A double extraction steam supply system and method based on ejector

Abstract

The present invention provides an ejector-based double-extraction steam supply system and method, comprising a boiler, a turbine intermediate-pressure cylinder, a back pressure machine and a steam boosting unit, wherein the main steam outlet of the boiler is respectively connected to the steam inlet of the back pressure machine and the steam inlet of the steam boosting unit; the outlet of the back pressure machine is connected to the inlet of the steam boosting unit; the reheat steam outlet of the boiler is connected to the reheat steam inlet of the turbine intermediate-pressure cylinder; the exhaust port of the turbine intermediate-pressure cylinder is connected to the inlet of the steam boosting unit; the reheat steam outlet of the boiler and the outlet of the steam boosting unit are also connected to a medium-pressure industrial steam pipeline; the exhaust port of the turbine intermediate-pressure cylinder and the outlet of the steam boosting unit are also connected to a low-pressure industrial steam pipeline; the system structure of the present invention is simple, the investment is small, and the adjustment is convenient.

Description

Technical Field

[0001] The invention belongs to the field of heating, and in particular relates to an ejector-based double-extraction steam supply system and method. Background Art

[0002] At present, the industrial structure and land use structure of cities in my country are constantly changing. The centralized construction of industrial parks for chemical, pharmaceutical, textile, steel and other industrial enterprises has become an inevitable trend in urban development. As an important carrier of industrial development, industrial parks play an increasingly important role in promoting the process of industrialization and promoting regional economic prosperity. For the reasonable planning and development of industrial parks, the construction of centralized heating systems to replace the small boiler rooms built by each enterprise has become the main way for enterprises to use heat in modern industrial parks. Centralized heating systems can not only significantly reduce the cost of steam use by enterprises, improve the reliability of heating, but also be more conducive to protecting the environment of the park.

[0003] Industrial centralized heating systems mostly use steam for heating for the following reasons: (1) Using steam as a heat transfer medium can make the heating system have a wider range of applications and meet the requirements of different heat users, as well as meet the needs of high-temperature steam disinfection; (2) Industrial parks often occupy a large area, and the distance between each heat user and the heat source can even be up to ten kilometers. Compared with hot water pipes, steam transportation does not require additional booster equipment and can meet the transportation needs by its own pressure, thereby saving energy; (3) Steam has the characteristics of high temperature and high pressure, and has a very high calorific value per unit mass. Therefore, a heat exchange system with a small heat dissipation area can be used, and the investment in heat exchange equipment is relatively small; (4) The friction resistance of steam in the pipeline is small, and the transmission efficiency is higher than that of the hot water pipe network. It can not only reduce losses along the way, but also has certain advantages in ensuring the heat quality of remote heat users.

[0004] Steam ejector is a hybrid booster device that can boost the pressure of low-pressure steam using the energy of high-pressure steam, and has significant energy-saving and emission-reduction effects. The ejector has the advantages of simple structure, low cost, energy-saving and environmental protection, low maintenance cost, and cascade utilization of energy, and is widely used in various industrial devices.

[0005] With the development of the global economy, energy and environmental protection, coal-fired power plants will face stricter environmental protection requirements and severe market operation situations. The double extraction steam cogeneration units are required to participate in peak load regulation. The quality of the heating steam output by the heating unit is directly related to the production process and safety of the heat-using enterprise industry, which puts higher requirements on the safety and reliability of steam transmission by the cogeneration unit. How to transform the unit to flexibly and efficiently meet the heating extraction parameter requirements while participating in peak load regulation is of great significance.

[0006] However, when the existing double-extraction steam cogeneration units participate in peak regulation and cause insufficient pressure of the heating steam source, they often directly switch to a higher pressure steam extraction point, resulting in poor parameter matching and low energy utilization. Summary of the invention

[0007] The object of the present invention is to provide a dual-extraction steam supply system and method based on an ejector, which solves the above-mentioned deficiencies in the prior art.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] The present invention provides an ejector-based double-extraction steam supply system, comprising a boiler, a steam turbine intermediate pressure cylinder, a back pressure machine and a steam boosting unit, wherein the main steam outlet of the boiler is connected to the steam inlet of the back pressure machine and the steam inlet of the steam boosting unit respectively;

[0010] The outlet of the back pressure machine is connected to the inlet of the steam boosting unit;

[0011] The reheat steam outlet of the boiler is connected to the reheat steam inlet of the intermediate pressure cylinder of the steam turbine; the exhaust port of the intermediate pressure cylinder of the steam turbine is connected to the inlet of the steam boosting unit;

[0012] The reheat steam outlet of the boiler and the outlet of the steam boosting unit are also connected to a medium-pressure industrial steam pipeline;

[0013] The exhaust port of the intermediate pressure cylinder of the steam turbine and the outlet of the steam boosting unit are also connected to a low-pressure industrial steam pipeline.

[0014] Preferably, the steam boosting unit includes a No. 1 ejector and a No. 2 ejector, wherein the main steam outlet of the boiler, the reheat steam outlet of the boiler and the outlet of the back pressure machine are all connected to the No. 1 ejector, and the steam outlet of the No. 1 ejector is connected to a medium-pressure industrial steam pipeline; the exhaust port of the medium-pressure cylinder of the steam turbine and the reheat steam outlet of the boiler are both connected to the No. 2 ejector, and the steam outlet of the No. 2 ejector is connected to a low-pressure industrial steam pipeline.

[0015] Preferably, the steam outlet of the No. 1 ejector is also connected to the No. 2 ejector, and a No. 6 valve is installed on the connecting pipeline between the two.

[0016] Preferably, a No. 2 valve is provided on the connecting pipe between the main steam outlet of the boiler and the No. 1 ejector; and a No. 4 valve is provided on the connecting pipe between the reheat steam outlet of the boiler and the No. 1 ejector.

[0017] Preferably, a No. 7 valve is provided on the connecting pipe between the reheat steam outlet of the boiler and the No. 2 ejector; and a No. 8 valve is provided on the connecting pipe between the exhaust port of the intermediate pressure cylinder of the steam turbine and the No. 2 ejector.

[0018] Preferably, a No. 1 valve is provided on the connecting pipe between the main steam outlet of the boiler and the back pressure machine.

[0019] Preferably, a No. 3 valve is provided on the connecting pipe between the reheat steam outlet of the boiler and the medium-pressure industrial steam pipeline.

[0020] Preferably, a No. 9 valve is provided on the connecting pipe between the exhaust port of the intermediate-pressure cylinder of the steam turbine and the low-pressure industrial steam pipeline.

[0021] A double extraction steam supply method based on an ejector, based on the double extraction steam supply system based on an ejector, comprises the following steps:

[0022] When the unit load is large, the boiler's reheat extraction steam is used to supply medium-pressure industrial steam; the exhaust steam from the turbine's medium-pressure cylinder is used to supply low-pressure industrial steam;

[0023] If the unit load is small, the main steam of the boiler enters the steam booster unit after doing work in the back pressure machine, and is used to inject the reheated steam from the reheated steam outlet of the boiler to form steam supply medium-pressure industrial steam that meets the steam supply pressure;

[0024] At the same time, the reheated steam of the boiler is sent to the steam boosting unit to be injected into the exhaust steam of the intermediate pressure cylinder exhaust port of the steam turbine, forming a steam supply low-pressure industrial steam that meets the steam supply pressure.

[0025] Preferably, if the steam after the back pressure machine does work is not enough to raise the steam pressure at the outlet of the No. 1 ejector to meet the medium-pressure industrial steam, the No. 2 valve is opened, and the main steam directly enters the No. 1 ejector to inject the steam from the boiler reheat steam outlet, forming steam that meets the steam supply pressure for steam supply;

[0026] If the reheat extraction steam is not sufficient to raise the steam pressure at the outlet of No. 2 ejector to meet the requirements of low-pressure industrial steam, close valve No. 7, open valve No. 6, and the steam at the outlet of No. 1 ejector will be used to draw the exhaust steam from the intermediate pressure cylinder of the turbine to form steam that meets the steam supply pressure for steam supply.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention provides an ejector-based double-extraction steam supply system and method, which adopts a steam ejector to assist in heating, and replaces a portion of high-grade steam with low-grade steam, thereby reducing heating costs. The present invention switches the steam supply source accordingly according to changes in the unit load, and cooperates with the ejector and the back pressure machine to enable the unit to reduce the consumption of high-parameter steam while meeting the heating parameters, reduce irreversible losses, and improve the energy utilization efficiency of the unit. The system structure of the present invention is simple, the investment is small, and the adjustment is convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic diagram of the system structure involved in the present invention;

[0030] Among them, 1-boiler, 2-turbine high-pressure cylinder, 3-turbine medium-pressure cylinder, 4-turbine low-pressure cylinder, 5-condenser, 6-condensate pump, 7-low-pressure heater group, 8-deaerator, 9-feedwater pump, 10-high-pressure heater group, 11-valve No. 1, 12-valve No. 2, 13-valve No. 3, 14-valve No. 4, 16-valve No. 6, 17-valve No. 7, 18-valve No. 8, 19-valve No. 9, 20-valve No. 10, 21-back pressure machine, 24-ejector No. 1, 25-ejector No. 2, 26-valve No. 11. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0032] like Figure 1 As shown, the present invention provides an ejector-based double-extraction steam supply system, comprising a boiler 1, a turbine high-pressure cylinder 2, a turbine medium-pressure cylinder 3, a turbine low-pressure cylinder 4, a condenser 5, a condensate pump 6, a low-pressure heater group 7, a deaerator 8, a feed water pump 9, a high-pressure heater group 10, a valve No. 1 11, a valve No. 2 12, a valve No. 3 13, a valve No. 4 14, a valve No. 6 16, a valve No. 7 17, a valve No. 8 18, a valve No. 9 19, a valve No. 10 20, a back pressure machine 21, an ejector No. 1 24, an ejector No. 25 and a valve No. 11 26, wherein the main steam outlet of the boiler 1 is divided into three routes, one of which is connected to the inlet of the back pressure machine 21, and the connecting pipeline between the two is installed with the valve No. 11; the second route is connected to the inlet of the ejector No. 24, and the connecting pipeline between the two is installed with the valve No. 2 12; the remaining route is connected to the inlet of the turbine high-pressure cylinder 2; and the connecting pipeline between the two is installed with the valve No. 11 26.

[0033] The outlet of the back pressure machine 21 is connected to the inlet of the first injector 24 .

[0034] The reheat steam outlet of the boiler 1 is divided into four routes, one of which is connected to the first pipeline A1, on which the No. 3 valve 13 is installed; the second route is connected to the inlet of the No. 1 ejector 24, and the No. 4 valve 14 is installed on the connecting pipeline between the two; the third route is connected to the inlet of the No. 2 ejector 25, and the No. 7 valve 17 is installed on the connecting pipeline between the two; the remaining route is connected to the steam inlet of the turbine intermediate pressure cylinder 3.

[0035] The outlet of the No. 1 injector 24 is connected to the inlet of the No. 2 injector 25, and a No. 6 valve 16 is installed on the connecting pipeline between the two.

[0036] The exhaust port of the steam turbine intermediate pressure cylinder 3 is divided into three routes, one of which is connected to the inlet of the No. 2 ejector 25, and a No. 8 valve 18 is installed on the connecting pipeline between the two; the second route is connected to the second pipeline B1, and a No. 9 valve 19 is installed on the second pipeline B1; the remaining route is connected to the inlet of the steam turbine low pressure cylinder 4, and a No. 10 valve 20 is installed on the connecting pipeline between the two.

[0037] The outlet of the second injector is connected to the third pipeline B2.

[0038] The back pressure machine 21 can drive a generator to generate electricity, which is then incorporated into the factory electricity to reduce the factory electricity consumption rate.

[0039] The exhaust port of the low-pressure cylinder 4 of the steam turbine is connected to a condenser 5, and the condensate outlet of the condenser 5 is connected to a low-pressure heater group 7 through a condensate pump 6. The outlet of the low-pressure heater group 7 is connected to the water inlet of the boiler 1 through a deaerator 8, a feed water pump 9 and a high-pressure heater group 10 in sequence.

[0040] Working process of the present invention:

[0041] When the unit load is large, medium-pressure industrial steam is supplied through the first pipeline A1, i.e., reheat extraction steam;

[0042] If the unit is running at low load and the pressure at the first pipeline A1 is insufficient, the back pressure machine 21 and the No. 1 ejector 24 are activated to meet the medium-pressure industrial steam; the function of the No. 1 ejector 24 is as follows: the main steam of the boiler 1 enters the No. 1 ejector 24 after doing work in the back pressure machine 21, and is used to inject the reheated steam from the reheated steam outlet of the boiler 1 to form steam that meets the steam supply pressure; if the steam after the back pressure machine 21 does work is not enough to increase the steam pressure at the outlet of the No. 1 ejector 24 to meet the medium-pressure industrial steam, open the No. 2 valve 12, and the main steam directly enters the No. 1 ejector 24 to inject the steam from the reheated steam outlet of the boiler 1 to form steam that meets the steam supply pressure for steam supply;

[0043] When the unit load is high, low-pressure industrial steam is supplied through the first pipeline B1, i.e., the exhaust steam from the intermediate pressure cylinder of the steam turbine;

[0044] If the unit is running at a low load and the pressure at the first pipeline B1 is insufficient, open valve No. 7 17, enable ejector No. 2 25 to supply low-pressure industrial steam through the third pipeline B2, and use the reheat steam extraction to inject the exhaust steam from the intermediate pressure cylinder of the steam turbine to form steam that meets the steam supply pressure; if the reheat steam extraction is not enough to increase the steam pressure at the outlet of ejector No. 2 25 to meet the low-pressure industrial steam pressure, close valve No. 7 17, open valve No. 6 16, and use the steam at the outlet of ejector No. 1 24 to inject the exhaust steam from the intermediate pressure cylinder of the steam turbine to form steam that meets the steam supply pressure.

Claims

1. A double extraction steam supply system based on ejector, characterized in that: It comprises a boiler (1), a steam turbine intermediate pressure cylinder (3), a back pressure machine (21) and a steam boosting unit, wherein the main steam outlet of the boiler (1) is connected to the steam inlet of the back pressure machine (21) and the steam inlet of the steam boosting unit respectively; The outlet of the back pressure machine (21) is connected to the inlet of the steam boosting unit; The reheat steam outlet of the boiler (1) is connected to the reheat steam inlet of the steam turbine intermediate pressure cylinder (3); the exhaust port of the steam turbine intermediate pressure cylinder (3) is connected to the inlet of the steam boosting unit; The reheat steam outlet of the boiler (1) and the outlet of the steam boosting unit are also connected to a medium-pressure industrial steam pipeline; The steam exhaust port of the steam turbine intermediate pressure cylinder (3) and the outlet of the steam boosting unit are also connected to a low-pressure industrial steam pipeline; The steam boosting unit comprises a No. 1 ejector (24) and a No. 2 ejector (25), wherein the main steam outlet of the boiler (1), the reheat steam outlet of the boiler (1) and the outlet of the back pressure machine (21) are all connected to the No. 1 ejector (24), and the steam outlet of the No. 1 ejector (24) is connected to a medium-pressure industrial steam pipeline; the exhaust port of the medium-pressure cylinder (3) of the steam turbine and the reheat steam outlet of the boiler (1) are all connected to the No. 2 ejector (25), and the steam outlet of the No. 2 ejector (25) is connected to a low-pressure industrial steam pipeline; The steam outlet of the No. 1 ejector (24) is also connected to the No. 2 ejector (25), and a No. 6 valve (16) is installed on the connecting pipeline between the two; A No. 2 valve (12) is provided on the connecting pipe between the main steam outlet of the boiler (1) and the No. 1 ejector (24); a No. 4 valve (14) is provided on the connecting pipe between the reheat steam outlet of the boiler (1) and the No. 1 ejector (24); A No. 7 valve (17) is provided on the connecting pipe between the reheat steam outlet of the boiler (1) and the No. 2 ejector (25); and a No. 8 valve (18) is provided on the connecting pipe between the exhaust port of the intermediate pressure cylinder (3) of the steam turbine and the No. 2 ejector (25).

2. The double extraction steam supply system based on ejector according to claim 1, characterized in that: A valve (11) is provided on the connecting pipe between the main steam outlet of the boiler (1) and the back pressure machine (21).

3. The double extraction steam supply system based on ejector according to claim 1, characterized in that: A No. 3 valve (13) is provided on the connecting pipe between the reheat steam outlet of the boiler (1) and the medium-pressure industrial steam pipeline.

4. The double extraction steam supply system based on ejector according to claim 1, characterized in that: A No. 9 valve (19) is provided on the connecting pipe between the exhaust port of the medium-pressure cylinder (3) of the steam turbine and the low-pressure industrial steam pipeline.

5. A double extraction steam supply method based on ejector, characterized in that: A dual extraction steam supply system based on an ejector according to any one of claims 1 to 4 comprises the following steps: When the load of the unit is relatively large, the reheat extraction steam of the boiler (1) is used to supply medium-pressure industrial steam; and the exhaust steam of the medium-pressure cylinder (3) of the steam turbine is used to supply low-pressure industrial steam. If the unit load is relatively small, the main steam of the boiler (1) enters the steam boosting unit after doing work in the back pressure machine (21), and is used to inject the reheated steam from the reheated steam outlet of the boiler (1) to form steam supply medium-pressure industrial steam that meets the steam supply pressure; At the same time, the reheated steam of the boiler (1) is sent to the steam boosting unit to be used for introducing the exhaust steam into the exhaust port of the intermediate pressure cylinder (3) of the steam turbine, thereby forming a steam supply low-pressure industrial steam that meets the steam supply pressure.

6. The double extraction steam supply method based on ejector according to claim 5, characterized in that: If the steam after work by the back pressure machine (21) is not enough to raise the steam pressure at the outlet of the No. 1 ejector (24) to meet the medium-pressure industrial steam, the No. 2 valve (12) is opened, and the main steam directly enters the No. 1 ejector (24) to be used to inject the steam from the reheat steam outlet of the boiler (1), so as to form steam that meets the steam supply pressure for steam supply; If the reheat extraction steam is insufficient to raise the steam pressure at the outlet of the No. 2 ejector (25) to meet the requirements of low-pressure industrial steam, the No. 7 valve (17) is closed and the No. 6 valve (16) is opened. The steam at the outlet of the No. 1 ejector (24) is ejected into the exhaust steam of the intermediate pressure cylinder of the steam turbine to form steam that meets the steam supply pressure for steam supply.

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