material handling system

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By: kalavaniya (112 month(s) ago)

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Material Handling System : 

Material Handling System Prepared by : Mr Jitendra L. Patel

Pumps : 

Pumps Pumps impart pressure or head to the liq to go ahead at certain height. A machine that does work on a flowing fluid is called pump, blower, compressor. Methods: By action of centrifugal force By action of volumetric displacement By mechanical impulse By electromagnetic force By gravity

Factor affecting Selection : 

Factor affecting Selection Characters of liquid to be handled Total dynamic head Suction and discharge heads Temp, Viscosity Presence of solid and corrosion characteristics Space available

A) Positive displacement Pumps : 

A) Positive displacement Pumps Most commonly used for discharge of small quantities of fluid against relatively large heads. Fluid is positively displaced. It is independent of pressure.

a) Reciprocating pumps : 

a) Reciprocating pumps Here, the pumping element moves in forward and backward directions in a cylinder. The pumping element moves forward (down stroke/ delivery stroke ) later it recedes (suction stroke ) to draw the liq. In as an input. Pumping element is either a piston or a plunger.

i) Piston pumps : 

i) Piston pumps Here, the piston reciprocates in the enclosed space of the water cylinder. Piston carries packing material along with it. The liq. Enters from the suction valve and discharged through a delivery valve.

Single acting : : 

Single acting : It displaces water one half of the cycle of the piston movement. During other half of the cycle the cylinder receives the fluid. Such a pump require minimum two valves. One for receiving the liq. In to the cylinder and other for pumping liq out of the cylinder.

Single Acting: : 

Single Acting: Liquid admitted only to the portion of the cylinder in front of the piston. Limited capacity Discharge is pulsated

Double Acting: : 

Double Acting: In single acting there will be an interval during the return stroke when the cylinder will fill with liq. And delivery will remain zero. In case of double acting each stroke serves for suction and delivery. Here, fluid is on both the sides of the piston.

Double Acting: : 

Double Acting: Fluid is drown in one side by a stroke that delivers the fluid on the other. When 1st chamber Is emptied. 2nd is filled. When 1st chamber is filled 2nd is emptied. Give uniform flow Simple Used in gas-compressors

Piston pumps : 

Piston pumps Advantages High pressure generated on return stroke High efficiency Viscous fluid can be handled Dis advantages: Size and weight is more High cost Difficult to clean Application In spray system in sugar and film coating In peristaltic and HPLC pumps

ii) Diaphragm pump : 

ii) Diaphragm pump Modification of piston pump. It is so constructed that reciprocating parts do not contact the pumped liq. A diaphragm is fixed at the periphery, expands and contracts the pumping chamber, drawing in and discharging liq. Through valves.

Diaphragm pump : 

Diaphragm pump Advantages Cheap, Rugged and Simple Easily repairable Rate of discharge can be regulated Dis advantages: Limited pressure generated Limited materials of construction Pulsating flow Application For transporting liquids containing solids, hazardous, toxic and corrosive liquids.

Diaphragm pump : 

Diaphragm pump

iii) Plunger pump : 

iii) Plunger pump Plunger reciprocates in enclosed space of water cylinder. The term plunger refers to the element which move past to the stationary packing. It does not carry packing material with it as it is in piston pump. Principle : same as piston Plunger has same length as that of cylinder.

Plunger pump : 

Plunger pump Packing material is fixed so it can be fixed in any position. Based on its placements plunger pumps are classified as In side packed : The packing material is fixed in side the water cylinder, which is enclosed in the casing of the pump. Out side packed: Replacement of packing is more frequent. For a liquid containing suspended solid it is more convenient.

Plunger pump : 

Plunger pump Two way of Out side packing: 1) centre packed : packing material is placed at the centre of water cylinder. 2) End packed : packing material is packed at the end of cylinder. Packing is permanent so liquid can be pumped at high pressure. Valves are one way so flow is unidirectional.

Working : 

Working The movement of plunger creates vacuum and atm pressure forces liquid up through the suction pipe. The liquid pressure in the cylinder allows the valve to open. Two plungers are allowed to reciprocate in such a manner that at any moment , water enters in to left side cylinder, while water discharge through a right side cylinder or vice versa. This gives a non pulsating flow. Application : for handling liq at high pressure, for transportation of viscous liq and suspension.

Rotary positive displacement pumps : 

Rotary positive displacement pumps A rotary positive pumps combine a rotary motion with a positive displacement. Due to circular motion within a stationary housing the fluid is discharged with pressure. They give a non pulsating flow. The rotating element consist of two circular discs with lobes, which geared to each other.

Continue….. : 

Continue….. The liquid from the inlet port is trapped in a compartment which is reduced in size as the shaft turns and the liq is deliverd to discharge port. They rotate at low speed (100-300 RPM) They are used to pump viscous fluid. E.g. Gear, Lobe, Vane, Peristaltic, Screw

Gear pump : 

Gear pump It is type of rotary displacement pump. It consist of two gears which mesh each other. Both gears run in close contact with casing. 1 gear is driven by shaft and 2 nd by the first in opposite direction. Fluid is caught in the space between the teeth and casing. The meshing of gear prevents back flow

Gear pump : 

Gear pump Advantages Can handle viscous and heavy fluid Dis advantages: Not suitable for suspension Low capacity High power requirement

Lobe pump : 

Lobe pump Construction is same as that of gear pump with fewer teeth. Each impeller carries two or three lobes. Two impellers are driven separately through external gearing. They are also known as cycloidal pump.

Vane pump : 

Vane pump A circular disk, fitted with vanes sliding in slots in the disk and maintaining a sliding contact on casing. Sliding vanes, mounted in the surface of an off centre rotor but maintained in contact with case by centrifugal force. Adv: cheap and vanes are easily replaceable. Application: used as a blower, used to create vacuum.

Peristaltic pump (sqeeze pump, flow inducer : 

Peristaltic pump (sqeeze pump, flow inducer Here fluid flows through a flexible pipe by a peristaltic action. Peristaltic action is generated by a rotating mechanical device. The flexible pipe is clipped in to a semi circular base block. The tubing is compressed by rotor. The flow can be controlled by speed of rotor

Peristaltic pump : 

Peristaltic pump Advantages Simple, inexpensive Easy to clean Dis advantages: Linearity decrease as speed increases. Effectiveness decreases with viscous fluid Application For biological fluids, emulsion, creams, parenteral nutrition, blood pumping.

Screw pump : 

Screw pump It consist of a specially shaped helical metal worm rotor rotate in a stator made of rubber. The liquid being forced through a space between the stator and rotor. Applications : suitable for viscous and non viscous liquid, for non pulsating delivery, for corrosive and gritty liquids and to feed slurries to the filter press.

Non-Positive displacement pumpCentrifugal pump : 

Non-Positive displacement pumpCentrifugal pump it operates on the principle of rotating impeller throwing a fluid to the periphery by means of a centrifugal force. Due to revolving of impeller produce vacuum at entrance so liquid sucks in to the impeller from the suction pipe. Liquid flows outward in the space between vanes and leaves the impeller at a greater velocity. The impeller is rotated at a high speed.

Type of centrifugal pumps : 

Type of centrifugal pumps Volute Diffuser Turbine (Regenerative) Propeller Based on impeller shape: Enclosed, Semi enclosed, Open Based on operating characteristics: Single suction, Double suction. Based on direction of discharge: Radial, Axial, Mixed

Construction : 

Construction it consist of an impeller rotating within the casing. Mechanical energy of fluid is increased by centrifugal action. Rotating blade produce a reduction in pressure at the entrance. This cause the liq to flow in to impeller from suction pipe. This liq is forced outward along the blades at increasing velocity.

Centrifugal pump : 

Centrifugal pump Advantages : Simple Low cost Uniform flow Small size and large delivery capacity Easy to clean and sterilize Low maintenance cost Dis- Advantages: Efficiency falls with increase in viscosity. High head is difficult to obtain with single stage. More friction and power loss.

Volute pump : 

Volute pump Most common type A pump that is equipped with volute casing is known as volute pump. Liq enters at eye of impeller and is thrown radially out ward. The impeller discharge liq in to progressively widening spiral casing. It facilitate the conversion of velocity head in to pressure head gradually.

Volute pump : 

Volute pump Advantages : Any material can be pumped. Easy to clean, wash and sterilize. Large delivering capacity. Casing can be made of any material. No speed reduction of the impeller. Dis- Advantages: Less efficient than diffuser pump. Due to clearance some liq give resistance to rotor and efficiency reduce. Can not generate high pressure. Non- self priming.

Modification : 

Modification Open impeller- Semi open impeller: Impeller open to volute Fit between impeller and casing is poor so leakage to suction side. Used to pump liq. Containing suspended solids. Closed impellers: Impellers enclosed between two metal sheet. No back leakage. Single suction: Liq enters the impeller from one side. Double suction : Liq enters the impeller from both side. Pump consists of two impellers placed back to back and united in one casing

Diffuser pump : 

Diffuser pump In diffuser pump, after the liquid has left the impeller, it is passed through a ring of fixed diffuser vanes. This provide more controlled flow. The change from high velocity to pressure takes place gradually. This eliminates shock losses. Diffuser type pumps are used for high head.

Turbine (Regenerative) pumps : 

Turbine (Regenerative) pumps Here, the liq does not discharge freely from the tip of the impeller but is recirculated back to a lower point on the impeller diameter. The liq recalculates many times before it finally leaves the impeller. As a result of this recirculation develops high heads

Turbine (Regenerative) pumps : 

Turbine (Regenerative) pumps In turbine pump, the impeller has vanes located on both sides of the ring. As the liq. Enters the pump casing, it flows to both sides of the impeller. The liquids recirculates many times before it finally leaves the impeller.

Miscellaneous pumpsAir lift pump : 

Miscellaneous pumpsAir lift pump

Air lift pump : 

Air lift pump The air- lift is a device for inducing upward flow of a liquid through the introduction of a less dense immiscible fluid. Compressed air is most common lifting fluid. The average density of the material in the submerged column is reduced by the introduction of a gas at the base, and fluid level will rise above the level of submerging liquid. For air lift pumping of water an empirical relation Vair = (0.8).h’ / clog( (h+34)/34) Where, Vair = vol of free air rquired to lift 1 gal of water, h’ = total lift distance, h = distance from water level to point of air inlet.

Ejector pump : 

Ejector pump

Ejector pump : 

Ejector pump Here, expansion of the fluids occur through a nozzle. When primary fluid ( motive fluid- steam or air with pressure and velocity) enters through a small jet (nozzle) and expand, so create pressure drops (Vacuum), which sucks the secondary fluid, which is mix with primary fluid and mixture deliver from the common outlet.

Ejector pump : 

Ejector pump Advantages no moving part so no wear and tare No maintenance Dis advantages: Develop only small head Mechanically in efficient Application To create vacuum To transfer liq from one tank to another.

Modifiction : 

Modifiction Injector : Here, condensable gas is used to entrain a liq. And discharge at a pressure higher than the initial pressure. Ejector pump (Siphon exhauster, educator): it uses either gas or liq for either for either motive and entrained fluid and discharge at a pressure intermediate between the motive Pressure and the suction pressure. An exhauster is an ejector with gases as motive fluid and entrained fluids. A siphon ejector is ejector with gas as the motive fluid and liq as the entrained fluid. An educator is an ejector with liq. Both as motive and entrained fluids.

Pulsometer – Blow case : 

Pulsometer – Blow case

Rotary piston pump : 

Rotary piston pump

Roots blower : 

Roots blower

pulsometer : 

pulsometer

Sliding vane : 

Sliding vane

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