THE ROBOT STOKER

Taranaki Daily News, 17 July 1930, Page 7

THE ROBOT STOKER

COAL TURNED TO ENERGY.

ONE MAN DOES WORK OF FIFTEEN

It must i>e incomprehensible to many people to be told by engineering experts that only one grade of coal produced in New Zealand mines—Waikato slack—can be used to drive the turbines in the electricity-generating station at King’s Wharf, Auckland. Why should not ordinary steam coal suit the purpose when it is used in railway engines, ocean-going liners, and even in other steam-run power stations? The answer is to be found, says the New Zealand Herald, in the mechanical stoker, a very particular,-finnicky old Robot, whose digestion is delicately attuned to one eoal diet and no othei. He is strongly constructed of cast-iron but- his digestion is any thing but that. His invention makes it possible for one man to do the work of 15. He stokes the fires automatically and continuously, never tiring, never perspiring, from one year’s end to the other, without a single spell or a day off, but he is fai more particular about what he eats than the human beings whose labour he thus dispenses with. He must be petted and fussed over like a spoilt child, or he starts trouble. The Robot stoker would never be observed by the stranger who had not been warned of his presence,. which explains why a lady who was conducted through the furnace room the other day addressed two men whom she saw mixing Westport coal with the slack as “stokers.” They were not, of-course; the whole operation of stoking is performed by machines. Machinefy._n.iliV! tha day in this huge incubation house "of ej.-orgy.. Like a black waterfall, fine slack coal-drops from the hopper in a continuous stream on to an endless chain of cast-iron links, which travels at a snail’s pace across the floor of the furnace. The shower of coal falls unceasingly, so that- as the chain-feeder crawls along the floor it is covered with a perfectly even layer of coal which, when ignited, burns quickly and fiercely until, by the time the chain reaches the opposite end ot the combustion chamber, the coal is completely burned out and nothing but a fine ash remains. INGENUITY OF MACHINE. This, however, is only half the ingenuity of the machine. As some Waikato alack burns quicker than others it is necessary to make the cham-feeder move at a quicker pace when necessary. This is accomplished by . a Jour-speed gear-box, like any motorist is familiar with, which regulates the speed of the feeder by a simple pull at a lever. Also, it is sometimes desirable to thicken or thin out the layer of coal travelling atom* on the feeder. This happy consummation is effected by compelling the coal to pass under a brick door or guillotine, which, if it is lowered, neatly cuts off an inch or so of its height. At 8 o'clock on Saturday night the layer of coal was 4in. high, but the guillotine is capable of letting lin. or even Bin. pass through, , . An engineer who conducted the visitor over°the works explained the . peculiarities of the Robot’s diet. “Waikato slack is the only food it will take,” he

said, “because if you give it pure Newcastle or Westport coal, which have a high calorific value, the heat becomes too great and you burn out the brick doors and buckle the cast-iron links in the feeder-chain, and then you have to stop the whole thing until it is repaired. ’ The practitioner who prescribed for the Robot’s diet, however, stipulated the addition of small quantities of Westport or Newcastle steam coal. It was discovered that if this were not done, the burning slack toft a hard coagulated ash, which encrusted the walls of the combustion-chamber and clung to the links of the feeder-chain, but by inixin» the slack with a small proportion of° higher-grade coal, which burns at a fierce°wliite heat, the slack to completely burned, ash and all, only a very fine and negligible dust remaining. A peep through the series of inspection doors of the furnace shows what is aoincr on. As the mixture, enters on the chain-feeder it passes under a low brick arch, brought to white, heat, that instantaneously ignites the layer of coal. A. lump of wood as thick, as a man s arm thrown into the furnace, glows yellow. and white and entirely disappears in live seconds.

BEAUTIFUL WHITE SPRAY.

By the time the layer of coal reaches the end of the chamber hardly a vestige of it remains, just a soft grey dust and an attenuated shower of sparks carried to and fro by hot air current m a beautiful white spray. Not a tiace is to be found of that charcoal encrustation which chokes up the chamber when other coals or the wrong mixture of coals are used. _ Only two men are required to tend to the 15 boilers in that great noisy, throbbim* room. One man watches nine small low-pressure boilers and furnaces and two large high-pressure boilers and furnaces. They are not the grimy, black-faced denizens of the maritime coal furnaces, and the coal shovel and long rake are conspicuous by their absence. No raking is required in these furnaces; the mechanical stoker does ail that is needed. But that does not mean to say there is nothing for the men to do. Their job to to see that the mechanical stokers are being fed on the rio-ht kind of food, that they do not choke with too rich a mixture or get starved by too poor a one. “They have to-keep-their wits about them, those chaps,” observed the -engm-._ eer, stroking his chin. “They know iust the quantity of Westport and Newcastle to put in that mixture and nobody tells them a thing. When we are workim* on full load the proportion of hi"h-grade coal has to be increased to produce a bigger head of steam. On a wet ntoht between 4.30 and 6 o clock we are working at full pressure, pushing the old plant along ms we never used to in the old days, and it means working the furnaces for all they are worth. But it is not even necessary to tell those fellows to pep up the mixture; they do it without being told. How do they know? Because they find their steam is being taken off the boilers. That is the signal to bank up the fires, to add more Westport and open the regulating furnace doors that increase the supply of coal on the chain-feeders. You can’t afford to wink an eye on wet nights now.” And the two feeder-men walked about leisurely, throwing a little Westport into one hopper and peering thoughtfully through the inspection doors into the furnaces, thinking, pondering and calculating. They might have looked a little more picturesque if they stripped to the waist and stood in the fierce glare of the furnace doors with perspiration pourim* down over their shoulders, but this is° the day of brains and machines. The mind of man is all-conquering.