Dehydrated vegetables are dried vegetables made by using natural or artificial methods to remove some water from fresh vegetables. It basically maintains the original color of vegetables, taste and nutrients, edible convenience, because of less water, easy to transport, storage time is long, can adjust the light season of vegetable production, the main varieties of dehydrated vegetables have carrots, edible fungi, cabbage, cabbage and ginger, dry method has natural drying and Artificial dehydration two classes.
At present, China's dehydrated vegetable varieties, narrow scope, processing equipment lags behind foreign dehydrated vegetable industry, resulting in high processing costs, energy consumption, product quality is difficult to control the situation, seriously restricting the development of dehydrated vegetable industry. We learn from foreign advanced drying technology, according to the characteristics of dehydrated vegetables drying, the development of combined drying unit, in the dehydrated vegetable industry has been a good application.
First, the principle of design:
The initial water content of dehydrated vegetables is 75%-95%, for safe storage, the final moisture requirement is below 10%. Therefore, the whole drying time of dehydrated vegetables to undergo a typical heating stage, constant speed dehydration stage, spin-off phase, as shown in the following figure:
As can be seen from the above figure, during the entire drying process, the same time period of the required heat, air volume and drying medium penetration velocity is different. According to the characteristics of dehydrated vegetables to configure the drying line of heat, air volume and drying medium penetration velocity, to ensure maximum heat utilization, energy saving. As shown above, the final product volume accounts for only 30% of the raw material volume. Therefore, in the drying process, should choose the line of demarcation point, so that the smallest dry area can obtain the maximum load. In the process of processing different varieties of dehydrated vegetables, a variety of vegetables will have different characteristics, a good drying line requirements adaptable, flexible control, simple operation.
Second, the characteristics of the pipeline:
According to the dehydration rule of dehydrated vegetables, the pipeline can complete the drying operation by 3 units. The 1th unit is xinyu drying Equipment Co., Ltd. developed an improved GZQ fluidized bed dryer, 2nd and 3rd set using the company to improve the DWP type of flow conveyor belt dryer. In the 1th gzq type fluidized bed and 2nd DWP type Flow cycle belt dryer, the material heating up and constant speed drying stage is completed, and the 3rd type of DWP flow cycle belt dryer completes the spin-down drying section.
Dehydrated vegetables through the gzq type fluidized bed to complete most of the moisture quickly dry, improve drying efficiency and solve the problem of late drying of vegetable sticky nets, such as the need to achieve sulfur color protection, the latter type of DWP flow cycle belt dryer is composed of 5 drying units and a cooling unit, each Drying unit section includes a circulating fan, heating device, Fresh air Replenishment System, there is a common exhaust emission system, each drying unit independently control the air inlet, temperature, moisture and other drying elements.
After the material through the front process, into a fluidized bed dryer, after the rapid dehydration by vibration fluidization, after the discharge mouth into the lower feeder hopper, after the uniform material, the conveyor belt will be brought into the DWP dryer, the network belt running speed adjustable, cold air from the new wind to enter the centrifugal fan, After heating the fin-type heat exchanger (can also be used hot stove heating), into the dryer through the uniform wind growth plate spray through the material layer, and wet material full contact, heat exchange, moisture in the material is evaporated as water vapor, with the hot air to take away, part of the wet air from the wet mouth emptying, another part by the centrifugal fan, Cyclic use, according to the drying characteristics of dehydrated vegetables, each unit independently control drying elements to improve the drying strength, energy saving.
The pipeline solves the problem of sticky matter in the process of dehydrated vegetable processing , the whole drying process only 2~3.5 hours, shortens the drying time greatly, reduces the browning occurrence during vegetable processing, through fluidization, Jet flow, Sub-control temperature humidity, drainage and the recovery of the DWP exhaust gas, greatly improve the drying efficiency, energy saving and consumption.
Third, Operation points:
My company in the line of control with a large number of variable frequency, sensor and other electrical control technology. Different kinds of dehydrated vegetable varieties, dehydration speed is different (both drying time is different), in the whole drying process can be adjustable speed, gzq type fluidized bed by changing the mounting angle of the vibration motor to change the ejection angle and effective amplitude of the material to achieve change drying time, The DWP type flow cycle belt dryer changes the speed of the motor by changing the frequency of the main drive motor, which makes the drying time change to suit the drying requirements of different vegetables.
In the drying medium temperature and humidity control, the temperature using the popular thermocouple temperature sensor on the market as a temperature acquisition element, through the control of the solenoid valve and other flow control temperature control components. Exhaust system to the United States production of high-performance single-chip computer as the core, temperature sensor using the original Japanese temperature sensor for temperature compensation, humidity sensor imported high-precision humidity sensor, working in high humidity environment to ensure its sensitivity, according to humidity data to adjust the amount of moisture and the amount of recycled wind and cold air to achieve energy consumption.
Iv. Benefit Analysis:
the pipeline in many details of the optimization of drying parameters, such as thermal short-circuit waste, exhaust gas recycling, on-demand heating, etc., so the high rate of drying efficiency, dehydrated vegetables good quality, Xinyu Drying Equipment Co., Ltd. in Shanxi, Shandong and Zhejiang dehydrated vegetables customer testing, every 1 kilograms of the water loss of heat required about 4.5 million kj (different vegetables have differences), drying time only 2~3.5 hours. And the traditional baking road, baking pond, such as every 1 kilograms heat loss of 7500~11000 thousand Coke, drying time for 4-7 hours, large amount of artificial, drying quality by manual control, quality varies.
Take Nissan 5 tons dehydrated carrot granules as an example (at the same time can be processed chives, sweet pepper grains, green beans, long beans, evergreen, cabbage, etc.). Equipment model is dwp2-8-6-4 type, the installed capacity of 60.71 kw (after several measurements, the actual use only 48-kilowatt), coal consumption of 290 kilograms/hour, man-in-the-People/class. and traditional drying method processing 5 tons of dehydrated carrot granules, such as the use of baking pond, 20 baking pond, Installed capacity of 85-kilowatt, coal consumption of 400 kilograms/hour, artificial 10~12 person/class, if 1 years according to 6 months production, 1 years can save 396,000 yuan.
The key to the processing quality of dehydrated vegetables is in the drying process, and most of the cost is also in the drying process. The degree of automation and thermal efficiency of our company directly affect the market competitiveness of dehydrated vegetable processing enterprises, and also affect the process of industrialization of dehydrated vegetables.
CN