Particulate matter production

Applicable specifically to particulate matter emissions A. Decrease or eliminate particulate matter production... 

Information on particulate matter production in test fires has been compiled in Tables II-V. In a few instances, extinction cross sections were directly measured and used to derive the properties of the smoke particles. It is clear in all cases that available information is scanty, variable and uncertain. Because we are no experts in combustion research, we have checked our analysis with several combustion specialists and have gotten... 

G. A. Knauer, J. H. Martin and others, VERtical Transport and Exchange (VERTEX) program Pioneering research on the relationships between particulate matter production, export and remineralization tracer studies particle-associated nitrification trace element (Fe) controls on primary production establishment of an 18-month ocean time-series at 33°N, 139°W... 

The classification of the clean room for preparation of radiopharmaceuticals should be the outcome of a risk assessment and could be class B, C or D [11, 16, 17]. The risk assessment should take into account the use of closed systems, the time between preparation and use and the namre of the product. The critical working zone should be class A and can be realised with a radiopharmacy safety cabinet, an isolator or a hot cell (see Sect. 15.6.4). A compromise to respond to these demands could be an extra airlock between the clean room clothing area (first lock) and the preparation clean room [21]. The first lock has an overpressure of 10-15 Pa to the outside world for keeping out particulate matter (product protection). The second lock has an extra underpressure of — 10 to —15 Pa relative to the clean room to realise a deep underpressure (the so-called sink) for radioprotection and GMP-overpressure of 10 to 15 Pa between the clean room and this extra lock. See also Fig. 27.1. 

Plastic components can be leached into the product and the alkalinity also can be affected by certain types of glass (qv). Particulate matter can be introduced by flaking from container surfaces. The containers also must be able to withstand the heat and pressure of sterilization. 

Temperature. The temperature for combustion processes must be balanced between the minimum temperature required to combust the original contaminants and any intermediate by-products completely and the maximum temperature at which the ash becomes molten. Typical operating temperatures for thermal processes are incineration (750—1650°C), catalytic incineration (315—550°C), pyrolysis (475—815°C), and wet air oxidation (150—260°C at 10,350 kPa) (15). Pyrolysis is thermal decomposition in the absence of oxygen or with less than the stoichiometric amount of oxygen required. Because exhaust gases from pyrolytic operations are somewhat "dirty" with particulate matter and organics, pyrolysis is not often used for hazardous wastes. 

Beryllium, beryllium-containing aUoys, and beryUium oxide ceramic in soHd or massive form present no hazard whatsoever (31). SoHd shapes may be safely handled with bare hands (32) however, care must be taken in the fabrication and processing of beryUium products to avoid inhalation of airborne beryUium particulate matter such as dusts, mists, or fumes in excess of the prescribed workplace exposure limits. Inhalation of fine airborne beryUium may cause chronic beryUium disease, a serious lung disease in certain sensitive individuals. However, the vast majority of people, perhaps as many as 99%, do not react to beryUium exposure at any level (33). The biomedical and environmental aspects of beryUium have been summarized (34). 

Small organisms frequently become embedded within corrosion products and deposits. The organisms may make up a sizable fraction of the deposit and corrosion product. Seed hairs and other small fibers often blow into cooling towers, where they are transported into heat exchangers. The fibers stick to surfaces, acting like sieves by straining particulate matter from the water. Deposit mounds form, reinforced by the fibers (see Case History 11.5). 

The industries which produce and handle various stone products emit considerable amounts of particulate matter at every stage of the operation. These particulates may include fine mineral dusts of a size to cause damage to the lungs. The threshold values for such dusts have been set quite low to prevent disabling diseases for the worker. 

In the production of clay, talc, cement, chalk, etc., an emission of particulate matter will usually accompany each process. These processes may involve grinding, drying, and sieving, which can be enclosed and controlled to prevent the emission of particles. In many cases, the recovered particles can be returned to the process for a net economic gain. 

The most widely used pulping process is the kraft process, as shown in Fig. 6-11, which results in recovery and regeneration of the chemicals. This occurs in the recovery furnace, which operates with both oxidizing and reducing zones. Emissions from such recovery furnaces include particulate matter, very odorous reduced sulfur compounds, and oxides of sulfur. If extensive and expensive control is not exercised over the kraft pulp process, the odors and aerosol emissions will affect a wide area. Odor complaints have been reported over 100 km away from these plants. A properly controlled and operated kraft plant will handle huge amounts of material and produce millions of kilograms of finished products per day, with little or no complaint regarding odor or particulate emissions. 

Figure 30-lA presents the integrated environmental control potential for maximum control of particulate matter and SO2. Cooling tower water blowdown and treatment by-products may be used to satisfy scrubber makeup requirements. Fly ash and scrubber sludge will be produced separately. If the catalytic NO, process is required, the integration issues will be increased significantly. 

Figure 30-lC is distinctly different from the first two in the type of SO2 control processes used and the sequence of the particulate matter and SOj controls. It is a promising approach for up to 90% SO2 control of western United States coal, and there is a single waste product. Other features include the collection of particulate matter at temperatures below 90°C and the possibility for spray dryer cooling tower water integration. This. system may or may not include a catalytic NO unit. 

Alfalfa dehydration is carried out in a direct-fired rotary dryer. The dried product is transported pneumatically to an air cooler and then to a collecting cyclone. The collected particles are ground or pelletized and then packaged for shipment. The major atmospheric emission from the process is particulate matter, which is controlled by baghouses. Odors may also be a problem, but they disperse rapidly and are no longer a problem at distances of over 1 km. 

Wood-fired power boilers are generally found at the mills where wood products are manufactured. They are fired with waste materials from the process, such as "hogged wood," sander dust, sawdust, bark, or process trim. Little information is available on gaseous emissions from wood-fired boilers, but extensive tests of particulate matter emissions are reported (19). These emissions range from 0.057 to 1.626 gm per dry standard cubic meter, with an average of 0.343 reported for 135 tests. Collection devices for particulate matter from wood-fired boilers are shown in Table 30-21. 

A high-nickel alloy is used for increased strength at elevated temperature, and a chromium content in excess of 20% is desired for corrosion resistance. An optimum composition to satisfy the interaction of stress, temperature, and corrosion has not been developed. The rate of corrosion is directly related to alloy composition, stress level, and environment. The corrosive atmosphere contains chloride salts, vanadium, sulfides, and particulate matter. Other combustion products, such as NO, CO, CO2, also contribute to the corrosion mechanism. The atmosphere changes with the type of fuel used. Fuels, such as natural gas, diesel 2, naphtha, butane, propane, methane, and fossil fuels, will produce different combustion products that affect the corrosion mechanism in different ways. 

Atmospheric chemistry influences human health, climate, food production, and through its impact on visibility, our view of the world. Chemicals in the air affect us with each breath we take. Suspended particulate matter that form from gas-phase reactions affect the amount of solar energy reaching the earth s surface. 

Measures such as improved process design, operation, maintenance, housekeeping, and other management practices can reduce emissions. By improving combustion efficiency, the amount of products of incomplete combustion (PlCs), a component of particulate matter, can be significantly reduced. Proper fuel-firing practices and... 

Urea Plants - In urea plants, wet scrubbers or fabrie filters are used to control fugitive emissions from prilling towers fabric filters are used to eontrol dust emissions from bagging operations. These equipment are an integral part of the operations, to retain product. New urea plants should achieve levels of particulate matter in air emissions of less than 0.5 kg/t of product for both urea and ammonia. 

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