Temperature exit turbine

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... 

If the gases leave the tower at 6 atm, 25°C, and are expanded to, say, 1.5 atm, calculate the turbine exit gas temperatures without preheat, and if the gases are preheated to 400°C with the reactor off-gas. Also, estimate the power recovered from the preheated gases. 

An ideal Brayton cycle with regeneration has a pressure ratio of 10. Air enters the compressor at 14.7 psia and 29°F. Air enters the combustion chamber at 610°F. Air enters the turbine at 1520°F. The turbine exit air pressure is 15.0 psia. The air mass flow rate is 0.41 Ibm/sec. The turbine efficiency is 85%, and the compressor efficiency is 82%. Determine (a) the exit air temperature of the compressor, (b) the inlet air temperature of the combustion chamber, (c) the power required by the compressor, (d) power produced by the turbine, (e) rate of heat added, (f) back-work ratio, (g) net power produced, and (h) the cycle efficiency. 

Determine (a) the exit air temperature of the compressor, (b) the inlet air temperature of the combustion chamber, (c) the power required by the compressor, (d) power produced by the turbine, (e) rate of heat added, (f) back-work ratio, (g) net power produced, and (h) the cycle efficiency. 

The proposed General Atomics GT-MHR," with a direct recuperative gas-turbine cycle, has an efficiency of 48% with an exit gas temperature of 850°C. The AHTR, with an indirect recuperative multireheat gas-turbine cycle (Fig. 2.11), has an efficiency of 54%—assuming the same temperatures and turbomachinery parameters. Current materials may allow molten salt temperatures of 750°C. At these temperatures, the AHTR matches the efficiency of the GT-MHR with its exit helium temperature of 850°C. At 1000°C turbine inlet temperature that might be obtained with advanced materials, using the same fuel that currently limits the GT-MHR to an exit heliiun gas temperature of 850°C, and taking advantage of the improved heat transfer properties of the molten salt (see above), the efficiency of the AHTR can exceed 59%. 

This would bring the exit gas temperature down to about 55°C. Bearing in mind that the air will have been more or less saturated as it left the fuel cell, we would anticipate a good deal of condensation in the turbine, which would inhibit its performance. We should therefore perhaps round down our estimated power from the turbine to the still by no means negligible 10 kW. The power from the motor driving the screw compressor will therefore be about 47 kW. This is a very substantial parasitic power loss, and largely explains why the traction motor mentioned above is rated at 160 kW, whereas the fuel cell is 260 kW. The other major losses are the cooling system (estimated at 20-kW parasitic losses) and the electrical sub-systems, estimated at 13 kW. 

The third strategy is used to automate heat rate to follow slow or fast changes of heat load in the IHX perturbed from the thermal production plant. As the IHX primary exit flow temperature rises or falls in response to a change in the IHX secondary heat load, the flow valve CV3 opens or closes to introduce more or less of cold flow to upstream of the turbine from the compressor discharge to the mrbine inlet so as to keep the turbine inlet temperamre constant. The overall control strategy aims to continue normal power generation, unaffected by any heat load change in the IHX. 

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. 

This design has a number of tubes embedded inside the turbine biade to provide ehanneis for steam. In most cases these tubes are constructed from copper for good heat-transfer conditions. Steam injection is becoming the prime source of cooiing for gas turbines in a combined cycie appiication. The steam, which is extracted from the exit of the HP Turbine, is sent through the nozzie biades, where the steam is heated, and the biade metai temperature decreased. The steam is then injected into the flow stream entering the IP steam turbine. This increases the overaii efficiency of the combined cycie. 

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... 

Beeause of temperature eonstraints, the transdueers, whieh usually do not operate above 350 °F (177 °C) are loeated outside the engine. A probe is then loeated inside to direet the air to the transdueer. Most manufaeturers provide probes to measure the eompressor inlet pressure, eompressor exit pressure, and the turbine exhaust pressure. These probes are usually loeated along the shroud of the maehine, and therefore, the pressure readings may be slightly in error due to boundary-layer effeets. 

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. 

Calculation of the specific work and the arbitrary overall efficiency may now be made parallel to the method used for the a/s cycle. The maximum and minimum temperatures are specified, together with compressor and turbine efficiencies. A compressor pressure ratio (r) is selected, and with the pressure loss coefficients specified, the corresponding turbine pressure ratio is obtained. With the compressor exit temperature T2 known and Tt, specified, the temperature change in combustion is also known, and the fuel-air ratio / may then be obtained. Approximate mean values of specific heats are then obtained from Fig. 3.12. Either they may be employed directly, or n and n may be obtained and used. 

There is a link between the thermal efficiency and the turbine exit temperature Te. It results from expressing the thermal efficiency of the cycle in the form... 

For two step cooling, now with irreversible compression and expansion, Fig. 4.7 shows that the turbine entry temperature is reduced from Ti. to by mixing with the cooling air i/ H taken from the compressor exit, at state 2, pressure p2, temperature T2 (Fig. 4.7a). After expansion to temperature Tg, the turbine gas flow (1 + lp ) is mixed with compressor air at state 7 (mass flow i/h.) at temperature Tg. This gas is then expanded to temperature T g. 

For the various reversible cycles described in Section 4.2.1, the thermal efficiency was the same, independent of the number of cooling. steps. This is not the case for the irreversible cycles described in this section. Both the thermal efficiency and the turbine exit temperature depend on the number and nature of cooling steps (whether the cooling air is throttled or not). 

From (a) and (b), the stagnation pressure and temperature can thus be calculated at exit from the cooled row they can then be used to study the flow through the next (rotor) row. From there on a similar procedure may be followed (for a rotating row the relative (7 o)r, i and (po)k replace the absolute stagnation properties). In this way, the work output from the complete cooled turbine can be obtained for use within the cycle calculation, given the cooling quantities ip. 

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