Air dry heat type high-temperature sterilizer and design method

Abstract

The invention relates to the technical field of high-temperature sterilization equipment, in particular to an air dry heat type high-temperature sterilizer and a design method.The sterilizer comprises a heating section, a heat exchange section and a cooling section, the heating section comprises a heating outer pipe, a heating inner pipe and an electric heating bar, the heating inner pipe is sleeved with the heating outer pipe, and the electric heating bar is inserted into the heating inner pipe; the heat exchange section comprises a heat exchange inner pipe and a heat exchange outer pipe, the cooling section comprises a cooling inner pipe and a cooling outer pipe, one end of the heat exchange outer pipe is provided with an air inlet, the other end of the heat exchange outer pipe is connected with the heating inner pipe, one end of the heat exchange inner pipe is connected with the heating outer pipe, and the other end of the heat exchange inner pipe is connected with one end of the cooling inner pipe. The other end of the cooling inner pipe is an air outlet, a cold water inlet is formed in one end, close to the air outlet, of the cooling outer pipe, and a cold water outlet is formed in the other end, close to the air inlet, of the cooling outer pipe. The sterilization device has the advantages of being good in sterilization effect, high in sterilization efficiency, free of an independent sterilization cavity, capable of directly acting on bacteria through high temperature, thorough in sterilization and the like.

Description

Technical Field

[0001] This invention relates to the field of high-temperature sterilization equipment technology, specifically to an air dry heat high-temperature sterilizer and its design method. Background Technology

[0002] As is well known, the air used in bio-fermentation is sterilized by sterilization equipment, typically using sterile filters. These filters contain filter cartridges, but because they have a limited sterilization efficiency, they cannot achieve 100% sterilization. Furthermore, untimely filter replacement or filter failure can lead to contamination, potentially contaminating the entire fermentation unit. Conventional dry heat sterilizers involve placing the equipment to be sterilized in a sealed chamber and heating the air to a high temperature (above 250°C) for a certain period to kill bacteria in both the equipment and the air. Existing dry heat sterilizers require a separate sterilization chamber, directly heating the air within that chamber. This results in problems such as inconsistent sterilization purposes, long sterilization times, discontinuous air flow, and poor sterilization effectiveness. In particular, the heated air needs to be cooled after sterilization, which also takes time, leading to excessively long sterilization times and ineffective sterilization. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide an air dry heat high-temperature sterilizer and its design method that is simple in structure, has good sterilization effect, high sterilization efficiency, does not require a separate sterilization chamber, directly acts on the bacteria themselves at high temperature, sterilizes thoroughly, and can continuously sterilize the air.

[0004] The technical solution adopted by this invention to solve its technical problem is:

[0005] An air-dry heat high-temperature sterilizer is characterized in that the sterilizer includes a heating section, a heat exchange section, and a cooling section. The heating section includes an outer heating tube, an inner heating tube, and a heating rod. The outer heating tube is fitted with the inner heating tube, and the heating rod is inserted inside the inner heating tube. The heat exchange section includes an inner heat exchange tube and an outer heat exchange tube, with the inner heat exchange tube inserted inside the outer heat exchange tube. The cooling section includes an inner cooling tube and an outer cooling tube, with the inner cooling tube inserted inside the outer cooling tube. One end of the outer heat exchange tube has an air inlet, and the other end of the outer heat exchange tube is connected to the inner heating tube. One end of the inner heat exchange tube is connected to the outer heating tube, and the other end of the inner heat exchange tube is connected to one end of the inner cooling tube. The other end of the inner cooling tube is an air outlet. A cold water inlet is located at one end of the outer cooling tube near the air outlet, and a cold water outlet is located at the other end of the outer cooling tube near the air inlet.

[0006] The heating outer tube of the present invention is closed at both ends. One end of the heating inner tube is open and inserted into the bottom of the heating outer tube. The other end of the heating inner tube extends out of the heating outer tube and is provided with an air inlet. The air inlet is connected to the heat exchange outer tube through a pipe. The heating rod is inserted into the bottom of the heating inner tube through the heating inner tube extending out of the heating outer tube. An air outlet is provided on the heating outer tube on the same side as the air inlet. The air outlet is connected to the heat exchange inner tube of the heat exchange section through a connecting pipe.

[0007] The gap between the heating rod and the heating inner tube described in this invention is the heating gap.

[0008] The heat exchange inner tube of the present invention includes multiple heat exchange inner straight tubes and multiple heat exchange inner bent tubes. The beginning and end of the multiple heat exchange inner straight tubes are respectively connected to the heat exchange inner bent tubes in an S-shape. The heat exchange outer tube includes multiple heat exchange outer straight tubes and multiple heat exchange outer connecting tubes. The heat exchange outer straight tubes are sleeved on the outside of the heat exchange inner straight tubes. The beginning and end of the multiple heat exchange outer straight tubes are respectively connected to the heat exchange outer connecting tubes in an S-shape. One end of the heat exchange outer straight tube is provided with an air inlet. The other end of the heat exchange outer straight tube is connected to the heating inner tube. The heat exchange inner straight tube at the same position as the air inlet is connected to the cooling inner tube. The other end of the heat exchange inner straight tube is connected to the heating outer tube.

[0009] The heat exchange inner and outer tubes and the heat exchange outer connecting pipe described in this invention are located on the same side of the heat exchange inner straight tube and the heat exchange outer straight tube.

[0010] The cooling inner pipe of the present invention includes multiple cooling inner straight pipes and multiple cooling inner bent pipes. The beginning and end of the multiple cooling inner straight pipes are respectively connected to the cooling inner bent pipes in an S-shape. The cooling outer pipe includes multiple cooling outer straight pipes and multiple cooling outer connecting pipes. The cooling outer straight pipes are sleeved on the outside of the cooling inner straight pipes. The beginning and end of the multiple cooling outer straight pipes are respectively connected to the cooling outer connecting pipes in an S-shape. One end of the cooling outer pipe is provided with a cold water inlet, and the other end of the heat exchange outer pipe is provided with a cold water outlet. The outlet of the cooling inner straight pipe at the cold water inlet position is an air outlet. The other end of the cooling inner straight pipe is connected to the heat exchange inner straight pipe through the cooling inner and outer pipes.

[0011] A design method for an air dry heat high-temperature sterilizer, characterized by the following steps:

[0012] (I) Heat exchange section design method:

[0013] Step 1: First, determine the original parameters of the heat exchange section: inlet air pressure P1, standard atmospheric pressure P0, rated air flow rate M0 under standard conditions, air density ρ0 under standard conditions, air specific heat capacity Cp, air dynamic viscosity μ1, air thermal conductivity λ1, air Prandtl number Pr1, air volume expansion coefficient β, thermal conductivity of the heat exchange section pipe material λ0, tube-side inlet temperature t1, and the design target parameters: tube-side outlet temperature t2, circumferential seam inlet temperature t3, circumferential seam outlet temperature t4;

[0014] Step Two: Based on the parameters determined in Step One, calculate the air densities ρ1 and ρ2 using the following formula.

[0015]

[0016] Step 3: Select a set of heat exchange tubes. According to the ISO2037 standard series, DIN11850 standard series, or ASME BPE standard series, select two types of tubes: inner tube dw1, inner tube wall thickness δ1, outer tube Dw2, and outer tube wall thickness δ2.

[0017] Step 4: Calculate the inner pipe diameter dn1 (in meters), outer pipe inner diameter Dw2 (in meters), and equivalent circumferential gap diameter de (in meters) using the following formula. Based on the parameters determined in Step 2, calculate the average flow velocity W1 (in meters per second) and the average flow velocity W2 (in meters per second) in the pipe pass.

[0018] dn1=dw1-2×δ1

[0019] Dn2=Dw2-2×δ2

[0020] de=Dn2-dw1

[0021]

[0022] Step 5: Calculate the heat exchange capacity Q1 (in W) of the heat exchange section using the following formula.

[0023] Q1 = Cp × M0 × (t2 - t1);

[0024] Step Six: Calculate the inner tube Reynolds number Re_1 (dimensionless) and the circumferential joint Re_2 (dimensionless) using the following formula.

[0025]

[0026] Step 7: Calculate the heat transfer coefficient α1 on the inner side of the tube using the following formula (unit: W / m). 2 .℃),

[0027] Determining the applicable formula for heat transfer coefficient:

[0028] (1) When Re1 < 2100, the pipe size should be reduced to make Re1 > 2100;

[0029] (2) When 2100 < Re1 < 10000, use the following formula:

[0030]

[0031] (3) When Re1 > 10000, use the following formula:

[0032]

[0033] Step 8: Calculate the heat transfer coefficient α2 of the outer circumferential joint of the tube side using the following formula (unit: W / m²). 2 .℃),

[0034] The values ​​used in calculating the heat transfer coefficient of the annular gap are: temperature difference Δt, gravitational acceleration g;

[0035] Determining the applicable formula for heat transfer coefficient:

[0036] (1) When 200 < Re2 < 2000, use the following formula:

[0037]

[0038] (2) When Re2 > 10000, use the following formula:

[0039]

[0040] (3) When 2000 < Re2 < 10000, take the values ​​of Re2 = 2000 and Re2 = 10000, and then use interpolation to obtain the actual Re2 value;

[0041] (4) When Re2 < 200, the pipe specifications should be reduced. Following step three of the heat exchange section calculation method, reselect the pipe specifications and recalculate until the requirements are met;

[0042] Step 9: Calculate the heat transfer temperature difference ΔT1 (unit: °C) and the heat transfer coefficient K1 (unit: W / m²) using the following formulas. 2 .℃),

[0043]

[0044] Step 10: According to the structural design, first select a certain length L of the sleeve. 0-0 (unit: m), then calculate the heat exchange area F1 (unit: m) using the following formula. 2 Total casing length L1 (in meters), number of casings N 0-0 (dimensionless)

[0045]

[0046] (II) Cooling Section Design Method:

[0047] Step 1: First, determine the original parameters of the cooling section: thermal conductivity of water λ2, dynamic viscosity of water μ2, Prandtl number of water Pr2, water coefficient n2, thermal conductivity of air λ1, tube-side air inlet temperature t7 = t2, and the design target parameters: annular gap water inlet temperature t5, annular gap water velocity W4, tube-side outlet temperature t8.

[0048] Step Two: Based on the parameters determined in Step One, calculate the air density ρ3 (unit: kg / m³) using the following formula. 3 ),

[0049]

[0050] Step 3: Select two specifications of pipe (same as the heat exchange section, inner pipe dw1×δ1, outer pipe Dw2×δ2),

[0051] Step 4: Based on the parameters determined in Step 1, calculate the tube-side flow velocity W3 (in m / s).

[0052]

[0053] Step 5: Calculate the heat exchange capacity Q2 (in W), annular gap water flow rate M2 (in m / s), and annular gap water outlet temperature t6 (in °C) of the cooling section according to the following formula.

[0054] Q2 = Cp × M0 × (t7 - t8)

[0055]

[0056] Step Six: Calculate the tube-side Reynolds number Re3 (dimensionless) and the annular seam Re4 (dimensionless) using the following formula.

[0057]

[0058] Step 7: Calculate the heat transfer coefficient α3 inside the tube side using the following formula (unit: W / m). 2 .℃),

[0059] Determining the applicable formula for heat transfer coefficient:

[0060] (1) When Re3 < 2100, the pipe specification should be reduced to make Re3 > 2100. Then, according to step three in the calculation method of the cooling section, the pipe specification should be reselected and the calculation should be recalculated until the requirements are met.

[0061] (2) When 2100 < Re3 < 10000, use the following formula:

[0062]

[0063] (3) When Re3 > 10000, use the following formula:

[0064]

[0065] Step 8: Calculate the heat transfer coefficient α4 of the outer circumferential joint of the tube side using the following formula (unit: W / m²). 2 .℃);

[0066]

[0067] Step 9: Calculate the heat transfer temperature difference ΔT2 (unit: °C) and the heat transfer coefficient K2 (unit: W / m²) using the following formulas. 2 .℃),

[0068]

[0069]

[0070] Step 10: According to the structural design, first select a sleeve of length L. 0-1 (Generally, L is taken) 0-1 =L 0-0 The heat exchange area F2 (unit: m) is then calculated using the following formula. 2 ), Total casing length L2 (in meters), Number of casings N 0-1 (dimensionless)

[0071]

[0072] (III) Calculation method for air resistance of sterilizer:

[0073] Step 1: Determine the original operating parameters based on the structure: total number of tube bends in the heat exchange and cooling sections N1 (dimensionless), tube bend resistance coefficient ξ1, number of circumferential seam turns in the heat exchange section N2 (dimensionless), and circumferential seam turn resistance coefficient ξ2.

[0074] Step 2: Calculate the frictional resistance coefficient λ of the heat exchange section tubes based on the parameters determined in Step 1. n1 The frictional resistance coefficient λ of the cooling section tubes n3 (dimensionless), frictional resistance coefficient λ of the heat exchange section annular seam t2 (Dimensionless), tube-side air friction resistance ΔPzn (unit Pa), heat exchange section annular gap air friction resistance ΔPzt (unit Pa),

[0075]

[0076] Step 3: Based on the parameters determined in Step 1, calculate the total resistance coefficient of the pipe-side elbow ∑ξ1 (dimensionless), the circumferential joint turning resistance coefficient ∑ξ2 (dimensionless), the local resistance of the pipe-side ΔPznjb (unit Pa), and the local resistance of the circumferential joint ΔPztjb (unit Pa) using the following formulas.

[0077] ∑ξ1=N1×ξ1

[0078] ∑ξ2=N2×ξ2

[0079]

[0080] Step 4: Calculate the total air resistance of the sterilizer ∑ΔP (unit: Pa) using the following formula.

[0081] ∑ΔP=(ΔPzn+ΔPzt+ΔPznjb+ΔPztjb)×1.2,

[0082] Step 5: Verify the total air resistance of the sterilizer ∑ΔP (unit: Pa).

[0083] If the total air resistance of the sterilizer ∑ΔP < 2% × P1, then the selected pipe specifications meet the requirements; if ∑ΔP ≥ 2% × P1, then follow step three in the heat exchange section calculation method, reselect the pipe specifications, and recalculate until the requirements are met.

[0084] (IV) Calculation method for residence time in the heating section:

[0085] Step 1: First, select a specific specification for the heating outer tube's outer diameter Dtw (in meters), wall thickness δt (in meters), and length H (in meters).

[0086] Step 2: Based on the parameters determined in Step 1, calculate the internal volume Vt of the heating outer tube (unit: m³) using the following formula. 3 ),

[0087]

[0088] Step 3: Calculate the air residence time T (in seconds).

[0089]

[0090] Step 4: Verify the air residence time T (in seconds).

[0091] If the air residence time T > 10s, then the volume of the heating outer tube meets the requirements.

[0092] The present invention, due to the above-mentioned structure, has the advantages of simple structure, good sterilization effect, high sterilization efficiency, no need for a separate sterilization chamber, direct action on the bacteria themselves through high temperature, thorough sterilization, and continuous sterilization of air. Attached Figure Description

[0093] Figure 1 This is a schematic diagram of the structure of the present invention.

[0094] Figure 2 yes Figure 1 The main view. Detailed Implementation

[0095] The present invention will be further described below with reference to the accompanying drawings:

[0096] As shown in the attached figure, an air dry heat high-temperature sterilizer is characterized in that the sterilizer includes a heating section 1, a heat exchange section 2, and a cooling section 3. The heating section 1 includes a heating outer tube 4, a heating inner tube 5, and an electric heating rod 6. The heating outer tube 4 is fitted with the heating inner tube 5, and the electric heating rod 6 is inserted inside the heating inner tube 5. The heat exchange section 2 includes a heat exchange inner tube 7 and a heat exchange outer tube 8, with the heat exchange inner tube 7 inserted inside the heat exchange outer tube 8. The cooling section 3 includes a cooling inner tube 9 and a cooling outer tube 10, with the cooling inner tube 9 inserted inside the cooling outer tube 10. One end of the heat exchange outer tube 8 is provided with an air inlet 11, and the other end of the heat exchange outer tube 8 is connected to the heating inner tube 5. One end of the heat exchange inner tube 7 is connected to the heating outer tube 4, and the other end of the heat exchange inner tube 7 is connected to one end of the cooling inner tube 9. The other end of the cooling inner tube 9 is an air outlet 12. One end of the cooling outer tube 10 near the air outlet 12 is provided with a cold water inlet 13, and the other end of the cooling outer tube 10 near the air inlet 11 is provided with a cold water outlet 14.

[0097] Furthermore, both ends of the heating outer tube 4 are respectively closed, one end of the heating inner tube 5 is open and inserted into the bottom of the heating outer tube 4, the other end of the heating inner tube 5 extends out of the heating outer tube 4 and is provided with an air inlet, the air inlet is connected to the heat exchange outer tube 8 through a pipe, the heating rod 6 is inserted into the bottom of the heating inner tube 5 through the heating inner tube 5 extending out of the heating outer tube 4, and an air outlet is provided on the heating outer tube 4 on the same side as the air inlet, the air outlet is connected to the heat exchange inner tube 7 of the heat exchange section 2 through a connecting pipe.

[0098] Furthermore, the gap between the heating rod 6 and the heating inner tube 5 is the heating gap.

[0099] Furthermore, the heat exchange inner tube 7 includes multiple heat exchange inner straight tubes 15 and multiple heat exchange inner bent tubes 16. The beginning and end of the multiple heat exchange inner straight tubes 15 are respectively connected to the heat exchange inner bent tubes 16 in an S-shape. The heat exchange outer tube 8 includes multiple heat exchange outer straight tubes 21 and multiple heat exchange outer connecting tubes 22. The heat exchange outer straight tubes 21 are sleeved on the outside of the heat exchange inner straight tubes 15. The beginning and end of the multiple heat exchange outer straight tubes 21 are respectively connected to the heat exchange outer connecting tubes 22 in an S-shape. One end of the heat exchange outer straight tube 21 is provided with an air inlet 11. The other end of the heat exchange outer straight tube 21 is connected to the heating inner tube 5. The heat exchange inner straight tube 15 at the same position as the air inlet 11 is connected to the cooling inner tube 9. The other end of the heat exchange inner straight tube 15 is connected to the heating outer tube 4.

[0100] Furthermore, the heat exchange inner and outer tubes and the heat exchange outer connecting pipe 22 are located on the same side of the heat exchange inner straight pipe 15 and the heat exchange outer straight pipe 21.

[0101] Furthermore, the inner cooling pipe 9 includes multiple inner cooling straight pipes 17 and multiple inner cooling bends 18. The beginnings and ends of the multiple inner cooling straight pipes 17 are connected to the inner cooling bends in an S-shape. The outer cooling pipe 10 includes multiple outer cooling straight pipes 19 and multiple outer cooling connecting pipes 20. The outer cooling straight pipes 19 are sleeved on the outside of the inner cooling straight pipes 17. The beginnings and ends of the multiple outer cooling straight pipes 19 are connected to the outer cooling connecting pipes 20 in an S-shape. One end of the outer cooling pipe 10 is provided with a cold water inlet 13, and the other end of the heat exchange outer pipe 8 is provided with a cold water outlet 14. The outlet of the inner cooling straight pipe 17 at the cold water inlet 13 is an air outlet 12. The other end of the inner cooling straight pipe 17 is connected to the heat exchange inner straight pipe 15 via the inner and outer cooling pipes.

[0102] A design method for an air dry heat high-temperature sterilizer, characterized by the following steps:

[0103] (I) Heat exchange section design method:

[0104] Step 1: First, determine the original operating parameters of the heat exchange section: inlet air pressure P1 (in Pa), standard atmospheric pressure P0 (taken as 101325 Pa), and rated air flow rate M0 under standard conditions (in m³). 3 / s), air density ρ0 under standard conditions (taken as 1.293 kg / m³) 3 ), air specific heat capacity Cp (taken as 1.3 kJ / m³) 3 Air dynamic viscosity μ1 (taken as 0.0000183 Pa·s), air thermal conductivity λ1 (taken as 0.0296 W / m·℃ when the average tube-side temperature is 170℃, and as 0.0389 W / m·℃ when the average circumferential temperature is 210℃), air Prandtl number Pr1 (taken as 0.7239), air volumetric expansion coefficient β (taken as 3.676 × 10⁻⁶). -3 / ℃), the thermal conductivity λ0 of the heat exchange section tube material (3.0w / m.℃ for S30408 ​​and S31603 stainless steel), the tube inlet temperature t1 (20℃), and the design target parameters: tube outlet temperature t2 (320℃), circumferential seam inlet temperature t3 (360℃), and circumferential seam outlet temperature t4 (60℃).

[0105] The tube side refers to the process inside the inner tube, while the circumferential joint refers to the gap between the inner and outer tubes.

[0106] Step Two: Based on the parameters determined in Step One, calculate the air density ρ1 (unit: kg / m³) using the following formula. 3 ), ρ2 (unit kg / m 3 ),

[0107]

[0108] Step 3: Select a set of heat exchange tubes (based on the ISO2037 standard series, or DIN11850 standard series, or ASME BPE standard series) and choose two types of tubes, inner tube dw1 (unit m), inner tube wall thickness δ1 (unit m), outer tube Dw2 (unit m), outer tube wall thickness δ2 (unit m);

[0109] Step 4: Calculate the inner pipe diameter dn1 (in meters), outer pipe inner diameter Dw2 (in meters), and equivalent circumferential gap diameter de (in meters) using the following formula. Based on the parameters determined in Step 2, calculate the average flow velocity W1 (in meters per second) and the average flow velocity W2 (in meters per second) in the pipe pass.

[0110] dn1=dw1-2×δ1

[0111] Dn2=Dw2-2×δ2

[0112] de=Dn2-dw1

[0113]

[0114] Step 5: Calculate the heat exchange capacity Q1 (in W) of the heat exchange section using the following formula.

[0115] Q1 = Cp × M0 × (t2 - t1);

[0116] Step Six: Calculate the inner tube Reynolds number Re_1 (dimensionless) and the circumferential joint Re_2 (dimensionless) using the following formula.

[0117]

[0118] Step 7: Calculate the heat transfer coefficient α1 on the inner side of the tube using the following formula (unit: W / m). 2 .℃),

[0119] Determining the applicable formula for heat transfer coefficient:

[0120] (1) When Re1 < 2100, the pipe size should be reduced to make Re1 > 2100;

[0121] (2) When 2100 < Re1 < 10000, use the following formula:

[0122]

[0123] (3) When Re1 > 10000, use the following formula:

[0124]

[0125] Step 8: Calculate the heat transfer coefficient α2 of the outer circumferential joint of the tube side using the following formula (unit: W / m²). 2 .℃),

[0126] The values ​​used in calculating the heat transfer coefficient of the annular gap are: temperature difference Δt (taken as 60-20=40℃), gravitational acceleration g (taken as 9.81kg / m·s2);

[0127] Determining the applicable formula for heat transfer coefficient:

[0128] (1) When 200 < Re2 < 2000, use the following formula:

[0129]

[0130] (2) When Re2 > 10000, use the following formula:

[0131]

[0132] (3) When 2000 < Re2 < 10000, take the values ​​of Re2 = 2000 and Re2 = 10000, and then use interpolation to obtain the actual Re2 value;

[0133] (4) When Re2 < 200, the pipe size should be reduced, and the pipe size should be reselected and recalculated according to step three in the heat exchange section calculation method until the requirements are met.

[0134] Step 9: Calculate the heat transfer temperature difference ΔT1 (unit: °C) and the heat transfer coefficient K1 (unit: W / m²) using the following formulas. 2 .℃),

[0135]

[0136] Step 10: According to the structural design, first select a certain length L of the sleeve. 0-0 (unit: m), then calculate the heat exchange area F1 (unit: m) using the following formula. 2 Total casing length L1 (in meters), number of casings N 0-0 (dimensionless)

[0137]

[0138] (II) Cooling Section Design Method:

[0139] Step 1: First, determine the original parameters of the cooling section: thermal conductivity of water λ2 (0.621 W / m·℃), dynamic viscosity of water μ2 (0.00131 Pa·s), Prandtl number of water Pr2 (11.18), (water) coefficient n2 (0.4), thermal conductivity of air λ1 (0.0278 W / m·℃ when the average tube-side temperature is 45℃), tube-side (air) inlet temperature t7 = t2 (t2 = 60℃), and design target parameters: annular gap water inlet temperature t5 (5℃), annular gap water velocity W4 (0.25 m / s), tube-side outlet temperature t8 (30℃). The tube-side refers to the process inside the inner tube, and the annular gap refers to the gap between the inner and outer tubes.

[0140] Step Two: Based on the parameters determined in Step One, calculate the air density ρ3 (unit: kg / m³) using the following formula. 3 ),

[0141]

[0142] Step 3: Select two specifications of pipe (same as the heat exchange section, inner pipe dw1×δ1, outer pipe Dw2×δ2),

[0143] Step 4: Based on the parameters determined in Step 1, calculate the tube-side flow velocity W3 (in m / s).

[0144]

[0145] Step 5: Calculate the heat exchange capacity Q2 (in W), annular gap water flow rate M2 (in m / s), and annular gap water outlet temperature t6 (in °C) of the cooling section according to the following formula.

[0146] Q2 = Cp × M0 × (t7 - t8)

[0147]

[0148] Step Six: Calculate the tube-side Reynolds number Re3 (dimensionless) and the annular seam Re4 (dimensionless) using the following formula.

[0149]

[0150] Step 7: Calculate the heat transfer coefficient α3 inside the tube side using the following formula (unit: W / m). 2 .℃),

[0151] Determining the applicable formula for heat transfer coefficient:

[0152] (1) When Re3 < 2100, the pipe specification should be reduced to make Re3 > 2100. Then, according to step three in the calculation method of the cooling section, the pipe specification should be reselected and the calculation should be recalculated until the requirements are met.

[0153] (2) When 2100 < Re3 < 10000, use the following formula:

[0154]

[0155] (3) When Re3 > 10000, use the following formula:

[0156]

[0157] Step 8: Calculate the heat transfer coefficient α4 of the outer circumferential joint of the tube side using the following formula (unit: W / m²). 2 .℃);

[0158]

[0159] Step 9: Calculate the heat transfer temperature difference ΔT2 (unit: °C) and the heat transfer coefficient K2 (unit: W / m²) using the following formulas. 2 .℃),

[0160]

[0161] Step 10: According to the structural design, first select a sleeve of length L. 0-1 (Generally, L is taken) 0-1 =L 0-0 The heat exchange area F2 (unit: m) is then calculated using the following formula. 2 ), Total casing length L2 (in meters), Number of casings N 0-1 (dimensionless)

[0162]

[0163] (III) Calculation method for air resistance of sterilizer:

[0164] Step 1: Determine the original operating parameters based on the structure: total number of tube-side elbows in the heat exchange and cooling sections N1 (dimensionless), tube-side elbow resistance coefficient ξ1 (taken as 0.18), number of circumferential seam turns in the heat exchange section N2 (dimensionless), circumferential seam turn resistance coefficient ξ2 (taken as 2.2). The tube-side elbows are internal bends, and the number of circumferential seam turns in the heat exchange section is the number of external connecting pipes.

[0165] Step 2: Calculate the frictional resistance coefficient λ of the heat exchange section tubes based on the parameters determined in Step 1. n1 The frictional resistance coefficient λ of the cooling section tubes n3 (dimensionless), frictional resistance coefficient λ of the heat exchange section annular seam t2 (Dimensionless), tube-side air friction resistance ΔPzn (unit Pa), heat exchange section annular gap air friction resistance ΔPzt (unit Pa),

[0166]

[0167] Step 3: Based on the parameters determined in Step 1, calculate the total resistance coefficient of the pipe-side elbow ∑ξ1 (dimensionless), the circumferential joint turning resistance coefficient ∑ξ2 (dimensionless), the local resistance of the pipe-side ΔPznjb (unit Pa), and the local resistance of the circumferential joint ΔPztjb (unit Pa) using the following formulas.

[0168] ∑ξ1=N1×ξ1

[0169] ∑ξ2=N2×ξ2

[0170]

[0171] Step 4: Calculate the total air resistance of the sterilizer ∑ΔP (unit: Pa) using the following formula.

[0172] ∑ΔP=(ΔPzn+ΔPzt+ΔPznjb+ΔPztjb)×1.2,

[0173] Step 5: Verify the total air resistance of the sterilizer ∑ΔP (unit: Pa).

[0174] If the total air resistance of the sterilizer ∑ΔP < 2% × P1, then the selected pipe specifications meet the requirements; if ∑ΔP ≥ 2% × P1, then follow step three in the heat exchange section calculation method, reselect the pipe specifications, and recalculate until the requirements are met.

[0175] (IV) Calculation method for residence time in the heating section:

[0176] Step 1: First, select a specific specification for the heating outer tube's outer diameter Dtw (in meters), wall thickness δt (in meters), and length H (in meters).

[0177] Step 2: Based on the parameters determined in Step 1, calculate the internal volume Vt of the heating outer tube (unit: m³) using the following formula. 3 ),

[0178]

[0179] Step 3: Calculate the air residence time T (in seconds).

[0180]

[0181] Step 4: Verify the air residence time T (in seconds).

[0182] If the air residence time T > 10s, then the volume of the heating outer tube meets the requirements.

[0183] The above structure uses countercurrent heat exchange technology to cool the high-temperature sterile air that needs to be cooled after sterilization, which greatly reduces the power consumption of the electric heating rod and the cooling efficiency of the cold water.

[0184] The total length of the heat exchange section, the total length of the cooling section, and the parameters of the heating section obtained above can be adjusted to customize the space occupied by the sterilizer according to the installation location.

[0185] The present invention, due to the above-mentioned structure, has the advantages of simple structure, good sterilization effect, high sterilization efficiency, no need for a separate sterilization chamber, direct action on the bacteria themselves through high temperature, thorough sterilization, and continuous sterilization of air.

[0186] In this invention, the circumferential seam refers to the gap between the inner tube and the outer tube, and the tube stroke refers to the stroke inside the inner tube.

[0187] One embodiment of the method is as follows:

[0188] A design method for an air dry heat high-temperature sterilizer, the steps of which are as follows:

[0189] (I) Heat exchange section design method:

[0190] Step 1: First, determine the initial operating parameters of the heat exchange section: inlet air pressure P1 = 303975 Pa, standard atmospheric pressure P0 = 101325 Pa, rated air flow rate under standard conditions M0 = 50 L / min = 0.0008333 m³ / min 3 / s, air density under standard conditions ρ0=1.293kg / m³ 3 Specific heat capacity of air Cp = 1.3 kJ / m³ 3 .℃, air dynamic viscosity μ1=0.0000183Pa.s, air thermal conductivity λ1 (0.0296w / m.℃ when the average tube-side temperature is 170℃, and 0.0389w / m.℃ when the average circumferential temperature is 210℃), air Prandtl number Pr1 is 0.7239, air volume expansion coefficient β=3.676×10 -3 / ℃, the heat exchange section tube material is S31603 stainless steel with a metal thermal conductivity λ0=3.0w / m.℃, tube side inlet temperature t1=20℃, target parameters: tube side outlet temperature t2=320℃, circumferential seam inlet temperature t3=360℃, circumferential seam outlet temperature t4=60℃;

[0191] Step Two: Based on the parameters determined in Step One, calculate the air density ρ1 (unit: kg / m³) using the following formula. 3 ), ρ2 (unit kg / m 3 ),

[0192]

[0193] Step 3: Select a set of heat exchange tubes (based on the ISO 2037 standard series, DIN 11850 standard series, or ASME BPE standard series). Select two types of tubes: inner tube dw1 (unit: m), inner tube wall thickness δ1 (unit: m), outer tube Dw2 (unit: m), and outer tube wall thickness δ2 (unit: m). Select a set of heat exchange tubes with inner tube dw1 = 0.0254 m, inner tube wall thickness δ1 = 0.0015 m, outer tube Dw2 = 0.0381 m, and outer tube wall thickness δ2 = 0.0015 m.

[0194] Step 4: Calculate the inner pipe diameter dn1 (in meters), outer pipe inner diameter Dw2 (in meters), and equivalent circumferential gap diameter de (in meters) using the following formula. Based on the parameters determined in Step 2, calculate the average flow velocity W1 (in meters per second) and the average flow velocity W2 (in meters per second) in the pipe pass.

[0195] dn1=dw1-2×δ1=0.0254-2×0.0015=0.0224m

[0196] Dn2=Dw2-2×δ2=0.0381-2×0.0015=0.0351m

[0197] de=Dn2-dw1=0.0351-0.0254=0.0097m

[0198]

[0199] Step 5: Calculate the heat exchange capacity Q1 (in W) of the heat exchange section using the following formula.

[0200] Q1=Cp×M0×(t2-t1)=1.3×1000×0.0008333×(320-20)=325w;

[0201] Step Six: Calculate the inner tube Reynolds number Re_1 (dimensionless) and the circumferential joint Re_2 (dimensionless) using the following formula.

[0202]

[0203] Step 7: Calculate the heat transfer coefficient α1 on the inner side of the tube using the following formula (unit: W / m). 2 .℃),

[0204] The thermal conductivity λ1 of air is taken as 0.0296 W / m·℃ when the average temperature of the tube side is 170℃.

[0205] Criteria for determining the applicability of the heat transfer coefficient formula: When 2100 < Re1 = 3335 < 10000, use the following formula for calculation:

[0207]

[0208] Step 8: Calculate the heat transfer coefficient α2 of the outer circumferential joint of the tube side using the following formula (unit: W / m²). 2 .℃),

[0209] The values ​​used in calculating the heat transfer coefficient of the annular gap are: temperature difference Δt (taken as 60-20=40℃), gravitational acceleration g (taken as 9.81kg / m·s2);

[0210] The thermal conductivity of air, λ1, is taken as 0.0389 W / m·℃ when the average tube-side temperature is 210℃; L 0-0 The value is 0.7m.

[0211] Determining the applicability of the heat transfer coefficient formula: When 200 < Re2 = 1242 < 2000, use the following formula:

[0212]

[0213] Step 9: Calculate the heat transfer temperature difference ΔT1 (unit: °C) and the heat transfer coefficient K1 (unit: W / m²) using the following formulas. 2 .℃),

[0214]

[0215] Step 10: According to the structural design, determine the sleeve length L. 0-0 =0.7m, calculate the heat exchange area F1 (unit: m²) 2 Total casing length L1 (in meters), number of casings N 0-0 (dimensionless)

[0216]

[0217] Based on the structural design, N0-0 = 24;

[0218] (II) Cooling Section Design Method:

[0219] Step 1: First, determine the original parameters of the cooling section: thermal conductivity of water λ2 (taken as 0.621w / m.℃), dynamic viscosity of water μ2 (taken as 0.00131Pa.s), Prandtl number of water Pr2 (taken as 11.18), (water) coefficient n2 (taken as 0.4), thermal conductivity of air λ1 (taken as 0.0278w / m.℃ when the average tube-side temperature is 45℃), tube-side (air) inlet temperature t7 = t2 (t2 = 60℃), and the design target parameters: annular gap water inlet temperature t5 (taken as 5℃), annular gap water velocity W4 (taken as 0.25m / s), tube-side outlet temperature t8 (taken as 30℃).

[0220] Step Two: Based on the parameters determined in Step One, calculate the air density ρ3 (unit: kg / m³) using the following formula.3 ),

[0221]

[0222] Step 3: Select two specifications of pipe (same as the heat exchange section, inner pipe dw1×δ1, outer pipe Dw2×δ2),

[0223] Step 4: Based on the parameters determined in Step 1, calculate the tube-side flow velocity W3 (in m / s).

[0224]

[0225] Step 5: Calculate the heat exchange capacity Q2 (in W), annular gap water flow rate M2 (in m / s), and annular gap water outlet temperature t6 (in °C) of the cooling section according to the following formula.

[0226] Q2=Cp×M0×(t7-t8)=1.3×1000×0.0008333×(60-30)=32.5w

[0227]

[0228] Step Six: Calculate the tube-side Reynolds number Re3 (dimensionless) and the annular seam Re4 (dimensionless) using the following formula.

[0229]

[0230] Step 7: Calculate the heat transfer coefficient α3 inside the tube side using the following formula (unit: W / m). 2 .℃),

[0231]

[0232] Step 8: Calculate the heat transfer coefficient α4 of the outer circumferential joint of the tube side using the following formula (unit: W / m²). 2 .℃);

[0233]

[0234] Step 9: Calculate the heat transfer temperature difference ΔT2 (unit: °C) and the heat transfer coefficient K2 (unit: W / m²) using the following formulas. 2 .℃),

[0235]

[0236] Step 10: According to the structural design, determine the sleeve length L. 0-1 =L 0-0 =0.7m, calculate the heat exchange area F2 (unit: m²) 2 ), Total casing length L2 (in meters), Number of casings N 0-1 (dimensionless)

[0237]

[0238]

[0239] Round up to N 0-1 =2;

[0240] (III) Calculation method for air resistance of sterilizer:

[0241] Step 1: Determine the original operating parameters based on the structure: Total number of elbows in the heat exchange and cooling sections, N1 (dimensionless) N1 = N 0-0 +N 0-1 +1=27, pipe-side elbow resistance coefficient ξ1 (take 0.18), number of circumferential seam turns in the heat exchange section N2 (dimensionless) N2=N 0-0 +1=25, the circumferential seam turning resistance coefficient ξ2 (taken as 2.2).

[0242] Step 2: Calculate the frictional resistance coefficient λ of the heat exchange section tubes based on the parameters determined in Step 1. n1 The frictional resistance coefficient λ of the cooling section tubes n3 (dimensionless), frictional resistance coefficient λ of the heat exchange section annular seam t2 (dimensionless), tube-side air friction resistance ΔPzn (unit Pa), heat exchange section annular gap air friction resistance ΔPzt (unit Pa), 1.

[0243]

[0244] Step 3: Based on the parameters determined in Step 1, calculate the total resistance coefficient ∑ξ1 (dimensionless) of the pipe-side elbow, the circumferential joint turning resistance coefficient ∑ξ2 (dimensionless), the local resistance ΔPznjb (unit Pa) of the pipe-side elbow, and the local resistance ΔPztjb (unit Pa) of the circumferential joint.

[0245] ∑ξ1=N1×ξ1=27×0.18=4.86

[0246] ∑ξ2=N2×ξ2=25×2.2=55

[0247]

[0248] Step 4: Calculate the total air resistance of the sterilizer ∑ΔP (unit: Pa) using the following formula.

[0249] ∑ΔP=1.2×(ΔPzn+ΔPzt+ΔPznjb+ΔPztjb)=1.2×(48.8+110.9+7.5+40.5)=249.2Pa,

[0250] Step 5: Verify the total air resistance of the sterilizer ∑ΔP (unit: Pa).

[0251] The total air resistance of the sterilizer, ∑ΔP = 249.2 Pa < 2% × P1 = 2% × 303975 = 6079.5 Pa. Therefore, the selected pipe specifications meet the requirements.

[0252] (IV) Calculation method for residence time in the heating section:

[0253] Step 1: Determine the outer diameter D of the heater cylinder based on the structural layout. tw =0.133m, cylinder wall thickness δ t =0.003m, heating cylinder length H=0.7m,

[0254] Step 2: Based on the parameters determined in Step 1, calculate the internal volume Vt of the heating outer tube (unit: m³) using the following formula. 3 ),

[0255]

[0256] Step 3: Calculate the air residence time T (in seconds).

[0257]

[0258] Step 4: Verify the air residence time T (in seconds).

[0259] The air residence time T = 13.8s > 10s, and the volume of the heating outer tube meets the requirements.

Claims

1. An air dry heat high-temperature sterilizer, characterized in that... The sterilizer includes a heating section, a heat exchange section, and a cooling section. The heating section includes an outer heating tube, an inner heating tube, and a heating rod. The outer heating tube is fitted inside the inner heating tube, and the heating rod is inserted inside the inner heating tube. The heat exchange section includes an inner heat exchange tube and an outer heat exchange tube, with the inner heat exchange tube inserted inside the outer heat exchange tube. The cooling section includes an inner cooling tube and an outer cooling tube, with the inner cooling tube inserted inside the outer cooling tube. One end of the outer heat exchange tube has an air inlet, and the other end of the outer heat exchange tube is connected to the inner heating tube. One end of the inner heat exchange tube is connected to the outer heating tube, and the other end of the inner heat exchange tube is connected to one end of the inner cooling tube. The other end of the inner cooling tube is an air outlet. A cold water inlet is located at one end of the outer cooling tube near the air outlet, and a cold water outlet is located at the other end of the outer cooling tube near the air inlet.

2. The air dry heat high-temperature sterilizer according to claim 1, characterized in that... The heating outer tube has two closed ends. One end of the heating inner tube is open and inserted into the bottom of the heating outer tube. The other end of the heating inner tube extends out of the heating outer tube and has an air inlet. The air inlet is connected to the heat exchange outer tube via a pipe. The heating rod is inserted into the bottom of the heating inner tube through the heating inner tube extending out of the heating outer tube. An air outlet is provided on the heating outer tube on the same side as the air inlet. The air outlet is connected to the heat exchange inner tube of the heat exchange section via a connecting pipe.

3. The air dry heat high-temperature sterilizer according to claim 1, characterized in that... The gap between the heating rod and the inner heating tube is the heating gap.

4. The air dry heat high-temperature sterilizer according to claim 1, characterized in that... The heat exchange inner tube includes multiple heat exchange inner straight tubes and multiple heat exchange inner bent tubes. The beginning and end of the multiple heat exchange inner straight tubes are connected to the heat exchange inner bent tubes in an S-shape. The heat exchange outer tube includes multiple heat exchange outer straight tubes and multiple heat exchange outer connecting tubes. The heat exchange outer straight tubes are sleeved on the outside of the heat exchange inner straight tubes. The beginning and end of the multiple heat exchange outer straight tubes are connected to the heat exchange outer connecting tubes in an S-shape. One end of the heat exchange outer straight tube is provided with an air inlet, and the other end of the heat exchange outer straight tube is connected to the heating inner tube. The heat exchange inner straight tube at the same position as the air inlet is connected to the cooling inner tube, and the other end of the heat exchange inner straight tube is connected to the heating outer tube.

5. An air dry heat high-temperature sterilizer according to claim 1, characterized in that... The heat exchange inner and outer tubes and the heat exchange outer connecting pipe are located on the same side of the heat exchange inner straight tube and the heat exchange outer straight tube.

6. An air dry heat high-temperature sterilizer according to claim 1, characterized in that... The cooling inner pipe includes multiple cooling inner straight pipes and multiple cooling inner bent pipes. The beginning and end of the multiple cooling inner straight pipes are connected to the cooling inner bent pipes in an S-shape. The cooling outer pipe includes multiple cooling outer straight pipes and multiple cooling outer connecting pipes. The cooling outer straight pipes are sleeved on the outside of the cooling inner straight pipes. The beginning and end of the multiple cooling outer straight pipes are connected to the cooling outer connecting pipes in an S-shape. One end of the cooling outer pipe is provided with a cold water inlet, and the other end of the heat exchange outer pipe is provided with a cold water outlet. The outlet of the cooling inner straight pipe at the cold water inlet position is an air outlet. The other end of the cooling inner straight pipe is connected to the heat exchange inner straight pipe through the cooling inner and outer pipes.

7. A design method for an air dry heat high-temperature sterilizer, characterized in that... The design method steps are as follows: (I) Heat exchange section design method: Step 1: First, determine the original parameters of the heat exchange section operating conditions: inlet air pressure P1, standard atmospheric pressure P0, rated air flow rate M0 under standard conditions, air density ρ0 under standard conditions, air specific heat capacity Cp, air dynamic viscosity μ1, air thermal conductivity λ1, air Prandtl number Pr1, air volume expansion coefficient β, metal thermal conductivity λ0 of the heat exchange section pipe material, tube-side inlet temperature t1, and the designed target parameters: tube-side outlet temperature t2, annulus inlet temperature t3, annulus outlet temperature t4; Step 2: According to the parameters determined in Step 1, calculate the air densities ρ1 and ρ2 according to the following formula Step 3: Select a set of heat exchange tubes. According to the ISO2037 standard series, or DIN11850 standard series, or ASMEBPE standard series of the pipe material, select two of the pipe materials, inner tube dw1, inner tube wall thickness δ1, outer tube Dw2, outer tube wall thickness δ2; Step 4: Calculate the inner tube inner diameter dn1 (unit: m), outer tube inner diameter Dw2 (unit: m), and annulus equivalent diameter de (unit: m) according to the following formula, and calculate the tube-side average flow velocity W1 (unit: m / s) and annulus average flow velocity W2 (unit: m / s) according to the parameters determined in Step 2 dn1 = dw1 - 2×δ1 Dn2 = Dw2 - 2×δ2 de = Dn2 - dw1 Step 5: Calculate the heat transfer quantity Q1 (unit: w) of the heat exchange section according to the following formula Q1 = Cp×M0×(t2 - t1); Step 6: Calculate the inner tube Reynolds number Re_1 (dimensionless) and annulus Reynolds number Re_2 (dimensionless) according to the following formula Step 7: Calculate the heat transfer coefficient α1 on the inner side of the tube using the following formula (unit: W / m). 2 .℃), Discrimination of applicable formulas for heat transfer coefficient (1) When Re1 < 2100, the tube size should be reduced to make Re1 > 2100; (2) When 2100 <Re1 When <10000, use the following formula: (3) When Re1 > 10000, use the following formula Step 8: Calculate the heat transfer coefficient α2 of the outer circumferential joint of the tube side using the following formula (unit: W / m²). 2 .℃), Values used in calculating the annulus heat transfer coefficient: temperature difference Δt, gravitational acceleration g; Discrimination of applicable formulas for heat transfer coefficient (1) When 200 < Re2 < 2000, use the following formula (2) When Re2 > 10000, use the following formula (3) When 2000 < Re2 < 10000, take the values at Re2 = 2000 and Re2 = 10000, and then use the interpolation method according to the actual Re2 value; (4) When Re2 < 200, the tube size should be reduced, and according to Step 3 in the heat exchange section calculation method, reselect the pipe material specifications and recalculate until the requirements are met; Step 9: Calculate the heat transfer temperature difference ΔT1 (unit: °C) and the heat transfer coefficient K1 (unit: W / m²) using the following formulas. 2 .℃), Step 10: According to the structural design, first select a certain length L of the sleeve. 0-0 (unit: m), then calculate the heat exchange area F1 (unit: m) using the following formula. 2 Total casing length L1 (in meters), number of casings N 0-0 (dimensionless) (2) Cooling section design method Step 1: First, determine the original parameters of the cooling section operating conditions: water thermal conductivity λ2, water dynamic viscosity μ2, water Prandtl number Pr2, water coefficient n2, air thermal conductivity λ1, tube-side air inlet temperature t7 = t2, and the designed target parameters: annulus water inlet temperature t5, annulus water flow velocity W4, tube-side outlet temperature t8 Step Two: Based on the parameters determined in Step One, calculate the air density ρ3 (unit: kg / m³) using the following formula. 3 ), [[ID=二十一]]Step 3: Select two specifications of pipe materials (the same as the heat exchange section, inner tube dw1×δ1, outer tube Dw2×δ2) [[ID=二十二]]Step 4: According to the parameters determined in Step 1, calculate the tube-side flow velocity W3 (unit: m / s) Step 5: Calculate the heat transfer quantity Q2 (unit: w), the annular gap water flow rate M2 (unit: m / s), and the annular gap water outlet temperature t6 (unit: °C) in the cooling section according to the following formula: Q2 = Cp × M0 × (t7 - t8) Step 6: Calculate the Reynolds number Re3 (dimensionless) and the annular gap Reynolds number Re4 (dimensionless) in the tube side according to the following formula: Step 7: Calculate the heat transfer coefficient α3 inside the tube side using the following formula (unit: W / m). 2 .℃), Discrimination of the applicable formula for heat transfer coefficient: (1) When Re3 < 2100, the tube specification should be reduced to make Re3 > 2100. According to Step 3 in the calculation method of the cooling section, re-select the tube material specification and recalculate until the requirements are met. (2) When 2100 < Re3 < 10000, use the following formula: (3) When Re3 > 10000, use the following formula: Step 8: Calculate the heat transfer coefficient α4 of the outer circumferential joint of the tube side using the following formula (unit: W / m²). 2 .℃); Step 9: Calculate the heat transfer temperature difference ΔT2 (unit: °C) and the heat transfer coefficient K2 (unit: W / m²) using the following formulas. 2 .℃), Step 10: According to the structural design, first select a sleeve of length L. 0-1 (Generally, L is taken) 0-1 =L 0-0 The heat exchange area F2 (unit: m) is then calculated using the following formula. 2 ), Total casing length L2 (in meters), Number of casings N 0-1 (dimensionless) (III) Calculation method for the air resistance of the sterilizer: Step 1: First determine the original operating parameters according to the structure: the total number of elbows N1 (dimensionless) in the tube side of the heat exchange section and the cooling section, the elbow resistance coefficient ξ1 in the tube side, the number of annular gap turns N2 (dimensionless) in the heat exchange section, and the annular gap turn resistance coefficient ξ2. Step 2: Calculate the frictional resistance coefficient λ of the heat exchange section tubes based on the parameters determined in Step 1. n1 The frictional resistance coefficient λ of the cooling section tubes n3 (dimensionless), frictional resistance coefficient λ of the heat exchange section annular seam t2 (dimensionless), tube-side air friction resistance ΔPzn (unit Pa), heat exchange section annular gap air friction resistance ΔPzt (unit Pa), Step 3: According to the parameters determined in Step 1, calculate the total elbow resistance coefficient ∑ξ1 (dimensionless), the annular gap turn resistance coefficient ∑ξ2 (dimensionless), the local resistance ΔPznjb (unit: Pa) in the tube side, and the local resistance ΔPztjb (unit: Pa) in the annular gap according to the following formula: ∑ξ1 ＝ N1×ξ1 ∑ξ2 = N2 × ξ2 Step 4: Calculate the total air resistance ∑ΔP (unit: Pa) of the sterilizer according to the following formula: ∑ΔP = (ΔPzn + ΔPzt + ΔPznjb + ΔPztjb) × 1.2 Step 5: Check the total air resistance ∑ΔP (unit: Pa) of the sterilizer. If the total air resistance ∑ΔP of the sterilizer < 2% × P1, the selected tube material specification meets the requirements. If ∑ΔP ≥ 2% × P1, according to Step 3 in the calculation method of the heat exchange section, re-select the tube material specification and recalculate until the requirements are met. (IV) Calculation method for the residence time in the heating section: Step 1: First select the outer diameter Dtw (unit: m), the wall thickness δt (unit: m), and the length H (unit: m) of a certain specification of the heating outer tube. Step 2: Based on the parameters determined in Step 1, calculate the internal volume Vt of the heating outer tube (unit: m³) using the following formula. 3 ), Step 3: Calculate the air residence time T (unit: s). Step 4: Check the air residence time T (unit: s). If the air residence time T > 10 s, the volume of the heating outer tube meets the requirements.

Images