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13. What is the use of gear pumps in motor?
Gear pumps uses meshing gears that allow the pump fluid to be displaced by the
method of displacement. They are used for hydraulic fluid power applications.
They are one of the key factors involved in chemical installation having a
certain viscosity to pump fluid. This type of pumps uses positive displacement
pump having high pressure and low capacities. This includes the ability to
handle wide range of viscosities, and allow easy to build and maintain the
pumps. The gear pumps are controlled through the motor speed. Gear pumps can’t
handle high tolerances and the fluids that are free of abrasives.
14. What are the factors involved in considering the choice of dry screw
compressor?
Screw compressors are made up of a pair of meshing helical screws that is used
to compress the gases. The dry screw compressors are used to have a flow range
of 85-170 m/h and the discharge pressure is of 2070-2760 kPa. The dry screw
compressor consists of timing gears that is maintained aligned with the rotors.
The effectiveness is dependent on the clearances that exist between the helical
rotors and between the chambers used for sealing the compression cavities. They
are compact and smooth having the limited vibration and require spring
suspension as well.
15. What is the process of including heat exchangers in ammonia refrigeration
system?
The heat exchangers are used in ammonia refrigeration system from a very long
time. The heat exchanger used is having smaller sizes and they are equivalent
to the tubular exchanger can. This process works best for flooded system that
require a separate liquid from the vapor. The system that is explained consists
of a vessel, a drum, and accumulator and header tank with the heat exchanger.
It works like this:
>Liquid ammonia moves from vessel to exchanger
>Vapor is returned to middle of drum
>Vapor is removed from the drum and liquid enters through exchanger as it
has lower density than others entering at the same rate in the system
16. What is the method adopted to minimize shell side pressure drop in a shell?
The method of protecting the shell from the pressure drop is very essential as
it is very critical stage, where if not taken care properly the shell has to be
replaced due to its degradation. In this rods or tube protectors are used
instead of plates in top rows. The use of these rods puts less pressure drop
and provides better distribution of the pressure on the plate. The plate that
is used causes an abrupt of 90 degree turn of shell stream and an extra
pressure drop on the whole shell. Use of the tube protectors will allow the
shell to be saved from this and maintains its longevity.
17. What are the strategies acquired to cure tube vibration and exchangers in a
shell?
The strategies that can be followed are as follows:
>To cure the tube vibration uses the tubes that doesn’t allow passing of the
flow-induced vibrations through them and are longer in height than others.
Usually the tubes supported
>Are of 3-4 inch. To make the bundle stiff insert metal slats and rods
between the tubes that is used in the process.
>Add a shell nozzle opposite of the inlet to cut the flow of the velocity of
the fluid in half. This solution works for non-removable bundles that can
easily be solved also by adding a distributor belt on the shell. This might be
expensive solution to adopt as it requires more man power and use of more
tubes.
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