Flammable emissions

Quite clearly, this discussion will raise many points for the designers to consider. Similarly, each of the other hazard prompts can be addressed. They will undoubtedly raise questions about the design of the venting system (toxic and flammable emissions), how to deal with a failure of the cooling water supply to the condenser, how to control and monitor the effluent discharge even under conditions of plant malfunction, instrument failure, loss of other services such as electrical supply and steam, human error, ease of safe maintenance and so on. The prompt internal fire may lead to a debate on the start-up of the system, when acetone vapour and air will be present initially. 

Table 5.10 lists polymers used for both water- and solvent-based adhesives. Water-based adhesives cost less than the equivalent solvent-based compounds. Even inexpensive organic solvents are costly when compared to water. The use of water eliminates problems of flammability, emission, and toxicity associated with organic solvents. However, in most cases, water-based adhesives must be kept from freezing during shipment and storage because of possible permanent damage to both the container and the contents. 

Udel is a slightly yellow but tianspaient engineering thermoplastic. It has low flammability and smoke emission and good electrical properties. It has excellent resistance to water, steam, and alkaline solutions. Specific uses for Udel iaclude microwave cookware, beverage dispensers, coffee brewers, cookware, hair dryers, com poppers, and steam table trays. Its steam resistance makes it particularly fit for a dishwasher environment. Properties of polysulfone resias ate given ia Table 11. 

Emission of toxic, flammable or corrosive vapors when equipment is opened for clean-ing/maintenance or during charging of hazardous material. Possibility for operator exposure. 

Loss of sealing fluid for vessel agitator seal. Possible seal failure and emission of flammable or toxic vapors. 

Waste treatment prior to disposal may introduee phase ehanges whieh result in quite different pollution eontrol eonsiderations. For example, the gases generated by ineineration of a solid waste ean be serubbed with liquid in order to meet an aeeeptable diseharge eriterion henee, in addition to ash for disposal, a liquid effluent stream is produeed and requires treatment. Other waste treatment proeesses may result in the liberation of flammable or toxie gaseous emissions as exemplified in Table 16.5. 

TRACE II Toxic Release Analysis of Chemical Emissions Safer Emergency Systems, Inc. Darlene Davis Dave Dillehay 756 Lakefield Road Westlake Villa, CA 91361 (818) 707-2777 Models toxic gas and flammable vapor cloud dispersion. Intended for risk assessment and planning purposes, rather than realtime emergencies. 

VDI Part 1 models the dispersion of vapor plumes with output consisting of vapor ctiriccntration as a function of time and downwind distance and denser-than-air vapor releases. VDI Part 2 determines the downwind distance to the lower flammable limit of a combustible vapor. Part 2 may also be used in conjunction with Part 1 to model a toxic gas emission. 

FIRE SIMULATOR predicts the effects of fire growth in a 1-room, 2-vent compartment with sprinkler and detector. It predicts temperature and smoke properties (Oj/CO/COj concentrations and optical densities), heat transfer through room walls and ceilings, sprinkler/heat and smoke detector activation time, heating history of sprinkler/heat detector links, smoke detector response, sprinkler activation, ceiling jet temperature and velocity history (at specified radius from the flre i, sprinkler suppression rate of fire, time to flashover, post-flashover burning rates and duration, doors and windows which open and close, forced ventilation, post-flashover ventilation-limited combustion, lower flammability limit, smoke emissivity, and generation rates of CO/CO, pro iri i post-flashover. 

The primary concern abont hazardons processes is that they be operated in a safe manner so that fires, deflagrations, detonations, and releases of flammable and toxic gases into the atmosphere or inside process bnildings are eliminated or minimized. Also of great concern from an environmental standpoint is the control and minimization of volatile organic componnd (VOC) emissions from process vents and fugitive sources. 

Additional experiments should be performed on a large scale to establish the emissive power of fireballs generated by BLEVEs. The effects of flammable substances involved, fireball diameter, and initial pressure should be investigated. 

Fire properties of insulation materials range from the highest to the lowest, from non-combustible to flammable with toxic fume emission. Generally, inorganic materials tend to be non-combustible while organic (or oil-based) materials are combustible, but many have surface treatments to improve their fire-safety rating. 

At present there is no small-scale test for predicting whether or how fast a fire will spread on a wall made of flammable or semiflammable (fire-retardant) material. The principal elements of the problem include pyrolysis of solids char-layer buildup buoyant, convective, tmbulent-boundary-layer heat transfer soot formation in the flame radiative emission from the sooty flame and the transient natme of the process (char buildup, fuel burnout, preheating of areas not yet ignited). Efforts are needed to develop computer models for these effects and to develop appropriate small-scale tests. 

The worst hazard scenarios (excessive temperature and pressure rise accompanied by emission of toxic substances) must be worked out based upon calorimetric measurements (e.g. means to reduce hazards by using the inherent safety concept or Differential Scanning Calorimetry, DSC) and protection measures must be considered. If handling hazardous materials is considered too risky, procedures for generation of the hazardous reactants in situ in the reactor might be developed. Micro-reactor technology could also be an option. Completeness of the data on flammability, explosivity, (auto)ignition, static electricity, safe levels of exposure, environmental protection, transportation, etc. must be checked. Incompatibility of materials to be treated in a plant must be determined. 

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