Steam condenser for steam turbine generator unit

Abstract

The invention discloses a steam condenser for a steam turbine generator unit, and relates to a direct cooling type cooling system of a thermal generator unit, in particular to a steam condenser. The problems of low efficiency and serious freezing injury of a reverse flow tube bundle area are solved by utilizing the rapid heat dissipation capability of the heat tube heat exchange device. According to one scheme, a steam main pipe is communicated with an inlet of a downstream area heat dissipation unit, a condensate pipe is communicated with an outlet of the downstream area heat dissipation unit, and the condensate pipe is further communicated with an inlet and an outlet of a countercurrent area heat dissipation unit; the countercurrent area heat dissipation unit achieves heat dissipation and condensation through a heat pipe. According to the other scheme, the downstream pipe bundles are communicated with the steam mother pipe and the condensate pipe, the number of the countercurrent pipe bundles is smaller than that of the downstream pipe bundles, and the countercurrent pipe bundles are distributed among the downstream pipe bundles in a scattered mode. The lower end of each countercurrent pipe bundle is communicated with a condensate pipe; the upper end of each countercurrent tube bundle is communicated with a gas inlet end of a vacuum pump; an exhaust port of the vacuum pump is communicated with the atmospheric environment to empty separated gas; one end of each heat pipe heat exchange device is inserted into the countercurrent pipe bundle to achieve heat balance inside and outside a pipe cavity of the countercurrent pipe bundle.

Description

TECHNICAL FIELD

[0001] The present application relates to a direct cooling system of a thermal power generating unit, in particular to a steam condenser. BACKGROUND

[0002] In the vast northwest region, drought and little rain has become the norm, water resources are extremely scarce. Power plant steam turbine generator unit generally uses a direct air cooling system, which is an efficient water-saving technical solution. In the design of this direct air cooling system, the exhaust steam of the turbine is directly introduced into the tube bundle part of the air cooling island. The air cooling island is located at a high place, and is equipped with strong axial flow fans below. The role of these fans is to guide the cold air on the ground upwards, so that it flows along the surface of the tube bundle of the air cooling island. Through this cold air flow mode, the exhaust steam in the tube bundle is rapidly cooled. With the decrease of temperature, the steam in the tube bundle is gradually cooled and condensed into condensed water. These condensed water is collected through the condensate pipe and returned to the system, and the whole system runs in a closed loop, thereby greatly improving the water utilization efficiency.

[0003] Since the pressure inside the cooler (also known as the condenser) is lower than the atmospheric pressure, and the tube bundle structure of the air cooling island is constructed by welding process, the external air can penetrate into the tube bundle through the welding gap and mix with the liquid therein to form non-condensable gas bubbles. At the same time, steam bubbles are also produced in the process of high-temperature exhaust steam being not completely converted into water. The existence of these bubbles will cause air resistance phenomenon inside the cooling system, thereby significantly reducing the working efficiency of the cooler. In order to solve these bubble and air resistance problems, the air cooling island structure is designed as shown in Figure 2 and Figure 3 Some tube bundles in the two groups of multiple rows of tube bundles on the left half slope and the right half slope between the air cooling island steam main pipe 1 and the condensate pipe 2 arranged in the A-type frame are selected as the configuration of the counter-flow zone tube bundles arranged at intervals. In Figure 3 , the dark part of the tube bundle is the counter-flow zone tube bundle b, and the light part of the tube bundle is the co-flow zone tube bundle a. The lower end of the counter-flow zone tube bundle b is connected with the condensate pipe 2, and the upper end is not connected with the steam main pipe 1, but is connected with the vacuum pump 4. Through the negative pressure suction effect of the vacuum pump 4, the non-condensable gas bubbles accumulated in the condensate pipe 2 in the system are sucked and discharged to the external environment through the vacuum pump 4 above the counter-flow zone tube bundle b. In the counter-flow zone tube bundle b, the steam bubbles are condensed into water and then flow back to the condensate pipe, which avoids the occurrence of bubble and air resistance phenomenon in the air cooling island, and to some extent, guarantees the operation of the air cooling island.

[0004] Although the air resistance phenomenon in the air cooling island is solved, the existence of the counterflow zone structure brings new problems for the operation of the condenser. First, the initial temperature of the steam in the counterflow zone is lower, and the cooling effect of using the tube bundle structure is obviously not as good as that of the convection zone, resulting in waste of space resources and affecting the overall operation effect of the system. Second, this structure is particularly unfavorable in winter operation in the north. The steam temperature in the convection tube bundle is higher than that in the counterflow zone tube bundle. When the ambient temperature drops below 0℃, the convection zone tube bundle can work normally, while the counterflow zone tube bundle faces the risk of icing. In order to avoid icing, the system back pressure needs to be increased, the water flow speed needs to be increased, and the condensate return temperature needs to be increased, but due to this measure, the heat exchange time of the tube bundle is reduced, and the operation potential of the air cooling island system under low back pressure is limited. This makes the strong cooling capacity of the air cooling island in winter unable to be fully utilized, affecting the coal saving and consumption reduction target, and further affecting the economic benefit of the unit. Therefore, solving the anti-freezing problem of the counterflow zone of the air cooling island is crucial to improve the operation safety and economic benefit of the unit. SUMMARY

[0005] The purpose of the present application is to provide a steam condenser for a steam turbine generator set, to solve the problems of low efficiency and serious freezing in the counterflow tube bundle area of the existing steam condenser of the air cooling island, so as to eliminate the obstacles to reducing the system back pressure to save coal for the steam turbine generator set.

[0006] The steam condenser for a steam turbine generator set comprises a steam main pipe 1 and a condensate pipe 2, and further comprises a convection zone heat dissipation unit A and a counterflow zone heat dissipation unit B; the steam main pipe 1 is connected to the inlet of the convection zone heat dissipation unit A, the condensate pipe 2 is connected to the outlet of the convection zone heat dissipation unit A, and the condensate pipe 2 is further connected to the inlet and outlet of the counterflow zone heat dissipation unit B; the counterflow zone heat dissipation unit B uses heat pipes to realize heat dissipation and condensation, and the counterflow zone heat dissipation unit B uses vacuum pumping to remove air in the water.

[0007] The present application removes all the tube-type heat exchange structures of the "counterflow cooling tube bundle" from the A-shaped tube bundle of the air cooling island, and replaces them with "convection cooling tube bundles" in the original space position, realizes the complete separation of the space positions of the convection zone heat dissipation unit A and the counterflow zone heat dissipation unit B, makes them respectively in different temperature environments, respectively uses different heat exchange technologies, and makes the overall system operation without weak links. Thus, the efficiency of the overall heat dissipation and condensation of the system is improved. As a high-efficiency heat transfer element exceeding the tube-type heat exchange method, the heat pipe realizes rapid heat transfer by using the phase change process. In addition, the medium inside the heat pipe has excellent low-temperature performance and can operate stably at -40℃, thereby significantly improving the anti-freezing ability of the air cooling island.

[0008] The present invention also provides another technical solution, which includes a steam header 1, a condensate pipe 2, a vacuum pump 4, several co-current tube bundles 9 and several counter-current tube bundles 90. The upper end of each co-current tube bundle 9 is connected to the steam header 1, and the lower end of each co-current tube bundle 9 is connected to the condensate pipe 2. The number of counter-current tube bundles 90 is less than the number of co-current tube bundles 9 and they are distributed among the several co-current tube bundles 9. The lower end of each counter-current tube bundle 90 is connected to the condensate pipe 2. The upper end of each counter-current tube bundle 90 is connected to the air inlet of the vacuum pump 4, and the exhaust port of the vacuum pump 4 is connected to the atmospheric environment to vent the released gas. It also includes several heat pipe heat exchange devices 8, one end of each heat pipe heat exchange device 8 is inserted into the counter-current tube bundle 90 to achieve thermal balance inside and outside the tube cavity of the counter-current tube bundle 90.

[0009] This technical solution modifies existing steam condensers by adding a heat pipe heat exchanger 8 to the existing countercurrent tube bundle 90. The rapid heat dissipation capability of the heat pipe heat exchanger 8 improves the operating efficiency of the countercurrent tube bundle. In winter, when temperatures are low, the system back pressure is increased to increase the water flow rate and prevent freezing in the countercurrent tube bundle. The heat transfer loss caused by the increased flow rate is compensated by the heat pipe heat exchanger 9. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the structure of the present invention. Figure 2 This is a schematic diagram of the structure of an existing air-cooled island. Figure 3 This is a schematic diagram of the alternating distribution of counter-current and co-current tube bundles in a conventional condenser. Figure 4 A schematic diagram illustrating the principle of steam and water condensation within the tube bundle of an air-cooled condenser. Figure 5 This is a schematic diagram of the steam flow state within the co-current tube bundle; Figure 6 This is a schematic diagram of the steam flow state inside the countercurrent tube bundle; Figure 7 This is a schematic diagram showing the separation arrangement of the co-current region and the heat pipe counter-current region in the condenser in Embodiment 1; Figure 8 for Figure 7 An enlarged structural diagram of the left half. Figure 9 This is a schematic diagram of the structure of Embodiment 2 of the present invention; Figure 10 This is a three-dimensional structural diagram of the water collection pipe, condensate pipe, and steam header in Implementation Method 2. Figure 11 This is a structural diagram of implementation method four. Figure 12 yes Figure 11 A schematic diagram of the structure viewed from below. Figure 13 This is a structural schematic diagram of implementation method nine. Detailed Implementation

[0011] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments.

[0012] Specific implementation one: combined Figure 1 The embodiment is illustrated, and the steam condenser of the steam turbine generator set comprises a steam main pipe 1 and a condensate pipe 2, and further comprises a downstream heat dissipation unit A and an upstream heat dissipation unit B; the steam main pipe 1 is connected to the inlet of the downstream heat dissipation unit A, the condensate pipe 2 is connected to the outlet of the downstream heat dissipation unit A, and the condensate pipe 2 is further connected to the inlet of the upstream heat dissipation unit B; the outlet of the upstream heat dissipation unit B is connected to a vacuum pump 4; the upstream heat dissipation unit B uses a heat pipe to realize heat dissipation and condensation; that is, the heat pipe technology is used to realize the discharge of heat in the cavity of the upstream heat dissipation unit B to the environment outside the cavity.

[0013] As shown in Figure 4 , 5 and 6, steam first enters the downstream pipe bundle, also known as the main condenser. In the main condenser, steam flows from top to bottom, and condensed water also flows from top to bottom. In the downstream pipe bundle, the condensed steam enters the lower part of the upstream pipe bundle through the lower connecting pipe, and in the upstream pipe bundle, steam flows from bottom to top, and condensed water flows from top to bottom. There is a "transition point" in both the downstream pipe bundle and the upstream pipe bundle. The transition point in the downstream pipe bundle refers to the point at which steam is completely condensed into water, and the position of the transition point depends on the load of the unit and the ambient temperature. The higher the position of the transition point, the greater the possibility of supercooling of the condensed water, and the greater the risk of freezing. The transition point in the upstream pipe bundle refers to the point at which steam is completely condensed into non-condensable gas, and in the non-condensable gas, flocculent ice is likely to form, blocking the flow cross section, so the fan of the upstream unit needs to be reversed to warm up according to the monitoring situation.

[0014] As shown in Figure 7 and Figure 8 , the present application can realize the spatial separation of the downstream heat dissipation unit A and the upstream heat dissipation unit B.

[0015] Specific implementation two: combined Figure 9 and Figure 10 The embodiment is specifically described. The embodiment is composed of a steam main pipe 1, a condensate pipe 2, a downstream pipe bundle 9, a first pipe shell 7, a second pipe shell 17, and a heat pipe heat exchange device 8. The steam main pipe 1 is horizontally arranged and located above the condensate pipe 2. A plurality of downstream pipe bundles 9 are connected between the steam main pipe 1 and the condensate pipe 2. The distal end of the condensate pipe 2 is connected to the inner cavities of the first pipe shell 7 and the second pipe shell 17. The heat pipe heat exchange device 8 penetrates into the shells of the first pipe shell 7 and the second pipe shell 17 to realize the heat balance inside and outside the cavities of the first pipe shell 7 and the second pipe shell 17. The first pipe shell 7 and the second pipe shell 17 are used to condense or precipitate and discharge the gas in the water outside the tank.

[0016] As shown in Figure 10As shown in the figure, the steam main pipe 1 is one, the condensate pipes 2 are two, the distal ends of the two condensate pipes 2 are respectively connected to the bottom ends of the first and second pipe shell bodies 7 and 17, the two condensate pipes 2 and the steam main pipe 1 above form a triangular arrangement, which looks like the English letter "A" from the side, the parallel flow pipe bundles 9 connected between the steam main pipe 1 and the two condensate pipes 2 form the left and right half-pitch heat dissipation units of the air cooling island, and the axial flow fan 6 is arranged between the left and right half-pitch heat dissipation units and has a height lower than the height of the plane where the two condensate pipes 2 are located. In this way, the heat dissipation efficiency is relatively high.

[0017] Specific implementation method three: in combination with Figure 9 In this embodiment, the difference from the second embodiment is that the distal ends of the condensate pipes 2 are obliquely connected to the bottom ends of the first and second pipe shell bodies 7 and 17, a vacuum pump 4 is arranged on the upper part of the tank body of the first and second pipe shell bodies 7 and 17, the air inlet of the vacuum pump 4 is connected to the inner cavities of the first and second pipe shell bodies 7 and 17, and the air outlet of the vacuum pump 4 is connected to the atmosphere to exhaust the separated gas. In this way, the gas-water mixture mixed with bubbles and the gas flow upward from the upper half of the condensate pipe 2 into the first and second pipe shell bodies 7 and 17 under the action of vacuum pumping, gradually condense the steam and exhaust the gas. While the water is collected in the lower half of the condensate pipe 2.

[0018] The angle X between the distal end of the condensate pipe 2 and the horizontal plane is between 14 degrees and 8 degrees.

[0019] Specific implementation method four: in combination with Figure 11 Specifically, in this embodiment, the difference from the second embodiment is that the outer surface of the heat pipe heat exchange device 8 is provided with heat conduction fins 8-1. In this way, the heat exchange efficiency between the heat pipe heat exchange device 8 and the environment is increased. The heat pipe is a heat transfer component with high thermal conductivity, which is composed of a pipe shell, a wick and an end cover. Its working principle is to use the evaporation and condensation of the working medium in the fully closed vacuum pipe shell to transfer heat, which has the advantages of high thermal conductivity, good isothermality, long-distance heat transfer, compact structure, small pressure loss, etc. After adding fins, the heat exchange efficiency between the heat pipe heat exchange device 8 and the environment is higher.

[0020] Specific implementation method five: in combination with Figure 11 Specifically, in this embodiment, the difference from the second embodiment is that it also includes an axial flow induced draft fan 15, the first and second pipe shell bodies 7 and 17 are arranged side by side and horizontally, the axial flow induced draft fan 15 is arranged below the overhead first and second pipe shell bodies 7 and 17 and guides the cold air upward, the part of the heat pipe heat exchange device 8 exposed to the air is arranged in the middle of the area between the first and second pipe shell bodies 7 and 17, and the airflow guided by the axial flow induced draft fan 15 blows toward the heat pipe heat exchange device 8. In this way, the heat exchange efficiency is improved.

[0021] Specific implementation six: the following is combined with Figure 11 Specific description of this embodiment. This embodiment is different from embodiment one in that it also includes an electric heater 16, which is an immersion heater, and the electric heater 16 is arranged in the cavities of the first pipe shell 7 and the second pipe shell 17. In this way, the anti-freezing protection of the gas treatment tank in winter is increased.

[0022] Specific implementation seven: this embodiment is different from embodiment two in that it also includes an electric heating device arranged in the cavity of the condensate pipe 2 and along the length direction of the condensate pipe 2. In this way, the condensate pipe can be protected from icing in cold winter. The electric heating device is selected from an electric heating rod or an electric heating pipe, such as an immersion heater commonly used in electric kettles. In terms of structure and function, it is a resistance wire sealed in a metal pipe (usually stainless steel), surrounded by an insulating and heat-conducting material (such as magnesium oxide powder), which can effectively transfer heat and insulate and protect. When powered on, the resistance wire generates heat, which is conducted to the water through the metal pipe, thereby achieving the heating function. The electric heater 16 in embodiment six can also be such an immersion heater.

[0023] Specific implementation eight: as shown in Figure 8 and Figure 11 This embodiment is different from embodiment two in that it also includes a third pipe shell 27, which is in communication with the cavities of the first pipe shell 7 and the second pipe shell 17 through the communication pipes 30, and the third pipe shell 27 is arranged above the first pipe shell 7 and the second pipe shell 17. The vacuum pump 4 is arranged on the third pipe shell 27 to apply vacuum to the first pipe shell 7, the second pipe shell 17, and the third pipe shell 27. The upper end of the heat pipe heat exchange device 8 is inserted into the cavity of the third pipe shell 27. In this way, a heat dissipation component is added, and the heat dissipation efficiency is higher.

[0024] Specific implementation nine: the following is combined with Figure 13 Specific description of this embodiment. It includes a steam main pipe 1, a condensate pipe 2, a vacuum pump 4, a plurality of forward flow pipe bundles 9, and a plurality of backward flow pipe bundles 90. The upper end of each forward flow pipe bundle 9 is in communication with the steam main pipe 1, and the lower end of each forward flow pipe bundle 9 is in communication with the condensate pipe 2. The number of backward flow pipe bundles 90 is less than the number of forward flow pipe bundles 9 and is dispersed between the plurality of forward flow pipe bundles 9. The lower end of each backward flow pipe bundle 90 is in communication with the condensate pipe 2. The upper end of each backward flow pipe bundle 90 is in communication with the air inlet of the vacuum pump 4, and the air outlet of the vacuum pump 4 is in communication with the atmosphere to exhaust the separated gas. It also includes a plurality of heat pipe heat exchange devices 8, one end of each heat pipe heat exchange device 8 being inserted into the backward flow pipe bundle 90 to achieve heat balance between the inside and outside of the backward flow pipe bundle 90.

[0025] The present embodiment slightly changes the prior art steam condenser, and installs the heat pipe heat exchange device 8 on the existing counterflow tube bundle 90, so as to improve the working efficiency of the counterflow tube bundle by using the rapid heat dissipation capacity of the heat pipe heat exchange device 8. The present embodiment slightly changes the original structure, and only changes locally, and the technical effect is reliable.

[0026] The present application has been disclosed in the preferred embodiments as above, however, not for limiting the present application, any person skilled in the art, without departing from the technical scheme of the present application, according to the technical essence of the present application, any simple modification, equivalent change and modification of the above embodiments, still belongs to the technical scheme range of the present application.

Claims

1. Steam condenser for steam turbine generator units, comprising a steam main (1) and a condensate pipe (2), characterized in that It also includes the heat dissipation unit (A) of the parallel flow area and the heat dissipation unit (B) of the counter flow area; the steam main pipe (1) is connected to the inlet of the heat dissipation unit (A) of the parallel flow area, the condensate pipe (2) is connected to the outlet of the heat dissipation unit (A) of the parallel flow area, and the condensate pipe (2) is also connected to the inlet and outlet of the heat dissipation unit (B) of the counter flow area; the heat dissipation unit (B) of the counter flow area uses heat pipes to achieve heat dissipation and condensation, and the heat dissipation unit (B) of the counter flow area uses vacuum pumping to remove air in the water.

2. The steam condenser for a steam turbine generator set according to claim 1, wherein the heat dissipation unit (A) of the parallel flow area includes a plurality of parallel flow pipe bundles (9), the heat dissipation unit (B) of the counter flow area includes a first pipe shell (7) and a heat pipe heat exchange device (8), the steam main pipe (1) is arranged horizontally and above the condensate pipe (2), a plurality of parallel flow pipe bundles (9) are arranged between the steam main pipe (1) and the condensate pipe (2), the distal end of the condensate pipe (2) is connected to the inner cavity of the first pipe shell (7), and the heat pipe heat exchange device (8) penetrates into the shell of the first pipe shell (7) to achieve heat balance inside and outside the cavity of the first pipe shell (7).

3. The steam condenser for a steam turbine generator unit according to claim 2, characterized by: It also includes a second pipe shell (17), the distal end of the condensate pipe (2) is connected to the bottom end of the first pipe shell (7) and the second pipe shell (17) in a slanting upward manner, the heat pipe heat exchange device (8) penetrates into the shell of the second pipe shell (17) to achieve heat balance inside and outside the cavity of the second pipe shell (17), a vacuum pump (4) is arranged on the upper part of the tank of the first pipe shell (7) and the second pipe shell (17), the air inlet of the vacuum pump (4) is connected to the inner cavities of the first pipe shell (7) and the second pipe shell (17), and the air outlet of the vacuum pump (4) is connected to the atmosphere to exhaust the extracted gas.

4. The steam condenser for a steam turbine generator unit according to claim 2 or 3, characterized by: The outer surface of the heat pipe heat exchange device (8) is provided with heat conduction fins (8-1).

5. The steam condenser for a steam turbine generator unit as set forth in claim 3, characterized by: It also includes an axial flow air blower (15), the first pipe shell (7) and the second pipe shell (17) are arranged horizontally side by side, the axial flow air blower (15) is arranged below the first pipe shell (7) and the second pipe shell (17) arranged in the air and blows cold air upward, the part of the heat pipe heat exchange device (8) exposed to the air is arranged in the middle of the area between the first pipe shell (7) and the second pipe shell (17), and the airflow guided by the axial flow air blower (15) blows toward the heat pipe heat exchange device (8).

6. The steam condenser for a steam turbine generator unit as set forth in claim 3, characterized by: It also includes an electric heater (16), which is an immersed electric heating tube, and the electric heater (16) is arranged in the cavities of the first pipe shell (7) and the second pipe shell (17).

7. The steam condenser for a steam turbine generator unit as set forth in claim 1, characterized by: It also includes an electric heating device, which is arranged in the inner cavity of the condensate pipe (2) and along the length direction of the condensate pipe (2).

8. The steam condenser for a steam turbine generator unit as set forth in claim 3, characterized by: It also includes a third tube shell (27) which communicates with the inner cavities of the first tube shell (7) and the second tube shell (17) through the communicating tubes (30) respectively, the third tube shell (27) is arranged above the first tube shell (7) and the second tube shell (17), the vacuum pump (4) is arranged on the third tube shell (27) to apply vacuumization to the first tube shell (7), the second tube shell (17) and the third tube shell (27), and the upper end of the heat pipe heat exchange device (8) is inserted into the cavity of the third tube shell (27).

9. A steam condenser for steam turbine generator unit, which comprises a steam main pipe (1), a condensate pipe (2), a vacuum pump (4), a plurality of parallel flow tube banks (9) and a plurality of counter flow tube banks (90), the upper end of each parallel flow tube bank (9) being connected to the steam main pipe (1), the lower end of each parallel flow tube bank (9) being connected to the condensate pipe (2), the number of counter flow tube banks (90) being less than the number of parallel flow tube banks (9) and being arranged between the plurality of parallel flow tube banks (9) in a scattered manner, the lower end of each counter flow tube bank (90) being connected to the condensate pipe (2), the upper end of each counter flow tube bank (90) being connected to the air inlet end of the vacuum pump (4), the air outlet of the vacuum pump (4) being connected to the atmosphere to exhaust the separated gas, characterized in that It also includes a plurality of heat pipe heat exchange devices (8), one end of each heat pipe heat exchange device (8) is inserted into the counterflow tube bundle (90) to achieve heat balance inside and outside the tube cavity of the counterflow tube bundle (90).

Images