DESIGN OF MECHANICAL FLAT - BED DRYER

ASSUMPTIONS:

Initial Palay Weight, Wi : 500 Kgs.Initial Moisture Content, Mci : 24 %Final Moisture Content, Mcf: 15 %

Drying Properties:

Atmospheric Air: Inlet Air: Outlet Air:

Relative Humidity: 70 % 75 %Temperature: 20 °C 42 °C 25 °C

68 ºF 107.6 ºF 77 ºF

Abs. Humidity, H: 0.0102 Kg./Kg dry air 0.0149 Kg./Kg dry airEnthalpy, E: 11 Kcal/Kg. 16.1 Kcal/Kg.Abs. Volume, Va: 0.908 cu.m./kg.

1.) Calculate for the Water Removed:

Ww = Wi - Wi(1-Mci)/(1-Mcf) 52.94 Kgs. of Water

at 8 hours drying operation: 6.62 Kgs./hour

2.) Calculate air volume required to remove the water from the grain:

G = Ww/(H2-H1) 1,408.01 Kgs./hour

Q = G*r 1,278.47 cu.m./hr.of dry air

0.36 cu.m./sec.of dry air 751.90 cu.ft./min.of dry air

3.) Calculate the Heat energy required:

q = G(E2-E1) 7,180.85 Kcal/hr.

4.) Calculate/Determine the amount of fuel to Dry the Palay @ 14% MC for 8 hours.

Sr Fuel Approx heating value Kcal/Kg Fuel Reqt.

Dry StateKg/8-hr.

A BIOMASS

1 Wood 1500 3500 16.41

2 Cattle dung 1000 3700 15.53

3 Bagasse 2200 4400 13.06

4 2400 2500 22.98

5 3000 3000

19.15

6 3500 3500

16.41

7 4000 4000 14.36

8 4200 4200 13.68

9 Cotton husks 4400 4400 13.06

10 Peat 6500 6500 8.84

B

1 Coal 5500 10.44

2 Coke 6500 8.84

3 Charcoal 7000 8.21

Natural State

     

Wheat and rice straw

Cane trash, rice husk, leaves and vegetable wastes

Coconut husks, dry grass and crop residues

Groundnut shells

Coffee and oil palm husks

FOSSIL FUELS

     

 

 

 

4 Carbon 8000 7.18

5 Fuel oil 9800 5.86

6 10000 5.74

7 Petrol 10800 5.32

8 Paraffin 10500 5.47

9 Natural gas 8600 6.68

10 Coal gas 4000 14.36

11 860 66.80 Kw/8-hr.

12 5350

128.85

5.) Calculate the Drying Bin dimension:

Drying Bin dimension

CFM/sq.ft. Inches, Water Width,m. Length, m.

12.50 3/16 60.15 1.50 3.73 14.00 1/4 53.71 1.50 3.33 17.00 5/16 44.23 1.50 2.74 21.00 6.5/16 35.80 1.50 2.22 24.00 1/2 31.33 1.50 1.94 28.00 5/8 26.85 1.50 1.66 30.00 10.5/16 25.06 1.50 1.55

 

 

Kerosene and diesel

 

 

 

 

 

Pressure Drop

 

Bio gas(Kcal/cu mtr) (12 kg of dung produces 1 cu. Mtr gas)

  kgs. of dung (e.g.swine manure, etc) reqd.

Air Flow Rate per

unit Area of Drying Bin,

Q:

Pressure drop per

Foot depth of Grain,

Ph:

Area of a Drying Bin Required:

Square Foot of Grain

1.) Calculating the Moisture Ratio:

MC, %: 24.00

MR = (MC - Mce)/(Mci-Mce) 1.00

MR = e^(-x)(t^y) -0.5214519034 0.593658

Where: x = 0.026 - 0.0045h + 0.01215T 0.521452Y = 0.013362 +0.194h - 0.000177h^2 + 0.009468T 13.12372

2.) Calculating the Drying Time:

td = M/V(ha-hea) 3.30 Hours

t0.5 = td/Y 0.25

DM = V*Cp*t0.5*(Tdh-Twa)/Ln/(Mco-Mce)