Double-backpressure condenser circulation structure

Abstract

The utility model relates to the technical field of condensing steam turbine circulation in the large heat energy power generation process of fire coal, fuel gas, nuclear energy and the like, and discloses a double-back-pressure condenser circulation structure. When the back pressure of a low-back-pressure condenser is lower than the blocking back pressure, the low-back-pressure condenser is switched to single-back-pressure operation by opening and closing an inlet connection isolation door of a vacuum pump; and meanwhile, the back pressure of the unit is reduced, the operation economy is improved, coal consumption is reduced, and carbon emission is reduced. Double-back-pressure operation is converted into single-back-pressure operation, so that the steam turbine is prevented from operating under blocked back pressure, and overload and water erosion of the last-stage blade of the low-pressure cylinder of the steam turbine are avoided. After implementation of technical measures of single-double backpressure switching and vacuum pump operation optimization, the final-stage blade condition of the low-pressure cylinder of the steam turbine is checked to be good, and no obvious water erosion condition exists.

Description

Technical Field

[0001] This utility model relates to the technical field of condensing steam turbine cycles in large-scale thermal power generation processes such as coal-fired, gas-fired, and nuclear power, and specifically to a dual-backpressure condenser cycle structure. Background Technology

[0002] A steam turbine is a rotating machine that uses steam as power and converts the thermal energy of steam into mechanical work. It is the most widely used prime mover in modern thermal power plants. Air-cooling systems are the main cooling method for thermal power plants in water-scarce areas. These systems include direct and indirect air-cooling systems, with indirect air-cooling systems being more commonly used. Indirect air-cooling systems are characterized by low noise, less susceptibility to ambient wind, and low power consumption. The cooling water in an indirect air-cooling system operates in a completely closed loop, resulting in minimal water loss. Theoretically, the system consumes zero water, demonstrating significant water-saving effects.

[0003] The indirect air-cooled system uses an indirect-cooled reaction condensing steam turbine. The exhaust steam from the low-pressure cylinder enters condensers A and B respectively. The circulating water passes through condensers A and B in series, enters from the low back-pressure condenser A, and the outlet water enters the high back-pressure condenser B. After heat exchange, the water is transported to the indirect cooling tower for cooling by the indirect-cooled circulating water pump.

[0004] In winter environments, as temperatures gradually decrease, the exhaust temperature of the low-pressure condenser in the indirect air-cooled system also gradually declines. Simultaneously, the back pressure of the low-pressure condenser decreases, reducing the steam intake to the turbine for the same power generation. This causes the steam velocity at the turbine outlet to approach the back pressure at the speed of sound, resulting in a blocking back pressure. Consequently, the low-pressure condenser back pressure operates below the corresponding load blocking back pressure value. At this time, the steam undergoes turbulent expansion in the last-stage blades, causing additional losses. Consequently, the steam intake to the turbine needs to increase for the same power generation, leading to a decrease in the unit's operating economy. Utility Model Content

[0005] The present invention aims to provide a dual-backpressure condenser circulation structure that can maintain the back pressure values ​​of both the low-backpressure condenser and the high-backpressure condenser at a rate not lower than the blocking back pressure values ​​under different load conditions of the unit when the winter temperature is low.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] 1) A double-back pressure condenser circulation structure, comprising a low-back pressure condenser and a high-back pressure condenser, the low-back pressure condenser and the high-back pressure condenser being connected through a vacuum communication pipe, characterized in that a vacuum pump and a vacuum pump inlet communication isolation door are installed on the vacuum communication pipe, different vacuum pump inlet communication isolation doors on the vacuum communication pipe are opened and closed to enable the low-back pressure condenser and the high-back pressure condenser to be communicated with each other through different vacuum pumps on the vacuum communication pipe, the vacuum pressures of the low-back pressure condenser and the high-back pressure condenser are consistent, and the back pressure values of the low-back pressure condenser and the high-back pressure condenser are kept from being simultaneously lower than the choking back pressure values under different load states of the unit.

[0008] The vacuum pump inlet communication isolation door on the vacuum communication pipe is opened and closed, the low-back pressure condenser and the high-back pressure condenser are communicated with each other through the vacuum pump on the vacuum communication pipe, at this time, the back pressure of the low-back pressure condenser starts to rise, the back pressure of the high-back pressure condenser starts to drop, the vacuum pressures of the low-back pressure condenser and the high-back pressure condenser tend to be consistent, and the back pressure values of the low-back pressure condenser and the high-back pressure condenser are kept from being simultaneously lower than the choking back pressure values under different load states of the unit, the overheat steam can be prevented from being changed into saturated steam or even wet steam after the low-pressure cylinder steam does work, water erosion of the last-stage blades of the low-pressure cylinder of the steam turbine is avoided, the turbulent flow formed after the last-stage blades is also possible to cause the vibration of the steam turbine to increase, and the safe operation of the steam turbine is threatened.

[0009] 2) The double-back pressure condenser circulation structure according to 1), wherein:

[0010] The vacuum pump comprises an A vacuum pump, a B vacuum pump and a C vacuum pump, the vacuum pump inlet communication isolation door comprises a first vacuum pump inlet communication isolation door and a second vacuum pump inlet communication isolation door, the first vacuum pump inlet communication isolation door corresponds to the A vacuum pump, and the second vacuum pump inlet communication isolation door corresponds to the B vacuum pump.

[0011] The B vacuum pump is a standby machine, and the C vacuum pump is in an open state, and when normally used, the C vacuum pump is connected with the low-back-pressure condenser and the high-back-pressure condenser through vacuum connecting pipes to be in a double-back-pressure state.

[0012] 3) The double-back-pressure condenser circulating structure according to 1), wherein:

[0013] The low-back-pressure condenser and the high-back-pressure condenser are respectively provided with circulating water inlets and outlets, and a plurality of circulating water connecting pipes are arranged in the low-back-pressure condenser and the high-back-pressure condenser and connect the low-back-pressure condenser and the high-back-pressure condenser in series, and the circulating water connecting pipes are connected with the outlet of the low-back-pressure condenser and the inlet of the high-back-pressure condenser.

[0014] In the utility model, circulating water enters from the inlet of the low-back-pressure condenser, the circulating water outlet of the low-back-pressure condenser enters the circulating water inlet of the high-back-pressure condenser through the circulating water connecting pipe, and then is discharged from the circulating water outlet of the high-back-pressure condenser.When the back pressure of the low-back-pressure condenser is lower than the choking back pressure value, the first vacuum pump inlet connecting isolation door is opened, and the back pressures of the low-back-pressure condenser and the high-back-pressure condenser will be consistent, and finally reach the balanced state, and become single-back-pressure operation. The back pressure of the low-back-pressure condenser rises, and the back pressure of the high-back-pressure condenser drops, and under the condition that the back pressure is not lower than the choking back pressure, the temperature of circulating water can be continuously reduced, so that the average back pressure of the unit is reduced to be closer to the economic value of the choking back pressure.

[0015] Compared with the prior art, the utility model still has the following technical effects:

[0016] The utility model discloses a low back pressure condenser and high back pressure condenser are connected through the vacuum communication pipe, and the vacuum pump and the vacuum pump inlet communication isolation door are installed on the vacuum communication pipe, and the different vacuum pump inlet communication isolation door on the vacuum communication pipe is opened and closed to make the low back pressure condenser and the high back pressure condenser be communicated through the vacuum pump on the different circulating water communication pipe, at this moment, the low back pressure condenser back pressure starts to rise, and the high back pressure condenser back pressure starts to drop, and the low back pressure condenser and the high back pressure condenser vacuum pressure tend to be consistent, and the back pressure value of low back pressure condenser and high back pressure condenser is kept simultaneously not less than the blockage back pressure value under the different load state of unit, can avoid the overheat steam of low pressure cylinder steam work possibly change into saturated steam or even wet steam, causes the water erosion of turbine low pressure cylinder last stage blade, and the disorderful steam flow formed after last stage blade still can cause the vibration of turbine to increase, threatens the safe operation of turbine. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a double back pressure condenser circulation structure schematic diagram for the utility model. DETAILED DESCRIPTION

[0018] The following is further explained in detail through specific implementation:

[0019] The figure marks in the description annex include: low back pressure condenser 1, high back pressure condenser 2, A vacuum pump 3, B vacuum pump 4, C vacuum pump 5, first vacuum pump inlet communication isolation door 6, second vacuum pump inlet communication isolation door 7.

[0020] Embodiment, see Figure 1 The utility model discloses a low back pressure condenser and high back pressure condenser are connected through the vacuum communication pipe, and the vacuum pump and the vacuum pump inlet communication isolation door are installed on the vacuum communication pipe, and the different vacuum pump inlet communication isolation door on the vacuum communication pipe is opened and closed to make the low back pressure condenser and the high back pressure condenser be communicated through the vacuum pump on the different circulating water communication pipe, at this moment, the low back pressure condenser back pressure starts to rise, and the high back pressure condenser back pressure starts to drop, and the low back pressure condenser and the high back pressure condenser vacuum pressure tend to be consistent, and the back pressure value of low back pressure condenser and high back pressure condenser is kept simultaneously not less than the blockage back pressure value under the different load state of unit, can avoid the overheat steam of low pressure cylinder steam work possibly change into saturated steam or even wet steam, causes the water erosion of turbine low pressure cylinder last stage blade, and the disorderful steam flow formed after last stage blade still can cause the vibration of turbine to increase, threatens the safe operation of turbine.

[0021] The embodiment makes the low back pressure condenser and the high back pressure condenser be communicated through the vacuum pump on the different circulating water communication pipe through the opening and closing vacuum pump inlet communication isolation door set on the vacuum communication pipe, at this moment, the low back pressure condenser back pressure starts to rise, and the high back pressure condenser back pressure starts to drop, and the low back pressure condenser and the high back pressure condenser vacuum pressure tend to be consistent, and the back pressure value of low back pressure condenser and high back pressure condenser is kept simultaneously not less than the blockage back pressure value under the different load state of unit, can avoid the overheat steam of low pressure cylinder steam work possibly change into saturated steam or even wet steam, causes the water erosion of turbine low pressure cylinder last stage blade, and the disorderful steam flow formed after last stage blade still can cause the vibration of turbine to increase, threatens the safe operation of turbine.

[0022] Secondly, the vacuum pump comprises an A vacuum pump 3, a B vacuum pump 4, and a C vacuum pump 5, the vacuum pump inlet communication isolation door comprises a first vacuum pump inlet communication isolation door 6 and a second vacuum pump inlet communication isolation door 7, the first vacuum pump inlet communication isolation door 6 corresponds to the A vacuum pump 3, and the second vacuum pump inlet communication isolation door 7 corresponds to the B vacuum pump 4.

[0023] In the embodiment, the B vacuum pump is a standby machine, and the C vacuum pump 5 is in an open state. In normal use, the C vacuum pump 5 is connected with the low-back-pressure condenser 1 and the high-back-pressure condenser 2 through vacuum communication pipes, and is in a double-back-pressure state. When the back pressure of the low-back-pressure condenser is lower than the choking back pressure value, the first vacuum pump inlet communication isolation door 6 is opened, the A vacuum pump 3 is connected with the C vacuum pump 5 and acts on the low-back-pressure condenser 1 and the high-back-pressure condenser 2, at this time, the back pressure of the low-back-pressure condenser starts to rise, and the back pressure of the high-back-pressure condenser starts to fall, when the back pressure of the low-back-pressure condenser and the back pressure of the high-back-pressure condenser tend to be consistent, the A vacuum pump 3 is stopped, and the C vacuum pump 5 is kept in single-pump operation. The single and double back pressure switching operation of the condenser can keep the low-pressure cylinder turbine running at not less than the choking back pressure, and can avoid the situation that the overheat steam of the low-pressure cylinder steam is possibly changed into saturated steam or even wet steam after work, and cause the water erosion of the last-stage blade of the low-pressure cylinder turbine, the turbulent flow formed behind the last-stage blade, and the possible increase of the vibration of the turbine, which threatens the safe operation of the turbine.

[0024] In addition, the low-back-pressure condenser and the high-back-pressure condenser are respectively provided with a circulating water inlet and a circulating water outlet, a plurality of circulating water communication pipes are arranged in the low-back-pressure condenser and the high-back-pressure condenser and connect the two in series, and the circulating water communication pipes are connected with the circulating water outlet of the low-back-pressure condenser and the circulating water inlet of the high-back-pressure condenser.

[0025] In the embodiment, the circulating water enters the low-back-pressure condenser from the circulating water inlet of the low-back-pressure condenser, the circulating water outlet of the low-back-pressure condenser enters the circulating water inlet of the high-back-pressure condenser through the circulating water communication pipe, and then is discharged from the circulating water outlet of the high-back-pressure condenser. When the back pressure of the low-back-pressure condenser is lower than the choking back pressure value, the first vacuum pump inlet communication isolation door 6 is opened, the back pressures of the low-back-pressure condenser and the high-back-pressure condenser tend to be consistent, and finally reach a balanced state, and the low-back-pressure condenser and the high-back-pressure condenser are in single-back-pressure operation; or the second vacuum pump inlet communication isolation door is opened, the B vacuum pump is connected with the C vacuum pump and acts on the low-back-pressure condenser and the high-back-pressure condenser, the low-back-pressure condenser and the high-back-pressure condenser keep consistent vacuum pressure, the B vacuum pump is stopped, and the C vacuum pump is kept in single-pump operation. The back pressure of the low-back-pressure condenser rises, and the back pressure of the high-back-pressure condenser falls, and under the condition of not less than the choking back pressure, the temperature of the circulating water can be continuously reduced, so that the average back pressure of the unit is reduced to a more close-to-choking back pressure economic value.

[0026] When the back pressure of the low back pressure condenser is lower than the choke back pressure in the embodiment, switching to single back pressure operation is realized by opening and closing the vacuum pump inlet communication isolation door, the unit back pressure is reduced, the economic type of operation is improved, the coal consumption is reduced, and the carbon emission is reduced. By switching to single back pressure operation from double back pressure operation, the turbine is prevented from operating below the choke back pressure, and the overloading of the last stage blade of the low pressure cylinder of the turbine and the water erosion of the blade are eliminated. Since the single / double back pressure switching and the vacuum pump operation optimization technology measures are implemented, the last stage blade of the low pressure cylinder of the turbine is in good condition, and no obvious water erosion occurs.

[0027] The above is only the embodiment of the utility model, and the specific technical solutions and / or common knowledge of characteristics in the scheme are not described in detail. It should be pointed out that for those skilled in the art, without departing from the technical solutions of the utility model, a number of modifications and improvements can be made, which should also be considered as the protection scope of the utility model, and these will not affect the effect and practicality of the utility model. The protection scope of the present application should be subject to the content of its claims, and the specific implementation mode and the like in the specification can be used to explain the content of the claims.

Claims

1. A dual-backpressure condenser circulation structure, comprising a low-backpressure condenser and a high-backpressure condenser, wherein the low-backpressure condenser and the high-backpressure condenser are connected by a vacuum connecting pipe, characterized in that, Vacuum pumps and vacuum pump inlet isolation doors are installed on the vacuum interconnection pipe to open and close different vacuum pump inlet isolation doors on the vacuum interconnection pipe, so that the low back pressure condenser and the high back pressure condenser are interconnected through different vacuum pumps on the vacuum interconnection pipe. The vacuum pressure of the low back pressure condenser and the high back pressure condenser are consistent, and the back pressure values ​​of the low back pressure condenser and the high back pressure condenser are kept at no lower than the blocking back pressure values ​​under different load conditions of the unit.

2. The condenser circulation structure with dual back pressure according to claim 1, characterized in that: The vacuum pumps include vacuum pump A, vacuum pump B, and vacuum pump C. The vacuum pump inlet communication isolation door includes a first vacuum pump inlet communication isolation door and a second vacuum pump inlet communication isolation door. The first vacuum pump inlet communication isolation door corresponds to vacuum pump A, and the second vacuum pump inlet communication isolation door corresponds to vacuum pump B.

3. The condenser circulation structure with dual back pressure according to claim 1, characterized in that: The low-back-pressure condenser and the high-back-pressure condenser are respectively provided with circulating water inlet and outlet. Several circulating water connecting pipes are set inside the low-back-pressure condenser and the high-back-pressure condenser and connected in series. The circulating water connecting pipes are connected to the high-back-pressure condenser inlet through the outlet of the low-back-pressure condenser.

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