Dateline: March 20, 2007

News
Technically Speaking

North America

Fault Determined
The U.S. Chemical Safety and Hazard Investigation Board (CSB) faulted Formosa Plastics and Borden Chemical for a 2004 accident at a polyvinyl chloride (PVC) plant in Illiopolis, Illinois that killed five workers.  The CSB said Formosa and Borden did not adequately plan for consequences of human error.  Formosa bought the plant from Borden in 2002.

World

New Projects
Methanex is considering a di-methyl ether (DME) project in Egypt to be built alongside its planned 1.3 million ton/year methanol project there.  In addition, the company has signed a memorandum of understanding with GeoPark Holdings providing for the long-term supply, development and acquisition of new natural gas reserves in Chile, including a 10-year gas supply and purchase commitment from GeoPark’s Fell Block in southern Chile, beginning in May.  The agreement includes incentives for volume growth up to 100 million cubic feet/day of natural gas and includes provisions for the financing of development operations and the potential joint acquisition of new hydrocarbon blocks in Chile.

Technically Speaking

I need to protect a vertical knock out drum against freezing with a minimum ambient temperature of 14 °F (-10 °C).  What would be a good method?

Steam Option:

"I've done this several times in Chemical processing plants and the results turned out very well each time. What I've done is the following:

1. Strip the vertical drum of any insulation and clean the drum of all surface paint and rust;

2. Obtain and apply a mortar-like paste called "Thermite" ( a special, heat-transfer cement made by a company in San Antonio, TX) and on top of the mortar wind a 1/2" copper tube in a spiral coil - starting at the bottom cylindrical seam and stopping at the top horizontal seam. The coil should be tightly wound and tight so that the contact between the drum's surface, the mortar and the coil will be as close as is possible. You will be depending on CONDUCTION as the primary heat transfer, so you want the surfaces to be intimate.

3. When the mortar sets, you can insulate the results. Introduce low pressure (waste) steam at the top of the coil and put a small, thermostatic steam trap at the bottom exit. You can control the steam flow automatically or manually. The drum will be heated and winterized.

If you ever maintain a low level in the drum (below the lower cylindrical seam, then you should also put a coil on the bottom head. This coil would be a flat, pancake shape formed around the head such that the top inlet is just below the lower cylindrical seam and the outlet is near the center, bottom of the head. Again, introduce steam at the top and put a steam trap at the bottom. Insulate the results and be sure to vapor seal.

I hope this helps you out. You can find the Thermite cement source by asking for it in the industry or searching on the Google database engine. Go to: http://www.thermon.com/ and click on "Catalog". You can download a lot of useful information on heat tracing."

Art Montemayor via Cheresources.com Forums

Electric Option:

"Electric heat tracing is another option that is worth looking at. It runs at minimal temperatures. I can safely put my hand on it and it feels only moderately warm. If you are a long distance from a suitable heat source it may be an easier installation. It can use a surprising amount of electricity (depending on how much tracing you require), so it is worth getting an electrical person involved to estimate the requirements. You will want to consider how this will impact your electrical bill and utility supply. However, the advantage is that it can be easily controlled by automatic temperature controls, so you don't need to run it when the temperature is above freezing.

You should also heat trace the liquid line out of the vessel, particularly if flow is intermittant. Same options on tracing medium apply as above. However, another option that can be used is a utilidor. This is an insulated box that contains your piping. you also run other piping that is hot (waste heat source) in the utilidor to keep it warm. Of course, this requires that you have such piping in the immediate area."

Shaun Hill via Cheresources.com Forums