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Saturday, 15 June 2019

PNEUMATIC CONVEYORS

          Pneumatic conveyors are used to transport dry, free-flowing, grannular material in suspension within a pipe or duct. This is done by the use of a high-velocity air stream or by the energy of expanding compresses air within a comparatively dense column of fluidized or aerated material.
Principal uses of pneumatic conveyors are 
(1) Dust collection,
(2) Conveying soft materials such as flake or tow, and
(3) Conveying hard materials such as fly ash, cement, and saw dust.

The primary advantages of pneumatic conveyor systems are the flexibility of piping configurations and the fact that they greatly reduce the explosion hazard. With exception of the primary driver, there are no moving parts that can fail or cause injury. However, when they are used to transport explosive materials, there is still some potencial for static charge buildup that could cause an explosion.

Configuration:
          A typical pneumatic conveyor consists of Schedule -40 pipe or ductwork, which provides the primary flow path used to transport the conveyed material. Motive power is provided by the primary drive, which can be a fn, fluidizer, or positive-displacement compressor.

Performance:
Pneumatic conveyor performance is determined by the following factors:
(1) Primary-driver output,
(2) Internal surface of the piping or ductwork, and 
(3) Condition of the transported material.
Specific factors affecting performance include motive power, fricition loss, and flow restricitons.

Motive Power:
          The motive power is provided by the primary drive, which generates the air velocity to transport material within a pneumatic conveyor system. due to this the efficiency of the system is depends on the primary drive's operating condition.

Friction Loss:
          Friction loss within a pneumatic conveyor system is a primary source of efficiency loss. To reduce these losses the piping or duct work must be properly size is used.

Flow Restrictions:
          One of the disadvantage of this system is their potencial for blockage. To reduce this the inside surfaces must be clean and free of protrusions or other defects that can restrict or interrupt the flow of material. In some cases when the system is shutdown or the velocity drops below the minimum required to keep the transported material suspended, the product will settle in the duct, this settled material cause reduce flow and eventually result in a complete blockage of the system.

Installation:
          All piping and ductwork should be as stright and short as possible. Bends should have a radius of atleast three times the diameter of the pipe or ductwork. The diameter should be selected to minimize friction losses and maintain enough velocity to prevent settling of the conveyed material. Brach lines should be configured to match as closely as possible the primary flow direction and avoid 90-degree angles to the main line. The area of the main conveyor line at any point along its run should be 20-25% greater than the sum of all its branch lines.
          Clean-outs and drop-legs, should be installed at regular intervals throughout the system to permit foreign materials to drop out of the conveyed mateerial. It is must to install adequate clean-out systems near flow restrictions and at the end of the conveyor system.

Operating Methods:
          Pneumatic conveyor systems must be operated properly to prevent chronic problems. The primary concern being to maintain constant flow and velocity.
          Constant velocity can be maintained only when the system is operated within its performance envelope and when regular clean-out is part of the normal operating practice. In addition, the primary driver must be in good operating condition. Any deviation in the primary driver's efficiency reduces the velocity and can result in partial or complete blockage.
          The entire pneumatic conveyor system should be completely evacuated before shutdown to prevent material from settling in the piping or ductwork. In non-continuous applications, the conveyor system should be operated until all material within the conveyor's piping is transported to its final destination. Material that is allowed to settle will compact and partially block the piping. Over time, this will cause a total blockage of the conveyor system.

 



Thursday, 13 June 2019

Conveyor Systems

         Conveyor system is a standard piece of mechanical material handling equipment or assemblie, that moves materials or packages from one location to a different location with minimal effort over a fixed path. 
Image Source: Wikipedia
          They typically contains frames that support rollers, wheels or belts and that they could also be motor powered or manual devices. Conveyors are particularly helpful in applications involving the transportation of heavy or bulky materials like gravel or aggrregate. They are extremely popular in the material handling and packaging industries due to efficient and fast transportation of materials. 
         They also include moving belts that used in belt conveyors, bucket and vertical conveyors that raise material, vibrating conveyors that use vibrating motion to maneuver material, and overhead conveyors from which things suspend throughout transport. Different sorts include screw conveyors for moving liquid or material consisting of small grains, chute conveyors are located on sleek surfaces and gravity, and drag or tow conveyors that use cables to pull objects on. Walking beam conveyors move objects by forward sweep mechanism to planned positions for manufacturing operations.
Image Source: http://foodanddrinkmatters.co.uk/carefully-customised-conveyor-solutions/

Types of conveyor systems


          Coming to types of conveyors, there are many alternative varieties of conveyors we are able to notice. First of all companies those who want to use conveyors should be able to notice their wants. Some of the foremost common things ought to be considered before installation are mentioned below.


  1. Product type being handled: Unit load or Bulk load
  2. Product dimention: Length, breadth and height
  3. Product Variability
  4. Surrounding environment i.e., It's location : Overhead, on-floor, or in-floor
  5. Whether or not lots will accumulate on the conveyor
  6. Type of path: Horizantal, Declined or Inclined manner
          The verity of conveyors is infinite, but the two major classifications used in typical plants are Pneumatic and Mechanical.

Note: The power requirement of a Pneumatic conveyor system are much greater than for a mechanical conveyor of equal capacity. 

What is meant by conveyor?

Different types of conveyors:


Mechanical Conveyors:

1. Chute conveyor
                 a. Gravity Roller conveyor
                 b. Live powered roller conveyor
                 a. Magnetic belt conveyor
                 b. Troughed belt conveyor
                 c. Slider bed
                 d. Roller bed
                 e. Horizontal belt conveyor
                 f. Inclined and declined conveyor
                 g. Brake and meter conveyor
                 h. Wire mesh belt conveyor
                 i. Portable conveyor
                 j. Metal piano hinge conveyor
7. Bucket conveyor
8. Vibrating conveyor
10. Tow conveyor
11. Trolley conveyor
12. Monorail conveyor
13. 



Pneumatic Conveyors:




Types of conveyor systems

           Coming to types of conveyors, there are many alternative varieties of conveyors we are able to notice. First of all companies those who want to use conveyors should be able to notice their wants. Some of the foremost common things ought to be considered before installation are mentioned below.

  1. Product type being handled: Unit load or Bulk load
  2. Product dimention: Length, bredth and height
  3. Product Variability
  4. Surrounding environment i.e., It's location : Overheadon-floor, or in-floor
  5. Whether or not lots will accumulate on the conveyor
  6. Type of path: HorizantalDeclined or Inclined manner


Different types of conveyors:

          The verity of conveyors is infinite, but the two major classifications used in typical plants are Pneumatic and Mechanical.

Note: The power requirement of a Pneumatic conveyor system are much greater than for a mechanical conveyor of equal capacity. 

Mechanical Conveyors:
1. Chute conveyor
                 a. Gravity Roller conveyor
                 b. Live powered roller conveyor
                 a. Magnetic belt conveyor
                 b. Troughed belt conveyor
                 c. Slider bed
                 d. Roller bed
                 e. Horizantal belt conveyor
                 f. Inclined and declined conveyor
                 g. Brake and meter conveyor
                 h. Wire mesh belt conveyor
                 i. Portable conveyor
                 j. Metal piano hinge conveyor
7. Bucket conveyor
8. Vibrating conveyor
9. Screw conveyor
10. Tow conveyor
11. Trolley conveyor
12. Monorail conveyor

Pneumatic Conveyors:

what is meant by conveyor? or Conveyor system?

          Conveyor system is a standard piece of mechanical material handling equipment or assemblie, that moves materials or packages from one location to a different location with minimal effort over a fixed path. 
Image source: Wikipedia
          They typically contains frames that support rollers, wheels or belts and that they could also be motor powered or manual devices. Conveyors are particularly helpful in applications involving the transportation of heavy or bulky materials like gravel or aggrregate. They are extremely popular in the material handling and packaging industries due to efficient and fast transportation of materials. 
         They also include moving belts that used in belt conveyors, bucket and vertical conveyors that raise material, vibrating conveyors that use vibrating motion to maneuver material, and overhead conveyors from which things suspend throughout transport. Different sorts include screw conveyors for moving liquid or material consisting of small grains, chute conveyors are located on sleek surfaces and gravity, and drag or tow conveyors that use cables to pull objects on. Walking beam conveyors move objects by forward sweep mechanism to planned positions for manufacturing operations.
          The verity of conveyors is infinite, but the two major classifications used in typical plants are Pneumatic and Mechanical.
Note: The power requirement of a Pneumatic conveyor system are much greater than for a mechanical conveyor of equal capacity. 
Image Source: http://foodanddrinkmatters.co.uk/carefully-customised-conveyor-solutions/


Monday, 20 May 2019

PAPER MACHINE HEADBOX

          The paper machine headbox is an equipment that supply low consistancy pulp (stock) uniformly into the forming section. The formation and uniformity if the final paper product depends on the dispersion of fibre and fillers. Machine headbox had major effect on paper qualities. There are different types of headboxes are present, all are not suitable for for all grades and types of paper and machine speed. Awell constructed headbox will give good quality paper. So the design headbox should be proper. The headbox is also called as "Stuffbox" or "Flowbox". 

Paper machine headbox types:

          In general the Headbox is catogarised into 3 major types, as Open type, Air padded type, and Hydraulic type.
         Hydraulic type of headbox is designed for high speed paper machines (speed above 350 m/min). Whereas open type open type headbox is designed for low speed paper machine. In Hydraulic and Air padded headedbox, the discharge velocity from the slice depends on the feeding pump. For this reason they are generally called as "Pressurised Headbox". The hydraulic headbox has no air pad, it is fully closed.
          Incase of air padded headbox pond level is maintained. Above the pond level it containes pressuried air. To maintain this air pressure we use headbox blowers. The stock level is known as Head, which is controlled by air pressure. The head determines the slice jet velocity or speed. These type of headboxes contains two or three "Holey rolls or rectifier rolls", and a "headbox shower".
          Multi layered headbox is available for making Tissue paper and light weight container board. Foe each layer it has different furnish compositions and delivary system.

Headbox jet velocity calculation:

          Jet velocity is the very important factor in the manufacturing of high quality paper. We have to maintain jet-to-wire velocity ratio; 0.97 to 1.03. The headbox jet velocity can be calculated from Bernoulli's equation:
              V2=2gh

Headbox Functions:

           The headbox serves many functions among them the following three functions are very important in the paper production process. If the headbox doesnot perform these three functions acceptbly, the quality of the paper produced will be greatly diminished.

1. Spread the low consistancy stock uniformly along the width of the wire.
2. Accelerate the stock and maintain constant velocity according to the paper machine operating speed.
3. Create control turbulance and suspend the pulp fibres throughout the out going slurry to eliminate fibre gathering.

Parts of Headbox:

The Headbox generally contains following parts:

1. Diffuser
2. Compressor line
3. Holly rolls
4. Rotating shower
5. Bottom lip
6. Top lip

Holey roll or Rectifier roll or evenor roll:

These rolls are genreally 2 to 3 present in headbox. These rolls are used for controlling both even outflow irregularities and to create turbulance to keep the fibre dispersed up to the slice opening. Normally hole diameter is 3 to 4 cm.

Rotating shower:

          This shower is used for continous headbox cleaning purpose and also consistancy maintenance.


Paper machine headbox slice:

          The paper machine headbox slice is a full width nozzle with a completely adjustable opening to give the desired rate of flow. The slice contains two lips; Top lip and Bottom lip. Among them bottom lip is adjustable; we can up or down or move sides also by hand operated or motor driven. On the otherhand top lip is fixed. The distance between the top lips are called Slice opening. The slice opening controls the stock jet velocity which is very importnat for the paper fromation.
The slice spindle contains a gearbox, connecting rod, Spindle, and hook which lifts bottom lip. 

Wednesday, 15 May 2019

SCREW CONVEYOR

          A Screw conveyor or Auger conveyor is a mechanism that uses a rotating helical screw, usually within a tube (Trough), to move liquid or grannular materials. The rotating part of this type of conveyor is called Auger.

          Screw conveyor in modern industry are often used horizontally or at a slight inclined as an efficient way to move semi-solid materials, including food waste, boiler ash, powder materials, agricultural material and many other. The first type of screw conveyor was the Archimede's screw, used since ancient times to pump irrigation water.

          They usually oncist a trough or tube containing either a spiral blade coiled around a shaft, driven at one end and held at the other end, or a "Shaftless spiral", driven at one end and free at other end. The rotational rate of shaft is directly proportional to the rate of material transfer.

          Screw conveyors can be operated with the flow of material inclined upward. As the angle of inclination increases, the capasity of a given unit rapidly decreases.

Types of screw conveyors:

1) Horizontal screw conveyor
2) Inclined screw conveyor
3) Shaft less screw conveyor
4) Vertical screw conveyor








Source take from Wikipedia




Monday, 6 May 2019

TYPES OF MECHANICAL SEALS


Mechanical Seals are the devices which arrests leakage of fluids when joined the parts or mechanisms together. Mechanical seals are available in different designs. We have to understand first how they function, it will help us to select the suitable for our application.
Different types of mechanical seals are mentioned below they are:
1. Conventional
2. Pusher
3. Non-Pusher
4. Blanced
5. Unbalanced
6. Cartridge 
7. Cortage

1. Pusher type:

Saturday, 4 May 2019

ION EXCHANGER COLUMN






AIR KNOCKER

          Air knocker is a kind of process automation equipment, designed to eliminate problems occuring due to the deposition of powder inside a hopper. This equipment consists of a "Magnetic Piston". Due to the interaction between Magnetic Piston and Air pressure this equipment dislodges some force on hopper. 

AIR KNOCKER

AIR KNOCKER






Sunday, 28 April 2019

WATER SOFTENING PROCESS

          The objective of treatment in a Base Exchange Softner is to convert hardness forming salts of Calcium and Magnesium to soluble Sodium salts. Due to the low solubility of Calcium and Magnesium Salts, they tend to precipitate and form scales when the temperature of water us increased.
          Sodium salts are highly soluble and hence do not form hard scales. The hard water, to be treated, flows through bed of bead type Polystyrene Cation Exchange resins in sodium form, which exchanges sodium ions with Calcium and Magnesium ions present in hard water.

There are two types of hardness present in water.
1. Temporary Hardness: This occurs due to presence of Carbonates and Bicarbonates of Calcium and Magnesium.
2. Permanent Hardness: This occurs due to presence of Sulfates, chlorides and nitrates of Calcium and Magnesium.

          The output capasity of the water softner is inversely proportional to the hardness present in the raw water. The resign has to be regenerated periodically with Sodium Chloride solution of 10-13% concentration.

The ion exchange reaction for the service runcan be presented as follows:

Ca++      +     2 NaR = CaR2       +        2 Na+
Mg++      +    2 NaR = MgR2      +           Na+
(hard water)   (resin in Na form)    (exhausted resin)    (soft water)
where R is the resin.

          From the above reaction, it will be seen that resign retains the Calcium and Magnesium and releases equivalent of sodium to the water leaving the Softner. After the Softner has produced specific quantity of soft water, the softner should be regenerated with Sodium Chloride. The reaction for the regeneration is given below:

CaR2 + 2NaCl       =     2 NaR     +          CaCl2
MgR2 + 2NaCl      =     2 NaR     +          MgCl2
(exhausted resin)  (common salt)   (regenerated Resin)  (waste to drain)
 Where R is the resin.

          It should be noted that the same Softner could produce less amount of Soft Water between two regenrations, with increase in raw water hardness. The quality of soft water may also get affected due to this increase/change in composition of raw water.

Sunday, 14 April 2019

WATER TREATMENT - IMPORTANCE OF REMOVAL OF IMPURITIES

          The major concern in industrial water treatment, where thw water used directly or indirectly in an industrial process, is to treat the water to be suitable for that particular application/process. The use of water in boiler for steam generation is an obvious industrial use. Depending on the process, varying degrees of purity of treated water are required. For example, a textile processing unit will require soft and clea water for process use; a chemical plant will require pure water for process not exceeding 1.0 mg/ltr of dissolved impurities or electronic components manufacturing unit require ultra pure water containing total dissolved impurities not exceeding 0.5 mg/ltr or less. So depending upon the requirement, various water treatment processes are adopted to ttreat the water, to make the water suitable for that particular application. The details of the process are as follows:

FILTRATION
          Filtration is the process of passing a liquid containing suspended matter through a suitable porous material (filtering medium) to efficiently remove the suspended matter in the liquid. This is basically a physical treatment of water.
          Filtration is employed in the treatment of industrial water in order to remove or reduce suspended solids and turbidity. This is of special importance in boiler feed water as otherwise there will be formation of sludge and slit deposits. These will restrict flow, causes overheating and consequent failure of water wall tubes. Furthur, in combination with hardness, these sludge and slit deposits will add to the volume and has the insulating effect of scale deposits.

          1. Filtration is employed as a pre-treatment to softening or demineralising plants to protect the resins in them. It is also employed for treating potable water.
          2. The weakly basic anion resins exchanges only the strong acids such as Hydrochloric acid, Sulphuric acid and Nitric acid.

          There are basically two types of Filters - Gravity type, and Pressure type. For industrial applications the latter are preferred; they can be linked into the mains as they work under pressure and used in conjunction with other water treating equipment like softners, demineralisers without recourse to re-pumping. Also, Presure Filters are easier to install and operate, require less space and minimal civil work.

          Filter media commonly employed are graded and washed sand of effective size 0.35 mm to 0.5 mm resting on supporting underbed of crushed gravel and pebble of four varying sizes, with the coarsest size at the bottom of the bed. The sand depth is 500 mm and the underbed depth also 500 mm.

          The major components of a pressure filter are a steel pressure vessel with dished ends (normally vertical and cylindrical, though larger flows horizontal and cylindrical vessels are employed); internals comprising raw water distributor and filtered water collector-cum backwash water distributor; external pipe work and valves; filter media and instruments like pressure gauges, flow indicator etc.,

          Backwashing of the filter bed has to be carried out periodically (normally once in 24 hours, more frequently if the pressure drop across the bed exceeds 0.7 kg/cm and which indicates accumulation of dirt in the bed) with filtered water at a minimum head of 10 MWC. If air agitation facilitates are provided then the backwash rate can be reduced. The normal backwash time is 5-6 minutes and the scour time 2-3 minutes.

          NormallyFilters should not be fed with water carrying suspended matter and turbidity content of more than 30 to 50 NTU. Above these limits the water should be settled and clarified before Filtration. Also to increase the efficiency of Filtration and to ensure that even fine Suspensions are removed, the ususal practice is to dose Coagulant Chemicals like alum, ferrous sulfates or sodium aluminate at the inlet to the filter by means of a effluent. Activated carbon is used as a filtering Medium when oil/chlorine removal, etc, are required. A layer of processes Manganese Dioxide is incorporated in sand filters for iron removal. A layer of anthracite once the sand bed enhances the filtering capasity by providing in-depth filtration. When anthracite is used for filter can handle turbidity of upto 100 NTU.   

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