SMOKE DENSITY METER IN BOILER

          It is very easy to achieve a smokeless fire without any special equipment for supervision. On the other hand, to achieve a smokeless fire and economic combustion will be a bit harder. The air supply has to be slightly in excess of the theoretical requirements. That is, the combustion air flow is reduced almost to the smoke limit. A plant that never shows traces of smoke at the chimney is not burning the fuel efficiently.

There are four instruments that will help you to achieve the optimal combustion:

1.     Smoke Density Monitor.   High smoke density indicates uneconomical combustion and it might also cause penalty from the environmental protecting authorities.

2.     O2 - Analyzer.   High O2 content indicates heating of unnecessary high quantity of combustion air.

3.     CO - Analyzer.  High CO content indicates unburned hydrocarbons. This is not only uneconomical, the CO is also harmful to mans health. Besides, mixed with air, CO might be an explosion risk.

4.     CO2 - Analyzer.  Low CO2 content indicates poor combustion, but it doesn’t tell if more or less air is required.

The most important instrument, the Smoke Density Monitor, happened to be the cheapest of them and you can’t do without it if you are trying to optimize the combustion of your burners.
The equipment is very simple. A light beam is sent across the flue duct, from a light emitter to a light receiver. An electronic unit monitors the opacity. It indicates 0% if there is no black smoke present and 100% if the light beam is totally absorbed by the smoke. An alarm activates if the smoke density exceeds the preset limit.

Some advises:

• The smoke density meters light emitter and light receiver are normally scavenged by sealing air to keep them free from soot. Therefore it would be vise to install these units higher up in the flue duct than the O2-analyzer to prevent the measured O2 value from being influenced by the smoke density meters sealing air flow.
• Check and clean the glasses of the smoke density meters light emitter and the light receiver regularly.
• The smoke density alarm should be overridden during the burners start and stop sequences, since the opacity normally increases before the flame has stabilized.
• Never adjust the O2 content all the way down to zero unless you have facilities to check the CO content.
• It might be worthwhile to spend a few minutes studying the diagram below.
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The FUEL OIL Calculation Program,  can easily calculate the theoretic requirement of air per kilogram of fuel.