One Series programmable temperature controls from Able have been used as part of a GBP22,000 upgrade of a natural draft utility heater. The heater was only achieving 64 per cent combustion efficiency and was having problems maintaining process temperature. Each of the two fire tubes was estimated to have approximately 3.5 million BTU per hour.
The eight-wire One Series maintained a process temperature of 272C, with only one fire tube running at 68 per cent combustion efficiency. Its two independent solid-state relays allow for the separation of the control points and precise setting for each dead band, which eliminated previous process temperature overshoot and undershoot issues. The second fire tube has a live pilot, which will turn on if the process temperature drops below 267C.
A 4-20mA auxiliary output is included, which can be tied into a PLC/DCS as a trending and monitoring function. The total volume of air is now being heated by one fire tube and is approximately 105,000 SCF per hour; this is a reduction in air volume and translates to more heat into the process and less wasted into the atmosphere. The efficiency gains with using the One Series temperature controls will pay for the system upgrade in as little as two months, with approximately GBP410 per day being saved in fuel costs.
