(6) The amount of dry flue gas produced by burning one kilogram of coal :
Where l 0 ———dry flue gas volume, kg/kg;
A—the total air consumption coefficient of the combustion chamber and the mixing chamber, see formula (6);
L 0 ———theoretical air consumption, kg/kg. See formula (4);
H Y , W Y , A Y — The hydrogen content of coal and moisture and ash are expressed in %.
(7) The amount of water vapor entering the combustion chamber and mixing chamber simultaneously with air when burning one kilogram of coal:
g 2 =0.001aL 0 d 0 (9)
Where g 2 ———the amount of water vapor, kg/kg;
A—the total air consumption coefficient of the combustion chamber and the mixing chamber;
L 0 ———theoretical air consumption, kg/kg. See formula (4);
d 0 ———The outdoor air temperature is t 0 , and the humidity content of humidity is ф 0 , that is, the moisture content of outdoor air entering the combustion chamber, g/kg.
(8) The amount of water vapor entering the dryer at the same time as the flue gas:
g 3 =g 1 +g 2 (10)
Where g 3 ———the amount of water vapor, kg/kg;
g 1 ———The amount of water vapor produced by burning coal, kg/kg. See formula (7)
g 2 ——— The amount of water vapor entering the combustion chamber and mixing chamber at the same time as burning coal, kg/kg. See formula (9)
(9) The moisture content of the flue gas entering the dryer (temperature t 1 ):
Where d 1 ———the moisture content of the flue gas entering the dryer, g/kg;
g 3 ——— the amount of water vapor entering the dryer at the same time as the flue gas, kg/kg. See formula (10);
l 0 ———The amount of dry flue gas produced by burning coal, kg/kg. See formula (8).
(10) The heat content of the flue gas entering the dryer, and the heat content of the flue gas is obtained from the graph according to the values ​​of d 1 and t 1 , and can also be calculated by the following formula:
I 1 =[0.24t 1 +0.001d 1 (595+0.47t 1 )]×4.1868 (12)
Where I 1 ———the heat content of the flue gas entering the dryer, kJ/kg;
t 1 ———the temperature of the flue gas entering the dryer, °C;
d 1 ———The moisture content of the flue gas entering the dryer, g/kg.[next]
(11) The difference between the heat supply and the heat loss inside the dryer:
△=c W T 1 +Q 1 -ΣQ n (13)
In the formula △———the difference between the heat supply and the heat loss inside the dryer, kJ/kg;
c W ———the specific heat capacity of water, C W =4.1868KJ/kg;
T 1 ———the temperature of the material before drying, °C;
Q 1 ———The heat released by the heat source in the drying room, there is no longer a heat source in the drying room, so Q 1 =0;
ΣQ n ——— Total heat loss in the dryer;
ΣQ n =Q 2 +Q 3 +Q 4 .kJ/kg (13a)
Q 2 —--heat loss of one kilogram of water taken away by the material;
G 1 ———weight of material before drying, kg/h;
c 3 ———the specific heat capacity of the material to be dried;
G 2 ———weight of the conveying equipment circulating into and out of the dryer, kg/h;
c 5 ———the average specific heat capacity of the materials used in the equipment;
c 5 =0.115×4.1868, kJ/(kg · K)
t 3 ———The temperature at which the conveying device that circulates in and out of the dryer exits the dryer, °C;
t 4 ———The temperature at which the conveying equipment entering and leaving the dryer enters the dryer, °C, because the dryer generally does not have a transport device, so Q 3 =0;
Q 4 —- Heat dissipated from the surface of the dryer and not tight;
Q 5 ———The effective heat of the dryer;
Q 5 =(i 2 -c w T 1 )+Q 2 +Q 3 ,kJ/kg (13f)
i 2 ———the heat content of water vapor in the gas discharged from the dryer;
i 2 =(595+0.47t 2 )×4.1868, kJ/kg (13g)
t 2 ———The temperature of the exhaust gas of the dryer, °C;
T 2 ———The temperature of the material after drying, °C;
W———the amount of vaporized water in the drying process, kg/h. See formula (1);
W 1 ——— the moisture of the material before drying, %. See formula (1);
W 2 ———The moisture of the material after drying, %.
There are actually three states in the drying process: the difference between the internal heat supply and the heat loss of the dryer: â–³=0, â–³<0 and â–³>0.
The common state is â–³<0. At this time, the heat lost in the dryer is greater than the compensated heat, and the heat content in the flue gas will partially compensate the loss, so I 1 >I 2 . And so on, then â–³=0, I 1 =I 2 ; â–³>0, I 1 <I 2
(12) Dry flue gas volume required to evaporate one kilogram of water:
Where ι———the amount of dry flue gas required to evaporate water, kg/kg;
d 1 ———the moisture content of the flue gas entering the dryer, g/kg;
d 2 ——— The moisture content of the gas discharged from the dryer is found by the Id diagram (Fig. 14), g/kg;
(13) The amount of dry flue gas required per hour for the dryer:
ι 1 =ιw (15)
Where ι 1 ———the amount of dry flue gas required per hour of the dryer, kg/h;
ι———the amount of thousand flue gas required to evaporate one kilogram of water, kg/kg;
W———the amount of vaporized water in the drying process, kg/h. See formula (1).
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