Application of drying oven in agriculture
The processing of many pesticides can not be separated from drying oven, and the high requirement of pesticide dosage form also brings new development space to air circulation oven. In the past, the pesticide industry mainly use drying oven, drying room and other static drying, then break into powder after drying. Not only the production conditions were very bad, the use of drugs and the effectiveness were limited. Using new drying methods and new drying technology will play a very important role in the development of new pesticide formulations.
The characteristics of pesticide drying
Pesticide drying and other chemical products drying has many differences. First, the dosage form of pesticide is more, in addition to liquid dosage form, solid dosage form has powder, granular, block, strip, flake. For pesticides, drying is not only evaporation of water, but also the formation of different solid forms in the drying process, but also to ensure the role of drugs, so the drying process is also the process of dosage form manufacturing. Therefore, the drying equipment used is more complex. Secondly, toxic and taste are the basic characteristics of pesticide products, and the safety protection of drying field workers is very important.
The discharge of gas during drying operation should also be strictly controlled. For example, efficient herbicide drying, if there is farmland around the production site to ensure the safety of crops. After drying, the economical heat source is chosen as far as possible, especially the pesticide with low added value should control the production cost.
There are two main parts of drying, one is the drying of pesticide processing aids and fillers, the other is drying in the preparation process to obtain the final product.
Because the moisture content of pesticide products is strict and the moisture content of fillers directly affects the quality of products, the drying of fillers is also an important link in the processing of pesticide powder. Because of the large amount of pesticide, considering the product price, the filler of pesticide powder is mainly clay, clay, kaolin, silica and other minerals. For this reason, the pesticide drying equipment basically uses convection drying, and mainly to rotary dryer, box dryer, airflow dryer, shaft kiln and so on. With the improvement of preparation technology, spray dryer and other equipment began to be equipped in pesticide production. Rotary fast dryer, blade dryer has also been used.
Hot air oven for pesticide production
Benchtop and floor-standing air blasting oven is one of the most used drying equipment in pesticide factory. Box type drying oven is,small investment, easy operation, convenient variety replacement and small tail gas treatment capacity. Suitable for small batch, regular variety change, intermittent production occasions. However, it belongs to static intermittent drying, the traditional equipment has poor working conditions, large labor intensity and long production cycle. Although the operating temperature is not high, it is easy to overheat the dry material because the material is subjected to the same temperature for a long time. General products after drying but also after crushing, also not suitable for the production of large tonnage products. Box dryer also has two types of parallel flow and through flow. The former is mainly used for drying paste materials, and the flow box dryer is mainly dried by hot air through the surface of wet materials. When the hot air passes through the wet material surface, the surface material is heated and the moisture vaporizes first. Due to the humidity difference inside and outside the material, the internal moisture moves to the outside and vaporizes, repeating the above process to dry the material. Through flow box dryer is hot air vertical through the material, mainly used for block and granular material drying. Compared with the parallel flow box dryer, the drying time is shorter and the production efficiency is higher. Most pesticide plants use the method of placing the tray on the steam pipe, turning the material manually at regular time, and heating and drying under static condition. This method must have high labor intensity, more importantly, the inhomogeneity of material drying is inevitable, the product quality can not be guaranteed, and the energy loss is very large. The thermal efficiency of this box dryer is not more than 20%.
In recent years, the drying oven manufacturer have carried on the technical transformation to the box type precision oven, mainly has made the improvement in the following several aspects.
First, the tray of box dryer adopts cart type, and multi-layer tray is placed on the cart, which improves the working efficiency and reduces the labor intensity.
Secondly, using forced hot air circulation, the temperature in every corner of the dryer is basically the same, which not only ensures the uniformity of moisture and quality of the product, but also greatly improves the working efficiency and thermal efficiency. Although the box drying oven is the original, old drying equipment, but also practical can not be eliminated, it has other drying equipment incomparable advantages.
Therefore, although many new drying devices have been developed, there is still no sign of withdrawal. The automatic temperature regulating system and ventilation system of box dryer should be further developed. The gas relative humidity measuring instrument is installed at the outlet of the gas discharge, and some hot air circulation is adopted to correct its shortcomings as far as possible, so that this old equipment can play a new role.