Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER III FLUE GAS ANALYSIS Let us assume that we have succeeded in discovering the best coal, all things considered, for our plant. By making proximate analyses and estimating heat values we have found one grade of coal which has minimum moisture and ash; consequently, it gives maximum heat-generating material per dollar invested. Upon actual trial in the boiler room it is found to work satisfactorily with the existing equipment. It does not clinker badly and, hence, the firemen can handle it easily and efficiently and maintain the stem pressure uniform without undue trouble. Our next problem is: How best to burn this coal so as to get most of the heat it contains into the boiler and generate the greatest quantity of steam possible per pound of coal fired. And right here is where our knowledge of the underlying principle of combustion comes into use. Excess Air Necessary In preceding chapters it was shown that each pound of coal of a certain composition requires a certain fixed weight of air for complete combustion and the method of figuring this weight war given. But, this theoretically required amount of air will not suffice in the boiler plant because if only the required amount is supplied, the distribution must be perfect so that each particle of oxygen in the air may come in contact with a particle of carbon or hydrogen. If this does not take place, some of the oxygen will escape without combining with its allotted share of the combustible matter, with the result that either of the two following things may happen: Some of the hydrogen may escape unburned, or some of the carbon may be only partly burned and form CO instead of CO2. In the boiler plant this perfect distribution of the oxygen is impossible. Consequently, an excess quantity of air must be suppl...