Low temperature evaporation device using Carnot cycle principle

Abstract

The present invention discloses a low-temperature evaporation device using the Carnot cycle principle, including a thin liquid kettle, an evaporator, a thin liquid pump, a chiller, a liquid preheater, a fan and a dewatering condenser. The thin solution that needs to be evaporated and concentrated is pumped from the thin liquid kettle to the thin liquid preheater by the thin liquid pump, and heat is exchanged with the high-temperature refrigerant gas that has been compressed and heated by the compressor of the chiller, and then enters the evaporator. The condensed refrigerant is throttled and depressurized by a throttle valve to gasify, and the water condenser exchanges heat with the wet air from the evaporator. The refrigerant absorbs heat and becomes gas, and then enters the chiller for compression and heating. At the same time, the liquid in the evaporator is continuously mixed with the thin liquid and enters the thin liquid pump for circulation until it is concentrated or crystallized. The present invention uses the Carnot cycle principle to fully use the heat of both the heating and cooling parts for evaporation. Its efficiency is far better than MVR evaporation that simply converts mechanical energy into pressure energy for heating, greatly reducing the energy consumption of sewage treatment and improving thermal efficiency.

Description

Technical Field

[0001] The invention relates to a low-temperature evaporation device, in particular to a low-temperature evaporation device utilizing the Carnot cycle principle. Background Art

[0002] With the deepening of environmental protection, the treatment of industrial wastewater, due to its complex composition and large treatment volume, in order to achieve "zero emission", both at home and abroad basically use evaporation concentration to concentrate and remove the substances dissolved in the water, and then reuse the water.

[0003] The previous treatment method basically used multiple-effect evaporation (see Appendix Figure 1 ) to separate the solid from the water. Steam is used as a heat source to evaporate the water in the liquid for reuse. In order to reduce the steam consumption of multi-effect evaporation, the steam heat energy generated by the last effect is completely wasted, and then the MVR steam recompression evaporation device was developed (see Appendix Figure 2 ), the steam generated by the evaporator enters the compressor, and the centrifugal (or Roots) compressor compresses the steam to increase the pressure, and then heats it up to evaporate the water in the material in the evaporator, but it is limited to: 1), because the material evaporation is carried out at the boiling point, once the boiling point of the evaporated solution exceeds the boiling point of water at the same pressure by 18°C, due to the pressure and temperature rise capacity of the compressor after the compressed steam, evaporation will not be able to proceed. 2), if the gas volatilized from the evaporated liquid is not completely water vapor, it will cause evaporation to be impossible or external steam will have to be used at the same time. It can be seen that MVR evaporation uses the method of converting mechanical energy into pressure energy, and then from pressure energy to heat energy. The mechanical energy is converted twice, and its thermal efficiency is relatively low. Summary of the invention

[0004] In order to overcome the above defects, the present invention provides a low-temperature evaporation device using the Carnot cycle principle. The high-efficiency heat-to-work conversion principle - Carnot cycle is used for industrial wastewater evaporation and concentration equipment, which can greatly reduce the energy consumption of wastewater treatment and improve the heat-to-work efficiency.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] A low temperature evaporation device using the Carnot cycle principle:

[0007] It includes a thin liquid kettle, an evaporator, a thin liquid pump, a chiller, a liquid preheater, a fan and a dehydration condenser.

[0008] The discharge port of the thin liquid kettle is connected to the feed port of the thin liquid pump through a pipeline, the discharge port of the thin liquid pump is connected to the feed port of the liquid preheater through a pipeline, and the discharge port of the liquid preheater is connected to the feed port of the evaporator through a pipeline;

[0009] The steam outlet arranged at the top of the evaporator is connected to the wet air inlet of the dehydration condenser through a pipeline; the dry air outlet of the dehydration condenser is connected to the air inlet of the fan through a pipeline, and the air outlet of the fan is connected to the air inlet of the evaporator through a pipeline;

[0010] The lower outlet arranged at the lower end of the evaporator is connected to the pipeline between the discharge port of the dilute liquid kettle and the feed port of the dilute liquid pump through a pipeline;

[0011] The outlet end of the chiller is connected to the high-temperature medium inlet of the liquid preheater through a pipeline, the low-temperature medium outlet of the liquid preheater is connected to the low-temperature medium inlet of the dehydration condenser through a pipeline, and the high-temperature medium outlet of the dehydration condenser is connected to the inlet end of the chiller through a pipeline.

[0012] As a further improvement of the present invention, the low-temperature evaporation device further comprises a concentrate pump, the feed port of the concentrate pump is connected to a pipeline connected to the lower outlet of the evaporator through a pipeline.

[0013] A throttle valve is provided on the pipeline between the low-temperature medium outlet of the liquid preheater and the low-temperature medium inlet of the dehydration condenser of the low-temperature evaporation device.

[0014] The feed inlet of the evaporator of the low-temperature evaporation device is located at the upper position of the cavity of the evaporator, and the air inlet of the evaporator is located at the lower position of the cavity of the evaporator.

[0015] A feed inlet is arranged on the upper side of the dilute liquid kettle of the low-temperature evaporation device.

[0016] A condensed water outlet is provided on the lower side of the dehydration condenser of the low-temperature evaporation device.

[0017] The beneficial effects of the present invention are as follows: the present invention utilizes the Carnot cycle principle to fully utilize the heat energy of both heating and cooling for evaporation, and its efficiency is far better than MVR evaporation which simply converts mechanical energy into pressure energy for heating, greatly reducing the energy consumption of sewage treatment and improving thermal efficiency. At the same time, evaporation is not performed at the boiling point of the feed liquid, and there is no need to consume heat energy to heat the feed liquid to the boiling point. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of existing multiple-effect evaporation;

[0019] Figure 2 It is a schematic diagram of the existing MVR evaporation process;

[0020] Figure 3 It is a schematic diagram of the principle of the present invention;

[0021] Figure 4 It is a schematic diagram of the Carnot cycle principle of the present invention.

[0022] Combined with the attached drawings, the following description is given:

[0023] 1——liquid kettle for thin material; 2——evaporator;

[0024] 3——concentrated liquid pump; 4——diluted liquid pump;

[0025] 5——Water chiller; 6——Liquid preheater;

[0026] 7——fan; 8——water removal condenser;

[0027] 9——Throttle valve. DETAILED DESCRIPTION

[0028] A preferred embodiment of the present invention is described in detail below in conjunction with the accompanying drawings.

[0029] See attached Figure 3 , which is a low-temperature evaporation device using the Carnot cycle principle described in the present invention, mainly includes a thin liquid kettle 1, an evaporator 2, a concentrated liquid pump 3, a thin liquid pump 4, a chiller 5, a liquid preheater 6, a fan 7, a dehydration condenser 8 and a throttle valve 9.

[0030] Among them, the discharge port of the thin liquid kettle 1 is connected to the feed port of the thin liquid pump 4 through a pipeline, the discharge port of the thin liquid pump 4 is connected to the feed port of the liquid preheater 6 through a pipeline, and the discharge port of the liquid preheater 6 is connected to the feed port of the evaporator 2 through a pipeline.

[0031] The steam outlet arranged at the top of the evaporator 2 is connected to the wet air inlet of the dehydration condenser 8 through a pipeline; the dry air outlet of the dehydration condenser 8 is connected to the air inlet of the fan 7 through a pipeline, and the air outlet of the fan 7 is connected to the air inlet of the evaporator 2 through a pipeline.

[0032] The lower outlet arranged at the lower end of the evaporator 2 is connected to the pipeline between the discharge port of the dilute liquid kettle 1 and the feed port of the dilute liquid pump 4 through a pipeline.

[0033] The outlet end of the chiller 5 is connected to the high-temperature medium inlet of the liquid preheater 6 through a pipeline, the low-temperature medium outlet of the liquid preheater 6 is connected to the low-temperature medium inlet of the dehydration condenser 8 through a pipeline, and the high-temperature medium outlet of the dehydration condenser 8 is connected to the inlet end of the chiller 5 through a pipeline.

[0034] The feed port of the concentrate pump 3 is connected to the pipeline connected to the lower outlet of the evaporator 2 through a pipeline.

[0035] A throttle valve 9 is provided on the pipeline between the low-temperature medium outlet of the liquid preheater 6 and the low-temperature medium inlet of the dehydration condenser 8 .

[0036] The feed port of the evaporator 2 is located at the upper position of the cavity of the evaporator 2, and the air inlet of the evaporator 2 is located at the lower position of the cavity of the evaporator; a feed port is provided on the upper side of the thin material liquid kettle 1, and a condensed water outlet is provided on the lower side of the dehydration condenser 8.

[0037] The working principle of the low-temperature evaporation device using the Carnot cycle principle is as follows:

[0038] The dilute solution that needs to be evaporated and concentrated, i.e., the feed liquid, is added into the dilute liquid kettle 1 from the feed inlet on the upper side thereof, and is sent by the dilute liquid pump 4 to the dilute liquid preheater 6 for heat exchange with the high-temperature refrigerant gas compressed and heated by the compressor of the chiller 5. The feed liquid is heated and the refrigerant is condensed. The heated dilute liquid enters the evaporator 2, and the condensed refrigerant is throttled and depressurized by the throttle valve 9 to be vaporized, and the water removal condenser 8 exchanges heat with the extremely high water content wet air from the evaporator 2. The water in the wet air is condensed, and the water content in the air is greatly reduced, becoming dry air and being sent by the fan 7 to the evaporator 2 to absorb the moisture in the feed liquid. The refrigerant becomes gas after absorbing the heat, and then enters the chiller 5 for compression and heating. At the same time, the feed liquid in the evaporator 2 is continuously mixed with the dilute liquid and enters the dilute liquid pump 4 for circulation until it is concentrated or crystallized, and then is sent out of the system by the concentrated liquid pump 3.

[0039] As we all know, the "Carnot cycle" is to transfer the heat of one of the two parts with the same enthalpy to the other part by mechanical energy, so that one part is heated up and the other part is cooled down. This method is currently used in refrigerators. Energy is transferred, such as refrigerator refrigeration and air conditioning. However, only one of the two parts, heating and cooling, is used, and the other part of the energy is wasted.

[0040] See also Figure 4 , which is a heat transfer diagram of the "Carnot cycle" adopted in the present invention: both the heating and cooling parts are fully utilized for evaporation, and its efficiency is far better than MVR evaporation which simply converts mechanical energy into pressure energy for heating, as described in detail below.

[0041] The present invention utilizes the "Carnot cycle" principle. The material is transported to the thin liquid preheater 6 via the thin liquid pump 1. In this device, the Carnot cycle 2-3 (see the attached Figure 4) is an isothermal exothermic process in which the entropy value decreases. The refrigerant that is compressed by the compressor and heated up releases heat to heat up the dilute liquid, and the refrigerant changes from vapor to liquid due to the decrease in entropy value due to the heat released. The heated liquid enters the evaporator 2, and the refrigerant that becomes liquid passes through the throttle valve and pressure reducing valve, which is an isentropic process. The Carnot cycle 3-4 process is an adiabatic expansion. Since this process does not output external work, the temperature of the refrigerant decreases. The refrigerant that has become a vapor then enters the water removal condenser 8 pipe pass and exchanges heat with the high-humidity air coming out of the evaporator 2. This process is the Carnot cycle 4-1, an isothermal endothermic process in which the entropy value increases. The air with high humidity content is therefore cooled, and the water vapor contained therein is condensed and removed. After the moisture content in the air is reduced, it is sent to the evaporator by the fan, and the vapor phase refrigerant enters the compressor of the chiller 5 again to undergo adiabatic compression in the isentropic process of the Carnot cycle.

[0042] This cycle of converting mechanical energy into thermal energy is repeated over and over again.

[0043] The heat energy of the compressor is used to heat the thin liquid, and the cold energy is used to remove moisture from the air with high moisture content coming out of the evaporator to turn it into dry air.

[0044] The thin liquid enters the evaporator and is fully contacted with the dry air with low moisture content. The dry air takes away the moisture in the liquid and turns it into air with high moisture content. The liquid is thus concentrated. Before the concentration requirement is reached, the liquid is still sent to the thin liquid preheater by the thin liquid pump for heating and then enters the evaporator. The cycle is repeated until the concentration requirement is reached or the thin liquid slowly and continuously enters the system. After concentration, solids are continuously precipitated and the system runs continuously.

[0045] It can be seen that the low-temperature evaporation device using the Carnot cycle principle uses the Carnot cycle principle to fully use the heat energy of both heating and cooling for evaporation, and its efficiency is far better than MVR evaporation that simply converts mechanical energy into pressure energy for heating, greatly reducing the energy consumption of sewage treatment and improving thermal efficiency.

Claims

1. A low temperature evaporation device using the Carnot cycle principle, characterized in that: It comprises a thin liquid kettle (1), an evaporator (2), a concentrated liquid pump (3), a thin liquid pump (4), a chiller (5), a liquid preheater (6), a fan (7) and a water removal condenser (8); The discharge port of the thin liquid kettle (1) is connected to the feed port of the thin liquid pump (4) via a pipeline, the discharge port of the thin liquid pump (4) is connected to the feed port of the liquid preheater (6) via a pipeline, and the discharge port of the liquid preheater (6) is connected to the feed port of the evaporator (2) via a pipeline; The steam outlet arranged at the top of the evaporator (2) is connected to the wet air inlet of the dehydration condenser (8) through a pipeline; the dry air outlet of the dehydration condenser (8) is connected to the air inlet of the fan (7) through a pipeline, and the air outlet of the fan (7) is connected to the air inlet of the evaporator (2) through a pipeline; The lower outlet arranged at the lowest end of the evaporator (2) is connected to a pipeline between the discharge port of the thin liquid kettle (1) and the feed port of the thin liquid pump (4) through a pipeline; The feed inlet of the concentrate pump (3) is connected to the pipeline connected to the lower outlet of the evaporator (2) through a pipeline; The outlet end of the chiller (5) is connected to the high-temperature medium inlet of the liquid preheater (6) through a pipeline, the low-temperature medium outlet of the liquid preheater (6) is connected to the low-temperature medium inlet of the dehydration condenser (8) through a pipeline, and the high-temperature medium outlet of the dehydration condenser (8) is connected to the inlet end of the chiller (5) through a pipeline; A throttle valve (9) is provided on the pipeline between the low-temperature medium outlet of the liquid preheater (6) and the low-temperature medium inlet of the dehydration condenser (8); The working principle of the low-temperature evaporation device using the Carnot cycle principle is as follows: The dilute solution to be evaporated and concentrated, i.e., the feed liquid, is added into the dilute liquid kettle (1) from the feed inlet on the upper side of the dilute liquid kettle (1), and is sent to the feed liquid preheater (6) by the dilute liquid pump (4) to exchange heat with the high-temperature refrigerant gas that has been compressed and heated by the compressor of the chiller (5). The feed liquid is heated and the refrigerant is condensed. The heated dilute liquid enters the evaporator (2), and the condensed refrigerant is throttled and depressurized and gasified by the throttling valve (9). The dehydration condenser (8) and the evaporator ( 2) is used for heat exchange with the extremely high water content humid air. The water in the humid air is condensed, and the water content in the air is greatly reduced. The dry air is sent to the evaporator (2) by the fan (7) to absorb the water in the liquid. The refrigerant absorbs the heat and becomes gas. It then enters the chiller (5) for compression and temperature increase. At the same time, the liquid in the evaporator (2) is continuously mixed with the dilute liquid and enters the dilute liquid pump (4) for circulation until it is concentrated or crystallized. The concentrated liquid pump (3) then sends it out of the system.

2. The low-temperature evaporation device using the Carnot cycle principle according to claim 1 is characterized in that: The feed inlet of the evaporator (2) is located at an upper position of the cavity of the evaporator (2), and the air inlet of the evaporator (2) is located at a lower position of the cavity of the evaporator.

3. The low-temperature evaporation device using the Carnot cycle principle according to claim 1 is characterized in that: A feed inlet is provided on the upper side of the thin material liquid kettle (1).

4. The low-temperature evaporation device using the Carnot cycle principle according to claim 1 is characterized in that: A condensed water outlet is provided on the lower side of the dewatering condenser (8).

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