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Fact sheets on air emission abatement techniques

File: B8176 Registration number: MD-MV20090007 Version: 3 VITO/InfoMil February 2009

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Table of contents

1 Introduction ................................................................................................ 5

2 Research lay-out and results ....................................................................... 6

3 Use of the fact sheets .................................................................................. 8 3.1 Selection and application of air emission abatement techniques ..................... 8 3.2 Lay-out fact sheets..................................................................................11 3.3 Sub-division of techniques........................................................................12

4 Fact sheets ................................................................................................ 14

4.1 Gravitation .............................................................................................14 Settling chamber / Gravitational separator ........................................................................... 15 Cyclone / Dust cyclone / Wet cyclone / Multi-cyclone / Vortex separation ................................. 18

4.2 Scrubbing ..............................................................................................22 Scrubbing (general) / Wet dust remover / Wet dust scrubber.................................................. 23 Spraying tower / Rotational scrubber / Dynamic scrubber ...................................................... 26 Venturi-scrubber / Venturi-scrubber / Whirl scrubber............................................................. 29

4.3 Filtration ................................................................................................32 Fabric filter (filtering dust separator) / Tube filter / Bag filter .................................................. 33 Ceramic filter (filtering dust-separator) / Ceramic filter / High temperature filter / Candle filter.... 37 Two-stage dust filter......................................................................................................... 40 Absolute filter / HEPA-filter / surface filter / cartridge filter / micro filter ................................... 43 Demister / Aerosol filter / Deep bed filter............................................................................. 46 Dry electrostatic precipitator / Electrostatic precipitator (ESP) / Dry E-Filter / Dry ESP / Dry electrostatic precipitator / Electro filter ........................................................................ 48 Wet electrostatic precipitator / Wet E-filter / Wet ESP / Wet Electrostatic precipitator / Electro-filter .................................................................................................................. 51

4.4 Condensation..........................................................................................54 Condenser / Heat exchanger / Odour control condensation (OCC) ........................................... 55 Cryocondensation / Cooled condensation ............................................................................. 58

4.5 Adsorption..............................................................................................61 Adsorption (general)......................................................................................................... 62 Adsorption of active coal / Active coal filtering / Coal filter...................................................... 65 Zeolite filter (adsorption) / Zeolite filter / Hefite filter ............................................................ 69 Polymer adsorption........................................................................................................... 72 Dry lime injection / dry lime-sorption / Fixed bed lime-sorption / Cascade adsorption................. 75 Semi-dry lime injection / Spray-dry adsorption / Semi-dry lime adsorption / Semi-wet lime sorption ................................................................................................... 78

4.6 Absorption..............................................................................................81 Gas scrubber (general) / Scrubber / Absorber / Air scrubber................................................... 82 Acid gas scrubber / Acid scrubber ....................................................................................... 85 Alkaline gas scrubber........................................................................................................ 88 Gas scrubber alkaline-oxidative .......................................................................................... 91

4.7 Biological cleaning...................................................................................94 Biofiltration / Bio-bed / Biological filter / Bio-bed filter / Compost filter..................................... 95 Biotrickling / Lavafilter / BTF / Biodenox .............................................................................. 99 Biological scrubber (general) / Bioscrubber / Bioscrubber ..................................................... 102 Moving bed trickling filter / MBTF...................................................................................... 105

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4.8 Thermal oxidation .................................................................................108 Thermal incinerator / Incinerator / Thermal oxidation .......................................................... 109 Catalytic incinerator / Catalytic oxidation (catox) / Thermocat............................................... 113 Flare ............................................................................................................................ 117

4.9 Cold oxidation.......................................................................................121 Ionization / Active oxygen injection / Ozone injection / Plasma cleaning ................................. 122 Photo oxidation / UV-oxidation ......................................................................................... 125

4.10 Chemical reduction................................................................................127 Selective non-catalytic reduction / SNCR ........................................................................... 128 Selective catalytic reduction / SCR.................................................................................... 130 Non-selective catalytic reduction / NSCR............................................................................ 133

4.11 Other techniques...................................................................................135 Membrane filtration / Solvent recuperation / Air separation with membranes .......................... 136 Vapor recovery unit / VRU ............................................................................................... 139

5 Additional research on specific techniques .............................................. 140 5.1 Techniques...........................................................................................140 5.2 Field-testing of emissions.......................................................................143

6 Cost effectiveness.................................................................................... 144

7 Recommendations for future research..................................................... 145

8 Index ....................................................................................................... 146

9 Annexes................................................................................................... 147 Annex 1 Field emission data.................................................................................148 Annex 2 Illustrative calculations of cost effectiveness..............................................149 Annex 3 List of suppliers who provided information.................................................150

10 Colophon .............................................................................................. 151

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1 Introduction

The fact sheets with basic information on air emission abatement techniques are meant to answer the most frequently asked questions on these techniques. They are an aid in determining the Best Available Techniques (BAT) in specific situations. They also are the Dutch and Flemish input in the revision of the BREF Wastewater and gas treatment for the chemical industry. The fact sheets give a brief description of the functioning, efficiency, financial aspects, etcetera of the air emission abatement techniques that have proven to work in the field. Because of the standardized lay-out the information is easy to find. Based on the fact sheets a first selection of the possible techniques for a specific application can be made. The primary target audience of the fact sheets are the competent authorities, advisors and companies that are not or barely familiar with the techniques. For detailed technical information one can contact the suppliers. The precursor of this document, publication, L26 ‘Fact sheets waste gas treatment techniques’ (2000), was issued in 1999. On behalf of InfoMil, DHV has researched the topicality of the fact sheets en renewed them where necessary. The revision of the BAT Reference document (BREF) Waste gas and water treatment for the chemical industry was a reason to check the fact sheets for topicality. The information in these renewed fact sheets was offered as information for the revision of this BREF. The range of application of the fact sheets however, is broader than just the chemical industry. In the Flanders region of Belgium, VITO provides similar information fact sheetvia ‘LUSS’ (starting 2004). LUSS is a system that may help with first explorations and final decisions on possible air pollution abatement techniques. This system is digitally available through http://www.emis.vito.be/luss/.

The renewal of the fact sheets took place in close cooperation with research institute VITO and with suppliers, companies and governments. The research consisted of: a) Literature study (including LUSS and BREFs); b) Survey among Dutch suppliers; c) Interviews with suppliers, companies and the competent authoritiy. This manual is restricted to air emission abatement techniques that are currently applied on an industrial scale. Techniques that are only applied on a research or laboratory scale are not described in these fact sheets. Distinction between the techniques is based on their working principle, such as: gravitational separation, filtering and adsorption; the most important implementations are described in the fact sheets. The before mentioned techniques represent the majority of air emission abatement techniques in existence, although not every single existing technique can be found in this manual. Reading directions In chapter 2 the research and the resulting conclusions are briefly explained. Chapter 3 explains the use of the fact sheets, including an overview of the described techniques and the most critical parameters per technique. Chapter 4 contains the 36 fact sheets in total. Chapter 5 displays the results of further research on some techniques. These techniques are relatively new or interesting for further research, for different reasons. For a number of techniques the topicality of the previously determined emission ranges was also judged. In chapter 6 some examples are given of cost effectiveness calculations. Chapter 7 gives an overview of the missing information (blank spots).

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2 Research lay-out and results

The predetermined lay-out of the renewal of the fact sheets is displayed in general outlines in figure 1. The research project was guided by a commission wherein the competent authority, the suppliers, the industry, the Ministry of VROM and InfoMil were represented.

Figure 1. Research project renewal fact sheets

Existing sheets

3.3. questionnaire suppliers

3.5. Interviews selected suppliers

3.1. Desk study, first analysis

3.4. Analysis 2

3.6. Report & updated sheets

1st updated sheets

BREF, EPA, LUSS, literature, cost assessment

Kick off meeting

Meeting with project

committee

Final meeting

Input from literature, competent authorities,

Emission reports, permits

The research plan assumed that for the renewal of the data, information would be gathered from literature and from the internet (point 3.1 from figure 1), as well as from the market (point 3.2 in figure 1). The key literature and internet sources used are: BREFs, LUSS and the US Environmental Protection Agency (EPA).

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In gaining information from the market, the suppliers played an essential part. By means of amonst others a surveythey were interviewed about recent market developments regarding their products. Over 80 suppliers were summoned and asked to answer a number of questions regarding costs, new techniques and changes in techniques in their range of products. The Organization of Suppliers of Environmental Equipment (VLM, about 30 members) approached its its membersabout. In spite of this, the response of the suppliers was low: about 15%. An important consequence of this low response is that the indexation of the costs is primarily based on data from literature and only very little upon data from suppliers. Simply applying an index number on the old economical numbers turned out to be impossible in a number of cases. In one case the costs had decreased (minimum caustic scrubber), while in another case the costs have remained the same or have risen sharply (active coal). The suppliers that did respond reported that the development of air emission abatement techniques is slow. The techniques evolve, but there are no reports of revolutionary developments. However, new variants of existing techniques and optimizations are reported. These developments can be described as the fine-tuning of existing techniques. A different development is the application of existing techniques within different sectors. Stricter environmental legislation (emission requirements) within a specific sector is often the cause . Chapter 5 further investigates the developments as reported by the suppliers and competent authorities. The research lay-out also aimed at verifying the efficiency and emission values through use of measurement reports. Measurement reports were collected from the competent authorities, suppliers of installations and from open information sources (internet). In practice it sometimes turned out to be difficult to get clear to what specific configurations of techniques the measurements apply. For this reason fewer measurements were collected than was planned. In Annex 1 the gathered emission values are further investigated.

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3 Use of the fact sheets

3.1 Selection and application of air emission abatement techniques

The factsheets containing basic information on air emission abatement techniques serve as an aid in selecting the Best Available Techniques (BAT) in specific situations. The described techniques can be applied after checking the applicability of process integrated measures for preventing or decreasing the environmental impact, for example by switching to different raw materials or recycling of emission streams. If this is not feasable, air emission abatement techniques are to be considered. In order to make a first selection of air emission abatement techniques, an overview-table (table 3.1) is included. With the aid of this table a first choice can be made based on the component to be removed, the flow or other critical process variables. For a first selection of techniques for removing (fine) dust, figure 2 can be used as well. For example, in figure 2 one can find that a cyclone and gravitation-separator are effective at a larger dust load (about 10 g/m³) and particle size (>µm 10), while a wet scrubber is more effective for a smaller dust load and particle size. Sometimes a combination of techniques is necessary to attain a low emission value.

(Source: D.R. Woods, Process design and engineering practice, Prentice Hall PTR, New Jersey, ISBN 0-13-805755-9)

After the first indicative selection of techniques (table 3.1), the corresponding fact sheets may be used to compare the techniques’ most important features and to further consider their application in the situation concerned. Further elaboration may be needed for the preferred technique, requiring more information than that offered in the fact sheet. In that case one may decide to search for further expertise or information. One example of this is

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the calculation of a techniques’ cost effectiveness. The fact sheets do not always provide sufficient information for calculating the cost effectiveness in a specific situation according to the NeR1-method 4.13 (see also chapter 6). Table 3.1. The table below indicates which chemicals can be removed by use of a specific air emission abatement technique. If a technique’s primary goal is not the removal of a specific pollution, but this pollution is (partly) removed by the technique, this is indicated by a ‘+’.

Removed components Parameters Working

principle Name technique

Dry

dust

Wet

dus

VO

C

SO

2

NO

x

NH

3

Inorg

anic

gas

ses

Odour

Eff

icie

ncy

[%]

Indic

atio

nof

applie

dflow

[m3/h

]

Critica

lpar

amet

ers

Sinking chamber

� � 10 -90 100 – 100,000

Fluid percentage Gravitational separation

Cyclone � � 5 - 99 1 – 100,000 Fluid percentage

Dust scrubber

� � � � � � � 99 720 – 170,000

Pollution

Spray tower � � � � � 70 - 99 1,000 – 50,000

Temperature, pollution

Dust scrubber

Venturi scrubber

� � � � � � 50 -99 720 – 100,000

Fabric filter

� 99.95 300 – 1,800,000

Temperature, fluid percentage

Ceramic filter

� 80 – 99.99

300 – 1,800,000

Stickiness

Two-stage dust filter

� < 75,000 Ingoing gas flow and speed

Absolute filter

� 99.99-99.999

100 - 360 Fluid percentage

Demister � � � 99 90

< 1,000,000

Gas scrubber

� � � � � � 30 – 99 50 - 500,000

Temperature Absorption

Acid gas scrubber

� � � � � � 80 - 99 50 – 500,000

Temperature

1 NeR is short for ‘Nederlandse emissierichtlijn lucht’ (Netherlands emission guidelines for air).

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Removed components Parameters Working principle

Name technique

Dry

dust

Wet

dus

VO

C

SO

2

NO

x

NH

3

Inorg

anic

gas

ses

Odour

Eff

icie

ncy

[%]

Indic

atio

nof

applie

dflow

[m3/h

]

Critica

lpar

amet

ers

Alkaline gas scrubber

� � � � � � 90 - 99 50 – 500,000

Temperature

Gas scrubber alkaline oxidative

� 80 – 90

50 – 500,000

Temperature

Bio filtration � � 70 – 95 100 - 100,000

Temperature

Bio trickling � � � � 70 – 99 1,000 - 500,000

Temperature

Biological scrubber

� � � � 70 – 95 - Temperature

Biological cleaning

Moving bed trickling filter

� � �80 - >

98

5,000 - 40,000

Temperature

Thermal incinerator � � �

98 – 99,9

90 – 86,000 Ingoing concentration VOC

Catalytic incinerator � � � 80 – 99

90 – 90,000 ingoing concentration VOC

Thermal oxidation

Flare � > 99 < 1,800,000 Caloric value of ingoing gas

Ionization � � � 80 – 99.9

20 – 200,000

Fluid percentage of ingoing gas

Cold oxidation

Photo oxidation

� � � � 80 -98 2,000 – 60,000

Temperature, fluid percentage

Selective non-catalytic reduction

� � 40 -70 < 200,000 High T required

Selective catalytic reduction

� � 80 - 97 < 1,000,000 High T required

Chemical reduction

Non-selective catalytic reduction

� � � 90 – 98

< 35,000

Remaining techniques

Membrane filtration

� � 99.9 < 3,000

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3.2 Lay-out fact sheets

Title / synonyms First a common name for the technique concerned is given as a title, followed by synonyms that are used in practice . Brief description Here the main description of the technique is given. The abatement principle is clarified using a schemetic diagram. Often VITO provides a more extensive description: http://www.emis.vito.be/Luss/. Applicability Under this heading the industrial sectors are listed wherein these techniques are often applied. The list is not always exhaustive and the application of the technique in other sectors than indicated is possible. Also the efficiency, remaining emission and the quality of these data are listed here. The quality of the information is divided into three categories: - Validation number 1 means no validation: the numbers are not substantiated by

measurement reports. - Validation number 2 means limited validation: when measurements weren’t directly

presentable or available, for example when measurements are mentioned in an environmental permit or measurements taken by a non-certified agency.

- Validation number 3 means validation: the numbers are substantiated by at least one measurement report.

The efficiency and emission data used here are those gained from suppliers and/or competent authorities. The values were often gained under different circumstances and in specific situations and thus must be regarded as indicative. The preconditions and process conditions are of great importance and are often presented as a wide range. The wide ranges are a result of the often wide variety in possible applicability of a technique. Measured values are based upon half-hour average values as prescribed in the NeR. Elaborate description Some techniques have a strong resemblance to the described technique and may be seen as a variant of this technique. In those cases they are referred to in the fact sheet as a variant and are not described in a separate fact sheet. The variants can be found easily through the index in the back of this document. Qualitative criteria for design and maintenance are also described under this heading. The quantitative information on maintenance, when available, is listed under the financial aspects. The elaborate description also further examines the monitoring. A brief consideration is given of the points of interest. Monitoring is a very important and complex aspect of air emission abatement techniques and the corresponding emissions of residues. A further observation of this subject falls outside of the range of the fact sheets and for this we refer to the specific literature and legislation on this subject like the NeR and BEES (Netherlands decree on emission limits for combustion plants). Environmental pros and cons The pros and cons listed here apply to the application of the technique in an “average situation”. In specific situations these pros and cons won’t all apply. The cross media effects may imply an important pro or con for the environment and are mentioned here for this reason. Also the use of additional materials, which is connected to the assessment, is mentioned here because it may affect the choice of a technique in a severe(ly) (negative) manner.

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Financial aspects The ranges mentioned give an indication of the costs. The exact costs of course depend on the specific conditions, situation (existent or not) and configuration of the technique. The costs apply to operational costs and investment costs. These costs can be subdivided further, for example into fixed costs, like maintenance and operation, and variable costs like gas, water, electricity and residue processing (see method 4.13 from the NeR). Operational costs in the fact sheets basically imply all these costs, unless otherwise indicated. As many nuances as possible were taken into consideration. Where possible the personal costs, or utility costs (including electricity) are explicitly mentioned. The aforementioned investment costs apply to the bare purchase price. Additional and single investments may far exceed this purchase price, especially in existent situations. Chapter 6 offers examples for calculating the cost effectiveness of several techniques. Information source Here the most important reference documents used to test the existing information (L26) are listed. Besides the documents listed under this heading especially the suppliers (Annex 3) and the competent authorities (paragraph 5.2) were an important source of information for this research.

3.3 Sub-division of techniques

In chapter 4 the techniques are divided as follows: Gravitation (paragraph 4.1) Techniques that are based on the principle of separation by gravitation or gravity include the settling chamber and the cyclone.

Dust scrubbers (paragraph 4.2) The dust scrubbers are techniques where the separation of dust and air takes place by means of using the medium water. The techniques described here include the scrubbing (general), the venturi scrubber and the spraying tower.

Filtration (paragraph 4.3) Filters work based on a filter medium that filters the dust from the incoming polluted gas. The dust remains on the filter. The filter medium may consist of a fixed filter that the gas stream and particles must pass, like a fabric filter, or an electrical field with collectors, like the electro filter. Six different applications of this technique are described in the fact sheets: fabric filter, ceramic filter, two-stage dust filter, absolute filter, demister, dry electrostatic precipitator and wet electrostatic precipitator. Condensation (paragraph 4.4.) The techniques that belong to this group are based on the principal of separation by cooling through means of a cooling medium and a lowering of the vapor pressure of a component that is to be removed. Applications mentioned here are the condenser and cryocondensation.

Adsorption (paragraph 4.5) Adsorption is a reaction binding the polluted components to a solid or liquid, adsorbing it and removing it from the incoming gas stream. Six different applications of this technique are described in the fact sheets: adsorption (general), active coal, zeolite filter, polymer adsorption, dry and semi-dry lime injection. Absorption (paragraph 4.6) With absorption, as opposed to adsorption, no chemical reaction takes place. In the wet absorption section however, an exchange does take place between the absorption medium and the component to be removed. The techniques described here are four different applications of gas scrubbers: gas scrubber, acid gas scrubber, alkaline gas scrubber and gas scrubber with alkaline oxidative.

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Biological cleaning (paragraph 4.7) In case of biological cleaning, the incoming gas stream is led through a column or filter bed consisting of micro organisms on a carrier material. The micro organisms break down the pollution. Four techniques based on this principle are described in the fact sheets: bio filtration, bio trickling, biological scrubbing and Moving Bed Trickling Filter (MBTF)

Thermal oxidation (paragraph 4.8) Thermal oxidation implies the combustion of incoming gas streams at high temperatures. Described are: the thermal incinerator, catalytic incinerator and flare. Cold oxidation (paragraph 4.9) As opposed to thermal oxidation, in case of cold oxidation no rise in temperature occurs. Charged particles cause a breakdown and partial oxidation of any present pollution. The techniques described here are: ionization and photo oxidation. Chemical reduction (paragraph 4.10) Chemical reduction stands for the removal of a polluted component by injecting a reducing reagent, like ammonia, into the incoming gas. Three techniques are described in the factsheets: SNCR, SCR and NSCR.

Remaining techniques (paragraph 4.11) Two techniques are presented here: membrane filtration and vapor recovery, which can either be seen as a combination of techniques or cannot be easily fitted into one of the other categories.

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4 Fact sheets

4.1 Gravitation

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Settling chamber / Gravitational separator

Brief description Description The gas stream is led into a room where dust, aerosols and/or drops are separated from the gas under influence of gravity and momentum. Because of the sharp drop in gas speed in the settling chambers the larger particles will sink under the influence of gravity. The separating effect becomes more effective because of the change in the gas’ flowing direction and the collision of particles and partitions, plates or metallic gasses. Settling chambers are primarily used as pre-separators.

Schematic diagram

Applicability Great range of applicability in the following sectors: - wood and furniture industry - construction sector - brickyards - glass industry - storage and handling - ferro and non-ferro: removal of dust for the protection of techniques in sequence. Settling chambers are also very suitable for the removal of hot or glowing particles before the gas stream is led to an additional technique.

Settlingchamber

Gas flow in Clean gas

Dust particles

Dust discharge

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Components Removed components

Removal efficiency1, % Remaining emission, mg/m03

Validation number

Dust 10 – 90 High; > 100 is possible

1

1 Depending on the specific configuration and the working conditions. Values are based upon half-hour averages. The settling chamber’s efficiency is strongly dependant on particle size; large particles are neatly removed, smaller particles less so.

Preconditions Gas flow, m03/h 100 – 100,000 Temperature, ºC No limitation, at least up to 540 Pressure, bar No limitation Pressure drop, mbar Little Fluid percentage Above dew point Dust, g/m03 No limitation

Elaborate description Variations - Gravity counter stream separator: The flow direction of the incoming gas in the

separator is vertical. Under influence of gravity the particles settle in the opposite direction of the flow direction.

- Gravity diagonal stream separator: Here the flow direction of the incoming gas in the separator is diagonal. Under influence of gravity the particles settle perpendicular to the flow direction.

- Impact filter: Because of the implementation of multiple obstacles, such as plates, the gas stream is redirected. The particles cannot follow the stream direction due to their slowness and thus are removed.

Installation: design and maintenance Settling chambers may be constructed out of various materials, including steel and synthetic material, depending on the composition of the incoming gas stream. In the application of settling chambers a good uniform speed distribution is essential. Preferential streams have a negative effect on the functioning of the settling chamber. By using internal obstructions one can work at higher speeds, resulting in a smaller settling chamber. Downside to this is the increase in pressure drop on the system. Leakage of cold air into the settling chamber must be avoided to prevent condensation of the gas stream. Condensation may lead to corrosion, dust accumulation and obstruction of the dust outlet. Monitoring The most frequently occurring cause of malfunction is obstruction of the chamber by dust. This can be prevented through constant monitoring and periodical inspection of the chamber. Environmental pros and cons Specific pros - Reasonably suitable for the removal of large and midsized particles (> 15 µm) - Simple construction - No moving parts - Low investment costs - Simple management - Low maintenance - Low pressure drop - Low energy consumption - Can be constructed to specifically apply in extreme conditions, for example high and

low temperatures Specific cons - Low removal efficiency - Unsuitable for the removal of smaller particles, mostly suitable as a pre-cleanser of

rough particles

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- Unsuitable for sticky particles - Large machine. Additives Settling chambers do not use additives. In some specific Applicabilitys (like the drip separator), a settling chamber has cleaning system to keep the partitions and plates clean. The amount of water needed for this depends on the applicability. It can range between 100 – 200 liters/m².

Cross Media Effects The separated dust has to be carried off, and it may be conveyed as regular or chemical/hazardous waste depending on the incoming gas stream’s composition. Sometimes the dust can be recycled into the process.

Financial aspects Investments, EUR/1,000 m03/h Small if the system is integrated into other systems

(Large inlet or convoy partition). Exact value is hard to determine.

Operational expenses, EUR/1,000 m03/h Low Personnel Very little Help and additives None Energy consumption, kWh/1,000 m03/h Low, just for the ventilator Electricity costs, EUR/1,000 m03/h Low, just for the ventilator Cost-determining parameters Pressure drop, (if relevant) costs of conveying dust Benefits None, (if relevant) recovery of raw materials

Information source 1. Description of air emission abatement techniques, L26 Infomil/Tauw, March 2000. 2. Guide on air cleaning techniques, VITO 2004/IMS/R/066. 3. IPPC Reference document on Best Available Techniques in Common Waste Water and Waste Gas Treatment Management Systems in the Chemical Sector, February 2003. 4. Dutch Association of Cost Engineers, edition 25, November 2006. 5. US EPA CACT Air Pollution Control Technology Factsheet (http://www.epa.gov/ttn/catc/dir1/fsetling.pdf)

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Cyclone / Dust cyclone / Wet cyclone / Multi-cyclone / Vortex separation Brief Description Description The contaminated gas stream is passed into the cylinder shaped chamber. The dust is swung to the wall by the centrifugal force, after which the dust is carried of through the bottom. The purified gas leaves the cyclone in the middle at the top. The gas entering is forced to move down past the inside of the cyclone in a circular motion, and at the bottom of the cyclone the incoming stream reverses and leaves the cyclone at the top.

Schematic diagram

Applicability Because of its relatively small efficiency and relatively high residue emission a cyclone is used as pre-separator to take away the largest dust load, followed by, for example, a scrubber or fabric filter. The pre-treatment usually applies to particles > 5 µm.

Broad range of application in the following sectors: - wood and furniture industries - construction industry - glass industry - transport industry (storage and handling) - food industry - waste incineration - chemical industries - melting processes in metallurgy - sintering processes - coffee roasting

Dust removal

Cyclone

Gas flow inClean gas

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Components Removed components

Removal efficiency1, % Remaining emission, mg/m03

Validation number

Dust (< 1 µm) Dust (6-10 µm) Dust (> 10 µm) Dust (> 50 µm)

550 90 99

--100 -

1121

¹Depending on the specific configuration, operational conditions and reagents. Values are based upon half-hour averages.

Preconditions Gas flow, m03/h 1 – 100,000 Pressure, bar Not critical Pressure drop, mbar 5 – 20 Temperature, oC Dependant on the construction; may be very

high

Dust, g/m03 Up to dozens

Extensive description Variations - High throughput cyclones have a diameter of more than 1.5m and are suitable for the

removal of particles 20 µm and up. - High efficiency cyclones have a diameter that varies between 0.4 and 1.5m and are

applicable for the removal of particles 10 µm and up. - Multi-cyclones are constructed in parallel out of cyclones with a diameter ranging

between 0,005 and 0,3m. Here the gas feed occurs tangential or axial, after which the gas is brought into rotation by blades. A multi-cyclone is sensitive to good distribution of the gas amongst the smaller cyclones. If the distribution is wrong, a reversal or clogging of the gas may occur. Multi-cyclones can reach a high removal efficiency of over 99%, depending on particle size.

- Electric cyclones work by applying an electric field between the centre and the wall of the cyclone. This way the driving force pushing the particles towards the wall is increased causing higher removal efficiency.

- Secondary flow enhanced cyclone: In a cylindrical casing the gas enters at the bottom with a rotational movement. By tangential supply of secondary air at the top the centrifugal forces working the particles are increased, causing a higher efficiency. The secondary air can be clean or cleansed air.

- Condensation cyclone: these cyclones are cooled to below the dew point so substances like fats and water condensate and can be removed.

- Wet cyclone: to increase the removal efficiency for dust (< 20 µm) water is atomized. The water binds to the fine dust and is drained off like slurry.

- Micronsep wringing separator: The system consists of a spiral-shaped interior that is fitted into a cyclone-like casing. The system has an efficiency of more than 99.5% for particles larger than 1 µm, distinguishing itself from classical cyclones.

- Rotating particles separator (RPS): The core of the particle filter consists of the filter element. The filter consists of a large amount of channels that, as a whole, rotate around a collective rotation axis. Solid or liquid particles are forced against the walls by the so-called centrifugal force and remain there. The cleansed gas or liquid leaves the filter element and the filter can be periodically cleaned if necessary. Even at high gas speeds (a few meters per second), particles smaller than one µm can be caught by increasing the filter’s length (usually up to a meter). The length and height of the channels can thus be so dimensioned that the pressure drop amongst the channels is restricted to a few mbar. The RDS has been applied in very different situations, wherein a good efficiency at a low investment price was noted (efficiency is nearly on the same level as the EPS but the costs are significantly lower). There is currently no set supplier, only a licensee.

Installation: design and maintenance The efficiency of cyclones is dependant on the assessment of efficient with a low capacity or less efficient with a high capacity. Cyclones are most efficient at high air entering speeds, small cyclone diameter and large cylinder length, in contradiction to the so-called “high

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throughput” cyclone, where the high capacity and thus large size take their toll on the efficiency. The air entering speed of a cyclone is between 10 and 20 m/s, the average speed is about 16 m/s. Fluctuations in this speed (lower speed) causes the removal efficiency to sharply drop. The efficiency of a cyclone is determined by the particle size and the design of the cyclone. The efficiency is increased by: - Particle size and density - Cyclone length - Amount of circulations of the incoming gas stream in the cyclone - Dust load - Slipperiness of the inside of the cyclone

The efficiency is decreased by an increase in: - The cyclone chamber’s diameter - Diameter of the outgoing gas stream - Surface of the incoming gas stream’s entry point - Gas density

The maintenance requirements of a cyclone are simple: they have to be easily accessible for periodical inspection for corrosion or erosion. The pressure drop has to be checked regularly and the dust-catching mechanism has to be inspected for obstructions. Monitoring In order to monitor the cyclone’s efficiency the dust concentration in the cleansed gas stream can be determined by isokinetic sampling (without obstructing the gas stream) or a measurement method based on, for example, UV, visible light transparency, beta radiation or particle detection. Environmental pros and cons Specific pros - Simple construction - Recovery of raw materials possible - No moving parts - Low maintenance - Low investment costs and operational expenses - Consistent pressure drop Specific cons - Low efficiency for smaller particles < 10 µm- High pressure drop (5 - 20 mbar) depending on the variant - Bad results with shared loads - Emission of waste water in case of the wet cyclone - Not applicable for particles causing excessive corrosion or obstruction - Potential noise pollution Additives - Energy consumption - Consumption among other things dependant on the temperature of incoming gas (in

the wet cyclone’s case) Cross Media Effects Removed dust must be disposed off as waste product or recycled. The dust slurry of a wet cyclone has to be treatedin a water treatment plant.

MD-MV20090007 -21-

Financial aspects Investments, EUR/1,000 m03/h 1,200 Operational expenses None Personnel, hours per week Up to 2 Help and additives Water (wet cyclone) Energy consumption, kWh/1,000 m03/h 0.25 – 1.5 Cost-determining parameters Gas flow, pressure drop Benefits Potential regaining of raw materials

Information sources 1. Description of air emission abatement techniques, L26 Infomil/Tauw, March 2000. 2. Guide on air cleaning techniques, VITO 2004/IMS/R/066. 3. IPPC Reference document on Best Available Techniques in Common Waste Water and Waste Gas Treatment / Management Systems in the Chemical Sector, February 2003. 4. Dutch Association of Cost Engineers, edition 25, November 2006. 5. US EPA CACT Air Pollution Control Technology Factsheet (http://www.epa.gov/ttn/catc/dir1/fcyclon.pdf) 6. Interview Airtechnic Solutions, Romico Holding (rotating particles separator), 2008 7. Kok, H. Particle size distribution of emitted fine dust at industrial sources, TNO October 2006.

MD-MV20090007 -22-

4.2 Scrubbing

MD-MV20090007 -23-

Scrubbing (general) / Wet dust remover / Wet dust scrubber Brief description Description Wet scrubbing is a variation on wet gas scrubbing. The two most common techniques are the venturi scrubber and rotational scrubber. Wet scrubbing entails separating the dust by intensively mixing the incoming gas with mater, mostly combined with a removal of the coarse particles through us of centrifugal force. In order to achieve this, the gas is put in tangentially (at an angle from the side). The removed solid dust is collected in the bottom of the dust scrubber. Aside from the dust, inorganic chemicals like SO2, NH3 and VOC and heavy metals that may be attached to the dust are removed. The major goal for which the scrubber is applied is the removal of the dust. Schematic diagram

Applicability Many applications including the chemical industry and asphalt production. For the specific applications, such as the venturi and rotational scrubber, we refer to the specific fact sheets of those variants.

Water & dustdischarge

Wet dust scrubber

Clean gas

Gas flow in

Scrubbingwater

MD-MV20090007 -24-

Components

Removed components

Removal efficiency1, % Remaining emission, mg/m03

Validation number

(fine) dust

99

< 10

2

¹Dependant on the specific configuration and operational conditions. Values are based upon half-hour averages. Other components such as heavy metals and inorganic chemicals can be removed simultaneously (also see absorption). Preconditions Gas flow, m03/h 720 – 170,000 Temperature, °C 4 - 370 Dust, g/m03 0.2 - 115 Pressure, bar atmospheric Pressure drop, mbar 20 – 50

Extensive description Variations There are many variations on the wet dust scrubber like the venturi scrubber, the rotational scrubber, the whirl scrubber, the spraying chamber, the wet cyclone and the packed bed and dish columns. Some of these scrubbers are also used as gas scrubbers. Installation: design and maintenance The liquid-gas-ratio of a dust scrubber is the ratio between gas flow and the srcubber liquid flow. For the proper dimensioning and judgment of a dust scrubber’s performance it is important to know how much liquid per m0

3 is necessary to achieve the preferred level of emission. The performance is strongly dependent on the degree of pollution of the dust scrubber. Regular inspection, maintenance and cleaning are necessary for a good performance. Monitoring To judge the dust scrubber’s performance, one can apply isokinetic sampling, UV or beta radiation. Parameters that have to be checked regularly include the pressure drop on the scrubber, the gas-liquid-ratio, the optimal amount of spraying water, and the pH. The dust scrubber needs to be accessible in order to check these factors regularly. Environmental pros and cons Specific pros - Low risk in applying dust scrubber for gas streams containing explosive or flammable

chemicals. - May also be used as cooler for hot gasses - Neutralizes corrosive gasses - Simultaneous removal of dust and inorganic components Specific cons - Produces waste water - Wet by-product - Chance of freezing - Incoming gas has to be treated further in order to prevent the forming of plumes Additives Water and possibly additional chemicals to increase the precipitation of the component that is to be removed. Cross Media Effects Waste water that has to be treated or discharged. Residues that have to be drained off after dehydration.

MD-MV20090007 -25-

Financial aspects Investment costs, EUR/1,000 m03/h Operational costs, EUR/1,000 m03/h Personnel, hours per month Help and additives Energy consumption, kWh/1,000 m03 /h Cost-determining parameters Benefits

5,000 5,000 – 50,000 About 4 Drainage of waste matter and treatment of waste water < 0,5 Scale and eventual special treatment of gas stream None

Information sources 1. Description of air emission abatement techniques, L26 Infomil/Tauw, March 2000. 2. Guide on air cleaning techniques, VITO 2004/IMS/R/066. 3. IPPC Reference document on Best Available Techniques in Common Waste Water and Waste Gas Treatment / Management Systems in the Chemical Sector, February 2003. 4. http://www.frtr.gov/matrix2/section4/4-60.html5. Netherlands emission guidelines for air, NeR paragraph 3.7 and Annex 4.7, 2008

MD-MV20090007 -26-

Spraying tower / Rotational scrubber / Dynamic scrubber Brief description Description The spraying tower is a specific type of dust scrubber. The washing liquid is sprayed or scattered by a fast-spinning nebulizer disc or rotating sprays, creating a large contact surface for the drops and the gas. There are variations of the spraying tower that do not have a spinning turbine. The gas is put in tangentially (at an angle from the side) into the dust removal chamber. The centrifugal forces and the rotating nebulas drag the dust particles to the chamber wall, making high removal efficiency possible. The separated dust has to be dehydrated and disposed of.

Schematic diagram

Applicability The scrubber is primarily applied for separating very small dust particles (< PM10). Other easily soluble water components such as HF, HCI and SO2 can also be efficiently removed. Broad range of application including the following sectors: - chemical industry for the removal of dust and aerosols - metal industry for various kinds of gasses - waste-incineration - potato processing industry for the removal of amylum - glass industry

Scrubbingwater

Water & dustdischarge

Clean gas

Gas flow in

Spraying tower

Droplet separator

Rotating wheel

MD-MV20090007 -27-

- foundries - sintering processes - drying process - fertilizer production - pharmaceutical industry - plastics industry. Components Removed components

Removal efficiency1, % Remaining emission, mg/m03

Validation number

PM10 70-992

MD-MV20090007 -28-

Financial aspects Investments, EUR/1,000 m03/h1

Personnel, hours per week Operational costs, EUR/1,000 m03/h Residue, EUR/ton Energy consumption, kWh/1,000 m03/h Benefits

5.000 - 25.000 About 1 1,000 – 30.000 Ranging from 100 – 250 depending on the type of waste Costs for treatment of waste water 0,4 - 2,7 depending on design None

¹ For capacities > 10,000 m03/h an up scaling to the power of 0.3 applies (additional costs > price0.3 for extra capacity beyond 10,000 m03/h). Information sources 1. Description of air emission abatement techniques, L26 Infomil/Tauw, March 2000. 2. Guide on air cleaning techniques, VITO 2004/IMS/R/066. 3. IPPC Reference document on Best Available Techniques in Common Waste Water and Waste Gas Treatment / Management Systems in the Chemical Sector, February 2003. 4. Dutch Association of Cost Engineers, edition 25, November 2006. 5. Netherlands emission guidelines for air, NeR paragraph 3.7 and Annex 4.7, 2008 6. http://www.frtr.gov/matrix2/section4/4-60.html7. Supplier information DMT Environmental Technology

MD-MV20090007 -29-

Venturi-scrubber / Venturi-scrubber / Whirl scrubber Brief description Description A venturi-scrubber consists of a converged neck (the narrowest part of the venturi tube), a diverging expansion chamber and beyond that a drip precipitator. The dust/gas mixture streams into the venturi tube and reaches high speeds in the neck. Then the mixture reaches the expansion chamber where the speed diminishes. The liquid is added to the gas just before or inside the neck. Then an intensive mixing of the gas and liquid takes place in the venturi tube. Because of the gas and liquid’s high speed the water scatters into small drops resulting in an intense contact between the gas and liquid phases. Achieving this fine droplet distribution takes a relatively large amount of energy. Venturi-scrubbers can be applied for the removal of small particles (< 1 µm) from a gas stream, although the efficiency generally decreases with particle size. They can however also be applied for larger particles, although in such as a case the energy consumption rate is much higher than those of competing techniques. Some dusts cannot be removed, even at a very high pressure drop. Schematic diagram

Applicability The scrubber is primarily applied for the removal of fine dust (PM10). Broad range of application including the following sectors: - Chemical industry - Basic metal industry - Asphalt production - Wood and paper industry - Waste incineration

Venturi scrubber

water water

Gas in

Clean gas

Dust and wastewater

MD-MV20090007 -30-

Components Removed components

Removal efficiency1, %

Remaining emission, mg/m03

Validation number

PM10 PM0,3 à PM0,5 HCl, HF

70-992

MD-MV20090007 -31-

Financial aspects

Information sources 1. Description of air emission abatement techniques, L26 Infomil/Tauw, March 2000. 2. Guide on air cleaning techniques, VITO 2004/IMS/R/066. 3. IPPC Reference document on Best Available Techniques in Common Waste Water and Waste Gas Treatment / Management Systems in the Chemical Sector, February 2003. 4. EPA-CICA fact sheet: http://www.epa.gov/ttn/catc/dir1/fventuri.pdf5. http://www.frtr.gov/matrix2/section4/4-60.html6. Dutch Association of Cost Engineers, edition 25, November 2006. 7. Netherlands emission guidelines for air, NeR paragraph 3.7 and Annex 4.7, 2008 8. Supplier information: Pure Air Solutions

Investments, EUR/1,000 m03/h Personnel, hours per week Operational costs, EUR/1,000 m03/h Additives and residues Energy consumption, kWh/1,000 m03 /h Benefits

5,000 – 7,000, depending on design About 1 2,000 – 50,000 Strongly dependent on the application 0.5 – 7 None

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4.3 Filtration

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Fabric filter (filtering dust separator) / Tube filter / Bag filter Brief description Description The polluted air is lead through the fabric filter and the dust particles are separated. The dust is periodically removed from the filter and collected in a funnel (hopper) placed below the filtering installation. The fabric filter can be attached in many ways such as in tubes, envelopes, etc. The incoming air usually does not stream directly into the filters but is lead through one or multiple dividing plates. The goal here is to achieve a good distribution of the pressure on the cloth. This way the air also uses a lot of its kinetic energy, allowing for a pre-removal through gravity. A tapping mechanism is used to frequently remove the accumulating dust from the filter. The dust that falls off the cloth is caught in the bottom of the filter and can in some cases be re-cycled into the process. Schematic diagram

Applicability Fabric filters are primarily used for the removal of dust and particles up to

MD-MV20090007 -34-

Various types of cloth can be used for different purposes. Some examples of this are given below. Examples of fabric filter material

Chemical resistance Material Acid milieu Basic milieu

Working temperature, ºC

Polyester Good Reasonable 130 M-Aramide Good Good 200 PTFE Very good Very 260 Polyamide Good Good 260

Components Removed components

Removal efficiency1, %

Remaining emission, mg/m03

Validation number

Dust (> 2,5 µm)

Dioxin / furans

99,95

MD-MV20090007 -35-

etcetera. Temperature and pressure have to be checked regularly. The pressure drop on the filter determines when the cleaning cycle has to be initiated. Regular inspection of the filters is necessary for checking the filters and casing for deterioration, so easy access to the filter is necessary. A well-inspected fabric filter needs to have a leak-detection system with an alarm to prevent uncontrolled emissions. Environmental pros and cons Specific pros - High removal efficiency - Changing loads have no influence on pressure drop and efficiency - Removed dust can eventually be re-used as raw material Specific cons - Not suited for wet or sticky chemicals because of the risk of filter clogging. Eventual

heating of gas stream prevents condensation of fluid on the filter. - Risk of explosion - Potential electrostatic charge - Takes up a lot of space

Additives - Different types of cloth are available (varying in quality and depending on the type of

pollution). - The most common filter materials are cotton, wool, nylon, polypropylene, Orlon,

Dacron, Dynel, glass fiber, Nomex, polyethylene and Teflon. - Pre-coating of the fabric filter may be necessary in case of sticky or static chemicals for

the protection of the cloth. - Compressed air: 3 - 7 bar is needed to clean the filter elements and for compressed air

and ultrasonic cleaning. - Energy consumption: 0.2 – 2 kWh/1,000 m0

3.- Filter cloths: 11 - 17 m2 /1,000 m0

3/h.

Cross Media Effects Solid waste including the removed dust and the cloths used. The quantity is dependent on the application. Systems with a heightened risk (explosion, fire) are to be fitted with safety regulations such as an expansion hatch or sprinklers. Financial aspects Investment costs, EUR/1,000 m03/h Filter material, EUR/1,000 m03/h

1,000 – 4,500, depending on the design 660 – 920

Operational expenses, EUR per year/1,000 m03/h

About 200 – 1,500

Personnel, hours per week 2 Energy consumption, kWh/1,000 m03/h 0.2 – 2 Cost-determining parameters Pressure drop, and eventual costs for

conveying dust Benefits Saving in costs of raw materials when recycling

is possible, for instance in the glass industry

MD-MV20090007 -36-

Information sources 1. Description of air emission abatement techniques, L26 Infomil/Tauw, March 2000. 2. Guide on air cleaning techniques, VITO 2004/IMS/R/066. 3. IPPC Reference document on Best Available Techniques in Common Waste Water and Waste Gas Treatment / Management Systems in the Chemical Sector, February 2003. 4. Dutch Association of Cost Engineers, edition 25, November 2006. 5. US EPA APTI Virtual Classroom: http://yosemite.epa.gov/oaqps/EOGtrain.nsf/DisplayView/SI_412A_0-5?OpenDocument6. Mikropul Filter Media Fiber Selector. 7. Various emission rapports on asphalt plants from the competent authorities, 2003-2008. 8. Kok, H. Particle size distribution of emitted fine dust in industrial sources. TNO October 2006.

MD-MV20090007 -37-

Ceramic filter (filtering dust-separator) / Ceramic filter / High temperature filter / Candle filter Brief description Description In a ceramic filter the contaminated gas is lead through filtering material, comparable to the fabric filter. The filter ensures that the particles remain in the filtering material and the incoming gas is cleaned. The difference with a fabric filter is that the filtering material is ceramic. There are also designs where the acid components such as HCI, NOx and SOx and dioxins are removed. In such a case the filtering material is fitted with catalysts and the injection of reagents may be necessary.

Applicability Mostly applied for dust removal at high temperatures, especially with: - combustion installations and gasification systems with coal as fuel - waste processing industry - plastics processing industry - chemical industry - glass industry

Dust discharge

Clean gas

Gas flow in

Ceramic filter

Compressedair

MD-MV20090007 -38-

Components Removed components

Removal efficiency1, %

Remaining emission, mg/m03

Validation number

Dust HCl SO2NOxdioxin

99 – 99.99 95 80 95 99

< 2unknown unknown

< 200 unknown

21111

1 Dependent on the specific configuration, operational conditions and reagents. Values are based upon half-hour averages. Preconditions Gas flow, m03/h 300 – 1,800,000 Temperature, °C < 1,200 Pressure, mbar ~ 50 higher of lower then atmospheric Pressure drop, mbar 25 Fluid level Has to be above the dew point of condensable

materials in the gas to avoid clogging Dust, g/m03 < 20

Sticky particles have to be avoided

Extensive description Variants - (Improved) compact filter - Three-stage filter The filtering material of the ceramic filter can be applied in many different forms. It is possible to convert the ceramic material into cloth, fiber felt, fiber elements, sinter element or filter candles. The table below gives an overview of the different applications: Filter medium Filter cloth1 Fiber felt Fiber element Sinter element Design Bag with

supporting basket

Bag with supporting materials

Pipe, self-carrying

Pipe, candle, self-carrying

Surface weights (g/m2)

1,000 – 2,000 2,500 – 3,500 2,000 – 4,500 12,500 – 22,800

Mechanical qualities

Flexible, not very grating-proof

Flexible, not very grating-proof

Half stiff, a little grating-proof

Stiff, grating-proof

Air transparency

High Average Average Small

1 Cloth with ceramic material

Installation: design and maintenance The ceramic filters require a relatively large amount of maintenance and regular inspection, in order to prevent clogging and bad performance of the filtering elements. For these reasons it may decided that the process temperatures should be lowered and fabric filters installed, for they are easier to maintain. Monitoring The performance of the filter can be checked by measuring the particle mass in the outgoing gas. This can be achieved by, for example, isokinetic sampling, tribo-electric flow gauge, UV/Transparency meter, etc. The temperature and pressure drop have to be registered in order to determine the condition of the filtering material and to ensure that it is cleaned in time. For details we refer to the NeR paragraph 3.7 and Annex 4.7.

MD-MV20090007 -39-

Environmental pros and cons Specific pros - High dust removal efficiency - Modular construction - Can handle high and varying capacities - Can withstand acid and basic chemicals - Removed dust may potentially be re-used - Simple mechanic Specific cons - Vulnerable (ceramic material) - Relatively high pressure drop - A lot of maintenance and relatively large weight - Less suitable for wet and/or sticky chemicals - Explosion risk in case of flammable chemicals - Relatively high operational costs compared with other filtering materials

Additives Filtering material Compressed air for the cleaning of the filtering elements Cross Media Effects The lifespan of the filtering material is dependent on the design and application. The removed dust can be disposed of as waste or recycled back into the process. Financial aspects Investment costs, EUR/1,000 m03/h 30,000 – 55,000 Operational costs, EUR/1,000 m03/h About 1,000 Help and additives, EUR/ton - 0 (in case of recycling. See: benefits)

- Inert waste: about 75 (solid, non-hazardous waste) - Hazardous wastel: about 250

Energy consumption, kWh/1,000 m03/h 0.2 – 2 Cost-determining parameters Gas flow , filtering material, surface pressure Benefits Cost-saving because of potential recycling of material

Information sources 1. Description of air emission abatement techniques, l26 Infomil/Tauw, March 2000. 2. Guide on air cleaning techniques, VITO 2004/IMS/R/066. 3. IPPC, BREF Waste Gas and Waste Water Treatment, 2003. 4. Reference document on BAT in the large volume inorganic chemicals, ammonia, acids and fertilizers industry, draft 2004. 5. Netherlands emission guidelines for air, NeR paragraph 3.7 and Annex 4.7, 2008. 6. Suppliers: Airtechnic Solutions, Lutec, Nedfilter 7. Gamma Holding, Madison Filter; Cerafil, presentation January 2007.

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Two-stage dust filter Brief description Description The two-stage dust filter has metallic gauze as filtering material. In the first stage a filtering layer is accumulated after which the filtering takes place in the second stage. Depending on the pressure drop on the filters the second stage is cleaned and the air stream is switched between the two stages. The first filter now serves as the second and vice versa. The dust falls to the bottom of the installation where it may be removed. Schematic diagram

Afgas

Gereinigd gas

Afgescheiden stof Afgescheiden stof

Klep om gasstroomrichting om te draaien

Klep om gasstroomrichting om te draaien

metaalgaasfilter

Applicability The two-stage dust filter has the same applications as the improved compact filter and is primarily suited for the removal of dust. It has a range of application in the following sectors: - Waste processing industry - Chemical industry - Wood industry - Refineries

Clean gas

Gas flow in

Dust dischargeDust discharge

Metal gasketfilter

Valve for turninggas flow

Valve for turninggas flow

MD-MV20090007 -41-

Components Removed components

Removal efficiency Remaining emission [mg/m03]

Validation number

Dust (PM) - 1 - 20 3

Preconditions Gas flow, m03/h Up to 75,000 per module Temperature, ºC Up to about 500 Pressure, bar Atmospheric Pressure drop, mbar About 25 Fluid percentage No known limitation Ingoing mass No limitation

Extensive description Variants One variation on the standard issue two-stage dust filter is a system with more than two metallic gauze filters where a filtering layer is accumulated before the filter is placed into the incoming untreated gas stream. This prevents the removal efficiency from decreasing just after the cleaning of the filters. Installation: design and maintenance The most important design parameters are the incoming gas flow and speed when travelling through the filtering material and the filters. Because this filtering material can handle a bigger load than a fabric filter, less filtering surface is required which may result in gain in space. However, because of the fact this is a two-stage system this advantage is nullified. It is claimed that the additional space in the two-stage system is entirely compensated by the higher filter load. Monitoring The performance of the filter can be checked by measuring the particle mass in the outgoing gas. This can be done using isokinetic sampling, UV/Transparency meter, etc. Temperature and pressure have to be checked regularly. The pressure drop on the filter determines when the cleaning cycle should start. Regular inspection of the filter is necessary in order to prevent deterioration of the filters and the casing, so good access to the filter is essential. A dust filter should have a leak detection system with an alarm in order to be sure of a good performance. Environmental pros and cons Specific pros - High dust removal efficiency - Regaining of solid materials is possible - Modular structure - Filtering material barely needs replacement, all-steel design - Filter load higher than with a cloth or compact filter - Also applicable for fluid, sticky, fibrous or static dust - Can withstand high temperatures (limited fire risk) - Possibility of regaining heat at high temperatures Specific cons - Higher costs than a fabric or compact filter when used at ambient temperatures, this

does not apply at higher temperatures - Frequent changing between the two compartments (with a normal two-stage filter) - Valves necessary in a dusty environment; greater change of malfunctions - Explosion risk Additives - Metallic gauze as filtering material - Compressed air for the cleaning of the filters - Energy consumption

MD-MV20090007 -42-

Cross Media Effects The removed dust can be polluted, depending on the application. For example, dioxins and/or heavy metals can be present in the dust in case of combustion processes. The dust may then be classified as toxic waste. Financial aspects

InformInformation sources 1. Description of air emission abatement techniques, L26 Infomil/Tauw, March 2000. 2. IPPC Reference document on Best Available Techniques in Common Waste Water and Waste Gas Treatment / Management Systems in the Chemical Sector, February 2003. 3. Dutch Association of Cost Engineers, edition 25, November 2006. 4. BP Australia, Installs & commissions Pall GSS 3rd stage blow back filter system to reduce RCC flue gas emissions, 2004. 5. Bioflamm, http://www.bioflamm.de 2008

Investments, EUR/1,000 m03/h 40,000 Operational costs, kWh/1,000 m03 /h about 1.5 Personnel, hours/week About 2 Help and additives, EUR/ton Conveyance as toxic waste: 150 - 250 Cost-determining parameters Gas flow, pressure drop, conveyance toxic waste Benefits Savings or profits from regained materials (in

case of eventual recycling)

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Absolute filter / HEPA-filter / surface filter / cartridge filter / micro filter Brief description Description The incoming gas stream is lead into a chamber and guided through a High Efficiency Particle Air filter (HEPA filter). A HEPA’s filtering material consists of very thin glass fibers mounted in paper or a paper filter. In order to attain the largest possible filtering surface, the glass fiber paper is folded like a harmoniabout This is necessary because the thick mass of glass fiber paper doesn’t let much air trough. In order to move a high enough volume of air a large surface is required. The dust remains on the filter, but does not penetrate it. So the process consists of surface filtration. The layer of dust that forms a layer onto the filter can initially improve the dust removal efficiency. If the pressure drop on the filter grows too large after some use, it has to be replaced. The HEPA-filter can be placed directly into a piping, or in a separate casing. HEPA-filters do require a pre-cleaning stage to remove the coarse dust. Because of this, HEPA-filters are often the last filtering stage for the removal of dust. HEPA-filters are rarely re-used, because the cleaning of it may cause damage or leakage of the filter. Schematic diagram

Applicability Absolute filters are applicable for the removal of dust between PM0.12 and PM0.3 and for toxic or dangerous particles, like most heavy metals. Because of it’s high efficiency another installation is placed before the absolute filter for the removal of coarse particles, like an electrostatic precipitator or fabric filter. Absolute filters are often used for the filtration of inside air in locations where a good air quality is necessary like in operating rooms in hospitals or in production spaces of the pharmaceutical, the photographic and the electronics sectors. Other sectors where the absolute filter is applied include: - Biochemical industry - Food industry - Chemical industry Components Removed components

Removal efficiency, % Remaining emission, mg/m03

Validation number

PM > 99.999 > 0.0001 1 PM0.01 > 99.99 unknown 1 PM0.1 > 99.999 unknown 1

1 Depending on the specific configuration and working conditions

Gas flow in

Clean gas

Pre filter

MD-MV20090007 -44-

Preconditions Gas flow, m03/h 100 – 360 per module Temperature, ºC < 200 for most common HEPA

< 530 for glass or ceramic HEPA Pressure Atmospheric Pressure drop, mbar Size unknown, although pressure drop is

present Fluid level, % < 95; always above the incoming gas’ dew

point Ingoing dust concentration, mg/m03 1 - 30

Extensive description Variants One can distinguish between two variants: - HEPA (High Efficiency Particle Air) filter: 99.97% minimal removal efficiency for fine

dust > 0.3 micrometer - ULPA (Ultra Low Penetration Air) filter: 99.9995% minimal removal efficiency for fine

dust > 0.12 micrometer Installation: design and maintenance Absolute filters are the last filtering phase for the removal of dust, prior to the absolute filter an ESP or fabric filter is applied in order to remove the coarse particles. Determining parameters for the design of the mechanical aspect and the casing are temperature and pressure. With the most common designs, the filtering units are either right-angled or cylindrical in shape. The filter is folded in order to enlarge the surface. Monitoring The outgoing gas stream can be monitored with the help of an isokinetic sampler or a meter based on UV, light-transparency, beta-radiation or particle detection. Environmental pros and cons Specific pros - Filters submicron particles of fine dust - Very high efficiency, low remaining emission (see applicability) - Filtered incoming gas stream is very clean and can be re-circulated into the process - Modular design - Not sensitive to small variations in the gas stream - Relatively easy operational management - Not sensitive to corrosion Specific cons - Not suitable for the removal of wet dust or Applicability in humid conditions - Not suitable for large dust loads (unless after pre-filtering) - Not suitable for gas streams containing bases - Explosion risk - Frequent replacement of filtering element is necessary Additives Filtering material (paper and/or glass fibers) has to be replaced frequently. Energy consumption < 0,1 kW/1,000 m0

3/h. Cross Media Effects The used filter is carried off as waste material, with one filtering module generally absorbing 1 kilogram of dust. Multiple modules can be in effect simultaneously. Financial aspects Investment costs, EUR/1,000 m03/h 2,400 – 3,200 Operational costs, kWh/1,000 m03/h < 0.1 Personnel, hours per week About 2 Help and additives, EUR per year/1,000 m03/h

100 - 190

Cost-determining parameters Gas flow, filtering material Benefits None

MD-MV20090007 -45-

Information sources 1. Description of air emission abatement techniques, L26 Infomil/Tauw, March 2000. 2. Guide on air cleaning techniques, VITO 2004/IMS/R/066. 3. IPPC Reference document on Best Available Techniques in Common Waste Water and Waste Gas Treatment / Management Systems in the Chemical Sector, February 2003. 4. Dutch Association of Cost Engineers, Edition 25, November 2006. 5. http://www.epa.gov/ttn/catc/dir1/ff-hepa.pdf

MD-MV20090007 -46-

Demister / Aerosol filter / Deep bed filter Brief description Description Most demisters are woven elements of metal or synthetic material. The filters work on the principal of mechanical removal and depend on the speed at which the particles or drops pass the filter. The efficiency of demisters can rise up to 99% for dust and aerosols. Filtering elements with a small mesh for the removal of dust (1 - 3 µm) are more efficient for the smallest drops, but the chance of clogging increases. For the removal of sticky matter and fatty or viscous fluids, interchangeable filters can be applied. In case of fatty fumes the filter may become clogged if coagulation takes place as a result of a drop in temperature. Schematic diagram

Applicability Demisters often form an integrated part of other techniques, for example a gas scrubber. Broad range of application for the removal of pollution in the form of drops and aerosols after steam kettles and gas scrubbers in the: - Chemical industry - Textile industry - Food industry - Plastics processing Components Removed components

Removal efficiency1, %

Remaining emission, mg/m03

Validation number

Dust, drops and aerosols

< 99%

Scrubbing liquid with removed dust and polluted filtering material

1

1 Depending on the specific configuration and operational conditions. Values are based on half-hour averages. Preconditions Gas flow, m03/h Up to 150,000 Temperature, °C < 170 Pressure - Pressure drop, mbar Normally up to 25 (up to 90 at high loads) Aerosol level, g/m03 Some Dust, mg/m03 < 1

Gas flow in

Clean gas

Demister

Filter element

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Extensive description Variants Besides those demisters based on woven elements of metal or synthetic materials there are also variants based on specially designed gaskets or bended plates. Installation: design and maintenance Material of choice: steel. Dimensioning basis: gas flow and filter load. When the demister separates drops and aerosols, these may be self-cleaning because of the running fluid. In this is not the case, the filter should be rinsed. Monitoring The pressure drop after each filtering stage should be measured separately in order to determine the performance of the filter. Environmental pros and cons Specific pros - Self-cleaning in case of removal of fluids - Suitable for filtration of fluid aerosols. Specific cons - Polluted scrubbing fluid when cleaning the filter - Chance of high pressure drop when separating solid dust particles - Chance of obstruction because of solid matter and fatty fumes. Additives - Filtering medium - If applicable scrubbing fluid for cleaning. Cross Media Effects Scrubbing fluid containing removed dust and polluted filter material should be considered waste, depending on the chemical. Financial aspects

Information sources 1. Description of air emission abatement techniques, L26 Infomil/Tauw, March 2000. 2. Guide on air cleaning techniques, VITO 2004/IMS/R/066. 3. IPPC BREF, Waste Water and Waste Gas Treatment, 2003.

Investment costs, EUR/ 1,000 m03/h

< 2,300

Operational costs, EUR/year 2,500 + (450 * flow/1,000) Personnel about 2 hours per week Help and additives, EUR per year/1,000 m03/h

250 to 600 (filtering material)

Energy consumption, kWh/1,000 m03/h

Energy consumption rate depends on the filtering system

Cost-determining parameters Gas flow, pressure drop, filtering element Benefits None

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Dry electrostatic precipitator / Electrostatic precipitator (ESP) / Dry E-Filter / Dry ESP / Dry electrostatic precipitator / Electro filter Brief description Description A dry electrostatic precipitator is a device that charges (ionizes) particles by means of electrical fields and removes them from the gas stream by having them pulled towards collecting electrodes. The removed particles fall because of gravity or (in the case of solids) because of the periodical tapping or shaking of the collecting electrons and end up in a dumping bunker. There are two types of dry electrostatic precipitators: - The plate filter wherein the gas is carried horizontally past the plates. - The pipe filter wherein the gas is carried through the tubes vertically. Schematic diagram

Applicability The primary areas of application are large complex waste gas cleaning systems in power plants and waste incineration facilities. Components

Removed components

Removal efficiency1,%

Remaining emission, mg/m03

Validation number

Dust, aerosols PM1

PM2PM5

> 97 > 98 > 99.9

5 – 20 3

1 Depending on the specific configurations and operational conditions. Values are based on half-hour averages.

Gas flow in

Clean gas

Discharge ofdust

High voltage

Dry Electrostatic precipitator

Isolator

Discharge electrode

Collector electrode

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Preconditions Gas flow, m03/h 360,000 – 2,000,000 (plate filter)

1,800 – 180,000 (pipe filter) Temperature, °C ≤ 700 Pressure Atmospheric Pressure drop, mbar 0.5 – 3 Dust, mg/m03 2 - 110 (plate filter)

1 – 10 (pipe filter)

Extended description Variants The two-stage electro-filter consists of two compartments, with the ionization of the particles taking place in the first compartment and the removal and collection of the particles in the second compartment. Installation: design and maintenance - Material of choice: steel - Dimensioning basis: gas flow, gas speed in filter (0.6 - 1 m/s) - Capacity (m3/1,000 m0

3/h): 1.4 – 2.8 Construction aspects An electro-filter consists of one or more chambers among which the incoming gas is evenly divided. This done by means of a gas-dividing screen. The system is built based on a series of independently operating fields, placed in serial order. The first field removes the majority of the dust, while the last fields are there in order to keep the remaining emissions low. Independently coordinated fields are preferred because of the operational safety. Each field should be fitted with it’s own dust funnel. Cleaning of the electrodes Because of the electrodes being tapped the removed dust can be collected in the dust funnel. However, when too many plates are being cleaned at the same time the remaining emission will temporarily be higher. It is thus beneficial to limit the amount of electrodes being tapped simultaneously. The plates should be tapped frequently in order to prevent the layer of fly ash to become too thick and thus decreasing the efficiency. However, when the plates are tapped too often, the fly ash layer doesn’t become thick enough, and breaks of into pieces and is sucked away with the gas stream. The configuration of the plates is important in this regard, with low gas-speed zones and the height/width ratio of the plates being essential for a good efficiency. Maintenance Electro-filters are relatively sensitive to proper maintenance and adjustments in the settings. Especially the removal of dust and the tapping mechanism may be a cause for extra maintenance. Monitoring The performance of the filter can checked by measuring the particle mass in the effluent gas. This can be done by means of isokinetic sampling or a UV transparency meter. For details we refer to NeR paragraph 3.7 and Annex 4.7. The system itself is to be regularly checked for corrosion of the electrodes and the isolation material. Environmental pros and cons Specific pros - Very high efficiency (including small particles) - Dust can be removed dry, making re-use possible. - Suitable for very large gas streams. - Suitable for use at high temperatures. - The efficiency of electro-filters can be increased by adding additional fields or zones. - Low pressure drop.

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Specific cons - Less suited for processes with varying gas streams, temperatures or dust

concentration. This however, can be compensated for by automatic adjustments. Varying operational conditions are no problem, if the installation is designed for the worst case situation.

- Sensitive to maintenance and the right settings. - Risk of explosion in combination with flammable chemicals such as soot. - Cleaning capacity is dependent on the conductibility of the chemicals that are to be

removed. - Takes up a lot of space. Additives None Cross Media Effects The removed dust can be re-used as, for example, filling matter in the asphalt and cement industry (depending on the dust’s nature), or it has to be disposed of as waste.

Financial aspects

1) Costs may turn out higher when the system has to be constructed out of stainless steel or titanium as a result of the nature of the dust that is to be separated. Information sources 1. Fact sheets on air emission abatement techniques, www.infomil.nl, Infomil 2. Guide on air cleaning techniques, VITO 2004/IMS/R/066 3. IPPC, BREF, Large Combustion Plants, 2006 4. IPPC, BREF Waste Water and Waste Gas Treatment, 2003 5. Netherlands emission guidelines for air, NeR paragraph 3.7 and Annex 4.7, 2008 6. Dutch power station, emission measurement, 2008 7. Kok, H. Particle size distribution of emitted fine dust in industrial sources, TNO October, 2006

Investment costs, EUR/1,000 m03 /h 10,000 – 30,000 (for systems 30,000 – 200,000 m03/h)1

Operational costs, EUR/1,000 m03/h 0.05 – 0.1 (for systems > 50.000 m03/h) Personnel, hours/day about 0.25 (maintenance of electrodes) Help and additives, EUR/ton Processing costs of the removed dust are

dependent on the nature of the remaining dust. In case of recycling: 0 Inert non-hazardous waste: about 75 Chemical waste: 150 – 250

Energy consumption, kW/1,000 m03/h 0.2 - 1 Cost-determining parameters Gas flow, dust concentration, efficiency Benefits Use of removed dust

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Wet electrostatic precipitator / Wet E-filter / Wet ESP / Wet Electrostatic precipitator / Electro-filter Brief description Description A wet electrostatic precipitator consists of one or more chambers among which the untreated gas is evenly divided. This is done by means of a gas-dividing screen. The filter consists of a number of independently operating, serially placed electrodes. The wet electrostatic precipitator works in the same way as the dry version, however the collecting electrodes are not tapped, but the removed dust is removed by a flushing liquid. The incoming air should be moistened beforehand. There are two types of wet electrostatic precipitators: - The plate filter wherein the gas is carried horizontally past the plates. - The pipe filter wherein the gas is carried through the tubes vertically. Schematic diagram

Applicability The primary areas of applications are small-scale waste gas cleaning systems in the metal industry and the chemical industry where dry electrostatic precipitators do not suffice when handling wet and sticky matter, flammable and explosive mixes and material with a high resistance. It is also applied for the removal of mercury in waste incineration plants. Components Removed components

Removal efficiency1,%

Remaining emission, mg/m03

Validation number

Dust, aerosols 97 – 99 - 1 1 Depending on the specific configuration and operational conditions. Values are based upon half-hour averages.

Gas flow in

Clean gas

Wet Electrostatic filter

High voltage

Water in

Dust discharge

Isolator

Discharge electrode

Collector electrode

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Preconditions Flow, m03/h 180,000 – 900,000 (plate filter)

1,800 – 180,000 (pipe filter) Temperature, °C 80 - 90 Pressure Atmospheric Pressure drop, mbar Some Dust, g/m03 2 - 110 (plate filter)

1 – 10 (pipe filter)

Extensive description Variants The two-stage electro-filter consists of two compartments with the ionization taking place in the first and the particles being collected in the second. Installation: design and maintenance - Material of choice: steel. - Capacity: 1.4 - 2.8 m3 per 1,000 m0

3/h. - Sensitive to proper maintenance. Monitoring The performance of the filter can be checked by measuring the particle mass in the effluent gas. This can be done by means of isokinetic sampling, a UV/Transparency meter, etcetera. For details we refer to the NeR, paragraph 3.7 and Annex 4.7. The system should be checked regularly on corrosion of the electrodes and the isolation material. Environmental pros and cons Specific pros - Very small particles can be removed - Both wet and dry dust is removed - System can be constructed in modules - Partial removal of acid fumes. - At a voltage of > 50 kV, the removal is independent of the residence time, making

compact construction possible. - It is possible to remove sticky particles, fumes and explosive chemicals. Specific cons - Waste water is released - The electro-filter is very heavy - High investment costs. Additives Scrubbing liquid (usually water) is used as an additive. This can be (partly) recycled, minimizing the consumption rate. Cross Media Effects The removed dust and waste water can be re-used or has to be disposed of as waste.

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Financial aspects

Information sources 1. Fact sheets on air emission abatement techniques, www.infomil.nl, InfoMil 2. Guide on air cleaning techniques, VITO 2004/IMS/R/066. 3. IPPC, BREF, Large Combustion Plants, July 2006. 4. IPPC, BREF Waste Water and Waste Gas Treatment, 2003. 5. Netherlands emission guidelines for air, NeR paragraph 3.7 and Annex 4.7, 2008.

Investment costs, EUR per 1,000 m03/h

60,000 – 300,000 (systems of 30,000 – 200,000 m03/h)

Operational costs 0.05 – 0.1 (systems larger than 50,000 m03/h) Personnel, hours/day about 0.25 (maintenance electrodes) Help and additives, EUR/ton Processing costs of the removed dust is dependent

on the nature of the dust. Recycling waste: 0. Inert waste: about 75 Chemical waste: 150 – 250

Energy consumption, kW/1,000/m03/h

0.2 – 1 (including fan)

Cost determining parameters Flow, dust concentration, efficiency Benefits Eventual recycling of removed dust

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4.4 Condensation

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Condenser / Heat exchanger / Odour control condensation (OCC) Brief description Description When applying a condenser (odour) components (including acids, alcohols and ammonia) are removed from a gas stream that is saturate with water or warm and damp, by condensing to far below the water’s dew point. The condensate that forms on the heat exchanger, serves as an absorption liquid (only) for (odour) components that are easily dissolvable in water. The relatively large contact surface that is required for the exchange of heat is also used as a contact surface for the excha