EPA-600/2-76-249b September 1976 Environmental Protection Technology Series CHARGED DROPLET SCRUBBER FOR FINE PARTICLE CONTROL: PILOT DEMONSTRATION Industrial Environmental Research Laboratory Office of Research and Development U.S. Environmental Protection Agency Research Triangle Park, North Carolina 27711 ------- RESEARCH REPORTING SERIES Research reports of the Office of Research and Development, U.S. Environmental Protection Agency, have been grouped into five series. These five broad categories were established to facilitate further development and application of environmental technology. Elimination of traditional grouping was consciously planned to foster technology transfer and a maximum interface in related fields. The five series are: 1. Environmental Health Effects Research 2. Environmental Protection Technology 3. Ecological Research 4. Environmental Monitoring 5. Socioeconomic Environmental Studies This report has been assigned to the ENVIRONMENTAL PROTECTION TECHNOLOGY series. This series describes research performed to develop and demonstrate instrumentation, equipment, and methodology to repair or prevent environmental degradation from point and non-point sources of pollution. This work provides the new or improved technology required for the control and treatment of pollution sources to meet environmental quality standards. EPA REVIEW NOTICE This report has been reviewed by the U.S. Environmental Protection Agency, and approved for publication. Approval does not signify that the contents necessarily reflect the views and policy of the Agency, nor does mention of trade names or commercial products constitute endorsement or recommendation for use. This document is available to the public through the National Technical Informa- tion Service, Springfield. Virginia 22161. ------- EPA-600/2-76-249b September 1976 CHARGED DROPLET SCRUBBER FOR FINE PARTICLE CONTROL: PILOT DEMONSTRATION by W. F. Krieve and J. M. Bell TRW Defense and Space Systems Group One Space Park Redondo Beach, California 90278 Contract No. 68-02-1345 ROAPNo. 21ADL-043 Program Element No. 1AB013 EPA Project Officer; Dale L. Harmon Industrial Environmental Research Laboratory Office of Energy, Minerals, and Industry Research Triangle Park, NC 27711 Prepared for U.S. ENVIRONMENTAL PROTECTION AGENCY Office of Research and Development Washington, DC 20460 ------- ABSTRACT This report presents the results of a successful Charged Droplet Scrubber (CDS) pilot demonstration of coke oven emissions control. It includes a description of the design, installation and checkout of the demonstration system. The CDS is a device that uses electrically sprayed water droplets, accelerated through an electric field to remove particulate material from a gas stream. The pilot demonstration was a continuation of the laboratory and bench scale studies for application of the CDS to fine particle control. The pilot demon- stration system included, in addition to the CDS, the ducting, flow transitions and blower necessary to circulate process gas through the CDS. The test was performed at the Kaiser Steel Company coke oven facility, Fontana, California. A large fraction of the coke oven emissions were submicron and composed of carbon particles and hydrocarbon aerosol. After the system check- out was completed during which the CDS operating parameters were established, the demonstration test series was performed. Results of the demonstration test indicates that the CDS is an effective pollution control device for con- trolling coke oven stack emissions. This report was submitted in fulfillment of Contract Number 68-02-1345, by TRW Defense and Space Systems Group, Preliminary Design and Fluid Systems Department, under sponsorship of the Environmental Protection Agency. Work was completed as of March 1976. ------- ACKNOWLEDGMENTS The support of Kaiser Steel Company, Fontana, California personnel is acknowledged with sincere appreciation. Special thanks is extended to Messrs. C. Kingsbury and S. Vitt of the KSC Engineering Department for their assistance. IV ------- CONTENTS Page No. I. CONCLUSIONS 1 II. INTRODUCTION 2 III. DEMONSTRATION TEST DESIGN AND ASSEMBLY 5 IV. DEMONSTRATION TEST CHECKOUT AND STARTUP 16 Design Verification Tests 16 Startup 18 V. DEMONSTRATION FIELD TEST 20 Sampling Procedures . ' 20 Screening Tests 24 Matrix Tests 25 Development Tests 28 Long Duration Tests 29 VI. DISCUSSION 32 Methods of Analysis 32 Process Characterization 32 Results of Analysis 34 APPENDIX A APPENDIX B APPENDIX C ------- LIST OF FIGURES Figure No. Page No. 1 Kaiser-Fontana Coke Oven Battery A Stack 5 2 CDS Structural Configuration 8 3 CDS Housing with Header Electrode Support Insulator Column Exposed 9 4 CDS Inlet Turning Section 10 5 Pipe Nest Component Layout and Electric Circuit Schematic 12 6 Plan View of CDS Pilot Demonstration System .... 14 7 Flow Distribution at 2.80 m/s Average Velocity ... 17 8 Modified E.P.A. Sampling Train with In-Stack Cascade Impactor 22 10 Gas Flow Velocity Distribution After Completion of Test Series 30 11 Gas Maldistribution Sensitivity to Specific Collecting Area-RMS Velocity Profile Vs Average Velocity 31 12 Coke Oven Flue Gas Process Variability, the Relationship of Inlet Dust Load to Particle Size . . 33 13 Inlet and Outlet Size Distributions at Low Inlet Load 35 14 Inlet and Outlet Size Distributions at Low Inlet Load 36 15 Inlet and Outlet Size Distributions at Low Inlet Load 37 16 Inlet and Outlet Size Distributions at High Inlet Load 38 17 Inlet and Outlet Size Distributions at High Inlet Load 39 . 18 Efficiency Correlation, Total Unedited Data Set With Continuous Wall Wash 40 vv ------- LIST OF FIGURES (CONTINUED) Figure No. Page No. 19 Efficiency Correlation, Total Unedited Data Set Without Wall Wash . . . 41 20 Effect of Gas Flow Rate on Overall Collecting Efficiency . . . 44 21 Insensitivity of Efficiency to Second Stage Electrode Voltage 46 22 Fractional Efficiency Data for the Higher Inlet Loadings 49 vii ------- LIST OF TABLES Table No. Page No. 1 Coke Oven Exhaust Stack Gas Composition 5 2 Kaiser Steel Water Sample Analysis . 6 3 CDS Design Summary . 7 4 Summary of Sampling Procedures Employed 21 5 Test Matrix Parameters 26 6 Suspect Kaiser CDS Data 43 7 Summary of Regression Analyses 47 8 Kaiser Observed CDS Stack Opacities 51 vi i i ------- I. CONCLUSIONS The Charged Droplet Scrubber (CDS) demonstrated effective control of the emissions from a coke oven battery over widely fluctuating process conditions. Particle removal efficiencies up to 95% were measured and were an increasing function of the time averaged particle loading. Improvements in the gas distribution internal to the equipment should result in additional improvements in collecting efficiency. The average inlet particulate load varied between 0.05 and 0.33 gr/ dscf, associated aerodynamic mean diameters varied between 0.4y (hydro- carbon aerosol) and 1.5y (carbon black). The most sensitive design variable affecting efficiency was the gas volume flow rate through the equipment. Low total energy and water consumptions, 0,8-1,2 watts/acfm and 0.8-1.0 gal/1000 acfm, respectively were demonstrated over most of the test conditions. Operation of the CDS with intermittent (8 hour cycle) collector plate over sprays was adequate for deposit control. The CDS gas discharge was not saturated during nominal operating conditions. -1- ------- II. INTRODUCTION This report describes the results of a pilot demonstration of the Charged Droplet Scrubber (CDS) to control coke oven flue gas particulate emissions. Heretofore, it was the general concensus of the industry that there was no suitable control technology for this process because of the wide process fluctuations. Emissions consisted of varying relative concen- trations of submicron sticky hydrocarbon and micron sized high conductivity carbon black. The CDS applies electrohydrodynamically sprayed water drop- lets to remove particulate material from a gas stream. The droplets have a size in the range of 60 to 250 ym in diameter and have a surface charge density near that allowed by surface tension forces. The charged droplets are accelerated through the gas stream by an applied electrostatic field. The objectives of the pilot demonstration were to verify the appli- cability for removing fine particles from an industrial effluent stack, to determine the influence of CDS operating variables on performance and behavior of the CDS under long term operation. The demonstration unit was to be of sufficient size, at least 17,000 m3/hr (10,000 acfm), to adequately describe the behavior of a full size unit. The emission source was to be characteristic of those requiring control with a relatively large fraction of particulate material in the submicron range. The pilot demonstration phase is a continuation of the laboratory and bench scale studies for the application of the CDS to fine particle control. These studies included an analysis of the particle removal interactions between particulate material and charged droplets. The laboratory scale studies included the determination of charged droplet characteristics under system operating conditions. The results of these studies were used to verify some of the models used in the fine particle removal analysis. The particle removal efficiencies of a small size CDS operating under simulated process conditions were measured during the bench scale studies. The results of these tests indicated that the CDS should be effective for fine particle control and was sufficiently devel- oped for a pilot demonstration test. The laboratory and bench scale studies are reported in Reference 1. -2- ------- A pilot demonstration phase was started at the conclusion of the first phase. The tasks of the pilot demonstration phase are: t Site Selection and Hardware Preparation • Pre-Delivery Design Verification Tests • Pilot Demonstration Field Test • Summary and Conclusions The site selection and hardware preparation task covered all of the back- ground work necessary for conduction of the demonstration program. The selected site was to provide an environment consistent with the objectives of the program. It must be adaptable for installation of a CDS and provide the required utilities within a reasonable time span. An acceptable working agreement with the organization providing the site was necessary to allow successful completion of the demonstration test. A test matrix was developed as part of this task to delineate the CDS operating parameters that would be varied during the test phase. The hardware preparation portion of the first task included the design and fabrication of the CDS, duct work and supporting structure for the demon- stration unit. All interfacing requirements between the site and demon- stration unit were established. Any special auxilary equipment was identified and either purchased or fabricated. Prior to delivery to the test site, the CDS was subjected to design and oper- ational verification tests. These tests of Task 2 were designed so that the CDS would be operational when delivered to the test site with a minimum of rework or retrofitting. The checkout of the CDS included high voltage component electrical breakdown tests, electrode water flow distribution and water flow rates, and pressure and power requirements. Task 3, Pilot Demonstration Field Tests, covers the on site hardware assembly, checkout and operational testing of the CDS. Hardware checkout and parameter checks such as gas flow distribution proceeded simultaneously with the assembly. This would allow any measurements or modifications to be made with a minimum of reassembly. Final checkout of the unit was made after complete assembly -3- ------- and connection to the process stream. The testing includes screening tests to determine the operating parameter levels of the CDS for the test matrix. Following the performance demonstration tests is a long duration test, 500 hours, to identify maintenance requirements and potential failure modes. The final task, of which this report is a part, includes documentation of the design, fabrication, assembly and checkout of the demonstration unit and a summary of the test results. -4- ------- III. DEMONSTRATION TEST DESIGN AND ASSEMBLY The site selected for the CDS pilot demonstration test was a coking oven battery exhaust stack at Kaiser Steel Co. in Fontana, California. A photo- graph of the stack site is shown in Figure 1. The emissions as originally specified consist of hydrocarbon aerosol and carbon particles of which 42 percent by weight are less than one pm in diameter and 96 percent by weight are less than ten pm. This particle size range was consistent with the requirements for the demonstration test. The nominal effluent temperature is 400°F, and the gas composition as measured in May of 1974 is shown in Table 1. Figure 1. Kaiser - Fontana Coke Oven Battery A Stack Table 1. Coke Oven Exhaust Stack Gas Composition Constituent Volume Percent CO, H20 CO S00 NOX as 4.2 12.6 15.0 95 ppm 300 ppm 102 ppm -5- ------- An existing port used during previous experiments allowed access through the stack wall. The necessary utilities were available either at the stack lo- cation or could be supplied through existing piping and conduit. There were two water sources available to use in the experiment. One was recycled industrial water and the other domestic or fresh water. Average values of the water properties taken during the months of June and August 1974 are shown in Table 2. Table 2. Kaiser Steel Water Sample Analysis Source Conductivity Hardness pH ymho/cm ppm Industrial 6/74 572 137 7.51 8/74 635 152 8.33 Domestic 6/74 214 58 8.45 8/74 169 57 9.02 Either of these water sources, based on the tabulated properties, could be used without conditioning in the scrubber. The particulate material properties and loading varied with time during the coke oven operating cycle. A typical cycle included loading an individual oven with coal, discharging coke, and coking with all ovens in the battery closed. The time period during which coal was charged and coke discharged constitute a high stack emission condition. A nominal operating period occurs when all ovens are closed. The previously measured particle loading was 290 mg/m3 (0.1 gr/ft3) and the stack Ringlemann 5 during a high emission condition. It was found during the test phase of this program that under these conditions particle loading could be as much as a factor of 3 higher. Under normal operating conditions, the particle loading is of the order of 1.37 mg/m3 (0.006 gr/ft3) and the stack Ringlemann 0 to 1. These sufficiently higher inlet loads resulted in a requirement to derate the equipment flow capacity to achieve higher overall collection effi- ciencies. As will be discussed later, this resulted in a substantial gas maldistribution problem and some loss in efficiency. -6- ------- The Charged Droplet Scrubber to be used on the program was purchased from the Development & Applications Division of TRW Inc. The unit was a cost-effective modified version of a Model 300 with a capacity of 51,000 m3/hr(28,500 acfm) at 1.83 m/s (6 ft/s) gas flow rate. An iso- metric sketch of the CDS is shown in Figure 2 and a photograph of the delivered unit in Figure 3. A design summary is shown in Table 3. The scrubber contained three electrostatic spraying stages arranged in series with parallel collecting plates on 0.127 m (5 inch) centers. It had 19 collecting modules. The scrubber structural members and collector plates were fabricated from mild steel. Material thickness of the scrubber housing and collector plates was 20.3 mm (0.080 inches). Although the compatibility problem of mild steel in the stack gas environment was recog- nized, it was felt that the material would maintain its integrity during the test period. The electrodes which distribute high voltage and water were fabricated from type 316 stainless steel tubing. Each electrode stage was supported from parallel main headers mounted exterior to the gas pass- ages and supported on corner insulator posts. A series of 12 doors, 6 on each side, was provided to allow access to the electrode headers and electrodes. Inspection and alignment of all electrodes on the three stages and the collector plates could be made through these doors. Table 3. CDS Design Summary • Three high voltage scrubbing stages with 0.127 m (5 in.) collector plate spacing. • Nineteen collecting modules, 3.05 m (10 ft) long. • Flow cross sectional area, 7.36 m2 (79.2 ft2). • High voltage electrode, type 316 stainless steel tubing 190 mm (0.75 in.) diameter, flattened to 0.127 mm (0.5 in.) • High voltage electrodes contained 67 spray tubes each on 44.5 mm (1.75 in.) centers. • Spray tubes, titanium with a 12.7 mm (0.050 in) O.D. by 1.52 mm (0.006 in) wall and protruding 25.4 mm (1.0 in) from the electrode. • Collector plates 3.05 m (10 ft.) long by 1.83 m (6 ft.) high by 20.3 mm (0.080 in) thick mild steel. • Wall wash system covering each collecting surface. -7- ------- COLLECTOR PLATES I CO FLANGED GAS EXIT ELECTRICAL UPPER SECTION HIGH TENSION SUPPORT HOUSING GAS DISTRIBUTION LOWER SECTION FLANGED GAS INLET HIGH TENSION WATER HEADERS SLURRY DISCHARGE HIGH TENSION CONNECTOR PANEL OVERFLOW MAINTENANCE PLATFORM Figure 2. CDS Structural Configuration ------- GAS EXIT HEADER ELECTRODE COMPARTMENT ACCESS DOORS INSULATOR COMPARTMENTS HEADER ELECTRODE SUPPORT INSULATOR Figure 3. CDS Housing with Header Electrode Support Insulator Column Exposed ------- A turning section, shown in Figure 4, was also part of the scrubber unit. This section was designed to accept a horizontal flow duct, deflect the flow into a vertical direction and distribute it uniformly over the scrubber cross section. The turning section contained right angle vanes to deflect the gas flow and moveable baffle elements to distribute the flow. „ MATING FLANGE TO CLEANING SECTION SUPPORT FOR ADJUSTABLE ANGLE IRON FLOW Figure 4. CDS Inlet Turning Section -10- ------- Electrode feed water is brought up to high voltage through a long length of non-conducting pipe. The piping is sized to restrict the leakage current through the water to an acceptable level when high voltage is applied at the electrode end and the water supply end grounded and to have a tolerable pressure drop. The pipe lengths are supported or nested as close as possible without developing electrical breakdown gradients between the lengths to minimize the containment volume. The pipe nest was enclosed in a sealed housing separate from the scrubber housing. Copper tubing, extending through penetration insulators in both the scrubber shell and pipe nest housing, was used to connect both the water and high voltage to the scrubber electrodes. This pipe nest was formed from thirteen 1.83 m (6 ft.) lengths of Schedule 80 polypropylene pipe interconnected with pairs of elbows. Isolation resistance between the stages was provided through three nominally 0.38 m (15 in) lengths of 6.35 mm (.25 in) I.D. by 6.35 mm (.25 in) wall Tygon tubing. The tubing was used to complete the water flow path from the end of the pipe nest to the copper tube extension of the individual stages. The high voltage input was connected upstream of the three flow distribution tubes. Therefore, the current path to each stage was through the water in the connecting tubes. The water resistance provided the electrical isolation between stages. A schematic of the pipe nest and electrical circuit is shown in Figure 5. A purge fan system was installed on the scrubber to provide an ambient air flow over the stage electrode support and penetration insulators. This air flow reduced direct contact of the insulators with the process stream gas eliminated fouling. The air purge fan had a design capacity of 1020 m3/hr (600 CFM) at a 25.4 mm (1.0 in) water pressure differential. The purge fan and duct was located external to the scrubber housing with the inlets to the scrubber on the top end of each support insulator housing. The high voltage source was a transformer/rectifier set with a maximum output of 75 kV at 400 ma and a single phase 480 v Input. The output voltage from the transformer/rectifier set could be controlled either manually with a potenti- ometer or by an automatic control circuit using an arc rate sensor for feed -11- ------- WATER LEAKAGE CURRENT MONITOR A CARBON STEEL ELL x AND STREET ELL * Fll TF» TAPArlTriB INLET J_ ' • . y$ • \ V f HIGH VOLTA \ I ARC EXIINCU|SHINC CAPACITOSS (3 PL/ > POLYPROPYLENE PIPE / *?' ? / ^ 1 1 ^ : o c ' H ' ; ^=a ^L'r^ TYGON TUBING ^ C | • (3 PLACES) 1 POTENTIAL DIVIDERS ' . (3 PLACES) ^^^n— f ||- VOLTAGE 1 r^ r MONITORING ^ i ( LEADS -i N }-"• (3 PLACES) JL I | PENETRATION ^^ |] INSULATORS •" ; /3 pi ACES1 WATER A PIPE NEST COMPONENTS ' ' LEADS TC HIGH VOLTAGE INPUT f -j, li *tr- m i T MO POWER STAGES GE LEAD ICES) TYGON TUBING (3 PLACES) FILTERING T CAPACITOR -ir ' ' ' ^- ARC EXTINGUISHING ^^"^ CAPACITORS POWER TO ELECTRODES ^^-^ (3 PLACES) ^^^ (3 PLACES) MONITOR J=*» — CAPACITOR DROPPING i^~ POTENTIAL DIVIDER II' WATER SUPPLY ISOLATING RESISTANCE "i /^RESISTANCE % (3 PLACES) 1 \ / <3PLACES) ' t ' — X°^!/"ONIT0' vVAWWAWAW ^ AAWA-J^ 1 • f LEAKAGE CURRENT ^ "T J -Jr SHUNTING RESISTANCE ^* -±- 4 • . . STAGE ISOLATING ^ - I , • RESISTANCE • I : n n f,r^\ ,rt^nnnnn^ • ™/- ... *. • > PIPE NEST ELECTRICAL CIRCUIT Figure 5. Pipe Nest Component Layout and Electrical Gfrcuit Schematic -12- ------- back control. The voltage when in the automatic mode would be either the maximum of the transformer/rectifier set or that required to maintain a pre- set arc rate. An rf coil located within the scrubber housing was used to sense the arcs. The operating voltage on the electrodes was the output of the transformer/rectifier set minus the voltage drop across the stage isolating resistors. Voltage on each stage was monitored through a potential divider located on the input to the stage. The total scrubber current was monitored directly on the ground return leg of the transformer/rectifier. Leakage current through the pipe nest was monitored with a current shunt near the pipe nest ground end. These monitoring circuits are shown in Figure 5. The structural support and ducting design along with the final working drawings for the CDS installation was made by Trade West of Corona, California. Trade West was the manufacturer of the CDS. A top view of the scrubber experimental layout is shown in Figure 6. Kaiser Steel Manufacturing Division performed the structural and ducting fabrication and installed all components of the demonstration test unit. A portion of the ducting used was salvaged from the previous experiment at the stack location. These items included a 1.52 m (5 ft) diameter flow control damper and a 50 horsepower blower used for draw- ing gas from the stack and exhausting it through the scrubber. The blower had a capacity of approximately 68,000 m3yhr(40,000 ACFM) at a draft of 100 mm (4 in) of water. The nominal vacuum in the stack at the position gas was withdrawn was 38 mm (1.5 in) of water. The ducting from the stack to the blower turning and transition section was 1.52 m (5 ft) in diameter. The straignt duct section between the elbow at the stack and the inlet to the blower transition was approximately 3.66 m (12 ft) long. It was angled approximately 20° relative to the horizontal to accommodate the difference in elevation between the ground level blower inlet and the stack port. Gas stream pre-cooling water spray nozzles were located 0.3 m (1 ft) up stream of the blower transition. The pre-cooling system con- tained 10 spray nozzles located on the upper 300° section on the duct periphery. CDS inlet gas stream sampling ports were located in the duct straight section 2.9 m (9.5 ft) downstream of the elbow from the main stack. The two sampling ports were located on the top and side of the straight duct section. Each port was equipped with an extension structure to support the sampling trains. The position of the pre-cooling system and inlet sampling ports are shown in Figure 6. ------- TRANSFORMER LADDER 440V-150 AW ELECTRICAL PANEL Figure 6. Plan View of CDS Pilot Demonstration System ------- The flow control damper was bolted directly to the stack outlet flange. It was not designed for complete flow cut-off; therefore, during scrubber non- operating periods, there was a back flow of ambient air through the scrubber into the stack. The damper was pre-set manually to control the flow rate through the CDS during test operation. Because of the fan capacity, the damper was only partially opened during CDS operation. A flow scoop extended into the stack to assist in diverting gas flow into the scrubber ducting system. The scoop was a half section of a 1.52 m (5 ft) diameter pipe. It was angled at 15° downward from the horizontal into the stack and extended inward 3.05 m (10 ft). Although the scoop may not have been necessary to insure adequate flow through the CDS because of the fan capacity, it would help provide a more representative stack gas sample. The transition section between the blower and scrubber turning section con- tained four equally spaced straightening vanes to assist in distributing the gas flow across the scrubber cross section. Gas sampling ports were located in each of the five flow passages formed by the vanes and transition walls. These sampling ports were used by APT, Inc. of San Diego, California who performed the designated EPA sampling tests. The scrubber inlet gas temperature monitoring thermocouple was located in this blower transition section. The outlet transition section of the CDS was a quadrihedron, truncated by 0.91 m (3 ft) diameter vertical exhaust stack. The exhaust stack was 3.05 m (10 ft) long. Its exhaust plane was 12.2 m (40 ft) from ground level. Three sampling ports, located in a horizontal plane, were in the exhaust stack, three feet below its exit plane. Two of the ports were at right angles and the third was in their enclosed quadrant. This port arrangement allowed simultaneous outlet sampling by the APT group during a test. A single overhead catwalk was incorporated into the scrubber support structure for access to the outlet sampling ports. Temporary scaffolding was erected for access to the CDS header electrode compartment doors and the vertical inlet sampling port. The temporary scaffolding was also used during scrubbing installation for access to various areas for alignment and checkout. -15- ------- IV. DEMONSTRATION TEST CHECKOUT AND STARTUP The fabricated equipment was first assembled and subjected to factory functional electrical and hydraulic tests. After installation additional dynamic tests were performed and modification work identified as described below. Design Verification Tests The CDS unit was subjected to design verification tests prior to delivery to the installation site. These included electrical breakdown tests of the high voltage components, both at the scrubber support and penetration insulators and within the pipe nest. Electrode and wall wash water flow distribution were also visually observed. The high voltage isolation tests indicated that the electrical isolation design was capable of withstanding the peak voltage stresses expected during operation. The pipe nest provided an acceptable isolation from ground with leakage currents in the range of 10 to 12 percent of the total scrubber current. The arc rate between the spray tubes and collector plates appeared to be excessive at the CDS operating voltage range. A part of the arcing problem was due to collector plate misalignment. There was adequate collector plate ad- justment to allow proper alignment; however, realignment of the plates was deferred until after installation at the test site. The water spray pattern of both the electrodes and wall wash were adequate for proper scrubber operation. The wall wash gave no indication of the impending problems that were to be encountered later in the program. The nozzles maintained a steady spray pattern on the collector plates with no splashing. The wall wash was operated on domestic water without filtering. After completion of these tests, the CDS was shipped to the test site for installation. Typical profiles of the gas flow, taken after the distribution baffles were adjusted, are shown in Figure 7. The profiles at an average velocity of 2.70 m/s (8 fps), are marginally outside the design requirements of the scrubber. As the anticipated operating average gas velocity was between 1.5 and 1.7 m/s, no further gas velocity adjustments were attempted at this time. It is necessary to maintain the best possible uniformity in gas flow distribution across the CDS cross sectional area to achieve -16- ------- GAS FLOW VELOCITY (M/S) — • tO NJ CO CO CO CQ c VI rh O 3 0) ft) -S O) (Q fD ft) O O I 5 C m — 5 ? I s S O m 5 5 —< ^ c •< z 1 + NJ NJ*. N Oi — O 393? S 8 s 8 —i NJ Ni CO CO CO 8 8 3 5 k 8 —• tO IO CO CO CO Cn o * z 00 pn CO in 00 — • NO NJ CO CO CO s s s o o —i » o CO m O 5 z CO DISTANCE FROM INLET END OF TURNING SECTION (M) ------- high particle removal efficiencies. Particle removal efficiency has a non-linear inverse dependence on gas flow rate; therefore, large variations in flow velocity in the scrubber cross section will result in a reduced efficiency. The high voltage was applied to the electrodes for one brief period prior to completion of the installation to check the integrity of the high voltage isolation. No sustained high voltage operation could be made until after completion of the installation when all high voltage elements were completely enclosed. After installation was complete, specific high voltage tests and adjustments were made. The tests included locating potential breakdown paths in the isolation, determining maximum operating voltages on the electrodes and monitoring corona and leakage currents. The adjust- ments included setting the arc rate controls for automatic mode operation and establishing the water tube lengths which served as the dropping resis- tors to the stages. Several other site specific, minor operating problems occurred due to the inadvertent hookup of the equipment to the wrong water source. Feed water filter plugging due to abnormally high suspended solids concentrations and inadequate supply pressures were corrected by hookup to the domestic water supply. Also, at this time the OEM tygon tubing in the pipe nest was replaced with polypropylene pipe as recent commercial experience in Japan indicated this to be a more stable material in a high electrical field gradient and temperature environment. Startup The CDS was then put on process and marked change in high voltage electrical stability noted as compared to operation with ambient air. Two effects were noted which potentially could have deteriorated collecting efficiency: • Abnormally high spark rate in the first electrostatic spraying stage. t Sustained arcing without sufficient quenching, primarily in the first stage. -18- ------- The high electrical sparking resulted from the presence of a low mobility particle space charge, primarily within the first or inlet spraying stage. The current from an electrode will decrease with increasing low mobility space charge resulting in the first stage having the smallest voltage drop across its isolating resistor. Under these conditions the first stage controls the operating voltage on the other stages. The dropping resistors to each stage were resized so that each successive downstream stage had a higher nominal operating voltage. The CDS would operate in a self-extinguishing arcing mode, except during periods of heavy particle loading. When the particle loading was heavy some arcs appeared to become sustained burning arcs. These sustained arcs, actually a series of arcs, resulted from reignition of the plasma left from the previous arc. The sustained arc mode was eliminated by changing the recharge rate, i.e., adding capacitance to each stage. The gas temperature conditioning spray system was close coupled to the blower in order to position the sampling ports as far as possible from the stack outlet elbow. Unvaporized water droplets were ingested into the fan, but were demisted by the fan blades. Although this did not create an operating problem, the water mass balance was more difficult to estimate. The unvaporized water was drained from a port in the blower inlet trans- ition and the net water flow vaporized was determined measuring both the preceding and overflow water flow rates. The precooler was capable of reducing the gas stream temperature up to 80 C (175°F). -19- ------- V. DEMONSTRATION FIELD TEST The objective of the field test was to determine the operating characteristics and particle collecting efficiency of a CDS under actual process conditions as a function of operating parameter levels. The parameters included: • Electrode voltage t Gas stream velocity • Electrode water flow rate • Electrode polarity Sampling Procedures Particle removal efficiency was determined by isokinetically and simultaneously measuring the inlet and outlet particulate material loadings during a test run. Three different sampling procedures were used to measure particle collection efficiency. During the statistically designed tests both the EPA Method 5 procedure (Reference 2) for overall efficiency and a modified procedure using a Washington State impactor for fractional efficiency were employed. Additional testing was performed with a shortened tes" period using EPA Method 5. The three procedures are described in more detail in Table 4 and the modified APT sampling train shown in Figure 8. Greased aluminum substrates were used in the impactors to prevent particle bounce and minimize wall losses. The gas stream temperature and kinetic pressure head were measured at each sampling point with the thermocouples and S-pitot tubes on the probes. These values were integrated over the duct areas to determine mean temperature and volumetric flow rates. The temperature monitored at the outlet sampling port corresponded to the outlet temperature of the CDS. The temperature measured at the inlet sampling port was near that of the gas stream in the coke oven battery main stack. The inlet gas temperature to the scrubber was measured with a thermocouple located down- stream of the gas precooler and blower. At the CDS inlet, eddy mixing and condensation in the pi tot tube was evident indicating negative velocity heads and recirculating gas flow. The best one point sampling location was used during the impactor runs. The eddy mixing would indicate that the inlet gas velocity average and the gas flow rate (volume/time) are questionable -20- ------- TABLE 4 SUMMARY OF SAMPLING PROCEDURES EMPLOYED i ro Method 1. EPA #5 2. EPA #5 3. Modified EPA #5 Equipment Joy Emission Analyzers Washington, Mark III Impactor Sample Location Inlet Outlet Circular Circular Duct,Up- Stack Stream of Fan Rectang- Circular ular Duct, Stack CDS Inlet Number of Sample Points Inlet Outlet 32' 32" 16-32^ 16-32' Sample Period Min. 90-120 Organ- ization TRW 30-90 TRW 30-45 APT Notes 'Performed along two radial traverses orthogonal to each other. 2, Performed along one or two radial traverses, sometimes on a coarser grid. ------- i ro ro i CASCADE IMPACTOR IMPINGER TRAIN STACK WALL I I ; I-CJEJB Ajj L. THERf--10.MET.ERS T J o > ROTOMHTP.R VACUUM GAUGE ORIFICE METER DRY GAS METER VACUUM PUMP Figure 8. Modified E.P.A. Sampling Train with In-stack Cascade Impactor ------- based on the inlet traverse. This also was the cause of poor gas distri- bution internal to the CDS. The outlet port was located three duct diameters downstream of the nearest disturbance and one duct diameter upstream of the stack outlet. Velocity traverses of the outlet revealed fully developed flow profiles. In addition to the CDS operating parameters, other observations which affect CDS performance were recorded from the power supply meters during a run. These included: t Electrode arc rate t Nominal electrode voltages • Nominal electrode and leakage currents • Voltage and current of the. electrode power supply The quantities associated with these observations varied during a course of a run. Ranges of values when appropriate are included with the tabulated data and are helpful in interpreting the test results. The CDS performance testing was divided into four series. These included: t Screening Tests • Variable Parameter Tests • Development t Long Duration Tests The screening tests were used to establish the parerneter levels for the parameter tost matrix. The test matrix runs constituted the najor portion of the testing sequence and the results were used to establish the CDS operating performance. The development tests were performed by the TRW division (DAD) supplying the CDS and the results are presented in this report. These tests were performed to obtain CDS performance data under specific process conditions and to determine means of improving the device's performance. The DAD tests were performed during and after the test matrix sequence. A long duration test of 500 hours was scheduled to start after completion of the test matrix runs. This test was included in the program to identify CDS maintenance schedule requirements and potential failure modes. -23- ------- The approved test matrix was drafted during the installation phase of the program. The matrix was based on a fractional factorial, two-level design for five independent variables. Screening Tests A screening test was first performed to identify several of the parameters and their levels. The following conclusions were drawn from the screening test (see Screening Test Summary, Appendix A, Table 1-A). t Positive polarity resulted in unstable, high voltage operation and was eliminated as a test variable. • Insufficient residence time for precooler droplet evaporation resulted in carry-over into the fan. • Considerable reentrainment of the collector plate auxiliary wash system water spray resulted in atypi- cally high particle outlet loads. • Extremely variable gas inlet conditions were observed and measured which sometimes exceeded the original design criteria (240 mg/Nnr*) on a time averaged basis and were significantly higher during part of a test period. t Electrode operating voltages (31 kv) were significantly lower than the tests with ambient air (36-38 kv). Based upon the above a fractional factorial design blocked with respect to with and without wall wash was adopted. All tests were at negative power supply polarity with manual voltage control. A nomenclature was derived during the screening tests to describe the "effluent from the coke oven battery stack. The main coke oven stack description which evolved was: Normal Atypical Black Gray White The condition could be identified also by observing the scrubber arc rate and electrode voltages. During normal operation, the stack effluent was • -24- ------- clear. The CDS operated at its pre-set voltage with a low, less than 100 arcs/min arc rate. During an abnormal condition, the stack effluent appeared black, various shades of gray and white and high electrode arc rates were measured, up to 1000 arcs/min. For periods of up to 10 minutes during black stack conditions, the spray pattern on the first stage and intermittently on the second stage would collapse. The scrubber operated normally during gray stack conditions with arc rates up to 350 arcs/min. During white stack operation, the scrubber arc rate was very sporadic, less than 250 to in excess of 500 arcs/min. Derating the gas velocity 20% substantially improved the electrical operation stability. MATRIX TESTS The matrix tests are designed by a letter and number series of the form TM-XXX-XXN where the X's are digits. The last two digits are used to identify the test relative to the run number. The first three digits correspond to the sequence in which the test was run during the matrix test series. The operating parameter levels established during the screening tests are shown in Table 5. Levels for each parameter were the same within both the wall wash and no wall wash blocks except voltage. High level voltages were selected to conform to conditions of about equivalent spark rate, low level 4-5 kv lower. A fixed damper opening was used to establish the volumetric flow rate for the test runs. The nominal flow rate at different degrees of damper opening was calibrated with pi tot traverses at the sampling ports. The actual gas flow rate changed during and between test runs because of variations in the main stack draft which coincided with the coke oven operating cycle. The damper positions determined during the screening tests were 5th notch for the low level and the 6th for high level. After start of the matrix tests, abnormal conditions were encountered that could not be handled by the scrubber at 6th notch operation. This level was subsequently changed to Notch 4. -25- ------- Table 5. Test Matrix Parameters Electrode Voltage A Gas Flow Rate B Wall Wash AQ = 31 kV A] = 35 kV B = B, = No Wall Wash 33 kV 38 kV 4th notch (Damper Setting)3 5th notch Electrode Water Flow Rate C Pre-Cool ing Water Flow Rateb D CQ = 12 gpm C, = 16 gpm D =3.75 gpm for B o o = 4.50 gpm for B, D.| =-5.00 gpm for B = 6.00 gpm for B, a. The damper setting referenced to clamping notches on handle track. First notch is closed position. b. The actual pre-cooling water absorbed by the gas is the dif- ference between the set flow rate, D, and the quantity measured in the overflow. The first matrix test series runs included the block with wall wash and are numbered 9 through 16 in the test matrix. The results of these tests are summarized in Appendix A, Table 2-A. The scrubber stack appearance can be characterized as containing a large quantity of entrained water droplets. The presence of these water droplets in the effluent and the location of the stack relative to the structures complicated Ringlemenn determinations. Average, high inlet load collecting efficiencies were about 87%. A screen mesh demister was installed in the stack to remove the entrained droplets, but plugged rapidly because of intermittent equipment operation which resulted in screen dryout. At the conclusion of the first series of matrix tests, a development test series was performed to investigate intermittent wall wash operation and automatic voltage control. Intermittent wall wash with adequate plete -26- ------- deposit control would allow higher voltage operation and eliminate the entrained droplets in the stack gas stream. It was determined during these tests that the scrubber could operate up to eight hours without wall wash and when used, required approximately 5 minutes of operation to clean the system. The wall wash cycle could coincide with periods of clean main stack without jeopardizing performance. There were no entrained droplets in the exhaust stack when operated without wash. Therefore, the second test block of the matrix, test numbers 1 through 8 were performed without wall wash. The voltage levels used for the tests were increased from those of the first block. The results of these tests are summarized in Appendix A, Table 3-A. with the exception of test number TM-016-03N, the particle removal efficiencies of this series exceeds the first. High inlet load average efficiencies were about 94%. The cause of the one low run may be attributable to pick up of rust particles in the sampling probe. This was the last test of the matrix run and at this point in time rust flakes from the ducting were noted in the scrubber stack. The outlet probe water wash contained 108 mg of material at com- pletion of the run and accounted for 61.7% of all material collected. The average weight of material collected in the water wash of the previous runs was 12.2 mg and accounted for 26% of the material collected. If this run were corrected, based on the sample distribution from previous tests, the particle removal efficiency would be approximately 80%. The main reason for the improved collection efficiency of the last test series over the first is attributed to the elimination of dirty, entrained water droplets. A more detailed analysis of the tests results and conclu- sions is presented in Section VI. A measure of the S02 and $03 removal was made during test number TM-015-05N. These measurements were made in accordance with EPA Method 8. The first impingers of the inlet and outlet sampling trains contained isopropyl alcohol to remove S03 from the sample gas and the second and third impingers of each train contained hydrogen peroxide for S02 removal. The inlet S02 concentration was determined to be 253.6 ppm and the outlet, 160.7 ppm. These values correspond to a removal efficiency of 36.6%. The inlet and outlet -27- ------- S03 concentrations were 3.00 ppm and 3.45 ppm respectively. The higher outlet concentration probably resulted from conversion of SO^ to SO- by ozone gen- erated in the droplet formation corona. DEVELOPMENT TESTS These tests, performed by DAD, were designed with specific objectives of determining means to improve the CDS performance, of further characterizing the process stream and of complementing the contractual test program. The sampling procedure and equipment used during these tests were the same as those used in the program tests with the exception that the sampling times at each point were shorter and in some cases only one traverse was used per run. The abbreviated test times were necessary so that a complete test would coincide with a normal or atypical stack emission period. The tests were conducted during a period between the two blocks of the matrix tests and after the matrix tests were completed. A summary of these tests may be found in Appendix A, Table 3-A. Included with these tests are the Ringlemann range estimates of both the CDS stack and the main stack. The opacity values are more significant for these tests because of their shorter duration and of their specific intent of being run during a limited range of main stack conditions. The tests were run in automatic voltage mode. During several of the tests, only two stages were operated. The object of the two stage operation tests was to determine the actual influence of staging on scrubber perform- ance. The main stack and CDS inlet particle concentration were measured simul- taneously during atypical and normal coke plant operations. The main stack had a particulate material loading of 764 mg/m3 (0,334 gr/scf) while the inlet to the CDS was 812 mg/m3 (0,355 gr/scf) at high emission load, A second run made during nominal operation indicated a main stack loading of 68.0 mg/m3 (0.0297 gr/scf) and a scrubber inlet loading of 97.7 mg/m3 (0.0427 gr/scf). As only six sampling points along one traverse axis were used in the 16 foot diameter main stack, the sample may not be representative. There is a possibility that particulate material is stratified along one side of stack. If any stratification in the main stream occurred, then -28- ------- the region from which the CDS flow was withdrawn could have a higher particle concentration. An access port was cut into the outlet transition section of the CDS after completion of the matrix tests to allow a gas stream velocity profile measurement across the CDS outlet. The results of these tests are shown in Figures 10 and 11. These velocity profiles have considerably more variation than those taken during the system checkout period and shown in Figure 7 and become progressively worse as the average velocity is decreased. At original design flow rates through the scrubber, the pressure drop of the baffles (25% open) appears to be sufficient. Post test calculations indicate that a 12% open area was required at the actual test flow rates. LONG DURATION TESTS The long duration test was started at the conclusion of the matrix tests. It was performed concurrently with additional development tests. The CDS was then operated for an additional eight hour day. Operating parameters of the CDS were varied during the sampling periods. However, during the extended daily operating period the parameters were adjusted to correspond to run number 2 of the matrix. The sixteen hour day scrubber operation was terminated during the second week because of operation problems that had developed which were attributed to the excessive collector plate corrosion. The arc rate was increasing with time and it was more difficult to maintain a pre-set operating voltage because roughened surfaces were initiating arcs. The total operating time during the long duration test was 100 hours. An additional 260 hours of operation were accumulated during the previous testing giving a total of 360 hours. -29- ------- MODULE NO. 3 1.40 1.20 1.00 0.80 0.60 0.40 0.20 0 S^ AVERAGE VELOCITY 0.88 M/S + 59% MAXIMUM DEVIATION - MODULE NO. ^7 1.40 1.20 1.00 0.80 0.60 0.40 0.20 0 O— > v H, ^v •x. >>- O ( S ^^ iX>^_ ^x^> ^ ^^ '^h^ "^ 0.5 1.0 1.5 2,0 2.5 3. DISTANCE FROM GAS FLOW INLET END (M) Figure 10. Gas Flow Velocity Distribution After Completion of Test Series -30- ------- I CO o* oe O uj £ u O UJ ISI 60 50 40 30 25 20 15 FINAL MODIFICATION _.-• 8.0 I INITIAL DESIGN POINT ® I AVERAGE GAS VELOCITY, fpi 5.0 4.0 3.0 2.5 2.0 0.08 .10 .12 .14 .16 .18 .20 .22 .24 .26 .28 .30 .32 .34 .36 SPECIFIC COLLECTING AREA, fiP/cfm iFigurell. Gas Maldistribution Sensitivity to Specific Collecting Area-RMS Velocity Profile Vs. Average Velocity ------- VI. DISCUSSION The test data developed from the statistically designed experiment previously discussed was used to estimate equipment performance over the range of the test parameters. However, efficiency changes due to process variability dominated over the efficiency changes affected by parameter level settings, thus, substantially weakening the statistical power of the experiment. Therefore, resort was made to data pooling, editing and regression analysis to develop the sensitivities of efficiency to the parameter levels. Methods of Analysis Three data sets were pooled, the APT and TRW original matrix test data, and the development test data. Preliminary data plotting indicated that the efficiency data with and without continuous wall wash were different, therefore, the data were initially classified into these two populations. The APT particle size distribution data was analyzed and it was determined that the efficiency variability was related to changes in particle aero- dynamic mean size. Low inlet loads corresponded to submicron high resis- tivity hydrocarbon particulate. Observations of the stack plume color under these conditions substantiated these condlusions. High dust loads corresponded to micron sized carbon particulate. Therefore, a regression analysis was first performed of efficiency vs. inlet dust load for the two segregated populations. This regression analysis was then used to identify statistical outliers and test anomalies. Judicious editing of this data finally evolved an analysis wherein the dominant parameter variables were identified and quantified. Process Characterization The APT emission and size distribution data was first investigated to determine if the process conditions could explain the variability in collecting efficiency. Figure 12 is a plot of mean aerodynamic diameter vs. inlet particle load. It can be seen that there is a correlation, lower inlet loads producing the smallest mean particle sizes. The mean particle sizes vary from about .4 microns to about 1.5 microns over the dust load range. Somewhere in the range of 200-250 mg/Nm3 the aero- -32- ------- SL TJ K oe. LLI LLJ Q 1 y S 1 O 2.0 1.5 1.0 0.9 0.8 0.7 0.6 0.5 0.4 100 150 200 300 INLET PARTICULATE LOAD, MG/dNm 500 700 1000 3 Figure 12. Coke Oven Flue Gas Process Variability, the Relationship of Inlet Dust Load to Particle Size -33- ------- dynamic mean diameters become more constant. Below this range mean size fluctuates widely. Examination of the particle size distributions plotted on log-probability paper, Figures 13-15, suggest that below about 220 mg/Nm3 the inlet particle size distribution is highly bimodal. At the higher inlet loadings and for most all outlets distributions, Figures 16 and 17, the distribution approachs a log normal distribution. The bimodal distribution is composed of a hydrocarbon aerosol having a mean size of perhaps 1 or 1 1/2 microns. This suggests a statistical approach to the data wherein the efficiency is first correlated to the inlet dust loads. Results of Analysis Regression analyses were first performed on the two data populations classified as with continuous wall wash and without. All of the test points from all three data sets were analyzed within each population. High correlation coefficients were obtained. The results of the regression analysis are shown on Figures 18 and 19. The data analyzed with the continuous wall wash was shown statistically to be significantly lower than the data without wall wash at a high confidence level. In both sets of data the efficiencies tend to assymtote and become nearly constant 3 at inlet dust loadings of about 220-260 mg/Nm. This corresponds to the inlet load at which mean aerodynamic diameter becomes constant. It would appear that the most statistical power would lie in the region of the q curves exceeding 220 mg/Nm . Efficiencies were about 4 1/2% higher for the population of data wherein the wall wash was not operated. As was previously discussed this was attributed to the elimination of the wash water spray droplet reentrain- ment problem which gave an atypically high outlet dust loading. Also the standard error of the residuals was substantial lower for the case of no wall wash, again reflecting the high variability of the outlet emission data when the wall wash was operated. The three data sets scattered randomly about the regression line, indicating they were all part of the same population. In order to determine the parameter effects an analysis of the residual deviations was made (i.e., deviation about the efficiency-inlet load -34-' ------- 4.0 E a. 8. ffi O y 5 Q O 2.0 1.0 0.5 0.2 SYM. POSITION O INLET A OUTLET LOADING mg/dNm3 182 22 I I I I I I 10 20 30 40 50 60 70 80 MASS PERCENT UNDERSIZE 90 95 98 Figure 13. Inlet and. Outlet Size Distributions at Low Inlet Load -35- ------- E a. o Q. ULJ fc < Q y Q O 6.0 5.0 2.0 1.0 0.5 0.2 SYM. POSITION O INLET A OUTLET LOADING o mg/dNm 201 23 I J I I I I 1 10 20 30 40 50 60 70 -80 MASS PERCENT UNDERSIZE 90 95 98 Figure 14. Inlet and Outlet Size Distributions at Low Inlet Load -36- ------- '6.0 5.0 2.0 a a. 1.0 o O 0.5 0.2 SYM. POSITION O INLET A OUTLET LOADING 3 mg/dNm 217 255 10 20 30 40 50 60 70 80 MASS PERCENT UNDERSIZE 90 95 98 Figure 15. Inlet and Outlet Size Distributions at Low Inlet Load -37- ------- < O a. < Z >- Q u < Z O O 0£ LU 6.0 5.0 4.0 3.0 2.0 1.5 1.0 0.8 0.6 0.5 0.4 0.3 0.2 SYM POSITION LOADING O mg/dNm O IN LET AOUTLET I I I I I 10 20 30 40 50 60 70 80 MASS PERCENT UNDERSIZE 90 95 98 Figure 16. Inlet and Outlet Size Distributions at High Inlet Load -38- ------- s. 85 te 1 a y < Q § 6.0 5.0 2.0 1.0 0.5 0.2 SYM POSITION O INLET A OUTLET LOAD mg/dNm3 508 23.1 I I I I I I I I I 10 20 30 40 50 60 70 90 MASS PERCENT UNDERSIZE I I 80 95 98 Figure 17. Inlet and Outlet Size Distributions at High Inlet Load -39- ------- 65. 165. 265. 365. 465. 565. 665. • 765. 865 PflRT IN Figure 18. Efficiency Correlation, Total Unedited Data Set With Continuous Wall Wash ------- 65. 165. 265 365. 465. 565. 665. PflRT IN Figure 19. Efficiency Correlation, Total Unedited Data Set Without Wall Wash ------- regression line). The parameters considered were inlet gas temperature, gas flow rate and voltage and interactions thereof. Analyses were per- formed after eliminating obvious statistical outliers and reviewing the data for test anomalies, Table 6. Generally, the outliers could be explained in terms of test anomalies particularly with respect to unstable electrode voltage operation or measurement procedure. For the case of the continuous wall wash the only statistically significant parameter identified was the inlet temperature. Increasing temperature slightly decreases efficiency. The data with the continuous wall wash system is atypical of the real potential of the CDS and is a situation that can be corrected by an improved design. Therefore, the remaining analyses were directed at analyzing the data without wall wash in an attempt to develop the efficiency sensitivities to the parameter levels. A detailed summary of the regression analyses may be found in Appendix C. The first analysis of the residual deviations for the data population without wall wash and incorporating edited data indicated an interaction between gas flow rate and inlet temperature. However, this data incorporated the low inlet dust loading tests with the highest degree of variability. The more steady process conditions on the assymtotic portion of Figure 18 suggests that more statistical power may be developed with this part of the data. Therefore, efficiency data greater than 90% or inlet loads •j greater than 227 mg/Nm were incorporated into a final data pool. A regression analysis was performed with first and second stage electrode voltages, inlet gas temperature and actual gas flow rate. The statistical analysis showed that gas flow rate was a highly significant variable having -4 •? a negative coefficient with a value of 2.9 x 10 %/nrVm, Figure 20. High gas velocities result in lower efficiencies. Over a 50% decrease in gas flow rate the efficiency only increased about 2%. This sensitivity is significantly less than that experienced in other pilot programs where the regression coefficients have been a factor of 2 higher. The relatively low sensitivity is attributed to the fact that the gas distribution grew progressively worse as gas flow rate was reduced. Post test velocity pro- files of three of 19 CDS modules were measured over a range of gas flow rates. A typical distribution is shown in Figure 10 and the rms error over the test velocity range shown in Figure 11. At a velocity of about 3 fps it is -42- ------- TABL2 6 SUSPECT KAISER CDS DATA Data No. 8 13 10 4 S-2 S-3 3N 12N 006 Point Source APT APT APT APT ' Screening Test Screening Test EPA EPA DAD COMMENTS Statistical Outlier Q p Outlier dP Outlier vs load Outlier vs load Outlier vs load Outlier vs load Outlier vs load Outlier vs load Outlier vs load on load vs on load vs on efficiency on efficiency on efficiency on efficiency 1 on efficiency on efficiency on efficiency Equipment Condition Voltage Wallwash Low voltage operation ( ~30KV) Low voltage operation ( ~30KV) .Upset 1st stage voltage Upset 1st stage voltage Positive polarity Arc control on 1st stage only Satisfactory Arc control on 1st and 2nd stages only 1st stage voltage collapse Yes Yes Yes Yes Yes Yes No Yes No Outlet sampling error. Measurement Anomally Position 1 APT 5 & 6th Stages-50% Plugged Inlet 4,10,18 APT Not 100% Simultaneous With Outlet, Inlet, Process Change Inlet 9 APT 6 & 7th Stages Wet Outlet 15 APT 3rd & 5th Stages, 20-30% Inlet Plugged Efficiency Effect Fractional Fractional and Overall Fractional Fractional -43- ------- V) c o £ -2 -3 -4 10 12 14 16 18 20 Measured Flow Rate sm3/m(xl03) 22 24 Figure 20 Effect of Gas Flow Rate on Overall Collecting Efficiency ------- substantially out of specification. The rms velocity error increased from 15% to 50%. The non-linear influence on velocity would therefore result in efficiency losses at low gas velocities (2.5 fps) estimated at between 2 1/2 and 3%. The increasingly poor gas distribution is attri- buted to the loss of pressure drop at the baffle system. Several regression analyses were attempted to bring out the effects of electrode voltage. The regression of the residual deviations was first attempted using the second stage voltage which is somewhat typical of the average voltage operation across all stages. As no correlation could be developed an additional analysis was conducted by introducing both the first and second stage voltages. It was felt that this would more typically reflect the first stage space charge effect on cleaning efficiency. Again, no influence was uncovered, Figure21. As can be seen the data fairly well scatters on both sides of the zero deviation line over a range of 33-41 kilovolts. When the voltage is pushed much beyond 40 kv greater statistical variability occurs which may be indicative of the high spark rate conditions. The insensitivity of voltage is surprising and it is attributed to the low gas velocity operation. It is hypothesized that the high space charge due to conducting carbonblack and water droplets and their correspondingly low mobility is affecting the ability of the high voltage to establish a suf- ficiently higher voltage gradient outside of the corona field. This effect would not be anticipated at higher gas velocities where the space charge is more evenly distributed through the equipment volume. A summary of the regression analyses discussed above may be found in Table 7. Further analyses did not result in any additional correlations. Based upon the above the particle size distribution data obtained in the APT test was analyzed to develop fractional efficiencies as a function of the aerodynamic diameter. Only those tests with no test or statistical anomalies and without wall wash were analyzed. The APT data were segregated into both high and low inlet loading conditions as previously discussed. The efficiencies at low inlet conditions (typically 180 mg/Nm^ to 220), Figure 22, are very similar for all three tests, Nos. 14, 16 and 19. Efficiency improves with the smaller aerodynamic diameters and reaches about 90% at 0.4 microns. This is atypical of other types of electrostatic and wet -45- ------- in c o 0 -1 -2 -3 -4 33 34 3T 36 37 Electrode Voltage (Stage 2) KV 38 39 40 41 Figure 21 Insensitivity of Efficiency to Second Stage Electrode Voltage ------- INDEPENDENT VARIABLES Inlet load, Residual Errors plus Test Parameters, T.°C Inlet load, Residual Errors plus Test Parameters, Q, — TABLE 7 SUMMARY OF REGRESSION ANALYSES DATA SET Pooled Data WALL WASH Yes Edited Data STD. ERROR OF RESIDUALS 8.9 Yes No No 6.4 3.6 1.57 SIGNIFICANT PARAMETER AND REG. COEFF. 89.1 (1-e " 40.6 - .318T 93.5 (l-e-014Ci) 5.6-2.9 x 10~4Q ------- scrubbing equipment, but has been experienced in other CDS pilot programs. It should be noted that the particulate under these conditions has a bi- modal distribution of high resistivity hydrocarbon and carbon black. Some hydrocarbon might have condensed on the carbon black increasing its surface electrical resistivity. Therefore, lower efficiency might result as com- pared with the higher inlet loadings (420-510 mg), Figure 22, at the same cut diameter. It is interesting to note that the low inlet load fractional efficiencies were almost independent of both electrode voltage and gas flow rate. Values of these parameters varied between 33 and 38 kilovolts and 12 and 15 x 103 m3/hr. The fractional efficiency data for the higher inlet loadings, Figure 22 , are more typical of the results normally expected from precipitators and high energy wet scrubbers. Efficiencies in the 1 to 2 micron range approach 99%. For this size particulate removal mechanisms consist of both high energy impaction of charged water droplets and electrostatic charging and precipitation. Below 1 micron the collection mechanism is probably by electrostatic precipitation either through charge transfer upon inter- action of a charged water droplets or through direct corona charging of the plasma. The fractional efficiencies at high inlet load and submicron particle sizes approach those of the low inlet load case. This is again attributed to the fact that most of the particulate in this range is hydrocarbon having the same electrical and physical properties as that of the lower inlet load case. Some additional equipment optimization probably could have been affected by running unbalanced electrode waterflow rates between the stages. This would result in optimally sizing the water droplet for high energy impaction and removal of the carbon black in the first stage and the electrostatic precipitation of the hydrocarbon in the second stage. Limited testing with a two-stage unit, (i.e., the third stage removed from the process) showed that about a 2 or 3% loss in efficiency results. Conversely had a fourth stage been added it is believed that approximately a 1.5 to 2.0% efficiency improvement could have been affected. The fourth stage would also protect against infrequent high dust loads which would normally cause a collapse of the first stage. In this event even with a -48- ------- LU a, *•. O LU (J LL. u_ LU 99 98 95 90 8 80 u g: 70 50 INLET LOAD, SYM mg/dM Nm3 RUN NO. X o X 419-508 182 - 217 017 015 O16 D19 A 14 0.3 0.4 0.6 1.0 1.5 2.0 AERODYNAMIC DIAMETER, MICRONS Figure 22. Fractional Efficiency Data for the Higher Inlet Loadings -49- ------- partial loss of the first stage.the equipment would basically perform as an optimized three stage unit. The above performance was achieved in a unit consuming very little power and at a low liquid to gas ratio. Under typical gas flow rate conditions of about 15,000 Nm3/n (13,000 acfm), the total power supply consumption was of the order 0.7-1 watt/hr/Nm3 (.85-1.2 watts/acfm) at a nominal 35 kv electrode voltage. Pressure drops between the CDS inlet and the stack discharge were extremely low, about 1.3 cm/we. System pressure drops, coke oven breeching to CDS stack, were of the order of 10 cm/we. This is probably an atypically high pressure drop in that there were numerous expansions and elbows of ductwork which would increase the pressure drop. The liquid to gas ratio at the nominal conditions were of the order of <5 0.18 £/Nrrr (0.9 gal/1000 acf) gas treated. Energy consumption is typical of energy requirements for wet electrostatic precipitators. Liquid to gas ratios are substantially lower than high energy Venturis and most other types of high performance wet systems. Limited CDS stack opacity observations were made to correlate time ave- raged outlet loads capable of meeting a 20% opacity criteria, Table 8. The stack opacities varied between 5 and 25%. The 15% opacity was not exceeded during Test No. 002 for an average discharge load of 33.4 mg/ o 3 dNm (.0146 gr/dscf). Values of 23 mg/dNm consistently resulted in a stack opacity of 0-5, Tests Nos. 003, 010, Oil, 012 and 015. During Test No. .006, performed during a major upset, the 20% opacity was exceeded during two 5-minute periods. The actual discharge load during this 3 period most certainly exceeded the measured average value of 37.8 mg/dNm as the first stage electrical voltage collapsed. It would appear that a o design point emission discharge of 23 mg/dNrrr would satisfy the requirement. Using 95% as the maximum efficiency for high voltage on three stages, the maximum permissable inlet load corresponds to 700 mg/dNm3 (.3 gr/scf). For inlet loads less than this progressively larger margins of safety result. It should be noted that most data from coking emissions is in the range of 230 to 500 mg/dNm3. The Kaiser Coking Furnace conditions and production rates are such that abnormally high smoking conditions are currently being experienced. It is felt that this results in a sufficiently conservatively CDS design and operating point. -50- ------- Test No. 002 003 010 Oil 012 006 015 Outlet mg/N 33.4 16.9 26. 8 23. 8 23. 8 37.8 22.9 TABLE 8 KAISER OBSERVED CDS STACK OPACITIES Outlet , Dust Load Observed Opacities, % Average / TWT *•' IV •*• I ft f> f T* O _ . 3 .0146 .008 .0117 .0104 .0104 .0165 . 0100 15,10,10,15,15,10,10 5, 5, 10,15,©,©,(2< (5, 5, 5, 5, 5,© 52) 12 5 5 5 5 ll» 7 ' 1st stage voltage severely deteriorated 2, Every other observation recorded 3' Circled nos. Stack A B0% opacity -51- ------- REFERENCES 1. "Charged Droplet Scrubber for Fine Particle Control - Laboratory Study", Report prepared for the Environmental Protection Agency under Contract Number 68-02-1345 by TRW Systems Group, February 13, 1976. 2. Federal Register, Vol 36, No. 247, pp 24887-24890, December 23, 1971. 3. Private Communication from Di-Gerald Shaughnessy of the University of Dayton, dated January 31, 1975. 4. Charged Droplet Scrubber Pilot Demonstration for Fine Particle Control, Test Matrix; Contract Number 68-02-1345, prepared for the Environmental Protection Agency, July 28, 1975. -52- ------- LIST OF TABLES AND FIGURES - APPENDICES A - B - C Table No. Page No. A-l A- 2 A- 3 A- 4 A- 5 B-l B-2 B-3 B-4 B-5 B-6 B-7 B-8 B-9 B-10 B-ll B-12 B-13 C-l C-2 Figure No. C-l C-2 Screening Test Summary . Block One Matrix Test Summary - With Wall Wash .... Development Test Summary Block Two Matrix Test Summary - No Wall Wash Inlet and Outlet Size Distribution Data Summary . . . Inlet and Outlet Sample Particle Data for Run #1 . . . Inlet and Outlet Sample Particle Data for Run #2 ... Inlet and Outlet Sample Particle Data for Run #6 ... Inlet and Outlet Sample Particle Data for Run #8 ... Inlet and Outlet Sample Particle Data for Run #9 . Inlet and Outlet Sample Particle Data for Run #10 . . Inlet and Outlet Sample Particle Data for Run #13 . . Inlet and Outlet Sample Particle Data for Run #14 . . Inlet and Outlet Sample Particle Data for Run #15 . . Inlet and Outlet Sample Particle Data for Run #16 . . Inlet and Outlet Sample Particle Data for Run #17 . . Inlet and Outlet Sample Particle Data for Run #18 . . Inlet and Outlet Sample Particle Data for Run #19 . . Analysis of Data - With Wall Wash Analysis of Data - Without Wall Wash Particle Loading Effect on Removal Efficiency With Wall Wash. Particle Loading Effect on Removal Efficiency Without Wall Wash. A-l A- 2 A- 3 A- 4 A- 5 B-l B-l B-2 B-2 B-3 B-3 B-4 B-4 B-5 B-5 B-6 B-6 B-7 C-l C-2 C-4 C-5 ------- APPENDIX A SUMMARY OF PERFORMANCE DATA ------- Table A-l. Screening Test Summary TEST NO. AND DATE 1 9/23/75 2 9/24/75 3 10/7/75 4 10/8/75 5 10/9/75 6 10/10/75 VOLTAGE a(kV) STAGE TR 1 2 3 SET 30 34 32 73 29 32.5 32.5 65 32 32 30 65.5 29 31 30 62 31 31.5 31.5 7T 29.5 30 29.5 64.5 WATER FLOW RATE (1/min) WALL PRE- ELECTRODE WASH COOLING 62 106 22.7 59 114 • 22.7 61 106 170 5.19e 61 106 17. Oe 6.706 45 106 17.0 6.516 61 106 17.0 6.32e GAS FLOW RATE (sm3/hr) INLET OUTLET 20 835 13 528 18 750 12 537 18 443 13 344 19 770. 17 417 17 930 14 554 21 470 18 130 GAS TEMPERATURE (°C) STACKb INLETC OUTLET 199 107 52 205 120 46 191 138 52 201 162 53 187 128 54 191 156 58 PERCENT MOISTURE INLET OUTLET 8.7 14.4 6.6 73.2 4.55 13.0 10.4 15.2 8.27 13.2 8.97 14.8 PARTICLE LOADING f (mg/sm3) INLET OUTLET 211.9 42.79 73.2 37.41 132.0 62.70 343.9 88.10 215.8 55.84 151.3 59.50 CLEANING EFFICIENCY PERCENT 79.8 48.9 52.5 74.4 74.1 60.7 DAMPER SETTING (NOTCH) 5 5 5 6 5 6 OUTPUT CURRENT (mA) TOTAL LEAKAGE 195 45.5 195 43 170 25 175 25.2 170 23 160 22 POWER INPUT (AC) VOLTS AMPS . 330 36 368 38 388 38 372 37.5 ARC RATE (ARCS/MIN.)d NOMINAL MAXIMUM 50 150 125 300 70 >500 150 >500 50 150 150 230 COMMENTS Negative polarity. One upset during test. Main stack light gray, except black during major load. Positive polarity. Main stack medium gray to clear. Sustained arcing during test. Power supply off periodically to quench arcs. Negative polarity. Main stack clear to medium gray. One major load. Arc quenching capacitor on first stage only. Negative polarity. Main stack light gray to black. Power supply off periodically to quench sustained arcs. Arc quenching capacitor in first stage only. Negative polarity. Main stack light gray. Major load started toward end of run. Arc quenching capacitor in first stage only. Negative polarity. Main stack light gray. Arc quenching capacitor in first stage only. Several collecting troughs were overflowing. a. Nominal set voltage. Mean voltage during periods of high arc rate was considerably lower. b. Stack gas temperature measured at same position as inlet particle sampling port. c. Inlet gas temperature to CDS turning section. Measured after pre-cooling. d. Maximum arc rate readable - 500 arcs/min. e. Net flow rate adsorbed by gas stream. f. gr/dscf = 2288 mg/dNm3 A-l ------- PAGE NOT AVAILABLE DIGITALLY ------- Table A-3. Development Test3 Summary TEST NO. AND DATE D-002 10/29/75 D-003 10/29/75 D-004 10/30/75 0-006 10/31/75 D-007 11/3/75 D-008 11/20/75 D-009 11/20/75 D-010 11/21/75 D-011 11/21/75 D-012 11/24/75 D-013 11/25/75 D-014 12/1/75 D-015 12/1/75 D-016 12/4/75 D-017b 12/5/75 D-018b 12/9/75 VOLTAGE (kV) STAGE 1 2 3 36 36 38 36 36 35 39 40 35 38 40 40 40 40 32 37 36 35 41 40 40.5 40 40 42 40 41 41 40 37 36 39 39 40 39 39.5 39 0 0 40 38 38 40 OUTLET GAS FLOW RATE (sm3/hr) 11 693 8 160 10 079 9 689 11 433 9 219 10 245 10 058 10 639 11 200 14 338 10 804 8 629 66 110C 64 528C GAS TEMPERATURE INLET OUTLET 121 135 120 123 135 132 144 146 137 144 141 140 139 21 Od 226d 51 68 51 69 74 69 69 64 71 77 73 77 72 66 176e 202e PERCENT MOISTURE OUTLET 12.2 6.8 12.3 11.6 12.9 12.0 22.2 12.0 12.8 11.7 11.8 12.8 11.2 ELECTRODE CURRENT (mA) 285 220 250 358 233 248 258 244 222 227 277 260 260 261 ARC RATE LOW/HIGH (ARC/MIN.) 250/575 100/375 50/100 400/500 150/270 >500 400/450 250/350 ?500 >500 >500 ?500 250/500 300/>500 SAMPLING NO. OF NO. OF TRAVERSES POINTS 1 2 1 2 2 2 2 2 2 2 2 1 1 2 16 32 16 32 32 32 16 16 16 16 16 8 16 32 SAMPLE TIME (min) 3 3 3 3 3 3 4 4 4 4 4 3 4 3 DAMPER SETTING (NOTCHES) 4 4 2 4 4 4 4 4 4 4 4 5 4 4 PARTICLE LOADING (mg/sm ) INLET OUTLET 294.7 244.6 364.8 505.5 230.0 642.1 342.1 225.9 253.6 204.8 248.5 551.5 153.3 233.4 68. Of 764. 3f 33.41 16.93 16.93 37.76 12.81 31.58 20.37 26.77 23.80 23.80 37.76 54.23 22.88 21.51 97. 79 CLEANING EFFICIENCY (PERCENT) 88.7 92.9 95.4 92.5 94.5 95.0 94.0 88.2 90.6 88.4 84.8 90.2 85.1 90.8 812. 49 ! STACK OPACITY (PERCENT) MAIN CDS 35-95 15 15 10 10 82 80 10-15 10-15 <5 <5 <5 15 COMMENTS With wall wash. Pi tot probe data in error. Main stack medium gray Main stack medium gray. Main stack clear to light gray. Main stack black to dark gray. Main stack black. Main stack white. Two stage operation. Two stage operation. Main stack black to light gray. Main stack black to dark gray. Main stack light to dark gray. Main stack black to light gray. Nominal Stack Condition Load I a. All DAD tests were run with an electrode flow rate of 53 i/min. and in automatic voltage control- mode. b. Tests D-017 and D-018 were run to obtain a comparison between particle loading in main stack gas stream and stream to CDS. c. Volumetric flow rate of main stack. d. Main stack gas stream temperature. e. Cut off stream to CDS temperature. f- Particle loading in main stack gas stream. A-3 ------- PAGE NOT AVAILABLE DIGITALLY ------- Table A-5. Inlet and Outlet Size Distribution Data Summary Air Pollution Technology, Inc. Run No. APT 1 4 6 8 9 10 13 14 15 16 17 18 19 10P(1) 13P(1) TRW 001 003 004 005 005 006 008 009 010 010 on on 012 Inlet Load , mg/NmJ 232 163 188 247 132 166 953 201 419 182 508 168 217 244 1789 Mean Size dpa,MmA 1.50 0.89 0.96 0.59 0.41 1.60 1.02 1.00 1.35 0.67 1.55 1.55 1.00 0.78 1.92 Std.Dev. ag 2.7 2.0 2.0 2.1 2.6 4.3 1.9 4.2 2.1 2.5 2.2 8.0 2.8 1.7 1.8 Outlet Load mg/Nm3 35.8 61.0 11.0 29.2 41.5 84.5 56.6 23.1 35.5 22.2 23.1 21.9 25.5 166 953 Mean Size dpa'MmA 0.57 0.69 0.96 0.41 0.61 0.95 1.13 1.00 1.40 0.83 1.06 1.25 0.98 2.10 1.02 Std.Dev. "g 2.6 1.9 2.0 2.7 1.8 2.1 2.0 2.2 2.5 2.3 2.2 2.7 2.5 4.3 1.9 Efficiency 85.7 62.9 94.2 88.4 69.5 49.6 94.2 88.9 91.6 88.0 95.6 87.3 88.6 (1) Runs 10P and 13P were samples taken before the water quench sprays; therefore, the inlets for Run 10 and 13 are the outlets for Runs 10P and 13P respectively. A-5 ------- APPENDIX B SUMMARY OF FRACTIONAL EFFICIENCY DATA ------- Table B-l. INLET AND OUTLET SAMPLE PARTICLE DATA FOR RUN #1 IMPACTOR STAGE NUMBER Precutter § Nozzle 1 2 3 4 5 6 7 Filter . Sample Volume (DNm3) INLET M cum (mg/DNm3) 232 232 232 232 230 180 99.8 50.8 42.9 d pc (pmA) 27.3 12.0 5.7 2.3 1.3 0.74 0.45 0.134 OUTLET "cum (mg/DNm3) 35.8 35.8 35.0 34.7 34.0 33.2 27.0 20.2 15.9 V (ymA) --.- 23.8 10.4 4.0 2.0 1.2 0.64 0.37 0.585 Table B-2. INLET AND OUTLET SAMPLE PARTICLE DATA FOR RUN #4 IMPACTOR STAGE NUMBER Precutter § Nozzle 1 2 3 4 5 6 7 Filter Sample Volume (DNm3) INLET M cum (mg/DNm3) 163 159 159 159 158 157 ' 120 65.8 " 28.9 d PC (ymA) 27.4 12.0 4.6 2.3 1.3 0.74 0.45 0.087 OUTLET M cum , (mg/DNn3) 61.0 61.0 60.8 60.6 59.8 58.9 45.4 22.9 17.2 d V (umA) . 23.6 10.3 4.0 2.0 1.2 0.64 0.37 0.475 B-l ------- Table B-3. INLET AND OUTLET SAMPLE PARTICLE DATA FOR RUN #6 IMPACTOR STAGE NUMBER Precutter § Nozzle 1 2 3 4 5 6 7 Filter Sample Volume (DNm3) INLET M cum (mg/DNm3) 188 187 186 186 186 177 132 67,0 26,4 d pc . (ymA) 25.6 11.2 5.3 2.2 1.3 0.69 0.42 0.099 OUTLET M cum (mg/DNm3) 11.0 10.8 10.6 10.6 10.6 10. .0 7.2 2.8 1.0 d VL pc (ymA) 24.3 10.6 4.1 2.1 1.2 0.66 •0.3S 0.602 Table B-4. INLET AND OUTLET SAMPLE PARTICLE DATA FOR RUN #8 IMPACTOR STAGE NUMBER Precutter § Nozzle 1 2 3 4 5 6 7 Filter Sample Volume (DNm3) INLET M cum (mg/DNm3) 247 247 246 245 245 238 - 194 134 - 59.0 V (ymA) 21.6 9.5 4.5 1.8 1.1 0.58 0.35 0.134 OUTLET "cum (mg/DNm3) 29.2 27.5 26.0 25.3 25.3 25.3 24.9 21.0 14.2 • V (ymA) 26.0 11.4 4.4 2.2 1.3 0.70 0.41 0.466 B-2 ------- Table B-5. INLET AND OUTLET SAMPLE PARTICLE DATA FOR RUN #9 IMPACTOR STAGE NUMBER Precutter 5 Nozzle 1 2 3 4 5 6 7 Filter Sample Volume (DNm3) INLET M cum (mg/DNm3) 132 119 113 113 113 113 113 95.4 65.21 d V (ymA) 24.5 10.7 4.2 2.1 1.2 0.66 0.40 0.106 OUTLET M cum (mg/DNm3) 4.1.5 41.3 40.6 40.6 40.6 40.6 39.5 23.0 13.9 d PC (ymA) 26.6 11.6 4.5 2.3 1.3 0.72 0.41 0.438 Table 6-6. INLET AND OUTLET SAMPLE PARTICLE DATA FOR RUN #10 IMPACTOR STAGE NUMBER Precutter § Nozzle 1 2 3 4 5 6 7 Filter Sample Volume (DNm3) INLET PRIME M cum (mg/DNn3) 244 244 244 244 244 244 224 137 5 7. -6 V (ymA) 32.1 14.0 5.4 2.7 1.6 0.87 0.52 0.045 INLET Mcum (mg/DNm3) 166 107 105 103 100 100 54.7 29.6 27.4 dpc (ymA) 24.7 10.8 5.1 2.1 1-2 0.67 0.40 0.044 OUTLET Mcum (mg/DNm3) 84.5 84.5 83.6 82.8 81.6 76.5 48.8 22.4 16.2 V (ymA) 26.0 11.4 4.4 2.2 1.3 0.70 0.40 . 0.355 B-3 ------- Table B-7. INLET AND OUTLET SAMPLE PARTICLE DATA FOR RUN #13 IMPACTOR STAGE NUMBER Precutter 5 Nozzle 1 2 3 4 5 6 7 Filter Sample Volume (DNm3) INLET PRIME M cum (mg/DNm3) 1789 1678 1651 1636 1569 1247 477 108 27.7 d pc (ymA) 26.9 11.8 4.6 2.3 1.3 0.73 0.44 _•__ 0.115 INLET M cum (mg/DNm3) 953 945 938 935 923 857 644 233 113 d pc (ymA) 26.6 11.7 4.5 2.3 1.3 0.72 0.42 0.088 OUTLET M cum (ng/DNm3) 56.6 54.8 53.7 52.0 50.2 44.1 29.0 12.5 2.5 d pc (ymA) 23.2 10.2 3.9 2.0 1.1 0.63 0.36 0.279 Table B-8. INLET AND OUTLET SAMPLE PARTICLE DATA FOR RUN #14 IMPACTOR STAGE NUMBER Precutter § Nozzle 1 2 3 4 5 6 7 . Filter Sample Volume (DNm3) INLET M cuin (mg/DNm3) 201 168 156 . 146 138 - 126 ' 90.8 41.4 5.9 d pc (ymA) 11.1 4.6 2.6 1.4 0.88 0.48 0.28 0.051 OUTLET M cum (mg/DNm3) 23.1 23.1 22.1 21.0 19.5 16.2 - 10.5 4.4 1.0 d pc (ymA) 17.3 7.6 2.9 1.5 0.85 0.47 0.27 --- 0.771 B-4 ------- Table B-9. INLET AND OUTLET SAMPLE PARTICLE DATA FOR RUN #15 IMPACTOR STAGE NUMBER Precutter 5 Nozzle 1 2 3 4 5 6 7 Filter Sample Volume (DNm3) INLET M cum (mg/DNm3) 419 410 399 382 360 195 84.5 36.8 7.4 d pc (ymA) 8.4 4.2 2.4 1.3 0.81 0.45 0.26 0.054 OUTLET M cum (mg/DNm3) 35.5 35.2 33.5 31.4 27.2 21.6 12.3 4.9 1.8 d pc (ymA) 18.8 8.2 3.2 1.6 0.92 0.51 0.29 0.554 Table B-10 INLET AND OUTLET SAMPLE PARTICLE DATA FOR RUN #16 IMPACTOR STAGE NUMBER Precutter 5 Nozzle 1 2 3 4 5 6 7 Filter Sample Volume (DN'm3) INLET M cum (mg/DNm3) 182 177 174 168 163 149 - 108 58.0 ' . 5.5 d V CymA) 10.1 4.2 2.4 1.3 0.80 0.44 0.25 0.036 OUTLET M cum (mg/DNm3) 22.2 22.2 21.8 21.2 20.0 17.6 12.9 7.4 1.4 d PC (ymA) 18.0 7.9 3.1 1.5 0.89 0.49 0.28 0.933 B-5 ------- Table B-ll INLET AND OUTLET SAMPLE PARTICLE DATA FOR RUN #17 IMPACTOR STAGE NUMBER Precutter § Nozzle 1 2 3 4 5 6 7 Filter Sample Volume . (DNm3) INLET M cum (mg/DNm3) 508 476 467 456 433 214 119 50.2 9.3 d pc (vimA) 9.4 4.8 2.7 1.5 0.90 0.50 0.29 0.054 OUTLET M cum (mg/DNm3) 23.1 23.0 22.2 21.1 19.1 15. -9 10.3 4.1 1.4 d pc (ymA) 18.6 8.1 3.2 1.6 0.91 0.50 0.29 0.876 Table B-12. INLET AND OUTLET SAMPLE PARTICLE DATA FOR RUN #18 IMPACTOR STAGE NUMBER Precutter § Nozzle 1 2 3 4 5 6 7 Filter Sample Volume (DNm3) INLET M cum (mg/DNm3) 168 129 126 121 116 111 103 78.4 - 24.5 dpc (MmA) 11.3 4.7 2.7 1.5 0.89 0.49 0.28 0.061 OUTLET Mcum (mg/DNm3) 21.8 21.8 21.0 19.8 17.5 14.3 9.8 5.2 1.1 V (pmA) 19.2 8.4 3.2 1.6 0.94 0.52 0.30 0.943 B-6 ------- Table B-13 INLET AND OUTLET SAMPLE PARTICLE DATA FOR RUN #19 IMPACTOR STAGE NUMBER Precutter 5 Nozzle 1 2 3 4 5 6 7 Filter Sample Volume (DNm3) INLET M cum (mg/DNm3) 217 170 166 160 151 135 77,5 50.3 15.0 d pc (pmA) 8.7 4.4 2.5 1.4 0.83 0.46 0.27 0.074 OUTLET M cum (mg/DNm3) 25.5 25.5 24.6 23.7 21.9 19.0 13.3 6.3 2.1 d pc (ymA) 1.9.5 8.5 3.3 1.7 0.96 0.53 0.30 0.663 B-7 ------- APPENDIX C REGRESSION ANALYSIS SUMMARY ------- Table C-l. Analysis of Data - With Wall Wash OBJECTIVE DATA SAMPLED RESULTS AND COMMENTS o i 1. Fit curve to eliminate effect of inlet particle loading on efficiency, n. Must meet initial conditions that at X = 0 n = 0, and at X = », n <100. 2. Determine additional reduction in residuals after correcting for inlet loading. Parameters considered were inlet gas temperature, outlet gas flow rate, and interaction.*** The outlet gas flow rate was corrected to standard dry condition. TRW DATA:9N, ION, UN, 12N, 13N, 14N, 15N, 16N, D002, SI * S2, S3, S4, S5, S6. ATP DATA: ION, UN, 12N, 13N, 15N. TRW DATA ONLY.** (Same as No. 1 above) n = KQ(1 - e"KlX), KQ = 89.1, K-, = .008746, s(K0) = 4.7, s(K1) = .0013, s(R) = 8.9. (See Figure 1) This curve is significantly different from the curve obtained without wall wash. Indicated addition correction for inlet gas temperature, T. The correction is 40.6 - .318T. The standard error of residuals, s(R) = 8.0, was reduced to 6.4. (Completely opposite of results without wall wash) ** *** denotes screening tests. ATP data wasn't utilized because it was assumed that all input data was not available. Electrode Voltage was eliminated via visual examination of the plots of the parameters versus the residuals. ------- Table C-2. Analysis of Data - Without Wall Wash RESULTS AND COMMENTS OBJECTIVE DATA SAMPLED o i ro 1. 3. Fit curve to eliminate effect of inlet particle loading, X, on efficiency, n. Must meet initial conditions that at X = 0, n = 0, and at X = », n <100. Determine addition reduction in residuals after correcting for inlet loading. Parameters con- sidered* were inlet gas temperature, outlet gas flow rate and interaction. The outlet gas flow rate was corrected to standard dry condition. Determine additional reduction in residuals after correcting for inlet loading. Censured data. (n >90%, X >227 mg/m3). Parameters considered were electrode voltage (stage 1 and stage 2), inlet gas temp and the actual measured flow rate at the prevailing ambient condition. TRW DATA: IN, 2N, 4N, 5N, 6N, 7N, 8N, D003, D004, D006, D007, D008, D009, D010, DOll, D012, D014, D015, D016, D019, D020, D021, D022, D023, D024, D025. ATP DATA: 2N, 4N, 7N.7N, 8N, 8N. TRW DATA; ** IN, 2N, 4N, 5N, 6N, 8N, D006, D007, D008, D009, D010, D011, D012, D014, DO!5, DO!6. TRW DATA:*** IN, 2N, 4N, 5N, 6N, 8N, D006, D007, D008, 0009, DOll, D014, D016 ATP DATA 15, 17. N = K0(l - e"KlX), KQ = 93.5, K] = .014468, ) = .0009669, s(R) = 3.6. s(K0) = .92, (See Figure 2) This curve significantly different from the curve obtained with wall wash. Indicated additional correction for gas flow rate and interaction. The correction is 4.1 + .00057R - .000007RT The standard error of residuals, s(R) = 1.7 was reduced to 1.5. (Completely opposite of results with wall wash) Indicated additional correction for gas flow rate. The correction is 5.6 - .00029R. The standard error of residuals, s(R) = 1.76 was reduced to 1.57. ------- Table C-2. Analysis of Data * Without Wall Wash (Continued) OBJECTIVE DATA SAMPLED RESULTS AND COMMENTS o CO 4. Same as No. 3. except gas flow rate corrected to standard dry condition. 5. Same as No. 3. except used actual efficiencies. It is assumed the censored data is in a region where inlet loading has a minimal effect. 6. Same as No. 5. except used gas flow rate corrected to standard dry conditions. Same as No. 3. Same as No. 3. No additional correction indicated. No additional correction indicated. Same as No. 3. No additional correction indicated. * Electrode Voltage was eliminated via visual examination of the plot of the parameters versus the residuals. ** ATP data wasn't utilized because it was assumed that all input data was not available. *** All data obtained after 12/31/75 was deleted. Test equipment considered to be degraded. ------- o 95. 85. 1 75. u z LLJ y £ 65. 45. 65. 165. 265. 365. 465. 565. 665. 765. INLET LOADING (MG/M3) 865. Figure C-1. Particle Loading Effect on Removal Efficiency With Wall Wash ------- o on DATA SOURCE • APT • DAD A MATRIX 265. 365. 465. INLET LOADING(MG/M3) Figure C-2, Particle Loading Effect on Removal Efficiency Without Wall Wash ------- TECHNICAL REPORT DATA (Please read Instructions on the reverie before completing) 1. REPORT NO. EPA- 600/2 -76-249b 2. 3. RECIPIENT'S ACCESSION-NO. 4. TITLE AND SUBTITLE CHARGED DROPLET SCRUBBER FOR FINE PARTICLE CONTROL: PILOT DEMONSTRATION 5. REPORT DATE September 1976 6. PERFORMING ORGANIZATION CODE 7. AUTHOR(S) W. F. Krieve and J. M. Bell 8. PERFORMING ORGANIZATION REPORT NO. 9. PERFORMING ORGANIZATION NAME AND ADDRESS TRW Defense and Space Systems Group One Space Park Redondo Beach, California 90278 10. PROGRAM ELEMENT NO. 1AB013; ROAP 21ADL-043 11. CONTRACT/GRANT NO. 68-02-1345 12. SPONSORING AGENCY NAME AND ADDRESS EPA, Office of Research and Development Industrial Environmental Research Laboratory Research Triangle Park, NC 27711 13. TYPE OF REPORT AND PERIOD COVERED Phase: 7/74-6/76 14. SPONSORING AGENCY CODE EPA-ORD 15. SUPPLEMENTARY NOTES JERL-RTP project officer for this report is D.L. Harmon, Mail Drop 61, 919/549-8411, Ext 2925. 16. ABSTRACT The report gives results of a successful Charged Droplet Scrubber (CDS) pilot demonstration of coke oven emissions control, It also describes the design, installation, and checkout of the demonstration system. The CDS uses electrically sprayed water droplets, accelerated through an electric field, to remove particulate material from a gas stream. The pilot demonstration was a continuation of laboratory and bench scale studies for application of the CDS to fine particle control. The pilot demonstration included, in addition to the CDS, the ducting, flow transitions, and blower necessary to circulate process gas through the CDS. The test was performed at the Kaiser Steel Company coke oven facility, Fontana, California. A large fraction of the coke oven emissions were submicron and composed of carbon particles and hydrocarbon aerosol. After the system checkout was completed, during which CDS operating parameters were established, the demonstration test series was performed. Results of the demonstration test indicate that the CDS is an effective pollution control device for controlling coke oven stack emissions. 17. KEY WORDS AND DOCUMENT ANALYSIS DESCRIPTORS b.lDENTIFIERS/OPEN ENDED TERMS c. COSATI Field/Group Air Pollution Scrubbers Dust Electrostatics Coking Carbon Hydrocarbons Aerosols A ir Pollution Control Stationary Sources Particulate Charged Droplets Charged Droplet Scrub- ber 13B 07A 11G 20C 13H 07B 07C 07D 18. DISTRIBUTION STATEMENT Unlimited 19. SECURITY CLASS (This Report) Unclassified 21. NO. OF PAGES 82 20. SECURITY CLASS (This page) Unclassified 22. PRICE EPA Form 2220-1 (9-73) 82 ------- |