Fume control

Design considerations and costs of the catalyst, hardware, and a fume control system are direcdy proportional to the oven exhaust volume. The size of the catalyst bed often ranges from 1.0 m at 0°C and 101 kPa per 1000 m /min of exhaust, to 2 m for 1000 m /min of exhaust. Catalyst performance at a number of can plant installations has been enhanced by proper maintenance. Annual analytical measurements show reduction of solvent hydrocarbons to be in excess of 90% for 3—6 years, the equivalent of 12,000 to 30,000 operating hours. When propane was the only available fuel, the catalyst cost was recovered by fuel savings (vs thermal incineration prior to the catalyst retrofit) in two to three months. In numerous cases the fuel savings paid for the catalyst in 6 to 12 months. 

Catalysis is utilized in the majority of new paper filter cure ovens as part of the oven recirculation/bumer system which is designed to keep the oven interior free of condensed resins and provide an exhaust without opacity or odor. The apphcation of catalytic fume control to the exhaust of paper-impregnation dryers permits a net fuel saving by oxidation of easy-to-bum methyl or isopropyl alcohol, or both, at adequate concentrations to achieve a 110—220°C exotherm. 

A 13.9 Electrostatic technique of powder painting 13/409 A13.I0 Effluent treatment and fume control 13/4l2... 

Training for all staff, covering both normal operation and emergency situations, is essential. The combination of measures used will depend upon the degree of hazard, and the scale and nature of the processes. For example, dust and fume control measures in the rubber industry are summarized in Table 5.19. 

Table 5.19 Combination of measures for dust and fume control in the rubber industry ...

Rubber Industry Advisory Committee - A New Practical Guide to Complying with COSHH in the Rubber Industry Dust Control in Powder Handling and Weighing Dust and Fume Control in Rubber Mixing and Milling Control of Solvents in the Rubber Industry... 

On oxygen steel conversion furnaces, primary fume control is usually achieved by a separate close-capture hood positioned over the vessel mouth. The enclosure is then used for secondary fume control during charging, turndown, tapping, and slagging. 

For a high-production furnace the fume volume flow rate after air dilution to 130 °C will be considerably higher than for secondary fume control by enclosure. A separate primary fume capture system would be used for this case. 

Fumes are defined as solid airborne particulates that have been produced by a change of state. Many industrial operations produce fumes which affect both the indoor environment and the outdoor environment. For many operations, fumes are generated by a high-temperature process. The gas stream containing the fume is usually of high temperature and contains combustibles. The combustibles may form an explosive mixture, thus necessitating specialized design inputs for most fume control ventilation systems. The major elements of a fume control system are pictured in Fig. 13.28. 

If the fume generation process cannot be eliminated, a fume control system must be designed- An overview of design methodology and design procedures for the different types of fume control systems follows. 

Detailed designs for fume control systems and selection [Pg.1268]

The first essential step in the design of a fume control system and selection of gas-cleaning equipment is the characterization of the fume emission source. Design procedures which can be used for new and existing industrial plants follow. The characterization of fume emission sources includes parameters such as plume flow rates (mVs), plume geometry (m), source heat flux (J/s), physical and chemical characteristics of particulates, fume loadings (mg/m ), etc. 

Coverall Overall fume control system performance... 

Consider a fume control system with an overall hood fume capture efficiency of 60% and a fume cleaning efficiency of 99%. Calculate overall fume control system performance. 

Solution The overall fume control system performance is (60)(99)... 

The technology in the fume capture field Is not well developed, and performances of many capture systems are low and typically may be in the 30% to 60% range. There is a paucity of fundamental research and development in the fume capture field. In contrast, hundreds of million of dollars have iteen spent on research and development activities in the gas-cleaning area, which is mature and well developed. It is not uncommon to specify and to measure gas-cleaning equipment performances of over 99.9% colleaion efficiency. As shown in Eq. (13.75), the ovcTall fume control system performance is determined by the product of the capture efficiency and the gas-cleaning efficiency. This equation clearly shows the need to improve the efficiency of capture of the fume at the source in order to obtain significant improvements in the overall fume control system performance. 

Table 13.17 lists some of the important considerations for the different fume capture techniques. From the point of view of cost effectiveness, the usual preference is source collection or a low-level hood, provided an acceptable scheme can be developed within the process, operating, and layout constraints. The cost of fume control systems is almost a direct function of the gas volume being handled. Flence, the lower volume requirements for the source capture or low-level hood approach often results in significant capital and operating cost savings for the fume control system. 

The factors affecting the performance of a local exhaust system are well known. For fume control, an added factor is the effect of heat release or buoyancy. Important design parameters are process heat release and the size and geometry of air-supply openings and their location relative to major surfaces of the enclosure, lire kxation of the fume off-take is usually only of secondary importance. 

Goodfellow, H. D. Fume Control for Electric Furnaces—Past, Present and Future. Ventilation 94, Stockholm, September 5-9, 1994,... 

Goodfellow, H. D. Ventilation Systems for Fume Control. Brussels von Karmen Institute for Fluid Dynamics (May 1998,1. 

Direct flame incineration A fume control device in which organic pollutants in the waste gas stream are oxidized to form nonpolluting by-products. 

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