Combined heat and power generation system capable of efficiently and flexibly heating by means of dual-unit combined supply

Abstract

The present application relates to the technical field of energy utilization, and particularly to a combined heat and power generation system capable of efficiently and flexibly heating by means of dual-unit combined supply, comprising a high backpressure unit and a conventional unit, and further comprising a first-stage heating unit, a second-stage heating unit, a third-stage heating unit, and a fourth-stage heating unit. In the present application, four stages of different heating units are provided and are simultaneously communicated with a conventional backpressure unit and the high backpressure unit, and a low-pressure cylinder crossover pipe heating mode and a low-pressure cylinder zero-output heating mode are flexibly selected on the basis of the total steam consumption demand of the third-stage and fourth-stage heater in combination with the real-time electric load condition of the conventional backpressure unit, so that the heating load of the units can be adjusted more flexibly; and when an electric load is determined, the external heating loads of the conventional and high backpressure units can fluctuate between -50% and +50%, and a high thermal-electric decoupling capability is realized.

Description

A dual-machine combined heat and power supply efficient and flexible heat supply combined heat and power system

[0001] Cross-reference to Related Applications

[0002] The present application claims priority to the Chinese patent application No. 202411358537.5, filed on September 27, 2024, and entitled "A dual-machine combined heat and power supply efficient and flexible heat supply combined heat and power system", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of energy utilization, in particular to a dual-machine combined heat and power supply efficient and flexible heat supply combined heat and power system. BACKGROUND

[0004] High back pressure heat supply refers to increasing the pressure of the exhaust steam in the condenser, using the circulating water of the heat network to cool the exhaust steam, so as to realize the heating of the circulating water by the latent heat of vaporization of the exhaust steam of the turbine unit, and realize heat supply. This technology has low heat supply energy consumption. However, it has the following shortcomings: (1) strong coupling between heat and electricity, poor operation flexibility, when the heat supply is constant, the electric load adjustment capacity is less than 5%, and (2) high requirement for heat network operation stability, when the circulating water of the heat network leaks, it may cause insufficient cooling water of the unit and increase the exhaust temperature, thereby threatening the safe operation of the unit.

[0005] The medium and low pressure connection pipe heat supply and the low pressure cylinder zero output heat supply technology both use the exhaust steam of the medium pressure cylinder to heat the circulating water of the heat network. In this way, the unit has greater operation flexibility, but the exhaust steam of the medium pressure cylinder has high energy quality, and direct use for heating the circulating water of the heat network causes energy loss, and the heat supply energy consumption is high.

[0006] Due to their respective shortcomings, the unit cannot balance the generation flexibility and heat supply energy consumption, resulting in energy waste. SUMMARY

[0007] This section is intended to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract of the specification and the title of the invention to avoid obscuring the purpose of this section, the abstract of the specification and the title of the invention, and such simplifications or omissions cannot be used to limit the scope of the present application.

[0008] In view of the above problem that the heat supply unit operation flexibility and heat supply energy consumption cannot be well balanced, the present application is proposed.

[0009] Therefore, the purpose of the present application is to provide a dual-machine combined heat and power supply efficient and flexible heat supply combined heat and power system.

[0010] To solve the above technical problems, the application provides the following technical scheme: a dual-unit combined high-efficiency flexible heating combined heat and power system, comprising a high-back-pressure unit cell and a conventional unit cell, further comprising a first heating unit, a second heating unit, a third heating unit and a fourth heating unit; the first heating unit is in communication with the high-back-pressure unit cell and is used for preliminarily heating heating return water, the second heating unit is in communication with the high-back-pressure unit cell and the first heating unit and is used for further heating the heating return water, the third heating unit is in communication with the high-back-pressure unit cell, the conventional unit cell and the second heating unit and uses unit exhaust steam to further heat the heating return water, and the fourth heating unit is in communication with the conventional unit cell and the third heating unit and uses conventional unit exhaust steam to finally heat the heating return water.

[0011] As an optional solution of the dual-unit combined high-efficiency flexible heating combined heat and power system, the high-back-pressure unit cell comprises a high-back-pressure intermediate-pressure cylinder, a high-back-pressure low-pressure cylinder, a high-back-pressure communication steam pipe, a high-back-pressure generator, a high-back-pressure condenser, a condensate pump, a low-temperature heating module and a deaerator, the high-back-pressure intermediate-pressure cylinder and the high-back-pressure low-pressure cylinder are supplied with steam through the high-back-pressure communication steam pipe, the high-back-pressure intermediate-pressure cylinder, the high-back-pressure low-pressure cylinder and the high-back-pressure generator are coaxially arranged, the exhaust steam outlet of the high-back-pressure low-pressure cylinder is in communication with the high-back-pressure condenser, the water outlet of the high-back-pressure condenser is in communication with the condensate pump, the water outlet of the condensate pump is in communication with the low-temperature heating module, and the water outlet of the low-temperature heating module is in communication with the deaerator.

[0012] As an optional solution of the dual-unit combined high-efficiency flexible heating combined heat and power system, the conventional unit cell comprises a conventional intermediate-pressure cylinder, a conventional low-pressure cylinder, a conventional communication steam pipe, a conventional generator and a conventional condenser, the conventional intermediate-pressure cylinder and the conventional low-pressure cylinder are supplied with steam through the conventional communication steam pipe, the conventional intermediate-pressure cylinder, the conventional low-pressure cylinder and the conventional generator are coaxially arranged, and the exhaust steam outlet of the conventional low-pressure cylinder is in communication with the conventional condenser.

[0013] As an optional solution of the dual-unit combined high-efficiency flexible heating combined heat and power system, the first heating unit comprises a heating return water pipe, an adding port and an adding outlet, the input end of the heating return water pipe is in communication with external heating return water, the output end of the heating return water pipe is in communication with the adding port, and the adding port and the adding outlet are arranged on the high-back-pressure condenser.

[0014] As an optional solution of the double-machine combined high-efficient flexible heat supply cogeneration system described in the application, the secondary heating unit comprises a secondary heater, a secondary water supply pipe, a secondary heat supply pipe, a secondary water discharge pipe and a secondary water outlet pipe, the secondary heater is provided with a cold side and a hot side, the secondary water supply pipe is in communication with the first outlet and the water inlet of the cold side of the secondary heater respectively, the secondary heat supply pipe is in communication with the low-pressure heater and the heat supply port of the hot side of the secondary heater respectively, the secondary water discharge pipe is in communication with the hot side of the secondary heater and the input end of the low-pressure heater, and the secondary water outlet pipe is in communication with the water outlet of the cold side of the secondary heater.

[0015] As an optional solution of the double-machine combined high-efficient flexible heat supply cogeneration system described in the application, the tertiary heating unit comprises a tertiary heater, a medium-pressure cylinder steam supply pipe, a low-pressure cylinder steam supply pipe, a tertiary water supply pipe and a tertiary water discharge pipe, the tertiary heater is provided with two hot sides and one cold side, the input end of the cold side is in communication with the secondary water outlet pipe, and the output end of the cold side is in communication with the quaternary heating unit.

[0016] As an optional solution of the double-machine combined high-efficient flexible heat supply cogeneration system described in the application, one hot side of the tertiary heater is in communication with the medium-pressure cylinder exhaust steam through the medium-pressure cylinder steam supply pipe, the other hot side of the tertiary heater is in communication with the high-back-pressure low-pressure cylinder exhaust steam through the low-pressure cylinder steam supply pipe, and the output ends of the two hot sides of the tertiary heater are in communication with the output end of the condensate pump.

[0017] As an optional solution of the double-machine combined high-efficient flexible heat supply cogeneration system described in the application, the quaternary heating unit comprises a quaternary heater, a quaternary water supply pipe, a quaternary water discharge pipe, a quaternary steam supply branch, a water supply bypass and a quaternary water outlet pipe.

[0018] As an optional solution of the double-machine combined high-efficient flexible heat supply cogeneration system described in the application, the quaternary heater is in communication with the tertiary heater through the quaternary water supply pipe, and the output end of the quaternary heater is in communication with the external heating water supply through the quaternary water discharge pipe.

[0019] As an optional solution of the double-machine combined high-efficient flexible heat supply cogeneration system described in the application, the quaternary steam supply branch is in communication with the medium-pressure cylinder steam supply pipe, and the two ends of the water supply bypass are in communication with the tertiary water supply pipe and the quaternary water discharge pipe respectively.

[0020] The beneficial effects of the present application: the present application sets up four different heating units, simultaneously communicates with the conventional back pressure unit and the high back pressure unit, the medium pressure cylinder exhaust steam in the conventional back pressure unit is used as the heat source of the fourth heating unit to heat the heat network water; according to the total steam demand of the third and fourth heating units, combined with the real-time electric load of the conventional back pressure unit, the low pressure cylinder communication pipe heat supply mode and the low pressure cylinder zero output heat supply mode are flexibly selected, which can more flexibly adjust the heat supply load of the unit, and the general heat load fluctuation degree of the conventional high back pressure unit under the condition of the determined electric load is not more than 5%; under the scheme of the present application, the general heat supply load of the conventional high back pressure unit can fluctuate between ±50% under the condition of the determined electric load, and has high heat and electricity decoupling capability. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating laborious work.

[0022] Fig. 1 is a whole schematic diagram of a double-machine combined high-efficiency flexible heat supply combined heat and power system. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned purposes, features and advantages of the present application more apparent and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the drawings of the specification.

[0024] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of the present application, therefore the present application is not limited by the specific embodiments disclosed below.

[0025] Secondly, the "one embodiment" or "embodiment" referred to herein means that the specific features, structures or characteristics can be included in at least one implementation of the present application. "In one embodiment" appearing in different places in the specification does not mean the same embodiment, nor is it an embodiment that is independent of or selected from other embodiments.

[0026] Thirdly, the present application is described in detail in combination with the schematic diagram, in the detailed description of the embodiments of the present application, for the convenience of description, the sectional view showing the structure of the device will be partially enlarged without general proportion, and the schematic diagram is only an example, which should not limit the scope of protection of the present application herein. In addition, the three-dimensional spatial dimensions of length, width and depth should be included in actual manufacture.

[0027] Embodiment 1

[0028] Referring to Fig. 1, for the first embodiment of the present application, the embodiment provides a dual-heat-supply high-efficiency flexible heat-supply combined heat and power system, which comprises a high-back-pressure unit 100 and a conventional unit 200, and further comprises a first heating unit 300, a second heating unit 400, a third heating unit 500 and a fourth heating unit 600; the first heating unit 300 is in communication with the high-back-pressure unit 100 and is used for preliminarily heating the heating return water, the second heating unit 400 is in communication with the high-back-pressure unit 100 and the first heating unit 300 and is used for further heating the heating return water, the third heating unit 500 is in communication with the high-back-pressure unit 100, the conventional unit 200 and the second heating unit 400 and uses the exhaust steam of the units to further heat the heating return water, and the fourth heating unit 600 is in communication with the conventional unit 200 and the third heating unit 500 and uses the exhaust steam of the conventional unit 200 to finally heat the heating return water.

[0029] Specifically, the high-back-pressure unit 100 comprises a high-back-pressure intermediate-pressure cylinder 101, a high-back-pressure low-pressure cylinder 102, a high-back-pressure communication steam pipe 103, a high-back-pressure generator 104, a high-back-pressure condenser 105, a condensate pump 106, a low-pressure heater module 107 and a deaerator 108; the high-back-pressure intermediate-pressure cylinder 101 is supplied with steam through the high-back-pressure communication steam pipe 103 with the high-back-pressure low-pressure cylinder 102; the high-back-pressure intermediate-pressure cylinder 101, the high-back-pressure low-pressure cylinder 102 and the high-back-pressure generator 104 are coaxially arranged; the exhaust steam outlet of the high-back-pressure low-pressure cylinder 102 is in communication with the high-back-pressure condenser 105; the water outlet of the high-back-pressure condenser 105 is in communication with the condensate pump 106; the water outlet of the condensate pump 106 is in communication with the low-pressure heater module 107; the water outlet of the low-pressure heater module 107 is in communication with the deaerator 108; the high-back-pressure condenser 105 serves as a first heater; the heating return water (generally at 40-50℃) is added in the first heater; when the exhaust steam back pressure of the low-pressure cylinder of the steam turbine is 54 kPa, the water temperature at the outlet of the first heater can reach about 80℃; the heating water is heated in the first heater and then enters the second heater 401; the low-pressure heater module 107 is provided with four low-pressure heaters which are in communication with each other and with the high-back-pressure low-pressure cylinder 102.

[0030] Optionally, the conventional unit 200 comprises a conventional intermediate-pressure cylinder 201, a conventional low-pressure cylinder 202, a conventional communication steam pipe 203, a conventional generator 204 and a conventional condenser 205; the conventional intermediate-pressure cylinder 201 is supplied with steam through the conventional communication steam pipe 203 with the conventional low-pressure cylinder 202; the conventional intermediate-pressure cylinder 201, the conventional low-pressure cylinder 202 and the conventional generator 204 are coaxially arranged; the exhaust steam outlet of the conventional low-pressure cylinder 202 is in communication with the conventional condenser 205; the conventional unit 200 does not participate in the first heating and the second heating; the conventional unit is in a conventional back pressure state or a low-pressure cylinder zero output state.

[0031] Optionally, the first heating unit 300 comprises a heating return water pipe 301, an inlet 302 and an outlet 303, the input end of the heating return water pipe 301 is in communication with the external heating return water, the output end of the heating return water pipe 301 is in communication with an inlet 302, the inlet 302 and the outlet 303 are arranged on the high back pressure condenser 105, and the heating return water is heated by the exhaust steam of the high back pressure low pressure cylinder 102 entering the high back pressure condenser 105.

[0032] Optionally, the second heating unit 400 comprises a second heating unit 401, a second supply water pipe 402, a second supply heat pipe 403, a second drain pipe 404 and a second outlet water pipe 405, the second heating unit 401 is provided with a cold side and a hot side, the second supply water pipe 402 is in communication with the outlet 303 and the cold side water inlet of the second heating unit 401 respectively, the second supply heat pipe 403 is in communication with the low heating module 107 and the hot side heat supply port of the second heating unit 401 respectively, the second drain pipe 404 is in communication with the hot side of the second heating unit 401 and the input end of the low heating module 107, and the second outlet water pipe 405 is in communication with the cold side water outlet of the second heating unit 401.

[0033] Specifically, the second heating unit 401 adopts the first type of absorption heat pump, which can realize that the outlet water temperature of the heat pump driven hot water is lower than the inlet water temperature of the heating network water that needs to be heated, in the second heating unit 401, the condensed water before the inlet of the unit regenerative system deaerator 108 is used as high temperature driven hot water (about 150℃), the driven hot water is heated in the second heating unit 401, and the water temperature is reduced to about 65℃, then the water is pumped back to the unit regenerative system, and the energy of the low pressure cylinder to the low pressure heater of the regenerative system is increased by recycling the high temperature condensed water of the regenerative system, that is, the energy of the low grade steam extraction is indirectly applied (the energy consumption of the low pressure cylinder extraction heating is lower than that of the medium pressure cylinder exhaust heating, wherein the energy consumption index is medium pressure cylinder exhaust>4# low pressure extraction>3# low pressure extraction>2# low pressure extraction>1# low pressure extraction), the energy is used in order and high efficiency, and the heating network water can be heated by 5℃ in the second heating unit 401, that is, the outlet water temperature reaches 85℃, and the outlet water temperature depends on the ratio of the water extraction amount of the regenerative system and the heating network water amount.

[0034] Embodiment 2

[0035] Referring to FIG. 1, the second embodiment of the present application is different from the first embodiment in that the third heating unit 500 comprises a third heating unit 501, a medium pressure cylinder steam supply pipe 502, a low pressure cylinder steam supply pipe 503, a third supply water pipe 504 and a third drain pipe 505, the third heating unit 501 is provided with two hot sides and one cold side, the input end of the cold side is in communication with the second outlet water pipe 405, and the output end of the cold side is in communication with the fourth heating unit 600.

[0036] Specifically, the third heater 501 adopts a second type of absorption heat pump, the exhaust steam of the conventional intermediate-pressure cylinder 201 of the conventional unit 200 is used as the driving heat source of the third heater 501, and the exhaust steam of the high-back-pressure low-pressure cylinder 102 of the high-back-pressure unit 100 is used as the low-temperature heat source. The condensed water recovered from the heat recovery is returned to the pipeline before the condensate pump 106 of the high-back-pressure unit 100.

[0037] Optionally, one hot side of the third heater 501 is in communication with the exhaust steam of the conventional intermediate-pressure cylinder 201 through the intermediate-pressure cylinder steam supply pipe 502, the other hot side of the third heater 501 is in communication with the exhaust steam of the high-back-pressure low-pressure cylinder 102 through the low-pressure cylinder steam supply pipe 503, and the output ends of the two hot sides of the third heater 501 are in communication with the output end of the condensate pump 106.

[0038] During operation, whether the third heater 501 is put into operation is determined according to whether the heat network return water is completely utilized in the first heater. If the heat network return water is small and the high-back-pressure unit exhaust steam waste heat is not completely utilized in the first heater, the third heater 501 is started, and the heat network water is heated in the third heater 501; otherwise, the heat network water is directly connected to the fourth heater 601 through a bypass, and the heating water is heated in the third heater 501, and the temperature is increased by 1-10°C, which mainly depends on the exhaust steam heat that is not utilized in the first heater.

[0039] Embodiment 3

[0040] Referring to FIG. 1, the third embodiment of the present application is different from the above embodiments in that the fourth heating unit 600 includes a fourth heater 601, a fourth heating water supply pipe 602, a fourth heating water discharge pipe 603, a fourth heating steam supply branch 604, a heating water bypass 605, and a fourth heating water outlet pipe 606.

[0041] Specifically, the fourth heater 601 is in communication with the third heater 501 through the fourth heating water supply pipe 602, the output end of the fourth heater 601 is in communication with the external heating water supply through the fourth heating water discharge pipe 603, the fourth heater 601 adopts a surface heat exchanger, and the heating water is heated in the fourth heater 601 to a temperature of 100-110°C, which meets the needs of external heating load.

[0042] Optionally, the fourth heating steam supply branch 604 is in communication with the intermediate-pressure cylinder steam supply pipe 502, and the two ends of the heating water bypass 605 are in communication with the third heating water supply pipe 504 and the fourth heating water discharge pipe 603, respectively.

[0043] The exhaust steam of the medium-pressure cylinder of the conventional unit 200 is used as the heat source of the fourth heater 601 to heat the heat network water; the steam heat exchange cooled drain water is collected to the front pipeline of the condensate pump 106 of the high back pressure unit 100, and the conventional unit 200 flexibly selects the low-pressure cylinder connection pipe heat supply mode and the low-pressure cylinder zero output heat supply mode according to the total steam demand of the third heater 501 and the fourth heater 601 and the real-time electric load of the conventional unit 200.

[0044] Suppose that the total power generation P1 is the total coal consumption of the two units B1; the power generation P1 and the heat supply Q1 correspond to the total coal consumption of the two units B2; then the heat supply energy consumption of the heat supply Q1 is (B2-B1) / Q1, which can reach 13 kg of standard coal / GJ, far lower than the heat supply energy consumption index of 23 kg of standard coal / GJ of the low-pressure cylinder zero output mode. For two 350 MW supercritical units, the heat supply of the two units can reach 3600 GJ / h after using the system.

[0045] Importantly, it should be noted that the constructions and arrangements of the present application shown in the various exemplary embodiments are merely illustrative. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters (e.g., temperatures, pressures, etc.), mounting arrangements, use of materials, colors, orientations, etc.) using no more than the common general knowledge of the art to which this application pertains. For example, elements shown as integrally formed can be constructed of multiple parts or elements, the position of elements can be reversed or otherwise varied, and the nature or number of discrete elements or positions can be altered or changed. Accordingly, all such modifications are intended to be included within the scope of the present application. The order or sequence of any process or method steps can be changed or re-sequenced without departing from the scope of the application. In the claims, any "means plus function" clause is intended to cover the structures described herein as performing the recited functionality, and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes, and omissions can be made in the design, operating conditions, and arrangement of the exemplary embodiments without departing from the scope of the present application. Accordingly, the present application is not limited to the particular embodiments described herein, but extends to various modifications that still fall within the scope of the appended claims.

[0046] Furthermore, in order to provide a concise description of exemplary embodiments, all features of an actual implementation can not be described (i.e., those unrelated to the presently considered best mode of carrying out the present application, or those unrelated to achieving the present application).

[0047] It is to be understood that the detailed description and specific examples described above are intended for purposes of illustration only and are not intended to limit the scope of the present application. Those of ordinary skill in the art will recognize that the technology described herein can be practiced with modification and alteration, and that the technology described herein can be employed with a variety of optical and electronic components. Accordingly, the specification and examples are to be regarded in an illustrative manner and the true scope of the application is indicated by the appended claims along with the full scope of equivalents to which such claims are entitled. It is also to be understood that the following claims are to govern the scope of the application disclosed herein.

[0048] It should be noted that the above examples are merely used to illustrate the technical solutions of the present application but not to limit the present application. Although the present application is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the spirit and scope of the present application, and all should be included in the scope of the claims of the present application.

Claims

1. A combined heat and power system for double supply of high efficient and flexible heating, comprising a high back pressure unit (100) and a conventional unit (200), characterized in that: Also comprising, The primary heating unit (300), the secondary heating unit (400), the tertiary heating unit (500) and the quaternary heating unit (600); The primary heating unit (300) is communicated with the high back pressure unit (100) for preliminary heating of the heating return water, the secondary heating unit (400) is communicated with the high back pressure unit (100) and the primary heating unit (300) for further heating of the heating return water, the tertiary heating unit (500) is communicated with the high back pressure unit (100), the conventional unit (200) and the secondary heating unit (400) for further heating of the heating return water by the exhaust steam of the unit, and the quaternary heating unit (600) is communicated with the conventional unit (200) and the tertiary heating unit (500) for final heating of the heating return water by the exhaust steam of the conventional unit (200).

2. The dual-supply high-efficient flexible heating combined heat and power system according to claim 1, characterized in that: The high back pressure unit (100) comprises a high back pressure intermediate pressure cylinder (101), a high back pressure low pressure cylinder (102), a high back pressure communication steam pipe (103), a high back pressure generator (104), a high back pressure condenser (105), a condensate pump (106), a low pressure heater module (107) and a deaerator (108), the high back pressure intermediate pressure cylinder (101) is supplied with steam through the high back pressure communication steam pipe (103) with the high back pressure low pressure cylinder (102), the high back pressure intermediate pressure cylinder (101), the high back pressure low pressure cylinder (102) and the high back pressure generator (104) are coaxially arranged, the exhaust steam outlet of the high back pressure low pressure cylinder (102) is communicated with the high back pressure condenser (105), the water outlet of the high back pressure condenser (105) is communicated with the condensate pump (106), the water outlet of the condensate pump (106) is communicated with the low pressure heater module (107), and the water outlet of the low pressure heater module (107) is communicated with the deaerator (108).

3. The combined heat and power system with efficient and flexible heating as described in claim 2, characterized in that: The conventional unit (200) comprises a conventional intermediate pressure cylinder (201), a conventional low pressure cylinder (202), a conventional communication steam pipe (203), a conventional generator (204) and a conventional condenser (205), the conventional intermediate pressure cylinder (201) is supplied with steam through the conventional communication steam pipe (203) with the conventional low pressure cylinder (202), the conventional intermediate pressure cylinder (201), the conventional low pressure cylinder (202) and the conventional generator (204) are coaxially arranged, and the exhaust steam outlet of the conventional low pressure cylinder (202) is communicated with the conventional condenser (205).

4. The combined heat and power system with efficient and flexible heating as described in claim 3, characterized in that: The primary heating unit (300) comprises a heating return water pipe (301), an adding inlet (302) and an adding outlet (303), the input end of the heating return water pipe (301) is communicated with the external heating return water, the output end of the heating return water pipe (301) is communicated with the adding inlet (302), and the adding inlet (302) and the adding outlet (303) are arranged on the high back pressure condenser (105).

5. The combined heat and power system with efficient and flexible heating as described in claim 4, characterized in that: The secondary heating unit (400) comprises a secondary heater (401), a secondary water supply pipe (402), a secondary heat supply pipe (403), a secondary water discharge pipe (404), and a secondary water outlet pipe (405). The secondary heater (401) is provided with a cold side and a hot side. The secondary water supply pipe (402) is in communication with the first outlet (303) and the cold side water inlet of the secondary heater (401) respectively. The secondary heat supply pipe (403) is in communication with the low-pressure heater module (107) and the hot side heat supply port of the secondary heater (401) respectively. The secondary water discharge pipe (404) is in communication with the hot side of the secondary heater (401) and the input end of the low-pressure heater module (107). The secondary water outlet pipe (405) is in communication with the cold side water outlet of the secondary heater (401).

6. The combined heat and power system with efficient and flexible heating as described in claim 5, characterized in that: The tertiary heating unit (500) comprises a tertiary heater (501), a medium-pressure cylinder steam supply pipe (502), a low-pressure cylinder steam supply pipe (503), a tertiary water supply pipe (504), a tertiary water discharge pipe (505), and a tertiary water outlet pipe (606). The tertiary heater (501) is provided with two hot sides and one cold side. The input end of the cold side is in communication with the secondary water outlet pipe (405), and the output end of the cold side is in communication with the quaternary heating unit (600).

7. The combined heat and power system with efficient and flexible heating as described in claim 6, characterized in that: One hot side of the tertiary heater (501) is in communication with the exhaust steam of the conventional medium-pressure cylinder (201) through the medium-pressure cylinder steam supply pipe (502). The other hot side of the tertiary heater (501) is in communication with the exhaust steam of the high-back-pressure low-pressure cylinder (102) through the low-pressure cylinder steam supply pipe (503). The output ends of the two hot sides of the tertiary heater (501) are in communication with the output end of the condensate pump (106).

8. The combined heat and power system with efficient and flexible heating as described in claim 7, characterized in that: The quaternary heating unit (600) comprises a quaternary heater (601), a quaternary water supply pipe (602), a quaternary water discharge pipe (603), a quaternary steam supply branch (604), a water supply bypass (605), and a quaternary water outlet pipe (606).

9. The system according to claim 8, wherein the system further comprises a heat exchanger. The quaternary heater (601) is in communication with the tertiary heater (501) through the quaternary water supply pipe (602). The output end of the quaternary heater (601) is in communication with the external heating water supply through the quaternary water discharge pipe (603).

10. The system according to claim 9, wherein the system further comprises a heat exchanger. The quaternary steam supply branch (604) is in communication with the medium-pressure cylinder steam supply pipe (502). The two ends of the water supply bypass (605) are in communication with the tertiary water supply pipe (504) and the quaternary water discharge pipe (603) respectively.

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