From controlled combustion process

Toxicity of Soot from a Controlled Combustion Process... 

Claus Sulfur Recovery Process The Claus process is a controlled combustion process commonly used for the recovery of sulfur from H2S. Temperatures >2,000°F (1,093.3°C) are achieved during combustion and yields of about 95% are typical. The basic reaction involves the following ... 

The chemical equilibrium assumption breaks down if the chemistry is fully or partly ki-netically controlled. Figure 13.2 shows the equilibrium concentrations of important components in a typical flue gas from a combustion process as function of temperature. 

There are an estimated 10000 to 11000 organo-chlorines in commercial production and many thousands more may be present, but are as yet unidentified, as by-products of the production. In addition, processes such as chlorination of sewage effluent to kill bacteria, result in active forms of chlorine which react with natural organic chemicals in the sewage to produce a myriad of organo-chlorines perhaps hundreds to thousands depending on the effluent and the chlorination conditions. Small amounts of organochlorines are also reported to result from various combustion processes, both natural fires and volcanic eruptions, and human-controlled processes such as incineration of wastes. 

Wastes from the combustion process include exhaust gases and, when coal or oil is used as the boiler fuel, ash. These wastes are typically controlled to reduce the levels of pollutants exiting the exhaust stack. Bottom ash, another by-product of combustion, also is discharged from the furnace. 

Scholes, C. A., Smith, K. H., Kentish, S. E., Stevens, G. W. (2010). Review—CO2 capture from pre-combustion processes—strategies for membrane gas separation. International Journal of Greenhouse Gas Control, 4, 739—755. 

Some beehive ovens, having various improvements and additions of waste heat boilers, thereby allowing heat recovery from the combustion products, may stiU be in operation. Generally, however, the beehive oven has been replaced by waH-heated, horizontal chamber, ie, slot, ovens in which higher temperatures can be achieved as well as a better control over the quality of the coke. Modem slot-type coke ovens are approximately 15 m long, approximately 6 m high, and the width is chosen to suit the carbonization behavior of the coal to be processed. For example, the most common widths are ca 0.5 m, but some ovens may be as narrow as 0.3 m, or as wide as 0.6 m. 

The plant is designed to satisfy NSPS requirements. NO emission control is obtained by fuel-rich combustion in the MHD burner and final oxidation of the gas by secondary combustion in the bottoming heat recovery plant. Sulfur removal from MHD combustion gases is combined with seed recovery and necessary processing of recovered seed before recycling. 

These ideas form the basis of most approaches to NO control with N-containing fuels. In principal, they are readily appHcable to the modification of certain combustors in which the desired divisions in the combustion process exist for other reasons. Although such improvements have been demonstrated, it is difficult in practice to make the required revisions in the air and fuel distribution without adverse effects on other emissions or on performance. It has also been shown that when steam is used to reduce thermal NO production, the formation of NO from fuel N is enhanced, or the reduction is less than otherwise expected. 

Hazards from combustion and runaway reactions play a leading role in many chemical process accidents. Knowledge of these reactions is essential for control of process hazards. It is important that loss of containment be avoided. For example ... 

Technological interest during these 30 years has focused on automotive air pollution and its control, on sulfur oxide pollution and its control by sulfur oxide removal from flue gases and fuel desulfurization, and on control of nitrogen oxides produced in combustion processes. 

Effective with the 1982 model year, particulate matter from diesel vehicles was regulated by the U.S. Environmental Protection Agency for the first time, at a level of 0.37 gm km . Diesel vehicles were allowed to meet an NO level of 0.93 gm km under an Environmental Protection Agency waiver. These standards were met by a combination of control systems, primarily exhaust gas recirculation and improvements in the combustion process. For the 1985 model year, the standards decreased to 0.12 gm of particulate matter per kilometer and 0.62 gm of NO per kilometer. This required the use of much more extensive control systems (1). The Clean Air Act Amendments of 1990 (2) have kept the emission standards at the 1985 model level with one exception diesel-fueled heavy trucks shall be required to meet an NO standard of 4.0 gm per brake horsepower hour. 

The first equation may be applied to a control volume CV surrounding a gas turbine power plant, receiving reactants at state Rg = Ro and discharging products at state Py = P4. As for the combustion process, we may subtract the steady flow availability function for the equilibrium product state (Gpo) from each side of Eq. (2.47) to give... 

Fig. 4.8 shows the open cooling process in a blade row diagrammatically. The heat transfer Q, between the hot mainstream (g) and the cooling air (c) inside the blades, takes place from control surface A to control surface B, i.e. from the mainstream (between combustion outlet state 3g and state Xg), to the coolant (between compressor outlet state 2c and state Xc). The injection and mixing processes occur within control surface C (between states Xg and Xc and a common fully mixed state 5m, the rotor inlet state). The flows through A plus B and C are adiabatic in the sense that no heat is lost to the environment outside these control surfaces thus the entire process (A + B + C) is adiabatic. We wish to determine the mixed out conditions downstream at station 5m. 

The combustion processes which control the critical depressurization rate are not understood. Landers (LI) and Von Elbe (VI) have tired to derive an expression for the critical depressurization rate, but the transient combustion model they used is far too simplified to predict the effects shown in Figs. 24 and 25. One possible explanation for these large variations would be that heat-release processes within the solid phase are important. From light-emission measurements during depressurization, Ciepluch observed that it was much easier to eliminate light emission than to terminate combustion (i.e., approximately 12,000 psi/sec produced light emission, compared with 100,000 psi/sec for termination). 

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