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

Abstract

The invention discloses a gradient utilization energy-saving system for auxiliary steam electric heat cogeneration of a power station. The gradient utilization energy-saving system comprises auxiliary steam, an auxiliary steam power generation system, dead steam, a dead steam heat supply system and a condensation water system. Wherein auxiliary steam enters the auxiliary steam power generation system through a pipeline valve, and is changed into dead steam to be discharged after being subjected to power generation through a screw expansion power generator in the auxiliary steam power generation system; dead steam enters the dead steam heat supply system, in the dead steam heat supply system, the dead steam passes through a condensation heat exchanger, dead steam heating water is heated, and the dead steam becomes condensed water; the dead steam is heated by heating water to serve as a working medium to enter the next procedure, and condensed water enters a condensed water system and is discharged to the next procedure through a water tank and a condensed 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 invention relates to the technical field of steam power generation and waste heat utilization, and in particular to a power station auxiliary steam power and heat cogeneration gradient utilization energy-saving system. Background Art

[0002] At present, 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 thermal energy, people use steam as a heat source to heat other working fluids in the process for various productions. The thermal energy utilization of the steam system needs to be fully utilized step by step according to the energy grade, with high energy and high use, low energy and low use, and temperature and pressure matching. Energy cascade utilization, comprehensive utilization, and multiple heat utilization of steam, exhaust steam and condensed water. In order to more effectively utilize steam for heating in the production process, most companies have further improved their market competitiveness and energy conservation and emission reduction through equipment improvements.

[0003] The power stations usually mentioned include coal-fired power generation, gas turbine (combined) power generation, IGCC, solar thermal, nuclear power, waste incineration power plants and other power plants. In power plants, auxiliary steam (abbreviated as auxiliary steam) is often introduced to heat the medium required in the process. Auxiliary steam usually comes from the extraction of steam from the turbine or boiler system. Under many working conditions, the temperature of the heated medium is not high, such as water, air, etc., whose heating temperature is usually tens of degrees, and the highest is also around 100 degrees. The auxiliary steam is usually 200 to 300 degrees due to the extraction position and process, and the pressure is also high. Although the enthalpy of auxiliary steam heating is released, the pressure and temperature of the auxiliary steam are high, and its working capacity (exergy value) is not utilized, resulting in energy waste. This waste is usually called unreasonable energy utilization gradient. For example, in the primary and secondary air heaters in coal-fired units, the air is usually heated to 20 to 30 degrees, but the steam pressure is often 4-10 kg (absolute pressure) and 200 to 300 degrees. Under the same working conditions, the raw water of the raw water heater is usually heated to 20-30 degrees, but the extracted auxiliary steam also reaches 200-300 degrees, 4-10 kilograms. In power plants in northern China, auxiliary steam is usually used for heating in the plant, and the heating circulating water is usually only 80 degrees, but the auxiliary steam is also usually the aforementioned high temperature and high pressure (all from the steam extraction of the steam turbine). Similarly, in garbage power plants, the heating of leachate also uses the steam extraction of auxiliary boilers or steam turbines, called auxiliary steam, as a heat source for heating, but the heated temperature of the leachate is not high. For a long time, energy-saving research in industry for small flow, high parameter, and large gradient steam heating has not been well solved due to the influence of the price, adjustability, start-stop frequency of the power generation steam turbine system, and other factors such as the feasibility of exhaust steam heat exchange.

[0004] Therefore, it is necessary to further improve the prior art to solve the above technical problems. Summary of the invention

[0005] The purpose of the present invention is to provide a power station auxiliary steam electric heat cogeneration gradient utilization energy-saving system, which can solve the technical problem of the prior art that the working capacity is wasted due to the excessive energy gradient between the auxiliary steam and the heating medium.

[0006] The technical solution of the present invention is: A power station auxiliary steam power and heat cogeneration gradient utilization energy-saving system, characterized in that it includes: auxiliary steam, an auxiliary steam power generation system, exhaust steam, an exhaust steam heating system, and a condensate water system; wherein: the auxiliary steam passes through a pipeline valve and enters the auxiliary steam power generation system, and is converted into exhaust steam and discharged after being generated by a screw expansion generator in the auxiliary steam power generation system; the exhaust steam enters the exhaust steam heating system, and in the exhaust steam heating system, the exhaust steam passes through a condensing heat exchanger to heat exhaust steam heating water, and the exhaust steam is converted into condensate water; after the exhaust steam heating water is heated, it enters the next process as a working medium, and the condensate water enters the condensate water system and is discharged to the next process through a water tank and a condensate water pump.

[0007] The auxiliary steam enters the auxiliary steam power generation system through pipelines and valve components; auxiliary steam is steam extracted from steam-producing equipment such as steam turbines or boilers, and is provided to auxiliary machines. Auxiliary machines in power stations usually refer to those used for power generation in a broad sense. All power station supporting equipment other than the three main machines are auxiliary machines, including desulfurization and denitrification equipment, water treatment equipment, in-plant heating equipment, carbon capture systems, etc. However, it does not include auxiliary equipment such as external steam and heating supply of power stations.

[0008] The auxiliary steam power generation system includes a screw expander, a generator and connecting accessories; the auxiliary steam passes through the pipeline and enters the screw expander to generate electricity or work, drives the screw expander, and is connected to the motor through the accessories to drive the generator to generate electricity; after the auxiliary steam works, its temperature and pressure drop and is discharged from the exhaust port of the screw expander. The pressure and temperature of the exhaust steam meet the requirements of the subsequent exhaust steam heating system, and the energy gradient between the auxiliary steam inlet and the auxiliary steam exhaust port is used to generate electricity.

[0009] The exhaust steam heat exchange system includes exhaust steam, exhaust steam heating water, exhaust steam pipeline, condensing heat exchanger, vacuum system, water inlet pipeline, and water outlet pipeline; the exhaust steam is discharged from the exhaust port of the screw expander, and in the condensing heat exchanger, the exhaust steam condenses and releases heat, and is discharged as condensed water and enters the condensate tank; the exhaust steam heating water is a working medium, which is water that needs to be directly heated by the auxiliary machine, or an intermediate medium, which is used as a medium to heat the working medium that needs to be heated by the auxiliary machine; the exhaust steam heating water may be other fluids, and the exhaust steam heating water passes through the water inlet pipeline and the water outlet pipeline and enters the condensing heater, where it is heated by the heat released by the exhaust steam and enters the next process.

[0010] The condensate system includes a condensate inlet pipeline, a condensate tank, a liquid level gauge, a condensate pump, a vacuum pressure pipe or an exhaust pipe, a condensate drain pipe, a condensate heat exchanger, condensate heating water, a condensate heating water inlet pipe, and a condensate heating water outlet pipe; the exhaust steam releases heat in the condensation heat exchanger to become condensate, and enters the condensate tank; a liquid level gauge is provided on the condensate tank to monitor the liquid level; a vacuum exhaust or exhaust system is provided on the top of the vacuum tank, and a condensate pump is provided at the bottom to discharge the condensate to the next process through the condensate drain pipe.

[0011] The condensate system can selectively utilize the heat of the condensate to exchange heat with the condensate heating water through a condensate heat exchanger before it is discharged to the next process, thereby raising the temperature of the condensate heating water and sending it to the next process.

[0012] Compared with the prior art, the power station auxiliary steam power and heat cogeneration gradient utilization energy-saving system of the present invention has the following beneficial effects: 1. The present invention provides a power station auxiliary steam electric heat cogeneration gradient utilization energy-saving system, which can realize effective heat supply under the condition of unchanged total steam volume, and convert steam kinetic energy with energy gradient into electric energy for utilization of electric heat cogeneration. Thus, energy saving and emission reduction can be achieved, waste can be turned into treasure, and economic benefits can be significantly improved.

[0013] 2. The power station auxiliary steam electric heat cogeneration gradient utilization energy-saving system of the present invention utilizes the waste heat in the condensed water, thereby better collecting the heat of steam condensation and achieving energy-saving effect.

[0014] 3. The present invention solves the mechanical equipment problems such as vibration, fatigue, and over-configuration of drain caused by high-parameter steam, and 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 drain, which plays a role in water saving and emission reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0016] Figure 1 It is a schematic structural diagram of an embodiment of the present invention.

[0017] Summary of reference numerals: 1. Auxiliary steam; 2. Auxiliary steam power generation system, including: 2.1 screw expander, 2.2 generator, 2.3 connecting accessories; 3. Exhaust steam; 4. Exhaust steam heating system, including: 4.1 Exhaust steam pipeline, 4.2 Condensation heat exchanger, 4.3 Vacuum system, 4.4 Water inlet pipeline, 4.5 Water outlet pipeline; 5. Exhaust steam heating water; 6. Condensate system, including: 6.1 Condensate inlet pipeline, 6.2 Condensate tank, 6.3 Liquid level gauge, 6.4 Condensate pump, 6.5 Vacuum pressure pipe, 6.6 Condensate heat exchanger, 6.7 Condensate drain pipe; 7. Condensate heating water, including: 7.1 Condensate heating water inlet pipe, 7.2 Condensate heating water outlet pipe.

[0018] Hereinafter, an embodiment of a power station auxiliary steam power and heat cogeneration gradient utilization energy-saving system of the present invention will be described with reference to the accompanying drawings.

[0019] The embodiments described herein are specific embodiments of the present invention, which are used to illustrate the concept of the present invention, are illustrative and exemplary, and should not be interpreted as limiting the embodiments of the present invention and the scope of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the claims and the contents disclosed in the specification of this application, including any obvious replacement and modification of the embodiments described herein.

[0020] The drawings in this specification are schematic diagrams, which assist in explaining the concept of the present invention and schematically show 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 invention, the drawings are not necessarily drawn in the same proportions. The same or similar reference numerals are used to represent the same or similar parts.

[0021] A power station auxiliary steam power and heat cogeneration gradient utilization energy-saving system, comprising: auxiliary steam, an auxiliary steam power generation system, exhaust steam, an exhaust steam heating system, and a condensate system. The auxiliary steam passes through a pipeline valve and enters the auxiliary steam power generation system. After generating electricity through a screw expansion generator in the auxiliary steam power generation system, it is discharged as exhaust steam. The exhaust steam enters the exhaust steam heating system. In the exhaust steam heating system, the exhaust steam passes through a condensing heat exchanger to heat the exhaust steam heating water, and the exhaust steam becomes condensate. After the exhaust steam heating water is heated, it enters the next process as a working medium. The condensate enters the condensate system. It is discharged to the next process through a water tank, a condensate pump, etc., and the heat of the condensate is exchanged with the condensate heating water before being discharged. Auxiliary steam is steam extracted from steam-producing and gas-using equipment such as a steam turbine or a boiler, and is used as an auxiliary machine. Auxiliary equipment in power stations usually refers to those generalized power station auxiliary equipment used for power generation. All power station supporting equipment except the three main machines are auxiliary equipment, including desulfurization and denitrification equipment, water treatment equipment, in-plant heating equipment, carbon capture system, etc. However, it does not include auxiliary equipment such as external steam and heat supply of the power station. The auxiliary steam power generation system includes screw expanders, generators and connecting accessories. Auxiliary steam passes through the pipeline and enters the screw expander to generate electricity or work, drives the screw expander, and connects to the motor through the accessories to drive the generator to generate electricity. After the auxiliary steam works, its temperature and pressure drop and is discharged from the exhaust port of the screw expander. The pressure and temperature of the exhaust steam meet the requirements of the subsequent exhaust steam heating system. The energy gradient between the auxiliary steam inlet and the auxiliary steam exhaust port is used to generate electricity. Here, exhaust steam refers to the steam discharged from the screw expander that has done work. The exhaust steam heat exchange system includes exhaust steam, exhaust steam heating water, exhaust steam pipeline, condensing heat exchanger, vacuum system, water inlet pipeline, and water outlet pipeline. The exhaust steam is discharged from the exhaust port of the screw expander. In the condensing heat exchanger, the exhaust steam condenses and releases heat, and becomes condensed water and discharged into the condensate tank. As a working medium, the exhaust steam heating water may be water that needs to be directly heated by the auxiliary machine, or it may be an intermediate medium, which is used as a medium to heat the working medium that needs to be heated by the auxiliary machine. The exhaust steam heating water can also be other fluids. The exhaust steam heating water enters the condensation heater through the water inlet pipe and the water outlet pipe, and is heated by the heat released by the exhaust steam in the condensation heater and enters the next process. The condensate system includes a condensate inlet pipeline, a condensate tank, a liquid level gauge, a condensate pump, a vacuum pressure pipe or exhaust pipe, a condensate drain pipe, a condensate heat exchanger, condensate heating water, a condensate heating water inlet pipe, and a condensate heating water outlet pipe. The exhaust steam releases heat in the condensing heat exchanger and becomes condensate, and enters the condensate tank. A liquid level gauge is provided on the condensate tank to monitor the liquid level. A vacuum exhaust or exhaust system is provided on the top of the vacuum tank. A condensate pump is provided at the bottom to discharge the condensate to the next process through the condensate drain pipe. Optionally, before being discharged to the next process, the heat of the condensate can be used to exchange heat with the condensate heating water through the condensate heat exchanger to raise the temperature of the condensate heating water and send it to the next process.

[0022] The condensate heating water and the exhaust steam heating water can be the same medium, which is heated in series, or different mediums, which are heated separately. Alternatively, only one of the condensate heating water and the exhaust steam heating water can exist.

[0023] Furthermore, the screw expander is a traditional screw expander or a latest general screw expander.

[0024] Furthermore, the screw expanders can be used in parallel or in series, or in parallel and in 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 rest enters the next stage of the screw expander for power generation.

[0025] Furthermore, the screw expander generator refers to the screw expander working to drive the generator to generate electricity. In practical applications, it is also possible to drive other equipment to work, such as driving a water pump and a fan to work.

[0026] Furthermore, the exhaust steam heating water and condensate heating water can be different working fluids, or the same working fluid heated in series. At the same time, they can also be other working fluids besides water, such as heat transfer oil, air, other fluids, etc.

[0027] The above is a description of the implementation method of a power station auxiliary steam electric heat cogeneration gradient utilization energy-saving system of the present invention. The specific features of the power station auxiliary steam electric heat cogeneration gradient utilization energy-saving system of the present invention, such as shape, size and position, can be specifically designed according to the functions of the above-disclosed features, and these designs can be implemented by those skilled in the art. Moreover, the various technical features disclosed above are not limited to the combination with other features that have been disclosed. Those skilled in the art can also make other combinations between the various technical features according to the purpose of the present invention, so as to achieve the purpose of the present invention.

Claims

1. A power station auxiliary steam power and heat cogeneration gradient utilization energy-saving system, characterized by: include: Auxiliary steam, auxiliary steam power generation system, exhaust steam, exhaust steam heating system, condensate water system; wherein: the auxiliary steam passes through the pipeline valve and enters the auxiliary steam power generation system, and after generating electricity through the screw expansion generator in the auxiliary steam power generation system, it is converted into exhaust steam and discharged; the exhaust steam enters the exhaust steam heating system, and in the exhaust steam heating system, the exhaust steam passes through the condensing heat exchanger to heat the exhaust steam heating water, and the exhaust steam is converted into condensate water; after the exhaust steam heating water is heated, it enters the next process as a working medium, and the condensate water enters the condensate water system and is discharged to the next process through the water tank and the condensate water pump.

2. According to claim 1, a power station auxiliary steam power and heat cogeneration gradient utilization energy-saving system is characterized by: The auxiliary steam enters the auxiliary steam power generation system through pipelines and valve components; the auxiliary steam is steam extracted from the steam production equipment and provided to the auxiliary machine for use.

3. The power station auxiliary steam power and heat cogeneration gradient utilization energy-saving system according to claim 1 is characterized by: The auxiliary steam power generation system includes a screw expander, a generator and connecting accessories; the auxiliary steam passes through the pipeline and enters the screw expander to generate electricity or work, drives the screw expander, and is connected to the motor through the accessories to drive the generator to generate electricity; after the auxiliary steam works, its temperature and pressure drop and is discharged from the exhaust port of the screw expander. The pressure and temperature of the exhaust steam meet the requirements of the subsequent exhaust steam heating system, and the energy gradient between the auxiliary steam inlet and the auxiliary steam exhaust port is used to generate electricity.

4. The power station auxiliary steam power and heat cogeneration gradient utilization energy-saving system according to claim 1 is characterized by: The exhaust steam heat exchange system includes exhaust steam, exhaust steam heating water, exhaust steam pipeline, condensing heat exchanger, vacuum system, water inlet pipeline, and water outlet pipeline; the exhaust steam is discharged from the exhaust port of the screw expander, and in the condensing heat exchanger, the exhaust steam condenses and releases heat, and is discharged as condensed water and enters the condensate tank; the exhaust steam heating water is a working medium, which is water that needs to be directly heated by the auxiliary machine, or an intermediate medium, which is used as a medium to heat the working medium that needs to be heated by the auxiliary machine; the exhaust steam heating water may be other fluids, and the exhaust steam heating water passes through the water inlet pipeline and the water outlet pipeline and enters the condensing heater, where it is heated by the heat released by the exhaust steam and enters the next process.

5. The power station auxiliary steam power and heat cogeneration gradient utilization energy-saving system according to claim 1 is characterized by: The condensate system includes a condensate inlet pipeline, a condensate tank, a liquid level gauge, a condensate pump, a vacuum pressure pipe or an exhaust pipe, a condensate drain pipe, a condensate heat exchanger, condensate heating water, a condensate heating water inlet pipe, and a condensate heating water outlet pipe; the exhaust steam releases heat in the condensation heat exchanger to become condensate, and enters the condensate tank; a liquid level gauge is provided on the condensate tank to monitor the liquid level; a vacuum exhaust or exhaust system is provided on the top of the vacuum tank, and a condensate pump is provided at the bottom to discharge the condensate to the next process through the condensate drain pipe.

6. The power station auxiliary steam power and heat cogeneration gradient utilization energy-saving system according to claim 5 is characterized by: The condensate system can selectively utilize the heat of the condensate to exchange heat with the condensate heating water through a condensate heat exchanger before it is discharged to the next process, thereby raising the temperature of the condensate heating water and sending it to the next process.

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