Method for recovering high condensation point waste gas

Abstract

A high-freezing point waste gas recovery device, characterized in that it includes a heat exchanger, a waste oil tank, an alkali washing tower and a fan, wherein the top of the heat exchanger is provided with a waste gas inlet pipe and the bottom is provided with a discharge pipe; the feed end of the waste oil tank is connected to the discharge end of the aforementioned discharge pipe, and the top of the waste oil tank is provided with a waste gas outlet; the middle or bottom of the alkali washing tower is provided with a waste gas inlet, the top is provided with an exhaust port, the upper part is provided with an alkali liquid inlet, and the lower part is provided with an alkali liquid outlet; the air inlet end of the combustion equipment is connected with the exhaust port of the aforementioned alkali washing tower. The present invention also discloses a high-freezing point waste gas recovery method. By adopting the treatment of cooling, alkali liquid absorption and combustion, C5 and C5+ components are finally condensed and collected in the waste oil tank, and C4 and lower light components are then sent to the combustion equipment to complete the combustion, with high processing efficiency and reliable emission, and the overall equipment is simple and easy to maintain, and the relatively low processing cost.

Description

Technical Field

[0001] The present invention relates to a waste gas treatment device, in particular to a high-freezing point waste gas recovery device and a high-freezing point waste gas recovery method. Background Art

[0002] Since the 1980s, China has started to carry out research and development and technology introduction in the field of oil and gas recovery in an organized manner, and has achieved certain results. However, most oil and gas processing technologies and processing facilities are mainly for light oil and gas processing. With the increasingly stringent environmental protection requirements and the increasing amount of crude oil imports, the treatment and recovery of high-freezing point waste gas has also received more and more attention.

[0003] As we all know, the oil and gas components of high-freezing-point waste gas such as asphalt are complex, including carbocyclic hydrocarbons, cyclic hydrocarbon derivatives and other compounds, such as benzopyrene, benzanthracene, carbazole, dibenzofuran, phenanthridine, etc. Therefore, it is necessary to treat it before discharging it into the atmosphere.

[0004] The commonly used oil and gas treatment methods are mainly the following or their combinations: 1. Condensation method. 2. Absorption method. 3. Adsorption method. 4. Membrane separation method. 5. Combustion method.

[0005] The traditional condensation absorption treatment method requires cooling the high-freezing-point exhaust gas to -130°C to completely condense the C2 and above components in the high-freezing-point exhaust gas. This method is very expensive, and for high-freezing-point exhaust gas, there is a risk of heavy components in the oil and gas condensing and clogging the condenser during the condensation process.

[0006] When the membrane separation method is used for high-freezing-point exhaust gas, the gelatinous oil in the oil and gas may adhere to the separation membrane, affecting the separation effect.

[0007] The method of direct adsorption of high-freezing-point exhaust gas will cause the adsorbent in the adsorption tank to be quickly saturated due to the formation of a gelatinous condensate in the condensed oil, making desorption difficult. Summary of the invention

[0008] The first technical problem to be solved by the present invention is to provide a high-freezing point waste gas recovery device with low cost and meeting environmental protection requirements after waste gas treatment in view of the above-mentioned technical status quo.

[0009] The second technical problem to be solved by the present invention is to provide a method for recovering high-freezing-point waste gas with low cost and meeting environmental protection requirements after waste gas treatment in response to the above-mentioned technical status quo.

[0010] The technical solution adopted by the present invention to solve the above-mentioned first technical problem is: a high-freezing point waste gas recovery device, characterized in that it includes

[0011] A heat exchanger having an exhaust gas inlet pipe at the top end, a discharge pipe at the bottom end, and a first tube layer capable of accommodating cooling water;

[0012] A waste oil tank, the feed end of which is connected to the discharge end of the discharge pipe, and the top of which is provided with a waste gas outlet;

[0013] The alkali washing tower has an exhaust gas inlet in the middle or at the bottom, an exhaust port at the top, an alkali liquid inlet at the top, and an alkali liquid outlet at the bottom;

[0014] A fan to transport the waste gas from the slop tank to the caustic scrubber; and

[0015] The combustion equipment has an air inlet end connected to the exhaust port of the aforementioned alkali washing tower.

[0016] The exhaust gas inlet pipe is sheathed with a steam heating pipe and a heat preservation layer. The heat preservation layer is arranged on the outer periphery of the steam heating pipe, and the steam heating pipe can ensure that the exhaust gas inlet pipe maintains a certain temperature, and can effectively prevent the heavy components from condensing in the pipeline during the oil and gas transportation process.

[0017] Furthermore, a liquid level sensor is provided in the waste oil tank, and a valve linked to the liquid level sensor is provided on the exhaust gas intake pipe.

[0018] Furthermore, the first tube layer is also connected to the first steam inlet pipe and the first condensate outflow pipe. Because the high-condensation point exhaust gas components are complex, such as asphalt, colloidal dirty oil will adhere to the inner wall of the cooler shell and the outer wall of the tube layer, affecting the heat exchange effect. The heat exchange effect is judged by monitoring the temperature at the heat exchanger outlet. When the heat exchange effect decreases significantly, the circulating cooling water of the first tube layer and the jacket layer is discharged, and steam is introduced to liquefy the attached colloidal dirty oil by heating and collect it in the dirty oil tank.

[0019] The waste oil tank has a second pipe layer, which is connected to a second steam inlet pipe and a second condensate outlet pipe. The bottom of the waste oil tank is connected to a condensate outlet pipe. Steam is introduced into the pipe layer or the jacket for heating to increase the temperature of the condensate and the fluidity of the condensate. The condensate is transported to the waste oil tank area of ​​the refinery for recycling through the waste oil pump and the condensate outlet pipe.

[0020] The technical solution adopted by the present invention to solve the above second technical problem is: a recovery method using a high freezing point waste gas recovery device, characterized in that it includes the following steps:

[0021] The high-freezing-point exhaust gas is insulated and heated to maintain 130℃ and enters the first shell of the heat exchanger from the exhaust gas inlet pipe. The heat exchanger cools the high-freezing-point exhaust gas in the first shell to 35℃, and the C5 and C5+ components in the oil and gas are condensed and collected in the waste oil tank; the high-freezing-point exhaust gas with heavy components removed enters the alkali washing tower through the fan, and the acidic components in the oil and gas are removed by alkali liquid. The treated oil and gas mainly contains C4 and below light components and is then sent to the combustion equipment and finally discharged after combustion.

[0022] Compared with the prior art, the advantages of the present invention are: through cooling, alkaline solution absorption and combustion treatment, C5 and C5+ components are finally condensed and collected in the waste oil tank, and C4 and lower light components are then sent to the combustion equipment to complete the combustion, with high treatment efficiency and reliable emissions, the overall equipment is simple and easy to maintain, and the relatively low treatment cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the structure of an embodiment. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below with reference to the accompanying drawings.

[0025] like Figure 1 As shown, the high freezing point waste gas recovery device in this embodiment includes a heat exchanger 1, a waste oil tank 2, an alkali washing tower 3, a fan 6 and a combustion device 4.

[0026] The heat exchanger 1 has an exhaust gas inlet pipe 5 at the top, a discharge pipe 14 at the bottom, and a first tube layer 12 that can accommodate cooling water; the exhaust gas inlet pipe 5 in this embodiment is sheathed with a steam tracing pipe 51 and an insulation layer, and the insulation layer is located on the outer periphery of the steam tracing pipe 51 (not shown in the figure). The steam tracing pipe 51 can ensure that the exhaust gas inlet pipe 5 maintains a constant temperature of 130°C, which can effectively prevent the heavy components from condensing in the pipeline during the oil and gas transportation process. The first tube layer 12 in this embodiment is connected to a circulating water inlet pipe 17 and a circulating water outlet pipe 18.

[0027] The heat exchanger 1 also has a jacket layer 13. The first tube layer 12 is also connected to a first steam inlet pipe 15 and a first condensate outlet pipe 16. Because the high-condensation point exhaust gas components are complex, such as asphalt, colloidal dirty oil will adhere to the inner wall of the cooler shell and the outer wall of the tube layer, affecting the heat exchange effect. The heat exchange effect is judged by monitoring the temperature at the heat exchanger outlet. When the heat exchange effect decreases significantly, the circulating cooling water of the first tube layer and the jacket layer is discharged, and steam is introduced to liquefy the attached colloidal dirty oil by heating and collect it in the dirty oil tank.

[0028] The feed end of the waste oil tank 2 is connected to the discharge end of the discharge pipe 14, and a waste gas outlet is provided at the top of the waste oil tank 2; a liquid level sensor 22 is provided in the waste oil tank 2, and a valve 23 linked to the liquid level sensor 22 is provided on the waste gas inlet pipe 5. As the liquid level of the condensed oil rises to the set value, the valve 23 is automatically interlocked and closed, thereby closing the discharge pipe 14.

[0029] The waste oil tank 2 has a second pipe layer 21, which is connected to a second steam inlet pipe 211 and a second condensate outlet pipe 212. The bottom of the waste oil tank 2 is connected to a condensate outlet pipe 22. Steam is introduced into the second pipe layer 21 for heating, so as to increase the temperature of the condensate and the fluidity of the condensate. The condensate is then transported to the waste oil tank area of ​​the refinery for recycling through the waste oil pump and the condensate outlet pipe. Of course, the waste oil tank 2 in this embodiment may also have a jacket layer, in which steam is passed.

[0030] The alkali washing tower 3 has an exhaust gas inlet at the middle and lower part, an exhaust port at the top, an alkali liquid inlet at the upper part, and an alkali liquid outlet at the lower part. The alkali liquid inlet is connected to the liquid inlet pipe 31, and the alkali liquid outlet is connected to the liquid outlet pipe 32. The fan 6 is used to transport the exhaust gas from the waste oil tank 2 to the alkali washing tower 3; the air inlet end of the combustion device 4 is connected to the exhaust port of the alkali washing tower 3, and the gas after combustion by the combustion device 4 is discharged into the atmosphere.

[0031] The recycling method includes the following steps:

[0032] The high-freezing-point exhaust gas is insulated and heated to maintain 130°C and enters the first shell layer of the heat exchanger 1 from the exhaust gas inlet pipe 5. The heat exchanger 1 cools the high-freezing-point exhaust gas in the first shell layer to 35°C, and the C5 and C5+ components in the oil and gas are condensed and collected in the waste oil tank 2; the high-freezing-point exhaust gas with heavy components removed enters the alkali washing tower 3 through the fan 6, and the acidic components in the oil and gas are removed by alkali liquid. The treated oil and gas mainly contains C4 and below light components and is then sent to the combustion equipment 4 and finally discharged after combustion.

[0033] This embodiment treats high-freezing-point waste gas, which can effectively avoid the direct discharge of oil and gas from the tank area. In view of the situation where the asphalt tail gas has a heavy odor and the heavy components and paraffin components are more prone to condensation, the pretreatment method of desulfurization after water cooling has the advantages of low cost, short process, and stable operation. The water-cooling unit uses a jacketed heat exchanger and a waste oil tank for the coil to be heated, which can effectively treat the asphalt wax condensed and attached to the surface of the equipment. The subsequent desulfurization unit can effectively remove the H2S component of the asphalt oil and gas and eliminate the odor of the tail gas. Finally, it enters the combustion equipment and is fully oxidized to meet the national environmental protection emission standards before being discharged.

[0034] This embodiment targets the process characteristics of high-freezing-point waste gas such as asphalt and liquid sulfur, combines cooling, alkali washing, absorption and combustion, sets up equipment in a targeted manner, and processes each component in the oil and gas in layers, ultimately achieving the purpose of qualified emissions. It has the advantages of low investment, short process, stable operation, etc., and has strong feasibility in the treatment of high-freezing-point waste gas in China.

Claims

1. A method for recovering high-freezing-point waste gas, characterized in that The recovery method utilizes a high-freezing-point waste gas recovery device, which includes A heat exchanger (1) having an exhaust gas inlet pipe (5) at the top end, a discharge pipe (14) at the bottom end, and a first tube layer (12) capable of accommodating cooling water; A waste oil tank (2), the feed end of which is connected to the discharge end of the discharge pipe (14), and a waste gas outlet is provided at the top of the waste oil tank (2); The alkali washing tower (3) has a waste gas inlet at the middle or bottom, an exhaust port at the top, an alkali liquid inlet at the top, and an alkali liquid outlet at the bottom; A fan (6) is used to transport the waste gas from the waste oil tank (2) to the alkali washing tower (3); and A combustion device (4), the air inlet end of which is connected to the exhaust port of the aforementioned alkali washing tower (3); The exhaust gas inlet pipe (5) is sheathed with a steam heating pipe (51) and a heat insulation layer on its outer periphery; The first tube layer (12) is also connected to a first steam inlet pipe (15) and a first condensate outlet pipe (16); The waste oil tank (2) has a second pipe layer (21), and the second pipe layer (21) is connected to a second steam inlet pipe (211) and a second condensate outflow pipe (212); The steps include: The high-freezing-point waste gas is insulated and heated to maintain 130°C and enters the first shell of the heat exchanger (1) from the waste gas inlet pipe (5). The heat exchanger (1) cools the high-freezing-point waste gas in the first shell to 35°C. The C5 and C5+ components in the oil and gas are condensed and collected in the waste oil tank (2). The high-freezing-point waste gas with heavy components removed enters the alkali washing tower (3) through the fan (6). The acidic components in the oil and gas are removed by alkali liquid. The treated oil and gas mainly contains C4 and light components below and is then sent to the combustion equipment (4) for final discharge after combustion.

2. The method for recovering high-freezing-point waste gas according to claim 1, characterized in that A liquid level sensor (22) is provided in the waste oil tank (2), and a valve (23) linked to the liquid level sensor (22) is provided on the exhaust gas intake pipe (5).

3. The method for recovering high-freezing-point waste gas according to claim 1, characterized in that The bottom of the waste oil tank (2) is connected to a condensate output pipe (22).

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