Material sealed screw feeder principle and basic form

Biomass is the most widely used on Earth material , biomass is an important area of ​​application of biomass gasification . Circulating fluidized bed gasification is a major

biomass gasification technology, which is the basic principle Vibration feedergasification in a fluidized state . Biomass burning in the lower part of the bed ,

The upper part of the bed gasification , carbon particles blown collected by various separation down , back to the bed gasification cycle . The technology for fuel adaptability,

gasification temperature is lower , and the large-scale continuous production . Circulating fluidized bed gasification technology in recent years has been the rapid development

and application .
Looking abroad circulating fluidized bed gasification plant , the raw material feeding device is always flawed , the most important is the feeder sealing problems. Positive

pressure circulating fluidized bed system , in order to prevent leakage of air flow inside the furnace , you must cut off the feeder connected with the outside world . Usually

do

Method is to use the feed to seal off the wind , but the effect is poor. Here straw as raw material , the application of material sealed screw feeder device solved the problem

of feeding seals .
1 screw feeder material sealed principle
Screw feeder is installed in the center axis of the helical segments , the shaft and the helical segments in a fixed rotation within the housing , with the function of a

mechanical device to transport raw materials . When changing the pitch of the helix or spiral path , the transmission capacity of the feeder will change , through the

transmission capacity feeder

Changes in the raw material accumulation within the feeder , which play a role in sealing material , which is material sealed .
Spiral material sealed feeder ( also known as material sealed auger ) has the following characteristics :
( 1 ) screw feeder transport distance is short, usually no more than 3m;
( 2 ) screw feeder for mobility, non-tacky or sticky little or no pondering pondering the nature of small powder granular materials , raw material particle size generally less

than 50mm, the moisture content does not apply to large , hard , pondering of the great and highly viscous materials ;
( 3 ) screw feeder is a relatively closed system , transmission capacity is relatively small, the power consumption is relatively large .
2 screw feeder basic form of seal material
( A ) tapered spiral feeder
Tapered spiral feeder is in a certain period in the shaft diameter or pitch screw feeder diminishing . When taking a certain value , feeder transmission capacity will be

reduced, but the raw material into the feeder conveyor is a certain amount , so that when the raw material is transported , the late delivery of raw materials

Will be the backlog , as time goes by, the backlog of raw materials will be more and more slowly will be in the interior of the casing feeder filled with raw materials. When the

material is to a certain extent the backlog , the raw material particles will gradually narrow the gap between , when the narrow gap to a certain extent, it will give off

Feeder ventilation with the outside , so that to achieve the purpose of sealing .
( 2 ) Disconnect the spiral feeder
Disconnect the Dewatering screen is removed in a certain period in the axis of the spiral chip conveyor while it declined sharply in the feeder . This form of feeder tapered sealing

principle and the same type of feeder , the difference is material handling capabilities. In the off -type feeder , the axis of the screw diameter segment

And pitch are zero , by the screw feeder throughput formula shows that the relative resistance of tapered -type feeder is bigger.
3 . Analysis and discussion
Take 3 different granularity , hardness and elasticity of materials, such as corn stalks (20-40mm), peanut shells, rice husk powder (0.1-1mm), to prepare a current tester,

blowers, and grouping experiments, corresponding current , length, and the sealing performance ( room temperature only

Sealing performance ) .
For each type of feeder , the feeder has a length such that a good seal machine , while power consumption is not large. When it exceeds a certain value , the raw material will

be clogged pipes, raw materials can not be transported , then the motor current sharp rise is likely to be damaged due to overload the motor . So

, In order to make the feeder in the work process , both the normal transport of raw materials , while maintaining the seal, you must choose the right seal segment length. For

different materials , the feeder of the length of the sealing section is different, in general, large particle size , poor compressibility , the surface roughness

Large material required length is small; the small particle size , compressibility , surface roughness of the material requires a large length . This is just a general rule,

there will be some unusual materials studied. In short , in order to get a reasonable seal feeder, must be based on different materials with

Circumstances of the design .
Sealing screw feeder structures , there are many , the principle is basically the same , are transported by reducing the amount of raw materials played a role in the backlog ,

so as to achieve the purpose of sealing .
4 Conclusion
( 1 ) Sealing screw feeder design difficulty is necessary to ensure the tightness , but also to ensure smooth transportation of raw materials , which are mutually contradictory

problems . Meanwhile, the different materials required for sealing the length of the seal segments may also vary widely , but also because even if the same particle size as a

raw material , changes in humidity and other factors,

The sake of change . To design a rational sealing screw feeder should be based on the theoretical analysis , combined with a large number of experiments to determine a

reasonable design.
( 2 ) For the circulating fluidized bed is recommended to choose the middle disconnect type screw feeder , first, because of its good sealing effect, the fluidized bed of the

powder material is particularly suitable ; Second, because the feeder pipe sealing segment middle , thus reducing the material temperature of the internal temperature of the bed