Question

In a typical large scale chemical process plant design for example Nitric acid

1-describe the basis of any decision made around recycle streams and,

2-explain what are the key variables associated to the recycles

Pleae explain in detail

Thanks

Answer 1

In case on the Nitric acid plant, the recycling is basically done at the reaction and absorption section in order to consume maximum quantity of the reactant and increase the concentration of the final product.

The decision made around recycle stream is mainly based on the cost associated with the Operating of the section and the difficulty associated in doing so.

The basis of design for recycle stream would be saving in the OPEX. The absorption section follows counter current flow in order to certain maximum absorption. The recycling of the vent gas also can be done based on the Enviornmental obligations.

The key variables associated with the recycles are:

1. Purpose

2. Operating parameters

3. Sandard acceptable vent norms

4. OPEX optimization

5. CAPEX associated