Posted tagged ‘conveyor’

Vertical screw conveyors

September 8, 2011


01-Vertical screw conveyors- Vertical screw pump- Vertical screw conveyor design- Vertical screw conveyor calculations

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.

01-Vertical screw lift- Vertical screw elevator- Vertical screw feeder- vertical screw conveyor-vertical screw pump

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.

01-screw conveyor design calculation- screw conveyor power calculation- screw conveyor efficiency- screw conveyor theory- screw conveyor formulae- screw conveyor flow rates

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

P = PH + PN + Pst

Where,

PH = Power necessary for the progress of the material

PN = Driving power of the screw conveyor at no load

Pst = Power requirement for the inclination of the conveyor

Power necessary for the progress of the material PH:

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.

PH = Im.L. λ.g / 3600 (kilowatt)

= Im.L. λ / 367 (kilowatt)

Where,

Im = 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, PN:

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

PN = D.L / 20 (Kilowatt)

Where,

D = Nominal diameter of screw in meter

L = Length of screw conveyor in meter

Power due to inclination: Pst

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

Pst = Im.H.g / 3600

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

Vibratory conveyor / Oscillating Conveyor

September 8, 2011


01-vibrating conveyor- vibrating conveyor systems-vibrating conveyor parts-shaker conveyor-inertia conveyor-reciprocating conveyor-oscillating conveyor

A vibratory conveyor essentially consists of an open or closed trough or pipe, generally horizontal but not always so, and which is elastically supported on a base structure or suspended from an overhead structure by springs. The trough or pipe is caused to oscillate at high frequency and small amplitude by an appropriate drive mechanism. Vibratory conveyors are commonly employed in industry to carry a wide variety of particulate and granular types of bulk materials. The fundamental action of the vibrating troughs on the bulk material loaded on it is to throw the particles upward in the forward direction so that the material performs series of short hopping movement and propagates at a certain speed.

Oscillating conveyors are utilized to convey sand or other granular particles at a desired rate. The conveyor is generally placed under a vibrating shakeout or a grid to eliminate direct handling of hot sand by the belt conveyor. In the process of reciprocation, the oscillating conveyor cools the hot sand to some extent which increases the life of the return sand conveyor belt.

An important characteristic of vibratory conveyor is the ease with which the flow rate of the conveyed material can be controlled by adjusting the amplitude and or frequency of the vibration. This particular aspects of such conveyor has led to the wide spread application of vibrating trough as feeders employed to supply material in controlled amount to various machines. When the trough is replaced by a screen, the vibratory conveyor may serve as vibrating screen, which has wide application in various industries. A distinction must be made between feeders and conveyors. A feeder is used as a discharge device under a storage hopper or bin and is subjected to varying head loads. A conveyor requires regulated feed rate and must not operate under varying head load conditions.

Construction details of Oscillating Conveyor:

01-vibrating conveyor parts-oscillating conveyor design-oscillatory motion design-vibrating trough conveyors-vibrating oscillatory machine-vibrating machine

01-vibrating conveyor parts-vibrating conveyor design-vibrating conveyor components-vibrating feeders-vibrating machine-vibrating motor-horizontal motion vibrating bed-motion of vibrating systems

CONVEYOR LAYOUT

August 23, 2011

Conveyor layouts:

Belt conveyors can be designed for practically any desired path of travel. It should be noted that transfer between conveyors should be avoided where possible due to additional wear on the belts at the loading points. Some of the profiles shown below:

Horizontal Conveyor

01-belt conveyor for mining-horizontal belt conveyor-belt conveyor inclination-belt conveyor layout-belt conveyor lacing

01-belt conveyor layouts-horizontal belt conveyor-belt conveyor types-airplane conveyor belt-belt conveyor horizontal curves

01-belt conveyor loading-horizontal belt conveyor-belt conveyor bulk material handling-belt conveyor construction

 


 

Decline Conveyor

01-decline belt conveyor-belt conveyor capacity calculation-belt conveyor counter weight-belt conveyor brake

01-layout of belt conveyor-types of belt conveyors-belt conveyor roller design-belt conveyor notes

01-types of belt conveyor-belt conveyor accessories-v belt conveyor-conveyor v belt pulleys-conveyor belt friction-conveyor rollers

Inclined Conveyor

01-belt conveyor equipment-belt conveyor drawing-belt conveyor equations-belt conveyor frame

01-belt conveyor for mining-belt conveyor gantry- belt conveyor head pulley-belt conveyor length

01-inclined belt conveyor-belt conveyor types-belt conveyor width- belt conveyor wide-belt conveyor weigh scales

Overland Conveyor

01-belt conveyor lift-belt conveyor links-belt conveyor inspection-belt conveyor examples-belt conveyor construction

CONVEYOR LAYOUT

August 23, 2011

Conveyor layouts:

Belt conveyors can be designed for practically any desired path of travel. It should be noted that transfer between conveyors should be avoided where possible due to additional wear on the belts at the loading points. Some of the profiles shown below:

Horizontal Conveyor

01-belt conveyor for mining-horizontal belt conveyor-belt conveyor inclination-belt conveyor layout-belt conveyor lacing

01-belt conveyor layouts-horizontal belt conveyor-belt conveyor types-airplane conveyor belt-belt conveyor horizontal curves

01-belt conveyor loading-horizontal belt conveyor-belt conveyor bulk material handling-belt conveyor construction

 


 

Decline Conveyor

01-decline belt conveyor-belt conveyor capacity calculation-belt conveyor counter weight-belt conveyor brake

01-layout of belt conveyor-types of belt conveyors-belt conveyor roller design-belt conveyor notes

01-types of belt conveyor-belt conveyor accessories-v belt conveyor-conveyor v belt pulleys-conveyor belt friction-conveyor rollers

Inclined Conveyor

01-belt conveyor equipment-belt conveyor drawing-belt conveyor equations-belt conveyor frame

01-belt conveyor for mining-belt conveyor gantry- belt conveyor head pulley-belt conveyor length

01-inclined belt conveyor-belt conveyor types-belt conveyor width- belt conveyor wide-belt conveyor weigh scales

Overland Conveyor

01-belt conveyor lift-belt conveyor links-belt conveyor inspection-belt conveyor examples-belt conveyor construction

CONVEYOR

August 23, 2011

Conveyor Take-up Arrangement:

01-belt conveyor-take up arrangement-screw take up-take up pulley-automatic take up device-fixed take up device-manual take up-self adjusting take up devices


All belt conveyors require the use of some form of take-up device for the following reasons:

  • To ensure adequate tension of the belt leaving the drive pulley so as to avoid any slippage of the belt
  • To ensure proper belt tension at the loading and other points along the conveyor
  • To compensate for changes in belt length due to elongation
  • To provide extra length of belt when necessary for splicing purpose.

Usually there are two types of take up arrangements.

  • Fixed take up device that may be adjusted periodically by manual operation
  • Automatic take up devices for constant load type

In a screw take up system the take up pulley rotates in two bearing blocks which may slide on stationery guide ways with the help of two screws. The tension is created by the two screws which are tightened and periodically adjusted with a spanner. It is preferable to use screws with trapezoidal thread t decrease the effort required to tighten the belt.

01-hydraulic take up device-pneumatic take up device-electrical take up device-self adjusting take up device-automatic take up device

The main problem with the use of manual take-up is that it requires a vigilant and careful operator to observe when take up adjustment is required. Perfect tension adjustment with this system is also not possible. For this reason these devices are used only in case of short conveyors of up 60 m length and light duty.

In automatic take up arrangement the take up pulley is mounted on slides or on a trolley which is pulled backwards by means of a steel rope and deflecting pulleys. The carriage travels on guide ways mounted parallel to the longitudinal axis of the conveyor, i.e., horizontally in horizontal conveyors and at an incline in inclined conveyors. Hydraulic, pneumatic and electrical take up devices are also used.

Automatic take-up has the following features:

  • It is self adjusting and automatic
  • Greater take-up movement is possible.