All About Steamers - The Boilers And Engines

ALL ABOUT STEAMERS THE BOILERS and THE ENGINES The basic parts of a steam engine are thus - the fuel system, the water-feed system, the boiler and condenser, the cylinders or turbine and the coupled shafts - to the paddle-wheels or propellor(s). Stoking The Fires While cold boilers must be warmed through very slowly to avoid damage to the plates and joints, that taking anything from 24 to 48 hours, an already warm boiler, its fire banked, the ashpan and funnel dampers closed overnight, can quickly raise steam to working pressure in a couple of hours or so if necessary. In the case of these small steamers and the like of the old steam fishing drifters, the general practice was to rake one half of the grate clear of any clinker and, halving spread the remaining glowing coals evenly out again, cover these with half-a-dozen shovels of fresh coal. Five minutes later and the fresh coals now lit, these would all be raked down evenly and, after another ten or so minutes, with the fire now burning clearly, the process repeated on the other half of the fire-grate, the idea being that the smoke and gases from the freshly shovelled coal would be burnt by the fierce and clear fire on the other half of the grate and the amount of black smoke coming from the funnel would be minimised. By this procedure, twelve shovels would be added to the fire every 30 minutes or so and, in the course of an average summer day’s ‘dawn-to-dusk’ run, the boiler fire would consume about ¾ ton of coal, boiler’s ash-pan being emptied, thanks to the slow build up of steam coal ash, perhaps every 1

other day and all the while, in between stokings, the engineer too would be constantly, lubricating the constantly turning machinery of the main engine, running about 138 r.p.m. on a puffer at about 6 knots and too lubricating all the auxiliary equipment ! LIGHTING FIRES. Fires should not be started until the boiler has been pumped full. If too much water has been pumped in, blow off by the bottom valve, after the water is partly heated. This will withdraw cold water from the bottom and start the circulation. Start the fires in ample time and do not force them with cold water in the boiler. The grate should be kept well covered with a thin fire. Do not feed with large lumps or too much at a time, or keep the fire door open too long. Keep the grate free from clinker, so that the draft may not be impaired. The fires are started by splitting a quantity of wood and distributing it with shavings and oily cotton waste over the grate. When this has reached a blaze and the ashes glow, introduce a little fine coal without smothering the wood fire. Cotton waste should not be kept stored up for this purpose, however, as it is liable to spontaneous combustion. A slow rate of cumbustion with moderate draft produces a better evaporative result than when the fires are urged. The test of a good fire is in the glow of the ashpit. When the ashes in the pit appear dull, the fire needs cleaning, but it should not be broken up. The bars should be evenly covered and no space left bare, as a cold current of air would draw up and sweep over the fire, cooling it down. In boilers with two furnaces attend one at a time. Bituminous coal is apt to form a crust on the surface, and before feeding should be broken. Avoid heaping the fuel at the front, and do not clean a fire down too low, as it will take some time to come up again. SAFETY VALVE. Raise the safety valve to permit hot air to escape. When a few pounds pressure are shown on the gauge, open stop and throttle valve and allow steam to pass through the engine to warm up its parts. Sudden admission of high steam to the cold engine would cause such expansion to packing of piston and other light parts that free working will be endangered. When steam is up, the fires should be so managed that the safety valve will not blow off, although the point of blow-off should first be compared with the steam gauge. If the boiler steams too fast, close the damper and shut off draft, but do not throw open the furnace door if it can be avoided. The Basic Arrangement of the Fuel Burning System - As the temperature of heavy ‘boiler’ oil must be raised before it will ignite, other means are used to start raising steam from cold. Though in the old days a small coal fire would have been lit to start the boiler coke, instead of coal, being used if the boiler was still warm from the previous day, nowadays, a gravity fed supply of ‘light’ diesel oil will be led to start the boiler fire(s) - lit of course by applying an ordinary household match to an oil-soaked rag. As steam temperatures and pressures rose, steam was run into the heating coils in the oil fuel bunker storage tanks to allow the cold fuel oil to be pumped, through a suction filter to remove grit and heavy impurities, to a fuel heater, externally heated by steam, which raised the temperature of the fuel oil to some 20° or 30° lower than its ‘flash point’ i.e. its ignition point (about 190° F) and the fuel oil, after possibly being passed through the fuel heater several times to raise its temperature sufficiently, then being pumped, at somewhere between 100-150 p.s.i. (pounds per square inch), to the boiler’s oil burners, the number of burners varied according to the size and type of boiler and the burners, about 18 inches long and 1½ inches in diameter, are quickly changed, from diesel to boiler oil, using a vice-grip and spanner. The steam heating the bunker heating coils and the fuel heater passed through a windowed inspection tank which allowed a visual inspection to ensure that no fuel oil had 2

entered the water system (and consequently the steam itself) that might be fed to the main boiler, the now rapidly condensing ‘heating steam’ then returned to the main water feed system. The Water Feed System - circulates and tops up the water supplies to the main boiler(s) and water feed heaters, these operating in the same fashion as the oil fuel heater (above) and raising the temperature of the water before it reaches the boiler(s) ! Previously heated water reduces internal stresses on the boiler(s), gives easier steaming and reduces fuel consumption and thus water might enter the water feed heaters at between 140° and 150° F and leave, on its road to the boiler at 200° F. The Boiler - The greater the contact that the water has with the heat from a fire, the faster the water will evaporate to make steam and, for that very reason, many tubes run through, often several times through, boilers and chambers before the steam eventually reaches the engine(s). The Condenser - takes all the surplus and previously used steam from the main and auxiliary engines, the steam then being passed many times over the condenser tubes, these salt water filled and supplied constantly with sea water by means of a circulating pump. The condensed steam, now again water and any air and vapour removed from the condenser by an air pump which discharges to the outside atmosphere, is in turn filtered and fed to the hotwell - an intermediary point in the water feed system which, as previously described, again begins to heat the water in the water feed heaters. Of the various water temperatures, given the boiler at say 212° F, then the return to the condenser at about 126° F, the air pump then further reducing the water temperature to between perhaps 90° and 110° F and the hotwell then raising the water temperature to perhaps some 150° F before returning the water to the water feed heaters to be heated up again for the boiler(s) etc. again at around 200° F. While steam acts against all sides of cylinders equally, both temperature and pressure drop. A drop in temperature means, essentially, that ‘work’ is lost. By dividing the temperature drop between a number of cylinders, condensation losses are proportionately decreased, cylinder cooling is minimised and the advantages of pressures are maximised. Understanding that 1 p.s.i. (pound per square inch) equals about 2” (inches) of vacuum and that barometric pressure at sea level is about 30” (inches) may make it easier to follow the workings of the engine as the engine gauge readings indicate pressures relative to the prevailing ‘atmospheric’ pressures ! If there was no vacuum e.g. if the barometric pressure was 30” (inches) and the vacuum gauge was reading 15 p.s.i., it being remembered that 1 p.s.i. equals about 2” (inches) of vacuum, the engine would of course slow down as the engine is essentially an ‘atmospheric engine’ and consequently the vacuum gauge should always read lower than the ‘outside’ barometric pressure if the engine is expected to work ! And so to The Engine(s) - The likely sequence of events in the case of a triple expansion engine, given that the boiler is supplying steam to the throttle at say 180 p.s.i. (pound per square inch), would be that the high pressure cylinder (usually the middle cylinder of the engine) would receive at a slightly reduced pressure, perhaps about 170 p.s.i., the exhausted steam from the high pressure cylinder being fed to the medium pressure cylinder, at perhaps between 58 and 60 p.s.i. and, in turn, this exhausted steam being fed to the low pressure cylinder at about 1 or 2 p.s.i. and the steam then returned to the condenser (and, in turn, as hot water) to the water feed system etc. etc.. 3

Pressure relief valves and drains are fitted on the ends of the cylinders, the drains being opened and shut from the engine control platform. While the high pressure steam from the drain on the high pressure cylinder would, eventually, damage the tubes of the condenser, the high pressure steam is led away to the bilges, the drains from the medium and low pressure cylinders return direct to the condenser. Though the drains might be used when slowly warming through the engine before sailing, the drains would only be opened in the most exceptional circumstances when the engine was running. The Engine Controls - consist simply of 6 levers set in a frame, the ‘valve settings’ for going ‘Ahead’ or ‘Astern’ are controlled by the ‘Direction Lever’, centred at ‘Stop’ and being pushed forward for ‘Ahead’ or pulled back for ‘Astern’, set to the engineer’s left hand. Though it seems needless to state that the ‘Regulating Throttle’ (below) should be shut before the position of the ‘Direction Lever’ is changed, one of the ‘engineers’ on Loch Lomond’s “Maid of The Loch” regularly ignored ‘the obvious’ and his handling of her engine (and indeed her boiler) caused great expense to the company. In 1816, when James Watt made his final trip home to Scotland, he had taken a trip to Rothesay on the “Dumbarton Castle” and, in a conversation with the ship’s engineer and was told that on the previous evening the ship had run aground on the river-bank while going up-river home. Fortunately, as the tide flooded, the pressure of the current on the paddlefloats had caused the engine to reverse and the ship came off the river-bank. Watt instantly grasped what had happened and, unable to make the ship’s engineer understand the theory of what had happened, Watt threw off his coat and putting his hand to the engine’s controls showed the engineer how to make the ship go astern and thus, the first intentional reversing of a marine engine occurred at Rothesay Pier ! Watt’s discovery was momentous and from then on ships were able to come alongside piers with ‘precision and promptitude’ ! Next and to the right of the ‘Direction Lever’ , lie the three ‘Drain Levers’, from left-toright, for ‘Low’ - ‘High’ and ‘Medium’ pressure cylinders, the drains being ‘shut’ with the lever(s) pushed forward and ‘open’ with the lever(s) pulled back. The engine’s ‘Regulating Throttle’ is the outer lever, set to the engineer’s right hand, the lever being ‘notched’ forwards to admit steam from the boiler to the engine, the narrowerspaced ‘notches’ being for ‘manoeuvring’ alongside piers at low speeds and the wider-spaced ‘notches’ coming into use as the speed of the engine is increased once clear of the piers. In the old, particularly single-cylinder single-cranked, paddle steamers, if the crank was ‘centred’, it had to be manually ‘jacked over’ using a large crow-bar to get the engine started, a great handicap when manoeuvring at piers ! On ‘modern’ paddle steamers, e.g. in the case of a three crank triple expansion ship such as the “Waverley”, a ‘Starting Steam Lever’ is fitted immediately to the left of the ‘Regulating Throttle’. This is operated briefly if the (centre) high pressure cylinder crank is ‘centred’ (lying) above or below the main crankshaft connecting the engine to the paddle wheels. By briefly operating the ‘Starting Steam Lever’, steam is admitted to the medium and low 4

pressure cylinders and, as the three engine cylinder cranks are fitted to oppose each other at 120° angles, the high pressure cylinder crank is therefore ‘jacked over’ and the engine started. Where there is constant manoeuvring at piers, the engine’s expansion gear keeps the engine’s valve stroke travel equal to the throw of the eccentrics on the main shaft and, e.g. on ‘slow cruises’, the expansion gear can be ‘linked in’ so that total engine power is reduced, engine revolutions decreased and fuel consumption lowered. The engine’s high pressure expansion gear is frequently ‘linked in’ on coastal passages. Conversely, by ‘linking out’ the expansion gear, the engine’s valve stroke travel becomes greater and total power and engine revolutions are increased, as are speed and fuel consumption ! The Main Steam and Engine Gauges are set in front of the engineer and unfortunately, as in the case of the “Waverley”, out of the direct view of passengers. The typical array of gauges (and their typical Working Readings), from left-to-right, are for ‘Auxiliary Steam’, ranging from 0 - 350 p.s.i. (180 p.s.i.); ‘Auxiliary Exhaust’, ranging from 0 - 50 p.s.i. (10 p.s.i.); ‘Main Steam’, ranging from 0 - 350 p.s.i. (180 p.s.i.); ‘Low Pressure Cylinder’, ranging from 0 - 50 p.s.i. (1 p.s.i.); ‘High Pressure Cylinder’, ranging from 0 - 350 p.s.i. (170 p.s.i.); ‘Medium Pressure Cylinder’, ranging from 0 - 150 p.s.i. (60 p.s.i.) and ‘Vacuum’, there being gauges for both main and auxiliary steam and both gauges these ranging from 0 - 30 p.s.i. and both, for the reasons set out before, likely to read about 25 p.s.i.. Finally and vitally to The Engine Room Telegraph(s) - their ‘face-plate’ orders being marked sequentially “Full Astern” - “Half Astern” - “Slow Astern” - “Dead Slow Astern” “Finished With Engines” - “STOP” - “Stand By” - “Dead Slow Ahead” - “Slow Ahead” - “Half Ahead” and “Full Ahead”. The first ‘telegraphs’ were fitted to the 1864-built “Iona (III)” in 1873, that year she too becoming the first Clyde steamer to be fitted with steam steering gear. Denny’s first iron-built steamer, the 1845-built “Loch Lomond”, had been fitted with a ‘knocking contrivance’, a rack-pin system fitted below the bridge to the engine room hatch, which put an end to the practice of shouting orders to the engineers. GETTING UNDERWAY. See that all the manholes and handhole plates are fully screwed up over the packing grummets and open the blow-off cocks, allowing the water to fun up as high as it will, unless it is proposed to fill up with fresh water from a hose on the dock. Meanwhile get the fires ready and start when the boiler has been pumped up by hand to the level required. Blow-offs are to be closed after running up the water, and the feed pump connected for working by steam after boiler is full, the suction opened and the check valve to suit as well as intermediate valves in the feed pipe. Injection and outboard delivery must be opened ready for the condenser to operate. Open the stop valve slowly when steam has been raised. Then open the throttle valve partly and the blow-through valves and drain cocks on the engine. Allow the steam to drive the water and air from the steam chests, cylinders and passages, until steam alone issues from the drain cocks. Close the blow-through valves, and the steam having found its way into the condenser, 5

will be precipitated by the cold injection water in the pipes and form a partial vacuum. Then throw the valve gear partly into action and start the engine slowly, being sure that there is nothing to foul the screw. The links may have to be thrown back full distance in some engines to give a good supply of steam to start the machinery from rest. But as soon as started, the supply should be checked by the throttle, which can then be gradually opened wide as the vessel moves away. All the machinery will then be in regular action. The circulating pump is forcing cold injection through the condenser pipes and the air pump is drawing off the condensed steam to the hot-well or tank from which the feed pump returns it to the boiler, if operated from the main engine, or else must be given steam independently to suit. The valves can be regulated by watching the glass water gauge. In compound engines, a starting valve is placed on a connection between the steam chest of the high-pressure cylinder and the lowpressure cylinder, so that high steam may be admitted into the latter to assist in starting. ATTENDANCE WHILE RUNNING. See that the oil cups are full and wicks in order, and attend those of the cylinders, by closing the upper and opening the lower cock on the vacuum side of the piston. Watch the bearings that they may not heat. If this is found to be the case, slow down and turn on cold water to cool them. The stream should be played over the shaft and not over the brasses, as the latter are liable to crack or scale upon sudden cooling. A common cause of hot bearings is carelessness when polishing the engines with fine emery paper, as grit is very liable to work its way into the bearings. In a seaway, the throttle requires a hand stationed to manipulate the valve so as to prevent violent "racing," unless an. efficient governor is attached. Pumps and valves need attention after starting until they perform their functions as required. Steam and water gauge need constant inspection. LOW WATER. Should the water meanwhile run down in the boiler, draw the fire and leave furnace door open, or bank the fires or cover with fresh coal and leave furnace door open. But if the crown sheets are supposed to be overheated, cover the fire with damp ashes, open door and close the damper. Under no circumstances turn on the feed full speed and force cold water over the hot sheets, should it suddenly be found to work. This is a frequent cause of explosions. A very slow feed may be kept up, if it has been going at the time, but if engine and feed have been stopped do not start them, as a sudden commotion in the boiler might cause disaster. If the engines are going, do not interfere, and do not suddenly lift the safety valve, as the boiler should be left at rest under the circumstances and not be submitted to any violent disturbance. When the boiler has cooled a little, the safety valve may be lifted gently and the engines started to run down the steam. The fire should not be drawn in the extreme case of hot crown sheet, because much heat would be liberated during the attempt. It is better to smother it and open the smoke-box door to draw cold air through the tubes. In hastily drawing fires, the hot coal is dumped in front of the boiler, and the fireman finds he cannot complete the work, owing to the heat rising from the pile. He is then in trouble and apt to lose his head and quit his post, demoralizing those around him.

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After steam has run down, the boiler must be emptied and examined by a person capable of estimating the damage before risking a fresh start. With proper gauge, cocks and low water alarm, frequently tested, only gross negligence or incompetency can bring about overheated crown sheets, and even then the fusible plug should avert danger if it has been properly attended to. INSPIRATOR FAILS TO FEED. If the steam pipe is full of hot water when the Hancock Inspirator is to be started, open the steam valve sufficiently to allow the water to pass off through the inspirator and out at the overflow. If the steam pipe connecting with boiler is long, it should be of larger size than the inspirator connections, and if the pipe is horizontal, pitch it so as to return condensation back to boiler. If the suction is filled with hot water from the same cause, it may be remedied in two ways. Cool the inspirator and suction with cold water, or else pump the water out by letting the steam on and off suddenly at the starting valve of the instrument, until the hot water has been disposed of. If the inspirator does not lift water well the difficulty will nearly always be found with the suction, which must be absolutely tight to secure good results. The lift should not be out of proportion to the steam pressure, the overflow should be wide open and not choked by being piped too small. The steam and air should be given free vent at the overflow to raise the water. Sometimes when the suction is very hot, the water becomes very much heated by the time it reaches the inspirator, and it will not condense the steam; the water will come up into the inspirator, but will not pass through the jet. The simplest way to overcome this trouble is to shut off the steam and let the water down. This will cool the inspirator and suction and you can then let on the steam again and get the water without difficulty. If, after the water is got, it will not penetrate to the boiler, the cause is often due to "starving" the inspirator, not giving it water enough. It is caused by having the suction too small, so that the "lifter" does not supply the "forcer" with water enough to condense the steam on the forcer side, hence the inspirator refuses to work. Sometimes, owing to a leaky steam valve, the first water that comes is very hot, and then the forcer cannot take care of it, as it will not condense the steam. When this is the trouble, let the water run out at the overflow until it becomes cooler, then the forcer will take it and send it to the boiler. See that the check valve in the delivery pipe to boiler is not stuck down, and that it has enough play not to choke the delivery. This pipe should be as large as the inspirator connections. A leaky suction will also prevent the water going to the boiler when the forcer valve is opened and the final overflow closed.

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