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[VIDEO] Powerful Precipitators for Wood-Fired Applications
March 05, 2019
John returns to talk about powerful precipitators for wood-fired applications. He discusses the most significant improvements he has seen in his career and one diagnostic check he recommends on an operating ESP.
0:00 - Introduction
0:15 - What is the role of an ESP in a wood-fired application?
1:28 - What is the most significant improvement for precipitators you’ve seen in your career?
2:44 - What is one diagnostic check that you recommend on an operating ESP?
Jessica Duncan: Welcome back to another episode of B&W’s Ask the Expert. Returning with us is John Knapik to talk about electrostatic precipitators on wood-fired boilers. Welcome back, John.
John Knapik: It’s good to be back. Thank you.
JD: What is the role of an ESP in a wood-fired application?
JK: First, a precipitator is a dust collector. So, it is collecting the ash coming off the boiler in a biomass boiler or a wood-fired boiler. The application is very easy for a precipitator. It’s easy because the dust or the ash is highly conductive, and a precipitator loves highly conductive dust. When the dust is highly conductive, then the power levels at which the precipitator operates can go very high. The higher the power levels, the higher the collection efficiency. So, it’s an easy application for precipitators. It’s an application where you have to watch out because it has the highest incidents of fires in a precipitator. So, one thing they do is they put a mechanical collector ahead of a precipitator. Because there is the mechanical collector, because it’s highly conductive dust, it has very few number of fields (two or three fields verses a coal-fired boiler which might have five or six). But bottom line, it’s a simple application for a precipitator.
JD: What is the most significant improvement for precipitators you’ve seen in your career?
JK: Power supplies. Precipitators have been around since the early 1900s in commercial applications and have used transformer rectifier sets. A precipitator is a DC device. It uses high voltage, but it doesn’t use high voltage AC, it uses high voltage DC. But for years, that high voltage DC was provided by a device where the high voltage had a lot of ripple in it. So, if you had an oscilloscope, and looked at the waveform, you’d see it going up and down and up and down. And that waveform is less efficient than if you could get pure DC that stays at the same voltage level, as time proceeds.
So, the biggest innovation has been low ripple power supplies where they’ve taken the ripple out of the waveform which has increase the power into the precipitator by 25-30% or more. More power in means less dust out.
The biggest innovation has been low ripple power supplies where they’ve taken the ripple out of the waveform which increases the power into the precipitator by 25-30% or more. More power in means less dust out.
JD: What is one diagnostic check that you recommend on an operating ESP?
JK: Precipitators are a power dominated device, so you need to record and monitor the total power at which the precipitator operates.
TIP: Precipitators are a power dominated device, so you need to record and monitor the total power at which the precipitator operates.
JK: So, if your precipitator has four or five voltage controls, or four or five power supplies, you need to get each one of those power supplies to report to the precipitator computer. The computer then sums up all four or five of those and gives you one value which is the total power in which the precipitator operates. You don’t need to be an expert, you know that more power in means less dust out. So, you just watch that over time and you’ll be very good at evaluating if one has a problem or if you are running at optimal performance.
JD: Thank you for joining us again, John.
JK: It was my pleasure, I hope to do it again.
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