Pressure drop calculation
Pressure drop calculation
(OP)
I have a vacuum distillation column with vacuum of 15 inHG being pulled from overheads condensate receiver. There is a pressure equalization line from overheads condenser to this receiver.
At increased vapor loads, condenser will not handle so I am installing a vent condenser on vacuum line from receiver to vacuum pump. At high vapor rates, about 3000 lbs/hr of acetone flows through equalization line ( condenser to condensed liquid receiver) How should I calculate pressure drop across this 2" line?
Does pressure in my receiver and condenser will be same due to equalization line?
Thank You
Koshy
At increased vapor loads, condenser will not handle so I am installing a vent condenser on vacuum line from receiver to vacuum pump. At high vapor rates, about 3000 lbs/hr of acetone flows through equalization line ( condenser to condensed liquid receiver) How should I calculate pressure drop across this 2" line?
Does pressure in my receiver and condenser will be same due to equalization line?
Thank You
Koshy





RE: Pressure drop calculation
rmw
RE: Pressure drop calculation
The equalization line should be a separate line and it should see vapor only. It should be connected from the top of the condenser (or the line to the vacuum pump) down to the vapor space at the top of the receiver.
You are correct that the pressures in the condenser and receiver are (or should be) the same. That is what the equalization line is for. The head that drives the liquid from the condenser to the receiver is the static head due to the difference in heights - the receiver is placed below the condenser.
I suppose it would be possible to combine the liquid drain line and the equalization line into one if the line was sized for self venting flow. The line would have to run from the bottom of the condenser to the vapor space of the receiver and have no low points in it. It sounds as though this is what you have and 3000 lb/h of acetone in a 2" line is just at the limit of self venting flow. In my opinion you are lucky that this system works and this type of arrangement should be avoided.
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: Pressure drop calculation
Liquid flows through bottom discharge. At high rates, excess vapors will flow through equalization line to receiver and will be pulled by vacuum pump. My intention is to condense these excess vapors using a BEM type condenser installed on vacuum line between receiver and vacuum pump.
I request for how to calculate pressure drop in eqalization line( flow is 3000 lbs/hr). IS the type of configuration have success? what is momentum factor? ( used in vapor nozzle sizing)
Thanks a Lot
Koshy
RE: Pressure drop calculation
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: Pressure drop calculation
Katmar,
I agree with you on pipe size. Existing condenser nozzle is 2" and 3.5" pipe will work at 3000 lbs/hr.
Can I still use 2" condenser nozzle and upsize my pipe to 3" with a reducer? Please advice me
Thank You very much
RE: Pressure drop calculation
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: Pressure drop calculation
I guess I did my home work after some inputs from this post.
Maximum vapor flow rate handled by main condenser is 23,500 lbs/hr of acetone. At high rates, ( 26,000 lb/hr) I need another small condenser ( this rate is limited by flooding in columns with high efficiency trays, superfrac) to handle this rate.
Option 1: Installing vent condenser on vacuum line to pump requires more piping and hence pressure drop.
Option 2: Parallel condenser requires vapor flow meter and control valves on chilled water and vapor side( pressure drop and cost)
Option 3: To install condenser on pressure equalization line. This seems to be better as I have to upsize only one nozzle on main condenser and ofcourse piping too.
I have attached drawing in my previous post. Please help me with your advice/ recommendations on above options.
Thank you Katmar and rmw.
Koshy
RE: Pressure drop calculation
Thank You
Koshy