Boiler blowdown water heat energy and water recovery device

Abstract

The utility model relates to a kind of boiler blowdown water heat energy and water recovery device, including fixed discharge expander;Blowdown water heat energy recovery;Water seal, by integrally-formed left and right two part pipes, left side pipeline is connected with the blowoff port of the fixed discharge expander, liquid level meter is further equipped on left side pipeline side surface, and left side pipeline is connected to blowdown water heat energy recovery by pipeline and located in the lower portion of liquid level meter, the sewage outlet of the blowdown water heat energy recovery is communicated to water tank connecting pipeline by sewage booster pump, the inlet of right side pipeline is higher than liquid level meter, and the outlet of right side pipeline is communicated with sewage pool connecting pipe. Through the liquid level meter of water seal side surface, it is ensured that the inner shell side liquid level of blowdown water heat energy recovery is always at safe liquid level, when liquid level meter liquid level is lower than minimum liquid level, alarm, sewage booster pump stops running, ensure the safety of sewage booster pump, when liquid level meter liquid level exceeds maximum liquid level, overflow to sewage pool by water seal, without affecting system safety.

Description

Technical Field

[0001] This utility model relates to the field of boiler heat energy recovery technology, specifically a boiler wastewater heat energy and water recovery device. Background Technology

[0002] To ensure boiler water quality, industrial boilers and power plant boilers are generally equipped with continuous blowdown expansion tanks and periodic blowdown expansion tanks. The continuous blowdown expansion tank primarily receives continuous wastewater. The flash steam from the continuous blowdown expansion tank is connected to the deaerator inlet header. The wastewater from the continuous blowdown expansion tank undergoes secondary flash steaming in the periodic blowdown expansion tank. The flash steam is vented, and the wastewater flows into an underground water tank. After cooling, it is pumped into a circulating water tank or sent to a wastewater treatment plant via a submersible pump. The periodic blowdown expansion tank is the receiver for periodic boiler blowdowns. Periodic blowdowns are performed for short periods with high intensity and are generally operated at atmospheric pressure.

[0003] Boiler wastewater originates from boiler water. Except for a slightly higher salinity, other water quality indicators are excellent, such as turbidity and conductivity, which are superior to raw water. However, according to traditional boiler design specifications, the heat and water resources of boiler wastewater are not well recovered and utilized. In today's context where energy conservation and carbon reduction are national priorities, this design is clearly a huge waste of high-grade thermal energy and water resources.

[0004] In recent years, design institutes, owners, and energy service providers have made many improvements to the recovery of boiler wastewater heat energy. For example, adding a heat exchanger after the fixed discharge expansion tank can recover a portion of the boiler wastewater heat energy to heat demineralized water, thus achieving energy conservation. However, the recycling of boiler wastewater water resources remains relatively crude. Although traditional boiler wastewater is first sprayed with cold water to cool it after flowing into the wastewater tank, and then pumped to the circulating water tank for replenishment by a submersible pump installed in the cooling tank, suspended particles in the air, rainwater, and sewage from the ground will flow into the water tank and pollute the water quality, leading to higher subsequent water treatment costs and additional sewage discharge fees. Depending on the quality of the boiler wastewater, if the subsequent process is not polluted, it can be returned to the industrial water tank for use as industrial water. Therefore, recovering boiler wastewater heat energy has high economic and environmental benefits and is a very important energy conservation and carbon reduction issue.

[0005] Based on this, a boiler wastewater heat energy and water recovery device is proposed to solve the above problems. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this utility model provides a boiler wastewater heat energy and water recovery device. By using a level gauge on the side of the water seal component connected to the wastewater discharge pipe of the fixed discharge expansion vessel, it ensures that the liquid level on the inner shell side of the heat exchanger is always at a safe level, thus enhancing safety.

[0007] To achieve the above objectives, this utility model provides the following technical solution: a boiler wastewater heat energy and water recovery device, comprising:

[0008] The fixed discharge expansion tank discharges continuous wastewater into the tank, where secondary steam (flash steam) is generated as the pressure decreases. It can be used directly as a heating source for low-pressure steam equipment; or it can be recovered locally through a flash steam recovery device for use in applications requiring higher steam pressure.

[0009] Wastewater heat recovery unit can be used to preheat softened water and demineralized water, boiler feedwater, increase the temperature of softened water, supply it to the deaerator, and reduce the steam consumption of the deaerator for heating boiler feedwater; it can also be used to preheat other process liquids, depending on the specific circumstances of the enterprise.

[0010] The water seal consists of two integrally formed pipes, left and right. The left pipe is connected to the sewage outlet of the fixed discharge expansion container via a pipe. A level gauge is also installed on the side of the left pipe. The left pipe, located below the level gauge, is connected to the sewage heat recovery unit via a pipe. The sewage outlet of the sewage heat recovery unit is connected to the water tank connection pipe via a sewage booster pump. The inlet of the right pipe is higher than the level gauge, and the outlet of the right pipe is connected to the sewage tank connection pipe. The level gauge on the side of the water seal ensures that the liquid level on the inner shell side of the sewage heat recovery unit is always at a safe level.

[0011] Furthermore, the cold side (pipe side) of the wastewater heat recovery unit is connected to a demineralized water pipe. The demineralized water at room temperature enters the wastewater heat recovery unit through the demineralized water pipe and is preheated by the waste heat of the wastewater, thereby improving production efficiency.

[0012] Furthermore, the wastewater inlet pipe of the wastewater heat recovery unit is equipped with a heat exchanger inlet valve. When the heat exchange system needs maintenance, closing the heat exchanger inlet valve can shut off the heat exchange system without affecting the operation of the main unit.

[0013] Furthermore, the wastewater inlet pipe of the wastewater heat recovery unit is also equipped with a filter located after the heat exchanger inlet valve. The wastewater entering the wastewater heat recovery unit can be filtered through the filter.

[0014] Furthermore, the lower sides of the left and right sections of the water seal are connected by a pipeline, and a bypass valve is installed on the pipeline. When the heat exchange system is shut down for maintenance, the bypass valve can be opened, and sewage can be directly discharged into the sewage tank through the sewage tank connection pipe.

[0015] Compared with the prior art, the technical solution of this application has the following beneficial effects:

[0016] In operation, the boiler wastewater heat and water recovery device first enters the wastewater heat recovery unit to exchange heat with the ambient temperature demineralized water. The wastewater is then heated by the residual heat to cool it to below 60°C. Finally, it is pumped to an industrial water tank by a wastewater booster pump and mixed with other industrial water for recycling. The device ensures that the liquid level on the inner shell of the wastewater heat recovery unit is always at a safe level by a level gauge on the side of the water seal component connected to the wastewater discharge pipeline of the fixed discharge expansion container. When the liquid level on the level gauge is lower than the minimum level, an alarm is triggered and the wastewater booster pump stops operating to ensure the safety of the wastewater booster pump. When the liquid level on the level gauge exceeds the maximum level, it overflows into the wastewater tank through the water seal component without affecting the system safety.

[0017] Meanwhile, when the heat exchange system needs maintenance, the heat exchange system can be shut off by closing the heat exchanger inlet valve without affecting the operation of the main unit. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of this utility model.

[0019] In the diagram: 1. Fixed discharge expansion container; 2. Water seal; 3. Level gauge; 4. Wastewater heat recovery unit; 5. Demineralized water pipeline; 6. Bypass valve; 7. Wastewater tank connection pipe; 8. Wastewater booster pump; 9. Water tank connection pipe; 10. Heat exchanger inlet valve; 11. Filter. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0021] After boiler blowdown water undergoes depressurization and flash evaporation in the expansion tank, a large amount of saturated water remains at the flash pressure. This water has a saturation temperature of 104°C at 0.02 MPa. Direct discharge would not only result in a significant loss of valuable heat energy but also cause thermal pollution and potential damage to sewage pipes due to the high temperature. Therefore, the heat from the remaining blowdown water should be recovered, reducing its temperature to below 60°C before reuse. The high temperature of the flash-evaporated wastewater is used to heat boiler feedwater or softened water from a chemical water treatment plant via a heat exchanger, simultaneously lowering the wastewater temperature to below 60°C for reuse. This system uses a heat exchanger to cool the remaining wastewater after flash evaporation in the flash tank. The secondary cooling water for the heat exchanger comes from the boiler cold feedwater tank or softened water from the chemical water treatment plant. The heat exchanger should be selected to reduce the temperature to below 60°C even at the boiler's maximum blowdown rate.

[0022] Please see Figure 1 This embodiment of a boiler wastewater heat and water recovery device includes a fixed discharge expansion vessel 1 and a wastewater heat recovery unit 4. Continuous wastewater is discharged into the fixed discharge expansion vessel 1, where secondary steam (flash steam) is generated as the pressure decreases. This secondary steam can be directly used as a heating source for low-pressure steam equipment; alternatively, the flash steam recovery unit can recover all flash steam locally for use in applications requiring higher steam pressure. The continuous boiler wastewater, after passing through the wastewater heat recovery unit 4, can be used to preheat softened water and demineralized water, boiler feedwater, increasing the temperature of the softened water for supply to the deaerator, reducing the steam consumption for heating the boiler feedwater; it can also be used to preheat other process liquids, depending on the specific needs of the enterprise. The wastewater heat recovery unit 4 includes a left tube sheet, shell, heat exchange tubes, spacer tubes, tie rods, baffles, right tube sheet, drain port, support, connecting flange, gaskets, end caps, partition plates, tube box flanges, bolts, nuts, and gaskets. The specific structure and connection relationships are all existing known technologies and will not be detailed here.

[0023] The device also includes a water seal 2, which consists of two integrally formed pipes, left and right. The left pipe is connected to the sewage outlet of the fixed discharge expansion container 1. A level gauge 3 is also provided on the side of the left pipe. The left pipe, located below the level gauge 3, is connected to the wastewater heat recovery unit 4. An opening is made on the left pipe of the water seal 2 near the bottom of the level gauge 3. This opening is connected to the hot side (shell side) of the wastewater heat recovery unit 4 by a welded pipe. The cold side (pipe side) of the wastewater heat recovery unit 4 is connected to a demineralized water pipe 5. The other side of the wastewater heat recovery unit 4 is connected to a makeup water tank. The ambient temperature demineralized water enters the wastewater heat recovery unit 4 through the demineralized water pipe 5 and is preheated by the waste heat of the sewage to improve production efficiency. The wastewater outlet of the wastewater heat recovery unit 4 is connected to the water tank connection pipe 9 via the wastewater booster pump 8. The wastewater after heat exchange can enter the water tank connection pipe 9 through the wastewater booster pump 8 and finally be discharged into the industrial water tank. The inlet of the right pipe is higher than the level gauge 3, and the outlet of the right pipe is connected to the wastewater pool connection pipe 7. When the wastewater level in the level gauge 3 exceeds the maximum level, it overflows into the wastewater pool through the wastewater pool connection pipe 7 at the outlet of the right pipe of the water seal 2, without affecting the safety of the system.

[0024] The function of the water seal 2 is that one end of the water seal 2 is connected to the sewage outlet of the fixed discharge expansion container 1, and the other end of the water seal 2 is connected to the sewage tank through the sewage tank connection pipe 7. Therefore, the liquid level on the inner shell side of the sewage heat recovery unit 4 can be ensured to always be at a safe level through the liquid level gauge 3 on the side of the water seal 2. It should be noted that the hot side shell of the sewage heat recovery unit 4 is connected to the inlet of the sewage booster pump 8, and the outlet of the sewage booster pump 8 is connected to the industrial water tank through the pipeline. In order to save energy, the sewage booster pump 8 adopts a frequency converter and is interlocked with the liquid level gauge 3. The start and stop of the sewage booster pump 8 can be controlled by the liquid level, so that the sewage booster pump 8 can only operate when hot sewage needs to flow into the sewage heat recovery unit 4, and its flow rate is controlled by the frequency converter. Since the pure flash steam is separated in the fixed discharge expansion container 1, the concentration of dissolved solids in the residual sewage after flash evaporation is higher than that in the boiler water, which is very easy to corrode and scale. Therefore, the sewage heat recovery unit 4 should be made of corrosion-resistant materials and be easy to disassemble and maintain. The level gauge 3 can be a magnetic float level gauge, model CZ / UHZ / 500 / C / B / 20 / J. The magnetic float level gauge is equipped with a dedicated level alarm, which can realize remote alarm of upper and lower limit level. It is also equipped with a level signal converter, which can linearly convert the change of level height into a 4-20mA standard DC current signal, so as to realize the remote transmission, centralized display, recording and control of level signal.

[0025] When the liquid level is within the normal range, the sewage booster pump 8 is started, and the sewage heat recovery unit 4 begins to work. When the liquid level in the level gauge 3 is lower than the minimum liquid level, the sewage booster pump 8 can be stopped immediately to ensure the safety of the sewage booster pump 8. The sewage heat recovery unit 4 stops working and issues a warning signal. When the sewage level in the level gauge 3 exceeds the maximum liquid level, a high liquid level alarm signal is issued. If the liquid level continues to rise, the sewage will overflow through the sewage tank connection pipe 7 at the outlet of the water seal 2 and be discharged into the sewage tank and then into the ditch, protecting the main system and this device from damage and ensuring system safety.

[0026] In addition, a heat exchanger inlet valve 10 is installed on the sewage inlet pipe of the sewage heat recovery unit 4. When the heat exchange system needs maintenance, closing the heat exchanger inlet valve 10 will shut off the heat exchange system without affecting the operation of the main unit. Furthermore, a filter 11 is also installed on the sewage inlet pipe of the sewage heat recovery unit 4, located after the heat exchanger inlet valve 10. The sewage entering the sewage heat recovery unit 4 can also be filtered through the filter 11. The lower sides of the left and right sections of the water seal 2 are connected by a pipeline, and a bypass valve 6 is installed on the pipeline. When the heat exchange system is started, the bypass valve 6 is closed. When the heat exchange system is shut down for maintenance, the bypass valve 6 can be opened, and the sewage can be directly discharged into the sewage tank through the sewage tank connection pipe 7.

[0027] It should be noted that the components involved in this embodiment, such as the fixed-discharge expansion tank, heat recovery unit, and booster pump, are all conventional components that can be purchased directly through existing procurement channels. Their internal structure and working principle will not be described in detail here.

[0028] In the above embodiments, after the boiler wastewater enters the depressurization and flash evaporation tank 1, it passes through the level gauge 3 on the side of the water seal 2, and then through the filter 11 to filter the wastewater before finally entering the wastewater heat recovery unit 4. At the same time, ambient temperature demineralized water enters the wastewater heat recovery unit 4 through the demineralized water pipe 5 to exchange heat with the wastewater. The preheated demineralized water is discharged to the makeup water tank, and the wastewater after heat exchange is discharged to the industrial water tank through the wastewater booster pump 8. During the heat exchange process, the level gauge 3 on the side of the water seal 2 can ensure that the liquid level on the inner shell side of the wastewater heat recovery unit 4 is always at a safe level. Furthermore, when the liquid level in the level gauge 3 is lower than the minimum level, an alarm is triggered, and the wastewater booster pump 8 can be stopped immediately to ensure the safety of the wastewater booster pump 8. When the wastewater level in the level gauge 3 exceeds the maximum level, it overflows into the wastewater tank through the wastewater tank connection pipe 7 at the outlet of the water seal 2, without affecting the system safety.

[0029] If the heat exchange system needs maintenance, closing the heat exchanger inlet valve 10 will shut off the heat exchange system without affecting the operation of the main unit. At the same time, sewage will be discharged to the sewage tank through the sewage tank connection pipe 7.

[0030] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0031] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A device for recovering heat energy and water from boiler wastewater, characterized in that, include: Fixed-displacement expansion container (1); Wastewater heat recovery unit (4); The water seal component (2) is composed of two integrally formed pipes, left and right. The left pipe is connected to the sewage outlet of the fixed discharge expansion container (1) through a pipe. A level gauge (3) is also provided on the side of the left pipe. The left pipe is connected to the sewage heat recovery device (4) through a pipe located below the level gauge (3). The sewage outlet of the sewage heat recovery device (4) is connected to the water tank connection pipe (9) through a sewage booster pump (8). The inlet of the right pipe is higher than the level gauge (3). The outlet of the right pipe is connected to the sewage tank connection pipe (7).

2. The boiler wastewater heat energy and water recovery device according to claim 1, characterized in that: The wastewater heat recovery unit (4) is connected to a demineralized water pipe (5) on its cold side.

3. The boiler wastewater heat energy and water recovery device according to claim 1, characterized in that: The wastewater heat recovery unit (4) is equipped with a heat exchanger inlet valve (10) on the wastewater inlet pipe.

4. The boiler wastewater heat energy and water recovery device according to claim 3, characterized in that: The wastewater inlet pipe of the wastewater heat recovery unit (4) is also equipped with a filter (11) located behind the heat exchanger inlet valve (10).

5. The boiler wastewater heat energy and water recovery device according to claim 1, characterized in that: The left and right parts of the water seal (2) are connected by a pipeline, and a bypass valve (6) is installed on the pipeline.

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