Parallel steam extraction energy level lifting system of steam turbine
Technical Field
The utility model belongs to the technical field of thermal power generation etc, especially to boiler air preheat, thermodynamic system backheat circulation and boiler flue gas waste heat and steam turbine exhaust waste heat recovery utilization, specifically, relate to a parallel steam extraction energy level hoist system of steam turbine.
Background
The mode of generating electricity by using energy contained in combustible materials and the like is generally called thermal power generation, and according to the power generation mode, the thermal power generation is divided into coal-fired steam turbine power generation, oil-fired steam turbine power generation, gas-steam combined cycle power generation and internal combustion engine power generation. The coal-fired thermal power generator set in the energy system of China is still the main energy, thermal power still occupies most of the market of electric power, and only if the thermal power technology is continuously improved and developed and the power generation efficiency is continuously improved, the thermal power generation can be gradually transformed into an efficient, clean and environment-friendly power generation mode, so that the requirements of the harmonious society are met.
The structural form of the turbine regenerative system is important for the efficiency of the thermal power generation system. At present, the domestic and foreign mature wet cooling units with the power of more than 300MW mostly adopt eight-stage regenerative steam extraction systems, the air cooling units mostly adopt seven-stage regenerative steam extraction systems, and through improving primary parameters, the regenerative stages are properly increased, an external steam cooler is arranged, and a secondary reheating technology and the like are adopted, so that the efficiency of a steam turbine can be further improved. However, in the research on the key technology of the regenerative system, only the turbine system is considered, and the boiler air and flue gas system as an important component of the thermal power generation system is not considered in the regenerative system of the turbine set.
SUMMERY OF THE UTILITY MODEL
The utility model overcomes prior art exists not enough, provides a parallel extraction steam energy level lift system of steam turbine, and the purpose is the low-level extraction steam latent energy of rational utilization backheat extraction steam, saves the power generation coal consumption, improves thermal power system thermal efficiency.
The utility model discloses a realize through following technical scheme.
A parallel steam extraction energy level lifting system of a steam turbine comprises a water circulation heat exchange system, an air preheater bin dividing system, a high-pressure water supply gas-water heat exchange system and a condensed water-gas-water heat exchange system; the water circulation heat exchange system comprises a plurality of steam heaters and an air gas-water heat exchanger, and the steam heaters correspond to the steam extraction stages of the low-pressure cylinder; the air preheater bin dividing system comprises an air preheater which is additionally provided with a bin, and the bin is connected with a bin dividing fan; the high-pressure water supply gas-water heat exchange system comprises a high-pressure water supply gas-water heat exchanger; the condensed water gas-water heat exchange system comprises a condensed water gas-water heat exchanger; the extraction pipeline export of low pressure jar is connected with water cycle heat transfer system and air heater in proper order, air heater's export pipeline is connected with boiler air system, the branch storehouse that boiler flue gas system and air heater increased is connected, divide the storehouse export respectively with high-pressure feedwater gas water heat exchanger, condensate water gas water heat exchanger links to each other and heats high-pressure feedwater and condensate water, the hot water export of high-pressure feedwater gas water heat exchanger and condensate water gas water heat exchanger is connected with steam turbine heat regeneration air exhaust system respectively, the extraction to high-pressure jar and intermediate pressure jar among the steam turbine heat regeneration air exhaust system is arranged and is crowded.
Furthermore, steam inlets of the steam heaters are connected with each stage of the low-pressure cylinder steam extraction system, hot water outlets of the steam heaters are sequentially connected in series and then connected with a high-temperature water inlet of the air-water heat exchanger, air from natural wind enters the air-water heat exchanger through a pipeline for heat exchange, and a cooling water outlet of the air-water heat exchanger is connected with a water inlet of the steam heater through a water circulating pump; the warm air outlet of the air-water heat exchanger is connected with the air preheater, the hot air outlet of the air preheater is connected with the air inlet of the coal mill, and the air powder outlet of the coal mill is connected into a boiler air system.
Furthermore, the bin dividing fan is connected with a cold air inlet of the air preheater, a bin dividing hot air outlet pipeline of the air preheater is connected with a hot air inlet of the high-pressure water supply gas-water heat exchanger, a hot air outlet of the high-pressure water supply gas-water heat exchanger is connected with a hot air inlet of the condensed water gas-water heat exchanger, and a warm air outlet pipeline of the condensed water gas-water heat exchanger is connected with an inlet of the bin dividing fan.
Further, a steam exhaust port of the low-pressure cylinder is connected with a condenser, and the condenser is connected with the condensed water gas-water heat exchanger through a first water outlet pipeline of the condensed water pump; a hot water outlet of the condensed water-gas-water heat exchanger is connected with a deaerator; and a flue gas pipeline of the boiler is connected with the air preheater through a denitration device.
Furthermore, each section of steam extraction of the low-pressure cylinder of the steam turbine respectively enters a first steam extraction pipeline and a second steam extraction pipeline, the first steam extraction pipeline and the second steam extraction pipeline are respectively connected with a steam heater, the steam heaters on the first steam extraction pipeline of each section of steam extraction are connected in series, the steam heaters on the second steam extraction pipeline of each section of steam extraction are connected in series, and a second water outlet pipeline of the condensate pump is connected with the steam heaters on the first steam extraction pipeline.
Furthermore, flue gas in the boiler enters the air preheater after being denitrated by the denitration device, exchanges heat with air in the air preheater, is dedusted by the deduster, is pressurized by the draught fan, enters the desulfurization device for desulfurization, and is discharged through the chimney.
Furthermore, the condensed water-gas-water heat exchanger is connected with a deaerator, an outlet of the deaerator is connected with an inlet of a high-pressure water feed pump, the feed water pressurized by the high-pressure water feed pump is divided into two paths, one path of the feed water enters an economizer inlet pipeline of the boiler after being heated by a steam heater, and the other path of the feed water is connected with an economizer inlet pipeline of the boiler after being heated by the high-pressure feed water-gas-water heat exchanger.
Furthermore, high-pressure water in the economizer is heated by a boiler to form main steam, and a main steam pipeline at the outlet of the boiler enters a high-pressure cylinder of a steam turbine to generate power.
The water circulation heat exchange system is of a closed water circulation structure, the closed water circulation heat exchange system is provided with steam heaters according to the corresponding stages of the back-heating steam extraction of the steam turbine, and the capacity of each stage of the steam heaters is determined according to the principle of heating step by step according to the corresponding steam extraction parameters. The temperature of the closed water in the closed water circulation heat exchange system after the last stage steam heater is heated through extraction steam meets the requirement of the steam heater end difference, and the temperature of the high-temperature closed water after the high-temperature closed water passes through the air-water heat exchanger of the boiler cold air system and then is cooled is determined according to the temperature of the condensation water entering the first stage low-pressure cylinder extraction steam system.
The heat capacity of the closed water circulation heat exchange system is determined according to the heat quantity required by the temperature of the last stage steam heater of the low-pressure cylinder steam extraction system after the temperature of all cold air of the boiler is heated from normal temperature (20 ℃) and the temperature difference of the heat exchanger is reduced.
The primary air is heated by the air-water heat exchanger and the air preheater to meet the air temperature requirement of the drying agent at the inlet of the coal mill. The secondary air is heated by the air-water heat exchanger and the air preheater to meet the requirement of the boiler on the air temperature of the secondary hot air inlet. The capacity of the air-water heat exchanger meets the requirement that all heat carried by the closed water circulation heat exchange system is brought to the cold air system.
The low-pressure cylinder steam extraction system is provided with a steam extraction system according to the corresponding stage number of the regenerative steam extraction of the steam turbine. The steam extraction amount of the low-pressure cylinder steam extraction system is determined according to the heat required by the steam heating amount of the corresponding closed water circulation heat exchange system, and the steam extraction amount meets the requirement of gradual heating according to the parameters of the steam turbine thermal equilibrium diagram.
The air preheater has a sub-chamber structure for absorbing the high-quality heat exhausted from the boiler fume system, and the circulated air in the sub-chamber does not participate in the combustion of the boiler and is a medium for transferring heat. The air in the sub-bin absorbs the high-quality heat exhausted and extruded in a boiler flue gas system in the air preheater, the heated air releases the heat when heating high-pressure feed water and condensed water in the air-water heat exchanger, the cooled air returns to the inlet of the fan of the sub-bin, and then enters the air preheater again to absorb the heat after being boosted by the fan of the sub-bin, and the circulation is carried out.
The bin capacity of the air preheater can be properly increased, and the increase range is considered according to the condition that the exhaust gas temperature of the boiler is reduced to the temperature without condensation.
The feed water in the high-pressure feed water gas-water heat exchanger is led out from a feed water pump outlet pipeline, and is heated by the high-pressure feed water gas-water heat exchanger and then is connected into a high-pressure feed water pipeline at the inlet of a boiler economizer.
The condensed water in the condensed water gas-water heat exchange system is led out from an outlet pipeline of the condensed water pump and is heated by the condensed water gas-water heat exchanger and then is connected into the deaerator.
The working process of the utility model is as follows:
the method comprises the following steps of heating closed water passing through corresponding parallel steam heaters step by increasing the steam extraction amount of a low-pressure cylinder, and heating air in a cold air system for the first time by the heated closed water through an air-water heat exchanger arranged in a boiler cold air system so as to bring part of low-quality heat of a steam turbine low-pressure cylinder system into the boiler air system; the closed water after heat exchange returns to the inlet of the water side of the parallel steam heater corresponding to the steam extraction through the closed water circulating water pump; the air after primary heating is heated by an air preheater to meet the requirements of the coal mill and the hearth on the air temperature; through the process, part of low-quality heat in the low-pressure cylinder system of the steam turbine is brought into a cold air system of the boiler, and the heat absorbed by the cold air system from a flue gas system of the boiler is correspondingly reduced; the corresponding discharged and extruded relatively high-quality heat in the boiler flue gas system is absorbed by air in a bin dividing system of the air preheater, the hot air sequentially heats part of high-pressure feed water from an outlet of a high-pressure feed water pump and part of condensed water from an outlet of a condensed water pump through a high-pressure feed water-gas heat exchanger and a condensed water-gas heat exchanger in the bin dividing system, the heated high-pressure feed water is connected to a feed water pipeline at an inlet of a boiler economizer, and the heated condensed water is connected to a deaerator, so that the discharged and extruded heat in the flue gas system is brought back to a turbine regenerative system through the high-pressure feed water and the condensed water; air in the sub-bin system cooled by the high-pressure feed water and the condensed water returns to an inlet of the sub-bin fan to prepare for the next circulation; the flue gas is subjected to heat exchange in the air preheater, passes through the dust remover, the draught fan and the desulphurization device, and is discharged to the atmosphere through the chimney.
The utility model discloses produced beneficial effect does for prior art.
1. The utility model discloses a thermal power factory's of thermal power system of parallel extraction energy level promotion technique efficiency for adopting traditional steam turbine to backheat the efficiency of extraction system and very improving.
2. The utility model can reduce the exhaust temperature by 10-30 degrees.
3. The utility model discloses optimized the backheating steam extraction system of steam turbine, the heat consumption of steam turbine, the electricity generation standard coal consumption of unit are very reduced, convert to the coal consumption then can reduce electricity generation standard coal consumption 10-20g kWh.
To sum up, the utility model discloses optimize the backheat steam extraction system of steam turbine, reduced the boiler exhaust gas temperature, reduced the heat consumption of steam turbine and the electricity generation coal consumption of unit, reached high-efficient, energy-conservation, emission reduction's effect.
Drawings
Fig. 1 is a schematic connection diagram of a parallel extraction level lifting system of a steam turbine according to embodiment 1 of the present invention.
Fig. 2 is a schematic connection diagram of a parallel extraction level lifting system of a steam turbine according to embodiment 2 of the present invention.
Fig. 3 is a schematic connection diagram of a parallel steam extraction energy level lifting system with an air cooling unit provided with closed water circulation heat exchange.
Fig. 4 is a schematic connection diagram of a parallel steam extraction level lifting system of an air cooling unit without closed water circulation heat exchange.
In the figure, 1 is a boiler; 2 is a high-pressure cylinder of the steam turbine; 3 is a turbine intermediate pressure cylinder; 4 is a low pressure cylinder of the steam turbine; 5 is a first high-pressure heater; 6 is a second high-pressure heater; 7 is a third high-pressure heater; 8 is a deaerator; 9 is a first low-pressure heater; 10 is a second low-pressure heater; 11 is a third low-pressure heater; 12 is a fourth low pressure heater; 13 is a shaft seal heater; 14 is a condensate pump; 15 is a condenser; 16 is a high-pressure water supply pump; 17 is a fourth parallel heater; 18 is a third parallel heater; 19 is a second parallel heater; 20 is a first parallel heater; 21 is a secondary air-water heat exchanger; 22 is a primary air-gas-water heat exchanger; 23 is a closed water circulating pump; 24 is a closed water constant pressure device; 25 is a condensed water gas-water heat exchanger; 26 is a high-pressure water supply gas-water heat exchanger; 27 is a primary air fan; 28 is a secondary fan; 29 is an N +1 bin fan; 30 is an air preheater; 31 is a coal mill; 32 is a dust remover; 33 is a draught fan; 34 is a desulfurizing device; 35 is a denitration device; and 36 is a chimney.
Detailed Description
In order to make the technical problem, technical scheme and beneficial effect that the utility model will solve more clearly understand, combine embodiment and attached drawing, it is right to go on further detailed description the utility model discloses. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The technical solution of the present invention is described in detail below with reference to the embodiments and the drawings, but the scope of protection is not limited thereto.
Example 1
As shown in fig. 1, the system is a parallel extraction energy level lifting system for a steam turbine, wherein, the extraction steam of the 8 sections of the low pressure cylinder 4 of the steam turbine is divided into two paths, one path is connected to a fourth low pressure heater 12, and the other path is connected to a fourth parallel heater 17; the 7-section steam extraction of the steam turbine low-pressure cylinder 4 is divided into two paths, one path is connected to a third low-pressure heater 11, and the other path is connected to a third parallel heater 18; the 6-section steam extraction of the steam turbine low-pressure cylinder 4 is divided into two paths, one path is connected to a second low-pressure heater 10, and the other path is connected to a second parallel heater 19; the 5-section steam extraction of the steam turbine low pressure cylinder 4 is divided into two paths, one path is connected to the first low pressure heater 9, and the other path is connected to the first parallel heater 20.
The closed water at the outlet of the closed water circulating water pump 23 is connected to a closed water inlet of a fourth parallel heater 17, the closed water outlet of the fourth parallel heater 17 is connected to a closed water inlet of a third parallel heater 18, the closed water outlet of the third parallel heater 18 is connected to a closed water inlet of a second parallel heater 19, the closed water outlet of the second parallel heater 19 is connected to a closed water inlet of a first parallel heater 20, the closed water outlets of the first parallel heater 20 are divided into two paths, one path is connected to the closed water inlet of the secondary air-gas-water heat exchanger 21, the other path is connected to the closed water inlet of the primary air-gas-water heat exchanger 22, the closed water at the outlets of the secondary air-gas-water heat exchanger 21 and the primary air-gas-water heat exchanger 22 is connected to the inlet of the closed water circulating water pump 23, and the closed water.
The ambient air is pressurized by the primary air fan 27 and then is connected to a cold air inlet pipeline of the primary air-water heat exchanger 22, a warm air outlet pipeline of the primary air-water heat exchanger 22 is connected to a primary air inlet pipeline of the air preheater 30, a primary hot air outlet pipeline of the air preheater 30 is connected to a primary air interface of the coal mill 31, and a primary air powder outlet of the coal mill 31 is connected to a primary air coal powder interface of the boiler 1.
The ambient air is pressurized by the secondary fan 28 and then is connected to the cold air inlet pipeline of the secondary air-water heat exchanger 21, the warm air outlet pipeline of the secondary air-water heat exchanger 21 is connected to the secondary air inlet pipeline of the air preheater 30, and the secondary hot air outlet pipeline of the air preheater 30 is connected to the secondary air interface of the boiler 1.
The environment air is pressurized by the N +1 bin-dividing fan 29 and then is connected to the cold air inlet pipeline of the N +1 bin of the air preheater 30, the hot air outlet pipeline of the N +1 bin of the air preheater 30 is connected to the hot air inlet pipeline of the high-pressure water supply gas-water heat exchanger 26, the hot air outlet pipeline of the high-pressure water supply gas-water heat exchanger 26 is connected to the hot air inlet pipeline of the condensed water gas-water heat exchanger 25, and the warm air outlet pipeline of the condensed water gas-water heat exchanger 25 is connected to the inlet pipeline of the N +1 bin-dividing fan 29.
The condensed water pipeline at the outlet of the condensed water pump 14 is heated by a shaft seal heater 13 and then divided into two paths, one path of the condensed water pipeline passes through a fourth low-pressure heater 12, a third low-pressure heater 11, a second low-pressure heater 10 and a first low-pressure heater 9 in sequence and then enters a deaerator 8 after being heated, heating and deaerating are carried out in the deaerator 8, and the other path of the condensed water pipeline is heated by a condensed water gas-water heat exchanger 25 and then enters the deaerator 8.
The outlet of the deaerator 8 is connected to the inlet of a high-pressure water feed pump 16, the feed water pressurized by the high-pressure water feed pump 16 is divided into two paths, one path of the feed water sequentially passes through a third high-pressure heater 7, a second high-pressure heater 6 and a first high-pressure heater 5 to be heated and then enters the economizer inlet pipeline of the boiler 1, and the other path of the feed water is heated by a high-pressure feed water gas-water heat exchanger 26 and then is connected to the economizer inlet pipeline of the boiler 1.
High-pressure feed water is connected into an economizer and then is heated by a boiler 1 to become main steam, a main steam pipeline at an outlet of the boiler 1 enters a high-pressure steam cylinder 2 of the steam turbine for power generation, one path of the main steam after work is taken is 1-section extraction steam and is connected into a first high-pressure heater 5, the other path of the main steam is exhaust steam and 2-section extraction steam of the high-pressure steam cylinder 2 of the steam turbine, the exhaust steam of the high-pressure steam cylinder 2 of the steam turbine is connected into a cold reheat steam (cold section) inlet of the boiler 1, and the 2-section extraction steam is connected into.
The cold reheat steam (cold section) becomes hot reheat steam (hot section) after boiler 1 heats, and hot section steam inserts 3 electricity generations in the steam turbine intermediate pressure jar, and the steam after doing the work is 3 sections steam extractions all the way and inserts third high pressure feed water heater 7, and another way is the steam extraction and the 4 sections steam extractions of steam turbine intermediate pressure jar 3, and 4 sections steam extractions are inserted into oxygen-eliminating device 8, and the steam extraction inserts steam turbine low pressure jar 4.
The steam after doing work in the steam turbine low pressure cylinder 4 is sequentially as follows: 5-section extraction steam is connected into a first low-pressure heater 9 and a first parallel heater 20; the 6-section extraction steam is connected into a second low-pressure heater 10 and a second parallel heater 19; 7-section steam extraction is connected into a third low-pressure heater 11 and a third parallel heater 18; 8-section extraction steam is connected into a fourth low-pressure heater 12 and a fourth parallel heater 17; the exhaust steam of the turbine low pressure cylinder 4 is connected into a condenser 15, and the exhaust steam is condensed into water in the condenser 15 and then is connected into an inlet of a condensate pump 14.
Flue gas in the boiler 1 enters the air preheater 30 after being denitrated by the denitrating device 35, is dedusted by the deduster 32 after being subjected to heat exchange with air in the air preheater 30, then enters the induced draft fan 33, is pressurized by the induced draft fan 33, then enters the desulfurizing device 34 for desulfurization, and then is discharged through the chimney 36.
Example 2
Referring to fig. 2, the parallel extraction steam level boost system of a steam turbine is different from that of embodiment 1 in that a closed water circulation heat exchange system is not provided, but the capacity of a condensate pump and the capacity of low-pressure heaters at each stage are increased. As shown in fig. 2: after being pressurized by a condensate pump 14, condensate from a condenser 15 passes through a shaft seal heater 13, a fourth low-pressure heater 12, a third low-pressure heater 11, a second low-pressure heater 10 and a first low-pressure heater 9 in sequence for heating, a part of the condensate enters a deaerator 8, the other part of the condensate enters a secondary air-water heat exchanger 21 and a primary air-water heat exchanger 22 water side inlet, and the secondary air-water heat exchanger 21 and the primary air-water heat exchanger 22 water side outlet are combined together and then return to a hot well of the condenser 15.
The above is stated to the steam turbine backheating steam extraction system of wet cooling unit, the utility model discloses equally also can be used to the air cooling unit, the flow chart of air cooling unit is shown in fig. 3, fig. 4.
The above description is for further details of the present invention with reference to specific preferred embodiments, and it should not be understood that the embodiments of the present invention are limited thereto, and it will be apparent to those skilled in the art that the present invention can be implemented in a plurality of simple deductions or substitutions without departing from the scope of the present invention, and all such alterations and substitutions should be considered as belonging to the present invention, which is defined by the appended claims.