Rotary dryer design calculation for wood chips

Rotary Dryer Detailed Description:

Rotary Dryer from Qingdao Palet Machinery can reduce the biomass material moisture content from 40-55% to below 10% -15%, according to the customers’ request. How to choose the rotary dryer design for wood chips? We have finished a successful project for wood chips dryer in Malaysia.

How to calculate the dimension of the rotary dryer for wood chips?

The information as follows:

The material: wet wood chips, sawdust

The output: 3ton per hour

A：Drying intensity (35kg/m³h)

G₁：Dry Material Production (3t/h)

V：Dry Space needed(m³)

W₁：Initial Moisture Content(55%)

W₂：Final Moisture Content(12%)

Material Calculation：

For every 1000kg wet material evaporation and moisture content：

W=1000×（0.55-0.12）/(1-0.12)=488.6kg(H20)

For every 1000kg wet material quantity after evaporate：M=1000-488.6=511.4kg

To produce 1000kg of end product need to feed in：

G=1000/511.4×1000=1955.4kg(wet raw material)

Rotary Dryer Calculation：

Volume calculation:

G₁=AV÷｛1000×〖W1—W2〗÷〖100—W1〗｝

3=AV÷｛1000×(55-12)/(100-55)｝=AV/956

V=81.9m³

Provided Drum dimension:φ2.2×24m

V=πr²L=3.14x（1.1）²x24=91m³ >82m³（fulfill requirement)

Rotary Dryer Energy Balance

Air Flow Velocity:  v=1.5m/s,

Dry Air Density:  ρ=1.2kg/m³,

Air Humidity:  H=0.007kg/kg_{dry air}，

Ambient Air Temperature: t₀=30°

Inlet Hot Air Temperature: t₁=250°

Outlet Hot Air Temperature: t₂=70°

Dry air consumption：

L=πr²vρ3600=3.14×1²x1.5×1.2×3600=20347.2kg/h

Wet air consumption：

L₁=L(1+H)=20347.2X(1+0.007)=20490kg/h

Heating value for ambient air：

Q₁=L(1.01+1.88H)(t₂-t₀)=20347.2÷3600x（1.01+1.88×0.007）x（70-30）=231.3kw

Heating value for evaporating moisture：

Q₂=W(2490+1.88t₂-4.187×30°）

=955.4÷3600x（2490+1.88×70-125.61)=622.4kw

Heating value for wet material：

Q₃=Gc（ wood ）（t₂-t₀）=1955.4×2.5×10³x40÷3600÷1000=54.3kw

Heating value loses：

Q₄=（Q₁+Q₂+Q₃）0.22=908×0.22=199.76kw

Total Heating Value：

Q=Q₁+Q₂+Q₃+Q₄=1107.76kw

Rotary Dryer Gas Quantity Needed

For standard condition

Dry Air Density:ρ=1.29kg/m³
Air Specific Heat Capacity:c=1.0×10³J/(kg.℃)

Q=V（T-t₂）ρc=V（400-70）ρc

V=2303.4*3.6×10⁶/370*1.29*10³=17373m³

Single Rotary Dryer System Air Flow Rate

Evaporation=955.4kg，t₁=250°，t₂=70°

System Air Flow Rate=Evaporation*3000/(t₁-t₂）=16000m³/h

Air Flow Rate =1.3*System Air Flow Rate=20800m³/hm³/h

Provided model：4-72-8C-22kw

Rotary Dryer Draft Fan Air Flow Rate

Draft Fan Air Flow Rate=2*System Air Flow Rate=32000m³/h

Provided model：4-72-10C-45kw

Rotary dryer design pdf for biomass