Buy the fluid bed dryer should consider several important issues
1, the final moisture content
Segments are generally dry in the falling rate drying stage, the lower final moisture content, drying more difficult it becomes, the longer the drying time required, the lower the thermal efficiency, and therefore also affect the production requirements.
2, the material form
Boiling dryer selection is based mainly be dried material in the form to determine the form of materials not only to determine their dry way, while the drying efficiency of the fluid bed dryer, drying quality, uniform drying and into the discharge device has a significant effects, therefore, as the process allows the dry materials should be taken of crushing, screening, chopped pretreatment. Drying equipment is not just a selection, but also should develop the drying process of science, in order to achieve satisfactory results.
(3) hot air temperature
The hot air temperature or the drying medium temperature, is one of the most sensitive to drying conditions. The hot air temperature is higher, it contains more heat, while the relative humidity of hot air, the lower absorption of water, the stronger the ability to carry water is very beneficial to dry, and dry thermal efficiency is also high. Dehydration basic other things being equal, fluid bed dryer with hot air temperature is proportional to the changes in the number of drying equipment. The choice of drying equipment, we must limit temperature of the destruction of the material have sufficient data in the case of the material allows, try to select the high-temperature media. Should be noted that many types of drying methods, in particular, is fast drying, after drying the material temperatures much lower than the temperature of the drying medium such as air flow to the fluid bed dryer hot air temperature up to more than 250 ℃, out of the material temperature were 60 ° C below.
(4) environmental temperature and humidity
Here mainly refers to the drying effects of weather changes, and general fluid bed dryer drying medium, the higher the temperature of the atmosphere are based on atmospheric heating, the lower the humidity, the more conducive to dry, while the southern spring and summer rain, wet , air humidity is not conducive to the ability to play fluid bed dryer, affecting production.
China has a vast, North and South air humidity vary widely. Some places in the south, the winter the humidity is only 0.008 kg water / kg oven dry air to the spring and summer, the atmospheric humidity of up to 0.025 kg water / kg oven dry air is more than three times of the former, therefore, in a relatively low exhaust gas temperature (<90 ° C) operating under the hot air drying in the spring and summer when increased atmospheric humidity, the drying rate is bound to decline, while the time required will rise. Due to the increase of atmospheric humidity, the equilibrium water content of the material is bound to rise, these factors will enable dry decline, in some cases cause the decline more than 50%.
(5) fluid bed dryer capacity factors
Due to the same kinds of drying methods, drying and dehydration of one kg consumed by the heat is basically the same fluid bed dryer of the supporting capacity of the heat source (hot air furnace, steam radiators, etc.) is certainly the major technical indicators fluid bed dryer - drying capacity often based on hourly dehydration (dehydration). This indicator is measured under certain conditions, such as wet type of material, the initial moisture content, final moisture content, air temperature, environmental temperature and humidity and so on. As long as there is a condition change has an impact on the capacity of the fluid bed dryer, and sometimes also a larger impact. The following description.
(1) wet type of material
Types of wet material here is in the form of combination of materials and water. The wet material can be divided into ① capillary porous materials, moisture depends mainly on the capillary force together in the materials such as sand, silica, activated carbon, unglazed ceramic, the bonding strength of water and materials smaller, dry more easily; 2 colloid dominant penetration combination in the form of materials, water and materials, such as glue, dough, this material is the general performance of the viscosity, water and materials bond strength, drying more difficult; ③ capillary porous colloidal materials, the nature of the above two types of substances, such as peat, clay, wood, fabric, grain, leather and other such type of material up to, but the combination in the form of such materials between the water makes a difference, determines the ease of dehydration under the same conditions not the same.
The shape of the material has a great influence on the drying particulate materials, particle a majority particles is small and difficult to dry, while the large piece of material, the thickness of the small thickness is large and easy to dry.
(2) The moisture content of wet material
The moisture content (moisture content) is the moisture percentage of the total weight of the wet material.
m = W × 100 =
W × 100 (%)
G Go + W
Where: W - weight of water;
G - wet weight of materials;
G 0 - oven dry material weight.
The initial moisture content is dry before you enter the boiling water content of wet material, usually wet material in boiling dryer, the higher the initial moisture content, boiling dryers, dehydration ability to play the more sufficient. Conversely, the higher the initial moisture content, final moisture content when the fluid bed dryer the more it can reach the maximum dehydration, but a dry feeding amount worse. |
Select the boiling dryer should be considered