CN219654753U

CN219654753U - Steam waste heat utilization system behind steam turbine low pressure jar

Info

Publication number: CN219654753U
Application number: CN202320861213.8U
Authority: CN
Inventors: 宋端阳; 范春学; 采有林; 田建明; 李计珍; 周广权; 王勇; 姚海宙; 姜岸
Original assignee: Beijing SPC Environment Protection Tech Co Ltd
Current assignee: Beijing SPC Environment Protection Tech Co Ltd
Priority date: 2023-04-18
Filing date: 2023-04-18
Publication date: 2023-09-08
Anticipated expiration: 2033-04-18

Abstract

The utility model relates to a steam waste heat utilization system behind a low-pressure cylinder of a steam turbine, which comprises a condenser, a liquid expander, an evaporator and a compressor, wherein a steam outlet of the low-pressure cylinder of the steam turbine is connected with a shell side inlet of the evaporator, a shell side outlet of the evaporator is connected with the shell side inlet of the condenser through a pipeline by a condensate pressurizing and conveying system, a shell side outlet of the condenser is connected with an economizer water inlet of a boiler through a pipeline, a high-temperature high-pressure steam outlet of the boiler is connected with a steam inlet of the steam turbine through a pipeline, and a tube side outlet of the evaporator, an inlet and an outlet of the compressor, a tube side inlet and a tube side outlet of the condenser, an inlet and an outlet of the liquid expander and a tube side inlet of the evaporator are sequentially connected in series through pipelines. The advantages are that: the steam liquefying process after the low-pressure cylinder of the steam turbine is realized, so that the evaporation water loss during water cooling of the traditional cooling tower is avoided, and meanwhile, the heat is recovered. The multifunctional water-saving device realizes multiple functions of water saving, waste heat utilization, waste heat power generation and the like.

Description

Steam waste heat utilization system behind steam turbine low pressure jar

Technical Field

The utility model relates to the technical field of energy conservation and environmental protection, in particular to a steam turbine low-pressure cylinder rear steam waste heat utilization system.

Background

The conventional steam turbine is a device for converting internal energy into electric energy by pushing a turbine rotor with high-temperature steam from a boiler. Since the temperature and pressure are corresponding in the vessel in the saturated state, for the steam turbine, the exhaust temperature of the steam turbine is corresponding to the exhaust gas, that is, the lower the exhaust pressure (the higher the vacuum), the lower the exhaust temperature. The exhaust temperature of the turbine is low in the case where the exhaust temperature of the turbine is high in vacuum. However, the exhaust temperature is preferably not lower than 20 ℃, the temperature is lower than the water carried by the last stage blade, the scouring is large, and the exhaust temperature is low, so that the bearing seat of the steam turbine sinks. Many turbines control the low pressure cylinder exhaust temperature to around 65 ℃. The low-temperature steam needs to be condensed into liquid water and enters the boiler again to produce steam, so that an air cooling island or a cooling tower (water cooling) is generally adopted for indirect cooling, and the heat is dissipated. The heat quantity is quite large, and huge energy waste exists, and particularly when the cooling tower is used for cooling, the water resource is consumed relatively along with evaporation of the process water.

Therefore, it is necessary to develop a waste heat utilization system to solve the above technical problems.

Disclosure of Invention

The utility model aims to solve the technical problem of providing a steam turbine low-pressure cylinder rear steam waste heat utilization system, which effectively overcomes the defects of the prior art.

The technical scheme for solving the technical problems is as follows:

a steam waste heat utilization system behind a low-pressure cylinder of a steam turbine comprises a condenser, a liquid expander, an evaporator and a compressor, wherein a low-pressure cylinder steam outlet of the steam turbine is connected with a shell side inlet of the evaporator, a shell side outlet of the evaporator is connected with the shell side inlet of the condenser through a pipeline by a condensate pressurizing and conveying system, a shell side outlet of the condenser is connected with a coal economizer water inlet of a boiler through a pipeline, a high-temperature high-pressure steam outlet of the boiler is connected with a steam inlet of the steam turbine through a pipeline, and a tube side outlet of the evaporator, an inlet and an outlet of the compressor, a tube side inlet and a tube side outlet of the condenser, an inlet and an outlet of the liquid expander and a tube side inlet of the evaporator are sequentially connected in series through pipelines.

On the basis of the technical scheme, the utility model can be improved as follows.

Further, the condensate pressurized conveying system comprises a condensate pump, a deaerator and a water supply pump, wherein the shell side outlet of the evaporator, the inlet and the outlet of the condensate pump, the inlet and the outlet of the deaerator, the inlet and the outlet of the water supply pump and the shell side inlet of the condenser are sequentially connected in series through pipelines.

Further, a gas-liquid separator is arranged between the compressor and the tube side outlet of the evaporator, the inlet of the gas-liquid separator is connected with the tube side outlet of the evaporator through a pipeline, and the gas outlet of the gas-liquid separator is connected with the inlet of the compressor through a pipeline.

Further, the outer surface of the compressor and the outside of the pipeline connecting the compressor and the tube side inlet of the condenser are provided with heat insulation structures.

Further, the outer surface of the liquid expander and the outside of the pipeline connected between the liquid expander and the tube side inlet of the evaporator are respectively provided with a cold insulation structure.

Further, a barometer for monitoring the exhaust pressure of the liquid expander is arranged at the outlet of the liquid expander.

Further, a temperature monitor for monitoring the temperature of the fluid in the evaporator is arranged at the outlet of the tube side of the evaporator.

The beneficial effects of the utility model are as follows: the steam liquefying process after the low-pressure cylinder of the steam turbine is realized, so that the evaporation water loss during water cooling of the traditional cooling tower is avoided, and meanwhile, the heat is recovered. One part is used for primarily heating the circulating water of the low-temperature liquid boiler, and the other part is used for generating power by using a liquid expander, so that multiple functions of water saving, waste heat utilization, waste heat power generation and the like are realized.

Drawings

FIG. 1 is a schematic diagram of a system for utilizing residual heat of steam after a low pressure cylinder of a steam turbine according to the present utility model;

FIG. 2 schematically illustrates a temperature entropy diagram of an embodiment of a system and process for post-low pressure cylinder steam waste heat utilization for a steam turbine in accordance with an embodiment of the present utility model;

FIG. 3 schematically illustrates a pressure enthalpy diagram of an embodiment of a system and process for post-low pressure cylinder steam waste heat utilization for a steam turbine in accordance with an embodiment of the present utility model;

FIG. 4 schematically illustrates a temperature entropy diagram of a conventional heat pump cycle;

fig. 5 schematically shows a pressure enthalpy diagram of a conventional heat pump cycle.

In the drawings, the list of components represented by the various numbers is as follows:

1. a condenser; 2. a liquid expander; 3. an evaporator; 4. a compressor; 5. a condensate pump; 6. a deaerator; 7. and a water supply pump.

Detailed Description

The principles and features of the present utility model are described below with reference to the drawings, the examples are illustrated for the purpose of illustrating the utility model and are not to be construed as limiting the scope of the utility model.

Examples: as shown in fig. 1, the system for utilizing residual heat of low-pressure cylinder post-steam of a steam turbine in this embodiment comprises a condenser 1, a liquid expander 2, an evaporator 3 and a compressor 4, wherein a low-pressure cylinder steam outlet of the steam turbine (denoted by M in the figure) is connected with a shell side inlet of the evaporator 3, a shell side outlet of the evaporator 3 is connected with a shell side inlet of the condenser 1 through a pipeline by a condensate pressurizing and conveying system, a shell side outlet of the condenser 1 is connected with an economizer water inlet of a boiler through a pipeline, a high-temperature high-pressure steam outlet of the boiler is connected with a steam inlet of the steam turbine through a pipeline, and a tube side outlet of the evaporator 3, an inlet and an outlet of the compressor 4, a tube side inlet and a tube side outlet of the condenser 1, an inlet and an outlet of the liquid expander 2 and a tube side inlet of the evaporator 3 are sequentially connected in series through pipelines.

In the use process, low-pressure cylinder outlet steam of a steam turbine of a power plant power generation system firstly enters into a shell side of the evaporator 3, heat is transferred to a low-temperature low-pressure working medium in the tube side, and water vapor is cooled and gradually condensed into liquid water. And then the part of liquid water enters a subsequent condenser 1 after being pressurized by a condensed water pressurizing and conveying system, the low-temperature liquid water runs in the shell pass of the condenser 1, receives heat conducted by a high-temperature circulating working medium in the tube pass, and the liquid water is primarily heated and then enters an economizer of a boiler, so that partial utilization of heat recovered from low-pressure cylinder exhaust is realized.

In this embodiment, according to the thermodynamic cycle: the exhaust of the low-pressure cylinder of the steam turbine is in the evaporator 3, heat is transferred to the thermodynamic cycle working medium in the tube side, the cycle working medium is gradually evaporated from a gas-liquid mixed state into a gas state, the temperature is also slightly increased, but the temperature cannot be higher than the allowable air inlet temperature of the compressor 4. After compression work is done by the compressor 4, the circulating working medium becomes a high-temperature high-pressure gaseous state. Then enters the condenser 1, and the high-temperature and high-pressure circulating working medium transfers heat to the low-temperature liquid water in the shell side in the condenser 1, and is cooled and gradually condensed into liquid. At this time, part of the heat recovered from the turbine low pressure cylinder exhaust gas has been transferred to the boiler circulating water, and part of the heat recovery has been achieved. Then, the low-temperature high-pressure liquid working medium enters the liquid expander 2, and the liquid working medium expands in the liquid expander 2 and pushes the rotor to rotate due to the huge pressure difference between the front and the back, so that the conversion from the internal energy to the electric energy is realized. The thermodynamic cycle has fully utilized the heat recovered from the turbine low pressure cylinder post-exhaust.

In summary, in the steam turbine low pressure cylinder rear steam waste heat utilization system of the embodiment, the steam turbine low pressure cylinder rear steam is liquefied, the process avoids the evaporation water loss during the water cooling of the traditional cooling tower, and simultaneously, the heat is recovered. One part is used for primarily heating the circulating water of the low-temperature liquid boiler from the evaporator, and the other part is used for generating electricity by using a liquid expander. The multifunctional water-saving device realizes multiple functions of water saving, waste heat utilization, waste heat power generation and the like.

As a preferred embodiment, the condensate pressurized delivery system includes a condensate pump 5, a deaerator 6 and a feed pump 7, wherein the shell side outlet of the evaporator 3, the inlet and outlet of the condensate pump 5, the inlet and outlet of the deaerator 6, the inlet and outlet of the feed pump 7 and the shell side inlet of the condenser 1 are sequentially connected in series through pipelines.

In the embodiment, the circulating water of the low-temperature liquid boiler coming out of the shell side of the evaporator 3 is conveyed by the condensate pump 5, the deaerator 6 is used for deoxidizing and reducing the corrosion and pressurization of liquid to metal, and the water feeding pump 7 is used for smoothly conveying the circulating water to the condenser 1, so that the circulating water of the low-temperature liquid boiler is conveyed in a good pressurized mode, the structural design is reasonable, and the pressurized effect is good.

In a preferred embodiment, a gas-liquid separator is provided between the compressor 4 and the tube side outlet of the evaporator 3, the inlet of the gas-liquid separator is connected to the tube side outlet of the evaporator 3 through a pipeline, and the gas outlet of the gas-liquid separator is connected to the inlet of the compressor 4 through a pipeline.

In the above embodiment, since the air intake of the compressor 4 must be guaranteed to be in a pure gas state, if part of the circulating working medium at the outlet of the evaporator 3 is still in a liquid state, an air-liquid separator is needed before the compressor 4, so the problem that the operation of the compressor 4 is affected by the part of the liquid working medium in the circulating working medium from the evaporator 3 is solved by adding the air-liquid separator in the embodiment.

As a preferred embodiment, the heat insulation structure is provided on the outer surface of the compressor 4 and the outside of the pipeline connecting the compressor 4 and the pipe side inlet of the condenser 1.

In the above embodiment, heat loss is reduced by the insulating structure. In this embodiment, the heat insulation structure may be a heat insulation technology commonly used on pipelines, such as a coating heat insulation layer.

As a preferred embodiment, a cold insulation structure is provided outside the outer surface of the liquid expander 2 and outside the line connecting the liquid expander 2 and the tube side inlet of the evaporator 3.

In the above embodiment, the cooling loss is reduced by providing the cooling structure. Specifically, the cold insulation structure adopts the cold insulation measure (the existing cold insulation measure) on the conventional pipeline. The cold insulation measures belong to the prior art and are not described in detail here.

In this embodiment, a barometer for monitoring the discharge pressure of the liquid expander 2 is installed at the outlet of the liquid expander. Meanwhile, a temperature monitor for monitoring the temperature of the fluid therein is installed at the tube side outlet of the evaporator 3. The exhaust pressure of the liquid expander 2 and the condensation water temperature at the outlet of the evaporator 3 are monitored in real time, specifically, during the operation of the system, the exhaust pressure of the liquid expander 2 cannot be too low so as to ensure that the exhaust temperature does not freeze water in the shell side of the evaporator 3, and generally, the exhaust temperature of the liquid expander 2 should be ensured to be higher than 0 ℃. However, at the same time, the discharge pressure of the liquid expander 2 must not be too high, so as to ensure that the discharge temperature of the circulating working medium must be lower than the temperature of water or steam in the shell side of the evaporator 3, and the temperature difference can reach more than 10 ℃. The outlet temperature of the evaporator 3 must be lower than the allowable inlet temperature of the compressor 4 (typically 25-30 ℃), so as to prevent the sealing device of the compressor 4 from being damaged due to the excessive temperature of the circulating working medium after the compressor 4 works. Therefore, by setting the barometer and the temperature monitor (a thermocouple can be adopted), real-time monitoring is realized, so that the staff can make timely response.

What needs to be specifically and additionally stated is: in the steam turbine low-pressure cylinder rear steam waste heat utilization system, necessary auxiliary facilities such as a safety valve, a pressure relief valve, a pressure transmitter, a temperature transmitter, a valve, a control system and the like can be flexibly configured on each core component and related pipelines according to actual use requirements. To increase the safety of the overall system use.

Of course, the barometer and the temperature detector can be matched with various electric control valves arranged on the pipeline to realize the sectional opening and closing of the pipeline, and the intelligent control is realized through a control system as a whole.

In the following, in order to describe the operation flow and process of the present utility model more specifically, CO is used ₂ The transcritical cycle is exemplified by the following:

as shown in fig. 2 and 3, to compare the advantages of the low pressure cylinder post-steam waste heat utilization system of the steam turbine according to the embodiment, another opposite example (e.g. fig. 4 and 5) is illustrated. First, as can be seen from the temperature-entropy diagram (FIG. 2), the thermodynamic cycle in the system of the present embodiment can be approximated as four processes, isentropic compression (a-b), constant pressure exotherm (b-c), isentropic expansion (c-d), constant pressure endotherm (d-a). In the cycle, the working medium after isentropic expansion is at the d point (3.5 MPa,0 ℃), the working medium state is in a gas-liquid mixed state, and the cycle working medium enters the evaporator 3, and because the temperature of the working medium is 0 ℃ and a large temperature difference exists between the working medium and the exhaust gas (about 65 ℃ generally) of the low-pressure cylinder of the power plant turbine running in the shell side, the heat in the exhaust gas of the low-pressure cylinder of the turbine can be transferred to CO ₂ In the circulating working medium, CO ₂ The working medium gradually evaporates from the gas-liquid mixed state to the pure gas state, and the temperature is also increased to 20 ℃, namely the point a (3.5 MPa,20 ℃). And then into compressor 4, CO ₂ Working mediumThe temperature and pressure reach the point b (11 MPa,105 ℃), and the high-temperature high-pressure CO is generated at the moment ₂ The working medium enters a condenser and continuously transfers heat to the boiler low-temperature circulating water running on the shell side, so that the boiler water is primarily heated, and CO ₂ The temperature of the working medium is reduced to 35 ℃, namely the point c (11 MPa,35 ℃), and then CO ₂ The working medium is subjected to isentropic expansion through the liquid expander, and the high-pressure working medium pushes the expander rotor to rotate, so that the conversion from internal energy to mechanical energy is realized. At the moment, the working medium is in a low-temperature and low-pressure state, namely, the d point (3.5 MPa,0 ℃). The working medium is regenerated into a high-quality cold source, and the high-quality cold source enters the evaporator again to repeat the thermodynamic exchange cycle.

The energy conversion process of the above-exemplified embodiment, such as CO shown in FIG. 3 ₂ Transcritical circulating pressure enthalpy diagram. Constant pressure endothermic Process (d-a), CO ₂ The enthalpy of the working medium is increased from 260KJ/Kg to 462KJ/Kg, and then the working medium is compressed and applied by the compressor 4, namely, the isentropic compression process (a-b), and the enthalpy of the working medium is further increased to 505KJ/Kg. To this end, CO ₂ The enthalpy difference (heat absorption capacity) of the working medium reaches 245KJ/Kg in total, and the energy consumption of the compressor 4 is 43KJ/Kg. Then the constant pressure exothermic process (b-c) and CO are carried out in the heat recovery process ₂ The enthalpy of the working medium is reduced from 505KJ/Kg to 292KJ/Kg, wherein 213KJ/Kg is used for heating other working mediums in the plant and is transferred out. Finally, isentropic expansion process (c-d) and CO are carried out in a liquid expander ₂ The enthalpy value of the working medium is reduced from 292KJ/Kg to 260KJ/Kg, and 32KJ/Kg is utilized by an expander in the process and converted into electric energy. From the whole circulation, the energy is saved by 43KJ/Kg, and the expansion process generates 32KJ/Kg, so that the electric energy generated by the liquid expander can be well complemented with the energy consumption of the compressor, and the actual energy consumption of the compressor is only 11KJ/Kg.

The thermodynamic cycle adopted in the steam turbine low-pressure cylinder rear steam waste heat utilization system is similar to the traditional heat pump cycle and refrigeration cycle, and the difference is that the isentropic expansion process of the liquid expander is adopted in the third process (c-d) to replace the isenthalpic expansion process of a throttle valve of the common heat pump or refrigeration cycle. Comparing fig. 2, 3 with fig. 4 and 5, it is found that when the liquid expander is adopted, the isentropic expansion process corresponds to the enthalpy difference before and after the process is used for generating power for the liquid expander, and the enthalpy value of the working medium after expansion is reduced by the output system, so that the heat absorption capacity of the working medium is greatly increased. When a throttle valve is adopted (as shown in fig. 4 and 5), the process is an isenthalpic process, and heat is not output from the system but always exists in the working medium, so that the enthalpy difference of the working medium before and after expansion is 0. The heat absorption capacity of the working medium is lower than that of the thermodynamic cycle corresponding to the isentropic expansion process by adopting the liquid expander.

In the description of the present utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present utility model and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present utility model.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present utility model, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.

In the present utility model, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present utility model, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present utility model. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

While embodiments of the present utility model have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the utility model, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the utility model.

Claims

1. A steam turbine low pressure jar back steam waste heat utilization system, its characterized in that: including condenser (1), liquid expander (2), evaporimeter (3) and compressor (4), the low pressure jar steam outlet connection of steam turbine shell side entry of evaporimeter (3), the shell side export of evaporimeter (3) is through condensate water pressurization conveying system through the pipeline connection shell side entry of condenser (1), the shell side export of condenser (1) is through the economizer water inlet of pipeline connection boiler, the high temperature high pressure steam outlet of boiler is through the pipeline connection the steam inlet of steam turbine, the tube side export of evaporimeter (3), the import and the export of compressor (4), the tube side entry and the tube side export of condenser (1), the import and the export of liquid expander (2) and the tube side entry of evaporimeter (3) are through the pipeline in order.

2. The system for utilizing waste heat of low pressure cylinder post-steam of steam turbine according to claim 1, wherein: the condensate water pressurized conveying system comprises a condensate water pump (5), a deaerator (6) and a water feeding pump (7), wherein a shell side outlet of the evaporator (3), an inlet and an outlet of the condensate water pump (5), an inlet and an outlet of the deaerator (6), an inlet and an outlet of the water feeding pump (7) and a shell side inlet of the condenser (1) are sequentially connected in series through pipelines.

3. The system for utilizing waste heat of low pressure cylinder post-steam of steam turbine according to claim 1, wherein: a gas-liquid separator is arranged between the compressor (4) and the tube side outlet of the evaporator (3), an inlet of the gas-liquid separator is connected with the tube side outlet of the evaporator (3) through a pipeline, and a gas outlet of the gas-liquid separator is connected with an inlet of the compressor (4) through a pipeline.

4. The system for utilizing waste heat of low pressure cylinder post-steam of steam turbine according to claim 1, wherein: and heat insulation structures are arranged outside pipelines connecting the outer surface of the compressor (4) with the tube side inlet of the condenser (1).

5. The system for utilizing waste heat of low pressure cylinder post-steam of steam turbine according to claim 1, wherein: and a cold insulation structure is arranged outside a pipeline connected between the outer surface of the liquid expander (2) and the tube side inlet of the evaporator (3).

6. The system for utilizing waste heat of low pressure cylinder post-steam of steam turbine according to claim 1, wherein: and an air pressure gauge for monitoring the exhaust pressure of the liquid expander (2) is arranged at the outlet of the liquid expander.

7. The system for utilizing waste heat of low pressure cylinder post-steam of steam turbine according to claim 1, wherein: and a temperature monitor for monitoring the temperature of fluid in the evaporator (3) is arranged at the outlet of the tube side of the evaporator.