4 replies to this topic

[Fallenangelyk]

Good day, everyone. I am trying to draw a process flow diagram for production of ethyl chloride, but I am confused on what should be used as a fresh feed or feed. Please help me!

 

[shantanuk100]

1. Ethylene + HCl over AlCl3 catalyst -----> give Ethyl Chloride

 

2. Feed consists of 100 kmol/hr flow at 25 C and 1 atm and :-

 

          Ethylene - 48 mol%  = 0.48 * 100 kmol/hr  =   48 kmol/hr of flow

          HCl - 50 mol%          = 0.5 * 100 kmol/hr   =   50 kmol/hr of flow

          Nitrogen - 2 mol%     = 0.02 * 100 kmol/hr  =   2 kmol/hr of flow

 

3. All streams are at 25 C temperature including feed, and all other pressure drops are ignored.

 

4. Amount of Ethylene converted in reaction = 0.9 * 48 kmol/hr  = 43.2 kmol/hr converted so remaining ethylene stream and unreacted reactants are recycled to feed stream. Work out the other values on a similar basis.

 

5. The feed stream  is the mixture of ethylene, hcl and nitrogen, including any recycles, so that is what you have to take as the feed stream.

The fresh feed is the individual component streams and makeup streams if any like nitrogen, ethylene, hcl that we add in pure state.

 

 

Regards,

Shantanu

Edited by shantanuk100, 29 March 2016 - 10:50 PM.

[Pilesar]

The feed stream to the reactor is different from the fresh feed. Start with what you know cannot change: the flow rates of the individual feed components to the reactor. You will then have to calculate your product streams and your recycle streams. The recycle streams will be less mass than the feed stream, so you will have to make up the difference with fresh feed. The fresh feed will be the amount of ethylene and HCl and nitrogen that are required to balance the overall system.

[Fallenangelyk]

I should solve it like this right?

[Pilesar]

Your diagram is not the way I would interpret the problem statement. I read that the 100 kmol/hr is the feed to the reactor so that is the flow the reactor sees. (The reactor sees only the feed stream at the composition and flow rate stated no matter whether the material comes from recycle or fresh feed.) The composition and flows of the rest of the streams are to be calculated. You know the composition of the product stream (and also the flow) and the flow of the purge stream (but not the composition.) You do not know the flow or the composition of the fresh feed. All the stream flows and compositions can be calculated from the information given. It is a puzzle to solve and you start with the reactor effluent. As there can be only one correct way to interpret the problem statement, I suggest you clarify your understanding with the grader if possible.