Tuesday, September 14, 2010

P-o-o-o-f-f Goes the Chemical Reactor

Norcross M10 Viscosity  Sensor
Norcross has been measuring the viscosity of fluids in chemical reactors for many years. This can be done under a full vacuum or under pressure and at a wide range of temperatures and viscosities.

We recently had a very curious issue, with a customer in China. The M10 would be up and running and working fine. After a few batches there would be a build up of vaporized fluid in the head assembly of the M10. This would eventually cause the unit to malfunction. Why is that we thought?

After visiting the customer we found that when one batch was completed they would pressurize the main reactor to 'push' the product out of the reactor.

Then they would pressurize another feed reactor to 'push' the fluid into the main reactor.

These reactors were being pressurized to only about 15psi but their volume was approx 300 cubic feet. This means the total pressure force in the reactor is tremendous. Thus as the fluid reached the bottom of the feed reactor the pressure blew through the fluid into the 4 inch feed pipe connecting to the main reactor. This action vaporized all the remaining adhesive.

This blow through is like a burst of high energy steam but it is high energy vaporized adhesive at high temperature. There are release ports on the main reactor to vent this pressure burst. The "P-o-o-o-f-f" as we named it lasted approximately 1/2 second.

Even with purge gas flowing in through the M10 the pressure spike was so great that it blows back through the purge lines, in addition to blowing out through the release ports. Thus depositing a vapor of adhesive all through the M10.

Conclusion: When a reactor is emptied by pressure, things will work but it must be filled via a pump to avoid the "P-o-o-o-f-f".

Best to you all,

Bob Norcross