I. Overview
At present, the soft capsule drying technology has the following types: 1 cage drying, 2 crawler drying 3 static tray drying. Since the static tray drying technology has the advantages of ensuring the softness of the surface of the soft capsule and no damage rate, it is a trend to compare the static tray drying technology after four or five years of practical experience. Because the drying of materials is only related to the four elements of temperature, humidity, wind speed and evaporation rate of the air. Due to the self-factor of the soft capsule, the drying temperature cannot be too high, so in order to improve the production efficiency, it is only necessary to reduce the air humidity and increase the number of air changes in the drying chamber.
In order to ensure the temperature, humidity, cleanliness, large number of air changes in the drying chamber of the soft capsule, and in accordance with GMP standards, an artificial environment must be created to meet the requirements of the above four parameters.
How to select the rotary dehumidifier in soft capsule drying application
Second, the design of soft capsule drying room
The drying room area is 52m2, the height is 3m; the soft capsule is about 350kg; the drying time is 35-40 hours; the cleanliness is 100,000; the room temperature is 18-25°C, the humidity requirement is 20%-30%; The temperature is 35 ° C, the wet bulb temperature is 28 ° C; the air supply mode is sent up and down; the staff is up to 4; there is no other wet source.
Third, the selection of dehumidifier
(1) Determine the air supply volume of the drying room: According to the relevant section of the air purification and clean room of the Air Conditioning Design Manual, when the cleanliness is 100,000, the number of room air changes is designed to be no less than 15 times/hour. The design was carried out 20 times per hour. The air supply amount L = 20 V = 20 × 52 × 3 m 2 / h = 3120 m 3 / h. There are also users who increase the number of air changes to 30 times/hour in order to improve the drying efficiency.
(2) Calculate the amount of moisture in the drying chamber: Check the "Air Conditioning Design Manual" to know that at room temperature 22 ° C, light labor intensity, adult's moisture capacity is 150g / h, indoors up to 4 people work, that is, in the room The maximum amount of moisture in the human body is 600g/h. Due to the different varieties of soft capsules, their own volatilization rate is also different, and the amount of moisture is actually variable. Therefore, this example is designed on the premise of not putting glue in summer. The soft capsule manufacturer should make an experiment to determine which kind of temperature and humidity conditions the drying effect of the product is faster and the effect is good, so as to finally determine the unit dehumidification amount of the air supply.
(3) Determine the temperature and humidity of the air supply: Because there is no heat source in the room, and there is no other wet source other than the four staff members, the intermediate value required by the room is taken as the final design goal, that is, the temperature is 22 ° C and the humidity is 25%. Considering the temperature rise of the blower at 5 °C, it is appropriate to check the relevant manual and take the supply air temperature at 17 °C. After deducting the amount of moisture per hour of the human body, the moisture content of the air supply should be no more than 3.8g/kg dry air.
(4) Determine the amount of fresh air: According to the "Air Conditioning Design Manual", determine the fresh air volume of the clean room should take the maximum of the following three conditions: 1 to ensure positive pressure in the room; 2 to ensure that the average per capita oxygen per worker per hour is not Less than 45 cubic meters; 3 take 10% of the total air supply. In the summer, when the soft capsules are dry, the fresh air volume should be minimized because the fresh air contains too much water. In order to avoid the penetration of the outdoor wet load into the room, the positive pressure in the drying chamber should be ensured. When the fresh air volume is 1 to 2 times the number of air changes in the room, the positive pressure difference of 5 to 10 Pa can be maintained indoors. For this example, we take a supplemental fresh air volume of 300m3/h.
(5) Selection of dehumidifier: The dehumidification method of general air conditioner compressor can only reduce the air dew point temperature to 10 °C, and the dew point temperature of the soft capsule drying chamber needs to reach below 1 °C, so it is impossible to use the general freezing and dehumidification method. Meet the production process requirements. The combination of an air conditioning refrigeration and a rotary dehumidifier can easily reduce the air dew point to -40 °C.
How to select the rotary dehumidifier in soft capsule drying application
(6) Selection of cooling mode for air conditioning: Water-cooled chillers are suitable for large rooms of 1000 square meters or larger, or large systems, and cost-effective; for small rooms of 200 square meters or less, air-cooled pipe machines have more Many advantages, such as simple operation, easy maintenance, no need for water source and so on. The drying chamber of this example is suitable for air-cooled pipe machine
(7) Selection of regeneration mode of rotary dehumidifier: At present, there are two types of regeneration modes of rotary dehumidifier, namely electric heating and steam heating. The gauge pressure of steam heating shall be not less than 4 kgf/cm2. When steam heating regeneration mode is selected, it is better to choose high temperature resistant solenoid valve, which not only can realize self-control to save energy, but also prolong the service life of dehumidification runner. When the actual air volume of the dehumidifying drying wheel is less than 2000m3/h, the electric heating regeneration method is simpler and more labor-saving.
(8) Selection of the refrigerating machine before dehumidification runner: The air temperature after mixing fresh air 300m3/h and return air 2820m3/h is 23°C, and the air moisture content is 5.8g/kg dry air. Under the premise of ensuring that the moisture content of the air is constant, the lower the air temperature of the dehumidification wheel, the better the dehumidification effect of the dehumidification wheel. We are based on this principle by reducing the air after mixing to 10 ° C and then feeding it to the dehumidification wheel. According to the relevant thermal formula, the front refrigerator needs a cooling capacity of 13.52KW, thus selecting the refrigerator.
(9) Selection of dehumidification drying wheel: Check the technical manual of the dehumidifier of our factory. When the inlet air temperature is 10 °C and the air moisture content is 5.8g/kg dry air, it is processed by the silica gel runner with the specification of φ770×200. After that, the air content of the air is 1.2g/kg dry air, which is far lower than the requirement of 3.8g/kg dry air of the air supply. The dehumidification wheel of this specification is too large. In order to save energy and initial investment, we appropriately select the small dehumidification wheel such as φ550×200 for check calculation. The rated air volume of φ550×200 is 1500m3/h, so another 1620m3/h of air needs to be bypassed. The air moisture content after mixing is 3.5g/kg dry air, which is close to the requirement of air supply moisture content of 3.8g/kg dry air. Therefore, this type of dehumidification runner is selected.
(10) Selection of chiller after dehumidification runner: The air temperature after dehumidification runner is 23 °C, the moisture content is 3.5g/kg dry air, the air supply temperature is 17 °C, according to the relevant thermal formula calculation, refrigeration is required. The amount of 7.28KW, thus selecting the refrigerator
(11) Filter selection: According to the actual situation of the project, the primary effect and medium efficiency filter are selected.
(12) Selection of fan: Calculate each filter, front and rear chiller evaporator, dehumidification runner,
The total resistance of the air return pipe and the high-efficiency air supply port is not less than 1200Pa. Check the performance curve of the 4-72-3.6A blower. When the air supply volume is 3120m3/h, the total pressure is 1500Pa, and the total system residual pressure is 300Pa. small. In order to ensure the air supply volume, increase the wind pressure, and improve the drying efficiency of the soft capsule, a low-noise full-pressure 500Pa air-conditioning fan is connected in series.
(13) Control selection: After comparing the traditional experience of traditional relay contact control, single-chip control and PLC control, it is determined that the rotary dehumidifier adopts PLC control. It has the following major advantages: 1 high reliability, strong anti-interference ability; 2 can realize the integration of electric control, electric meter and electric junction; 3 simple programming, convenient use, variable control program, good Flexible one; 4 small size, light weight, low power consumption. In order to achieve remote monitoring, you can also choose touch screen or PC microcomputer control.
Fourth, the conclusion
After the above-mentioned thirteen steps of calculation and consideration, a tailor-made soft capsule drying dehumidification air conditioner purification unit has been selected. The outer casing of the integrated unit should be insulated. At present, various manufacturers generally use 50mm original sandwich panels. The insulation layer is made of polyethylene foam and polyurethane foam. Among them, polyurethane foam can withstand high temperature, but its price is twice that of polyethylene foam.
References: "Air Conditioning Design Manual", Editor-in-Chief of the Tenth Design and Research Institute of the Ministry of Electronics Industry; Shanghai Zhongyou Industrial Co., Ltd. "Technical Manual for Rotary Dehumidifier", etc.
At present, the soft capsule drying technology has the following types: 1 cage drying, 2 crawler drying 3 static tray drying. Since the static tray drying technology has the advantages of ensuring the softness of the surface of the soft capsule and no damage rate, it is a trend to compare the static tray drying technology after four or five years of practical experience. Because the drying of materials is only related to the four elements of temperature, humidity, wind speed and evaporation rate of the air. Due to the self-factor of the soft capsule, the drying temperature cannot be too high, so in order to improve the production efficiency, it is only necessary to reduce the air humidity and increase the number of air changes in the drying chamber.
In order to ensure the temperature, humidity, cleanliness, large number of air changes in the drying chamber of the soft capsule, and in accordance with GMP standards, an artificial environment must be created to meet the requirements of the above four parameters.
How to select the rotary dehumidifier in soft capsule drying application
Second, the design of soft capsule drying room
The drying room area is 52m2, the height is 3m; the soft capsule is about 350kg; the drying time is 35-40 hours; the cleanliness is 100,000; the room temperature is 18-25°C, the humidity requirement is 20%-30%; The temperature is 35 ° C, the wet bulb temperature is 28 ° C; the air supply mode is sent up and down; the staff is up to 4; there is no other wet source.
Third, the selection of dehumidifier
(1) Determine the air supply volume of the drying room: According to the relevant section of the air purification and clean room of the Air Conditioning Design Manual, when the cleanliness is 100,000, the number of room air changes is designed to be no less than 15 times/hour. The design was carried out 20 times per hour. The air supply amount L = 20 V = 20 × 52 × 3 m 2 / h = 3120 m 3 / h. There are also users who increase the number of air changes to 30 times/hour in order to improve the drying efficiency.
(2) Calculate the amount of moisture in the drying chamber: Check the "Air Conditioning Design Manual" to know that at room temperature 22 ° C, light labor intensity, adult's moisture capacity is 150g / h, indoors up to 4 people work, that is, in the room The maximum amount of moisture in the human body is 600g/h. Due to the different varieties of soft capsules, their own volatilization rate is also different, and the amount of moisture is actually variable. Therefore, this example is designed on the premise of not putting glue in summer. The soft capsule manufacturer should make an experiment to determine which kind of temperature and humidity conditions the drying effect of the product is faster and the effect is good, so as to finally determine the unit dehumidification amount of the air supply.
(3) Determine the temperature and humidity of the air supply: Because there is no heat source in the room, and there is no other wet source other than the four staff members, the intermediate value required by the room is taken as the final design goal, that is, the temperature is 22 ° C and the humidity is 25%. Considering the temperature rise of the blower at 5 °C, it is appropriate to check the relevant manual and take the supply air temperature at 17 °C. After deducting the amount of moisture per hour of the human body, the moisture content of the air supply should be no more than 3.8g/kg dry air.
(4) Determine the amount of fresh air: According to the "Air Conditioning Design Manual", determine the fresh air volume of the clean room should take the maximum of the following three conditions: 1 to ensure positive pressure in the room; 2 to ensure that the average per capita oxygen per worker per hour is not Less than 45 cubic meters; 3 take 10% of the total air supply. In the summer, when the soft capsules are dry, the fresh air volume should be minimized because the fresh air contains too much water. In order to avoid the penetration of the outdoor wet load into the room, the positive pressure in the drying chamber should be ensured. When the fresh air volume is 1 to 2 times the number of air changes in the room, the positive pressure difference of 5 to 10 Pa can be maintained indoors. For this example, we take a supplemental fresh air volume of 300m3/h.
(5) Selection of dehumidifier: The dehumidification method of general air conditioner compressor can only reduce the air dew point temperature to 10 °C, and the dew point temperature of the soft capsule drying chamber needs to reach below 1 °C, so it is impossible to use the general freezing and dehumidification method. Meet the production process requirements. The combination of an air conditioning refrigeration and a rotary dehumidifier can easily reduce the air dew point to -40 °C.
How to select the rotary dehumidifier in soft capsule drying application
(6) Selection of cooling mode for air conditioning: Water-cooled chillers are suitable for large rooms of 1000 square meters or larger, or large systems, and cost-effective; for small rooms of 200 square meters or less, air-cooled pipe machines have more Many advantages, such as simple operation, easy maintenance, no need for water source and so on. The drying chamber of this example is suitable for air-cooled pipe machine
(7) Selection of regeneration mode of rotary dehumidifier: At present, there are two types of regeneration modes of rotary dehumidifier, namely electric heating and steam heating. The gauge pressure of steam heating shall be not less than 4 kgf/cm2. When steam heating regeneration mode is selected, it is better to choose high temperature resistant solenoid valve, which not only can realize self-control to save energy, but also prolong the service life of dehumidification runner. When the actual air volume of the dehumidifying drying wheel is less than 2000m3/h, the electric heating regeneration method is simpler and more labor-saving.
(8) Selection of the refrigerating machine before dehumidification runner: The air temperature after mixing fresh air 300m3/h and return air 2820m3/h is 23°C, and the air moisture content is 5.8g/kg dry air. Under the premise of ensuring that the moisture content of the air is constant, the lower the air temperature of the dehumidification wheel, the better the dehumidification effect of the dehumidification wheel. We are based on this principle by reducing the air after mixing to 10 ° C and then feeding it to the dehumidification wheel. According to the relevant thermal formula, the front refrigerator needs a cooling capacity of 13.52KW, thus selecting the refrigerator.
(9) Selection of dehumidification drying wheel: Check the technical manual of the dehumidifier of our factory. When the inlet air temperature is 10 °C and the air moisture content is 5.8g/kg dry air, it is processed by the silica gel runner with the specification of φ770×200. After that, the air content of the air is 1.2g/kg dry air, which is far lower than the requirement of 3.8g/kg dry air of the air supply. The dehumidification wheel of this specification is too large. In order to save energy and initial investment, we appropriately select the small dehumidification wheel such as φ550×200 for check calculation. The rated air volume of φ550×200 is 1500m3/h, so another 1620m3/h of air needs to be bypassed. The air moisture content after mixing is 3.5g/kg dry air, which is close to the requirement of air supply moisture content of 3.8g/kg dry air. Therefore, this type of dehumidification runner is selected.
(10) Selection of chiller after dehumidification runner: The air temperature after dehumidification runner is 23 °C, the moisture content is 3.5g/kg dry air, the air supply temperature is 17 °C, according to the relevant thermal formula calculation, refrigeration is required. The amount of 7.28KW, thus selecting the refrigerator
(11) Filter selection: According to the actual situation of the project, the primary effect and medium efficiency filter are selected.
(12) Selection of fan: Calculate each filter, front and rear chiller evaporator, dehumidification runner,
The total resistance of the air return pipe and the high-efficiency air supply port is not less than 1200Pa. Check the performance curve of the 4-72-3.6A blower. When the air supply volume is 3120m3/h, the total pressure is 1500Pa, and the total system residual pressure is 300Pa. small. In order to ensure the air supply volume, increase the wind pressure, and improve the drying efficiency of the soft capsule, a low-noise full-pressure 500Pa air-conditioning fan is connected in series.
(13) Control selection: After comparing the traditional experience of traditional relay contact control, single-chip control and PLC control, it is determined that the rotary dehumidifier adopts PLC control. It has the following major advantages: 1 high reliability, strong anti-interference ability; 2 can realize the integration of electric control, electric meter and electric junction; 3 simple programming, convenient use, variable control program, good Flexible one; 4 small size, light weight, low power consumption. In order to achieve remote monitoring, you can also choose touch screen or PC microcomputer control.
Fourth, the conclusion
After the above-mentioned thirteen steps of calculation and consideration, a tailor-made soft capsule drying dehumidification air conditioner purification unit has been selected. The outer casing of the integrated unit should be insulated. At present, various manufacturers generally use 50mm original sandwich panels. The insulation layer is made of polyethylene foam and polyurethane foam. Among them, polyurethane foam can withstand high temperature, but its price is twice that of polyethylene foam.
References: "Air Conditioning Design Manual", Editor-in-Chief of the Tenth Design and Research Institute of the Ministry of Electronics Industry; Shanghai Zhongyou Industrial Co., Ltd. "Technical Manual for Rotary Dehumidifier", etc.
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