CN110793007A - Reheating steam combined middle-exhaust steam heating water supply and heat supply system and method - Google Patents

Abstract

The invention provides a reheat steam combined middle-exhaust steam heating water supply heating system, including a pure condensing turbine thermal power generating unit and a combined heating system; the pure condensing turbine thermal power generating unit mainly includes a boiler, a steam turbine high-pressure cylinder, a steam turbine Medium pressure cylinder, steam turbine low pressure cylinder, high pressure heater, deaerator, low pressure heater, condenser, feedwater prepump, steam-driven feedwater pump; the combined heating system mainly includes a first-level surface feedwater heater, steam Generator, secondary surface steam heater. The invention provides a method for heating feed water with reheat steam combined with middle-row steam heating. The invention utilizes the superheat degree of the middle-exhaust steam, the steam exhaust volume of the unit is smaller, the cold end loss is smaller, the unit efficiency is higher, and the energy level gradient utilization is more reasonable; More stable and less volatile. The system structure is reasonable, the system is reliable, the load adaptability is good, and the host safety is high.

Description

A kind of reheat steam combined middle-exhaust steam heating feed water heating system and method

technical field

The invention belongs to the technical field of energy, and in particular relates to a new energy-saving steam combined water supply heating system and method.

Background technique

In order to improve the economy of the unit and respond to the national call for energy conservation and emission reduction, at present, most domestic thermal power units have undergone technological transformation, and they are extracting steam for heat supply to the outside world.

The improvement of the economical efficiency of thermal power units is related to many factors such as extraction parameters, extraction volume, extraction location and so on. Under the premise of the same heating demand, choosing the most economical steam extraction scheme suitable for the unit is the focus of research on thermal systems.

At present, the conventional heating method is to select a number of steam extraction sources, and use the direct water spray throttling method to reduce temperature and pressure according to the parameter requirements, and supply heat to the outside. This heating method has the following defects: large exhaust steam volume of the unit, large cold end loss, low unit efficiency, and unreasonable utilization of energy level gradient; the heating parameters of water spray heat exchange are unstable and fluctuate greatly.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a steam extraction heating system with reasonable structure, reliable system, good load adaptability, small fluctuation of heating parameters and high safety of the main engine.

In order to solve the above-mentioned technical problems, the technical scheme of the present invention is to provide a reheat steam combined middle-exhaust steam heating water supply heating system, which is characterized in that: it includes a pure condensing turbine thermal power generating unit and a combined heating system;

The pure condensing turbine thermal power generating unit comprises a boiler, the steam outlet of the boiler is connected to the inlet of the high-pressure cylinder of the steam turbine, the outlet of the high-pressure cylinder of the steam turbine is connected to the inlet of the reheated steam of the boiler, the outlet of the reheated steam of the boiler is connected to the inlet of the middle-pressure cylinder of the steam turbine, and the outlet of the middle-pressure cylinder of the steam turbine is connected to the inlet of the steam turbine. The inlet of the low-pressure cylinder of the steam turbine, the outlet of the low-pressure cylinder of the steam turbine is connected to the inlet of the condenser, the outlet of the condenser is connected to the inlet of the low-pressure heater, the outlet of the low-pressure heater is connected to the inlet of the deaerator, and the outlet of the deaerator is connected to the inlet of the high-pressure heater , the outlet of this side of the high-pressure heater is connected to the steam inlet of the boiler;

The combined heating system comprises a primary surface feedwater heater, the low temperature side inlet of the primary surface feedwater heater is connected to the outlet of the deaerator, and the low temperature side outlet of the primary surface feedwater heater is connected to the steam generator inlet, The high temperature side inlet of the primary surface feedwater heater is connected to the outlet of the medium pressure cylinder of the steam turbine, the high temperature side outlet of the primary surface feedwater heater is connected to the deaerator inlet; the steam generator outlet is connected to the low temperature side of the secondary surface saturated steam heater Inlet, the high temperature side inlet of the secondary surface saturated steam heater is connected to the outlet of the high pressure cylinder of the steam turbine and/or the inlet of the middle pressure cylinder of the steam turbine, the high temperature side outlet of the secondary surface saturated steam heater is connected to the inlet of the steam generator, and the secondary surface saturated steam heater is connected to the inlet of the steam generator. The low temperature side outlet of the surface saturated steam heater is connected to the external heating pipeline.

Preferably, the outlet of the deaerator is connected to the inlet of the feedwater prepump, the outlet of the feedwater prepump is connected to the inlet of the steam-powered feed pump, and the outlet of the steam-powered feed pump is connected to the inlet on one side of the high-pressure heater.

More preferably, the low temperature side inlet of the first-stage surface feedwater heater is connected to the outlet of the feedwater prepump.

Preferably, the first-stage surface feedwater heater uses the middle row steam at the outlet of the middle pressure cylinder of the steam turbine to heat part of the feedwater at the outlet of the deaerator once; the middle row steam is cooled and then led to the Deaerator.

More preferably, the steam generator uses the reheated steam after heat exchange by the secondary surface type steam heater to perform mixed secondary heating on the feedwater at the outlet of the primary surface type feedwater heater, and heat it. Evaporates to saturated steam.

Further, the secondary surface type steam heater uses the reheated steam at the outlet of the high-pressure cylinder of the steam turbine and/or the inlet of the medium-pressure cylinder to heat the saturated steam at the outlet of the steam generator three times; The superheated steam heated by the secondary surface steam heater supplies external heat.

The present invention also provides a method for heating feed water with reheated steam combined with middle-row steam, which is characterized in that: adopting the above-mentioned reheated steam combined with middle-row steam to heat the water supply heating system, comprising the following steps:

Step 1: The low-pressure feed water is surface-heated once by the middle-row steam;

The low-pressure feed water is drawn from the outlet of the deaerator, and the low-pressure feed water is first surface-heated by a first-stage surface feed water heater, and the heating heat source is the middle-exhaust steam at the outlet of the middle-pressure cylinder of the steam turbine;

Step 2: The low pressure feed water is mixed and heated by the reheated steam for a second time;

The low-pressure feed water heated in step 1 enters the steam generator, and the heating source of the steam generator is the reheated steam after heat exchange by the secondary surface saturated steam heater; in the steam generator, the low-pressure feed water heated in step 1 The feed water is mixed and heated by the reheated steam and evaporated into saturated steam;

Step 3: Saturated steam is surface-heated three times by reheated steam;

The saturated steam generated in step 2 enters the secondary surface type saturated steam heater, and is heated to superheated steam for external heating; the heating source of the secondary surface type saturated steam heater is the outlet of the high pressure cylinder of the steam turbine and/or the inlet of the middle pressure cylinder of the steam turbine. Reheat steam.

Compared with the traditional steam extraction and direct desuperheating and decompression heating system, the reheat steam combined middle-exhaust steam heating water supply heating system provided by the present invention has the following beneficial effects:

1. Using the superheat degree of the middle exhaust steam, the exhaust steam volume of the unit is smaller, the cold end loss is smaller, the unit efficiency is higher, and the energy level gradient utilization is more reasonable;

2. Using the evaporator to replace the direct water spray heat exchange, the heating parameters are more stable and the fluctuation is small.

3. Reasonable structure, reliable system, good load adaptability and high host safety.

Description of drawings

1 is a schematic diagram of a reheat steam combined middle-row steam heating feed water heating system provided by the present embodiment;

Description of reference numbers:

1—boiler, 2—turbine high pressure cylinder, 3—steam turbine medium pressure cylinder, 4—steam turbine low pressure cylinder, 5—high pressure heater, 6—deaerator, 7—low pressure heater, 8—condenser, 9—feed water Front pump, 10—steam-driven feed water pump, 11—first-level surface feedwater heater, 12—steam generator, 13—secondary surface-type saturated steam heater.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments.

1 is a schematic diagram of the reheat steam combined middle row steam heating feed water heating system provided by the present embodiment, the reheat steam combined middle row steam heating feed water heating system includes a boiler 1, a steam turbine high pressure cylinder 2, a steam turbine middle pressure cylinder 3. Turbine low-pressure cylinder 4, high-pressure heater 5, deaerator 6, low-pressure heater 7, condenser 8, feedwater prepump 9, steam-driven feedwater pump 10, primary surface feedwater heater 11, steam generator 12, secondary surface saturated steam heater 13, etc.

Among them, boiler 1, steam turbine high pressure cylinder 2, steam turbine medium pressure cylinder 3, steam turbine low pressure cylinder 4, high pressure heater 5, deaerator 6, low pressure heater 7, condenser 8, feed water prepump 9, steam power supply The water pumps 10 together constitute a conventional pure condensing turbine thermal power generating unit.

The primary surface type feed water heater 11, the steam generator 12, and the secondary surface type saturated steam heater 13 together constitute a combined heating system. The combined heating system uses the middle exhaust steam and reheat steam of the pure condensing turbine thermal power generating unit to heat the low-pressure feed water to superheated steam, and supply heat to the outside.

The specific structure is as follows:

The pure condensing turbine thermal power generating set includes boiler 1, the steam outlet of boiler 1 is connected to the inlet of high pressure cylinder 2 of the steam turbine, the outlet of the high pressure cylinder 2 of the steam turbine is connected to the reheat steam inlet of boiler 1, the reheat steam outlet of boiler 1 is connected to the inlet of the middle pressure cylinder 3 of the steam turbine, and the steam turbine The outlet of the medium pressure cylinder 3 is connected to the inlet of the low pressure cylinder 4 of the steam turbine, the outlet of the low pressure cylinder 4 of the steam turbine is connected to the inlet of the condenser 8, the outlet of the condenser 8 is connected to the inlet of the low pressure heater 7, and the outlet of the low pressure heater 7 is connected to the deaerator 6 The inlet, the outlet of the deaerator 6 is connected to the inlet of the feed water prepump 9, the outlet of the feed water prep The outlet is connected to the steam inlet of boiler 1.

The combined heating system includes a primary surface feedwater heater 11, the low temperature side inlet of the primary surface feedwater heater 11 is connected to the outlet of the feedwater prepump 9, and the low temperature side outlet of the primary surface feedwater heater 11 is connected to the steam generator 12. At the inlet, the high temperature side inlet of the primary surface feedwater heater 11 is connected to the outlet of the middle pressure cylinder 3 of the steam turbine, and the high temperature side outlet of the primary surface feedwater heater 11 is connected to the inlet of the deaerator 6 . The outlet of the steam generator 12 is connected to the low temperature side inlet of the secondary surface type saturated steam heater 13, and the high temperature side inlet of the secondary surface type saturated steam heater 13 is connected to the outlet of the high pressure cylinder 2 of the steam turbine and/or the inlet of the medium pressure cylinder 3 of the steam turbine. The outlet of the high temperature side of the type saturated steam heater 13 is connected to the inlet of the steam generator 12, and the outlet of the low temperature side of the secondary surface type saturated steam heater 13 is connected to the external heating pipeline.

In this embodiment, the heated working fluid of the first-stage surface feedwater heater 11 is taken from the low-pressure feedwater at the outlet of the deaerator 6, and then led to the steam generator 12 after heating, and the heating working fluid is taken from the outlet of the middle pressure cylinder 3 of the steam turbine. The steam is discharged in the middle, and is led to the deaerator 6 after heat exchange.

The heated working fluid of the secondary surface saturated steam heater 13 comes from the saturated steam at the outlet of the steam generator 12, and the saturated steam is heated to superheat to supply external heat. 3 The imported reheated steam is led to the steam generator 12 after heat exchange.

The heated working fluid of the steam generator 12 comes from the low-pressure feed water at the outlet of the primary surface feed water heater 11, the heating working fluid is taken from the reheated steam at the outlet of the secondary surface saturated steam heater 13, and the low-pressure feed water is supplied to the steam generator 12. It is mixed with reheated steam and heated into saturated steam and then led to the secondary surface type saturated steam heater 13 .

The working process of the reheat steam combined middle-exhaust steam heating water supply heating system provided by this embodiment is as follows:

The heated medium in the working process is low-pressure feed water, and the heating medium is the middle row steam and the reheated steam. The work process is mainly divided into three processes.

In the first process, the low-pressure feed water is surface-heated by the middle-exhaust steam. The low-pressure feedwater of the system is drawn from the outlet main pipe of the feedwater prepump 9, and the low-pressure feedwater first passes through the primary surface feedwater heater 11 for primary surface heating. The heating heat source is the middle exhaust steam from the outlet of the middle pressure cylinder 3 of the steam turbine.

In the second process, the low-pressure feed water is mixed and heated by the reheated steam. The low-pressure feed water heated by the first process enters the steam generator 12, and the heat source of this process is the reheated steam after heat exchange in the third process. In the steam generator 12, the low pressure feed water is mixed and heated by the reheated steam and evaporated into saturated steam.

In the third process, the saturated steam is surface-heated three times by the reheated steam. The saturated steam generated in the second process enters the secondary surface saturated steam heater 13, and is heated to superheated steam for external heating. The heating source is the reheated steam at the outlet of the high pressure cylinder 2 of the steam turbine or the inlet of the middle pressure cylinder 3 of the steam turbine.

The reheat steam combined middle row steam heating feed water heating system provided by the present invention first uses the superheat degree of the middle row steam to heat the feed water and then enters the steam generator. The evaporation heat source of the steam generator adopts reheat steam, and the superheat degree of the reheat steam is first It is used for superheat absorption of saturated steam at the steamer outlet, and then enters the evaporator to provide the latent heat required for the conversion of saturated water to saturated steam. Compared with the direct desuperheating and decompression heating system of extraction steam, this system utilizes the superheat degree of the middle exhaust steam, the exhaust steam volume of the unit is smaller, the cold end loss is smaller, the unit efficiency is higher, and the utilization of energy level gradient is more reasonable. .

Compared with the direct desuperheating and decompression heating system with steam extraction, this system uses the evaporator to replace the direct water spray heat exchange, and the heating parameters are more stable and the fluctuation is small. Taking the 600MW steam turbine generator set as an example to supply 400t/h of external heat, after the application of this system, the coal consumption of the unit for power generation is reduced by 4.5g/kWh, the annual power generation is 3300 million kWh, the annual coal saving is 14850t, and the unit price of standard coal is based on 800 yuan / t, the annual increase in gross income is about 11.88 million yuan.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention in any form or substance. It should be pointed out that for those skilled in the art, without departing from the method of the present invention, the Several improvements and supplements can be made, and these improvements and supplements should also be regarded as the protection scope of the present invention. All those skilled in the art, without departing from the spirit and scope of the present invention, can utilize the above-disclosed technical content to make some changes, modifications and equivalent changes of evolution, all belong to the present invention. Equivalent embodiments; at the same time, any modification, modification and evolution of any equivalent changes made to the above embodiments according to the essential technology of the present invention still fall within the scope of the technical solutions of the present invention.

Claims (7)

1. a reheat steam combined middle row steam heating water supply heating system, is characterized in that: comprise pure condensing steam turbine thermal power generating unit and combined heating system; The pure condensing turbine thermal power generating set comprises a boiler (1), the steam outlet of the boiler (1) is connected to the inlet of a high-pressure cylinder (2) of the steam turbine, and the outlet of the high-pressure cylinder (2) of the steam turbine is connected to the reheat steam inlet of the boiler (1), and the boiler (1) ) The outlet of the reheated steam is connected to the inlet of the middle pressure cylinder (3) of the steam turbine, the outlet of the middle pressure cylinder (3) of the steam turbine is connected to the inlet of the low pressure cylinder (4) of the steam turbine, and the outlet of the low pressure cylinder (4) of the steam turbine is connected to the inlet of the condenser (8). The outlet of the deaerator (8) is connected to the inlet of the low-pressure heater (7), the outlet of the low-pressure heater (7) is connected to the inlet of the deaerator (6), and the outlet of the deaerator (6) is connected to the side of the high-pressure heater (5). Inlet, the side outlet of the high pressure heater (5) is connected to the steam inlet of the boiler (1); The combined heating system includes a primary surface feed water heater (11), the low temperature side inlet of the primary surface feed water heater (11) is connected to the outlet of the deaerator (6), and the primary surface feed water heater (11) The outlet on the low temperature side is connected to the inlet of the steam generator (12), the inlet on the high temperature side of the primary surface feedwater heater (11) is connected to the outlet of the middle pressure cylinder (3) of the steam turbine, and the primary surface feedwater heater (11) The outlet of the high temperature side is connected to the inlet of the deaerator (6); the outlet of the steam generator (12) is connected to the inlet of the low temperature side of the secondary surface saturated steam heater (13), and the inlet of the high temperature side of the secondary surface saturated steam heater (13) is connected The outlet of the high pressure cylinder (2) of the steam turbine and/or the inlet of the medium pressure cylinder (3) of the steam turbine, the high temperature side outlet of the secondary surface saturated steam heater (13) is connected to the inlet of the steam generator (12), and the secondary surface type saturated steam heater (13) is connected to the inlet of the steam generator (12). The outlet of the low temperature side of the saturated steam heater (13) is connected to an external heating pipeline. 2. The reheat steam combined middle-exhaust steam heating feed water heating system as claimed in claim 1, wherein the outlet of the deaerator (6) is connected to the inlet of the feed water prepump (9), and the feed water prepump The outlet of the pump (9) is connected to the inlet of the steam-powered feed water pump (10), and the outlet of the steam-powered feed pump (10) is connected to the inlet of one side of the high-pressure heater (5). 3. The reheat steam combined middle-row steam heating feed water heating system according to claim 2, characterized in that: the low temperature side inlet of the first-stage surface feed water heater (11) is connected to the feed water prepump (9) EXPORT. 4. The reheat steam combined middle-exhaust steam heating feed water heating system according to any one of claims 1 to 3, characterized in that: the first-stage surface feed water heater (11) utilizes the steam in the steam turbine The middle row steam at the outlet of the pressure cylinder (3) heats part of the feed water at the outlet of the deaerator (6) once; the middle row steam is cooled and then led to the deaerator (6). 5. The reheat steam combined middle-exhaust steam heating feed water heating system according to claim 4, characterized in that: the steam generator (12) utilizes the secondary surface type steam heater (13) The reheated steam after heat exchange performs mixed secondary heating on the feed water at the outlet of the primary surface feed water heater (11), and evaporates it into saturated steam. 6. The reheat steam combined middle-exhaust steam heating feed water heating system according to claim 5, characterized in that: the secondary surface type steam heater (13) utilizes the outlet of the steam turbine high-pressure cylinder (2) And/or the reheated steam at the inlet of the medium pressure cylinder (3), the saturated steam at the outlet of the steam generator (12) is heated three times; Superheated steam provides external heat. 7. A method for heating feed water with reheated steam combined with middle row steam, characterized in that: adopting the reheat steam combined middle row steam heating feed water heating system according to any one of claims 1 to 6, comprising the following steps : Step 1: The low-pressure feed water is surface-heated once by the middle-row steam; The low-pressure feedwater is drawn from the outlet of the deaerator (6), and the low-pressure feedwater is first surface-heated through a first-stage surface-type feedwater heater (11), and the heating heat source is the middle-discharge steam from the outlet of the middle-pressure cylinder (3) of the steam turbine; Step 2: The low pressure feed water is mixed and heated by the reheated steam for a second time; The low-pressure feed water heated in step 1 enters the steam generator (12), and the heating heat source of the steam generator (12) is the reheated steam after heat exchange by the secondary surface saturated steam heater (13); In (12), the low-pressure feedwater heated in step 1 is mixed and heated by the reheated steam, and evaporated into saturated steam; Step 3: Saturated steam is surface-heated three times by reheated steam; The saturated steam generated in step 2 enters the secondary surface saturated steam heater (13), and is heated to the superheated steam for external heating; the heating heat source of the secondary surface saturated steam heater (13) is the outlet of the high-pressure cylinder (2) of the steam turbine and/or reheated steam at the inlet of the turbine intermediate pressure cylinder (3).

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