JBCheney
Mechanical
- Aug 19, 2003
- 1
Can anybody give me any advice regarding back-up heavy fuel oil firing of boilers.
We have a set of six Thompson steam boilers, fed primarily from gas, but the essential back-up system is of heavy fuel oil which used to be used as the primary source of fuel.
The fuel oil is recirculated from storage tanks, to high pressure gear pumps ( to 15 Bar) through filters and heaters ( to 125DegC) to the burners, and while not used recirculated back to tank. The problem is that the temperature of the tanks is above the flash point (66DegC) and has been considered a safety risk, and I'm looking to install a recirculation leg from the burners to the pump suctions. The temperature and pressure has to be kept as is for essential quick change over in case of a power cut.
The problem is that by circulating the oil to the pump suction, the inlet pressure will be dictated by the head of the tanks, which is only 5 metres. I've found that the oil will flash at any pressure/head lower than 2 barg, therefore the oil will flash. What I haven't been able to ascertain is whether the vapour would be significant, and cause pump cavitation wear over time. The oil suppliers have not been forthcoming with data or advice.
I've found that the industry standard is to have low pressure feed pumps from tank to high pressure pumps, this could be an expensive outlay if not necessary.
Any ideas/comments? Thanks in advance.
We have a set of six Thompson steam boilers, fed primarily from gas, but the essential back-up system is of heavy fuel oil which used to be used as the primary source of fuel.
The fuel oil is recirculated from storage tanks, to high pressure gear pumps ( to 15 Bar) through filters and heaters ( to 125DegC) to the burners, and while not used recirculated back to tank. The problem is that the temperature of the tanks is above the flash point (66DegC) and has been considered a safety risk, and I'm looking to install a recirculation leg from the burners to the pump suctions. The temperature and pressure has to be kept as is for essential quick change over in case of a power cut.
The problem is that by circulating the oil to the pump suction, the inlet pressure will be dictated by the head of the tanks, which is only 5 metres. I've found that the oil will flash at any pressure/head lower than 2 barg, therefore the oil will flash. What I haven't been able to ascertain is whether the vapour would be significant, and cause pump cavitation wear over time. The oil suppliers have not been forthcoming with data or advice.
I've found that the industry standard is to have low pressure feed pumps from tank to high pressure pumps, this could be an expensive outlay if not necessary.
Any ideas/comments? Thanks in advance.
