A method and system for recovering waste heat from an organic liquid hydrogen storage process

Abstract

The present application provides a method and system for recovering waste heat from an organic liquid hydrogen storage process, the method comprising: subjecting the high-temperature gaseous hydrogenation product output from the reaction device to heat exchange with a liquid hydrogen storage carrier having a pressure lower than that required for the hydrogenation reaction, so that the liquid hydrogen storage carrier is heated and vaporized to obtain a gaseous hydrogen storage carrier, pressurizing the gaseous hydrogen storage carrier to make the gaseous hydrogen storage carrier reach the pressure of the hydrogenation reaction, and obtaining a gaseous hydrogen storage carrier that meets the temperature and pressure requirements of the hydrogenation reaction; and inputting the gaseous hydrogen storage carrier and hydrogen that meet the temperature and pressure requirements of the hydrogenation reaction into the reaction device for hydrogenation reaction to obtain a high-temperature gaseous hydrogenation product. The above method can be used to efficiently recover and utilize the waste heat generated during the hydrogen storage process through the designed new system, further enhancing the energy-saving effect of the organic liquid hydrogen storage process.

Description

Technical Field

[0001] The present application relates to the technical field of organic liquid hydrogen storage, and in particular to a method and system for recovering waste heat from an organic liquid hydrogen storage process. Background Art

[0002] Hydrogen energy is one of the cleanest and most efficient energy sources, but due to its special physical and chemical properties, its large-scale long-distance storage and transportation is extremely difficult, which seriously limits the large-scale application of hydrogen energy. Organic liquid hydrogen storage technology has the advantages of large hydrogen storage capacity, high safety, and the ability to use existing oil storage and transportation facilities. It is regarded as the most promising hydrogen storage and transportation technology.

[0003] The specific process of the above organic liquid hydrogen storage process is: heat the hydrogen storage carrier and hydrogen separately to completely vaporize the hydrogen storage carrier, and then introduce them into the reaction device to react under the action of the catalyst. After the reaction product leaves the reaction device, it enters the water cooling device for condensation and cooling, and then enters the gas-liquid separation device for separation. The hydrogen-rich organic liquid enters the liquid storage device, and the hydrogen returns to the front end for recycling. However, the above process generally has the problems of high energy consumption, imperfect thermal management, and low comprehensive energy efficiency utilization, and special thermal design is required for the process.

[0004] The conventional thermal design currently used is to use the reaction products to preheat the reaction raw materials to achieve heat recovery. However, during the hydrogen storage process, there is a mismatch between the heat load and heat exchange temperature of the hydrogen storage carrier and the hydrogen-rich organic liquid, resulting in a large amount of waste heat generated in the hydrogen storage process that cannot be utilized, and its energy-saving effect is poor. Summary of the invention

[0005] To solve the above problems, the present application provides a method and system for recovering waste heat from an organic liquid hydrogen storage process. By using this method, the waste heat generated during the hydrogen storage process can be efficiently recovered and utilized through a newly designed system, thereby further enhancing the energy-saving effect of the organic liquid hydrogen storage process.

[0006] In a first aspect, the present application provides a method for recovering waste heat from an organic liquid hydrogen storage process, the method comprising:

[0007] S1, performing heat exchange treatment on the high-temperature gaseous hydrogenation product output from the reaction device and a liquid hydrogen storage carrier having a pressure lower than the pressure required for the hydrogenation reaction, so that the liquid hydrogen storage carrier is heated and vaporized to obtain a gaseous hydrogen storage carrier;

[0008] S2, pressurizing the gaseous hydrogen storage carrier to make the gaseous hydrogen storage carrier reach the pressure of the hydrogenation reaction, and obtaining the gaseous hydrogen storage carrier that meets the temperature and pressure requirements of the hydrogenation reaction;

[0009] S3, inputting the gaseous hydrogen storage carrier and hydrogen that meet the hydrogenation reaction temperature and pressure requirements into the reaction device for hydrogenation reaction to obtain the high-temperature gaseous hydrogenation product;

[0010] Wherein, the high-temperature gaseous hydrogenation product includes: vaporized hydrogen-rich organic liquid and hydrogen.

[0011] Optionally, the method further comprises:

[0012] S4, after the high-temperature gaseous hydrogenation product is subjected to heat exchange treatment in S1, it is cooled and separated in sequence to obtain hydrogen-rich organic liquid and hydrogen.

[0013] Optionally, in step S4, the hydrogen obtained from the separation process is reused and reused in the hydrogenation reaction.

[0014] In a second aspect, the present application provides a waste heat recovery system for an organic liquid hydrogen storage process, the system being applicable to the waste heat recovery method for the organic liquid hydrogen storage process described in the first aspect, the system comprising: a carrier storage device (1), a hydrogen storage device (2), a heat exchange device (3), a pressurizing device (4) and a reaction device (5);

[0015] The discharge port of the reaction device (5) is connected to the hot flow inlet of the heat exchange device (3) to provide the high-temperature gaseous hydrogenation product to the heat exchange device (3); the outlet of the carrier storage device (1) is connected to the cold flow inlet of the heat exchange device (3) to provide the liquid hydrogen storage carrier to the heat exchange device (3); in the heat exchange device (3), the liquid hydrogen storage carrier exchanges heat with the high-temperature gaseous hydrogenation product to obtain the gaseous hydrogen storage carrier;

[0016] The cold logistics outlet of the heat exchange device (3) is connected to the booster device (4) for passing the gaseous hydrogen storage carrier into the booster device (4) for pressurization treatment, so that the gaseous hydrogen storage carrier reaches the pressure of the hydrogenation reaction, and the gaseous hydrogen storage carrier that meets the temperature and pressure requirements of the hydrogenation reaction is obtained, and is passed into the feed port of the reaction device (5);

[0017] The hydrogen storage device (2) is connected to the feed port of the reaction device (5) and is used to provide the hydrogen to the reaction device (5); after the hydrogenation reaction is completed in the reaction device (5), the high-temperature gaseous hydrogenation product is obtained.

[0018] Optionally, the hydrogenation reaction temperature of the gaseous hydrogen storage carrier is 150~350℃.

[0019] Optionally, when the hydrogenation reaction temperature of the gaseous hydrogen storage carrier is 200°C;

[0020] In step S1, the temperature of the liquid hydrogen storage carrier after heating and vaporization is 180°C~200°C; in step S2, the temperature of the gaseous hydrogen storage carrier after pressurization treatment is 210°C~250°C.

[0021] Optionally, in step S1, the difference between the dew point temperature of the liquid hydrogen storage carrier and the dew point temperature of the pressurized high-temperature gaseous hydrogenation product is greater than the minimum heat transfer temperature difference.

[0022] Optionally, in step S1, the pressure of the liquid hydrogen storage carrier whose pressure is lower than the pressure required for the hydrogenation reaction is 0.5 bar to 4 bar;

[0023] In step S2, the pressure of the gaseous hydrogen storage carrier after the pressurization treatment is 4 bar to 8 bar.

[0024] Optionally, the system further comprises: a cooling device (6), a separation device (7) and a hydrogen-rich organic liquid storage device (8) connected in sequence;

[0025] The hot flow outlet of the reaction device (5) is connected to the inlet of the cooling device (6) for cooling the high-temperature gaseous hydrogenation product after the heat exchange is completed; the separation device (7) is used to separate the cooled product to obtain hydrogen-rich organic liquid and hydrogen;

[0026] The hydrogen-rich organic liquid storage device (8) is used to store the hydrogen-rich organic liquid obtained after cooling and separation.

[0027] Optionally, the temperature of the high-temperature gaseous hydrogenation product after the heat exchange is completed is cooled to 20°C~50°C;

[0028] The hydrogen separated by the separation device (7) is transported to the reaction device (5) to continue participating in the hydrogenation reaction.

[0029] Through the above method, the phase change temperature of the cold flow (hydrogen storage carrier) is appropriately lowered from a higher temperature to change the phase change temperature mismatch between the hydrogen storage carrier and the gaseous hydrogenation product, greatly increase the heat exchange between the product and the raw material, and thus significantly reduce the use of additional cold and hot utilities, thereby achieving energy saving effects to the greatest extent. The energy during the operation of the device can be self-supplied, so as to improve the comprehensive energy utilization rate of the organic liquid hydrogen storage process and reduce process energy consumption and operating costs.

[0030] It should be noted that after the gaseous hydrogen storage carrier is pressurized, the temperature also rises slightly. The gaseous hydrogen storage carrier at this temperature is in an overheated state, which is more conducive to promoting the hydrogenation reaction and increasing the reaction rate.

[0031] In summary, the present application includes at least one of the following beneficial technical effects:

[0032] 1. The present application provides a waste heat recovery and utilization method of an organic liquid hydrogen storage process. During the implementation, the phase change temperature of the liquid hydrogen storage carrier whose pressure is lower than the pressure required for the hydrogenation reaction is further reduced, breaking the mismatching of the phase change temperature of the hydrogen storage carrier and the gaseous hydrogenation product. After the gaseous hydrogenation product and the hydrogen storage carrier are heat-exchanged, the hydrogen storage carrier undergoes temperature increase and vaporization, and the gaseous hydrogenation product undergoes temperature decrease and liquefaction. Both of them realize phase change, significantly improving the heat exchange between the product and the raw material, and increasing the self-supply ratio of the energy for preheating the raw material (liquid hydrogen storage carrier) from less than 50% to more than 80%, greatly improving the energy utilization rate of the organic liquid hydrogenation process, and significantly reducing the supply of cold and hot utilities, reducing operating costs, and enhancing energy-saving effects;

[0033] 2. The present application provides a waste heat recovery and utilization system for an organic liquid hydrogen storage process. The system does not require an evaporator and can vaporize all the raw materials solely through the waste heat of the product, thereby helping to reduce the extra consumption of heat utilities. At the same time, after the heat of the product is exchanged more, it also helps to further reduce the cold utilities consumed by cooling the product, thereby achieving high efficiency and energy saving. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0035] Figure 1 It is a system diagram of hydrogenation process proposed by the prior art;

[0036] Figure 2 It is another hydrogenation process system diagram proposed in the prior art;

[0037] Figure 3 is a reaction system diagram of the conventional thermal design proposed in Example 1;

[0038] Figure 4 It is a temperature enthalpy diagram of the heat exchange process between the hydrogen storage carrier and the gaseous hydrogenation product proposed in the prior art;

[0039] Figure 5 It is the temperature enthalpy diagram of the heat exchange process of the hydrogen storage carrier and the gaseous hydrogenation product proposed in this application;

[0040] Figure 6 This is a flow chart of the waste heat recovery and utilization method of the organic liquid hydrogen storage process proposed in this application;

[0041] Figure 7This is a reaction system diagram of waste heat recovery and utilization of the organic liquid hydrogen storage process proposed in Example 1 of the present application;

[0042] Figure 8 is a reaction system diagram of the conventional thermal design proposed in Example 2;

[0043] Fig. 9 This is a reaction system diagram for waste heat recovery and utilization of the organic liquid hydrogen storage process proposed in Example 2 of the present application.

[0044] Description of reference numerals:

[0045] 1. Carrier storage device; 2. Hydrogen storage device; 3. Heat exchange device; 4. Pressurization device; 5. Reaction device; 6. Cooling device; 7. Separation device; 8. Hydrogen-rich organic liquid storage device. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0047] In the drawings, the size of the constituent elements, the thickness of the layer or the area may be exaggerated for the sake of clarity. Therefore, any implementation of the present disclosure is not necessarily limited to the size shown in the drawings, and the shapes and sizes of the components in the drawings do not reflect the true proportions. In addition, the drawings schematically show ideal examples, and any implementation of the present disclosure is not limited to the shapes or values ​​shown in the drawings.

[0048] The essence of the organic liquid hydrogen storage process is to make the hydrogen-free hydrogen storage carrier and hydrogen undergo a hydrogenation reaction to generate a hydrogen-containing hydrogen-rich organic liquid. In the prior art, 500 kg H2 / d of paraxylene is used as the injection amount to describe the traditional organic liquid hydrogen storage process in detail. The reaction system is referred to Figure 1 :

[0049] 1. With 8812 kg / d of paraxylene and 500 kg / d of hydrogen as feed, 4 bar of paraxylene is heated from 25 °C to 200 °C in a preheater and then enters the reactor. The 4 bar of hydrogen is mixed with the 3 bar, 200 kg / d of hydrogen recycled from the rear end and enters the reactor;

[0050] 2. All the p-xylene in the reactor is converted into p-dimethylcyclohexane. All the products are discharged from the reactor at 4 bar and 210°C and then enter the water cooler for condensation and cooling. After cooling to 40°C, they enter the gas-liquid separator for separation, and finally 9312 kg / d of p-dimethylcyclohexane is obtained. In this process, the preheater needs to provide 1585 kW of heat from the heat transfer oil, and the water cooler takes away 1782 kW of heat.

[0051] If 1000 kg H2 / d of toluene is used as the injection volume, the operation steps are exactly the same as the above steps, the only difference is the reaction parameters. For details, see Figure 2 .

[0052] In summary, in the reaction system of the organic liquid hydrogenation process in the prior art, the heat of the product needs to be taken away by the cooler, and the raw materials also need to be heated by heat transfer oil, resulting in high energy consumption in the process, imperfect thermal management, and low overall energy efficiency utilization.

[0053] To solve the above problems, the commonly used thermal design solution is to use the reaction products to preheat the reaction raw materials to achieve heat recovery. If this thermal design is applied to the organic liquid hydrogen storage process, the waste heat of the hydrogen storage process can in principle achieve heat complementarity between the hydrogen storage carrier and the gaseous hydrogenation product. However, during the hydrogen storage process, there is a mismatch in heat load and heat exchange temperature between the hydrogen storage carrier and the gaseous hydrogenation product, resulting in a large amount of waste heat that cannot be utilized when this design is adopted, and there is still a large space for energy saving.

[0054] In order to enable those skilled in the art to better understand the present application, the following is an explanation of a waste heat recovery method and system for an organic liquid hydrogen storage process provided by the present application through a number of specific embodiments and comparative examples.

[0055] See also Figure 3 , this application further explains the conventional design scheme of using reaction products to preheat reaction raw materials.

[0056] Comparative Example 1:

[0057] 1. After leaving the reactor, the gaseous p-dimethylcyclohexane enters the product-raw material heat exchanger, where the gaseous p-dimethylcyclohexane is cooled from 210°C to 128°C, and the liquid p-xylene is heated from 25°C to 198°C (at 4 bar pressure, p-xylene is still liquid). The heated liquid p-xylene then enters the evaporator for vaporization;

[0058] 2. The vaporized p-xylene enters the reactor for hydrogenation reaction with hydrogen to obtain a hydrogenation product, which includes vaporized p-dimethylcyclohexane and hydrogen;

[0059] 3. The gaseous p-dimethylcyclohexane enters the circulating water cooler for cooling, and after cooling, is separated by the gas-liquid separator to obtain liquid p-dimethylcyclohexane, and the obtained liquid p-dimethylcyclohexane is stored in a storage tank.

[0060] In the traditional thermal design of this process, the heat load of the product-feedstock heat exchanger is 835 kW, and the system still requires 749 kW of hot utilities and 946 kW of cold utilities. Compared with the original process without any integrated design, the hot utilities of this process are reduced by 52.68% and the cold utilities are reduced by 46.86%. However, there is still a large space for energy saving compared with the process to be proposed in this application.

[0061] Based on the above problems, this application analyzes the enthalpy of the heat exchange process between the hydrogen storage carrier and the gaseous hydrogenation product, as follows:

[0062] refer to Figure 4 The dew point temperature of the hydrogen storage carrier component is usually higher than the dew point temperature of the hydrogen-rich organic liquid at the same pressure, that is, the liquefaction temperature of the hot flow is lower than the vaporization temperature of the cold flow, so that part of the phase change latent heat of the heat flow cannot be used, and heat exchange can only be carried out in a small temperature range. The initial state of heat exchange of the hydrogen-rich organic liquid as a heat source is the gas phase, and the initial state of heat exchange of the hydrogen storage carrier as a heat sink is the liquid phase. The heat released during the process of cooling the hydrogen-rich organic liquid from the high-temperature gas phase to the low-temperature liquid phase can cover most of the heat required during the process of heating the hydrogen storage carrier from the low-temperature liquid phase to the high-temperature gas phase. However, due to the misalignment of the dew point temperature, only the gas phase sensible heat and part of the phase change latent heat of the hydrogen-rich organic liquid can be transferred to the hydrogen storage carrier as the liquid phase sensible heat for liquid phase heating. The remaining phase change latent heat and liquid phase sensible heat of the hydrogen-rich organic liquid must be taken away by the circulating water, and part of the liquid phase sensible heat, phase change latent heat and gas phase sensible heat of the hydrogen storage carrier must be supplied by the thermal utility. Although a certain energy-saving effect has been achieved, there is still a large space for energy saving.

[0063] It should be noted that the gaseous hydrogenation products here are mainly analyzed and explained with the gaseous hydrogen-rich organic liquid as the main component.

[0064] Based on the above problems, the present application designs a new waste heat recovery method and system for the organic liquid hydrogen storage process, which appropriately reduces the phase change temperature of the hydrogen storage carrier from a higher temperature, breaks the phase change temperature mismatch between the hydrogen storage carrier and the hydrogen-rich organic liquid, achieves better heat exchange, significantly improves the heat exchange rate between reaction products and raw materials, greatly reduces the use of cold and hot utilities, and achieves energy saving effects to the greatest extent.

[0065] In this application, the bubble point temperature of the cold flow (hydrogen storage carrier) increases with increasing pressure, so by reducing its pressure value, the bubble point temperature can be reduced. Figure 5, the heat transfer process enthalpy diagram of the hydrogen storage carrier and the gaseous hydrogenation product. It can be found that the heat transfer range of the hydrogen storage carrier and the gaseous hydrogenation product is significantly expanded, the heat transfer capacity of the two components is increased, and the waste heat of the product is more efficiently recovered and utilized.

[0066] Specifically, refer to Figure 6 In the present application, a high-temperature gaseous hydrogenation product output from a reaction device is subjected to heat exchange treatment with a liquid hydrogen storage carrier having a pressure lower than that required for a hydrogenation reaction, so that the liquid hydrogen storage carrier is heated and vaporized to obtain a gaseous hydrogen storage carrier; then, the gaseous hydrogen storage carrier is pressurized to reach the pressure of a hydrogenation reaction to obtain a gaseous hydrogen storage carrier that meets the temperature and pressure requirements of the hydrogenation reaction (the specific steps are as follows: Figure 6 In this way, no additional heat is required for the liquid hydrogen storage carrier, and the temperature and pressure required for the hydrogenation reaction can be achieved by relying only on the calorific value contained in the gaseous hydrogenation product; the surplus heat of the hydrogenation product is utilized, so that the overall energy saving effect of the organic liquid hydrogen storage process is higher than that of the existing technology and the comparative example.

[0067] Example 1

[0068] See also Figure 7 :

[0069] The feed amount is 500 kg H2 / d of paraxylene.

[0070] 1. After high-temperature gaseous dimethylcyclohexane leaves the reactor, it enters the heat exchanger. The feed pressure of liquid p-xylene in the liquid storage tank is adjusted to 2 bar, and then it is transported to the heat exchanger to perform heat exchange treatment between high-temperature gaseous dimethylcyclohexane and liquid p-xylene. The temperature of liquid p-xylene is raised from 25°C to 190°C. At this time, liquid p-xylene is completely vaporized at a pressure of 2 bar to obtain gaseous p-xylene.

[0071] 2. After leaving the heat exchanger, the gaseous para-xylene enters the compressor, and its pressure is increased from 2 bar to 4 bar. The temperature of the pressurized gaseous para-xylene rises to 211 °C, and the gaseous para-xylene that meets the temperature and pressure requirements of the hydrogenation reaction is obtained. At this time, the gaseous para-xylene is in a gas phase superheated state;

[0072] 3. The obtained gaseous p-xylene meeting the temperature and pressure requirements of the hydrogenation reaction is transported to the reactor, mixed with the hydrogen transported by the hydrogen storage tank, and then subjected to a hydrogenation reaction to obtain a high-temperature gaseous hydrogenation product, which includes vaporized p-dimethylcyclohexane and hydrogen;

[0073] 4. The vaporized p-dimethylcyclohexane is cooled from 210°C to 59°C after heat exchange, and then transported to a circulating water cooler to be further cooled to 40°C. The cooled product is separated into liquid p-dimethylcyclohexane and hydrogen by a gas-liquid separator, and the liquid p-dimethylcyclohexane is stored in a hydrogen-rich organic liquid storage tank.

[0074] Compared with comparative example 1, the heat load of the heat exchanger is significantly reduced. In Example 1, the heat load of the heat exchanger is 1555 kW, the heat load of the circulating water cooler is 232 kW, and the compressor requires 81 kW of electricity. The energy saving effect reaches 1555 kW, the hot utility is reduced by 100%, the cold utility is reduced by 87.3%, and only an additional 81 kW of electricity consumption is required. Example 1 can achieve an additional saving of 720 kW of hot and cold utilities, increasing the savings of hot utilities from 52.68% to 100%, and the savings of cold utilities from 46.86% to 87.3%, greatly improving the comprehensive utilization rate of energy and reducing the operating cost of the system.

[0075] Similarly, when the liquid hydrogen storage carrier is toluene, the comparative examples and embodiments of the waste heat recovery method and system of the organic liquid hydrogen storage process are as follows:

[0076] Comparative Example 2

[0077] See also Figure 8 :

[0078] The injection amount was 1000 kg H2 / d of toluene.

[0079] 1. After the gaseous methylcyclohexane leaves the reactor, it enters the product-raw material heat exchanger, where the gaseous methylcyclohexane is cooled from 200°C to 161°C, and the liquid toluene is heated from 25°C to 165°C (at 4 bar pressure, toluene is still liquid). The heated liquid toluene then enters the evaporator for vaporization;

[0080] 2. The vaporized toluene enters the reactor and undergoes a hydrogenation reaction with hydrogen to obtain gaseous methylcyclohexane. The hydrogenation product includes vaporized methylcyclohexane and hydrogen.

[0081] 3. The gaseous methylcyclohexane enters the circulating water cooler for cooling, and after cooling, it is separated by the gas-liquid separator to obtain liquid methylcyclohexane, and the obtained liquid methylcyclohexane is stored in a storage tank.

[0082] Example 2

[0083] See also Fig. 9 :

[0084] The injection amount was 1000 kg H2 / d of toluene.

[0085] 1. After high-temperature gaseous methylcyclohexane leaves the reactor, it enters the heat exchanger. The feed pressure of liquid toluene in the liquid storage tank is adjusted to 2 bar, and then it is transported to the heat exchanger to perform heat exchange treatment between high-temperature gaseous methylcyclohexane and liquid toluene, so that the temperature of liquid toluene is raised from 25°C to 180°C. At this time, toluene has been completely vaporized under a pressure of 2 bar to obtain gaseous toluene;

[0086] 2. After leaving the heat exchanger, the gaseous toluene enters the compressor, increasing its pressure from 2 bar to 4 bar, and the temperature of the pressurized gaseous toluene rises to 194 °C. At this time, the gaseous toluene is in a gas phase superheated state;

[0087] 3. The gaseous toluene that meets the temperature and pressure requirements of the hydrogenation reaction is transported to the reactor, mixed with the hydrogen transported by the hydrogen storage tank, and then subjected to a hydrogenation reaction to obtain a gaseous hydrogenation product (high-temperature gaseous methylcyclohexane and hydrogen);

[0088] 4. After heat exchange, the high-temperature gaseous methylcyclohexane is cooled from 200°C to 77°C. It is then transported to a circulating water cooler to cool to 40°C, and then separated by a gas-liquid separator to obtain liquid methylcyclohexane, which is then stored in a hydrogen-rich organic liquid storage tank.

[0089] Compared with Comparative Example 2, the heat load of its heat exchanger is significantly reduced. In Example 2, the heat load of the heat exchanger is 2578 kW, the heat load of the circulating water cooler is 462 kW, the compressor requires 157 kW of electricity, and the energy saving effect reaches 2578 kW, the hot utility is reduced by 100%, and the cold utility is reduced by 84.88%, but an additional 157 kW of electricity consumption is required. Example 2 can achieve an additional saving of 1454 kW of hot and cold utilities, increasing the savings of hot utilities from 42.79% to 100%, and the savings of cold utilities from 36.78% to 84.88%, greatly improving the comprehensive utilization rate of energy and reducing the operating cost of the device.

[0090] In summary, the method provided in the present application can efficiently recycle and utilize the waste heat generated by the organic liquid hydrogenation process, and can achieve a 100% reduction in hot utilities and an over 80% reduction in cold utilities, thereby making full use of the waste heat and enhancing the energy-saving effect.

[0091] The present application proposes a waste heat recovery method and system for an organic liquid hydrogen storage process, which increases the self-supplied ratio of energy for preheating raw materials from less than 50% to more than 80%, greatly improving the energy utilization rate of the process, and significantly reducing the supply of cold and hot utilities, thereby reducing operating costs.

[0092] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0093] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present application.

[0094] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0095] The above is a detailed introduction to the waste heat recovery method and system of an organic liquid hydrogen storage process provided by the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea; at the same time, for general technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for recovering waste heat from an organic liquid hydrogen storage process, characterized in that: The method comprises: S1, performing heat exchange treatment on the high-temperature gaseous hydrogenation product output from the reaction device and a liquid hydrogen storage carrier having a pressure lower than the pressure required for the hydrogenation reaction, so that the liquid hydrogen storage carrier is heated and vaporized to obtain a gaseous hydrogen storage carrier; S2, pressurizing the gaseous hydrogen storage carrier to make the gaseous hydrogen storage carrier reach the pressure of the hydrogenation reaction, and obtaining the gaseous hydrogen storage carrier that meets the temperature and pressure requirements of the hydrogenation reaction; S3, inputting the gaseous hydrogen storage carrier and hydrogen that meet the hydrogenation reaction temperature and pressure requirements into the reaction device for hydrogenation reaction to obtain the high-temperature gaseous hydrogenation product; Wherein, the high-temperature gaseous hydrogenation product includes: vaporized hydrogen-rich organic liquid and hydrogen.

2. The method for recovering waste heat from the organic liquid hydrogen storage process according to claim 1, characterized in that: The method further comprises: S4, after the high-temperature gaseous hydrogenation product is subjected to heat exchange treatment in S1, it is cooled and separated in sequence to obtain hydrogen-rich organic liquid and hydrogen.

3. The method for recovering waste heat from the organic liquid hydrogen storage process according to claim 2, characterized in that: In step S4, the hydrogen obtained from the separation process is reused and reused in the hydrogenation reaction.

4. A waste heat recovery system for an organic liquid hydrogen storage process, characterized in that: The system is applicable to the waste heat recovery and utilization method of the organic liquid hydrogen storage process according to any one of claims 1 to 3, and the system comprises: a carrier storage device (1), a hydrogen storage device (2), a heat exchange device (3), a pressurizing device (4) and a reaction device (5); The discharge port of the reaction device (5) is connected to the hot flow inlet of the heat exchange device (3) to provide the high-temperature gaseous hydrogenation product to the heat exchange device (3); the outlet of the carrier storage device (1) is connected to the cold flow inlet of the heat exchange device (3) to provide the liquid hydrogen storage carrier to the heat exchange device (3); in the heat exchange device (3), the liquid hydrogen storage carrier exchanges heat with the high-temperature gaseous hydrogenation product to obtain the gaseous hydrogen storage carrier; The cold logistics outlet of the heat exchange device (3) is connected to the booster device (4) for passing the gaseous hydrogen storage carrier into the booster device (4) for pressurization treatment, so that the gaseous hydrogen storage carrier reaches the pressure of the hydrogenation reaction, and the gaseous hydrogen storage carrier that meets the temperature and pressure requirements of the hydrogenation reaction is obtained, and is passed into the feed port of the reaction device (5); The hydrogen storage device (2) is connected to the feed port of the reaction device (5) and is used to provide the hydrogen to the reaction device (5); after the hydrogenation reaction is completed in the reaction device (5), the high-temperature gaseous hydrogenation product is obtained.

5. The waste heat recovery and utilization system of the organic liquid hydrogen storage process according to claim 4 is characterized in that: The hydrogenation reaction temperature of the gaseous hydrogen storage carrier is 150-350°C.

6. The waste heat recovery system of the organic liquid hydrogen storage process according to claim 5 is characterized in that: When the hydrogenation reaction temperature of the gaseous hydrogen storage carrier is 200°C; In step S1, the temperature of the liquid hydrogen storage carrier after heating and vaporization is 180°C~200°C; in step S2, the temperature of the gaseous hydrogen storage carrier after pressurization treatment is 210°C~250°C.

7. The waste heat recovery and utilization system of the organic liquid hydrogen storage process according to claim 4 is characterized in that: In step S1, the difference between the dew point temperature of the liquid hydrogen storage carrier and the dew point temperature of the pressurized high-temperature gaseous hydrogenation product is greater than the minimum heat transfer temperature difference.

8. The waste heat recovery and utilization system of the organic liquid hydrogen storage process according to claim 7 is characterized in that: In step S1, the pressure of the liquid hydrogen storage carrier whose pressure is lower than the pressure required for the hydrogenation reaction is 0.5 bar to 4 bar; In step S2, the pressure of the gaseous hydrogen storage carrier after the pressurization treatment is 4 bar to 8 bar.

9. The waste heat recovery and utilization system of the organic liquid hydrogen storage process according to claim 4 is characterized in that: The system further comprises: a cooling device (6), a separation device (7) and a hydrogen-rich organic liquid storage device (8) connected in sequence; The hot flow outlet of the reaction device (5) is connected to the inlet of the cooling device (6) for cooling the high-temperature gaseous hydrogenation product after the heat exchange is completed; the separation device (7) is used to separate the cooled product to obtain hydrogen-rich organic liquid and hydrogen; The hydrogen-rich organic liquid storage device (8) is used to store the hydrogen-rich organic liquid obtained after cooling and separation.

10. The waste heat recovery and utilization system of the organic liquid hydrogen storage process according to claim 9, characterized in that: After the heat exchange is completed, the temperature of the high-temperature gaseous hydrogenation product after cooling is 20°C to 50°C; The hydrogen separated by the separation device (7) is transported to the reaction device (5) to continue participating in the hydrogenation reaction.

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