Nondestructive testing method for all-round hard scale of process pipeline of natural gas desulfurization device

Abstract

The invention relates to the technical field of deposited scale detection, in particular to a nondestructive detection method for all-round hard scale of a process pipeline of a natural gas desulfurization device. The boundary between the outer wall of the metal pipeline and air is clear, and the boundary between the inner wall of the metal pipeline and dirt is not clear; scale is tightly attached to the inner wall of the pipeline and is deep in color, and the scale and rich liquid boundary is a line parallel to the edge of the outer wall of the pipeline and can be recognized. And measuring the total thickness of the metal pipe wall and the scale by adopting DR distance measurement software, and calculating the thickness of the deposited scale according to the total thickness of the metal pipe wall and the scale and the thickness of the metal pipe wall. According to the invention, the DR and EMAT nondestructive testing method is adopted to measure the thickness of the full-circumferential hard scale in the rich liquid pipeline under the condition of no shutdown and no pipe opening, and technical support can be provided for the blocking degree of deposited scale. Huge economic loss of enterprises caused by shutdown and pipe opening is avoided, and the gas production rate of the enterprises is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of deposited scale detection, and in particular to a non-destructive detection method for full-circumference hard scale in a process pipeline of a natural gas desulfurization device. Background Art

[0002] After extraction, sour natural gas is typically desulfurized in-situ using single-well desulfurization stations to reduce corrosion on pipelines. Complex iron wet desulfurization technology offers significant advantages in natural gas desulfurization and purification. However, the sulfur and secondary salts produced by the desulfurization process can, under certain conditions, form a circumferential hard scale, often blocking the desulfurization unit's process piping, leading to unplanned downtime and significant economic losses for the company. Desulfurization unit process piping is typically constructed of corrosion-resistant austenitic stainless steel, a non-ferromagnetic material. This hard scale typically forms a circumferential scale, adhering to the pipe wall with minimal variation in thickness around the pipe. The surface is rough and non-dense, with a density of approximately 1.91 g / ml. The pipe is made of austenitic stainless steel, with a density of approximately 7.85 g / ml, while the density of the rich liquid medium is approximately 1 g / ml. The pipe diameter is approximately 150 mm, with a wall thickness of approximately 5 mm.

[0003] Existing technology, electromagnetic ultrasonic testing (EMAT), can measure pipe wall thickness. However, because circumferential scale is non-conductive and relatively coarse, EMAT cannot directly measure circumferential scale thickness and can only be used to measure pipe wall thickness. Currently, circumferential scale thickness is typically measured directly with measuring tools after shutting down the pipeline, which can cause significant economic losses to companies. To avoid unplanned downtime caused by circumferential scale blockage, it is crucial to understand the circumferential scale thickness without shutting down the pipeline or opening the pipe. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a non-destructive testing method for the circumferential hard scale in the process pipeline of a natural gas desulfurization device, which can quantify the thickness of the circumferential hard scale without shutting down the machine or opening the pipe.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is: A nondestructive detection method for all-round hard scale in a process pipeline of a natural gas desulfurization device is provided, which comprises the following steps: S1. Determination of the full-circumference hard scale detection location: Based on the historical data of pipeline blockage caused by scale deposition, the location with a slow flow rate upstream of the rich liquid pipeline is selected as the full-circumference hard scale detection location; S2. Pipe wall thickness detection: Use ultrasonic thickness measurement technology to measure the metal pipe wall thickness in all directions of the full-circumference hard scale detection position; S3. DR detection of all-around hard scale: While ensuring clear display with the thickest dual-wire image quality meter, obtain a resolvable DR image by optimizing the tube voltage, tube current, and number of iterations, taking the imaging quality of the deposited scale as the standard. S4. DR imaging feature recognition of all-around hard scale: The boundary between the outer wall of the metal pipe and the air is clear, while the boundary between the inner wall of the metal pipe and the scale is unclear. The scale adheres closely to the inner wall of the pipe and is darker in color. The boundary between the scale and the rich liquid is a line parallel to the edge of the outer wall of the pipe and can be identified. S5. Quantification of the thickness of the full-circumference hard scale: Use DR distance measurement software to measure the total thickness δt of the metal pipe wall and the scale; calculate the thickness δ of the deposited scale based on the total thickness δt of the metal pipe wall and the scale and the metal pipe wall thickness δw.

[0006] Furthermore, in step S2, a double-wall vertical radiography method is used to photograph the inspection part of the process pipeline; the image quality meter uses a double-wire image quality meter, and the distance between the radiation source and the pipeline should ensure that the radiation penetrates twice the pipe wall. While ensuring that the thickest wire can be displayed, the X-ray tube voltage is reduced and the number of iterations is increased to obtain the best imaging effect of deposited scale.

[0007] The beneficial effects of the present invention are: This method uses DR (X-ray Digital Imaging Technology) and EMAT nondestructive testing to measure the thickness of hard scale around the entire circumference of a liquid-rich pipeline without shutting down the plant or opening the pipeline. This provides technical support for determining the extent of scale blockage, avoiding the significant economic losses that would result from shutting down the pipeline and ensuring gas production. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 Flow chart of the method of the present invention; Figure 2 Schematic diagram of the pipe wall thickness detection position in the embodiment; Figure 3 Schematic diagram of the double-wall double-shadow transillumination technology in the embodiment; Figure 4 Schematic diagram of the full-circle hard scale characteristics of DR in the embodiment; Figure 5 This is the DR imaging feature of the all-around hard scale in the example. DETAILED DESCRIPTION

[0009] The specific embodiments of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the concepts of the present invention are protected.

[0010] Example Reference Figure 1 A nondestructive detection method for all-round hard scale in a natural gas desulfurization unit process pipeline comprises the following steps: Step 1. Determine the location for full-circle hard scale detection. Based on historical data on blockage caused by scale deposits in single-well desulfurization units, select a location upstream of the rich liquid pipeline of the desulfurization unit (such as the absorption tower, spray tower, or flash separator) where the flow rate is relatively slow.

[0011] Step 2. Pipe wall thickness detection. Use EMAT technology or other ultrasonic thickness measurement technology to measure the pipe wall thickness in all directions of the detection position. The measurement position should cover all directions as much as possible, such as Figure 2 shown.

[0012] Step 3. DR detection of all-around hard scale Since the pipe diameter range is usually around 150mm, this embodiment adopts the double-wall vertical transillumination method. According to the placement of the flat panel detector, it is divided into horizontal shooting and vertical shooting, and the thickness of the deposited scale is transilluminated from two vertical directions. The transillumination method is as follows: Figure 3 As shown in the figure, a dual-filament image quality meter should be used. The distance between the X-ray source and the pipe should ensure that the X-ray penetrates twice the pipe wall. While ensuring that the thickest filament can be displayed, the X-ray tube voltage should be reduced and the number of iterations increased to obtain the best imaging effect of deposited scale.

[0013] Specifically for the full-circle hard scale in the process pipeline of the natural gas desulfurization device of this application, the specific parameters of DR detection are: voltage 150 kV to 280 kV, current 0.5 mA to 3 mA, exposure time: 1 second to 3 seconds, number of iterations 4 times, focal length 600 mm to 1000 mm.

[0014] 4. DR image feature recognition method for all-round hard scale The full-circle hard scale usually grows evenly along the inner wall of the pipe. Due to the different absorption of radiation by the scale, metal pipe wall and rich liquid medium, the intensity of the X-ray reaching the flat panel detector is also different, so the grayscale of the DR image is also different. The boundary line between the full-circle hard scale layer and the rich liquid medium is parallel to the line on the outer wall of the pipe, such as Figure 4 shown.

[0015] However, in the actual detection process, due to the uneven surface of the full-circumference hard scale, the boundary line between the full-circumference hard scale and the rich liquid medium in the thickness direction is a zigzag line, which is roughly parallel to the edge line of the pipe outer wall. The color is darker when it is close to the pipe outer wall. The deposited scale on the side of the pipe will also be DR imaged. The edge line is irregular and lighter when it is far away from the pipe wall. Figure 5 shown.

[0016] Therefore, the DR imaging characteristics of full-circumferential hard scale are: the boundary between the outer wall of the metal pipe and the air is clear, and the boundary between the inner wall of the metal pipe and the scale is unclear; the scale is close to the inner wall of the pipe and has a darker color. The boundary between the scale and the rich liquid is a line roughly parallel to the edge of the outer wall of the pipe and can be identified.

[0017] 5. Quantitative method for full-circumference hard scale thickness Based on the imaging characteristics of full-circumference hard scale, the boundary between the metal pipe wall and the air is clear, while the boundary between the inner metal pipe wall and the scale is difficult to identify. However, the boundary between the scale and the rich liquid is easily discernible. Therefore, the DR distance measurement software cannot directly select the scale thickness; it can only measure the total thickness δt of the metal pipe wall and scale.

[0018] The thickness of the metal pipe wall δw can be measured using the EMAT method. The difference between the two is the thickness of the deposited scale δ, which is expressed as follows (1): δ = δt - δw (1) A single DR radiographic image is only a planar projection of the pipeline, guaranteeing coverage of only two sides of the pipeline perpendicular to the radiation, such as the top and bottom sides or the left and right sides. The total thickness in each of the four directions can be measured. Based on the metal wall thickness at the corresponding locations measured by EMAT, the deposited scale thickness in each of the four directions can be determined. The maximum deposited scale thickness is used as the deposited scale thickness at the test location.

[0019] This invention uses DR and EMAT nondestructive testing methods to measure the thickness of circumferential hard scale within the rich liquid pipeline without shutting down the machine or opening the pipe. This provides technical support for determining the degree of blockage caused by deposited scale, avoids the huge economic losses that would otherwise be incurred by shutting down the machine and opening the pipe, and ensures the company's gas production.

[0020] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

[0021] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A non-destructive testing method for all-round hard scale in the process pipeline of a natural gas desulfurization device, characterized in that: The following steps are involved: S1. Determination of the full-circumference hard scale detection location: Based on the historical data of pipeline blockage caused by scale deposition, the location with slow flow velocity upstream of the rich liquid pipeline is selected as the full-circumference hard scale detection location; S2. Pipe wall thickness detection: Use ultrasonic thickness measurement technology to measure the thickness of the metal pipe wall in all directions of the full-circumference hard scale detection position; S3. DR detection of all-around hard scale: While ensuring clear display with the thickest dual-wire image quality meter, obtain a resolvable DR image by optimizing the tube voltage, tube current, and number of iterations, taking the imaging quality of the deposited scale as the standard. S4. DR imaging feature recognition of all-around hard scale: The boundary between the outer wall of the metal pipe and the air is clear, while the boundary between the inner wall of the metal pipe and the scale is unclear. The scale adheres closely to the inner wall of the pipe and is dark in color. The boundary between the scale and the rich liquid is a line parallel to the edge of the outer wall of the pipe and can be identified. S5. Quantification of full-circumferential hard scale thickness: Use DR distance measurement software to measure the total thickness of the metal pipe wall and scale; calculate the thickness of the deposited scale based on the total thickness of the metal pipe wall and scale and the thickness of the metal pipe wall.

2. The nondestructive testing method for all-round hard scale in the process pipeline of a natural gas desulfurization device according to claim 1 is characterized in that: In step S2, a double-wall vertical radiography method is used to photograph the inspection part of the process pipeline; a double-wire image quality meter is used, and the distance between the radiation source and the pipeline should ensure that the radiation penetrates twice the pipe wall. While ensuring that the thickest wire can be displayed, the X-ray tube voltage is reduced and the number of iterations is increased to obtain the best imaging effect of deposited scale.

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