Abstract
Experience gained from nearly three years’ operation of the large single-ended stokers at Delray has led to developments and improvements in design, the application of which has made them comparable with other types of coal-burning equipment. Improvements have been made with two things in mind—namely, an increase in efficiency of combustion and a reduction of maintenance by decreasing burned stoker parts. All improvements possible, particularly those to improve combustion, have not as yet been completed; however, changes that have been incorporated have materially improved performance. Automatic control of preheated air to the various parts of the fuel bed has been sufficiently developed to establish it as a desirable and valuable aid to combustion, particularly with long stokers burning high-volatile coal. One of the stokers has been operated successfully for a short period with preheated-air temperatures as high as 500 F. Development of a similar air-control system, manually operated, under two boilers in the Beacon Street Heating Plant, handling cold air, has resulted in an increased steaming capacity of 31 per cent and an increase in calculated boiler efficiency of from 1/2 to 2 per cent. The paper is a description of the Delray installation, but reference is made to the large double-ended stokers, supplied with cold air, and the manually operated metered air control in the Beacon Street Heating Plant.
