A low-carbon, low-energy-consumption drying oven system and method for a painting workshop

Abstract

A low-carbon, low-energy-consumption drying oven system and method for a painting workshop belongs to the field of automotive manufacturing technology. It solves the problems of high carbon emissions and low heat recovery efficiency. Key technical points: Based on CL-DRM technology, CO2 waste gas generated in the combustion furnace is used as raw material in the CH4 reforming process, converting the original CO2 emissions into high-value-added CO products, which can then be used as fuel or raw materials for other chemicals. This invention recovers a large amount of heat energy generated by the regenerative thermal oxidizer to maintain the energy required for the CL-DRM reaction. Furthermore, an additional heat recovery step is added to the zeolite rotor at the front end of the regenerative thermal oxidizer to reduce input energy consumption and improve system energy utilization efficiency. Photovoltaic electrolysis of water is used to produce hydrogen to provide auxiliary fuel (H2) and oxidant (O2) for the combustion process. While utilizing clean energy to improve energy utilization efficiency, it also facilitates the capture of high-purity CO2 exhaust gas for further conversion and utilization.

Description

Technical Field

[0001] This invention relates to the field of automobile manufacturing technology, specifically to a low-carbon, low-energy-consumption drying oven system and method for a painting workshop. Background Technology

[0002] The automotive painting workshop is a crucial part of the automobile manufacturing production line, primarily responsible for applying protective or decorative layers to the metallic or non-metallic surfaces of automobiles. The entire painting production line mainly consists of pretreatment equipment, powder coating systems, painting equipment, drying ovens, heat source systems, electrical control systems, exhaust gas treatment systems, and overhead conveyor chains. Among these, the drying oven is one of the most critical pieces of equipment, as the uniformity of its internal temperature largely determines the final quality of the coating. The heat source system primarily uses methane as fuel (a few use hydrogen, but this is more expensive), and the heat released in the combustion furnace provides energy to the drying oven through direct or indirect heating. The exhaust gas treatment system mostly employs regenerative thermal oxidizers (RTOs), whose main function is to post-treat the volatile organic compounds (VOCs) generated during the coating drying process. For ease of description, the three subsystems—drying oven, heat source system, and exhaust gas treatment system—will be collectively referred to as the drying oven system.

[0003] With the development of industrial technology, current coating processes have gradually moved towards automation. However, some key issues remain unresolved in the design and application of drying oven systems. Two key issues are highlighted here: First, high carbon emissions. For methane combustion furnaces, most processes currently use air-assisted combustion, resulting in a mixture of CO2 and N2 as combustion products. This makes CO2 difficult to capture and recover, ultimately leading to its emission into the atmosphere and incurring carbon emission costs for enterprises. Second, low heat recovery efficiency. In waste gas treatment systems, the combustion temperature inside the RTO typically reaches over 800℃. However, current mainstream heat recovery methods only utilize a portion of this heat for VOCs concentration in the zeolite rotor at the RTO's front end, saving on combustion air volume. Even for some processes that have achieved industrialization, the heat generated by combustion within the RTO is entirely dissipated through natural convection without any corresponding heat recovery steps.

[0004] Therefore, there is an urgent need to propose a low-carbon and low-energy-consumption drying oven system and method for painting workshops to solve the problems of high carbon emissions and low heat recovery efficiency in existing technologies. Summary of the Invention

[0005] In view of the above facts, in order to solve the problems of high carbon emissions and low heat recovery efficiency in the prior art, the present invention designs a low-carbon and low-energy-consumption drying oven system and method for coating workshops.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] Option 1: A low-carbon and low-energy-consumption coating workshop drying oven system, including a mixing tank, a drying oven, a zeolite rotor, a regenerative thermal ignition furnace, a chimney, a combustion furnace, a CL-DRM reactor, a raw material tank, a photovoltaic water electrolysis device, and a mixed fuel tank;

[0008] The mixing tank, drying furnace, zeolite rotor, regenerative incinerator, and chimney are connected in sequence;

[0009] The exhaust port of the drying oven is connected to the mixing tank through a return air duct, and fresh air is introduced into the mixing tank.

[0010] The raw material tank is connected to the CL-DRM reactor, the exhaust port of the CL-DRM reactor is connected to the mixed fuel tank, and the exhaust port of the photovoltaic water electrolysis device is connected to the mixed fuel tank.

[0011] The mixed fuel tank is connected to the combustion furnace, and the exhaust port of the combustion furnace is connected to the CL-DRM reactor.

[0012] The combustion furnace is connected to the mixing tank via a heat exchanger;

[0013] The regenerative thermal incinerator and the zeolite rotor are connected via a first heat recovery pipe;

[0014] The regenerative incinerator and the CL-DRM reactor are connected via a second heat recovery pipeline.

[0015] Option 2: A method for implementing a low-carbon, low-energy-consumption drying oven in a painting workshop, the specific steps of which are as follows:

[0016] Step 1: CH4 feed gas is cracked to produce syngas under the action of catalyst inside the CL-DRM reactor. At the same time, the regenerative thermal oxidizer maintains the temperature required for the CL-DRM reactor reaction through heat recovery.

[0017] Step 2: The syngas produced in Step 1 is mixed with the gas produced by the photovoltaic water electrolysis device in a mixing fuel tank and then transported to the combustion furnace for combustion and heat release.

[0018] Step 3: Fresh air and return air from the drying furnace form a mixture. The combustion furnace indirectly heats the mixture to the set temperature and then sends it to the drying furnace for drying. When the VOCs generated during the process reach a certain concentration, the exhaust gas is discharged. The exhaust gas enters the zeolite rotor for further concentration.

[0019] Step 4: The mixed gas carrying high concentrations of VOCs is transported to a regenerative thermal oxidizer for combustion, generating a high temperature of 800-1100℃. A small portion of the heat is recovered through the first heat recovery pipe and provides energy to the zeolite rotor through a heat exchanger. Most of the heat is recovered through the second heat recovery pipe to maintain the temperature conditions required for the reaction in the CL-DRM reactor.

[0020] Step 5: Since the mixed fuel formed in Step 2 directly uses oxygen as the oxidant, the H2O and CO2 produced during the combustion process are high-purity exhaust gases. After drying, this exhaust gas can be used to obtain high-purity CO2, which is then transported to the CL-DRM reactor for catalyst regeneration reaction to obtain high-purity CO, which is then recycled.

[0021] Furthermore, the catalyst inside the CL-DRM reactor is an iron-based, nickel-based, or cerium-based metal oxide, and the CH4 feed gas is cracked into a syngas product containing CO and H2 in a 1:1 ratio.

[0022] Furthermore, the photovoltaic water electrolysis device generates H2 and O2.

[0023] The beneficial effects of this invention are as follows:

[0024] 1. This invention introduces CL-DRM technology into the traditional direct combustion process of methane, collecting the CO2 tail gas that would otherwise be directly emitted into the atmosphere and converting it into high-purity CO product. This saves enterprises carbon emission costs, and the energy released by the H2 and CO produced after CH4 reforming is almost the same as that of CH4 in terms of combustion (1 mol CH4 has a calorific value of 39.82 MJ / m³). 3 The total calorific value of 2 mol H2 + 1 mol CO is 38.12 MJ / m³. 3 Therefore, it has virtually no impact on the economic cost of combustion.

[0025] 2. The process route of this invention, which mainly uses heat recovery energy for the CL-DRM process, is feasible in terms of reaction principle and reaction conditions, improves heat recovery efficiency, and saves system energy consumption costs.

[0026] 3. This invention uses photovoltaic water electrolysis to produce hydrogen, providing fuel (H2) and oxidant (O2) for the combustion process. This allows for the capture of high-purity CO2 tail gas while improving energy utilization efficiency using clean energy, facilitating further conversion and utilization. Attached Figure Description

[0027] Figure 1 This is a system structure diagram of the present invention;

[0028] Figure 2 This is a process flow diagram of the present invention.

[0029] In the diagram: 2-mixed gas tank, 3-drying furnace, 4-zeolite rotor, 5-regenerative incinerator, 6-chimney, 7-combustion furnace, 8-CL-DRM reactor, 9-raw material tank, 10-photovoltaic water electrolysis device, 11-mixed fuel tank. Detailed Implementation

[0030] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0031] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0032] In this application, the terms "upper," "lower," "inner," "middle," "outer," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0033] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0034] Furthermore, the terms "set up," "connect," and "fix" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0035] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0036] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0037] Example 1: A low-carbon and low-energy-consumption drying oven system for a painting workshop in this example includes a mixed gas tank 2, a drying oven 3, a zeolite rotor 4, a regenerative thermal ignition furnace 5, a chimney 6, a combustion furnace 7, a CL-DRM reactor 8, a raw material tank 9, a photovoltaic water electrolysis device 10, and a mixed fuel tank 11.

[0038] The mixing tank 2, drying furnace 3, zeolite rotor 4, regenerative incinerator 5, and chimney 6 are connected in sequence.

[0039] The exhaust port of the drying oven 3 is connected to the mixing tank 2 through a return air pipe, and fresh air is introduced into the mixing tank 2.

[0040] The raw material tank 9 is connected to the CL-DRM reactor 8, the exhaust port of the CL-DRM reactor 8 is connected to the mixed fuel tank 11, and the exhaust port of the photovoltaic water electrolysis device 10 is connected to the mixed fuel tank 11.

[0041] The mixed fuel tank 11 is connected to the combustion furnace 7, and the exhaust port of the combustion furnace 7 is connected to the CL-DRM reactor 8;

[0042] The combustion furnace 7 is connected to the mixing tank 2 via a heat exchanger;

[0043] The regenerative incinerator 5 and the zeolite rotor 4 are connected by a first heat recovery pipe.

[0044] The regenerative incinerator 5 and the CL-DRM reactor 8 are connected by a second heat recovery pipeline.

[0045] Example 2: A method for implementing a low-carbon, low-energy-consumption drying oven in a coating workshop according to this example, the specific steps are as follows:

[0046] Step 1: CH4 feed gas is cracked to produce syngas under the action of catalyst inside CL-DRM reactor 8. The regenerative thermal oxidizer 5 maintains the temperature of CL-DRM reactor 8 above 800 degrees through heat recovery, providing the temperature conditions for CH4 chemical looping dry reforming reaction.

[0047] Step 2: The syngas produced in Step 1 is mixed with the gas produced by the photovoltaic water electrolysis device 10 in the mixed fuel tank 11 and then transported to the combustion furnace 7 for combustion and heat release to heat the mixed gas transported to the drying furnace 3.

[0048] Step 3: Fresh air and return air from drying furnace 3 form a mixture. After the mixture is indirectly heated to the set temperature by combustion furnace 7, it is sent to drying furnace 3 to dry the automotive coating by thermal convection. When the VOCs generated during the process reach a certain concentration, exhaust gas is discharged. After the exhaust gas enters zeolite rotor 4 for concentration, the concentration of VOCs will be further increased.

[0049] Step 4: The mixed gas carrying high concentrations of VOCs is transported to the regenerative incinerator 5 for combustion, generating a high temperature of 800-1100℃. A small portion of the heat is recovered through the first heat recovery pipe and provides energy to the zeolite rotor 4 in the form of a heat exchanger. Most of the heat is recovered through the second heat recovery pipe to maintain the temperature conditions required for the reaction in the CL-DRM reactor 8.

[0050] Step 5: Since the mixed fuel formed in Step 2 directly uses oxygen as the oxidant, the H2O and CO2 produced during the combustion process are high-purity exhaust gases. After drying, this exhaust gas can be used to obtain high-purity CO2, which is then transported to the CL-DRM reactor 8 for catalyst regeneration reaction to obtain high-purity CO, which is then recycled.

[0051] More specifically: the catalyst inside the CL-DRM reactor 8 is an iron-based, nickel-based, or cerium-based metal oxide, and the CH4 feed gas is cracked into a syngas product containing CO and H2 in a 1:1 ratio.

[0052] More specifically: the photovoltaic water electrolysis device 10 generates H2 and O2.

[0053] More specifically: the CL-DRM reaction equation can be expressed as:

[0054] Step 1, reduction reaction (partial oxidation of methane):

[0055] (one)

[0056] The second step is the oxidation reaction (catalyst regeneration reaction):

[0057] (two)

[0058] The overall reaction of the entire process is expressed as:

[0059] (three)

[0060] in, This represents the stoichiometric coefficients of CH4 and CO2 during the reaction, where x is a positive number and greater than 1. .

[0061] More specifically: the residual H2 produced by the photovoltaic water electrolysis device 10 can be stored or sold.

[0062] More specifically: the CO product generated in step five is a high-value-added carbon recovery product, which can generate profits through storage, combustion, reprocessing, and sales, thereby reducing the operating costs of the system.

[0063] More specifically: the CL-DRM reactor 8 is the site where the CH4 chemical chain dry reforming reaction takes place, and the large amount of heat energy generated during the incineration process of the regenerative incinerator 5 can be recovered and used to maintain the energy required for the reaction process.

[0064] More specifically: CO and H2 generated in the first step of the CH4 chemical chain dry reforming reaction are mixed and burned with H2 and O2 generated by the photovoltaic water electrolysis device 10 in the combustion furnace 7, and the heat generated is used to heat the mixed gas delivered to the drying furnace 3.

[0065] More specifically: the drying oven 3 is generally made of high-temperature resistant material to withstand high temperatures and maintain good sealing. The heat generated by the combustion furnace 7 heats the mixed gas to a set temperature and then transports it into the drying oven 3 to dry the automotive coating by thermal convection.

[0066] More specifically: After the exhaust gas enters the zeolite rotor 4, the zeolite material adsorbs the volatile organic compounds in the gas, thus concentrating them.

[0067] More specifically: the waste gas undergoes a high-temperature oxidation reaction in the regenerative thermal incinerator 5, oxidizing and decomposing the VOCs organic waste gas into corresponding oxides and water; a small portion of the heat generated by incineration is recovered to provide energy for the zeolite rotor 4, while most of the heat is used to maintain the energy required for the CL-DRM reactor 8.

[0068] More specifically: the photovoltaic water electrolysis device 10 uses solar energy to electrolyze water to produce H2 and O2, which are mixed with CO and H2 generated in the first step reaction and burned, and the mixed gas is indirectly heated and transported to the drying furnace.

[0069] More specifically: Since the combustion of mixed fuels not only produces high-purity CO2, but also H2O, it is necessary to dry and remove water. This can usually be achieved by condensation drying, adsorption drying, or membrane separation technology.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; as long as there is no structural conflict, the various features in the specific embodiments disclosed in this application can be combined with each other in any way, and will not cause the substance of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

[0071] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A low-carbon, low-energy-consumption drying oven system for a painting workshop, characterized in that, Includes a gas mixing tank (2), a drying furnace (3), a zeolite rotor (4), a regenerative thermal incinerator (5), a chimney (6), a combustion furnace (7), a CL-DRM reactor (8), a raw material tank (9), a photovoltaic water electrolysis device (10), and a mixed fuel tank (11). The mixing tank (2), drying furnace (3), zeolite rotor (4), regenerative incinerator (5), and chimney (6) are connected in sequence; The exhaust port of the drying oven (3) is connected to the mixing tank (2) through a return air pipe, and fresh air is introduced into the mixing tank (2). The raw material tank (9) is connected to the CL-DRM reactor (8), the exhaust port of the CL-DRM reactor (8) is connected to the mixed fuel tank (11), and the exhaust port of the photovoltaic water electrolysis device (10) is connected to the mixed fuel tank (11). The mixed fuel tank (11) is connected to the combustion furnace (7), and the exhaust port of the combustion furnace (7) is connected to the CL-DRM reactor (8); The combustion furnace (7) is connected to the mixing tank (2) via a heat exchanger; The regenerative incinerator (5) and the zeolite rotor (4) are connected by a first heat recovery pipe; The regenerative incinerator (5) and the CL-DRM reactor (8) are connected by a second heat recovery pipeline.

2. A method for implementing a low-carbon, low-energy-consumption drying oven in a painting workshop, comprising the following specific steps: Step 1: CH4 feed gas is cracked to produce synthesis gas under the action of catalyst inside the CL-DRM reactor (8). At the same time, the regenerative incinerator (5) recovers heat through the second heat recovery pipeline to maintain the reaction temperature required by the CL-DRM reactor (8). Step 2: The syngas produced in Step 1 is mixed with the gas produced by the photovoltaic water electrolysis device (10) in the mixed fuel tank (11) and then transported to the combustion furnace (7) for combustion and heat release; Step 3: Fresh air and return air from the drying furnace (3) form a mixed gas. The combustion furnace (7) indirectly heats the mixed gas to the set temperature and then sends it to the drying furnace (3) for drying. When the VOCs generated during the process reach a certain concentration, the exhaust gas is discharged and enters the zeolite rotor (4) for further concentration. Step 4: The mixed gas carrying high concentrations of VOCs is transported to the regenerative incinerator (5) for combustion, generating a high temperature of 800-1100℃. A small portion of the heat is recovered through the first heat recovery pipe and provides energy to the zeolite rotor (4) in the form of a heat exchanger. Most of the heat is recovered through the second heat recovery pipe to maintain the temperature conditions required for the reaction in the CL-DRM reactor (8). Step 5: The gas generated by the combustion furnace (7) in step 2 is dried and dehydrated to obtain high-purity CO2, which is then transported to the CL-DRM reactor (8) for catalyst regeneration reaction to obtain high-purity CO and recycle it.

3. The method for implementing a low-carbon, low-energy-consumption drying oven in a coating workshop according to claim 2, characterized in that: The catalyst inside the CL-DRM reactor (8) is an iron-based, nickel-based, or cerium-based metal oxide. The CH4 feed gas is cracked into a syngas product containing CO and H2 in a ratio of 1:

1.

4. The method for implementing a low-carbon, low-energy-consumption drying oven in a coating workshop according to claim 2, characterized in that: The photovoltaic water electrolysis device (10) generates H2 and O2.

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