LNG storage tank expanded perlite online filling method

Abstract

The application provides an LNG storage tank expanded perlite online filling method, comprising the following steps: S1, judging the expanded perlite settlement height; S2, establishing an expanded perlite theoretical filling amount calculation model; S3, delivering the expanded perlite to the filling position through a filling system; and S4, measuring the expanded perlite filling height after filling. The application is safe in operation, avoids overfilling, and achieves the filling requirements and expected effects.

Description

TECHNICAL FIELD

[0001] The present application relates to liquefied natural gas cryogenic storage technology field, especially to a LNG storage tank expansion perlite online filling method. BACKGROUND

[0002] Large LNG storage tank is the most important facility of LNG receiving station and also the highest investment single facility. The LNG storage tank adopts expansion perlite for heat insulation and cold preservation to keep the cold preservation performance of the LNG storage tank to meet the design requirements.

[0003] With the extension of the operation cycle, the cold preservation expansion perlite will be unevenly settled to a certain extent, which will affect the cold preservation performance of the storage tank, and will cause brittleness of the carbon steel of the inner wall of the outer tank of the storage tank, and will shorten the service life of the storage tank. In order to avoid the brittleness of the inner wall of the outer tank of the storage tank caused by low temperature, the storage tank will be seriously damaged and the cold preservation performance of the storage tank will be reduced, which will increase the BOG evaporation amount, so it is necessary to fill the expansion perlite of the storage tank in time.

[0004] When the expansion perlite of the LNG storage tank in service is settled and filled, the tank pressure needs to be reduced to below the lower limit value, which will cause large power consumption loss, large BOG loss of the storage tank, safety risk of low-temperature gas leakage during operation, and problems and difficulties caused by tank pressure control affecting normal unloading plan. If the LNG storage tank is in an online state, personnel cannot enter the inside of the storage tank to measure, which will cause overfilling. SUMMARY

[0005] The purpose of the present application is to provide a LNG storage tank expansion perlite online filling method which can avoid energy loss and solve the problem of overfilling.

[0006] The present application provides a LNG storage tank expansion perlite online filling method, which comprises the following steps:

[0007] S1, judging the settlement height of the expansion perlite;

[0008] S2, establishing a theoretical filling amount calculation model of the expansion perlite;

[0009] S3, transporting the expansion perlite to the filling position through a filling system;

[0010] S4, measuring the height of the expansion perlite after filling.

[0011] Further, in S1, the settlement position of the expansion perlite of the storage tank is measured by infrared thermal imaging technology and an outer tank scale.

[0012] Further, the 360° thermal imaging scanning of the outer wall of the storage tank is performed at a distance of not less than 20 meters from the outer wall of the storage tank, and a photograph is taken for each filling port, and meanwhile, a person stands at the filling port for photographing and places a scale along the outer wall of the tank, and according to the temperature difference position displayed on the thermal imager and the scale, the sinking height of each filling port is marked.

[0013] Further, after measuring the sinking height of each filling port, finite element analysis of the expansion perlite settlement of the LNG storage tank is performed in combination with the architectural drawings of the LNG storage tank.

[0014] Further, the theoretical filling amount calculation model of the expansion perlite is established on the basis of the finite element analysis.

[0015] Further, the filling space is divided into five regions according to the theoretical filling amount calculation model of the expansion perlite.

[0016] Further, the volume of the first region is:

[0017] The volume of the second region is:

[0018] The volume of the third region is:

[0019] The volume of the fourth region is:

[0020] The volume of the fifth region is:

[0021] In the formula:

[0022] R1 is the distance from the center of the storage tank to the glass fiber elastic cotton felt wall, in meters (m);

[0023] R2 is the distance from the center of the storage tank to the left bottom edge of the first region, in meters (m);

[0024] R3 is the distance from the center of the storage tank to the center of the expansion perlite filling port, in meters (m);

[0025] R4 is the radius of the inner tank of the storage tank, in meters (m);

[0026] R5 is the radius of the inner tank of the storage tank + the thickness of the annular space glass fiber elastic cotton felt, in meters (m);

[0027] R6 is the distance from the center of the storage tank to the inner wall of the outer tank, in meters (m);

[0028] H1 is the average height of the first region, in meters (m);

[0029] H2 is the average height of the second region, in meters (m);

[0030] H3 - average height of the third region, in meters (m);

[0031] H4 - average height of the fourth region, in meters (m);

[0032] H5 - average height of the fifth region, in meters (m).

[0033] Further, the filling system in S3 comprises a transfer tank connected with the LNG storage tank through a conveying pipeline, a nitrogen gas pocket is connected with the transfer tank, one end of the conveying pipeline is installed at the bottom of the transfer tank, and the other end of the conveying pipeline is installed on the ball valve of the filling port at the top of the LNG storage tank.

[0034] Further, the conveying pipeline is a transparent anti-static high-wear pipeline, a start control box is installed on the nitrogen gas pocket, and a nitrogen gas source is connected with the gas inlet end of the nitrogen gas pocket.

[0035] Further, a height measuring device is installed at the filling port, the height measuring device comprises a sealed shell and a tape measure, the tape measure is installed inside the sealed shell, a weight is installed at the telescopic end of the tape measure, and the telescopic end of the tape measure is vertically inserted into the LNG storage tank through the filling port; in S4, the height after the expanded perlite filling is measured by the height measuring device.

[0036] The present application is safe in operation, avoids personnel entering the inside of the storage tank, avoids overfilling, and achieves the requirements and expected effects of the filling. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the specific embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0038] Fig. 1 is the step diagram of the present application;

[0039] Fig. 2 is the filling space sectional view of the present application;

[0040] Fig. 3 is the filling system schematic diagram of the present application;

[0041] Explanation of reference signs:

[0042] In the figure: 1-LNG storage tank, 11-outer wall, 12-inner tank, 13-elastic cotton felt, 14-glass wool insulation layer, 15-glass cloth retaining wall, 2-expanded perlite, 21-first area, 22-second area, 23-third area, 24-fourth area, 25-fifth area, 3-conveying pipeline, 4-transporting tank, 5-nitrogen gas pocket, 51-starting control box, 52-gas conveying pipeline, 6-filling port, 61-ball valve; DETAILED DESCRIPTION

[0043] The technical solutions of the present application will be described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0044] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like indicate the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0045] In addition, the terms "first" and "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the present application, "a plurality of" means two or more, unless otherwise explicitly specified. In addition, the terms "mounting", "connecting", "connecting" should be broadly understood, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0046] Example 1

[0047] As Figs. 1-3 shown:

[0048] The method comprises the following steps: S1, judging the settlement height of the expanded perlite 2; S2, establishing a theoretical expanded perlite filling amount calculation model; S3, delivering the expanded perlite to the filling position through a filling system; and S4, measuring the height of the expanded perlite after filling.

[0049] As shown in Fig. 2 and Fig. 3 , the LNG storage tank 1 comprises an inner tank 12 and an outer concrete wall 11, the expanded perlite 2 is filled between the inner tank 12 and the outer wall 11, the outer wall of the inner tank 12 is further provided with a glass fiber elastic cotton felt 13, the top of the inner tank 12 is provided with a glass cotton insulation layer 14 and a glass blanket retaining wall 15, so that the filling space of the expanded perlite 2 is annular, and the outer wall 11 is provided with 38 filling ports 6 arranged in a ring shape and extending to the filling space.

[0050] Since the storage tank 1 has been put into operation, the storage tank 1 cannot be opened for surveying, and there is no peeping system and monitoring facility inside the storage tank 1, so it is impossible to judge the settlement of the expanded perlite 2 in the annular space of the storage tank 1 and the influence on the internal structure of the storage tank 1.

[0051] Therefore, in S1, the settlement position of the expanded perlite 2 of the storage tank 1 is measured by means of infrared thermal imaging technology and an outer tank scale.

[0052] The 360° thermal imaging scanning of the outer wall of the storage tank 1 is performed at a distance of more than 20 meters from the outer wall of the storage tank 1, and each filling port 6 is photographed, and at the same time, a person stands at the filling port 6 for photographing and places a scale along the outer tank wall. According to the temperature difference position displayed on the thermal imager combined with the scale of the scale, the settlement height of each filling port 6 is marked.

[0053] Selecting 38 points (each filling port 6 corresponds to one photographing point) for photographing can cover all the horizontal areas. The specific orientation, area, degree, distribution state of the cold leakage and the settlement position of the expanded perlite 2 of the storage tank 1 are accurately checked, and a scientific basis is provided for the next filling work.

[0054] In S2, after measuring the settlement height of each filling port 6, the finite element analysis of the settlement of the expanded perlite 2 of the LNG storage tank 1 is performed in combination with the architectural drawings of the LNG storage tank 1.

[0055] In S3, the theoretical expanded perlite filling amount calculation model is established on the basis of the finite element analysis.

[0056] As shown in Fig. 2As shown, according to the theoretical filling amount calculation model of expanded perlite 2, the filling space is divided into five regions, namely, first region 21, second region 22, third region 23, fourth region 24 and fifth region 25. Although the surface of the settled expanded perlite 2 has concave-convex, the range is small, the surface is almost flat, and the error is negligible.

[0057] The volumes of the five regions are respectively:

[0058] The volume of the first region 21 is:

[0059] The volume of the second region 22 is:

[0060] The volume of the third region 23 is:

[0061] The volume of the fourth region 24 is:

[0062] The volume of the fifth region 25 is:

[0063] In the formula:

[0064] R1 - the distance between the center of the storage tank 1 and the glass surrounding cloth retaining wall 15 of the expanded perlite 2, in meters (m);

[0065] R2 - the distance between the center of the storage tank 1 and the left bottom edge of the first region 21, in meters (m);

[0066] R3 - the distance between the center of the storage tank 1 and the center of the filling port 6 of the expanded perlite 2, in meters (m);

[0067] R4 - the radius of the inner tank 12 in the storage tank 1, in meters (m);

[0068] R5 - the radius of the inner tank 12 in the storage tank 1 + the thickness of the annular space glass fiber elastic cotton felt 13, in meters (m);

[0069] R6 - the distance between the center of the storage tank 1 and the inner wall of the outer tank, in meters (m);

[0070] H1 - the average height of the first region 21, in meters (m);

[0071] H2 - the average height of the second region 22, in meters (m);

[0072] H3 - the average height of the third region 23, in meters (m);

[0073] H4 - the average height of the fourth region 24, in meters (m);

[0074] H5 – The average height of Zone 25, in meters (m).

[0075] The total volume of all filling ports 6 is V = V1 + V2 + V3 + V4 + V5.

[0076] like Fig. 3 As shown, the filling system in S3 includes a transfer tank 4 connected to the LNG storage tank 1 via a conveying pipe 3. The transfer tank 4 is connected to a nitrogen gas tank 5 via a gas conveying pipe 52. One end of the conveying pipe 3 is installed at the bottom of the transfer tank 4, and the other end of the conveying pipe 3 is installed on the ball valve 61 of the filling port 6 at the top of the LNG storage tank 1.

[0077] The conveying pipeline 3 is a transparent, anti-static, and highly wear-resistant pipeline. If the expanded perlite 2 becomes blocked, the location of the expanded perlite 2 can be determined in a timely and accurate manner. The nitrogen gas tank 5 is equipped with a start-up control box 51, and the inlet end of the nitrogen gas tank 5 is connected to a nitrogen gas source.

[0078] The gas transmission pipeline 52 and the delivery pipeline 3 are also equipped with pressure transmitters, regulating valves and other components, which are sufficient to enable the pipeline to be connected and shut down, and will not be elaborated on here.

[0079] Through research on the impact of different nitrogen delivery pressures on the performance of expanded perlite 2 products and on the filling efficiency under different nitrogen delivery pressures and delivery distances, it was found that when the pressure of LNG storage tank 1 is 15-20 kPa, the nitrogen delivery pressure is 35-50 kPa.

[0080] In this embodiment, the following parameters were calculated:

[0081] The filling space volume of the first area 21 is 233.22 cubic meters, and its actual filling volume is approximately 326.51 cubic meters of filling material.

[0082] The filling space volume of the second area 22 is 36.1 cubic meters, and its actual filling volume is approximately 50.54 cubic meters of filling material.

[0083] The filling space volume of the third area 23 is 742.74 cubic meters, and the actual filling material delivered is about 1039.84 cubic meters.

[0084] The filling space volume of the fourth zone 24 is 167 cubic meters, and the actual filling material delivered is approximately 233.8 cubic meters.

[0085] The filling space volume of Zone 25 is 105.77 cubic meters, and the actual filling volume delivered is approximately 148.01 cubic meters of filling material;

[0086] The total calculated filling space volume is 1284.83 cubic meters, and the actual total filling volume delivered is approximately 1798.76 cubic meters.

[0087] The nitrogen is used as a driving source to transport the expanded perlite 2 to carry out the filling, and the theoretical filling amount of the expanded perlite is the total amount of the expanded perlite 2 and the nitrogen, which is calculated to be about 1.4 times of the filling space volume.

[0088] The height measuring device is installed at the filling port 6, and the height measuring device comprises a sealed shell and a tape measure, the tape measure is installed inside the sealed shell, a weight is installed at the telescopic end of the tape measure, and the telescopic end of the tape measure is vertically inserted into the LNG storage tank 1 through the filling port 6; in S4, the height of the expanded perlite 2 after filling is measured by the height measuring device, and the data is recorded after the measurement, and the online filling work is completed.

[0089] The application is safe in operation, replaces the traditional method of measuring the pressure reduction of the storage tank, reduces the energy consumption, avoids the personnel entering the inside of the storage tank, avoids the abnormal conditions such as overfilling and the expanded perlite entering the inner tank, and achieves the filling requirements and the expected effect.

[0090] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the application, but not to limit them; although the application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the application.

Claims

1. A method for online filling of expanded perlite for LNG storage tanks, characterized in that, The method comprises the following steps: S1, judging the settling height of expanded perlite, measuring the settling position of the expanded perlite in the storage tank by infrared thermal imaging technology and the way of the scale outside the tank, performing 360° thermal imaging scanning on the outer wall of the storage tank at a distance not less than 20 meters, taking a photo of each filling port, and at the same time, one person stands at the filling port for taking the photo and places a scale along the outer wall of the tank, and according to the temperature difference position displayed on the thermal imager and the scale, the settling height of each filling port is marked; S2, establishing a theoretical expanded perlite filling amount calculation model, after measuring the settling height of each filling port, the finite element analysis of the settling of the expanded perlite in the LNG storage tank is performed in combination with the architectural drawings of the LNG storage tank; S3, transporting the expanded perlite to the filling position through a filling system, the theoretical expanded perlite filling amount calculation model is established on the basis of the finite element analysis, and the filling space is divided into five regions according to the theoretical expanded perlite filling amount calculation model; The volumes of the five regions are respectively: volume of the first region: ; Volume of the second region: ; Volume of the third region: ; Volume of the fourth region: ; Volume of the fifth region: ; In the formula: R1 is the distance between the center of the tank and the expanded perlite glass surrounding cloth retaining wall, in meters (m); R2 is the distance between the center of the tank and the left bottom edge of the first region, in meters (m); R3 is the distance between the center of the tank and the center of the expanded perlite filling port, in meters (m); R4 is the radius of the inner tank of the tank, in meters (m); R5 is the radius of the inner tank of the tank + the thickness of the annular space glass fiber elastic cotton felt, in meters (m); R6 is the distance between the center of the tank and the inner wall of the outer tank, in meters (m); H1 is the average height of the first region, in meters (m); H2 is the average height of the second region, in meters (m); H3 is the average height of the third region, in meters (m); H4 is the average height of the fourth region, in meters (m); H5 is the average height of the fifth region, in meters (m); S4, measuring the height of the expanded perlite after filling.

2. The LNG storage tank expanded perlite on-line replenishment method according to claim 1, characterized by, The filling system in S3 comprises a moving feed tank connected with the LNG storage tank through a conveying pipeline, a nitrogen gas bag connected with the moving feed tank, one end of the conveying pipeline is installed at the bottom of the moving feed tank, and the other end of the conveying pipeline is installed on the ball valve of the filling port at the top of the LNG storage tank.

3. The LNG storage tank expanded perlite on-line replenishment method according to claim 2, characterized by, The conveying pipeline is a transparent anti-static high-wear pipeline, a start control box is installed on the nitrogen gas bag, and a nitrogen gas source is connected with the gas inlet end of the nitrogen gas bag.

4. The LNG storage tank expanded perlite on-line replenishment method according to claim 2, characterized by, A height measuring device is installed at the filling port, the height measuring device comprises a sealed housing and a tape measure, the tape measure is installed inside the sealed housing, a weight is installed at the telescopic end of the tape measure, and the telescopic end of the tape measure is vertically extended into the LNG storage tank through the filling port; in S4, the height of the expanded perlite after filling is measured through the height measuring device.

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