Raising Boiler Efficiency

There are several limiting factors in determining the maximum efficiency available in boiler operation. Two factors include: 1) Burner design, and 2) Flue gas temperature. There are other considerations in addition to these two, such as furnace design for maximum radiant and conduction heat exchange in the furnace section; convection heat exchange in the tube bundle, steam chest and dome (in the case of steam), etc. Having said that, present day boilers can be fine tuned to produce in excess 0f the standard 80%. Gas fired condensing boilers can produce efficiences in excess of 90%, but at what cost in maintenance, and constant attention to output and control settings.

Until someone designs a better burner requiring no excess air - ie, using only primary air to obtain complete 100% combustion; and a furnace that absorbs all the radiant and conduction heat and etc., there will be inefficiences in the combustion process.

Flue gas temperatures are maintained above condensation temperatures to prevent acid forming in the flues and vents. If materials which are not affected by the acid are used, then the flue gas temperatures can be reduced, thus improving the efficiecy of the boiler, this is being done in the condensing boilers. In addition, a forced draft fan is used to produce sufficient draft to exhaust the products of combustion.

Certainly variation in the heating value of the fuels and their chemical compsition affects the combustion. Here, the firing rate, atomizing pressure,and fuel-air ratio would need be controlled to maintain the maximum efficiency.

Can all this be accomplished?...Yes, it can.............and, at what cost?...Who knows?

Therein, lies the problem........In my opinion, the 90% minimum efficiency standard ia a little unrealistic at the point........

g scott

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When I ponders, I sits and thinks, sometimes, I just sits.

Decades ago, a man named Eric Cottell (now deceased) had a company, Tymponic Corp. (now defunct), which offered for lease an "ultrasonic nebulizer". It was shown to result in oil savings of 25% for oil fired boilers, and he had a money-back guarantee if you didn't save at least 15%. Several peer-reviewed tests proved it worked. For example, a college with identical boilers ran one with it, one without, and measured the steam output for a whole heating season. One ship engineer claimed he saved 7 tons of oil a day in port and was able to burn a lower grade of bunker oil. It also worked on a Mercedes automobile on a dynamometer. The world did not beat a path to Tymponic, and Cottell retired to Barbados.

The principle involved was interesting. The nebulizer made small droplets of oil with a smaller droplet of water contained inside. As the oil droplet heated up and burned, the contained superheated water droplet exploded into steam, dispersing the oil. The effects on the flame were obvious (it was brighter) and the stack temperatures went down. Hypothetically, the increased efficiency came about because the flame was more emissive in the infra-red, so more energy went into making steam and less went up the flue. I don't know why the car developed more power, but... Perhaps the steam in the flame went to pushing the pistons, instead of warming the radiator.

In South Africa, coal burning steam locomotives were used during the oil embargo. Their efficiency was improved by feeding steam from the boiler to the firebox, making producer gas (H2 and CO) which burned cleaner than coal alone.

We're not talking of putting cow magnets on the fuel line or refueling during the proper astrological sign; these were honest improvements in fuel efficiency. The question is why such good ideas so often fail to be adopted.

Your Blog "Raising Boiler Efficiency" is very interesting.

Please be noted that Japanese company has developed

"Fuel-Water Emulsion" to reduce oil fuel consumption.

The same water developed by FUKAI SOSEISUI is also used by Canadian Government to study if it is usable for cleaning cloths purpose, which Memorundum copy is available at NAKAO. This project is under way to evaluation how much water saving and how much better for envrionment since this water can eliminate detergent. I believe the water has surfectant capability and to certain degree ionized. Please visit You Tube: http://youtube.com/watch?v=Uk5lmPdOTzE

where you can see 50% water 50% kerosene/light oil are burning from conventional boiler burner.

Sorry, there is no English super to explain what are shown in the video, which I am preparing in English now.

Please help us to whom NAKAO should show this innovative water/fuel emulsion.

We have confirmed 35-40% of energy cost is saved, and more than 50% of harmful waste gas emmission is reduced.

Re; Raising Boiler Efficiency

Your blog entry of 19th March.

Would like more details of your fuel/water emulsion system. Kindly contact via

indrawim@yahoo.com

I am the son of Eric C. Cottell who was better known as Jock.

This technology is once again available through www.cotefco.com for boilers in the US and Canada, for other applications www.nonoxltd.com both still guarantee satisfaction.

I am not a registered member of this blog, but I'd like to provide an update. The Cottell process (water-in-oil emulsion) is being ressurected in a simpler (Hydrasonic, not ultrasonic) and more cost effective form. I happen to be the Sr VP of Engineering for COTEFCO Energy Group of which Jock Cottell's son is our partner. We have installed this new technology on a 200 HP boiler, a 500 HP Cat ship engine and another Mercedes. It works great on all of them. It reduces NOx and Consumption among other things. Google Cotefco if you are curious.

Remember, I am a biased insider but I deal in fact, not fiction. Cheers, Charlie

The law also calls for an automatic adjustment means for matching boiler output for building load. As you are well aware the outer environment is always changing for a building or home. What is the best means for adjusting the boiler for the load?

Unfortunately, there is no one best means for controlling a boiler. For example, the boiler in a small residential system could very well be controlled from a room thermostat, simply by turning the boiler on and off. A more sophisticated control system couldn't be justified because of capital costs and maintenance. Whereas, a large industrial boiler maintaining a constant steam pressure or hot water temperature requires a complex control system with a high degree of accuracy.

Progress is being slowly made in boiler and burner efficiency as designs are being refined. Burners today hardly look like the primative conversion oil and gas burners of the '40's. 60 years or so of improvement has resulted in an increase in efficiencies of 15 - 20 % in the combustion process.

My inside opinion is Exquisite Heat. www.Exqheat.com With this techology the boiler output is adjusted from the thermostat activity over time. See the website for details.

There are indoor reset controls, Outdoor reset controls, and indoor/outdoor reset controls.

These are produced by Honeywell, Tekmar, Taco and Exquisite Heat. You can find all in google under boiler reset controls.

In the 80's we where allready using boilers with efficiency figures of 87.% for gas and 89.5% for oil. By using economisers we where able to increase the eficiency up to 92+ %.

Hans

FBC Boiler : Fluidised Bed Combustion Boiler - Can use Waste as fuel. FBC Boiler You can get more information at fbcboiler . com