Stack gas quantity

Here is a handy graph for estimating stack gas quantity. 

GPSA Engineering Data Book, Gas Processors Suppliers Association, Vol. I, 10th Ed. 

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A zeolite catalyst operated at 1 atm and 325-500 K is so active that the reaction approaches equilibrium. Suppose that stack gas having the equilibrium composition calculated in Example 7.17 is cooled to 500 K. Ignore any reactions involving CO and CO2. Assume the power plant burns methane to produce electric power with an overall efficiency of 70%. How much ammonia is required per kilowatt-hour (kWh) in order to reduce NO , emissions by a factor of 10, and how much will the purchased ammonia add to the cost of electricity. Obtain the cost of tank car quantities of anhydrous ammonia from the Chemical Market Reporter or from the web. 

Several uncertainties in this periodic process have not been resolved. Pressure drop is too high at SV = 10,000 h 1 when packed beds of carbon are used. Study of carbon-coated structured packing or of monoliths with activated carbon washcoats is needed to see if lower pressure drops at 95% SO2 removal can be achieved. Stack gas from coal or heavy oil combustion contains parts-per-million or -per-billion quantities of toxic elements and compounds. Their removal in the periodically operated trickle bed must be examined, as well as the effect of these elements on acid quality. So far, laboratory experiments have been done to just 80°C use of acid for flushing the carbon bed should permit operation at temperatures up to 150°C. Performance of periodic flow interruption at such temperatures needs to be determined. The heat exchange requirements for the RTI-Waterloo process shown in Fig. 26 depend on the temperature of S02 scrubbing. If operation at 150°C is possible, gas leaving the trickle bed can be passed directly to the deNO, step without reheating. 

Many of the conservation measures require detailed process analysis plus optimization. For example, the efficient firing of fuel (category 1) is extremely important in all applications. For any rate of fuel combustion, a theoretical quantity of air (for complete combustion to carbon dioxide and water vapor) exists under which the most efficient combustion occurs. Reduction of the amount of air available leads to incomplete combustion and a rapid decrease in efficiency. In addition, carbon particles may be formed that can lead to accelerated fouling of heater tube surfaces. To allow for small variations in fuel composition and flow rate and in the air flow rates that inevitably occur in industrial practice, it is usually desirable to aim for operation with a small amount of excess air, say 5 to 10 percent, above the theoretical amount for complete combustion. Too much excess air, however, leads to increased sensible heat losses through the stack gas. 

Rows below the last one shown can be used to calculate intermediate quantities.) Execute enough runs (including the two shown above) to determine the effea on the stack gas composition of each of the five input parameters. Then for the values of p, q, r, and x% given in part (a), find the minimum percentage excess air needed to keep the dry-basis SO2 composition below 700 ppm. (Make this the last run in the output table.)... 

What are the compositions (mole and mass fractions) and volumetric flow rates (m /kmol CH4 fed to burners) of (a) the effluent gas from the reformer burners and (b) the gas entering the stack What is the specific gravity, relative to ambient air (30X, 1 atm, 70% rh), of the stack gas as it enters the stack Why is this quantity of importance in designing the stack Why might there be a lower limit on the temperature to which the gas can be cooled prior to introducing it to the stack ... 

Tn 1970, 20 million tons of sulfur dioxide emitted from steam electric-power plants. Without control measures these emissions will increase to 40 million tons by 1980. With typical SO2 concentrations in stack gas currently in the range of 1000-2000 ppm, target levels for future control legislation correspond to 50-150 ppm SO2 in the stack, and there are not sufficient low sulfur fuels to meet these standards. To fill the gap between projected supplies of low sulfur fuels and our nation s energy requirements, an economical, high efficiency process to remove SO2 from the fiue gases of power plants is required. Such a process must also recover SO2 in a form which can be readily handled and sold, in recognition of the quantities involved. Furthermore such a process must be compatible with the many constraints public utilities face in its installation and operation. 

Description A tray or compartment diyer is an enclosed, insulated housing in which solids are placed upon tiers of trays in the case of particulate solids or stacked in piles or upon shelves in the case of large objects. Heat transfer may be direct from gas to sohds by circulation of large volumes of hot gas or indirect by use of heated shelves, radiator coils, or refractoiy walls inside the housing. In indirec t-heat units, excepting vacuum-shelf equipment, circulation of a small quantity of gas is usually necessary to sweep moisture vapor from the compartment and prevent gas saturation and condensation. Compartment units are employed for the heating and diying of lumber, ceramics, sheet materi s (supported on poles), painted and metal objects, and all forms of particulate solids. 

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