“My UV flame detector worked last week, and now it keeps shutting down the system, even though the flame is there. I ran diagnostics, and it’s not the detector. Can you help?”
When an instrument or technology works, it’s frustrating when all of a sudden, it stops… especially when it causes your burner or boiler process to stop unexpectedly and without reason. What’s the cause? Is it the flame detector? The control? Wiring? A valve or switch in the fuel train? Or might it be caused by the flame?
More and more chemical plants are mixing hydrogen into their natural gas fuels in incinerator and super-heater applications, either for burn-off or to cut costs. Studies have shown that adding even 5% hydrogen can descrease NOx and CO emissions by up to 50%. And, hydrogen is considerably less expensive than natural gas for an equivalent BTU output.
It’s a great plan: The plant saves fuel costs and reduces greenhouse gas emissions, reducing their potential for costly EPA violations. But, unfortunately, sometimes the last people to know about the fuel mixture change are the instrumentation engineer and the operator.
Here’s the catch: As the fuel mixture changes, so does the flame it produces. So, if you’re using a UV scanner that’s tuned specifically for a natural gas flame, it may not properly detect the flame from a natural gas/hydrogen mixture. When that happens, your combustion system shuts down unnecessarily, wasting time and money.
Last week, Lalit Mehta from Honeywell talked about this and a bunch of other flame detection applications in a free webinar to Lesman customers. It’s available to watch or download from our website. If the topic interests you, check it out.
Beside this application, he also talks about flare stack monitoring and greenhouse emissions, detecting flame on low NOx burners, flame discrimination issues with recovery boilers, sulfur recovery units, and cement, lime, and material processing kilns. Finally, he’ll introduce you to Honeywell’s Iris Systems line of combustion control and flame safety instruments.
There’s a lot more flame safety information available on my company’s website: http://www.lesman.com/unleashd/combustion.htm