阅读说明：本技术 一种低热值联合循环机组煤压机间冷热量利用系统及方法 (Cold and heat utilization system and method for coal press room of low-heat-value combined cycle unit ) 是由 张传辉 左德权 唐健 于兰兰 陈赛科 龚伟 于 2020-12-29 设计创作，主要内容包括：本发明提供一种低热值联合循环机组煤压机间冷热量利用系统及方法,包括间冷热量系统,间冷热量系统包括间冷管道、流通于间冷管道内的间冷换热介质、设置于该间冷水管道上的间冷泵、煤压机中间换热器和锅炉给水换热器,间冷热量系统中的间冷换热介质,在煤压机中间换热器中冷却高温高压煤气过程中被加热,并且由间冷管道流经锅炉给水换热器,加热流经位于锅炉给水换热器的锅炉给水,不仅提高了锅炉的给水温度,充分利用了间冷热量；同时,提高了锅炉排烟温度,防止尾部换热面的腐蚀,即无需减少余热锅炉低压部分换热面积,使得机组可以产生更多的蒸汽,提高联合循环机组效率。(The invention provides a system and a method for utilizing cold and heat between coal presses of a low-heat-value combined cycle unit, which comprises an inter-cold and heat system, wherein the inter-cold and heat system comprises an inter-cooling pipeline, an inter-cooling heat exchange medium circulating in the inter-cooling pipeline, an inter-cooling pump arranged on the inter-cooling water pipeline, an intermediate heat exchanger of the coal press and a boiler water supply heat exchanger; meanwhile, the exhaust gas temperature of the boiler is improved, the corrosion of a tail heat exchange surface is prevented, namely, the heat exchange area of a low-pressure part of the waste heat boiler does not need to be reduced, so that the unit can generate more steam, and the efficiency of the combined cycle unit is improved.)

1. A cold and heat utilization system of a coal press room of a low-heat-value combined cycle unit comprises a coal gas compressor (10), a gas turbine (20), a waste heat boiler (30), a steam turbine (40), a condenser (41), a fuel pipeline (21), a water supply pipeline (42), a steam pipeline (43) and a flue gas pipeline (22); the gas compressor (10) is communicated with the gas turbine (20) through a fuel pipeline (21), and the gas turbine (20) is communicated with the waste heat boiler (30) through a flue gas pipeline (22); the waste heat boiler (30) is communicated with the steam turbine (40) through the steam pipeline (43), and the steam turbine (40), the condenser (41) and the waste heat boiler (30) are communicated through the water supply pipeline (42) in sequence; the method is characterized in that:

the system comprises an indirect cooling pipeline (51), indirect cooling heat exchange media flowing in the indirect cooling pipeline (51), an indirect cooling pump (52) arranged on the indirect cooling pipeline, a coal press intermediate heat exchanger (53) and a boiler water supply heat exchanger (54), wherein the cold side of the coal press intermediate heat exchanger (53) is communicated with the hot side of the boiler water supply heat exchanger (54) through the indirect cooling pipeline (51);

the coal gas compressor (10) comprises a coal press high-pressure section (11) and a coal press low-pressure section (12), an indirect cooling fuel pipeline (13) is connected between a fuel outlet of the coal press low-pressure section (12) and a fuel inlet of the coal press high-pressure section (11), and the indirect cooling fuel pipeline (13) is communicated with the hot side of the coal press intermediate heat exchanger (53);

and a water supply pipeline (42) connected between the condenser (41) and the waste heat boiler (30) is communicated with the cold side of the boiler water supply heat exchanger (54).

2. The system for utilizing cold and heat of the coal press room of the combined cycle unit with a low heating value as set forth in claim 1, wherein the room cold and heat system further comprises a surface cooler group (60), the surface cooler group (60) is communicated with the air inlet of the gas turbine (20) through an air pipe (61), and the room cold pipe (51) connected with the outlet side of the intermediate heat exchanger (53) of the coal press is further communicated with the surface cooler group (60).

3. The system for utilizing the cold and heat in the coal press room of the combined cycle unit with low heating value as claimed in claim 1, characterized in that the room cold and heat energy system also comprises a surface cooler group (60) and an absorption refrigeration system, the surface cooler group (60) is communicated with an air inlet of the gas turbine (20) through an air pipeline (61), the absorption refrigeration system comprises an absorption refrigerator (70), a freezing water pipe (74) and a freezing water pump (73) arranged on the freezing water pipe (74), the absorption chiller (70) comprises a chiller generator (71) and a chiller evaporator (72) connected, an indirect cooling pipeline (51) connected with the outlet side of the coal press intermediate heat exchanger (53) is also communicated with the refrigerator generator (71), the refrigerator evaporator (72) is communicated with the surface cooler group (60) through a freezing water pipe (74).

4. The system for optimizing and utilizing the cold and heat of the coal press room of the combined cycle unit with the low heating value as claimed in claim 1, characterized by further comprising a cooling system, wherein the cooling system comprises a cooling water pipeline (80) and a room cold and heat cooler (55), the room cold pipeline (51) connected between the boiler feed water heat exchanger (54) and the coal press middle heat exchanger (53) is communicated with the hot side of the room cold and heat cooler (55), and the cold side of the room cold and heat cooler (55) is communicated with the cooling water pipeline (80).

5. The system for utilizing cold and heat between coal press rooms of a combined cycle plant with a low heating value as claimed in claim 1, wherein the cooling medium circulating in the cooling water pipeline (80) is open water.

6. The system for utilizing the cold and heat of the coal press room of the combined cycle unit with the low heating value as claimed in claim 1, wherein the medium for exchanging heat of the cold and heat of the room is closed water.

7. A cold and heat utilization system of a coal press room of a low-heat-value combined cycle unit comprises a coal gas compressor (10), a gas turbine (20), a waste heat boiler (30), a steam turbine (40), a condenser (41), a fuel pipeline (21), a water supply pipeline (42), a steam pipeline (43) and a flue gas pipeline (22); the gas compressor (10) is communicated with the gas turbine (20) through the fuel pipeline (21), and the gas turbine (20) is communicated with the waste heat boiler (30) through the flue gas pipeline (22); the waste heat boiler (30) is communicated with the steam turbine (40) through the steam pipeline (43), and the steam turbine (40), the condenser (41) and the waste heat boiler (30) are communicated through the water supply pipeline (42) in sequence; the method is characterized in that: the system also comprises a room cold and heat system, wherein the room cold and heat system comprises a coal press middle heat exchanger (53); the coal gas compressor (10) comprises a coal press high-pressure section (11) and a coal press low-pressure section (12), an indirect cooling fuel pipeline (13) is connected between a fuel outlet of the coal press low-pressure section (12) and a fuel inlet of the coal press high-pressure section (11), and the indirect cooling fuel pipeline (13) is communicated with the hot side of the coal press intermediate heat exchanger (53); and a water supply pipeline (42) connected between the condenser (41) and the waste heat boiler (30) is communicated with the cold side of the coal press intermediate heat exchanger (53).

8. A use method of the cold and heat utilization system of the coal press room of the combined cycle unit with low heating value according to claim 1, characterized in that the gas turbine (20) is operated, the inter-cooling pump (52) and the boiler feed water heat exchanger (54) are started, and the inter-cooling heat exchange medium enters the coal press intermediate heat exchanger (53) and exchanges heat with the fuel passing through the inter-cooling fuel pipeline (13); the heated indirect cooling heat exchange medium in the indirect cooling pipeline (51) is used as a heat source to enter the boiler water supply heat exchanger (54) to heat the condensed water from the water supply pipeline (42), and the condensed water is heated and then enters the waste heat boiler (30).

9. The method for utilizing the cold and heat in the coal press room of the combined cycle unit with the low heating value as claimed in claim 8, wherein the method comprises the following steps: the inter-cooling heat and power system further comprises a surface cooler group (60), the surface cooler group (60) is communicated with an air inlet of the gas turbine (20) through an air pipeline (61), and an inter-cooling pipeline (51) connected with the outlet side of the coal press intermediate heat exchanger (53) is further communicated with the surface cooler group (60);

when the inlet air of the gas turbine (20) needs to be heated, the surface cooler group (60) is started, and the high-temperature indirect cooling heat exchange medium extracted from the outlet of the coal press intermediate heat exchanger (53) by the surface cooler group (60) serves as a heat source to heat the air flowing into the surface cooler group (60); the heated air flows into the gas turbine (20) through an air duct (61).

10. The method for utilizing the cold and heat in the coal press room of the combined cycle unit with the low heating value as claimed in claim 9, wherein the method comprises the following steps: the inter-cold heat quantity system further comprises an absorption refrigeration system, the absorption refrigeration system comprises an absorption refrigerator (70), a freezing water pipe (74) and a freezing water pump (73) arranged on the freezing water pipe (74), the absorption refrigerator (70) comprises a refrigerator generator (71) and a refrigerator evaporator (72) which are connected, an inter-cold pipeline (51) connected with the outlet side of the coal press intermediate heat exchanger (53) is also communicated with the refrigerator generator (71), and the refrigerator evaporator (72) is communicated with the surface cooler group (60) through the freezing water pipe (74);

when the inlet air of the gas turbine (20) needs to be cooled, the high-temperature indirect cooling heat exchange medium extracted from the outlet of the coal press intermediate heat exchanger (53) by the surface cooler group (60) is cut off; starting the absorption refrigerator (70) and a freezing water pump (73), wherein the absorption refrigerator (70) extracts a high-temperature intercooling heat exchange medium as a driven heat source from an outlet of the coal press intermediate heat exchanger (53), and after the absorption refrigerator (70) is driven, freezing water generated by a refrigerator evaporator (72) enters an external cooler group (60) to cool air flowing into the external cooler group (60); the cooled air flows into the gas turbine (20) through the air duct (61).

Technical Field

The invention relates to the field of combined cycle units, in particular to a system and a method for utilizing cold and heat between coal presses of a low-heat-value combined cycle unit.

Background

The steel industry is a resource and energy-intensive industry, and a process gas with a lower heat value is generated in the process: blast furnace gas, coke oven gas, converter gas and the like, and steel plants usually build self-contained power plants by taking the low-heat-value process gas as fuel, wherein a gas-steam combined cycle unit (a combined cycle unit for short) with the characteristics of large single-machine capacity, small occupied area, environmental protection, high efficiency and the like becomes the optimal choice.

The method is suitable for a gas turbine (combustion engine for short) in a combined cycle unit of low-calorific-value fuel, and has certain pressure requirement on the fuel. The low-calorific-value fuel is generally normal pressure, a gas compressor (coal press for short) is needed to raise the fuel pressure to the fuel pressure required by a combustion engine, and the coal press has higher outlet pressure, so that the fuel compression process needs to be realized by adopting a sectional compression mode and an intermediate cooling mode (intermediate cooling for short), and a large amount of low-quality heat exists in an intermediate cooling system.

The low-heat value coal gas generated in the process of the steel plant has high sulfide content, and the flue gas discharged by a gas turbine has high dew point temperature due to high oxygen-sulfur compound content, so that the high exhaust gas temperature of the waste heat boiler needs to be ensured in order to prevent the corrosion problem of the heat exchange surface at the tail part of the waste heat boiler in the combined cycle unit, usually the heat exchange surface at the low-pressure part of the waste heat boiler is reduced, and the high exhaust gas temperature is ensured by reducing the steam yield. The reduced low pressure steam production reduces the unit energy utilization, i.e., the combined cycle unit efficiency, as compared to a conventional fuel (no/minimal sulfide) combined cycle unit.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, the present invention provides a system and a method for utilizing cold and heat energy of a coal press room of a combined cycle unit with low calorific value, which can fully utilize cold and heat energy of the room and deepen energy cascade utilization.

The invention provides a system for utilizing cold and heat between coal press rooms of a low-heat-value combined cycle unit, which comprises a gas compressor, a gas turbine, a waste heat boiler, a steam turbine, a condenser, a fuel pipeline, a flue gas pipeline, a water supply pipeline and a steam pipeline, wherein the gas compressor is connected with the gas turbine; the gas compressor is communicated with the gas turbine through a fuel pipeline, the gas turbine is communicated with the waste heat boiler through a flue gas pipeline, the waste heat boiler is communicated with the steam turbine through a steam pipeline, and the steam turbine, the condenser and the waste heat boiler are communicated through a water supply pipeline in sequence; the cold side of the coal press intermediate heat exchanger is communicated with the hot side of the boiler water supply heat exchanger through the indirect cooling pipeline; the coal gas compressor comprises a coal press high-pressure section and a coal press low-pressure section, an indirect cooling fuel pipeline is connected between a fuel outlet of the coal press low-pressure section and a fuel inlet of the coal press high-pressure section, and the indirect cooling fuel pipeline is communicated with the hot side of the coal press intermediate heat exchanger; and a water feeding pipeline connected between the condenser and the waste heat boiler is communicated with the cold side of the boiler water feeding heat exchanger.

Furthermore, the intermediate cooling and heating system further comprises a surface cooler group, the surface cooler group is communicated with an air inlet of the gas turbine through an air pipeline, and an intermediate cooling pipeline connected with the outlet side of the intermediate heat exchanger of the coal press is also communicated with the surface cooler group.

Further, the inter-cold heat system further comprises an surface cooler group and an absorption type refrigerating system, the surface cooler group is communicated with an air inlet of the gas turbine through an air pipeline, the absorption type refrigerating system comprises an absorption type refrigerator, a freezing water pipe and a freezing water pump arranged on the freezing water pipe, the absorption type refrigerator comprises a refrigerator generator and a refrigerator evaporator which are connected, the inter-cold pipeline connected with the outlet side of the coal press intermediate heat exchanger is also communicated with the refrigerator generator, and the refrigerator evaporator is communicated with the surface cooler group through the freezing water pipe.

Furthermore, the system for utilizing the cold and heat between the coal presses of the low-heat-value combined cycle unit further comprises a cooling system, wherein the cooling system comprises a cooling water pipeline and a cold and heat cooler, an inter-cooling pipeline connected between the boiler water supply heat exchanger and the coal press intermediate heat exchanger is communicated with the hot side of the inter-cooling heat cooler, and the cold side of the inter-cooling heat cooler is communicated with the cooling water pipeline.

Furthermore, the cooling medium circulating in the cooling water pipeline is open water.

Further, the indirect cooling heat exchange medium is closed water.

The invention provides another cold and heat utilization system between coal press rooms of a low-calorific-value combined cycle unit, which comprises a gas compressor, a gas turbine, a waste heat boiler, a steam turbine, a condenser, a fuel pipeline, a water supply pipeline and a steam pipeline; the gas compressor is communicated with the gas turbine through a fuel pipeline, the gas turbine is communicated with the waste heat boiler through a flue gas pipeline, the waste heat boiler is communicated with the steam turbine through a steam pipeline, and the steam turbine, the condenser and the waste heat boiler are communicated through a water supply pipeline in sequence; the system also comprises a room cold and heat energy system, wherein the room cold and heat energy system comprises a coal press middle heat exchanger; the coal gas compressor comprises a coal press high-pressure section and a coal press low-pressure section, an indirect cooling fuel pipeline is connected between a fuel outlet of the coal press low-pressure section and a fuel inlet of the coal press high-pressure section, and the indirect cooling fuel pipeline is communicated with the hot side of the coal press intermediate heat exchanger; and a water feeding pipeline connected between the condenser and the waste heat boiler is communicated with the cold side of the intermediate heat exchanger of the coal press.

The invention also provides a method for utilizing the cold and heat quantity of the coal press room of the low-heat-value combined cycle unit, wherein when the gas turbine runs, the indirect cooling pump and the water supply heat exchanger are started, and the indirect cooling heat exchange medium enters the intermediate heat exchanger of the coal press and exchanges heat with the fuel passing through the indirect cooling fuel pipeline; after being heated, the indirect cooling heat exchange medium in the indirect cooling pipeline enters the boiler water supply heat exchanger as a heat source to heat the condensed water from the water supply pipeline, and the condensed water enters the waste heat boiler after being heated.

Furthermore, the inter-cooling heat system also comprises a surface cooler group, the surface cooler group is communicated with an air inlet of the gas turbine through an air pipeline, and an inter-cooling pipeline connected with the outlet side of the intermediate heat exchanger of the coal press is also communicated with the surface cooler group; when inlet air of the gas turbine needs to be heated, the surface cooler group is started, and high-temperature indirect cooling heat exchange media extracted from an outlet of a coal press intermediate heat exchanger by the surface cooler group serve as a heat source to heat the air flowing into the surface cooler group; the heated air flows into the gas turbine through an air duct.

Furthermore, the inter-cold heat system further comprises an absorption refrigeration system, the absorption refrigeration system comprises an absorption refrigerator, a freezing water pipe and a freezing water pump arranged on the freezing water pipe, the absorption refrigerator comprises a refrigerator generator and a refrigerator evaporator which are connected, an inter-cold pipeline connected with the outlet side of the intermediate heat exchanger of the coal press is also communicated with the refrigerator generator, and the refrigerator evaporator is communicated with the surface cooler group through the freezing water pipe; when the inlet air of the gas turbine needs to be cooled, the high-temperature indirect cooling heat exchange medium extracted from the outlet of the intermediate heat exchanger of the coal press by the surface cooler group is cut off; starting the absorption type refrigerating machine and the refrigerating water pump, wherein the absorption type refrigerating machine extracts a high-temperature indirect cooling heat exchange medium from an outlet of the intermediate heat exchanger of the coal press as a driven heat source, and after the absorption type refrigerating machine is driven, refrigerated water generated by an evaporator of the refrigerating machine enters the surface cooler group to cool air flowing into the surface cooler group; the cooled air flows into the gas turbine through the air duct.

As mentioned above, the system and the method for utilizing the cold and heat between the coal press rooms of the low-heat-value combined cycle unit have the following beneficial effects:

in the invention, the indirect cooling heat exchange medium in the indirect cooling heat quantity system is heated in the process of cooling high-temperature high-pressure coal gas in the intermediate heat exchanger of the coal press, flows through the boiler water supply heat exchanger through the indirect cooling pipeline, and heats boiler water supply flowing through the boiler water supply heat exchanger, thereby not only improving the water supply temperature of the boiler, but also fully utilizing the indirect cooling heat quantity; meanwhile, the exhaust gas temperature of the boiler is improved, the corrosion of a tail heat exchange surface is prevented, namely, the heat exchange area of a low-pressure part of the waste heat boiler does not need to be reduced, so that the unit can generate more steam, and the efficiency of the combined cycle unit is improved. And the inter-cold heat system can also comprise a surface cooler group which is used for heating the air temperature at the inlet of the gas turbine by using the inter-cold heat, and under the limited load, the load rate of the gas turbine can be improved as much as possible, so that the efficiency of the combined cycle unit is improved under the condition that the power of the combined cycle unit is not changed. Furthermore, the room cooling and heating system can also comprise an absorption refrigeration system, when the unit is in a high-temperature working condition, the room cooling and heating system drives the absorption refrigeration device therein, and the temperature of the air at the inlet of the gas turbine is reduced through the surface cooler unit, so that the output of the unit is improved.

Drawings

FIG. 1 is a schematic diagram of a first embodiment of a system for utilizing cold and heat in a coal press room of a combined cycle unit with a low heating value according to the present invention;

FIG. 2 is a schematic diagram of a second embodiment of the system for utilizing the cold and heat in the coal press room of the combined cycle unit with low calorific value according to the present invention.

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.

It should be understood that the structures, ratios, sizes, and the like shown in the drawings and described in the specification are only used for matching with the disclosure of the specification, so as to be understood and read by those skilled in the art, and are not used to limit the conditions under which the present invention can be implemented, so that the present invention has no technical significance, and any structural modification, ratio relationship change, or size adjustment should still fall within the scope of the present invention without affecting the efficacy and the achievable purpose of the present invention. In addition, the terms such as "upper", "lower", "left", "right" and "middle" used in the present specification are for clarity of description, and are not intended to limit the scope of the present invention, and changes or modifications of the relative relationship may be made without substantial technical changes.

Embodiment I of cold and heat utilization system between coal press of low-heat-value combined cycle unit

As shown in fig. 1, the first embodiment of the cooling and heating energy utilization system between the coal press rooms of the combined cycle unit with low heating value provided by the invention comprises a gas compressor 10, a gas turbine 20, a waste heat boiler 30, a steam turbine 40, a condenser 41, a fuel pipeline 21, a flue gas pipeline 22, a water supply pipeline 42 and a steam pipeline 43; the gas compressor 10 is communicated with the gas turbine 20 through a fuel pipeline 21, the gas turbine 20 is communicated with the waste heat boiler 30 through a flue gas pipeline 22, the waste heat boiler 30 is communicated with the steam turbine 40 through a steam pipeline 43, and the steam turbine 40, the condenser 41 and the waste heat boiler 30 are communicated through a water supply pipeline 42 in sequence; meanwhile, the cold and heat utilization system of the coal press room of the low-calorific-value combined cycle unit further comprises a room cold and heat system, the room cold and heat system comprises a room cold pipeline 51, a room cold heat exchange medium circulating in the room cold pipeline 51, a room cold pump 52 arranged on the room cold pipeline, a coal press middle heat exchanger 53 and a boiler feed water heat exchanger 54, and the hot side of the coal press middle heat exchanger 53 is communicated with the hot side of the boiler feed water heat exchanger 54 through the room cold pipeline 51; the coal gas compressor 10 comprises a coal press high-pressure section 11 and a coal press low-pressure section 12, an indirect cooling fuel pipeline 13 is connected between a fuel outlet of the coal press low-pressure section 12 and a fuel inlet of the coal press high-pressure section 11, and the indirect cooling fuel pipeline 13 is communicated with the hot side of a coal press intermediate heat exchanger 53; a feed water pipe 42 connected between the condenser 41 and the exhaust heat boiler 30 communicates with the cold side of the boiler feed water heat exchanger 54.

When the unit normally operates, the gas compressor 10 works, the low-pressure section 12 of the coal press pressurizes fuel with low calorific value, and the fuel enters the high-pressure section 11 of the coal press through an indirect cooling fuel pipeline 13. The temperature of the fuel passing through the indirect cooling fuel pipeline 13 is high, and the fuel passes through the intermediate heat exchanger 53 of the coal press to exchange heat with indirect cooling heat exchange medium, so that the high-temperature and high-pressure coal gas is cooled, and meanwhile, the temperature of the indirect cooling heat exchange medium is increased after passing through the intermediate heat exchanger 53 of the coal press. The gas compressor 10 supplies fuel to the gas turbine 20 through a fuel line 21, the gas turbine 20 supplies high-temperature flue gas to the heat recovery steam generator 30 through a flue gas line 22, the heat recovery steam generator 30 supplies steam to the steam turbine 40 through a steam line 43, the steam turbine 40 outputs electric power by applying work, and a cycle is formed by a condenser 41 and a water supply line 42. Further, at the intermediate heat exchanger 53 of the coal press, the intercooling heat transfer medium with the increased temperature enters the hot side of the boiler feed water heat exchanger 54 through the intercooling pipe 51, and exchanges heat with the condensed water (i.e., the boiler feed water) passing through the cold side of the boiler feed water heat exchanger 54, so that the temperature of the boiler feed water circulating into the waste heat boiler 30 is increased. This not only make full use of cold and heat between, simultaneously, the rising of the boiler feed water temperature that flows into exhaust-heat boiler 30 makes boiler exhaust gas temperature rise, effectively prevents the corruption of afterbody heat transfer surface, need not to reduce exhaust-heat boiler 30 low pressure part heat transfer area promptly for the unit can produce more steam, improves combined cycle unit output and thermal efficiency.

As shown in fig. 1, the inter-cooling heat system further includes a surface cooler group 60, the surface cooler group 60 is communicated with an air inlet of the gas turbine 20 through an air duct 61, and the inter-cooling duct 51 connected to an outlet side of the intermediate heat exchanger 53 of the coal press is also communicated with the surface cooler group 60. The outlet side of the surface cooler group 60 is also connected with the inlet side of the coal press intermediate heat exchanger 53 through an indirect cooling pipeline 51 to form a circulation.

When the combined cycle unit operates at partial load, the inlet guide vane of the gas turbine 20 is turned down, the through-flow capacity of the gas turbine is reduced, and the efficiency of the gas turbine 20 and the combined cycle unit is reduced. At this time, the intercooling heat transfer medium having an increased temperature and passing through the coal press intermediate heat exchanger 53 is introduced into the surface cooler group 60 through the intercooling duct 51, and heats the air introduced into the gas turbine 20. Under the limited load, the load rate of the combustion engine can be improved as much as possible, so that the efficiency of the combined cycle unit is improved under the condition that the power of the combined cycle unit is not changed.

As shown in fig. 1, the inter-cold heat system further includes an absorption refrigeration system, the absorption refrigeration system includes an absorption refrigerator 70, a chilled water pipe 74 and a chilled water pump 73 disposed on the chilled water pipe 74, the absorption refrigerator 70 includes a refrigerator generator 71 and a refrigerator evaporator 72 connected to each other, the inter-cold pipeline 51 connected to the outlet side of the coal press intermediate heat exchanger 53 is further communicated with the refrigerator generator 71, and the refrigerator evaporator 72 is communicated with the surface cooler group 60 through the chilled water pipe 74.

The output of the combined cycle unit is reduced along with the rise of the environmental temperature, and the output of the combined cycle unit can be improved by artificially reducing the inlet air temperature of the gas compressor of the gas turbine under the high-temperature working condition. At this time, the intermediate cooling heat transfer medium having an increased temperature is introduced into the generator of the absorption refrigerator 70 by blocking the intermediate cooling duct 51 in which the intermediate cooling heat transfer medium having an increased temperature enters the front surface cooler group 60 via the coal press intermediate heat exchanger 53, and the absorption refrigerator is driven as a heat source. At this time, the chilled water pump 73 is started, the chilled water in the chilled water pipe 74 passes through the refrigerator evaporator 72, the temperature is further reduced, and the air passing through the surface cooler unit 60 is cooled in the surface cooler unit 60, so that the output force of the unit under the high-temperature working condition is effectively improved. Meanwhile, in the present embodiment, the absorption refrigerator may employ a lithium bromide absorption refrigerator.

As shown in fig. 1, the system for utilizing cold and heat between coal presses of a combined cycle plant with a low calorific value further comprises a cooling system, wherein the cooling system comprises a cooling water pipeline 80 and a cold and heat cooler 55, an intermediate cooling pipeline 51 connected between a boiler feed water heat exchanger 54 and the inlet side of an intermediate heat exchanger 53 of the coal press, the intermediate cooling pipeline 51 connected between the outlet side of a surface cooler group 60 and the inlet side of the intermediate heat exchanger 53 of the coal press, the intermediate cooling pipeline 51 connected between the outlet side of a refrigerator generator 71 and the inlet side of the intermediate heat exchanger 53 of the coal press are both communicated with the hot side of the cold and heat cooler 55, and the cold side of the cold and heat cooler 55 is communicated with the cooling water pipeline 80. The indirect cooling heat exchange medium released by the boiler feed water heat exchanger 54 and the indirect cooling heat exchange medium released by the surface cooler unit 60 are fully released in the indirect cooling heat cooler 55, are further cooled and cooled, enter the cold side of the coal press intermediate heat exchanger 53 through the indirect cooling pipeline 51 to absorb heat, and cool high-temperature high-pressure coal gas in the indirect cooling fuel pipeline 13 to form circulation of the indirect cooling heat exchange medium in the indirect cooling pipeline, so that the indirect cooling heat exchange medium can be recycled, and the stability of an indirect cooling system is also improved. As shown in fig. 1, the cooling medium flowing through the cooling water pipe 80 is open water. The indirect cooling heat transfer medium flowing through the indirect cooling pipe 51 is closed water. An open water system and a closed water system are generally arranged in a common combined unit, and a cooling system can be directly applied to the open water system of the original combined unit. The indirect cooling system can be improved on the basis of the original closed water system, namely, a plurality of pipelines are added on the basis of the original closed water system to serve as indirect cooling pipelines 51, and heat exchangers are added to serve as a coal press intermediate heat exchanger 53 and a boiler feed water heat exchanger 54; meanwhile, the inter-cold heat cooler 55 can directly adopt a closed water-open water heat exchanger of the original combined unit, which greatly reduces the workload of the inter-cold heat system and the cooling system during engineering.

Second embodiment of the system for utilizing cold and heat between coal presses of low-heat value combined cycle unit

As shown in fig. 2, the second embodiment of the cooling and heating energy utilization system between the coal press rooms of the combined cycle unit with low heating value provided by the invention comprises a gas compressor 10, a gas turbine 20, a waste heat boiler 30, a steam turbine 40, a condenser 41, a fuel pipeline 21, a flue gas pipeline 22, a water supply pipeline 42 and a steam pipeline 43; the gas compressor 10, the gas compressor 10 and the gas turbine 20 are communicated through a fuel pipeline 21, the gas turbine 20 and the waste heat boiler 30 are communicated through a flue gas pipeline 22, the waste heat boiler 30 and the steam turbine 40 are communicated through a steam pipeline 43, and the steam turbine 40, the condenser 41 and the waste heat boiler 30 are communicated through a water supply pipeline 42 in sequence; the system also comprises an inter-cold heat system, wherein the inter-cold heat system comprises a coal press intermediate heat exchanger 53; the coal gas compressor 10 comprises a coal press high-pressure section 11 and a coal press low-pressure section 12, an indirect cooling fuel pipeline 13 is connected between a fuel outlet of the coal press low-pressure section 12 and a fuel inlet of the coal press high-pressure section 11, and the indirect cooling fuel pipeline 13 is communicated with the hot side of a coal press intermediate heat exchanger 53; a water feed line 42 connected between the condenser 41 and the waste heat boiler 30 communicates with the cold side of the coal press intermediate heat exchanger 53.

The second embodiment is different from the first embodiment in that the condenser 41 and the water supply pipe 42 of the waste heat boiler 30 are directly communicated with the cold side of the coal press intermediate heat exchanger 53, and the coal press intermediate heat exchanger 53 directly heats the boiler feed water. The water supply temperature of the boiler can be improved, and the cold and heat of the room are fully utilized; the exhaust gas temperature of the boiler is improved, the corrosion of the heat exchange surface at the tail part is prevented, namely, the heat exchange area of the low-pressure part of the waste heat boiler 30 is not required to be reduced, so that the unit can generate more steam, and the output and the heat efficiency of the combined cycle unit are improved.

The embodiment of the invention also provides a method for utilizing the cold and heat between the coal presses of the low-heat-value combined cycle unit, which uses the first embodiment of the system for utilizing the cold and heat between the coal presses of the low-heat-value combined cycle unit shown in the figure 1. The method for utilizing the cold and heat between the coal presses of the low-heat-value combined cycle unit comprises the following steps:

when the gas turbine 20 operates, the indirect cooling pump 52 and the boiler water supply heat exchanger 54 are started, and indirect cooling heat exchange media enter the coal press intermediate heat exchanger 53 and exchange heat with fuel passing through the indirect cooling fuel pipeline 13; the heated intermediate cooling heat transfer medium in the intermediate cooling pipe 51 enters the boiler feed water heat exchanger 54 as a heat source to heat the condensed water from the feed water pipe 42, and the condensed water is heated and then enters the waste heat boiler 30. In practical engineering, when the combined cycle unit with low calorific value and the gas compressor 10 are operated, and the heat and cold utilization system between the coal presses of the combined cycle unit with low calorific value is in a working condition of heating the feed water of the waste heat boiler 30, the intermediate heat exchanger 53 of the coal press and the feed water heat exchanger 54 of the boiler are only required to be opened, and the intermediate cooling pump 52 is started after the conduction of the intermediate cooling pipeline 51 communicating the intermediate heat exchanger 53 of the coal press and the feed water heat exchanger 54 of the boiler is confirmed. In this embodiment, the intercooling heat transfer medium as the heat source is released into the boiler feedwater heat exchanger 54, enters the intercooling heat exchanger heat cooler 55, is further cooled, and then returns to the inlet of the medium compressor intermediate heat exchanger 53, thereby achieving the recycling of the intercooling heat transfer medium.

When the inlet air of the gas turbine 20 needs to be heated, the surface cooler group 60 is started, and the high-temperature indirect cooling heat exchange medium extracted from the outlet of the intermediate heat exchanger 53 of the coal press by the surface cooler group 60 is used as a heat source to heat the air flowing into the surface cooler group 60; the heated air flows into the gas turbine 20 through the air duct 61. In this embodiment, the high-temperature indirect heat exchange medium releases heat in the surface cooler unit 60, enters the indirect heat cooler 55 for further cooling, and then returns to the inlet of the indirect heat exchanger 53 of the coal press. The cold and heat utilization system of the coal press room of the low-heat value combined cycle unit is under the working condition of heating the air at the inlet of the gas turbine 20, generally, the gas yield of the unit is large in fluctuation, and the load of the gas turbine 20 is lower than 90% of the rated load. In the implementation process, only the surface cooler group 60 and the intermediate heat exchanger 53 of the coal press need to be conducted, the surface cooler group 60 and the gas turbine 20 need to be conducted, and the surface cooler group 60 is started. At this time, a part of the intercooling heat transfer medium heated by the coal press intermediate heat exchanger 53 flows through the boiler feed water heat exchanger 54 to heat the boiler feed water, and the remaining part flows into the surface cooler group 60 to heat the air before flowing into the gas turbine 20.

When the inlet air of the gas turbine 20 needs to be cooled, the high-temperature indirect cooling heat exchange medium extracted from the outlet of the coal press intermediate heat exchanger 53 by the surface cooler group 60 is stopped; starting the absorption refrigerator 70 and the chilled water pump 73, extracting a high-temperature intercooling heat exchange medium from the outlet of the coal press intermediate heat exchanger 53 by the absorption refrigerator 70 to serve as a driven heat source, and after the absorption refrigerator 70 is driven, introducing chilled water generated by a refrigerator evaporator 72 into the surface cooler group 60 to cool air flowing in the surface cooler group 60; the cooled air flows into the gas turbine 20 through the air duct 61.

The cold and heat utilization system between the coal presses of the low-heat value combined cycle unit is under the working condition of reducing the air temperature at the inlet of the gas turbine 20, generally when the gas yield is large and the electric load demand exceeds the corresponding full load power within 10% of the ambient temperature. In the actual operation process, the surface cooler group 60 and the intercooling pipeline 51 of the coal press intermediate heat exchanger 53 are only required to be cut off, the refrigerator evaporator 72, the freezing water pipe 74 and the surface cooler group 60 are conducted, the coal press intermediate heat exchanger 53 and the refrigerator generator 71 are conducted, the surface cooler is confirmed to be opened, and the absorption refrigerator 70 and the freezing and cooling water pump are started. At this time, a part of the indirect cooling heat transfer medium heated by the coal press intermediate heat exchanger 53 flows through the boiler feed water heat exchanger 54 to heat the boiler feed water, and the remaining part flows into the surface cooler group 60 to flow into the cooler generator 71 to drive the absorption chiller to operate.

Of course, in the method for utilizing the cold and heat between the coal presses of the combined cycle plant with a low calorific value, the hot side of the boiler feedwater heat exchanger 54 may be cut off, and only the surface cooler group 60 and the coal press intermediate heat exchanger 53 may be conducted, or the intermediate cooling pipe 51 of the surface cooler group 60 and the coal press intermediate heat exchanger 53 may be cut off at the same time, and only the refrigerator evaporator 72, the chilled water pipe 74, and the surface cooler group 60 may be conducted. And need not be described in detail herein. The method for utilizing the cold and heat between the coal press chambers of the low-heat-value combined cycle unit is simple and flexible to operate and is suitable for the operation of the low-heat-value combined cycle unit under various working conditions.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.