The double-ended coal mill has two completely symmetrical grinding circuits, and its working principle is as follows:
The raw coal enters the falling coal pipe through the coal feeder which can automatically control the speed, falls into the lower part of the conveying device by gravity, and is sent to the cylinder of the coal mill by the rotating twisting cage. The rotating cylinder body is filled with a certain amount of steel balls. , grinding the raw coal into pulverized coal.
The primary air enters the cylinder of the mill from the hollow tubes on both sides of the coal mill, and the raw coal and coal powder are dried, and the ground coal powder is transported to the upper part of the coal mill through the annular passage of the stranded cage. In the device, the unqualified coarse coal powder is returned to the cylinder for re-grinding, and the qualified fine powder is sent to the burner of the boiler.
Part of the primary air enters the mixing box, and the raw coal is fully pre-dried and then enters the coal mill separator, and mixed with the primary air to complete the further drying and transportation of the coal powder.
Different from other forms of coal mill, double-ended coal mill is not through the coal mill to adjust the control of output, but by adjusting the coal mill through the primary air control. In operation, no matter how the load is, the ratio of wind coal inside the mill remains unchanged. That is to say, under a given load, if you want to increase or decrease the mill output, only to increase or decrease the amount of air can be achieved, which is the unique characteristics of the double in and double out mill. Therefore, the adjustment time of the double in and double out pulverizer in response to boiler load is very short, which can be comparable with oil and gas boilers.
|
Item |
Unit |
BBD double ended ball mill |
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|
BBD |
BBD |
BBD 3448 |
BBD |
BBD 4060 |
BBD |
BBD |
BBD 4760 |
BBD 4772 |
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|
Inside diameter (inside liner) |
mm |
2450 |
2850 |
3350 |
3750 |
3950 |
3950 |
4250 |
4650 |
4650 |
|
|
Length of shell |
mm |
3740 |
4340 |
4940 |
5540 |
6140 |
6340 |
6740 |
6140 |
7340 |
|
|
Double cone |
mm |
1600 |
1800 |
2100 |
2400 |
2900 |
2900 |
3050 |
3200 |
3500 |
|
|
Speed |
r/min |
20.4 |
19 |
18 |
17 |
16.6 |
16.6 |
16 |
15.3 |
15.3 |
|
|
Motor |
Power |
KW |
280 |
500 |
830 |
1200 |
1400 |
1600 |
1800 |
2140 |
2550 |
|
Rotation speed |
r/min |
1000 |
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|
voltage |
V |
6000 |
|||||||||
|
Maximum steel ball loading |
t |
20 |
32 |
48 |
67 |
76 |
88 |
97 |
106 |
127 |
|
|
Total weight |
|
|
119 |
196.7 |
235 |
236.1 |
242 |
245 |
263 |
||
|
Capacity |
According to the data given by standard coal： |
t/h |
13 |
22 |
35 |
52 |
60 |
62 |
79 |
90 |
105 |
