Hydrogen energy comprehensive utilization system for preparing sebacic acid

Abstract

The invention provides a hydrogen energy comprehensive utilization system in a sebacic acid preparation process. The hydrogen energy comprehensive utilization system comprises a cooler, a switching system, a pressure stabilization control system, a buffer tank, a cracking device and a heating device which are communicated in sequence. According to the hydrogen energy comprehensive utilization system, the high calorific value of hydrogen is allowed to be utilized, so that dependence on external fuel is reduced, and the production cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical preparation, and in particular relates to a hydrogen energy comprehensive utilization system in the process of preparing sebacic acid. Background Art

[0002] Aliphatic dicarboxylic acids, especially sebacic acid, are important chemical raw materials. For example, sebacic acid is a raw material for the production of important industrial products such as nylon, plasticizers, and lubricants.

[0003] Currently, sebacic acid is typically produced through the cracking of castor oil or ricinoleic acid under alkaline conditions. This cracking reaction produces hydrogen as a byproduct, which has the advantage of high calorific value. However, safety concerns hinder its recovery and utilization. For example, the explosion limits of hydrogen in air are very wide, ranging from 4% to 75%. Therefore, hydrogen recycling and utilization poses significant safety risks. This risk is exacerbated when pipeline pressure fluctuates, as pressure fluctuations can cause air or other oxidizing gases to mix with the hydrogen flow, creating an explosion risk.

[0004] Sebacic acid is typically produced in batch or semi-batch reactors, with the hydrogen production flow rate varying widely over time.

[0005] Sebacic acid can also be produced in a continuous reactor: during startup or during changes in production capacity, the hydrogen production flow rate is varied.

[0006] Given the above, there are currently few concrete and feasible processes to recover and utilize the hydrogen produced during this reaction. Hydrogen is typically vented along with other by-products or burned, for example, in a flare that can tolerate variations in hydrogen production flow.

[0007] Therefore, it is necessary to provide a system that allows safe and reliable recovery and utilization of hydrogen generated during the preparation of sebacic acid, and the method and system can utilize the high calorific value of hydrogen, thereby reducing dependence on external fuels Summary of the Invention

[0008] In view of the above-mentioned defects or deficiencies in the prior art, the present invention provides a hydrogen energy comprehensive utilization system in the process of preparing sebacic acid in order to solve the above-mentioned problems in the prior art.

[0009] The main technical solution is: a comprehensive hydrogen energy utilization system in the process of preparing sebacic acid, including: a cooler, a switching system, a voltage stabilization control system, a buffer tank, a cracking device and a heating device;

[0010] A switching system for switching the running direction of a hydrogen-containing stream comprises a pipeline P1, a pipeline P2, a valve V1 and a valve V2, wherein the pipeline P1 is equipped with a valve V1, the pipeline P2 leads to the atmosphere or a torch for burning hydrogen and is equipped with a valve V2, and the pipeline P1 and the pipeline P2 are fluidically connected; and a cooler arranged before the switching system, the inlet of the cooler receiving a stream containing hydrogen, and the outlet of the cooler being fluidly connected to the pipeline P1 and the pipeline P2; a buffer tank connected to the pipeline P1, the buffer tank having an inlet and an outlet for receiving a stream containing hydrogen; also comprising a cracking unit connected to the inlet of the cooler, and a heating device for supplying heat to the cracking unit, the heating device having an inlet for receiving a stream containing hydrogen from the outlet of the buffer tank; and a pressure stabilization control system arranged between the cooler and the buffer tank.

[0011] Furthermore, it also includes a water seal tank. The outlet of the buffer tank 3 material flow is connected to the water seal tank 4 through the pipeline PI, and then enters the heating device 5 through the pipeline PE. The outlet of the pipeline PI entering the water seal tank 4 is located below the water seal liquid level, and the inlet of the pipeline PE leaving the water seal tank is located above the water seal liquid level.

[0012] Furthermore, the pipeline PI and the pipeline PE are provided with control valves V5 and V6 respectively.

[0013] Furthermore, the pressure stabilization control system includes a pipeline P3, a pipeline P4 and a liquid ring compressor, wherein the end of each of the pipelines P3 and P4 is respectively connected to the inlet pipe and outlet pipe of the liquid ring compressor, the pipeline P3 is equipped with a valve V3, and the pipeline P4 is equipped with a valve V4; and a pressure indicating controller PIC for controlling valves V3 and V4, the pressure indicating controller PIC is connected to the inlet pipe of the liquid ring compressor before the pipeline P3 and the pipeline P4.

[0014] Furthermore, the liquid ring compressor has an inlet for receiving a hydrogen-containing stream and an outlet fluidly connected to the inlet of the buffer tank 3 .

[0015] Furthermore, the working fluid in the liquid ring compressor is water.

[0016] Furthermore, the pressure stabilization control system includes a pressure control valve V3' arranged before the buffer tank 3 and a pressure indicating controller PIC for controlling the pressure control valve V3', wherein the pressure indicating controller PIC is located upstream of the pressure control valve V3', wherein the inlet of the cooler is used to receive a material flow containing hydrogen, and the outlet of the cooler is fluidically connected to the pressure control valve V3'.

[0017] Furthermore, the pressure control valve V3' is configured to reduce the pressure of the hydrogen-containing stream to 30 kPa to 500 kPa above atmospheric pressure.

[0018] Furthermore, the heating device is a burner matched with the cracking unit.

[0019] Furthermore, the hydrogen-containing stream is hydrogen generated during the preparation of sebacic acid.

[0020] The beneficial effects of the present invention are:

[0021] 1. The system of the present invention allows for safe and reliable recovery and utilization of hydrogen, even when the direction of flow changes or the flow rate of the reactants varies or when the reaction for preparing sebacic acid is carried out in batch mode, semi-batch mode or continuous mode;

[0022] 2. The hydrogen recovery method and system of the present invention allows the high calorific value of hydrogen to be utilized, thereby reducing dependence on external fuels and lowering production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Other features, objects and advantages of the present application will become more apparent upon reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0024] Figure 1 is a schematic diagram of an embodiment of the present invention and a related system for recovering hydrogen;

[0025] Figure 2 is a schematic diagram of another embodiment of the present invention and a related system for recovering hydrogen;

[0026] The legend of the drawings is as follows:

[0027] 100, 100', hydrogen recovery system;

[0028] 200, 200', voltage stabilization control system;

[0029] 1. Condenser;

[0030] 2. Water ring compressor;

[0031] 3. Buffer tank;

[0032] 4. Water seal tank;

[0033] 5. Molten salt furnace;

[0034] 6. Cracking unit;

[0035] PIC, pressure indicating controller;

[0036] V1, V1', V2, V2', V3, V3', V4, V5, V6, VN and VT indicate valves;

[0037] P1, P2, P1', P2', P3, P4, PI and PE represent pipes. DETAILED DESCRIPTION

[0038] The present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the relevant invention and are not intended to limit the invention. It should also be noted that, for ease of description, only portions relevant to the invention are shown in the accompanying drawings.

[0039] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0040] A hydrogen energy comprehensive utilization system in the process of preparing sebacic acid, comprising a switching system for switching the running direction of a material flow B (a material flow containing hydrogen), comprising a pipeline P1, a pipeline P2, a valve V1, and a valve V2, wherein the pipeline P1 leads to a valve equipped with the valve V1, the pipeline P2 leads to the atmosphere or a torch for burning hydrogen and is equipped with the valve V2, and the pipeline P1 and the pipeline P2 are in fluid communication;

[0041] a cooler disposed before the switching system, wherein the inlet of the cooler receives a stream containing hydrogen, and the outlet of the cooler is in fluid communication with the pipeline P1 and the pipeline P2;

[0042] a buffer tank 3 connected to the pipeline P1, the buffer tank 3 having an inlet and an outlet for receiving a stream containing hydrogen;

[0043] It also includes a cracking device 6 connected to the inlet of the cooler, and a heating device for supplying heat to the cracking device 6, wherein the heating device has an inlet for receiving a feed stream containing hydrogen from the outlet of the buffer tank 3; and a pressure stabilization control system arranged between the cooler and the buffer tank 3.

[0044] In a specific embodiment, the inlet of the cooler is used to receive a stream B containing hydrogen, and the outlet of the cooler is fluidly connected to pipeline P1 and pipeline P2. The configuration of the cooler allows the by-product 2-octanol and water contained in the stream B to be separated from the stream B through a condensation step before step c).

[0045] In a specific embodiment, the buffer tank 3 has an inlet and an outlet for receiving a stream containing hydrogen (the stream containing hydrogen is a fluid obtained after separating the target product therefrom); the heating device has an inlet for receiving a stream containing hydrogen from the outlet of the buffer tank 3, wherein the heating device is configured to burn the hydrogen and use the generated heat for heat exchange, such as heating the cracking device 6.

[0046] In a specific embodiment, the hydrogen energy comprehensive utilization system for producing sebacic acid further includes a subsystem for flushing the system's pipelines with inert gas. A water seal tank 4 is disposed between the buffer tank 3 and the heating device. The outlet of the pipeline PI entering the water seal tank 4 from the buffer tank 3 is located below the water seal liquid level, while the inlet of the pipeline PE exiting the water seal tank 4 is located above the water seal liquid level. Furthermore, the pipeline PE exiting the water seal tank 4 is in fluid communication with the heating device.

[0047] In one embodiment of the present invention, the pressure stabilization control system includes a pipeline P3 and a pipeline P4, wherein the end of each of the pipelines P3 and P4 is respectively connected to the inlet pipe and outlet pipe of the liquid ring compressor, the pipeline P3 is equipped with a valve V3, and the pipeline P4 is equipped with a valve V4; and a pressure indicating controller PIC for controlling the valves V3 and V4, and the pressure indicating controller PIC is connected to the inlet pipe of the liquid ring compressor before the pipeline P3 and the pipeline P4.

[0048] In one embodiment of the present invention, the system includes a liquid ring compressor having an inlet for receiving a stream containing hydrogen and an outlet in fluid communication with the inlet of the buffer tank 3. The liquid ring compressor is configured such that at the outlet of the compressor, the pressure of the stream containing hydrogen is increased to 30 kPa to 500 kPa above atmospheric pressure, preferably 50 kPa to 200 kPa above atmospheric pressure. The working fluid in the liquid ring compressor is water.

[0049] Another configuration of the pressure stabilizing control system is, comprising a pressure control valve V3' and a pressure indicating controller PIC for controlling the pressure control valve V3', the pressure indicating controller PIC being located upstream of the pressure control valve V3', and a switching system for switching the running direction of the material flow B at the outlet of the pressure control valve V3', comprising a pipeline P1', a pipeline P2', a valve V1' and a valve V2', wherein the pipeline P1' leads to the buffer tank 3 and is equipped with a valve V1', the pipeline P2' leads to the atmosphere or a torch for burning hydrogen and is equipped with a valve V2', and the pipelines P1' and P2' are fluidically connected; and an optional cooler, wherein the inlet of the cooler is used to receive the material flow B containing hydrogen, and the outlet of the cooler is fluidically connected to the pressure control valve V3', the configuration of the cooler allows the by-products 2-octanol and water contained in the material flow B to be separated from the material flow B through a condensation step before step c), and to be located before the pressure stabilizing control system.

[0050] The pressure control valve V3' is arranged before the buffer tank 3 to adjust the pressure of the hydrogen-containing stream before entering the buffer tank. The pressure control valve V3' is configured to reduce the pressure of the hydrogen-containing stream to 30 kPa to 500 kPa above atmospheric pressure, preferably 50 kPa to 200 kPa above atmospheric pressure.

[0051] The heating device is a burner associated with the cracking unit 6, or the heating equipment includes a furnace for heating a heat transfer fluid, wherein the heat transfer fluid heats the cracking unit, wherein the heat transfer fluid is selected from steam, molten salt, or an organic heat transfer fluid. The salt used in the molten salt includes a nitrate, such as potassium nitrate. The fuel for the heating device also includes a gaseous fuel, such as natural gas or a liquid fuel.

[0052] A specific embodiment of the present invention is as follows Figure 1 As shown, the system for hydrogen recovery includes

[0053] A switching system for switching the running direction of a material flow containing hydrogen, comprising a pipeline P1, a pipeline P2, a valve V1 and a valve V2, wherein pipeline P1 leads to a liquid ring compressor and is equipped with valve V1, pipeline P2 leads to the atmosphere or a torch for burning hydrogen and is equipped with valve V2, and pipeline P1 and pipeline P2 are fluidically connected; a pressure stabilization control system, comprising a pipeline P3 and a pipeline P4, wherein the end of each of pipelines P3 and P4 is fluidically connected to the inlet pipe and outlet pipe of the liquid ring compressor respectively, pipeline P3 is equipped with valve V3, and pipeline P4 is equipped with valve V4; and a pressure indicating controller PIC for controlling valves V3 and V4, the pressure indicating controller PIC being connected to the inlet pipe of the liquid ring compressor before pipeline P3 and pipeline P4; and an optional cooler, wherein the inlet of the cooler is used to receive a material flow containing hydrogen, and the outlet of the cooler is fluidically connected to pipeline P1 and pipeline P2.

[0054] Another specific embodiment of the present invention is as follows Figure 2 wherein the system for hydrogen recovery comprises:

[0055] A pressure stabilization control system includes a pressure control valve V3' and a pressure indicating controller PIC for controlling the pressure control valve V3', the pressure indicating controller PIC is located upstream of the pressure control valve V3', and a switching system for switching the running direction of a hydrogen-containing material flow at the outlet of the pressure control valve V3', including a pipeline P1', a pipeline P2', a valve V1' and a valve V2', wherein the pipeline P1' leads to a buffer tank and is equipped with a valve V1', the pipeline P2' leads to the atmosphere or a torch for burning hydrogen and is equipped with a valve V2', and the pipelines P1' and P2' are fluidically connected; and the outlet of the cooler is fluidically connected to the pressure control valve V3', and the configuration of the cooler allows the fluid containing hydrogen to be condensed before entering the buffer tank 3 and to be located before the pressure stabilization control system.

[0056] The system and related systems of the present invention not only achieve safe and reliable recovery and utilization of hydrogen, but also reduce the cost of producing sebacic acid. The present invention utilizes the combination and coordination of multiple hydrogen recovery and utilization steps and system components to achieve safe and reliable recovery and utilization of hydrogen, even when the hydrogen production rate varies over time. The method and system for recovering hydrogen of the present invention enable hydrogen from the cracker 6 to be burned in a burner to directly heat the cracker 6, or burned in a furnace to heat the heat transfer fluid used to heat the cracker 6, thereby at least partially replacing external fuels, such as gaseous fuels such as natural gas or liquid fuels, used in the heating device associated with the cracker 6.

[0057] The hydrogen-containing stream of the present invention is the hydrogen generated in the process of preparing sebacic acid.

[0058] Specifically, the preparation method of sebacic acid comprises the following steps:

[0059] Step a), heating one part of a reactant derived from castor oil in the presence of 1 to 3 parts of a base to produce a stream A comprising sebacate and hydrogen;

[0060] Step b), performing gas-solid separation on the material stream A to produce a gas phase material stream B containing hydrogen and a solid phase material stream C containing sebacate;

[0061] Step c), passing stream B through a buffer device and entering a heating device to burn hydrogen;

[0062] In step d), the material stream C is first treated with acid to a pH of 5 to 7, then separated by adsorption, and then acidified to a pH of 1 to 3, and purified by solid-liquid separation to obtain sebacic acid.

[0063] In particular, the method and system for recovering hydrogen of the present invention has good safety precautions against the risks associated with switching hydrogen-containing streams between different pipelines, which is achieved by the pressure stabilization control system explained below.

[0064] The method and system for recovering hydrogen of the present invention can adapt to the flow rate of hydrogen to be recovered that varies with time.

[0065] Now, combine Figure 1 and Figure 2 Specifically describe the implementation of the hydrogen energy comprehensive utilization system.

[0066] Figure 1 and Figure 2 In a non-limiting manner, a system for implementing the method of the present invention is shown, which includes a system 100 or 100' for recovering hydrogen. The implementation of the method of the present invention will be described below in conjunction with the system.

[0067] In step a), the reactants react in the presence of a base in a cracking device 6 heated by a heating device to produce a stream A comprising sebacate and hydrogen.

[0068] In a preferred embodiment, the reaction temperature of step a) may be from 180°C to 400°C, or preferably from 180°C to 250°C.

[0069] In a preferred embodiment, the reaction pressure is 0.1 kPa to 1000 kPa higher than atmospheric pressure. It has been found that when the reaction pressure is relatively low, the risk of external gases (including oxidizing gases) entering the piping of the system of the present invention may increase.

[0070] In step b), the stream A is separated to produce a stream B containing hydrogen and a stream C containing sebacate, wherein the stream B is intended to enter a hydrogen recovery system 100, which includes a buffer tank 3 and a heating device (e.g., Figure 1 Molten salt furnace 5).

[0071] In a preferred embodiment, step a) and step b) are carried out in the same reactor.

[0072] The hydrogen-containing stream B also contains the by-product 2-octanol and water and is, before step c), Figure 1 Cooler 1 in the process separates the by-products from stream B by a condensation step.

[0073] Before the condensation step or step c), the system is flushed by flushing the subsystem with an inert gas. In this embodiment, valves VN and VT are opened to flush the hydrogen recovery system 100 with an inert gas such as nitrogen until the atmosphere of the hydrogen recovery system is replaced by nitrogen, wherein the nitrogen is introduced from valve VN and discharged through valve VT.

[0074] In a first preferred embodiment ( Figure 1 ), the reaction pressure is 0.1kPa to 80kPa higher than the atmospheric pressure. The hydrogen recovery system 100 also includes a liquid ring compressor (e.g., Figure 1 Water ring compressor 2).

[0075] Under the condition that nitrogen keeps passing through, the water ring compressor 2 is started, and the pressure before and after the water ring compressor 2 is kept stable through the adjustment and control of the valves V3, V4 and the PIC pressure indicating controller in the pressure stabilization control system 200.

[0076] Under the condition that the cracking unit 6 continues to operate, the hydrogen-containing stream B is switched from the exhaust / combustion mode to the recovery and utilization mode. Specifically, the valve V2 on the pipeline P2 is closed, and the valve V1 on the pipeline P1 is opened, wherein the hydrogen recovery system 100 maintains a positive pressure (i.e., the pressure in the system is greater than the external pressure).

[0077] The hydrogen-containing stream B enters the water ring compressor 2. During this process, the pressure before and after the water ring compressor 2 is kept stable by adjusting and controlling the valves V3 and V4 and the PIC pressure indicating controller in the pressure stabilization control system 200. The water ring compressor 2 increases the pressure of the hydrogen-containing stream B to 30 kPa to 500 kPa higher than the atmospheric pressure, preferably 50 kPa to 300 kPa higher than the atmospheric pressure at the compressor outlet.

[0078] Maintaining the pressure stability of the water ring compressor 2 is very important for the safety of the system. The present invention achieves reliable safety through the pressure stabilization control system 200 and the water ring compressor 2. When switching the open and closed states of different pipelines, air or other oxidizing gases may enter the pipelines due to instantaneous pressure changes, which will bring safety risks because the explosion limit of hydrogen is very wide. The pressure stabilization control system 200 can balance the pressure before and after the water ring compressor 2, and the water ring compressor 2 can effectively reduce the risk of sparks during operation. Therefore, the combination of the pressure stabilization control system 200 and the water ring compressor 2 of the present invention effectively reduces safety risks.

[0079] In the second embodiment ( Figure 2 ), the reaction pressure is 80 kPa to 1000 kPa above atmospheric pressure. The hydrogen recovery system 100 further includes a pressure stabilization control system 200', which includes a pressure control valve V3' for controlling the pressure in the cracking unit 66 and is controlled by a PIC pressure indicating controller. The pressure downstream of the pressure control valve V3' is lower than the pressure upstream. The pressure of stream B prior to step c) is reduced by the pressure control valve V3' to 30 kPa to 500 kPa above atmospheric pressure, preferably 50 kPa to 300 kPa above atmospheric pressure.

[0080] Under the condition that the cracking unit 6 continues to operate, the hydrogen-containing stream B is switched from the exhaust / combustion mode to the recycling and utilization mode. Specifically, the valve V2' on the pipeline P2' is closed, and the valve V1' on the pipeline P1' is opened, wherein the hydrogen recovery system 100 is maintained at a positive pressure sufficient to operate the heating device for hydrogen combustion (i.e., the pressure in the system is greater than the external pressure).

[0081] When the next step c) is performed, the hydrogen-containing stream B enters the buffer tank 3. The flow rate of the hydrogen-containing stream B flowing out of the buffer tank 3 can be adjusted by valve V5 so that the flow rate and pressure are suitable for combustion in the heating device 5.

[0082] In one embodiment, the buffer tank 3 is a variable-volume gas storage tank. The pressure in the buffer tank 3 is preferably maintained constant. When the flow rate of the inlet stream B from the cracking unit 6 is higher than the flow rate injected into the heating device, the volume of the buffer tank 3 increases. When the flow rate of the inlet stream B from the cracking unit 6 is lower than the flow rate injected into the heating device, the volume of the buffer tank 3 decreases.

[0083] In one embodiment, the buffer tank 3 is a tank with a fixed volume. In this case, the pressure in the buffer tank 3 may vary. When the flow rate of the incoming stream B from the cracking device 6 is higher than the flow rate injected into the heating device, the pressure increases. When the flow rate of the incoming stream B from the cracking device 6 is lower than the flow rate injected into the heating device, the pressure decreases.

[0084] During step d), the hydrogen-containing stream B from the buffer tank 3 enters the water seal tank 4 and then enters the heating device 5. The outlet of the pipeline PI entering the water seal tank 4 is located below the water seal liquid level, while the inlet of the pipeline PE leaving the water seal tank is located above the water seal liquid level. The buffer tank 3 maintains stable pressure in the front and rear parts of the system, and the water seal tank 4 can further reduce the risk of air or oxidizing gas entering the hydrogen recovery system 100 from the outside. Therefore, the combination of the buffer tank 3 and the water seal tank 4 further improves the safety of the hydrogen recovery system 100.

[0085] The stream B containing hydrogen enters the heating device 5 and is burned. The heating device 5 is a burner associated with the cracking device 6, or the heating device comprises a furnace for heating a heat transfer fluid, which heats the cracking device 6.

[0086] In the heating device, it is also possible to use external fuels, such as gaseous fuel natural gas or liquid fuel ( Figure 1 (not shown). Therefore, the stream B containing hydrogen can replace at least a portion of the external fuel, thereby reducing costs. The heat generated by the heating device provides heat for the cracking device 6 to keep the cracking reaction running continuously.

[0087] The heat transfer fluid is selected from steam, molten salt or organic heat transfer fluid. There is no particular limit to the number of cracking units 6. For example, multiple cracking units 6 can be used to increase production, for example, from 2 cracking units 6 to 100 cracking units 6. They are usually installed in parallel.

[0088] When a plurality of cracking units 6 are combined in parallel, each unit preferably has its own step a) and step b) and its own condenser 1 .

[0089] In the case of the first embodiment, each cracking unit 6 has its own valves V1 and V2. The hydrogen-containing streams B from all cracking units 6 are preferably brought together in a single compressor.

[0090] In the case of the second embodiment, each cracking unit 6 has its own pressure valve V3' and valves V1' and V2'. The hydrogen-containing streams B from all cracking units 6 are preferably connected together before step c.

[0091] In both embodiments, even when multiple cracking units 6 are connected in parallel, there is a buffer tank 3 and a water seal tank 4. All cracking units may use a single molten salt furnace 5 to distribute heat transfer fluid to each cracking unit. Alternatively, a heating device may be installed for each cracking unit 6.

[0092] In addition, condensate can be recovered from the cooler 1, the water ring compressor 2 and the buffer tank 3. Therefore, the condenser 1, the water ring compressor 2 and the buffer tank 3 may be equipped with a pipeline for recovering condensate ( Figure 1 not shown).

[0093] When carrying out step e), the sebacic acid salt-containing stream C is treated to recover sebacic acid.

[0094] In a preferred embodiment, stream C is mixed with a mineral acid such as aqueous sulfuric acid or hydrochloric acid to form sebacic acid.

[0095] During the practice of the present invention, the system 100 for recovering hydrogen should maintain a positive pressure.

[0096] In both embodiments, the buffer tank 3 allows for coping with upstream hydrogen flow changes or upstream pressure changes, and delivers a stable hydrogen flow and pressure to the heating device for hydrogen combustion. This is key to operating the heating device. In addition, the use of the water seal tank 4 provides additional safety for pressure changes in the system. Preferably, by using the buffer tank 3 and the water seal tank 4 in the above order and / or manner, reliable circulation of hydrogen can be achieved for both embodiments. In a preferred embodiment, the water seal tank 4 is arranged between the buffer tank 3 and the heating device (such as the molten salt furnace 5), and will prevent possible backfire of the heating device and ignition of the hydrogen in the buffer tank 3. Therefore, in this preferred embodiment, enhanced safety is achieved.

[0097] With respect to the above-described embodiments and other variations, the present invention can achieve safe and reliable recovery and utilization of hydrogen and reduce the cost of producing sebacic acid.

[0098] The above embodiments do not constitute any limitation to the present invention.

[0099] The following examples further illustrate the present invention in a non-limiting manner.

[0100] according to Figure 1 The hydrogen recovery method and system of the above-mentioned embodiment are used to implement the production of sebacic acid.

[0101] Example 1

[0102] Fifteen crackers 6 are operated in parallel in a continuous mode. Each cracker 6 is heated by circulating nitric acid molten salt from a separate molten salt furnace 5. The vents of each cracker 6 are connected to 15 condensers 1. The pipelines for collecting non-condensable gases from each condenser 1 are connected to 15 valves V1 and valves V2. All valves V1 are connected to a single water ring compressor 2, which is connected to a buffer tank 3, a water seal tank 4 and a molten salt furnace 5. All valves V2 are connected to a flare.

[0103] During startup, natural gas is used as fuel in the molten salt furnace 5. All reactors are heated to 250°C. All valves V1 are closed and all valves V2 are opened. The first five cracking units 6 are started. 166 kg / h of ricinoleic acid (75% purity), 150 kg / h of aqueous sodium hydroxide solution and 40 kg / h of phenol are injected into each cracking unit 6. The temperature in each cracking reactor is maintained at 250°C. The pressure in the reactor is 8 kPa higher than atmospheric pressure. A condensed stream containing water and 2-octanol and an uncondensed stream containing hydrogen are collected from the condenser 1. The liquid output material of the cracking unit 6 is acidified with sulfuric acid to form crude sebacic acid.

[0104] During the first hour of operation, the non-condensable stream containing hydrogen was sent to the flare. After one hour of operation, the non-condensable stream containing hydrogen was sent to water ring compressor 2 through 15 valves V1 (open), and all valves V2 were closed. Then, part of the natural gas was replaced by hydrogen.

[0105] Then, 5 additional cracking units 6 are started up in the same manner. Then, the last 5 cracking units 6 are started up in the same manner.

[0106] When the 15 cracking units 6 reach a steady state, the total hydrogen flow rate produced is 140Nm 3 / h. The inlet pressure of the water ring compressor 2 is 5 kPa above atmospheric pressure, and the outlet pressure of the water ring compressor 2 is 80 kPa above atmospheric pressure. The pressure of the buffer tank 3 is 80 kPa. After pressure regulation, the hydrogen-containing stream B enters the molten salt furnace 5 and is burned at a pressure of 25 kPa above atmospheric pressure. In this case, the natural gas flow rate entering the molten salt furnace 5 is reduced by 45 Nm compared to when all cracking units 6 are in operation and all hydrogen-containing non-condensable streams are sent to the flare. 3 / h.

[0107] Example 2

[0108] The eight cracking reactors operate in semi-batch mode. Each cracking reactor is heated by circulating nitric acid molten salt from a single molten salt furnace 5. The tail gas outlet of each cracking unit 6 is connected to eight condensers 1. The pipelines collecting non-condensable gases from each condenser 1 are connected to eight valves V1 and valves V2. All valves V1 are connected to a single water ring compressor 2, which is connected to a buffer tank 3, a water seal tank 4 and a molten salt furnace 5. All valves V2 are connected to a flare or the atmosphere.

[0109] The first reactor, heated at 210°C, was charged with 130 kg of 85% sodium hydroxide. Condenser 1 was vented through valve 1 (V2), and valve 1 (V1) was closed. Then, within 2 hours and 15 minutes of the start of the addition, 130 kg of ricinoleic acid and 70 kg of 2-ethylhexanoic acid were added. Condenser 1 was vented through valve 1 (V1) (open), and valve 1 (V2) was closed. A small amount of steam was added underground at 210°C for 2 hours, while 2-octanol condensed in condenser 1. Hydrogen was sent to water ring compressor 2 and finally to molten salt furnace 5. The temperature was then raised to 320°C over 2 hours, while 2-octanol and hydrogen were released. Valve 1 (V1) was then closed, nitrogen injection into the reactor began, and valve 1 (V2) was opened. The reactor was cooled to 210°C and then vented over 2 hours. The cycle then began anew.

[0110] The other seven cracking reactors follow the same cycle that lasts for 8 hours. The start of the cycle for each of the eight reactors is organized so that a new cycle begins every hour with a different reactor.

[0111] During all operations, the compressor maintained an inlet pressure of 2 kPa and an outlet pressure of 90-100 kPa. During the cycle, the pressure in the reactor varied between 2 and 6 kPa.

[0112] In this way, hydrogen (about 90Nm 3 ) is stored in the buffer tank 3 and transported to the molten salt furnace 5 at a stable flow rate to replace part of the natural gas.

[0113] When the above examples are implemented, the method and system for recovering hydrogen of the present invention can maintain effective and safe operation for a long period of time, even when switching modes or switching the direction of flow. This fully demonstrates that the method and hydrogen recovery system of the present invention can safely and reliably recover and utilize the hydrogen generated during the reaction process. Based on the safe and reliable recovery and utilization of hydrogen, the present invention can effectively utilize the high calorific value of hydrogen, thereby significantly reducing natural gas flow and lowering the production cost of sebacic acid.

[0114] The above description is merely a preferred embodiment of the present application and an illustration of the technical principles employed. Those skilled in the art should understand that the scope of the invention herein is not limited to the technical solutions formed by the specific combination of the above-mentioned technical features, but also encompasses other technical solutions formed by any combination of the above-mentioned technical features or their equivalents without departing from the inventive concept. For example, a technical solution formed by replacing the above-mentioned features with (but not limited to) technical features having similar functions disclosed in this application.

Claims

1. A hydrogen energy comprehensive utilization system for preparing sebacic acid, characterized in that: include: A switching system for switching the direction of a hydrogen-containing stream, comprising a pipeline P1, a pipeline P2, a valve V1, and a valve V2. The pipeline P1 is equipped with a valve V1, and the pipeline P2 is connected to the atmosphere or a flare for burning hydrogen and is equipped with a valve V2. The pipelines P1 and P2 are in fluid communication. A cooler is provided before the switching system. The inlet of the cooler receives the hydrogen-containing stream, and the outlet of the cooler is in fluid communication with the pipelines P1 and P2. a buffer tank connected to the pipeline P1, the buffer tank having an inlet and an outlet for receiving a stream comprising hydrogen; Also included is a cracking device connected to the inlet of the cooler, and a heating device for supplying heat to the cracking device, the heating device having an inlet for receiving a stream containing hydrogen from the outlet of the buffer tank; and A pressure stabilizing control system is provided between the cooler and the buffer tank.

2. The hydrogen energy comprehensive utilization system for preparing sebacic acid according to claim 1, characterized in that: It also includes a water seal tank; the outlet of the buffer tank material flow is connected to the water seal tank through the pipeline PI, and then enters the heating device through the pipeline PE. The outlet of the pipeline PI entering the water seal tank is located below the water seal liquid level, and the inlet of the pipeline PE leaving the water seal tank is located above the water seal liquid level.

3. The hydrogen energy comprehensive utilization system for preparing sebacic acid according to claim 2, characterized in that: The pipeline PI and the pipeline PE are respectively provided with control valves V5 and V6.

4. A hydrogen energy comprehensive utilization system for preparing sebacic acid according to any one of claims 1 to 3, characterized in that: The pressure stabilization control system includes a pipeline P3, a pipeline P4 and a liquid ring compressor, wherein the ends of each of the pipelines P3 and P4 are respectively connected to the inlet pipe and the outlet pipe of the liquid ring compressor, the pipeline P3 is equipped with a valve V3, and the pipeline P4 is equipped with a valve V4; and a pressure indicating controller PIC for controlling the valves V3 and V4, the pressure indicating controller being connected to the inlet pipe of the liquid ring compressor before the pipelines P3 and P4.

5. The hydrogen energy comprehensive utilization system for preparing sebacic acid according to claim 4, characterized in that: The liquid ring compressor has an inlet for receiving a hydrogen-containing stream and an outlet in fluid communication with the inlet of the buffer tank.

6. The hydrogen energy comprehensive utilization system for preparing sebacic acid according to claim 5, characterized in that: The working fluid in the liquid ring compressor is water.

7. A hydrogen energy comprehensive utilization system for preparing sebacic acid according to any one of claims 1 to 3, characterized in that: The pressure stabilization control system includes a pressure control valve V3' arranged before the buffer tank and a pressure indicating controller PIC that controls the pressure control valve V3', wherein the pressure indicating controller PIC is located upstream of the pressure control valve V3', wherein the inlet of the cooler is used to receive a material flow containing hydrogen, and the outlet of the cooler is fluidically connected to the pressure control valve V3'.

8. The hydrogen energy comprehensive utilization system for preparing sebacic acid according to claim 7, characterized in that: The pressure control valve V3' is arranged to reduce the pressure of the stream comprising hydrogen to 30 kPa to 500 kPa above atmospheric pressure.

9. The hydrogen energy comprehensive utilization system for preparing sebacic acid according to claim 1, characterized in that: The heating device is a burner matched with the cracking device.

10. The hydrogen energy comprehensive utilization system for preparing sebacic acid according to claim 1, characterized in that: The hydrogen-containing stream is hydrogen generated during the preparation of sebacic acid.

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