Flash evaporation device for twice cooling of liquid ammonia in liquid ammonia refrigeration process

Abstract

The utility model belongs to the technical field of liquid ammonia refrigeration, and particularly relates to a flash evaporation device for twice cooling of liquid ammonia in a liquid ammonia refrigeration process. According to a flash tank disclosed in the prior art, through pressure reduction, liquid ammonia is subjected to flash vaporization and heat absorption at the liquid ammonia liquid level in the flash tank, heat exchange between the liquid ammonia and gaseous ammonia occurs at the liquid ammonia liquid level, and the flash vaporization refrigeration effect is poor; according to the utility model, the atomization device is arranged, so that flash gas ammonia and atomized liquid ammonia are in full contact in a space above the liquid level of liquid ammonia in the flash tank for heat exchange; compared with a flash tank disclosed in the prior art, heat exchange between liquid ammonia and gas ammonia exists in the space above the liquid level of the liquid ammonia in the flash tank, the heat exchange area is larger, and the flash refrigeration effect is better, so that the temperature of the liquid ammonia can be efficiently reduced. And by arranging the heat exchanger, the liquid ammonia is cooled by utilizing the low-temperature gas ammonia gasified by flash evaporation, so that the cooling capacity in the gas ammonia can be effectively utilized, and the waste of the cooling capacity in the gas ammonia is avoided.

Description

Technical Field

[0001] The utility model belongs to the technical field of liquid ammonia refrigeration, in particular to a flash evaporation device for twice cooling liquid ammonia in a liquid ammonia refrigeration process. Background Art

[0002] Liquid ammonia as a refrigerant offers advantages such as a low boiling point, moderate pressure, high cooling capacity per unit volume, minimal throttling losses, easy detection of dissolved water and leaks, and low cost. Liquid ammonia in refrigeration processes achieves its cooling effect through a series of physical transformations. The compressor compresses low-pressure ammonia vapor into high-pressure gas. The high-pressure gas enters the condenser, where it is cooled and converted into liquid ammonia. The liquid ammonia is then depressurized by a throttle valve and then enters the evaporator, where it absorbs heat, lowering the ambient temperature. The evaporated gaseous ammonia is then drawn back into the compressor, completing the refrigeration cycle. Ammonia refrigeration systems employ different cooling methods depending on their application, such as direct evaporation or indirect refrigeration with a secondary refrigerant. Direct evaporation involves reducing the pressure of liquid ammonia and feeding it into a flash tank. Within the flash tank, the liquid ammonia vaporizes, absorbing heat and transforming into gaseous ammonia, which then flows out of the flash tank. The remaining liquid ammonia is cooled and subsequently used as a refrigerant. However, during the flash evaporation process, the liquid ammonia temperature is lowered solely by the reduced pressure, which causes the partial vaporization of the liquid ammonia to absorb heat, resulting in low cooling efficiency. In addition, the ammonia gas after flash evaporation directly enters the compressor for compression. Since the temperature of this part of the ammonia gas is lowered, this part of the cooling capacity is not effectively utilized, resulting in a waste of cooling capacity. Utility Model Content

[0003] Based on the existing technical problems, the utility model provides a flash evaporation device for twice cooling liquid ammonia in a liquid ammonia refrigeration process. This method greatly plays the role of liquid ammonia flash evaporation refrigeration, making the temperature of liquid ammonia obtained by flash evaporation lower, and also fully utilizing the cooling capacity of gaseous ammonia obtained by flash evaporation.

[0004] In order to solve the above technical problems, the technical solutions of the present invention are as follows:

[0005] A flash evaporation device for twice cooling liquid ammonia in a liquid ammonia refrigeration process comprises a flash tank and a heat exchanger, wherein the heat exchanger is arranged above the flash tank and is provided with a liquid ammonia inlet a, a liquid ammonia outlet a, a gaseous ammonia inlet a, and a gaseous ammonia outlet a; the liquid ammonia inlet b of the flash tank is connected to the liquid ammonia outlet a of the heat exchanger, and the gaseous ammonia outlet b of the flash tank is connected to the gaseous ammonia inlet a of the heat exchanger; the liquid ammonia outlet b is provided at the bottom of the flash tank; and a plurality of atomizing devices are provided inside the flash tank, and the plurality of atomizing devices are connected to the liquid ammonia inlet b of the flash tank via pipelines.

[0006] Furthermore, a regulating valve is provided on the branch pipeline connecting the plurality of atomizing devices and the liquid ammonia inlet b, and the regulating valve is provided outside the flash tank shell.

[0007] Furthermore, the atomizing device is a hollow rectangular parallelepiped shell structure or a cylindrical shell structure or a combination structure with a plurality of branch pipes provided on a main pipe. The upper shell of the atomizing device is provided with a liquid ammonia inlet, which is connected to the liquid ammonia inlet b, and the lower shell of the atomizing device is provided with a plurality of circular holes.

[0008] Furthermore, a plurality of circular holes are provided on the lower shell of the atomizing device, and atomizing nozzles are provided on the plurality of circular holes.

[0009] Furthermore, the heat exchanger is a plate heat exchanger or a shell and tube heat exchanger.

[0010] Furthermore, a liquid level gauge is provided on the flash tank. Beneficial effects

[0011] 1. In flash tanks disclosed in the prior art, liquid ammonia enters the flash tank and, due to pressure reduction, flash vaporizes at the liquid ammonia surface, absorbing heat. Heat exchange between the liquid ammonia and the gaseous ammonia occurs at the liquid ammonia surface, resulting in poor flash vaporization refrigeration. The present invention, by providing an atomizing device, allows the flashed gaseous ammonia and the atomized liquid ammonia to fully contact and exchange heat within the space above the liquid ammonia surface within the flash tank. Compared to flash tanks disclosed in the prior art, heat exchange between the liquid ammonia and the gaseous ammonia occurs in the space above the liquid ammonia surface within the flash tank, resulting in a larger heat exchange area and a better flash refrigeration effect, thereby efficiently reducing the temperature of the liquid ammonia.

[0012] 2. The utility model provides a heat exchanger to utilize the low-temperature gaseous ammonia vaporized by flash gas to cool the liquid ammonia, thereby effectively utilizing the cooling capacity in the gaseous ammonia and avoiding the waste of cooling capacity in the gaseous ammonia.

[0013] 3. The utility model realizes flow regulation of liquid ammonia atomization by arranging regulating valves on branch pipes connecting several atomizing devices and liquid ammonia inlet b, flexibly adjusts the number of operating atomizing devices, and avoids poor atomization effect when the liquid ammonia flow is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A is a schematic diagram of the main structure of the flash tank of the utility model;

[0015] Figure 2 b is a schematic diagram of the main structure of the flash tank of the utility model;

[0016] Figure 3 c is a schematic diagram of the main structure of the flash tank of the utility model;

[0017] Figure 4 This is a left-side perspective structural diagram of the internal structure of the flash tank of the present invention;

[0018] Figure 5 This is a bottom view of the atomizing device with a rectangular shell structure according to the present invention;

[0019] Figure 6 This is a bottom view of the atomizing device with a cylindrical shell structure according to the present invention;

[0020] Figure 7 This is a bottom view of the structure of the atomizing device of the utility model, in which a plurality of branch pipes are arranged on the main pipe;

[0021] In the figure: 1-flash tank; 2-heat exchanger; 3-liquid ammonia inlet a; 4-gaseous ammonia outlet a; 5-liquid ammonia outlet a; 6-liquid ammonia inlet b; 7-gaseous ammonia outlet b; 8-gaseous ammonia inlet a; 9-atomizer; 10-liquid ammonia outlet b; 11-circular small hole. DETAILED DESCRIPTION Example 1

[0022] Reference Figure 1 、 Figure 4 、 Figure 5 In order to achieve a better refrigeration effect by flash evaporation of liquid ammonia and at the same time reduce the cooling capacity loss caused by flash evaporation of liquid ammonia as much as possible, the utility model provides a flash evaporation device for twice cooling liquid ammonia in a liquid ammonia refrigeration process, comprising a flash tank 1 and a heat exchanger 2, wherein the heat exchanger 2 is arranged above the flash tank 1, and the heat exchanger 2 is a shell and tube heat exchanger 2, wherein the heat exchanger 2 is provided with a liquid ammonia inlet a3, a liquid ammonia outlet a5, a gaseous ammonia inlet a8, and a gaseous ammonia outlet a4. The liquid ammonia is passed through the tube side through the liquid ammonia inlet a3 and the liquid ammonia outlet a5, and the gaseous ammonia is passed through the shell side through the gaseous ammonia inlet a8 and the gaseous ammonia outlet a4. The liquid ammonia inlet b6 of the flash tank 1 is connected to the liquid ammonia outlet a5 of the heat exchanger 2, and the gaseous ammonia outlet b7 of the flash tank 1 is connected to the gaseous ammonia inlet a8 of the heat exchanger 2; a liquid ammonia outlet b10 is provided at the bottom of the flash tank 1; an atomizing device 9 is provided inside the flash tank 1, and the atomizing device 9 is connected to the liquid ammonia inlet b6 of the flash tank 1 through a pipeline;

[0023] The atomizing device 9 is a rectangular shell structure with a hollow interior. The upper shell of the atomizing device 9 is provided with a liquid ammonia inlet, which is connected to the liquid ammonia inlet b6. A plurality of circular holes 11 are provided on the lower shell of the atomizing device 9, through which the liquid ammonia is sprayed out and atomized. A liquid level gauge is provided on the flash tank 1 to detect the liquid level in the flash tank 1 to prevent the liquid level from being too high and submerging the atomizing device 9, thereby losing the atomization effect.

[0024] When the device is in operation, liquid ammonia first enters the heat exchanger 2, and is cooled by the gaseous ammonia flashed out of the flash tank 1 in the heat exchanger 2. The liquid ammonia cooled in the heat exchanger 2 enters the flash tank 1, and is atomized and flashed by the atomizing device 9 in the flash tank 1. A part of the liquid ammonia is flashed and converted into gaseous ammonia, flows out of the flash tank 1 and enters the heat exchanger 2, and the other part of the liquid ammonia is cooled and collected in the flash tank 1; the gaseous ammonia is heated in the heat exchanger 2 and flows out of the heat exchanger 2; during operation, the liquid level in the flash tank 1 is controlled to be lower than the atomizing device 9. Example 2

[0025] Reference Figure 2 、 Figure 4 、 Figure 6 In order to achieve a better refrigeration effect by flash evaporation of liquid ammonia and at the same time reduce the cooling capacity loss caused by flash evaporation of liquid ammonia as much as possible, the utility model provides a flash evaporation device for twice cooling liquid ammonia in a liquid ammonia refrigeration process, comprising a flash tank 1 and a heat exchanger 2, wherein the heat exchanger 2 is arranged above the flash tank 1, and the heat exchanger 2 is a shell and tube heat exchanger 2, wherein the heat exchanger 2 is provided with a liquid ammonia inlet a3, a liquid ammonia outlet a5, a gaseous ammonia inlet a8, and a gaseous ammonia outlet a4, wherein the liquid ammonia is passed through the tube side through the liquid ammonia inlet a3 and the liquid ammonia outlet a5, and the gaseous ammonia is passed through the shell side through the gaseous ammonia inlet a8 and the gaseous ammonia outlet a4, and the liquid ammonia inlet b6 of the flash tank 1 is connected to the heat exchanger 2. The liquid ammonia outlet a5 of the flash tank 1 is connected, and the gaseous ammonia outlet b7 of the flash tank 1 is connected to the gaseous ammonia inlet a8 of the heat exchanger 2; a liquid ammonia outlet b10 is provided at the bottom of the flash tank 1; three atomizing devices 9 are provided inside the flash tank 1, and the three atomizing devices 9 are connected to the liquid ammonia inlet b6 of the flash tank 1 through a pipeline; a regulating valve is provided on the branch pipeline connecting the three atomizing devices 9 and the liquid ammonia inlet b6, and the regulating valve is provided outside the shell of the flash tank 1, and the atomizing effect of the atomizing device 9 is adjusted by the regulating valve to avoid poor atomization effect when the liquid ammonia flow rate is small. When the liquid ammonia flow rate is small, one atomizing device 9 is stopped and two atomizing devices 9 are operated.

[0026] The atomizing device 9 is a cylindrical shell structure with a hollow interior. The upper shell of the atomizing device 9 is provided with a liquid ammonia inlet, which is connected to the liquid ammonia inlet b6. The lower shell of the atomizing device 9 is provided with a plurality of circular holes 11, through which the liquid ammonia is sprayed out and atomized. A liquid level gauge is provided on the flash tank 1 to detect the liquid level in the flash tank 1 to prevent the liquid level from being too high and submerging the atomizing device 9, thereby losing the atomization effect.

[0027] When the device is in operation, liquid ammonia first enters the heat exchanger 2, and is cooled by the gaseous ammonia flashed out of the flash tank 1 in the heat exchanger 2. The liquid ammonia cooled in the heat exchanger 2 enters the flash tank 1, and is atomized and flashed by the atomizing device 9 in the flash tank 1. A part of the liquid ammonia is flashed and converted into gaseous ammonia, flows out of the flash tank 1 and enters the heat exchanger 2, and the other part of the liquid ammonia is cooled and collected in the flash tank 1; the gaseous ammonia is heated in the heat exchanger 2 and flows out of the heat exchanger 2; during operation, the liquid level in the flash tank 1 is controlled to be lower than the atomizing device 9. Example 3

[0028] Reference Figure 3 、 Figure 4 、 Figure 7 In order to achieve a better refrigeration effect by flash evaporation of liquid ammonia and at the same time reduce the cooling capacity loss caused by flash evaporation of liquid ammonia as much as possible, the utility model provides a flash evaporation device for twice cooling liquid ammonia in a liquid ammonia refrigeration process, comprising a flash tank 1 and a heat exchanger 2, wherein the heat exchanger 2 is arranged above the flash tank 1, and the heat exchanger 2 is a shell and tube heat exchanger 2, wherein the heat exchanger 2 is provided with a liquid ammonia inlet a3, a liquid ammonia outlet a5, a gaseous ammonia inlet a8, and a gaseous ammonia outlet a4, wherein the liquid ammonia is passed through the tube side through the liquid ammonia inlet a3 and the liquid ammonia outlet a5, and the gaseous ammonia is passed through the shell side through the gaseous ammonia inlet a8 and the gaseous ammonia outlet a4, and the liquid ammonia inlet b6 of the flash tank 1 is connected to the heat exchanger 2. The liquid ammonia outlet a5 is connected, and the gaseous ammonia outlet b7 of the flash tank 1 is connected to the gaseous ammonia inlet a8 of the heat exchanger 2; a liquid ammonia outlet b10 is provided at the bottom of the flash tank 1; three atomizing devices 9 are provided inside the flash tank 1, and the three atomizing devices 9 are connected to the liquid ammonia inlet b6 of the flash tank 1 through a pipeline; a regulating valve is provided on the branch pipeline connecting the three atomizing devices 9 and the liquid ammonia inlet b6, and the regulating valve is provided outside the shell of the flash tank 1, and the atomizing effect of the atomizing device 9 is adjusted by the regulating valve to avoid poor atomization effect when the liquid ammonia flow rate is small. When the liquid ammonia flow rate is too small, the two atomizing devices 9 are stopped and only one atomizing device 9 is operated.

[0029] The atomizing device 9 is a combination structure in which a plurality of branch pipes are provided on a main pipe. A liquid ammonia inlet is provided on the upper main pipe of the atomizing device 9, and the liquid ammonia inlet is connected to the liquid ammonia inlet b6. A plurality of circular holes 11 are provided at the lower part of the branch pipe of the atomizing device 9, through which the liquid ammonia is sprayed out and atomized. A liquid level gauge is provided on the flash tank 1 to detect the liquid level in the flash tank 1 to prevent the liquid level from being too high to submerge the atomizing device 9 and thereby lose the atomizing effect.

[0030] When the device is in operation, liquid ammonia first enters the heat exchanger 2, and is cooled by the gaseous ammonia flashed out of the flash tank 1 in the heat exchanger 2. The liquid ammonia cooled in the heat exchanger 2 enters the flash tank 1, and is atomized and flashed by the atomizing device 9 in the flash tank 1. A part of the liquid ammonia is flashed and converted into gaseous ammonia, flows out of the flash tank 1 and enters the heat exchanger 2, and the other part of the liquid ammonia is cooled and collected in the flash tank 1; the gaseous ammonia is heated in the heat exchanger 2 and flows out of the heat exchanger 2; during operation, the liquid level in the flash tank 1 is controlled to be lower than the atomizing device 9.

[0031] Another embodiment differs from embodiment 3 in that: the heat exchanger 2 is a plate-type heat exchanger 2; the atomizing device 9 is a combination structure in which a plurality of branch pipes are arranged on a main pipe; a liquid ammonia inlet is provided on the upper main pipe of the atomizing device 9, and the liquid ammonia inlet is connected to the liquid ammonia inlet b6; a plurality of circular holes are provided at the lower part of the branch pipe of the atomizing device 9, and atomizing nozzles are provided on the plurality of circular holes, and the liquid ammonia is atomized through the atomizing nozzles.

[0032] The working principle of the present invention is as follows: in the flash tank 1 disclosed in the prior art, liquid ammonia enters the flash tank 1, and due to pressure reduction, the liquid ammonia flash vaporizes at the liquid ammonia surface and absorbs heat. The heat exchange between the liquid ammonia and the gaseous ammonia occurs at the liquid ammonia surface, and the flash vaporization refrigeration effect is poor. The present invention provides an atomizing device 9, so that the flashed gaseous ammonia and the atomized liquid ammonia are fully in contact with each other in the space above the liquid ammonia surface inside the flash tank 1 to exchange heat. Compared with the flash tank 1 disclosed in the prior art, the present invention has heat exchange between the liquid ammonia and the gaseous ammonia in the space above the liquid ammonia surface inside the flash tank 1, resulting in a larger heat exchange area and a better flash vaporization refrigeration effect, thereby efficiently reducing the temperature of the liquid ammonia. In addition, the present invention provides a heat exchanger 2, which uses the low-temperature gaseous ammonia vaporized by the flash vapor to cool the liquid ammonia, thereby effectively utilizing the cooling capacity in the gaseous ammonia and avoiding waste of cooling capacity in the gaseous ammonia.

[0033] Modifications and changes to the invention made by those familiar with the present invention are all within the patent scope of the present invention, and are not limited to those described in the embodiments.

Claims

1. A flash evaporation device for twice cooling liquid ammonia in a liquid ammonia refrigeration process, characterized by: The invention comprises a flash tank and a heat exchanger, wherein the heat exchanger is arranged above the flash tank and is provided with a liquid ammonia inlet a, a liquid ammonia outlet a, a gaseous ammonia inlet a, and a gaseous ammonia outlet a. The liquid ammonia inlet b of the flash tank is connected to the liquid ammonia outlet a of the heat exchanger, and the gaseous ammonia outlet b of the flash tank is connected to the gaseous ammonia inlet a of the heat exchanger; the liquid ammonia outlet b is provided at the bottom of the flash tank; a plurality of atomizing devices are provided inside the flash tank, and the plurality of atomizing devices are connected to the liquid ammonia inlet b of the flash tank through pipelines.

2. The flash evaporation device for twice cooling liquid ammonia in a liquid ammonia refrigeration process according to claim 1, characterized in that: A regulating valve is provided on the branch pipeline connecting the plurality of atomizing devices and the liquid ammonia inlet b, and the regulating valve is provided outside the flash tank shell.

3. The flash evaporation device for twice cooling liquid ammonia in a liquid ammonia refrigeration process according to claim 1, characterized in that: The atomizing device is a rectangular shell structure with a hollow interior, a cylindrical shell structure, or a combination structure in which a plurality of branch pipes are arranged on a main pipe; a liquid ammonia inlet is arranged on the upper shell of the atomizing device, the liquid ammonia inlet is connected to the liquid ammonia inlet b, and a plurality of circular holes are arranged on the lower shell of the atomizing device.

4. The flash evaporation device for twice cooling liquid ammonia in a liquid ammonia refrigeration process according to claim 1, characterized in that: A plurality of circular holes are arranged on the lower shell of the atomizing device, and atomizing nozzles are arranged on the plurality of circular holes.

5. The flash evaporation device for twice cooling liquid ammonia in a liquid ammonia refrigeration process according to any one of claims 1 to 4, characterized in that: The heat exchanger is a plate heat exchanger or a shell and tube heat exchanger.

6. The flash evaporation device for twice cooling liquid ammonia in a liquid ammonia refrigeration process according to any one of claims 1 to 4, characterized in that: A liquid level gauge is provided on the flash tank.

Images