JP4619563B2 - Ultra turbine - Google Patents

Description

[0001]
[Industrial application fields]
Industrial gas turbines, which have excellent thermal efficiency, have begun to be increasingly used in recent years, as small as a distributed type, as a medium size as an emergency power source for hotels and hospitals, and as a large size as a combined cycle in a large-scale power plant. The present invention can be used as a means for further improving the thermal efficiency of these gas turbines, but is mainly intended for small gas turbines having an output of about 30 kW or less, which are referred to as microturbines.
[0002]
[Prior art]
FIG. 1 shows the operating cycle of a current gas turbine in relation to temperature and entropy. Entropy is a thermodynamic parameter that represents fluid loss. In the state of 1 in the figure, the atmosphere is sucked in, compressed to 2, heated from 2 to 3, expanded by a turbine from 3 to 4, and released into the atmosphere in the state of 4 to complete one cycle. All of these processes are performed at a higher pressure than the atmosphere. Since the exhaust gas in the state No. 4 has a high temperature of about 600 ° C., cogeneration that re-enters the boiler and recovers the exhaust heat by using steam or hot water is spreading. As another technology for improving efficiency, an attempt to reduce the amount of input fuel by exchanging heat between the exhaust heat in the state 4 in FIG. 1 and the compressed air in the state 2 to increase the air temperature in the state 2 is a small gas turbine. It is made in.
[0003]
[Problems and Means to be Solved by the Invention]
In order to improve the thermal efficiency of gas turbines, the method of preheating the high-temperature gas from the compressor with the turbine exhaust gas as described above is currently the only absolute method, but the working gas at the outlet of the compressor is already at a high temperature. The heat exchange efficiency is poor. Therefore, the thermal efficiency of a 30 kW commercially available small gas turbine cannot exceed 25%. Even small gas turbines require a fuel pump of about 3 to 5 atm, which is cumbersome and hinders its spread. Boiler equipment is required for exhaust heat recovery.
The present invention solves these drawbacks. First, a conceptual diagram of the invention of claim 1 is shown in FIG. The fresh air preheated in the low-temperature side heat exchanger section 4 for sucking outside air provided for heat exchange flows into the combustor 1 at a pressure slightly lower than the atmospheric pressure, so a special fuel pump is not required and There is an advantage that it can be directly supplied from a gas pipe for use. The calculation of thermodynamics was performed assuming a small gas turbine with an output of 30 kW. If the pressure ratio is 3, the heat insulation efficiency of the turbine 2 and the compressor 3 is 85%, the turbine inlet temperature is 900 ° C., the outlet temperature is 600 ° C., and the heat exchange temperature efficiency is 80%, the thermal efficiency in question becomes 35%. The reason why such a relatively high thermal efficiency is obtained is that the temperature is preheated from the atmospheric temperature. In the present invention, since the combustor 1, the turbine 2 and the compressor 3 are arranged in the reverse order to that of a normal gas turbine, air at atmospheric temperature can be heated, so that the thermal efficiency is superior to the conventional system.
Although Claim 1 is a simple system, there is still room for improvement in terms of thermal efficiency. Therefore, a new function is added in the invention of Claim 2, and its conceptual diagram is shown in FIG. Cooling of the working gas from the turbine 2 outlet to the compressor 3 outlet is performed in two stages of air and fluid. That is, fresh air is used while the gas immediately after the turbine outlet is still relatively hot, and this preheated air is used as the working gas. For example, it is performed with air taken from outside until the working gas at the turbine outlet 600 ° C. is cooled to 200 ° C. After that, the temperature of the working gas at the compressor inlet is cooled to about 20 ° C. using a fluid, Further, the compressor 3 is intercooled by the heat exchanger 5. In the case of the 30 kW small gas turbine mentioned above, the work required for compression is reduced and the thermal efficiency can be 45%. If water is used as the fluid, hot water is obtained, and a boiler is not necessary. If natural gas is used for the fluid, it becomes a vaporization plant.
Claim 3 performs cooling of the working gas only with the fluid, and the concept of the invention is shown in FIG. At this time, since the working gas is not preheated, the efficiency is low, and since it is intermediately cooled by the heat exchanger 5, the thermal efficiency of about 30% is maintained. Use only when large amounts of vaporized gas or hot water are needed.
[0004]
【The invention's effect】
Gas turbines are promising heat engines for energy conversion that are closely related to energy problems and carbon dioxide emission reduction problems. Increasing thermal efficiency is becoming increasingly important for humanity. According to the present invention, the concept of the conventional system in which compressed air is heated with exhaust gas is reversed, and a high thermal efficiency of 45%, which has not been achieved with a small gas turbine, can be achieved. The effect is that, even if the compressor is intercooled in the conventional system, the air temperature before combustion is lowered and the efficiency is not improved. However, in the present invention, since the combustor is located in front of the turbine, if the compressor is intercooled, the thermal efficiency is reliably improved. Furthermore, the greatest effect of the present invention is that the outside air that cools the working gas exiting the turbine for increasing the shaft output can be used twice as a preheated air for fuel saving. Therefore, high thermal efficiency of 45%, which has been impossible with a small gas turbine, is achieved. No boiler is required to get hot water or steam from the exhaust gas. No special equipment is required for fuel input to the combustor. It is safe to perform combustion in a state close to atmospheric pressure. Evaporation of hot water and natural gas is obtained as a by-product of power generation.
[Brief description of the drawings]
FIG. 1 is a cycle diagram of a conventional gas turbine. FIG. 2 is a cross-sectional view showing the concept of the present invention in claim 1. FIG. 3 is a conceptual diagram of claim 2. FIG. 4 is a conceptual diagram of claim 3. Explanation of symbols]
B Combustor C Compressor T Turbine G Generator

Claims (3)

In a power generator where a combustor is placed in front of the turbine of a turbomachine in which the turbine and the compressor are connected by a shaft and the working gas passes through the combustor, the turbine, and the compressor in this order and is discharged to the outside, the turbine outlet method of heat cooling the hot working gas to the compressor outlet to preheat the fresh air conducted by heat exchange with the outside air introduced by utilizing the suction force of the compressor to flow as a working gas to the combustor and organ.   The high-temperature working gas according to claim 1 is cooled by using a fluid newly introduced by a pump or the like provided outside the power generator in addition to the outside air, and only the preheated outside air is put into the combustor of the power generator to operate. Gas heat engine.   A heat engine for cooling a high-temperature working gas from a turbine outlet to a compressor outlet by pumping fluid by a pump or the like provided outside the power generation device of claim 1.

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