174

SHEET FLUE SUPERHEATERS.

of the casing—are connected to the roof of theboiler. The two boxes horizontally situatedadmit the steam to the superheater when requi-site. The volume, after traversing through theundulated passage, reaches the main dischargevalve, which latter, when opened, permits theflow to the engines. It will be noticed, onfurther examining the plan, that on each sideof this valve box, last alluded to, a handle isshown, being a connection for manipulating thethrottle valves, which latter are closed when thesteam is passing through the apparatus in ques-tion. Now, assuming the steam is required to

deemed compact, in common with the principleexemplified. The heated products from thesmoke box pass direct through the intermediatepassages, and the cleansing requisite, therefore,rendered a simple matter. The arrangementin question is a modification by ourselves ofthat recently fitted in some vessels belongingto the P. & 0. Company’s fleet.

The description of the several examplesherein brought into notice is now concluded,and a brief summary of the several require-ments common with the principle under noticewill not be out of place.

Fig. 3G.

INTERNAL VERTICAL SHEET FLUE SUPERHEATER.

flow from the boilers direct to the engines, thevalves horizontally situated must be closed, alsothe main discharge valve at the left hand. Thevalves directly connected to the boiler areopened, also the throttle valves, and thus thesuperheater is closed to the steam.

It is seen both in plan and elevation thata supplementary valve box is secured on themain discharge branch pipe, being for thepurpose of preventing disaster from an extremepressure in the superheater. The main safetyvalves are similarly arranged on each side ofthe casing; and the entire arrangement can be

The engineer has to deal with severalmatters when he undertakes the cause andeffect of superheating. First, he has steam in'a saturated state ; second, the heated productsfrom the smoke box as an antidote for thebane; third, the application; and fourth, theform and construction of the apparatus.

Enough has been stated and illustrated toportray the several ideas generally entertainedon the subject; and the matter in question is,therefore, now condensed direct to the princi-ples most applicable for development. It hasbeen clearly shown that two functions are avail-