Keywords: natural gas, explosions, HAZOP, start-up, ignition, furnace.
On April 1st 2003 an explosion occurred in a gas-fired furnace in the melamine plant of DSM in Geleen. Three people sadly lost their lives during the accident. The gas-fired furnace at which the accident occurred generates heat for the melamine process and is installed next to this plant as a separate unit. The explosion occurred during start-up of the furnace after a short maintenance stop. A detailed root cause analysis was done and the conclusions drawn are also applicable to other parts of the chemical industry.
After this accident new Hazard and Operability (HAZOP) Safety Analyses were performed on all gas-fired equipment of DSM. This new HAZOP was also done for the fertiliser plants of DSM. Here the focus was for a major part on the ammonia plants where gas is fired in the primary reformer, the auxiliary boiler, the start-up furnaces and the gas turbine.
The perception is often that natural gas is not a dangerous gas and therefore the risks of operating a gas-fired apparatus are not always recognised. There is clearly an effect of complacency in the use of natural gas in plants.
The dedicated HAZOP performed by DSM for their fertiliser plants resulted in a lot of potential improvement. With regards to instructions and procedures it is essential to make sure that clear instructions are present and that work is done exactly according to these instructions. Operators not following the work procedures create new operating methods and the SHE aspects of these new methods are not always reviewed properly. This is especially important during start-up of gas-fired equipment. This is by far the most dangerous moment because starting up gas-fired apparatus is not easy and it is not done frequently. If the first start-ups fail, operators can become creative in finding ‘ways round’ giving rise to unsafe situations. Furthermore it was concluded that because of the explosion risks local panels should be prohibited close to gas-fired equipment.
Harrie Duisters, DSM Agro, PO Box 29, NL 6160 MG Geleen, The Netherlands.
23 Pages, 1 Figure, 4 Tables, 10 References.