Power station auxiliary steam electricity and heat co-production gradient utilization energy-saving system

Abstract

The utility model discloses a gradient utilization energy-saving system for auxiliary steam electric heat cogeneration of a power station, which is characterized in that a dead steam outlet of an auxiliary steam power generation system is connected with a dead steam heat supply system, and a condensation water system is connected behind the dead steam heat supply system; the auxiliary steam power generation system is communicated with the auxiliary steam inlet pipeline; in the dead steam heat supply system, dead steam passes through a condensation heat exchanger, dead steam heating water is heated, and the dead steam becomes condensed water; the condensation water system comprises a condensation water inlet pipeline, the condensation water inlet pipeline is connected with a condensation water tank, the condensation water tank is provided with a liquid level meter and connected with a condensation water pump and a vacuum pressure pipe or an exhaust pipe, and a condensation water heat exchanger is connected behind the condensation water pump. The technical problem that in the prior art, due to the fact that the energy gradient between auxiliary steam and a heating medium is too large, work capacity is wasted can be solved.

Description

Technical Field

[0001] The utility model relates to the technical fields of steam power generation and waste heat utilization, in particular to an energy-saving system for gradient utilization of auxiliary steam electro-thermal co-generation in a power station. Background Technique

[0002] With the advent of the dual-carbon era, people's pursuit of energy has become more economical and cost-effective. As a carrier of traditional energy, how to better utilize steam has become an important task and challenge. In many industries, in order to obtain stable heat energy, steam is used as a heat source to heat other working fluids in the process for various productions. The heat energy utilization of the steam system needs to make full use of it step by step according to the energy quality, with high-energy used for high-level applications, low-energy used for low-level applications, and temperature and pressure matching. Energy cascade utilization and comprehensive utilization, including the utilization of various heats of steam, exhaust steam and condensate. In order to more effectively utilize steam for heating in the production process, most enterprises improve their equipment to further enhance their market competitiveness and energy conservation and emission reduction.

[0003] There are many heavy industries in China, especially the heavy industries represented by the power generation industry. China is a major power generation country. Generally speaking, power stations include coal-fired power generation, gas turbine (combined) power generation, IGCC, solar thermal, nuclear power, waste incineration power stations, etc. In power stations, auxiliary steam (abbreviated as auxiliary steam) is often introduced to heat the media required in the process. Auxiliary steam usually comes from the extraction steam of the steam turbine or boiler system. In many working conditions, the temperature at which the medium to be heated needs to be heated is not high, such as water, air, etc., and its heating temperature is usually several tens of degrees, and at most it is around 100 degrees. Due to the extraction position and process, auxiliary steam is usually two or three hundred degrees and has a relatively high pressure. Although the enthalpy value of the auxiliary steam heating is released, the pressure and temperature of the auxiliary steam are relatively high, and its work capacity (exergy value) is not utilized, resulting in energy waste. This kind of waste is usually called unreasonable energy utilization gradient. For example, in the primary and secondary air heaters of coal-fired units, air is usually heated to twenty or thirty degrees, while the pressure of the steam is often 4-10 kg (absolute pressure) and two or three hundred degrees. Under the same working conditions, the raw water in the raw water heater is usually heated to 20-30 degrees, but the extracted auxiliary steam also reaches two or three hundred degrees and 4-10 kg. In power plants in northern China, in-plant heating usually also uses auxiliary steam for heating. The heating circulating water is usually only 80 degrees, but the auxiliary steam is also usually the aforementioned high temperature and high pressure (both from the extraction steam of the steam turbine). Similarly, in waste power stations, the leachate is also heated by the extraction steam of the auxiliary boiler or steam turbine, called auxiliary steam, as a heat source for heating, but the temperature at which the leachate is heated is not high. For a long time, due to the influence of the price, adjustability, start-stop frequency of the power generation steam turbine system, and the feasibility of exhaust steam heat exchange and other factors, the energy-saving research on small-flow, high-parameter, large-gradient steam heating in industry has not been well solved for this kind of waste.

[0004] Therefore, it is necessary to further improve the existing technology to solve the above technical problems. Summary of the Invention

[0005] The purpose of the present utility model is to provide an energy-saving system for gradient utilization of auxiliary steam and electric heat co-generation in power stations, which can solve the technical problem in the existing technology that due to the too large energy gradient between the auxiliary steam and the heating medium, the work capacity is wasted.

[0006] The technical solution of the present utility model is as follows:

[0007] An energy-saving system for gradient utilization of auxiliary steam and electric heat co-generation in power stations, characterized in that: the exhaust steam outlet of the auxiliary steam power generation system is connected to the exhaust steam heating system, and the exhaust steam heating system is followed by a condensate system; the auxiliary steam power generation system is communicated with the auxiliary steam inlet pipeline; in the exhaust steam heating system, the exhaust steam passes through a condensation heat exchanger to heat the exhaust steam heating water, and the exhaust steam becomes condensate; the condensate system includes a condensate inlet tank pipeline, the condensate inlet tank pipeline is connected to a condensate tank, the condensate tank is provided with a liquid level gauge, the condensate tank is connected with a condensate pump, a vacuum pressure pipe or an exhaust pipe, and the condensate pump is followed by a condensate heat exchanger; the auxiliary steam power generation system includes a screw expander, a generator and connecting accessories; the auxiliary steam passes through the pipeline, enters the screw expander to generate electricity or do work, pushes the screw expander, and drives the generator to generate electricity through the connection of the accessories to the motor.

[0008] The exhaust steam heating system includes exhaust steam, exhaust steam heating water, an exhaust steam pipeline, a condensation heat exchanger, a vacuum system, an inlet water pipeline, and an outlet water pipeline; the exhaust steam is discharged from the exhaust port of the screw expander, and in the condensation heat exchanger, the exhaust steam condenses and releases heat, becomes condensate and is discharged, and enters the condensate tank; the exhaust steam heating water is used as a working medium, which is the water or intermediate medium that needs to be directly heated by the auxiliary machine.

[0009] The energy-saving system for gradient utilization of auxiliary steam and electric heat co-generation in power stations of the present utility model has the following beneficial effects compared with the existing technology:

[0010] 1. The present utility model provides an energy-saving system for gradient utilization of auxiliary steam and electric heat co-generation in power stations, which can effectively supply heat under the condition of constant total steam volume, and convert the steam kinetic energy with energy gradient into electric energy for electric heat co-generation. Thus, energy conservation and emission reduction are realized, turning waste into treasure, and the economic benefit is significantly improved.

[0011] 2. The energy-saving system for gradient utilization of auxiliary steam and electric heat co-generation in power stations of the present utility model makes better use of the waste heat in the condensate, collects the heat of steam condensation better, and plays an energy-saving role.

[0012] 3. The utility model solves mechanical equipment problems such as vibration, fatigue of heat exchange equipment and too high hydrophobic configuration caused by high-parameter steam, reduces the temperature and pressure of the heat exchange equipment to a reasonable range, which is more conducive to the safe operation of the heat exchange equipment. It is also more conducive to the recovery of hydrophobic water, playing a role in water conservation and emission reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The following further describes the present utility model in conjunction with the drawings and embodiments.

[0014] Figure 1 It is a schematic structural diagram of an embodiment of the present utility model.

[0015] Summary of reference numerals in the drawings:

[0016] 1. Auxiliary steam; 2. Auxiliary steam power generation system, where: 2.1 Screw expander, 2.2 Generator, 2.3 Connecting accessory;

[0017] 3. Exhaust steam; 4. Exhaust steam heating system, where: 4.1 Exhaust steam pipeline, 4.2 Condensing heat exchanger, 4.3 Vacuum system, 4.4 Inlet water pipeline, 4.5 Outlet water pipeline;

[0018] 5. Exhaust steam heated water; 6. Condensate system, where: 6.1 Condensate inlet tank pipeline, 6.2 Condensate tank, 6.3 Liquid level gauge, 6.4 Condensate pump, 6.5 Vacuum pressure regulating pipe, 6.6 Condensate heat exchanger, 6.7 Condensate drain pipe;

[0019] 7. Condensate heated water, where: 7.1 Condensate heated water inlet pipe, 7.2 Condensate heated water outlet pipe. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] In the following, an embodiment of an auxiliary steam electro-thermal co-generation gradient utilization energy-saving system of the present utility model will be described with reference to the drawings.

[0021] The embodiments recorded herein are specific specific embodiments of the present utility model, used to illustrate the concept of the present utility model, and are all explanatory and exemplary, and should not be construed as a limitation on the embodiments of the present utility model and the scope of the present utility model. Except for the embodiments recorded herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of this application, and these technical solutions include technical solutions that make any obvious substitutions and modifications to the embodiments recorded herein.

[0022] The drawings in this specification are schematic diagrams to assist in explaining the concept of the present utility model, schematically showing the shapes of various parts and their mutual relationships. Please note that in order to clearly show the structures of various parts of the embodiments of the present utility model, the drawings may not be drawn according to the same scale. Identical or similar reference numerals are used to represent identical or similar parts.

[0023] An energy-saving system for gradient utilization of auxiliary steam electro-thermal co-generation in a power station, comprising: auxiliary steam 1, an auxiliary steam power generation system 2, exhausted steam 3, an exhausted steam heating system 4, and a condensate system 6. The auxiliary steam 1 enters the auxiliary steam power generation system through pipeline valves. After generating electricity through a screw expansion generator in the auxiliary steam power generation system, it becomes exhausted steam and is discharged. The exhausted steam enters the exhausted steam heating system 4. In the exhausted steam heating system, the exhausted steam heats the heated water of the exhausted steam through a condensation heat exchanger 4.2, and the exhausted steam becomes condensate. The heated water of the exhausted steam is used as a working medium to enter the next process after its temperature is raised. The condensate enters the condensate system 6. It is discharged to the next process through a water tank 6.2, a condensate pump 6.4, etc., and the heat of the condensate is exchanged with the heated water of the condensate before being discharged. The auxiliary steam is the steam extracted from steam-producing equipment such as steam turbines or boilers and is provided for the use of auxiliary machines. Auxiliary machines in a power station generally refer to those general auxiliary machines used for power generation in the power station. All power station supporting equipment other than the three major main engines are auxiliary machines, including desulfurization and denitration equipment, water treatment equipment, in-plant heating equipment, carbon capture systems, etc. However, it does not include auxiliary equipment such as external steam supply and heating in the power station. The auxiliary steam power generation system includes a screw expander 2.1, a generator 2.2, and a connecting accessory 2.3. The auxiliary steam enters the screw expander 2.1 through a pipeline to generate electricity or do work, driving the screw expander, and drives the generator 2.2 to generate electricity through the accessory connecting the motor. After doing work, the temperature and pressure of the auxiliary steam drop, and it is discharged from the exhaust port of the screw expander. The pressure and temperature of the exhaust steam meet the requirements of the subsequent exhausted steam heating system. The energy gradient between the auxiliary steam inlet and the auxiliary steam exhaust port is used to generate electricity by doing work. Here, the exhausted steam refers to the steam that has done work and is discharged from the screw expander. The exhausted steam heating system includes exhausted steam 1, heated water of the exhausted steam 5, an exhausted steam pipeline 4.1, a condensation heat exchanger 4.2, a vacuum system 4.3, an inlet pipeline 4.4, and an outlet pipeline 4.5. The exhausted steam is discharged from the exhaust port of the screw expander. In the condensation heat exchanger, the exhausted steam condenses and releases heat, becomes condensate and is discharged, and enters the condensate tank 6.2. The heated water of the exhausted steam is used as a working medium, which may be the water that needs to be directly heated by the auxiliary machine or an intermediate medium. Taking this as the medium, it heats the working medium that needs to be heated by the auxiliary machine. The heated water of the exhausted steam can also be other fluids. The heated water of the exhausted steam enters the condensation heater through the inlet pipeline and the outlet pipeline, and is heated by the heat released by the exhausted steam in the condensation heater and enters the next process. The condensate system includes a condensate inlet tank pipeline 6.1, a condensate tank 6.2, a liquid level gauge 6.3, a condensate pump 6.4, a vacuum pressure pipe or an exhaust pipe, a condensate drain pipe 6.7, a condensate heat exchanger 6.6, heated water of the condensate 7, a heated water inlet pipe of the condensate 7.1, and a heated water outlet pipe of the condensate 7.2. The exhausted steam releases heat in the condensation heat exchanger and becomes condensate, which enters the condensate tank. A liquid level gauge is provided on the condensate tank to monitor the liquid level. A vacuum pumping or exhaust system is provided at the top of the vacuum tank. A condensate pump is provided at the bottom, and the condensate is discharged to the next process through the condensate drain pipe.Optionally, before being sent to the next process, the heat of the condensate can be utilized to heat the condensate heating water through a condensate heat exchanger, raising the temperature of the condensate heating water and sending it to the next process.

[0024] The condensate heating water and the exhaust steam heating water can be the same medium for series cascade heating, or different media for separate independent heating. It is also possible that only one of the condensate heating water or the exhaust steam heating water exists.

[0025] Furthermore, the screw expander is a traditional screw expander or the latest general screw expander.

[0026] Furthermore, the screw expanders can be used in parallel, in series, or in a combination of parallel and series. When used in series, the exhaust steam (or high-pressure water) is multi-stage exhaust steam, which can be extracted for use in other processes as needed, and the remaining enters the next-stage screw expander for power generation.

[0027] Furthermore, the screw expansion generator means that the screw expander does work to drive a generator for power generation. In practical applications, it is also possible to drive other equipment to do work, such as driving a water pump and a fan to operate.

[0028] Furthermore, the exhaust steam heating water and the condensate heating water can be different working fluids or the same working fluid for series heating. At the same time, they can also be other working fluids besides water, such as heat-conducting oil, air, other fluids, etc.

[0029] The above describes the implementation mode of an auxiliary steam-electricity co-generation gradient utilization energy-saving system of the present utility model. For the specific features of an auxiliary steam-electricity co-generation gradient utilization energy-saving system of the present utility model, such as shape, size, and position, they can be specifically designed according to the functions of the features disclosed above, and these designs can all be achieved by those skilled in the art. Moreover, the disclosed technical features are not limited to the combinations with other disclosed features. Those skilled in the art can also make other combinations among the technical features according to the purpose of the present utility model, with the purpose of the present utility model as the criterion.

Claims

1. An energy-saving system for gradient utilization of auxiliary steam and electric heat co-generation in a power station, characterized in that: Including: The exhaust steam outlet of the auxiliary steam power generation system is connected to the exhaust steam heating system, and the exhaust steam heating system is then connected to the condensate system; The auxiliary steam power generation system is communicated with the auxiliary steam inlet pipeline; in the exhaust steam heating system, the exhaust steam passes through the condensation heat exchanger to heat the exhaust steam heating water, and the exhaust steam becomes condensate; the condensate system includes a condensate inlet tank pipeline, the condensate inlet tank pipeline is connected to the condensate tank, the condensate tank is provided with a liquid level gauge, the condensate tank is connected with a condensate pump, a vacuum pressure pipe or an exhaust pipe, and a condensate heat exchanger is connected after the condensate pump; the auxiliary steam power generation system includes a screw expander, a generator and connecting accessories; the auxiliary steam passes through the pipeline, enters the screw expander to generate electricity or do work, pushes the screw expander, and drives the generator to generate electricity through the connecting accessories connecting the motor.

2. The energy-saving system for gradient utilization of auxiliary steam electro-thermal co-generation in a power station according to claim 1, wherein: The exhaust steam heating system includes exhaust steam, exhaust steam heating water, an exhaust steam pipeline, a condensation heat exchanger, a vacuum system, a water inlet pipeline, and a water outlet pipeline; the exhaust steam is discharged from the exhaust port of the screw expander, and in the condensation heat exchanger, the exhaust steam condenses and releases heat, becomes condensate and is discharged, and enters the condensate tank; the exhaust steam heating water is used as a working medium, which is the water or intermediate medium that needs to be directly heated by the auxiliary machine.

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