Multi-quality steam heat supply system and operation method

Abstract

The invention discloses a multi-quality steam heat supply system and an operation method, and belongs to the technical field of coal-fired combined heat and power generation. According to the multi-quality steam heat supply system, high-pressure steam of the boiler and low-pressure steam of the intermediate-pressure cylinder are received through the steam ejector, and the SSS clutch is arranged between the intermediate-pressure cylinder and the low-pressure cylinder rotor; the mass flow ratio of high-pressure steam to low-pressure steam is controlled by controlling the meshing relation of the SSS clutch and adjusting the high-pressure steam valve, the low-pressure steam valve and the butterfly valve, medium-pressure steam supply and low-pressure steam supply of different pressure grades are obtained, extra complex equipment is not needed, flexible adjustment of steam parameters can be achieved only by adjusting the steam ratio, and the steam supply efficiency is improved. Therefore, the requirements of different heat users are met; and meanwhile, energy mixing is achieved through low-pressure steam injection, and energy waste caused by throttling pressure reduction is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of coal-fired cogeneration, and in particular to a multi-quality steam heating system and an operating method thereof. Background Art

[0002] As a highly efficient energy utilization method, cogeneration (CHP) is an effective way to improve the efficiency of coal-fired power generation and expand the scope of centralized heating. It has been widely used in the fields of electricity and heat production. In traditional coal-fired power generation, a large amount of waste heat is discharged into the environment through equipment such as cooling towers, resulting in a significant waste of energy. However, CHP technology cleverly recycles the waste heat generated during power generation for heating, achieving a cascaded energy utilization strategy and improving overall energy efficiency.

[0003] However, existing cogeneration systems have limitations in meeting the diverse needs of heat users. These demands often require additional equipment or complex regulation, increasing system complexity and operating costs while also reducing energy efficiency. For example, to meet the low-pressure steam needs of certain users, high-pressure steam may need to be reduced in pressure, a process that inevitably results in energy losses.

[0004] Therefore, how to provide a multi-quality steam heating system that can meet the diverse needs of different heat users while ensuring the efficiency of the cogeneration system has become a technical problem that needs to be overcome urgently by those skilled in the art. Summary of the Invention

[0005] The purpose of the present invention is to provide a multi-quality steam heating system and an operating method to overcome the problem in the prior art that it is difficult to adapt to the diverse needs of different heat users while ensuring the efficient operation of the cogeneration system.

[0006] The present invention solves the above technical problems through the following technical solutions: A multi-quality steam heating system includes a boiler, a steam ejector, an SSS clutch, a steam turbine, a generator, a heat recovery system, a high-pressure steam valve, a low-pressure steam valve, and a butterfly valve. The steam turbine includes a high-pressure cylinder, a medium-pressure cylinder, and a low-pressure cylinder coaxially connected in sequence. The SSS clutch is installed between the rotor of the intermediate pressure cylinder and the rotor of the low pressure cylinder. The rotor of the low pressure cylinder is connected to the rotor of the generator. The main steam outlet of the boiler is divided into two routes. The first route is connected to the high pressure cylinder inlet, and the second route is connected to the first inlet of the steam ejector through the high pressure steam valve. The reheat steam outlet of the boiler is connected to the intermediate pressure cylinder inlet. The intermediate pressure cylinder outlet is divided into three routes. The first route is connected to the second inlet of the steam ejector through the low pressure steam valve, and the second route is connected to the low pressure cylinder inlet through the butterfly valve. The inlet of the boiler is connected to the third route of the intermediate pressure cylinder outlet, the high pressure cylinder outlet and the first outlet of the low pressure cylinder through the heat recovery system. It also includes a medium-pressure steam supply pipeline and a low-pressure steam supply pipeline. The medium-pressure steam supply pipeline is connected to the outlet of the steam ejector and is used for industrial steam at the industrial end; the low-pressure steam supply pipeline is connected between the medium-pressure cylinder outlet and the low-pressure steam valve and is used for heating steam at the heating end.

[0007] A further improvement of the present invention is that the heat recovery system includes a high-pressure heater assembly, a low-pressure heater, a feed water pump, a deaerator, a condensate pump and a condenser; the second outlet of the low-pressure cylinder is connected in sequence to the condenser, the condensate pump, the low-pressure heater, the deaerator, the feed water pump, the high-pressure heater assembly and the inlet of the boiler.

[0008] A further improvement of the present invention is that the third paths of the high-pressure cylinder outlet and the medium-pressure cylinder outlet are both connected to the high-pressure heater assembly; and the first outlet of the low-pressure cylinder is connected to the low-pressure heater.

[0009] A further improvement of the present invention is that the high-pressure heater assembly includes high-pressure heater No. 1, high-pressure heater No. 2 and high-pressure heater No. 3, the high-pressure cylinder outlet is connected to high-pressure heater No. 1, and the third line of the medium-pressure cylinder outlet is connected to high-pressure heater No. 2 and high-pressure heater No. 3 respectively.

[0010] A further improvement of the present invention is that it also includes a water spray desuperheater, and the medium-pressure steam supply pipeline is connected to the outlet of the steam ejector through the water spray desuperheater.

[0011] A further improvement of the present invention is that it also includes a make-up water pipe and a return water pipe, the first inlet of the condenser is connected in sequence to the return water pipe, the heating end of the heating steam to the low-pressure steam supply pipe; the second inlet of the condenser is connected in sequence to the make-up water pipe, the industrial end of the industrial steam to the medium-pressure steam supply pipe.

[0012] The present invention further provides an operating method of a multi-quality steam heating system, using the multi-quality steam heating system as described above. The multi-quality steam heating method is specifically as follows: The SSS clutch is engaged, and the rotor of the generator drives the high-pressure cylinder, the intermediate-pressure cylinder, and the low-pressure cylinder to work together. When the low-pressure steam generated by the intermediate-pressure cylinder is sufficient, the butterfly valve is opened. By adjusting the opening of the high-pressure steam valve and the low-pressure steam valve, the ratio of the high-pressure steam from the boiler and the low-pressure steam from the intermediate-pressure cylinder received by the steam ejector is adjusted, thereby realizing intermediate-pressure steam supply and low-pressure steam supply of different pressure levels. When the low-pressure steam generated by the intermediate-pressure cylinder is insufficient, the SSS clutch is disengaged, and the rotor of the generator only drives the high-pressure cylinder and the intermediate-pressure cylinder to work, the low-pressure cylinder does not work, and the butterfly valve is closed to transport all the low-pressure steam generated by the intermediate-pressure cylinder to the steam ejector, thereby expanding the intermediate-pressure steam supply regulation range.

[0013] A further improvement of the present invention is that the main steam pressure range of the main steam outlet of the boiler is 9-25 MPa, and the main steam temperature range is 480-566°C.

[0014] A further improvement of the present invention is that when the SSS clutch is in the engaged state, the medium-pressure steam supply pressure of the medium-pressure steam supply pipeline is adjusted in the range of 3 to 10 MPa; the low-pressure steam supply pressure of the low-pressure steam supply pipeline is adjusted in the range of 0.8 to 2 MPa.

[0015] A further improvement of the present invention is that the medium-pressure steam supply adjustment range is expanded to 2 ~ 10Mpa.

[0016] Compared with the prior art, the present invention has the following positive effects: The multi-quality steam heating system provided by the present invention receives high-pressure steam from the boiler and low-pressure steam from the intermediate-pressure cylinder through a steam ejector, and sets an SSS clutch between the intermediate-pressure cylinder and the low-pressure cylinder rotors. By controlling the engagement relationship of the SSS clutch and adjusting the high-pressure steam valve, the low-pressure steam valve and the butterfly valve to control the mass flow ratio of high-pressure steam and low-pressure steam, medium-pressure steam supply and low-pressure steam supply of different pressure levels can be obtained. No additional complex equipment is required, and flexible adjustment of steam parameters can be achieved only by adjusting the steam ratio, thereby meeting the needs of different heat users; at the same time, energy mixing is achieved through low-pressure steam injection, reducing energy waste caused by throttling and pressure reduction.

[0017] Furthermore, through the heat recovery system, the exhaust steam from the low-pressure cylinder passes through the condenser, condensate pump, low-pressure heater, deaerator, feed water pump and high-pressure heater components in sequence, and finally returns to the boiler inlet; in this process, the waste heat of the steam is gradually recovered and utilized to heat the feed water, and the feed water temperature is increased before entering the boiler, which can reduce boiler fuel consumption and improve the energy utilization efficiency of the entire cogeneration system.

[0018] Furthermore, steam from different sources has different pressure and temperature characteristics. By rationally allocating steam to different high-pressure heaters, irreversible loss of steam during the heating process is reduced.

[0019] Furthermore, a water spray desuperheater is installed at the connection between the medium-pressure steam supply pipeline and the steam ejector outlet, which can flexibly adjust the temperature of the output steam according to the specific requirements of different industrial users for the medium-pressure steam temperature, ensure that the steam quality meets user requirements, and meet the diverse industrial production needs.

[0020] The operating method of the multi-quality steam heating system provided by the present invention flexibly adjusts the proportion of steam entering the steam ejector by controlling the state of the SSS clutch and the high-pressure steam valve, low-pressure steam valve, and butterfly valve under different operating conditions. When the low-pressure steam generated by the intermediate-pressure cylinder is sufficient, the steam at the intermediate-pressure cylinder outlet is rationally distributed, with a portion entering the steam ejector for pressure regulation, a portion entering the low-pressure cylinder for continued work, and a portion directly used for low-pressure steam heating. This achieves intermediate-pressure and low-pressure steam supply at different pressure levels and avoids energy waste. When low-pressure steam is insufficient, the SSS clutch is disconnected, allowing the high- and intermediate-pressure cylinders to operate independently, and all the exhaust steam from the intermediate-pressure cylinder is used to provide low-pressure steam and transport it to the steam ejector, expanding the adjustment range of the intermediate-pressure steam supply. This enables the system to provide steam of appropriate pressure levels according to the specific steam pressure requirements of different heat users, meeting the diverse heating needs of industrial production, heating, and other industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings in the specification are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0022] Figure 1 This is a structural schematic diagram of a multi-quality steam heating system of the present invention.

[0023] Among them, 1 is the steam ejector; 2 is the SSS clutch; 3 is the high-pressure steam valve; 4 is the low-pressure steam valve; 5 is the boiler; 6 is the high-pressure cylinder; 7 is the medium-pressure cylinder; 8 is the butterfly valve; 9 is the low-pressure cylinder; 10 is the generator; 11 is the condenser; 12 is the condensate pump; 13 is the low-pressure heater; 14 is the deaerator; 15 is the feed water pump; 16 is the No. 3 high-pressure heater; 17 is the No. 2 high-pressure heater; 18 is the No. 1 high-pressure heater. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0026] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0027] In the description of the embodiments of the present invention, it should be noted that if the terms "upper," "lower," "horizontal," "inner," etc. appear, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the inventive product is typically placed when in use. These terms are merely for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first," "second," etc. are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0028] Furthermore, it should be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be interpreted broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, which are intended to explain the present invention rather than to limit it.

[0030] A multi-quality steam heating system includes a boiler 5, a steam ejector 1, an SSS clutch 2, a steam turbine, a generator 10, a heat recovery system, a high-pressure steam valve 3, a low-pressure steam valve 4, and a butterfly valve 8. The steam turbine includes a high-pressure cylinder 6, an intermediate-pressure cylinder 7, and a low-pressure cylinder 9 coaxially connected in sequence; The SSS clutch 2 is arranged between the rotor of the intermediate-pressure cylinder 7 and the rotor of the low-pressure cylinder 9. The rotor of the low-pressure cylinder 9 is connected to the rotor of the generator 10. The main steam outlet of the boiler 5 is divided into two routes, the first route is connected to the inlet of the high-pressure cylinder 6, and the second route is connected to the first inlet of the steam ejector 1 through the high-pressure steam valve 3. The reheat steam outlet of the boiler 5 is connected to the inlet of the intermediate-pressure cylinder 7. The outlet of the intermediate-pressure cylinder 7 is divided into three routes. The first route is connected to the second inlet of the steam ejector 1 through the low-pressure steam valve 4, and the second route is connected to the inlet of the low-pressure cylinder 9 through the butterfly valve 8. The inlet of the boiler 5 is connected to the third route of the outlet of the intermediate-pressure cylinder 7, the outlet of the high-pressure cylinder 6, and the first outlet of the low-pressure cylinder 9 through the regenerative system. It also includes a medium-pressure steam supply pipeline and a low-pressure steam supply pipeline. The medium-pressure steam supply pipeline is connected to the outlet of the steam ejector 1 and is used for industrial steam at the industrial end; the low-pressure steam supply pipeline is connected between the outlet of the medium-pressure cylinder 7 and the low-pressure steam valve 4 and is used for heating steam at the heating end.

[0031] The high-pressure steam from the boiler 5 and the low-pressure steam from the intermediate-pressure cylinder 7 are received through the steam ejector 1. The SSS clutch is set between the rotors of the intermediate-pressure cylinder 7 and the low-pressure cylinder 9. The mass flow ratio of the high-pressure steam and the low-pressure steam is controlled by controlling the engagement relationship of the SSS clutch and adjusting the high-pressure steam valve 3, the low-pressure steam valve 4 and the butterfly valve 8 to obtain medium-pressure steam supply and low-pressure steam supply of different pressure levels. Without the need for additional complex equipment, the steam parameters can be flexibly adjusted only by adjusting the steam ratio, thereby meeting the needs of different heat users. At the same time, energy mixing is achieved through the low-pressure steam injection, reducing energy waste caused by throttling and pressure reduction.

[0032] Specifically, the heat recovery system includes a high-pressure heater assembly, a low-pressure heater 13, a feed water pump 15, a deaerator 14, a condensate pump 12 and a condenser 11; the second outlet of the low-pressure cylinder 9 is connected in sequence to the condenser 11, the condensate pump 12, the low-pressure heater 13, the deaerator 14, the feed water pump 15, the high-pressure heater assembly and the inlet of the boiler 5.

[0033] Through the heat recovery system, the exhaust steam from the low-pressure cylinder 9 passes through the condenser 11, the condensate pump 12, the low-pressure heater 13, the deaerator 14, the feed water pump 15 and the high-pressure heater assembly in sequence, and finally returns to the inlet of the boiler 5; in this process, the waste heat of the steam is gradually recovered and utilized to heat the feed water, and the feed water enters the boiler 5 after the temperature is increased, which can reduce the fuel consumption of the boiler 5 and improve the energy utilization efficiency of the entire cogeneration system.

[0034] Specifically, the third outlets of the high-pressure cylinder 6 and the medium-pressure cylinder 7 are both connected to the high-pressure heater assembly; the first outlet of the low-pressure cylinder 9 is connected to the low-pressure heater 13 .

[0035] Specifically, the high-pressure heater assembly includes a No. 1 high-pressure heater 18, a No. 2 high-pressure heater 17 and a No. 3 high-pressure heater 16. The outlet of the high-pressure cylinder 6 is connected to the No. 1 high-pressure heater 18, and the third line of the outlet of the medium-pressure cylinder 7 is connected to the No. 2 high-pressure heater 17 and the No. 3 high-pressure heater 16 respectively.

[0036] Steam from different sources has different pressure and temperature characteristics. By rationally allocating steam to different high-pressure heaters, the irreversible loss of steam during the heating process is reduced.

[0037] The more stages the heat recovery system has, the higher the theoretical system cycle efficiency. Therefore, the number of high-pressure heaters or low-pressure heaters can be increased to 13 as much as possible. However, this is also limited by investment and site conditions and is generally limited to 7 to 8 stages. Since the double-extraction steam supply unit has a large amount of heat supply extraction steam and a relatively small amount of heat recovery extraction steam, it is difficult to support multi-stage heating of the main feed water. The number of high-pressure and low-pressure heaters can be further reduced to 13 stages. The efficiency improvement brought by the double-extraction steam supply is more obvious, which can offset the efficiency loss caused by the reduction in the number of heat recovery stages.

[0038] Specifically, it also includes a water spray desuperheater, and the medium-pressure steam supply pipeline is connected to the outlet of the steam ejector 1 through the water spray desuperheater.

[0039] A water spray desuperheater is installed at the connection between the medium-pressure steam supply pipeline and the outlet of the steam ejector 1. It can flexibly adjust the temperature of the output steam according to the specific requirements of different industrial users for the medium-pressure steam temperature, ensure that the steam quality meets the user requirements, and meet the diverse industrial production needs.

[0040] The steam ejector 1 prioritizes pressure matching and outputs steam that meets the pressure requirements, but the temperature matching is not accurate enough. It can be connected to a water spray desuperheater or other device for temperature adjustment. The ejection coefficient of the steam ejector 1 is the ratio of the mass flow rates of low-pressure steam and high-pressure steam. By adjusting the high-pressure steam valve 3 and the low-pressure steam valve 4, the flow rates of high- and low-pressure steam can be controlled, and then the ejection coefficient can be adjusted to generate steam of various pressures between the high- and low-pressure steam pressures.

[0041] Specifically, it also includes a feed water pipe and a return water pipe. The first inlet of the condenser 11 is connected to the return water pipe, the heating end of the heating steam to the low-pressure steam supply pipe in sequence; the second inlet of the condenser 11 is connected to the feed water pipe, the industrial end of the industrial steam to the medium-pressure steam supply pipe in sequence.

[0042] Based on the same inventive concept, the present invention further provides an operating method of a multi-quality steam heating system, using the multi-quality steam heating system as described above. The multi-quality steam heating method is specifically as follows: Engage the SSS clutch 2, and use the rotor of the generator 10 to drive the high-pressure cylinder 6, the intermediate-pressure cylinder 7, and the low-pressure cylinder 9 to work together. When the low-pressure steam generated by the intermediate-pressure cylinder 7 is sufficient, open the butterfly valve 8. By adjusting the openings of the high-pressure steam valve 3 and the low-pressure steam valve 4, the ratio of the high-pressure steam from the boiler 5 and the low-pressure steam from the intermediate-pressure cylinder 7 received by the steam ejector 1 is adjusted, thereby achieving intermediate-pressure steam supply and low-pressure steam supply at different pressure levels. When the low-pressure steam generated by the intermediate-pressure cylinder 7 is insufficient, the SSS clutch 2 is disengaged, and the rotor of the generator 10 only drives the high-pressure cylinder 6 and the intermediate-pressure cylinder 7 to work, the low-pressure cylinder 9 does not work, and the butterfly valve 8 is closed to transport all the low-pressure steam generated by the intermediate-pressure cylinder 7 to the steam ejector 1, thereby expanding the medium-pressure steam supply adjustment range.

[0043] The SSS clutch 2 has two operating modes: disengagement and engagement, which can realize the disturbance-free switching of the two heating modes of the unit, namely back pressure operation and extraction condensing operation. When the SSS clutch 2 is disengaged, the rotor of the low-pressure cylinder 9 is disengaged from the rotors of the high- and medium-pressure cylinders 7, so that the rotor of the low-pressure cylinder 9 no longer rotates to do work, the low-pressure cylinder 9 does not work, the unit operates at back pressure, and all the exhaust steam of the medium-pressure cylinder 7 is used for heating, with the maximum heat supply. When engaged, the low-pressure cylinder 9 works normally together with the high-pressure cylinder 6 and the medium-pressure cylinder 7, and the unit operates at extraction condensing, ensuring good power generation while providing heat. Electrical efficiency; the SSS clutch 2 can absorb the relative displacement between the input shaft and the output shaft. When the SSS clutch 2 is arranged between the high- and medium-pressure rotors and the low-pressure rotor, the axial dynamic and static design clearance of the low-pressure flow can be reduced; after the SSS clutch 2 is disengaged, the low-pressure cylinder 9 does not work, the low-pressure heater 13 is deactivated, the unit operates at back pressure, and the condenser 11 is no longer used to condense the exhaust steam of the low-pressure cylinder 9, but is only used to collect return water and make-up water into the circulation system. The condenser 11 can also be deactivated and the return water and make-up water can be directly connected to the deaerator 14.

[0044] The operating method provided by the present invention flexibly adjusts the proportion of steam entering the steam ejector 1 by controlling the state of the SSS clutch 2, as well as the high-pressure steam valve 3, the low-pressure steam valve 4, and the butterfly valve 8 under different operating conditions. When the low-pressure steam generated by the intermediate-pressure cylinder 7 is sufficient, the steam at the outlet of the intermediate-pressure cylinder 7 is rationally distributed, with a portion entering the steam ejector 1 for pressure regulation, a portion entering the low-pressure cylinder 9 for further work, and a portion directly used for low-pressure steam heating. This achieves intermediate-pressure and low-pressure steam supply at different pressure levels and avoids energy waste. When low-pressure steam is insufficient, the SSS clutch 2 is disconnected, allowing the high- and intermediate-pressure cylinders 7 to operate independently, and all the exhaust steam from the intermediate-pressure cylinder 7 is used to provide low-pressure steam and transported to the steam ejector 1. This expands the adjustment range of the intermediate-pressure steam supply, enabling the system to provide steam of appropriate pressure levels according to the specific steam pressure requirements of different heat users, meeting diverse heat needs such as industrial production and heating.

[0045] Specifically, the main steam pressure of the main steam outlet of the boiler 5 ranges from 9 to 25 MPa, and the main steam temperature ranges from 480 to 566°C.

[0046] Specifically, when the SSS clutch 2 is in the engaged state, the medium-pressure steam supply pressure of the medium-pressure steam supply pipeline is adjusted in the range of 3 to 10 MPa; the low-pressure steam supply pressure of the low-pressure steam supply pipeline is adjusted in the range of 0.8 to 2 MPa.

[0047] Specifically, the expanded medium-pressure steam supply adjustment range is 2 ~ 10Mpa.

[0048] Example 1 Referring to the figure, a multi-quality steam heating system includes a boiler 5, a steam ejector 1, an SSS clutch 2, a steam turbine, a generator 10, a regenerative system, a high-pressure steam valve 3, a low-pressure steam valve 4, and a butterfly valve 8. The steam turbine includes a high-pressure cylinder 6, an intermediate-pressure cylinder 7, a low-pressure cylinder 9, a low-pressure heater 13, a feedwater pump 15, a deaerator 14, a condensate pump 12, a condenser 11, a No. 1 high-pressure heater 18, a No. 2 high-pressure heater 17, and a No. 3 high-pressure heater 16, which are coaxially connected in sequence. The steam at the outlet of the boiler 5 is divided into two streams, one of which enters the steam ejector 1 through the high-pressure steam valve 3 and the other is connected to the inlet of the high-pressure cylinder 6. The steam at the outlet of the high-pressure cylinder 6 returns to the inlet of the boiler 5 and is connected to the inlet of the intermediate-pressure cylinder 7 after reheating. The steam at the outlet of the intermediate-pressure cylinder 7 is divided into three streams, one of which enters the steam ejector 1 through the low-pressure steam valve 4, one of which is connected to the inlet of the low-pressure cylinder 9 through the butterfly valve 8, and one of which is directly used for low-pressure steam heating. The outlet of the low-pressure cylinder 9 is connected to the inlet of the condenser 11, the outlet of the condenser 11 is connected to the inlet of the condensate pump 12, the outlet of the condensate pump 12 is connected to the cold fluid inlet of the low-pressure heater 13, the cold fluid outlet of the low-pressure heater 13 is connected to the inlet of the deaerator 14, the outlet of the deaerator 14 is connected to the inlet of the feed water pump 15, the outlet of the feed water pump 15 is connected to the cold fluid inlet of the No. 3 high-pressure heater 16, the cold fluid outlet of the No. 3 high-pressure heater 16 is connected to the cold fluid inlet of the No. 2 high-pressure heater 17, the cold fluid outlet of the No. 2 high-pressure heater 17 is connected to the cold fluid inlet of the No. 1 high-pressure heater 18, and the cold fluid outlet of the No. 1 high-pressure heater 18 is connected to the inlet of the boiler 5, forming a steam Rankine cycle with a reheat cycle and a heat recovery cycle; the high-pressure cylinder 6, the intermediate-pressure cylinder 7, the low-pressure cylinder 9 and the generator 10 are coaxially arranged, and the rotors of the high-pressure cylinder 6, the intermediate-pressure cylinder 7 and the low-pressure cylinder 9 rotate simultaneously, driving the steam to do work, and driving the rotor of the generator 10 to rotate to generate electricity.

[0049] A certain amount of high-pressure steam is extracted from the outlet of the high-pressure cylinder 6 and enters the hot fluid inlet of the No. 1 high-pressure heater 18. The drain water after heat exchange enters the hot fluid inlet of the No. 2 high-pressure heater 17 from the hot fluid outlet of the No. 1 high-pressure heater 18. A certain amount of medium-pressure steam with higher parameters is extracted from the front of the intermediate-pressure cylinder 7 and enters the hot fluid inlet of the No. 2 high-pressure heater 17. The drain water after heat exchange enters the hot fluid inlet of the No. 3 high-pressure heater 16 from the hot fluid outlet of the No. 2 high-pressure heater 17. A certain amount of medium-pressure steam is extracted from the middle of the intermediate-pressure cylinder 7 and enters the hot fluid inlet of the No. 3 high-pressure heater 16. The drain water after heat exchange enters the deaerator 14 inlet from the hot fluid outlet of the No. 3 high-pressure heater 16. A certain amount of medium-pressure steam with lower parameters is extracted from the outlet of the intermediate-pressure cylinder 7 and enters the deaerator. The inlet of the oxygenator 14 and the outlet of the deaerator 14 are connected to the feed water pump 15; a certain amount of low-pressure steam is extracted from the appropriate part of the low-pressure cylinder 9 and enters the hot fluid inlet of the low-pressure heater 13, and the drain water after heat exchange enters the condenser 11 from the hot fluid outlet of the low-pressure heater 13, and is collected with the make-up water, return water and condensed water to form the main feed water; the cold fluids of the high-pressure and low-pressure heaters 13 are both the main feed water, and the hot fluids are respectively extracted from the various levels of extraction steam of the high-pressure, medium-pressure and low-pressure cylinders 9. According to the matching of the cold and hot fluids, the number of high-pressure or low-pressure heaters 13 can be increased or decreased to realize the cascade utilization of energy, complete the step-by-step preheating of the main feed water before entering the boiler 5, make full use of the internal heat of the system, reduce the fuel consumption of the boiler 5, and improve the overall efficiency of the thermal cycle.

[0050] The medium-pressure steam supply provided by the multi-quality steam heating system is generally industrial steam. The medium-pressure steam supply output port is connected to the industrial steam input port. After use, it will not return to the system, resulting in water loss in the system. It is necessary to increase the make-up water of the same flow rate to maintain the normal operation of the steam Rankine cycle. The make-up water pipeline is directly connected to the condenser 11; the low-pressure steam supply is generally heating steam. The low-pressure steam supply output port is connected to the heat network input end. After the steam is used, the heat network return water is formed and connected to the condenser 11 through the heat network output end. The make-up water and return water are combined with the condensate generated by the condenser 11 condensing the exhaust steam of the low-pressure cylinder 9 to form the main feed water. After passing through the condensate pump 12, the low-pressure heater 13, the deaerator 14, the feed water pump 15, the No. 3 high-pressure heater 16, the No. 2 high-pressure heater 17, and the No. 1 high-pressure heater 18, it returns to the boiler 5 inlet and re-enters the multi-quality steam heating system for circulation.

[0051] The steam ejector 1 and SSS clutch 2 are used together to control heating steam parameters, including steam pressure, steam temperature, and steam flow rate. High-pressure steam is drawn from the main steam pipeline into the steam ejector 1, where a high-speed steam flow is generated through the nozzle, forming a low-pressure zone. This is then ejected into the steam ejector 1, where low-pressure steam is discharged from the intermediate-pressure cylinder 7. Different flow ratios are then adjusted based on the high- and low-pressure steam parameters. The high-pressure steam valve 3 and the low-pressure steam valve 4 are then adjusted to control the flow rates of the high- and low-pressure steam. After mixing the high- and low-pressure steam through the steam ejector 1 to achieve the required steam pressure, intermediate-pressure steam with appropriate parameters is provided to the heat user. When insufficient low-pressure steam enters the steam ejector 1 through the low-pressure steam valve 4 and is unable to reduce the high-pressure steam from the main steam source to the appropriate pressure, the SSS clutch 2, installed between the main shafts of the intermediate-pressure cylinder 7 and the low-pressure cylinder 9, disconnects the low-pressure rotor from the intermediate- and high-pressure rotors of the steam turbine. The low-pressure cylinder 9 stops rotating and working, allowing the intermediate- and high-pressure cylinders 7 to operate independently. All the exhaust steam from the intermediate-pressure cylinder 7 is then used to provide low-pressure steam. This significantly increases the amount of low-pressure steam entering the steam ejector 1, expanding the regulation range of the intermediate-pressure steam supply pressure at the outlet of the steam ejector 1.

[0052] The steam turbine, consisting of high-pressure cylinder 6, intermediate-pressure cylinder 7, and low-pressure cylinder 9, is a supercritical double-extraction cogeneration steam turbine. This supercritical double-extraction unit features high main steam parameters and low cooling losses, improving system energy efficiency. The main steam generated by boiler 5 has a pressure range of 9 to 25 MPa and a temperature range of 480 to 566°C. The low-pressure steam supply pressure ranges from 0.8 to 2 MPa, and the intermediate-pressure steam supply pressure generally ranges from 3 to 10 MPa. By activating SSS clutch 2 to increase the amount of low-pressure steam ejected by steam ejector 1, the intermediate-pressure steam supply pressure range can be further expanded to 2 to 10 MPa. The low-pressure steam supply pressure is determined by the exhaust pressure of intermediate-pressure cylinder 7. The boiler 5, steam turbine, and generator 10 are collectively referred to as a unit. While the pressure varies between units and under different load conditions, it remains essentially unchanged within the same unit and under the same load condition. Adjusting the intermediate-pressure steam supply pressure allows the unit to remain constant even when the load condition remains unchanged.

[0053] The multi-quality steam heating system provided by the present invention receives a part of the main steam high-pressure steam from the boiler 5 and a part of the low-pressure steam from the intermediate-pressure cylinder 7 through the steam ejector 1. When the low-pressure steam is sufficient, the ratio of the main steam and the low-pressure steam is adjusted to obtain intermediate-pressure steam supply and low-pressure steam supply of different pressure levels. At this time, the outlet steam of the intermediate-pressure cylinder 7 is divided into three streams: one stream enters the steam ejector 1 through the low-pressure steam valve 4, one stream enters the low-pressure cylinder 9 through the butterfly valve 8, and one stream is directly used for low-pressure steam heating; when the low-pressure steam is insufficient, the butterfly valve 8 is closed, and the low-pressure cylinder 9 does not work. At this time, the outlet steam of the intermediate-pressure cylinder 7 is divided into two streams, one stream enters the steam ejector 1 through the low-pressure steam valve 4, and one stream is directly used for low-pressure steam heating. The connection between the intermediate-pressure cylinder 7 and the low-pressure cylinder 9 is disconnected by the SSS clutch 2, and all the low-pressure steam can be transported to the steam ejector 1, thereby expanding the pressure regulation range. Different flow ratios are made according to the high and low pressure steam parameters, and the high pressure steam valve 3 and the low pressure steam valve 4 are adjusted to control the steam flow entering the steam ejector 1, so as to obtain steam of different pressure levels and meet the requirements of various heat users; when the low pressure steam entering the steam ejector 1 through the low pressure steam valve 4 is insufficient and the high pressure steam from the main steam cannot be reduced to a suitable pressure, the low pressure rotor of the steam turbine is disconnected from the high and medium pressure rotors through the SSS clutch 2 added to the main shaft of the turbine, and the high and medium pressure cylinders 7 work independently, and the exhaust steam of the medium pressure cylinder 7 is all used to provide low pressure steam, and the amount of low pressure steam entering the steam ejector 1 is increased, which expands the adjustment range of the steam pressure at the outlet of the steam ejector 1, enhances the heating flexibility of the unit, and enables the system to adjust the heating mode and heating steam pressure in time according to the needs of heat users, thereby improving the overall efficiency.

[0054] Finally, it should be noted that the embodiments listed above are merely one or more specific manifestations of the technical solution of the present invention. Their purpose is to clearly illustrate the concept, principles, and application of the present invention through specific examples, and is in no way intended to limit the scope of protection of the present invention to these specific embodiments. In fact, the true value of this invention lies in its technical ideas and innovations, not in its form of expression or implementation.

[0055] For ordinary technicians in the relevant technical field, after thoroughly reading and understanding the technical solutions of the present invention, they are fully capable of making various forms of changes, modifications or equivalent replacements to the specific implementation methods of the invention based on their own professional knowledge and skills. These changes may include but are not limited to: adjusting the value range of technical parameters, optimizing algorithm processes to improve efficiency, replacing some technical components to achieve better compatibility or reduce costs, etc. As long as these modified technical solutions still substantially maintain the technical features claimed for protection by the original invention, that is, they can still achieve the core functions and effects of the present invention, then these changes should be deemed to fall within the scope of protection of the pending claims of the present invention.

[0056] Furthermore, with the continuous advancement and development of technology, new technical means and methods continue to emerge, providing ample room for further improvement and perfection of the present invention. Therefore, the scope of protection of the present invention should also include reasonably foreseeable improvements and extensions based on existing technologies. As long as these improvements and extensions do not deviate from the basic principles and core concepts of the present invention, they should be considered equivalent to the present invention and equally protected by patent rights.

Claims

1. A multi-quality steam heating system, characterized in that: It includes a boiler (5), a steam ejector (1), an SSS clutch (2), a steam turbine, a generator (10), a heat recovery system, a high-pressure steam valve (3), a low-pressure steam valve (4) and a butterfly valve (8), wherein the steam turbine includes a high-pressure cylinder (6), a medium-pressure cylinder (7) and a low-pressure cylinder (9) which are coaxially connected in sequence; The SSS clutch (2) is arranged between the rotor of the medium-pressure cylinder (7) and the rotor of the low-pressure cylinder (9), and the rotor of the low-pressure cylinder (9) is connected to the rotor of the generator (10); the main steam outlet of the boiler (5) is divided into two routes, the first route is connected to the inlet of the high-pressure cylinder (6), and the second route is connected to the first inlet of the steam ejector (1) through the high-pressure steam valve (3); the reheat steam outlet of the boiler (5) is connected to the inlet of the medium-pressure cylinder (7), and the outlet of the medium-pressure cylinder (7) is divided into three routes, the first route is connected to the second inlet of the steam ejector (1) through the low-pressure steam valve (4), and the second route is connected to the inlet of the low-pressure cylinder (9) through the butterfly valve (8); the inlet of the boiler (5) is connected to the third route of the outlet of the medium-pressure cylinder (7), the outlet of the high-pressure cylinder (6) and the first outlet of the low-pressure cylinder (9) respectively through the heat recovery system; It also includes a medium-pressure steam supply pipeline and a low-pressure steam supply pipeline. The medium-pressure steam supply pipeline is connected to the outlet of the steam ejector (1) and is used for industrial steam at the industrial end; the low-pressure steam supply pipeline is connected between the outlet of the medium-pressure cylinder (7) and the low-pressure steam valve (4) and is used for heating steam at the heating end.

2. The multi-quality steam heating system according to claim 1, characterized in that: The heat recovery system includes a high-pressure heater assembly, a low-pressure heater (13), a feed water pump (15), a deaerator (14), a condensate pump (12) and a condenser (11); the second outlet of the low-pressure cylinder (9) is connected in sequence to the condenser (11), the condensate pump (12), the low-pressure heater (13), the deaerator (14), the feed water pump (15), the high-pressure heater assembly and the inlet of the boiler (5).

3. The multi-quality steam heating system according to claim 2, characterized in that: The third outlet of the high-pressure cylinder (6) and the outlet of the medium-pressure cylinder (7) are both connected to the high-pressure heater assembly; the first outlet of the low-pressure cylinder (9) is connected to the low-pressure heater (13).

4. The multi-quality steam heating system according to claim 3, characterized in that: The high-pressure heater assembly includes a No. 1 high-pressure heater (18), a No. 2 high-pressure heater (17) and a No. 3 high-pressure heater (16). The outlet of the high-pressure cylinder (6) is connected to the No. 1 high-pressure heater (18), and the third outlet of the medium-pressure cylinder (7) is connected to the No. 2 high-pressure heater (17) and the No. 3 high-pressure heater (16).

5. The multi-quality steam heating system according to claim 3, characterized in that: It also includes a water spray desuperheater, and the medium-pressure steam supply pipeline is connected to the outlet of the steam ejector (1) through the water spray desuperheater.

6. The multi-quality steam heating system according to claim 3, characterized in that: It also includes a water supply pipe and a return water pipe. The first inlet of the condenser (11) is connected in sequence to the return water pipe, the heating end of the heating steam, and the low-pressure steam supply pipe; the second inlet of the condenser (11) is connected in sequence to the water supply pipe, the industrial end of the industrial steam, and the medium-pressure steam supply pipe.

7. A method for operating a multi-quality steam heating system, characterized in that: The multi-quality steam heating system according to any one of claims 1 to 6 is used, and the operating method is specifically as follows: The SSS clutch (2) is engaged, and the rotor of the generator (10) drives the high-pressure cylinder (6), the medium-pressure cylinder (7), and the low-pressure cylinder (9) to work together. When the low-pressure steam generated by the medium-pressure cylinder (7) is sufficient, the butterfly valve (8) is opened, and the openings of the high-pressure steam valve (3) and the low-pressure steam valve (4) are adjusted to adjust the ratio of the high-pressure steam received by the steam ejector (1) from the boiler (5) and the low-pressure steam received from the medium-pressure cylinder (7), thereby realizing medium-pressure steam supply and low-pressure steam supply of different pressure levels; When the low-pressure steam generated by the intermediate-pressure cylinder (7) is insufficient, the SSS clutch (2) is disengaged, and the rotor of the generator (10) only drives the high-pressure cylinder (6) and the intermediate-pressure cylinder (7) to work, the low-pressure cylinder (9) does not work, and the butterfly valve (8) is closed, so that all the low-pressure steam generated by the intermediate-pressure cylinder (7) is delivered to the steam ejector (1), thereby expanding the medium-pressure steam supply adjustment range.

8. The method for operating a multi-quality steam heating system according to claim 7, wherein: The main steam pressure range of the main steam outlet of the boiler (5) is 9 ~ 25MPa, and the main steam temperature range is 480 ~ 566℃.

9. The method for operating a multi-quality steam heating system according to claim 7, wherein: When the SSS clutch (2) is in the engaged state, the medium-pressure steam supply pressure of the medium-pressure steam supply pipeline is adjusted within a range of 3 to 10 MPa; and the low-pressure steam supply pressure of the low-pressure steam supply pipeline is adjusted within a range of 0.8 to 2 MPa.

10. The method for operating a multi-quality steam heating system according to claim 7, wherein: The expanded medium-pressure steam supply adjustment range is 2 ~ 10Mpa.

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