A heat-pump-based autothermal cycle evaporation apparatus and a heat-pump-based autothermal cycle evaporation method
By using a heat pump self-heating circulation evaporator to generate high-potential steam as a heating source through multi-effect steam energy, the problems of high cost of MVR process and high energy consumption of multi-effect evaporator are solved, achieving the effect of high energy efficiency and low investment cost.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SINOPEC ENERGY SAVING TECH SERVICE CO LTD
- Filing Date
- 2026-03-24
- Publication Date
- 2026-06-12
AI Technical Summary
In existing evaporation processes, MVR (Multi-Effect Vapor Reduction) equipment is complex and costly, while multi-effect evaporators consume a lot of energy and require a large amount of condensate, making it difficult to efficiently utilize thermal energy.
A heat pump-based self-heating circulation evaporator is adopted, which uses the energy of multi-effect steam to generate high-potential steam as a heating source, reducing the consumption of external steam, and realizing energy recovery through the process of converting electrical energy into heat energy.
It significantly reduces the energy consumption of evaporators, reduces external steam consumption, achieves efficient energy utilization and low investment costs, and has promotional value.
Smart Images
Figure CN122183184A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of environmental protection technology, specifically relating to a heat pump-based self-heating circulating evaporation device and a heat pump-based self-heating circulating evaporation method. Background Technology
[0002] Evaporation concentration and evaporation crystallization are important technologies for the separation and purification of substances. They can effectively separate solutes from solutions and have the advantages of simple operation, low energy consumption, and wide applicability. They are widely used in industrial and environmental protection fields for solvent recovery and wastewater treatment.
[0003] Currently, the evaporation processes widely used in industry are mainly divided into two categories: multi-effect evaporation (such as triple-effect evaporation) and mechanical vapor recompression evaporation (MVR process).
[0004] The MVR process uses electricity to drive a compressor to perform work on secondary steam, increasing its enthalpy and then recovering all of it as a system heat source. Theoretically, it only requires a small amount of energy to compensate for system heat loss and material heating, resulting in extremely high thermal efficiency. However, the core equipment of the MVR process—the steam compressor—is technically complex and expensive, with extremely high requirements for equipment materials, control, and maintenance, leading to exceptionally high initial investment costs. Furthermore, it faces challenges when processing materials prone to scaling, with high boiling point rises, or containing non-condensable gases.
[0005] Compared to MVR (Multi-Effect Vapor Reduction) technology, multi-effect evaporation is a traditional and mature technology. By connecting multiple evaporators in series, the secondary steam generated in the first effect is used as the heat source for the subsequent effect, achieving cascaded utilization of thermal energy and thus improving thermal efficiency. It has certain advantages in terms of reliability and lower investment threshold. However, since there is no steam compressor to perform work on the steam, a continuous supply of fresh steam is required from the outside, resulting in energy consumption far exceeding that of MVR technology. It also requires a large amount of condensate, further increasing investment. Summary of the Invention
[0006] To address the aforementioned problems in existing technologies, the present invention aims to provide a heat pump-based self-heating circulating evaporation device and a heat pump-based self-heating circulating evaporation method. Through a heat pump energy-saving device, the energy of its own generated secondary steam is used to produce steam with higher potential energy. This steam with increased potential energy enters the evaporation system as a heating source and is recycled, replacing the vast majority of fresh steam. External steam is only used to compensate for heat loss and to supplement the enthalpy required for the inlet and outlet temperatures, thereby significantly reducing the consumption of live steam in the evaporator. Energy saving is achieved through the process of converting electrical energy into heat energy.
[0007] To achieve the above objectives, a first aspect of the present invention provides a self-heating circulating evaporation device based on a heat pump, comprising a multi-effect evaporation unit and a heat pump unit; the heat pump unit comprises a heat pump evaporator, a compressor, an integrated steam generator, and a throttling valve that are connected in series via heat exchange working fluid pipes to form a heat exchange loop; The heat pump evaporator is provided with a heat pump evaporator steam inlet and a heat pump evaporator condensate outlet; the integrated steam generator is provided with a fresh water inlet and a fresh steam outlet. The multi-effect evaporation unit is provided with a material feed end, a material discharge end, a steam feed end, a steam discharge end, and a multi-effect evaporator connected in sequence along the steam flow direction; the steam discharge end of the multi-effect evaporation unit is connected to the steam inlet of the heat pump evaporator, and the fresh steam outlet is connected to the steam feed end of the multi-effect evaporation unit.
[0008] A second aspect of the present invention provides a self-heating cycle evaporation method based on a heat pump, which employs the aforementioned self-heating cycle evaporation device based on a heat pump, and includes the following steps: (1) The material to be concentrated enters the multi-effect evaporator from the material feed end of the multi-effect evaporator unit for concentration, and external steam enters the multi-effect evaporator from the steam feed end of the multi-effect evaporator unit to provide heat; (2) The exhaust gas from the steam outlet of the multi-effect evaporation unit enters the heat pump evaporator to recover energy and provide heat for the heat exchange medium. After condensing into liquid, it is discharged. The gaseous heat exchange medium evaporated by the heat pump evaporator is pressurized by the compressor and enters the integrated steam generator to condense and provide energy for fresh water. The condensed liquid heat exchange medium is depressurized by the throttling valve and returns to the heat pump evaporator. (3) The fresh water is heated to produce fresh steam, which enters the multi-effect evaporator to provide energy, and external steam is stopped or reduced.
[0009] The beneficial effects of this invention are: 1) The device and method of the present invention utilize the energy of multi-effect steam to convert it into a single-effect heating heat source, thereby saving energy. The method is simple to implement, has low investment costs, and has significant energy-saving effects, making it worthy of promotion.
[0010] 2) The apparatus and method of the present invention achieve energy recovery and reuse by converting electrical energy into heat energy, thereby achieving energy conservation.
[0011] 3) The device and method of the present invention only require a portion of external fresh steam as a start-up heat source when the machine is turned on, and then consume a portion of electrical energy and recover all of its own heat, so as to achieve the effect of not consuming (or reducing consumption) external steam heat source.
[0012] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description
[0013] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the invention.
[0014] Figure 1 A schematic diagram of the evaporation device of the present invention utilizing a heat pump self-heating cycle is shown.
[0015] Figure 2 The diagram illustrates the operating principle of the evaporation device utilizing a heat pump self-heating cycle according to the present invention.
[0016] Explanation of reference numerals in the attached figures: 1-Single-effect evaporator; 2-Double-effect evaporator; 3-Triple-effect evaporator; 4-Condenser; 5-Vacuum pump; 6-Compressor; 7-Heat pump evaporator; 8-Integrated steam generator; 9-Throttle valve; 10-External steam; 11-Single-effect steam; 12-Double-effect steam; 13-Triple-effect steam; 14-Condensate; 15-Fresh water; 16-Fresh steam; 18-Material; 19-Single-effect concentrate; 20-Double-effect concentrate; 21-Triple-effect concentrate; 22-Gaseous working fluid; 23-Liquid working fluid; 24-Cooling water inlet; 25-Cooling water outlet. Detailed Implementation
[0017] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.
[0018] A first aspect of the present invention provides a self-heating circulating evaporation device based on a heat pump, comprising a multi-effect evaporation unit and a heat pump unit; the heat pump unit comprises a heat pump evaporator, a compressor, an integrated steam generator and a throttling valve connected in series in a heat exchange circuit via heat exchange working fluid pipes; The heat pump evaporator is provided with a heat pump evaporator steam inlet and a heat pump evaporator condensate outlet; the integrated steam generator is provided with a fresh water inlet and a fresh steam outlet. The multi-effect evaporation unit is provided with a material feed end, a material discharge end, a steam feed end, a steam discharge end, and a multi-effect evaporator connected in sequence along the steam flow direction; the steam discharge end of the multi-effect evaporation unit is connected to the steam inlet of the heat pump evaporator, and the fresh steam outlet is connected to the steam feed end of the multi-effect evaporation unit.
[0019] According to the present invention, preferably, the heat exchanger of the heat pump evaporator is made of stainless steel and is covered with 80-110mm of rock wool as an insulation layer.
[0020] According to the present invention, preferably, the multi-effect evaporation unit includes three to six effect evaporators connected sequentially along the steam flow direction, preferably a three-effect evaporator.
[0021] According to the present invention, preferably, each evaporator of the multi-effect evaporation unit is provided with a feed inlet and a discharge outlet; The outlet of the previous-effect evaporator along the steam flow direction is connected to the inlet of its adjacent evaporator via a pipe.
[0022] According to the present invention, preferably, each evaporator of the multi-effect evaporation unit is provided with a steam inlet and a steam outlet at its bottom and top, respectively; In addition to the steam outlet of the last effect evaporator, the steam outlet of the previous effect evaporator along the steam flow direction is connected to the steam inlet of the next adjacent effect evaporator via a pipe.
[0023] According to the present invention, preferably, each effect evaporator is provided with a vacuum port, and the vacuum port is connected to a vacuum pump; The multi-effect evaporation unit also includes a condenser and an optional preheater. The steam outlet pipe of the last effect evaporator is divided into two paths, one of which is connected to the steam inlet of the heat pump evaporator, and the other is connected to the condenser.
[0024] A second aspect of the present invention provides a self-heating cycle evaporation method based on a heat pump, which employs the aforementioned self-heating cycle evaporation device based on a heat pump, and includes the following steps: (1) The material to be concentrated enters the multi-effect evaporator from the material feed end of the multi-effect evaporator unit for concentration, and external steam enters the multi-effect evaporator from the steam feed end of the multi-effect evaporator unit to provide heat; (2) The exhaust gas from the steam outlet of the multi-effect evaporation unit enters the heat pump evaporator to recover energy and provide heat for the heat exchange medium. After condensing into liquid, it is discharged. The gaseous heat exchange medium evaporated by the heat pump evaporator is pressurized by the compressor and enters the integrated steam generator to condense and provide energy for fresh water. The condensed liquid heat exchange medium is depressurized by the throttling valve and returns to the heat pump evaporator. (3) The fresh water is heated to produce fresh steam, which enters the multi-effect evaporator to provide energy, and external steam is stopped or reduced.
[0025] According to the present invention, preferably, the multi-effect evaporation unit includes a triple-effect evaporator connected in sequence along the steam flow direction, wherein the temperature of the external steam is 140-160°C and the pressure is 0.3-0.5 MPaG; The conditions for a single-effect evaporator include: a temperature of 80-100℃ and a pressure of 0.06-0.08 MPa.a. The conditions for a double-effect evaporator include: a temperature of 70-90℃ and a pressure of 0.046-0.048 MPa.a. The conditions for a triple-effect evaporator include: a temperature of 60-80℃ and a pressure of 0.030-0.032 MPa.a.
[0026] According to the present invention, preferably, the steam temperature at the steam outlet of the triple-effect evaporator is 50-90°C, and it is divided into two parts, one part of which enters the heat pump evaporator and the other part enters the condenser for condensation; the volume ratio of the steam entering the heat pump evaporator and the condenser is 80~90:10~20.
[0027] According to the present invention, preferably, the heat pump evaporator evaporates a gaseous heat exchange medium at 60-70°C, which is then pressurized and enters an integrated steam generator. The heat exchange medium changes from a gaseous state to a liquid state, and the released heat heats the fresh water to produce fresh steam at 80-130°C.
[0028] According to the present invention, the preferred application industries are: wastewater desalination, lithium ore purification, pharmaceutical intermediate mother liquor concentration, alumina multi-effect evaporation, monosodium glutamate (MSG) process concentration, etc.
[0029] Example 1
[0030] The device used in this embodiment is shown in Figure 1, including a triple-effect evaporation unit and a heat pump unit. The heat pump unit includes a heat pump evaporator 7, a compressor 6, an integrated steam generator 8, and a throttling valve 9, which are connected in series through heat exchange medium pipes to form a heat exchange loop. The heat exchanger of the heat pump evaporator 7 is made of stainless steel and is covered with 80-110mm of rock wool as an insulation layer. The heat pump evaporator 7 is provided with a heat pump evaporator steam inlet and a heat pump evaporator condensate outlet. The integrated steam generator is provided with a fresh water inlet and a fresh steam outlet. The triple-effect evaporation unit is provided with triple-effect evaporators connected in sequence along the steam flow direction. Each evaporator in the multi-effect evaporation unit is provided with a feed inlet and a discharge outlet in the upper middle and lower middle parts, respectively. The discharge outlet of the previous evaporator along the steam flow direction is connected to the feed inlet of its adjacent evaporator through a pipe. Each evaporator in the multi-effect evaporation unit has a steam inlet and a steam outlet at its bottom and top, respectively. The steam outlet of the previous evaporator along the steam flow direction is connected to the steam inlet of the next adjacent evaporator through a pipe. Except for the steam outlet of the last evaporator, which is connected to the steam inlet of the heat pump evaporator, the fresh steam outlet is connected to the steam feed end of the multi-effect evaporation unit.
[0031] Vacuum pump 5 maintains a pressure of 0.07 MPa·a for the first-effect evaporator, 0.047 MPa·a for the second-effect evaporator, and 0.031 MPa·a for the third-effect evaporator, corresponding to evaporation temperatures of 90℃, 80℃, and 70℃, respectively. External liquid first passes through a preheater (if present) to reach the required pressure and temperature before entering the first-effect evaporator. External 0.4 MPaG (152℃) fresh steam acts as a heat source for the first-effect evaporator, heating the waste liquid and causing it to evaporate at 0.07 MPa·a to produce 90℃ first-effect steam, achieving primary concentration of the waste liquid. The first-effect steam then serves as a heat source for the second-effect evaporator. The first-effect concentrate enters the second-effect evaporator and is heated by the first-effect steam, causing it to evaporate at 0.047 MPa·a to produce 80℃ second-effect steam, further concentrating the first-effect concentrate into a second-effect concentrate. The steam from the double-effect evaporator then serves as a heat source for the triple-effect evaporator. The double-effect concentrate in the double-effect evaporator enters the triple-effect evaporator and is heated by the double-effect steam, causing the double-effect concentrate to evaporate at a pressure of 0.031 MPa to produce triple-effect steam at 70°C. This further concentrates the double-effect concentrate into concentrated waste liquid, which then enters the subsequent processes.
[0032] The 70°C exhaust steam from the triple-effect evaporator cannot be fully recovered due to heat introduced by the compressor. Approximately 20% enters the condenser, where it loses heat through heat exchange with external cooling water. The remaining 80% enters the heat pump evaporator, where the exhaust steam exchanges heat with the working fluid, evaporating into a 65°C gaseous working fluid. This gaseous fluid is then compressed by the compressor and enters the integrated steam generator. In the integrated steam generator, the working fluid changes from a gaseous state to a liquid state, releasing heat to heat the external makeup water and generate 105°C steam. The high-pressure liquid working fluid is then depressurized by a throttling valve, becoming a low-pressure liquid working fluid, which enters the evaporator for evaporation, simultaneously recovering the heat from the triple-effect steam entering the evaporator. The 105°C fresh steam generated by the integrated steam generator is integrated into the heat source network of the single-effect evaporator, serving as its heat source. Simultaneously, the original 0.4MPaG fresh steam supply is shut down, achieving waste heat recovery and reducing the need for external high-grade energy. In a conventional system, the heat lost by the cooling water in the condenser is absorbed by the heat pump and converted into usable high-pressure, high-temperature fresh steam. This fresh steam is reused as an external heat source for the first-effect evaporator, allowing the heat from the third-effect steam to be transferred to the first-effect evaporator, thus achieving energy saving and consumption reduction, and saving a large amount of condensate.
[0033] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.
Claims
1. A self-heating circulating evaporator based on a heat pump, characterized in that, It includes a multi-effect evaporation unit and a heat pump unit; the heat pump unit includes a heat pump evaporator, a compressor, an integrated steam generator and a throttling valve connected in series to form a heat exchange loop through heat exchange working fluid pipes; The heat pump evaporator is provided with a heat pump evaporator steam inlet and a heat pump evaporator condensate outlet; the integrated steam generator is provided with a fresh water inlet and a fresh steam outlet. The multi-effect evaporation unit is provided with a material feed end, a material discharge end, a steam feed end, a steam discharge end, and a multi-effect evaporator connected in sequence along the steam flow direction; the steam discharge end of the multi-effect evaporation unit is connected to the steam inlet of the heat pump evaporator, and the fresh steam outlet is connected to the steam feed end of the multi-effect evaporation unit.
2. The self-heating circulating evaporator based on a heat pump according to claim 1, wherein, The heat exchanger of the heat pump evaporator is made of stainless steel and is covered with 80-110mm of rock wool as an insulation layer.
3. The self-heating circulating evaporator based on a heat pump according to claim 1, wherein, The multi-effect evaporation unit includes three to six effect evaporators connected sequentially along the steam flow direction, preferably a three-effect evaporator.
4. The self-heating circulating evaporator based on a heat pump according to claim 3, wherein, Each evaporator in the multi-effect evaporation unit is equipped with a feed inlet and a discharge outlet; The outlet of the previous-effect evaporator along the steam flow direction is connected to the inlet of its adjacent evaporator via a pipe.
5. The self-heating circulating evaporator based on a heat pump according to claim 3, wherein, Each evaporator in the multi-effect evaporation unit is equipped with a steam inlet and a steam outlet at its bottom and top, respectively. In addition to the steam outlet of the last effect evaporator, the steam outlet of the previous effect evaporator along the steam flow direction is connected to the steam inlet of the next adjacent effect evaporator via a pipe.
6. The self-heating circulating evaporator based on a heat pump according to claim 3, wherein, Each evaporator is equipped with a vacuum port, which is connected to a vacuum pump. The multi-effect evaporation unit also includes a condenser and an optional preheater. The steam outlet pipe of the last effect evaporator is divided into two paths, one of which is connected to the steam inlet of the heat pump evaporator, and the other is connected to the condenser.
7. A self-heating cycle evaporation method based on a heat pump, characterized in that, The process, employing the heat pump-based self-heating circulation evaporator according to any one of claims 1-6, includes the following steps: (1) The material to be concentrated enters the multi-effect evaporator from the material feed end of the multi-effect evaporator unit for concentration, and external steam enters the multi-effect evaporator from the steam feed end of the multi-effect evaporator unit to provide heat; (2) The exhaust gas from the steam outlet of the multi-effect evaporation unit enters the heat pump evaporator to recover energy and provide heat for the heat exchange medium. After condensing into liquid, it is discharged. The gaseous heat exchange medium evaporated by the heat pump evaporator is pressurized by the compressor and enters the integrated steam generator to condense and provide energy for fresh water. The condensed liquid heat exchange medium is depressurized by the throttling valve and returns to the heat pump evaporator. (3) The fresh water is heated to produce fresh steam, which enters the multi-effect evaporator to provide energy, and external steam is stopped or reduced.
8. The self-heating cycle evaporation method based on a heat pump according to claim 7, wherein, The multi-effect evaporation unit includes a triple-effect evaporator connected in sequence along the steam flow direction, with the external steam temperature being 140-160℃ and the pressure being 0.3-0.5 MPaG; The conditions for a single-effect evaporator include: a temperature of 80-100℃ and a pressure of 0.06-0.08 MPa.a. The conditions for a double-effect evaporator include: a temperature of 70-90℃ and a pressure of 0.046-0.048 MPa.a. The conditions for a triple-effect evaporator include: a temperature of 60-80℃ and a pressure of 0.030-0.032 MPa.a.
9. The self-heating cycle evaporation method based on a heat pump according to claim 7, wherein, The steam temperature at the steam outlet of the triple-effect evaporator is 50-90℃. The steam is divided into two parts: one part enters the heat pump evaporator, and the other part enters the condenser for condensation. The volume ratio of the steam entering the heat pump evaporator and the condenser is 80~90:10~20.
10. The self-heating cycle evaporation method based on a heat pump according to claim 7, wherein, The heat pump evaporator evaporates a gaseous heat exchange medium at 60-70℃. After being pressurized, the heat exchange medium enters the integrated steam generator and changes from a gaseous state to a liquid state. The released heat heats the fresh water to produce fresh steam at 80-130℃.