Method and device for increasing thermal inertia based on phase change thermal storage material

Abstract

The application discloses a method and device for increasing thermal inertia based on phase change heat storage materials, and the method for increasing thermal inertia based on phase change heat storage materials is applied to the device for increasing thermal inertia based on phase change heat storage materials, and the method comprises the following steps: determining phase change heat storage materials according to a pyrolysis temperature interval of the device, and the phase change point of the phase change heat storage materials is in the pyrolysis temperature interval; manufacturing phase change heat storage modules from the phase change heat storage materials; and arranging the phase change heat storage modules on the side wall of a hearth of the device. The application realizes the increase of the thermal inertia of the device based on the phase change heat storage materials.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thermal storage material energy sources, in particular to a method and device for increasing thermal inertia based on phase change thermal storage materials. BACKGROUND

[0002] Electric heating pyrolysis technology is a widely used thermochemical conversion technology in the field of solid waste, sludge, biomass and other treatment, which realizes efficient pyrolysis of materials by external power supply to generate economically valuable biochar, oil and gas products. Conventional pyrolysis devices (such as electric heating pyrolysis furnace) mainly use resistance or induction heating, and the thermal inertia of the furnace body is small during the heating process, which is prone to temperature fluctuations. Especially when fluctuating renewable energy such as abandoned wind and light is used as the power source, the electric heating pyrolysis furnace is significantly affected by unstable power input, resulting in unstable furnace temperature, reduced pyrolysis reaction efficiency, and difficult to guarantee product quality.

[0003] Currently, conventional technologies usually use methods such as increasing heating power or adding heavy wall structures to enhance thermal inertia, which cannot effectively adapt to rapid and frequent temperature changes under fluctuating power conditions. SUMMARY

[0004] The main purpose of the present application is to provide a method and device for increasing thermal inertia based on phase change thermal storage materials, aiming to solve the technical problem that conventional electric heating pyrolysis furnaces and other devices cannot effectively adapt to power fluctuations during pyrolysis, which affects the reaction process.

[0005] To achieve the above purpose, the present application provides a method for increasing thermal inertia based on phase change thermal storage materials, which is applied to a device for increasing thermal inertia based on phase change thermal storage materials. The method includes the following steps:

[0006] Determine the phase change thermal storage material according to the pyrolysis temperature range of the device, and the phase change point of the phase change thermal storage material is within the pyrolysis temperature range;

[0007] Prepare the phase change thermal storage material into a phase change thermal storage module;

[0008] Set the phase change thermal storage module on the side wall of the hearth of the device.

[0009] In a feasible embodiment, the step of preparing the phase change thermal storage material into a phase change thermal storage module includes:

[0010] Melt the phase change thermal storage material and place it in a thermal storage container;

[0011] The phase change heat storage material is dispersed into a porous framework in the heat storage container to obtain the phase change heat storage module.

[0012] In an embodiment, the melting temperature is greater than the phase change point of the phase change heat storage material, and a temperature difference between the melting temperature and the phase change point of the phase change heat storage material is 10-30℃.

[0013] In an embodiment, the phase change heat storage module comprises at least one phase change heat storage unit, and the step of preparing the phase change heat storage material into the phase change heat storage module comprises:

[0014] The total mass of the phase change heat storage material is determined according to the latent heat of the phase change heat storage material and a preset heat storage capacity of the phase change heat storage module.

[0015] The number of the phase change heat storage units is determined according to the total mass of the phase change heat storage material and a preset mass of the phase change heat storage unit.

[0016] The phase change heat storage material is prepared into the phase change heat storage module according to the total mass of the phase change heat storage material and the number of the phase change heat storage units.

[0017] In an embodiment, before the step of determining the total mass of the phase change heat storage material according to the latent heat of the phase change heat storage material and the preset heat storage capacity of the phase change heat storage module, the method further comprises:

[0018] The fluctuation amount of heat in a single fluctuation period is determined according to the missing heat of the device in the single fluctuation period and the required heat of the target reaction in the device in the single fluctuation period.

[0019] The heat storage capacity of the phase change heat storage material is determined according to the fluctuation amount, wherein the heat storage capacity of the phase change heat storage material is greater than the fluctuation amount.

[0020] In an embodiment, before the step of determining the fluctuation amount of heat in a single fluctuation period according to the missing heat of the device in the single fluctuation period and the required heat of the target reaction in the device in the single fluctuation period, the method further comprises:

[0021] The missing heat of the device is determined according to the fluctuation amplitude of the power of the device in a single fluctuation period.

[0022] The required heat of the target reaction in the device is determined according to the unit heat requirement of the target reaction in the device and the yield of the target reaction.

[0023] In an embodiment, the step of arranging the phase change heat storage module on the side wall of the furnace of the device comprises:

[0024] In the case that the pyrolysis temperature interval of the device is less than or equal to the first pyrolysis temperature, the phase change heat storage module is arranged on the side wall of the furnace by integral casting;

[0025] In the case that the pyrolysis temperature interval of the device is greater than or equal to the second pyrolysis temperature, the phase change heat storage module is arranged on the side wall of the furnace after interface optimization;

[0026] In the case that the device needs to respond to temperature changes quickly, the phase change heat storage module provided with strain absorbing material is arranged on the side wall of the furnace.

[0027] In an available embodiment, the phase change heat storage material includes at least one of nitrate and carbonate.

[0028] The application also provides a device for increasing thermal inertia based on phase change heat storage material, which comprises a furnace and a phase change heat storage module arranged on the side wall of the furnace, wherein the phase change heat storage module is made of phase change heat storage material determined according to the pyrolysis temperature interval of the device, and the phase change point of the phase change heat storage material is within the pyrolysis temperature interval.

[0029] In an available embodiment, the phase change heat storage module is uniformly distributed along the side wall of the furnace.

[0030] And / or, the coverage rate of the phase change heat storage module on the side wall of the furnace is greater than or equal to a preset coverage rate threshold.

[0031] The application provides a method for increasing thermal inertia based on phase change heat storage material, which is applied to a device for increasing thermal inertia based on phase change heat storage material, and the device comprises a furnace and a phase change heat storage module arranged on the side wall of the furnace. The method comprises the following steps: determining phase change heat storage material according to the pyrolysis temperature interval of the device, wherein the phase change point of the phase change heat storage material is within the pyrolysis temperature interval, the phase change heat storage material is accompanied by heat absorption and heat release processes when it changes phase, the temperature of the phase change point of the phase change heat storage material matches the actual reaction temperature, i.e. the pyrolysis temperature interval, during the pyrolysis process of the device, and the phase change heat storage material can efficiently perform heat absorption and heat release processes within the pyrolysis temperature interval of the device; then, the phase change heat storage material is made into a phase change heat storage module, the phase change heat storage module can be installed flexibly and can more efficiently increase the thermal inertia of the device; the phase change heat storage module is installed on the side wall of the furnace of the device, and the phase change heat storage module is used to absorb excess heat of the furnace or release stored heat; further, the thermal inertia of the device is increased by the phase change heat storage material in the phase change heat storage module when it changes phase, and the phase change heat storage material can provide heat compensation for the reaction process without external control circuit when the temperature changes due to power fluctuation. The thermal inertia of the device is increased by the phase change heat storage material. BRIEF DESCRIPTION OF DRAWINGS

[0032] The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate embodiments consistent with the present application and, together with the description, further serve to explain the principles of the application.

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the accompanying drawings required to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

[0034] Figure 1 A flowchart is provided for an embodiment of the method for increasing thermal inertia based on phase change heat storage material of the present application.

[0035] Figure 2 A device schematic diagram is provided for an embodiment of the method for increasing thermal inertia based on phase change heat storage material of the present application. Figure One

[0036] Figure 3 A device schematic diagram is provided for an embodiment of the method for increasing thermal inertia based on phase change heat storage material of the present application. Figure Two

[0037] BRIEF DESCRIPTION OF DRAWINGS

[0038] 10, furnace shell; 20, furnace chamber; 30, phase change heat storage module;

[0039] 301, phase change heat storage unit; 40, electric heating wire.

[0040] The purposes, functional features and advantages of the present application will be further explained with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0041] It should be understood that the specific embodiments described herein are merely intended to explain the technical solutions of the present application, and are not intended to limit the present application.

[0042] In order to better understand the technical solutions of the present application, the following will be described in detail in combination with the drawings and specific embodiments.

[0043] ​​The main solution of the embodiment of the application is that the method for increasing thermal inertia based on phase change heat storage material is applied to a device for increasing thermal inertia based on phase change heat storage material, and the device comprises a furnace body, a hearth and a phase change heat storage module. The method comprises the following steps: determining a phase change heat storage material according to a pyrolysis temperature range of the device, wherein the phase change point of the phase change heat storage material is within the pyrolysis temperature range; manufacturing the phase change heat storage material into a phase change heat storage module; installing the phase change heat storage module on the side wall of the hearth of the device; and increasing the thermal inertia of the device through the heat change process of the phase change heat storage material in the phase change heat storage module.

[0044] Since the device for pyrolysis reaction, such as a conventional electric heating pyrolysis furnace, cannot effectively adapt to temperature changes caused by power fluctuations during the pyrolysis process, the conventional technology usually adopts means such as increasing heating power or adding heavy wall structure to enhance thermal inertia, which increases energy consumption and equipment cost to a certain extent, and cannot effectively adapt to rapid and frequent temperature changes under fluctuating power conditions.

[0045] The embodiment of the application provides a method for increasing thermal inertia based on phase change heat storage material, which is applied to a device for increasing thermal inertia based on phase change heat storage material. The device comprises a hearth and a phase change heat storage module, and the phase change heat storage module is arranged on the side wall of the hearth. The method comprises the following steps: determining a phase change heat storage material according to a pyrolysis temperature range of the device, wherein the phase change point of the phase change heat storage material is within the pyrolysis temperature range, the phase change heat storage material is accompanied by a heat absorption and heat release process in the case of phase change, the temperature of the phase change point of the phase change heat storage material matches the actual required reaction temperature, i.e. the pyrolysis temperature range, of the device during the pyrolysis process, and the phase change heat storage material efficiently performs the heat absorption and heat release process within the pyrolysis temperature range of the device; then, the phase change heat storage material is manufactured into a phase change heat storage module, the phase change heat storage module can be flexibly installed, and the thermal inertia of the device is more efficiently increased; the phase change heat storage module is installed on the side wall of the hearth of the device, and the phase change heat storage module is used for absorbing excess heat of the hearth or releasing stored heat; further, the thermal inertia of the device is increased through the phase change heat storage material in the phase change heat storage module in the case of phase change, and the heat compensation for the reaction process under the condition of temperature changes caused by power fluctuations can be realized without an external control circuit. The thermal inertia of the device is increased through the phase change heat storage material.

[0046] Based on this, the first embodiment of the application provides a method for increasing thermal inertia based on phase change heat storage material, which is applied to a device for increasing thermal inertia based on phase change heat storage material. The method comprises the following steps S10-S30: Figure 1

[0047] ​Step S10, determine the phase change thermal storage material according to the pyrolysis temperature range of the device, and the phase change point of the phase change thermal storage material is within the pyrolysis temperature range;

[0048] In a feasible embodiment, a suitable phase change thermal storage material is selected for a device that increases the thermal inertia based on phase change thermal storage material. The basis for selection is the pyrolysis temperature range of the device, and the phase change point temperature of the selected phase change thermal storage material must be within this pyrolysis temperature range, so as to ensure that the phase change thermal storage material can play its heat storage and heat release characteristics within the working temperature range of the device, thereby increasing the thermal inertia of the device.

[0049] Optionally, the device can be an electric heating pyrolysis furnace, mainly used in the field of thermal chemical conversion technology for solid waste, sludge, biomass, etc. The furnace realizes efficient pyrolysis of materials by providing heat from an external power source, producing biochar, oil and gas products with economic value. The furnace body is the outer shell of the device, providing a relatively closed space for the entire device to accommodate other components and serve as protection and support. The furnace chamber is the space inside the furnace body for heat exchange or chemical reaction, and is the core area of heat generation, transfer and utilization, usually in direct contact with the heating source and the heated object. The phase change thermal storage module is a component in the device that is specifically used to store and release heat, composed of phase change thermal storage material and corresponding packaging structure.

[0050] Optionally, the pyrolysis temperature range refers to the temperature range required for the normal operation of the pyrolysis device, i.e. the upper and lower limits of the temperature during operation.

[0051] Optionally, the phase change thermal storage material refers to a material that can undergo a phase change (such as from solid to liquid or from liquid to solid) at a specific temperature (phase change point) and absorb or release a large amount of heat during the phase change. The characteristic of phase change thermal storage material is that during the phase change, the temperature remains relatively stable while a large amount of latent heat is absorbed or released, so that the phase change thermal storage material can store heat when the temperature rises and release heat when the temperature drops, thereby playing a role in temperature regulation and increasing thermal inertia.

[0052] Optionally, the phase change point refers to the temperature at which the phase change thermal storage material undergoes a phase change, i.e. the specific temperature at which the material changes from one phase to another. Different phase change thermal storage materials have different phase change points. For example, the phase change point of phase change thermal storage material A is 400℃, when the temperature rises to 400℃, phase change thermal storage material A begins to change from solid to liquid, absorbing heat; when the temperature drops to 400℃, phase change thermal storage material A changes from liquid to solid, releasing heat.

[0053] Optionally, the phase transition point of the phase change heat storage material can be calculated or measured by experiment. For a single and definite phase change heat storage material, the phase transition point can be obtained by consulting the corresponding phase diagram; for a common mixture, the corresponding phase transition point can be obtained by consulting the corresponding eutectic table; in the case of adjusting the proportion of the phase change heat storage material to adjust the phase transition point, the corresponding phase transition point can be determined by differential scanning calorimetry.

[0054] In a feasible embodiment, the phase change heat storage material comprises at least one of nitrate and carbonate.

[0055] Optionally, the nitrate can be NaNO3 (sodium nitrate), KNO3 (potassium nitrate), or a NaNO3-KNO3 eutectic mixture; the carbonate can be Li2CO3 (lithium carbonate), Na2CO3 (sodium carbonate), K2CO3 (potassium carbonate), or a eutectic mixture thereof.

[0056] Step S20, the phase change heat storage material is made into a phase change heat storage module;

[0057] In a feasible embodiment, the determined phase change heat storage material is pretreated, dried, and subjected to a melting treatment, and then poured into a specially made heat storage container resistant to high temperature and corrosion to naturally cool to solidification, thereby forming a phase change heat storage module with a fixed shape.

[0058] Optionally, the phase change heat storage module refers to a unit group with a fixed shape and structure formed by packaging the phase change heat storage material in a heat storage container after certain treatment.

[0059] In another feasible embodiment, the step S20 of making the phase change heat storage material into a phase change heat storage module comprises steps S201-S202:

[0060] Step S201, after melting the phase change heat storage material, placing it in a heat storage container;

[0061] Optionally, the size of the heat storage container is determined according to the actual production needs of the device. Generally, the heat storage reaction module is determined.

[0062] Optionally, the material of the heat storage container is determined according to the phase transition point of the phase change heat storage material and the pyrolysis temperature range of the device. The material of the heat storage container can be stainless steel or ceramic. For example, in the case of stainless steel as the material of the heat storage container, the pyrolysis temperature range of the device can be within the range of 400℃; in the case of ceramic as the material of the heat storage container, the pyrolysis temperature range of the device can reach 500℃ or above.

[0063] In a feasible embodiment, the melting temperature is greater than the phase transition point of the phase change heat storage material, and the temperature difference between the melting temperature and the phase transition point of the phase change heat storage material is 10-30℃.

[0064] Optionally, the temperature difference between the melting temperature and the phase change point of the phase change heat storage material is 10-30°C, ensuring that the phase change material can completely change from solid to liquid at the melting temperature. If the melting temperature is only slightly higher than the phase change point, it may cause part of the phase change material to not melt sufficiently, thereby affecting the performance of the phase change heat storage material. If the melting temperature is too high, more than 30°C above the phase change point, the high temperature may accelerate the aging and decomposition of the phase change material, reducing its service life and performance stability, and the high temperature may also increase energy consumption and increase costs.

[0065] The present embodiment sets an appropriate melting temperature, which is greater than the phase change point and has a temperature difference of 10-30°C from the phase change point. The phase change heat storage material can fully change phase, and the high melting temperature does not increase costs or cause the phase change heat storage material to age and decompose, reducing service life and stability.

[0066] Step S202, dispersing the phase change heat storage material into the porous framework in the heat storage container to obtain a phase change heat storage module.

[0067] In a feasible embodiment, the porous framework has a pore structure, and when the phase change heat storage material is filled into the pores of the porous framework, the pores of the porous framework will divide the phase change heat storage material into many small units, thereby achieving dispersion of the phase change heat storage material. The contact area between the dispersed phase change heat storage material and the porous framework increases, and the thermal resistance decreases, thereby accelerating the heat transfer speed. When the ambient temperature changes, the phase change heat storage material can absorb or release heat faster, improving the efficiency of heat storage and heat release.

[0068] Optionally, the porous framework is a solid material with a large number of pore structures, and the pore size, shape, and distribution can be designed and controlled according to different needs. Common porous framework materials include foamed metal, porous ceramic, activated carbon, etc. These materials have a large specific surface area and abundant pore structure, which can provide good support and dispersion space for the phase change heat storage material.

[0069] The present embodiment designs the size of the heat storage container according to the actual production process of the pyrolysis device, and determines the material of the heat storage container according to the pyrolysis temperature range and the phase change point of the phase change heat storage material, so that the heat storage container is more suitable for actual production needs. Further, the heat storage container is built-in with a porous framework for dispersing the phase change heat storage material, increasing the contact area, accelerating the heat transfer, and improving the efficiency of heat storage and heat release.

[0070] Step S30, arranging the phase change heat storage module on the side wall of the furnace of the device;

[0071] Optionally, the phase change heat storage module can be arranged outside the sidewall of the furnace, or arranged inside the sidewall of the furnace (outside the reaction area), or arranged in the middle of the inner and outer walls of the sidewall of the furnace.

[0072] In another possible embodiment, the step of arranging the phase change heat storage module on the sidewall of the furnace of the device comprises steps S301-S303:

[0073] Step S301, in the case where the pyrolysis temperature range of the device is less than or equal to a first pyrolysis temperature, the phase change heat storage module is arranged on the sidewall of the furnace by integral casting.

[0074] In one possible embodiment, the first pyrolysis temperature is 400℃, that is, in the case of medium reaction temperature, the phase change heat storage module is arranged on the sidewall of the furnace by integral casting.

[0075] Optionally, a deep U-shaped ring groove (partitioned according to requirements) is cast outside the cylindrical furnace shell, integrally cast with the sidewall of the furnace, and a Ni-Mo corrosion-resistant layer is sprayed on the inner wall of the deep U-shaped ring groove. When the pyrolysis device is initially installed, it is heated to 250℃ by vacuum, so that the molten phase change heat storage material is injected through the bottom filling port and fills the deep U-shaped ring groove, and then the opening is sealed and becomes an integral part of the furnace wall. The reaction temperature is 400℃ and below, and the reaction conditions are relatively mild, and the thermal expansion and thermal fatigue effect of the phase change heat storage material is relatively small. The integral casting method can long-term maintain the integrity and sealing of the structure. Moreover, since integral casting does not need to be frequently disassembled, maintenance costs and potential failure points are reduced.

[0076] Step 302, in the case where the pyrolysis temperature range of the device is greater than or equal to a second pyrolysis temperature, the phase change heat storage module is arranged on the sidewall of the furnace after interface optimization;

[0077] In one possible embodiment, the second pyrolysis temperature is 500℃, that is, in the case of higher reaction temperature, interface optimization is adopted, which includes using the same material interface or coating a high-inert coating on the interface.

[0078] Optionally, two layers of stainless steel sheaths are arranged outside the hearth, a closed interlayer is formed by vacuum diffusion welding, vacuum molten salt is poured, and the top is sealed by electron beam welding; in a high temperature environment, electrochemical corrosion may occur between different materials, causing interface damage. Using the same material as the interface can prevent such electrochemical corrosion and improve the durability of the structure. Further, a high inert coating can form a protective film on the surface of the material, preventing corrosive substances such as oxygen and moisture from contacting the material, thereby reducing corrosion. At the same time, the coating can also relieve thermal stress and reduce the impact of thermal fatigue on the material. High temperatures can accelerate the corrosion and aging process of the material, and thermal fatigue can also cause cracks and damage to the material. The use of an interface with the same material or a high inert coating can effectively improve the corrosion resistance and thermal fatigue resistance of the material at high temperatures, extending the service life of the structure.

[0079] In step S303, the phase change heat storage module provided with strain absorbing material is arranged on the side wall of the furnace in a case where rapid response to temperature change is required.

[0080] In an available embodiment, the strain absorbing material includes corrugated sheets, foam layers, and graphite paper. The strain absorbing material has good elasticity and deformation ability. In a medium-high temperature rapid response scenario, the material will undergo a large volume change due to rapid temperature changes. The strain absorbing material can convert these volume changes into elastic deformation, thereby releasing internal stress and preventing the phase change heat storage module from being damaged due to stress concentration. Further, the medium-high temperature rapid response scenario requires the ability to adapt to temperature changes in a short period of time. The strain absorbing structure can timely absorb and release the stress caused by temperature changes, and at the same time, the strain absorbing material will not significantly hinder temperature changes, thus meeting the requirement of rapid response.

[0081] Optionally, the case where rapid response to temperature change is required refers to an application environment where the pyrolysis device has frequent and large temperature fluctuations and requires the pyrolysis device to complete temperature regulation in a short period of time, and the pyrolysis device needs to withstand thermal stress caused by temperature changes without failure.

[0082] Optionally, a spiral channel is machined inside the side wall of the furnace, the top of the channel is covered with a plate and a closed cavity is formed by laser deep penetration welding, and expanded graphite paper is arranged in the channel for strain absorption; after the furnace body is welded as a whole, the bottom end is plugged to evacuate air and the phase change heat storage material is poured at 350°C, and then the phase change heat storage module is formed by sealing with welding, which can be used in a case where rapid response to temperature change is required.

[0083] This embodiment sets the phase change heat storage module in different ways for different scenarios, making the design and installation of the phase change heat storage module more suitable for specific application scenarios and improving the use efficiency of the phase change heat storage module.

[0084] The embodiment determines the phase change heat storage material according to the pyrolysis temperature range of the device, the phase change heat storage material changes phase at a temperature within the pyrolysis temperature range, the phase change heat storage material changes phase accompanied by the process of heat absorption and heat release, the phase change point of the phase change heat storage material matches the actual reaction temperature required by the device in the pyrolysis process, that is, the pyrolysis temperature range, to ensure that the phase change heat storage material efficiently absorbs and releases heat within the pyrolysis temperature range of the device; further, the phase change heat storage material is made into a phase change heat storage module, the phase change heat storage module can be flexibly installed, and the thermal inertia of the pyrolysis device is more efficiently increased; the phase change heat storage module is arranged on the side wall of the furnace of the device, and the phase change heat storage module can absorb the excess heat of the furnace or release the stored heat. Through the heat change process of the phase change heat storage material in the phase change heat storage module, the thermal inertia of the device is increased, and heat compensation for the pyrolysis reaction process can be realized without external control circuit when the power fluctuation causes temperature change. The thermal inertia of the device is increased by the phase change heat storage material.

[0085] Based on the first embodiment of the present application, the second embodiment of the present application is provided, and in the second embodiment, the same or similar contents as the above embodiments can be referred to the above introduction, and will not be described in detail. The phase change heat storage module includes at least one phase change heat storage unit, and the step S20 of making the phase change heat storage material into a phase change heat storage module includes:

[0086] Step S201, determining the total mass of the phase change heat storage material according to the latent heat of the phase change heat storage material and the preset heat storage capacity of the phase change heat storage module;

[0087] Step S202, determining the number of phase change heat storage units according to the total mass of the phase change heat storage material and the preset mass of the phase change heat storage unit;

[0088] Step S203, making the phase change heat storage material into a phase change heat storage module according to the total mass of the phase change heat storage material and the number of phase change heat storage units.

[0089] Optionally, the latent heat of the phase change heat storage material refers to a large amount of heat absorbed or released by the phase change heat storage material in the process of phase change (such as from solid to liquid or from liquid to solid), and this heat is the latent heat of phase change. The size of the latent heat is related to the type of the material.

[0090] Optionally, the preset heat storage capacity of the phase change heat storage module refers to the total amount of heat that can be stored by the phase change heat storage module.

[0091] Optionally, the total mass of the phase change heat storage material refers to the mass of the phase change heat storage material required to be arranged in the pyrolysis device.

[0092] Optionally, the phase change heat storage unit refers to a component of the phase change heat storage module, and the phase change heat storage module includes at least one phase change heat storage unit.

[0093] Optionally, the preset mass of the phase change heat storage unit refers to the fixed mass of the single phase change heat storage unit determined by the pyrolysis device in the design stage according to the actual demand and process conditions.

[0094] Optionally, the number of the phase change heat storage units refers to the quotient obtained by dividing the total mass of the phase change heat storage material by the mass of each preset phase change heat storage unit.

[0095] Optionally, the total mass of the phase change heat storage module The total mass of the phase change heat storage module can be determined according to the following formula:

[0096] m PCM =Q PCM / L

[0097] Wherein, L is the latent heat of the phase change heat storage material (unit: kJ·kg -1 ), Q PCM is the heat storage capacity of the phase change heat storage module (unit: J).

[0098] Optionally, the number n of the phase change heat storage units can be determined according to the following formula:

[0099] n=m PCM / m unit

[0100] Wherein, m unit is the mass of each phase change heat storage unit (unit: kg).

[0101] In another possible embodiment, before the step of determining the total mass of the phase change heat storage material according to the latent heat of the phase change heat storage material and the heat storage capacity of the preset phase change heat storage module, it further comprises:

[0102] Step B10, determining the fluctuation amount of heat in a single fluctuation period according to the missing heat of the device in a single fluctuation period and the required heat of the target reaction in the device;

[0103] Step B20, determining the heat storage capacity of the phase change heat storage material according to the fluctuation amount, wherein the heat storage capacity of the phase change heat storage material is greater than the fluctuation amount.

[0104] Optionally, the power fluctuation refers to the phenomenon that the input of the power source is unstable during the heating process of the pyrolysis device, especially when the wind, light and other fluctuating renewable energy sources are used as the power source, the pyrolysis device is more obviously affected by the instability of the power input. The power fluctuation can be the fluctuation of photovoltaic caused by the cloud cluster passing or the existence of shadow. The single fluctuation period refers to the time when the cloud cluster passes or the shadow exists.

[0105] Optionally, the missing heat of the pyrolysis device can be the energy reduced compared with the case that the power supply is not fluctuated due to the power supply fluctuation.

[0106] Optionally, the required heat of the target reaction in the pyrolysis device refers to the heat consumed by the pyrolysis device to maintain the normal progress of the target reaction in a single fluctuation period.

[0107] Optionally, the fluctuation amount of heat in a single fluctuation period refers to the sum of the missing heat of the pyrolysis device and the required heat of the target reaction in the pyrolysis device in a single fluctuation period.

[0108] Optionally, the heat storage capacity of the phase change heat storage material can be determined according to the following formula:

[0109]

[0110] Wherein, is the missing heat of the pyrolysis device (unit: J), is the required heat of the target reaction in the pyrolysis device (unit: J), and S is the safety redundancy coefficient.

[0111] Optionally, the safety redundancy coefficient refers to the coefficient that needs to be considered in the case that the heat storage capacity meets the fluctuation amount and the aging and heat dissipation loss in the production process. Optionally, S is 1.1-1.3.

[0112] In another possible embodiment, before the step of determining the fluctuation amount of heat in a single fluctuation period according to the missing heat of the device in a single fluctuation period and the required heat of the target reaction in the device, it further comprises:

[0113] Step C10, determining the missing heat of the device according to the fluctuation amplitude of the power of the device in a single fluctuation period;

[0114] Step C20, determining the required heat of the target reaction in the device according to the unit heat requirement of the target reaction in the device and the yield of the target reaction.

[0115] Optionally, the fluctuation amplitude of the power of the device in a single fluctuation period refers to the ratio of the power drop of the device in a single fluctuation period.

[0116] Optionally, the unit heat requirement of the target reaction in the device refers to the heat required to be absorbed in the target reaction process carried out in the pyrolysis device for each unit amount (such as unit amount of substance, unit mass, etc.) of the target reaction completed.

[0117] Optionally, the yield of the target reaction refers to the actual yield of the target reaction in the pyrolysis device per unit time.

[0118] Optionally, the missing heat can be determined according to the following formula:

[0119]

[0120] wherein, the fluctuation amplitude of the power of a single pyrolysis device in a single fluctuation period (unit: %), optionally, may be 10%~25%; P e is the rated electric power of a single pyrolysis device (unit: kW); t dip is a single fluctuation period (unit: s).

[0121] Optionally, the required heat quantity of the target reaction may be determined according to the following formula:

[0122]

[0123] wherein, is the yield of the target reaction (unit: kg·h⁻ 1 ), q py is the unit heat requirement of the target reaction (unit: MJ·kg⁻ 1 ), optionally, q py may be 1.1~2 MJ·kg⁻ 1 .

[0124] Optionally, taking the production of straw biochar by the pyrolysis device as an example, the process of determining the total mass of the phase change heat storage material and the number of phase change heat storage units is as follows:

[0125] Step D10, the missing heat quantity of the pyrolysis device is determined according to the following formula:

[0126]

[0127] wherein, F PV is 15%, P e is 150 kW, and t dip is 120 s.

[0128] Step D20, the required heat quantity of the target reaction (preparation of straw biochar) in the pyrolysis device is determined according to the following formula:

[0129]

[0130] wherein, is 50 kg·h -1 , q py is 1.5 MJ·kg -1 , and t dip is 120 s.

[0131] Step D30, the heat storage capacity of the phase change heat storage module can be determined according to the following formula:

[0132]

[0133] wherein S is 1.25.

[0134] Step D40, the total mass of the phase change heat storage module can be determined according to the following formula:

[0135] m PCM =Q PCM / L=6.5×10 6 / 3.7×10 5 ≈17.6kg

[0136] wherein, in the case of using Li2CO3-Na2CO3 eutectic mixture as the phase change heat storage material, the latent heat L is 370 kJ·kg -1 .

[0137] Step D50, the number n of the phase change heat storage modules can be determined according to the following formula:

[0138] n=m PCM / m unit =17.6 / 2.5=7.04≈8

[0139] wherein m is the mass (kg) of each phase change heat storage module, and m is 2.5 kg.

[0140] Optionally, PID (Proportional-Integral-Derivative Controller) refers to a desired power value calculated by the PID algorithm according to various parameters of the device in the production process, which is used to adjust the running state of the whole system, so that the pyrolysis device can stably reach and maintain the set working condition. The PID-power supply power greater than or equal to 15% of the charge-discharge power of the phase change heat storage module means that the difference between the control power output by the PID and the actual power supply power is greater than or equal to 15% of the charge-discharge power of the phase change heat storage module. Reserving 15% of the charge-discharge power of the phase change heat storage module can ensure that the pyrolysis device has enough energy to adjust and balance the impact and maintain the stable operation of the pyrolysis reaction in the device.

[0141] The embodiment simulates the total mass of the phase change heat storage material and the number of phase change heat storage units under different configurations by aiming at different phase change heat storage materials or power fluctuation characteristics, and forms a general thermal inertia enhancement scheme suitable for different application scenarios.

[0142] ​The embodiment of the present application also provides a device for increasing thermal inertia based on a phase change heat storage material, which applies the method for increasing thermal inertia based on a phase change heat storage material as described above, and the device comprises:

[0143] a hearth and a phase change heat storage module, the phase change heat storage module is arranged on the side wall of the hearth, wherein the phase change heat storage module is made of a phase change heat storage material, the phase change heat storage material is determined according to a pyrolysis temperature range of the device, and the phase change point of the phase change heat storage material is within the pyrolysis temperature range.

[0144] Optionally, referring to Figure 2 , the pyrolysis device comprises a furnace shell 10, a hearth 20, a phase change heat storage module 30, a phase change heat storage unit 301 and an electric heating wire 40.

[0145] In another possible embodiment, the phase change heat storage modules are uniformly distributed along the side wall of the hearth.

[0146] Optionally, the phase change heat storage module has a coverage rate on the side wall of the hearth, and the coverage rate is greater than or equal to a preset coverage rate threshold.

[0147] Optionally, the electric heating pyrolysis furnace can be a box-type electric heating pyrolysis furnace, referring to Figure 3 , the furnace shell 10 and the hearth 20 are cuboids or cubes, and the electric heating wire 40 and the phase change heat storage unit 301 are usually arranged in layers inside the furnace shell 10 and the hearth 20. The internal space of the box-type electric heating pyrolysis furnace is relatively regular, which is convenient for installing various components required for pyrolysis. Moreover, the cubic structure is relatively simple in the process of construction and installation, and can reduce the manufacturing cost. Due to the regular internal space, the flow of hot gas in the furnace is relatively stable, which is conducive to achieving a relatively uniform pyrolysis effect. When processing some blocky or granular materials, it can be ensured that the materials can be heated uniformly at various positions, thereby improving the efficiency and quality of pyrolysis. In a possible embodiment, the heat load of each region of the side wall of the hearth can be different (for example, the temperature near the combustion zone is higher). By uniformly distributing the heat storage modules, local overheating or heat concentration can be avoided, and the overall temperature field of the hearth can be ensured to be stable.

[0148] Optionally, the coverage rate refers to the percentage of the coverage area or the perimeter of the heat storage module to the total area or the perimeter of the side wall of the hearth. The preset coverage rate threshold refers to the minimum percentage of the coverage area or the perimeter of the phase change heat storage module to the total area or the total perimeter of the side wall of the hearth, which is obtained by calculation to ensure that the phase change heat storage module can be effectively used for heat storage and release under different working conditions, the overall temperature field of the hearth can be maintained to be stable, and the system thermal efficiency requirement can be met. Preferably, the preset coverage rate threshold is 70% to 85%. For example, the coverage rate can be ≥70% of the perimeter of the side wall of the hearth.

[0149] Optionally, during the installation process, the phase change heat storage modules are arranged alternately with the heating wires, so that the heat generated by the heating wires can be more evenly transferred to the phase change heat storage modules; the ΔT of the heat conduction layer is less than 5°C (during the production process at the rated power), the ΔT of the heat conduction layer refers to the temperature difference between the two ends of the heat conduction layer, and the ΔT of the heat conduction layer is controlled to be less than 5°C, so that the entire production process can be carried out in a stable temperature environment, and the quality and production efficiency of the product are improved; further, if it is necessary to arrange a small number of phase change heat storage modules considering economic factors, the phase change heat storage modules are preferentially arranged at the lower part of the side wall of the hearth, in the hearth, hot air flows upward naturally, resulting in that the temperature at the lower part of the hearth is relatively low, and the temperature at the upper part of the hearth is relatively high. Therefore, the heat loss at the lower part of the hearth is relatively large. Arranging the phase change heat storage modules at the lower part of the side wall of the hearth can more effectively absorb and store the lost heat.

[0150] The device based on the method of increasing thermal inertia of the phase change heat storage material in the embodiment increases the thermal inertia of the phase change heat storage material, sets a furnace body, a hearth and phase change heat storage modules, stores or releases heat based on the heat change process caused by the phase change of the phase change heat storage material at the phase change point, and provides stable reaction temperature conditions for the reaction in the device, so that the reaction in the device can be normally carried out under the action of the phase change heat storage modules in the case of power fluctuation of the device. Further, the installation parameters of the phase change heat storage modules on the side wall of the hearth are determined by a preset parameter algorithm, so that the phase change heat storage modules are uniformly installed on the side wall of the hearth under the condition of meeting the preset coverage rate threshold, and the effectiveness of the phase change heat storage modules in storing or releasing heat is improved.

[0151] In order to enable the above-mentioned details and operations of the embodiments of the present application to be clearly understood by those skilled in the art, and the significant performance of the embodiments of the present application to be embodied, the above-mentioned technical solutions are illustrated by multiple embodiments as follows.

[0152] Embodiment 1

[0153] Step E10, a deep U-shaped ring groove with a depth of 24 mm is cast outside the cylindrical electric heating pyrolysis furnace shell with a diameter of φ900 mm, the ring groove is divided into eight sections, and the ring groove is integrally cast with the furnace shell wall thickness, the inner wall of the ring groove is sprayed and coated, and a layer of Ni-Mo corrosion-resistant layer with a thickness of 150 µm is sprayed and coated;

[0154] Step E20, a eutectic mixture of NaNO3-KNO3 is provided as the phase change heat storage material 1, the material ratio is mass ratio NaNO3:KNO3=6:4, the melting point (phase change point) is about 220°C, and the phase change latent heat is about 110 kJ / kg. During the initial assembly of the furnace body, the furnace body is vacuum heated, and the temperature is raised to 250°C;

[0155] Step E30, the phase change heat storage material 1 is heated to melt, and is injected into the deep U-shaped ring groove through a filling opening at the bottom of the furnace body until the ring groove is completely filled, and the filling opening is sealed to make the sealed ring groove and the furnace wall an integral whole;

[0156] Step E40, an AlSi mesh with a thickness of 0.25 mm is embedded in each ring groove in advance, and the volume fraction of the AlSi mesh is 8%, so as to construct a multi-directional heat conduction path;

[0157] Step E50, the heat storage capacity of the entire electric heating pyrolysis furnace reaches 6.8 MJ, and the equivalent phase change heat storage material 1 with a mass of 62 kg is uniformly distributed in the eight ring grooves, so as to ensure that the coverage area of the ring groove to the furnace wall is not less than 75%.

[0158] Step E60, when the temperature in the furnace exceeds 220°C during the operation of the electric heating pyrolysis furnace, the phase change heat storage material 1 undergoes solid-liquid phase change, absorbs excessive heat of the furnace body, effectively buffers the temperature fluctuation caused by power fluctuation or load change, and when the temperature in the furnace decreases, the phase change heat storage material 1 gradually solidifies and releases the stored latent heat of phase change, so as to maintain the stability of the pyrolysis temperature in the furnace.

[0159] Example 2

[0160] Step F10, the electric heating pyrolysis furnace cylinder is wrapped with two layers of 1.5 mm thick 310S stainless steel sheath, a spacing of 12 mm is kept between the two layers of sheath, vacuum diffusion welding process is used to weld the two layers of sheath, and a closed interlayer with a depth of 10 mm is formed;

[0161] Step F20, Li2CO3-Na2CO3 is provided as the phase change heat storage material 2, the mass ratio is 52% Li2CO3 and 48% Na2CO3, the melting point (phase change point) is about 497°C, and the latent heat of phase change is about 370 kJ / kg;

[0162] Step F30, under the condition of 520°C, the Li2CO3-Na2CO3 is uniformly melted and mixed, and then is injected into the closed interlayer, an electron beam welding is used to seal the top of the interlayer, and a Φ 6 mm corrugated expansion compensation sheet is arranged, which is used to absorb the volume strain in the heat cycle process;

[0163] Step F40, a 1 mm thick Cu-Cr foam plate with a porosity of 90% is inserted into the closed interlayer as a layered insert, and the layer spacing is set to 30 mm, so as to enhance the heat conduction performance;

[0164] Step F50, the heat storage capacity of the entire electric heating pyrolysis furnace reaches 8.0 MJ, and the volume fraction of the phase change heat storage material 2 in the interlayer reaches 82%, and the mass is about 60 kg;

[0165] Step F60, when the furnace temperature exceeds 497°C, the phase change heat storage material 2 undergoes solid-liquid phase change, absorbs excessive heat of the furnace body, effectively buffers the temperature fluctuation caused by power fluctuation or load change; when the furnace temperature decreases, the phase change heat storage material 2 gradually solidifies and releases the stored latent heat of phase change, thereby maintaining the stability of the pyrolysis temperature inside the furnace.

[0166] Example 3

[0167] Step G10, a 16 mm × 14 mm spiral channel is processed inside the 12 mm thick wall of the electric heating pyrolysis furnace, the pitch is set to 40 mm, and 4 turns are processed, so that the coverage efficiency of the channel to the furnace wall reaches 78%, a cover plate made of the same material as the furnace wall is covered on the top of the channel, laser deep penetration welding process is used to weld the cover plate and the furnace wall to form a closed cavity, and high vacuum pumping operation is performed on the furnace body through the plug at the bottom end of the furnace body;

[0168] Step G20, NaNO3(industrial purity above 99%) is provided as the phase change heat storage material 3, the melting point (phase change point) is about 306°C, and the latent heat of phase change is about 172 kJ / kg, the furnace body is heated to 350°C, the phase change heat storage material 3 is filled into the closed cavity of the spiral channel, and the plug at the bottom end is sealed by using tungsten TIG welding;

[0169] Step G30, 8 wt% of expanded graphite paper is pre-laid in the spiral channel, and the thermal conductivity of the compacted graphite paper is about 40 W·m -1 ·K -1 ;

[0170] Step G40, the total length of the spiral channel is ensured to reach 11.3 m, and the mass of the filled phase change heat storage material 3 is 72 kg, so that the heat storage capacity of the whole system reaches 12.4 MJ;

[0171] Step G50, when the furnace temperature exceeds 306°C, the phase change heat storage material 3 undergoes solid-liquid phase change, absorbs excessive heat of the furnace body, effectively buffers the temperature fluctuation caused by power fluctuation or load change; when the furnace temperature decreases, the phase change heat storage material 3 gradually solidifies and releases the stored latent heat of phase change, thereby maintaining the stability of the pyrolysis temperature inside the furnace.

[0172] The above is only part of the embodiments of the present application, and does not limit the patent scope of the present application, any equivalent structural transformation made by using the contents of the present application specification and drawings, or direct / indirect application in other related technical fields is included in the patent protection scope of the present application.

Claims

1. A method of increasing thermal inertia based on a phase change heat storage material, characterized by, The method for increasing thermal inertia based on the phase change heat storage material is applied to a device for increasing thermal inertia based on the phase change heat storage material, and the method comprises the following steps: determining the phase change heat storage material according to a pyrolysis temperature interval of the device, wherein the phase change point of the phase change heat storage material is within the pyrolysis temperature interval; determining the missing heat of the device according to the fluctuation amplitude of the power of the device within a single fluctuation period; determining the required heat of the target reaction in the device according to the unit heat demand of the target reaction in the device and the yield of the target reaction; determining the fluctuation amount of heat within a single fluctuation period according to the missing heat of the device within a single fluctuation period and the required heat of the target reaction in the device; determining the heat storage capacity of the phase change heat storage material according to the fluctuation amount, wherein the heat storage capacity of the phase change heat storage material is greater than the fluctuation amount; determining the total mass of the phase change heat storage material according to the latent heat of the phase change heat storage material and the preset heat storage capacity of the phase change heat storage module; determining the number of the phase change heat storage units according to the total mass of the phase change heat storage material and the preset mass of the phase change heat storage unit; manufacturing the phase change heat storage material into a phase change heat storage module according to the total mass of the phase change heat storage material and the number of the phase change heat storage units, wherein the phase change heat storage module comprises at least one phase change heat storage unit; in the case that the pyrolysis temperature interval of the device is less than or equal to a first pyrolysis temperature, integrally casting the phase change heat storage module on the side wall of the hearth of the device; in the case that the pyrolysis temperature interval of the device is greater than or equal to a second pyrolysis temperature, setting the phase change heat storage module on the side wall of the hearth of the device after interface optimization; in the case that the device needs to respond to temperature changes quickly, setting the phase change heat storage module provided with strain absorbing material on the side wall of the hearth of the device.

2. The method of increasing thermal inertia based on a phase change heat storage material according to claim 1, wherein, The step of manufacturing the phase change heat storage material into a phase change heat storage module comprises: melting the phase change heat storage material and placing it in a heat storage container; dispersing the phase change heat storage material into a porous framework in the heat storage container to obtain the phase change heat storage module.

3. The method of increasing thermal inertia based on phase change heat storage material according to claim 2, wherein, The melting temperature is greater than the phase change point of the phase change heat storage material, and the temperature difference between the melting temperature and the phase change point of the phase change heat storage material is 10-30℃.

4. The method of increasing thermal inertia based on a phase change heat storage material according to claim 1, wherein, The phase change heat storage material comprises at least one of nitrate and carbonate.

5. A device for increasing thermal inertia based on a phase change heat storage material, characterized by The device comprises a hearth and a phase change heat storage module, and the phase change heat storage module is installed on the side wall of the hearth, wherein the phase change heat storage module is manufactured from phase change heat storage material, the phase change heat storage material is determined according to the pyrolysis temperature interval of the device, and the phase change point of the phase change heat storage material is within the pyrolysis temperature interval.

6. The device for increasing thermal inertia based on phase change heat storage material according to claim 5, wherein The phase change heat storage module is uniformly distributed along the side wall of the hearth. And / or, the coverage rate of the phase change heat storage module on the side wall of the hearth is greater than or equal to a preset coverage rate threshold.

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