Low-energy-consumption evaporative crystallization system for treating salt-containing wastewater of power plant by utilizing heat pump technology

Abstract

The utility model relates to the technical field of wastewater treatment, in particular to a low-energy-consumption evaporative crystallization system for treating salt-containing wastewater of a power plant by utilizing a heat pump technology, which comprises an evaporation tower, a heat exchanger, a condensing tower and a heat pump assembly, the external power plant salt-containing wastewater collecting tank is connected with the evaporation tower, a liquid outlet in the bottom of the evaporation tower is communicated with a first channel inlet of the heat exchanger, a first channel outlet of the heat exchanger is communicated with a backflow liquid inlet in the top of the evaporator, and the heat pump assembly is communicated with a second channel inlet of the heat exchanger. A second channel outlet of the heat exchanger communicates with the heat pump assembly, the heat exchanger provides a cold water source for the heat pump assembly, and the heat pump assembly supplies a generated high-temperature heat source to the heat exchanger; a water vapor outlet in the top of the evaporation tower is communicated with an inlet in the bottom end of the condensation tower. The low-temperature normal-pressure evaporation technology and the heat pump technology are combined, waste heat and waste heat are used for supplementing heat for the low-temperature normal-pressure evaporation technology, and low-energy-consumption operation of power plant salt-containing wastewater treatment is completed.

Description

Technical Field

[0001] This utility model relates to the field of wastewater treatment technology, and in particular to a low-energy evaporation crystallization system for treating saline wastewater from power plants using heat pump technology. Background Technology

[0002] Currently, most landfill leachate treatment uses membrane recycling technology. The concentrated membrane solution (salt, heavy metals, and recalcitrant organic matter) is reinjected into the landfill. Over time, the quality of landfill leachate deteriorates rapidly, and existing processes are overwhelmed and have partially ceased operation (biological and membrane processes).

[0003] Waste-to-energy plants and coal-fired power plants contain large amounts of waste heat that require cooling water (turbines cooling water, generator cooling water, transformer cooling water, etc.) and high-temperature flue gas. Additionally, the concentrated brine from various membrane processes requires treatment. Current practices directly mix this wastewater with pulverized coal or dry waste for incineration, leading to furnace corrosion and high fuel salt content that hinders subsequent fly ash recovery. Existing evaporation processes have a high demand for high-grade heat sources (industrial electricity, live steam), while neglecting low-grade heat sources and failing to explore alternative uses. This results in the complete waste of low-grade heat sources, which generate no value. Furthermore, resources are required to collect and cool these low-grade heat sources to meet production process requirements.

[0004] Therefore, it is crucial to find ways to utilize the aforementioned waste heat sources to optimize the treatment process of saline wastewater from power plants. Utility Model Content

[0005] To address the aforementioned problems, the purpose of this invention is to provide a low-energy evaporation crystallization system that utilizes heat pump technology to treat saline wastewater from power plants.

[0006] The essence of the low-temperature evaporation technology in this invention lies in utilizing the difference in moisture-carrying capacity of air under normal pressure (the saturated vapor pressure of water vapor increases with increasing temperature). At room temperature, the water vapor content in the air is very low, but near the boiling point of water (80°C) and above, the water vapor content can approach 75%–90%. After being heated, the saline wastewater from the power plant is transferred by air from the evaporation tower to the condensation tower for condensation and release of latent heat. Light components continuously decrease in the evaporation tower, while heavy components (salts, organic matter, heavy metals, etc.) accumulate to form concentrated mother liquor, which is ultimately incinerated or crystallized. The sensible heat in the condensation tower is utilized and cooled by a cold source (cooling water, chilled water) for reuse or to meet emission standards.

[0007] The objective of this utility model can be achieved through the following technical solutions:

[0008] This utility model provides a low-energy evaporation crystallization system for treating saline wastewater from power plants using heat pump technology. The system is connected to an external saline wastewater collection tank from the power plant and includes an evaporation tower, a heat exchanger, a condensation tower, and a heat pump assembly.

[0009] The external power plant saline wastewater collection tank is connected to an evaporation tower, which is used to evaporate and concentrate the wastewater, thereby improving the wastewater recycling rate and reducing the wastewater end-of-pipe treatment rate.

[0010] The liquid outlet at the bottom of the evaporation tower is connected to the inlet of the first channel of the heat exchanger to provide a cold water source for the heat exchanger.

[0011] The heat exchanger is used to convert cold water source into hot water source;

[0012] The first channel outlet of the heat exchanger is connected to the reflux liquid inlet at the top of the evaporator, and is used to provide hot water source for the evaporator;

[0013] The heat pump assembly is connected to the second channel inlet of the heat exchanger, and the second channel outlet of the heat exchanger is connected to the heat pump assembly. The heat exchanger is used to provide a cold water source for the heat pump assembly, and the heat pump assembly is used to receive the low-temperature heat source of the heat exchanger and convert it into a high-temperature heat source to power the heat exchanger.

[0014] The water vapor outlet at the top of the evaporator is connected to the inlet at the bottom of the condenser, and the condenser is used to condense the water vapor from the evaporator into recyclable water.

[0015] In this invention, the evaporation tower adopts low-temperature positive pressure evaporation technology.

[0016] In one embodiment of this utility model, the heat pump assembly is connected to an external cooling circulation tower, which provides an external waste heat source for the heat pump assembly and receives the low-temperature refrigerant from the heat pump assembly.

[0017] In one embodiment of this utility model, the heat pump assembly includes an evaporator, a compressor, and a condenser;

[0018] The first channel outlet of the evaporator is connected to the inlet of the compressor, the outlet of the compressor is connected to the first channel inlet of the condenser, and the first channel outlet of the condenser is connected to the first channel inlet of the evaporator and the liquid inlet of the external cooling circulation tower.

[0019] The second channel outlet of the heat exchanger is connected to the first channel inlet of the evaporator, and the gas outlet of the condenser is connected to the second channel inlet of the heat exchanger.

[0020] The gas outlet of the external cooling circulation tower is connected to the gas inlet of the evaporator;

[0021] The evaporator is used to receive the cold water source from the heat exchanger and the waste heat source from the external cooling circulation tower, and absorbs the waste heat source to convert the cold water source into low-temperature and low-pressure gas.

[0022] The compressor is used to convert low-temperature, low-pressure gas into high-temperature, high-pressure gas.

[0023] The condenser is used to convert high-temperature, high-pressure gas into low-temperature refrigerant and release high-temperature heat source; the condenser is connected to the heat exchanger to provide a high-temperature heat source for the heat exchanger and to provide low-temperature refrigerant for the evaporator and external cooling circulation tower.

[0024] In one embodiment of this utility model, the bottom liquid outlet of the condensing tower is connected to the top inlet of the condensing tower through a reflux pipe to improve the condensing effect of the condensing tower.

[0025] In one embodiment of this utility model, the bottom liquid outlet of the condensation tower is connected to an external greywater recycling system via a liquid pipeline.

[0026] In one embodiment of this utility model, a condensate circulating water pump is provided at the bottom liquid outlet of the condensation tower.

[0027] In one embodiment of this utility model, a forced circulation water pump is provided at the bottom liquid outlet of the evaporation tower.

[0028] In one embodiment of this utility model, the evaporation tower is connected to a blower, which is used to provide a stable airflow to the evaporation tower to improve the evaporation efficiency of the evaporation tower.

[0029] In one embodiment of this utility model, a liquid inlet pump is provided at the bottom liquid inlet of the evaporation tower.

[0030] In one embodiment of this utility model, a waste residue discharge valve is provided at the bottom liquid outlet of the evaporation tower.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The system provided by this utility model introduces an evaporation process to complete the final treatment of demineralized water from power plant boilers and membrane concentrate from landfills. It can complete evaporation and concentration under normal pressure until the crystalline salt begins to crystallize, eliminating the continuous water quality deterioration caused by disorderly discharge of demineralized water and reinjection of landfill leachate (membrane concentrate). The wastewater fundamentally removes recalcitrant organic matter, salts, heavy metals, etc. from the system, and the produced water can be directly reused as boiler feedwater or directly used as circulating water to supplement the cooling circulation system. It is very friendly to the stable operation of the wastewater system and also reduces the large amount of heat source waste from concentrated liquid incineration.

[0033] (2) The system provided by this utility model adopts the atmospheric pressure low temperature evaporation process, which is safe and reliable in daily production, has no dangerous control points, and is friendly to safe production and personnel operation; and uses air as a power source to continuously drive the evaporated secondary steam, and the humid air can be repeatedly recycled after condensation.

[0034] (3) The system provided by this utility model is not affected by changes in water quality (salt type, high-boiling organic matter, low-boiling organic matter content) in terms of treatment efficiency and treatment effect. The produced water can be directly reused due to its mild evaporation effect and superior water quality.

[0035] (4) The system provided by this utility model uses a low-temperature evaporation process. Considering the waste heat sources, which are mainly waste steam and turbine cooling water in the process of waste incineration power generation and coal-fired power generation (all of which are relatively low-grade heat sources), the heat pump components convert them into high-temperature heat sources and provide them to the heat exchanger.

[0036] (5) Considering that the optimal operating state of a heat pump has the highest COP value, a large temperature gradient, and a wide energy level range, the required input power is greater and the energy efficiency ratio is lower. Moreover, for evaporator heat exchange, in principle, heat exchange can be carried out as long as the heat source is greater than the set evaporation temperature. However, if the logarithmic temperature difference is small, the heat exchanger area will be larger (the heat exchanger uses precious metals), and the equipment will not be economical.

[0037] (6) The heat pump component in the system provided by this utility model outputs hot water source temperature of 45℃~85℃, which is particularly suitable for low temperature evaporation process. Due to the low temperature evaporation temperature (55~100℃), the complementary characteristics of the heat pump component and the low temperature evaporation process are utilized to use the waste heat and residual heat generated by the power plant for "waste-to-waste" and promote the green and sustainable development of the power plant.

[0038] (7) The heat pump component in the system provided by this utility model refers to a heat pump unit that can recover 20-55°C and provide hot water at 65-95°C, and uses a compressor to continuously extract energy from a low-temperature heat source to supply the condenser.

[0039] In summary, this utility model combines low-temperature atmospheric pressure evaporation technology and heat pump technology, using "waste heat" to supplement the low-temperature atmospheric pressure evaporation technology, thereby achieving low-energy operation of power plant saline wastewater treatment and promoting the green and sustainable development of power plants. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of a low-energy evaporation crystallization system for treating saline wastewater from power plants using heat pump technology, according to this utility model.

[0041] Labels in the diagram: 1. Blower; 2. Power plant saline wastewater collection tank; 3. Evaporator; 4. Forced circulating water pump; 5. Waste residue discharge valve; 6. Heat exchanger; 7. Condensation tower; 8. Condensation circulating water pump; 9. Reclaimed water discharge valve; 10. Evaporator; 11. Compressor; 12. Condenser; 13. Cooling circulation tower; 14. Waste heat source replenishment pump; 15. Liquid inlet pump. Detailed Implementation

[0042] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0043] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0044] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0045] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do 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. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0046] In the following embodiments, unless otherwise specified, the structures or components used are conventional structures or components in the art, as long as they can achieve the corresponding functions.

[0047] Example 1

[0048] This embodiment provides a low-energy evaporation crystallization system for treating saline wastewater from power plants using heat pump technology, such as... Figure 1As shown, the system is connected to an external power plant saline wastewater collection tank 2 and includes an evaporator 3, a heat exchanger 6, a condenser 7, and a heat pump assembly. The external power plant saline wastewater collection tank 2 is connected to the evaporator 3, which is used to evaporate and concentrate the wastewater, improving wastewater recycling rates and reducing wastewater end-of-pipe treatment rates. The liquid outlet at the bottom of the evaporator 3 is connected to the first channel inlet of the heat exchanger 6, providing a cold water source for the heat exchanger 6. The heat exchanger 6 converts the cold water source into a hot water source. The first channel outlet of the heat exchanger 6 is connected to the evaporator 6... The top reflux inlet of the evaporator 10 is connected to provide hot water for the evaporator 10; the heat pump assembly is connected to the second channel inlet of the heat exchanger 6, and the second channel outlet of the heat exchanger 6 is connected to the heat pump assembly. The heat exchanger 6 is used to provide cold water for the heat pump assembly, and the heat pump assembly is used to receive the low-temperature heat source of the heat exchanger 6 and convert it into a high-temperature heat source to power the heat exchanger 6; the water vapor outlet at the top of the evaporator 3 is connected to the bottom inlet of the condenser 7, and the condenser 7 is used to condense the water vapor of the evaporator 3 into reusable water.

[0049] Furthermore, the heat pump assembly is connected to an external cooling circulation tower 13, which provides an external waste heat source for the heat pump assembly and receives the low-temperature refrigerant from the heat pump assembly.

[0050] Furthermore, the heat pump assembly includes an evaporator 10, a compressor 11, and a condenser 12; the first channel outlet of the evaporator 10 is connected to the inlet of the compressor 11, the outlet of the compressor 11 is connected to the first channel inlet of the condenser 12, and the first channel outlet of the condenser 12 is connected to the first channel inlet of the evaporator 10 and the liquid inlet of the external cooling circulation tower 13; the second channel outlet of the heat exchanger 6 is connected to the first channel inlet of the evaporator 10, and the gas outlet of the condenser 12 is connected to the second channel inlet of the heat exchanger 6; the gas outlet of the external cooling circulation tower 13 is connected to the gas outlet of the evaporator 10. The inlet is connected; the evaporator 10 is used to receive the cold water source of the heat exchanger 6 and the waste heat source of the external cooling circulation tower 13, and absorbs the waste heat source to convert the cold water source into low temperature and low pressure gas; the compressor 11 is used to convert the low temperature and low pressure gas into high temperature and high pressure gas; the condenser 12 is used to convert the high temperature and high pressure gas into low temperature refrigerant and release high temperature heat source; the condenser 12 is connected to the heat exchanger 6 through the waste heat source conveying pipeline to provide high temperature heat source for the heat exchanger 6 and low temperature refrigerant for the evaporator 10 and the external cooling circulation tower 13; a waste heat source replenishment pump 14 is installed on the waste heat source conveying pipeline.

[0051] Furthermore, the bottom liquid outlet of the condensing tower 7 is connected to the top inlet of the condensing tower 7 via a reflux pipe to improve the condensing effect of the condensing tower 7.

[0052] A condensate circulating water pump 8 is installed on the return pipe. The return pipe is allowed to be connected to the discharge pipe. A recycled water discharge valve 9 is installed on the discharge pipe.

[0053] Furthermore, the bottom liquid outlet of the evaporator 3 is connected to the first channel inlet of the heat exchanger 6 via a liquid pipeline. A forced circulation water pump 4 is installed on the liquid pipeline. The liquid pipeline is also allowed to be connected to a discharge pipeline, which is equipped with a waste residue discharge valve 5.

[0054] Furthermore, the blower 1 is connected to the evaporation tower 3 via a gas pipeline, and the blower 1 is used to provide a stable airflow to the evaporation tower 3 to improve the evaporation efficiency of the evaporation tower 3.

[0055] Furthermore, the saline wastewater from the power plant is connected to the evaporation tower 3 via an inlet pipe, and an inlet pump 15 is installed on the inlet pipe.

[0056] Example 2

[0057] This embodiment provides a low-energy evaporation crystallization process for treating saline wastewater from power plants using heat pump technology. The low-energy evaporation crystallization system for treating saline wastewater from power plants using heat pump technology from Embodiment 1 includes the following steps:

[0058] The external power plant saline wastewater collection tank 2 transports wastewater to the evaporation tower 3 through the liquid inlet pump 15. The evaporation tower 3 evaporates and concentrates the wastewater, with evaporated water vapor obtained at the top and concentrated wastewater obtained at the bottom (during the operation of the evaporation tower 3, the blower 1 delivers cold air to the evaporation tower 3 through the gas pipeline).

[0059] The evaporated water vapor enters the condenser tower 7 through the top water vapor outlet, and the condenser tower 7 condenses the evaporated water vapor into recyclable water; the circulating water of the condenser tower 7 is returned to the condenser tower 7 through the return pipe for condensation treatment.

[0060] The reclaimable water obtained from the condensation tower is as follows: if the reclaimable water meets the discharge standards, it is discharged directly through the reclaimed water discharge valve 9; if the reclaimable water meets the reuse standards, it enters the greywater reuse system through the reclaimed water discharge valve 9; if the reclaimable water does not meet the discharge standards, it re-enters the wastewater treatment system through the reclaimed water discharge valve 9.

[0061] The concentrated wastewater is transported to the heat exchanger 6 by the forced circulation water pump 4. The heat exchanger 6 heats the concentrated wastewater and then returns the heated concentrated wastewater to the top of the evaporation tower 3.

[0062] A portion of the chilled water in heat exchanger 6 is supplied to evaporator 10. The chilled water circulation tower uses waste heat source supplement pump 14 to supply the generated waste heat source to evaporator 10. Evaporator 10 absorbs external waste heat source and converts chilled water into low-temperature, low-pressure gas, which is then supplied to compressor 11. Compressor 11 compresses the low-temperature, low-pressure gas into high-temperature, high-pressure gas and supplies it to condenser 12. Condenser 12 converts the high-temperature, high-pressure gas into low-temperature refrigerant and releases high-temperature heat source, which is supplied to heat exchanger 6. The low-temperature refrigerant is supplied to evaporator 10 and external cooling circulation tower 13.

[0063] If the concentrated wastewater is concentrated 8 to 10 times to the point of salt saturation, the waste residue discharge valve 5 is opened and the waste residue is discharged.

[0064] The above description of the embodiments is provided to enable those skilled in the art to understand and use the utility model. It will be apparent to those skilled in the art that various modifications can be easily made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present utility model is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the interpretation of the present utility model without departing from its scope should be within the protection scope of the present utility model.

Claims

1. A low-energy evaporation crystallization system for treating saline wastewater from power plants using heat pump technology, connected to an external saline wastewater collection tank (2) of the power plant, characterized in that, It includes an evaporator (3), a heat exchanger (6), a condenser (7), and a heat pump assembly; The external power plant saline wastewater collection tank (2) is connected to the evaporation tower (3), which is used to evaporate and concentrate the wastewater. The liquid outlet at the bottom of the evaporator (3) is connected to the first channel inlet of the heat exchanger (6) to provide a cold water source for the heat exchanger (6); The heat exchanger (6) is used to convert cold water source into hot water source; The first channel outlet of the heat exchanger (6) is connected to the reflux liquid inlet at the top of the evaporator (10) to provide hot water to the evaporator (10); The heat pump assembly is connected to the second channel inlet of the heat exchanger (6), and the second channel outlet of the heat exchanger (6) is connected to the heat pump assembly. The heat exchanger (6) is used to provide cold water source for the heat pump assembly. The heat pump assembly is used to receive the low temperature heat source of the heat exchanger (6) and convert it into a high temperature heat source to provide energy for the heat exchanger (6). The water vapor outlet at the top of the evaporator (3) is connected to the inlet at the bottom of the condenser (7), and the condenser (7) is used to condense the water vapor in the evaporator (3) into recyclable water. The heat pump assembly is connected to an external cooling circulation tower (13), which provides an external waste heat source for the heat pump assembly and receives the low-temperature refrigerant from the heat pump assembly. The heat pump assembly includes an evaporator (10), a compressor (11), and a condenser (12). The first channel outlet of the evaporator (10) is connected to the inlet of the compressor (11), the outlet of the compressor (11) is connected to the first channel inlet of the condenser (12), and the first channel outlet of the condenser (12) is connected to the first channel inlet of the evaporator (10) and the liquid inlet of the external cooling circulation tower (13). The second channel outlet of the heat exchanger (6) is connected to the first channel inlet of the evaporator (10), and the gas outlet of the condenser (12) is connected to the second channel inlet of the heat exchanger (6). The gas outlet of the external cooling circulation tower (13) is connected to the gas inlet of the evaporator (10); The evaporator (10) adopts low-temperature positive pressure evaporation technology; the evaporator (10) is used to receive the cold water source of the heat exchanger (6) and the waste heat source of the external cooling circulation tower (13), and absorb the waste heat source to convert the cold water source into low-temperature and low-pressure gas. The compressor (11) is used to convert low-temperature, low-pressure gas into high-temperature, high-pressure gas; The condenser (12) is used to convert high-temperature and high-pressure gas into low-temperature refrigerant and release high-temperature heat source; the condenser (12) is connected to the heat exchanger (6) to provide high-temperature heat source for the heat exchanger (6) and to provide low-temperature refrigerant for the evaporator (10) and the external cooling circulation tower (13); The evaporator (3) is connected to the blower (1) through a gas delivery pipeline. The blower (1) is used to provide a stable airflow to the evaporator (3) to improve the evaporation efficiency of the evaporator (3).

2. The low-energy evaporation crystallization system for treating saline wastewater from power plants using heat pump technology according to claim 1, characterized in that, The bottom liquid outlet of the condenser (7) is connected to the top reflux liquid inlet of the condenser (7) or an external greywater recycling system.

3. The low-energy evaporation crystallization system for treating saline wastewater from power plants using heat pump technology according to claim 1, characterized in that, The bottom liquid outlet of the condenser (7) is connected to an external greywater recycling system.

4. A low-energy evaporation crystallization system for treating saline wastewater from power plants using heat pump technology according to claim 1, characterized in that, A condensate circulating water pump (8) is installed at the bottom liquid outlet of the condenser (7).

5. A low-energy evaporation crystallization system for treating saline wastewater from power plants using heat pump technology according to claim 1, characterized in that, The bottom liquid outlet of the evaporator (3) is equipped with a forced circulation water pump (4) and a waste residue discharge valve (5).

6. A low-energy evaporation crystallization system for treating saline wastewater from power plants using heat pump technology according to claim 1, characterized in that, The system is equipped with a blower (1), which is connected to the evaporation tower (3).

7. A low-energy evaporation crystallization system for treating saline wastewater from power plants using heat pump technology according to claim 1, characterized in that, The evaporator (3) is equipped with a liquid inlet pump (15) at the bottom liquid inlet.

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