MB Rod Mill
December 31, 2018

MPH Medium speed coal mill

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Description

MPH Medium Speed Coal Mill

What is MPH medium speed coal mill
The MPH mill manufactured by our company has absorbed the advantages of MPS mill and HP mill, and removed their respective shortcomings. We  optimized the design on structure thus develop the new type of coal mill.
MPH medium-speed coal mill is mainly composed of the following parts of central coal drop pipe, separator, spring loading device, grinding roller, middle-frame, grinding disk, nozzle ring, scraper, lower-frame, lower- frame seal ring, planetary gear reducer, lubricant station, coupling, motor.


How the MPH medium coal mill works

The MPH medium speed coal mill is the type of roller mill with stressing extensively. The motor acts on the main reducer to drives the grinding disk to rotate and the rotation of the disk brings the three grinding rollers which are evenly distributed at 120 degree to rotate themselves. The raw coal falls through the coal pipe down the disk, and moves along the radial direction towards the circumference under the effect of centrifugal force, evenly enters the disk roller path then is grinded between the roller and the disk tile. This grinding system is enclosed in the middle frame. The grinding pressure is automatically applied by the spring loading installed on the mid-frame and is adjusted according to the coal grade. The grinding pressure and the themselves weight of the grinding parts are all applied to the reducer and then transmitted to the foundation. These three grinding rollers are evenly separated on the grinding disk roller-path and fixed on the middle frame by two trunnions, and roller arm can be adjusted to incline 12-15 degrees along the radial direction by the trunnion to get to the change of materials thickness and the angle change caused of the yearly working wear between the roller and disk.
The hot air used to delivering the pulverized coal and drying raw coal blows into the mill from the hot air inlet in which the static pressure is transformed into dynamic pressure by the nozzle ring outside the disk, and blows the pulverized coal at the speed of 75-90 m/s into the separator above the coal mill, and simultaneously the raw coal is dried out by strong stirring happening here. The raw coal not completely grinded is blown back to disk. The unbreakable iron blocks or gangue will fall into the hot air chamber located at the lower part of the disk, and these foreign matters are scraped into the waste bin by the scraper fixed on the disk support and discharged from the mill.
After the pulverized coal enters the separator at the upper part of the mill,  the coal meeting the fineness requirements is selected out and delivered to the coal bin through the output pipe located in the separator, however the coarse coal returns to the disk for grinding through the lower part of the separator.


What is the shortcomings of MPS Mill and HP Mill

1.The shortcomings of MPS mill
1) It is difficult to overhaul the mill roller. For the MPS mill is loading through triangular pressure frame, and with which the roller is connected by hinge shaft. When the overhaul is performed the connection between the roller and the pressing frame are firstly removed and then the roller is just taken out, during which the steps are intricacy and the overhaul is heavy.
2)The hydraulic loading is adopted. For the hydraulic cylinder always moving up and down in a long time will cause of the short life of the seal, and which is often required to replace the seal. If the replacement is not done in time it will lead to oil leakage thus will seriously pollute environment.
2.The shortcomings of HP mill
The output of the mill will seriously decrease after the mill operates for years. For the roller works in linear contact, the grinding parts will be worn after working many years, which will cause of the unstable contact among the grinding parts thus it leads to decrease the output.


What is the feature of MPH medium speed coal mill

1. The roller diameter is big, rolling resistance is small, and the grinding condition is good so the output characteristic is excellent and the power consumption is low.
2.The stable output, easy adjustment, low noise, small vibration and evenly wear of grinding parts.
The roller, roller arm and trunnion are connected to the middle frame in which the roller can be adjusted among the range of 12~15 degrees so that the roller can be well adapted to the changes caused by the thickness of the material layer, the feeding particle and the wear of grinding parts. In addition, the loading force is automatically controlled by the spring loading change. As the thickness of the material layer increased the loading force correspondingly increases thus the good grinding effect is achieved.
3.The coal mill can start and stop in the condition of no-load.
4.The stable output at post-worn period
MPH mill that is similar to MPS mill has good tile curvature of the roller and disk, and good matches in the ends to ensure excellent grinding effect. In the post-worn period of grinding parts, the output of the mill is slightly affected, which only decrease 5% lower than normal operation. This is the main advantage of MPH coal mill. For the HP medium speed coal mill it has the liner contact at working therefore the output will be reduced by 10%-20% in the post-worn period.
5.The grinding parts is made of various materials to lengthen service life            The roller bed and disk grate of MPH mill are made of high chromium cast iron, hard nickel cast iron (Ni-Hard IV) or lay-welding hard carbide metals which can also be reversed to use to make sure of the longer service life and ensure long-term stable operation.
6.The big output and little waste
The speed of air vortex is 70-90m/s in the mill which can fully hold the material to be grinded. Only the non-grindable waste can be excluded from the mill and the waste is less which reduces the workload of the maintenance in operation.
7.The easy maintenance
As the spring variation automatically loading is adopted the roller can be overhauled by taking it over directly. The mill is easy to overhaul with low cost.
8.The low operating cost
The traditional MPS mill adopts hydraulic loading. For the hydraulic loading requires to frequently replace of seal or hydraulic cylinder leaking will result in serious environmental pollution and the operating costs is increased. In addition the hydraulic station runs overtime and the energy consumption is increased.


The selection Parameter

 

Type

MPS125

MPS140

MPS150

MPS160

MPS170

MPS180

Output(t/h)
HGI=50;Mt=10%;R90=20%

13.3

17.7

21

24.7

28.8

33.2

Disk Diameter (mm)

1250

1400

1500

1600

1700

1800

Roller Diameter (mm)

970

1090

1170

1250

1320

1400

Disk Rotation(r/min)

35.6

32.6

32.6

31

31

29

Motor Rate(Kw)

160

185

210

250

280

355

Primary Air Flow(Kg/s)

5.78

7.73

9.1

10.7

12.46

14.38

Mill Resistance (KPa)

4.44

4.81

5.04

5.3

5.56

5.74

Air flow in Seal(Kg/s)

1.0

1.16

1.16

1.21

1.21

1.33

 

Type

MPS190

MPS200

MPS212

MPS225

MPS235

MPS245

Output (t/h)
HGI=50;Mt=10%;R90=20%

38

43.2

50

58

64.7

71.8

Disk Diameter (mm)

1900

2000

2120

2250

2350

2450

Roller Diameter (mm)

1500

1560

1650

1750

1830

1900

Disk Rotation(r/min)

29

29

26.6

26.6

26.6

25

Motor Rate(Kw)

400

450

500

560

630

710

Primary Airflow(Kg/s)

16.75

18.55

21.65

24.74

27.94

31.43

Mill Resistance(KPa)

5.93

6.11

6.3

6.48

6.63

6.93

Airflow in seal(Kg/s)

1.33

1.33

1.53

1.53

1.53

1.65

 

Type

MPS255

MPS265

MPS275

MPS280

MPS290

MPS300

Output (t/h)
HGI=50;Mt=10%;R90=20%

79.3

87.3

95.8

100.2

109.4

119

Disk Diameter (mm)

2550

2650

2750

2800

2900

3000

Roller Diameter (mm)

1980

2060

2140

2180

2260

2330

Disk Rotation (r/min)

25

25

23.8

23.8

23.8

22.6

Motor Rate (Kw)

800

900

1000

1000

1120

1250

Primary Airflow (Kg/s)

34.3

37.79

41.46

43.38

47.34

51.53

Mill Resistance (KPa)

7.08

7.23

7.31

7.38

7.6

7.76

Airflow in seal (Kg/s)

1.65

1.65

1.8

1.8

1.8

1.95

 

Type

MPH72

MPH90

MPH105

MPH130

MPH150

MPH170

Output (t/h)
HGI=50;Mt=10%;R90=20%

4.55

5.87

8.63

16.6

21

30.6

Disk Diameter (mm)

720

900

1050

1300

1500

1700

Roller Diameter (mm)

560

700

820

1010

1170

1320

Disk Rotation (r/min)

60

50.8

47.4

37.5

34.3

33

Motor Rate (Kw)

55

75

90

160

210

280

Primary Airflow (Kg/s)

1.89

3.25

4.29

7

9.1

12.46

Mill Resistance (KPa)

2.9

3.69

4.01

4.67

5.04

5.56

Airflow in seal (Kg/s)

0.26

0.26

0.6

0.77

1.16

1.21

Note: When the grain R90≤16% the SLS modular rotation separator is recommended

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