VOC Emissions from Manufacturing Processes
5. Process-Integrated Production Modification Measures
This chapter contains catalogue of abatement measures for different post-processes.
Measures from the catalogue can be used in the scenarios and action plans described in
chapter 4.
Technical modifications
Process-integrated measures generally involve technical modifications to prevent emissions at their source, or by means of which emissions are reduced, extracted and transported away.
In the following sections 5.1 to 5.10, potential process-integrated emission reduction measures are examined more closely.
The capital costs stated in this project are based on costs in Germany and are converted from DM to DKK with a conversion rate of 4. Differences in the size of taxes etc. are not included.
The production units are shown in Figure 5.1 where the numbers refer to sections 5.1 to 5.10.
Figure 5.1
Overview of production units in the paint and coatings industry.
Implementation of the production modification measures described in 5.1-5.10 will result as a rule in the prevention (in enclosed systems) or reduction (by extraction of fumes) of emissions from diffuse sources. They bring about a significant improvement of the emissions situation at the workplace, and will generally lead to compliance with the maximum allowable concentrations (MAC) stipulated for places of work.
But it must be noted that changing diffuse emissions by extracting fumes into directed emissions can result in an increase of VOC loadings in the exhaust air stream. This is unavoidable in particular if the exhaust air system is over dimensioned with regard to the fan extraction rate and at the same time the emitters are encapsulated. Therefore, a prerequisite for successful reduction of the emissions by modification of production facilities is careful design of the fume extraction equipment.
Table 5.1 summarizes individual measures considered in this chapter. The influence on point source emissions and VOC limits for diffuse emissions is indicated as follows:
| ê | Reduction of VOC concentration |
| î | Slight reduction of VOC concentration |
| ì | Slight increase of VOC concentration |
| é | Increase of VOC concentration |
Table 5.1
Measures and their influence on diffuse emissions and point source emissions.
MEASURES |
Diffuse emissions |
Point source emissions |
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5.1 Unloading system for feedstock dosing and tankfarms |
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5.2 Dissolver and reactor |
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5.3 Holding store for mobile bins |
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MEASURES |
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5.4 Dosing station for mobile production bins |
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5.5 Mills for fine dispersing |
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5.6 Finish tanks |
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5.7 Filter systems |
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5.8 Filling systems |
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5.9 Rinsing basin |
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5.10 Cleaning of mobile production bins |
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Examples of some measures are shown on photos in Appendix A.
Avoidance of diffuse VOC emissions to the atmosphere is described in 5.1-5.10.
5.1 Unloading system for feedstock dosing and tankfarms
Emissions
VOC emissions from tankfarms and loading/unloading systems are caused mainly by:
Displacement of exhaust air to atmosphere during loading and unloading of road or rail tankers:
| Volumetric flow: | 20-50 normal m³/h |
| Concentration: | 1,000-5,000 mg org. C/normal m³, depending on temperature |
Respiration losses in the tankfarm to atmosphere:
| Volumetric flow: | < 1 normal m³/h |
| Resins concentration: | 1,000-5,000 mg org. C/normal m³ |
| Solvents concentration: | 10,000-50,000 mg org. C/normal m³ |
Measures
Measures for cutting VOC emissions and their capital costs are:
A1: Installation of a pressure equalizing line
| Efficiency: | Nearly 100% |
| Capital costs: | Approx. 20,000-80,000 DKK for one line, depending on number of tanks and distance between unloading station and tankfarm (piping system, valves, flashback arresters) |
A2: Isolation of tank by fitting over-/under pressure valves
Closes the system at a defined pressure (e.g. -5/+10 mbar)
| Efficiency: | Nearly 100% because of closed system at a defined pressure |
| Capital costs: | 10,000-20,000 DKK/tank, depending on pipe diameter and pressure drop |
5.2 Dissolver and reactor
Emissions
VOC emissions from dissolver and reactor are caused mainly by:
Displacement during liquid feedstock dosing:
| Volumetric flow: | 5-10 normal m³/h, depending on installed pump capacity |
| Concentration: | 1,000-5,000 mg org. C/normal m³, depending on temperature |
| Chemical reactions: | |
| Temperature: | Rise up to 50-70°C |
| Concentration: | Up to 10,000 mg org. C/normal m³ |
| Rising temperatures caused by shearing forces, among others: | |
| Temperature: | Rise up to 50-70°C |
| Concentration: | Up to 10,000 mg org. C/normal m³ |
| Cleaning of dissolver (shaft and disc) or reactor | |
| Concentration: | 1,000-3,000 mg org. C/normal m³ |
Measures
Measures for cutting VOC emissions and their capital costs are:
B1: Feedstock charging via closed systems
Avoidance of diffuse VOC emissions to atmosphere by using containers with adapter and charging via stationary closed piping systems. Dosing controlled manually (using delivery containers with definite weight) or automatically by e.g. weighing and automatically initiated switch-off.
| Transceiver: | Mobile (container, bins with adapter and/or integrated unloading systems) |
| Transmitter: | Stationary (pipes) |
| Receiver: | Stationary (dissolver) |
| Efficiency: | 100% with pressure equalizing line between container and dissolver/reactor |
| Capital costs: | 40,000-80,000 DKK/container system |
B2: Feedstock distribution and dosing via closed systems
Avoidance of diffuse VOC emissions to atmosphere by using stationary closed piping systems; distribution and dosing of solvents and resins controlled fully automatically by volumetric flow meter and automatically initiated switch-off (alternatively by level measurement).
| Transceiver: | Stationary (tanks, containers with integrated unloading systems) | |
| Transmitter: | Stationary (pipes) | |
| Receiver: | Stationary (dissolver) | |
| Efficiency: | - | Emissions caused by handling of drums or containers are prevented; efficiency nearly 100% |
| - | Increase of throughput capacity / availability by up to 30% | |
| - | Reduction of staff costs by up to 30% | |
| - | Improved and reproducible quality in dosing | |
| - | Only recommended for solvents and resins with a high frequency in usage and/or a high consumption (cost analysis is necessary) | |
| Capital costs: | Site specific | |
B3: Feedstock dosing or charging from mobile bins into partially closed systems
Reduction of diffuse VOC emissions to atmosphere by installation of small charging holes on the dissolver lid (lockable), start-up/shutdown of exhaust air system activated manually or automatically (e.g. dead stop position switch on the cap).
| Transceiver: | Mobile (bins, container with adapter or integrated unloading system) | |
| Transmitter: | Mobile/flexible (e.g. pumps with flexible hose on pressure side) | |
| Receiver: | Stationary (dissolver) | |
| Efficiency: | - | Improvement in personnel protection; reduction of emissions at place of work |
| - | Reduction of diffuse emissions by about 100% | |
| Capital costs: | Approx. 20,000 DKK/lid | |
B4: Feedstock dosing or charging from drums into partially closed systems
Reduction of diffuse VOC emissions to atmosphere by installation of hoppers with, for example, side extraction slit on the dissolver lid; start-up/shutdown of exhaust air system activated manually or automatically (e.g. dead stop position switch on the cap).
| Transceiver: | Mobile (drum) | |
| Transmitter: | - | |
| Receiver: | Stationary (dissolver) | |
| Efficiency: | - | Improvement in personnel protection; reduction of emissions at place of work |
| - | Reduction of diffuse emissions | |
| Capital costs: | 10,000-20,000 DKK/lid | |
B5: Interlocking of systems for extraction of solvents and particulates
Reduction of VOC loadings by interlocking of extraction systems for solvents and
particulates to minimize volumetric flows of solvent-diluted exhaust fumes (reduction of
respiration losses).
Extraction of particulate emissions by way of a filter to atmosphere, dosing of solids as
automatic or semi-automatic system with integrated dust filter and ventilator.
| Efficiency: | Respiration losses of solvents will be reduced. Dilution of VOC emissions will be avoided. Volumetric flow rate will be reduced as much as possible |
| Capital costs: | Site specific |
B6: Encapsulation of mobile bins during dispersing / mixing
Reduction of diffuse VOC emissions to atmosphere by encapsulation of mobile bins
during dosing with an extraction hood; alternatively increase of peripheral extraction.
| Efficiency: | - | Improvement in personnel protection; reduction of emissions at place of work |
| - | Reduction of diffuse emissions by 90-100% | |
| Capital costs: | - | 20,000-40,000 DKK/dissolver, depending on performance |
B7: Encapsulation of dissolver, additionally special dissolver lids with integrated condensation system
Encapsulation of open or partially closed dissolver with extraction hood and swivel opening, start-up/shutdown of exhaust air system activated manually or automatically (interlocking with swivelling door).
Volumetric flow rate of extraction system during dosing of liquids and solids about 500-600 m³/h and during dispensing about 15-50 m³/h (slight under pressure).
| Valves in the extraction system in position: | ||
| ON = dosing MIN.= dispensing OFF = dissolver not operating |
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| Efficiency: | - | Improvement in personnel protection; reduction of emissions at place of work |
| - | Respiration losses will be reduced (minimized extraction) | |
| - | Reduction of diffuse emissions by 90-100% | |
| - | Condensation systems can be used, with cooling by air or water depending on temperature attained during dispensing process. The efficiency of this system is very high, with solvent vapors condensed out almost completely and returned to the production bin or vessel. | |
| - | Reduction of directed emissions by 90-100% | |
| Capital costs: | 40,000-60,000 DKK/encapsulation system | |
B8: Automation of dissolver cleaning, dissolver with large production vessels as closed system
| Procurement of replacement equipment. | ||
| Efficiency: | - | Improvement in personnel protection; reduction of emissions at place of work |
| - | Reduction of emissions by about 100% | |
| Capital costs: | - | Automatic cleaning system, e.g. with rotating nozzle and solvent-based cleaning: 75,000-160,000 DKK |
B9: Volumetric flow minimized by using manually or automatically driven valves and flow restrictors in the extraction system
| Efficiency: | - | Improvement in personnel protection; reduction of emissions at place of work |
| - | Effectiveness of extraction at each emission source enhanced | |
| - | Respiration losses reduced (minimized extraction) | |
| - | Reduction of electricity consumption | |
| - | Personnel training may be necessary Capital costs: Site specific |
5.3 Holding store for mobile bins
Emissions
VOC emissions at holding stores for mobile bins are caused mainly by:
Respiration losses to atmosphere during temporary storage
Measures
Measures for cutting VOC emissions and their capital costs are:
C1: Covering of mobile bins with wooden lids or plastic membranes
| Efficiency: | - | Reduction of emissions at place of work by approx. 100% |
| - | Personnel training may be necessary | |
| Capital costs: | Costs are negligible |
C2: Provision of special storage areas for bins with separate extraction systems
Efficiency gains and capital costs are site-specific.
5.4 Dosing station for mobile production bins
Emission
VOC emissions at dosing stations for mobile production bins are caused mainly by:
Displacement during dosing of solvents and resins into open bin.
Leaks at dosing valves.
Emission releases during free jet dosing into open bins.
Diameters of extraction systems are often over-dimensioned.
Correct positioning of the extraction system is not possible or is inconvenient (and therefore not done properly by operators)
Measures
Measures for cutting VOC emissions and their capital costs are:
D1: Flexible hoods
Reduction of diffuse emissions by installation of flexible extraction systems with
hood (peripheral or segmental extraction rate of about 500 m³/h; DN 150).
| Efficiency: | Improvement in personnel protection; reduction of emissions at place of work by about 100% |
| Capital costs: | Approx. 20,000-40,000 DKK |
D2: Free jet dosing
Avoidance of leaks by installation of flexible hoses or lengthening dosing pipelines (offshore dosing).
| Efficiency: | Improvement in personnel protection; reduction of emissions at place of work. |
D3: Installation of stationary extraction hood
Only if dosing equipment is arranged close together or if replacement equipment is procured.
Peripheral or segmental extraction of about 500 m³/h; DN 150.
Interlocking of extraction system with automatically driven valves or pumps only recommended for solvents and resins that are often used.
| Efficiency: | Improvement in personnel protection; reduction of emissions at place of work |
D4: Installation of automatic shut-off valves
Dosing valves (e.g. ball valves) are not shut-off valves, because they do not close fully. If there are no shut-off valves, drip pans have to be installed beneath the dosing valves.
5.5 Mills for fine dispersing
Emissions
VOC emissions at mills for fine dispersing are caused mainly by:
Open mills and mobile container.
Outlet of mills (free jet) directed to container of different height.
Splashing during inflow into container.
Measures
Measures for cutting VOC emissions and their capital costs are:
E1: Covering of mobile container
Using movable lids; lids equipped with connection for inflow and extraction.
Extraction: max. 50 m³/h (DN 50).
Extraction via flexible hoods.
| Efficiency: | - | Improvement in personnel protection; reduction of emissions at place of work |
| - | Reduction of diffuse emissions by nearly 100% | |
E2: Covering of mills
Installation of hoppers at mill outlets, with flexible tubes and adapter for container lid.
| Efficiency: | Improvement in personnel protection; reduction of emissions at place of work |
| Capital costs: | 10,000-20.000 DKK, depending on milling system |
Emissions
VOC emissions at finish tanks are caused mainly by:
Displacement during charging to atmosphere.
Respiration losses to atmosphere.
Measures
Measures for cutting VOC emissions and their capital costs are:
F1: Isolation of tank by under-/overpressure valves
| Efficiency: | Nearly 100% because of closed system up to defined pressure (e.g. -5/+10 mbar) |
| Capital costs: | Approx. 10,000 DKK/valve |
| F2: Elevated exhaust points combined with manual control valve | |
| Efficiency: | Substantial decrease of VOC concentration in exhaust air |
| Capital costs: | 2,000-5,000 DKK |
5.7 Filter systems
Emissions
VOC emissions at filter systems are caused mainly by:
Open filter systems.
Cleaning of filter systems.
Operation of potentially leaky filter systems (e.g. sieve-type filter systems).
Measures
Measures for cutting VOC emissions and their capital costs are:
G1: Edge or bag filter
Replacement filter systems to avoid diffuse emissions should be procured.
| Efficiency: | Nearly 100% |
| Capital costs: | 20,000-40,000 DKK |
| G2: | Flexible extraction hood for open filter systems |
| Efficiency: | Improvement in personnel protection; reduction of diffuse emissions at place of work |
| Capital costs: | 8,000-12,000 DKK |
5.8 Filling systems
Emissions
VOC emissions at filling systems are caused mainly by:
Displacement of solvent vapour during filling.
Measures
Measures for cutting VOC emissions and their capital costs are:
H1: Stationary extraction hood and encapsulation of filling system
| Efficiency: | Nearly 100% reduction of diffuse emissions at the workplace |
| Capital costs: | 20,000-40,000 DKK, depending on size of filling station |
5.9 Rinsing basins
Emissions
VOC emissions at solvent-based rinsing basins are caused mainly by:
Manual cleaning of tools and small bins in open cleaning basins.
Drying of tools after cleaning them gives rise to solvent vapour emissions at rinsing basin locations.
Measures
Measures for cutting VOC emissions and their capital costs are:
I1: Encapsulated rinsing basins (fitted with lids) with automatic, directed exhaust air flow
For loading and unloading parts for rinsing, the lids of the rinsing basins are raised by a knee-operated device; air extraction switches in automatically by opening of the respective pneumatic dampers.
Additionally, solvent vapours are swept by the extraction airflow from the operator gangway to the exhaust duct.
The flow rate is around 2000 m³/h, but matched to the size of the rinsing basin, with VOC concentration 200-300 mg/m³, depending on flow rate and temperature.
Due to the high concentration, cleaning of the extracted exhaust is necessary for compliance with the emissions standards.
| Capital costs: | 160,000-200,000 DKK |
5.10 Solvent-based washing of mobile production bins in cleaning cabinet
Emissions
VOC emissions at solvent-based cleaning cabinets are caused mainly by:
Cleaning cabinets are not completely enclosed systems.
The cleaning cycle does not conclude with a drying step, so the cleaning cabinet location is exposed to organic solvents after removal of cleaned bins.
Generally, due to the high concentration of VOCs, the exhaust air requires post-treatment, like thermal combustion, for compliance with emission standards.
Measures
Measures for cutting VOC emissions and their capital costs are:
J1: Cabinet washing installation with water-based (e.g. hot alkaline) rinsing system
| Efficiency: | Emissions reduced by 100%, with no post-treatment needed for VOC removal; wastewater must be treated. |
| Capital costs: | 1,000,000-1,600,000 DKK, depending on plant size; additional costs for water treatment plant |
J2: Cabinet washing installation with solvent-based rinsing system and exhaust fume cleaning equipment
Cabinet washing installation with integrated fume extraction and drying is the present state of the art; explosion proofed; cleaning with rotating nozzle and high-pressure jet or rotating brushes.
Condensing system to remove a major part of the solvent emissions from the exhaust air.
| Distillation plant for recycling used solvent. | |
| Storage vessels for clean and used solvent. | |
| Efficiency: | Reduction of diffuse emissions at workplace by nearly 100%. Connection to incinerator or other exhaust air treatment plant is necessary for compliance with emission standards. |
| Capital costs: | Approx. 1,600,000 DKK, depending on plant size; additional costs for post-production clean-up, e.g. incineration, of exhaust air. |