A furfural tubular reactor and design method thereof

Abstract

The invention discloses a furfural tubular reactor and a design method thereof. The furfural tubular reactor comprises a reaction tube body, wherein a steam inlet is arranged at one end of the reaction tube body, a material outlet is arranged at the other end, and a material inlet is arranged on a side wall of the reaction tube body close to the steam inlet; the reaction tube body is divided into a material accelerated heating zone and a material uniform heating zone from bottom to top, and the material uniform heating zone is divided into a uniform heating first stage, a uniform heating second stage, a uniform heating reaction stage, and an isothermal uniform reaction stage from bottom to top; the invention adopts a tubular reactor as a reaction device for producing furfural, and the device has the advantages of high production capacity, continuous production, and short reaction time. At the same time, the height of each section is obtained according to theoretical calculation, and the total height of the tubular reactor is finally obtained. Under the condition of ensuring that the reaction can be completely carried out, the production cost of the tubular reactor is reduced and the production efficiency of furfural is improved.

Description

Technical Field

[0001] The invention relates to the technical field of furfural preparation, and in particular to a furfural tubular reactor and a design method thereof. Background Art

[0002] Furfural is an organic compound, a colorless, transparent, oily liquid with a special smell similar to benzaldehyde. It is mainly used as an industrial solvent and can also be used to produce furfuryl alcohol, furoic acid, tetrahydrofuran, γ-valerolactone, pyrrole, tetrahydropyrrole, etc. Furfural is mainly produced from agricultural and forestry waste. Since agricultural and forestry waste contains a large amount of hemicellulose, hemicellulose is formed into furfural through hydrolysis, dehydration and cyclization.

[0003] The production of furfural in industry mainly uses batch or continuous reactors. After acid-treated hemicellulose is passed through saturated steam or superheated steam, the hemicellulose is partially hydrolyzed into xylose. The xylose generated by hydrolysis then undergoes a dehydration cyclization reaction to ultimately produce furfural. Depending on whether the hydrolysis reaction and dehydration cyclization reaction are carried out in the same reactor, the furfural synthesis process can be divided into a one-step process and a two-step process. In the two-step furfural preparation process, the commonly used reactor is a tubular reactor. The inventors have found that the chemical reaction rate and reactant concentration at any position in the tubular reactor vary only with the length of the tube, not with time. However, in the existing two-step process for preparing furfural, the height of the tubular reactor is usually not considered when selecting the tubular reactor. When the height of the tubular reactor is too high, it occupies a large space, increasing the cost. When the height of the tubular reactor is too low, the reaction process cannot be fully carried out, resulting in a low furfural preparation efficiency. Summary of the Invention

[0004] In response to the problems existing in the prior art, the present invention provides a furfural tubular reactor and a design method thereof. The internal structure of the tubular reactor is divided into different sections, and the height of each section is obtained according to theoretical calculations, and finally the total height of the tubular reactor is obtained. While ensuring that the reaction can be carried out completely, the production cost of the tubular reactor is reduced.

[0005] The technical solutions of the present invention are as follows:

[0006] In a first aspect of the present invention, a furfural tubular reactor is provided, comprising a reaction tube body, wherein a steam inlet is provided at one end of the reaction tube body, a material outlet is provided at the other end, and a material inlet is provided on a side wall of the reaction tube body close to the steam inlet; the reaction tube body is divided into a material accelerated heating zone and a material uniform heating zone from bottom to top, and the material uniform heating zone is divided into a uniform heating stage 1, a uniform heating stage 2, a uniform heating reaction stage, and an isothermal uniform reaction stage from bottom to top.

[0007] In some embodiments of the present invention, the steam inlet is connected to a steam pipe via a blower, the material outlet is connected to a cyclone separator, and the material inlet is connected to a material conveying device.

[0008] In a second aspect of the present invention, a method for designing a furfural tubular reactor is provided, comprising the following steps:

[0009] (1) Calculate the steam flow rate and reactor diameter based on the heating temperature, residence time, and material parameters required for the material reaction;

[0010] (2) Assume that the material is heated to T after passing through the material acceleration heating zone. m1 , according to the temperature T m1 Perform constant heat calculation to obtain the average steam temperature in the material accelerated heating zone;

[0011] (3) Calculate the Reynolds number of the material passing through the material acceleration heating zone, and calculate the height of the material acceleration heating zone based on the Reynolds number;

[0012] (4) Repeat steps (2)-(3) to calculate the heights of the uniform heating stage 1, the uniform heating stage 2, the uniform heating reaction stage, and the isothermal uniform reaction stage in sequence;

[0013] (5) Calculate the total height of the furfural tubular reactor and round it up.

[0014] In some embodiments of the present invention, in step (1), the flow rate of the steam is calculated according to the energy conservation formula:

[0015]

[0016] Where, is the material handling capacity; is the specific heat capacity of water; is the specific heat capacity of the material; is the material outlet temperature; is the material inlet temperature; L is the steam flow rate; is the inlet steam specific enthalpy; is the outlet steam specific enthalpy.

[0017] In some embodiments of the present invention, in step (1), the diameter of the reactor is calculated according to the following formula:

[0018]

[0019] Where, L is the steam flow rate; is the specific volume of the inlet steam; D is the reactor diameter; is the inlet steam velocity.

[0020] In some embodiments of the present invention, in step (2), the physical properties of the water vapor are queried based on the obtained average steam temperature of the material, and the physical properties include specific volume, dynamic viscosity and thermal conductivity.

[0021] In some embodiments of the present invention, in step (3), the Reynolds number is calculated based on the physical parameters of the water vapor, and the Reynolds number includes the initial Reynolds number and the sedimentation Reynolds number.

[0022] In some embodiments of the present invention, in step (3), the volume heat transfer coefficient in the region is calculated based on the sedimentation Reynolds number, and then the height of the reactor in the region is obtained according to the following formula:

[0023]

[0024] Where Q is the heat transfer capacity of the reactor in this area, is the volume heat transfer coefficient, D is the diameter of the reactor, H is the height of the reactor in this area, is the steam temperature difference in this area.

[0025] In some embodiments of the present invention, the height of the isothermal uniform velocity stage is used to meet the residence time of the particles passing through the uniform velocity reaction zone.

[0026] In some embodiments of the present invention, in step (4), the Reynolds number calculation in the calculation process of each height of the uniform heating stage 1, the uniform heating stage 2, the uniform heating reaction stage, and the isothermal uniform reaction stage only includes the sedimentation Reynolds number calculation.

[0027] One or more technical solutions of the present invention have the following beneficial effects:

[0028] (1) The present invention uses a tubular reactor as a reaction device for producing furfural. This device has the advantages of high production capacity, continuous production, and short reaction time. The raw materials are fed horizontally into the vertical tubular reactor by a feeder, and superheated steam is introduced from below to heat the raw materials, complete the reaction, and transport them. A cyclone separator is connected to the outlet of the tubular reactor to separate the reaction solid residue and steam. After separation, the aldehyde gas enters the next process for furfural purification, which facilitates the scale-up design of industrial production.

[0029] (2) The design method of the tubular reactor provided by the present invention divides the interior of the reaction tube body into a material accelerated heating zone and a material uniform heating zone according to the characteristics of the heating and reaction of the material and steam in the tube, and further divides the material uniform heating zone into a uniform heating stage 1, a uniform heating stage 2, a uniform heating reaction stage, and an isothermal uniform reaction stage. The height of each section is obtained according to theoretical calculation, and the total height of the tubular reactor is finally obtained. Under the condition of ensuring that the reaction can be carried out completely, the production cost of the tubular reactor is reduced and the production efficiency of furfural is improved.

[0030] (3) The furfural production process provided by the present invention adopts a one-step process, wherein the hydrolysis reaction is carried out in a tubular reactor. By limiting the reaction temperature to 220-250°C and the residence time to 5-120s, the reaction rate is improved. Since the material is heated at a high speed and reaches the reaction temperature quickly, in order to ensure the reaction time, an isothermal and uniform reaction stage is designed in the uniform reaction zone, so that the gas and raw material temperatures are maintained at 250°C at the end of the heating section, and the pressure of the reactor should be maintained at 3.98MPa (saturated vapor pressure at 250°C), thereby preventing the raw material moisture from being evaporated during the isothermal and uniform reaction stage. In addition, the use of superheated steam at 250°C can prevent the superheated steam from condensing, thereby increasing the furfural yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the process flow chart for furfural production;

[0032] Figure 2 Schematic diagram of the structure of the furfural tubular reactor of the present invention.

[0033] In the figure: 1. Reaction tube body; 101. Steam inlet; 102. Material inlet; 103. Material outlet; 104. Insulation cotton; 2. Cyclone separator; 201. Gas outlet; 202. Solid outlet; 3. Blower; 4. Valve. DETAILED DESCRIPTION

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0035] Example 1

[0036] A furfural production process, such as Figure 1 As shown, the process involves conveying pretreated material into a tubular reactor. Simultaneously, superheated steam enters the tubular reactor under the action of a blower. The material then passes through the material acceleration heating zone and the material uniform heating zone, where it undergoes a hydrolysis reaction with the steam to produce furfural. The furfural then enters a cyclone separator to separate the solid residue from the gas, which then enters the next step for furfural purification. The reaction temperature is 220-250°C, and the reaction residence time is 5-120 seconds.

[0037] In a typical embodiment of the present invention, based on the above furfural production process, a furfural tubular reactor is proposed, such as Figure 1 As shown, it includes a reaction tube body 1, a steam inlet 101 is provided at one end of the reaction tube body, and a material outlet 103 is provided at the other end. A material inlet 102 is provided on the side wall of the reaction tube body 1 near the steam inlet 101; the reaction tube body 1 is divided into a material accelerated heating zone and a material uniform heating zone from bottom to top, and the material uniform heating zone is divided into a uniform heating stage 1, a uniform heating stage 2, a uniform heating reaction stage, and an isothermal uniform reaction stage from bottom to top, wherein the temperature of the material particles in the material uniform heating zone is lower than 220°C. At this time, the steam only heats the material, and the material and steam do not react. The temperature of the particles in the material uniform heating reaction zone is 220-250°C, and the particles react to produce furfural. The temperature of the particles in the uniform reaction zone is maintained at 250°C and only reacts.

[0038] Furthermore, the steam inlet 101 is connected to the steam pipe through the blower 3. A steam valve 4 is also provided at the steam inlet 101 for adjusting the amount of steam entering the reaction tube body 1. The material outlet 103 is connected to the cyclone separator 2, and the material inlet 102 is connected to the material conveying device.

[0039] In order to reduce the heat loss generated by the tubular reactor, a heat-insulating layer 104 is provided on the outer surface of the tubular reactor to improve the heat utilization rate.

[0040] The working principle of the furfural tubular reactor provided in this embodiment is as follows: the pretreated material is transported to the tubular reactor. At the same time, superheated steam enters the tubular reactor under the action of a blower, and passes through the material acceleration heating zone and the material uniform heating zone of the tubular reactor in sequence. In the tubular reactor, the material and steam undergo a hydrolysis reaction to produce furfural; the furfural enters the cyclone separator to separate the reaction solid residue and gas, and the gas enters the next process for furfural purification.

[0041] Example 2

[0042] In a typical embodiment of the present invention, a design method of a furfural tubular reactor is proposed, comprising the following steps:

[0043] (1) Calculate the steam flow rate and reactor diameter based on the heating temperature, residence time, and material parameters required for the material reaction;

[0044] (2) Assume that the material is heated to T after passing through the material acceleration heating zone. m1 , according to the temperature T m1 Perform constant heat calculation to obtain the average steam temperature in the material accelerated heating zone;

[0045] (3) Calculate the Reynolds number of the material passing through the material acceleration heating zone, and calculate the height of the material acceleration heating zone based on the Reynolds number;

[0046] (4) Repeat steps (2)-(3) to calculate the heights of the uniform heating stage 1, the uniform heating stage 2, the uniform heating reaction stage, and the isothermal uniform reaction stage in sequence;

[0047] (5) Calculate the total height of the furfural tubular reactor and round it up.

[0048] Furthermore, in step (1), the flow rate of the steam is calculated according to the energy conservation formula:

[0049]

[0050] Where, is the material handling capacity; is the specific heat capacity of water; is the specific heat capacity of the material; is the material outlet temperature; is the material inlet temperature; L is the steam flow rate; is the inlet steam specific enthalpy; is the outlet steam specific enthalpy.

[0051] Furthermore, in step (1), the diameter of the reactor is calculated according to the following formula:

[0052]

[0053] Where, L is the steam flow rate; is the specific volume of the inlet steam; D is the reactor diameter; is the inlet steam velocity.

[0054] Furthermore, in step (2), the physical properties of the water vapor are queried based on the obtained average steam temperature of the material, and the physical properties include specific volume, dynamic viscosity and thermal conductivity.

[0055] Furthermore, the Reynolds number in step (3) includes the initial Reynolds number and the sedimentation Reynolds number.

[0056] Furthermore, the height of the isothermal uniform reaction stage is used to meet the residence time of the particles passing through the uniform reaction zone.

[0057] Below in conjunction with specific embodiment, the design method of furfural tubular reactor is described in detail:

[0058] The height of the furfural tubular reactor should meet the following two conditions:

[0059] (1) The material should be heated to 220-250℃ within the designed height of the reactor;

[0060] (2) The material should stay at 220-250℃ for 5-120s.

[0061] Because the material heats up quickly and reaches the reaction temperature quickly, an isothermal, uniform-rate reaction stage is required to ensure reaction time. Therefore, at the end of the heating stage, the gas and feedstock temperature should be 250°C, and the reactor pressure should be maintained at 3.98 MPa (saturated vapor pressure at 250°C) to prevent the feedstock from evaporating during the isothermal, uniform-rate reaction stage. Furthermore, using superheated steam at 250°C prevents condensation and maximizes furfural yield.

[0062] Taking dry wood as an example, the design conditions are:

[0063] Dry wood processing capacity: G0 = 60kg / h; reaction temperature: 220-250℃; residence time: 10s; working pressure: p = 3.98Mpa; design pressure: p* = 4.77MPa (take 1.2 times the safety factor); superheated steam temperature: T gr =300℃.

[0064] Make the following assumptions:

[0065] (1) To simplify the calculation, the reaction heat and pipeline heat loss are not considered in the design process, and only the heat required to heat the material to the corresponding temperature is considered;

[0066] (2) The reaction particles are spherical and of uniform size;

[0067] (3) In the drying tube, the particles are dispersed and suspended in the air flow without any mutual adhesion;

[0068] (4) During the design process, the design pressure has a greater impact on the reactor wall thickness. Therefore, the wall thickness is calculated according to the design pressure, and the reactor height is calculated according to the working pressure. In order to reduce the impact, the reactor tube height is adjusted upward.

[0069] Material parameters can be found in the relevant manual: Material density: ;

[0070] Specific heat capacity of material: C m =2.5kJ / (kg·℃)

[0071] Particle diameter:

[0072] Specific heat capacity of water: C s =4.2kJ / (kg·℃).

[0073] The superheated steam flow calculation process is as follows:

[0074] Known superheated steam inlet temperature: T gr =300℃, superheated steam outlet temperature: T gc =250℃, material outlet temperature: T mc =250℃;

[0075] Assume that the inlet temperature of the heated material is: T mr =70℃

[0076] The physical parameters of water vapor are as follows: p = 3.98 MPa, superheated steam specific enthalpy H at T = 300 ° C 300 =2962KJ / Kg; p=3.98MPa, T=250℃ superheated steam specific enthalpy H 250 = 2801KJ / Kg

[0077] Then the energy conservation formula is:

[0078]

[0079] Therefore, the gas flow rate L is:

[0080]

[0081]

[0082] The diameter of the tubular reactor is calculated as follows:

[0083] Assume the inlet gas velocity is , and the specific volume of superheated steam at p = 3.98 MPa and T = 300 ° C

[0084] Then the diameter should satisfy the following equation:

[0085]

[0086] So the diameter D is: D=0.099m, rounded up to 0.1m.

[0087] 1. The calculation process of the height H1 of the material accelerated heating zone is as follows:

[0088] (1) Constant heat calculation

[0089] Suppose this piece of wood is heated to ,

[0090] The energy required is:

[0091]

[0092]

[0093] Steam provides energy for:

[0094]

[0095] Depend on The steam specific enthalpy at the end of this section is for:

[0096]

[0097]

[0098] Check the water vapor physical parameter table to get the gas temperature at the end of this section =287.5℃,

[0099] The average gas temperature in this section is

[0100]

[0101]

[0102] Check water vapor T=293.75 、Physical properties of p=3.98MPa:

[0103] specific volume

[0104] Dynamic viscosity

[0105] Thermal conductivity

[0106] (2) Reynolds number calculation

[0107] The average air velocity in this section is:

[0108]

[0109]

[0110] So the initial Reynolds number for:

[0111]

[0112]

[0113]

[0114] in is the particle velocity and ;

[0115] because It is the transition zone, and its heat calculation formula is as follows:

[0116]

[0117]

[0118] QB and QK are coefficients, which can be obtained by looking up the chart. For the convenience of calculation, the following two formulas are used here to solve:

[0119]

[0120]

[0121] in is the Reynolds number at the inlet, is the Reynolds number when the particles are settling, i.e. at a constant velocity; is the Nusselt number at the entrance, is the Nusselt number of the particle during sedimentation.

[0122] Assume that the Reynolds number during sedimentation is ,but

[0123]

[0124]

[0125] because ,but

[0126]

[0127]

[0128] Therefore ,

[0129] The temperature difference in this section

[0130]

[0131]

[0132] This section of Archimedean number

[0133]

[0134]

[0135]

[0136] Assumptions but ,

[0137] so

[0138] Depend on The particle velocity at the outlet for:

[0139]

[0140]

[0141] So the relative speed for:

[0142]

[0143] ,

[0144] (3) Calculation of the height H1 of the material accelerated heating zone

[0145] According to the above calculation, this section , Start to , At the end, since the Re values ​​are all in the transition zone, the calculation of the reactor height H1 should be based on the transition section formula, which is as follows:

[0146]

[0147]

[0148] 2. The calculation process of the height H2 of the first stage of uniform heating is as follows:

[0149] Because of the previous stage ,and , the reaction is considered to have entered the uniform speed stage; and the diameter of the uniform speed heating section is equal to the diameter of the accelerated heating zone.

[0150] (1) Constant heat calculation

[0151] Suppose this piece of wood is heated to ,

[0152] The energy required is:

[0153]

[0154]

[0155] Steam provides energy for:

[0156]

[0157] Depend on The specific enthalpy of steam at the end of this section is:

[0158]

[0159]

[0160] Check the physical parameter table of water vapor to get the steam temperature at the end of this section =272.96℃,

[0161] The average gas temperature in this section is

[0162]

[0163]

[0164] Check water vapor T=280.23 、Physical properties of p=3.98MPa:

[0165] specific volume

[0166] Dynamic viscosity

[0167] Thermal conductivity

[0168] (2) Reynolds number calculation

[0169] Sedimentation velocity :

[0170]

[0171]

[0172] Due to the assumption Located in the transition zone, the resistance coefficient between the particles and the airflow is ε

[0173]

[0174]

[0175] so

[0176] Therefore, the actual sedimentation Reynolds number is:

[0177]

[0178]

[0179] Due to the assumption actual ,and , which indicates that the hypothesis is established;

[0180] The average air velocity in this section is:

[0181]

[0182]

[0183] Therefore for:

[0184]

[0185]

[0186] (3) Calculation of the height of H2 during the first stage of uniform heating

[0187] Calculation of heat transfer area A:

[0188]

[0189]

[0190] Since it is in the constant velocity section, the heat transfer coefficient correlation can be calculated using formula 32:

[0191]

[0192] Therefore, the heat transfer coefficient for:

[0193]

[0194]

[0195] The volume heat transfer coefficient for:

[0196]

[0197]

[0198] Therefore, the heat transfer capacity Q of this section of the reactor is:

[0199]

[0200] The temperature difference in this section is:

[0201]

[0202]

[0203] Depend on The height of this section of the reactor is:

[0204]

[0205] Therefore, the sum of the heights of the accelerated heating zone H1 and the uniform heating stage H2 is:

[0206]

[0207]

[0208] 3. The calculation process of the height H3 of the second stage of uniform heating is as follows:

[0209] (1) Constant heat calculation

[0210] Suppose this piece of wood is heated to ,

[0211] The energy required is:

[0212]

[0213]

[0214] Steam provides energy for:

[0215]

[0216] Depend on The specific enthalpy of steam at the end of this section is:

[0217]

[0218]

[0219] Check the physical parameter table of water vapor to get the steam temperature at the end of this section =257.184℃,

[0220] The average gas temperature in this section is

[0221]

[0222]

[0223] Check water vapor T= 、Physical properties of p=3.98MPa:

[0224] specific volume

[0225] Dynamic viscosity

[0226] Thermal conductivity .

[0227] (2) Reynolds number calculation

[0228] Sedimentation velocity :

[0229]

[0230]

[0231] Because of the previous stage Located in the transition zone, so

[0232]

[0233]

[0234] so

[0235] so for:

[0236]

[0237]

[0238] The average air velocity in this section is:

[0239]

[0240]

[0241] Therefore for:

[0242]

[0243]

[0244] (3) Calculation of the height H3 of the second stage of uniform heating

[0245] Calculation of heat transfer area A:

[0246]

[0247]

[0248] Since in the constant velocity motion section, the heat transfer coefficient correlation can be used

[0249]

[0250] Therefore, the heat transfer coefficient for:

[0251]

[0252]

[0253] The volume heat transfer coefficient for:

[0254]

[0255]

[0256] Therefore, the heat transfer capacity of this section of the reactor is:

[0257]

[0258] The temperature difference in this section is:

[0259]

[0260]

[0261] Depend on The height H3 of the second stage of uniform heating is:

[0262]

[0263] Therefore, the total height of the material accelerated heating zone H1, the uniform heating stage 1 H2, and the uniform heating stage 2 H3 is:

[0264]

[0265]

[0266] 4. The height calculation process of the uniform heating reaction stage H4 is as follows:

[0267] (1) Constant heat calculation

[0268] Assume that this section of material is heated to ,

[0269] The energy required is:

[0270]

[0271]

[0272] Steam provides energy for:

[0273]

[0274] Depend on The specific enthalpy of steam at the end of this section is:

[0275]

[0276]

[0277] Check the physical parameter table of water vapor to get the steam temperature at the end of this section =250.15℃, which is close to the initial analysis temperature, so the calculation is correct;

[0278] The average gas temperature in this section is

[0279]

[0280]

[0281] Check water vapor T= 、Physical properties of p=3.98MPa:

[0282] specific volume

[0283] Dynamic viscosity

[0284] Thermal conductivity

[0285] (2) Reynolds number calculation

[0286] Sedimentation velocity :

[0287]

[0288]

[0289] Because of the previous stage Located in the transition zone, so

[0290]

[0291]

[0292] so

[0293] so

[0294]

[0295]

[0296] The average air velocity in this section is:

[0297]

[0298]

[0299] Therefore for:

[0300]

[0301]

[0302] (3) The height H4 of the second stage of uniform heating is calculated as follows:

[0303] Calculation of heat transfer area A:

[0304]

[0305]

[0306] Since in the constant velocity motion section, the heat transfer coefficient correlation can be used

[0307]

[0308] Therefore, the heat transfer coefficient for:

[0309]

[0310]

[0311] The volume heat transfer coefficient for:

[0312]

[0313]

[0314] Therefore, the heat transfer capacity of this section of the reactor is:

[0315]

[0316] in

[0317]

[0318]

[0319] Depend on The height H4 of the uniform heating reaction stage is:

[0320]

[0321] Therefore, the height sum of the material accelerated heating zone H1, uniform heating stage 1 H2, uniform heating stage 2 H3, and uniform heating reaction stage H4 is:

[0322]

[0323]

[0324] Since the particles are roughly If you pass this section, the time it takes to pass this section is:

[0325]

[0326]

[0327] 5. The calculation process of the height H5 in the isothermal and uniform reaction stage is as follows:

[0328] because The time is too short, far from meeting the requirement of 5-120s, so an isothermal uniform reaction stage is set to increase the residence time. Assuming that the total residence time of the reaction is , to calculate the remaining remaining height.

[0329] Since the velocity of gas and solid is relatively small, the effect of the resistance loss along this section on the velocity is ignored.

[0330] (1) Steam physical property parameter query

[0331] Since the particle temperature and gas temperature are close to 250 , so this reaction stage is an isothermal and isobaric reaction.

[0332] Check water vapor T= 、Physical properties of p=3.98MPa:

[0333] specific volume

[0334] Dynamic viscosity

[0335] Thermal conductivity

[0336] (2) Reynolds number calculation

[0337] Sedimentation velocity :

[0338]

[0339]

[0340] Because of the previous stage Located in the transition zone, so

[0341]

[0342]

[0343] so

[0344] so for:

[0345]

[0346]

[0347] The average air velocity in this section is:

[0348]

[0349]

[0350] Therefore for:

[0351]

[0352]

[0353] The outlet gas velocity is , so the inlet air velocity The assumption is established.

[0354] (3) The height H5 of the isothermal and uniform reaction stage is calculated as follows:

[0355] The height H5 of the isothermal and uniform reaction stage is:

[0356]

[0357]

[0358] Therefore, the total height of the reactor That is, the sum of the heights of the material accelerated heating zone H1, the uniform heating stage 1 H2, the uniform heating stage 2 H3, the uniform heating reaction stage H4, and the isothermal uniform reaction stage H5:

[0359]

[0360] ,

[0361] Therefore, the total height The total height is 2.5m, so the actual height of the isothermal uniform reaction stage is

[0362]

[0363] Example 3

[0364] Assuming that other conditions in Example 2 remain unchanged, the total residence time of the isothermal reaction is extended to τ = 60 s, wherein steps (1) and (2) are calculated in the same manner as for τ = 10 s.

[0365] In step (3), the reactor height is calculated

[0366] The height H5 of the isothermal and uniform reaction stage is:

[0367]

[0368]

[0369] Therefore, the total height of the reactor for:

[0370]

[0371] ,

[0372] Therefore, the total height The total is 15.0m, so the actual height of the isothermal and uniform reaction stage is

[0373]

[0374] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A design method for a furfural tubular reactor, characterized in that, The following steps are involved: (1) Determine the material heating temperature and residence time, and calculate the steam flow rate and reactor diameter based on the material parameters; (2) Assume that the material is heated to T after passing through the material acceleration heating zone. m1 , according to the temperature T m1 Perform constant heat calculation to obtain the average steam temperature in the material accelerated heating zone; (3) Calculate the Reynolds number of the material passing through the material acceleration heating zone, and calculate the height of the material acceleration heating zone based on the Reynolds number; (4) Repeat steps (2)-(3) to calculate the heights of the uniform heating stage 1, the uniform heating stage 2, the uniform heating reaction stage, and the isothermal uniform reaction stage in sequence; (5) Calculate the total height of the furfural tubular reactor and round the height; The furfural tubular reactor used in the design method of the furfural tubular reactor includes a reaction tube body, a steam inlet is provided at one end of the reaction tube body, a material outlet is provided at the other end, and a material inlet is provided on the side wall of the reaction tube body near the steam inlet; the reaction tube body is divided into a material accelerated heating zone and a material uniform heating zone from bottom to top, and the material uniform heating zone is divided into a uniform heating stage 1, a uniform heating stage 2, a uniform heating reaction stage, and an isothermal uniform reaction stage from bottom to top.

2. the design method of furfural tubular reactor as claimed in claim 1, is characterized in that, The steam inlet is connected to the steam pipeline through a blower, the material outlet is connected to the cyclone separator, and the material inlet is connected to the material conveying device.

3. The method for designing a furfural tubular reactor as claimed in claim 1, wherein In step (1), the flow rate of the steam is calculated according to the energy conservation formula: Where, is the material handling capacity; is the specific heat capacity of water; is the specific heat capacity of the material; is the material outlet temperature; is the material inlet temperature; L is the steam flow rate; is the inlet steam specific enthalpy; is the outlet steam specific enthalpy.

4. The method for designing a furfural tubular reactor as claimed in claim 1, wherein In step (1), the diameter of the reactor is calculated according to the following formula: Where, L is the steam flow rate; is the specific volume of the inlet steam; D is the reactor diameter; is the inlet steam velocity.

5. The method for designing a furfural tubular reactor as claimed in claim 1, wherein In step (2), the physical properties of the water vapor are queried based on the obtained average steam temperature of the material, and the physical properties include specific volume, dynamic viscosity and thermal conductivity.

6. The design method of the furfural tubular reactor as claimed in claim 5, wherein In step (3), the Reynolds number is calculated based on the physical parameters of the water vapor, and the Reynolds number includes the initial Reynolds number and the sedimentation Reynolds number.

7. The design method of the furfural tubular reactor as claimed in claim 6, wherein In step (3), the volume heat transfer coefficient in the region is calculated based on the sedimentation Reynolds number, and then the height of the reactor in the region is obtained according to the following formula: Where Q is the heat transfer capacity of the reactor in this area, is the volume heat transfer coefficient, D is the diameter of the reactor, H is the height of the reactor in this area, is the steam temperature difference in this area.

8. The design method of the furfural tubular reactor as claimed in claim 1, wherein The height of the isothermal uniform reaction is used to meet the residence time of the particles passing through the uniform reaction zone.

9. The method for designing a furfural tubular reactor according to claim 1, wherein In the step (4), the Reynolds number calculation in the calculation process of each height of the uniform heating stage 1, the uniform heating stage 2, the uniform heating reaction stage, and the isothermal uniform reaction stage only includes the sedimentation Reynolds number calculation.

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