Posted tagged ‘operation’

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)

Oscillating Conveyor System

September 8, 2011

Selection of vibratory conveyor:

01-vibrating conveyor-vibrating conveyor applications-vibrating conveyor belt-vibrating conveyor motor-oscillator-reciprocating conveyor-shaker conveyor-inertia conveyor

The oscillating motion of the trough is achieved via specially designed inclined arms and an eccentric shaft driven by a motor through V-belts. The eccentric shaft is mounted on anti friction bearings and has V-pulleys at both ends with weights on them to counteract the unbalancing force. The rotation of the eccentric shaft provides a forward and backward motion to a connecting arm attached to the trough through a rubberized pin. The trough motion is predominantly horizontal with some vertical component, which causes it to oscillate with a pattern conductive to conveying material. A retaining spring assembly at the back of the trough absorbs shock load. All components including drive motor are mounted on a rigidly constructed base frame.

Advantages:

· Hot and abrasive materials can be handled

· Cooling, drying and de-watering operation can be done during transport

· Scalping, screening or picking can be done

· Units can be covered and made dust tight

· Simple construction and low head room

· Can be made leak proof

Disadvantages:

· Relatively short length of conveying ( about 50m Maximum)

· Limited capacity, about 350 tons per hour for length of conveying of 30 m.

· Some degradation of material takes place.

Applications:

Vibratory conveyors find wide spread application in the transportation of dusty, hot, toxic, and chemically aggressive bulk material through a closed trough or pipe in chemical, metallurgical, mining industries and manufacturing of building materials.

Vibratory conveyors are also employed for transportation of steel chips in machine shop, hot knocked out sand, wastes and small castings in foundry shop. Vibratory feeders are also in use for delivery of small machine parts like screws, rivets etc.

Sticky materials like wet clay or sand are unsuitable for vibratory conveyors. In handling finely pulverized materials, like cement etc., the performance of such conveyors are reported to be poor.

Vibratory conveyors are hardly employed for handling common bulk loads, such as sand, gravel, coal etc as the same can be done more efficiency by belt conveyors.

Operation Wild October Morning….!!

August 23, 2011

The world had shown me ten million ways to hate

i thought they should be the ten million ways to love…..
I never knew that they are The Unique Ten million ways to f**k myself off….!
I guess most of men have a little private reserve of their own in some corner of their souls where they don’t welcome intruders…..!!
I lacked that…!!
And that made most of this crap…!!!
Yet The Word
“Wild October Morning”
Has got something significant…!
Tropical By Birth ,tropical By Nature…!
The ocotber, fall winter spring
Trees shed their leaves in the hope of new leaves….!!
In my life too
Some people exit from my diary and some new people enter…!!
I happened to knew from all my f*****g experience that It is me who has to keep the other people in my diary Happy….
Of course
Its me who need to stay happy through out My life history….
Losing my happienes for makin othr ppl to stay cool may end me up as dumbass…!
The word i always wanted to avoid is “AVOID”
When u r walkng along road smbdy may avoid u…
but heart feels like hell wen smbdy whom u fought , smiled and of course shared some inner most feelings …!!
This i never wanted to let happen…!!
It could be fair to exit from their territorial waters before being thrown out ..!!
Okay….
enough is enough….
Yes its always enough…
My creative brain(Used it very well in my INtermediate daz…!!)
and now i’m ” IN Term Idiot” to fell as a prey for some unfrank ,pirated emotions….!!
Yet most of my octane cylinders got emptied….
Buy i’m fortunate nough to have ppl lyk Avnsh,rajeev,krishna,reddy,akash…etc……
to refill those cylinders….!!
The first ever Flight of ASPIRATION AIRWAYS si ready to take its flight….!!
Injected with MAd Adrenaline….
Hope i cud end my show with flying colors….
Anyway dis May has marked few new ppl in my Diary
a cute little sister
and cute friend who had found littile interest in my LOST Mechanical diary crap…!
Nd no more inclusion of people suffering from Psyche Flu(a psychological version of Swine flu…!)
And Today is Rabia’s B’Day…
Happy B’day Rabia…!!
—– MooNY(My New Nickname..!!)

FMEA

August 23, 2011

01-Aircraft-Maintenance-manufacturing-aviation-failure mode and effect analysis-fmea

Failure Mode – A particular way in which an item fails, independent of the reason for failure.

 Failure Mode and Effects Analysis (FMEA) – A procedure by which each credible failure mode of each item from a low indenture level to the highest is analyzed to determine the effects on the system and to classify each potential failure mode in accordance with the severity of its effect.

Indenture Levels – The hierarchy of hardware levels from the part to the component to the subsystem to the system, etc.

Redundancy – More than one independent means of performing a function.  There are different kinds of redundancy, including:
(1) Operational – Redundant items, all of which are energized during the operating cycle; includes load-sharing, wherein redundant items are connected in a manner such that upon failure of one item, the other will continue to perform the function.  It is not necessary to switch out the failed item or switch in the redundant one.

            (2) Standby – Items that are inoperative (have no power applied) until they are switched in upon failure of the primary item.

            (3) Like Redundancy – Identical items performing the same function.

            (4) Unlike Redundancy – Non identical items performing the same function

THE FMEA PROCESS

01-web- failure analysis-unexpected failure-operational fracture-failure rate

  • Define the system to be analyzed.  A complete system definition includes identification of internal and interface functions, expected performance at all indenture levels, system restraints, and failure definitions.  Also state systems and mission phases not analyzed giving rationale for the omissions.

  • Indicate the depth of the analysis by identifying the indenture level at which the analysis is begun.

  • Identify specific design requirements that are to be verified by the FMEA.

  • Define ground rules and assumptions on which the analysis is based.  Identify mission phases to be analyzed and the status of equipment during each mission phase.

  • Obtain or construct functional and reliability block diagrams indicating interrelationships of functional groups, system operation, independent data channels, and backup or workaround features of the system.

  • Identify failure modes, effects, failure detection and workaround features and other pertinent information on the worksheet.

  • Evaluate the severity of each failure effect in accordance with the prescribed severity categories.

FMEA Flow Diagram:

01-FMEA FLOW DIAGRAM-STEPS-PREVENTIVE ACTION-CORRECTIVE ACTION

History:

The FMECA was originally developed by the National Aeronautics and Space Administration (NASA) to improve and verify the reliability of space program hardware.

FMECA Flow Diagram: ( Failure Mode, Effects and Criticality Analysis )

01-FMECA Flow Diagram- Failure Mode Effects and Criticality Analysis

Criticality Analysis Flow:

01-quantitative method-qualitative method-analysis-criticality analysis flow diagram

Who is the Team ?

 

Areas to be represented are:

  • Quality
  • Logistics
  • Engineering
  • Purchasing
  • Manufacturing
  • Sales
  • Tooling
  • Marketing
  • Customer
  • Supplier

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.

QTC

August 23, 2011

01-3D tablet-touch screen-force sensitive touch screen-quantum tunnelling composite

QTC is a composite made from micron-sized metallic filler particles (Silicone Rubber) mixed into an elastomeric matrix. Quantum tunnelling composite is a flexible polymer that exhibits extraordinary electrical properties. In its normal state it is a perfect insulator, but when compressed it becomes a more or less perfect conductor and able to pass very high currents.

01-QTC-Graph-resistance vs force - quantum tunnelling composite

History:

First produced in 1996, QTC is a composite material made from conductive filler particles combined with an elastomeric binder, typically silicone rubber. The unique method of combining these raw materials results in a composite which exhibits significantly different electrical properties when compared with any other electrically conductive material.

01-QTC pills-variable resistor-applications of QTC using pills-touch switches

Types of QTC:

1. Elastomeric (Material: Silicone Rubber) (The particle move close together)

2. Ink / Coating Solvent or Aqueous Polymer

3. Granular Sensors

Working of Quantum tunnelling composite:

01-quantum tunnelling composite-QTC-smart flexible polymer-silicone rubber-pressure switching-sensing-metal like conductor-variable inductance principle-QTC working-QTC operation

QTC usually comes in the form of pills or sheet. QTC pills are just tiny little pieces of the material. The sheets are composed of one layer of QTC, one layer of a conductive material, and a third layer of a plastic insulator. While QTC sheets switch quickly between high and low resistances, QTC pills are pressure sensitive variable resistors.

Application:

01-QTC touch Screen-pills-force or pressure sensors-quantum tunneling composite screen-pressure sensitive variable resistors

– Touch switches (sheet)
– Force/pressure sensors (pills)
– Motor speed control using force (pills)

Benefits:

  • QTC is a pressure/force sensing material. It can be easily integrated into existing products to enable force sensing opportunities and solutions.
  • Product surfaces can be incorporated, coated or impregnated with QTC to impart the properties of force sensing into or onto the host surface.
  • QTC material can be formed or moulded into virtually any size, thickness or shape, permitting redesign of product interfaces and providing improved ergonomics, aesthetics and user comfort.
  • QTC is an enabling technology which is simple and reliable to use.
  • QTC material is durable – it has no moving parts to wear out.
  • QTC material is mechanically strong.
  • QTC material can be made to withstand extreme temperatures limits.
  • QTC material is versatile, both electrically and physically e.g. Its range and sensitivity can be altered. QTC material is also intrinsically safe – the material is a contactless switch, ideal for sparkless operation.
  • QTC material can be directly interfaced to standard electronic and electrical devices.
  • QTC material and/or technology can be customized for customer requirements, applications and products.

Artificial photosynthesis

August 23, 2011

Artificial photosynthesis is one of the newer ways researchers are exploring to capture the energy of sunlight reaching earth.

01-photosynthetic reaction-receive sunlight as photons-transfer energy to a network of pigment protein complexes

Photosynthesis:

01-Photosynthesis-basics-operation-oxygen release-hydrogen splits


Photosynthesis is the conversion of sunlight, carbon dioxide, and water into usable fuel and it is typically discussed in relation to plants where the fuel is carbohydrates, proteins, and fats. Using only 3 percent of the sunlight that reaches the planet, plants collectively perform massive energy conversions, converting just over 1,100 billion tons of CO2 into food sources for animals every year.

Photovoltaic Technology:

This harnessing of the sun represents a virtually untapped potential for generating energy for human use at a time when efforts to commercialize photovoltaic–cell technology are underway. Using a semiconductor–based system, photovoltaic technology converts sunlight to electricity, but in an expensive and somewhat inefficient manner with notable shortcomings related to energy storage and the dynamics of weather and available sunlight.

Artificial Photosynthesis:

01-photosynthesis system-Artificial Photosynthesis-Artificial Photosynthesis Solar energy to produce hydrogen directly used in fuel cell

Two things occur as plants convert sunlight into energy:

  • Sunlight is harvested using chlorophyll and a collection of proteins and enzymes, and
  • Water molecules are split into hydrogen, electrons, and oxygen.

These electrons and oxygen then turn the CO2 into carbohydrates, after which oxygen is expelled.

Rather than release only oxygen at the end of this reaction, an artificial process designed to produce energy for human use will need to release liquid hydrogen or methanol, which will in turn be used as liquid fuel or channeled into a fuel cell. The processes of producing hydrogen and capturing sunlight are not a problem. The challenge lies in developing a catalyst to split the water molecules and get the electrons that start the chemical process  to produce the hydrogen.

There are a number of promising catalysts available, that, once perfected, could have a profound impact on how we address the energy supply challenge:

  • Manganese directly mimics the biology found in plants.
  • Titanium Dioxide is used in dye-sensitized cell.
  • Cobalt Oxide is very abundant, stable and efficient as a catalyst

Artificial Photosynthesis Operation:

01-artificial Photosynthesis-arrays of microwave coated catalysts-split water to make hydrogen or liquid hydrocarbon fuels

Under the fuel through artificial photosynthesis scenario, nano tubes embedded within a membrane would act like green leaves, using incident solar radiation (H³) to split water molecules (H2O), freeing up electrons and oxygen (O2) that then react with carbon dioxide (CO2) to produce a fuel, shown here as methanol (CH3OH). The result is a renewable green energy source that also helps scrub the atmosphere of excessive carbon dioxide from the burning of fossil fuels.

01-artificial photosynthesis solar collector to energy-concentrated solar radiation- convert photosynthesis to Hydrogen and oxygen

History:

Plants use organic compounds that need to be continuously renewed. Researchers are looking for inorganic compounds that catalyze the needed reactions and are both efficient and widely available.

The research has been significantly boosted by the application of nano technology. It’s a good example of the step wise progress in the scientific world.

Studies earlier in the decade showed that crystals iridium efficiently drove the reduction of CO2, but iridium is extremely rare so technology that required its use would be expensive and could never be used on a large scale.

Cobalt crystals were tried. They worked, and cobalt is widely available, but the original formulations weren’t at all efficient.

Things changed with the introduction of nano technology.

The main point is that this unique approach increasing appears to be feasible. It has the advantage of harnessing solar energy in a form that can be stored and used with greater efficiency than batteries and it is at least carbon neutral.