Liquid nitrogen cryogenic oil gas recovery device for complex chemical production tail gas

Abstract

The utility model belongs to the technical field of waste gas treatment, and relates to a liquid nitrogen cryogenic oil gas recovery device for complex chemical production tail gas, which comprises a liquid separation tank, a primary spiral winding heat exchanger, a secondary spiral winding heat exchanger, a liquid nitrogen storage tank, a condensate tank and a tail gas emission unit, a tube pass outlet of the first-stage spiral winding heat exchanger is connected with a tube pass inlet of the second-stage spiral winding heat exchanger, a tube pass outlet of the first-stage spiral winding heat exchanger is connected with a shell pass inlet of the first-stage spiral winding heat exchanger, and a shell pass outlet of the first-stage spiral winding heat exchanger is connected with the tail gas emission unit; and liquid phase outlets of the first-stage spiral winding heat exchanger and the second-stage spiral winding heat exchanger are connected with a condensate tank. The method can be used for treating complex chemical tail gas, meets the national emission requirement, can turn waste into wealth, and has remarkable economic benefits and ecological benefits.

Description

Technical Field

[0001] The utility model belongs to the technical field of waste gas treatment, and relates to an oil and gas recovery device, in particular to a liquid nitrogen deep cooling oil and gas recovery device for the tail gas of complex chemical production. Background Art

[0002] During the process of liquid oil products in petrochemical and coal chemical industries being fed into storage tanks, when the liquid enters the storage tank, the liquid level in the tank rises, squeezing the space in the tank. When the space pressure exceeds the exhalation control pressure of the "breathing valve", VOCs gas is discharged into the atmospheric environment, that is, "big breathing". The waste gas generated by "big breathing" needs to be recovered and treated to meet the standards before being discharged. Moreover, there are many types of materials in the tank area, such as toluene, ethanol, xylene, dichloroethane, petroleum ether, dichloromethane, etc. In order to save the cost of tail gas treatment, chemical plants do not treat the tail gas separately, but collect it for centralized treatment. After unified collection, the composition of the tail gas is complex and becomes the tail gas of complex chemical production, which is not conducive to meeting the discharge standards. Therefore, it is usually necessary to carry out oil and gas recovery on the tail gas of complex chemical production.

[0003] The existing oil and gas recovery methods mainly include mechanical condensation method, catalytic combustion method, low-temperature solvent absorption method, etc. Among them, the mechanical condensation method has low treatment efficiency and high power consumption; the catalytic combustion method has high fuel and catalyst consumption and high operating costs, and cannot utilize the effective components in the waste gas, without economic benefits; the waste gas recovery rate of the low-temperature solvent absorption method is low, and a subsequent treatment process needs to be added, with high operating costs.

[0004] Therefore, in order to overcome the defects of the above-mentioned existing technologies, it is necessary to develop a new type of oil and gas recovery device for the tail gas of complex chemical production. Content of the Utility Model

[0005] The purpose of the utility model is to overcome the defects existing in the prior art, and provide a liquid nitrogen deep cooling oil and gas recovery device for the tail gas of complex chemical production. After the tail gas of complex chemical production is condensed by liquid nitrogen deep cooling and adsorbed by an activated carbon box, it can meet the national emission standard requirements, and most of the VOCs in the tail gas are condensed into liquid phase for recovery, turning waste into treasure; the treatment process is simple, energy-saving and environmentally friendly, with significant economic and ecological benefits; the treatment process isolates the outside air from entering the system, can realize the intrinsic safety of the device operation, and avoid the materials in the storage tank from being polluted.

[0006] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0007] A liquid nitrogen deep cooling oil and gas recovery device for the tail gas of complex chemical production, which includes a liquid separation tank, a first-stage spiral wound heat exchanger, a second-stage spiral wound heat exchanger, a liquid nitrogen storage tank, a condensate tank and a tail gas discharge unit. It is characterized in that the tail gas of complex chemical production enters the inlet of the liquid separation tank through a pipeline. The outlet of the liquid separation tank is connected to the tube-side inlet of the first-stage spiral wound heat exchanger through a pipeline. The tube-side outlet of the first-stage spiral wound heat exchanger is connected to the tube-side inlet of the second-stage spiral wound heat exchanger through a pipeline. The tube-side outlet of the second-stage spiral wound heat exchanger is connected to the shell-side inlet of the first-stage spiral wound heat exchanger through a pipeline. The shell-side outlet of the first-stage spiral wound heat exchanger is connected to the tail gas discharge unit through a pipeline. The outlet of the liquid nitrogen storage tank is connected to the shell-side inlet of the second-stage spiral wound heat exchanger through a pipeline. The liquid-phase outlets of the first-stage spiral wound heat exchanger and the second-stage spiral wound heat exchanger are connected to the inlet of the condensate tank through a pipeline.

[0008] Preferably, the liquid nitrogen deep cooling oil and gas recovery device for the tail gas of complex chemical production includes multiple groups of the first-stage spiral wound heat exchangers, multiple groups of the second-stage spiral wound heat exchangers and an electric heater. The shell-side outlet of each group of the second-stage spiral wound heat exchangers is connected to the electric heater through a pipeline.

[0009] Preferably, the tube-side outlet of one group of the second-stage spiral wound heat exchangers is also connected to the tube-side inlet of another group of the first-stage spiral wound heat exchangers through a pipeline.

[0010] Preferably, the shell-side inlet of each group of the second-stage spiral wound heat exchangers is also connected to a nitrogen pipeline network through a pipeline.

[0011] Preferably, the tail gas discharge unit includes a booster fan, an activated carbon box and an exhaust stack. The shell-side outlet of each group of the first-stage spiral wound heat exchangers is connected to the inlet of the booster fan through a pipeline. The outlet of the booster fan is connected to the inlet of the activated carbon box through a pipeline. The outlet of the activated carbon box is connected to the inlet of the exhaust stack through a pipeline.

[0012] Compared with the prior art, the liquid nitrogen deep cooling oil and gas recovery device for the tail gas of complex chemical production of the present utility model has one or more of the following beneficial technical effects:

[0013] 1. The liquid nitrogen deep cooling oil and gas recovery device for the tail gas of chemical production of the present utility model condenses the tail gas of complex chemical production after deep cooling with liquid nitrogen, and an activated carbon box is set as an adsorption device, meeting the waste gas emission standard and recovering most of the VOCs from the gas phase to the liquid phase.

[0014] 2. The treatment process of the liquid nitrogen deep cooling oil and gas recovery device for chemical production tail gas of the present utility model is simple, energy-saving and environmentally friendly, with significant economic and ecological benefits. The treatment process isolates the outside air from entering the storage tank, realizes the intrinsic safety of the device operation, and avoids the pollution of the materials in the storage tank.

[0015] 3. When at least two groups of heat exchangers are provided in the liquid nitrogen deep cooling oil and gas recovery device for chemical production tail gas of the present utility model, the heat exchangers of each group can operate alternately, effectively solving the problem of ice blockage. Moreover, during defrosting, the tail gas can preferentially enter the tube side of the heat exchanger with ice blockage, and defrosting is carried out through the heat carried by the tail gas, which can reduce the waste gas temperature and the consumption of liquid nitrogen. At the same time, the nitrogen gas generated by the operating heat exchanger is heated by the electric heater and then enters the shell side of the heat exchanger with ice blockage for defrosting. The shell side and the tube side are defrosted simultaneously, reducing the ice blockage time.

[0016] 4. The waste gas at the tube side outlet of the secondary spiral wound heat exchanger in the liquid nitrogen deep cooling oil and gas recovery device for chemical production tail gas of the present utility model can be recycled back to the primary spiral wound heat exchanger for cold quantity recovery and utilization.

[0017] 5. The liquid nitrogen deep cooling oil and gas recovery device for chemical production tail gas of the present utility model uses liquid nitrogen to provide cold quantity for the tail gas, and the generated nitrogen gas can enter the nitrogen pipeline network, which has functions such as nitrogen sealing and anti-oxidation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic structural diagram of the liquid nitrogen deep cooling oil and gas recovery device for complex chemical production tail gas of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] In order to make the objectives, technical solutions and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. Usually, the components of the embodiments of the present utility model described and illustrated herein can be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the present utility model provided in the drawings is not intended to limit the scope of the claimed present utility model, but merely represents selected embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0021] Figure 1 shows a schematic structural diagram of the liquid nitrogen deep cooling oil and gas recovery device for complex chemical production tail gas of the present utility model. As Figure 1As shown in the figure, the liquid nitrogen deep cooling oil and gas recovery device for the tail gas of complex chemical production of the present utility model includes a liquid separation tank 1, a heat exchanger, a liquid nitrogen storage tank 4, a condensate tank 5 and a tail gas discharge unit. Among them, the heat exchanger includes a first-stage spiral wound heat exchanger and a second-stage spiral wound heat exchanger.

[0022] The tail gas of complex chemical production enters the inlet of the liquid separation tank 1 through a pipeline. The outlet of the liquid separation tank 1 is connected to the tube side inlet of the first-stage spiral wound heat exchanger through a pipeline. The tube side outlet of the first-stage spiral wound heat exchanger is connected to the tube side inlet of the second-stage spiral wound heat exchanger through a pipeline. The tube side outlet of the second-stage spiral wound heat exchanger is connected to the shell side inlet of the first-stage spiral wound heat exchanger through a pipeline. The shell side outlet of the first-stage spiral wound heat exchanger is connected to the tail gas discharge unit through a pipeline. The outlet of the liquid nitrogen storage tank 4 is connected to the shell side inlet of the second-stage spiral wound heat exchanger through a pipeline. The liquid phase outlets of the first-stage spiral wound heat exchanger and the second-stage spiral wound heat exchanger are connected to the inlet of the condensate tank 5 through a pipeline.

[0023] The liquid nitrogen storage tank 4 is used to provide the cooling capacity required for tail gas recovery. After the tail gas of complex chemical production is introduced into the liquid separation tank 1 for buffering, it enters the tube side of the first-stage spiral wound heat exchanger and is condensed by the cryogenic waste gas generated by the second-stage spiral wound heat exchanger. The condensed liquid phase enters the condensate tank 5, and the gas phase enters the tube side of the second-stage spiral wound heat exchanger and is condensed by the liquid nitrogen from the liquid nitrogen storage tank 4. The condensed liquid phase enters the condensate tank 5, and the gas phase enters the shell side of the first-stage spiral wound heat exchanger to facilitate the condensation of the tail gas of complex chemical production in the tube side of the first-stage spiral wound heat exchanger. The waste gas at the shell side outlet of the first-stage spiral wound heat exchanger enters the tail gas discharge unit and is discharged to the outside.

[0024] Thus, the treatment process of the liquid nitrogen deep cooling oil and gas recovery device for the tail gas of chemical production of the present utility model is simple, energy-saving and environmentally friendly, with significant economic and ecological benefits. The treatment process isolates the outside air from entering the storage tank, realizes the inherent safety of the device operation, and avoids the pollution of the materials in the storage tank.

[0025] In the present utility model, preferably, it includes multiple groups of heat exchangers and an electric heater 6. Each group of the heat exchangers includes a first-stage spiral wound heat exchanger and a second-stage spiral wound heat exchanger. The shell side outlet of each group of the second-stage spiral wound heat exchangers is connected to the electric heater 6 through a pipeline.

[0026] In Figure 1In the illustrated example, it includes two groups of heat exchangers. The first group of heat exchangers includes a first-stage spiral wound heat exchanger 2-1 and a second-stage spiral wound heat exchanger 3-1. The second group of heat exchangers includes a second-stage spiral wound heat exchanger 2-2 and a second-stage spiral wound heat exchanger 3-2. At the same time, the shell-side outlets of the first second-stage spiral wound heat exchanger 3-1 and the second second-stage spiral wound heat exchanger 3-2 are both connected to the electric heater 6 through pipelines.

[0027] Thus, when at least two groups of heat exchangers are provided in the liquid nitrogen deep cooling oil and gas recovery device for chemical production tail gas of the present utility model, the heat exchangers of each group can operate alternately, effectively solving the problem of ice blockage. Moreover, during defrosting, the tail gas preferentially enters the tube side of the group of heat exchangers with ice blockage, and defrosting is carried out by the heat carried by the tail gas itself, which can reduce the tail gas temperature and the consumption of liquid nitrogen. At the same time, the nitrogen gas generated by the operating group of heat exchangers enters the shell side of the heat exchanger with ice blockage after being heated by the electric heater for defrosting, and defrosting is carried out simultaneously on the shell side and the tube side, reducing the ice blockage time.

[0028] Furthermore, in the present utility model, preferably, the tube-side outlet of one group of the second-stage spiral wound heat exchangers is also connected to the tube-side inlet of the other group of the first-stage spiral wound heat exchangers through a pipeline. For example, the tube-side outlet of the first second-stage spiral wound heat exchanger 3-1 is also connected to the tube-side inlet of the second first-stage spiral wound heat exchanger 2-2 through a pipeline, and the tube-side outlet of the second second-stage spiral wound heat exchanger 3-2 is also connected to the tube-side inlet of the first first-stage spiral wound heat exchanger 2-1 through a pipeline.

[0029] Thus, the waste gas at the tube-side outlet of the second-stage spiral wound heat exchanger in the liquid nitrogen deep cooling oil and gas recovery device for chemical production tail gas of the present utility model can be recycled back to the first-stage spiral wound heat exchanger for cold quantity recovery and utilization.

[0030] In addition, in the present utility model, the shell-side inlet of each group of the second-stage spiral wound heat exchangers is also connected to the nitrogen pipeline network through a pipeline. For example, the shell-side inlets of the first second-stage spiral wound heat exchanger 3-1 and the second second-stage spiral wound heat exchanger 3-2 are also connected to the nitrogen pipeline network through a pipeline.

[0031] Thus, the liquid nitrogen deep cooling oil and gas recovery device for chemical production tail gas of the present utility model uses liquid nitrogen to provide cold quantity for the tail gas, and the generated nitrogen gas can enter the nitrogen pipeline network, which has uses such as nitrogen sealing and anti-oxidation.

[0032] Finally, in the present utility model, the tail gas emission unit includes a booster fan 7, an activated carbon box 8, and an exhaust stack 9. The shell-side outlet of each group of the first-stage spiral wound heat exchanger is connected to the inlet of the booster fan 7 through a pipeline, the outlet of the booster fan 7 is connected to the inlet of the activated carbon box 8 through a pipeline, and the outlet of the activated carbon box 8 is connected to the inlet of the exhaust stack 9 through a pipeline. By providing the booster fan 7, it is convenient for the tail gas to pass through the activated carbon box 8. The activated carbon box 8 is used for filtering the tail gas. The exhaust stack 9 is used for discharging the tail gas.

[0033] Thus, the liquid nitrogen cryogenic oil and gas recovery device for chemical production tail gas of the present utility model condenses the complex chemical production tail gas by liquid nitrogen cryogenic cooling, and an activated carbon box is provided as an adsorption device to meet the waste gas emission standards, and most of the VOCs can be recovered from the gas phase to the liquid phase by condensation.

[0034] In the present utility model, the temperature of the gas phase outlet of the tube side of the first-stage spiral wound heat exchanger is preferably 0°C to 5°C, which can reduce the possibility of ice blockage; the temperature of the gas phase outlet of the tube side of the second-stage spiral wound heat exchanger is preferably -95 to -110°C, which can ensure the up-to-standard discharge of the outlet waste gas.

[0035] At the same time, in the present utility model, the temperature of the gas phase outlet of the shell side of the second-stage spiral wound heat exchanger is preferably -20 to 0°C, which can ensure the full utilization of the liquid nitrogen cooling capacity; the temperature of the gas phase outlet of the shell side of the first-stage spiral wound heat exchanger is preferably -20 to 0°C, which can ensure the full recovery and utilization of the waste gas cooling capacity.

[0036] The following further illustrates the present utility model in combination with specific application examples:

[0037] The tail gas produced in the tank area of a certain chemical plant is complex in composition, including toluene, ethanol, methanol, ammonia water, ethyl acetate, hydroxyethyl methacrylate, diketene, xylene, dichloroethane, petroleum ether, dichloromethane, dimethyl phthalate, tetrahydrofuran, waste solvent, etc. The tail gas temperature is 0 - 50°C and the pressure is atmospheric pressure. The treatment process is as follows:

[0038] After the tail gas from the tank area is introduced into the separation tank 1 for buffering, the tail gas enters the tube side of the first-stage spiral wound heat exchanger and is condensed by the cryogenic tail gas generated by the second-stage spiral wound heat exchanger. The condensed liquid phase enters the condensate tank 5, and the gas phase enters the tube side of the second-stage spiral wound heat exchanger.

[0039] The gas phase generated by the first-stage spiral wound heat exchanger enters the tube side of the second-stage spiral wound heat exchanger and is condensed by the liquid nitrogen from the liquid nitrogen storage tank 4. The condensed liquid phase enters the condensate tank 5, and the gas phase enters the shell side of the first-stage spiral wound heat exchanger to condense the tail gas in the tube side of the first-stage spiral wound heat exchanger.

[0040] The waste gas at the shell side outlet of the primary spiral wound heat exchanger enters the tail gas emission unit, passes through the booster fan 7 and then enters the activated carbon box 8 to further treat the waste gas, and is discharged through the exhaust stack 9 after ensuring that the waste gas meets the standards.

[0041] During operation, when ice blockage occurs in a group of heat exchangers, the treatment process is as follows:

[0042] The tail gas from chemical production is introduced into the separation tank 1 for buffering, and then the tail gas passes through the tube side of the ice-blocked primary spiral wound heat exchanger and the tube side of the secondary spiral wound heat exchanger, and enters a group of normally operating heat exchangers for the above process. At the same time, the nitrogen gas generated after the vaporization of liquid nitrogen enters the shell side of the ice-blocked primary spiral wound heat exchanger and the shell side of the secondary spiral wound heat exchanger after being heated by the electric heater 6, and then enters the nitrogen gas pipeline.

[0043] After heat exchange in the primary spiral wound heat exchanger, the temperature of the tail gas drops to 2.7 °C. After condensation heat exchange, part of the gas phase condenses into liquid and flows into the condensate tank 5 by gravity. After heat exchange in the secondary spiral heat exchanger, the temperature of the tail gas drops to -96 °C. After condensation heat exchange, part of the gas phase condenses into liquid and flows into the condensate tank 5 by gravity. The waste gas enters the tail gas emission unit after heat exchange in two-stage heat exchangers, and the VOC emission value after deep cooling is ≤ 60 mg / m 3 , meeting the emission requirements.

[0044] The above embodiments of the present invention are merely examples for clearly explaining the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation manners here. Any obvious changes or modifications derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. A liquid nitrogen deep cryogenic oil and gas recovery device for the tail gas of complex chemical production, which comprises a liquid separation tank (1), a first-stage spiral wound heat exchanger (2-1, 2-2), a second-stage spiral wound heat exchanger (3-1, 3-2), a liquid nitrogen storage tank (4), a condensate tank (5) and a tail gas discharge unit, and is characterized in that, The tail gas from complex chemical production enters the inlet of the liquid separation tank (1) through a pipeline. The outlet of the liquid separation tank (1) is connected to the tube side inlet of the first-stage spiral wound heat exchanger (2-1, 2-2) through a pipeline. The tube side outlet of the first-stage spiral wound heat exchanger (2-1, 2-2) is connected to the tube side inlet of the second-stage spiral wound heat exchanger (3-1, 3-2) through a pipeline. The tube side outlet of the second-stage spiral wound heat exchanger (3-1, 3-2) is connected to the shell side inlet of the first-stage spiral wound heat exchanger (2-1, 2-2) through a pipeline. The shell side outlet of the first-stage spiral wound heat exchanger (2-1, 2-2) is connected to the tail gas discharge unit through a pipeline. The outlet of the liquid nitrogen storage tank (4) is connected to the shell side inlet of the second-stage spiral wound heat exchanger (3-1, 3-2) through a pipeline. The liquid phase outlets of the first-stage spiral wound heat exchanger (2-1, 2-2) and the second-stage spiral wound heat exchanger (3-1, 3-2) are connected to the inlet of the condensate tank (5) through a pipeline.

2. The nitrogen liquefaction cryogenic oil and gas recovery device for the tail gas of complex chemical production according to claim 1, wherein, It includes multiple groups of the first-stage spiral wound heat exchangers (2-1, 2-2), multiple groups of the second-stage spiral wound heat exchangers (3-1, 3-2) and an electric heater (6). The shell side outlet of each group of the second-stage spiral wound heat exchangers (3-1, 3-2) is connected to the electric heater (6) through a pipeline.

3. The nitrogen liquefaction cryogenic oil and gas recovery device for the tail gas of complex chemical production according to claim 2, characterized in that, The tube side outlet of one group of the second-stage spiral wound heat exchangers (3-1, 3-2) is also connected to the tube side inlet of another group of the first-stage spiral wound heat exchangers (2-1, 2-2) through a pipeline.

4. The nitrogen liquid cryogenic oil and gas recovery device for the tail gas of complex chemical production according to claim 3, characterized in that, The shell side inlet of each group of the second-stage spiral wound heat exchangers (3-1, 3-2) is also connected to the nitrogen pipeline network through a pipeline.

5. The nitrogen liquefaction cryogenic oil and gas recovery device for the tail gas of complex chemical production according to claim 4, characterized in that, The tail gas discharge unit includes a booster fan (7), an activated carbon box (8) and an exhaust stack (9). The shell side outlet of each group of the first-stage spiral wound heat exchangers (2-1, 2-2) is connected to the inlet of the booster fan (7) through a pipeline. The outlet of the booster fan (7) is connected to the inlet of the activated carbon box (8) through a pipeline. The outlet of the activated carbon box (8) is connected to the inlet of the exhaust stack (9) through a pipeline.

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