Combustion apparatus

Abstract

An object of the present invention is to provide a combustion apparatus capable of certainly detecting a shortage of an amount of air relative to that of fuel gas.A combustion apparatus 1 is adapted to perform a primary combustion of air-fuel mixture in an oxygen-deficient condition composed of mixture of primary air and fuel gas and further perform a secondary combustion upon supply of secondary air 67, including a first ion current measuring element 65 positioned at a site where a flame of the primary combustion is to take place and a second ion current measuring element 66 adjacent to a secondary air supply opening 20, 21, 63, or 64 for supplying the secondary air 67, so as to control at least one selected from a group consisting of (a) a ratio of an amount of the primary air to that of the secondary air, (b) a total amount of the primary and the secondary air, and (c) an amount of the fuel gas based on measured values by the first and the second ion current measuring elements 65 and 66.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a combustion apparatus, and more particularly to a combustion apparatus recommended to be used in a water heater or a bath heater.[0003]2. Description of the Related Art[0004]A combustion apparatus is a main component in a water heater or a bath heater and in widespread use at home as well as at factories.[0005]Recently, environmental destruction resulting from acid rain has become a grave social issue, and thus, there is a pressing need to reduce a total amount of emission of NOx (nitrogen oxides).[0006]There is a combustion apparatus employing a combustion system called the “thick and thin fuel combustion” method adapted to be used in a small device such as a water heater and to reduce NOx emissions.[0007]The “thick and thin fuel combustion” method is designed to produce a main flame from a lean mixed gas composed of fuel gas premixed with air of about 1.6 times the amount of the theor...

AI Technical Summary

Benefits of technology

The present invention provides a combustion apparatus that can detect a shortage of air relative to fuel gas using ion current measuring elements. The apparatus includes a first ion current measuring element positioned at a site where a flame of the primary combustion is to take place and a second ion current measuring element adjacent to a secondary air supply opening for supplying the secondary air. The first measuring element does not reach an extremely high temperature in totality and is cooled by the secondary air, while the second measuring element is cooled by the primary air. This allows for the detection of an amount of supplied air being reduced and appropriate normalization of combustion condition. The apparatus can also adjust the supply or ratio of distribution of the primary and secondary air to control combustion.

Problems solved by technology

Recently, environmental destruction resulting from acid rain has become a grave social issue, and thus, there is a pressing need to reduce a total amount of emission of NOx (nitrogen oxides).

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