V-/EPA
                                United States
                                Environmental Protection
                                Agency
                                Industrial Environmental Research
                                Laboratory
                                Research Triangle Park NC 27711
                                Research and Development
                                EPA-600/S7-82-038 Sept. 1982
Project Summary
                                Environmental Assessment of a
                                Low-Emission  Oil-Fired
                                Residential  Hot  Water
                                Condensing Heating  System
                                C. Castaldini
                                 The report gives results of tests to
                                evaluate multimedia emissions from a
                                condensing hot water residential
                                heating system equipped with a low-
                                emission oil-fired burner manufactured
                                by Maschinenfabrick Augsburg-Nurn-
                                berg (M.A.N.) of West Germany. Tests
                                included continuous monitors for flue
                                gas criteria pollutant  emissions and
                                laboratory analysis of samples utilizing
                                gas chromatography  (GC), infrared
                                spectrometry (IR), liquid chromatog-
                                raphy (LC), and gas chromatography/
                                mass spectrometry  (GC/MS) for
                                organics; and spark source mass
                                spectrometry (SSMS), atomic absorp-
                                tion spectrometry  (AAS). and ion
                                chromatography (1C) for trace metals
                                and anions. Flue gas concentrations of
                                NOx. SO2, and CO averaged 76. 156,
                                and 40 ppm, respectively, corrected
                                to zero % O2. Sulfate and copper were
                                the primary pollutants in  the tank
                                water discharge, about 1,000 and
                                500 mg/l,  respectively. Concentra-
                                tions of copper and other trace metals
                                in this water were  attributed  to
                                leaching of heat transfer  surfaces
                                immersed in acidic (pH = 3.0) water.
                                Organic emissions measured 3.5
                                mg/dscm in the flue gas and  0.1
                                mg/l in the waste water. Biological
                                tests indicated moderate mutagenic
                                response of the flue gas and moderate
                                toxicity of waste water to mammalian
                                cells.
                                 This Project Summary was devel-
                                oped by EPA 's industrial Environ-
                                mental Research Laboratory, Research
                                Triangle Park, NC, to announce key
                                findings of the research project that is
                                fully documented in a separate report
                                of the same title (see Project Report
                                ordering information at back).


                                Introduction
                                 A number of  low-emission, high-
                                efficiency residential systems and
                                burners have been developed recently.
                                This report describes the results of
                                extensive emissions testing of one of
                                these units. The flue gas was analyzed
                                for criteria pollutants as well as
                                noncntena  organic  and  inorganic
                                species. Since the unit was a condensing
                                hot water heater, water tank composition
                                was also determined.
                                 The residential heater tested repre-
                                sents an innovative European design
                                utilizing a condensing  flue gas system
                                and a high-efficiency low-emission
                                burner. The burner, shown in Figure 1,
                                is manufactured by Maschinenfabrick
                                Augsburg-Nurnberg (M.A.N ) of West
                                Germany. It utilizes a finely atomized
                                distillate oil and  recirculated hot com-
                                bustion gases mixed with fresh air to
                                complete combustion of the fuel in the
                                burner pipe. The fuel oil can be pressur-
                                ized to 2.1 MPa (about 300 psi) and is
                                atomized by a 60° hoHow-cone nozzle

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 Nozzle
                 Seal
  Damper
Figure 1.  M.A.N. residential oil-fired
          burner.

delivering about 0.53 ml/s (0.5 gal./hr).
The combustion of the fuel in the mixing
tube produces a stable blue flame The
recirculation of the combustion gases
also  causes  NO* emissions to be 40-
50% lower than those from a conven-
tional high-pressure atomizing  burner
widely used for  residential oil-fired
furnaces.  Because the M.A.N.  burner
recirculates the combustion gases
internally within the burner pipe where
combustion is completed, retrofit instal-
lation on  existing  residential heating
systems  is possible. Although  other
blue flame burner designs have been
developed and implemented in the U.S.,
the retrofit  capability  of the M.A.N.
design has  made it  attractive as  a
potential  technique for  reducing NOx
emissions from existing residential
units.
  The firebox of the furnace is completely
immersed  in water.  The water level
reaches approximately 2 cm (less than 1
in.) below the top of  three exhaust
pipes. This water level is controlled by
positioning the condensed water drain
spout. Before the combustion products
exit  the furnace exhaust duct, they
pass over the water surface andthrough
a series of baffles and heat exchanger
tubes. The cooling water, which absorbs
heat from  the furnace and carries it to
the residence, enters through  a  heat
exchanger tube  near the top  of  the
furnace and  then flows through  the
immersed  copper coils before it exits.
Condensation of  the water in the flue
gas  begins  when cool water meets
combustion products on their way out of
the tank, condensing practically all the
water produced by combustion of the
fuel.
  Condensing heating systems such as
this  can  achieve  thermal  efficiencies
exceeding 95%  under normal cyclic
operation. This high thermal recovery is
a significant improvement over  cyclic
efficiencies of conventional residential
heating  systems,  normally about 75-
80%.
  Tests were performed with  the unit
operating in a typical cyclic mode. Cycle
frequency of the burner was controlled
by  adjusting  the  setting of  the tank
water thermostat and the cooling water
flowrate.  A thermostat setting of
approximately 54°C (129°F) and  a
cooling water flowrate of 107 ml/s (1.7
gal /hr) resulted  in burner cycle fre-
quencies of 11-14 min on, 22-25 min
off.
  The sampling and analysis procedures
used in this test program conformedto a
modified EPA  Level 1  protocol for the
gas and liquid discharge streams. Flue
gas measurements made at the exit of
the furnace at about 1 m (3 ft) from the
base of the uninsulated exhaust pipe
included:
   • Continuous monitors for NO, NO,,
     CO, C02, 02, and  total unburned
     hydrocarbons (TUHC).
   • Source  Assessment Sampling
     System (SASS) train sampling.
   • EPA Method  5 for solid and con-
     densable  particulate mass emis-
     sions
   • EPA Method  8 for S02 and S03.
   • Grab sample  for onsite analysis of
     Ci to C6  hydrocarbons   by gas
     chromatography.
   • Bacharach smoke spot. The analy-
     sis protocol for SASS train samples
     included:
   • Analyzing the filter catch, ashed
     XAD-2 resin,  and the first impinger
     solution  for  73 elements using
     spark  source mass spectrometry
     (SSMS)  and  for Hg  using cold-
     vapor atomic  absorption spectrom-
     etry (AAS)
   • Analyzing the second and third
     impinger  solutions for As and Sb
     using furnace AAS techniques,
     and for Hg using cold-vapor AAS.
   • Extracting the XAD-2 sorbent resin
     in a  Soxhlet apparatus using
     methylene chloride, concentrating
     the extract to 10 ml, then deter-
     mining the organic content of the
     extract in two boiling point ranges:
     100-300°C  by  total chromato-
     graphable organics (TCO) analysis
     and >300°C  by gravimetry.
   • Further concentrating the extract
     to 1  ml and  analyzing for the 58
     semivolatile  organic priority pol-
     lutants by gas chromatography/
     mass spectrometry
Water tank discharge samples collected
were subjected to  inorganic analysis by
SSMS  and AAS for Hg, As, and Sb; and
to anion analysis  for chloride,  nitrate,
and sulfate by ion chromatography.
They were a Iso extracted with methylene
chloride and subjected to the organic
analysis protocol noted above.
  The XAD-2 sorbent resin extract was
also subjected to liquid chromatography
separation into seven polarity fractions
on silica gel to give compound category
composition information. In addition,
infrared spectra were obtained for the
gravimetric residues of all extract
samples (whole  samples and liquid
chromatography fractions).
  The XAD-2 sorbent extract and the
tank water discharge were subjected to
mutagenicity and toxicity evaluation
using the Level 1 Ames mutagenicity,
CHO cytotoxicity, and the whole animal
acute toxicity in rodent (RAT) bioassay
tests.
Summary and Conclusions
  Table 1 lists flue gas emission levels
of CO, C02, NO, N02, TUHC, particulate,
SOX, and smoke in the flue gas measured
during the  period  of firing. During the
test there were peaks of CO and HC
emissions  at the start  and end of
burner-on times. The peak emissions at
the start  of each cycle are included in
the reported emissions; however, the
effects of  burner shut-off were not
included. Since the blower and the fuel
pump were  shut off at the same  time,
there was no forced air when the burner
was shut off. Thus, the combustion air
flowrate is unknown, and the CO and
HC  emissions at the end of the firing
cycle cannot be evaluated.
  Burner  start-up peak  emissions
averaged 150 ppm for CO and 1 5 ppm
for  HCs.  The NO  started at  zero and
reached approximately 70 ppm on the
average at  1.9%  average excess O2.
Smoke emissions measured  with the
Bacharach  hand  pump kit were zero
during the entire burner-on period. NO
emissions averaged 76 ppm at zero % O2
over the duration of the test. This level is
a 40% reduction from  conventional
residential  heating systems  burning
distillate oil. Condensation of  flue gas
moisture apparently removed all  N02
from the flue gas. Analysis to determine
anions in the tank water and condensate
drain collected during the test showed,
in fact, that nitrates were absorbed in
the water  Tank  water  nitrate  levels
reached 7 mg/l. The nitrogen content of
the oil burned averaged 0.04%, making
it a relatively high  nitrogen  distillate,
leading  to correspondingly  high NO
emissions.
  Sulfur species (SO2 and SOa) in the
exhaust gas were  analyzed  by EPA
Method  8.  As expected, S02  was the

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 only sulfur species found in the exhaust
 gas. Both gaseous  SO3 and any con-
 densed-phase sulfate were absorbed in
 the water, as indicated by the sulfate
 content of the  tank water, which
 reached 990 mg/l. Chloride levels in the
 tank water reached 1.0 mg/l.
  Bacharach smoke emissions were
 measured throughout the test program
 at various time intervals after fuel light-
 off  Smoke numbers were consistently
 zero throughout each firing period  The
 absence of smoke and relatively low CO
 emission peaks during burner light-off
 are attributable to the fuel oil delay valve
 of the  M.A.N. burner which prevented
 ignition for approximately 15 sec after
 the blower started.
  Table 2 shows results of the organic
 analysis of SASS samples by boiling
 point range.  100 to 300°C (TCO) and
 greater than  300°C (gravimetric).  The
 flue gas results indicate that 74% of all
 the organic emissions were measured
 by TCO analysis of  the XAD-2 extract.
 Still,  total concentration of organic
 matter m the flue gas measured only 3.5
 mg/dscm. The water analysis results
 indicate that some organic matter
 condensed in the_water,  however, the
 total concentration measured  in the
 tank water discharge was less than 0.1
 mg/l.
  Infrared spectra  of the gravimetric
 residue of the XAD-2 extract and the
 tank water discharge extract suggested
 the presence of aliphatic hydrocarbons
 and oxygenated species (carboxyhc
 acids, esters, aldehydes, alcohols,
 etc.).
  The XAD-2 extract was subjected  to
 liquid  chromatography separation.
 Results of this fractionation combined
 with infrared analysis of the gravimetric
 residue of sample fractions suggested
 that, of the 3.5  mg/dscm of organics
 emitted by the furnace, about 92% are
 aliphatic hydrocarbons and the remain-
 ing 8% are oxygenated species. This
 suggests that the bulk of the organics
 emitted consist of unburned  fuel; the
 remainder is partially oxidized fuel.
  Gas  chromatography/mass spec-
trometry analysis of sample  extracts
was performed to  determine the 58
semivolatile organic priority pollutants.
Of these, only naphthalene  and phe-
nanthrene or anthracene were detected,
as also shown in Table 2.
  Results of a SAM/IA evaluation of the
data obtained in this test program are
given in Table 3, which shows species
with discharge severity (DS) greater
than 0.1. In the flue gas stream, NO and
Table 1.    Flue Gas Emissions3

              Species
      flange
Average
Oz. percent dry
COz, percent dry
HzO, percent
C0a, ppm at 0 percent Oz
ng/J
NO. ppm at 0 percent 02
ng/J as NO 2
NOz
TUHC. ppm at 0 percent Oz
ng/J as CsHa
SOz, ppm at 0 percent Oz
ng/J
SOz
Solid paniculate. ng/J
(Method 5)
Condensable paniculate, ng/J
(Method 5)
Smoke. Bacharach
1 4 to 2.4
12.6 to 14.0
2.7 to 3.0
15 to 51
4.5 to 15
68 to 79
33 to 39
0"
0.5 to 9.0
0.2 to 4. 1
—
—
Ob
—

—

0
1 9
12.9
2.9
40
12
76
37
0
3.3
15
56
106
00
13

1.4

0
"Includes peak emissions at the start of burner-on cycle.
^Nitrates and sulfates were absorbed in the tank water.
Table 2.    Organic Emissions Summary
                                    Flue Gas
                                    mg/dscm
                 Tank Water Discharge
                        mg/l
Total Chromatographable
  Organics (TCO}
2.6
Gravimetric (GRAV)
Total
Naphthalene
Phenanthren e/A nthracene
0.9
3.5
fjg/dscm
36
2
<0.1
<0.1
vg/t
0.4
0.08
Table 3.    Discharge Severities Greater Than 0.1 for the Low-Emission Condensing
           Furnace System
Pollutant Species
Cu
sot
/VOx
SOz
Fe
Ni
Cr
Se
CO
Mn
S
Zn
Aldehydes
Pb
Carboxylic acids
Na
Flue Gas
Emitted
Concentration
/jg/dscm
59
—
9.9 x 704
1.3 x 10s
15
8.6
3.4
0.25
3. 1 x 70"
1.4
480
7.5
100
2.8
200
220

DS
0.03
	
11
10
0.015
0.57
3.4
0.001
0.77
<0.001
0.48
0.002
0.40
0019
0.20
0.11
Tank Water
Discharge
Concentration
H9/I
5.0 x 705
5.3 x JO5
	
	
7. Ox 70"
7,000
700
700
—
730
	
7.0 x /O4
—
70
—
—

DS
100
67
	
	
67
4.4
2.8
2.0
—
0.76
	
0.40
—
0.28
—
—
                                                                                   * US.GOVERNMENTPRINTimOFFICE:IN).559-017/0800

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    SO? emissions were responsible for the
    highest DS values, both exceeding unity
    by a  factor of nearly 10. CO and THCs
    (primarily aliphatics)  were present in
    nonhazardous  concentrations  (DS
    <1 0). Four elements with DS greater
    than 0 1 were found m the flue gas Cr,
    Ni, Na, and S, with only Cr having a DS
    exceeding unity  Both  Cr and Ni emis-
    sions, however, are suspected contam-
    inants  inherent in sample preparation
    for trace element analysis
      Two organic categories  had potential
    DS values greater than 0 1. However,
    these organic category DS values were
    calculated under the conservative as-
    sumption that all the  organic content
    assignable to the respective category
    consisted of  the  compound  with the
    lowest discharge multimedia environ-
    mental goal (DMEG) potentially present
    in the sample
      Trace elements in the tank water for
    which DS exceeded unity were Cu, Cr,
         Fe, Ni, and Se. Cu concentrations, in
         fact, exceeded those of any other
         element detected in the tank water This
         high concentration of Cu is attributed to
         leaching of heat exchanger copper coils
         immersed in  the  warm acidic  tank
         water. In fact, concentrations of most of
         the other three  trace  elements of
         potential concern can  be attributed to
         the leaching  of  metal surfaces in
         contact with the tank water Sulfate (as
         sulfunc acid) in the tank water repre-
         sents the next greatest potential concern.
           Results of these bioassay analyses
         showed that the XAD-2 sorbent extract
         exhibited moderate mutagenicity in the
         Ames bioassay, and low to  nondetec-
         table toxicity in the CHO assay The tank
         water discharge exhibited  moderate
         cytotoxicity in the CHO assay, non-
         detectable toxicity in the rodent whole
         animal test,  and nondetectable muta-
         genicity in the Ames bioassay
       C. Castaldini is with Acurex Corp., Mountain View, CA 94042.
       Robert E. Hall is the EPA Project Officer (see below).
       The complete report consists of two volumes, entitled "Environmental Assess-
         ment of a Low-Emission Oil-Fired Residential Hot Water Condensing Heating
         System:"
           "Volume I. Technical Results," (Order No. PB 82-239 344; Cost: $12.00,
           subject to change)
           "Volume II. Data Supplement," (Order No. PB 82-239 351; Cost: $16.50.
       subject to change)
       The above reports will be available only from:
              National Technical Information Service
              5285 Port Royal Road
              Springfield,  VA 22161
              Telephone. 703-487-4650
       The EPA Project Officer can be contacted at:
              Industrial Environmental Research Laboratory
              U.S. Environmental Protection Agency
              Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Postage and
Fees Paid
Environmental
Protection
Agency
EPA 335
Official Business
Penalty for Private Use $300
             PS    00003a9

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