A molten salt pyrolysis recycling system and method for waste hydrogen storage cylinders

Abstract

The present application relates to the technical field of molten salt pyrolysis, and particularly relates to a molten salt pyrolysis recycling system and method for waste hydrogen storage cylinders. The system comprises: a first reaction tank provided with a first target molten salt; a rotating device for driving the waste hydrogen storage cylinder to rotate along its axis, wherein the axis of the waste hydrogen storage cylinder is horizontally arranged above the liquid level of the first target molten salt, the outer layer of the waste hydrogen storage cylinder is carbon fiber composite material, the inner layer is a plastic liner or a metal liner, the inner layer of the waste hydrogen storage cylinder is provided with a microwave medium ball, and the outer layer of the waste hydrogen storage cylinder at the lowermost position is immersed in the first target molten salt, so as to utilize the first target molten salt and the microwave medium ball to pyrolyze the outer layer of the waste hydrogen storage cylinder, thereby removing the resin in the carbon fiber composite material; and a filament collecting device for collecting long filament fibers generated by the waste hydrogen storage cylinder. The above scheme can realize molten salt pyrolysis recycling of the waste hydrogen storage cylinder.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of molten salt pyrolysis, in particular to a molten salt pyrolysis recycling system and method for waste hydrogen storage cylinders. BACKGROUND

[0002] Hydrogen energy, as an important clean energy carrier, plays an important role in addressing climate change. The booming development of hydrogen energy also puts higher requirements on hydrogen energy storage, accompanied by new demands for recycling of hydrogen storage devices. Pressure cylinder storage, as the most mature hydrogen storage technology today, has significant advantages in hydrogen energy storage and transportation.

[0003] Currently, the mature hydrogen storage cylinders on the market are type III and type IV cylinders, which use steel, aluminum or plastic as the inner liner, and the outer layer is wrapped with carbon fiber composite material, which can increase the working pressure of the cylinder and reduce its mass, thereby having higher hydrogen storage density.

[0004] However, the component separation technology of waste hydrogen storage cylinders is not mature, and there is a problem of low separation efficiency. Based on this, there is an urgent need for a molten salt pyrolysis recycling system and method for waste hydrogen storage cylinders to solve the above technical problems. SUMMARY

[0005] The embodiments of the present application provide a molten salt pyrolysis recycling system and method for waste hydrogen storage cylinders, which can realize molten salt pyrolysis recycling of waste hydrogen storage cylinders.

[0006] In a first aspect, the embodiments of the present application provide a molten salt pyrolysis recycling system for waste hydrogen storage cylinders, comprising:

[0007] A first reaction tank is provided with a first target molten salt;

[0008] A rotating device is used to drive the waste hydrogen storage cylinder to rotate along its axis, the axis of the waste hydrogen storage cylinder is horizontally arranged above the liquid level of the first target molten salt, the outer layer of the waste hydrogen storage cylinder is carbon fiber composite material, the inner layer is plastic liner or metal liner, the inner layer of the waste hydrogen storage cylinder is provided with a microwave medium ball, and the outer layer of the waste hydrogen storage cylinder at the lowermost position is immersed in the first target molten salt, so as to utilize the first target molten salt and the microwave medium ball to pyrolyze the outer layer of the waste hydrogen storage cylinder, thereby removing the resin in the carbon fiber composite material;

[0009] A silk collecting device is used to collect long filament fibers generated by the waste hydrogen storage cylinder.

[0010] In a second aspect, the embodiments of the present application provide a molten salt pyrolysis recycling method for waste hydrogen storage cylinders, comprising:

[0011] A microwave medium ball is loaded into a waste hydrogen storage cylinder; wherein the outer layer of the waste hydrogen storage cylinder is a carbon fiber composite material, and the inner layer is a plastic liner or a metal liner;

[0012] The waste hydrogen storage cylinder loaded with the microwave medium ball is horizontally arranged above the liquid level of the first target molten salt; wherein the outer layer of the waste hydrogen storage cylinder at the lowermost position is immersed in the first target molten salt;

[0013] The waste hydrogen storage cylinder is rotated, and the outer layer of the waste hydrogen storage cylinder is pyrolyzed by the first target molten salt and the microwave medium ball to remove the resin in the carbon fiber composite material;

[0014] Long filament fibers generated by the waste hydrogen storage cylinder are collected by a filament collecting device located above the waste hydrogen storage cylinder.

[0015] The embodiment of the present application provides a waste hydrogen storage cylinder molten salt pyrolysis recycling system and method, which introduces a molten salt method, promotes the removal of resin binders in the outer layer of the carbon fiber composite material in the molten salt system by the catalytic action of the molten salt system, and separates long filament fibers. The introduction of microwave technology makes the heating of the inner and outer layers of the cylinder more uniform, improves the heat transfer process, and makes the plastic liner of the inner layer difficult to produce residual carbon adhesion to the fiber material due to local uneven heating during the thermal decomposition process. The steel and aluminum material of the inner layer is an inert substance in the molten salt system and will not chemically react, thereby effectively retaining the structural integrity. Therefore, the above technical solution can realize the molten salt pyrolysis recycling of the waste hydrogen storage cylinder. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0017] Figure 1 is a structural schematic diagram of the waste hydrogen storage cylinder molten salt pyrolysis recycling system provided by the embodiment of the present application;

[0018] Figure 2 is a position schematic diagram of the waste hydrogen storage cylinder, the first reaction tank, the rotating device and the filament collecting device provided by the embodiment of the present application;

[0019] Figure 3 is a flow schematic diagram of the waste hydrogen storage cylinder molten salt pyrolysis recycling method provided by the embodiment of the present application.

[0020] REFERENCE SIGNS:

[0021] 10 - waste hydrogen storage cylinder; 1 - first reaction tank; 2 - rotating device; 3 - filament collecting device; 4 - second reaction tank; 5 - drying device; 6 - condensing device; 7 - combustion device; 8 - washing device. DETAILED DESCRIPTION

[0022] To make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0023] As shown in Figure 1 and Figure 2 , the embodiments of the present application provide a waste hydrogen storage cylinder molten salt pyrolysis recycling system, comprising a first reaction tank 1, a rotating device 2 and a filament collecting device 3, wherein:

[0024] The first reaction tank 1 is provided with a first target molten salt;

[0025] The rotating device 2 is used to drive the waste hydrogen storage cylinder 10 to rotate along its axis, the axis of the waste hydrogen storage cylinder 10 is horizontally arranged above the liquid surface of the first target molten salt, the outer layer of the waste hydrogen storage cylinder 10 is a carbon fiber composite material, the inner layer is a plastic liner or a metal liner, the inner layer of the waste hydrogen storage cylinder 10 is provided with a microwave medium ball, and the outer layer of the waste hydrogen storage cylinder 10 at the lowermost position is immersed in the first target molten salt, so as to utilize the first target molten salt and the microwave medium ball to pyrolyze the outer layer of the waste hydrogen storage cylinder 10, thereby removing the resin in the carbon fiber composite material;

[0026] The filament collecting device 3 is used to collect the long filament fibers generated by the waste hydrogen storage cylinder 10.

[0027] In the embodiments, the molten salt method is introduced, the catalytic action of the molten salt system is utilized in the molten salt system to promote the removal of the resin binder in the outer layer carbon fiber composite material, and the long filament fibers are separated. The microwave technology is introduced to make the heating of the inner and outer layers of the cylinder more uniform, improve the heat transfer process, and make the plastic liner in the inner layer not easy to produce residual carbon adhesion to the fiber material due to local uneven heating in the thermal decomposition process. The steel and aluminum materials in the inner layer are inert substances in the molten salt system and will not chemically react, so as to effectively retain the structural integrity. Therefore, the above technical solutions can realize the molten salt pyrolysis recycling of the waste hydrogen storage cylinder.

[0028] It should be noted that the outer shell carbon fiber can absorb microwaves, so microwaves are introduced into the first reaction tank 1 for strengthening the thermal decomposition of the outer shell; the purpose of the microwaves is to strengthen the thermal decomposition of the plastic inner shell, optimize the reaction process, and make the plastic decomposition products more homogeneous, so as not to be too low in quality. In order to facilitate, a ball cage is sleeved outside the microwave medium ball, the size of the ball cage is similar to the bottle mouth, and the ball cage is easily popped in the inside and not easily popped out.

[0029] In some embodiments, the material of the microwave medium ball is a ferrite microwave absorbing material, such as lithium-cadmium ferrite, lithium-zinc ferrite, nickel-cadmium ferrite, and ceramic ferrite. The density of the ball cage + microwave medium ball as a whole is controlled at 2 g / cm 3 , and the power of the microwave radiation is set to 2000-2500 MHz.

[0030] In an embodiment of the present application, the first target molten salt includes nitrate, carbonate (such as K2CO3-Na2CO3-Li2CO3), and basic molten salt (such as NaOH-KOH), and the heating temperature of the first target molten salt is 400-500℃.

[0031] In this embodiment, the resin can be removed by the strong oxidation of the nitrate.

[0032] In some embodiments, the nitrate can include NaNO2-NaNO3-KNO3, NaNO2-NaNO3, which is not specifically limited here.

[0033] In an embodiment of the present application, the above system further includes a second reaction tank 4, and the second reaction tank 4 is provided with a second target molten salt, which is used to mix with the plastic inner shell when the inner layer of the waste hydrogen storage cylinder 10 is a plastic inner shell, so as to pyrolyze the plastic inner shell by using the second target molten salt.

[0034] In this embodiment, considering that the plastic inner shell can also undergo a strong thermal decomposition process in the molten salt system, thereby precipitating liquid and gas components. Therefore, by screening a suitable molten salt system, the plastic thermal decomposition can generate a hydrocarbon-rich oil, which has the potential to recycle and reuse the plastic, and the gas produced can be used to heat the drying device by a combustion device.

[0035] In an embodiment of the present application, the second target molten salt includes chloride (such as KCl-ZnCl2), carbonate (such as K2CO3-Na2CO3-Li2CO3), and basic molten salt (such as NaOH-KOH, NaOH-Na2CO3), and the heating temperature of the second target molten salt is 450-550℃.

[0036] In the embodiment, the plastic is converted into a hydrocarbon-rich oil by the second target molten salt with good catalytic and deoxidation performance, so as to regenerate the hydrocarbon-rich oil which can be used as a raw material for the plastic by further synthesis. After fractional condensation, the content of the chain hydrocarbon component in the hydrocarbon-rich oil is more than 90%, and the hydrocarbon-rich oil can be used as a raw material to process the plastic liner again.

[0037] In one embodiment of the present application, the second target molten salt includes a preset percentage of water vapor in the pyrolysis atmosphere when pyrolysis is performed, and the preset percentage is 3-7%.

[0038] In the embodiment, the second target molten salt is supplied with the preset percentage of water vapor, so that more H free radicals can be generated to inhibit the cyclization of the chain hydrocarbon product generated by the pyrolysis of the plastic to form an aromatic component. In addition, the pyrolysis temperature is controlled to be below 600°C, so that the gasification reaction can also be controlled.

[0039] It should be noted that the related art may have a scheme of supplying water vapor into the molten salt, but its role is gasification, and the temperature is all higher than 600°C, mainly to provide OH free radicals to generate the reaction of C+·OH→C(O)+H·, so as to gasify the coke to generate gas. However, in the system of the second target molten salt of the present application, the yield of coke is <5% when the plastic reacts with the molten salt, and the yield of coke is very low, so the above reaction will not occur.

[0040] In one embodiment of the present application, the above system further includes a drying device 5, a condensing device 6, a combustion device 7, and a washing device 8. The drying device 5 is used to dry and dehydrate the volatile matter generated by the pyrolysis of the second target molten salt, the condensing device 6 is used to separate the hydrocarbon-rich component by fractional condensation of the dried and dehydrated product, the combustion device 7 is used to burn the non-condensable gas and supply the heat generated by the combustion to the drying device 5, and the washing device 8 is used to wash the collected fibers with an organic solvent to obtain clean fibers.

[0041] In the embodiment, the non-condensable gas includes combustible gases such as CH4, CO, H2, and the heat value is 15-20 MJ / m 3 .

[0042] It should be noted that the above each entity device does not show the specific structure in the embodiment of the present application, but those skilled in the art can understand that the structure with the function of each entity device is within the protection scope of the present application, and the specific structure of each entity device will not be described here.

[0043] In addition, as Figure 3 indicated, the embodiment of the present application also provides a molten salt pyrolysis recycling method for waste hydrogen storage cylinders, which includes:

[0044] Step S1, loading the microwave medium balls into the waste hydrogen storage cylinder; wherein, the outer layer of the waste hydrogen storage cylinder is carbon fiber composite material, and the inner layer is plastic liner or metal liner;

[0045] Step S2, horizontally arranging the waste hydrogen storage cylinder loaded with the microwave medium balls above the liquid surface of the first target molten salt; wherein, the outer layer at the lowermost of the waste hydrogen storage cylinder is immersed in the first target molten salt;

[0046] Step S3, rotating the waste hydrogen storage cylinder, and pyrolyzing the outer layer of the waste hydrogen storage cylinder by the first target molten salt and the microwave medium balls, so as to remove the resin in the carbon fiber composite material;

[0047] Step S4, collecting the filament fibers generated by the waste hydrogen storage cylinder by the filament collecting device located above the waste hydrogen storage cylinder.

[0048] In an embodiment of the present application, the first target molten salt includes nitrate, carbonate and alkaline molten salt, and the heating temperature of the first target molten salt is 400-500℃.

[0049] In an embodiment of the present application, when the inner layer of the waste hydrogen storage cylinder is plastic liner, further comprising:

[0050] immersing the plastic liner in the second target molten salt to pyrolyze the plastic liner by the second target molten salt; wherein, the second target molten salt includes chloride, carbonate and alkaline molten salt, and the heating temperature of the second target molten salt is 450-550℃.

[0051] In an embodiment of the present application, when pyrolyzing the plastic liner by the second target molten salt, a preset percentage of water vapor is introduced into the second target molten salt; wherein, the preset percentage is 3-7%.

[0052] In an embodiment of the present application, further comprising:

[0053] washing the collected fibers by the organic solvent to obtain clean fibers.

[0054] In an embodiment of the present application, after pyrolyzing the plastic liner by the second target molten salt, further comprising:

[0055] drying and dehydrating the volatile components generated by the pyrolysis of the second target molten salt;

[0056] fractionally condensing the product after drying and dehydration to separate out the hydrocarbon-rich components, and introducing the non-condensable gas into the combustion device for combustion; wherein, the heat generated by the combustion of the combustion device is used for drying and dehydration.

[0057] It can be understood that the method embodiments and the system embodiments provided by the present application are based on the same inventive concept, and have the same beneficial effects. Therefore, the beneficial effects of the method embodiments will not be described here.

[0058] It should be noted that the relational terms herein such as first and second, and the like, are used only to differentiate one entity or operation from another, and do not necessarily require or imply any actual such relationship or order between or among the entities or operations. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "comprises... a" does not, without more constraints, foreclose the existence of additional identical elements in the process, method, article, or apparatus that comprises the recited element.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A molten salt pyrolysis recycling system for spent hydrogen storage cylinders, comprising: The system comprises: a first reaction tank provided with a first target molten salt; a rotating device for rotating the waste hydrogen storage cylinder along its axis, the axis of the waste hydrogen storage cylinder being horizontally arranged above the liquid level of the first target molten salt, the outer layer of the waste hydrogen storage cylinder being carbon fiber composite material, the inner layer being plastic liner, the inner layer of the waste hydrogen storage cylinder being provided with microwave medium balls, the outer layer of the waste hydrogen storage cylinder being immersed in the first target molten salt at the lowermost position, so as to pyrolyze the outer layer of the waste hydrogen storage cylinder by the first target molten salt and the microwave medium balls, thereby removing the resin in the carbon fiber composite material; a filament collecting device for collecting the filament fibers generated by the waste hydrogen storage cylinder; The system further comprises a second reaction tank provided with a second target molten salt, the second target molten salt being used to mix with the plastic liner, so as to pyrolyze the plastic liner by the second target molten salt, thereby converting the plastic into chain hydrocarbon oil, regenerating the chain hydrocarbon oil, and further synthesizing the chain hydrocarbon oil to generate plastic raw materials; The second target molten salt comprises chloride salt, carbonate salt and basic molten salt, and the heating temperature of the second target molten salt is 450-550℃; When the second target molten salt is pyrolyzed, a preset percentage of water vapor is included in the pyrolysis atmosphere to generate H free radicals, thereby inhibiting the cyclization of chain hydrocarbon products generated by the pyrolysis of the plastic to form aromatic components, and the preset percentage is 3-7%.

2. The system of claim 1, wherein, The first target molten salt comprises nitrate salt, carbonate salt and basic molten salt, and the heating temperature of the first target molten salt is 400-500℃.

3. The system of claim 1, wherein, The system further comprises a drying device for drying and dehydrating the volatile matter generated by the pyrolysis of the second target molten salt, a condensing device for separating the hydrocarbon-rich components by fractional condensation of the products after drying and dehydration, a combustion device for burning the non-condensable gas and supplying the heat generated by the combustion to the drying device, and a washing device for washing the collected fibers with an organic solvent to obtain clean fibers.

4. A method for recycling of spent hydrogen storage cylinders by molten salt pyrolysis, characterized in that, The system based on any one of claims 1-3, comprising: loading the waste hydrogen storage cylinder with microwave medium balls; wherein the outer layer of the waste hydrogen storage cylinder is carbon fiber composite material, and the inner layer is plastic liner; arranging the waste hydrogen storage cylinder loaded with microwave medium balls horizontally above the liquid level of the first target molten salt; wherein the outer layer of the waste hydrogen storage cylinder at the lowermost position is immersed in the first target molten salt; rotating the waste hydrogen storage cylinder, and pyrolyzing the outer layer of the waste hydrogen storage cylinder by the first target molten salt and the microwave medium balls to remove the resin in the carbon fiber composite material; collecting the filament fibers generated by the waste hydrogen storage cylinder by the filament collecting device located above the waste hydrogen storage cylinder; The plastic liner is immersed in a second target molten salt to pyrolyze the plastic liner by the second target molten salt to convert the plastic into a rich hydrocarbon oil, regenerate the rich hydrocarbon oil, and further synthesize the rich hydrocarbon oil to generate a plastic raw material; wherein the second target molten salt comprises a chloride salt, a carbonate salt, and an alkaline molten salt, and the heating temperature of the second target molten salt is 450-550°C. When the plastic liner is pyrolyzed by the second target molten salt, a preset percentage of water vapor is introduced into the second target molten salt to generate H free radicals and inhibit the cyclization of the chain hydrocarbon product generated by the pyrolysis of the plastic to generate aromatic components; wherein the preset percentage is 3-7%.

5. The method of claim 4, wherein, The first target molten salt comprises a nitrate salt, a carbonate salt, and an alkaline molten salt, and the heating temperature of the first target molten salt is 400-500°C.

6. The method of claim 4, wherein, Further comprising: washing the collected fibers with an organic solvent to obtain clean fibers; and / or, After the plastic liner is pyrolyzed by the second target molten salt, further comprising: drying and dehydrating the volatile components generated by the pyrolysis of the second target molten salt; fractionally condensing the dried and dehydrated product to separate out the rich hydrocarbon components, and introducing the non-condensable gas into a combustion device for combustion; wherein the heat generated by the combustion of the combustion device is used for drying and dehydration.

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