Transportation and Storage
Belts
Learning Objectives:
- Define belt conveyors and explain their significance in material handling and industrial processes.
- Differentiate between belt conveyors and other types of conveyors.
- Identify and describe the key components of a belt conveyor system, including the conveyor belt, pulleys, idlers, and drive systems.
- A belt is a looped strip of flexible material, used to mechanically link two or more rotating shafts.
- They may be used as a source of motion, to efficiently transmit power, or to track relative movement. Belts are looped over pulleys.
- In a two pulley system, the belt can either drive the pulleys in the same direction, or the belt may be crossed, so that the direction of the shafts is opposite.
- The velocity of the belt
- The Tension of the belt
- The arc of contact between the belt and smaller pulley
- The condition under which the belt is used
- Open Belt Drive: The open belt drive is used with shafts arranged parallel and rotating in the same direction
- Crossed Belt Drive: The crossed belt drive is used with shafts arranged parallel and rotating in the opposite direction
- Where high-speed applications (up to 140,000 rpm) are more important than power transmission
- Long center distances are necessary
- Where drives with non-parallel shafts are required (belt can be twisted)
- Applications requiring small pulley diameters (as small as 3/8") Disadvantages:
- Tend to slip under load
- lower efficiency at moderate speeds
- must be kept under tension to function (require tensioning devices); causes high bearing loads
- require friction for proper functioning (therefore, cannot be used when absolute synchronization between pulleys must be maintained)
- stretch over time
CecaRJ, CC BY-SA 4.0, via Wikimedia Commons
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Solved Example: 9101-01
In a belt drive system, when the speed of the belt increases:
A. Co-efficient of friction between the belt and pulley increases
B. Co-efficient of friction between the belt and pulley decreases
C. Power transmitted will decrease
D. Power transmitted will increase
Correct Answer: D
Solved Example: 9101-02
Which is a positive drive?
A. Round belt drive
B. Flat belt drive
C. Crossed belt drive
D. Timing belt
Correct Answer: D
Pneumatic
Learning Objectives:
- Recognize the diverse industrial applications of pneumatic conveying, such as in the handling of powders, granules, and other solid materials in industries like agriculture, pharmaceuticals, and manufacturing.
- Identify and understand the functions of key components, including air source (compressor or blower), conveying pipeline, feed systems, air-material separation devices, and material receiving units.
- Learn how material properties, such as particle size, shape, density, and cohesion, influence the selection of the appropriate pneumatic conveying system.
Pneumatic Conveying
- “Pneumatic conveying is a common method of transferring powder, granules and other dry bulk materials.”
- The suspending fluid in pneumatic conveyer is a gas, usually air flowing at velocity’s between 15 to 30 m/sec. in pipes ranging from 50-400 mm in diameter.
- The principal types of system are below :
- Negative pressure system
- Positive pressure system
- Vacuum pressure system
- Pressure fluidized system
- Infinite availability of the source: Air is available in the world around us in unlimited quantities at all times and places.
- Easy channeled: Air is substance that is easily passed or moved from one place to another through a small pipe, the long pipe.
- Easy to leak: One of the properties of air is like to always occupy the empty space.
- Easy condenses: Pressurized air is easily condensed, so before entering the system must be processed first in order to meet certain requirements, such as dry.
Slurries
Learning Objectives:
- Define slurries and explain their importance in various chemical engineering applications.
- Differentiate between slurries and other fluid-solid mixtures.
- Describe the flow behavior of slurries, including characteristics like viscosity, rheology, and sedimentation.
- Analyze the factors affecting slurry flow, such as particle size and concentration.
Slurry:
- “A mixture of water & small pieces of a solid especially such a mixture in a industrial of furming process.”
- Particle smaller then 15 $\mu$m diameter.
- Larger particles size is 0.25 mm diameter.
Tanks
Learning Objectives:
Storage tanks
- General Storage of liquid materials is commonly accomplished in industrial plants by use of cylindrical, spherical or rectangular tanks.
- Storage tanks are also used as an intermediate stage in process, particularly in batch process
- These tanks may be constructed of wood, concrete, or metal, with metal being the most common material of construction.
- Now a days metallic storage tanks are replaced by fiber reinforced plastic(FRP) and high density polyethylene (HDPE).
- The design of storage vessels involves consideration of details such as size and number of openings, shape of heads, necessary temperature and pressure controls and corrosive action of the content.
- The design of storage vessels involves consideration of details such as size and number of openings, shape of heads, necessary temperature and pressure controls and corrosive action of the content.
- Storage tanks having cylindrical shell, flat bottom, conical or dome shaped roof are designed, fabricated and erected as per the standards.
Eng.dilan86, CC BY-SA 4.0, via Wikimedia Commons
- This tank has no roof and may store or nonhazardous liquid such as water other aqueous solution can be stored.
- These tanks are most common types of tanks which are used in industries.
- These are used for liquid with very high flash point, (e.g fuel oil, water, bitumen etc.) Cone roofs, dome roof and umbrella roofs are usual.
- These are provided with breathers or vents to permit the variation in vapour pressure of liquid with temperature and permit the change in volume of liquid with temperature.
- These are insulated to prevent the clogging of certain materials, wherein the heat is provided by steam coil within the tanks.
Floating roof tanks
- Floating roof tanks are broadly divided into two types: i. Internal floating roof tanks (IFR) ii. External floating roof tanks (FR) i. Internal floating roof tanks (IFR):
- These tanks are used for liquids with low flash points (e.g. gasoline, ethanol).
- These tanks are nothing but cone roof tanks with a floating roof inside which travels upward and down along with the liquid level
- Floating roofs are supported with legs or cables on which they rest.
- Floating roofs are considered a safety requirement as well as a pollution prevention measure for many industries including petroleum refining
- This type of scenario affords protection for the floating roof from outdoor elements such as rain, frost and snow.
- In addition, covered floating roof tanks minimize, and in some cases eliminate, the potentially harmful gaseous zone that accumulates over stored liquid and space between the floating roof and fixed roof is always well-ventilated.
EPA, Public domain, via Wikimedia Commons
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Hoppers
Learning Objectives:
- Define what a hopper is and explain its role in material handling and storage.
- Describe the basic components and features of a hopper.
- Identify and differentiate between various types of hoppers, such as conical hoppers, wedge hoppers, and pyramid hoppers.
- Understand when and why each type of hopper is used in different applications.
Hoppers are used in many industries to hold material until it is needed, such as flour, sugar or nuts for food manufacturing, food pellets for livestock, crushed ores for refining, etc.
Pearson Scott Foresman, Public domain, via Wikimedia Commons
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