Details

Parent Category: Incident Alert Archives

Category: Industrial Fires & Explosions Alerts

Published: 08 May 2012

This was a utility coal fired boiler at 11:30 am but at 12:15 pm it was basically scrap metal. The plant had just finished an outage and was in the process of placing the boiler back online. The furnace was started on natural gas and once it had reached a certain point it would switch over to coal. The unit was being filled after the outage and the manual gas valves had been turned on. When the boiler was full it was noted that there was a leak in one of the feedwater heaters, so the boiler was put on hold until the leak could be fixed.

The plant had experienced a problem during the outage with a bathroom toilet. A plumbing company came in to fix the problem. When an adjacent building was built the plumbing was tied into this facility and a new PVC drain line was installed. The contractors who installed the PVC line did not know that the drain they installed was about 6” away from the blowdown line from the boiler. The blowdown line would heat up and melt the PVC drain line. When the plumber came into fix the drain problem he used a snake down below the toilet and ran into a check valve that was installed to prevent the backflow from the adjacent building from going up into the toilet. The toilet in the adjacent building was flushed and it flowed down the drain until it came to the melted line. It backed up and since the check valve was damaged it when up the line to the toilet upstairs. This toilet was located just above the room that housed the PLC controls. The water ran down on the PLCs and caused a short in the valve the controlled the Natural gas control valves and the burner igniter. The gas valves were opened and the igniter was initiated.

The fuel filled the furnace and was lit off. This created a huge fireball almost an explosion. When this fireball hit the top of the furnace it lifted the boiler up off it’s pendants and when it came down it broke the pendants. This allowed the boiler to drop into a pile on the ground.

The two guys that were working on the feedwater heaters heard a problem and moved to the other side of the turbine deck. This was the only thing that saved their lives.

It cost $290 million to replace the boiler. The replacement time was 18 months. The loss of electricity caused the owner to bring online two units that had not been online in 10 years. The price of electricity went up and the price of scrap metal dropped.