The discharge of fly ash can be divided into two types: dry and wet. Dry ash disposal can be made by comprehensive utilization of separation and grinding process; wet ash disposal is first dried and then separated and finely ground. The system is flexible in layout, simple in equipment and easy to control. Thus, the zero emission of coal ash in power plant is realized, and the comprehensive utilization project of fly ash has obvious economic and social benefits, which is widely popularized and used for reference for the wet ash discharge and dry ash discharge of the boiler in the power plant.

First, an overview
Fly ash is the largest industrial waste residue. The comprehensive utilization of fly ash is of great significance to China's economy and environment. The discharge of fly ash can be divided into two types: dry and wet. At present, the domestic utilization of fly ash is mainly to dry fly ash with relatively high price, and dry ash can be comprehensively utilized by separating and grinding technology. Because of the high moisture content, small proportion and low utilization rate of wet ash, it is necessary to use huge capital to build up the yard every year. It not only takes up the good field, but also is very easy to raise the dust, seriously pollute the environment, and the development and utilization of wet ash can not be delayed. If it can be used directly, it will produce great social benefits. After years of practice in the Institute of scientific research and design and the fly ash treatment professional units, the process of drying and sorting wet ash before drying is used, not only to ensure the quality of different kinds of fly ash in power plants, but also to broaden the development and utilization of fly ash more effectively, improve the use grade of fly ash, and further improve the enterprise  Economic and social benefits. A
Two, fly ash drying system
According to the characteristics of high moisture content of wet ash, small proportion and suspension after drying, the three layer drum type energy saving dryer for fly ash is developed, which consists of three parts: heating system, heat exchange system, ventilation and dust removal system. And combine the three together, give full play to its best drying effect, greatly improve the utilization rate of heat energy, and truly realize energy saving, high production and consumption reduction. This machine is widely used in power plant fly ash, desulphurization gypsum, cement plant slag, clay, building materials and other industries. The output is 10-50t/h. Pretreatment: the wet discharge of fly ash from power plants is generally about 45%. If direct drying is done at this time, the production cost will be greater, and the equipment will also be under great pressure. It can be stacked for about 15 days in a well ventilated place, so that the moisture content will drop to about 20%.  When the hot air temperature of the fluidized bed furnace reaches 650 degrees, the equipment will start working under the control system. The wet material conveying equipment will send the wet fly ash with the moisture content less than 20% into the feeding feeder. The feeding machine has double functions of breaking and transporting, making the material evenly distributed to the belt conveyor, then entering the storage bin, then passing the spiral feeder, and evenly sending the fly ash into the inner layer of the roller, so as to dry the material and make the material be dry. The material in the inner layer is moved into the middle layer at the other end of the inner layer, and the material is continuously drated into the middle layer, and the material is repeatedly carried forward in the middle layer. The material is in the two step backward way. The material absorbs the heat from the inner layer and absorbs the middle layer fully in the middle layer. The heat of the drum extends the drying time at the same time, and the material reaches the best drying state here. The material goes to the other end of the middle layer and falls into the outer layer. The material is moving in a rectangular multi loop way in the outer roller, and the drying material is rapidly moving out of the roller under the effect of hot air, and thus the drying process is completed.
Product features:
1, the self insulation heat efficiency of the cylinder is as high as 80% (the thermal efficiency of the traditional single dryer is only 35%), and the thermal efficiency is increased by 45%.
2, fuel can adapt to coal, oil and steam. Bulk, granular and powdery materials that can bake below 20mm
3, compared with the single cylinder dryer, it has reduced the area occupied by 50%, the civil construction investment has decreased by about 50%, and the electricity consumption is less than 60%.
4, the use of alloy steel manufacturing than ordinary steel plate wear resistance 4 times.
5, according to user requirements, we can easily control the final water requirement.
6, the outlet temperature is low, and the dust removal equipment is used for a long time.
7, no need for small and large gears to rotate.
8, discharging temperature below 60%, continuous production of packaging drum dryer main technical parameters: can be re designed according to customer requirements.
Three. Separation and grinding process of fly ash
The system is directly from the original ash bin to take the ash, through the spiral feeder, the electronic weighing is transported into the grinding head hoist after the weight of the air slots, and the hoist is fed into the pulverized machine for the grinding. The coarse ash after the separation is sent into the mill inlet through the air inclined trough and enters the grinding mill. The material is contained in the grinding machine after the mill. A large number of fine ash, once again fed by the hoist to the selected powder separator, is sent to the finished ash bank through the follow-up equipment, and the tail of the mill is equipped with a dust collecting system to collect dust. Compared with the open road (no separator) system, the output of the fine ash can be increased by 30 to 40%.
Ash reached the standard of grade I ash, and the fine ash fineness was less than 12% (0.045mm square hole sieve residue).
Precautions for matching reconstruction
1. When the special classifier for fly ash is used, the mill must be adjusted at the same time.
A, the grinding machine is adjusted to three silos, subdividing the crushing, crushing and grinding functions to three storehouses, reducing the phenomenon of grinding and breaking the grinding function, improving the working conditions in the grinding and eliminating the anti classification of the grinding body at the same time.
B, one or two storehouse and two or three storehouse are used by our company to produce a double screen separating plate device for closed mill. The sieving seam between the one or two storehouses is 4mm, and the sieving seam of the two or three storehouse is 2.5mm. (our company provides manufacturing drawings or substitute for processing).
Use of C and grate grate