Design method of electric heating furnace for mixed-phase material based on radiation heat transfer

Abstract

The present application relates to the technical field of petroleum chemical industry, and particularly relates to a design method of an electric heating furnace for mixed-phase materials based on radiation heat transfer. The method comprises the following steps: determining an electric heating element, and arranging the electric heating element according to a furnace body structure; selecting a material heating mode, presetting a furnace tube bundle arrangement mode, and calculating a furnace tube surface heat intensity; determining a heat transfer model, and calculating a heat transfer temperature difference according to the heat transfer model; calculating a pipe outer radiation heat transfer coefficient and a pipe inner convection heat transfer coefficient according to the furnace tube surface heat intensity and the heat transfer temperature difference; calculating a heat transfer coefficient according to the pipe outer radiation heat transfer coefficient and the pipe inner convection heat transfer coefficient; calculating a heat transfer area according to the heat transfer coefficient and the heat transfer temperature difference, and arranging the furnace tube bundle according to the furnace body structure; obtaining control parameters of the furnace body structure, determining an oil film temperature, and building a target electric heating furnace in cooperation with the furnace tube bundle arrangement. The method provided by the present application realizes efficient and stable heat transfer, ensures a safe and non-coking material heating process, and improves heat utilization efficiency and production control precision.

Description

Technical Field

[0001] This invention relates to the field of petrochemical technology, and in particular to a design method for an electric heating furnace for mixed-phase materials based on radiation heat transfer. Background Technology

[0002] In the petrochemical industry, heating furnaces are key equipment, and their performance directly affects production efficiency and product quality. Traditional heating furnaces often face problems in heat transfer design, such as unreasonable medium flow velocity within the furnace tubes, unstable flow patterns, and uneven heat load distribution. This leads to low heat transfer efficiency, serious energy waste, and even affects the service life of the furnace tubes, increasing equipment maintenance costs.

[0003] In terms of control design, existing solutions struggle to balance temperature control accuracy and cost, failing to meet the temperature requirements of complex processes, and the safety and reliability of the power supply system also need improvement. Therefore, a design method for an electric heating furnace for mixed-phase materials based on radiative heat transfer is proposed. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] This invention provides a design method for an electric heating furnace for mixed-phase materials based on radiation heat transfer, in order to overcome the problems of coking and scaling that exist in traditional heating methods when processing mixed-phase materials.

[0006] (II) Technical Solution

[0007] To address the above problems, this invention provides a design method for an electric heating furnace for mixed-phase materials based on radiative heat transfer, comprising:

[0008] Step S1: Establish a target electric heating furnace model, pre-set the furnace body structure based on the target electric heating furnace model, determine the electric heating elements based on the furnace body structure, and arrange the electric heating elements according to the furnace body structure;

[0009] Step S2: Select the material heating method according to the furnace structure determined in Step S1, preset the furnace tube bundle arrangement according to the material heating method, and calculate the surface heat intensity of the furnace tubes.

[0010] Step S3: Select the furnace tube bundle according to the furnace body structure determined in step S1, determine the heat transfer model according to the furnace tube bundle, and calculate the heat transfer temperature difference according to the heat transfer model.

[0011] Step S4: Calculate the external radiation heat transfer coefficient based on the surface heat intensity of the furnace tube determined in step S2 and the heat transfer temperature difference determined in step S3, and calculate the internal convection heat transfer coefficient.

[0012] Step S5: Calculate the heat transfer coefficient based on the external radiation heat transfer coefficient and the internal convection heat transfer coefficient determined in step S4, in conjunction with the heat transfer model determined in step S3.

[0013] Step S6: Calculate the heat transfer area based on the heat transfer coefficient determined in Step S5 and the heat transfer temperature difference determined in Step S3, and arrange the furnace tube bundles according to the furnace tube bundle arrangement preset in Step S2.

[0014] Step S7: Obtain the control parameters of the furnace body structure determined in Step S1, determine the oil film temperature based on the surface heat intensity of the furnace tubes determined in Step S2, and construct the target electric heating furnace in conjunction with the furnace tube bundle arrangement determined in Step S6 and the target electric heating furnace model determined in Step S1.

[0015] Preferably, in step S1, the selection factors for the heating element include temperature range, operating environment and life cycle, and the factors for the arrangement of the heating element include voltage level, type, material, power and surface load.

[0016] Preferably, in step S2, the furnace body structure contains heating material, the material is heated by radiation heat transfer, the radiation medium is a radiation gas, and the radiation gas includes CO2, triatomic or polyatomic gas.

[0017] Preferably, in step S2, the formula for calculating the surface thermal intensity of the furnace tube is:

[0018] q=C0[ε(T g / 100) 4 -α(T w / 100) 4 (1)

[0019] Where q is the surface thermal intensity of the furnace tube; ε is the corrected gas emissivity; T g α is the absolute temperature of the gas; α is the gas absorptivity; T w This represents the absolute temperature of the pipe wall.

[0020] Preferably, in step S3, the selection factors for the furnace tube bundle include flow characteristics, heat transfer efficiency, pressure drop, and blockage or corrosion; the heat transfer temperature difference is calculated based on the countercurrent heat transfer temperature difference, and the calculation formula is as follows:

[0021] Δt=(t 〞 -t ˊ ) / ln[(t g -t ˊ ) / (t g -t 〞 (2)

[0022] Where Δt is the heat transfer temperature difference; t g t represents the temperature of the gas inside the furnace. ˊ t represents the inlet temperature of the medium. 〞 This refers to the outlet temperature of the medium.

[0023] Preferably, in step S4, the formula for calculating the external radiation heat transfer coefficient is: α1=q / Δt, where α1 is the external radiation heat transfer coefficient, q is the surface heat intensity of the furnace tube, and Δt is the heat transfer temperature difference; the influencing factors of the internal convective heat transfer coefficient include fluid properties and flow state, wherein the fluid properties include single-phase flow and two-phase flow, and the flow state includes laminar flow, transitional flow, and turbulent flow.

[0024] Preferably, in step S5, the formula for calculating the heat transfer coefficient is:

[0025]

[0026] Where k is the heat transfer coefficient; α1 is the external radiation heat transfer coefficient; λ is the thermal conductivity of the tube; α2 is the internal convection heat transfer coefficient; d o d is the outer diameter of the pipe. i This refers to the inner diameter of the pipe.

[0027] Preferably, in step S6, the calculation formula for the heat transfer model is:

[0028] H=Q / (kΔt) (4)

[0029] Where Q is the heating power; k is the heat transfer coefficient; H is the heat transfer area; and Δt is the heat transfer temperature difference.

[0030] Preferably, in step S6, the furnace tube bundle includes a serpentine reciprocating structure or a spiral coil structure; if the furnace tube bundle is selected as a serpentine reciprocating structure, the furnace tube is selected as a long-radius elbow, and the number of transverse tubes N1, the number of longitudinal tubes N2, and the tube length l are calculated; if the furnace tube bundle is selected as a spiral coil structure, the furnace tube is selected as a coil pitch, and the coil diameter D and the coil length L are calculated.

[0031] Preferably, in step S7, the oil film temperature is lower than the critical temperature at which the heated material begins to coke, and the control parameters include heating power, material outlet temperature, material temperature variation range, and radiant gas temperature variation range.

[0032] (III) Beneficial Effects

[0033] The present invention provides a design method for an electric heating furnace for mixed-phase materials based on radiation heat transfer. By scientifically selecting and rationally arranging electric heating elements, the heating method of the material is determined, effectively achieving efficient and stable heat transfer. The furnace tube bundle design is optimized to adapt to the characteristics of mixed-phase materials, improving the equipment's tolerance to complex media. Parameters such as the surface heat intensity and heat transfer coefficient of the furnace tubes are accurately calculated to determine a reasonable equipment structure and control strategy, ensuring safe and coking-free material heating process, improving heat utilization efficiency and production control accuracy, and providing a high-performance, reliable, and durable heating solution for the petrochemical and refining industries. Attached Figure Description

[0034] Figure 1 This is a flowchart illustrating the design method of an electric heating furnace for mixed-phase materials based on radiation heat transfer, according to an embodiment of the present invention.

[0035] Figure 2 This is a diagram showing the arrangement of the heating elements in an embodiment of the present invention;

[0036] Figure 3 This is a structural diagram of the heating furnace according to an embodiment of the present invention;

[0037] Figure 4 This is a graph showing the temperature changes of the medium and the radiation gas in an embodiment of the present invention. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] Figure 1 This is a flowchart illustrating the design method of an electric heating furnace for mixed-phase materials based on radiative heat transfer, as described in this embodiment of the invention. Figure 1 As shown, this invention provides a design method for an electric heating furnace for mixed-phase materials based on radiative heat transfer, comprising:

[0040] Step S1: Establish a target electric heating furnace model, pre-set the furnace body structure based on the target electric heating furnace model, determine the electric heating elements based on the furnace body structure, and arrange the electric heating elements according to the furnace body structure;

[0041] Step S2: Select the material heating method according to the furnace structure determined in Step S1, preset the furnace tube bundle arrangement according to the material heating method, and calculate the surface heat intensity of the furnace tubes.

[0042] Step S3: Select the furnace tube bundle according to the furnace body structure determined in step S1, determine the heat transfer model according to the furnace tube bundle, and calculate the heat transfer temperature difference according to the heat transfer model.

[0043] Step S4: Calculate the external radiation heat transfer coefficient based on the surface heat intensity of the furnace tube determined in step S2 and the heat transfer temperature difference determined in step S3, and calculate the internal convection heat transfer coefficient.

[0044] Step S5: Calculate the heat transfer coefficient based on the external radiation heat transfer coefficient and the internal convection heat transfer coefficient determined in step S4, in conjunction with the heat transfer model determined in step S3.

[0045] Step S6: Calculate the heat transfer area based on the heat transfer coefficient determined in Step S5 and the heat transfer temperature difference determined in Step S3, and arrange the furnace tube bundles according to the furnace tube bundle arrangement preset in Step S2.

[0046] Step S7: Obtain the control parameters of the furnace body structure determined in Step S1, determine the oil film temperature based on the surface heat intensity of the furnace tubes determined in Step S2, and construct the target electric heating furnace in conjunction with the furnace tube bundle arrangement determined in Step S6 and the target electric heating furnace model determined in Step S1.

[0047] In this design method, in step S1, the selection factors for the heating element include temperature range, working environment and life cycle, and the factors for the arrangement of the heating element include voltage level, type, material, power and surface load.

[0048] In practical applications, in step S2, the furnace body contains heating materials, which are heated by radiation heat transfer. The radiation medium is a radiation gas, including CO2, triatomic or polyatomic gases.

[0049] In this design method, the formula for calculating the surface thermal intensity of the furnace tube in step S2 is:

[0050] q=C0[ε(T g / 100) 4 -α(T w / 100) 4 (1)

[0051] Where q is the surface thermal intensity of the furnace tube; ε is the corrected gas emissivity; T g α is the absolute temperature of the gas; α is the gas absorptivity; T w This represents the absolute temperature of the pipe wall.

[0052] In practical applications, in step S3, the selection factors for the furnace tube bundle include flow characteristics, heat transfer efficiency, pressure drop, and blockage or corrosion; the heat transfer temperature difference is calculated based on the counter-current heat transfer temperature difference, and the calculation formula is as follows:

[0053] Δt=(t 〞 -tˊ ) / ln[(t g -t ˊ ) / (t g -t 〞 (2)

[0054] Where Δt is the heat transfer temperature difference; t g t represents the temperature of the gas inside the furnace. ˊ t represents the inlet temperature of the medium. 〞 This refers to the outlet temperature of the medium.

[0055] In this design method, in step S4, the formula for calculating the external radiation heat transfer coefficient is: α1=q / Δt, where α1 is the external radiation heat transfer coefficient, q is the surface heat intensity of the furnace tube, and Δt is the heat transfer temperature difference; the influencing factors of the internal convective heat transfer coefficient include fluid properties and flow state, where fluid properties include single-phase flow and two-phase flow, and flow state includes laminar flow, transitional flow, and turbulent flow.

[0056] In practical applications, the formula for calculating the heat transfer coefficient in step S5 is:

[0057]

[0058] Where k is the heat transfer coefficient; α1 is the external radiation heat transfer coefficient; λ is the thermal conductivity of the tube; α2 is the internal convection heat transfer coefficient; d o d is the outer diameter of the pipe. i This refers to the inner diameter of the pipe.

[0059] In this design method, the calculation formula for the heat transfer model in step S6 is:

[0060] H=Q / (kΔt) (4)

[0061] Where Q is the heating power; k is the heat transfer coefficient; H is the heat transfer area; and Δt is the heat transfer temperature difference.

[0062] In practical applications, in step S6, the furnace tube bundle includes a serpentine reciprocating structure or a spiral coil structure; if the furnace tube bundle is selected as a serpentine reciprocating structure, the furnace tube is selected as a long radius elbow, and the number of transverse tubes N1, the number of longitudinal tubes N2, and the tube length l are calculated; if the furnace tube bundle is selected as a spiral coil structure, the furnace tube is selected as a coil pitch, and the coil diameter D and the coil length L are calculated.

[0063] In this design method, in step S7, the oil film temperature is less than the critical temperature at which the heated material begins to coke. The control parameters include heating power, material outlet temperature, material temperature variation range, and radiant gas temperature variation range.

[0064] This invention provides a design method for an electric heating furnace for miscible materials based on radiative heat transfer. By scientifically selecting and rationally arranging heating elements, the heating method for the material is determined, effectively achieving efficient and stable heat transfer. The furnace tube bundle design is optimized to adapt to the characteristics of miscible materials, improving the equipment's tolerance to complex media. Precise calculation of parameters such as the surface heat intensity and heat transfer coefficient of the furnace tubes determines a reasonable equipment structure and control strategy, ensuring safe and coking-free material heating, improving heat utilization efficiency and production control accuracy, and providing a high-performance, reliable, and durable heating solution for the petrochemical and refining industries. The working principle of this electric heating furnace design method for miscible materials based on radiative heat transfer is described in detail below:

[0065] Step 1: Establish a model of the target electric heating furnace, pre-set the furnace body structure based on the target electric heating furnace model, determine the heating elements based on the furnace body structure, and arrange the heating elements according to the furnace body structure;

[0066] Step 2: Select the material heating method according to the furnace structure, preset the furnace tube bundle arrangement according to the material heating method, and calculate the surface heat intensity of the furnace tubes;

[0067] Step 3: Select the furnace tube bundle according to the furnace body structure, determine the heat transfer model according to the furnace tube bundle, and calculate the heat transfer temperature difference according to the heat transfer model;

[0068] Step 4: Calculate the external radiation heat transfer coefficient based on the surface heat intensity and heat transfer temperature difference of the furnace tube, and calculate the internal convection heat transfer coefficient.

[0069] Step 5: Calculate the heat transfer coefficient based on the external radiation heat transfer coefficient and the internal convection heat transfer coefficient, in conjunction with the heat transfer model;

[0070] Step 6: Calculate the heat transfer area based on the heat transfer coefficient and heat transfer temperature difference, and arrange the furnace tube bundles according to the preset furnace tube bundle arrangement.

[0071] Step 7: Obtain the control parameters of the furnace body structure, determine the oil film temperature based on the surface heat intensity of the furnace tubes, and build the target electric heating furnace in conjunction with the furnace tube bundle arrangement and the target electric heating furnace model.

[0072] In practical applications, this embodiment mainly includes the selection of heating elements; the arrangement of heating elements; the material heating method; determining the surface heat intensity of the radiant furnace tubes based on the material inlet temperature, outlet temperature, type of radiant gas, radiant gas temperature, and radiant gas pressure; determining the specifications and material of the heat exchange tube bundle based on the material flow rate, velocity, flow pattern, and physical properties; calculating the heat transfer area based on the material heating power, external radiative heat transfer coefficient, internal convective heat transfer coefficient, tube thermal conductivity, and heat transfer temperature difference; determining the structure of the electric heating furnace for mixed-phase materials based on the heat transfer area; calculating the oil film temperature based on the surface heat intensity of the radiant furnace tubes; and determining the control strategy based on the relationship between the material temperature, radiant gas temperature, and heating power. Based on this embodiment, an electric heating furnace using mixed-phase materials as the heating medium is designed to meet the application requirements of hydrogenation and other types of heating furnaces in the petrochemical and refining industries.

[0073] In this embodiment, the heating elements convert electrical energy into heat energy, serving as the heat source for the heating furnace. The selection of heating elements is based on factors such as the operating temperature range, working environment, and lifespan. The arrangement of the heating elements is related to factors such as voltage level, type, material, power, surface load, and furnace structure. The voltage level determines the safe clearance between the heating elements; the main types of heating elements are wire and strip; different materials are suitable for different temperature ranges; power and surface heat load can be used to calculate the number of heating elements used; and the furnace structure determines the arrangement of the heating elements.

[0074] In practical applications, this heating furnace heats materials electrically. However, due to the diverse and complex composition of these materials, direct contact heating with an electric heater can easily lead to coking and scaling. By employing radiative heat transfer, electrical energy is converted into thermal energy, and a radiating gas is used as the intermediate heat exchange medium to reheat the mixed-phase materials, thus preventing coking and scaling. The gas used is a triatomic or polyatomic gas such as CO2 as the radiating medium.

[0075] In this embodiment, based on the heat exchange method of the heating furnace, namely radiant heat exchange, the surface heat intensity of the heat exchange between the radiant gas and the furnace tubes is related to the temperature of the radiant gas, the material inlet temperature, and the material outlet temperature. Simultaneously, the tube bundle arrangement is initially determined, and the type of radiant gas is selected. Based on the temperature, arrangement, and gas type, the surface heat intensity of the furnace tubes is calculated. It should be noted that the surface heat intensity of the radiant furnace tubes is also related to the characteristics of the medium inside the tubes, the flow rate of the medium inside the tubes, and the material of the furnace tubes. Therefore, different media should meet corresponding requirements during heating.

[0076] In practical applications, the medium inside the furnace tube is a mixed-phase material with a gas-liquid two-phase flow, typically consisting of two or more fluids mixed together. The furnace tube design considers flow characteristics, heat transfer efficiency, pressure drop, and the risk of blockage or corrosion. Regarding materials, given the high temperature, high pressure, and corrosive nature of the mixed-phase material, corrosion-resistant materials are selected, and the wall thickness is increased to enhance erosion resistance.

[0077] In this embodiment, during the heating process, electrical energy is converted into thermal energy to heat the furnace wall, furnace top, furnace bottom, and gas inside the furnace. The furnace wall, furnace top, furnace bottom, and gas inside the furnace transfer heat to the outer wall of the furnace tube through radiation heating. The heat from the outer wall of the furnace tube is transferred to the inner wall of the furnace tube through thermal conduction, and then transferred to the medium inside the tube through convection heat transfer.

[0078] In practical applications, since the temperature of the radiant gas inside the furnace remains constant, the heat transfer temperature difference is calculated according to the countercurrent heat transfer temperature difference. The external radiative heat transfer coefficient is calculated based on the surface heat intensity and heat transfer temperature difference of the radiant furnace tube. The internal convective heat transfer coefficient is calculated based on the fluid properties and flow state using the corresponding formula. In conjunction with the heat transfer model, the heat transfer coefficient and heat transfer area are calculated.

[0079] In this embodiment, the furnace tube bundle arrangement is determined based on the heat transfer area, tube diameter, and structural dimensions, combined with the preset furnace tube bundle layout. If the furnace tube bundle adopts a serpentine reciprocating structure, a long-radius bend is selected, and the number of transverse tubes N1, the number of longitudinal tubes N2, and the tube length l are calculated. If the furnace tube bundle adopts a spiral coil structure, the coil pitch is selected, and the coil diameter D and coil length L are calculated.

[0080] In practical applications, one of the main limiting factors for the surface heat intensity of furnace tubes is the critical temperature at which material begins to coke. Controlling the highest oil film temperature within the tube bundle below the critical temperature can prevent coking. The critical temperature is calculated based on the surface heat intensity of the furnace tubes, and it should be lower than the highest oil film temperature.

[0081] In this embodiment, the material outlet temperature is adjusted by the heating power, and the temperature change range of the material and the radiant gas are calculated when the power changes. In practical applications, this method is used in the design of electric heating furnaces for mixed-phase materials. According to this design method, the overall structural layout of the heating furnace matches the site requirements; the surface load of the electric heating elements ensures the safety, stability, and long-term operation of the heating; the calculation of the surface heat load and oil film temperature of the furnace tubes ensures that the material does not coke and the tube bundle is safe; the application of CO2 radiant gas can improve heat exchange performance and achieve zero contact between the material and oxygen, resulting in high explosion-proof performance; the selection of long-radius elbows can adapt to complex media inside the tubes and improve light transmission, allowing the material inside the tube bundle to receive more heat and improving heat utilization; the algorithm design of heating power and heating temperature improves the control accuracy.

[0082] In practical applications, CO2 is used as the radiant gas inside the furnace. Firstly, CO2 has strong radiant properties, and industrial CO2 sources are widespread and stable. Secondly, CO2 acts as a slightly positive pressure, closed-loop heating medium within the furnace, preventing oxygen from contacting flammable and explosive media should leak from the materials inside the tubes, thus improving explosion-proof performance. Furthermore, the heating elements are made of high-temperature grade materials, suitable for radiant heating furnaces requiring precise temperature control and long-term stable operation. The heating elements are in the form of heating tapes, which can meet higher surface load requirements compared to wire.

[0083] In this embodiment, as Figure 2 As shown, the heating material is mixed hydrogen oil, the heating power is 5000kW, and the heating elements are divided into three phases: A, B, and C. Each phase has eight sets of heating tapes connected in parallel, namely A1~A8, B1~B8, and C1~C8. The heating tape is 25mm wide, 2mm thick, and has a maximum operating temperature of 1300℃. The surface load can meet the requirements of actual use.

[0084] In practical applications, the radiant gas temperature is designed to be between 800 and 1200℃. Within the safe operating range, the surface heat intensity of the furnace tubes is low when the radiant gas temperature is low, resulting in an increase in the structural dimensions of the heating furnace. Specifically, when the radiant gas temperature of this heating furnace is designed to be 1030℃, the material inlet temperature to be 230℃, and the outlet temperature to be 400℃, the surface heat intensity of the furnace tubes is 26.3 kW / m². 2 At this point, the highest oil film temperature of the material is 428℃, which is lower than the critical temperature of 482℃ at which the material begins to coke, thus meeting the operating requirements.

[0085] In this embodiment, for gas-liquid two-phase flow materials, a small pipe diameter can increase the heat transfer area, but it results in a large pressure drop, making it unsuitable for miscible materials. A large pipe diameter can reduce the pressure drop. By controlling the flow rate or mass flow rate, heat transfer efficiency and pressure drop can be balanced, and turbulence-induced phase separation or vibration can be avoided. The pipe specification is designed as DN100 based on the flow rate, suitable for miscible materials. Under rated operating conditions, the medium inside the pipe is in an annular mist flow pattern, ensuring heat transfer. The material is corrosion-resistant stainless steel.

[0086] In practical applications, the heat transfer temperature difference is: Δt = (t 〞 -t ˊ ) / ln[(t g -t ˊ ) / (t g -t 〞 )]=711.6℃;

[0087] The external radiative heat transfer coefficient is: α1 = 36.9 W / (m²). 2 ℃);

[0088] It should be noted that the material inside the heating furnace tube is a mixed phase, and the heat transfer coefficient of the two-phase fluid is calculated by multiplying the mass percentage of each phase fluid by the corresponding heat transfer coefficient.

[0089] In this embodiment, the convective heat transfer coefficient inside the tube is: α2 = 1095.9 W / (m²). 2 ℃);

[0090] The heat transfer coefficient is:

[0091] Furthermore, the heat transfer area is: H = Q / (kΔt) = 5000 / (35.1 / 1000 × 711.6) = 200.2 m² 2 .

[0092] In practical applications, such as Figure 3 As shown, the heat transfer area is distributed among 84 tubes. Based on the heat exchange characteristics and the size of the heating furnace, the number of transverse tubes N1 = 3, the number of longitudinal tubes N2 = 28, and the effective tube length l = 6660mm.

[0093] In this embodiment, as Figure 4 As shown, two high-voltage power control cabinets are used as electrical control equipment for the heating furnace. The temperature control of the hydrogenation radiation furnace is achieved through the heating module and power control. The heating furnace power changes by 27kW, the gas temperature changes by 2-4℃, and the material heating temperature changes by 1℃, thus precisely controlling the outlet temperature.

[0094] In practical applications, the structure of this embodiment is highly adaptable. The tube bundle arrangement is determined based on the heat transfer area, tube diameter and structural dimensions, so that the overall structure of the heating furnace can be highly matched with the site requirements. It can be flexibly applied to different working conditions and scenarios, and meet the diverse application requirements of hydrogenation and other types of heating furnaces in the petrochemical and refining fields.

[0095] In this embodiment, the heating is safe and stable. The selection and arrangement of the heating elements take into account various factors such as the operating temperature range, working environment, life cycle, and voltage level. This allows for the precise determination of the specifications and quantity of the heating elements, ensuring that the surface load of the heating elements is within a reasonable range. This, in turn, ensures the safety, stability, and long-term sustainability of the heating process and reduces the risk of equipment failure.

[0096] In practical applications, this embodiment exhibits excellent anti-coking performance. It employs radiative heat transfer, using triatomic or polyatomic gases such as CO2 as the radiant medium, avoiding direct contact between the electric heater and the material. This effectively prevents coking and scaling during the heating process. By calculating the surface heat intensity of the radiant furnace tubes, the oil film temperature is controlled, keeping the highest oil film temperature within the tube bundle below the critical temperature for material coking. This further ensures material heating safety, extends equipment lifespan, and reduces maintenance costs.

[0097] In this embodiment, the heat exchange performance is excellent. Using CO2 as the radiating gas, its excellent radiation characteristics enhance heat exchange performance. The unique heat transfer design, through accurate calculation of the external radiative heat transfer coefficient, the internal convective heat transfer coefficient, the heat transfer coefficient, and the heat transfer area, achieves efficient heat transfer and improves heating efficiency. Simultaneously, zero contact between the material and oxygen greatly improves the equipment's explosion-proof performance, making it suitable for hazardous operating environments such as petrochemical and refining plants where safety requirements are extremely high.

[0098] In practical applications, this embodiment exhibits good media adaptability. The furnace tube bundle is designed specifically for the characteristics of mixed-phase materials, using corrosion-resistant materials and a thickened wall design to enhance the erosion resistance of the tube bundle. It can adapt to high-temperature, high-pressure, and corrosive mixed-phase materials. The serpentine reciprocating structure uses long-radius elbows, which can adapt to complex media flow inside the tube, improve light transmission, allow the material to receive more heat, improve heat utilization efficiency, and ensure uniform heating of the material.

[0099] In this embodiment, the control is precise and efficient. By accurately calculating the relationship between material temperature, radiant gas temperature and heating power, the control strategy is determined. The material outlet temperature can be precisely adjusted, and the temperature change range of material and radiant gas when the power changes can be accurately grasped. This achieves precise control of the heating process and improves the stability of the production process and product quality.

[0100] The above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also fall within the scope of the present invention, and the patent protection scope of the present invention should be defined by the claims.

Claims

1. A design method for an electric heating furnace for mixed-phase materials based on radiative heat transfer, characterized in that, include: Step S1: Establish a target electric heating furnace model, pre-set the furnace body structure based on the target electric heating furnace model, determine the electric heating elements based on the furnace body structure, and arrange the electric heating elements according to the furnace body structure; Step S2: Select the material heating method according to the furnace structure determined in Step S1, preset the furnace tube bundle arrangement according to the material heating method, and calculate the surface heat intensity of the furnace tubes. Step S3: Select the furnace tube bundle according to the furnace body structure determined in step S1, determine the heat transfer model according to the furnace tube bundle, and calculate the heat transfer temperature difference according to the heat transfer model. Step S4: Calculate the external radiation heat transfer coefficient based on the surface heat intensity of the furnace tube determined in step S2 and the heat transfer temperature difference determined in step S3, and calculate the internal convection heat transfer coefficient. Step S5: Calculate the heat transfer coefficient based on the external radiation heat transfer coefficient and the internal convection heat transfer coefficient determined in step S4, in conjunction with the heat transfer model determined in step S3. Step S6: Calculate the heat transfer area based on the heat transfer coefficient determined in Step S5 and the heat transfer temperature difference determined in Step S3, and arrange the furnace tube bundles according to the furnace tube bundle arrangement preset in Step S2. Step S7: Obtain the control parameters of the furnace body structure determined in Step S1, determine the oil film temperature based on the surface heat intensity of the furnace tubes determined in Step S2, and construct the target electric heating furnace in conjunction with the furnace tube bundle arrangement determined in Step S6 and the target electric heating furnace model determined in Step S1.

2. The design method for an electric heating furnace for mixed-phase materials based on radiative heat transfer according to claim 1, characterized in that, In step S1, the selection factors for the heating element include temperature range, working environment and life cycle, and the factors for the arrangement of the heating element include voltage level, type, material, power and surface load.

3. The design method for an electric heating furnace for mixed-phase materials based on radiative heat transfer according to claim 1, characterized in that, In step S2, the furnace body structure contains heating material, the material is heated by radiation heat transfer, the radiation medium is a radiation gas, and the radiation gas includes CO2, triatomic or polyatomic gas.

4. The design method for an electric heating furnace for mixed-phase materials based on radiative heat transfer according to claim 1, characterized in that, In step S2, the formula for calculating the surface thermal intensity of the furnace tube is: q=C0[ε(T g / 100) 4 -α(T w / 100) 4 ] (1) Where q is the surface thermal intensity of the furnace tube; ε is the corrected gas emissivity; T g α is the absolute temperature of the gas; α is the gas absorptivity; T w This represents the absolute temperature of the pipe wall.

5. The design method for an electric heating furnace for mixed-phase materials based on radiative heat transfer according to claim 1, characterized in that, In step S3, the selection factors for the furnace tube bundle include flow characteristics, heat transfer efficiency, pressure drop, and blockage or corrosion; the heat transfer temperature difference is calculated based on the counter-current heat transfer temperature difference, and the calculation formula is as follows: Δt=(t 〞 -t ˊ ) / ln[(t g -t ˊ ) / (t g -t 〞 )] (2) Where Δt is the heat transfer temperature difference; t g t represents the temperature of the gas inside the furnace. ˊ t represents the inlet temperature of the medium. 〞 This refers to the outlet temperature of the medium.

6. The design method for an electric heating furnace for mixed-phase materials based on radiative heat transfer according to claim 1, characterized in that, In step S4, the formula for calculating the external radiation heat transfer coefficient is: α1=q / Δt, where α1 is the external radiation heat transfer coefficient, q is the surface heat intensity of the furnace tube, and Δt is the heat transfer temperature difference; the influencing factors of the internal convective heat transfer coefficient include fluid properties and flow state, where fluid properties include single-phase flow and two-phase flow, and flow state includes laminar flow, transitional flow, and turbulent flow.

7. The design method for an electric heating furnace for mixed-phase materials based on radiative heat transfer according to claim 1, characterized in that, In step S5, the formula for calculating the heat transfer coefficient is: Where k is the heat transfer coefficient; α1 is the external radiation heat transfer coefficient; λ is the thermal conductivity of the tube; α2 is the internal convection heat transfer coefficient; d o d is the outer diameter of the pipe. i This refers to the inner diameter of the pipe.

8. The design method for an electric heating furnace for mixed-phase materials based on radiative heat transfer according to claim 1, characterized in that, In step S6, the calculation formula for the heat transfer model is: H=Q / (kΔt) (4) Where Q is the heating power; k is the heat transfer coefficient; H is the heat transfer area; and Δt is the heat transfer temperature difference.

9. The design method for an electric heating furnace for mixed-phase materials based on radiative heat transfer according to claim 1, characterized in that, In step S6, the furnace tube bundle includes a serpentine reciprocating structure or a spiral coil structure; if the furnace tube bundle is selected as a serpentine reciprocating structure, the furnace tube is selected as a long radius elbow, and the number of transverse tubes N1, the number of longitudinal tubes N2, and the tube length l are calculated; if the furnace tube bundle is selected as a spiral coil structure, the furnace tube is selected as a coil pitch, and the coil diameter D and the coil length L are calculated.

10. The design method for an electric heating furnace for mixed-phase materials based on radiative heat transfer according to claim 3, characterized in that, In step S7, the oil film temperature is lower than the critical temperature at which the heated material begins to coke, and the control parameters include heating power, material outlet temperature, material temperature variation range, and radiant gas temperature variation range.

Images