A method for repairing a groove of a tank of an online coal gas deep desulfurization system

Abstract

This invention relates to a method for repairing dents in tanks of an online deep desulfurization system for coal gas. The method includes the following steps: Step 1: determining the water level by injecting water; Step 2: calculating and verifying the charging pressure; Step 3: selecting the location of the air filling point; Step 4: determining the installation location of the pressure gauge; Step 5: controlling the water injection and air circulation rates; Step 6: pressurizing and repairing the dented area of ​​the tank. This technical solution fully considers the environmental safety of the coal gas operation area, involves non-flame construction, and does not require stopping the operation of the device. It only uses water filling and air circulation to repair the dented tank. The entire operation process is simple, convenient, and low-cost, making it easy to promote and apply further.

Description

Technical Field

[0001] This invention relates to a repair method, specifically a method for repairing dents in tanks of an online deep desulfurization system for coal gas, belonging to the field of tank dent repair technology. Background Technology

[0002] Currently in the coal gas deep desulfurization industry, due to the potential fluctuations in coal gas parameters, operators may fail to adjust the operating parameters in a timely manner, leading to operational errors. As a result, some atmospheric pressure tanks in the deep desulfurization system may experience negative pressure of -30 kPa or higher. Under atmospheric pressure, the tank walls of the negative pressure tanks may deform inward, reducing their usability.

[0003] In extreme cases, if the tank wall is completely dented and severely deformed in multiple areas, with the deformed area exceeding 50%, the conventional repair plan involves cutting and repairing the dented area. This involves cutting out the dented and deformed parts, then welding them back together with the same shape and materials. After welding, the welds are inspected according to the original tank's technical requirements. This plan often requires cutting out the dented parts of the tank, completely removing the tank from operation, purging it with nitrogen, erecting full-scale scaffolding, removing platforms, stairs, instruments, and other accessories, and re-applying internal and external anti-corrosion coatings. A DN10000mm diameter, 15-meter-high atmospheric pressure tank requires approximately one month for repair. The repair process is complex, consumes a large amount of steel, and has a long construction period. For a tank with 50% damage, the cost is comparable to building a new tank.

[0004] Because the tank is located in a gas operation area, and gas is toxic, harmful, flammable, and explosive, repairing dents and deformations in the tank is classified as a Class 1 high-risk hot work operation. Safety measures are time-consuming and costly, often requiring equipment shutdown. Therefore, the repair process must first carefully consider the safety of the working environment, as well as simplicity, speed, labor and material savings, low pressure, and minimal disruption to equipment operation. Summary of the Invention

[0005] This invention addresses the problems existing in the prior art by providing a method for repairing dented tanks in an online deep desulfurization system for coal gas. This technical solution fully considers the environmental safety of the coal gas operation area, involves no open flame construction, and does not require the equipment to be shut down. The dented tanks are repaired only by filling with water and venting. The entire operation process is simple and convenient, with low cost, and is easy to promote and apply.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: a method for repairing dents in tanks of an online deep desulfurization system for coal gas, the method comprising the following steps:

[0007] Step 1: Determine the water level by injecting water.

[0008] Step 2: Calculation and verification of charging pressure.

[0009] Step 3: Selecting the inflation point location.

[0010] Step 4: Determining the installation location of the pressure gauge.

[0011] Step 5: Controlling the water injection and ventilation rates.

[0012] Step 6: Pressurize and repair the dented parts of the tank.

[0013] As a further improvement of the present invention, step 1: determining the water level by water injection is as follows: the tank includes a recessed cylinder, which is provided with a manhole, spare port one, spare port two, vent, tank inlet, other pipe ports, water injection port, sampling port and U-shaped pressure gauge. The water level determination includes closing the manhole, opening the vent, and closing the other pipe ports. Water is injected into the recessed cylinder through the water injection port to a height of h2, ensuring that h2 is higher than the top elevation h1 of the tank inlet, ensuring that the tank inlet is full of liquid and does not leak air during the subsequent pressurization process. The height of h2 does not exceed the bottom elevation of the recessed part and is not less than h1+1m, ensuring a certain water holding capacity at the bottom of the tank, so that the tank bottom plate and tank wall remain balanced and stable during the pressurization process.

[0014] As a further improvement of the present invention, step 2: calculation and verification of the charging pressure is as follows:

[0015] 1) Calculate the displayed pressure of the U-tube manometer using the formula P = ρgh.

[0016] 2) Calculate the pressure inside the tank based on the formula PV=nRT, the gas side volume of the tank, and the input gas pressure. Compare and analyze the errors of the two multiple times to facilitate the accuracy and controllability of the step-by-step pressurization implementation.

[0017] As a further improvement of the present invention, step 3: the selection of the location of the inflation point includes taking into account non-flame construction in a gas environment, being far away from the liquid side, selecting the second spare port on the top of the tank as the inflation port, and connecting it to the purging pipeline by installing reducer fittings and hoses.

[0018] As a further improvement of the present invention, step 4: determining the installation location of the pressure gauge, including considering non-flame construction in a gas environment and the accuracy of pressure measurement, selecting a spare port on the top of the tank as the pressure gauge port, installing a blind flange on the port, opening a hole in the blind flange, and connecting it to the U-shaped pressure gauge through a flexible hose, and installing the U-shaped pressure gauge near the top of the tank to maintain stability and balance.

[0019] As a further improvement to the present invention, step 5: control of water injection and aeration rates is as follows:

[0020] The ventilation process includes a replacement phase. A pressure gauge is installed at backup port one, the water inlet is closed, and nitrogen is introduced through backup port two. The pressure gauge at backup port one is observed, and the pressure inside the tank does not exceed the design pressure. The gas inside the tank is replaced until the CO concentration at the sampling port is 0. The ventilation rate is controlled by closing the vent and continuing to introduce gas through backup port two. At this time, the gas can be nitrogen or air. The ventilation rate is controlled so that the pressure rise in the tank per minute does not exceed 1% of the design pressure, which facilitates the slow recovery of the dented cylinder and prevents the cylinder structure from being damaged by the recovery rate too fast. The pressure gauge at backup port one is observed. When the pressure inside the tank reaches 5% of the design pressure, ventilation is stopped and observed for a period of time. After the dented part stops recovering and there are no abnormalities, ventilation is resumed. Ventilation is stopped and observed every time the pressure inside the tank increases by 5% of the design pressure until the dented part of the tank is completely recovered. Under normal circumstances, when the pressure inside the tank reaches 50% of the design pressure, the dented part can recover about 80%, and when it reaches 100%, the dented part is basically recovered.

[0021] As a further improvement of the present invention, step 6: pressurize and repair the dented part of the tank, specifically as follows: pressurization repair includes keeping all pipe ports in their original positions after the tank dent is restored, maintaining pressure for 2 hours, and then depressurizing. The repair includes opening the vent after the tank dent is restored and depressurizing, and then introducing nitrogen gas through the spare port to purge and replace the tank until the nitrogen content of the sample taken from the sampling port is >98% and the oxygen content is less than 2%. The tank repair is then completed and it can be put into operation.

[0022] Compared with the prior art, the present invention has the following advantages: the technical solution fully considers the environmental safety of the gas operation area, does not require fire construction, the device does not need to stop operation, and only uses water filling and air ventilation to repair the dented tank. It is simple, fast, labor-saving, material-saving, low investment, and the low pressure does not affect operation, and is worth promoting and using. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a recessed tank in an online deep desulfurization system for coal gas according to the process of this invention.

[0024] In the diagram: 1. Recessed cylinder, 2. Manhole, 3. Spare port one, 4. Spare port two, 5. Vent, 6. Tank inlet, 7. Other pipe ports, 8. Water inlet, 9. Sampling port, 10. U-shaped pressure gauge. Detailed Implementation

[0025] To enhance understanding of the present invention, the embodiments will be described in detail below with reference to the accompanying drawings.

[0026] Example 1: See Figure 1A method for repairing dents in tanks of an online deep desulfurization system for coal gas includes: determining the water injection level, calculating and verifying the charging pressure, selecting the location of the air filling point, determining the installation location of the pressure gauge, and controlling the water injection and air supply rates to pressurize and repair the dented parts of the tank, as detailed below:

[0027] The tank includes a recessed cylinder 1, a manhole 2, a spare port 1 3, a spare port 2 4, a vent 5, a tank inlet 6, other pipe ports 7, a water inlet 8, and a sampling port 9. The pressure gauge includes a U-shaped pressure gauge 10. The water level determination includes closing the manhole 2, opening the vent 5, and closing the other pipe ports 7. Water is injected into the recessed cylinder 1 through the water inlet 8 until the water level reaches a height of h2. This ensures that h2 is higher than the top elevation h1 of the tank inlet 6, guaranteeing that the tank inlet 6 is full and airtight during subsequent pressurization. The height h2 does not exceed the bottom elevation of the recessed part and is not less than h1+1m, ensuring a certain water holding capacity at the bottom of the tank and keeping the tank bottom plate and tank wall balanced and stable during pressurization.

[0028] The calculation and verification of the charging pressure includes 1) calculating the displayed pressure of the U-shaped pressure gauge 10 according to the formula P=ρgh, and 2) calculating the pressure inside the tank according to the formula PV=nRT, the gas side volume of the tank, and the input gas pressure. The error between the two is compared and analyzed multiple times to facilitate the accuracy and controllability of the step-by-step charging implementation.

[0029] The selection of the inflation point location includes taking into account non-flame construction in a gas environment, being far away from the liquid side, selecting spare port 4 on the top of the tank as the inflation port, and connecting it to the purging pipeline by installing reducer fittings and hoses.

[0030] The determination of the pressure gauge installation location takes into account non-flammable construction in a gas environment and the accuracy of pressure measurement. The spare port 3 on the top of the tank is selected as the pressure gauge port. A blind flange is installed at the port, and the blind flange is perforated. It is connected to the U-shaped pressure gauge 10 through a flexible hose. The U-shaped pressure gauge 10 is installed near the top of the tank to maintain stability and balance.

[0031] The ventilation process includes a replacement step. A pressure gauge is installed at the backup port 3, the water inlet 8 is closed, nitrogen is introduced through the backup port 4, and the pressure gauge at the backup port 3 is observed. The pressure inside the tank does not exceed the design pressure. The gas inside the tank is replaced until the CO concentration at the sampling port 9 is 0.

[0032] The ventilation rate control includes closing the vent 5 and continuing to introduce gas through the backup port 4. The gas can be nitrogen or air. The ventilation rate is controlled so that the pressure rise in the tank per minute does not exceed 1% of the design pressure, facilitating the slow recovery of the dented cylinder 1 and preventing excessively rapid recovery from damaging the cylinder structure. The pressure gauge at the backup port 3 is observed. When the pressure inside the tank reaches 5% of the design pressure, ventilation is stopped, and observation is maintained for a period of time. Once the dented area stops recovering and no abnormalities are confirmed, ventilation is resumed. Ventilation is stopped and observed every 5% increase in the tank pressure compared to the design pressure until the dented area of ​​the tank is completely recovered. Generally, when the tank pressure reaches 50% of the design pressure, the dented area can recover about 80%, and when it reaches 100%, the dented area is essentially recovered.

[0033] The pressurization repair process involves restoring the dented tank, keeping all pipe openings in their original positions, maintaining pressure for 2 hours, and then depressurizing.

[0034] The repair process includes restoring the dented tank and depressurizing it, opening the vent 5, and introducing nitrogen gas through the spare port 4 to purge and replace the tank until the nitrogen content at the sampling port 9 is >98% and the oxygen content is less than 2%. The tank repair is then complete and the tank can be put into operation.

[0035] Work process: Refer to Figure 1 This invention discloses a process for repairing dents in tanks of a deep desulfurization system for coal gas, comprising: Figure 1As shown, its operating principle is as follows: Manhole 2 is closed, vent 5 is open, and other ports 7 are closed. Water is injected into the recessed cylinder 1 through water inlet 8 until the water level reaches height h2, which is higher than the top elevation h1 of the tank inlet 6, ensuring the tank inlet 6 is full and leak-proof. A pressure gauge is installed at spare port 3. Water inlet 8 is closed, and nitrogen is introduced through spare port 4. The pressure gauge at spare port 3 is observed. If the pressure inside the tank does not exceed the design pressure, the gas inside the tank is displaced until the CO concentration sampled at sampling port 9 is 0. Vent 5 is closed, and gas is continued to be introduced through spare port 4. This gas can be nitrogen or air. The rate of gas introduction is controlled so that the pressure rise in the tank per minute does not exceed 1% of the design pressure, facilitating the slow recovery of the recessed cylinder 1 and preventing damage to the cylinder structure due to excessive recovery speed. The pressure gauge at spare port 3 is observed. When the pressure inside the tank reaches 5% of the design pressure, gas introduction is stopped. Observe for a period of time until the recessed area no longer recovers and no abnormalities are confirmed. Then, gas introduction is resumed. For every 5% increase in tank pressure compared to the design pressure, gas supply is stopped and the tank is observed until the dented area is completely restored. Generally, when the tank pressure reaches 50% of the design pressure, the dented area will have recovered approximately 80%, and when it reaches 100%, the dent is essentially restored. After the tank dent is restored, all pipe openings remain in their original positions, and the pressure is maintained for 2 hours before depressurization. After depressurization and restoration, vent port 5 is opened, and nitrogen gas is introduced through spare port 4 to purge and replace the tank until the nitrogen content at sampling port 9 is >98% and the oxygen content is less than 2%. The tank repair is then complete and it can be put into operation.

[0036] It should be noted that the above embodiments are not intended to limit the scope of protection of the present invention. Equivalent transformations or substitutions made based on the above technical solutions all fall within the scope of protection of the claims of the present invention.

Claims

1. A method for repairing dents in tanks of an online deep desulfurization system for coal gas, characterized in that, The method includes the following steps: Step 1: Determine the water level by injecting water. Step 2: Calculation and verification of charging pressure. Step 3: Selecting the inflation point location. Step 4: Determining the installation location of the pressure gauge. Step 5: Controlling the water injection and ventilation rates. Step 6: Pressurize and repair the dented areas of the tank; Step 1: Determine the water level by injecting water, as follows: The tank includes a recessed cylinder (1), which is equipped with a manhole (2), spare port one (3), spare port two (4), vent (5), tank inlet (6), other pipe ports (7), water injection port (8), sampling port (9) and U-shaped pressure gauge (10). The water level determination includes closing the manhole (2), opening the vent (5), closing the other pipe ports (7), injecting water into the recessed cylinder (1) through the water injection port (8), and injecting water to a height of h2, ensuring that h2 is higher than the top elevation h1 of the tank inlet (6), ensuring that the tank inlet (6) is full of liquid and does not leak air during the subsequent pressurization process, and that the height of h2 does not exceed the bottom elevation of the recessed part and is not less than h1+1m, ensuring a certain water holding capacity at the bottom of the tank, so that the tank bottom plate and tank wall remain balanced and stable during the pressurization process; Step 2: Calculation and verification of the charging pressure, as follows: 1) Calculate the displayed pressure of the U-shaped pressure gauge (10) according to the formula P=ρgh. 2) Calculate the pressure inside the tank based on the formula PV=nRT, the gas side volume of the tank, and the input gas pressure. Compare and analyze the errors between the two multiple times to facilitate the accuracy and controllability of the step-by-step pressurization implementation. Step 3: Selection of the inflation point location, including consideration of non-flame construction in a gas environment, away from the liquid side, selecting the second (4) spare port on the top of the tank as the inflation port, and connecting it to the purging pipeline by installing reducer fittings and hoses; Step 4: Determining the installation location of the pressure gauge, including considering non-flame construction in a gas environment and the accuracy of pressure measurement, selecting the spare port 1 (3) on the top of the tank as the pressure gauge port, installing a blind flange on the pipe port, opening the blind flange, and connecting it to the U-shaped pressure gauge (10) through a flexible hose, and installing the U-shaped pressure gauge (10) near the top of the tank to maintain stability and balance; Step 5: Control of water injection and ventilation rates, as detailed below: The ventilation process includes a replacement phase. A pressure gauge is installed at the backup port 1 (3), the water inlet (8) is closed, and nitrogen is introduced through the backup port 2 (4). The pressure gauge at the backup port 1 (3) is observed. The pressure inside the tank does not exceed the design pressure. The gas inside the tank is replaced until the CO concentration at the sampling port (9) is 0. The control of the ventilation speed includes closing the vent (5) and continuing to introduce gas through the backup port 2 (4). At this time, the gas is nitrogen or air. The ventilation speed is controlled so that the pressure rise of the tank per minute does not exceed 1% of the design pressure, so that the dented cylinder (1) can be slowly restored. This is to prevent the restoration speed from being too fast and damaging the cylinder structure. The pressure gauge at the backup port 1 (3) is observed. When the pressure inside the tank reaches 5% of the design pressure, the ventilation is stopped and observed for a period of time. After the dented part no longer restores and it is confirmed that there is no abnormality, the ventilation is continued. The ventilation is stopped and observed every time the pressure inside the tank increases by 5% of the design pressure until the dented part of the tank is completely restored. Step 6: Pressurize and repair the dented parts of the tank as follows: Pressurization repair includes keeping all pipe openings in their original positions after the tank dent is restored, maintaining pressure for 2 hours, and then depressurizing. The repair includes opening the vent (5) after the tank dent is restored and depressurized, and then introducing nitrogen gas through the spare port (4) to purge and replace the tank until the nitrogen content of the sample taken from the sampling port (9) is >98% and the oxygen content is less than 2%. The tank repair is completed and it can be put into operation.

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