Power plants – Motive fluid energized by externally applied heat – Process of power production or system operation
Patent
1983-05-13
1985-10-29
Husar, Stephen F.
Power plants
Motive fluid energized by externally applied heat
Process of power production or system operation
60659, F01K 300
Patent
active
045494010
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method and apparatus for reducing the losses which occur initially on start-up and which subsequently occur during the following stabilization period prior to normal running conditions; the invention also relates to a method and apparatus for increasing the usable power and for improving the controllability of a thermal power plant.
During the initial start-up period and the immediately following stabilization period in conventionally operated thermal power plants, large quantities of steam must bypass the turbine complex through the condenser. During this process, enormous quantities of heat remain unused and are given off via the condenser cooling water and the cooling tower into the atmosphere.
In particular, with large power plant systems, the initial start-up period and the subsequent stabilizing period can take up to an hour or more, depending on the condition of the installation. In addition to this, many conventional power plant systems must be shut down regularly at weekends and at night. The quantities of heat which are produced during these start-up and stabilizing periods, and which constitute a considerable fraction of the total amount of converted thermal energy, are released unutilized.
It has also been found, unfortunately, that a power plant system cannot be controllably operated when working at its upper load limit, especially at the limit of its rated pyrometric power, since, in order to attain power-controlled operation, it is necessary to retain a certain controllable load reserve in order to compensate for fluctuations in the demand.
Compensation of the control deviations in the electrical power of a power plant system from the demand power can only be effected via the time-behavior of the steam production and the storage capacity of the steam generator which decisively determines the controllability of the power plant system.
The object of the invention is to improve the economy of operation of a power plant by reducing the initial start-up and following stabilizing period losses and thereby increasing the plant's utilizable power. A further objective of the invention is to improve the controllability of a power plant.
In accordance with the invention, this object is accomplished by arranging for one or more pressurized heat storage reservoirs to be integrated into the power plant's water-steam cycle, the said heat storage reservoirs being charged by supplying them with excess heat produced in the power plant and, in the event of an increased demand for steam, discharging the said heat storage reservoirs by releasing stored heat back again into the water-steam cycle.
The pressurized heat storage reservoirs are charged during the start-up and stabilizing processes with start-up steam or stabilization period steam.
The pressurized heat storage reservoirs return their charged energy to the power plant's water-steam cycle during periods of high load or periods when there is an increased demand for power to produce electrical energy.
Thus, it is possible, with the method according to the invention, to store an appreciable fraction of the energy, hitherto given-off, unused, into the atmosphere during the start-up and following stabilizing phases of a power plant system, and to use this energy during periods of increased power demand.
In order to effect a further increase in the upper load limit, it is additionally advantageous, during low or partial load periods, to charge the pressurized heat storage reservoirs with hot condensate via medium pressure/low pressure preheaters using steam bled from the medium pressure steam system and/or suitable extractions from the medium pressure and/or low pressure turbines.
In an additional embodiment of the method according to the invention, control deviations in the electric power from the demand power of a power plant system are at least partially compensated by changes made in the pressurized heat storage reservoirs' charging or discharging flow.
By this means, it is additionally possible to reduce a power plant system's a
REFERENCES:
patent: 1770256 (1930-07-01), Smekal
patent: 4129004 (1978-12-01), Thelen et al.
patent: 4130992 (1978-12-01), Bitterlich et al.
patent: 4291537 (1981-09-01), Oplatka
Brown Boveri Mitteilungen, Aug., 1980, p. 459.
Husar Stephen F.
Ljungman Nils H.
Saarbergwerke Aktiengesellschaft
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