Falling film evaporator heat recovery device in adipic acid production process

Abstract

The utility model discloses a falling film evaporator heat recovery device in the adipic acid production process. The falling film evaporator heat recovery device comprises a falling film evaporator, a flash tank and the like. The high-pressure steam is condensed into a steam-water mixture after the materials are heated by the falling-film evaporator, the liquid is sent to a steam condensate storage tank after the steam-water mixture is separated by the flash tank, and the gas is sent to an inlet of the falling-film evaporator for recycling. Heat of high-pressure steam is fully utilized, and steam consumption in production is reduced; the flash tank is used for replacing a steam trap, and material consumption caused by frequent damage of the steam trap is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to a falling film evaporator heat recovery device, concretely relates to a falling film evaporator heat recovery device in adipic acid production process. TECHNICAL BACKGROUND

[0002] At present, the adipic acid production process at home and abroad mainly is nitric acid oxidation KA oil process, and it has the advantages of high reaction efficiency, good selectivity and high product yield. In the oxidation process of KA oil, under the action of catalyst, nitric acid is used as oxidant to produce adipic acid. In order to make the production stable, easy to control, reduce the side reaction and improve the yield of adipic acid, usually excessive nitric acid is added, so there is a certain proportion of nitric acid solution in adipic acid waste liquid. In order to recover nitric acid in adipic acid waste liquid, falling film evaporator is used. High pressure steam is consumed in the process of recovering nitric acid by falling film evaporator, but the temperature of high pressure steam condensate is very high, and the pressure is high. Direct discharge exists safety hazard, waste heat energy, and the impact on the trap is large, which leads to frequent replacement of the trap. Therefore, in the production concept of safety, consumption reduction and energy saving, there is still optimization space in the process of recovering nitric acid by falling film evaporator. SUMMARY

[0003] The utility model aims at providing a kind of heat recovery device in adipic acid falling film evaporation process, realize heat reuse in falling film evaporation process, reduce energy consumption cost, and then reduce adipic acid production cost.

[0004] To solve the above technical problems in production process, the technical route adopted by the utility model is as follows:

[0005] A kind of falling film evaporator heat recovery device in adipic acid production process, including falling film evaporator and flash tank, the steam inlet of falling film evaporator is connected with high pressure steam pipeline, the condensate outlet of falling film evaporator is equipped with two branches, a branch is equipped with trap, the outlet of trap is connected with steam condensate storage tank by pipeline, another branch is connected with the inlet of flash tank, flash tank is equipped with steam outlet and liquid outlet, steam outlet is connected with the steam inlet of falling film evaporator by pipeline and gas phase valve on the pipeline.

[0006] Further, the liquid outlet of flash tank is connected with steam condensate storage tank by pipeline and liquid level regulating valve on the pipeline, liquid level meter is arranged on flash tank, liquid level regulating valve and liquid level meter are connected according to single loop control, so that the opening of liquid level regulating valve is controlled by the liquid level data of liquid level meter. The power of liquid level delivery of flash tank is provided by the pressure in the tank.

[0007] Further, steam regulating valve is arranged on high pressure steam pipeline, pressure gauge is arranged on the shell side of falling film evaporator, steam regulating valve and pressure gauge are connected according to single loop control, so that the opening of steam regulating valve is controlled by the pressure data of pressure gauge.

[0008] Further, the falling film evaporator is provided with a distributor, so that the entering material is uniformly distributed and flows downward.

[0009] Further, the trap is a double valve group trap, and is provided with a trap bypass.

[0010] Further, the liquid level regulating valve is provided with a bypass.

[0011] Further, the falling film evaporator is provided with a tail gas outlet, and the tail gas outlet is connected with a nitrous gas absorption system through a pipeline.

[0012] The use process of the utility model is as follows: during the evaporation process of the falling film evaporator, nitric acid vapor goes to the nitrous gas absorption system, and after recovery, the nitric acid is reused. After the high-pressure steam is condensed through the falling film evaporator, the high-temperature steam condensate is discharged after separation through the flash tank and is sent to the condensate system. The gas phase of the flash tank is reused to the steam inlet of the falling film evaporator. When the device is started, the steam provides conveying power.

[0013] The utility model has the advantages of:

[0014] (1) The steam condensate of the falling film evaporator needs to be separated by the trap, and the flash tank is used to replace the trap, so that the loss caused by the impact of high-pressure steam on the trap is reduced.

[0015] (2) The gas phase of the flash tank has high temperature and high pressure, and the gas phase is connected with the steam inlet of the falling film evaporator for reuse, so that the use amount of high-pressure steam is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a structural schematic view of the utility model,

[0017] The symbols and equipment diagrams in the figure are as follows: 1. falling film evaporator, 2. flash tank, 3. steam regulating valve, 4. pressure gauge, 5. liquid level meter, 6. liquid level regulating valve, 7. trap, 8. gas phase valve, 9. trap bypass, 10. bypass. DETAILED DESCRIPTION

[0018] The utility model will be further explained and described in combination with specific examples, but the protection scope of the utility model is not limited.

[0019] A falling film evaporator heat recovery device in adipic acid production process, like Figure 1As shown, including falling film evaporator 1 and flash tank 2, falling film evaporator 1 steam inlet and high pressure steam pipe connection, falling film evaporator 1 condensate outlet is provided with two branches, one branch is provided with trap 7, the outlet of trap 7 is connected with steam condensate tank through pipeline, the other branch is connected with the inlet of flash tank 2, flash tank 2 is provided with steam outlet and liquid outlet, the steam outlet is connected with the steam inlet of falling film evaporator 1 through pipeline and gas phase valve 8 arranged on the pipeline, the liquid outlet is connected with steam condensate tank through pipeline and liquid level regulating valve 6 arranged on the pipeline, the liquid level meter 5 is arranged on the flash tank 2, the liquid level regulating valve 6 and the liquid level meter 5 are connected in single loop control so as to control the opening of the liquid level regulating valve 6 according to the liquid level data of the liquid level meter 5. The steam regulating valve 3 is arranged on the high pressure steam pipeline, the pressure gauge 4 is arranged on the shell side of the falling film evaporator 1, and the steam regulating valve 3 and the pressure gauge 4 are connected in single loop control so as to control the opening of the steam regulating valve 3 according to the pressure data of the pressure gauge 4.

[0020] The high pressure steam of the falling film evaporator 1 passes through the steam regulating valve 3, exchanges heat with the adipic acid material in the downstream mode, passes through the flash tank 2, adjusts the liquid level in the flash tank 2 through the pressure difference mode and uses the liquid level regulating valve 6, and then is sent to the condensate tank. The gas in the flash tank 2 is sent to the steam inlet of the falling film evaporator 1 through the gas phase valve 8 to reuse the heat of the flash tank 2. When the flash tank 2 has a problem, the trap 7 is used to send the condensate water of the falling film evaporator 1 to the condensate tank.

[0021] In this embodiment, the liquid level regulating valve 6 is provided with a bypass 10, and the bypass 10 is provided with a valve.

[0022] In this embodiment, the falling film evaporator 1 is provided with an overflow distributor device with a height of 10 cm on each tube of the top tube side.

[0023] In this embodiment, the steam regulating valve 3 and the pressure gauge 4 form a single loop control, and a root valve is arranged at the pressure gauge 4;

[0024] In this embodiment, the liquid level regulating valve 6 and the liquid level meter 5 form a single loop control, and a root valve is arranged at the liquid level meter 5;

[0025] In this embodiment, the trap 7 is a double valve group trap, and a trap bypass 9 is arranged therein.

[0026] In this embodiment, a switch valve is arranged on the high pressure steam pipeline, valves are arranged on the pipelines before and after the trap 7 and on the pipelines before and after the liquid level regulating valve 6. A valve is arranged on the inlet pipeline of the flash tank 2.

[0027] In this embodiment, the flash tank 2 and the trap 7 can be switched for use.

[0028] According to the process design, the heat source of the falling film evaporator 1 is high-pressure steam, and the condensed liquid is sent to the condensed liquid storage tank after being flashed from the flash tank 2, which reduces the frequent damage and replacement of the drain trap 7 due to the impact of the high-pressure steam condensed liquid, and the large amount of heat in the gas phase of the flash tank 2 can be reused to reduce the daily consumption of high-pressure steam by about 5%, thereby further saving the production cost of adipic acid.

[0029] The above examples are only used to illustrate the technical solutions of the present application, and those skilled in the art should understand that the technical solutions of the present patent can be modified and equivalently replaced without departing from the purpose and scope of the present patent, and they should be covered in the scope of the claims of the present patent.

Claims

1. A heat recovery device for a falling film evaporator in the adipic acid production process, characterized in that, It includes a falling film evaporator and a flash tank. The steam inlet of the falling film evaporator is connected to a high-pressure steam pipeline. The condensate outlet of the falling film evaporator has two branches. One branch is equipped with a steam trap, and the outlet of the steam trap is connected to a steam condensate storage tank through a pipeline. The other branch is connected to the inlet of the flash tank. The flash tank has a steam outlet and a liquid outlet. The steam outlet is connected to the steam inlet of the falling film evaporator through a pipeline and a vapor phase valve installed on the pipeline.

2. The heat recovery device for falling film evaporator in the adipic acid production process according to claim 1, characterized in that, The liquid outlet of the flash tank is connected to the steam condensate storage tank via a pipeline and a level regulating valve installed on the pipeline. The flash tank is equipped with a level gauge, and the level regulating valve and the level gauge are connected in a single-loop control manner so that the opening degree of the level regulating valve is controlled by the level data of the level gauge.

3. The heat recovery device for falling film evaporator in the adipic acid production process according to claim 1, characterized in that, A steam regulating valve is installed on the high-pressure steam pipeline, and a pressure gauge is installed on the shell side of the falling film evaporator. The steam regulating valve and the pressure gauge are connected in a single-loop control manner, so that the opening degree of the steam regulating valve is controlled by the pressure data of the pressure gauge.

4. The heat recovery device for falling film evaporator in the adipic acid production process according to claim 1, characterized in that, The falling film evaporator is equipped with a distributor to ensure that the incoming material is evenly distributed and flows downwards.

5. The falling film evaporator heat recovery device in the adipic acid production process according to claim 1, characterized in that, The steam trap is a dual-valve steam trap and is equipped with a steam trap bypass.

6. The heat recovery device for the falling film evaporator in the adipic acid production process according to claim 2, characterized in that, The level control valve is equipped with a bypass.

7. The falling film evaporator heat recovery device in the adipic acid production process according to claim 1, characterized in that, The falling film evaporator has a tail gas outlet at the top, which is connected to the nitrite absorption system via a pipeline.

Images