Coal-fired cogeneration unit

Abstract

The invention discloses a coal-fired heat and power cogeneration unit. The coal-fired heat and power cogeneration unit comprises a steam turbine, a high-pressure regenerative heater and an absorption heat pump. The turbine has a high-pressure cylinder; the high-pressure regenerative heater is provided with a steam extraction inlet and a drain water outlet, the steam extraction inlet communicates with the high-pressure cylinder and is used for extracting steam from the steam turbine, and the drain water outlet is used for discharging drain water formed after steam condensation; the drain outlet communicates with the absorption heat pump, and the drain serves as a driving heat source of the absorption heat pump. According to the coal-fired combined heat and power unit, the irreversible loss in the heat transfer process of the absorption heat pump can be reduced, so that the overall energy efficiency is improved, and the heat supply efficiency can also be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of combined heat and power units, and more particularly to a coal-fired combined heat and power unit. Background Art

[0002] With the growth of energy consumption, coal-fired combined heat and power units have become an important way to improve the overall energy utilization efficiency because they can generate electricity and heat simultaneously. However, there are significant energy waste problems in conventional coal-fired combined heat and power units. An absorption heat pump for heating is often provided in a coal-fired combined heat and power unit. The way that the absorption heat pump directly uses the extraction steam of the steam turbine to heat the return water of the heat network not only causes the problem of mismatched energy grades, but also increases the irreversible loss and reduces the overall energy efficiency of the system. In order to address these problems, the absorption heat pumps in the prior art attempt to use the drain water of the low-pressure regenerative heater as the driving heat source, but the energy conversion efficiency of the absorption heat pump in this solution is low, which affects the heating efficiency. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. For this purpose, the present invention provides a coal-fired combined heat and power unit, which can reduce the irreversible loss in the heat transfer process of the absorption heat pump, thereby improving the overall energy efficiency, and can also improve the heating efficiency.

[0004] The coal-fired combined heat and power unit according to an embodiment of the present invention includes: a steam turbine, a high-pressure regenerative heater, and an absorption heat pump. The steam turbine has a high-pressure cylinder; the high-pressure regenerative heater has a steam extraction inlet and a drain outlet. The steam extraction inlet is connected to the high-pressure cylinder for extracting steam from the steam turbine, and the drain outlet is used for discharging the drain water formed after the steam condenses; the drain outlet is connected to the absorption heat pump, and the drain water serves as the driving heat source of the absorption heat pump.

[0005] In the coal-fired combined heat and power unit according to an embodiment of the present invention, by making the high-pressure regenerative heater extract steam from the high-pressure cylinder of the steam turbine and connecting the drain outlet of the high-pressure regenerative heater to the absorption heat pump, the drain water of the high-pressure regenerative heater serves as the driving heat source of the absorption heat pump, eliminating the need for the absorption heat pump to separately extract steam from the steam turbine, which is beneficial to increasing the power generation of the coal-fired combined heat and power unit. While improving the utilization rate of the waste heat of the drain water of the high-pressure regenerative heater, it can also reduce the irreversible loss in the heat transfer process, and thus is beneficial to improving the overall energy efficiency of the coal-fired combined heat and power unit. At the same time, the drain water temperature of the high-pressure regenerative heater is higher than that of the low-pressure regenerative heater, which can improve the energy conversion efficiency of the absorption heat pump, thereby improving the heating efficiency of the coal-fired combined heat and power unit.

[0006] According to some embodiments of the present invention, a feed water pipe is provided inside the high-pressure regenerative heater. The absorption heat pump has a drain outlet for discharging the drain water. The coal-fired cogeneration unit further includes: a deaerator and a boiler. The drain outlet is communicated with the deaerator, and a water tank is fixedly arranged at the bottom of the deaerator; the feed water pipe is respectively communicated with the boiler and the water tank.

[0007] In some embodiments of the present invention, the drain outlet is connected to the deaerator through a first drain pipe, and the first drain pipe is threadedly connected to the absorption heat pump and the deaerator respectively.

[0008] In some embodiments of the present invention, the deaerator is communicated with the steam turbine and extracts steam from the steam turbine.

[0009] In some embodiments of the present invention, the steam turbine has a low-pressure cylinder, the low-pressure cylinder is communicated with the high-pressure cylinder and is located downstream of the high-pressure cylinder. The low-pressure cylinder has an exhaust port. The coal-fired cogeneration unit further includes a condenser and a low-pressure regenerative heater. The condenser is communicated with the exhaust port, and a hot well is fixedly arranged at the bottom of the condenser; the low-pressure regenerative heater is communicated with the low-pressure cylinder and extracts steam from the low-pressure cylinder. A return water pipe is provided inside the low-pressure regenerative heater, and the return water pipe is respectively communicated with the deaerator and the hot well.

[0010] According to some embodiments of the present invention, the absorption heat pump is a lithium bromide absorption heat pump, and the absorption heat pump includes a generator, and the drain outlet is communicated with the generator.

[0011] According to some embodiments of the present invention, the drain outlet is connected to the absorption heat pump through a second drain pipe, and the second drain pipe is threadedly connected to the high-pressure regenerative heater and the absorption heat pump respectively.

[0012] According to some embodiments of the present invention, a heat exchanger is fixedly connected to the top of the absorption heat pump, and the heat exchanger is connected to the heat network return water system.

[0013] According to some embodiments of the present invention, a first controller is provided on the high-pressure regenerative heater for monitoring and controlling the flow rate of the steam entering the extraction inlet from the high-pressure cylinder; and / or, a second controller is provided on the absorption heat pump for monitoring and controlling the flow rate of the drain water; and / or, a maintenance door is provided on the absorption heat pump.

[0014] According to some embodiments of the present invention, there are multiple high-pressure regenerative heaters, and there are multiple absorption heat pumps corresponding to the multiple high-pressure regenerative heaters.

[0015] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned by practice of the present invention. Description of the Drawings

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0017] Figure 1 is a schematic diagram of a coal-fired cogeneration unit according to an embodiment of the present invention.

[0018] Reference Signs:

[0019] 100, coal-fired cogeneration unit;

[0020] 1, high-pressure regenerative heater; 11, extraction steam inlet; 12, drain outlet; 13, first controller;

[0021] 2, absorption heat pump; 21, drain outlet; 22, second controller; 23, maintenance door;

[0022] 3, deaerator; 31, water tank; 32, third controller;

[0023] 4, heat exchanger;

[0024] 51, first drain pipe; 52, second drain pipe. Detailed Description of the Embodiments

[0025] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

[0026] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention. In addition, features defined as "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0027] In the description of the present invention, it should be noted that, unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" 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 an indirect connection through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] Reference is made below to Figure 1 describe the coal-fired combined heat and power unit 100 according to an embodiment of the present invention.

[0029] As Figure 1 shown, the coal-fired combined heat and power unit 100 according to an embodiment of the present invention includes a steam turbine, a high-pressure regenerative heater 1, and an absorption heat pump 2.

[0030] Specifically, as Figure 1 shown, the steam turbine has a high-pressure cylinder. The high-pressure regenerative heater 1 has a steam extraction inlet 11 and a drain outlet 12. The steam extraction inlet 11 is in communication with the high-pressure cylinder for extracting steam from the steam turbine, and the drain outlet 12 is used for discharging the drain formed after the steam condenses. The drain outlet 12 is in communication with the absorption heat pump 2, and the drain serves as the driving heat source of the absorption heat pump 2.

[0031] The coal-fired combined heat and power unit 100 is provided with a boiler. The boiler burns coal to generate high-temperature and high-pressure steam and supplies it to the steam turbine. The steam turbine converts the thermal energy of the steam into mechanical energy and then drives a generator to generate electricity, thereby realizing the power generation function of the coal-fired combined heat and power unit 100.

[0032] The high-pressure regenerative heater 1 is used to increase the temperature of the boiler feed water. The steam extraction inlet 11 of the high-pressure regenerative heater 1 is in communication with the high-pressure cylinder of the steam turbine, and high-temperature and high-pressure steam can be extracted from the high-pressure cylinder and used to preheat the boiler feed water, thereby increasing the feed water temperature, reducing the boiler fuel consumption, and improving the thermal efficiency.

[0033] The high-temperature and high-pressure steam extracted from the high-pressure cylinder is condensed into a drain after heat exchange with the boiler feed water in the high-pressure regenerative heater 1 and discharged from the drain outlet 12, and then enters the absorption heat pump 2 as its driving heat source, enabling the absorption heat pump 2 to recover low-grade waste heat and output high-grade thermal energy to heat the heating circulating water, thereby realizing the heating function of the coal-fired combined heat and power unit 100. Without the absorption heat pump 2 extracting steam from the steam turbine, the effective recovery of the drain waste heat of the high-pressure regenerative heater 1 is realized, the utilization rate of the drain waste heat of the high-pressure regenerative heater 1 is improved, and it is beneficial to increase the power generation power of the coal-fired combined heat and power unit 100.

[0034] Compared with the traditional method of using the extraction steam of the steam turbine as the driving heat source of the absorption heat pump 2 to directly heat the return water of the heat network, using the drain water of the high-pressure regenerative heater 1 as the driving heat source of the absorption heat pump 2 can reduce the irreversible loss in the heat transfer process, which is conducive to improving the overall energy efficiency of the coal-fired cogeneration unit 100.

[0035] Compared with the method of using the drain water of the low-pressure regenerative heater to drive the absorption heat pump 2, the drain water temperature of the high-pressure regenerative heater 1 is higher and the heat supply speed is faster. The high-pressure regenerative heater 1 extracts the steam from the high-pressure cylinder, and its drain water temperature is relatively high, that is, the driving heat source temperature of the absorption heat pump 2 is higher, and the driving temperature difference of the absorption heat pump 2 is larger, which can improve the energy conversion efficiency of the absorption heat pump 2 and give full play to the efficiency of the absorption heat pump 2, thereby improving the heat supply efficiency of the coal-fired cogeneration unit 100. Moreover, the absorption heat pump 2 using the drain water of the high-pressure regenerative heater 1 as the driving heat source can directly meet the heat supply demand without secondary heating, thus reducing the energy consumption of secondary heating.

[0036] For the coal-fired cogeneration unit 100 according to the embodiment of the present invention, by making the high-pressure regenerative heater 1 extract steam from the high-pressure cylinder of the steam turbine and connecting the drain outlet 12 of the high-pressure regenerative heater 1 to the absorption heat pump 2, the drain water of the high-pressure regenerative heater 1 is used as the driving heat source of the absorption heat pump 2, without the absorption heat pump 2 extracting steam from the steam turbine separately, which is conducive to improving the power generation power of the coal-fired cogeneration unit 100. While improving the utilization rate of the waste heat of the drain water of the high-pressure regenerative heater 1, it can also reduce the irreversible loss in the heat transfer process, which is conducive to improving the overall energy efficiency of the coal-fired cogeneration unit 100. At the same time, the drain water temperature of the high-pressure regenerative heater 1 is higher than that of the low-pressure regenerative heater, which can improve the energy conversion efficiency of the absorption heat pump 2, thereby improving the heat supply efficiency of the coal-fired cogeneration unit 100.

[0037] In some embodiments of the present invention, as Figure 1 shown, a water supply pipe is provided in the high-pressure regenerative heater 1. The absorption heat pump 2 has a drain outlet 21 for discharging drain water. The coal-fired cogeneration unit 100 further includes: a deaerator 3 and a boiler. The drain outlet 21 is communicated with the deaerator 3. A water tank 31 is fixedly arranged at the bottom of the deaerator 3. The water supply pipe is respectively communicated with the boiler and the water tank 31.

[0038] Thus, when the drain water of the high-pressure regenerative heater 1 enters the absorption heat pump 2 for heat exchange and then flows out from the drain outlet 21, it enters the deaerator 3. The deaerator 3 can remove the dissolved oxygen in the boiler feed water to prevent equipment corrosion. After the drain water enters the deaerator 3, it enters the water tank 31 and returns to the boiler through the feed water pipe. The boiler burns coal to generate high-temperature and high-pressure steam and then supplies it to the steam turbine, thus forming a thermal cycle. The effective recovery of the waste heat of the drain water of the high-pressure regenerative heater 1 is realized, the utilization rate of the waste heat of the drain water of the high-pressure regenerative heater 1 is improved, which is beneficial to improving the power generation power of the coal-fired cogeneration unit 100. It not only optimizes the thermal cycle process but also ensures the overall stable operation of the coal-fired cogeneration unit 100.

[0039] In some embodiments of the present invention, as Figure 1 shown, the drain outlet 21 is connected to the deaerator 3 through the first drain pipe 51, and the first drain pipe 51 is threadedly connected to the absorption heat pump 2 and the deaerator 3 respectively. In this way, the detachability of the first drain pipe 51 can be ensured, which can not only ensure the connection stability between the first drain pipe 51 and the absorption heat pump 2 and the deaerator 3 but also facilitate disassembly, which is convenient for subsequent maintenance and repair.

[0040] In some embodiments of the present invention, the deaerator 3 is communicated with the steam turbine and extracts steam from the steam turbine. In this way, the deaeration condition can be ensured. To ensure the deaeration effect of the deaerator 3, the extraction steam volume of the deaerator 3 increases. However, compared with the absorption heat pump 2 directly extracting steam to heat the return water of the heat network, the extraction steam volume of the steam turbine can be reduced, which is beneficial to improving the power generation power of the coal-fired cogeneration unit 100.

[0041] In some embodiments of the present invention, the steam turbine has a low-pressure cylinder. The low-pressure cylinder is communicated with the high-pressure cylinder and is located downstream of the high-pressure cylinder. The low-pressure cylinder has an exhaust port. The coal-fired cogeneration unit 100 further includes a condenser and a low-pressure regenerative heater. The condenser is communicated with the exhaust port, and a hot well is fixedly arranged at the bottom of the condenser; the low-pressure regenerative heater is communicated with the low-pressure cylinder and extracts steam from the low-pressure cylinder. A return water pipe is arranged in the low-pressure regenerative heater, and the return water pipe is communicated with the deaerator 3 and the hot well respectively.

[0042] The boiler burns coal to generate high-temperature and high-pressure steam and supplies it to the steam turbine. The steam flows through the high-pressure cylinder, the intermediate-pressure cylinder and the low-pressure cylinder in sequence, and converts the thermal energy into mechanical energy to drive the generator to generate electricity. The steam after doing work forms exhaust steam and enters the condenser from the exhaust port for condensation, and is condensed into boiler feed water and stored in the hot well. The boiler feed water in the hot well flows from the return water pipe to the deaerator 3, is preheated by the steam extracted by the steam turbine in the low-pressure regenerative heater, and finally returns to the boiler, forming a thermal cycle. It can reduce the cold source loss and improve the overall energy efficiency of the coal-fired cogeneration unit 100.

[0043] In some embodiments of the present invention, the absorption heat pump 2 is a lithium bromide absorption heat pump 2. The absorption heat pump 2 includes a generator, and the drain outlet 12 is communicated with the generator. Specifically, the absorption heat pump 2 includes a generator, a condenser, an evaporator, and an absorber. The generator uses the drain water of the high-pressure regenerative heater 1 as a driving heat source to heat the dilute lithium bromide solution, releasing water vapor and forming a concentrated lithium bromide solution. The condenser condenses the water vapor coming from the generator into liquid water and releases heat to the heat supply pipe network. The evaporator uses low-grade waste heat (such as the circulating water of the condenser) to heat the liquid water, evaporating it into low-temperature water vapor. The concentrated lithium bromide solution in the absorber absorbs the low-temperature water vapor coming from the evaporator, releasing the absorption heat to the heat supply pipe network. The absorption heat pump 2 is also provided with a solution pump to pressurize and transport the dilute solution in the absorber back to the generator to maintain the cycle. Thus, low-grade waste heat can be recovered and high-grade thermal energy can be output, ensuring the heating function and heating efficiency of the coal-fired cogeneration unit 100.

[0044] In some embodiments of the present invention, as Figure 1 shown, the drain outlet 12 is connected to the absorption heat pump 2 through a second drain pipe 52. The second drain pipe 52 is threadedly connected to the high-pressure regenerative heater 1 and the absorption heat pump 2 respectively. In this way, the detachability of the second drain pipe 52 can be ensured, which can not only ensure the connection stability between the second drain pipe 52 and the high-pressure regenerative heater 1 and the absorption heat pump 2, but also facilitate disassembly, which is convenient for subsequent maintenance and repair.

[0045] In some embodiments of the present invention, as Figure 1 shown, a heat exchanger 4 is fixedly connected to the top of the absorption heat pump 2. The heat exchanger 4 is connected to the heat network return water system. Heat exchange between the absorption heat pump 2 and the heat network return water system can be realized, improving the heat exchange effect, and further ensuring the heating function and heating efficiency of the coal-fired cogeneration unit 100.

[0046] In some embodiments of the present invention, as Figure 1 shown, a first controller 13 is provided on the high-pressure regenerative heater 1, which is used to monitor and control the flow rate of the steam entering the extraction inlet 11 from the high-pressure cylinder, so as to control the temperature of the boiler feed water heated by the high-pressure regenerative heater 1 and the drain water temperature, which is beneficial to optimizing the thermal cycle and ensuring the stable operation of the overall coal-fired cogeneration unit 100.

[0047] In some embodiments of the present invention, as Figure 1 shown, a second controller 22 is provided on the absorption heat pump 2, which is used to monitor and control the flow rate of the drain water. Thus, the heating temperature and heating efficiency of the absorption heat pump 2 can be controlled according to actual needs, which is beneficial to optimizing the thermal cycle and ensuring the stable operation of the overall coal-fired cogeneration unit 100.

[0048] In some embodiments of the present invention, as Figure 1As shown, a third controller 32 is provided on the deaerator 3 for monitoring and controlling the flow rate of steam extracted from the steam turbine and the flow rate of boiler feed water. Thus, the circulation speed and efficiency of steam and feed water can be controlled according to actual requirements, which is beneficial to optimizing the thermal cycle and ensuring the stable operation of the entire coal-fired cogeneration unit 100.

[0049] In some embodiments of the present invention, as Figure 1 shown, a maintenance door 23 is provided on the absorption heat pump 2, which is convenient for the maintenance and repair of the absorption heat pump 2.

[0050] In some embodiments of the present invention, there are multiple high-pressure regenerative heaters 1, and there are multiple absorption heat pumps 2 corresponding to the multiple high-pressure regenerative heaters 1. The driving heat sources of the multiple absorption heat pumps 2 come from the drain water of each stage of the high-pressure regenerative heaters 1, which can further improve the utilization rate of the waste heat of the drain water of the high-pressure regenerative heaters 1 and enhance the power generation power, heat supply efficiency and overall energy efficiency of the coal-fired cogeneration unit 100.

[0051] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0052] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and purposes of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A coal-fired combined heat and power unit, characterized in that: include: A steam turbine having a high-pressure cylinder; a high-pressure regenerative heater, the high-pressure regenerative heater having a steam extraction inlet and a drain outlet, the steam extraction inlet being in communication with the high-pressure cylinder and used for extracting steam from the steam turbine, and the drain outlet being used for discharging drain formed after the steam is condensed; Absorption heat pump, the drain outlet is connected to the absorption heat pump, and the drain serves as a driving heat source for the absorption heat pump.

2. The coal-fired combined heat and power unit according to claim 1, characterized in that: The high-pressure regenerative heater is provided with a water supply pipe, the absorption heat pump has a drain outlet for draining the drain, and the coal-fired cogeneration unit further includes: A deaerator, the drain outlet is connected to the deaerator, and a water tank is fixedly arranged at the bottom of the deaerator; The boiler and the water supply pipe are respectively connected with the boiler and the water tank.

3. The coal-fired combined heat and power unit according to claim 2, characterized in that: The drain outlet is connected to the deaerator through a first drain pipe, and the first drain pipe is threadedly connected to the absorption heat pump and the deaerator respectively.

4. The coal-fired combined heat and power unit according to claim 2, characterized in that: The deaerator is in communication with the steam turbine and extracts steam from the steam turbine.

5. The coal-fired combined heat and power unit according to claim 2, characterized in that: The steam turbine has a low-pressure cylinder, which is connected to the high-pressure cylinder and is located downstream of the high-pressure cylinder, and the low-pressure cylinder has a steam exhaust port. The coal-fired cogeneration unit also includes: A condenser, the condenser is connected to the exhaust port, and a hot well is fixedly arranged at the bottom of the condenser; A low-pressure heat recovery heater is connected to the low-pressure cylinder and extracts steam from the low-pressure cylinder. A return water pipe is provided in the low-pressure heat recovery heater, and the return water pipe is connected to the deaerator and the hot well respectively.

6. The coal-fired combined heat and power unit according to claim 1, characterized in that: The absorption heat pump is a lithium bromide absorption heat pump, and the absorption heat pump comprises a generator, and the drain outlet is communicated with the generator.

7. The coal-fired combined heat and power unit according to claim 1, characterized in that: The drain outlet is connected to the absorption heat pump through a second drain pipe, and the second drain pipe is threadedly connected to the high-pressure regenerative heater and the absorption heat pump respectively.

8. The coal-fired combined heat and power unit according to claim 1, characterized in that: A heat exchanger is fixedly connected to the top of the absorption heat pump, and the heat exchanger is connected to a heat network return water system.

9. The coal-fired combined heat and power unit according to claim 1, characterized in that: The high-pressure regenerative heater is provided with a first controller for monitoring and controlling the flow rate of steam entering the steam extraction inlet from the high-pressure cylinder; And / or, the absorption heat pump is provided with a second controller for monitoring and controlling the flow rate of the drain; And / or, the absorption heat pump is provided with an inspection door.

10. The coal-fired combined heat and power unit according to claim 1, characterized in that: The number of the high-pressure regenerative heaters is plural, and the number of the absorption heat pumps is plural corresponding to the number of the high-pressure regenerative heaters.

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