VDI-RICHTLINIEN
June 1961
DEUTSCHER
INGENIEURE
Staubauswurfbegrenzung
Handbediente Zentralheizungskessel fur
feste Brennstoffe mit Leistungen bis
etwa 600 000 kcal/h
VDI 2115
RESTRICTING EMISSION OF DUST FROM MANUALLY OPERATED
CENTRAL-HEATING BOILERS, CAPACITY 600, 000 KCAL/HR
AND.LESS, FIRED WITH SOLID FUELS
This publication, translated from the German, was prepared by
the Sub-Committee for Small Business and Domestic Furnaces of
the Committee on Dust and Gas of the VDI Committee on Air
Purification. All rights reserved.
Reproduced with permission by the
U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
. Public Health Service
Washington, D. C.
L
VDI-Handbuch Reinhaltung der Luft
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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 EMISSION OF DUST FROM MANUALLY OPERATED
CENTRAL-HEATING BOILERS, CAPACITY 600,000 KCAL/HR
AND LESS, FIRED WITH SOLID FUELS
Prepared by:
Sub-Committee for Small Business and Domestic Furnaces
of the Committee on Dust and Gas of the VDI
Committee on Air Purification
VDI No. 2115, June 1961
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TABLE OF CONTENTS
Page
VDI Committee for Air Purification iii
Introduction 1
1. Technology ........ 2
1.1 Description of Furnaces 2
1.11 Boiler with Through-Draft 2
1.12 Boiler with Up-Draft 2
1.2 Fuels ......... 2
1.3 Operating Data ..... 3
2. Reduction of Dust and Soot Emission h
2.1 Selection of Suitable Boiler h
2.2 Selection of Suitable Fuel !?
2.3 Influences on Dust Formation 5
2.U Chimney and Chimney Flues . 6
2.hi Dimensions and Construction of Chimney 6
3. Reduction of Dust Emission 7
U* References 8
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VDI COMMITTEE FOR AIR PURIFICATION
The VDI Commitee for Air Purification is composed of experts
in all fields of importance for air purification0 These experts col-
laborate with the Committee on their own responsibility and without
compensation and are proposed for the Committee by the following
societies and institutions;
German Society for Hygiene and Microbiology
German Society for Oil and Coal Chemistry
German Society of Gas and Water Experts
German Meteorological Services
Society of German Chemists
Society of German Iron Mine and Steel Mill Experts
Association of Anthracite Mines
Technical Inspection Associations
Society of German Steel Mill Experts
Society of German Foundry Experts
VDI Trade Section on Dust Technology
Association of Steam Boiler Owners
Scientists from Universities and Institutes in Biology,
Chemistry, FovfrSwy and /-grift\attvre., Human and
Veterinary Medicine, Metallurgy, Physics, and
Technology
Research Institute of the Cement Industry
Federation of German Industry (Chemical Industry, Oil
Industry, Automobile Industry, etc»)
German Federal Railroads
Federation of German Farmers
Federation of Community Associations
Settlement Federation of the Ruhr-Coal District
Competent Federal and State Ministries
Institute for Water, Soil, and Air Hygiene of the
Federal Public Health Service
Public Inspection Services
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INTRODUCTION
The VDI Specifications on Purification of Air are divided into
the following groups 2
1. Maximum Immission Concentrations (PIC-values);
2. Calculation of the Distribution of Dust and Gas;
3. Restriction of Emission;
U. Dust and Gas Measuring Techniques,
In the evaluation of questions of air pollution, the inner
relations of these four specifications must be taken into considera-
tion.
These specifications are applicable to warm-water and low-
pressure central-heating boilers with furnaces for solid fuels5
capacity 600,000 kcal/hr and less, operated manually under natural
draft (no blower).
It is the task of the specifications:
to characterize the causes leading to the formation of dust
(fly-ash, cinders, and eventually together with soot and other non-
gaseous and combustible components) from central-heating boilers for
solid fuels;
to recommend measures for the reduction of dust emission;
to establish guide lines for the restriction of permissible
immission.
The measures recommended in the specifications take into account
the latest technical findings. The guide values for the restriction
of emission will be adapted to further technical developments.
Sections 1 and 2 give indications on the range of utilization
of these specifications and the technical possibilities for the reduc-
tion of dust and soot emission„ Section 3 contains the restricting
factors (upon publication of specifications No. 2050 now in preparation,
Sections 1 and 2 will be adapted to the latter).
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1. Technology
1.1 Description of Furnaces?
1.11 Boiler with Through-Draft (Fig. l)j
Through-draft is a method of burning solid fuels in which the
entire fuel charge becomes incandescent and in which the height of the
fuel bed decreases during combustion.
1*12 Boiler with Up-Oraft (Fig. 2)s
Up-draft is a method of burning solid fuels in which only the
bottom layer of the fuel charge becomes incandescent and the burnt
fuel is continuously replaced from a silo so that the height of the
incandescent layer remains uniform.
1.2 Fuels (2)s
The instructions of the boiler manufacturer in regard to the
selection of fuel must be strictly complied with.
Fuels for Customary Boilers
Crushed coke No. 1 80-60 mm
Crushed coke No. 2 60-UO mm
Crushed coke No. 3 UO-20 mm
Anthracite nut No. 1 80-50 mm
Anthracite nut No. 2 50-30 mm
Fuels for Special-Design Boilers
Crushed coke No. h pearl coke
Non-caking nut coal Nos, 1-lj, anthracite briquets, lignite
briquets, lignite coke, peat and wood develop gases in combustion which
burn with flames of greater or lesser length. Economical combustion
with minimum development of smoke and soot is possible for these fuels
in special boilers with secondary air supply, large combustion chamber,
etc.
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Figure 1. Domestic
Boiler Furnace
with Through-
Draft Combustion.
Figure 2. Domestic
Boiler Furnace
with Up-Draft
Combustion
(1) Fuel bed; (2) Combustion airj
(3) Boiler and chimney flues.
Caking coal and coal waste are unsuitable for combustion.
1.3 Operating Data:
The following indicates average values of actually constructed
installations at nominal rating for boilers of customary design fired
with coke and anthracite.
Flue gases at smoke box
Temperature in C
CO - content in percent (of dry flue gas]
Dry flue gas volume in NnP/kg of fuel at
Amt.
Dust
in mg/kg fuel
Concentration in mg/Nm^
Coke
100-500
10-50
150-300
\ 12-16
11.3
Anthracite
to 700
to 70
at 12-16 CO,,.
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Table 1
AVERAGE COMPOSITION AND CALORIFIC
VALUE OF SOLID FUELS
Character-
istics
Volatile com-
Coke
ponents in rela-
tion to water
and ash free
substance in
percent.
Ash content in
relation to
• raw substance
in percent.
Sulphur content
in relation to
raw substance
in per cento
Calorific value
in relation to
raw substance
in kcal/kg.
5-10
0.7-1
6,200*-6,900
Anthracite
6-1? as
well as
over 37
3-7
O.S-l.li
6,900-7,900
Lignite
Briquets
55-60
5-10
O.li-1.8
ii, 700-5, ooo
Peat
70
Wood
70-75
of air-dry
substance
O.ii-9
about
3,500
0.2-0.8
about
3,500
Depending on grain size corresponding to VDI Specifications No. 2067.
2. Reduction of Dust and Soot Emission
2.1 Selection of Suitable Boiler;
Central heating boilers should offer proper structural pre-
requisites to prevent emission of dust into the atmosphere. Particular
attention must be given to proper air-flow design of combustion chamber
and boiler flues.
Design, construction and any rebuilding of central-heating
boilers should be done by experts. The regulations of the local
building construction office should be complied with (U).
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2.2 Selection of Suitable Fuel:
As far as possible, only fuels with low gas content should be
utilized in central-heating boilers (Table 1).
It is recommended to seek the advice of experts, e.g., boiler
and fuel suppliers, in the selection of the most suitable fuel for
given conditions. The operating instructions of the boiler manufacturer
should be strictly complied with.
2.3 Effective Agents;
table 2
FACTORS INFLUENCING DUST FORMATION
Point of
Origin
Of. Pig
1 and 2
Affecting the formation of dust and soot
Increasing Reducing
Fuel
High content of breeze.
Grain size too small.
High content of volatile
components. Combustion
of waste in large
aaounts.
Careful handling of fuel to
reduce formation of breeze,
e.g., when delivering to
seller, during storage
(protection from weather).
Prevention of grain unmixing
when charging fuel.
Correct selection of grain
size corresponding to the
operating instructions of
the boiler manufacturer.
Prevention of soot formation
through correct supply of
primary and secondary air.
Utilization of fuel with
low gas content, e.g., coke,
Fuel
bed
Excessive stoking
Unsuitable grants con-
struction.
Careful stoking only when
required.
Special grates corresponding
to type of fuel.
(continued)
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(Continuation of Table 2)
Point of
Origin
Cf. Fig
1 and 2
Increasing
Reducing
Combus-
tion air
Excessive air velocity
in fuel bed (high
draft intensity),
high grate-surface
loading, poor air
distribution, non-
uniform fuel layer,
grate not clean.
Correct draft intensity
adjusted to operating
instructional of boiler
manufacturer.,
Throttling of draft and
balanced height of fuel
layer „
Boiler
and stack
flues
Excessive velocity of
combustion gases due
to restrictions
(clogging). Excessive
utilization of paper,
excelsior, wood for
fire making.
Correct dimensions and
regular cleaning of boiler
and stack flues. Correct
dimensions and uniform
distribution of fire-
making material on grate.
Igniting with gas jet.
2.k Chimney and Chimney Flues:
Dust and soot in furnaces is reduced by constructing a suitable
chimney for each such furnace as provided by building construction
regulations (6). Chimneys must discharge flue gases into the atmos-
phere in such manner that no danger or annoyance is created.
The regulations of local building construction services and
technical specifications (building codes and standards) must be observed
in the dimension and construction of the chimney (k» 5s 6, 79 8).
New methods of construction (assembly of standard unit parts), where
permitted, are preferable.
2.1|1 Dimensions and Construction of Chimneys
Any furnace with a capacity of more than 20^000 kcal/hr must
have its own chimney to which neither other furnaces nor ventilation
systems may be connected. In the interest of air purification, central-
heating boilers and air heaters with a capacity of less than 20,000
kcal/hr should also have their own chimney.
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Masonry or concrete connecting ducts between furnace and chimney
as well as smoke pipes of sheet steel should not exceed a length of
2$% of the chimney height. They should be installed with a rise of
not less than 1C# and should convey the flue gases over the shortest
possible distance. The chimney must be tight and smooth on the interior
and have a uniform cross section. It is preferable for the latter to
be round or a,^. . Chimneys with rectangular cross sections should
have the long side not longer than 1.5 times that of the short side.
Chimneys should not be located in exterior walls and should be arranged
so that they are protected against heat loss (this is particularly
applicable to flue gas ducts and sheet-steel chimneys). At points
where chimneys are exposed to cooling, they should be equipped with
suitable heat insulation.
Height of chimney;
Unless the volume of sulphur-dioxide emission requires greater
minimum heights, the opening of the chimney should lie preferably 1 m
above the ridge pole. Roofs with a slope of less than 3Q£ should have
the calculation of chimney height based on assuming a hip roof of at
least 3Q# slope. Draft reducing influences in the vicinity and un-
favorable influences for the distribution of the flue gases (trees,
buildings, hilly terrain) should be especially considered in determining
chimney height.
3. Reduction of Oust Emission
The following factors should be taken into account when con-
structing new central-heating boilers for solid fuels. The boilers
should be operated only with the types and grades of fuel recommended
by the boiler manufacturer.
When burning coke or anthracite, dust emission is so minor
(Cf. Sec. 1.3) that it is not necessary to establish any degree of
restriction. When burning other types of coal as well as peat and
wood, unfavorable conditions of combustion may lead to a visible dis-
coloration of the flue gases through emission of dust and soot. This
discoloration makes it possible to utilize the method of optical com-
parison developed by Ringelmann.
The maximum permissible blackness of flue gases when burning
coal with high gas content, peat and wood should be kept below No. 2
of the Ringelmann scale.
The particular degree of blackness of the discharge from a
given chimney can be determined by the utilization of an optical in-
strument with built-in three-part filter disc corresponding to the
values of the Ringelmann scale.
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Gravimetric methods of measurement permitting reliable, exact
and simple determination of discharge volumes from central-heating
boilers do not yet exist.
it. References
1. K. Lenhart and ¥„ Egenlof: Measurement of Emission from Central-
Heating Boilers. Dust, Vol. 18, 1958, No. 6, pp 169/73.
2. VDI Specifications No. 2072 on Fuels and Their Thermodynamic
Utilization.
3. Proposed Standard Building Code for Individual Lander of West
Germany.
U. Currently Applicable Building Codes of the Individual Lander.
5. VDI Specifications No. 2050 on Construction and Equipment of
Central-Heating Furnace Rooms and Fuel-Storages Spaces.
6. DIN No. Ijl08, Heat Insulation in Above-ground Construction.
7. DIN No. i;705, Calculation of Clear Cross Section of Chimneys for
Central Heating.
8. DIN No. 18,160, Sheet 1, Furnace Installations and Domestic
Chimneys. Specifications for Dimension and Construction.
9. Ringelmann: Smoke Chart, Charles Griffin and Co., Drury Lane,
London, WC 2.
10. DIN, No. ii702, Domestic Heating Boilers. Rules for Calculation.
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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 6CO, 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 869-17*
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