Three Pass Dryer

Three pass rotary dryer

Three pass rotary dryer can be used for saw dust,wood chips,straw,wood sheaving, Medicago sativa, Cassava, Distillers' grains, herb,etc
The dryer use the furnace that has different stages, the efficiency for the heating is rising up 15%-20%, and the cost to dry is lowered down, the tense of the drying is 2 or 3 times than traditional dryer, and the length of the drum is 30%-40% shorter than the single pass, the occupation of the three pass dryer is 65% lower than the single pass dryer.

1. Philosophy for the three pass dryer

Three pass dryer is composed of three drum, the material flow as follows: Inner drum-->middle drum--->outter drum, every drum has the special shape of material guiding plate, the material is moved by the rotary force from drum and the attrative force from hot air.

2. The working status for dryer:

AB: pre-heating stage, material is transfered to the dryer, since the hot air, the temperature of material is rising up the wet ball, at this stage, the moisture inside the material is stable, and the temperature of hot air is dropping down, the heat release from hot air is use to pre heat the wet material.
BC. drying at the same speed, the ratio of drying is stable, at this stage, the feasture of wet ball has free water to be evapourated by the heat transfered from the hot air so that the temperature is stable, but the temperature of hot air and the moisture of material is dropping down.

CD: The ratio of drying is dropping down, the spreading ratio of moisture inside the material is less than
Rate of Evaporation for the moisture, the surface of material do not have enough moisture, so the ratio of drying is slow down, the heat transferd to the material is high than the heat used to evaporate the moisture so that the temperature of material is rising up and the temperature of hot air is dropping down.

DE, The moisture of material is lowered down the request and the material is released from the dryer to cooling system to make sure the temperature of material is a little high than ambient and pack it up.

3. specification of three pass dryer:

Heat Exchange——Agent for drying is hot air
Model	HTG-600			HTG-1200			HTG-2400			HTG-4800			HTG-8000
Moisture erase	600			1200			2400			4800			8000
Primary moisture	70%	60%	50%	70%	60%	50%	70%	60%	50%	70%	60%	50%	70%	60%	50%
Final moisture	10%			10%			10%			10%			10%
Capacity(dryed)	300--800			600--1500			1200--3000			2400--6000			4000--10000
kgs/h
Coal consumption	500	320	240	500	320	240	500	320	240	500	320	240	500	320	240
Kgs/t
Electricity consumption	37			72.1			98.7			131,6			168
Output	45			95			130			175			220
Outter dimension(m)	3265			3476			3697			38107			50108
Area	500			500			600			600			800

Direct Heating ——agent is high temperature cleaned bluegas

Model	HTG-900			HTG-1800			HTG-3600			HTG-4800			HTG-5400			HTG-8000
Moisture erase	900			1800			3600			4800			5400			8000
Primary moisture	70%	60%	50%	70%	60%	50%	70%	60%	50%	70%	60%	50%	70%	60%	50%	70%	60%	50%
Final moisture	10%			10%			10%			10%			10%			10%
Capacity(dryed)	300--800			600--1500			1200--3000			2400--6000			2700-6000			4000-10000
kgs/h
Electricity consumption	25			38			53			60			75			105
Coal consumption	400	250	200	400	250	200	400	250	200	400	250	200	400	250	200	400	250	200
Kgs/t
Output	37			54			75			110			128			150
Outter dimension M	24×6×5			26×8×7			30×9×8			32×10×9			36×12×10			40×12×12

Item	Reference 1	Reference 2
Material dried	Wood sheaving	Wood chips
kg/h	8000	2500
Inlet hot air℃	550-600	360-400
Outlet hot air℃	110-125	130
Speed of drum rpm	5.5	5.5
Introduction fan kw	125	55
Output for dryer kw	13	8
Air capacity m³/h	60000	27000
Lenght of drier m	10	9
Diameter of dryer m	3.4	2.2