A method and device for deep utilization of flue gas waste heat of a gas turbine combined heat and power unit

Abstract

The present application relates to a kind of gas turbine cogeneration unit flue gas waste heat deep utilization method and system, utilize gas turbine cogeneration unit flue gas waste heat and heat network steam to carry out heating and refrigeration, the flue gas discharged by gas turbine cogeneration unit waste heat boiler is sent into direct contact heat exchanger;Direct contact heat exchanger sprays intermediate medium absorption flue gas waste heat, and according to the outlet temperature of intermediate medium is adjusted according to refrigeration or heating operating condition temperature set value;After absorbing flue gas waste heat, intermediate medium enters the absorption heat pump unit of waste heat utilization module;When refrigeration, intermediate medium and heat network heating steam are further warmed in steam-water mixer, and then enter hot water type absorption lithium bromide unit to realize waste heat refrigeration;When heating, intermediate medium and heat network heating steam enter steam type absorption lithium bromide unit to realize waste heat heating.The present application significantly improves the thermal efficiency of unit, and can provide cold, hot air conditioning load for user, expands the applicable scope of flue gas waste heat deep utilization system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of flue gas waste heat utilization of combined heat and power unit, in particular to a flue gas waste heat deep utilization method and device of gas turbine combined heat and power unit. BACKGROUND

[0002] The gas turbine combined heat and power unit has advantages of high efficiency and cleanliness, and its proportion in the energy structure in China is increasing. The main products of flue gas of the gas turbine fueled by natural gas include nitrogen, excess oxygen, water vapor and carbon dioxide, and a small amount of NO x , and almost no sulfur. The temperature of flue gas after the waste heat boiler is 80-110℃, and the heat of this part is directly discharged into the atmosphere without being utilized, which reduces the thermal efficiency of the combined cycle unit.

[0003] The heat exchanger for flue gas waste heat recovery generally has tube-shell type, heat pipe type and plate type, etc., which are all indirect contact type heat exchangers, and the temperature of recovered flue gas is still relatively high, and the heat exchange efficiency is low; in addition, there is a direct contact type heat exchanger, which can reduce the temperature of flue gas to below the dew point by spraying heat exchange, and can recover the water vapor in the flue gas while recovering the flue gas waste heat, and can also wash the flue gas, so that the flue gas is cleaner, and the application in the flue gas waste heat recovery of gas turbine unit is also more and more widely.

[0004] At present, the utilization of flue gas waste heat for refrigeration or heating is mainly realized by absorption heat pump unit, which is a mature equipment, and the available energy includes waste heat flue gas, hot water, steam or natural gas combustion heat, etc. In the heating system in northern China, the flue gas waste heat and high temperature heat source (steam) of the gas turbine combined heat and power unit are often used by absorption heat pump to heat the heating network return water, and this method uses a contact type superheater to realize the deep utilization of flue gas waste heat, but this method can only realize waste heat heating due to the low temperature of the intermediate medium water, and cannot be used in cases with cold load demand. SUMMARY

[0005] The purpose of the present application is to overcome the defects of the prior art and provide a flue gas waste heat deep utilization method for gas turbine combined heat and power unit, which can realize cold and heat supply and achieve efficient and step-by-step utilization of energy.

[0006] The purpose of the present application can be realized by the following technical solutions:

[0007] As a first aspect of the present application, a flue gas waste heat deep utilization method for gas turbine combined heat and power unit is provided, which utilizes flue gas waste heat and heating network steam of the gas turbine combined heat and power unit for heating and refrigeration, and the steps include:

[0008] The flue gas discharged from the waste heat boiler of the gas turbine combined heat and power unit is sent into the direct contact heat exchanger;

[0009] The intermediate medium sprayed by the direct contact heat exchanger absorbs the waste heat of the flue gas, and the outlet temperature of the intermediate medium in the direct contact heat exchanger is adjusted according to the temperature setting value of the refrigeration or heating working condition;

[0010] The intermediate medium after absorbing the waste heat is used for waste heat utilization, and refrigeration or heating is performed through the absorption heat pump unit;

[0011] When the waste heat utilization is used for refrigeration, the intermediate medium after absorbing the waste heat is mixed with the heat network steam to increase the temperature, and then enters the hot water type absorption lithium bromide unit to perform waste heat refrigeration;

[0012] When the waste heat utilization is used for heating, the intermediate medium after absorbing the waste heat is input into the steam type absorption lithium bromide unit with the heat network heating steam to perform waste heat heating.

[0013] Further, the specific steps of the method for refrigeration include:

[0014] The intermediate medium after absorbing the waste heat is mixed with the heat network steam and then enters the first generator of the hot water type lithium bromide unit, and returns to the direct contact flue gas heat exchanger after completing heat transfer;

[0015] The cooling water from the cooling tower passes through the first absorber and the first condenser of the hot water type lithium bromide unit in sequence, and then returns to the cooling tower after increasing the temperature;

[0016] The user side cold water return water enters the evaporator of the hot water type lithium bromide unit, and then is supplied to the user after decreasing the temperature by heat release;

[0017] Further, the specific steps of the method for heating include:

[0018] The intermediate medium after absorbing the waste heat enters the second evaporator of the steam type lithium bromide unit to transfer heat and decrease the temperature; the heat network steam enters the second generator of the steam type lithium bromide unit to transfer heat, decrease the temperature and form condensed water, and the condensed water and the intermediate medium are combined and then returned to the direct contact flue gas heat exchanger;

[0019] The user side hot water return water enters the second absorber and the second condenser of the steam type lithium bromide unit in sequence, and then is supplied to the user after increasing the temperature by heat absorption;

[0020] Further, the adjustment of the outlet temperature of the intermediate medium in the direct contact heat exchanger according to the temperature setting value of the refrigeration or heating working condition specifically includes:

[0021] In cooling, according to the refrigeration working condition temperature setting value, the flue gas and the intermediate medium flow entering the direct contact flue gas heat exchanger are adjusted, so that the outlet flue gas temperature of the direct contact flue gas heat exchanger is slightly lower than the flue gas dew point temperature, to meet the intermediate medium circulating temperature setting value under the refrigeration working condition;

[0022] In heating, according to the heating working condition temperature setting value, the flue gas and the intermediate medium flow entering the direct contact flue gas heat exchanger are adjusted, so that the outlet flue gas temperature is far lower than the dew point temperature, to meet the intermediate medium circulating temperature setting value under the heating working condition.

[0023] As a second aspect of the present application, a flue gas waste heat deep utilization system of a gas turbine combined heat and power unit is provided, comprising a gas turbine combined heat and power unit and a steam heat network, and the system further comprises:

[0024] A flue gas waste heat recovery module, comprising a direct contact heat exchanger for absorbing flue gas waste heat by an intermediate medium;

[0025] An intermediate medium temperature adjusting module for adjusting the temperature of the intermediate medium output by the waste heat utilization module, to adapt to different requirements of the intermediate medium temperature in cooling and heating;

[0026] A waste heat utilization module for cooling or heating by the intermediate medium after absorbing flue gas waste heat, comprising a hot water type lithium bromide unit for cooling and a steam type lithium bromide unit for heating;

[0027] A system control module for realizing automatic control of the intermediate medium temperature and control of the start-stop and operation of the whole system.

[0028] Further, the waste heat utilization module comprises:

[0029] A cooling sub-module, comprising a steam-water mixer and a hot water type lithium bromide unit, the input of the steam-water mixer being the intermediate medium output by the flue gas waste heat recovery module and the heat network steam, the steam-water mixer being connected to the first generator of the hot water type lithium bromide unit after mixing the two, and then returning to the direct contact heat exchanger; the cooling water passing through the first absorber and the first condenser of the hot water type lithium bromide unit in sequence; the user side cooling water return passing through the first evaporator of the hot water type lithium bromide unit, and returning to the user after heat release and temperature drop;

[0030] A heating sub-module, comprising a steam type lithium bromide unit, the intermediate medium output by the flue gas waste heat recovery module entering the second evaporator of the steam type lithium bromide unit; the heat network steam entering the second generator of the steam type lithium bromide unit to transfer heat and form condensed water after temperature drop, the condensed water and the intermediate medium coming out of the second evaporator being combined and then returning to the direct contact heat exchanger; the user side hot water return entering the second absorber and the second condenser of the steam type lithium bromide unit, and returning to the user after absorbing heat and temperature rise.

[0031] Further, the intermediate medium temperature adjusting module comprises:

[0032] A flue gas adjusting baffle is arranged between the waste heat boiler of the combined cycle unit and the flue gas waste heat recovery module, and is used for adjusting the flue gas flow entering the direct contact heat exchanger.

[0033] An intermediate medium circulating water adjusting valve is arranged at the intermediate medium inlet of the flue gas waste heat recovery module, and is used for adjusting the intermediate medium flow entering the direct contact heat exchanger.

[0034] Further, the system control module receives signals of the flue gas adjusting baffle, the intermediate medium circulating water adjusting valve and the intermediate medium outlet temperature of the flue gas waste heat recovery module, and controls the intermediate medium outlet temperature of the direct contact heat exchanger to meet the intermediate medium temperature setting value requirement under the refrigeration and heating working conditions.

[0035] Further, the system is provided with a dosing device at the intermediate medium outlet of the contact heat exchanger to adjust the pH value of the intermediate medium.

[0036] Further, the system is provided with a drainage valve at the intermediate medium inlet of the contact heat exchanger to drain the condensed water recovered from the flue gas to keep the water amount in the system balanced.

[0037] Compared with the prior art, the present application has the following beneficial effects:

[0038] 1) The flue gas waste heat utilization method of the combined cycle unit proposed in the present application can reduce the temperature of the utilized flue gas to below the dew point temperature, and can realize deep utilization of the flue gas waste heat and has a high waste heat utilization efficiency.

[0039] 2) The present application adjusts the outlet temperature of the intermediate medium circulating water of the direct contact flue gas heat exchanger through the proportion of the flue gas adjusting baffle, the intermediate medium circulating water adjusting valve and the circulating water flow, to adapt to the temperature requirement of the heat source water of the lithium bromide unit under the refrigeration and heating working conditions.

[0040] 3) The present application mixes a small amount of heat network steam with the intermediate medium cooling water at the outlet of the direct contact flue gas heat exchanger to exchange heat, which on the one hand improves the heat exchange efficiency of the steam and the hot water, and on the other hand improves the hot water temperature entering the lithium bromide unit to meet the refrigeration requirement of the lithium bromide unit, and realizes flue gas waste heat refrigeration while improving the refrigeration efficiency of the lithium bromide unit.

[0041] 4) The flue gas waste heat utilization system established by the flue gas adjusting baffle, the air supply fan and the direct contact flue gas heat exchanger proposed in the present application can realize two working conditions of refrigeration and heating, can provide cold load and heat load for buildings, has more application scenarios of the system, and improves the application range of the flue gas waste heat utilization system. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 Schematic diagram of waste heat recovery for the gas turbine combined heat and power unit flue gas waste heat deep utilization method of the present application;

[0043] Figure 2 Schematic diagram of refrigeration working condition for the gas turbine combined heat and power unit flue gas waste heat deep utilization method of the present application;

[0044] Figure 3 Schematic diagram of heating working condition for the gas turbine combined heat and power unit flue gas waste heat deep utilization method of the present application;

[0045] The figure shows: 1, gas turbine compressor, 2, combustion chamber, 3, turbine chamber, 4, steam turbine, 5, waste heat boiler, 6, chimney, 7, generator, 8, flue gas regulating baffle, 9, air blower, 10, contact heat exchanger, 11, intermediate medium flow regulating valve, 12, chemical feeding device, 13, control system, 14, intermediate medium circulating water delivery pump, 15, refrigeration inlet valve, 16, heating inlet valve, 17, steam-water mixer, 18, first steam valve, 19, second steam valve, 20, refrigeration outlet valve, 21, heating outlet valve, 26, hot water type lithium bromide unit, 261, first generator, 262, first condenser, 263, first absorber, 264, first evaporator, 27, steam type lithium bromide unit, 271, second generator, 272, second condenser, 273, second absorber, 274, second evaporator, 28, second drain valve. DETAILED DESCRIPTION

[0046] The present application will be described in detail below in conjunction with the drawings and specific examples. The present embodiment is implemented on the basis of the technical solution of the present application, and detailed implementation and specific operation process are given, but the protection scope of the present application is not limited to the following examples.

[0047] Example 1

[0048] The method for utilizing waste heat flue gas of a gas turbine combined heat and power unit provided in the present application can reduce the temperature of flue gas after waste heat recovery to below the dew point, so as to realize deep utilization of waste heat of flue gas. The outlet temperature of intermediate medium circulating water in the direct contact flue gas heat exchanger 10 is adjusted by the flue gas adjusting baffle 8, the intermediate medium circulating water adjusting valve 11 and the control system 13, so as to adapt to the temperature requirement of the heat source water of the lithium bromide unit in the refrigeration and heating conditions. A small amount of heat network steam is mixed with the outlet intermediate medium cooling water of the direct contact flue gas heat exchanger 10 in refrigeration, which on the one hand improves the heat exchange efficiency of steam and hot water, and on the other hand improves the temperature of hot water entering the lithium bromide unit, so as to meet the refrigeration requirement of the lithium bromide unit and improve the refrigeration efficiency of the lithium bromide unit. Based on the method, the present application further provides a flue gas waste heat utilization system, which can realize operation in two conditions of refrigeration and heating, can provide cold load and heat load for buildings, has more application scenarios of the system, and improves the application range of the flue gas waste heat utilization system.

[0049] The method adopts a waste heat flue gas utilization system including a gas turbine combined heat and power unit, a flue gas waste heat recovery module, a waste heat utilization module, an intermediate medium water temperature adjusting module and a system control module. The flue gas discharged from the waste heat boiler 5 of the gas turbine combined heat and power unit enters the direct contact heat exchanger 10 through the air blower 9 of the flue gas waste heat recovery module, and is in contact with the circulating water (intermediate medium) sprayed on the upper part of the direct contact heat exchanger. After absorbing the waste heat of flue gas, the intermediate medium enters the absorption heat pump unit of the waste heat utilization module. In refrigeration, the heated intermediate medium and the heat network heating steam are further heated in the steam-water mixer 17, and then enter the hot water type absorption lithium bromide unit 26 to realize waste heat refrigeration. In heating, the heated intermediate medium and the heat network heating steam enter the steam type absorption lithium bromide unit 27 to realize waste heat heating. The intermediate medium water temperature adjusting module is used to adjust the temperature of the heated intermediate medium, so as to adapt to different requirements of water temperature in refrigeration and heating. The system control module is used to realize automatic control of the temperature of the intermediate medium and control of starting and stopping and operation of the whole system.

[0050] The air compressed by the gas turbine compressor 1 enters the combustion chamber 2, and the natural gas is combusted in the combustion chamber 2 to release chemical energy, so as to generate high-temperature and high-pressure gas. The high-temperature and high-pressure gas enters the turbine chamber 3 to expand and do work, so as to drive the generator 7 to rotate and generate electric energy. The exhaust gas of the turbine chamber 3 enters the waste heat boiler 5, and the waste heat boiler 5 generates high-temperature and high-pressure steam by using the turbine exhaust gas. The high-temperature and high-pressure steam enters the steam turbine 4, and a part of the steam is supplied to a heat user, and a part of the steam drives the generator to rotate and generate electric energy. The excess flue gas is generally discharged from the chimney 6.

[0051] The flue gas waste heat utilization system of the present application works, the exhaust gas of the waste heat boiler 5 passes through the flue gas adjusting damper 8 and the air blower 9, enters the direct contact heat exchanger 10, and the waste heat is recovered in the contact heat exchanger 10. The intermediate medium after waste heat recovery is sent into the waste heat utilization module by the intermediate medium circulating water delivery pump 14. The recovered waste heat has two utilization methods: refrigeration and heating.

[0052] When the system is refrigerating, the control system adjusts the opening degree of the flue gas damper 8 and the intermediate medium flow regulating valve 11 according to the refrigeration working condition temperature setting value, so that the outlet flue gas temperature (about 50℃) is slightly lower than the flue gas dew point temperature. The heated intermediate medium enters the hot water type lithium bromide unit 26. When refrigerating, the refrigeration inlet valve 15, the first steam valve 18, the refrigeration outlet valve 20 and the intermediate medium flow regulating valve 11 are opened, and the heating inlet valve 16, the second steam valve 19 and the heating outlet valve 21 are closed. The intermediate medium is mixed with the heat network steam in the steam-water mixer 17, the intermediate medium water temperature is further increased, enters the first generator 261 of the hot water type lithium bromide unit 26, completes heat transfer, and then returns to the direct contact flue gas heat exchanger 10 for recycling. The cooling water from the cooling tower passes through the first absorber 263 and the first condenser 262 of the hot water type lithium bromide unit 26, the temperature is increased and then flows back to the cooling tower. The user side cold water return water enters the first evaporator 264 of the hot water type lithium bromide unit 26, the temperature is decreased after heat release, and then is supplied to the user, realizing system cooling.

[0053] When the system is heating, the control system adjusts the opening degree of the flue gas damper 8 and the intermediate medium flow regulating valve 11 according to the heating working condition temperature setting value, so that the outlet flue gas temperature (about 35℃) is far lower than its dew point temperature, and the outlet temperature of the heated intermediate medium is also lower than that in the refrigeration working condition, and then enters the steam type lithium bromide unit 27.

[0054] When heating, the heating inlet valve 16, the second steam valve 19, the heating outlet valve 21 and the intermediate medium flow regulating valve 11 are opened, and the refrigeration inlet valve 15, the first steam valve 18 and the refrigeration outlet valve 20 are closed. The intermediate medium enters the second evaporator 274 of the steam type lithium bromide unit 27, transfers heat and the temperature is decreased, the heat network steam enters the second generator 271 of the steam type lithium bromide unit 27, transfers heat and the temperature is decreased, forming condensed water, and then the condensed water and the intermediate medium are combined and returned to the direct contact flue gas heat exchanger 10 for recycling. The user side hot water return water enters the second absorber 273 and the second condenser 272 of the steam type lithium bromide unit 27, absorbs heat and the temperature is increased, and then is supplied to the user, realizing system heating.

[0055] The control system 13 receives the flue gas adjusting baffle 8, the intermediate medium circulating water adjusting valve 11 and the intermediate medium circulating water outlet water temperature signal, controls the intermediate medium circulating water outlet temperature, and meets the intermediate medium circulating water temperature set value requirement under the refrigeration and heating working conditions.

[0056] The dosing device 12 is added at the intermediate medium circulating water outlet of the contact heat exchanger 10 to adjust the pH value of the intermediate medium.

[0057] The drain valve 28 is added at the intermediate medium circulating water inlet of the contact heat exchanger 10 to drain the condensed water recovered from the flue gas, so that the water amount in the system is kept balanced.

[0058] The application can be applied to the flue gas waste heat utilization field of the gas turbine combined heat and power unit, and the gas turbine combined heat and power unit provides two forms of heat sources: steam and hot water for the waste heat utilization system, and the method can also be used for other similar energy supply systems, such as the natural gas boiler heating system, to realize deep utilization of waste heat. The application can utilize waste heat and recover water vapor in flue gas, has high waste heat utilization efficiency, can provide cold and hot air conditioning loads for users, has a wider application range and a broader application prospect compared with other traditional waste heat utilization systems.

[0059] The preferred embodiments of the application are described in detail above. It should be understood that those skilled in the art can make many modifications and changes without creative labor according to the concept of the application. Therefore, any technical solution obtained by logical analysis, reasoning or limited experiment on the basis of the prior art according to the concept of the application shall be within the protection scope defined by the claims.

Claims

1. A method for deep utilization of flue gas waste heat of a gas turbine combined heat and power unit, characterized in that, The method utilizes flue gas waste heat of a gas turbine combined heat and power unit and heat network steam to carry out heating and refrigeration, and the steps include: sending flue gas discharged by a waste heat boiler (5) of the gas turbine combined heat and power unit into a direct contact heat exchanger (10); the direct contact heat exchanger (10) sprays an intermediate medium to absorb waste heat of the flue gas, and adjusts an outlet temperature of the intermediate medium in the direct contact heat exchanger (10) according to a temperature setting value of a refrigeration or heating working condition, specifically: in refrigeration, according to the temperature setting value of the refrigeration working condition, the flow rates of the flue gas and the intermediate medium into the direct contact heat exchanger (10) are adjusted so that the outlet flue gas temperature of the direct contact heat exchanger (10) is 50℃ to meet the intermediate medium circulating temperature setting value under the refrigeration working condition; in heating, according to the temperature setting value of the heating working condition, the flow rates of the flue gas and the intermediate medium into the direct contact heat exchanger (10) are adjusted so that the outlet flue gas temperature is 35℃ to meet the intermediate medium circulating temperature setting value under the heating working condition; the intermediate medium after absorbing waste heat is used for waste heat utilization, and is used to carry out refrigeration or heating through an absorption heat pump unit; in refrigeration through the waste heat utilization, the intermediate medium after absorbing waste heat is mixed with heat network steam to be heated and then enters a hot water type lithium bromide unit (26) to carry out waste heat refrigeration; in heating through the waste heat utilization, the intermediate medium after absorbing waste heat is input into a steam type lithium bromide unit (27) with heat network heating steam to carry out waste heat heating.

2. The method according to claim 1, wherein, The specific steps of the method for refrigeration include: the intermediate medium after absorbing waste heat is mixed with heat network steam and then enters a first generator (261) of the hot water type lithium bromide unit (26), and returns to the direct contact heat exchanger (10) after completing heat transfer; cooling water from a cooling tower passes through a first absorber (263) and a first condenser (262) of the hot water type lithium bromide unit (26) in sequence, is heated and then flows back to the cooling tower; user side cold water return water enters an evaporator (264) of the hot water type lithium bromide unit (26), is heated and then is supplied to users.

3. The method according to claim 1, wherein the flue gas waste heat is deeply utilized by the combined cycle unit of the gas turbine. The specific steps of the method for heating include: the intermediate medium after absorbing waste heat enters a second evaporator (274) of the steam type lithium bromide unit (27), transfers heat and is heated; heat network steam enters a second generator (271) of the steam type lithium bromide unit (27), transfers heat, is heated and forms condensed water, and the condensed water and the intermediate medium are combined and then return to the direct contact heat exchanger (10); user side hot water return water enters a second absorber (273) and a second condenser (272) of the steam type lithium bromide unit (27) in sequence, absorbs heat, is heated and then is supplied to users.

4. A flue gas residual heat deep utilization system of a gas turbine combined heat and power unit, comprising a gas turbine combined heat and power unit and a steam heat network, characterized in that, The system further includes: a flue gas waste heat recovery module including the direct contact heat exchanger (10) that absorbs waste heat of the flue gas through the intermediate medium; an intermediate medium temperature adjusting module for adjusting the temperature of the intermediate medium output by the waste heat utilization module to adapt to different requirements of the intermediate medium temperature in refrigeration and heating; a waste heat utilization module that utilizes the intermediate medium after absorbing waste heat to carry out refrigeration or heating, including the hot water type lithium bromide unit (26) for refrigeration and the steam type lithium bromide unit (27) for heating. A system control module is configured to automatically control the temperature of the intermediate medium and control the start and stop of the whole system.

5. The system according to claim 4, characterized in that, The waste heat utilization module comprises: The refrigeration sub-module comprises a steam-water mixer (17) and a hot water type lithium bromide unit (26), the steam-water mixer (17) is connected to the first generator (261) of the hot water type lithium bromide unit (26) after mixing the intermediate medium and the steam from the flue gas waste heat recovery module, and then returns to the direct contact heat exchanger (10); the cooling water sequentially passes through the first absorber (263) and the first condenser (262) of the hot water type lithium bromide unit (26); the user side cold water return passes through the first evaporator (264) of the hot water type lithium bromide unit (26), and then returns to the user after heat release and temperature drop; The heating sub-module comprises a steam type lithium bromide unit (27), the intermediate medium from the flue gas waste heat recovery module enters the second evaporator (274) of the steam type lithium bromide unit (27); the steam from the heat supply network enters the second generator (271) of the steam type lithium bromide unit (27) to transfer heat and reduce the temperature to form condensed water, the condensed water and the intermediate medium from the second evaporator (274) are combined and then returned to the direct contact heat exchanger (10); the user side hot water return enters the second absorber (273) and the second condenser (272) of the steam type lithium bromide unit (27), and then returns to the user after absorbing heat and increasing the temperature.

6. The system according to claim 4, characterized in that, The intermediate medium temperature adjustment module comprises: A flue gas adjustment baffle (8) is arranged between the waste heat boiler (5) of the gas turbine combined heat and power unit and the flue gas waste heat recovery module, and is used to adjust the flue gas flow entering the direct contact heat exchanger (10); An intermediate medium circulating water adjustment valve (11) is arranged at the intermediate medium inlet of the flue gas waste heat recovery module, and is used to adjust the intermediate medium flow entering the direct contact heat exchanger (10).

7. The system according to claim 6, characterized in that, The system control module receives signals of the flue gas adjustment baffle (8), the intermediate medium circulating water adjustment valve (11) and the intermediate medium outlet temperature of the flue gas waste heat recovery module, and controls the intermediate medium outlet temperature of the direct contact heat exchanger (10) to meet the intermediate medium temperature set value requirement under the refrigeration and heating working conditions.

8. The system according to claim 4, characterized in that, The system is provided with a dosing device (12) at the intermediate medium outlet of the direct contact heat exchanger (10) to adjust the pH value of the intermediate medium.

9. The system according to claim 4, characterized in that, The system is provided with a drainage valve (28) at the intermediate medium inlet of the direct contact heat exchanger (10) to drain the condensed water recovered from the flue gas to keep the water amount in the system balanced.

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