Reliable drainage recovery system for power plants

Abstract

We provide a highly reliable drain recovery system for power plants. [Solution] The system includes a drain collection tank 1 with an air curtain 2 on top, a water collection source 6 and a water collection pipe 3 connected to the drain collection tank, respectively, and a condensation device 9, 10 and a water suction pipe 4 connected to the drain collection tank, respectively, wherein the air pressure in the condensation device is lower than atmospheric pressure, the vertical height of the water suction pipe is higher than the height of the water column that can be pumped up at standard atmospheric pressure, the water collection pipe is directly connected to the water collection source via a shutoff door 13, and drain wastewater flows from the water collection source into the drain collection tank by gravity.

Description

[Technical field]

[0001] The present invention relates to the technical field of boiler installations, and in particular to a reliable wastewater recovery system for power plants. [Background technology]

[0002] In thermal power plants, some secondary reheat supercritical boilers are equipped with a collection tank. During the start-up phase of the boiler, the drain pump is started to discharge the drainage in the collection tank into the circulating water return pipe, and the drainage is collected after the water quality meets the requirements. During normal operation, if the water level of the drainage in the collection tank is too high, the drainage is collected into the condensation system through the drain pump.

[0003] However, this design has certain risks. After a period of operation, the piping from the drain pump outlet to the target position is long, so when the drain pump is started, the piping will shake violently, and the welds may break due to long-term start and stop. In addition, if the three outlet doors draining to the condensation system leak or open incorrectly, or the drain pump is not stopped at the right time after starting, the vacuum level of the condenser may decrease, and in the worst case, it may cause abnormal conditions such as protection operation and unit tripping.

[0004] Some drain recovery devices install a recovery container to temporarily store the drainage water, send the drainage water into the recovery container with a water pump, and then send the drainage water to a destination facility for recovery. However, these containers usually occupy a large volume and are relatively expensive, so an urgent issue that needs to be resolved is how to reduce the volume of the additional recovery container while maintaining the original functionality. Summary of the Invention [Means for solving the problem]

[0005] The object of the present invention is to provide a highly reliable drain recovery system for power plants in order to overcome the drawbacks of the above-mentioned conventional technology, and to solve or partially solve the problem that the recovery container in the drain recovery system is large and it is difficult to reduce the size while maintaining the original function.

[0006] The objective of the present invention may be achieved by the following technical solutions:

[0007] The present invention provides a reliable drain recovery system for a power plant, the system comprising: A drain collection tank having an air curtain on the top; a water collection pipe connected to a water collection source and the drain recovery tank, respectively; a condensation device and a suction pipe connected to the drain recovery tank, The air pressure in the condensation equipment is lower than atmospheric pressure, the vertical height of the suction pipe is higher than the height of the water column that can be pumped up at standard atmospheric pressure, the water collection pipe is directly connected to the water collection source via a shut-off door, and drainage flows from the water collection source into the drain recovery tank by gravity.

[0008] As a preferred technical solution, the top of the drain recovery tank is further provided with an ultrasonic level sensor.

[0009] As a preferred technical solution, the end of the suction pipe close to the drain collection tank is 10 to 30 mm away from the bottom of the drain collection tank.

[0010] As a preferred technical solution, the rule for determining the vertical height of the suction pipe is as follows: The distance between the water level in the drain recovery tank and the end of the suction pipe close to the drain recovery tank is greater than a preset value.

[0011] As a preferred technical solution, the vertical height of the suction pipe is 10.5-13m.

[0012] As a preferred technical solution, the air pressure in the condensation equipment is 80-120 kPa.

[0013] As a preferred technical solution, said water collection source is an atmospheric expansion water collection tank.

[0014] As a preferred technical solution, the drain collection tank is connected to the ground via a bracket.

[0015] As a preferred technical solution, the intake pipe has the same diameter as the collection pipe.

[0016] As a preferred technical solution, the condensation equipment includes a low back pressure condenser and a high back pressure condenser.

[0017] As a preferred technical solution, the suction pipe is connected to the auxiliary opening of the condensation installation.

[0018] As a preferred technical solution, the bracket comprises: A support plate connected to the drain wastewater recovery tank; and support legs each connected to the support plate.

[0019] As a preferred technical solution, the diameter of the drain recovery tank is 600mm to 1000mm, and the volume is 1.0m 3 ~3.0m 3 It is.

[0020] Compared with the prior art, the present invention has at least one of the following beneficial effects: (1) Reducing the minimum design volume of the drain collection tank. In view of the current problems that when the water pump operates in low flow mode to send drainage to the collection container, the water pump has a short service life and consumes a lot of power, and when it operates in time-specified mode, the water pump has a high minimum volume requirement for the drain collection tank. In this invention, the drain collection tank is installed so that the collection pipe is directly connected to the water collection source through a blocking door, and the drainage flows from the water collection source into the drain collection tank by gravity, and then is sent to the condensation equipment by utilizing the negative pressure in the condensation equipment, thereby realizing pump-free drain collection in the entire process. While no power consumption is required during drain collection, the minimum volume requirement of the drain collection tank is low, and the drain collection tank can be made smaller while maintaining its original function. (2) Reducing the possibility of the drain collection tank overflowing / running empty. By making the suction pipe and the collection pipe the same diameter, this device limits the flow rate of drainage water entering and exiting the drain collection tank to some extent, thereby reducing the possibility of the drain collection tank overflowing / running empty to some extent. (3) High safety. In order to solve the problem that the water level in the drain recovery tank is too low and may affect the internal pressure of the condensation equipment, the present invention sets the vertical height of the suction pipe higher than the height of the water column that can be pumped up at standard atmospheric pressure, and sets the vertical height of the suction pipe based on the principle that the distance between the water level in the drain recovery tank and the end of the suction pipe close to the drain recovery tank is greater than a preset value, thereby maintaining a safe water level in the drain recovery tank, and based on this, adds an ultrasonic level sensor to monitor the liquid level. (4) Easy to implement. The present invention does not require laying additional pipelines, and does not require shutting down the unit during modification work, and the work can be carried out normally while the unit is in operation. (5) Energy saving and emission reduction effects are significant. On the one hand, the retrofit cost of this invention is low, and on the other hand, evaluations show that the recovered condensate can bring enormous economic and environmental benefits. [Brief description of the drawings]

[0021] [Figure 1] 1 is a schematic diagram of a pump-free condensate collection system for a power plant in an embodiment. 1, condensate collection tank, 2, air curtain, 3, collection pipe, 4, suction pipe, 5, ultrasonic level sensor, 6, atmospheric expansion collection tank, 7, bracket, 8, reserve opening, 9, low back pressure condenser, 10, high back pressure condenser, 11, reserve pipe, 12, condensate pump pit, 13, isolation door. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The technical solutions in the embodiments of the present invention are described below clearly and completely with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts are included in the scope of protection of the present invention.

[0023] In the description of the present invention, the orientations and positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside" and "outside" are based on the orientations and positional relationships shown in the drawings or the orientations and positional relationships in which the product of the present invention is usually placed when used. This is only for the purpose of explaining and simplifying the description of the present invention, and does not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. For example, "horizontal" only means that the direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, and it is acceptable to tilt slightly.

[0024] Considering the problems existing in the prior art as mentioned above, the present embodiment provides a reliable wastewater recovery system for power plants. Referring to FIG. 1, the system includes: The drain recovery tank 1 is provided in the condensate pump pit 12, and the top of the drain recovery tank 1 is provided with an air curtain 2, a reserve pipe 11, an ultrasonic level sensor 5, a water collection pipe 3, and a water suction pipe 4. The water collection pipe 3 is connected to the water collection source and the drain recovery tank 1, respectively, and the water suction pipe 4 is connected to the reserve opening 8 of the condensation equipment and the drain recovery tank 1, respectively. The air curtain 2 communicates the inside and outside of the drain recovery box 1, and ensures the balance of the air pressure inside and outside. The reserve pipe 11 is used for maintenance. The ultrasonic level sensor 5 is used to monitor whether the liquid level inside is within a safe range, and to issue an alarm when the liquid level is too low or too high. The water collection pipe (3) is directly connected to the water collection source through a shutoff door (13), and the drain drainage flows from the water collection source into the drain recovery tank (1) by gravity flow.

[0025] In this embodiment, the water collection source is an atmospheric expansion water collection tank 6, and the condensation equipment includes a low back pressure condenser 9 and a high back pressure condenser 10. Note that the water collection source and the condensation equipment may be replaced with other devices without competing with each other.

[0026] In the system, the air pressure in the condensation facility is lower than atmospheric pressure, and the vertical height of the suction pipe 4 is higher than the height of the water column that can be pumped up at standard atmospheric pressure. The distance between the water level in the drain recovery tank 1 and the end of the suction pipe 4 close to the drain recovery tank 1 is greater than a preset value. Preferably, the preset value is 1 meter, the end of the suction pipe 4 close to the drain recovery tank 1 is 10-30 mm away from the bottom of the drain recovery tank 1, the vertical height of the suction pipe 4 is 10.5-13 m, and the air pressure in the condensation facility is 80-120 kPa.

[0027] In a specific embodiment, the reference height of the ground where the steam turbine is located is set to 0 meters, and a manual shutoff door 13 (at an altitude of about 4.0 meters) is connected to the upper opening of the sewage pipe leading from the atmospheric expansion collecting tank 6 to the unit drain, and is connected to the condensate pump pit 12 via a φ50 mm stainless steel pipe (i.e., suction pipe 4), and a φ800 mm pipe with a volume of 2.0 m is located 4 meters below 0 meters. 3Install the drain collection tank 1 and attach the bracket 7 to its bottom. The bracket 7 includes a support plate connected to the bottom of the drain collection tank 1 to prevent rust and corrosion of the water tank. Install the ultrasonic radar level sensor 5 on the upper part of the water tank, connect a stainless steel water suction pipe with a diameter of 50 mm as the water suction pipe 4 to the preliminary opening with an elevation of 7.8 meters of the condenser, insert it 20 mm away from the bottom inside the water tank, and the cumulative height of the water suction pipe is estimated to be about 11.8 meters, and utilize the vacuum of the condenser to suck the drain water in the drain collection tank.

[0028] When the drain water is ideal pure water, it can suck up a water column of 10.32 meters under 1 standard atmosphere. Based on this principle, when the vacuum degrees of the condensers of the generator sets are calculated as 92 kPa in summer and 99 kPa in winter, the water level in the water tank is maintained at least 2.3 meters in summer and at least 1.5 meters in winter, and a safety distance of more than 1 meter is ensured from the water suction port at the bottom.

[0029] The atmospheric expansion water collection tank 6 is located on the boiler platform with an elevation of 4.2 meters, has a diameter of 2.5 meters, a total length of about 6.9 meters, and a designed volume of 31m 3There is a 1000mm water level gauge on the center line of the cylinder. According to past trend analysis, at an average load of 520MW, the water level rises from 0 to about 1100mm every 5 hours. Based on this, about 17 tons of desalinated water is discharged into the drain of the unit every 5 hours. This is about 3.4 tons per hour. Based on the annual average load of 520MW and the designed water supply of 1293t / h, recovering this part of the drainage can reduce the water make-up rate of the unit by about 0.26%. These two units can save 4,896 tons of desalinated water make-up every month. Currently, the production cost of desalinated water includes the cost of medicines such as resin and acid-alkali solution, electricity consumption, steam consumption, equipment depreciation, etc., and is about 19 yuan per ton. Based on this, it can save 87,324 yuan per month and about 1.05 million yuan per year. At the same time, it can reduce a large amount of carbon emissions. Recovering this part of the drainage will bring great economic and environmental benefits.

[0030] This system has the following advantages: The volume of the drain collection tank 1 can be relatively small, about 2.0 m 3 A stainless steel water tank of 1.0 mm is sufficient, steel consumption is small, cost is low, the water in the atmospheric expansion collecting tank 6 flows by gravity, there is no need to start the drain pump, power consumption is low, there is no need to pay attention to the water level in the collecting tank on the monitoring panel, only need to collect the water by gravity. The investment is small, only a stainless steel pipe of φ50 mm is required, it is safe and reliable, and does not affect the vacuum of the condenser. The construction cost is low and the economic benefit is large. The construction is carried out when the unit is stopped and is usually completed in 2 days.

[0031] The above description is merely a specific embodiment of the present invention, and the scope of protection of the present invention is not limited thereto, and those skilled in the art can easily think of various equivalent modifications and replacements within the technical scope disclosed in the present invention, and these modifications and replacements should also be included in the scope of protection of the present invention. Therefore, the scope of protection of the present disclosure should be subject to the scope of protection of the claims.

Claims

1. A highly reliable drain recovery system for a power plant, A drain recovery tank (1) having an air curtain (2) on the top thereof; A water collection pipe (3) connected to a water collection source and the drain recovery tank (1), respectively; a suction pipe (4) connected to the condensation equipment and the drain recovery tank (1), A highly reliable drain recovery system for a power plant, characterized in that the air pressure in the condensation equipment is lower than atmospheric pressure, the vertical height of the suction pipe (4) is higher than the height of the water column that can be pumped up at standard atmospheric pressure, the water collection pipe (3) is directly connected to the water collection source via a blocking door (13), and drain wastewater flows from the water collection source to the drain recovery tank (1) by gravity flow.

2. 2. A highly reliable drain recovery system for a power plant according to claim 1, further comprising an ultrasonic level sensor (5) at the top of the drain recovery tank (1).

3. 2. A highly reliable drain recovery system for a power plant according to claim 1, characterized in that an end of the suction pipe (4) close to the drain recovery tank (1) is 10 to 30 mm away from the bottom of the drain recovery tank (1).

4. The rules for determining the vertical height of the suction pipe (4) are as follows:

2. A highly reliable drain recovery system for a power plant according to claim 1, characterized in that a distance between a water level in the drain recovery tank (1) and an end of the suction pipe (4) close to the drain recovery tank (1) is greater than a preset value.

5. The diameter of the drain recovery tank (1) is 600 mm to 1000 mm, and the volume is 1.0 m ３ ~3.0m ３ 2. A highly reliable drain recovery system for a power plant according to claim 1 .

6. 2. A reliable drain recovery system for a power plant according to claim 1, characterized in that the water collection source is an atmospheric expansion water collection tank (6).

7. 2. A reliable drain recovery system for a power plant according to claim 1, characterized in that the drain recovery tank (1) is connected to the ground via a bracket (7).

8. The bracket (7) is A support plate connected to the drain recovery tank (1); 8. A highly reliable drain recovery system for a power plant according to claim 7, further comprising support legs connected to said support plates, respectively.

9. 2. A reliable drain recovery system for a power plant according to claim 1, characterized in that the suction pipe (4) has the same diameter as the collection pipe (3).

10. 2. A reliable drain recovery system for a power plant according to claim 1, characterized in that the condensation installation comprises a low back pressure condenser (9) and a high back pressure condenser (10).

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