VDI-RICHTLINIEN
VEREIN
DEUTSCHER
INGENIEURE
Staubauswurf
Eis enhuttenwerke
Hochofen
VDI 2099
February 1959
           RESTRICTING DUST EMISSION IN BLAST-
                     FURNACE OPERATION
This publication, translated from the German, was prepared by
the Society of German Metallurgists, Dusseidorf. All rights
reserved.
               Reproduced with permission by the
U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
                    Public Health Service
                      Washington, D. C.
              VDI-Kommission Reinhaltung der Luft
                                           Forts etzung Seite 2 bis 10
                VDI-Handbuch Reinhaltung der Luft:
     Katalog der Quellen fur die Luftverunreinigung,  Ziff. 3. 1. 1.

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                            Foreword

     This is one of several dozen VDI Clean Air Committee specifications
on air purification which the Division of Air Pollution of the U.S.  Public
Health Service has obtained permission to translate, publish, and distri-
bute in limited quantity.  A complete list of the VDI publications being
published by the Division of Air Pollution appears on the inside back
cover.  Because the VDI Committee from time to time revises these
specifications, this and other publications in the series may be super-
seded by later publications.

     The VDI Clean Air Committee specifications are compiled by trade
or professional associations and published by the Committee.  The Com-
mittee has neither official status nor regulatory authority,  although West
German governmental agencies participate in its activities.  Air quality
specifications published by the Committee are therefore advisory, rather
than regulatory.   They may however later be adopted by West German
governmental authorities.

     The English translations were done by the Joint Publications Research
Service of the Office of Technical Services, U.S. Department of Commerce.
It should be borne in mind that various terms literally taken from the Ger-
man do not have the same connotation in English} for example, the word
"standard" frequently  appears  where the word "criteria" might better
reflect the comparable American meaning, since in this country "standard"
is generally meant to imply a legally enforceable value,  while  "criteria"
usually means  a recommended value upon which standards may be based.

     The publication and distribution of these translations by the Public
Health Service constitutes neither endorsement of the specifications nor
of the air quality or emission limitations recommended in them.  We
believe that they contain much useful information that would otherwise
not be available to non-readers of German and for this reason have made
them available to workers in the air pollution field in the United States.

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         RESTRICTING DUST EMISSION IN BIAST-FURNACE OPERATION
                             Prepared bys



             Society of German Metallurgists, Dusseldorf
VDI No. 2099, February 1959

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                           TABLE OF CONTENTS
     Notes on Specifications on "Dust Emission"„  „  .  .  .  0  .  0     1

     Foreword  000000000000000000000000     2

lo   TeChnOlOgy  00000000000000000000000     3

lol  The Blast-Furnace ooooooooo<,ooooooo..o     3

Io2  Operating Data for Blast Furnaces o.oooooooooo     3

Io3  Blast Furnace Gas oooooooooooooooooo.oo     h

lok  Blast-Furnace Flue Oust o 0 <> <,<,<>  „<,»<-»  °  »„  0  <><,     8

20   Reduction of Dust Emission  , a 0 ,  ,  „  0  .  o  „  ,  „  »  .  .    11

2ol  Selection of Dust»Removal Installation for Blast=
       Fiiaraace Gas Purification  . » . .  .  o  «  .  .  *  «,  .  .  .  .    11

2o2  Operating Data of Customary Dust Separators  ,  „  ,  „  ,  0  »    13

2o3  Pointers fo» Cloth Filters  „ . . .  .  .  .  .  .  .  .  .  .  .  ,    Ih

20k  Pointers for Mechanical Dust Separators  (Bag and/or
       turbulence filters) , , , „ . . .  .  ,  „  0  .  .  .  .  .  «  .    ill

2o^  Pointers for Wet Electrostatic Precipitators  ,  «,  .  .  ,  0    i$

2o6  Measure in Special Cases  „ . o o ,  a  ,  *  ,  ,  ,  .  .  o  ,  ,    16

b O |   O WCavJ^Sl  OOOOOOOOOOOOOOOOOOOOOOO  O  O    A f

3o   Guide Lines for Restricting Dust Emission  o  .  .  .  .  .  .  .    18

     References  0 0 o „  0 0 o „<, oo«  0  0  <,  0  o  <,<><,<,  o<,    19
                                  ii

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              NOTES ON SPECIFICATIONS ON "DUST EMISSION"
       The VDI Committee on Air Purification has assumed the task of
determining the sources of air pollution, of collecting technical
documentation and of preparing suggestions for improvement of condi-
tions.  The Committee is composed of experts in all fields of importance
for safeguarding the purity of the air.

       The findings obtained are utilized for the preparation of
"Specifications" in which the measures for improving air purification
are grouped together,,

       The specifications are subdivided into the following groups;

           1)  Guide lines for the calculation of distribution!
           2)  Guide lines for permissible immission concentrationsj
           3)  Guide lines on restricting dust and gas emission^
           li)  Guide lines on measuring techniques.

       A review of all known sources of air pollution is contained
in VDI Specifications No. 2090.

       The committee will adapt the catalogue on sources and the guide
lines progressively to the latest scientific and technical findings.
The catalogue, the guide lines and other technical documentation of
the VDI Committee on Air Purification are collected in the VDI Manual
on Air Purification.
                                - 1

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                               FOREWORD
       It is the task of the specifications on "dust emission"!

           1) to characterize the influences which create dusts
           2) to point out measures for the reduction of dust emission j
           3) to establish guide lines for permissible dust emission j
           h) to determine the necessity for dust removal from flue
                gases and to give indications for the selection of
                suitable dust separators.

       Knowledge of the relation between emission and deposition is
important for an objective evaluation of the dust level.  Present
research findings give many indications on this relation (1-U) but the
evaluation of given circumstances is made very difficult by multiple
factors,

       Only accurate and comparable measurements provide reliable
data for correct evaluation.  Measurements must be carried out by
experts according to the VDI Specifications on Efficiency Tests for
Dust Separators
       The determination of the permissible emission from an installa-
tion depends to a large extent on the conditions in the area and can
therefore be effected only on the basis of measurements which take into
account also prior existing load factors.

       These specifications are applicable only to newly designed
installations .

       Gaseous emissions including sulphur dioxide are. treated .in the
specifications on "Gas Emission".
                                - 2 -

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                            1.  Technology
1.1  The Blast-Furnaces
       The blast furnace (Fig. l) is a shaft furnace for the produc-
tion of pig iron.  The burden consists of iron ore (+ 2.$% Fe) and the
complete charge of lime stone (for slag formation) and generally also
of sinter (Cf. VDI No. 2095) and scrap together with coke.  Coke
undergoes combustion by induced draft (550-900° C) to blast-furnace
gas containing carbon monoxide.  Coke and blast-furnace gas reduce
the iron ore which is smelted into pig iron at temperatures between
1,500 and 1,800° C.  The gangue of the ore (primarily lime, silicic
acid and alumina) is transformed to slag of the same time,  A modern
blast furnace, 30 m high and with a hearth diameter of 8 m, reaches
an output of over 1,000 ton/day of pig iron.  During 1957> l8.Ii
million tons of pig iron were produced in Western Germany.

       The processes in the blast furnace include numerous complicated
physicocheraieal and metallurgical reactions which are quite difficult
to observe and supervise, especially in the lower zones of high tem-
perature (up to 1,900° C), so that the reduction and smelting process
is not even today fully., k^own in all its details,

Io2  Operating Data for Blast Furnacess
 1. Furnace
    1.1 Utilisation
    1.2 Burden and charge


    1<,3 Capacity

    I0li
    !„£ Coke
    106 Heat. s
LO6 teal/
              Production of pig iron
              Iron ore,  coke,  lime
                stone, sinter,  scrap .
              6Q°1S200 and

              600~1S200


              700-1S200
                                            Is700_at hearth (molten
                                                   to 200 at throat
                                  3
                                                        (continued)

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 2, Blast-fjarnace gas
     'factors (raw gas)

    2d Volume produced
    2,2 Chemical
    2o3 Temperature at
    2,1* Dew poiat

    2o5 Calorific vslu©

    286 Properties
Nm /t coke
                                        3S900 average
                                        Cf. Table 1
              100-300

              35-50   .
              750-=!, 100

              Cf. Table 2 and 3
Flue dust

3ol Volume of dust
3<>2 Raw~gas dust
                              % of iron
    3o3 Chemical
         composii!

    3,h Grain classifies^
              2=20

              10-50 (up to 200 in
                special cases)

              Cfo Table h
              Cf. Figs* 3 and h and
                Table 5
    hoi Type ©f
    ho2 Efficiency rate

    ho3 Dust s@paration
                                              Cfo Sec. 2ol and 2,2
Io3  Blast Furnace Gas8

       Blastt-f&rnaee gas has a high content of dust and is made poisonous
by the ©arbon snonoadLde contained in it (Table !)„  It therefore needs
to bs purified before being used as fuel gas (Table 2),  The heat and
powar aconojjy of iron smelters is based on this valuable by-product.
The modern blast furnace is completely closed so that the entire volume
of gas is recovered at the throat«  An extensive system of pipe lines,
sometimes many kilometers long, transports the gas to the individual
consumer (Fig» 2),

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                                     a - base
                                     b - hearth
                                     o - bosh
                                     d - stack
                                     e - slag runner
                                     f — iron runner
                                     g - 'tuyere
h - tuyere inlet
i - air-blast aain
k - supporting
1 - backet
• - are cart
n - ore silo
Figure 1.  Modern-Blast Furnace Installation for Pig Iron Production

    of 1,200 ton/2U hr (Steel and Iron, Vol. 7ii, 1951, P-

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(to p«wtr pUnt,
 ««fcli»9 plant and
 othtr c*MiM«rt)


  Figure 2.  Blast-Furnace Qas Distribution of

     Combined Iron Smelter and Steel Plant.


                        -6 -

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      , Blast-furnace gas is used for heating of the blast air (Cowper),
of the, smelting and annealing furnaces of the steel and rolling mills
and the press and forging units, in particular also for firing thermal
power plants, as fuel in internal-combustion engines and gas turbines,
for firing coke ovenss etc. (Table 3)»  After combustion of carbon
monoxide and hydrogen, the spent blasts-furnace gas is discharged into
the atmosphere (Cf0 Sec. 2.7).
            Table 1

    CHEMICAL COMPOSITION AND
       CHARACTERISTICS OF
 NON-PURIFIED BLAST FURNACE GAS
                                                  Table 2

                                        CHARACTERISTIC OF BIAST FUR=
                                                  NACE GAS
                                            USED AS ENGINE FUEL
CO
CO
H2
CHU
N2
S, HgS, S02, 02
. H20
Dust content
Specific unit
weights of
purified gas
(at about
9$ C02)
10=16 Vol.-g
25-30
0.5-li
0.2=3
50=60
only traces
50=60 g/tom3
10=50 g/Nm3
About 1.3
kg/Nm3
                                      )ust content
                                      Calorific value


                                      Combustion
                                       air ratio
                                                         15-35
                                                         20 mg/Nm3
                                                         about 1,000
                                                          keal/Nm3

                                                          £  0.9=1.2
       In the blast ftemse process,
about li,000 Nar of blast-furnace gas
are produced per tea ©f pig iron.
An average-sipe blast furnace fur-
nishes 3 x 10° NmVdsy of blast-fur-
nace gas, together with 50=80 ton/
day of flue dust.  As by-product of '
iron smelting, blast fwaaees in
West Germany during 1957 produced
almost 7 x 1010 Nm? of blast
furnace gas which was purified
from dust and utilized as fuel.
                                         Chemical composition and
                                           specific unit weights
                                           (Table 1) do not change
                                           during purification,,
                                                  Table 3

                                          CHEMICAL COMPOSITION OF
                                           WLSTE GAS FROM FURNACE
                                         INSTALLATIONS  FIRED WITH
                                            BLAST=FURNACE GAS
COg
N2
S02
CO, H2, Q2
Dust content




20=25 Vol.-g '
70=75
£ 8 ffig/Nm3
traces
20=50 mg/tom3
depending on
dust content
of combustion
air.

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loli  Blast"Furnace Flue Dusts

       The dust in blast-furnace gas is entrained partially out of the
charge and partially enters into the blast-furnace gas with the sublima-
tion of vaporized slag and metal.  Chemical composition^, volume and
classification of flue dust are largely dependent on the physical and
chemical characteristics of the blast-furnace charge.  Chemical com-
position and classification also change with distance from the blast
furnace through sedimentation in the gas lines: and precipitation in
the dust-removal installations.

       The volume of flue dust per ton of pig iron amounts to about
20-200 kg or 2°2C$ of pig iron production,,  In low grade non-sintered
iron ores 5 these values may rise more than twice as high.  On the
average9 the dust content lies between 10 and 09 g/Nnr but,-may attain
200 g/Nm3 in defective furnaces,,

       The coarse iron-containing dust may have grain sizes up to
several millimeters (defective furnaces may discharge pieces, larger
•Mian a fist) and is precipitated in major part already in the primary
mechanical dust-removal devices (dust bag,, turbulence filter).  The
precipitation of the fine dust containing little iron, especially of
the small grain sizes from  < 0.01 to 2/4 requires high-efficiency, dust
separators.

                               Table h

               GRAIN SHARE > 60 ^ IN BLAST FfjRNACE GAS
              Raw gas

              Precipitation in
                primary separator

              Precipitation in
                secondary separator

              Purified gas
75


85
     5*
                                  8 -

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9
                           I   V*  I     S   V

                          Particle diameter
   I  f, 5
        Figure 3.  Falling Velocity of Various Particles
            of Blast-Furnace Charge as a Function of
               Particle Diameter at 20 and 180° C
                 (from American investigations).
Specific
 weight
           a - ore dust; b - line dust; c - coke.
                 5.2
               2.3
1.2

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                                            -
                 Qrain  sise of blast-furnaoe dust.

     Figure It.  Data on Blaat-Fumace 0*8 Dust
(dust discharged  from dust bag, turbulence filter,
 dry-gas purification) from C. Popp, Steel and Iron
               Vol.  58, pp. 22U/231.



                         - 10 -

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                               Table 5

           CHEMICAL COMPOSITION OF BLAST FURNACE FLUE DUST
Substance
Fe
sio2
CaO
MgO
A¥>3
Mn
H . P
% wt.
5 - ho
9-30
7-28
1-5
U-35
0.3 - 1.5
0,3 - 1.2
Substance
S
C
Zn
Pb
Alkali
Cu

£-4/t.
To 0.1
5-10
0-35
0-15
0-20
traces

                    2<>  Reduction of Dust Emission

2<>1  Selection of Dust-Removal Installation for Blast-Furnace
     Gas Purification

       The utilization of blast-furnace gas for the operation of gas
engines and turbines requires careful purification which is carried out
in a primary and a secondary stage0  The secondary stage requires
preceding cooling and the coolers act simultaneously as additional
purifiers (Sec,, 2o2)o

       Coarse Purifications

       This is done by means of dust chambers (so-called dust bags)
and frequently also with subsequent turbulence filters (Cf. Fig,, 1)
which remove dust at efficiency rates of 50 to 80# from the blast-
furnace gas with a residue of 5=10 g/Nvr (even less with combined dust
separators),,

       Gas Coolers8

       In addition to their main purpose of cooling the gas after it
leaves the primary dust separators9 the coolers also have an additional
purification action,,  At efficiency rates of 30 *° 90#» the dust content
of the pre-purified gas is lowered to 2^5 g/Nnr0  The less effective
                                  11

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spray coolers are generally arranged ahead of bag filters and hurdle
filters, scrubbing towers, jet coolers, and simplified Venturi stand-
pipe scrubbers are placed ahead of disintegrators and wet electro-
static precipitatorso

       Secondary Purifications

       For secondary purification,, only bag filters, wet scrubbers
(such as disintegrators and in the USA frequently also Pease-Anthony
Venturi-serubbers) and wet electrostatic precipitators are suitable.
All of them require pre~eoollng and the bag filters operating at higher
temperature also secondary cooling in order to prevent condensation
of moisture in the gas lines.  The efficiency rate of these installa-
tions is over 99% and residual dust remains at 5-15 mg/tonr .

       Total Purification Installations

       During the several stages of the purification process, the
following shares of dust are precipitated from the gas s

                  Primary purification        70=80$

                  Pre-eooling                 10-20$

                  Secondary purification       3-10$

       The total purification installation lowers the dust content of
the blast=furnace gas from 10-50 g/Hm3 to 5=15 rag/ftm-3 which corre-
sponds to an efficiency rate of over 99»9%o
                                  12 -

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  2.2  Operating Data of Customary Dust Separators (3 to 7)
         The following indicates average values for properly maintained
  dust separators?
Type of
Separator
1 Dry Process

Id Dust chambers
(dust bags)
1.2 Turbulence
filters
1.3 Bag filter
(type Hal-
berg-Beth)
2o Wet Process

2ol Pre-cooler
(spray)
202 Hurdle fil-
ters, scrub-
bing towers,
jet coolers
2o3 Disintegrators
2 *h Wet electro-
static pre-
cipitators
Effi-
ciency
Rate
%

50-80
50-80
99+

30=50
50-90
99+
99+
Dust
Content
Raw Gas
g/fom3

10-50
5-10
1-5

5-10
5-10
Oo7-2oO
Oo7°2oO
Dust
Content
Pur0 gas
g/Km3

5-10
5
Oo005=0o0i5

i-£
0<,7~2oO
Oo005-0o0i5
Oo005°0o0i5
Pressure
Drop*
mm water

15-10
30+
150-300

20-50
50-200
50-100**
5=10
Utilization

Primary purifi-
cation of non-
cooled gas with
high dust con-
tents
Primary purifi-
cation of non-
cooled gas with
low dust con-
tent.
Secondary puri-
fication of pre-
cooled gas (70=
90° C),

Purification
and cooling to
70-90° c0
Purification
and cooling to
about 25° Co
< Residual dust
1=2 g/fom3 and
gas temperature
25° C0
 *  Pressure of blast-furnace gas
**  Generally as pressure rise of
at throat outlet 150=1S000 mm water„
about 50-100 mm water.
                                    13

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     Pointers for Cloth Filterss
           Effect on efficiency rate of dust separators is?
          Unfavorable                              Favorable
Excessive filter load due to
  excessive gas or dust
  volumes.


Non-uniform gas distribution,,

Sxcessive temperatures„
Jnsuitable types of clothe
Defective cloths.

remperature drop below dew
  pointo


Poor cleaning of filter cloths.
Proper selection of filter cloth
  corresponding to type of dust,
  gas temperature and composi-
  tion 07
Proper maintainance of filter
  and continuous control of fil-
  ter insulation,,

Proper dust suction devices,,
     Pointers for Mechanical Dust Separators (Bag and/or
     turbulence filters)8
           Effect on efficiency rate of dust separators iss
         Unfavorable
             Favorable
High share of fine dust«

tlon=uniform loading of several
  parallel cyclones„
Partial or overload operation of
  non=adJustable dust separator„
  Incorrect adjustment of load
  of adjustable separator.
Internal leakage due to wearj by°
  passes between single or multi-
  cyclones or cell dust separators,
Dust separators for special cases.

Uniform distribution among several
  parallel aggregates and proper
  aerodynamic design of gas lines.

Shutdown of units not needed
  under partial load.
Proper maintainance and frequent
  control of parts subject to
  wear and protection by approv
                                                      (continued)

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(continuation)
           Effect on efficiency rate of dust separators iss
         Unfavorable
             Favorable
Clogging, in particular of cells
  and dust discharges of cells
  and single cyclones.  Leaking
  valves and traps, in particular
  of dust suction devices.
Incorrectly dimensioned separators
  (the efficiency rate depends on
  the volume of gas throughput)
Prevention of temperature drop
  below dew point*  Current re-
  cording of measurable operating
  data, e.g., pressure drop and
  energy consumption (changes
  in value generally indicate
  defects and errors).

Correctly dimensioned separator
  for normal load of blast
  furnace and discharge of col-
  lected dust at proper time.
2,5  Pointers for Wet Electrostatic Precipitators;
           Effect on efficiency rate of separator iss
         Unfavorable
            Favorable-
Operational deviations from
  design data of separator, e.g.,
  of volume and velocity of
  gas (extraneous air, over-
  load), dust content and
  grain classification of
  raw gas.

Dust with varying electrical
  resistance due to changes
  in charge (iron ore, sinter,
  etc.)
Unsuitable voltage (frequent
  sparking, short circuits or
  switch-opening) .
  Inappropriate deposition or
  spray electrodes.
Gas velocity too low and time
  of passage through separator
  too long.
Optimum purification is attained
  at 20-25° C and saturated gas.
Highest possible voltage through
  full-automatic voltage regula-
  tion.  Gas flow most favorable
  for the respective type of dust
  and corresponding phasing of
  electrode voltage in the in-
  dividual chambers (pre-ioniza-
  tion).
       	(continued)	
                                - 15 -

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(continuation)
           Effect on efficiency rate of dust separator is 8
         Unfavorable                                  Favorable
Non-uniform gas and dust inflow,,
  Aerodynamically unfavorable
  construction members in dust
  chamber (dust deposition on
  girder, etc.).  Non-uniform
  distribution of dust in gas
  flow.  Inappropriate cleaning
  of electrodes (spray water),,
Poor control and maintainanee
  of the overall installation.
Uniform velocity and distribu-
  tion of dust over entire cross
  section of separator and guide
  vanes or perforated plates to
  improve inflow.  Prevention of
  dust deposition at angles in
  guide vanes and at electrodes.


Proper operation and maintainance
  of separator cleaning devices
  (spray devices) through in-
  spection of electrodess clean-
  ing of separator interior with
  chamber shut down when neces-
  sary.

Regular or automatic slurry re-
  movals properly sealed and
  proper control and maintainance
  of slurry-discharge devices|
  prevention of extraneous-air
  admission also at non-sealed
  valves (e.g. for bypass lines)

Systematic inspection of the most
  important units and regular
  control of efficiency rates
  properly scheduled overhaulj
  ewrant recording of measur-
  able operating data (changes
  in value generally indicate
  defects and errors).
2.6  Measure in Special Casess

       The dust cloods occasionally visible aft the throat of the blast
furnace during operational failures ocew only occasionally and briefly
as well as almost exclusively only in the immediate vicinity of the
blast furnaceo  Purification of these dust clouds is not possible with
any presently existing techniques.
                                - 16

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       At sane blastfurnace installations, excess and not otherwise
utilizable blast-furnace gas occurs due to several operational reasons,
and must be burnt off,, in particular during sudden operational failures.
The "torch" required for this is an integral part of the design of
the local gas-purification,,  In already existing installations, the
possibility exists of liberating prima^y-purified gas through the
"torch" with a dust content of 1-2 g/
       During starting or shutdown, the blast furnace must be dis-
connected from the gas lines and consequently also from the gas purifica-
tion installation for safety reasons and blast-furnace gas must be
burnt off directly from the blast furnace through the ""torch" but these
are exceptions of short duration0

2.7  Stacksg

       The specifications ©n Restricting Dust Emission (Cf. Sec. 3)
establish the height and number of stacks0

       In addition to the creation of the necessary draft, the most
essential task of the stack is to discharge gas and dust as far as
possible from the surface of the ground and to effect simultaneously
a reduction of the ground concentration of such discharges by a better
distribution of the smoke streamer„

       This should be attempted bys

           a)  stasks as high as possible!
           b)  velocity of gas at top of smoke stack as high
           e)  maximum possible utilisation of thermic lift of
                smoke streamer*

        	a)  The lower limit ©f staek height is given by See. 3 of
these specifications„  In view ©f th© iamsdiat® vicinitys experience
indicates that the top of the stack sh&old not be less than !<=? times
as high as th© highest bmilding in th© immediate vicinity 0

       Cf» b)  In 6©mplian©@ with Se
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be more advantageous than an arrangement of several stacks of small
diameters0  In determining the diameter of a stack, however9 partial
load factors most be taken into consideration0
            3o  Guide Lines for Restricting Dust Emission

           following factors should be taken into consideration in the
design of new blast~furnaee installationss

       1)  Restriction of Emission on the Basis of Dust Depositions

       The ©mission ©f dust ©f an installation should be restricted on
the basis ©f the permissible amounts of deposition in the vicinity and
bj the conditions ©f distribution given by the type of construction
and location @>f the plant (stack height, orographic position, adjacent
emittersp ete0)0  The existing and permissible dust level of the area
should be included therein.  (Notes  This manner of determining the
restriction ©f ©Missies! by deposition takes into account the natural
laws between ©misision, distribution and deposition.  Details of the
method should be based on the latest technical findings.  The VDI Com-
mLttee @® Air Purification issues special instructions in this regard0)

       2)  Restriction ©f Emission on the Basis of Given Technical
       Especially in view ©f the further utilization of blast=furnaee
gasa provision should be made for a technically and economically
defensible installation, corresponding to the type and capacity of the
plant,, Jfor reducing the dust content ©f purified gas0  The maximum
permissible dust ©onteat for newly designed blast-furnace installations
in continuous operation should not exceed 20 mg/frnr of purified gas
and 50 asg/m^ of the flue gases of furnace installations and other
consumers operated with blast°furnace gas0  Accordingly, blast-furnace
gas burnt off by ratorch" should be purified in the same manner.

       All newly designed blast-furnace installations should be equipped
with dust-removal installations which should meet the data on restrie«=
tion ©f emission established in Sec. 1, subjection 2 unless Sec, 3,
sub°secti^n 1 provides for higher demands.  Only such dust-removal
installations should be built which correspond to the latest technical
findings.

       The maximum values resulting from Sec. 3, sub-section 2 assume
that the raw-gas dust content specified in the order will not be
exceeded and that the specified efficiency rates will be maintained
so that the corresponding values should be guaranteed by the supplier.


                                - 18 -

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In operation of the installation, individual tolerances for any given
case should be included in the guaranty data0  If acceptance inspection
does not confirm the specified guaranty, the supplier is required to
effect the necessary changes and alterations.

       In individual cases where the requirements of Sec. 3, sub-
section 2 on restriction of emission cannot be complied with, due to
particular operational conditions not to be anticipated in the design,
exceptions can be authorized only if the dust removal installation was
designed according to the latest technical findings.
                              References

1,  VDI Specifications No. 2066 on Efficiency Tests of Dust Separators,
      2nd Ed., Dusseldorf, 19li9, new issue in preparation.

2.  Osiander, R.s  Dust Removal from Gas, A Modern Problem?  Energy,
      Vol. 9, 1957, No. 5, PP. l67/l68o

3.  Guthmann, K.s  On the Status of Blast-Furnace Purification.  VDI
      Jornal, Vol. 77 s 1933, pp. 173/176,

h.  Guthmann, K.s  Status and Development of Blastfurnace Gas Pur-
      ification During the Last 10 Years0  Steel and Iron, Vol. 61,
      19ljl, pp. 865/870, 883/891 o

5.  Idems  The Development of Blast=Fumaee Gas Purification During the
      Last 10 Tears, Steel and Iron8 Vol. 73, 1953, pp. 282/292.

60  Idems  New Findings from Measurement of Dust Content in Industrial
      Gases.  Steel and Iron, Vol. 75 9 1955, pp. 1571/1582.

7»  Idems  A Review of 25 Tears of Investigating Dust in Iron Smelters.
      VDI Reports, No. 15, Dusseldorf, 1956, pp. 5/1?.

    Further reference is made to VDI documentation on Air Purification.
                                  19

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  VDI CLEAN AIR COMMITTEE SPECIFICATIONS, PUBLISHED IN ENGLISH
  BY THE DIVISION OF AIR POLLUTION,  U.S. PUBLIC HEALTH SERVICE
VDI No.
Title
2090     Sources of Air-Polluting Substances
2091     Restricting Dust Emission From Forced-Draft Boiler Installations,
           Capacity  10 Ton/Hr and Over, Hard-Coal Fired with Mechanical
           Grates
2092     Restricting Dust Emission From Forced-Draft Boiler Installations,
           Capacity  30 Ton/Hr and Over, Hard Coal-Dust Fired with Dry Ash
           Removal
2093     Restricting Dust Emission From Forced-Draft Boiler Installations,
           Capacity  30-600 Ton/Hr and Over,  Hard Coal-Dust Fired with liq-
           uid Ash Removal
2094     Dust Prevention -  Cement Industry
2095     Dust Emission From Induced-Draft Ore-Sintering Installations
2098     Restricting Dust Emission From Natural-Draft Steam Generators,
           Capacity  25 Ton/Hr and Less, Lignite-Fired with Stationary or
           Mechanical Grates
2099     Restricting Dust Emission in Blast-Furnace Operation
2101     Restricting Dust Emission From Copper-Ore Smelters
2102     Restricting Emission of Dust From Copper-Scrap Smelters
2103     The Restriction of Chlorine Gas Emission
2104     Terminology in Air Purification
2106     Permissible Immission Concentrations of Chlorine Gas
2107     Permissible Immission Concentrations of Hydrogen Sulphide
2108     Permissible Immission Concentrations of Sulfur Dioxide
2109     Restricting Emission of Hydrogen Sulphide and Other Sulphur-Con-
           taining Compounds, Except Sulphur Dioxide, From Gas Generators
           in Coke,  Gas, and Coal-Constituent Processing Plants
2110     Restricting Emission of Sulphur Dioxide From Coke Ovens and Gas
           Plants
2115     Restricting Emission of Dust From Manually Operated Central -
           Heating Boilers, Capacity 600, 000 KCAL/Hr and Less, Fired with
           Solid Fuels
2281     Restricting the Emission of Fumes From Diesel-Engine Vapors
2284     Restricting Emission of Dust and Sulphur Dioxide in Zinc Smelters
2285     Restricting Dust and Sulphur-Dioxide  Emission From Lead Smelters
2290     Restricting Emission From Gas Generators in Coke and Gas Plants
2292     Restriction of Dust Emission in Anthracite-Briquet Factories
2293     Restricting Emission of Dust in Anthracite Processing Installations
2302     Restricting Emission of Dust, Tar Mist and Gas when Charging Coke
           Ovens
2105     Permissible Concentrations of Nitrous Gases
                                                                   GPO 869-179

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