Cold supplementing system of precooling line

Abstract

The utility model relates to the field of natural gas deep cooling, in particular to a pre-cooling line cold supplementing system. Comprising a demethanation device, a secondary concentration tower and a demethanation device, wherein the demethanation device is internally provided with the secondary concentration tower; the natural gas liquefaction device is connected with the secondary concentration tower through a pipeline; the pre-cooling regulating valve group is arranged on a pipeline through which the natural gas liquefaction device is connected with the secondary concentration tower; and the precooling pipeline is connected with the pipelines of the natural gas liquefaction device and the secondary concentration tower. According to the precooling line cold supplementing system, the precooling pipeline is arranged, so that the precooling pipeline is prevented from being intercepted by a natural gas liquefying device, the obstruction on a cooling capacity transmission path is fundamentally eliminated, and the temperature of a flow channel pipeline between a secondary concentration tower of a demethanizing device and a precooling cold box can be stably maintained in a preset temperature interval; not only is the efficient cold supplement of the secondary concentration tower realized, but also the accurate matching of the temperature level in the whole system is ensured.

Description

Technical Field

[0001] The utility model relates to the field of natural gas cryogenics, in particular to a pre-cooling line cooling system. Background Art

[0002] The demethanizer is a key part of the natural gas liquefaction process. Its main task is to separate methane from the mixed gas and remove other impurities and light hydrocarbon components through a series of physical processes (such as distillation and concentration). In this process, the secondary concentration tower in the demethanizer is responsible for further concentrating the methane to meet the product purity requirements. The secondary concentration tower is generally connected to the pre-cooling feed line, which provides additional cooling capacity to the secondary concentration tower through the pre-cooling feed line to ensure that the material in the tower can be maintained at a low temperature, thereby promoting an efficient separation process. Under normal circumstances, the temperature of the flow channel pipeline from the secondary concentration tower to the pre-cooling cold box should be around -151°C during operation.

[0003] However, in actual operation, the temperature of the pre-cooling line usually fails to reach the standard temperature. Among them, the cut-off of the natural gas liquefaction device is one of the main reasons. When the natural gas liquefaction device is cut off, the flow of the low-temperature medium that should have been supplied to the pre-cooling line is reduced or interrupted, resulting in the pre-cooling line being unable to provide sufficient cooling capacity to the secondary concentration tower. In this case, not only can the cooling be effectively supplemented, but the release of the small amount of cooling capacity remaining in the pre-cooling line may cause local rewarming of the secondary concentration tower. It will be found that the temperature of the secondary concentration tower drops from -115°C to about -140°C under the action of the pre-cooling line, which obviously does not meet the temperature requirements during normal operation mentioned above. The temperature position does not match, affecting the operation of the demethanizer. Utility Model Content

[0004] The purpose of the utility model is to propose a pre-cooling line supplementary cooling system, which can improve the cooling rate of the secondary concentration tower, avoid being intercepted by the natural gas liquefaction device, and ensure that the temperature of the flow channel pipeline between the secondary concentration tower of the demethanizer and the pre-cooling cold box can be stably maintained within a preset temperature range. It not only achieves efficient supplementary cooling for the secondary concentration tower, but also ensures accurate matching of the temperature level in the entire system, which is crucial for the stable operation of the demethanizer and ensures the stability and reliability of the demethanizer.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] The utility model provides a pre-cooling line cooling system, comprising:

[0007] A demethanization device, wherein the demethanization device is provided with a secondary concentration tower;

[0008] A natural gas liquefaction device connected to a secondary concentration tower pipeline;

[0009] A pre-cooling regulating valve group, which is installed on the pipeline connecting the natural gas liquefaction device and the secondary concentration tower;

[0010] The precooling pipeline is connected to the pipelines of the natural gas liquefaction device and the secondary concentration tower.

[0011] As a further improvement, the pre-cooling regulating valve group includes a second manual valve, a pre-cooling regulating valve and a first manual valve which are sequentially arranged in the natural gas transmission direction.

[0012] As a further improvement, the pre-cooling pipeline is arranged between the pre-cooling regulating valve and the first manual valve.

[0013] As a further improvement, it also includes a branch pipeline, wherein one end of the branch pipeline is arranged before the second hand valve, and the other end is arranged after the first hand valve.

[0014] As a further improvement, the demethanizer includes a pre-cooling box, a primary purification tower and a secondary purification tower connected in sequence, the primary purification tower is connected to the primary cooler and the primary separator respectively, and the secondary purification tower is connected to the secondary cooler and the secondary separator respectively.

[0015] As a further improvement, a demethanizer is also included, wherein one end of the demethanizer is connected to the secondary purification tower, and the other end is connected to the pre-cooling cold box.

[0016] As a further improvement, a pre-cooling compressor is provided in the pre-cooling cold box.

[0017] As a further improvement, the first-stage cooler is provided with a first-stage compressor.

[0018] As a further improvement, a secondary compressor is provided in the secondary cooler.

[0019] As a further improvement, it also includes a cooling supplement pipeline, wherein the cooling supplement pipeline is connected to the pre-cooling pipeline.

[0020] Compared with the prior art, the present invention has achieved the following technical effects:

[0021] The utility model discloses a pre-cooling line supplementary cooling system, which avoids being intercepted by the natural gas liquefaction device by setting up the pre-cooling pipeline, fundamentally eliminates the obstruction of the cold capacity transmission path, and ensures that the temperature of the flow channel pipeline between the secondary concentration tower of the demethanizer and the pre-cooling cold box can be stably maintained within a preset temperature range. It not only realizes efficient supplementary cooling for the secondary concentration tower, but also ensures accurate matching of the temperature level in the entire system, which is crucial to the stable operation of the demethanizer and ensures the stability and reliability of the demethanizer.

[0022] This device also has the effect of significantly improving energy efficiency and saving costs. By optimizing the use of cooling capacity, it reduces unnecessary energy loss and improves the energy efficiency of the entire system. At the same time, it further enhances economic benefits by reducing downtime and maintenance costs caused by equipment failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a structural schematic diagram of a pre-cooling line cooling system of the utility model.

[0024] Figure numerals: 1. Demethanization unit; 11. Secondary concentration tower; 2. Natural gas liquefaction unit; 3. Pre-cooling regulating valve group; 31. Pre-cooling regulating valve; 32. First hand valve; 33. Second hand valve; 34. Branch pipeline; 4. Pre-cooling pipeline. DETAILED DESCRIPTION

[0025] The embodiments of the present application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present application and are not to be construed as limiting the present application. On the contrary, the embodiments of the present application include all variations, modifications, and equivalents that fall within the spirit and scope of the appended claims.

[0026] Examples of the present application are described in detail below. Examples of the examples are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The examples described below with reference to the accompanying drawings are illustrative and intended to be used to explain the present application, and should not be construed as limiting the present application.

[0027] like Figure 1 As shown, the utility model provides a pre-cooling line supplementary cooling system, comprising: a demethanizer 1, wherein the demethanizer 1 is provided with a secondary concentration tower 11; a natural gas liquefaction unit 2, wherein the natural gas liquefaction unit 2 is connected to the secondary concentration tower 11 by a pipeline; a pre-cooling regulating valve 31 valve group 3, wherein the pre-cooling regulating valve 31 valve group 3 is provided on the pipeline connecting the natural gas liquefaction unit 2 and the secondary concentration tower 11; and a pre-cooling pipeline 4, wherein the pre-cooling pipeline 4 is connected to the pipelines of the natural gas liquefaction unit 2 and the secondary concentration tower 11.

[0028] The equipment layout within the demethanizer 1 in the embodiment can be determined based on the actual designed process flow, ensuring that the demethanizer is equipped with a secondary concentration tower 11. The primary function of the secondary concentration tower 11 is to concentrate the heavy components in the liquid phase of the natural gas to ensure the quality of the bottom product while also increasing the yield of the top product. The concentration tower separates and purifies the liquid mixture through steam heating and cooling. During the distillation process, the raw material mixture is heated to its boiling point, generating steam. After entering the tower, the steam contacts the packing within the tower, causing a gas-liquid interaction between the solvent and the organic matter to be separated. This interaction results in the exchange of energy and matter, thereby achieving the separation and purification of the organic matter. The concentration tower utilizes differences in boiling point, volatility, and chemical affinity among different substances to separate the components in the mixture according to their chemical properties, thereby obtaining the desired product of higher purity.

[0029] The pre-cooling regulating valve 31 valve group 3 includes a second manual valve 33, a pre-cooling regulating valve 31 and a first manual valve 32 arranged in sequence in the natural gas transmission direction. The pre-cooling pipeline 4 is arranged between the pre-cooling regulating valve 31 and the first manual valve 32.

[0030] In the embodiment, the pre-cooling regulating valve 31 valve group 3 plays the role of both manual control and automatic control of the pipelines in the system. Figure 1 As shown, it includes a pre-cooling regulating valve 31 and a first manual valve 32 arranged in sequence along the natural gas transmission direction A, wherein the pre-cooling regulating valve 31 is used for automatic control and the first manual valve 32 is used for manual control; considering that the natural gas liquefaction device 2 releases a large amount of heat during the process of liquefying natural gas, the present application connects the pre-cooling pipeline 4 between the pre-cooling regulating valve 31 and the first manual valve 32 to ensure that the pre-cooling pipeline 4 is not affected by changes in flow caused by automatic control, thereby affecting the temperature of the secondary concentration tower 11. Instead, it is only through manual control of the first manual valve 32 by the operator to ensure that the pre-cooling pipeline 4 continuously inputs into the secondary concentration tower 11.

[0031] The system further includes a branch line 34, one end of which is located before the second hand valve 33 and the other end after the first hand valve 32. The branch line 34 in the embodiment is a bypass facility with a regulating function, specifically using mature technology from a conventional natural gas liquefaction system.

[0032] The demethanizer 1 includes a precooling box, a primary purification tower, and a secondary purification tower connected in sequence. The primary purification tower is connected to the primary cooler and the primary separator, respectively, and the secondary purification tower is connected to the secondary cooler and the secondary separator, respectively. It also includes a demethanizer, one end of which is connected to the secondary purification tower and the other end is connected to the precooling box. The precooling box is equipped with a precooling compressor. The primary cooler is equipped with a primary compressor, and the secondary cooler is equipped with a secondary compressor.

[0033] The equipment layout inside the demethanizer 1 in the embodiment can be determined according to the actual designed process flow. In one embodiment, in order to fully perform a series of treatments such as demethanization on the liquefied natural gas output by the natural gas liquefaction unit 2, a pre-cooling cold box, a primary purification tower and a secondary purification tower are set in the demethanizer 1, and corresponding coolers and separators are equipped to form a complete and efficient demethanization process flow.

[0034] In this embodiment, the liquid phase outlet of the secondary concentration tower is connected to the demethanizer, and the gas phase outlet of the demethanizer is connected to a pre-cooling cold box. The demethanizer can also be equipped with multiple liquid-phase side pipelines based on cooling capacity gradients, extracting different amounts of liquid streams in a gradient for cooling recovery. By controlling key parameters such as the number of liquid streams extracted from the demethanizer, extraction location, and extraction volume, comprehensive cooling capacity utilization is achieved, ensuring energy efficiency.

[0035] In the embodiment, the pre-cooling compressor, the first-stage compressor and the second-stage compressor are used to provide sufficient cooling capacity to match the natural gas during the demethanization and concentration process.

[0036] The system further includes a supplementary cooling line, which is connected to the pre-cooling line 4. In order to increase the flow rate of the pre-cooling line 4 to provide a better supplementary cooling effect and reduce the flow pressure of the pre-cooling line 4, the present application further provides a supplementary cooling line (not shown in the figure). The supplementary cooling line is connected to the pre-cooling line 4 and uses the same refrigerant medium to supplementary cool the secondary concentration tower 11.

[0037] The utility model discloses a pre-cooling line supplementary cooling system, which avoids being intercepted by the natural gas liquefaction device by setting up the pre-cooling pipeline, fundamentally eliminates the obstruction of the cold capacity transmission path, and ensures that the temperature of the flow channel pipeline between the secondary concentration tower of the demethanizer and the pre-cooling cold box can be stably maintained within a preset temperature range. It not only realizes efficient supplementary cooling for the secondary concentration tower, but also ensures accurate matching of the temperature level in the entire system, which is crucial to the stable operation of the demethanizer and ensures the stability and reliability of the demethanizer.

[0038] This device also has the effect of significantly improving energy efficiency and saving costs. By optimizing the use of cooling capacity, it reduces unnecessary energy loss and improves the energy efficiency of the entire system. At the same time, it further enhances economic benefits by reducing downtime and maintenance costs caused by equipment failure.

[0039] It should be noted that, in the description of this application, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance. In addition, in the description of this application, unless otherwise specified, the meaning of "plurality" is two or more.

[0040] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code comprising one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may be performed out of the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present application belong.

[0041] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0042] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A pre-cooling line cooling system, characterized in that: include: A demethanization device, wherein the demethanization device is provided with a secondary concentration tower; A natural gas liquefaction device connected to a secondary concentration tower pipeline; A pre-cooling regulating valve group, which is installed on the pipeline connecting the natural gas liquefaction device and the secondary concentration tower; The precooling pipeline is connected to the pipelines of the natural gas liquefaction device and the secondary concentration tower.

2. A pre-cooling line supplementary cooling system according to claim 1, characterized in that: The pre-cooling regulating valve group includes a second manual valve, a pre-cooling regulating valve and a first manual valve which are sequentially arranged in the natural gas transmission direction.

3. A pre-cooling line supplementary cooling system according to claim 2, characterized in that: The pre-cooling pipeline is arranged between the pre-cooling regulating valve and the first manual valve.

4. A pre-cooling line supplementary cooling system according to any one of claims 1 or 2, characterized in that: It also includes a branch pipeline, wherein one end of the branch pipeline is arranged before the second hand valve, and the other end is arranged after the first hand valve.

5. The pre-cooling line supplementary cooling system according to claim 1, characterized in that: The demethanizer comprises a pre-cooling cold box, a primary purification tower and a secondary purification tower connected in sequence. The primary purification tower is connected to a primary cooler and a primary separator respectively, and the secondary purification tower is connected to a secondary cooler and a secondary separator respectively.

6. A pre-cooling line supplementary cooling system according to claim 5, characterized in that: The invention also comprises a demethanizer, wherein one end of the demethanizer is connected to the secondary purification tower, and the other end is connected to the pre-cooling cold box.

7. A pre-cooling line supplementary cooling system according to claim 5, characterized in that: A pre-cooling compressor is provided in the pre-cooling cold box.

8. The pre-cooling line supplementary cooling system according to claim 5, characterized in that: A first-stage compressor is provided in the first-stage cooler.

9. The pre-cooling line supplementary cooling system according to claim 5, characterized in that: A secondary compressor is provided in the secondary cooler.

10. The pre-cooling line supplementary cooling system according to claim 1, characterized in that: It also includes a supplementary cooling line, wherein the supplementary cooling line is connected to the pre-cooling line.

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