CN215462543U

CN215462543U - Low-temperature liquid filtering device arranged in cold box and low-temperature system comprising same

Info

Publication number: CN215462543U
Application number: CN202121984346.1U
Authority: CN
Inventors: 阿兰·布里格利亚
Original assignee: LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Current assignee: LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Priority date: 2021-08-23
Filing date: 2021-08-23
Publication date: 2022-01-11
Anticipated expiration: 2031-08-23

Abstract

The utility model discloses a low-temperature liquid filtering device arranged in a cold box and a low-temperature system comprising the same. This filter equipment installs on rotating equipment upper reaches pipeline, it sets up in the cold box to rotate equipment, and this filter equipment contains casing and cap, and its casing extends to the cold box outside from the cold box to be connected with the cap outside the cold box, can conveniently carry out filter equipment's maintenance through dismantling the cap. The casing is additionally connected with an exhaust pipe, so that the gas in the filtering device is prevented from being wrapped and entering downstream rotating equipment due to excessive accumulation, and the downstream rotating equipment such as a low-temperature pump and the like is protected.

Description

Low-temperature liquid filtering device arranged in cold box and low-temperature system comprising same

Technical Field

The utility model relates to a filtering device for low-temperature liquid arranged in a cold box, in particular to a filtering device for solid impurities of the low-temperature liquid in the air separation field.

Background

In low-temperature systems of air separation, hydrogen liquefaction, synthesis gas separation and the like, gas at normal temperature is cooled and even liquefied, so that the process purposes of separation, purification, convenient storage and the like are realized. The temperature in the system is below ambient temperature, often below 0 deg.C, -40 deg.C, -150 deg.C, -180 deg.C or lower. The equipment of the cryogenic system, as well as the piping, needs to be installed in one or more insulated boxes, called cold boxes. The cold box is sometimes filled with thermal insulation materials such as pearlite sand or slag wool to maintain a low temperature environment in the system. Due to errors in installation and operation processes or aging caused by long-term operation, particles or other solid impurities can be entrained into the cryogenic liquid, and the solid impurities can cause damage to rotating equipment, cause equipment to jump, and even possibly cause safety accidents such as fire or explosion.

At present, installing a pipe filter in the pipe upstream of the rotating equipment is a conventional solution for protecting the rotating equipment. Because the filter is fixedly arranged at the upstream of the rotating equipment, once the filter is blocked, the cold box needs to be opened, the heat insulation material is removed, and the maintenance personnel can enter the interior of the cold box for operation. The maintenance process is complicated and high in cost, and people enter the closed space and risk of suffocation and the like.

Patent publication CN101360964A discloses a filter suitable for cryogenic system, which is installed on the upstream pipeline of the rotating equipment, placed in the isolation box and connected with a cap on the top of the filter through a flange, and by detaching the cap, the cleaning of the inside of the filter and the replacement of the filter screen can be realized. The flange of the filter is exposed to the atmosphere and can continuously exchange heat with the external environment. Heat from the environment is conducted into the filter interior causing the cryogenic liquid to evaporate and collect between the filter housing and the flange, forming a gas seal that reduces the rate of heat exchange between the cryogenic liquid and the external environment.

However, during long-term operation of the air separation, the cryogenic liquid in the filter continues to evaporate, constantly collecting at the air seal and forcing the level of cryogenic liquid downward. When the liquid level is below the level of the cryogenic liquid outlet in the filter, gas collected at the gas seal can pass through the filter outlet conduit into the cryogenic pump downstream. If the liquid entering the cryopump contains bubbles, cavitation can be generated in the cryopump body, internal structures such as a cryopump impeller and the like are damaged, the performance of the cryopump is seriously affected, and the cryopump is replaced. Furthermore, if cavitation occurs in the cryogenic liquid oxygen pump, it may cause friction between solid fragments and liquid oxygen in the pump, and thus explosion may occur.

In view of the above, a need exists in the art for a safe and easy-to-maintain cryogenic filter apparatus that overcomes the above-mentioned shortcomings and drawbacks of the prior art.

SUMMERY OF THE UTILITY MODEL

The technical problem to be solved by the utility model is how to maintain and clean the filtering device of the low-temperature liquid without disassembling the cold box and ensure the safety of the filtering device in long-term operation.

In order to achieve the purpose, the utility model discloses a low-temperature liquid filtering device arranged in a cold box, which comprises a shell, a liquid inlet, a liquid outlet and a liquid filtering device, wherein the liquid inlet and the liquid outlet are arranged in the cold box, the included angle between the central axis of the shell and the horizontal plane is in the range of 15-90 degrees, and the top of the shell is positioned outside the cold box; the shell cover is positioned on the outer side of the cold box and connected with the top of the shell; a filter screen placed inside the housing; wherein, the casing still is provided with the gas vent, just the gas vent set up in the cold box.

Further, the horizontal height of the upper edge of the exhaust port is higher than that of the upper edge of the liquid outlet.

Still further, in a horizontal section where the upper edge of the exhaust port is located, the closest distance (L) between the shell and the cold box panel is greater than or equal to the inner diameter (W) of the shell.

Further, the included angle between the central axis of the shell and the horizontal plane is 45 degrees.

The utility model also discloses a low-temperature system comprising the filtering device, and the low-temperature system also comprises a low-temperature liquid accommodating device, wherein the low-temperature liquid accommodating device is communicated with the liquid inlet of the filtering device through a pipeline; and the inlet of the rotating equipment is communicated with the liquid outlet of the filtering device through a pipeline. Preferably, the rotating device is a cryogenic liquid pump.

Further, the low-temperature liquid containing device is communicated with the exhaust port of the filtering device through a pipeline.

Further, the cryogenic liquid containment device comprises a cryogenic rectification column.

Further, the cryogenic liquid containment device comprises a cryogenic liquid storage tank.

Compared with the prior art, the low-temperature liquid filtering device provided by the utility model has the following advantages:

before the cryogenic liquid flows through the cryogenic pump, solid impurities in the cryogenic liquid need to be filtered, so that the safe operation of the cryogenic liquid is guaranteed. Generally, the low-temperature filtering device is a pipeline filter, and once the filter is blocked, the cold box and the pipelines upstream and downstream of the filter need to be disassembled for maintenance, which wastes time and labor. The shell of the filtering device is extended out of the cold box, so that the filtering screen in the filtering device can be conveniently cleaned and replaced, the maintenance time is saved, the maintenance flow is simplified, the personnel are prevented from entering the closed space in the cold box, and the safety of the maintenance personnel is improved.

Because the upper part of the shell of the filtering device is positioned outside the cold box and can continuously exchange heat with the external environment, the low-temperature liquid in the filtering device absorbs heat to evaporate and is gathered in the shell of the filtering device, and the gathered gas can harm the safe operation of a downstream low-temperature liquid pump in the past. The shell of the filtering device is provided with the exhaust port, so that the evaporated gas accumulated in the shell can be timely exhausted, the accumulated gas is prevented from entering a downstream low-temperature pump through a liquid outlet pipeline communicated with the shell, further, the gas accumulated in the filtering device is prevented from causing cavitation damage to the downstream low-temperature liquid pump, and the safety of a low-temperature system is improved.

The exhaust port of the utility model is connected to the low-temperature liquid accommodating device, so that the cold energy carried by the evaporated gas in the filtering device can be recovered, and the waste of the cold energy caused by the diffusion of the low-temperature gas is avoided. Furthermore, low-temperature oxygen generated by evaporation of the liquid oxygen is communicated into the rectifying tower through the exhaust port, so that the extraction rate of the rectifying tower on the oxygen can be further improved.

Drawings

The advantages and spirit of the present invention will be further understood by the following detailed description and accompanying drawings.

FIG. 1 is a cryogenic air separation system capable of employing the filtration apparatus of the present invention;

FIG. 2 is a schematic view of a filter apparatus of the present invention;

fig. 3 is a further schematic view of the filter device of the present invention.

Like reference numerals designate corresponding parts in fig. 1 to 3.

The reference numbers are as follows: 1-heat exchanger, 2-rectifying tower, 3-cryogenic pump, 4-filtering device for cryogenic liquid, 5-cold box panel, 11-air stream, 13-liquid inlet pipeline, 14-liquid outlet pipeline, 15-high-pressure liquid oxygen, 17-polluted nitrogen, 19-exhaust pipeline, 41-shell, 42-shell cover, 43-exhaust port, 44-filter screen, 45-liquid level of cryogenic liquid, 46-liquid inlet, 47-liquid outlet and 100-air separation cold box.

Detailed Description

Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, it is to be understood that the present invention is not limited to such an embodiment described below, and the technical idea of the present invention may be implemented in combination with other known techniques or other techniques functionally equivalent to those known techniques.

In the following description of the embodiments, the devices and systems of the present invention are described by directional terms, but the terms "upper", "lower", "front", "rear", "outer", "inner", "upper", "lower", "horizontal", "vertical", "parallel", and the like are to be construed as words of convenience and are not to be construed as words of limitation.

Further, in the description of the present invention, "a plurality" means two or more unless specifically stated otherwise. Similarly, the appearances of the phrases "a" or "an" in various places herein are not necessarily all referring to the same quantity, but rather to the same quantity, and are intended to cover all technical features not previously described. Similarly, unless a specific number of a claim recitation is intended to cover both the singular and the plural, and embodiments may include a single feature or a plurality of features. Similarly, modifiers similar to "about", "approximately" or "approximately" that occur before a numerical term herein typically include the same number, and their specific meaning should be read in conjunction with the context.

Unless clearly indicated to the contrary, each aspect or embodiment defined herein may be combined with any other aspect or embodiments. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature indicated as being preferred or advantageous.

The "filtering device" herein refers to a device for intercepting solid impurities in a fluid.

By "housing" herein is meant the body portion of the filter device, which is open at the top, houses the filter screen and communicates with the duct.

The "case cover" herein refers to a cover structure that is mated with the open end of the case, can be mated with the case, or is open relative to the case. The housing and the housing cover are detachably connected, for example, by flanges, clips or screws. The specific implementation of the connection can be understood by those skilled in the art as a specific case.

The term "screen" as used herein refers to a metallic filtering mesh structure placed on the bottom of the housing and made of stainless steel, monel, or low alloy steel. The screen size may be greater than 18 mesh, or greater than 40 mesh, or greater than 48 mesh, or greater than 100 mesh, among other suitable sizes.

The "air separation system" herein refers to a system which uses air as raw material, reduces the temperature of the air to a low temperature state by means of compressing the air and expanding and refrigerating, and then gradually separates oxygen, nitrogen, argon and other air components through a rectifying tower.

The "cold box" in the present context refers to an isolated box body carrying cryogenically operated equipment such as a rectifying column, a heat exchanger, a cryogenic pump, an expander and piping in an air separation system or other cryogenic system to limit the heat exchange of the cryogenic equipment with the environment. The cold box can be composed of one or more isolation box bodies, and heat insulation materials, such as pearlife or mineral wool, can be filled in the cold box to further slow down heat exchange between the inside and the outside of the cold box.

By "rotating device" herein is meant a device that changes the pressure of a liquid flowing therein by applying work to the fluid or by applying work outward from the fluid as it flows through the device. Rotating equipment commonly found in cryogenic systems includes "cryogenic pumps" which refer to devices used to increase the pressure of cryogenic liquids, e.g., liquid oxygen pumps, liquid nitrogen pumps, liquid argon pumps, etc.; also included is an "expander" which refers to a device, such as a liquid expander, a gas expander, etc., in which a high-pressure fluid flows through an impeller and applies work to the impeller to reduce the pressure and temperature of the fluid.

By "cryogenic liquid containment device" herein is meant a vessel operating at a temperature below ambient temperature, the cryogenic liquid in the vessel being piped to a cryogenic liquid filtering device and downstream rotating equipment. The term "rectifying column" as used herein refers to a cryogenic liquid receiver, and refers to a vessel for separating components by contacting a liquid with a gas, i.e., a device for separating light components and heavy components by contacting the liquid and the gas in a column-shaped vessel having a tray or packing structure, and allowing the light components to rise and the heavy components to fall. In the air separation system, the rectifying tower can be one or composed of a plurality of rectifying towers. When a plurality of rectifying towers are arranged, the rectifying towers can be arranged in parallel or in an up-down manner, and a heat exchange relationship is formed between the upper tower and the lower tower by a condensation evaporator. Liquid oxygen, liquid nitrogen, liquid argon, etc. may be withdrawn from the rectification column as an air separation product. As used herein, "liquid storage tank" is another type of cryogenic liquid containment device and refers to a cryogenic liquid storage device, such as a liquid oxygen tank, a liquid nitrogen tank, a liquid argon tank, and the like. In air separation systems, cryogenic liquid products produced by distillation or other means are stored in liquid storage tanks. Additionally, the liquid storage tank may also receive cryogenic liquid that is transported through a pipeline system or vehicle.

The "central axis" in this context refers to the geometric centre line of the filter device in the longitudinal direction of the housing. For example, the housing of the filter device is a cylinder, and the central axis of the housing is a connecting line of the center of the cross section of the housing in the longitudinal direction. For example, the housing of the filter device is a cube, and the central axis of the filter device is a connecting line of the intersection point of the diagonals of the transverse section of the housing in the longitudinal direction.

By "inner diameter" herein is meant the diameter of the inscribed circle/ellipse of the cross-section of the filter device housing. If the shell of the filtering device is a cylinder, the diameter of the inner side of the cylinder is the same.

"Low temperature" in this context includes any temperature below 0 ℃, or even below-40 ℃, or even below-150 ℃, or even below-180 ℃.

The term "communicate" as used herein is to be understood broadly and may be direct communication or indirect communication via devices, valves, and the like.

Examples

In the embodiment shown in fig. 1, a pressurized, purified air stream 11 enters an air separation cold box 100, is reduced to a cryogenic state via heat exchanger 1, and enters the lower column of higher pressure rectifier 2. In the lower tower of the rectifying tower 2, lighter nitrogen components in the air rise, heavier oxygen components fall, rectified substances rich in nitrogen and rectified substances rich in oxygen are separated and enter the upper tower of the rectifying tower 2 with lower pressure for further rectification. And the polluted nitrogen 17 is conveyed to the heat exchanger 1 for heat exchange by the upper tower of the rectifying tower 2, and leaves the air separation cold box 100 after reheating. The liquid oxygen is extracted from the bottom of the rectifying column 2 at the top thereof, and after particulate impurities are removed by the cryogenic liquid filtering apparatus 4, the liquid oxygen is sent to the cryopump 3, and is pressurized by the cryopump 3 to be high-pressure liquid oxygen 15. The high-pressure liquid oxygen 15 is conveyed to the heat exchanger 1 again, and leaves the air separation cold box 100 after being evaporated and reheated into an oxygen product.

In the long-term operation of the air separation system, impurities such as particulate matters may gradually gather in the filtering device 4 of the cryogenic liquid, so that the pressure drop of the liquid oxygen flowing through the filtering device 4 is increased, and meanwhile, the pressure of the liquid oxygen entering the cryogenic pump 3 is reduced, thereby affecting the efficiency and safety of the cryogenic pump 3. In addition, liquid oxygen rapidly impacts the surface of the particulate matter accumulated in filter device 4 and rubs against the particulate matter igniting the liquid oxygen to form an explosion, and therefore, when the pressure drop of cryogenic filter device 4 increases, it is necessary to remove solid impurities from filter device 4.

In accordance with the present invention, the filtering means 4 of the cryogenic liquid has a portion that protrudes outside the cold box 100, facilitating the removal of the solid impurities accumulated therein. The portion of the filter device 4 extending out of the cold box 100 is exposed to the air, and the heat absorbed by it is conducted to the portion of the filter device 4 located inside the cold box 100, so as to evaporate the liquid oxygen in the filter device 4. The oxygen generated by the evaporation collects in the filter device 4. In order to avoid excessive accumulation of oxygen, the low-temperature filtering device 4 is also provided with an exhaust port 43 and is communicated with an exhaust pipeline 19 for timely discharging excessive accumulated oxygen, and the exhaust pipeline 19 is communicated to the rectifying tower 2 for recovering the cold energy of the low-temperature oxygen and improving the oxygen extraction rate. In addition, the exhaust pipe 19 can also be communicated with other pipes in the cold box, or the outlet of the exhaust pipe 19 leads to the outside of the cold box for discharging.

Fig. 2 is a schematic view of the filter device 4. The filter device 4 is arranged vertically, i.e. its central axis forms an angle alpha of 90 degrees with the horizontal plane. The filter device 4 comprises a filter screen 44 located within the housing 41. The screen 44 may be made of a suitable material, such as stainless steel, low alloy steel, or monel, and may be sized to be 18 mesh, 40 mesh, 48 mesh, or 100 mesh. The housing 41 is connected with the upstream liquid inlet pipeline 13 and the downstream liquid outlet pipeline 14 through a liquid inlet 46 and a liquid outlet 47 respectively, the upper part of the housing 41 extends out of the cold box 100 and is opened, and a matched shell cover 42 is connected with the upper part of the housing 41. The cover 42 may be a blind flange that can be removed to facilitate opening the top of the housing 41 and removing the screen 44 from the housing 41. The housing cover 42 may also be a cover plate and may be connected to the housing 41 by other means for easy detachment, such as clamping, or screwing.

Since the upper part of the housing 41 and the housing cover 42 extend out of the cold box 100, the evaporated low-temperature oxygen gas is gathered between the housing cover 42 and the liquid level 45 to form an air seal, and the heat exchange rate between the liquid oxygen and the external environment can be slowed down to a certain extent. During long-term operation of the air separation, the continued heat exchange causes the gas seal volume to increase and force the liquid surface 45 downward. Therefore, the housing 41 is also provided with an exhaust port 43 to exhaust excessive oxygen accumulated in the gas seal out of the filter unit 4 in time, so as to prevent the liquid level 45 from falling below the upper edge of the liquid outlet 47, thereby preventing oxygen in the gas seal from entering the downstream cryopump 3 through the outlet pipe 14.

Preferably, the exhaust port 43 is at the level of the opening in the housing 41, submerged below the liquid level 45 and above the upper edge of the outlet pipe 14. When the vapor lock is too large, excess accumulated oxygen is vented from exhaust line 19 to rectifier 2, preventing bubbles from entering downstream cryopump 3 through exit line 14. And the gas quantity in the gas seal can be ensured to be stable under normal conditions, and the oxygen in the gas seal is prevented from being continuously discharged to the rectifying tower 2 through the exhaust pipe 43, so that the low-temperature liquid oxygen at the liquid level 45 is prevented from being evaporated too fast.

Fig. 3 is a schematic view of the filter unit 4 installed in the cold box, wherein the filter unit 4 is disposed obliquely and the included angle α between the central axis of the filter unit and the horizontal plane is 45 degrees. The housing 41 is installed in the cold box 100 so as to penetrate the cold box panel 5. Wherein, the inlet pipe 13, the outlet pipe 14, the shell 41 and the filter screen 44 therein are arranged at the inner side of the cold box panel 5, and the cold box 100 is filled with pearlife. The top of the case cover 42 and the case 41 extend out of the cold box panel 5. When the shell cover 42 is disassembled and the filter screen 44 is taken and placed, the structure of the panel 5 of the cold box is not damaged, the pearly-lustre sand in the cold box 100 does not need to be removed, and the maintenance time and the maintenance cost are saved. In addition, the operator does not need to enter the limited space surrounded by the cold box panel 5, and the safety risks of suffocation/oxygen poisoning and the like are avoided.

The air seal extends from the cover 42 outside the cold box panel 5 to the liquid level 45 inside the cold box panel 5, at most down to the upper edge of the exhaust port 43. Since the liquid level 45 fluctuates with the fluctuation of the flowing liquid oxygen, the exhaust port 43 is disposed inside the panel 5 of the cold box, so as to substantially maintain the liquid level 45 in the cold box 100, thereby preventing the liquid oxygen from being exposed to the external environment of the cold box 100 and being evaporated too quickly.

Further, at the level of the upper edge of the air outlet 43, the closest distance L of the housing 41 to the cold box panel 5 is equal to or greater than the diameter W of the housing 41. As the air separation unit is operated steadily at a predetermined operating condition, the volume between the cover 42 and the exhaust port 43 is gradually filled by the air seal formed by the evaporation of the low liquid. Therefore, the liquid surface 45 will be stabilized at a position near the upper edge of the exhaust port 43. Therefore, the distance L between the case 41 and the cold box panel 5 at the level of the upper edge of the exhaust port 43 can be understood as approximately the distance between the liquid surface 45 and the cold box panel 5. This distance L is equal to or greater than the diameter W of the housing 41, which further ensures that the liquid oxygen remains at a sufficient insulation distance from the external environment.

The included angle α between the central axis of the housing 41 and the horizontal plane is 15-90 °, and preferably 45 ° for an operator to conveniently detach the housing cover 42. Depending on the size of the cold box 100, the arrangement of the pipes, and the location of the operation platform, the skilled person can choose a suitable angle for installing the low temperature multi-filtration device 4.

The low-temperature liquid filtering device can be also used for connecting low-temperature liquid storage tanks, such as a liquid oxygen tank, a liquid nitrogen tank, a liquid argon tank and the like, and is particularly suitable for an air separation backup system.

The embodiments described in the specification are only preferred embodiments of the present invention, and the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the present invention. Those skilled in the art can obtain technical solutions through logical analysis, reasoning or limited experiments according to the concepts of the present invention, and all such technical solutions are within the scope of the present invention.

Claims

1. A cryogenic liquid filtering apparatus for installation in a cold box, comprising:

the cooling device comprises a shell, a cooling box and a cooling box, wherein the shell is provided with a liquid inlet and a liquid outlet, the liquid inlet and the liquid outlet are arranged in the cooling box, an included angle between the central axis of the shell and the horizontal plane is in a range of 15-90 degrees, and the top of the shell is positioned outside the cooling box;

the shell cover is positioned on the outer side of the cold box and connected with the top of the shell;

a filter screen placed inside the housing;

wherein, the casing still is provided with the gas vent, just the gas vent set up in the cold box.

2. The filter apparatus of claim 1, wherein a height of an upper edge of said gas outlet is higher than a height of an upper edge of said liquid outlet.

3. The filter apparatus of claim 2, wherein a closest distance L between said housing and said cold box panel in a horizontal section where said upper edge of said air outlet is located is greater than or equal to an inner diameter W of said housing.

4. The filtration apparatus of claim 1, wherein the central axis of the housing is at a 45 degree angle to the horizontal.

5. A cryogenic system comprising a filtration device according to any one of claims 1 to 4, further comprising:

the low-temperature liquid accommodating device is communicated with the liquid inlet of the filtering device through a pipeline;

and the inlet of the rotating equipment is communicated with the liquid outlet of the filtering device through a pipeline.

6. The cryogenic system of claim 5, wherein the cryogenic liquid containment device is in communication with the vent of the filtering device through a conduit.

7. The cryogenic system of claim 5, wherein the rotary equipment comprises a cryogenic pump.

8. The cryogenic system of claim 5, wherein the cryogenic liquid containment device comprises a cryogenic rectification column.

9. The cryogenic system of claim 6, wherein the cryogenic liquid containment device comprises a cryogenic rectification column.

10. The cryogenic system of claim 5, wherein the cryogenic liquid containment device comprises a cryogenic liquid storage tank.