阅读说明：本技术 一种空冷机组切除低压缸时汽轮机冷端防冻系统及方法 (Anti-freezing system and method for cold end of steam turbine when low-pressure cylinder of air cooling unit is cut off ) 是由 郑立军 陈飞飞 马斯鸣 阮宇雯 谢正超 王永学 于 2020-05-18 设计创作，主要内容包括：本发明公开了一种空冷机组切除低压缸时汽轮机冷端防冻系统及方法,属于热电联产技术领域,现在还没有一种能够有效实现空冷塔在极低乏汽流量下防冻的系统。本发明的系统包括空冷型汽轮机、乏汽管道、空冷塔隔离阀门、空冷塔、凝结水管道、冷凝器隔离阀门和冷凝器,空冷型汽轮机的乏汽出口通过乏汽管道分别与空冷塔隔离阀门的进口和冷凝器隔离阀门的进口连接,空冷塔隔离阀门的出口与空冷塔的乏汽进口连接,空冷塔的凝结水出口与凝结水管道连接,冷凝器隔离阀门的出口与冷凝器的汽侧进口连接,冷凝器的汽侧出口旁接在凝结水管道上。本发明可靠性高,经济效益好,能够很好地解决在极低乏汽流量工况下汽轮机冷端的防冻问题。(The invention discloses a system and a method for preventing freezing of a cold end of a steam turbine when an air cooling unit cuts off a low-pressure cylinder, belongs to the technical field of cogeneration, and does not have a system capable of effectively preventing freezing of an air cooling tower under extremely low exhaust steam flow. The system comprises an air cooling type steam turbine, a steam exhaust pipeline, an air cooling tower isolation valve, an air cooling tower, a condensed water pipeline, a condenser isolation valve and a condenser, wherein a steam exhaust outlet of the air cooling type steam turbine is respectively connected with an inlet of the air cooling tower isolation valve and an inlet of the condenser isolation valve through the steam exhaust pipeline, an outlet of the air cooling tower isolation valve is connected with a steam exhaust inlet of the air cooling tower, a condensed water outlet of the air cooling tower is connected with the condensed water pipeline, an outlet of the condenser isolation valve is connected with a steam side inlet of the condenser, and a steam side outlet of the condenser is connected to the condensed water pipeline in a bypassing mode. The invention has high reliability and good economic benefit, and can well solve the problem of freezing prevention of the cold end of the steam turbine under the working condition of extremely low exhaust steam flow.)

1. The utility model provides a steam turbine cold junction system that prevents frostbite when air cooling unit excision low pressure jar, includes air cooling type steam turbine (1), its characterized in that: the system also comprises a steam exhaust pipeline (2), an air cooling tower isolation valve (3), an air cooling tower (4), a condensed water pipeline (5), a condenser isolation valve (6), a condenser (7), a raw water pipeline (9), a raw water heating valve (10), a demineralized water treatment device (11), a demineralized water pipeline (12), a raw water bypass valve (13), a low-pressure cylinder steam extraction pipeline (14) and a steam extraction adjusting valve (15); the exhaust steam outlet of the air cooling type steam turbine (1) is respectively connected with the inlet of an air cooling tower isolation valve (3) and the inlet of a condenser isolation valve (6) through an exhaust steam pipeline (2), the outlet of the air cooling tower isolation valve (3) is connected with the exhaust steam inlet of an air cooling tower (4), the condensed water outlet of the air cooling tower (4) is connected with a condensed water pipeline (5), the outlet of the condenser isolation valve (6) is connected with the steam side inlet of a condenser (7), and the steam side outlet of the condenser (7) is connected to the condensed water pipeline (5) in a bypassing manner; the raw water pipeline (9) is respectively connected with an inlet of a raw water heating valve (10) and an inlet of a raw water bypass valve (13), an outlet of the raw water heating valve (10) is connected with a water side inlet of a condenser (7), a water side outlet of the condenser (7) is connected with a raw water inlet of a desalted water treatment device (11), an outlet of the desalted water treatment device (11) is connected with a desalted water pipeline (12), and an outlet of the raw water bypass valve (13) is also connected with a raw water inlet of the desalted water treatment device (11); the extraction outlet of the air cooling type steam turbine (1) is connected with the inlet of an extraction regulating valve (15) through a low-pressure cylinder extraction pipeline (14), and the outlet of the extraction regulating valve (15) is connected with the extraction inlet of the condenser (7).

2. The anti-freezing system for the cold end of the steam turbine when the air cooling unit removes the low-pressure cylinder according to claim 1, wherein: the condenser is characterized by further comprising a temperature monitoring device (8), wherein the temperature monitoring device (8) is installed at a condensed water outlet of the condenser (7).

3. The anti-freezing system for the cold end of the steam turbine when the air cooling unit removes the low-pressure cylinder according to claim 1, wherein: the air cooling type steam turbine (1) is a steam turbine with a condensed extraction back modified.

4. The anti-freezing system for the cold end of the steam turbine when the air cooling unit removes the low-pressure cylinder according to claim 1, wherein: and the air cooling tower isolation valve (3) and the condenser isolation valve (6) are automatic zero-leakage valves.

5. The anti-freezing system for the cold end of the steam turbine when the air cooling unit removes the low-pressure cylinder according to claim 1, wherein: the raw water heating valve (10) and the raw water bypass valve (13) are controlled by the temperature of condensed water, the opening of the valve can be automatically adjusted according to a set value, and the back pressure operation of the steam turbine is guaranteed within a reasonable range.

6. The anti-freezing system for the cold end of the steam turbine when the air cooling unit removes the low-pressure cylinder according to claim 1, wherein: the demineralized water treatment device (11) is a water quality treatment device utilizing the reverse osmosis principle.

7. An operating method of a cold end anti-freezing system of a steam turbine when a low pressure cylinder is cut off by an air cooling unit according to any one of claims 1 to 6, is characterized in that: the operation steps are as follows:

1) under a normal working condition, the air cooling type steam turbine (1) is in a pure condensation or extraction operation working condition, the air cooling tower (4) does not have the anti-freezing problem, at the moment, exhaust steam of the air cooling type steam turbine (1) is discharged into the air cooling tower (4), condensed water flows out from a condensed water pipeline (5), an air cooling tower isolation valve (3) is in an open state, and a condenser isolation valve (6) is in a completely closed state; if the raw water does not need to be heated, the steam extraction regulating valve (15) and the raw water heating valve (10) are in a closed state, the raw water bypass valve (13) is in an open state, the raw water directly enters the desalted water treatment device (11) without entering the condenser (7), and then is sent out through the desalted water pipeline (12); if raw water needs to be heated, the steam extraction regulating valve (15) and the raw water heating valve (10) are in an open state, the raw water bypass valve (13) is in a closed state, the raw water enters the condenser (7) and is heated by steam extraction to ensure the water production efficiency, the raw water passes through the desalted water treatment device (11) and then is discharged through the desalted water pipeline (12), and condensed water of steam extraction flows out of the condensed water pipeline (5);

2) under the anti-freezing working condition, the low-pressure cylinder of the air-cooling type steam turbine (1) is cut off to operate, at the moment, the flow of exhaust steam is extremely low and is not suitable for being sent to the air-cooling tower (4) for cooling, so that the isolation valve (3) of the air-cooling tower is in a completely closed state, the air-cooling tower (4) stops working, the isolation valve (6) of the condenser is in an open state, the exhaust steam is sent to the condenser (7) for condensation, and condensed water flows out from the condensed water pipeline (5); in order to keep the back pressure of the steam turbine within a reasonable range, the steam extraction regulating valve (15) is also completely closed, meanwhile, the temperature monitoring device (8) is used for measuring the temperature of a condensed water outlet of the condenser (7), the opening degrees of the raw water heating valve (10) and the raw water bypass valve (13) are adjusted in a linkage mode according to a set value, the purpose of reasonably controlling the back pressure of the steam turbine is achieved, all or part of raw water is sent to the condenser (7) to be heated according to conditions, then the heated and unheated raw water is sent to the demineralized water treatment device (11), and the treated demineralized water is sent out through the demineralized water pipeline (12).

8. The working method of the turbine cold end anti-freezing system when the air cooling unit removes the low pressure cylinder is characterized in that: exhaust steam is discharged from the air cooling type steam turbine (1), enters the air cooling tower (4) through the air cooling tower isolation valve (3) for cooling, and is then discharged from the condensed water pipeline (5) to form an exhaust steam condensation channel under a normal working condition; exhaust steam is discharged from the air cooling type steam turbine (1), enters a condenser (7) through a condenser isolation valve (6), and is then discharged from a condensed water pipeline (5) to form an exhaust steam condensation channel under an anti-freezing working condition; the extracted steam is extracted from the air cooling type steam turbine (1), enters the condenser (7) through the extracted steam adjusting valve (15), and is discharged from the condensed water pipeline (5) to form an extracted steam condensation channel; raw water enters a condenser (7) through a raw water heating valve (10) for heating, and then is sent to a demineralized water treatment device (11) and then is discharged to form a raw water heating channel; raw water directly enters the demineralized water treatment device (11) through the raw water bypass valve (13) and then is discharged to form a raw water non-heating channel.

Technical Field

The invention relates to a system for preventing freezing of a cold end of a steam turbine when an air cooling unit cuts off a low-pressure cylinder, which is a system capable of preventing freezing of an air cooling tower under extremely low exhaust steam flow and belongs to the technical field of cogeneration.

Background

For an air-cooled generator set, a traditional heating steam extraction mode only extracts part of steam exhausted by a medium pressure cylinder, a steam turbine still has exhaust steam with larger flow rate, and the exhaust steam flow rate is generally above the winter safety anti-freezing flow rate of an air cooling tower, so that when the air-cooled generator set adopts steam extraction for heating, the air cooling tower does not need to be specially transformed.

The novel condensation back extraction modification technology is different from the traditional steam extraction heating technology, safe operation under the extremely low flow (5 t/h-10 t/h) of the low-pressure cylinder of the steam turbine can be realized by additionally arranging a cooling steam bypass, more steam extraction amount can be provided compared with the traditional heating steam extraction technology, and therefore the novel condensation back extraction modification technology is more and more widely applied. If the air cooling unit is subjected to novel condensation back extraction transformation, the anti-freezing problem of the air cooling tower under the extremely low exhaust steam flow needs to be carefully treated.

Various types of desalted water are required to be used in a power plant, a reverse osmosis treatment technology is mostly adopted in a desalted water replenishing treatment mode, in order to increase the water yield and prolong the service life of equipment, the temperature of a replenishing water inlet is usually controlled to be 25-35 ℃, the water yield is reduced when the temperature is too low, the reverse osmosis membrane is easily damaged when the temperature is too high, and the waste phenomenon of high quality and low use exists when high quality steam is used for heating raw water.

At present, a system which is reasonable in structural design, convenient to use and capable of effectively preventing the air cooling tower from freezing under the condition of extremely low exhaust steam flow rate does not exist.

Disclosure of Invention

The invention aims to integrate the prior art, ensure that the cold end of a steam turbine can realize effective anti-freezing when an air cooling unit cuts off a low-pressure cylinder, utilize waste steam waste heat and improve the economic benefit of a system, and provides the anti-freezing system for the cold end of the steam turbine when the air cooling unit cuts off the low-pressure cylinder. The invention can solve the anti-freezing problem of the cold end of the steam turbine under the condition of extremely low exhaust steam flow in winter, and is particularly suitable for a unit which needs to operate under the working condition of extremely low exhaust steam flow for a long time; the second system can accurately control the vacuum degree of the cold end of the steam turbine, and the safe operation of the unit is guaranteed; and the third step can heat the raw water to be treated by using the dead steam, so that the water production efficiency of the device is improved. The invention has high reliability and good economic benefit, and can well solve the problem of freezing prevention of the cold end of the steam turbine under the working condition of extremely low exhaust steam flow.

The technical scheme adopted by the invention for solving the problems is as follows: the utility model provides a steam turbine cold junction system that prevents frostbite when air cooling unit excision low pressure jar, includes air cooling type steam turbine, its characterized in that: the system also comprises a steam exhaust pipeline, an air cooling tower isolation valve, an air cooling tower, a condensed water pipeline, a condenser isolation valve, a condenser, a raw water pipeline, a raw water heating valve, a demineralized water treatment device, a demineralized water pipeline, a raw water bypass valve, a low-pressure cylinder steam extraction pipeline and a steam extraction regulating valve; the waste steam outlet of the air cooling type steam turbine is respectively connected with the inlet of an air cooling tower isolation valve and the inlet of a condenser isolation valve through a waste steam pipeline, the outlet of the air cooling tower isolation valve is connected with the waste steam inlet of the air cooling tower, the condensed water outlet of the air cooling tower is connected with a condensed water pipeline, the outlet of the condenser isolation valve is connected with the steam side inlet of a condenser, and the steam side outlet of the condenser is connected to the condensed water pipeline in a bypassing manner; the raw water pipeline is respectively connected with an inlet of a raw water heating valve and an inlet of a raw water bypass valve, an outlet of the raw water heating valve is connected with a water side inlet of a condenser, a water side outlet of the condenser is connected with a raw water inlet of a desalted water treatment device, an outlet of the desalted water treatment device is connected with a desalted water pipeline, and an outlet of the raw water bypass valve is also connected with a raw water inlet of the desalted water treatment device; and the steam extraction outlet of the air cooling type steam turbine is connected with the inlet of the steam extraction regulating valve through a low-pressure cylinder steam extraction pipeline, and the outlet of the steam extraction regulating valve is connected with the steam extraction inlet of the condenser.

Further, the condenser also comprises a temperature monitoring device which is arranged near the condensed water outlet of the condenser.

Furthermore, the air-cooled steam turbine is a steam turbine with a condensed steam extraction back, and the low-pressure cylinder of the steam turbine can safely, stably and long-time operate under extremely low exhaust steam flow.

Furthermore, the air cooling tower isolation valve and the condenser isolation valve are automatic valves with zero leakage.

Furthermore, the raw water heating valve and the raw water bypass valve are controlled by the temperature of the condensed water, the opening of the valve can be automatically adjusted according to a set value, and the back pressure operation of the steam turbine is guaranteed within a reasonable range.

Furthermore, the demineralized water treatment device is a water treatment device utilizing the reverse osmosis principle.

The working method of the turbine cold end anti-freezing system when the air cooling unit cuts off the low pressure cylinder is characterized in that: the operation steps are as follows:

1) under a normal working condition, the air cooling type steam turbine is in a pure condensation or steam extraction operation working condition, the air cooling tower does not have the anti-freezing problem, at the moment, exhaust steam of the air cooling type steam turbine is discharged into the air cooling tower, condensed water flows out from a condensed water pipeline, an isolation valve of the air cooling tower is in an open state, and an isolation valve of a condenser is in a completely closed state; if the raw water does not need to be heated, the steam extraction regulating valve and the raw water heating valve are in a closed state, the raw water bypass valve is in an open state, the raw water directly enters the desalted water treatment device instead of entering the condenser, and then is sent out through the desalted water pipeline; if the raw water needs to be heated, the steam extraction regulating valve and the raw water heating valve are in an open state, the raw water bypass valve is in a closed state, the raw water enters the condenser and is heated by steam extraction to ensure the water production efficiency, the raw water passes through the demineralized water treatment device and then is discharged through the demineralized water pipeline, and the condensed water of the steam extraction flows out of the condensed water pipeline;

2) under the anti-freezing working condition, the low-pressure cylinder of the air-cooled steam turbine is cut off to operate, at the moment, the flow of exhaust steam is extremely low and is not suitable for being sent to the air-cooled tower for cooling, so that the isolation valve of the air-cooled tower is in a completely closed state, the air-cooled tower stops working, the isolation valve of the condenser is in an open state, the exhaust steam is sent to the condenser for condensation, and condensed water flows out from a condensed water pipeline; in order to keep the backpressure of the steam turbine within a reasonable range, the steam extraction regulating valve needs to be completely closed, meanwhile, the temperature monitoring device measures the temperature of a condensed water outlet of the condenser, the opening degrees of the raw water heating valve and the raw water bypass valve are adjusted in a linkage mode according to a set value, the purpose of reasonably controlling the backpressure of the steam turbine is achieved, all or part of raw water is sent into the condenser to be heated according to the situation, then, the heated and unheated raw water is sent to the demineralized water treatment device, and the treated demineralized water is sent out through a demineralized water pipeline.

Furthermore, exhaust steam is discharged from the air cooling type steam turbine, enters the air cooling tower through an air cooling tower isolation valve for cooling, and is discharged from a condensed water pipeline to form an exhaust steam condensation channel under a normal working condition; the exhaust steam is discharged from the air cooling type steam turbine, enters the condenser through the condenser isolation valve, and is then discharged from the condensed water pipeline to form an exhaust steam condensation channel under the anti-freezing working condition; extracting steam from the air cooling type steam turbine, entering a condenser through a steam extraction regulating valve, and then discharging the steam from a condensed water pipeline to form a steam extraction condensation channel; raw water enters a condenser for heating through a raw water heating valve, and is then sent to a demineralized water treatment device and then discharged to form a raw water heating channel; the raw water directly enters the demineralized water treatment device through the raw water bypass valve and then is discharged to form a raw water non-heating channel.

Compared with the prior art, the invention has the following advantages and effects: (1) the anti-freezing problem of the cold end of the steam turbine under the condition of extremely low exhaust steam flow in winter can be solved, and the anti-freezing device is particularly suitable for a unit which needs to operate under the working condition of extremely low exhaust steam flow for a long time; (2) the system can accurately control the vacuum degree of the cold end of the steam turbine, and the safe operation of the unit is guaranteed; (3) the raw water to be treated can be heated by using the dead steam, so that the water production efficiency of equipment and the economic benefit of a system are improved; (4) the system has high automation degree and can operate according to actual conditions and remote instructions; (5) the structure design is reasonable, the conception is unique, the operation is stable, and the reliability is good.

Drawings

FIG. 1 is a schematic structural diagram of a cold end anti-freezing system of a steam turbine when a low pressure cylinder is cut off by an air cooling unit in the embodiment of the invention.

In the figure: the system comprises an air cooling type steam turbine 1, a steam exhaust pipeline 2, an air cooling tower isolation valve 3, an air cooling tower 4, a condensed water pipeline 5, a condenser isolation valve 6, a condenser 7, a temperature monitoring device 8, a raw water pipeline 9, a raw water heating valve 10, a demineralized water treatment device 11, a demineralized water pipeline 12, a raw water bypass valve 13, a low-pressure cylinder steam extraction pipeline 14 and a steam extraction adjusting valve 15.

Detailed Description

The present invention will be described in further detail below by way of examples with reference to the accompanying drawings, which are illustrative of the present invention and are not to be construed as limiting the present invention.