Natural gas purification tail gas treatment system transformation method and tail gas treatment device

Abstract

The invention relates to the technical field of natural gas tail gas treatment, in particular to a natural gas purification tail gas treatment system transformation method and a tail gas treatment device.The transformation method comprises the following steps that S1, a drainage hole and a backflow hole are formed in the proper height of a chimney in a protective hole forming mode; s2, an alkaline washing tower and a first pipeline are arranged, one end of the first pipeline extends into the drainage hole and is connected with a chimney gas inlet pipe, and the other end of the first pipeline is connected into the alkaline washing tower; and S3, a second pipeline is arranged, and the second pipeline communicates with the backflow hole and is used for leading the tail gas passing through the alkaline washing tower back to the chimney. The holes are formed in the chimney to lead out tail gas and return the tail gas to the chimney, the phenomenon that sulfur dioxide in the tail gas exceeds the standard under the special working condition of a natural gas tail gas treatment system is avoided, the chimney is only modified, and the cost is reduced compared with a hydrogenation reduction process. And operation such as large-area dismounting, damage or reconstruction of existing equipment and pipelines is not needed, so that the transformation cost of the tail gas treatment system is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of natural gas purification, and in particular to a method for modifying a natural gas purification tail gas treatment system and a tail gas treatment device. Background Art

[0002] The high-sulfur natural gas tail gas treatment adopts the conventional Claus unconventional split-flow sulfur recovery and hydrogenation reduction tail gas absorption process technology, with a total sulfur recovery rate of more than 99.8%. Under normal production conditions, flue gas SO2 emissions meet the requirements of CB16297-1996 "Comprehensive Emission Standards for Air Pollutants", and the flue gas sulfur dioxide emission index is less than 960mg / m 3 As the country pays more and more attention to the ecological environment, the Ministry of Ecology and Environment approved and issued the "Onshore Oil and Natural Gas Extraction Industry Air Pollutant Emission Standards" on December 8, 2020, requiring the SO2 index of the tail gas of the natural gas purification plant to be controlled at 400mg / m 3 As a result, under some working conditions, the sulfur dioxide concentration in the tail gas cannot meet the emission requirements. For example, in the early stage of the natural gas tail gas treatment system, the catalyst for hydrogenation reduction was not fully activated, resulting in incomplete treatment of sulfur dioxide in the tail gas. Since the tail gas treatment system for natural gas production has been built, the pipelines and equipment have been finalized, and it is difficult to add other equipment and pipelines, which has brought great difficulty to the transformation of the tail gas treatment system.

[0003] Therefore, a technical solution is currently needed to solve the technical problem that after the natural gas tail gas treatment system is built and finalized, it cannot adapt to the new sulfur dioxide emission standards and is difficult to be modified. Summary of the invention

[0004] The purpose of the present invention is to provide a method for modifying a natural gas purification tail gas treatment system and a tail gas treatment device to address the technical problem that after the existing natural gas tail gas treatment system is built and finalized, it cannot adapt to the new sulfur dioxide emission standard and is difficult to be modified.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: A method for modifying a natural gas purification tail gas treatment system comprises the following steps: S1: Use protective opening method to open drainage holes and return holes at appropriate height of chimney; S2: an alkali washing tower and a first pipeline are provided, wherein one end of the first pipeline extends into the drainage hole and is connected to the chimney air inlet pipe, and the other end is connected to the alkali washing tower; S3: a second pipeline is provided, wherein the second pipeline is connected to the reflux hole and is used for guiding the tail gas passing through the alkali washing tower back to the chimney.

[0006] The invention discloses a method for modifying a natural gas tail gas treatment system. The method comprises the following steps: providing a drainage hole and a reflux hole on a chimney wall, extending a first pipe from the drainage hole and connecting the first pipe to an air inlet pipe of the chimney, so that the tail gas enters an alkali washing tower through the first pipe, removing most of the sulfur dioxide in the flue gas through alkali washing, reducing the content of sulfur dioxide in the tail gas, and then returning the alkali-washed flue gas to the chimney through a second pipe, and then discharging the tail gas to high altitude through the chimney. The invention discloses a method for modifying a natural gas tail gas treatment system. The method comprises the following steps: providing a drainage hole and a reflux hole on a chimney wall, extending a first pipe from the drainage hole and connecting the first pipe to an air inlet pipe of the chimney, so that the tail gas enters an alkali washing tower through the first pipe, removing most of the sulfur dioxide in the flue gas through alkali washing, reducing the content of sulfur dioxide in the tail gas, and avoiding the phenomenon that the sulfur dioxide in the tail gas exceeds the standard under special working conditions of the natural gas tail gas treatment system. Moreover, the method only modifies the chimney. Compared with changing the hydrogenation reduction process, the method does not require large-scale demolition, destruction or reconstruction of existing equipment and pipelines, thereby reducing the modification cost of the tail gas treatment system.

[0007] As a preferred embodiment of the present invention, in S1, the protective opening method comprises the following steps: S1-1: Erection of external scaffolding of chimney; S1-2: opening on the chimney outer wall; S1-3: Erection of scaffolding inside chimney; S1-4: Removal of refractory bricks and insulation layer on the inner wall of the chimney.

[0008] The above steps S1-1 and S1-2 are implemented before the tail gas treatment system is shut down, which will not affect the original tail gas emissions. Steps S1-3 and S1-4 are implemented after the tail gas treatment system is shut down, which can reduce the impact time of the transformation on the tail gas treatment and minimize the impact of the transformation process on the normal production of natural gas.

[0009] As a preferred solution of the present invention, the first pipeline includes a connecting section and a lead-out section, the connecting section is connected to the end of the air inlet pipe, one end of the lead-out section is connected to the connecting section, and the other end is connected to the alkali washing tower. Since the first pipeline needs to extend into the chimney and be connected to the air inlet pipe opening in the chimney, the first pipeline is divided into sections, connected to the air inlet pipe through the connecting section, and the exhaust gas is led out through the lead-out section connected to the connecting section, so that the installation of the first pipeline is simpler and the construction difficulty of the first pipeline is reduced.

[0010] As a preferred solution of the present invention, the end of the lead-out section is sleeved on one end of the connecting section, and the overlapping portion of the two passes through the drainage hole. The lead-out section and the connecting section are connected in a sleeved manner. When the port is sealed, the drainage hole can support the connecting section and the lead-out section at the same time, and no separate support is required, making the connection operation of the lead-out section and the connecting section easier, and convenient to fill elastic material between the two to offset the deformation of the pipe section that may occur due to heat.

[0011] As a preferred solution of the present invention, one end of the connecting section close to the lead-out section is wrapped with refractory fiber paper. Due to the high temperature of the exhaust gas, thermal expansion will occur to the pipe during the circulation of the first pipe. The connecting section and the lead-out section are filled with refractory fiber paper for sealing. The pipe sections expand and slide against each other, which fully reduces the impact of thermal stress on the chimney.

[0012] As a preferred solution of the present invention, in the processes of steps S1-2 and S1-3, the chimney wall is protected by injecting polyurethane, thereby reducing the scattering of silica gel plates and pearl sand in the chimney wall during the construction process and reducing the damage to the chimney structure caused by the hole opening process.

[0013] As a preferred solution of the present invention, it also includes step S1-5, in which steel sleeves are nested in the hole wall of the return hole and the hole wall of the drainage hole, and a refractory fiber blanket is laid on the inner wall of the steel sleeve. The steel sleeve supports and protects the hole wall, improves the structural strength of the chimney after the hole is opened, and reduces the influence of the drainage hole and the return hole on the chimney strength. The refractory fiber blanket has a certain expansion and contraction performance. When the first pipe or the second pipe undergoes thermal expansion, it can adapt to the deformation of the pipe through its own contraction deformation, thereby reducing the influence of the thermal deformation of the pipe on the chimney structure.

[0014] As a preferred solution of the present invention, step S1-6 is also included, wherein a supporting steel plate frame is arranged between the return hole and the drainage hole, and the supporting steel plate frame includes two straight plates arranged crosswise to improve the structural strength of the chimney wall between the drainage hole and the return hole after the opening, thereby ensuring the safety of the chimney.

[0015] As a preferred solution of the present invention, in S, before the drainage holes and the return holes are opened, the chimney parameters are input into the PKPM software, and the drainage hole (11) and the return hole (12) parameters are input to calculate whether the strength of the chimney after the holes are opened meets the requirements. By performing model calculation in the software, it is calculated in advance whether the chimney can meet the opening height and opening size, so as to avoid the chimney collapse or other safety hazards caused by the opening process.

[0016] A natural gas production tail gas treatment device, a tail gas treatment device formed by the above-mentioned natural gas tail gas treatment system modification method, includes a chimney body, a first pipeline, a second pipeline and an alkali washing tower, the chimney body is connected to an air inlet pipe, the side wall of the chimney body is provided with a drainage hole and a reflux hole, the first pipeline extends into the drainage hole and is connected to the air inlet pipe, the second pipeline is connected to the reflux hole, the air inlet end of the alkali washing tower is connected to the first pipeline, and the air outlet end is connected to the second pipeline.

[0017] The invention discloses a natural gas production tail gas treatment device. When in use, the tail gas enters into a first pipeline through an air inlet pipe, then enters into an alkali scrubber, and is then led back into a chimney through a second pipeline, so that under special working conditions, sulfur dioxide in the tail gas that has not been completely treated is secondary treated in the alkali scrubber, thereby avoiding large-scale transformation of the existing tail gas treatment system and reducing the cost of natural gas production.

[0018] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. This application opens a hole in the chimney to extract the tail gas and return it to the chimney, reducing the sulfur dioxide content in the tail gas and avoiding the phenomenon that the sulfur dioxide in the tail gas exceeds the standard under special working conditions of the natural gas tail gas treatment system; 2. Only the chimney is modified. Compared with changing the hydrogenation reduction process, there is no need to carry out large-scale demolition, destruction or reconstruction of existing equipment and pipelines, which reduces the modification cost of the exhaust gas treatment system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a process flow of a natural gas purification tail gas treatment system transformation method of the present invention; Figure 2 It is a structural schematic diagram of a natural gas production tail gas treatment device of the present invention; Figure 3 is a schematic cross-sectional view of the chimney body of the present invention; Figure 4 yes Figure 2 Enlarged view of area A in the middle; Figure 5 yes Figure 2 Enlarged view of area B in the middle; Figure 6 is a side schematic diagram of the chimney body of the present invention; Markings in the figure: 1-chimney body, 11-drainage hole, 12-reflux hole, 2-inlet pipe, 3-first pipeline, 31-connecting section, 32-lead-out section, 33-refractory fiber paper, 4-second pipeline, 5-alkali washing tower, 6-first flange, 7-second flange, 8-steel sleeve, 81-refractory fiber blanket, 9-third flange, 10-support steel plate frame, 101-straight plate. DETAILED DESCRIPTION

[0020] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0021] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0022] Example 1 like Figure 1 , Figure 2 , Figure 3 and Figure 6 As shown, this embodiment is based on the tail gas treatment of a high-sulfur natural gas purification plant as an example to illustrate a method for transforming a natural gas purification tail gas treatment system. Under the background of the new national standard, the high-sulfur natural gas purification plant will have a tail gas sulfur dioxide concentration of more than 1400 mg / m3 under special working conditions such as the hydrogenation furnace tripping and the start-up and shutdown of the device, which cannot meet the requirements of the new national standard. It is determined to adopt the "post-alkali washing" process to carry out tail gas treatment. However, the original design of the natural gas purification plant has a compact equipment layout, and the distance from the waste heat boiler to the chimney is only 900 mm. After calculation, the flow area and construction space at this place are insufficient, and the tail gas cannot be drawn out from this place. The tail gas can only be drawn out by opening a hole in the chimney. In this embodiment, the chimney was built in 2013 and put into use at the end of 2014. It has been in operation for 8 years. The chimney is 120 meters high and the inner diameter of the chimney top is 1.6 meters. The chimney opening has a series of problems such as unclear internal structure, narrow working surface, scattered cylinder wall fillings, and cylinder strength assurance.

[0023] This embodiment is a method for transforming a natural gas purification tail gas treatment system. First, the chimney structure is determined. This embodiment involves a chimney body that is a reinforced concrete structure in the shape of a bull leg, with a total height of 120 meters, a layer every 10 meters, an outer diameter of 10.42 meters (inner diameter 8.7 meters) at a height of 0 meters, and an outer diameter of 2.62 meters (inner diameter 1.6 meters) at a height of 120 meters. The body is built from the outside to the inside with expanded perlite silica gel products, expanded perlite bulk, and special high-aluminum insulating refractory bricks. In order to smoothly carry out the "post-alkali method", it is necessary to use a pipeline to connect the chimney with the alkali washing tower, and return the tail gas after alkali washing to the chimney for discharge. Therefore, it is necessary to open a drainage hole and a reflux hole on the chimney. The drainage hole is used to introduce the tail gas in the chimney into the alkali washing tower, and the reflux hole is used to lead the tail gas after the alkali washing tower treatment back to the chimney.

[0024] After deciding to carry out the transformation: first verify the strength of the chimney, enter the chimney parameters in the PKPM software, and enter the drainage hole and return hole parameters, calculate whether the strength of the chimney after the holes are opened meets the requirements, and calculate the model in the software. The hole diameter is larger than the actual hole diameter during the calculation. Pre-calculate whether the chimney can meet the hole height and hole size to avoid chimney collapse or other safety hazards during the hole opening process.

[0025] Since it is actually necessary to open a drainage hole with a diameter of 1442mm at the elevation EL+4378 and a return hole with a diameter of 1340mm at the elevation EL7158, it is expected that during verification, a circular hole with a diameter of 2.5 meters will be opened at an elevation of 5 meters. A 2.5-meter circular hole will be opened at the elevation of 5 meters and above the original hole. The vertical load will be considered as 10 tons and the horizontal load will be considered as 3 tons.

[0026] In the PKPM calculation software, the calculation results are shown as follows: (1) The original foundation slab has a diameter of 17 meters and is located on moderately weathered sandstone. The foundation bearing capacity is 600 kPa. After calculation, the maximum foundation bearing capacity of 247 kPa is less than 600 kPa, which meets the requirements. The original slab steel bars are structural reinforcements with a diameter of 25@150. After calculation, the reinforcement is still structural reinforcement, and there is no need to reinforce the foundation.

[0027] (2) The original vertical reinforcement of the cylinder wall is 16~25@150 from top to bottom. After calculation, the reinforcement of the cylinder wall meets the requirements.

[0028] That is, it is feasible to open a 2.5-meter circular hole 5 meters above the chimney, and the chimney opening only needs to consider reinforcement measures at the opening, but the safety of the chimney structure must be evaluated first, and then the reinforcement plan can be determined.

[0029] Then proceed as follows: S1: Use protective opening method to open drainage holes 11 and return holes 12 at appropriate heights of the chimney: S1-1: Erection of external scaffolding of chimney; S1-2: Drilling holes on the chimney outer wall; S1-3: Erection of scaffolding inside chimney; S1-4: Removal of refractory bricks and insulation layer on the inner wall of the chimney.

[0030] The above steps S1-1 and S1-2 are implemented before the tail gas treatment system is shut down, which will not affect the original tail gas emissions. Steps S1-3 and S1-4 are implemented after the tail gas treatment system is shut down, which can reduce the impact time of the transformation on the tail gas treatment and minimize the impact of the transformation process on the normal production of natural gas.

[0031] S2: an alkali washing tower 5 and a first pipeline 3 are provided, one end of the first pipeline 3 extends into the drainage hole 11 and is connected to the chimney air inlet pipe 2, and the other end is connected to the alkali washing tower 5; S3: a second pipeline 4 is provided, wherein the second pipeline 4 is connected to the reflux hole 12 and is used for guiding the tail gas passing through the alkali washing tower 5 back to the chimney.

[0032] In order to shorten the construction period and reduce the impact on production capacity, we strengthened management and control through comprehensive evaluation, and pre-implemented "external opening" and external steel bonding reinforcement before shutdown. After the shutdown, we took pipe threading as the core basis and simultaneously implemented the three major processes of internal pipeline installation, external pipeline installation, and internal drilling and steel bonding, to achieve the "one core and three synchronizations" situation, so as to make full use of the working surface and significantly shorten the construction period. The device actually needs to be shut down for 16 days (excluding the start-up and shutdown time of the device).

[0033] The present embodiment provides a method for modifying a natural gas tail gas treatment system, by opening a drainage hole 11 and a reflux hole 12 on the chimney wall, extending a first pipe 3 from the drainage hole 11 and connecting it with the air inlet pipe 2 of the chimney, so that the tail gas enters the alkali washing tower 5 through the first pipe 3, and most of the sulfur dioxide in the flue gas is removed by alkali washing to reduce the sulfur dioxide content in the tail gas, and then the alkali-washed flue gas is returned to the chimney through the second pipe 4, and the tail gas is discharged into the air at high altitude through the chimney; the present application opens a hole in the chimney to extract the tail gas and return it to the chimney, thereby reducing the sulfur dioxide content in the tail gas and avoiding the phenomenon that the natural gas tail gas treatment system exceeds the standard of sulfur dioxide in the tail gas under special working conditions, and only the chimney is modified. Compared with changing the hydrogenation reduction process, there is no need to carry out large-scale demolition, destruction or reconstruction of existing equipment and pipelines, thereby reducing the modification cost of the tail gas treatment system.

[0034] Example 2 like Figure 3 and Figure 4 As shown, in this embodiment, the difference from Embodiment 1 is that the first pipeline 3 includes a connecting section 31 and a lead-out section 32, the connecting section 31 is connected to the end of the air inlet pipe 2, one end of the lead-out section 32 is connected to the connecting section 31, and the other end is connected to the alkali washing tower 5.

[0035] In the present embodiment, since the first pipe 3 needs to extend into the chimney and be connected to the pipe opening of the air intake pipe 2 in the chimney, the first pipe 3 is divided into sections, connected to the air intake pipe 32 through the connecting section 31, and the exhaust gas is led out through the lead-out section 32 connected to the connecting section 31, so that the installation of the first pipe 3 is easier and the construction difficulty of the first pipe 3 is reduced.

[0036] Furthermore, the end of the lead-out section 32 is sleeved on one end of the connecting section 31, and the overlapping portion of the two passes through the drainage hole 11. The lead-out section 32 and the connecting section 31 are connected in a sleeved manner. The drainage hole 11 can support the connecting section 31 and the lead-out section 32 at the same time, and no separate support is required, so that the connection operation of the lead-out section 32 and the connecting section 31 is simpler and it is convenient to fill elastic material between the two to offset the deformation that may occur in the pipe section due to heat.

[0037] Furthermore, a first flange 6 is sleeved on the connecting section 31, and the first flange 6 is used to close the gap between the end of the lead-out section 32 and the connecting section 31, so as to prevent the untreated exhaust gas in the intake pipe 2 from leaking through the gap between the lead-out section 32 and the connecting section 31 during the exhaust gas lead-out process, thereby causing sulfur dioxide leakage.

[0038] Furthermore, a second flange 7 is provided on the lead-out section 32, and the second flange 7 is used to close the gap between the lead-out section 32 and the drainage hole 11 to prevent the treated exhaust gas in the chimney from leaking through the gap between the lead-out section 32 and the drainage hole 11 and damaging the low-altitude environment around the chimney.

[0039] Furthermore, a third flange 9 is provided on the second pipe 4, and the third flange 9 is used to close the gap between the second pipe 4 and the reflow hole 12 to prevent the treated exhaust gas in the chimney from leaking through the gap between the second pipe 4 and the reflow hole 12 and damaging the low-altitude environment around the chimney.

[0040] The first flange 6, the second flange 7 and the third flange 9 all include end plates and connecting plates. The end plates and the connecting plates enclose the joints at the joints to form a seal, and the enclosed space is filled with a refractory fiber blanket.

[0041] Furthermore, one end of the connecting section 31 close to the lead-out section 32 is wrapped with refractory fiber paper 33. Since the exhaust gas temperature is relatively high, thermal expansion will occur to the pipe during the circulation in the first pipe 3. The connecting section 31 and the lead-out section 32 are sealed with refractory fiber paper 33, and the pipe sections expand and slide against each other, thereby fully reducing the impact of thermal stress on the chimney.

[0042] Example 3 like Figure 1 As shown, the difference between this embodiment and embodiment 1 is that during the steps S1-2 and S1-3, the chimney wall is protected by pressure injection.

[0043] In this embodiment, polyurethane or other high-temperature resistant Class II structural adhesive is added to reduce the scattering of silicone plates and pearl sand in the chimney wall during the construction process, thereby reducing the damage to the chimney structure caused by the hole opening process.

[0044] Example 4 like Figure 3 , Figure 4 and Figure 5 As shown, the present embodiment differs from Embodiment 1 in that it further includes step S1-4, wherein a steel sleeve 8 is nested in the hole wall of the reflow hole 11 and the hole wall of the drainage hole 12, and a refractory fiber blanket 81 is laid on the inner wall of the steel sleeve 8.

[0045] In this embodiment, the steel sleeve 8 supports and protects the hole wall, improves the structural strength of the chimney after the hole is opened, and reduces the influence of the drainage hole 11 and the return hole 12 on the chimney strength. The refractory fiber blanket 81 has certain expansion and contraction properties. When the first pipe 3 or the second pipe 4 undergoes thermal expansion, it can adapt to the deformation of the pipe through its own contraction and deformation, thereby reducing the influence of the thermal deformation of the pipe on the chimney structure.

[0046] Example 5 like Figure 6 As shown, this embodiment is different from Embodiment 1 in that it further includes step S1-5, wherein a supporting steel plate frame 10 is arranged between the reflux hole 11 and the drainage hole 12, and the supporting steel plate frame 10 includes two straight plates 101 arranged crosswise to each other.

[0047] In this embodiment, the supporting steel plate frame 10 improves the structural strength of the chimney wall between the drainage hole 11 and the return hole 12, improves the structural strength of the chimney after the holes are opened, ensures the safe use of the chimney, and drilling operations are performed on the inner and outer walls of the chimney in advance. After the drilling is completed, the supporting steel plate frame 10 is fixed to the chimney wall by bolts.

[0048] Example 6 like Figure 1 As shown, in this embodiment, the difference from Embodiment 1 is that an identification step is provided before and after the entire transformation step: detecting whether various indicators of the chimney meet the requirements.

[0049] In this embodiment, by setting up identification steps before and after the renovation, it is ensured that all indicators of the chimney can meet the standards before and after the renovation, thereby ensuring the safety of the renovation process and subsequent use of the chimney.

[0050] Specifically, the identification steps include: (1) Use a steel bar position measuring instrument and a steel bar corrosion tester to test the various properties of the steel bars; (2) Use a total station to detect the chimney inclination; (3) Use a thickness detector to test the thickness of the chimney; (4) Use crack observation instruments, crack depth observation instruments, and crack width observation instruments to detect cracks in concrete components; (5) Use a brick rebound tester to test the strength of bricks; (6) Use SJY-800B penetration mortar strength tester to test the mortar strength; (7) Use a carbonation depth tester to test the carbonization of concrete; (8) The strength of concrete components is tested using the core drilling method and the rebound method.

[0051] After completing the above identification steps, the scaffolding will be removed.

[0052] Example 7 like Figure 2 , Figure 3 and Figure 6As shown, the present embodiment provides a natural gas production exhaust gas treatment device, such as an exhaust gas treatment device formed by a natural gas exhaust gas treatment system modification method as described in any one of Examples 1-6, comprising a chimney body 1, a first pipeline 3, a second pipeline 4 and an alkali washing tower 5, the chimney body 1 is connected to an air inlet pipe 2, the side wall of the chimney body 1 is provided with a drainage hole 11 and a reflux hole 12, the first pipeline 3 extends into the drainage hole 11 and is connected to the air inlet pipe 2, the second pipeline 4 is connected to the reflux hole 12, the air inlet end of the alkali washing tower 5 is connected to the first pipeline 3, and the air outlet end is connected to the second pipeline 4.

[0053] When in use, the tail gas enters the first pipeline 3 through the air inlet pipe, and then enters the alkali washing tower 5, and is then led back to the chimney through the second pipeline 4. Under special working conditions, the sulfur dioxide in the tail gas that has not been completely treated is secondary treated in the alkali washing tower, avoiding large-scale transformation of the existing tail gas treatment system and reducing the cost of natural gas production.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for transforming a natural gas purification tail gas treatment system, characterized in that: The steps include: S1: adopting a protective opening method, opening a drainage hole (11) and a return hole (12) at a suitable height of the chimney; S2: an alkali washing tower (5) and a first pipeline (3) are provided, wherein one end of the first pipeline (3) extends into the drainage hole (11) and is connected to the chimney air inlet pipe (2), and the other end is connected to the inside of the alkali washing tower (5); S3: a second pipe (4) is provided, wherein the second pipe (4) is connected to the reflux hole (12) and is used to guide the tail gas passing through the alkali washing tower (5) back to the chimney.

2. The method for modifying a natural gas purification tail gas treatment system according to claim 1, characterized in that: In S1, the protective opening method includes the following steps: S1-1: Erection of external scaffolding of chimney; S1-2: opening on the chimney outer wall; S1-3: Erection of scaffolding inside chimney; S1-4: Removal of refractory bricks and insulation layer on the inner wall of the chimney.

3. The method for modifying a natural gas purification tail gas treatment system according to claim 1, characterized in that: The first pipeline (3) comprises a connecting section (31) and a lead-out section (32), the connecting section (31) being connected to the end of the air inlet pipe (2), and the lead-out section (32) having one end connected to the connecting section (31) and the other end connected to the alkali washing tower (5).

4. The method for modifying a natural gas purification tail gas treatment system according to claim 3, characterized in that: The end of the lead-out section (32) is sleeved on one end of the connecting section (31), and the overlapping portion of the two passes through the drainage hole (11).

5. The method for modifying a natural gas purification tail gas treatment system according to claim 4, characterized in that: One end of the connecting section (31) close to the lead-out section (32) is wrapped with fire-resistant fiber paper (33).

6. The method for modifying a natural gas purification tail gas treatment system according to claim 2, characterized in that: During steps S1-2 and S1-4, the chimney wall is protected by injecting polyurethane.

7. The method for modifying a natural gas purification tail gas treatment system according to claim 2, characterized in that: The step also includes step S1-5, wherein a steel sleeve (8) is nested in the hole wall of the return hole (12) and the hole wall of the drainage hole (11), and a refractory fiber blanket (81) is laid on the inner wall of the steel sleeve (8).

8. The method for modifying a natural gas purification tail gas treatment system according to claim 7, characterized in that: The method further comprises step S1-6, wherein a supporting steel plate frame (10) is arranged between the reflow hole (12) and the drainage hole (13), wherein the supporting steel plate frame (10) comprises two straight plates (101) arranged crosswise to each other.

9. The method for modifying a natural gas purification tail gas treatment system according to claim 2, characterized in that: In S, before opening the drainage holes and the return holes, the chimney parameters are input into the PKPM software, and the drainage hole (11) and the return hole (12) parameters are input to calculate whether the strength of the chimney after the holes are opened meets the requirements.

10. A natural gas production tail gas treatment device, characterized in that: A tail gas treatment device formed by a natural gas tail gas treatment system modification method according to any one of claims 1 to 9, comprising a chimney body (1), a first pipeline (3), a second pipeline (4) and an alkali washing tower (5), wherein the chimney body (1) is connected to an air inlet pipe (2), and a drainage hole (11) and a reflux hole (12) are provided on the side wall of the chimney body (1), the first pipeline (3) extends into the drainage hole (11) and is connected to the air inlet pipe (2), the second pipeline (4) is connected to the reflux hole (12), and the air inlet end of the alkali washing tower (5) is connected to the first pipeline (3), and the air outlet end is connected to the second pipeline (4).

Images