Exiting gases exit temperature

Operational Characteristics. Oxygen generation from chlorate candles is exothermic and management of the heat released is a function of design of the total unit iato which the candle is iacorporated. Because of the low heat content of the evolved gas, the gas exit temperature usually is less than ca 93°C. Some of the heat is taken up within the candle mass by specific heat or heat of fusion of the sodium chloride. The reacted candle mass continues to evolve heat after reaction ends. The heat release duting reaction is primarily a function of the fuel type and content, but averages 3.7 MJ/m (100 Btu/fT) of evolved oxygen at STP for 4—8 wt % iron compositions. 

In converter passes downstream of the first pass, exit temperatures are limited by thermodynamic equiUbrium to around 500°C or less. To obtain optimum conversion, the heats of reaction from succeeding converter passes are removed by superheaters or air dilution. The temperature rise of the process gas is almost direcdy proportional to the SO2 converted in each pass, even though SO2 and O2 concentrations can vary widely. 

The carbon monoxide concentration of gas streams is a function of many parameters. In general, increased carbon monoxide concentration is found with an increase in the carbon-to-hydrogen ratio in the feed hydrocarbon a decrease in the steam-to-feed-carbon ratio increase in the synthesis gas exit temperature and avoidance of reequiUbration of the gas stream at a temperature lower than the synthesis temperature. Specific improvement in carbon monoxide production by steam reformers is made by recycling by-product carbon dioxide to the process feed inlet of the reformer (83,84). This increases the relative carbon-to-hydrogen ratio of the feed and raises the equiUbrium carbon monoxide concentration of the effluent. 

An equation representing an energy balance on a combustion chamber of two surface zones, a heat sink Ai at temperature T, and a refractory surface A assumed radiatively adiabatic at Tr, inmost simply solved if the total enthalpy input H is expressed as rhCJYTv rh is the mass rate of fuel plus air and Tp is a pseudoadiabatic flame temperature based on a mean specific heat from base temperature up to the gas exit temperature Te rather than up to Tp/The heat transfer rate out of the gas is then H— — T ) or rhCp(T f — Te). The... 

What is the sink-side efficiency T)i, the gas exit temperature Te, and the mean flux density through the tube surface ... 

Note that under choked conditions, the exit velocity is V = V = c = V/cKTVM not V/cKT(/M, . Sonic velocity must be evaluated at the exit temperature. For air, with k = 1.4, the critical pressure ratio p /vo is 0.5285 and the critical temperature ratio T /Tq = 0.8333. Thus, for air discharging from 300 K, the temperature drops by 50 K (90 R). This large temperature decrease results from the conversion of internal energy into kinetic energy and is reversible. As the discharged jet decelerates in the external stagant gas, it recovers its initial enthalpy. 

Drying conditions, because of turbulence and gas mixing, are uniform throughout the chamber i.e., the entire chamber is at the gas exit temperature—this fact has been well estabhshed in many chambers except in the immediate zone of gas inlet and spray atomization. 

They include the combustion chamber, gas burners, burner controls, and exit temperature indicator. Usual exit temperatures for the destruction of most organic materials are in the range of 650°-825°C, with retention times at the elevated temperature of 0.3-0.5 sec. 

The use of pyrometers in control of the advanced gas turbines is being investigated. Presently, all turbines are controlled based on gassifier turbine exit temperatures, or power turbine exit temperatures. By using the blade metal temperatures of the first section of the turbine the gas turbine is being controlled at its most important parameter, the temperature of the first stage nozzles and blades. In this manner, the turbine is being operated at its real maximum capability. 

The gas turbine eontrol loop eontrols the Inlet Guide Vanes (IGV) and the Gas Turbine Inlet Temperature (TIT). The TIT is defined as the temperature at the inlet of the first stage turbine nozzle. Presently, in 99% of the units, the inlet temperature is eontrolled by an algorithm, whieh relates the turbine exhaust temperature, or the turbine temperature after the gasifier turbine, the eompressor pressure ratio, the eompressor exit temperature, and the air mass flow to the turbine inlet temperature. New teehnologies are being developed to measure the TIT direetly by the use of pyrometers and other speeialized probes, whieh eould last in these harsh environments. The TIT is eontrolled by the fuel flow and the IGV, whieh eontrols the total air mass... 

The use of pyrometers in eontrol of the advaneed gas turbines is being investigated. Presently all turbines are eontrolled based on gasifier turbine exit temperatures or power turbine exit temperatures. By measuring the... 

An expansion turbine (also called turboexpander) converts gas or vapor energy into mechanical work as the gas or vapor expands through the turbine. The internal energy of the gas decreases as work is done. The exit temperature of the gas may be very low. Therefore, the expander has the ability to act as a refrigerator in the separation and liquefaction of gases. 

Rice [15] made a comprehensive study of the reheated gas turbine eombined plant. He first analysed the higher (gas turbine) plant with reheat, obtaining (t o)h> turbine exit temperature, and power turbine expansion ratio, all as funetions of plant overall pressure ratio and firing temperatures in the main and reheat burners. (The optimum power turbine expansion ratio is little different from the square root of the overall pressure ratio.) He then pre-seleeted the steam eyele eonditions rather than undertaking a full optimisation. 

Although it would be possible to design for an economizer gas exit temperature of 30-50°C above the feedwater temperature, this would result in a temperature too close to the acid dewpoint of the gases. The acid dewpoint is the temperature at which acidic gases begin to condense out of the exhaust gas mixture. This is principally sulfuric acid due to the sulfur contained in the oil or coal. Although the bulk gas temperature may be satisfactory, in practice, the... 

Condensing boilers are now available for both gas- and oil-fired plant, the advantage of these being that the flue gases are further cooled down to below 100°C so that the latent heat available in the flue gas water vapor is recovered. The condensate has to be removed and the boiler capital cost is higher than for conventional plant. However, the boiler plant efficiency is increased to the order of 90 per cent, based upon the fuel gross calorific value. Where the flue gas exit temperatures are in excess of 200° C a further economy can be obtained by the provision of a spray recuperator in the case of gas and flue gas economizers for oil and coal. 

In addition, the use of water-wall design lowered gas exit temperatures, which increased boiler efficiency and reduced the potential for rapid degradation of refractory surfaces caused by the buildup of slag (molten ash). All larger WT boilers today employ water-wall membrane designs in their construction. 

A typical simulation result is shown in Fig. 3. Under the given conditions, the concentration of fuel gas in bulk phase at the exit (Fig. 3a) is zero and the concentration of evaporative fuel gas at solid phase (Fig. 3b) at the exit did not reach the equilibrium concentration of activated carbon during adsorption. These results indicate that the canister of ORVR system is properly designed to adsorb the evaporative fuel gas. The temperature changes in canister (Fig. 3 c) during the operation remains in the acceptable range. The test results for different weather conditions showed that the canister design in this study can fulfill the required performance. 

Figure 3.54 Measured gas exit temperatures for a catalytic H2/O2 reaction with varying H2 content in 0.5 sipm synthetic air (A) and oxygen (T) enriched air (0.1 sipm oxygen -r 0.2 sipm nitrogen) [115].

Waste-heat boilers are often used to recover heat from furnace flue gases and the process gas streams from high-temperature reactors. The pressure, and superheat temperature, of the stream generated will depend on the temperature of the hot stream and the approach temperature permissible at the boiler exit (see Chapter 12). As with any heat-transfer equipment, the area required will increase as the mean temperature driving force (log mean AT) is reduced. The permissible exit temperature may also be limited by process considerations. If the gas stream contains water vapour and soluble corrosive gases, such as HC1 or S02, the exit gases temperature must be kept above the dew point. 

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