Category / Title
NFR: / 2.D.3.g / Chemical products
SNAP: / 060301
060302
060303
060304
060305
060306
060307
060308
060309
060310
060311
060312
060313
060314 / Polyester processing
Polyvinylchloride processing
Polyurethane foam processing
Polystyrene foam processing
Rubber processing
Pharmaceutical products manufacturing
Paints manufacturing
Inks manufacturing
Glues manufacturing
Asphalt blowing
Adhesive, magnetic tapes, films and photographs manufacturing
Textile finishing
Leather tanning
Other
ISIC:
Version / Guidebook 20132016
Coordinator
Jeroen Kuenen & Carlo Trozzi
Contributing authors (including to earlier versions of this chapter)
Stephen Richardson, Wilfried Winiwarter, Marc Deslauriers and Mike Woodfield
Contents
1 Overview 3
2 Description of sources 3
2.1 Process description 3
2.2 Techniques 7
2.3 Emissions 7
2.4 Controls 9
3 Methods 13
3.1 Choice of method 13
3.2 Tier 1 default approach 14
3.3 Tier 2 technology-specific approach 15
3.4 Tier 3 emission modelling and use of facility data 27
4 Data quality 27
4.1 Completeness 27
4.2 Avoiding double counting with other sectors 27
4.3 Verification 27
4.4 Developing a consistent time series and recalculation 28
4.5 Uncertainty assessment 28
4.6 Inventory quality assurance/quality control QA/QC 28
4.7 Gridding 28
4.8 Reporting and documentation 28
5 Glossary 29
6 References 29
7 Point of enquiry 31
1 Overview
This chapter covers the emissions from the use of chemical products. This includes many activities, as can be seen in the chapter heading. However many of these activities are considered insignificant, meaning that emissions from these activities contribute less than 1% to the national total emissions for every pollutant. However, care should be taken; in some countries activities not considered in this chapter may be significant for the national total of non-methane volatile organic compound (NMVOC) emissions.
This chapter deals with emissions from:
· polyurethane and polystyrene foam processing;
· asphalt blowing;
· tyre production;
· speciality organic chemical industry;
· manufacture of paints, inks and glues;
· fat, edible and non-edible oil extraction;
· industrial application of adhesives.
For all these processes, source descriptions and Tier2 emission factors are available in this Guidebook.
This document has been drafted using texts from an earlier version of the Guidebook and more recent information from the Expert Group on Techno-economic Issues (EGTEI, 2003) and International Institute for Applied Systems Analysis (IIASA, 2008). Additional technical information that is not included in this chapter can be found in BIPRO (2002).
2 Description of sources
2.1 Process description
This section gives brief process descriptions of some important processes within this source category. The descriptions are largely based on the EGTEI background reports (EGTEI, 2003) and an earlier version of the Guidebook. More detailed descriptions may be found in the BREF documents that cover the processes discussed in this chapter. These may be the documents on Surface Treatment using Organic Solvents and Production of Speciality Inorganic Chemicals. Because there is a strong link between this source category and the chemical industry, further explanations may also be found in Chapter 2.B Chemical industry.
2.1.1 Polyurethane and polystyrene foam processing
Foam processing deals with the application and subsequent discharge of organic compounds as blowing agents for creating plastic foams (polyurethane and polystyrene). These blowing agents need to be liquids characterised by a low boiling point. By application of external heat (polystyrene) or due to the reaction heat (polyurethane), the liquid evaporates and helps create the foam, without actually taking part in the reaction. Chlorofluorocarbons (CFCs) (such as F11, F12, F22) have been used for polystyrene processing; most of these are now replaced by pentane. In extruded polystyrene, other types of chemicals are used. In polyurethane, CFCs were also used, but presently other types of blowing agents are used. In polyurethane, the types of blowing agents used depend on the final use of the foam. Butane and pentane can be used as many substitutes of CFC such as HFC and HCFC. Some polyurethane foams can be expanded directly with CO2 resulting from a reaction between polyols and water.
Emissions are from the release of these blowing agents during foaming, or subsequently by the long-term release over several years, and are strictly evaporative. The production of the raw materials is included in SNAP code 040500 covering bulk chemical production.
Polyurethane (PUR) and polystyrene (EPS) are used in building construction, for heat insulation, and for packaging material. Characteristic is a high proportion of on-site foaming, i.e. only the production takes place in well defined production plants, the foaming (EPS) and the actual formation (PUR) directly at the site needed, which leads to direct emissions without foreseeable control.
a) Polyurethane
Polyurethane is produced by the exothermic reaction of iso-cyanates with alcohols. About 80% of the world production is foams (Stoeckhert et al, 1993), which are created by adding blowing agents. For soft polyurethane foams water may be used, which binds with iso-cyanate to form CO2. Hard polyurethane foams utilise organic liquids as blowing agents, which evaporate due to the heat formation of the reaction. Hard foam is known for its good sealing and insulation properties. This also determines its use in refrigeration equipment as well as in the building and construction industry. While prefabricated compounds can be attributed to production sites directly, a considerable proportion of polyurethane foam is produced and applied directly, for example at a construction site. Figures for Germany (Greenpeace, 1991) indicate that this ‘direct production’ is almost as large as prefabrication (7000t CFCs used, vs. 9500t).
Another aspect of the sealing properties is that the blowing agent is included into the cells of the structure, and only eventually released. According to the German estimation (Rentz et al, 1993), only about 15–25% of the blowing agent applied is released immediately; the rest is stored inside the cells of the foam and released eventually. Again, estimations are available for Germany (Plehn, 1990). The total amount of stored F11 (70000t) is about five times the annual usage of CFCs for hard foam polyurethane.
b) Polystyrene
Pentane-impregnated polystyrene beads contain about 6% in mass of pentane. They are processed as follows (CCME, 1997; EGTEI, 2005):
· heating and stirring in an expander with steam. Pentane acts as a blowing agent which, when heated with steam, expands the beads. Additives such as antistatic and mould-release agents are also added to the vessel;
· drying in a fluidised bed: the resulting ‘pre-expanded beads’ are transferred to a fluidised bed dryer where they are dried and screened to remove the agglomerated beads;
· storage: dried pre-expanded beads are stored in large-volume hanging cloths or mesh sacks for between a few hours to several days according to the final product density to be obtained. During this curing time, air permeates into the beads and restores their internal pressure;
· moulding: the cured pre-expanded beads are transferred into a mould where steam is admitted. The beads expand again but are constrained by the mould. They squeeze out all space and fuse together to make an article of a shape determined by the mould;
· storage of products. When insulation blocks are produced, the storage time again depends on the quality of insulation block to be obtained (density of these blocks).
When insulation boards are produced, EPS blocks are cut with electrically-heated taut wires to the final dimensions desired. According to the products manufactured, one or two stages of pre-expansion and curing are required. Polystyrene wastes (polystyrene wastes from the production as recovered used polystyrene) can be recycled. All NMVOC emissions result from the release of blowing agent (pentane) from the beads during processing, curing, moulding and storage (EGTEI, 2005).
2.1.2 Asphalt blowing
Asphalt blowing is used for polymerising and stabilising asphalt to improve its weathering characteristics. Air-blown asphalts are used in the production of asphalt roofing products, in the installation of built-up roofs and for the repair of leaky roofs. Air blowing of asphalt may be conducted at oil refineries, asphalt processing plants and asphalt roofing plants. The emissions from asphalt blowing are still primarily organic particulate with a fairly high concentration of gaseous hydrocarbon and polycyclic organic matter.
Asphalt blowing involves the oxidation of hot asphalt flux which is achieved by the bubbling air of the blowing still. Air is forced through holes in the sparger into a tank of hot asphalt flux. The result is an exothermic oxidation reaction, which raises the softening temperature of the asphalt, as well as modifying other characteristics.
The process is highly temperature dependent, as the rate of oxidation increases rapidly with increases in temperature. Since the reaction is exothermic, the temperature rises as blowing proceeds. Temperatures must be kept safely below the flash point of the asphalt. The temperature is therefore kept at an optimum level of 260oC during blowing by spraying water onto the asphalt surface. For some crude auxiliary cooling may also be required.
Inorganic salts such as ferric chloride (FeCl3) may be used as catalysts to achieve the desired properties and/or to increase the rate of reaction, thus decreasing the blowing time. Blowing times may vary in duration from 30 minutes to 12 hours, depending on the desired characteristics of the asphalt (softening point, penetration rate).
Stills may be either vertical or horizontal. Vertical stills are preferred because of the increased asphalt-air contact and consequent reduction in blowing times, as well as lower asphalt losses.
Asphalt blowing can be either a batch process or a continuous operation. Typically, stills at roofing plants and processing plants may be run as batch processes, while refineries may run in both modes, depending on the product demand.
In Canada, the percentage of asphalt produced that was sold for non-asphalt purposes, and was therefore likely to have been blown, ranged from 16.4 to 24.7% of total reported asphalt sales in the period 1983 to 1991. In the U.S., 14% of total sales was reported for non-paving uses in 1991. (Asphalt Institute 1992).
2.1.3 Tyre production
Tyres are produced using a large variety of materials. The main process steps are:
· mixing,
· extrusion,
· calendering,
· building,
· curing (vulcanisation).
2.1.4 Speciality organic chemical industry
This industry is very heterogeneous: plants manufacture a large range of products, using a large number of production processes and may store and use several hundred raw material substances or intermediate products. Processes are usually operated on a campaign basis and in multipurpose plants. For one active ingredient, several transformation stages are required. The processes typically involve between 1 to 40 transformation stages depending on molecules. Process stages cover the full range of unit operations, such as reactions, liquid/liquid extraction, liquid/liquid or liquid/solid or gas/solid separation, distillation, crystallisation, drying, gas adsorption, etc. Production is carried out in discontinuous processes (or batch processes). Equipment is rarely specific but, most often, multi-application. Processes frequently use solvents. Any reacted raw materials may be either recovered or recycled or ultimately discharged to the environment after appropriate treatment (HMSO, 1993; EGTEI, 2003).
Because of the diversity of processes used in this sector, no simple process description can be made (HMSO, 1993). Instead, a brief outline of characteristics of existing pharmaceutical product production plants is provided (Syndicat, 1998; Industrial experts, 1998; Allemand 1998).
2.1.5 Manufacture of paints, inks and glues
Raw materials used in the products manufacturing process include solids, binders, solvents and all kinds of additives.
· Solids provide the coating with colour, opacity, and a degree of durability.
· Binders are components which form a continuous phase, hold the solids in the dry film, and cause it to adhere to the surface to be coated. The majority of binders are composed of resins and drying oils which are to a great extent responsible for the protective and general mechanical properties of the film (more significant in decorative paints).
· For viscosity adjustment, solvents are required. Materials that can be used as solvents include aliphatic and aromatic hydrocarbons, alcohols, esters, ketones, and esters and ether-esters of ethylene and propylene glycol.
· Additives are raw materials which are added in small concentrations (0.2–10%). They perform a special function or give a certain property to the coating. Additives include driers, thickeners, antifoams, dispersing agents, and catalysts.
The function of each paint is the same whether it is based on alkyd or latex (based on styrene-butadiene polymers). The selection of which to use will depend on the substrate and desired performance.
Only physical processes as weighing, mixing, grinding, tinting, thinning, and packaging take place; no chemical reactions are involved. These processes are carried out in large mixing tanks at approximately room temperature.
Figure 21 Process scheme for source category 2.D.3.g Chemical products
2.2 Techniques
Techniques are described in subsection 2.1 of the present chapter.
2.3 Emissions
2.3.1 Polyurethane and polystyrene foam processing
Emissions are due to evaporation of blowing agents and consist of CFCs or alkanes (pentane, butane), respectively. All blowing agent used will eventually be emitted into the atmosphere, unless some kind of capturing device exists. However, it may take years until all of the blowing agent is released from the cells of a PUR foam.
Depending on the blowing agent, emissions used to be F11, F12, F22, butane and pentane. Nowadays, emissions are almost exclusively pentane, since this is the most frequently used blowing agent and since it is forbidden by law to use F-gases.
2.3.2 Asphalt blowing
Asphalt blowing stills are sources of particulate hydrocarbon, gaseous hydrocarbon and carbon monoxide. Emissions of gaseous hydrocarbons are small because of the prior removal of volatile hydrocarbons in the distillation units.
The type of crude and characteristics of the asphalt may influence the emissions. For instance, the US Environmental Protection Agency (USEPA, 1980) hypothesizes that uncontrolled emissions are higher for asphalts derived from the more volatile West Coast or Middle East crudes than from the mid-continent crudes. Process parameters influencing emissions include the blowing temperature, air rate, design/configuration of the still, and the type of product desired (e.g. saturant or coating asphalt).