RU2498091C1 - Method of operation of thermal power plant - Google Patents

Abstract

FIELD: power engineering.

SUBSTANCE: method of thermal power plant operation, according to which steam supplied in a forward-flow steam boiler after a live steam superheater is sent into a high pressure cylinder of a steam turbine, then a part of spent steam is sent to the second high pressure heater along with the feedwater flow and into an expansion turbine, the remaining part of steam arrives into a reheater, and then into a medium pressure cylinder and a low pressure cylinder of the turbine, afterwards the steam is condensed in a condenser and with a condensate pump is sent via low pressure heaters, where condensate is heated by steam of bleeds and steam from a turbodrive of a feed pump and then arrives into a deaerator of feedwater, where it is heated and deaerated by steam that exits from the expansion turbine; further feedwater from the deaerator of feedwater is supplied with a feed pump to the first high pressure heater along with the feedwater flow, where it is heated by steam from the expansion turbine, further feedwater arrives into the subsequent high pressure heaters, where it is heated by steam of the second and first bleeds of the steam turbine, afterwards it is sent into the forward-flow steam boiler.

EFFECT: invention makes it possible to reduce difference of temperatures between steam at the inlet to the first high pressure heater along feedwater flow and of feedwater at the outlet from it.

1 dwg

Description

The invention relates to the field of power engineering and can be used in thermal power plants.

A known method of operation of a thermal power plant, including a once-through boiler, a steam turbine, consisting of a high pressure cylinder (CVP), a medium pressure cylinder (CPS) and a low pressure cylinder (CPS), a steam condenser of a steam turbine, condensate pumps, low pressure regenerative heaters ( PND), feed water deaerator (DPA), feed water pump equipped with a turbo drive (ПТН), high pressure regenerative heaters (LDPE), through which steam from the first three withdrawals of a steam turbine is diverted to LDPE, and from Latter six - IPA, which successively heated main turbine condensate after the condenser and the feedwater; the second selection is carried out from the “cold” line of the intermediate superheat (CSP) of the steam, through which the steam after the central heating system is sent to the intermediate superheater (PP) of the direct-flow boiler and, then, is sent to the central cylinder; from the third selection, steam is also diverted to the ДПВ and the turbine drive of the feed pump, the spent steam of which is sent to the inlet of the low-pressure cylinder of the turbine (Yu.F. Kosyak “Steam turbine K-300-240 KhTGZ” - M .: Energoizdat, 1982. P.12 )

A disadvantage of the analogue is the reduced efficiency of the thermal power plant due to the high temperature difference of the steam of the third turbine and feed water outlet at the outlet of the first LDPE feed water.

Closest to the claimed invention is a method of heating feed water at a thermal power plant, in which feed water is sequentially heated by steam turbine offsets in HDPE, DPV and LDPE, in parallel with the latter, part of the feed water is heated in a remote desuperheater of the first high pressure heater along the feed water, moreover, the drainage of heating steam from the third LDPE along the feed water is discharged into the second, and from the second and first by separate flows into the RPA (patent RU 2053374).

The disadvantages of the prototype is the reduced efficiency of the thermal power plant due to the large difference in temperature of the steam at the inlet to the remote desuperheater and feed water at the outlet, as well as the drainage of the second LDPE feed water and feed water in the DPA.

The objective of the new method is to increase the efficiency of the thermal power plant.

The technical result achieved by the present invention is to reduce the temperature difference between the steam at the inlet of the first LDPE feed water and the feed water at the exit thereof.

The technical result is achieved by the fact that in the method of operation of a thermal power plant, steam from the first three selections of the steam turbine is fed to the LDPE, and of the last six to the HDPE, in which the main condensate of the turbine after the condenser and feed water are sequentially heated; the second selection is carried out from the “cold” line of intermediate overheating (CSP) of the steam, through which the steam after the CVP is sent to the intermediate superheater (PP) of the direct-flow boiler and, then, is sent to the CPS, also from the CSP, the steam is fed to a turboexpander located on one shaft with PTN, after expansion in a turboexpander, steam is supplied to the first LDPE and DPV along the feed water; steam is also taken from the third selection to the turbo drive of the feed pump, the spent steam of which is sent to the inlet of the low pressure cylinder of the steam turbine.

Thus, the steam passing through the turboexpander expands, performing work that is transmitted to the PTN shaft, as a result of which its temperature decreases, almost reaching the saturation temperature in the first in the course of the LDPE feed water, which makes the temperature difference between the steam at the inlet of the first in the course LDPE feed water and feed water at the outlet of it are significantly reduced and, consequently, irreversible losses during heat exchange between steam and feed water are reduced, which increases the useful work of the Rankine cycle and efficiency thermal power station.

The peculiarity lies in the fact that the steam sent to the DPV and the first along the LDPE feed water is supplied from the HPP and expanded in the turboexpander to a pressure equal to the pressure in the third extraction of the steam turbine, and the work performed by the steam in the turboexpander is transferred to the PTN shaft.

A new way of operating a thermal power plant allows you to increase the efficiency of a thermal power plant by reducing losses from the irreversibility of the heat exchange process between steam and feed water, in the first along the feed water of the LDPE.

Thus, the set of essential features set forth in the claims, allows to achieve the desired technical result.

Next, we consider the information confirming the possibility of carrying out the invention with obtaining the desired technical result.

The drawing shows a schematic diagram of a thermal power plant, explaining the proposed method. The station contains a steam boiler 1, a superheater of fresh steam 2, an intermediate superheater 3, a steam turbine with nine steam withdrawals 20-25 and 27-29, consisting of CVP 4, TsSD 5 and TsND 6, an electric generator 7, a condenser 8, a condensate pump 9 , PND 10, DPV 11, the feed pump 12 and the turbo drive of the feed pump 13, the turboexpander 14, the pipeline for supplying steam to the turboexpander 15, the pipeline for discharging steam from the turboexpander into the first along the feed water of the LDPE 16, the first along the feed water of the LDPE 17, the second by PVD feed water 18, third in x dy feedwater LDPE 19, discharge line steam turbine drive of feed pump 26.

Consider an example of the implementation of the claimed method of operation of a thermal power plant.

The steam generated in the once-through steam boiler after the superheater of fresh steam 2 is sent to the HPP 4 of the steam turbine, where it expands, completing the work transferred to the electric generator 7, and then part of the exhaust steam is sent to the second PVD 18 along the feed water and to the turbine expander 14 , the rest of the steam enters the intermediate superheater 3, and then in the DSP 5 and the low pressure cylinder 6, where the steam expands, doing the work transferred to the electric generator 7, after which the steam condenses in the condenser 8 and the pump 9 direction it is pumped through HDPE 10, where the condensate is heated by steam of samplings 23-25 and 27-29 and steam from the pipeline for removing steam from the turbo drive of the feed pump 26 and then enters the ДПВ 11, where it is heated and deaerated by steam leaving the turbine expander 14; Further, the feed water from the ДПВ 11 is supplied by the feed pump 12 through high-pressure heaters 17-19, where it is heated by steam of taps 20 and 21 and through the pipe 16 with steam from a turboexpander and then enters the direct-flow steam boiler 1.

Thus, the use of a turboexpander 14 to expand the steam of the second bleed 20 to a pressure equal to the vapor pressure of the third bleed 22, and the replacement of extremely superheated steam of the third bleed, fed into the steam and water dispenser 11 and the first in the direction of the feed water of the LDPE 17, with steam that has been spent in the turbine expander 14, allows to significantly reduce losses from the irreversibility of the heat transfer process in the DPV 11 and the first in the direction of the feed water LDPE 17, which increases the useful work of the Rankine cycle and the efficiency of the thermal power plant.

Claims (1)

A method of operating a thermal power plant, in which steam from a first selection of a steam turbine is supplied to a third high-pressure heater along the feed water, a second selection of steam turbines preceding the intermediate superheater is directed to a second high-pressure heater along the feed water; the steam after the high-pressure cylinder is sent to the intermediate superheater of the once-through boiler and then to the medium-pressure cylinder, characterized in that the steam sent to the feed water deaerator and the first high-pressure heater along the feed water is supplied from a turbine expander, in which the steam supplied from the selection of the steam turbine preceding the intermediate superheater expands to a pressure equal to the pressure in the third selection of the steam turbine, and the work performed by the steam in the turboexpander distributed on the shaft of the nutrient turbopump.

Images