Er.Md.Roomi Azad
Monday, 5 March 2012
Monday, 20 February 2012
PLANT LAYOUT
It means the deposition of various facilities such as
equipments, materials, men power etc. and service of the plant within the area
of the site selected.
Objectives of Good Plant layout
:
(i)
Material handling and transportation is minimized and
efficiency controlled.
(ii)
Work stations are design suitably and properly.
(iii)
Suitable place are allocated to production centre.
(iv)
The movement made by the worker are minimizes.
(v)
Working conditions are safer, better and improve.
(vi)
Plant maintenance is simpler etc.
Principle of Plant Layout :
(i)
Integration :
It means the
integration of the production centres. Facilities like, worker, machinery, raw
material etc. in a logical and balanced manner.
(ii)
Minimum movement and
Material handling :
The no. of
movements of the workers and materials should be minimized . It is better to
transport, materials in optimum bulk rather then in small amount.
(iii)
Smooth and continuous flow :
Bottle necks using the
floor space of room. If the ceiling height is maximum also utilized more
material and can be accommodate in the same room. Boxes or bags containing raw
materials or good can be stocked on above the other stored items in the same
room.
(iv)
Safe and improve environment.
Working place are safe,
free from dust, noise and other hazardous condition deciding increase the
operating efficiency of the worker and improve their morals.
(v)
Flexibility.
In automatic and other in
dust rise where models of products
changes after sometimes. It is better to permit acc possible flexibility in the
lay out the machinery are arranged pm such away the changes of production
process can be achieved at the least cost and disturbances.
(vi)
Process Layout.
It is also known as functional lay out and it concertized
by keeping similar location in other words all to the will be one place all
milling machines at another an shown, I e machine have been arranged according to their
functions . this type in distress engaged in job order production and
non-reparative or manufacturing activities.
1. Store Room
2. Inspection Department
3. Broaching
section
4. milling section
5. La the section
6. Shaper section
7. Drill section
8. Stock Room
Advantages :
(i)
Wide
flexibility enlists as regards of works to equipments and workness.
(ii)
Better
utilization of the available equipment.
(iii)
Comparatively
less number of machines are needed.
(iv)
Better
product quality because of the Supervisor and Workers attend to one type of M/C
or operation.
(v)
Varieties
of job coming as different job orders. Make this work more interesting for the
workers.
(vi)
Workers
in one section are not effected by the nature of operation carried out in
another, For example- A Lathe operation is not effected by the raye of welding
as two section are quite separate.
Disadvantages :
(i)
for the some amount of
production layout needs more space.
(ii)
Automatic material handling is
extremely difficult.
(iii)
More materials in process
remains in queue for further operation.
(iv)
Competition of same produce
takes more time.
(v)
Work in process inventory is
large.
(vi)
Production controls become
difficult distance for being processed to finished handling and also located.
(vii)
It needs more inspection and
efficient co-ordination.
Sunday, 19 February 2012
Domestic Electrolux Refrigerator
Introduction:-
In the vapour absorption system, the compressor is replaced by an absorption, a pump and generator and a pressure reducing valve. This components in vapour absorption system, perform the same function as that of a compressor in vapour refrigerant from the evaporation is drawn into an absorber where it is absorb by the weak solution of the refrigerant forming a strong solution. This strong solution is pumped to the generator where it is heated by some external source. During the heating process the vapour refrigerant is driven off by the solution and enters into the condenser where it is liquefied. The liquid refrigerant, then close into the evaporation and this the cycle is completed.
Domestic Electrolux Refrigerator:-
The idea was first developed by the ‘Electrolux company’ of Luton , England.
This type of refrigerator is also called three- fluid absorption system.
Main purpose of system:-
Is to eliminate the pump so that in the absence of moving parts, the machine becomes noiseless. The three fluids used in this system are ammonia, hydrogen and water. The ammonia is used as a refrigerant because it possesses most of the desirable properties. It is toxic, but due to absence of moving parts, there is very little chance for the leakage and the total amount of refrigerant used is small.
Uses of Hydrogen:-
The hydrogen the lightest gas, is used to increase the rate of *evaporation of the liquid ammonia passing through the evaporator. The hydrogen is also non- corrosive and insoluble in water. This is used in the low- pressure side of the system. The water is used as a solvent because it has the ability to absorb ammonia readily . The principle of operation of a domestic Electrolux type refrigerator, as show in Fig. 1, is discussed below.
Uses of Ammonia:-
The strong ammonia solution from the absorber through heat exchanger is heated in the generator by applying heat from an external source, usually a gas burner. During this heating process, ammonia vapors are removed from the solution and passed to the condenser. A rectifier or a water separator fitted before the condenser removes water vapor carried with the ammonia vapors, so that dry ammonia vapors are supplied to the condenser.
These water vapors, if not removed, will enter into the evaporator causing freezing and choking of the machine. The hot weak solution left behind in the generator flows to the absorber through the heat exchanger. This hot weak solution while passing through the exchanger is cooled. The heat removed by the weak solution is utilized in raising the temperature of strong solution passing through the heat exchanger. In this way, the absorption is accelerated and the improvement in the performance of a plant is achieved.
The ammonia vapors in the condenser are condensed by using external cooling source. The liquid refrigerant leaving the condenser flows under gravity to the evaporator where it meets the hydrogen gas. The hydrogen gas which is being fed to the evaporator permits the liquid ammonia to evaporate at a low pressure and temperature according to Dalton’s principle.
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