Vacuum system with condensing function

Abstract

The utility model relates to a vacuum system with a condensing function. The vacuum system comprises an evaporative condensing device, a front shell and tube condenser and a combined vacuum unit, the front shell and tube condenser is connected in series on a vacuum pipeline between an original condenser and a raw water ring vacuum pump of the generator set; the air inlet end of the evaporative condensing device is connected with an upper square box of the original condenser through a steam drainage pipe, the air outlet end of the evaporative condensing device is connected with a vacuum pipeline located at the front end of the front shell and tube condenser, the water outlet end of the evaporative condensing device is connected with an original condensing water tank of the generator set, and the horizontal height of the water outlet end is larger than that of the original condensing water tank. The combined vacuum unit comprises a roots vacuum pump and a water ring vacuum pump which are sequentially connected in series, and an air inlet of the roots vacuum pump is connected with an air outlet of the front shell and tube condenser. The device is low in investment cost and high in limit vacuum degree, can effectively improve the power generation efficiency of the condensing steam turbine unit, and meets the technical improvement requirements of energy conservation and efficiency improvement after the unit operates for a long time.

Description

Technical Field

[0001] The utility model relates to a vacuum system with a condensing function, belonging to the technical field of condensing power generation equipment. Background Art

[0002] Among the existing domestic coal-fired or gas-fired power stations, waste heat utilization power stations, and biomass power stations, 90% are condensing steam generator sets. Figure 1 After long-term operation, the performance of the cold-end equipment of condensing steam generator sets generally suffers from a decrease in vacuum value due to a decrease in condensing capacity, which ultimately leads to a decrease in power generation efficiency and higher energy consumption. Generally, a decrease in vacuum value of 1kPa will result in a decrease in power generation efficiency of 1-2%.

[0003] At present, the conventional transformation technologies for this problem are:

[0004] 1. Condenser Renovation: To solve the fouling problem, there are three methods: manual regular cleaning, automatic cleaning with rubber balls, and automatic cleaning with rotating belts. However, due to factors such as durability and instability, this renovation method has been gradually abandoned.

[0005] 2. Cooling tower optimization: Improve cooling capacity, but due to design limitations, the improvement is generally small;

[0006] 3. Vacuum pump transformation: Replace the vacuum pump type, but the vacuum pump suction capacity is proportional to energy consumption. Simply relying on increasing the vacuum pump suction capacity will greatly increase energy consumption.

[0007] However, given the performance characteristics of condensing steam turbine generator sets, there are many factors that affect vacuum degradation. Therefore, retrofitting cannot be considered solely from a unilateral perspective. A comprehensive assessment of the cold-end equipment performance, followed by optimization, is the primary technical path for current technical transformation. Only by employing relatively low-input, high-output solutions, such as improving vacuum, reducing back pressure, increasing efficiency, and reducing energy consumption, can the long-term goal of energy conservation and efficiency improvement be achieved.

[0008] Therefore, for the condensing steam turbine units that have already undergone renovation of the original cold end equipment but have not yet achieved the technical effect, a new renovation plan is urgently needed to achieve the technical renovation goals of low investment, high vacuum, high power generation efficiency, and maintain long-term energy saving and efficiency improvement. Summary of the Invention

[0009] The purpose of this utility model is to overcome the above-mentioned shortcomings and provide a low-investment, high-vacuum vacuum system with condensing function to improve the power generation efficiency of the condensing steam turbine unit, thereby solving the problem that the original cold end equipment of the condensing steam turbine generator unit cannot achieve the transformation effect after transformation, and achieving the purpose of long-term energy saving and efficiency improvement.

[0010] The purpose of this utility model is achieved in this way:

[0011] A vacuum system with a condensing function comprises an evaporative condensing device, a front shell and tube condenser, and a combined vacuum unit; the front shell and tube condenser is connected in series on the vacuum pipeline between the original condenser and the original water ring vacuum pump of the generator set; the air inlet end of the evaporative condensing device is connected to the upper square box of the original condenser through a steam drainage pipe, the air outlet end is connected to the vacuum pipeline located at the front end of the front shell and tube condenser, and the water outlet end is connected to the original condensate tank of the generator set, and the horizontal height of the water outlet end is higher than the original condensate tank; the combined vacuum unit is arranged in parallel with the original water ring vacuum pump, and comprises a Roots vacuum pump and a water ring vacuum pump connected in series in sequence, and the air inlet of the Roots vacuum pump is connected to the air outlet of the front shell and tube condenser.

[0012] Furthermore, the front shell and tube condenser, Roots vacuum pump and water ring vacuum pump are all provided with independent heat exchangers, and each heat exchanger is connected in parallel with the cooling water supply pipeline.

[0013] Furthermore, the condensate outlet of the front shell and tube condenser is connected to the original condensate tank.

[0014] Furthermore, the front shell and tube condenser includes a shell, a head tube box and a tail tube box respectively arranged at the left and right ends of the shell; the left side of the head tube box is connected to an inlet flange; the top of the tail tube box is connected to the original outlet flange; and a heat exchange exhaust pipe is arranged inside the shell.

[0015] Furthermore, the evaporative condensing device includes a casing, an air inlet and an air outlet respectively arranged on the left and right sides of the casing, a plurality of groups of row pipes arranged in parallel in the casing and connected to the air inlet and the air outlet, a spray pipe arranged above the row pipe, a circulating water tank arranged at the bottom of the casing, and a circulating water pump that draws cooling water in the circulating water tank into the spray pipe; the air inlet end is provided with an inlet distributor connected in parallel with each group of row pipes, which respectively introduces the gas discharged from the reactor into each group of row pipes; the air outlet end is provided with a gas-liquid separator connected in parallel with each group of row pipes, which collects the cooled non-condensable gas and discharges it into the vacuum pipeline, and at the same time collects the liquid produced after condensation, which flows into the original condensate tank of the generator set from the water outlet end.

[0016] Furthermore, the water outlet is connected to a U-shaped elbow that serves as an isolation.

[0017] Furthermore, a heat exhaust fan is provided on the top of the casing, and a water collector is provided below the heat exhaust fan to collect water vapor.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] The utility model connects an evaporative condensing device in parallel to the original condenser of the generator set, thereby enhancing the condensing capacity, lowering the gas temperature, recovering the condensed water, reducing the gas volume, reducing the vacuum load, and improving the power generation efficiency. A combined vacuum unit consisting of a high-efficiency Roots vacuum pump and a water ring vacuum pump connected in series is connected in parallel to the original water ring vacuum pump of the generator set, further improving the suction capacity of the vacuum pump, effectively compensating for the vacuum degree drop caused by long-term operation of the generator set, forming a high-strength pressure difference between the vacuum pump inlet pressure and the turbine exhaust pressure, and improving the power generation efficiency of the turbine. A pre-shell and tube condenser is installed on the main pipeline before the inlet of the vacuum pump for cooling the saturated wet air extracted from the condenser and condensing and recovering the condensable gas, thereby reducing the suction load of the vacuum pump, improving the suction capacity of the vacuum pump, and improving the power generation efficiency. The overall investment cost of the device is low, the vacuum degree is high, and the power generation efficiency of the condensing steam turbine set is improved, thereby solving the problem that the original cold end equipment of the condensing steam turbine generator set cannot achieve the desired transformation effect after transformation, and achieving the purpose of long-term energy saving and efficiency improvement. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the process principle diagram of the existing condensing steam generator set.

[0021] Figure 2 This is a schematic diagram of a vacuum system with condensing function in the utility model.

[0022] Figure 3 The utility model is a structural schematic diagram of an evaporative condensing device of a vacuum system with a condensing function.

[0023] Figure 4 The utility model is a structural schematic diagram of a front shell and tube condenser of a vacuum system with a condensing function.

[0024] Figure 5 This is a connection principle diagram of a combined vacuum unit of a vacuum system with a condensing function in the utility model.

[0025] in:

[0026] Evaporative condensing device 1, front shell and tube condenser 2, combined vacuum unit 3, original condenser 4, original water ring vacuum pump 5, vacuum pipeline 6, original condensate tank 7;

[0027] Steam drainage pipe 11, air inlet end 12, air outlet end 13, water outlet end 14, casing 15, drain pipe 16, spray pipe 17, circulating water tank 18, circulating water pump 19, inlet distributor 120, gas-liquid separator 130, U-shaped bend pipe 140, exhaust fan 150, water collector 151;

[0028] Shell 21, head pipe box 22, tail pipe box 23, inlet flange 24, outlet flange 25, heat exchange exhaust pipe 26, condensate outlet 27;

[0029] Roots vacuum pump 31, water ring vacuum pump 32. DETAILED DESCRIPTION

[0030] See also Figures 2-5 The utility model relates to a vacuum system with a condensing function, comprising an evaporative condensing device 1, a front shell and tube condenser 2, and a combined vacuum unit 3;

[0031] The front shell and tube condenser 2 is connected in series on the vacuum pipeline 6 between the original condenser 4 and the original water ring vacuum pump 5 of the generator set; the front shell and tube condenser 2 includes a shell 21, a head pipe box 22 and a tail pipe box 23 respectively arranged at the left and right ends of the shell 21; the left side of the head pipe box 22 is connected with an inlet flange 24; the top of the tail pipe box 23 is connected to the original outlet flange 25, and the bottom is provided with a condensate outlet 27, which is connected to the original condensate tank 7; a heat exchange exhaust pipe 26 is provided inside the shell 21; cooling water is passed through the heat exchange exhaust pipe 26, and the gas enters the head pipe box 22 from the inlet flange 24 end, and enters the tail pipe box 23 after heat exchange and cooling between the shell 21 and the heat exchange exhaust pipe 26, where due to the cooling effect, the condensable gas is converted into liquid, that is, water vapor is converted into condensate, which flows into the original condensate tank 7 of the generator set from the condensate outlet, and the non-condensable gas is discharged from the outlet flange 25 end;

[0032] A pre-shell-and-tube condenser 2 is installed on the main pipeline before the vacuum pump's inlet. This condenser is specifically designed for condensing gas. Cooling water flows through the tube side of the condenser, while mixed gas flows through the shell side. This condenser is used to cool the saturated moist air extracted from the condenser, condense and recover condensable gases, and reduce the vacuum pump's suction load. Because the gas phase change process is equivalent to a pressure change process, the reduction in gas volume naturally forms a vacuum inside the container, which is equivalent to adding a vacuum pump unit. The installation of a pre-condenser can condense and recover approximately 60-70% of the moist air, reducing the vacuum pump load by 60-70%. The ultimate vacuum can be increased by 10 orders of magnitude, greatly improving the vacuum pump's suction capacity. This creates a high pressure differential of approximately 4-6 kPa between the vacuum pump inlet pressure and the turbine exhaust pressure, thereby improving power generation efficiency.

[0033] The evaporative condensing device 1 includes a casing 15, an air inlet end 12 and an air outlet end 13 respectively arranged on the left and right sides of the casing 15, a plurality of rows of pipes 16 arranged in parallel in the casing 15 and connecting the air inlet end 12 and the air outlet end 13, a spray pipe 17 arranged above the row pipe 16, a circulating water tank 18 arranged at the bottom of the casing 15, and a circulating water pump 19 that draws cooling water in the circulating water tank 18 into the spray pipe 17; a heat exhaust fan 150 is provided at the top of the casing 15, and a water collector 151 is provided below the heat exhaust fan 150 to collect water vapor, and return it to the circulating water tank 18, and the circulating water pump 19 pumps water for circulation and cooling. The evaporative condensing device 1 is arranged in parallel with the original condenser 4. Specifically, the air inlet end 12 is connected to the upper square box of the original condenser 4 through the steam drainage pipe 11. An inlet distributor 120 connected in parallel with each group of row pipes 16 is provided on the air inlet end 12 to guide the incoming steam into each group of row pipes 16 respectively; the air outlet end 13 is connected to the vacuum pipeline 6 located at the front end of the front shell and tube condenser 2, and a gas-liquid separator 130 connected in parallel with each group of row pipes 16 is provided on the air outlet end 13. A gas-liquid separator 130 is provided at the lower part of the gas-liquid separator 130 to connect to the original condenser of the generator set. The condensate tank 7 is connected to the water outlet 14, and the level of the water outlet 14 is higher than the original condensate tank 7. The water outlet 14 is connected to the U-shaped bend pipe 140 for isolation. The mixed gas after cooling is discharged into the vacuum pipeline 6 through the gas outlet at the top of the gas outlet 13, and the condensed water produced after condensation is collected and flows into the original condensate tank 7 of the generator set from the water outlet 14. The U-shaped bend pipe 140 can ensure the gas-liquid isolation between the vacuum system and the condensate, so that the condensate can be automatically and continuously discharged into the original condensate tank 7 without damaging the vacuum system.

[0034] The evaporative condensing device 1 is installed outdoors in parallel with the original condenser, and the mature evaporative condensation technology is used to further enhance the condensing capacity, reduce the gas temperature, reduce the gas volume, reduce the vacuum load, and improve the power generation efficiency;

[0035] The combined vacuum unit 3 includes a Roots vacuum pump 31 and a water ring vacuum pump 32 connected in series. The air inlet of the Roots vacuum pump 31 is connected to the air outlet, i.e., the outlet flange 25, of the pre-shell-and-tube condenser 2. The pre-shell-and-tube condenser 2, the Roots vacuum pump 31, and the water ring vacuum pump 32 are each equipped with an independent heat exchanger, and each heat exchanger is connected in parallel to a cooling water supply pipeline. The heat exchanger of the pre-shell-and-tube condenser 2 is the shell 21 and the heat exchange pipe 26 structure.

[0036] By connecting the Roots vacuum pump 2 and the water ring vacuum pump 3 in series and then in parallel with the original water ring vacuum pump 5, the suction capacity of the vacuum system can be greatly improved, effectively compensating for the vacuum drop caused by the long-term operation of the generator set, and forming a high pressure difference between the vacuum pump inlet pressure and the turbine exhaust pressure, thereby improving the turbine power generation efficiency and ensuring system safety;

[0037] Retrofit application of a 30MW double super steam reheat gas condensing steam turbine generator set:

[0038] The main equipment at the cold end before the renovation included: shell and tube condensing system, condensate system, cooling water circulation system, and vacuum system. The designed exhaust steam capacity was 61t / h in winter with an exhaust steam back pressure of 7kPa, and 66t / h in summer with an exhaust steam back pressure of 10kPa. The condenser heat exchange area was 1150m 2 , the vacuum pump maintains power 22kw.

[0039] Problems: Exhaust steam back pressure is 3-5kPa higher than the design value, and power generation efficiency drops by 4.5-7.5%.

[0040] Cause analysis: 1. Insufficient heat exchange area of ​​the condenser (original design defect), serious fouling and reduced heat exchange efficiency; 2. Vacuum tightness problem, serious system leakage has reached 600pa / min (mainly turbine shaft seal leakage); 3. Cooling tower efficiency has decreased, the reduction is small and the energy consumption is high (original design defect).

[0041] In response to the above problems, the solution adopts the vacuum system with condensing function of the utility model:

[0042] 1. Use mature evaporative condensation technology equipment and install it outdoors in parallel with the original condenser to enhance the condensation capacity; the evaporative condensation technology equipment is the evaporative condensation device 1;

[0043] 2. The vacuum system is modified to adopt a Roots water ring vacuum unit + a pre-condenser, replacing a single stage with multiple stages to enhance the ultimate vacuum value and suction capacity; the Roots water ring vacuum unit is a combined vacuum unit 3; the pre-condenser is a pre-shell and tube condenser 2.

[0044] In addition: It should be noted that the above specific implementation is only an optimization scheme of this patent. Any changes or improvements made by technicians in this field based on the above concept are within the scope of protection of this patent.

Claims

1. A vacuum system with condensing function, characterized in that: The invention comprises an evaporative condensing device (1), a front shell and tube condenser (2), and a combined vacuum unit (3); the front shell and tube condenser (2) is connected in series to a vacuum pipeline (6) between an original condenser (4) of a generator set and an original water ring vacuum pump (5); an air inlet end (12) of the evaporative condensing device (1) is connected to an upper square box of the original condenser (4) through a steam drainage pipe (11), and an air outlet end (13) is connected to a square box located at the front shell and tube condenser ( 2) The front end vacuum pipeline (6) is connected, the water outlet (14) is connected to the original condensate tank (7) of the generator set, and the horizontal height of the water outlet (14) is higher than the original condensate tank (7); the combined vacuum unit (3) is arranged in parallel with the original water ring vacuum pump (5), and includes a Roots vacuum pump (31) and a water ring vacuum pump (32) connected in series, and the air inlet of the Roots vacuum pump (31) is connected to the air outlet of the front shell and tube condenser (2).

2. The vacuum system with condensing function according to claim 1, characterized in that: The front shell and tube condenser (2), the Roots vacuum pump (31) and the water ring vacuum pump (32) are all provided with independent heat exchangers, and each heat exchanger is connected in parallel to a cooling water supply pipeline.

3. The vacuum system with condensing function according to claim 1, characterized in that: The condensate outlet of the front shell and tube condenser (2) is connected to the original condensate tank (7).

4. The vacuum system with condensing function according to claim 1, characterized in that: The front shell and tube condenser (2) comprises a shell (21), a head tube box (22) and a tail tube box (23) respectively arranged at the left and right ends of the shell (21); the left side of the head tube box (22) is connected to an inlet flange (24); the top of the tail tube box (23) is connected to the original outlet flange (25); and a heat exchange exhaust pipe (26) is arranged inside the shell (21).

5. The vacuum system with condensing function according to claim 1, characterized in that: The evaporative condensing device (1) comprises a casing (15), an air inlet (12) and an air outlet (13) respectively arranged on the left and right sides of the casing (15), a plurality of sets of pipes (16) arranged in parallel in the casing (15) and connected to the air inlet (12) and the air outlet (13), a spray pipe (17) arranged above the pipes (16), a circulating water tank (18) arranged at the bottom of the casing (15), and a device for pumping cooling water in the circulating water tank (18) into the spray pipe (17). A circulating water pump (19); the air inlet end (12) is provided with an inlet distributor (120) connected in parallel with each group of pipes (16), and the gas discharged from the reactor is respectively introduced into each group of pipes (16); the air outlet end (13) is provided with a gas-liquid separator (130) connected in parallel with each group of pipes (16), which collects the cooled non-condensable gas and discharges it into the vacuum pipeline, and at the same time collects the liquid produced after condensation, and flows into the original condensate tank (7) of the generator set from the water outlet end (14).

6. The vacuum system with condensing function according to claim 5, characterized in that: The water outlet end (14) is connected to a U-shaped elbow (140) that serves as an isolation.

7. The vacuum system with condensing function according to claim 5, characterized in that: A heat exhaust fan (150) is provided on the top of the housing (15), and a water collector (151) is provided below the heat exhaust fan (150) to collect water vapor.

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