CN209991441U - Water loss protection system of circulating fluidized bed boiler - Google Patents
Water loss protection system of circulating fluidized bed boiler Download PDFInfo
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- CN209991441U CN209991441U CN201920739127.3U CN201920739127U CN209991441U CN 209991441 U CN209991441 U CN 209991441U CN 201920739127 U CN201920739127 U CN 201920739127U CN 209991441 U CN209991441 U CN 209991441U
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Abstract
The utility model provides a circulating fluidized bed boiler desiccation protection system, be provided with steam turbine bypass system on boiler over heater outlet pipe way, it contains the high-pressure bypass of connecting in over heater outlet pipe way and sets up the high side valve on this high-pressure bypass of this steam turbine bypass system, the export of this high-pressure bypass divide into first high-pressure bypass branch road and the high-pressure bypass branch road of second, the steam header is assisted in the connection of second high-pressure bypass branch road, still connect the desiccation cooling pipeline on the high side valve, be equipped with the desiccation cooling water pump on this desiccation cooling pipeline, independent water tank or the water tank of connecting other blocks in the unit are connected to the other end of desiccation cooling pipeline, the utility model discloses a desiccation protection system simple structure, non-maintaining, the investment is little, effectively avoids low temperature water to get into the.
Description
Technical Field
The utility model belongs to the equipment safety protection field of circulating fluidized bed boiler, especially a system that protection heating surface was not overtemperature when the loss of coolant accident took place.
Background
The circulating fluidized bed boiler has been widely used in China due to its advantages of wide fuel adaptability, combustibility of low calorific value fuel and other special fuels, low pollutant control cost, etc. The technology of the circulating fluidized bed in China is developed rapidly, and the circulating fluidized bed boiler is the country with the largest number of operating circulating fluidized bed boilers in the world. In recent years, 350 MW-grade CFB units with dozens of supercritical parameters are put into operation in China, and the largest supercritical circulating fluidized bed unit in the world is the second-stage 600MW unit in white horse in China.
One of the important differences between the circulating fluidized bed boiler and the pulverized coal furnace is that the gas-solid two-phase heat transfer to the heated surface is mainly performed in the hearth, a large amount of circulating material solid particles exist in the hearth, the hearth has large refractory material consumption, and the hearth has large thermal inertia. Therefore, when the boiler loses water, the possibility that the heating surfaces such as the water-cooled wall and the like are over-heated and damaged because the bed materials continuously release heat to the heating surfaces exists. Therefore, when the ALSTOM type CFB boiler was introduced in the early days, an emergency water supplement system was introduced at the same time as one of its necessary configurations.
The emergency water replenishing system is a special configuration system of the circulating fluidized bed boiler and comprises an emergency water replenishing pump, an emergency water replenishing tank and the like. The heating surface can be protected when water supply is lost, and the heating surface is prevented from being burnt out.
Because the emergency water replenishing pump has high pressure and large flow, an independent diesel engine needs to be configured to deal with the power loss condition of the whole plant, and because the diesel engine has high power and generally needs to be imported, the investment is large.
However, the probability of water supply loss caused by power loss of the whole plant is extremely low, and the emergency water supply system needs to be put into use immediately after the occurrence of the water loss accident and needs to be regularly operated in a trial mode, so that the daily operation and maintenance cost is high.
SUMMERY OF THE UTILITY MODEL
The utility model discloses the technical problem who solves is when the dehydration condition takes place at supercritical circulating fluidized bed boiler promptly, through steam turbine bypass system, in time will be received the working medium in the hot side and release with controlled rate according to setting for the logic to prevent to receive the hot side overtemperature, play the purpose that the protection received the hot side.
The technical means adopted by the utility model are as follows.
The utility model provides a circulating fluidized bed boiler loses water protection system, contains steam turbine bypass system, and it contains high-pressure bypass and sets up the high side valve on this high-pressure bypass, and the export of this high-pressure bypass divide into first high-pressure bypass branch road and second high-pressure bypass branch road, and the auxiliary steam header is connected to second high-pressure bypass branch road, still connect the temperature reduction pipeline that loses water on the high side valve.
The water loss temperature reducing pipeline is provided with a water loss temperature reducing water pump, and the other end of the water loss temperature reducing pipeline is connected with an independent water tank or a water tank connected with other blocks in the unit.
And water pump shut-off valves are arranged on the front pipeline and the rear pipeline of the water loss temperature reduction water pump.
The high side valve is connected with a water feeding pump outlet main pipe, and the water loss temperature reduction pipeline is connected to the water feeding pump outlet main pipe.
The high-pressure bypass branch is provided with a first shutoff valve, the second high-pressure bypass branch is provided with a second shutoff valve, and the high-pressure bypass valve, the water loss temperature-reducing water pump, the first shutoff valve, the second shutoff valve and the water pump shutoff valve are all connected to a security power supply.
The high side valve is opened by automatic control and closed by manual control, and the water loss temperature reduction water pump, the first shut-off valve, the second shut-off valve and the water pump shut-off valve are all automatically controlled.
The high side valve is hydraulically controlled or electrically controlled, and the water loss and temperature reduction water pump, the first shut-off valve, the second shut-off valve and the water pump shut-off valve are hydraulically controlled or pneumatically controlled or electrically controlled.
The beneficial effects of the utility model.
1. After a boiler water loss accident, particularly a boiler water loss accident caused by power loss of a whole plant, accumulated bed materials, castable in a boiler and the like can be transferred to heat of working media in a heating surface, the heat is taken out of a boiler body at a controlled mass flow rate, the phenomenon that the heating surface is over-heated due to the fact that the heat cannot be taken out of the boiler in time is prevented, meanwhile, a safety valve of a superheater and a PCV (positive pressure control) valve cannot jump, and waste of the working media is avoided. The utility model discloses a system mainly utilizes the steam turbine bypass system of unit, and the investment is very low, can replace conventional urgent water charging system completely, practices thrift a large amount of initial investments and fortune dimension expense, simplifies the emergent management of power plant, has reduced the human cost.
2. The utility model discloses a desiccation protection system simple structure, non-maintaining, investment are little, effectively avoid low temperature water to get into the boiler heating surface.
3. The existing emergency water replenishing system is not only complex, but also needs regular trial operation at ordinary times, but has few used opportunities, so that the cost performance is extremely low. After water loss occurs, a large amount of low-temperature water supplement is generated and enters the heating surface, and the heating surface is damaged. Use the utility model discloses a behind the desiccation protection system, through the flow of high pressure bypass valve control steam through the bypass, control the speed of releasing to the protection receives the hot side.
4. The utility model discloses a loss of water protection system can be used to the circulating fluidized bed boiler of different grade type like other parameters such as supercritical, subcritical, super supercritical, and the range of application is wide.
Drawings
Fig. 1 is a schematic diagram of the system structure of the present invention.
Detailed Description
A superheater outlet pipeline 1 is arranged behind a superheater 3 (or a water wall) of the boiler, and a steam turbine bypass system is arranged on the outlet pipeline 1. Specifically, the system comprises a high-pressure bypass 2 with an inlet connected to a superheater outlet pipeline 1, a high-pressure bypass valve 3 is arranged on the high-pressure bypass, and the other outlet of the high-pressure bypass valve 3 is communicated with a feed water pump outlet mother pipe 4. The outlet of the high-pressure bypass 2 is divided into two paths, namely a first high-pressure bypass branch 21 and a second high-pressure bypass branch 22, the first high-pressure bypass branch 21 is connected with the reheating cold section pipeline 6, the second high-pressure bypass branch 22 is connected with the auxiliary steam header 7, and the first high-pressure bypass branch 21 and the second high-pressure bypass branch 22 are respectively provided with a first shutoff valve 23 and a second shutoff valve 24.
In order to deal with the loss of water accident of the boiler in the whole plant, a loss of water temperature reduction pipeline 5 is connected to the water supply pump outlet main pipe 4, a loss of water temperature reduction water pump 51 with a high pressure head and a small flow rate is arranged on the loss of water temperature reduction pipeline 5, water pump shut-off valves 53 are arranged on the pipelines in front of and behind the loss of water temperature reduction water pump 51, the other end of the loss of water temperature reduction pipeline 5 is connected with a water tank 52, the water tank 52 can be an independent water tank special for the loss of water accident, water can be drawn from water tanks of other blocks, and the loss of water temperature reduction pipeline is determined according to the.
The high bypass valve 3 is hydraulically or electrically controlled and can be opened or closed manually. The other valves except the high bypass valve 3 can adopt one of hydraulic, pneumatic or electric control modes according to actual requirements, and can be automatically controlled to be opened and closed. The valve bodies are connected with a security power supply so as to still realize work in a power-off state.
After the water loss accident of the boiler occurs, particularly after the water loss accident of the boiler caused by the power loss of a whole plant occurs, the three fans are completely stopped, the circulating material quickly falls back to the air distribution plate, the temperature of the circulating material, castable in the boiler and the like is still as high as about 850 ℃, heat is released to heating surfaces such as a water cooling wall of a hearth in a radiation and heat conduction mode, working medium water continuously absorbs heat in the water cooling wall and is changed into steam, a main steam valve of the steam turbine and a steam inlet valve of an intermediate pressure cylinder are completely closed, and the steam pressure is increased. The working medium in the furnace is continuously converted into steam from water, and the steam continuously absorbs heat, so that the pressure and the temperature are increased.
After the loss of coolant accident occurs, the first shut-off valve 23 is closed and the second shut-off valve 24 is opened. The water pump shut-off valves 53 before and after the water loss temperature reduction water pump 51 are opened, and the water loss temperature reduction water pump 51 is started to supply temperature reduction water to the high-side valve 3. When the steam in the superheater rises to reach the set pressure A, the high-side valve 3 is automatically opened, the steam passes through the high-side valve 3 with controlled mass flow, and the high-temperature high-pressure steam and the desuperheating water are mixed, subjected to temperature and pressure reduction and then flow to the auxiliary steam header 7 to supply steam to a shaft seal and the like.
When the steam pressure is reduced to the pressure B, the high side valve 3 is manually closed, working media in a heated surface such as a boiler water-cooled wall continue to absorb heat, the steam pressure is increased, the high side valve 3 is opened again after the pressure A is reached, the temperature of bed materials, casting materials and the like in the boiler is reduced after the process is circulated for a plurality of times, the heat transfer rate to the working media in the heated surface such as the water-cooled wall is reduced, water can not be changed into steam any more, the pressure and the temperature of the steam can not be increased, and therefore the heated surface is protected from being over-heated. In the process, the flow of the high side valve 3 is controlled to be about 35t/h, and the pipe wall can be prevented from overtemperature.
When the power loss of the whole plant occurs, the water loss temperature reduction water pump 51 and the hydraulic valve are powered by an emergency diesel generator conventionally arranged in the unit.
The above description is given by way of example of the manner in which the valves are hydraulically controlled. Because the probability of power failure accidents is very small, other valves except the high-side valve 3 can be operated pneumatically instead of hydraulically and can be operated according to the following logic.
The 2 water pump shut-off valves 53 are switched from the off state to the on state after the power loss occurs.
The first shut-off valve 23 is switched from the open state to the closed state after the power loss occurs.
The second shut-off valve 24 is switched from the closed state to the open state after the power loss occurs.
Because the high-side valve 3 needs to be operated repeatedly, hydraulic control or electric control is necessary, and the closing can be controlled manually.
The utility model discloses the setting of the connection of well pipeline and corresponding valve, pump can be adjusted according to the demand, and this is that technical personnel in the field can all realize.
Claims (7)
1. The utility model provides a circulating fluidized bed boiler loses water protection system, contains steam turbine bypass system, and it contains high-pressure bypass (2) and sets up high side valve (3) on this high-pressure bypass (2), and its characterized in that, the export of this high-pressure bypass (2) divide into first high-pressure bypass branch (21) and second high-pressure bypass branch (22), and auxiliary steam header (7) are connected in second high-pressure bypass branch (22), still connect on high side valve (3) and lose water and subtract warm pipeline (5).
2. The boiler water loss protection system of claim 1, wherein the water loss temperature-reducing pipeline (5) is provided with a water loss temperature-reducing water pump (51), and the other end of the water loss temperature-reducing pipeline (5) is connected to an independent water tank (52) or a water tank connected to other blocks in the unit.
3. The circulating fluidized bed boiler water loss protection system of claim 2, wherein a water pump shut-off valve (53) is arranged on each of the front and rear pipelines of the water loss temperature reduction water pump (51).
4. The circulating fluidized bed boiler water loss protection system of claim 1, wherein the high-side valve (3) is connected with a feed pump outlet main pipe (4), and the water loss temperature reduction pipeline (5) is connected with the feed pump outlet main pipe (4).
5. The circulating fluidized bed boiler water loss protection system according to claim 3, wherein a first shutoff valve (23) is disposed on the first high-pressure bypass branch (21), a second shutoff valve (24) is disposed on the second high-pressure bypass branch (22), and the high-side valve (3), the water loss temperature reduction water pump (51), the first shutoff valve (23), the second shutoff valve (24), and the water pump shutoff valve (53) are all connected to a safety power supply.
6. The circulating fluidized bed boiler water loss protection system according to claim 3, wherein the high-side valve (3) is automatically controlled to be opened and manually controlled to be closed, and the water loss temperature reduction water pump (51), the first shut-off valve (23), the second shut-off valve (24) and the water pump shut-off valve (53) are all automatically controlled.
7. The circulating fluidized bed boiler water loss protection system according to claim 3, wherein the high-side valve (3) is hydraulically or electrically controlled, and the water loss temperature reduction water pump (51), the first shut-off valve (23), the second shut-off valve (24) and the water pump shut-off valve (53) are hydraulically or pneumatically or electrically controlled.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920739127.3U CN209991441U (en) | 2019-05-21 | 2019-05-21 | Water loss protection system of circulating fluidized bed boiler |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920739127.3U CN209991441U (en) | 2019-05-21 | 2019-05-21 | Water loss protection system of circulating fluidized bed boiler |
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| CN209991441U true CN209991441U (en) | 2020-01-24 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111981462A (en) * | 2019-05-21 | 2020-11-24 | 中国电力工程顾问集团华北电力设计院有限公司 | Water loss protection system of circulating fluidized bed boiler |
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- 2019-05-21 CN CN201920739127.3U patent/CN209991441U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111981462A (en) * | 2019-05-21 | 2020-11-24 | 中国电力工程顾问集团华北电力设计院有限公司 | Water loss protection system of circulating fluidized bed boiler |
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