Paraphrase 24

1. Screw conveyor’s advantage
The use of screw conveyor for moving heavy materials through an inclined path eliminates the problem of material movement up structures. In addition to efficiency, this approach uses minimal equipment at reduced conveying space.
Screw conveyors are applicable in conveying various materials. The choice of inclined screw conveyor in my design is based on its capability to elevate materials using the minimum possible equipment, thus less floor space requirement for the set-up. Here, the conveyor is to be used for conveying willow wood chips up into the furnace, situated some 5 metres above the ground.
2. Aim of the project
The main aim of this project is the designing of a screw conveyor for the elevation of willow wood chips from the ground bin into the furnace. The furnace to be fed with the material is 5 metres vertical distance from the ground.
3. Assumption
In the case of “energy from willow”, willow is a natural kind of fuel that can be used for the generation of green energy using a burning system. In this case, wood fuel heating system delivers hot water, the final product of the system, to Weobly School. The assumption is that an estimated 300 tonnes of fuel are used annually; the system is only operated during winter (4months); and chips delivery is twice a week. In addition, the burning capacity of wood is assumed to be 45 minutes at a conveyor speed of 15 minutes by hour. Lastly, the system is assumed to run 8 hours a day, Monday to Friday.
4. Anticipated special problems with this system
The designing process should take into consideration numerous potential problems.
Problem 1
With the screw conveyor’s angle of inclination above 25°, the design is marked with imminent conveyor efficiency loss. This problem has been attributed to two reasons:
a) At more than 25° inclination, the maximum possible capacity of the conveyor declines drastically.
b) On the other hand, there will be notable increase in the horsepower per capacity unit of the conveyor.
Solution:
A. The design should that standard screw conveyor components are not used for inclines above 25°. Typically, they should be limited to inclines equal or below 15°.
B. It should ensure close clearance between the trough and the screw.
C. The incline conveyor speed should be set higher compared to that of same size horizontal screw conveyor.
D. Using short pitch screws, typically of 2/3 or 1/2 pitch, subject to the permissible specifications of the material to be handled.
Problem 2
Willow chips quality factors such as size, shape, moisture, and chemical composition will impact on the conveyor performance. Moreover, direct falling of the chips from the feed chopper risks choking the conveyor.
Solution:
For this case, the willow wood chips are dry prior to storage in a concrete silo. Uniform-size cutting of the chips ensures their conveyance through the screw conveyor. To achieve this, a chip-size sampling system is necessary before their storage. Furthermore, the silo should be reliable enough to limit dry matter loss. However, it should have perforated ducts to mitigate incidences of mildewed in case the chips are not dry enough. Still, the use of tapering or stepped diameter conveyor screws would serve to ensure uniform withdrawal of chips from the entire feed opening length.
Problem 3
Allowing ideal combustion of fuel in the vibrating grate combustion systems means the rotation speed of the screw conveyor will be dependant on the quantity of willow chips. In addition, fire might failure to flow out of the stove along the fuel delivery system.
Solution:
Employ the use of vibrating grate combustion system as such will allow even level distribution of fuel in the stove. Further, it ensures that the fuel inlet shuts after chips have been fed into the stove.
Problem 4
Efficiency of the design is subject to the level of friction between the screw and the material.
Solution:
Polishing of screw surfaces as well as oiling or greasing, coupled with the use of wet materials enhances smooth flow.
5. Secondary equipment
As is evident in diagram 1, a feed hopper was used to feed chips to the conveyor in my design. The conveyor opening is marked with a regulating gate for reception and distribution of the chips. With the conveyor length ex...