Vertical screw conveyor transporting ash Problems and Solutions
Fly ash also known as fly ash, pulverized coal combustion flue gas by the dust collector collection and processing sediments, it is a good building material, widely used in
recent years gradually, recovered a large amount of thermal power plants.
Vertical screw conveyor is an enclosed vertical transport of materials capable, small footprint, high productivity transportation machinery. Fly ash is a means for conveying.
However, in actual use, there are still some serious problems, such as risk material, vibration, stuck, transmission parts damaged.
1 vertical screw conveyor conveying mechanism
Vertical conveyor screw speed is to rely on the proper role of the material caused by the centrifugal force on the particles and the resulting friction force generated on the
wall and for movement, when the screw is rotated at a constant angular velocity, the spiral surface of the material on their own inertia, starts slipping along the spiral Turn conveyor
surface, and gradual acceleration, if overcome the friction of the helical surface, the material in the wall under the effect of centrifugal force moves the increased pressure
acting on the wall, on the wall a greater frictional force, as the result of the action of friction, deceleration near the pipe wall material, and the helical surface relative
motion, so that the upward migration of part of the material, so as to achieve the purpose of transporting up.
(2) the material properties of coal ash
Fly ash is an easily inflated, will absorb, compaction, even produce a strong adhesion of the material, when it is inflated to a certain extent, there will be fluidized,
excellent mobility, can simply as dilute as free flowing slurry, when it is after a period of storage and natural compaction, mobility in general, and even tend to flow
difficulties, a typical angle of repose of 42 ° ash, moving the angle of repose of 30 °, if the belt conveyor conveyor, the inclination of up to 20-25 degrees, it is in the portable conveyor
case of long-term storage, can lose its loose and gathered into a group, and will produce adhesive, when it and other building materials such as cement, lime, etc. Wong
material, add water while stirring with a strong cohesive force, can be directly used as building material.
3 vertical screw conveyor structure
Power transmitted to the screw shaft by the belt, the screw shaft rotates clockwise, right-handed spiral blade generally, spaced intermediate bearing to ensure concentricity of
the screw shaft and motion smoothness. The following paragraph at the bottom of the spiral and leave some space to compensate for each section spirochete heat elongation. Helix
diameter and pitch designed according to international standards, the general pitch diameter D s with equal or equal 2/3xD. Vertical screw conveyor has two feed types, one is
the gravity feed type, another type of forced feed, respectively, for good mobility, poor density and flowability, low density materials.
Vertical screw conveyor conveying ash is difficult because there is a certain group
Fly ash is not suitable for materials with a vertical screw conveyor. Fly with a vertical screw conveyor elm send some difficulties, mainly due to:
(A) a special material properties of fly ash, the transport mechanism of the vertical screw conveyor difficult to achieve. Of fly ash in the recovery process, the purified flue
gas dust collector heat emitted into the atmosphere from the chimney to, but deposition on the precipitator ash hopper, the discharge temperature of 80-120 degrees, in inflated
state, completely fluidized. Then if a vertical screw conveyor transport, because the material internal friction is small, some still in the suspended state, you can not rely on
the spiral blade, blade friction material and small, can not play a role in its centrifugal force, it is not in a vertical spiral the delivery conveyor mechanism to work, it is
difficult vertical transport. Storage time after a Yin fly ash, through natural compaction and transport shock, with the typical characteristics of fly ash, a larger angle of
repose, poor mobility, prone to bagging or agglomerate binder, in order to make it flow better , sometimes filled with a certain amount of gas, the amount of control if
inflation is not good, but also easy to make the material fluidization. Especially in open dumps long-term storage of fly ash, a large adhesion, moisture content is higher,
easily bonded on the leaves, but also more difficult to use the vertical screw conveyor transport.
(2) vertical screw conveyor generally have intermediate bearings, bearing deep in the middle of the material, the fly ash is a very fine, medium abrasive materials, pervasive,
despite bearing seals, nor qualified long-term poor working conditions, are easily damaged, affecting the life of the vertical screw conveyor.
In summary, the use of fly ash conveying the existence of vertical screw conveyor difficult, but if you solve the following problems with vertical screw conveyor ash or
(1) fully aware of fly ash is an easy inflatable was fluidized material during transportation should avoid excessive inflation, to prevent the material fluidized ensure vertical
screw machine to achieve its delivery mechanism, in order to ensure its design throughput.
(2) In accordance with the vertical screw conveyor design allows the temperature of the material used, the general material temperature should be controlled below 80 ℃.
(3) Do not fly long open dumps, there must be proof measures to prevent caking material, gathered into a group.
(4) Improved intermediate bearing structure, enhance the sealing function, to improve their working conditions, and increased life expectancy.
(5) to open the top of the silo discharge hole, the hole diameter than the diameter of the vertical screw conveyor is 1-2 times.
(6) To set the limit feeding device, to ensure continuous and uniform feeding.
(7) In addition to debris screens have to remove the hard iron and easy to wound the ropes.