Treatment equipment and processes for small-molecule short-chain alkanes in volatile gas from single oil wells

Abstract

This invention provides a treatment device and process for small-molecule short-chain alkanes in the volatile gas of a single oil well, belonging to the field of oilfield waste gas treatment technology. The treatment device for small-molecule short-chain alkanes in the volatile gas of a single oil well provided by this invention includes the following process units: a gas collection hood, a suction pump, a buffer humidification tank, a photolysis reaction column, a photocatalytic oxidation reaction column, a spray tower, and a microbial trickling filter. The equipment and method provided by this invention can effectively remove small-molecule short-chain alkanes that are difficult to remove by conventional methods from waste gas under conditions with high explosion-proof requirements through the synergistic effect of physicochemical and biochemical processes, reducing construction area, lowering construction costs, and improving treatment efficiency.

Description

Technical Field

[0001] This invention belongs to the field of oilfield waste gas treatment technology, and particularly relates to the treatment device and process for small molecule short-chain alkanes in the volatile gas of single wells in oilfields. Background Technology

[0002] Due to variations in the production process and the different characteristics of oil and gas production in single-well drilling, VOC emissions from well site storage tanks are irregular, exhibit significant concentration variations, and have complex compositions, making remediation challenging. For single-well drilling with mixed oil and gas production or high oil production, the VOC concentration in the released gas is very high, exceeding 100,000 ppm, indicating significant recovery value. Small-scale on-site recovery technologies and equipment should be used for recovery. Single-well drilling with low oil production is more numerous and geographically dispersed. The VOC concentration in the gas released from its well site storage tanks is generally low, and the gas volume is also small, offering almost no recovery value. However, the exceedance levels by emission standards are still very high, making on-site disposal technologies and facilities suitable for treatment.

[0003] Currently, the difficulty in on-site VOCs treatment of storage tanks in single-well sites with low VOCs lies in the fact that the VOCs are mainly composed of small-molecule short-chain alkanes, and commonly used physicochemical and biochemical methods are not very effective in treating them. Summary of the Invention

[0004] The purpose of this invention is to provide a device and process for treating small-molecule short-chain alkanes in the volatile gas of a single well in an oilfield.

[0005] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a device for processing small-molecule short-chain alkanes in the volatile gas of a single oil well, the device comprising the following process units: (1) Gas collection hood The gas collection hood is installed on the breather valve of the single well tank; (2) Suction pump The suction pump is connected to the air collection hood; (3) Buffer humidification tank The buffer humidification tank is connected to the air intake pump; (4) Photolysis reaction column The photolysis reaction column is connected to the buffer humidification tank; (5) Photocatalytic oxidation reaction column The photocatalytic reaction column is connected to the photolysis reaction column; (6) Spray tower The spray tower is connected to the photocatalytic oxidation reaction column; (7) Microbial trickling filter tower The microbial trickling filter tower is connected to the spray tower.

[0006] Preferably, the gas collection hood is a cylindrical gas collection hood with dimensions of d500*300mm and is made of stainless steel.

[0007] Preferably, the suction pump is a two-phase reciprocating piston single-inlet air pump, the maximum air volume of the suction pump is 80L / min, the maximum air pressure of the suction pump is 29kpa, and the suction volume of the suction pump is adjusted by a regulating valve before the flow meter.

[0008] Preferably, the buffer humidification tank is a stainless steel cylindrical tank, and the effective volume of the buffer humidification tank is 0.05 m³. 3 The air inlet of the buffer humidifier is located below the liquid level at the bottom of the pipe.

[0009] Preferably, the photolysis reaction column is a stainless steel square column reactor with dimensions of 115*115*900mm and an effective volume of 11.4L. The inner wall of the photolysis reaction column is lined with a catalyst, specifically TiO2@g-C3N4L, and the effective irradiation and reaction area of ​​the photolysis reaction column is 4000cm². 2 ; A low-pressure mercury ultraviolet lamp is positioned at the center of the photolysis reaction column. The power of the low-pressure mercury ultraviolet lamp is 75W, and the wavelength of the ultraviolet lamp is 254nm.

[0010] Preferably, the photocatalytic oxidation reaction column is a stainless steel square column reactor with dimensions of 115*115*900mm and an effective volume of 11.4L. The inner wall of the photocatalytic oxidation reaction column is lined with a catalyst, specifically TiO2@g-C3N4H, and the effective irradiation and reaction area of ​​the photocatalytic oxidation reaction column is 4000cm². 2 ; A low-pressure mercury ultraviolet lamp with a power of 75W and a wavelength of 185nm is installed at the center of the photocatalytic oxidation reaction column. The air inlet pipe of the photocatalytic oxidation reaction column is equipped with a three-way valve and an air pump, which can be used to draw in air to regulate the oxygen content.

[0011] Preferably, the spray tower is a cylindrical PVC spray tower with dimensions of d500*2200, a packing height of 700mm, a circulating water tank height of 600mm, and is equipped with 137L hollow plastic balls and 1m... 3 The circulating pump has a flow rate of / L, and the spray intensity of the spray tower is 5m. 3 / m 2 ; Preferably, the microbial trickling filter is a cylindrical PVC biochemical tower with dimensions of d500*2200, a microbial carrier height of 700mm, a circulating water tank height of 600mm, and 137L of microbial carrier inside the microbial trickling filter. The spray intensity of the microbial trickling filter tower is 5m. 3 / m 2 .

[0012] Secondly, this invention provides a process for treating small-molecule short-chain alkanes in the volatile gas of a single oil well, the process comprising the following steps: (1) Small molecule short-chain alkane gas volatilized from a single well in the oilfield is collected by a gas collecting hood, and the collected small molecule short-chain alkane gas is pumped into a buffer humidification tank by a gas suction pump; The intake pump reaction conditions are: actual intake volume of 1000 L / h; (2) After being treated by a buffer humidification tank, the small molecule short-chain alkane gas enters the photocatalytic reaction column for reaction; The reaction conditions for the buffer humidification tank are as follows: the buffer humidification tank contains 30-50% water, which can humidify the gas when it passes through. The actual air intake is 1000L / h and the residence time is 3min. The photocatalytic reaction column reaction conditions are: residence time of 41s, oxygen content of 15-18%, wavelength of U-shaped low-pressure mercury ultraviolet lamp of 254nm, luminous power of 75w, and actual air intake of 1000L / h. (3) After the reaction is completed, the small molecule short-chain alkane gas enters the photocatalytic oxidation reaction column to carry out the reaction; The reaction conditions were: residence time of 20.5 s, oxygen content of 18-19%, wavelength of U-shaped low-pressure mercury ultraviolet lamp of 185 nm, and luminous power of 75 W. (4) After the reaction is complete, the small molecule short-chain alkane gas enters the spray tower to continue the reaction; The reaction conditions were: exhaust gas flow rate of 2000 L / h, residence time of 9.4 min, and spray intensity of 5 m. 3 / m 2 The spray solution contains 100 mg / ml hydrogen peroxide and 50 mg / L ferrous sulfate, and the circulation pump and suction pump operate synchronously and continuously.

[0013] (5) After the reaction is complete, the small molecule short-chain alkane gas enters the (7) microbial trickling filter tower to carry out the reaction; The reaction conditions were: exhaust gas flow rate of 2000 L / h, residence time of 9.4 min, and spray intensity of 5 m. 3 / m 2 .

[0014] The beneficial effects of this invention are: 1. This invention uses multi-band ultraviolet lamps (254 nm, 185 nm) and carbon nitride composite titanium dioxide catalyst, which can play a dual role of photocatalytic decomposition and photocatalytic oxidation. It can spontaneously generate O3, eliminating the need for an additional O3 generator, reducing construction costs and ensuring oilfield safety. It achieves efficient treatment of small molecule short-chain alkanes in exhaust gas from single well tanks in oilfields during the physicochemical treatment stage. 2. This invention combines photocatalysis with a biological trickling filter. The photocatalytic stage can convert small molecule alkanes into soluble organic matter, which is beneficial to the treatment in the biochemical stage and further ensures that the single-well tank achieves VOCs emission standards. 3. In this invention, H2O2 and Fe are added to the spray tower. 2+ This allows for multiple processes within the spray tower, including desulfurization, humidification, Fenton reaction, and O3 / H2O2 reaction, reducing construction area, lowering construction costs, and improving processing efficiency. Attached Figure Description

[0015] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0016] To clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution.

[0017] Example 1 This invention provides a device for processing small-molecule short-chain alkanes in the volatile gas of a single well in an oilfield. The device includes the following process units: (1) Gas collection hood The gas collection hood is installed on the breather valve of the single well tank. The gas collection hood is a cylindrical gas collection hood with dimensions of d500*300mm and is made of stainless steel. (2) Suction pump The suction pump is connected to the air collection hood. The suction pump is a two-phase reciprocating piston single-inlet air pump with a maximum air volume of 80L / min and a maximum air pressure of 29kpa. The suction volume of the suction pump is adjusted by the regulating valve in front of the flow meter. (3) Buffer humidification tank The buffer humidifier tank is connected to the intake pump. The buffer humidifier tank is a stainless steel cylindrical tank with an effective volume of 0.05 m³. 3 The air inlet of the buffer humidifier is located below the liquid level at the bottom of the pipe; (4) Photolysis reaction column The photolysis reaction column is connected to a buffer humidification tank. The photolysis reaction column is a stainless steel square column reactor with dimensions of 115*115*900mm and an effective volume of 11.4L. The inner wall of the photolysis reaction column is lined with a catalyst, specifically TiO2@g-C3N4L. The effective irradiation and reaction area of ​​the photolysis reaction column is 4000cm². 2 ; A low-pressure mercury ultraviolet lamp is placed at the center of the photolysis reaction column. The power of the low-pressure mercury ultraviolet lamp is 75W and the wavelength of the ultraviolet lamp is 254nm. (5) Photocatalytic oxidation reaction column The photocatalytic oxidation column is connected to the photolysis column. The photocatalytic oxidation column is a stainless steel square column reactor with dimensions of 115*115*900mm and an effective volume of 11.4L. The inner wall of the photocatalytic oxidation column is lined with a catalyst, specifically TiO2@g-C3N4H. The effective irradiation and reaction area of ​​the photolysis column is 4000cm². 2 ; A low-pressure mercury ultraviolet lamp is placed at the center of the photolysis reaction column. The power of the low-pressure mercury ultraviolet lamp is 75W and the wavelength type of the low-pressure mercury ultraviolet lamp is 185nm. (6) Spray tower The spray tower is connected to the photocatalytic oxidation reaction column. The spray tower is a cylindrical PVC spray tower with dimensions of d500*2200. The packing height is 700mm, and the circulating water tank height is 600mm. The spray tower contains 137L hollow plastic spheres and a 1m... 3 A circulating pump with a capacity of / L, and a spray intensity of 5m from the spray tower. 3 / m 2 ; (7) Microbial trickling filter tower The microbial trickling filter is connected to the spray tower. The microbial trickling filter is a cylindrical PVC biochemical tower with dimensions of d500*2200. The height of the microbial carrier in the microbial trickling filter is 700mm, and the height of the circulating water tank in the microbial trickling filter is 600mm. The microbial trickling filter contains 137L of microbial carrier. The spray intensity of the microbial trickling filter tower is 5m. 3 / m 2 .

[0018] Example 2 Single photolysis reaction The gas is processed through a gas collection hood, a suction pump, a buffer humidification tank, and a photolysis reaction column. Treatment target 1: Total VOCs of 500-1000 mg / m³ 3The composition is 50% methane, 25% ethane, and 25% propane. Treatment Target 2: Actual waste gas, with a total VOCs content of 1000-2000 mg / m³ 3 ; Experimental conditions: Intake pump stage: intake volume is 1000L / h; Buffer humidification tank stage: air intake is 1000L / h, buffer humidification tank contains 30-50% water, residence time is 3min; Photolysis reaction column stage: air intake is 1000L / h, residence time is 41s, oxygen content is 15-18%, wavelength of U-shaped low-pressure mercury ultraviolet lamp is 254nm, luminous power is 75w; Experimental results: Treatment target 1: The average removal rate of VOCs gas was 7.5%; The average removal rate of VOCs gas for treatment object 2 was 8.5%.

[0019] Example 3 Single photocatalytic oxidation reaction The gas is processed through a gas collection hood, a suction pump, a buffer humidification tank, and a photocatalytic oxidation reaction column. Treatment target 1: Total VOCs of 500-1000 mg / m³ 3 The composition is 50% methane, 25% ethane, and 25% propane. Treatment Target 2: Actual waste gas, with a total VOCs content of 1000-2000 mg / m³ 3 ; Experimental conditions: Intake pump stage: intake volume is 1000L / h; Buffer humidification tank stage: air intake is 1000L / h, buffer humidification tank contains 30-50% water, residence time is 3min; Photocatalytic oxidation reaction column: air intake is 1000L / h, residence time is 20.5s, oxygen content is 18-19%, U-shaped low-pressure mercury ultraviolet lamp wavelength is 185nm, luminous power is 75w; Experimental results: Treatment Target 1: The average removal rate of VOCs gas was 21%; Treatment target 2: The average removal rate of VOCs gas was 23%.

[0020] Example 4 Photocatalysis and catalytic oxidation combined The gas is processed through a gas collection hood, a suction pump, a buffer humidification tank, a photolysis reaction column, and a photocatalytic oxidation reaction column. Treatment target 1: Total VOCs of 500-1000 mg / m³ 3 The composition is 50% methane, 25% ethane, and 25% propane. Treatment Target 2: Actual waste gas, with a total VOCs content of 1000-2000 mg / m³ 3 ; Experimental conditions: Intake pump stage: intake volume is 1000L / h; Buffer humidification tank stage: air intake is 1000L / h, buffer humidification tank contains 30-50% water, residence time is 3min; Photolysis reaction column stage: air intake is 1000L / h, residence time is 41s, oxygen content is 15-18%, wavelength of U-shaped low-pressure mercury ultraviolet lamp is 254nm, luminous power is 75w; Photocatalytic oxidation reaction column: air intake is 1000L / h, residence time is 20.5s, oxygen content is 18-19%, U-shaped low-pressure mercury ultraviolet lamp wavelength is 185nm, luminous power is 75w; Experimental results: Treatment Target 1: The average removal rate of VOCs gas was 30%; The average removal rate of VOCs gas for treatment object 2 was 33%.

[0021] Example 5 The gas is processed through a gas collection hood, a suction pump, a buffer humidification tank, a photolysis reaction column, a photocatalytic oxidation reaction column, and a spray tower. Treatment target 1: Total VOCs of 500-1000 mg / m³ 3 The composition is 50% methane, 25% ethane, and 25% propane. Treatment Target 2: Actual waste gas, with a total VOCs content of 1000-2000 mg / m³ 3 ; Experimental conditions: Intake pump stage: intake volume is 1000L / h; Buffer humidification tank stage: air intake is 1000L / h, buffer humidification tank contains 30-50% water, residence time is 3min; Photolysis reaction column stage: air intake is 1000L / h, residence time is 41s, oxygen content is 15-18%, wavelength of U-shaped low-pressure mercury ultraviolet lamp is 254nm, luminous power is 75w; Photocatalytic oxidation reaction column stage: air intake is 1000L / h, residence time is 20.5s, oxygen content is 18-19%, wavelength of U-shaped low-pressure mercury ultraviolet lamp is 185nm, luminous power is 75w; Spray tower stage: air intake rate 2000 L / h, residence time 9.4 min, spray intensity 5 m 3 / m 2 The spray solution contains 100 mg / ml hydrogen peroxide and 50 mg / L ferrous sulfate, and the circulation pump and suction pump operate synchronously and continuously.

[0022] Experimental results: Treatment target 1: The average removal rate of VOCs gas was 60%; Treatment target 2: The average removal rate of VOCs gas was 65%.

[0023] Example 6 The gas is processed through a gas collection hood, a suction pump, a buffer humidification tank, a photolysis reaction column, a photocatalytic oxidation reaction column, a spray tower, and a microbial trickling filter tower. Treatment target 1: Total VOCs of 500-1000 mg / m³ 3 The composition is 50% methane, 25% ethane, and 25% propane. Treatment Target 2: Actual waste gas, with a total VOCs content of 1000-2000 mg / m³ 3 ; Experimental conditions: Intake pump stage: intake volume is 1000L / h; Buffer humidification tank stage: air intake is 1000L / h, buffer humidification tank contains 30-50% water, residence time is 3min; Photolysis reaction column stage: air intake is 1000L / h, residence time is 41s, oxygen content is 15-18%, wavelength of U-shaped low-pressure mercury ultraviolet lamp is 254nm, luminous power is 75w; Photocatalytic oxidation reaction column stage: air intake is 1000L / h, residence time is 20.5s, oxygen content is 18-19%, wavelength of U-shaped low-pressure mercury ultraviolet lamp is 185nm, luminous power is 75w; Spray tower stage: air intake rate 2000 L / h, residence time 9.4 min, spray intensity 5 m 3 / m 2 The spray solution contains 100 mg / ml hydrogen peroxide and 50 mg / L ferrous sulfate, and the circulation pump and the suction pump run synchronously and continuously. Microbial trickling filter stage: exhaust gas flow rate 2000 L / h, residence time 9.4 min, spray intensity 5 m 3 / m 2 .

[0024] Experimental results: Treatment Target 1: The average removal rate of VOCs gas was 90%; Treatment target 2: The average removal rate of VOCs gas was 93%.

[0025] The technical features of this invention not described can be implemented by or using existing technology, and will not be repeated here. Of course, the above description is not a limitation of this invention, and this invention is not limited to the examples above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of this invention should also be within the protection scope of this invention.

Claims

1. A process for treating small-molecule short-chain alkanes in volatile gas from a single oil well, characterized in that, The process is carried out using a treatment unit for small-molecule short-chain alkanes in the volatile gas of single wells in oil fields. The treatment unit includes the following process units: (1) Gas collection hood The gas collection hood is installed on the breather valve of the single well tank; (2) Suction pump The suction pump is connected to the air collection hood; (3) Buffer humidification tank The buffer humidification tank is connected to the air intake pump; (4) Photolysis reaction column The photolysis reaction column is connected to the buffer humidification tank; (5) Photocatalytic oxidation reaction column The photocatalytic reaction column is connected to the photolysis reaction column; (6) Spray tower The spray tower is connected to the photocatalytic oxidation reaction column; (7) Microbial trickling filter tower The microbial trickling filter tower is connected to the spray tower; The gas collection hood is a cylindrical gas collection hood with a dimension of d500. 300mm, the gas collection hood is made of stainless steel; The suction pump is a two-phase reciprocating piston single-inlet air pump. The maximum air volume of the suction pump is 80L / min, the maximum air pressure of the suction pump is 29kpa, and the air volume of the suction pump is adjusted by the regulating valve before the flow meter. The buffer humidification tank is a stainless steel cylindrical tank with an effective volume of 0.05 m³. 3 The air inlet of the buffer humidifier is located below the liquid level at the bottom of the pipe; The photolysis reaction column is a stainless steel square column reactor, and the size of the photolysis reaction column is 115. 115 The photolysis reaction column has a diameter of 900 mm and an effective volume of 11.4 L. The inner wall of the photolysis reaction column is lined with a catalyst, specifically TiO2@g-C3N4L. The effective irradiation and reaction area of ​​the photolysis reaction column is 4000 cm². 2 ; A low-pressure mercury ultraviolet lamp is set at the center of the photolysis reaction column. The power of the low-pressure mercury ultraviolet lamp is 75W and the wavelength of the ultraviolet lamp is 254nm. The photocatalytic oxidation reactor column is a stainless steel square column reactor, and the size of the photocatalytic oxidation reactor column is 115. 115 The photocatalytic oxidation reaction column has a diameter of 900 mm and an effective volume of 11.4 L. The inner wall of the photocatalytic oxidation reaction column is lined with a catalyst, specifically TiO2@g-C3N4H. The effective irradiation and reaction area of ​​the photocatalytic oxidation reaction column is 4000 cm². 2 ; A low-pressure mercury ultraviolet lamp with a power of 75W and a wavelength of 185nm is installed at the center of the photocatalytic oxidation reaction column. The air inlet pipe of the photocatalytic oxidation reaction column is equipped with a three-way valve and an air pump, which can be used to draw in air to regulate the oxygen content. The spray tower is a cylindrical PVC spray tower with a dimension of d500. 2200, the packing height of the spray tower is 700mm, the height of the circulating water tank of the spray tower is 600mm, and the spray tower is equipped with 137L hollow plastic balls and 1m 3 The circulating pump has a flow rate of / L, and the spray intensity of the spray tower is 5m. 3 / m 2 ; The microbial trickling filter is a cylindrical PVC biochemical tower with a dimension of d500. 2200, the height of the microbial carrier in the microbial trickling filter is 700mm, the height of the circulating water tank in the microbial trickling filter is 600mm, and 137L of microbial carrier is installed inside the microbial trickling filter; The spray intensity of the microbial trickling filter is 5m. 3 / m 2 ; The process includes the following steps: (1) Small molecule short-chain alkane gas volatilized from a single well in the oilfield is collected by a gas collecting hood, and the collected small molecule short-chain alkane gas is pumped into a buffer humidification tank by a gas suction pump; The intake pump reaction conditions are: actual intake volume of 1000 L / h; (2) After being treated by a buffer humidification tank, the small molecule short-chain alkane gas enters the photocatalytic reaction column for reaction; The reaction conditions for the buffer humidification tank are as follows: the buffer humidification tank contains 30-50% water, which can humidify the gas when it passes through. The actual air intake is 1000L / h and the residence time is 3min. The photocatalytic reaction column reaction conditions are: residence time of 41s, oxygen content of 15-18%, wavelength of U-shaped low-pressure mercury ultraviolet lamp of 254nm, luminous power of 75w, and actual air intake of 1000L / h. (3) After the reaction is completed, the small molecule short-chain alkane gas enters the photocatalytic oxidation reaction column to carry out the reaction; The reaction conditions were: residence time of 20.5 s, oxygen content of 18-19%, wavelength of U-shaped low-pressure mercury ultraviolet lamp of 185 nm, and luminous power of 75 W. (4) After the reaction is complete, the small molecule short-chain alkane gas enters the spray tower to continue the reaction; The reaction conditions were: exhaust gas flow rate of 2000 L / h, residence time of 9.4 min, and spray intensity of 5 m. 3 / m 2 The spray solution contains 100 mg / ml hydrogen peroxide and 50 mg / L ferrous sulfate, and the circulation pump and suction pump operate synchronously and continuously. (5) After the reaction is complete, the small molecule short-chain alkane gas enters the (7) microbial trickling filter tower to carry out the reaction; The reaction conditions were: exhaust gas flow rate of 2000 L / h, residence time of 9.4 min, and spray intensity of 5 m. 3 / m 2 .

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