Haomai drying reminds you to pay attention to 14 points in purchasing rotary flash dryer
Haomai drying reminds you to pay attention to 14 points in purchasing rotary flash dryerPhysicochemical properties of materials to be dried
Material form, moisture content, water content, crystal water, particle size, bulk density, viscosity, heat sensitivity, softening point, phase change point, thixotropy, toxicity, corrosivity, peculiar smell, flammability, explosibility, static electricity, air permeability, agglomeration, crystal or particle grindability, etc., will affect the drying effect
Drying characteristics of materials
Drying curve, critical moisture content and equilibrium moisture content under the proposed drying conditions.
3. Drying output requirements and long-term planning.
4. The influence of commodity value and drying effect on it. Such as product moisture, pollution, temperature, wear, pulverization, comminution, rehydration On the value of goods.
5. Requirements for material recovery rate.
6. The upper and lower process of material drying process. (state method involving feeding and discharging)
7. Past drying methods of materials or similar products.
8. Available heat sources (coal, fuel oil, electricity, gas, liquefied gas, natural gas)
9. Whether there are special requirements for the installation site size of rotary flash dryer.
Environmental protection requirements for dust emission, noise, vibration, odor, volatile matter And so on.
11. The amount of possible purchase funds, local labor, land and energy prices.
12. Operator level and maintenance ability of dryer users.
13. Local environment temperature and humidity
Here mainly refers to the influence of weather changes on drying. Generally, flash dryer uses atmospheric heating as drying medium. The higher the temperature and the lower the humidity of the atmosphere, the more conducive to drying. However, in spring and summer in southern China, the rainy days are humid and the air humidity is high, which is not conducive to the exertion of dryer capacity and affect the output.
In some parts of the south, the humidity in winter is only 0.008kg water / kg absolutely dry air, but in spring and summer, the air humidity is as high as 0.025kg water / kg absolutely dry air, which is more than three times of the former. Therefore, when the air humidity is increased in spring and summer, the drying rate will inevitably decrease and the time required will increase. Due to the increase of atmospheric humidity, the balance water content of materials will inevitably increase. All these factors will reduce the drying output, and in some cases, the output will drop by more than 50%.
14. Factors affecting the production capacity of flash dryer
Due to the same drying method, the heat energy consumed by one kilogram of drying and dehydration is basically the same, and the capacity of heat source (hot blast stove, steam radiator, etc.) matched with the dryer is also certain. Therefore, the main technical index of the dryer drying capacity is often based on the hourly dehydration (or large amount of dehydration). This index is measured under certain conditions, such as wet material type, initial moisture content, final moisture content, hot air temperature, environmental temperature and humidity. As long as one of the conditions changes, the production capacity of the dryer will be affected, and sometimes the impact is greater. It is explained separately below.
(1) Types of wet materials
type of wet material, here refers to the combination form of material and moisture. Wet materials can be divided into: (1) capillary porous materials, moisture is mainly combined in materials by capillary force, such as sand, silica, activated carbon, plain fired ceramics, etc., the binding strength of water and materials is small, and drying is easy; 2) colloidal materials, the infiltration and combination form of moisture and materials are dominant, such as glue, flour dough, etc., this material generally has high viscosity and water (3) capillary porous colloidal materials have the properties of the above two kinds of materials, such as mud coal, clay, wood, fabric, grain, leather and so on. However, the water binding forms of these materials are also different. The causeway factory has decided that the difficulty of dehydration under the same conditions is not the same. < br > the form of materials also has a great influence on drying. For example, for granular materials, the larger particles are harder to dry than the smaller ones, while the larger ones are easier to dry than the larger ones.
(2) moisture content of wet material,
moisture content (wet content) is the percentage of moisture in the total weight of wet materials.
Where: W -- moisture weight;
g,, -- wet material weight;
G0 -- absolute dry material weight.
The initial moisture content refers to the moisture content of the wet material before entering the dryer. Generally speaking, as long as the wet material can work in the dryer, the higher the initial moisture content is, the more fully the dehydration capacity of the dryer is displayed. On the contrary, the higher the initial moisture content and the fixed final moisture content, the dryer can achieve greater dehydration capacity, but the output of dry material decreases.
(3) ^ final water content
Generally, the later stage of drying is in the stage of decreasing speed. The lower the final moisture content is, the more difficult it is to dry. The longer the drying time is, the lower the thermal efficiency is. Therefore, the output is also affected.
(4) hot air temperature
Hot air temperature or drying medium temperature is a sensitive pipe jacking condition in drying. The higher the temperature of hot air is, the more heat energy it contains. At the same time, the relative humidity of hot air is also lower, and the ability of absorbing and carrying water is stronger, which is very conducive to drying, and the drying thermal efficiency is also very high. In many drying equipment, when other conditions remain unchanged, the dehydration capacity of dryer is basically proportional to the change of hot air temperature. In the selection of drying equipment, it is necessary to have sufficient data on the limit temperature of damaged materials. If the materials are allowed, high temperature medium should be selected as far as possible. Special attention should be paid to many drying methods, especially rapid drying. The temperature of dried materials is much lower than that of drying medium. For example, although the hot air temperature of air dryer is higher than 250 ℃, the discharge temperature is generally below 60 ℃.
Changzhou Haomai drying Engineering Co., Ltd. is a professional manufacturer of flash dryer, which can provide professional optimization scheme for your design according to different conditions and production process. Welcome to contact us for consultation!