Soot Blower Technologies / Clinker Prevention

[goldnwhite]

I am starting to research available soot blowing technologies for our two coal boilers. I found a good amount of information in the following closed thread that I will be building my questions from: thread605-133988.

Our boilers currently have nine manually operated wall blowers in the economizer and tube bundle areas. I would like to improve this process (automation? improved technology?) to increase boiler efficiencies. In my research on google and the previously mentioned thread, there are several options for soot blowing. My questions are:
Have there been any advancements in the practical applications of the non-stick coatings on tubes?
Has anyone had experience operating the detonation and sonic type 'blowers'? Can they be used affectively in the fire box?
Would the prevention of clinkers in the fire box fall under a cleaning issue or a combustion issue? If we could reduce clinker formation, it would garner significant payback, but I'm not aware of a reliable way to clean this area without turning the boiler down or subjecting the equipment to extreme temperatures.

I appreciate any guidance. This is my first time back on the site for about a year. Glad to see it's still a great source of practical information. I used to deal exclusively with gas-fired firetubes and am having my first experiences with coal-fired equipment. There's a lot to learn.

 

[rmw]

Before any of us can offer any tips on specific soot blowing methodologies (sonic, detonation, coatings, etc) we must know more and much more about your combustion process. What type of device (boiler, process heater), what fuel(s), combustion type (PC, stoker, liquid e.g. black liquor or fuel oil); lots more information.

If you want us to help you, help us.

rmw

 

[goldnwhite]

Thanks for the reply.

These are 1992 Vogt 160,000 lbm steam/hr (@ 300psi,550 deg F) coal-fired boilers with economizer and superheat. The coal feed consists of 4 reciprocating spreader stokers (Detroit Stoker RotoGrate). We burn coal from Eastern Ky/W. Va with a coal spec calling for max 9% ash. The existing soot blowers are from Diamond Power.

Sorry to not give you all this information up front. I was trying to avoid being long-winded, but didn't mean to sacrifice crucial information in the process. Let me know if I'm missing any other useful information.

 

[rmw]

Do you have combustion air preheat?

Two drum, 3 drum?

How friable is your ash?

Give a basic description of where your current soot blowers are located.

What pressure are your current soot blowers operated at (main steam, reduced pressure)?

What specific problems are you having that is causing the analysis (other than the previously mentioned clinkers.)

Where are the clinkers in the firebox (furnace) - grate, walls, screen tubes?

Is your furnace water cooled or refractory wall?

These will do for a starter.

rmw

 

[JEB66]

Slag formation is not an easy one to put black and with answers to. It is a combination of combustion, coal properties, operation and maintenance.

central app coals are usually high fusion temp coals, but there are a few seems where the H=1/2 reducing temp are low, in the 2100 F range. That is an important factor in dealing with slag formation.

Another parameter is ash loading lb/mmbtu. Typically the central app coals are about 12,100 BTU/lb and with 9% ash, that would be about 7 lb/mmbtu. Not to bad, but if for some reason you have less BTU's your ash loading will increase and your ability to maintain cleanliness will diminish.

If your furnace is dirty, or your combustion is poor, FEGT will increase. As the FEGT approaches the ash fusion temps, then the ash will stick. It is the semi molten ash that is the problem. The fluid type ash is not easily removed by mechanical methods. You will need to lower the furnace temp to solidify the ash for removal. That is why load cuts work well. Raising Excess air can help too.

I would doubt that detonation type devices will work on slag that is in the molten state. The force will simply deform the formation.

Water Cannons are gaining ground but have their perils. Thermal cycles as you mentioned cause cracking and failures. There are "Smart" systems that use heat flux sensons, but there is a pay off as to how many and the area they cover. I have seen cracks on the so called smart systems too.

For operation, I have seen with the current high market prices, a tendency to overfire the boiler. The desire to get all the load you can, will raise FEGT.

 

[tommy75]

Ever think of switching the G9B's to an IK-Retractable type?