A plant steam waste heat recovery and utilization system

Abstract

The present invention belongs to the technical field of waste heat recovery, and discloses a plant steam waste heat recovery and utilization system, including: a steam turbine; a generator and a compressor, which are coaxially connected to the steam turbine; the compressor is provided with a cooling cavity, and the steam inlet of the compressor is connected to the outlet of the cooling cavity; a steam pipeline, which is used to supply steam with waste heat and is connected to the inlet of the cooling cavity of the compressor; a pressure matcher; a low-pressure steam inlet valve, which is arranged between the cooling cavity of the compressor and the side steam inlet of the pressure matcher; a high-pressure steam inlet valve, which is arranged between the steam outlet of the compressor and the axial steam inlet of the pressure matcher; a bypass regulating valve, whose inlet is connected between the high-pressure steam inlet valve and the steam outlet of the compressor, and whose outlet is connected between the outlet of the pressure matcher and the steam inlet of the steam turbine. The present invention solves the problem that the existing steam waste heat recovery system can only convert the waste heat of steam into the heat of water for utilization, and cannot be converted into other energy forms, and has limitations.

Description

Technical Field

[0001] The invention belongs to the technical field of waste heat recovery, and in particular relates to a plant steam waste heat recovery and utilization system. Background Art

[0002] Boiler is a commonly used energy conversion equipment, which can output steam, high temperature water or organic heat carrier with certain thermal energy. After steam is exhausted, it still contains a lot of thermal energy. If the steam is directly discharged, it will cause serious energy waste and is not conducive to environmental protection. Although steam waste heat recovery and steam condensate waste heat recovery have been promoted and applied in many fields, their application form is relatively simple. Usually, only part of the heat is absorbed through simple heat exchange, and a large amount of waste heat is still not utilized.

[0003] my country's patent application number CN201210461394.1 discloses a steam waste heat recovery device, which includes: a steam-water conversion system, a heating system, a bathing system, a water bath drying system and a low-temperature condensed water recovery system. A variety of waste heat recovery methods are integrated into one system, and any method can be switched by opening or closing the pipeline valves and solenoid valves, which is convenient for manufacturing companies to choose and use. However, in the process of realizing the above application, it was found that the above technical solution can only convert the waste heat of steam into water heat for utilization, and cannot be converted into other energy forms, which has limitations. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that the existing steam waste heat recovery system can only convert the waste heat of steam into water heat for utilization, but cannot convert it into other energy forms, thus having limitations.

[0005] In order to solve the above technical problems, the present invention discloses a plant steam waste heat recovery and utilization system, comprising:

[0006] Steam turbine;

[0007] a generator, coaxially connected to the steam turbine;

[0008] A compressor is coaxially connected to the steam turbine; the compressor is provided with a cooling cavity, and the steam inlet of the compressor is connected to the outlet of the cooling cavity;

[0009] a steam pipe, for supplying steam with waste heat, connected to the cooling cavity inlet of the compressor;

[0010] Pressure matching device;

[0011] The pressure matcher comprises:

[0012] an axial steam inlet, connected to a steam outlet of the compressor;

[0013] An injection zone, arranged at the rear end of the axial steam inlet, the injection zone gradually narrowing;

[0014] A drainage area, arranged at the rear end of the injection area;

[0015] A side steam inlet is arranged on a side of the guide area; the side steam inlet is connected to the outlet of the cooling cavity;

[0016] A mixed flow zone is arranged at the rear end of the guide zone, wherein the mixed flow zone first becomes narrower and then becomes wider; an outlet of the mixed flow zone is connected to a steam inlet of the steam turbine;

[0017] The plant area steam waste heat recovery and utilization system also includes:

[0018] A low-pressure steam inlet valve, disposed between the cooling cavity of the compressor and the side steam inlet of the pressure matcher;

[0019] A high-pressure steam inlet valve, arranged between the steam outlet of the compressor and the axial steam inlet of the pressure matcher;

[0020] A bypass regulating valve, wherein the inlet of the bypass regulating valve is connected between the high-pressure steam inlet valve and the steam outlet of the compressor, and the outlet of the bypass regulating valve is connected between the outlet of the pressure matcher and the steam inlet of the steam turbine.

[0021] Furthermore, the system further comprises:

[0022] A negative pressure condenser connected to the rear of the last-stage impeller of the steam turbine;

[0023] The heat exchange tube is arranged in the negative pressure condenser.

[0024] Furthermore, the system further comprises:

[0025] a vacuum pump, wherein an inlet of the vacuum pump is connected to an upper portion of the negative pressure condenser;

[0026] The steam-water mixing heat exchanger has an emptying port at the top, and a water outlet and a water inlet at the bottom. The water inlet is used to receive return water from the user, and the water outlet is connected to the inlet of the heat exchange tube; the outlet of the vacuum pump is connected to the liquid level below the steam-water mixing heat exchanger;

[0027] A circulation pump is connected to the outlet end of the heat exchange tube; the downstream of the circulation pump is the user of hot water.

[0028] Furthermore, the lower part of the negative pressure condenser is communicated with the upper part of the steam-water mixing heat exchanger.

[0029] Furthermore, a water inlet is provided at the lower portion of the steam-water mixing heat exchanger, and the water inlet is connected to a water pump, and the water pump removes excess water in the steam-water mixing heat exchanger.

[0030] Furthermore, the system further comprises:

[0031] The two ends of the heat supplement regulating valve are respectively connected with the outlet of the cooling cavity and the lower part of the steam-water mixing heat exchanger.

[0032] Furthermore, when the system is started, electrical energy is used to drive the generator to rotate, thereby driving the steam turbine and the compressor to rotate.

[0033] The present invention has at least the following beneficial effects:

[0034] 1. Use steam to cool the compressor, thereby reducing the temperature difference between the inside and outside of the compressor, extending the service life of the compressor, and at the same time keeping the operating temperature of the compressor in a range between the internal and external steam temperatures, so that the operation is stable.

[0035] 2. While cooling the compressor, steam can also increase its own temperature, thereby improving the quality of the steam.

[0036] 3. The quality of steam compressed by the compressor is further improved, so that it can drive the steam turbine, which in turn drives the compressor to operate and drives the generator to generate electricity and output electrical energy, breaking the limitations of the utilization of low-grade thermal energy.

[0037] 4. Convert part of the high-temperature and high-pressure steam into medium-temperature and medium-pressure steam through the pressure matcher and improve the quality of part of the medium-temperature and low-pressure steam. By controlling the opening of the bypass regulating valve, the mixing ratio of high-quality steam and medium-temperature and pressure steam is controlled, thereby controlling the steam inlet temperature and pressure of the steam turbine.

[0038] 5. The last stage impeller of the steam turbine is connected to a negative pressure condenser, which makes the rear end of the last stage impeller negative pressure. Under the premise of a certain inlet pressure of the steam turbine, the inlet and exhaust pressure difference of the steam turbine is increased, so that more steam can be used to drive the operation of the steam turbine. The condensation temperature of steam is reduced under negative pressure, which prevents the steam near the last stage impeller of the steam turbine from condensing into water and causing impact on the steam turbine.

[0039] 6. The water obtained by condensation is used to provide heating for users. At the same time, the condensed water is used to absorb the heat released by condensation, further increasing the temperature of hot water and improving the utilization rate of waste heat.

[0040] 7. Use the heat supply regulating valve to control the appropriate amount of medium-temperature low-pressure steam to supply heat to the condensed water, thereby ensuring that users can always get enough hot water. When the demand for hot water is reduced or even non-existent, the negative pressure condenser can be directly cooled by water supply, and the supplementary water can be directly used for boiler water supply without wasting heat. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a schematic diagram of a plant steam waste heat recovery and utilization system according to an embodiment of the present invention;

[0042] Figure 2 Schematic diagram of a pressure matcher according to an embodiment of the present invention.

[0043] In the figure: 010-steam turbine, 020-generator, 030-compressor, 031-cooling cavity, 040-steam pipe, 050-pressure matcher, 051-axial steam inlet, 052-injection area, 053-diversion area, 054-side steam inlet, 055-mixing flow area, 060-low-pressure steam inlet valve, 070-high-pressure steam inlet valve, 080-bypass regulating valve, 090-negative pressure condenser, 100-heat exchange tube, 110-vacuum pump, 120-steam-water mixing heat exchanger, 130-circulating pump, 140-water supply pump, 150-heat supplement regulating valve, 160-user. DETAILED DESCRIPTION

[0044] The following specific embodiments illustrate the implementation of the present invention, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Although the description of the present invention will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this invention are limited to this implementation. On the contrary, the purpose of introducing the invention in conjunction with the implementation is to cover other options or modifications that may extend based on the claims of the present invention. In order to provide a deep understanding of the present invention, the following description will include many specific details. The present invention can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present invention, some specific details will be omitted in the description. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0045] It should be noted that in this specification, 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 and explained in the subsequent drawings.

[0046] In the description of this embodiment, it should be noted that the terms "upper", "lower", "inner", "bottom", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is usually placed when used. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0047] In the description of this embodiment, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this embodiment can be understood according to specific circumstances.

[0048] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0049] Reference Figure 1 The embodiment of the present invention discloses a plant steam waste heat recovery and utilization system, including a steam turbine 010, a generator 020 and a compressor 030 coaxially connected to the steam turbine 010; and a pressure matching device 050, referring to Figure 2 The pressure matcher 050 includes an axial steam inlet 051, the rear end of the axial steam inlet 051 is a gradually narrowing injection zone 052, the rear end of the injection zone 052 is a guide zone 053, and the two sides of the guide zone 053 are provided with side steam inlets 054. The rear end of the guide zone 053 is a mixing zone 055, and the mixing zone 055 first becomes narrower and then becomes wider. High-pressure steam enters from the axial steam inlet 051, and the pressure is converted into flow velocity when flowing through the injection zone 052, and the flow velocity increases, and then enters the guide zone 053. In the guide zone 053, the high-speed steam introduces the low-pressure steam introduced from the side steam inlet 054 into the mixing zone 055 for mixing, and the steam with medium pressure and flow velocity is formed after mixing.

[0050] The compressor 030 has a cooling cavity 031. In the cooling cavity 031 of the conventional compressor 030, cooling water or cooling oil flows. However, the compressor 030 of the present invention is used to compress steam, which has a relatively high temperature and is not easy to be directly cooled by water or oil. Therefore, steam cooling is adopted to reduce the temperature difference between the inside and outside of the compressor 030, thereby extending the service life of the compressor 030. At the same time, the operating temperature of the compressor 030 is maintained in a range between the internal and external steam temperatures, so that the operation is stable.

[0051] The steam pipe 040 of the waste heat steam is connected to the inlet of the cooling cavity 031 of the compressor 030. The downstream of the outlet of the cooling cavity 031 is divided into three paths. The first path is connected to the steam inlet of the compressor 030, the second path is connected to the side steam inlet 054 of the pressure matcher 050, and is provided with a low-pressure steam inlet valve 060. The third path is connected to the bottom of the steam-water mixing heat exchanger 120 and is provided with a supplementary heat regulating valve 150. The steam outlet of the compressor 030 is connected to the axial steam inlet 051 of the pressure matcher 050, and a high-pressure steam inlet valve 070 is provided in the middle. The outlet of the mixed flow area 055 of the pressure matcher 050 is connected to the steam inlet of the steam turbine 010. A bypass regulating valve 080 is connected in parallel with the pressure matcher 050. The inlet of the bypass regulating valve 080 is connected between the high-pressure steam inlet valve 070 and the steam outlet of the compressor 030, and the outlet is connected between the outlet of the pressure matcher 050 and the steam inlet of the steam turbine 010. High-pressure steam is output from the steam outlet of the compressor 030, flows through the pressure matcher 050 or the bypass regulating valve 080, and then enters the steam turbine 010, driving the steam turbine 010 to operate. The steam turbine 010 in turn drives the compressor 030 to rotate, and at the same time drives the generator 020 to generate electricity. The negative pressure condenser 090 is connected to the back of the last stage impeller of the steam turbine 010. The negative pressure condenser 090 is provided with a heat exchange pipe 100, and the upper part is used to extract steam to the outside through the vacuum pump 110, and the upper part is also provided with a water replenishment port. The steam in the negative pressure condenser 090 is condensed in large quantities under the cooling effect of the heat exchange pipe 100, and the vacuum pump 110 is used to extract steam, so that the negative pressure condenser 090 maintains a large negative pressure. The outlet of the vacuum pump 110 is connected to the liquid level below the steam-water mixing heat exchanger 120. The lower part of the negative pressure condenser 090 is connected to the upper part of the steam-water mixing heat exchanger 120. The top of the steam-water mixing heat exchanger 120 is provided with an emptying port, and the lower part is provided with a water outlet and a water inlet, respectively. The water outlet is connected to the inlet of the heat exchange tube 100 in the negative pressure condenser 090. The outlet of the heat exchange tube 100 is connected to a circulating pump 130 for supplying hot water to the user 160. The return water of the user 160 flows back to the steam-water mixing heat exchanger 120 through the water inlet of the steam-water mixing heat exchanger 120. The lower part of the steam-water mixing heat exchanger 120 is also provided with a water inlet, and the water inlet is connected to a water pump 140.

[0052] The operation method of the present invention is as follows:

[0053] The low-grade steam with waste heat flows through the cooling chamber 031 of the compressor 030, cooling the compressor 030 while increasing the steam temperature. The steam with a higher temperature is divided into three paths after being output from the cooling chamber 031, one of which is compressed by the compressor 030 to form high-temperature and high-pressure high-grade steam. The high-grade steam can directly enter the steam turbine 010 through the bypass regulating valve 080 to drive the steam turbine 010 to operate, or it can first flow through the pressure matcher 050 and mix with the steam output from the cooling chamber 031 to form steam with medium temperature and pressure. The steam with medium temperature and pressure can directly drive the steam turbine 010 to operate, or it can be mixed with the high-temperature and high-pressure steam flowing through the bypass regulating valve 080 to drive the steam turbine 010 to operate. When the temperature and pressure of the waste heat steam are low, the high-pressure steam inlet valve 070 and the low-pressure steam inlet valve 060 are closed, and the steam is directly driven to rotate the steam turbine 010 after being output from the compressor 030 to avoid further reducing the steam quality. When the temperature and pressure of the waste heat steam are high, the temperature and pressure of the high-grade steam output by the compressor 030 exceed the rated steam inlet temperature and pressure of the steam turbine 010, then the high-pressure steam inlet valve 070 and the low-pressure steam inlet valve 060 are opened, and the opening of the bypass regulating valve 080 is controlled to control the mixing of part of the high-grade steam with the steam of medium temperature and pressure, thereby controlling the steam inlet temperature and pressure of the steam turbine 010. The steam turbine 010 drives the compressor 030 to rotate, and drives the generator 020 to generate electricity at the same time. The negative pressure condenser 090 is connected to the rear of the last-stage impeller of the steam turbine 010, so that the rear end of the last-stage impeller is negative pressure. Under the premise of a certain steam inlet pressure of the steam turbine 010, the steam inlet and exhaust pressure difference of the steam turbine 010 is increased, so that more steam can be used to drive the operation of the steam turbine 010. At the same time, the condensation temperature of the steam under negative pressure is reduced, which prevents the steam near the last-stage impeller of the steam turbine 010 from condensing into water and causing impact on the steam turbine 010. The condensed water in the negative pressure condenser 090 flows freely from the bottom into the steam-water mixing heat exchanger 120, and mixes with the uncondensed steam in the steam-water mixing heat exchanger 120, thereby absorbing most of the steam and the heat of the steam, and a very small amount of low-temperature steam and gas impurities are discharged from the exhaust port. Under the action of the circulating pump 130, hot water is extracted from the steam-water mixing heat exchanger 120, flows through the heat exchange pipe 100 in the negative pressure condenser 090, exchanges heat with the steam discharged from the turbine 010, and then is used by the user 160. The return water after use by the user 160 returns to the steam-water mixing heat exchanger 120. When the water demand of the user 160 is large, or the waste heat steam in the plant area is small, and the steam heat discharged from the turbine 010 cannot meet the heating demand of the steam-water mixing heat exchanger 120, the supplementary heat regulating valve 150 is opened, and part of the steam from the cooling cavity 031 of the compressor 030 is directly passed into the steam-water mixing heat exchanger 120 to heat the water. As the steam continues to condense, the liquid level in the steam-water mixing heat exchanger 120 continues to rise. When the liquid level reaches the set value, the water supply pump 140 is started to provide water for the boiler to maintain the liquid level in the steam-water mixing heat exchanger 120 within a reasonable range.When the demand of hot water user 160 decreases or even disappears, supplementary water is used to directly cool the negative pressure condenser 090, and the supplementary water is directly used for boiler water supply without wasting heat.

[0054] When the system is started, since the steam turbine 010 does not rotate at the beginning and cannot drive the compressor 030, the reverse power transmission method is adopted at this time, using the electric energy in the field to reversely drive the generator 020 to rotate, and the generator 020 drives the steam turbine 010 and the compressor 030 to rotate, thereby providing initial steam for the steam turbine 010. When the steam provided to the steam turbine 010 is sufficient to drive the compressor 030 to operate, the generator 020 switches to the power generation mode.

[0055] The above only describes in detail the preferred embodiments of the present invention, which is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A plant steam waste heat recovery and utilization system, characterized in that: include: Steam turbine; a generator, coaxially connected to the steam turbine; A compressor is coaxially connected to the steam turbine; the compressor is provided with a cooling cavity, and the steam inlet of the compressor is connected to the outlet of the cooling cavity; a steam pipe, for supplying steam with waste heat, connected to the cooling cavity inlet of the compressor; A negative pressure condenser connected to the rear of the last-stage impeller of the steam turbine; A heat exchange tube is arranged in the negative pressure condenser; Pressure matching device; The pressure matcher comprises: an axial steam inlet, connected to a steam outlet of the compressor; An injection zone, arranged at the rear end of the axial steam inlet, the injection zone gradually narrowing; A drainage area, arranged at the rear end of the injection area; A side steam inlet is arranged on a side of the guide area; the side steam inlet is connected to the outlet of the cooling cavity; A mixed flow zone is arranged at the rear end of the guide zone, wherein the mixed flow zone first becomes narrower and then becomes wider; an outlet of the mixed flow zone is connected to a steam inlet of the steam turbine; The plant area steam waste heat recovery and utilization system also includes: A low-pressure steam inlet valve, disposed between the cooling cavity of the compressor and the side steam inlet of the pressure matcher; A high-pressure steam inlet valve, arranged between the steam outlet of the compressor and the axial steam inlet of the pressure matcher; A bypass regulating valve, wherein the inlet of the bypass regulating valve is connected between the high-pressure steam inlet valve and the steam outlet of the compressor, and the outlet of the bypass regulating valve is connected between the outlet of the pressure matching device and the steam inlet of the steam turbine; a vacuum pump, wherein an inlet of the vacuum pump is connected to an upper portion of the negative pressure condenser; The steam-water mixing heat exchanger has an emptying port at the top, and a water outlet and a water inlet at the bottom. The water inlet is used to receive return water from the user, and the water outlet is connected to the inlet of the heat exchange tube; the outlet of the vacuum pump is connected to the liquid level below the steam-water mixing heat exchanger; A circulation pump is connected to the outlet end of the heat exchange tube; the downstream of the circulation pump is a user of hot water; The two ends of the heat supplement regulating valve are respectively connected with the outlet of the cooling cavity and the lower part of the steam-water mixing heat exchanger.

2. The plant steam waste heat recovery and utilization system according to claim 1 is characterized in that: The lower part of the negative pressure condenser is communicated with the upper part of the steam-water mixing heat exchanger.

3. The plant steam waste heat recovery and utilization system according to claim 1 is characterized in that: A water inlet is provided at the lower part of the steam-water mixing heat exchanger, and the water inlet is connected to a water pump, and the water pump pumps away excess water in the steam-water mixing heat exchanger.

4. The plant steam waste heat recovery and utilization system according to claim 1 is characterized in that: When the system is started, electrical energy is used to rotate the generator, which in turn drives the steam turbine and the compressor.

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