Apparatus and method for application of multiple energy coupling capability reengineering in lng receiving terminals and ethylene cracking processes
By introducing multiple energy coupling devices into LNG receiving terminals and ethylene cracking processes, and utilizing the circulating heat exchange of refrigerant between different systems, the problems of high energy consumption in LNG rich liquid separation and high cost in ethylene cracking product separation have been solved, achieving efficient utilization of cold and heat energy and energy saving and consumption reduction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-12-09
- Publication Date
- 2026-06-09
AI Technical Summary
The high energy consumption in separating rich LNG, high energy consumption in vaporizing lean LNG, and high cost of separating ethylene cracking products, coupled with the difficulty in obtaining steam, leads to excessive energy consumption.
By introducing devices and methods with multiple energy coupling capabilities into LNG receiving terminals and ethylene cracking processes, and utilizing the circulating heat exchange of refrigerant between heating, LNG purification, ethylene cracking, and separation systems, comprehensive utilization of cold and heat can be achieved, thereby reducing energy consumption and costs.
It has achieved effective and comprehensive utilization of cold and heat energy in LNG receiving terminals and chemical plants, reduced production and separation costs, recovered cold energy for ethylene plants, provided high-quality cracking feedstock, and achieved significant energy-saving effects.
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Figure CN122168330A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of petrochemicals, specifically to an apparatus and method for the regeneration of multiple energy coupling capabilities in LNG receiving terminals and ethylene cracking processes. Background Technology
[0002] In recent years, with the rapid development of the ethylene industry, the capacity of ethylene plants has increased year by year, the technology has become increasingly advanced, and ethylene production has increased significantly. The issues of energy conservation, consumption reduction, and carbon emission reduction in ethylene plants have also received increasing attention. To ensure the separation of hydrogen, methane, ethylene, propylene, and other products from the cracked gas after the high-temperature cracking reaction in the steam cracking ethylene unit, different temperature-grade cryogenic refrigerants are required during normal production. Generally, the cryogenic refrigerants required by traditional ethylene plants are provided by propylene refrigeration compressors, ethylene refrigeration compressors, and methane refrigeration compressors. The energy consumption of the refrigeration compressors is one of the important indicators affecting the overall energy consumption of the ethylene plant.
[0003] Against the backdrop of the continuous development of the new energy industry and the increasingly severe energy and environmental problems, how to further improve the effective utilization of cold energy in LNG receiving terminals has become a new challenge.
[0004] Currently, the cooling capacity of the low-temperature lean LNG (-170℃) that was originally used for vaporization of seawater and propylene at the LNG receiving terminal has been exchanged with the surplus heat of the newly built 1.2 million tons / year ethylene plant. This coupled development approach achieves comprehensive regional development, reduces carbon emissions, and lowers the energy consumption per ton of product for the ethylene plant, thereby enhancing competitiveness with green advantages. It is the first time in China that the integrated utilization of cold and heat energy from LNG receiving terminals and ethylene plants has been adopted.
[0005] Currently, conventional LNG rich liquid separation units require steam (0.4 MPaG) as their heat source for separation, with a consumption of 23 tons / hour. This presents problems such as difficulty in obtaining steam and high energy consumption. Summary of the Invention
[0006] The purpose of this invention is to overcome the problems of high energy consumption in the separation of rich LNG (liquefied natural gas), high energy consumption in the vaporization of lean LNG, and high cost in the separation of ethylene cracking products in the existing technology, and to provide an apparatus and method for the application of multiple energy coupling capacity regeneration in LNG receiving terminals and ethylene cracking processes. This apparatus has low energy consumption and low cost in the separation of LNG and ethylene cracking products.
[0007] To achieve the above objectives, the present invention provides an apparatus for the application of multiple energy coupling capacity regeneration in LNG receiving terminals and ethylene cracking processes, the apparatus comprising:
[0008] Heating system, used to heat refrigerant to obtain high-temperature refrigerant;
[0009] The LNG purification system is used to receive high-temperature refrigerant from the heating system and exchange heat between the high-temperature refrigerant and LNG to obtain low-temperature refrigerant;
[0010] An ethylene cracking system is used to crack ethylene-containing hydrocarbon feedstocks to obtain cracking products.
[0011] A separation system is used to receive cryogenic refrigerant from an LNG purification system and cracking products from an ethylene cracking system, and to exchange heat between the cryogenic refrigerant and the cracking products and / or the cooling medium for the cracking products to obtain a medium-temperature refrigerant.
[0012] The medium-temperature refrigerant outlet of the separation system is connected to the refrigerant inlet of the heating system via a pipeline.
[0013] The second aspect of this invention provides a method for the regeneration of multiple energy coupling capabilities in LNG receiving terminals and ethylene cracking processes. This method is carried out in the apparatus described in the first aspect of this invention and includes the following steps:
[0014] (a) The refrigerant is fed into the heating system for heating to obtain a high-temperature refrigerant;
[0015] (b) A high-temperature refrigerant is introduced into the LNG purification system to exchange heat with the LNG in the LNG purification system to obtain a low-temperature refrigerant;
[0016] (c) The low-temperature refrigerant is introduced into the separation system to exchange heat with the pyrolysis products and / or the cooling medium of the pyrolysis products to obtain the medium-temperature refrigerant;
[0017] (d) Introduce medium-temperature refrigerant into the heating system for heating to obtain high-temperature refrigerant;
[0018] (e) Repeat steps (b)-(d).
[0019] Through the above technical solution, the present invention has the following advantages:
[0020] This invention utilizes intermediate media, namely refrigerant heat exchange pipelines and equipment, to recreate the multi-energy coupling capacity between LNG receiving terminals and ethylene projects. It recovers the cold energy of lean LNG for use in ethylene plants, achieving effective comprehensive utilization of cold and heat energy in LNG receiving terminals and chemical plants. This reduces production and separation costs and energy consumption. In the preferred embodiment, the heat source supplied by the intermediate media separates and purifies the C2+ product from the rich LNG, while simultaneously providing high-quality cracking feedstock for the ethylene plants. Attached Figure Description
[0021] Figure 1 This is an apparatus and flowchart of a preferred embodiment of the present invention for coupling LNG purification and ethylene cracking. Detailed Implementation
[0022] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0023] In this invention, "high temperature," "low temperature," and "medium temperature" are all relative concepts compared to the refrigerant feed temperature, i.e., the ambient temperature, and all refer to temperature ranges, not single point values. Specifically, high temperature is greater than medium temperature, which is greater than ambient temperature, which is greater than low temperature. Typically, in the process of this invention, the high temperature range is 50-100℃; the medium temperature range is 30-60℃; the low temperature range is -100 to -50℃; and the temperature of the refrigerant feedstock is the ambient temperature, typically 0-30℃.
[0024] This invention provides an apparatus for the application of multiple energy coupling capacity regeneration in LNG receiving terminals and ethylene cracking processes, the apparatus comprising:
[0025] Heating system, used to heat refrigerant to obtain high-temperature refrigerant;
[0026] The LNG purification system is used to receive high-temperature refrigerant from the heating system and exchange heat between the high-temperature refrigerant and LNG to obtain low-temperature refrigerant;
[0027] An ethylene cracking system is used to crack ethylene-containing hydrocarbon feedstocks to obtain cracking products.
[0028] A separation system is used to receive cryogenic refrigerant from an LNG purification system and cracking products from an ethylene cracking system, and to exchange heat between the cryogenic refrigerant and the cracking products and / or cracking products to obtain a medium-temperature refrigerant;
[0029] The medium-temperature refrigerant outlet of the separation system is connected to the refrigerant inlet of the heating system via a pipeline.
[0030] This invention utilizes intermediate media, namely refrigerant heat exchange pipelines and equipment, to recreate multiple energy coupling capabilities between LNG receiving terminals and ethylene projects, recovering the cold energy of lean LNG for use in ethylene plants. This enables the effective comprehensive utilization of cold and heat energy in LNG receiving terminals and chemical plants, reducing production and separation costs and energy consumption.
[0031] In this invention, the heating system, LNG purification system, ethylene cracking system, and separation system all include conventional devices with corresponding functions in the art. For example, the heating system may include electric heaters, heat exchangers, etc.; the LNG purification system may include separation towers, etc.; the ethylene cracking system may include commonly used cracking equipment, such as cracking furnaces; and the separation system may include a series of separation towers, the specific selection of which depends on the operating conditions.
[0032] According to a preferred embodiment of the present invention, the LNG purification system includes a heating unit that, together with a high-temperature refrigerant, provides heat for LNG purification, thereby enabling the LNG to be separated by heating to obtain NG and C2. + For hydrocarbons, a reboiler is preferred as the heating unit.
[0033] According to a preferred embodiment of the present invention, the C2 of the LNG purification system + The hydrocarbon outlet is connected to the ethylene-containing hydrocarbon feedstock of the ethylene cracking system via a pipeline. Preferably, the connecting pipeline is equipped with C2. + Hydrocarbon heating unit.
[0034] According to a preferred embodiment of the present invention, the LNG purification system includes an LNG rich liquid purification unit and an LNG lean liquid vaporization unit connected in series. A high-temperature refrigerant is introduced into the LNG rich liquid purification unit to exchange heat with the LNG rich liquid to obtain a medium-temperature refrigerant. The medium-temperature refrigerant is then introduced into the LNG lean liquid vaporization unit to exchange heat with the LNG lean liquid to obtain a low-temperature refrigerant.
[0035] According to a preferred embodiment of the present invention, the LNG rich liquid purification unit is provided with an LNG lean liquid outlet and a C2 outlet. + The hydrocarbon export unit and the LNG lean gasification unit are equipped with an LNG lean liquid inlet and an NG (natural gas) outlet. The LNG lean liquid outlet of the LNG rich liquid purification unit and the LNG lean liquid inlet of the LNG lean liquid gasification unit are connected by a pipeline.
[0036] According to a preferred embodiment of the present invention, the separation system further includes a refrigeration unit, which, together with the cryogenic refrigerant and the cooling medium for the pyrolysis products, provides cooling to the pyrolysis products, thereby separating the pyrolysis products into at least one of hydrogen, methane, polymer-grade ethylene, polymer-grade propylene, C4, pyrolysis gasoline, and pyrolysis fuel oil.
[0037] According to a preferred embodiment of the present invention, the refrigeration unit is at least one of a propylene refrigeration unit, an ethylene refrigeration unit, and a methane refrigeration unit.
[0038] This invention provides a method for regenerating multiple energy coupling capabilities in LNG receiving terminals and ethylene cracking processes. The method is carried out in the aforementioned apparatus and includes the following steps:
[0039] (a) The refrigerant is fed into the heating system for heating to obtain a high-temperature refrigerant;
[0040] (b) A high-temperature refrigerant is introduced into the LNG purification system to exchange heat with the LNG in the LNG purification system to obtain a low-temperature refrigerant;
[0041] (c) The low-temperature refrigerant is introduced into the separation system to exchange heat with the pyrolysis products and / or the cooling medium of the pyrolysis products to obtain the medium-temperature refrigerant;
[0042] (d) Introduce medium-temperature refrigerant into the heating system for heating to obtain high-temperature refrigerant;
[0043] (e) Repeat steps (b)-(d).
[0044] According to a preferred embodiment of the present invention, the refrigerant is an alcohol compound and / or a fluorine compound, preferably an alcohol compound, more preferably a C1-C3 alcohol compound, and more preferably methanol.
[0045] According to a preferred embodiment of the present invention, the method further includes: separating the C2 obtained after heat exchange of the LNG in step (b). + Hydrocarbons are fed into the ethylene cracking system for cracking.
[0046] According to a preferred embodiment of the present invention, the method further includes: the LNG heat exchange in step (b) includes first separating the rich LNG solution from the high-temperature refrigerant through heat exchange to obtain lean LNG solution and C2. + Hydrocarbons, LNG lean liquid and medium-temperature refrigerant are reheated to obtain NG; the medium-temperature refrigerant is the medium-temperature refrigerant obtained after heat exchange between high-temperature refrigerant and LNG rich liquid.
[0047] According to a preferred embodiment of the present invention, the method further includes: in step (c), the refrigeration unit, the low-temperature refrigerant, and the pyrolysis product cooling medium together provide cooling to the pyrolysis products, so that the pyrolysis products are separated into at least one of hydrogen, methane, polymer-grade ethylene, polymer-grade propylene, C4, pyrolysis gasoline, and pyrolysis fuel oil.
[0048] According to a preferred embodiment of the present invention, the cooling medium for the pyrolysis products in the method is quench water.
[0049] The present invention will be described in detail below through embodiments.
[0050] Example 1
[0051] The ability to regenerate multiple energy coupling capabilities between the LNG receiving terminal and the adjacent Nangang ethylene project is being realized. Figure 1 The procedure is carried out in the apparatus shown, and the process is as follows:
[0052] (a) The methanol material is fed into a heating system for heating to obtain high-temperature methanol;
[0053] (b) High-temperature methanol is introduced into the LNG purification system to exchange heat with the LNG-rich liquid in the LNG purification system. When the heat is insufficient, C2 is achieved in conjunction with a reboiler (heater and 0.4 MPaG steam as heat source). + Hydrocarbons are separated, and low-temperature methanol is obtained simultaneously;
[0054] (c)C2 + Hydrocarbons are fed into the ethylene cracking system as cracking feedstock. The cracking products are then fed into the separation system. Low-temperature methanol is then fed into the separation system of the ethylene cracking unit. Together with the propylene refrigeration unit, ethylene refrigeration unit, methane refrigeration unit, and quench water, methanol provides cooling to the separation system of the ethylene cracking unit, cooling the cracking products and achieving the separation of hydrogen, methane, polymer-grade ethylene, polymer-grade propylene, C4, cracked gasoline, and cracked fuel oil. Finally, the methanol is exchanged with quench water to obtain medium-temperature methanol.
[0055] (d) Medium-temperature methanol is passed into a heating system and heated to obtain high-temperature methanol;
[0056] (e) Repeat steps (b)-(d).
[0057] Compared to schemes that only use steam (0.4 MPaG) as the heat source for LNG separation and only use propylene refrigeration units, ethylene refrigeration units, methane refrigeration units, and quench water to provide cooling for the separation of cracking products, the above scheme of the present invention utilizes an intermediate medium to recreate the multi-energy coupling capacity between the LNG receiving terminal and the ethylene cracking project. The heat source mutually supplied through the intermediate medium is used to separate C2 from the LNG-rich liquid. + The separated products provide high-quality cracking feedstock for the ethylene plant, while the cold energy of the recovered lean LNG is used in the ethylene cracking product separation unit. This achieves effective and comprehensive utilization of the cold and heat energy of the LNG receiving station and chemical plant, greatly reducing production, separation costs and energy consumption.
[0058] Specific implementation results:
[0059] 1. While maintaining the original plan to recover 55MW of lean LNG cooling energy, C2 can be recovered annually from the moisture. + The plant produces 400,000 tons of hydrocarbons (mainly ethane and propane), which can provide more high-quality cracking feedstock for ethylene plants.
[0060] 2. The heat lost during the separation of ethylene feedstock is recovered by using methanol and supplied to the LNG rich liquid reboiler, which solves the problem of requiring 23 tons / hour of steam for LNG rich liquid separation.
[0061] 3. The low-temperature C2+ generated by LNG rich liquid separation can be used in other devices requiring cooling capacity;
[0062] 4. Compared with existing solutions, the present invention can save 1,500 kg of standard oil per hour at LNG receiving stations.
[0063] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.
Claims
1. An apparatus for the regeneration of multiple energy coupling capabilities in LNG receiving terminals and ethylene cracking processes, characterized in that, The device includes: Heating system, used to heat refrigerant to obtain high-temperature refrigerant; The LNG purification system is used to receive high-temperature refrigerant from the heating system and exchange heat between the high-temperature refrigerant and LNG to obtain low-temperature refrigerant; An ethylene cracking system is used to crack ethylene-containing hydrocarbon feedstocks to obtain cracking products. A separation system is used to receive cryogenic refrigerant from an LNG purification system and cracking products from an ethylene cracking system, and to exchange heat between the cryogenic refrigerant and the cracking products and / or the cooling medium for the cracking products to obtain a medium-temperature refrigerant. The medium-temperature refrigerant outlet of the separation system is connected to the refrigerant inlet of the heating system via a pipeline.
2. The apparatus according to claim 1, wherein, The LNG purification system includes a heating unit that, together with a high-temperature refrigerant, provides heat for LNG purification, enabling the LNG to be separated into NG and C2 by heating. + hydrocarbon.
3. The apparatus according to claim 2, wherein, C2 of the LNG purification system + The hydrocarbon outlet is connected to the ethylene-containing hydrocarbon feedstock of the ethylene cracking system via a pipeline. Preferably, the connecting pipeline is equipped with C2. + Hydrocarbon heating unit.
4. The apparatus according to any one of claims 1-3, wherein, The LNG purification system includes an LNG rich liquid purification unit and an LNG lean liquid vaporization unit connected in series. High-temperature refrigerant is introduced into the LNG rich liquid purification unit to exchange heat with the LNG rich liquid to obtain medium-temperature refrigerant. The medium-temperature refrigerant is then introduced into the LNG lean liquid vaporization unit to exchange heat with the LNG lean liquid to obtain low-temperature refrigerant.
5. The apparatus according to claim 4, wherein, The LNG rich liquor purification unit is equipped with an LNG lean liquor outlet and a C2 outlet. + The hydrocarbon outlet and the LNG lean gasification unit are equipped with an LNG lean inlet and an NG outlet. The LNG lean outlet of the LNG rich purification unit is connected to the LNG lean inlet of the LNG lean gasification unit via a pipeline.
6. The apparatus according to any one of claims 1-5, wherein, The separation system also includes a refrigeration unit, which, together with the low-temperature refrigerant and the cooling medium for the cracking products, provides cooling to the cracking products, thereby separating the cracking products into at least one of hydrogen, methane, polymer-grade ethylene, polymer-grade propylene, C4, cracked gasoline, and cracked fuel oil.
7. The apparatus according to claim 6, wherein, The refrigeration unit is at least one of a propylene refrigeration unit, an ethylene refrigeration unit, and a methane refrigeration unit.
8. A method for regenerating multiple energy coupling capabilities in LNG receiving terminals and ethylene cracking processes, characterized in that, The method is performed in the apparatus according to any one of claims 1-7, and the method includes the following steps: (a) The refrigerant is fed into the heating system for heating to obtain a high-temperature refrigerant; (b) A high-temperature refrigerant is introduced into the LNG purification system to exchange heat with the LNG in the LNG purification system to obtain a low-temperature refrigerant; (c) The low-temperature refrigerant is introduced into the separation system to exchange heat with the pyrolysis products and / or the cooling medium of the pyrolysis products to obtain the medium-temperature refrigerant; (d) Introduce medium-temperature refrigerant into the heating system for heating to obtain high-temperature refrigerant; (e) Repeat steps (b)-(d).
9. The method according to claim 8, wherein, The refrigerant is an alcohol compound and / or a fluorine compound, preferably an alcohol compound, more preferably a C1-C3 alcohol compound, and even more preferably methanol.
10. The method according to claim 9, wherein, The method further includes: The C2 obtained after heat exchange of LNG in step (b) + Hydrocarbons are fed into the ethylene cracking system for cracking; and / or Step (b) involves LNG heat exchange, which first separates the rich LNG solution from the high-temperature refrigerant to obtain lean LNG solution and C2. + Hydrocarbons, LNG lean liquid and intermediate-temperature refrigerant are reheated to obtain NG; the intermediate-temperature refrigerant is the intermediate-temperature refrigerant obtained after heat exchange between high-temperature refrigerant and LNG rich liquid; and / or In step (c), the refrigeration unit, the low-temperature refrigerant, and the pyrolysis product cooling medium together provide cooling for the pyrolysis products, so that the pyrolysis products are separated into at least one of hydrogen, methane, polymer-grade ethylene, polymer-grade propylene, C4, pyrolysis gasoline, and pyrolysis fuel oil. Preferably, the pyrolysis product cooling medium is quench water.