TWO MARINE INSTAIvLATlONS OF PRODUCER GAS. 221 



brick lined cylinder filled with anthracite pea coal in various stages of 

 combustion. While operating, the hottest fire zone is from six to eighteen 

 inches above the grate. Above this is a red hot and black hot layer of coal 

 extending up to the take-off pipe. The top of the producer is effectively 

 insulated by a considerable layer of coal around and above the take-off 

 pipe. Thus it will appear that the producer itself is extremely simple. 



Contrary to general land practise there is no water vaporizer whose 

 function is to generate steam vapor which, mixed with the air and passed 

 through the fire, serves the double purpose of enriching the gas (the steam 

 forming water gas) and softening the clinker. A number of attempts have 

 been made to incorporate this device with marine producers but without 

 success, owing to the deposit of salt and the effect on the vaporizer of the 

 rolling and pitching of the vessel. It is in fact a mooted question whether 

 the presence of considerable water gas is not a detriment rather than an 

 assistance to a smooth-running engine. This being the case, it is only 

 necessary to find a substitute for steam for the softening of the clinker. 

 Exhaust gas introduced under the grate has this effect. The exhaust 

 line from the engine is accordingly tapped and a portion of the exhaust 

 by-tapped to the producer. To keep the ashes and the bottom of the 

 producer cool a small quantity of water is run into the ash-pit, say fifty 

 drops per minute on a seventy-five horse-power producer. Such steam as 

 is formed from this small amount of water of course is turned into water 

 gas and assists slightly in keeping down the clinkers. 



With proper care the grate should last two years or more as the best 

 operating conditions require a layer of ashes between the grate and the 

 hottest fire zone. The fire-brick lining is good for three to five years accord- 

 ing to usage and the skill of the operator. Relining is comparatively 

 inexpensive. 



The gas is taken off near the top of the producer through a two-way 

 water-cooled valve, one outlet to the scrubber, and the other to the purge 

 stack. The latter carries off the gases from the producer when the engine 

 is not drawing same through the scrubber. The purge pipe should be of 

 sufficient height to induce enough natural draft to keep the fire alive when 

 standing by for long periods — weeks if desired. The purge pipe is most 

 conveniently run into a dummy stack which may also contain the exhaust 

 mufflers. The scrubber, whose function is to cool and clean the gas, is 

 shown in the photograph of the Mary A. Sharp located on the top of the 

 engine-room house and aft the stack. It is of the static type, is cylin- 

 drical in shape, and fitted with baffles, each section being provided with 

 three water sprays. The material is copper and monel metal to withstand 

 the effect of salt water from the sprays and sulphuric acid from the gas. 



