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Chemical Reactor Related interview Questions contained in this blog which are asked in chemical industry

Chemical Reactor Related interview Questions


1. Why steam enters top side of jacket in reactor?
2. Why the hot liquid in heat exchanger, reactor jacket should flow from bottom to top?
3. What is the function of catalyst in chemical industry?
4. Difference between Reversible and Irreversible chemical reactions

1. Why steam enters top side of jacket in reactor?

If we pass the steam from bottom side the condensate that is formed after losing the heat won’t have a comfortable passage to get out of the system.

Chemical Reactor Related interview Questions


In turn the entering steam will start to heat the returning condensate rather than heating the reactor surface. That’s why we have to pass it from the top.


2. Why the hot liquid in heat exchanger, reactor jacket should flow from bottom to top?

If we pass the liquid from top to bottom, it will flow fast by gravity itself. So it will have less contact time with the heat exchanger/reactor surface which will result in poor heat transfer.

That’s why the hot fluid should be passed from bottom to top to maximize the contact time. The same is applicable for cold fluid also in reactors.

Chemical Reactor - cut view



3. What is the function of catalyst in chemical industry?

A catalyst improves speed of chemical reaction by providing an alternate reaction pathway with lower activation energy. 

Since the activation energy is lower, more products will be formed in the same amount of time.

4. Difference between Reversible and Irreversible chemical reactions.

In reversible reaction, reactants react to form a new product & are get back the original product or reactant. 

While in irreversible reaction, it’s impossible to get back original product or reactant.
In reversible reaction, changes  take place  very  slowly  through  a series  of intermediate step in the equilibrium state. 

While in irreversible reaction, there is no equilibrium state.


5. How much power required for agitation?

It is a function of RPM.

It is also depends on 

  • Viscosity of fluid
  • Density of fluid.
  • Dimensions of vessels and Impeller

It is related by dimensionless form as:

How much power required for agitation.
Where

How much power required for agitation 2

P=power required for agitation

n = rotational speed of impeller

Da= diameter of impeller

९= density of fluid

μ=viscosity of fluid

For baffled vessels, Power number (Np) does not depend on the value of Froude number (Nfr). and it is only a function of Reynolds number (NRe).

Empirical correlations and charts are available with the dimensional groups to get Np. from which power required for agitation is calculated. This required power is supplied by means of electrical drive / gearbox assembly and transmitted to the vessels by the impeller attached with the shaft coupled to the drive.

The mechanical design of agiated vessel is calculated as per pressure vessel design codes such as ASME Section VIII Division 1 or IS 2825.



 

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