Peaking Heating and Energy Saving System for Gas-Steam Combined Cycle Heating Unit

Abstract

The present invention provides a peak shaving and heat supply and energy-saving system for a gas-steam combined cycle heat supply unit, which realizes peak shaving shutdown of the unit for heat supply, returns the heat storage steam to the unit for power generation, and utilizes waste heat. It is characterized in that it includes a saturated steam heat storage device, a superheated steam heat storage device, and a natural gas preheating system. The natural gas preheating system includes a second heat exchanger, a third heat exchanger, a thermoelectric hybrid heater, and a pressure regulating branch. The inlet of the heat medium channel of the second heat exchanger is connected to the outlet of the medium-pressure economizer, and the outlet of the heat medium channel is connected to the inlet of the heat medium channel of the third heat exchanger. The inlet of the fluid channel of the third heat exchanger is connected to the natural gas source, and the outlet of the fluid channel is connected to the inlet of the fluid channel of the second heat exchanger through the pressure regulating branch. The outlet of the fluid channel of the second heat exchanger is connected to the gas turbine. The heat medium channel of the thermoelectric hybrid heater is connected to the main heat supply pipe, and the outlet of its fluid channel converges to the heat medium pipe between the second heat exchanger and the third heat exchanger.

Description

Technical Field

[0001] The present invention relates to an energy recovery technology in the power field, and more particularly to a peak shaving heating and energy saving system for a gas-steam combined cycle heating unit. Background Art

[0002] Currently, gas-steam combined cycle heating units are heat-fixed and power-continuous operation units, usually equipped with a start-up boiler to meet the steam required for unit start-up, and the start-up boiler can be used for emergency heating in case of unit accidents. In the face of a high proportion of renewable energy, when the combined cycle heating unit needs to perform peak shaving and shut down, only the accident heating during the shutdown of the combined cycle unit and the start-up boiler can be used to maintain heating. The accident heating can only maintain the heat supply for 1 hour, and the continuous operation of the start-up boiler lacks stability, which poses a risk of heat supply interruption in the heating system. At the same time, during the shutdown process of the combined cycle unit, each steam bypass is opened to the condenser, and the waste heat boiler discharges sewage and water to the regular drain expansion vessel and then discharges it to the trench after cooling, resulting in heat waste. The auxiliary steam used by the lithium bromide refrigerator is not recovered and directly discharged to the trench, causing heat and working medium waste. Summary of the Invention

[0003] The present invention provides a peak shaving heating and energy saving system for a gas-steam combined cycle heating unit, which is used for heating during peak shaving shutdown of the unit, returning the heat storage steam to the unit for power generation, and utilizing waste heat. The specific implementation means are as follows:

[0004] The peak shaving heating and energy saving system for a gas-steam combined cycle heating unit of the present invention includes:

[0005] A saturated steam heat storage device, whose input port is connected to the low-pressure steam bypass of the unit, and whose output port is connected to a first heat exchanger, which is used to provide a heat source for water.

[0006] A superheated steam heat storage device, whose input port is connected to the high- and medium-pressure steam bypass of the unit, and whose output port is connected to the main heating pipe of the unit.

[0007] A natural gas preheating system, including a second heat exchanger, a third heat exchanger, a thermoelectric hybrid heater, and a pressure regulating branch; the inlet of the heat medium channel of the second heat exchanger is connected to the outlet of the medium-pressure economizer, and the outlet of the heat medium channel is connected to the inlet of the heat medium channel of the third heat exchanger; the inlet of the fluid channel of the third heat exchanger is connected to the natural gas source, and its fluid channel outlet is connected to the inlet of the fluid channel of the second heat exchanger through the pressure regulating branch, and the outlet of the fluid channel of the second heat exchanger is connected to the gas turbine; the heat medium channel of the thermoelectric hybrid heater is connected to the main heating pipe, and its fluid channel outlet converges to the heat medium pipeline between the second heat exchanger and the third heat exchanger.

[0008] In one or more embodiments of the present invention, a first filter and a second filter are respectively provided before and after the pressure regulating branch.

[0009] In one or more embodiments of the present invention, a water pump is provided at the fluid channel outlet of the thermoelectric hybrid heater.

[0010] In one or more embodiments of the present invention, the superheated steam heat storage device is further connected to a solar superheated steam generator.

[0011] In one or more embodiments of the present invention, the output port of the saturated steam heat storage device is connected to a lithium bromide refrigerator to provide a heat source for it.

[0012] In one or more embodiments of the present invention, the lithium bromide refrigerator is also communicated with the main heating pipe to obtain a heat source.

[0013] In one or more embodiments of the present invention, the lithium bromide refrigerator is provided with a cold source pipeline communicating with a compressor to provide a cold source for it, the first heat exchanger has a heat source pipeline communicating with the compressor to provide a heat source for it, and electronic valve groups controlled by a compressor intake temperature control device are respectively provided on the cold source pipeline and the heat source pipeline.

[0014] In one or more embodiments of the present invention, the output port of the superheated steam heat storage device is connected to the inlet of the cold section of the boiler reheater.

[0015] In one or more embodiments of the present invention, a boiler drain collector and a fourth heat exchanger are further provided. The boiler drain collector outputs drain water to the fourth heat exchanger to provide a heat source for the water body, and the water body pipeline between the fourth heat exchanger and the first heat exchanger is connected, so that the fourth heat exchanger and the first heat exchanger realize secondary heating of the water body.

[0016] The beneficial effects of the present invention are:

[0017] 1) The use of the steam of the superheated steam heat storage device can ensure the stability of the heating system after the combined cycle unit is shut down and improve the power generation capacity of the unit, effectively utilize the steam wasted during the start-up and shutdown processes of the unit and solar energy, and improve the economy of the unit.

[0018] 2) It can ensure that the temperature of the natural gas before the filter of the natural gas pressure regulating station is met, effectively utilize the heat of the medium-pressure economizer outlet water of the pre-module heater, and the water bath furnace and the pre-module start-up electric heater of the natural gas pressure regulating station can be cancelled.

[0019] 3) Using the steam of the saturated steam heat storage device as the heat source of the lithium bromide refrigerator can effectively utilize the steam wasted during the start-up and shutdown processes of the unit and improve the economy of the unit.

[0020] 4) Using the blowdown and drainage of the waste heat boiler for water heating can effectively utilize waste heat and improve the economy of the unit; recovering the blowdown and drainage of the waste heat boiler and the heat source working medium for the lithium bromide refrigerator to the chemical water treatment can reduce the waste of the working medium. Brief Description of the Drawings

[0021] Figure 1 This is a schematic diagram of the system framework of the present invention. Detailed Embodiment

[0022] The solution of the present application will be further described below in conjunction with the drawings:

[0023] Refer to the attached Figure 1 , the peak shaving heat supply and energy-saving system of the gas-steam combined cycle heat supply unit includes: a saturated steam heat storage device 1, a superheated steam heat storage device 2, a natural gas preheating system 3, a main heat supply pipe 4, a condenser 5, a lithium bromide refrigerator 6, a boiler drain collector 7, and a solar superheated steam generator 8; specifically, the input port of the saturated steam heat storage device 1 is connected to the low-pressure steam bypass of the unit, and its output port is respectively connected to a first heat exchanger 11 and a lithium bromide refrigerator 6; the boiler drain collector 7 is used to connect and collect the continuous blowdown and regular blowdown drain water of the boiler, and its output port is connected to a fourth heat exchanger 71; the saturated steam heat storage device 1 collects the low-pressure bypass steam that meets the steam parameters during the start-up and shutdown processes of the combined cycle unit, and supplies heat to the lithium bromide refrigerator 6 on one hand and supplies heat to the water body through the first heat exchanger 11 on the other hand; considering the full utilization of energy and that single heating may not meet the heat exchange requirements when the water body flow rate is large, it is designed that the first heat exchanger 11 and the fourth heat exchanger 71 jointly supply heat to the water body and realize secondary heating from the fourth heat exchanger 71 to the first heat exchanger 11, making full use of the hot steam and drain water of the unit. The heated water body can be used by the unit through pipelines or provide domestic hot water for the park; the steam output by the saturated steam heat storage device 1 flows to the condenser 5 after passing through the first heat exchanger 11, obtains condensate water and then is recycled; the drain water generated by the blowdown and water discharge of the waste heat boiler is sent to the chemical water recovery treatment and then reused after passing through the fourth heat exchanger 71;

[0024] The lithium bromide refrigerator 6 obtains heat media from the saturated steam heat storage device 1 and the main heat supply pipe 4 respectively. The heat source of the heat medium is sent to the chemical water recovery treatment and then reused after being applied by the lithium bromide refrigerator 6; the lithium bromide refrigerator 6 is provided with a cold source pipeline 61 communicating with the compressor to provide a cold source for it, and the first heat exchanger 11 has a heat source pipeline 12 communicating with the compressor to provide a heat source for it. It is equivalent to using the water body heated by the first heat exchanger 11 and the fourth heat exchanger 71 as the heat medium of the compressor. Electronic valve groups controlled by a compressor intake temperature control device 9 are respectively provided on the cold source pipeline 61 and the heat source pipeline 12. The main heat supply pipe 4 has an interface for connecting a start-up boiler, an interface for auxiliary steam output, and a heat supply network interface for outputting heat medium.

[0025] The input port of the superheated steam energy storage device 2 is connected to the high and medium pressure steam bypass of the unit, its output port is connected to the main heating pipe 4 and the inlet of the cold section of the boiler reheater, and the superheated steam energy storage device 2 is connected to the solar superheated steam generator 8; the superheated steam energy storage device 2 collects the high and medium pressure bypass steam that meets the steam parameters during the start-up and shutdown processes of the combined cycle unit and the superheated steam of the solar superheated steam generator 8, and outputs the heat medium to the main heating pipe 4 in one way and to the inlet of the cold section of the boiler reheater in the other way, and provides steam to the unit to increase power generation when the steam volume is sufficient or the power grid needs the generator to increase output;

[0026] The natural gas preheating system 3 includes a second heat exchanger 31, a third heat exchanger 32, a thermoelectric hybrid heater 33 and a pressure regulating branch 34; the inlet 31a of the heat medium channel of the second heat exchanger 31 is connected to the outlet of the medium pressure economizer, its outlet 31b of the heat medium channel is connected to the inlet 32a of the heat medium channel of the third heat exchanger 32, and the outlet 32b of the heat medium channel of the third heat exchanger 32 is connected to the condenser 5; the inlet 32c of the fluid channel of the third heat exchanger 32 is connected to the natural gas source, its outlet 32d of the fluid channel is connected to the inlet 31c of the fluid channel of the second heat exchanger 31 through the pressure regulating branch 34, and the outlet 31d of the fluid channel of the second heat exchanger 31 is connected to the gas turbine; a first filter 35 and a second filter 36 are respectively arranged before and after the pressure regulating branch 34; the inlet 33a of the heat medium channel of the thermoelectric hybrid heater 33 is connected to the main heating pipe 4, its inlet 33c of the fluid channel is connected to obtain condensate water, and its outlet 33d of the fluid channel converges to the heat medium pipeline between the second heat exchanger 31 and the third heat exchanger 32.

[0027] When the unit is not operating or in the startup stage, there is no heat medium supply at the outlet of the medium pressure economizer. At this time, the condensate water is heated by the thermoelectric hybrid heater 33, and then the third heat exchanger 31 is used to preheat the natural gas, so that the temperature of the natural gas meets the requirements before entering the first filter 35. If the heat supply of the main heating pipe 4 is insufficient at this time, the condensate water can also be heated by the electric heating function of the thermoelectric hybrid heater 33 itself; after the unit operates stably, the outlet of the medium pressure economizer can directly supply heat medium to the second heat exchanger 31 and the third heat exchanger 32, and at this time the thermoelectric hybrid heater 33 can be turned off; this embodiment effectively uses two-stage cascade preheat exchangers (i.e., the second heat exchanger 31 and the third heat exchanger 32) to preheat the natural gas, meets the temperature requirements of the natural gas, cancels the water bath furnace of the natural gas pressure regulating station and the pre-module start-up electric heater in the traditional scheme, and is more energy-saving and emission-reducing.

[0028] A number of electronic valve groups are respectively arranged on the pipelines between the devices of the system. These electronic valve groups are controlled by the upper controller and are used to control the opening and closing or / and the flow direction of the pipelines, including combinations of solenoid valves, stop valves, lift check valves, etc., which facilitate the system controller to enable / disable the pipelines as required or cut off the pipelines in a timely manner when an alarm occurs. For example, by controlling the electronic valve group between the lithium bromide chiller 6, the saturated steam heat storage device 1, and the main heat supply pipe 4, the heat supply source can be selected according to the actual situation; by using the electronic valve group between the superheated steam heat storage device 2, the main heat supply pipe 4, and the inlet of the cold section of the boiler reheater, heat supply to the cold section of the boiler reheater, or heat supply to the main heat supply pipe 4, or heat supply to both can be selected; through the electronic valve group between the solar superheated steam generator 8 and the superheated steam heat storage device 2, the heat supply from the solar superheated steam generator 8 can be selected to be enabled and connected; by using the electronic valve group at the fluid channel outlet 33d of the thermoelectric hybrid heater 33, the heat medium pipeline between the second heat exchanger 31 and the third heat exchanger 32 can be connected or disconnected; by using the electronic valve groups at the heat medium channel inlet 31a and the heat medium channel outlet 31b of the second heat exchanger 31, the heat supply from the outlet of the medium-pressure economizer can be connected or disconnected; and so on. The opening and closing or / and the flow direction of each electronic valve group are controlled according to the actual operation requirements.

[0029] The above preferred embodiments should be regarded as illustrative examples of the implementation modes of the application solutions of the present application. All technical deductions, substitutions, improvements, etc. that are identical, similar to, or based on the application solutions of the present application should be regarded as within the protection scope of this patent.

Claims

1. A peak shaving heating and energy-saving system for a gas-steam combined cycle heating unit, characterized in that Including: A saturated steam thermal energy storage device (1), whose input port is connected to the low-pressure steam bypass of the unit, and whose output port is connected to a first heat exchanger (11) for providing a heat source for the water body; A superheated steam thermal energy storage device (2), whose input port is connected to the high and medium pressure steam bypass of the unit, and whose output port is connected to the main heat supply pipe (4) of the unit; A natural gas preheating system (3), including a second heat exchanger (31), a third heat exchanger (32), a thermoelectric hybrid heater (33) and a pressure regulating branch (34); the inlet of the heat medium channel of the second heat exchanger (31) is connected to the outlet of the medium-pressure economizer, and its outlet of the heat medium channel is connected to the inlet of the heat medium channel of the third heat exchanger (32); the inlet of the fluid channel of the third heat exchanger (32) is connected to the natural gas source, and its outlet of the fluid channel is connected to the inlet of the fluid channel of the second heat exchanger (31) through the pressure regulating branch (34), and the outlet of the fluid channel of the second heat exchanger (31) is connected to the gas turbine; the heat medium channel of the thermoelectric hybrid heater (33) is connected to the main heat supply pipe (4), and its outlet of the fluid channel converges to the heat medium pipeline between the second heat exchanger (31) and the third heat exchanger (32).

2. The peak shaving and heat supply and energy saving system for a gas-steam combined cycle heat supply unit according to claim 1, wherein, A first filter (35) and a second filter (36) are respectively arranged before and after the pressure regulating branch (34).

3. The peak shaving and heat supply and energy saving system for a gas-steam combined cycle heat supply unit according to claim 1, characterized in that, A water pump (37) is arranged at the outlet of the fluid channel of the thermoelectric hybrid heater (33).

4. The peak shaving and heat supply and energy saving system for a gas-steam combined cycle heat supply unit according to claim 1, characterized in that, The superheated steam thermal energy storage device (2) is also connected with a solar superheated steam generator (8).

5. The peak shaving and heat supply and energy saving system for a gas-steam combined cycle heat supply unit according to claim 1, wherein The output port of the saturated steam thermal energy storage device (1) is connected to a lithium bromide refrigerator (6) to provide a heat source for it.

6. The peak shaving and heat supply and energy saving system for a gas-steam combined cycle heat supply unit according to claim 5, characterized in that, The lithium bromide refrigerator (6) also communicates with the main heat supply pipe (4) to obtain a heat source.

7. The peak shaving heat supply and energy saving system for a gas-steam combined cycle heat supply unit according to claim 5, characterized in that The lithium bromide refrigerator (6) is provided with a cold source pipeline (61) communicating with the compressor to provide a cold source for it, the first heat exchanger (11) has a heat source pipeline (12) communicating with the compressor to provide a heat source for it, and electronic valve groups controlled by the compressor inlet temperature control device are respectively arranged on the cold source pipeline (61) and the heat source pipeline (12).

8. The peak shaving and heat supply and energy saving system for a gas-steam combined cycle heat supply unit according to claim 1, wherein The output port of the superheated steam thermal energy storage device (2) is connected to the inlet of the cold section of the boiler reheater.

9. The peak shaving heat supply and energy saving system for a gas-steam combined cycle heat supply unit according to any one of claims 1-8, characterized in that A boiler drain collector (7) and a fourth heat exchanger (71) are also provided. The boiler drain collector (7) outputs drain water to the fourth heat exchanger (71) to provide a heat source for the water body. The water body pipeline between the fourth heat exchanger (71) and the first heat exchanger (11) is connected, so that the fourth heat exchanger (71) and the first heat exchanger (11) realize secondary heating of the water body.

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