Vertical screw conveyors

A vertical screw conveyor conveys material upward in a vertical path. It requires less space than some other types of elevating conveyors. Vertical screw conveyor can handle most of the bulk materials provided there is no large lump. The maximum height is usually limited to 30m.

A vertical screw conveyor consists of a screw rotating in a vertical casing. The top bearing for the screw shaft must be designed to stand against radial and thrust loads. A suitable inlet port at the lower end and a discharge port at the upper end of the casing are provided. Feeding a vertical screw conveyor deserves careful consideration. Most materials are fed to the vertical conveyor by a straight or offset horizontal feeder conveyor. The ideal operation of a vertical screw conveyor is to have a controlled and uniform volume of material feeding.

Uneven feeding and start stop operation may adversely affect the performance of the vertical screw conveyor in terms of speed, capacity and horse power.

Average capacities and speeds of vertical conveyor

Nominal diameter of screw in mm	Capacities in m3/hr	Speed of screw
150	10	Up to 400 RPM
250	35	300 RPM
300	75	250 RPM
400	170	200 RPM

Vertical screw conveyors or some special design of vertical screw conveyor finds wide application in ship unloading.

Practical experience with these conveyors has shown that the resistance factor for vertical conveyors is higher than those of the horizontal conveyors. Resistance factor λ may be taken as 5.5 to 7.5 for grains. 6.5 to 8.3 for salt.

The driving power of the loaded screw conveyor is given by:

P = P_H + P_N + P_st

Where,

P_H = Power necessary for the progress of the material

P_N = Driving power of the screw conveyor at no load

P_st = Power requirement for the inclination of the conveyor

Power necessary for the progress of the material P_H:

For a length L of the screw conveyor (feeder), the power PH in kilo watts is the product of the mass flow rate of the material by the length L and an artificial friction coefficient λ, also called the progress resistance coefficient.

P_H = I_m.L. λ.g / 3600 (kilowatt)

= I_m.L. λ / 367 (kilowatt)

Where,

I_m = Mass flow rate in t/hr

λ = Progress resistance coefficient

Each material has its own coefficient λ. It is generally of the order of 2 to 4. For materials like rock salt etc, the mean value of λ is 2.5. For gypsum, lumpy or dry fine clay, foundry sand, cement, ash, lime, large grain ordinary sand, the mean value of λ is 4.0.

In this connection it should be noted that the sliding of the material particles against each other gives rise to internal friction. Other resistance due to grading or shape of the output discharge pattern contributes to the resistance factor. That is why the parameter λ is always higher than that due to pure friction.

Drive power of the screw conveyor at no load, P_N:

This power requirement is very low and is proportional to the nominal diameter and length of the screw.

P_N = D.L / 20 (Kilowatt)

Where,

D = Nominal diameter of screw in meter

L = Length of screw conveyor in meter

Power due to inclination: P_st

This power requirement will be the product of the mass flow rate by the height H and the acceleration due to gravity g.

P_st = I_m.H.g / 3600

= I_m.H / 367

H should be taken positive for ascending screws and will be negative for descending screws.

Total power requirement:

The total power requirement is the sum total of the above items

P = (I_m (λ.L + H) / 367) + (D.L /20) (Kilowatt)

Some posts need no Title-2

I comforted myself at the back of 50 seater with my crew…!!

All took their ID cards out and got ready with complete formals except few guys like me …

I took Rajeev’s shirt..

for the fact i dint picked even a single formal dress for the tour…!!

It took almost 40 odd minutes to reach the CMTI from the rail station..

those 40 odd minutes had given us little glimpse of bustling metro life..!

The wallposters of kannadaWOOD(Don’t know what to call!!)

I don’t know why they got my attention…

those actresses are the people who tried their luck at tollywood and failed…!!

I saw My childhood Fav star Nikhita in “GUN” wall poster..!!

And the most amazing thing is there are some people Called HEROES looked like the fellows who were denied admission in Mysore ZOO..!!

There i saw “5 Idiots”

Something that looked like” Kalamanja”(I really dont know how to pronounce Kannada words…!!)

I felt so sorry for the audience of mighty Bengaluru Metro People..!!

When compared to those stars even OM (Okka Ma…..) is lil better…!!

Suddenly the bus stopped at a junction huge traffic…!!

A huge construction under progress….

We don’t know that it was a part of B’lore Metro..!!

There is a huge iron pillar..

something like huge plate was attached to it…

We had a heated argument about whether the plate is riveted or bolted…!!

Then came a guy known for his photography with his brand new canon Mr.Mahendra Pedapati photographed that thing and zoomed that picture and showed that it was riveted..!!

i own my stake of Rs.10/- with Kesh..!!

Few minutes later we reached CMTI @ CVRamanNagar..

The lunch was already arranged there for us…

I expected lot from the kannada people…

But i just had to adjust myslef with Chapathi, 2 cups rice….

Sambar and the curd (Sour..!!)….

all for just Rs.50/-

Started into industry …!!

They just don’t allow Cameras or phones into industry…!!

Immediately after security check we were all allowed into that esteemed ,serene campus..!!

We were divided into 2 groups and set sailed for the next 3 hours..!!

The group which consisted me rushed into Rapid prototyping block ,Where a guy called Vinod waiting for us ..!!

He explained What prototyping is

and why it is being used and alll…..

It is the only process where we can produce a sphere inside another sphere freely rotating and without seam that in single step…!!

The process is supported by A slicing software and a machine which manufactures…

Somebody told us to note down the specifications of that machine….

I wonder what we do with them…??!!