System for recycling boiler start-stop steam for heating demineralized water

Abstract

The utility model provides a system for recovering boiler start-stop steam for heating demineralized water, which comprises a boiler, a steam decompression tank and a demineralized water tank, the boiler is communicated with the steam decompression tank through a blow-off valve, the steam decompression tank is connected with a steam bubbling distributor mounted at the bottom of the demineralized water tank, and an outlet of the demineralized water tank is communicated with the boiler. In the starting and stopping process of the boiler, unqualified steam generated by the boiler is treated by the steam decompression tank and then enters the demineralized water tank, and cold demineralized water in the oxygen outlet water tank is bubbled and heated through the steam; the dissolved oxygen content in the heated demineralized water is lower than that in the cold demineralized water, so that the service life of the boiler can be prolonged, the heated hot demineralized water enters the boiler, the time for the boiler to heat the demineralized water to the specified temperature is shortened, the heating efficiency of the boiler can be improved, and the energy consumption is reduced. And in addition, desalted water of unqualified steam generated in the starting and stopping process of the boiler can be recycled, and the cost is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of boilers, in particular to a system for recovering boiler start-stop steam for heating desalted water. Background Art

[0002] The boiler is a device that heats desalted water into steam. In the steam-water circulation process of becoming desalted water, in the operation of the existing boiler system, the cold desalted water is basically discharged from the desalted water tank after being processed, and the cold desalted water enters the boiler for heating. Since the cold desalted water contains a large amount of dissolved oxygen, too high dissolved oxygen will cause oxygen corrosion of the boiler tube bundle and reduce the life of the boiler. In order to extend the life of the boiler, it is necessary to add deoxygenation equipment to deoxygenate the cold desalted water. During the start-up and shutdown process of the boiler, since the internal temperature gradually increases or decreases, for normal use, it is unqualified steam and is directly discharged into the air as exhaust gas, which will cause noise pollution and waste of heat energy. Utility Model Content

[0003] In view of the shortcomings of the prior art mentioned above, the purpose of the utility model is to provide a system for recovering boiler start-up and shutdown steam for heating desalted water, so as to solve the problems in the prior art of directly adding cold desalted water into the boiler, resulting in a shortened boiler life; if a separate deoxygenation device is used to deoxygenate the cold desalted water, the steam during the start-up and shutdown process of the boiler is directly discharged into the air, resulting in a waste of energy.

[0004] To achieve the above-mentioned purpose and other related purposes, the utility model provides a system for recovering boiler start-stop steam for heating desalted water, comprising a boiler, a steam pressure reducing tank, and a desalted water tank, wherein the boiler is connected to the steam pressure reducing tank via a vent valve, the steam pressure reducing tank is connected to a steam bubbling distributor installed at the bottom of the desalted water tank, and the outlet of the desalted water tank is connected to the boiler.

[0005] Furthermore, a first main pipe is provided between the relief valve and the steam pressure reducing tank for accommodating the relief steam during the start-up and shutdown of the boiler, and the steam pressure reducing tank is connected to the first main pipe.

[0006] Furthermore, a first safety valve is installed on the first main pipe, and a first pressure gauge is installed between the first safety valve and the first main pipe.

[0007] Furthermore, a second safety valve is installed on the steam pressure reducing tank to reduce the pressure of the steam pressure reducing tank.

[0008] Furthermore, a second pressure gauge is provided between the steam pressure reducing tank and the desalted water tank for monitoring the pressure at the outlet of the steam pressure reducing tank.

[0009] Furthermore, a first thermometer is installed at the inlet of the desalted water tank to monitor the temperature of the cold desalted water entering the desalted water tank, and a second thermometer is installed at the outlet of the desalted water tank to monitor the temperature of the hot desalted water flowing out of the desalted water tank.

[0010] Furthermore, a second main pipe is provided between the desalted water tank and the boiler, and the desalted water tank and the boiler are both connected to the second main pipe.

[0011] As described above, the utility model has the following beneficial effects: during the start and stop process of the boiler, the unqualified steam generated by the boiler is processed by a steam pressure reducing tank and then enters into a desalted water tank, and the cold desalted water in the oxygen outlet water tank is bubbled and heated by steam. The dissolved oxygen content in the heated desalted water is lower than that in the cold desalted water, which can extend the service life of the boiler, and the heated hot desalted water enters into the boiler, which reduces the time it takes for the boiler to heat it to a specified temperature, which can improve the heating efficiency of the boiler, and the desalted water of the unqualified steam generated by the boiler during the start and stop process can also be recovered to reduce costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A schematic diagram of the structure of a system for heating desalted water with start-stop steam from a recovery boiler provided in this application.

[0013] Part Number Description

[0014] Boiler, 2-steam pressure reducing tank, 3-desalting water tank, 4-releasing valve, 5-steam bubbling distributor, 6-first mother pipe, 7-first safety valve, 8-first pressure gauge, 9-second safety valve, 10-second pressure gauge, 11-first thermometer, 12-second thermometer. DETAILED DESCRIPTION

[0015] The following is an explanation of the implementation of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0016] It should be noted that the diagrams provided in the present embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, so the diagrams only show the components related to the present invention rather than the number, shape and size of the components in the actual implementation. The type, quantity and proportion of each component in the actual implementation can be changed at will, and the layout of the components may be more complicated. The structure, proportion, size, etc. shown in the diagrams attached to this specification are only used to match the content disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions that the present invention can be implemented, so they have no technical substantive significance. Any modification of the structure, change of the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effect and purpose that the present invention can produce. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" cited in this specification are only for the convenience of description and are not used to limit the scope of the implementation of the present utility model. Changes or adjustments to their relative relationships should be regarded as the scope of the implementation of the present utility model without substantially changing the technical content.

[0017] On the one hand, if Figure 1 As shown, the present application provides a system for recovering boiler start-stop steam for heating desalted water, including a boiler 1, a steam pressure reducing tank 2, and a desalted water tank 3. The boiler 1 is connected to the steam pressure reducing tank 2 through a vent valve 4, the steam pressure reducing tank 2 is connected to a steam bubbling distributor 5 installed at the bottom of the desalted water tank 3, and the outlet of the desalted water tank 3 is connected to the boiler 1.

[0018] In this embodiment, three boilers 1 are provided, but in actual use, there may be more than one. If steam recovery is required for two or more boilers 1 during the start-up and shutdown process, a first mother pipe 6 is provided between the boiler 1 and the steam pressure reducing tank 2. The first mother pipe 6 is used to accommodate the released steam during the start-up and shutdown process of the boiler 1. The release valve 4 of each boiler 1 is connected to the first mother pipe 6, and the air inlet of the steam pressure reducing tank 2 is connected to the first mother pipe 6, so that the steam of each boiler 1 is collected in the first mother pipe 6.

[0019] Since the steam from multiple boilers 1 is collected in the first mother pipe 6, in order to prevent the air pressure in the first mother pipe 6 from being too high, a first safety valve 7 is installed on the first mother pipe 6, and a first pressure gauge 8 is installed between the first safety valve 7 and the first mother pipe 6. By detecting the value of the first pressure gauge 8, when it is greater than the preset second preset pressure, the first safety valve 7 is opened to discharge the steam in the first mother pipe 6 to the outside to ensure the safety of the entire system. The second preset pressure is the pressure that the first mother pipe 6 can withstand. After multiple tests in the actual process, the second preset pressure is generally 6Mpa, that is, when the value detected by the first pressure gauge 8 is greater than 6Mpa, the first safety valve 7 is opened.

[0020] The steam pressure reducing tank 2 gathers and reduces the pressure of the steam from each boiler 1 and then enters the desalted water tank 3. In order to prevent the pressure in the steam pressure reducing tank 2 from being too high, a second safety valve 9 is installed on the steam pressure reducing tank 2 to reduce the pressure of the steam pressure reducing tank 2. A second pressure gauge 10 is provided between the steam pressure reducing tank 2 and the desalted water tank 3 to monitor the pressure at the outlet of the steam pressure reducing tank 2. The steam pressure reducing tank 2 is equipped with a pressure gauge for monitoring its internal pressure. When the pressure of the steam pressure reducing tank 2 is greater than the preset first preset pressure, the first safety valve 7 is opened. The first preset pressure is the safety pressure of the steam pressure reducing tank 2. The first preset pressure in this embodiment is 2Mpa, that is, when the value detected by the pressure gauge in the steam pressure reducing tank 2 is greater than 2Mpa, the second safety valve 9 is opened.

[0021] The inlet of the desalted water tank 3 is respectively equipped with a first thermometer 11 for monitoring the temperature of the cold desalted water entering the desalted water tank 3, and the outlet of the desalted water tank 3 is equipped with a second thermometer 12 for monitoring the temperature of the hot desalted water flowing out of the desalted water tank 3. By monitoring the values ​​of the first thermometer 11 and the second thermometer 12, the steam pressure entering the steam pressure reducing tank 2 and entering the desalted water tank 3 is adjusted. Generally, the temperature of the hot desalted water is within the range of 30-100°C, and the dissolved oxygen content is relatively low. Therefore, by adjusting the steam pressure at the outlet of the steam pressure reducing tank 2, the temperature of the water discharged from the desalted water tank 3 is within the range of 30-100°C. If the temperature is higher than 100°C, it is water vapor that enters the boiler 1, and the desalted water entering the boiler 1 is reduced.

[0022] Since it is aimed at multiple boilers 1, a second main pipe is provided between the desalted water tank 3 and the boiler 1, and the desalted water tank 3 and the boiler 1 are both connected to the second main pipe.

[0023] On the other hand, the present application provides a method for recovering boiler start-stop steam for heating desalted water, using the above system, including the following steps:

[0024] S1. The diffuser valve 4 of boiler 1 is opened during the start-up and shutdown process; the diffuser valve 4 is opened during the start-up and shutdown process of boiler 1, so that the unqualified steam in each boiler 1 enters the first main pipe 6 for collection and then enters the steam pressure reducing tank 2 for pressure reduction treatment, and then enters the desalted water tank 3 to heat the cold desalted water.

[0025] S2, detecting the temperature of the second thermometer 12 at the outlet of the desalted water tank 3, and adjusting the temperature of the water entering the boiler 1 according to the temperature of the second thermometer 12.

[0026] If the temperature of the second thermometer 12 is lower than the preset temperature, the pressure of the steam entering the desalted water tank 3 from the steam decompression tank 2 is increased. If the temperature of the second thermometer 12 is higher than the preset temperature, the pressure of the steam entering the desalted water tank 3 from the steam decompression tank 2 is reduced.

[0027] The dissolved oxygen content of hot desalted water is low when the temperature is between 30-100°C, so the preset temperature is 30-100°C. When the water temperature detected by the second thermometer 12 is less than 30°C, the pressure at the outlet of the steam pressure reducing valve is increased, so that the water vapor entering the desalted water tank 3 increases. When the water temperature detected by the second thermometer 12 is greater than 100°C, the pressure at the outlet of the steam pressure reducing valve is reduced, so that the water vapor entering the desalted water tank 3 decreases.

[0028] S3, monitor and adjust the pressure of the steam pressure reducing tank 2 and the pressure of the first main pipe 6; when the pressure in the steam pressure reducing tank 2 is greater than the first preset pressure, open the second safety valve 9 on the steam pressure reducing tank 2 to release the steam pressure reducing tank 2. When the value detected by the first pressure gauge 8 monitoring the pressure of the first main pipe 6 is greater than the second preset pressure, open the first safety valve 7 on the first main pipe 6 to release the first main pipe 6. The first safety valve 7 and the second safety valve 9 are both automatic valves. When the steam in the boiler 1 is qualified, the relief valve 4 is closed.

[0029] During the startup process of boiler 1, the furnace temperature needs to be gradually increased, and the temperature and pressure of the desalted water in boiler 1 need to be increased to meet the quality requirements for steam connection. It is a long and slow process from the startup of boiler 1 to the new steam being connected to the steam main pipe. Generally, boiler 1 takes 2-3 hours, and the evaporation capacity of boiler 1 is maintained at 5-20t / h. Except for a very small part used for heating pipes or draining, unqualified steam will be directly discharged into the air as waste steam during the startup process, causing noise pollution and waste of heat energy. During the shutdown process of boiler 1, steam is generally discharged into the air during the pressure relief operation without being used, which also causes the same waste of heat energy and working fluid to a certain extent.

[0030] The present application sets a first mother pipe 6 for starting and stopping steam recovery. The recovered steam enters the steam pressure reducing tank 2. After expansion and pressure reduction, it enters the bubbling distributor arranged at the bottom of the desalted water tank 3 to heat the cold desalted water. At the same time, the steam condenses into water after cooling down. When the boiler 1 is started and stopped, the vent valve 4 is no longer opened to release the steam to the air, so as to achieve the effect of recovering heat and water. When the steam of the boiler 1 is qualified, the cold desalted water in the desalted water tank 3 is deoxygenated by the deoxygenation equipment, which also saves energy. For example, if the start and stop times are calculated to be 24 times a year and the two boilers 1 are started and stopped once a month, 50 tons of low-pressure steam will be recovered each time the start and stop is performed. The benefit of recovering the desalted water working fluid is achieved. The price of secondary desalted water is calculated at 7 yuan / ton, so the annual benefit of recovering desalted water is 50*24*7=8,400 yuan; the benefit of increased power generation from recovered steam is calculated at a price of 0.7 yuan / kWh and low-pressure steam supplementary power generation is 160kWh / t, so the annual benefit of recovering steam for power generation is 50*160*24*0.7=134,400 yuan.

[0031] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed in the present invention shall still be covered by the claims of the present invention.

Claims

1. A system for recovering boiler start-stop steam to heat desalted water, characterized in that: The invention comprises a boiler (1), a steam pressure reducing tank (2), and a desalted water tank (3); the boiler (1) is connected to the steam pressure reducing tank (2) via a relief valve (4); the steam pressure reducing tank (2) is connected to a steam bubbling distributor (5) installed at the bottom of the desalted water tank (3); and the outlet of the desalted water tank (3) is connected to the boiler (1).

2. The system for heating desalted water by starting and stopping steam from a recovery boiler according to claim 1, characterized in that: A first main pipe (6) is provided between the relief valve (4) and the steam pressure reducing tank (2) for accommodating the relief steam during the start-up and shutdown process of the boiler (1); the steam pressure reducing tank (2) is in communication with the first main pipe (6).

3. The system for heating desalted water by starting and stopping steam from a recovery boiler according to claim 2, characterized in that: A first safety valve (7) is installed on the first main pipe (6), and a first pressure gauge (8) is installed between the first safety valve (7) and the first main pipe (6).

4. The system for heating desalted water by starting and stopping steam from a recovery boiler according to claim 1, 2 or 3, characterized in that: The steam pressure reducing tank (2) is provided with a second safety valve (9) for reducing the pressure of the steam pressure reducing tank (2).

5. The system for heating desalted water by starting and stopping steam from a recovery boiler according to claim 1, characterized in that: A second pressure gauge (10) is provided between the steam pressure reducing tank (2) and the desalted water tank (3) for monitoring the pressure at the outlet of the steam pressure reducing tank (2).

6. The system for heating desalted water by starting and stopping steam from a recovery boiler according to claim 1, characterized in that: A first thermometer (11) is installed at the inlet of the desalted water tank (3) for monitoring the temperature of the cold desalted water entering the desalted water tank (3), and a second thermometer (12) is installed at the outlet of the desalted water tank (3) for monitoring the temperature of the hot desalted water flowing out of the desalted water tank (3).

7. The system for starting and stopping steam from a recovery boiler (1) to heat desalted water according to claim 1 or 6, characterized in that: A second main pipe is provided between the desalted water tank (3) and the boiler (1), and the desalted water tank (3) and the boiler (1) are both connected to the second main pipe.

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