|At present, a food processing technology is an important development trend is maximally keep food nutrition and flavor, and the drying process and equipment selection has a great influence on the nutrition, flavor and color of food products. Food drying characteristics associated with lots of "food", which is different from the chemical product drying, the former requires consideration of food hygiene, nutrition loss, color change and so on, there are strict limits on the drying temperature and time; the food drying and different from the pharmaceutical product drying, because food is often low value-added products, and the drug is generally high value-added products, the former must consider economic drying process. Around the "quality and economy", in recent years the food drying technique and equipment was made a lot of progress, and the vacuum and drying method or heating technology, gives new meaning and vitality of the vacuum dryer.
Characteristics of 1 food vacuum dryer
Vacuum dryer is a basic principle: Based on the saturated vapor pressure and temperature are closely related, in a vacuum, the boiling point of water is reduced, which is operating under vacuum is operating at low temperatures, at high temperatures can avoid nutrition vitamin destruction, at the same time, improve the drying speed. In addition, the vacuum system, the unit volume of air content is lower than the content in the atmosphere, in which the relative hypoxia environment food drying can reduce or even avoid the oxidation of the opportunity of fat in foods, pigment browning or other oxidative deterioration, so the vacuum drying to obtain better food quality.
2 traditional vacuum dryer
Vacuum drying in food, pharmaceutical, chemical and other industries has been widely used, the development and introduction of various vacuum dryer, the structure forms. Commonly used in the food industry in the form of main type, double cone vacuum dryer, vacuum belt drying machine. Vacuum dryer these traditional using hot air, steam or electric heating, the heat conduction, convection and radiation heat from the outside to the principle of material inside
How to carry out the adjustment of the equipment on vacuum dryer? The steps are as follows:
First, open the vacuum dryer power supply, the power indicator. (6090 and 6210 should be open temperature controller switch) temperature control instrument power-on self-test, PV screen display indoor temperature measurement, SV screen display factory set temperature. Temperature controller. AT and HEAT lamp lighting, said instrument enter the heating working condition.
Two, change the setting temperature:
1, press the function key control instrument (SET); PV display SP characters, use the arrow buttons to set the temperature changes (6090 and 6210 for 2 and 3 meters shall be respectively set modification, similar).
2, after modification, then press the SET key, PV screen display ST characters, setting time. If not using the timing function, still let it ST=0
3, then press the SET key, the PV screen display studio temperature, SV display temperature setting new. Instrument AT and HEAT lights, this instrument to enter the heating working condition.
4, if the studio vacuum dryer humidity, the moisture will affect the performance of the vacuum pump, vacuum dryer in between the chassis and a vacuum pump, a series of "vacuum dryer / filter".
5, if in the process of vacuum dryer goods, need to add nitrogen and other inert gas, should be specified in the contract, with an inlet valve.
Three, when the room temperature is close to the set temperature, the HEAT lamp flickered, said heating into the PID adjustment stage, instrument sometimes measuring temperature exceeds the set temperature, sometimes is lower than the set temperature is normal. When the temperature is close to or equal to the preset temperature, studio into the constant temperature state to stay 1~2h, items into the vacuum dryer stage.
Four, the temperature is low, can use two settings, such as the required working temperature is 70 ℃, 60 ℃ first set, etc. the temperature overshoot began to fall, second set at 70 ℃, which can reduce or even eliminate the temperature overshoot, thermostatic state as soon as possible.
Five, when the vacuum dryer after use, turn the power off, if the accelerated cooling, then open the bleeder valve so that the vacuum degree is 0, for 5 minutes and then open the door.