Heat pump rectification system

Abstract

The utility model relates to the technical field of heat pump rectification, and particularly discloses a heat pump rectification system which comprises a rectification tower; the tower top gas liquefaction system comprises a compressor connected with a gas phase at the top of the rectifying tower, and a reboiler, a throttling device, a condenser and a flow divider which are sequentially connected with the compressor; liquid phase connection at the bottom of the rectifying tower is communicated with the reboiler, the tower bottom reboiling system comprises an auxiliary reboiler and a flash evaporator which are sequentially communicated with the reboiler, and the flash evaporator is communicated to the rectifying tower; and the gas phase at the top of the rectifying tower is heated by the compressor and then enters the reboiler to exchange heat with the liquid phase at the bottom of the rectifying tower, so that the rectifying energy consumption can be reduced, and the energy-saving effect is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat pump rectification, and specifically discloses a heat pump rectification system. BACKGROUND

[0002] Rectification refers to a process that, under certain pressure, different components of a liquid mixture are separated from each other through multiple partial vaporization and multiple partial condensation in a tower, and is the most widely used liquid mixture separation operation in industry, and is widely used in petroleum, chemical industry, light industry, food industry, metallurgy and other departments.

[0003] The operation characteristics of a conventional rectification tower are that an external refrigerant is needed to cool the top of the tower to remove heat from the top of the tower, and an external heating agent is needed to heat the bottom of the tower to provide heat to the tower. If the heat of the tower top gas is transferred to the tower bottom material, there is a problem that the temperature of the tower top is lower than that of the tower bottom. The heat pump rectification is to compress the tower top vapor through a compressor to increase the temperature and pressure, and when the temperature and pressure reach the required temperature and pressure, the heat is released through the evaporator at the tower bottom, the tower top vapor is condensed into a liquid phase, and the tower bottom liquid is heated. The heat pump rectification sends the heat of the tower top vapor to the tower bottom, and also saves most of the cooling water consumption, thereby achieving the purpose of energy saving.

[0004] However, for different rectification processes of different substances, the temperature difference between the top and bottom of the rectification tower is also different. If the temperature difference between the top and bottom of the tower is too large, the tower top gas needs to be greatly heated to make the tower bottom liquid phase reboil, thereby increasing the energy consumption of the gas compressor, and even causing the energy consumption of the heat pump rectification to be higher than that of the ordinary rectification. Generally, the condition for the rectification tower to be able to be modified by the heat pump is that the temperature difference between the top and bottom of the tower is less than 35 DEG C, which to a great extent limits the heat pump rectification technology. Moreover, if the tower top gas phase is in a saturated state, direct compression by the compressor is prone to liquefaction, and liquid hammer occurs in the compressor, which not only affects the service life of the compressor, but also causes a large amount of energy loss through heat exchange between the compressor and the air. Therefore, the present application provides a heat pump rectification system to solve the above problems. CONTENT OF THE UTILITY MODEL

[0005] The purpose of the present application is to provide a heat pump rectification system which can reduce the energy consumption of rectification and achieve the effect of energy saving.

[0006] In order to achieve the above purpose, the basic scheme of the present application provides a heat pump rectification system, which comprises:

[0007] a rectification tower;

[0008] a tower top gas liquefaction system comprising a compressor connected with the gas phase at the top of the rectification tower, a reboiler connected with the compressor in sequence, a throttling device, a condenser and a flow divider;

[0009] The tower bottom reboiling system is connected with the liquid phase at the bottom of the rectifying tower and communicates with the reboiler, and the tower bottom reboiling system comprises an auxiliary reboiler and a flash evaporator which are sequentially communicated with the reboiler, and the flash evaporator communicates with the rectifying tower;

[0010] The gaseous phase at the top of the rectifying tower is increased in temperature by the compressor and then enters the reboiler to exchange heat with the liquid phase at the bottom of the rectifying tower.

[0011] Further, the tower top gas liquefaction system further comprises a first heat exchanger arranged between the top of the rectifying tower and the compressor and used for preliminarily heating the gaseous phase at the top of the rectifying tower.

[0012] Further, the tower top gas liquefaction system further comprises a second heat exchanger arranged between the reboiler and the throttling device.

[0013] Further, the tower top gas liquefaction system further comprises a circulating medium pipeline arranged between the first heat exchanger and the second heat exchanger.

[0014] Further, the compressor is any one of a Roots compressor, a centrifugal compressor or a double-screw compressor.

[0015] The rectifying tower is a rectifying tower of a plate tower structure or a rectifying tower of a packed tower structure.

[0016] The condenser is any one of an air cooler, an evaporative air cooler or a water cooler.

[0017] The reboiler and the auxiliary reboiler are of a plate heat exchange structure or a forced circulation heat exchange structure.

[0018] Further, the first heat exchanger and the second heat exchanger are of a plate heat exchange structure or a forced circulation heat exchange structure.

[0019] The principle and effects of the present scheme are as follows:

[0020] 1. The gaseous phase at the top of the rectifying tower is increased in temperature by the compressor and then enters the reboiler to exchange heat with the liquid phase at the bottom of the rectifying tower, and the fluid after being decreased in temperature by the throttling device is liquefied by the condenser, and finally, the fluid is controlled by the flow divider to be produced or returned to the rectifying tower.

[0021] 2. The liquid phase at the bottom of the rectifying tower is increased in temperature by the reboiler and then is secondarily heated by the auxiliary reboiler, and finally, the fluid is vaporized by the flash evaporator and then returned to the rectifying tower. By the secondary heat exchange, the process of the liquid phase at the bottom of the rectifying tower being increased in temperature is more gentle and can be flexibly adjusted, and the temperature requirement of the hot side of the reboiler is reduced, thereby reducing the temperature requirement of the outlet of the compressor.

[0022] 3、The first heat exchanger and the second heat exchanger are arranged, which can preliminarily heat the overhead gas phase distilled out of the rectifying tower, so as to reduce the energy consumption of the compressor, and can avoid the problem that the overhead gas phase is in a saturated state and is easily liquefied by directly compressing by the compressor, and the circulating medium pipeline is arranged, so that part of the heat in the gas after heat exchange of the reboiler can also be used for preliminarily heating the overhead gas phase. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0024] Figure 1 A flow chart of a heat pump rectifying system is shown. DETAILED DESCRIPTION

[0025] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined utility model purposes, the specific embodiments, structures, features and effects according to the present application will be described in detail below in combination with the drawings and preferred embodiments.

[0026] The reference signs in the drawings of the specification include: rectifying tower 1, compressor 2, reboiler 3, throttling device 4, heat exchanger 5, flow divider 6, auxiliary reboiler 7, flash evaporator 8, first heat exchanger 9, second heat exchanger 10.

[0027] A heat pump rectifying system, as shown in the embodiment Figure 1 The rectifying tower 1, the overhead gas liquefaction system and the bottom reboiling system are shown, and the specific embodiments are as follows:

[0028] The rectifying tower 1 is a plate tower structure rectifying tower or a packed tower structure rectifying tower.

[0029] The top gas liquefaction system includes a compressor 2 connected to the top gas phase of the distillation tower 1, a reboiler 3 connected to the compressor 2 in sequence, a throttling device 4, a condenser and a splitter 6. The compressor 2 is any one of a Roots compressor, a centrifugal compressor or a twin-screw compressor. The throttling device 4 can be a throttle valve. The condenser is any one of an air cooler, an evaporative air cooler or a water cooler. In order to avoid the top gas phase of the distillation tower 1 being in a saturated state, the problem of liquefaction is easily caused by direct compression by the compressor 2. A first heat exchanger 9 is arranged between the top of the distillation tower 1 and the compressor 2, a second heat exchanger 10 is arranged between the reboiler 3 and the throttling device 4, a circulating medium pipeline is arranged between the first heat exchanger 9 and the second heat exchanger 10, and the first heat exchanger 9 and the second heat exchanger 10 are plate heat exchange structures or forced circulation heat exchange structures.

[0030] Bottom reboiler system: The liquid phase at the bottom of the distillation tower 1 is connected to the reboiler 3. The reboiler 3 is part of the top gas liquefaction system and also part of the bottom reboiler system. The bottom reboiler system also includes an auxiliary reboiler 7 and a flash evaporator 8 which are sequentially connected to the reboiler 3. The flash evaporator 8 is connected to the distillation tower 1. The reboiler 3 and the auxiliary reboiler 7 are plate heat exchange structures or forced circulation heat exchange structures.

[0031] In the tower top gas liquefaction system of this embodiment, the gas phase at the top of the distillation tower 1 enters the first heat exchanger 9, and the medium of the circulating medium pipeline preliminarily heats the gas phase at the top of the distillation tower 1; the heated gas phase at the top of the distillation tower 1 enters the compressor 2 for pressurization and temperature increase; then enters the reboiler 3, and cools down by heat exchange with the liquid phase at the bottom of the distillation tower 1 in the reboiler 3. The temperature after cooling is still higher than the liquid phase temperature at the bottom of the distillation tower 1, that is, higher than the gas phase temperature at the top of the distillation tower 1, and exchanges with the medium of the circulating medium pipeline through the second heat exchanger 10 to cool down again, and is reduced in pressure and cooled by the throttling device 4. The gas after throttling evaporation is then liquefied by the condenser, and finally the splitter 6 is used to control whether the fluid is produced or refluxed to the distillation tower 1.

[0032] In the bottom reboiling system of this embodiment, the liquid phase at the bottom of the distillation tower 1 enters the reboiler 3 to absorb heat and heat up, then enters the auxiliary reboiler 7 for secondary heat exchange, and finally flows through the flash evaporator 8 to be vaporized and then refluxes into the distillation tower 1.

[0033] In this embodiment, the heat source of the auxiliary reboiler 7 is provided separately. By detecting the temperature and pressure at the air inlet and outlet ends of the auxiliary reboiler 7, a controller is used to automatically control the heat of the medium supplied to the auxiliary reboiler 7, thereby accurately regulating the vaporization amount of the bottom liquid.

[0034] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A heat pump distillation system, characterized in that: include: distillation tower; The top gas liquefaction system includes a compressor connected to the top gas phase of the distillation tower, a reboiler, a throttling device, a condenser and a splitter connected in sequence to the compressor; A tower bottom reboiling system, wherein the liquid phase at the bottom of the distillation tower is connected to the reboiler, and the tower bottom reboiling system comprises an auxiliary reboiler and a flash evaporator which are sequentially connected to the reboiler, and the flash evaporator is connected to the distillation tower; The gas phase at the top of the distillation tower is heated by the compressor and then enters the reboiler to exchange heat with the liquid phase at the bottom of the distillation tower.

2. A heat pump distillation system according to claim 1, characterized in that: The tower top gas liquefaction system further includes a first heat exchanger which is arranged between the top of the distillation tower and the compressor and which preliminarily heats the gas phase at the top of the distillation tower.

3. A heat pump distillation system according to claim 2, characterized in that: The tower top gas liquefaction system further includes a second heat exchanger arranged between the reboiler and the throttling device.

4. A heat pump distillation system according to claim 3, characterized in that: The tower top gas liquefaction system further includes a circulating medium pipeline arranged between the first heat exchanger and the second heat exchanger.

5. A heat pump distillation system according to any one of claims 1 to 4, characterized in that: The compressor is any one of a Roots compressor, a centrifugal compressor or a twin-screw compressor; The distillation tower is a distillation tower with a plate tower structure or a distillation tower with a packed tower structure; The condenser is any one of an air cooler, an evaporative air cooler or a water cooler; The reboiler and the auxiliary reboiler are plate-type heat exchange structures or forced circulation heat exchange structures.

6. A heat pump distillation system according to claim 3, characterized in that: The first heat exchanger and the second heat exchanger are plate-type heat exchange structures or forced circulation heat exchange structures.

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