Fractionating column cold box

Abstract

The utility model relates to the technical field of fractionating column cold box, specifically disclose a fractionating column cold box, including main cold box, install a plurality of low temperature liquid pump of main cold box outer wall, with the liquid guide pipe of low temperature liquid pump connection, and set up nitrogen tube outside main cold box, the main cold box is filled with pearl sand heat preservation layer, still include vacuum heat insulation board layer, lay in the inner tank wall of main cold box, with pearl sand heat preservation layer jointly constitute composite heat preservation structure, through composite heat preservation, nitrogen purging and electric heating moistureproof multiple effect, realized the comprehensive, efficient prevention and cure of fractionating column cold box frost problem, not only significantly improved the heat preservation performance, effectively prevented the pearl sand damp agglomeration, prolonged its service life, also ensured the quick reliable start of low temperature liquid pump, simultaneously, strengthened the ability of equipment to respond complex working condition, reduced the maintenance frequency and cost, improved the operation stability, security and intelligent management level of fractionating column system as a whole.

Description

Technical Field

[0001] This utility model relates to the field of fractionation tower cold box technology, and specifically discloses a fractionation tower cold box. Background Technology

[0002] The fractionation tower cold box is a core piece of equipment in air separation units, natural gas liquefaction (LNG) processes, and other similar procedures. It houses fractionation towers, heat exchangers, cryogenic liquid pumps, and various process pipelines, used to separate and liquefy gas mixtures at extremely low temperatures. To ensure stable operation of the internal equipment, the cold box is typically filled with insulating materials such as perlite to create a stable cryogenic environment and prevent external heat intrusion. In actual operation, due to the extremely low temperatures of the internal equipment and pipelines, and the relatively high external ambient temperature, the significant temperature difference easily causes water vapor in the air to seep through the cold box walls and condense into frost or even ice on the cryogenic surfaces. Severe frost formation not only significantly reduces the insulation performance of the perlite, leading to increased cooling loss and energy consumption, but can also increase the weight of the cold box due to caking, placing a burden on the cold box structure and affecting the normal start-up and operation of auxiliary equipment such as cryogenic liquid pumps.

[0003] To address the aforementioned frosting problem, several improvements have been proposed in the prior art. For example, Chinese Utility Model Patent Publication No. CN218210321U discloses a fractionation tower cold box for preventing frosting. This solution involves installing a nitrogen pipe outside the cold box to introduce nitrogen gas into the interior of the cold box filled with perlite. The inertness and drying properties of nitrogen enhance the insulation effect of the perlite and prevent frosting. This solution improves the problem to some extent and represents a common technical approach in this field.

[0004] However, the aforementioned existing technologies still have significant shortcomings and limitations. First, their nitrogen purging system is relatively simple. After the nitrogen is discharged from the vent on the pipe, the uniformity of its distribution and flow direction in the perlite filling layer are uncontrollable, making it difficult to ensure an effective and fully covered dry air curtain for all key areas prone to frost, such as the bottom of the cold box and the cryogenic pump interface, resulting in blind spots in the anti-frost effect. Second, this solution relies solely on nitrogen for physical isolation and lacks active control over the state of the perlite itself. Once a small amount of moisture intrudes or condensation occurs due to temperature differences, the perlite will still become damp and clump together, and it cannot recover on its own. In addition, the system lacks intelligent monitoring and feedback control, and cannot adjust the nitrogen flow rate or activate auxiliary dehumidification methods in real time according to the actual temperature and humidity changes inside the cold box, resulting in low energy utilization efficiency and a weak ability to cope with complex operating conditions. Utility Model Content

[0005] This utility model proposes a fractionation tower cold box, which achieves comprehensive and efficient prevention and control of frost formation in the fractionation tower cold box through multiple functions of composite insulation, nitrogen purging and electric heating for moisture prevention. It significantly improves the insulation performance, effectively prevents perlite from becoming damp and clumping, and extends its service life.

[0006] This utility model is implemented as follows: a fractionation tower cold box includes a main cold box body, multiple cryogenic liquid pumps installed on the outer wall of the main cold box body, liquid guide pipes connected to the cryogenic liquid pumps, and a nitrogen pipe disposed outside the main cold box body. The main cold box body is filled with a perlite insulation layer, and further includes:

[0007] Vacuum insulation panels are laid on the inner wall of the main cold box, forming a composite insulation structure together with the perlite insulation layer.

[0008] The nitrogen pipe extends into the main cold box and is arranged in a ring. Several air outlets are opened on the pipe wall. The distribution density of the air outlets gradually increases along the nitrogen flow direction. The outside of the air outlets is covered with a breathable and waterproof membrane.

[0009] The electric heating moisture-proof module includes a PTC ceramic heating element embedded in a perlite insulation layer;

[0010] The sensor group includes a temperature and humidity sensor installed inside the main cold box to detect temperature and humidity, and a frosting sensor to detect frosting status.

[0011] The controller, a PLC controller, is installed on the outside of the main cold box and is electrically connected to the sensor group and the electric heating and moisture-proof module.

[0012] As a preferred embodiment of the fractionation tower cold box of this utility model, the bottom of the main cold box body is provided with a condensate collection structure, the condensate collection structure is a funnel-shaped water collection tank, and the bottom of the condensate collection structure is provided with a drain valve.

[0013] As a preferred embodiment of the fractionation tower cold box of this utility model, the controller is equipped with a communication module for data interaction with a remote monitoring terminal.

[0014] As a preferred embodiment of the fractionation tower cold box of this utility model, a reflective aluminum foil layer is also provided between the vacuum insulation board layer and the inner wall of the main cold box.

[0015] As a preferred embodiment of the fractionation tower cold box of this utility model, the breathable and waterproof membrane is an ePTFE nanofilm.

[0016] As a preferred embodiment of the fractionation tower cold box of this utility model, the PTC ceramic heating element is evenly distributed in the lower region of the perlite insulation layer.

[0017] In a preferred embodiment of the fractionation tower cold box of this utility model, the opening direction of the gas outlet is downward.

[0018] The beneficial effects of this utility model are:

[0019] Through the combined effects of composite insulation, nitrogen purging, and electric heating for moisture prevention, a comprehensive and efficient prevention and control of frost formation in the cold box of the distillation tower is achieved. This not only significantly improves the insulation performance and effectively prevents the perlite from becoming damp and clumping, thus extending its service life, but also ensures the rapid and reliable start-up of the cryogenic liquid pump. At the same time, it enhances the equipment's ability to cope with complex operating conditions, reduces maintenance frequency and costs, and improves the overall operational stability, safety, and intelligent management level of the distillation tower system. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0021] Figure 1 This is a diagram showing the overall internal structure of this utility model;

[0022] Figure 2 This is a diagram showing the overall external structure of the present invention;

[0023] Figure 3 This is a bottom view of the nitrogen pipe structure of this utility model.

[0024] The markings in the diagram are: 1. Main cold chamber; 2. Cryogenic liquid pump; 3. Nitrogen pipe; 4. Perlite insulation layer; 5. Vacuum insulation panel layer; 6. Vent; 7. Breathable and waterproof membrane; 8. PTC ceramic heating element; 9. Temperature and humidity sensor; 10. Frost sensor; 11. Controller; 12. Condensate collection structure; 13. Drain valve; 14. Reflective aluminum foil layer. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments to aid in understanding its content. Unless otherwise specified, the methods used in this invention are conventional methods; the raw materials and apparatus used, unless otherwise specified, are conventional commercially available products.

[0026] Please see Figure 1-3 A fractionation tower cold box includes a main cold box body 1, multiple cryogenic liquid pumps 2 installed on the outer wall of the main cold box body 1, liquid guide pipes connected to the cryogenic liquid pumps 2, and a nitrogen pipe 3 disposed outside the main cold box body 1. The main cold box body 1 is filled with a perlite insulation layer 4, and further includes:

[0027] Vacuum insulation board layer 5 is laid on the inner wall of the main cold box 1, and together with the perlite insulation layer 4, it forms a composite insulation structure.

[0028] Nitrogen pipe 3 extends into the main cold box 1 and is arranged in a ring. Several vent holes 6 are opened on the pipe wall. The distribution density of the vent holes 6 gradually increases along the direction of nitrogen flow. The outside of the vent holes 6 is covered with a breathable and waterproof membrane 7.

[0029] The electric heating and moisture-proof module includes a PTC ceramic heating element 8 embedded in the perlite insulation layer 4;

[0030] The sensor group includes a temperature and humidity sensor 9 installed inside the main cold box 1 for detecting temperature and humidity, and a frosting sensor 10 for detecting frosting status.

[0031] The controller 11 is installed on the outside of the main cold box 1 and is a PLC controller. It is electrically connected to the sensor group and the electric heating and moisture-proof module.

[0032] In this embodiment: A vacuum insulation board layer 5 is laid on the inner wall of the main cold box 1. Together with the internal perlite insulation layer 4, it forms a highly efficient composite insulation barrier, greatly reducing the intrusion of external heat into the cold box and reducing the driving force for frost formation at the source. For trace amounts of moisture that may seep in, the nitrogen pipes 3 arranged in a ring inside the box have gradually increasing distribution of vent holes 6 and are covered with a breathable and waterproof membrane 7. This structure ensures that the dry nitrogen gas diffuses evenly from near to far in the perlite insulation layer 4, forming a fully covered dry air curtain that actively disperses moisture. Meanwhile, the electric heating and dehumidification module, consisting of PTC ceramic heating elements 8 embedded in the lower part of the perlite insulation layer 4, can gently heat the bottom area prone to condensation, keeping its temperature above the dew point and effectively preventing condensation. The entire system is monitored in real time by temperature and humidity sensors 9 and frost sensors 10 located at key points. All data is transmitted to the PLC controller 11, which analyzes and automatically controls the start, stop, and intensity of nitrogen purging and heating dehumidification, ultimately achieving a comprehensive effect of efficient anti-frost, ensuring stable system operation, and significant energy saving.

[0033] As a technical optimization of this utility model, a condensate collection structure 12 is provided at the bottom of the main cold box 1. The condensate collection structure 12 is a funnel-shaped water collection tank, and a drain valve 13 is provided at the bottom of the condensate collection structure 12.

[0034] In this embodiment, a funnel-shaped condensate collection structure 12 and a drain valve 13 are provided at the bottom of the main cold box 1. The funnel structure efficiently collects any small amount of condensate that may be generated, and the drain valve 13 is used to periodically discharge it, preventing water from accumulating at the bottom of the box. This eliminates the long-term damage of water accumulation to the perlite and the box structure, and improves the reliability of the system.

[0035] As a technical optimization of this utility model, the controller 11 is equipped with a communication module for data interaction with the remote monitoring terminal.

[0036] In this embodiment, a communication module is integrated into the controller 11, giving the local control system remote interaction capabilities. It can upload operating data to the monitoring center and receive remote commands, realizing remote monitoring and fault diagnosis of the equipment, which greatly improves the convenience of operation and maintenance and the level of intelligent management.

[0037] As a technical optimization of this utility model, a reflective aluminum foil layer 14 is also provided between the vacuum insulation board layer 5 and the inner wall of the main cold box 1.

[0038] In this embodiment, a reflective aluminum foil layer 14 is added between the vacuum insulation board layer 5 and the inner wall of the box. The extremely low emissivity of the aluminum foil reflects the cold energy radiated by the internal low-temperature equipment back, forming effective radiative insulation, which further enhances the overall performance of the composite insulation structure and reduces the loss of cold energy caused by radiative heat transfer.

[0039] As a technical optimization of this utility model, the breathable and waterproof membrane 7 is an ePTFE nanofilm.

[0040] In this embodiment: the breathable and waterproof membrane 7 is an ePTFE nanofilm. Utilizing the unique microporous structure of this material, the micropores are much smaller than water droplets but larger than nitrogen molecules, thus allowing only gas to pass through while blocking liquid water, achieving smooth nitrogen overflow, and at the same time effectively preventing external moisture from back-penetrating or perlite from clogging the pores.

[0041] As a technical optimization of this utility model, the PTC ceramic heating element 8 is evenly distributed in the lower area of ​​the pearlescent sand insulation layer 4.

[0042] In this embodiment, PTC ceramic heating elements 8 are evenly distributed in the lower part of the perlite insulation layer 4 to provide precise and localized active heating for the areas in the cold box where cold air sinks and is most prone to frost.

[0043] As a technical optimization of this utility model, the opening direction of the air outlet 6 is downward.

[0044] In this embodiment, the kinetic energy of the nitrogen outflow is used to directly impact and agitate the area at the bottom where cold and humid air tends to accumulate, ensuring that the dry nitrogen can preferentially cover and protect the bottom components with the highest risk of frost formation, thus eliminating frost-proof blind spots.

[0045] The working principle and usage process of this utility model are as follows: During system startup, temperature and humidity sensors 9 and frost sensors 10, distributed inside the main cold box 1, continuously monitor the internal environment and transmit the data to the PLC controller 11 in real time. The controller 11 analyzes the data. If it determines there is a risk of frost formation or detects excessive humidity, it first activates the intelligent nitrogen purging system. The nitrogen source is opened, and dry nitrogen is delivered through the nitrogen pipe 3, flowing out from the downward-facing, gradually increasing density vents 6 on its annular pipe. The breathable and waterproof membrane 7 outside the vents 6 effectively prevents blockage and ensures smooth nitrogen flow. The nitrogen diffuses evenly from top to bottom and from dense to sparse within the perlite insulation layer 4, creating a dry atmosphere that displaces and removes water vapor. If the sensors detect that the temperature in the bottom area is close to the dew point or the humidity remains high, the controller 11 will simultaneously or separately activate the electric heating moisture-proof module, causing the PTC ceramic heating elements 8, evenly distributed below the perlite insulation layer 4, to operate, generating gentle heat and raising the temperature in that area, fundamentally preventing condensation. Throughout the process, the composite insulation structure consisting of the vacuum insulation board layer 5 and the perlite insulation layer 4 continuously plays an efficient isolation role, reducing cold loss. The minimal amount of condensate that may be generated will be collected by the condensate collection structure 12 at the bottom and discharged periodically through the drain valve 13. The controller 11 can also interact with the remote terminal through the internal communication module to realize remote monitoring and intelligent operation and maintenance.

[0046] In the description of this utility model, it should be understood that the terms "left", "right", "up", "down", "top", "bottom", "front", "back", "inner", "outer", "back", "middle", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0047] However, the above description is only a specific embodiment of this utility model and should not be construed as limiting the scope of implementation of this utility model. Therefore, any substitution of equivalent components or equivalent changes and modifications made in accordance with the scope of protection of this utility model should still fall within the scope of the claims of this utility model.

Claims

1. A fractionation tower cold box, characterized in that: The main cold box (1) includes a main cold box (1), multiple cryogenic liquid pumps (2) installed on the outer wall of the main cold box (1), liquid guide pipes connected to the cryogenic liquid pumps (2), and a nitrogen pipe (3) located outside the main cold box (1). The main cold box (1) is filled with a perlite insulation layer (4). The main cold box (1) also includes: Vacuum insulation board layer (5) is laid on the inner wall of the main cold box (1) and together with the perlite insulation layer (4) forms a composite insulation structure. The nitrogen pipe (3) extends into the main cold box (1) and is arranged in a ring. Several air outlets (6) are opened on the pipe wall. The distribution density of the air outlets (6) gradually increases along the nitrogen flow direction. The outside of the air outlets (6) is covered with a breathable and waterproof membrane (7). The electric heating moisture-proof module includes a PTC ceramic heating element (8) embedded in the perlite insulation layer (4); The sensor group includes a temperature and humidity sensor (9) installed inside the main cold box (1) for detecting temperature and humidity, and a frosting sensor (10) for detecting frosting status. The controller (11) is installed on the outside of the main cold box (1) and is a PLC controller. It is electrically connected to the sensor group and the electric heating and moisture-proof module.

2. The fractionation tower cold box according to claim 1, characterized in that: The bottom of the main cold box (1) is provided with a condensate collection structure (12), which is a funnel-shaped water collection tank, and a drain valve (13) is provided at the bottom of the condensate collection structure (12).

3. A fractionation tower cold box according to claim 1, characterized in that: The controller (11) is equipped with a communication module for data interaction with the remote monitoring terminal.

4. A fractionation tower cold box according to claim 1, characterized in that: A reflective aluminum foil layer (14) is also provided between the vacuum insulation panel layer (5) and the inner wall of the main cold box (1).

5. A fractionation tower cold box according to claim 1, characterized in that: The breathable and waterproof membrane (7) is an ePTFE nanofilm.

6. A fractionation tower cold box according to claim 1, characterized in that: The PTC ceramic heating element (8) is evenly distributed in the lower region of the perlite insulation layer (4).

7. A fractionation tower cold box according to claim 1, characterized in that: The opening of the air outlet (6) faces downward.

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