Book - School of Science and Technology

278 Boilers and firing equipment. alarm devices (high and low water, etc.). control devices.Some packaged boilers are provided with an electrically driven boiler feed pumpsupplied from a frame-mounted condensate cylinder. This latter must not be confusedwith the large-scale hot well required in the case of most systems to collect the intermittentflow of returning condensate (see p. 165).Boiler firing ± solid fuelAt the present time, there is little interest in the use of solid fuel for firing either large orsmall boiler plants but, as has happened in the past, economic or other pressures may leadto a resurgence of activity at some time in the future. Hand firing, with its human failingsand other vagaries, is unlikely to return but a variety of mechanised equipment, admittedlynot yet wholly automatic, is widely available. Properly applied and maintained, suchequipment is able to produce an adequately high combustion efficiency. The section onsolid fuel firing in this and other chapters has been retained in this edition mainly forreference purposes.Magazine boilersThe boiler illustrated in Figure 10.15 is a domestic pattern unit designed to burn anthracitegrains but equipment of very similar type is available for commercial applications upto ratings of about 600 kW. The principle common to all is top charging of the fuel into ahopper whence it descends by gravity to the burning zone. Ash and clinker are removedby hand from the base.Hopper doorF.D. fanWaterwaysGrateFigure 10.15 Magazine boiler (Trianco)