(1).Introduction

　　Paddle dryer (cooler) is a compact, indirect-heat equipment with high thermal efficiency. By mechanical structure, it is made up of top cover, rotating shaft, trough, dryer frame and driving unit. Paddle shaft is key part of the dryer, which consists of hollow shaft(s) and hollow blade with special flow channels. The trough is inclined to horizontal. Wet cake is fed into the inlet nozzle and transported to the outlet nozzle due to the rotation of shaft and gravity. Dried product is transported to downstream process after overflow the dam. The thermal is transferred to (or from) the material via hollow blade, hollow shaft and jacket to implement the purpose of heating or cooling.

　　Paddle dryer (cooler) is mainly used in process of drying, reacting, cooling, crystallizing, evaporating, sterilizing, low temperature roasting etc. for non heat-sensitive organic and inorganic products and heat sensitive products in vacuum condition. It can also be used for combined multi-application.

　　By heating medium, paddle dryer can be classified as steam type (saturated steam or superheated steam) and liquid type (water or oil, hot or cool). By operation method, it can be categorized into continuous and batch type. By the number of paddle shaft, it can be categorized into single shaft, twin-shaft and quad-shaft. By operating pressure, paddle dryer can be categorized into vacuum type, atmospheric type and pressurized type.

　　Usually two paddle shafts rotate in opposite directions as a coupled rotors. Specially designed paddles secures sufficient contact between the blade surface and the material. Owing to the wedged shaping of blade, material can be pressed and released alternatively in the axial direction, which makes paddle blades self-cleaning. Relative shear force between blades and material keeps blades clean for better heat and mass transfer.

　　(2).Features

　　Compact structure with large heat exchange surface and small installation space

　　Even distribution, high thermal efficiency, good drying effect

　　No adhere with self-cleaning wedge-shaped paddles

　　Low energy consumption and low operation cost Low dust and material loss

　　Indirect-heating (cooling), no contamination to product.

　　Simple control interface, flexile and reliable operation

　　Gas-tight for toxic and odorous products

　　Multifunction for different process

　　(2).Specifications

　　By heat-exchange area, there are specifications from 2 to 350m2, with shaft speed 5 to 20rpm. Hollow blades can be wedged or disk type. Customized design is available.

　　(4).Application

　　Paddle dryer (cooler) is widely used for the drying or cooling of slurry, powder, pellets, filter cake and other materials in petrochemical, inorganic chemical, metallurgy, architecture, environment, dye and colorants, foodstuff, pharmaceutical, sledge and etc, typical product application as below:

　　Petrochemical: polyolefin powder, high/low density polyethylene, linear low density polyethylene, Polyacetal, Nylon6, Nylon 66, acetate fiber, Poly-Phenylene Sulfide, PP based resin, PP, SAN, ABS, PVC, PS, PVA, molecular sieve, Catalyst, plastic additive

　　Environment: PTA sludge, pharmaceutical waste residue, surge factory residue, industry sludge, electroplating sludge, urban sewage, coal powder

　　Feedstuff: soy mill waste, bone feedstuff, brewery dreg, vinegar dreg, apple dreg, orange peel, bean dreg, fish powder, feed additive, bio-sludge

　　Foodstuff starch, coco bean, corn, salt, milk powder, sugar

　　Pharmaceutical: p-aminophenol, medicine

　　Chemical: active carbon, Calcium carbonate, magnesium sulfate, anhydrous sodium sulfate, titanium pigment, sodium hydrocarbon, potassium chloride, titanium tetrachloride, silicon carbide, sodium hydroxide, ferric oxide, Glauber's salt, sodium carbonate, nitrogen phosphorous potassium compound fertilizer, kaolin, bentonite, silica aerogel, carbon black, phosphogysum, magnesium carbonate, sodium fluoride, Aluminum hydroxide, barium sulfate, calcium sulfate, dyestuff and intermediate, molecular sieve, saponin

　　Architecture: gypsum, Calcium carbonate, tricalcium phosphate

　　Cooling: Sodium carbonate, nylon salt, phosphate salt, etc.

The main parameters