US566664A

US566664A - corbett

Info

Publication number: US566664A
Authority: US
Publication date: 1896-08-25
Anticipated expiration: 1913-08-25

Description

(No Model.) 4 Sheets-Sheet 1.

J. GORBETT.

STEAM GENERATOR.-

-No. 566,664. Patented Aug. 25, 1896.

Sleamh Aro frs.

mi mms vz rms La. mman-awa wwmmm (No Model.) l 4 4 Sheets-Sheet 2.

J. CORBETT.

STEAM GENERATOR. N0. 566,664. Patented Aug'. 25, 1896.

I 00000000 OOOOOOO- )Mw MM...

A TTUFE Ys.

e e..." IN.5, BOQQGQOQGOGOGO @Q o j l @3%. A

(N0 Mudel.) 4 Sheets-Sheet 3.

J. CORBETT. STE-AM GENERATOR.

Patented Aug. Z5, 1896.

ffl

/NVFNTOH ...n f? YS.

W/TNESSES.'

(No Model.) t 4 Sheets-Sheet 4.

J. CORBETT.

STEAM GENERATOR.

No. 566,664. Patented Aug. 25, 1896.

A TTOH YS'.

UNITED STATES' PATENT JOSEPH CORBETT, OF BROOKLYN, NEW YORK, ASSIGNOR OF ONE-HALF TO HENRY C. BERLIN AND THOMAS F. SHAW?, OF NEV YORK, N. Y.

STEAM-GENERATOR.

SPECIFEGATION forming part of Letters Patent No. 566,664, dated August 25, 1896.

Application led May 10, 1894. Serial No. 510,68. (No model.)

2"0 oLZZ whom t may con/cern.-

Be it lznown'that I, JOSEPH CORBETT, a citizen of the United States, residing in the city of Brooklyn, inthe county of Kings and State 5 of New York, have invented certain new and useful Improvements lin Apparatus for Generating Steam, of which the following is a specification. l

The various constructions of steam-generators heretofore known possess radical defects, which is clearly proved by the wellknown fact that the power actually obtained from the fuel is far below the theoretical equivalent of the same. This is due to three I5 diderent causes: first, to the incomplete combustion of the fuel and consequent waste of the same; secondly, to the imperfect absorption of the heat of the products of combustion and consequent escape of heat zo through the chimney; thirdly, to the loss of heat by radiation from the Walls of the furnace, boilers, condensers, dac. Many attempts were made heretofore to reduce or obviate the great loss of power incidental to all systems of generators, but all these attempts were mainly directed toward improving the instrumentalities by which the combustion of the fuel was rendered more complete, the heat of the products of combustion absorbed 3o in a higher measure, and the loss of heat by radiation diminished. No attempts, however, were made by which the various causes of waste and loss of power stated were sought to be remedied by one process and a single efficient structure by which nearly all the thermal units contained in the fuel, with the exception of a small loss of the same caused by radiation, are utilized.

The object of this invention is to furnish a 4o powergenerator in which the before-mentioned defects are almost entirely avoided, the nearly-perfect combustion of the fuel obtained, and the heatof the products of combustion and of the exhaust-steam utilized in the gradual heating and evaporating of the the heating medium, and produce by the heat of the same and the initial heat of the product-s of combustion, primarily, the superheating of the steam, which is obtained from the feed-water by the action of the products of com bustion mingled With the exhauststeain returned from the motor, the heat of which gradually transforms the feed-water into steam of lonr pressure, which is finally 6o subjected to the direct heating action of the surfaces heated by the gas and transformed into superheated steam of high pressure.

The invention consists in the constructionl of a power-generator which com prises a steam- 6 5 tank having a central heating-chamber, in which the means for heating the tank are arranged. On the heating-chamber are a number of cups to which water or saturated steam of low temperature is supplied, said steam 7o being superheated by contact with a coil in the steam-tank, through which the gases or products of combustion are conducted, and by contact with a heating-drum in the upper part of the steam-tank. The steam-tank is surrounded by an exterior tank, which forms with the outer surface of the steam-tank a reservoir, to the top part of which the exhauststeam pipe is connected, While the lower end of the coil, through which the products of com- So bustion are conducted off, is connected with the lower part of the reservoir formed between the steam-tank and its inclosing tank. The products of combustion and exhaust-steam are mingled in the reservoir referred to, so as 8 5 to form a steam-jacket around the steamtank, and then conducted through the exterior pipes of a series of concentric connectingcoils which are grouped around the steamtank, whi le the feed Water is conducted 9o through the interior pipes of said coils. The feed-water is pumped against the counterpressure of the steam generated in the steamtank and the interior pipe of the coils through said interior pipe into the steam-tank, while g 5 the gases are drawn by suction in a countercurrent to the feed-Water through the exterior pipe of the coils, so that the heat contained in the same is absorbed by and utilized in the heating and evaporating of the feed-water.

The invention consists, further, of certain details of construction by which my improved IOO steam-generator is started, and after being started reliably kept in operation; also of devices for indicating the level of the Water in the coils and the steam-tank, and of other details, which will be fully described hereinafter and iinally pointed out in the claims.

In the accompanying drawings, Figure 1 represents a side elevation of my improved steam-generator, showing the connection of the same with the different pumps by which the heating-gas, feed-water, air, the., are supplied. Fig. 2 is a plan of the same. Fig. 3 is a vertical central section on line 3 3, Fig. 2, drawn on a` larger scale. Fig. 4 is a` vertical central section of the heating-chamber of the steam-tank with its evaporatingcups, heating devices, ne., drawn on a still larger scale;Y and Figs. 5 and 6 are detail vertical' longitudinal and horizontal sections of the valveby which the interior pipe of one coil is connected with the interior pipe of the adjacent coil.

Similar letters of reference indicate corresponding parts.

Referring to the drawings, A represents a steam-tank of cylindrical or other shape, which is made of any suitable metal, so as to resist the pressure of the steam generated in the same.l At the interior of the steam-tank A is arranged a heating-chamber B, which eX- extends through an openin g in the bottom of the-steam-tank and which is connected at its top with a heating-drum B', of oval or other shape, that communicates by a valved discharge-pipe B2 with a chimney for conducting off the products of combustion when the generator is started for action. The heatingdrum B is provided with a horizontal diaphragm B3, by which the products of combustion are deflected, so that they heat up more eectively the Walls of the drum. The bottom part of the heating-drum B' is further anges or baftie plates. 134 which extend around the top part of the heating-chamber, said Iianges or plates serving to prevent the steam from carrying along mechanically some of the water that is spattered around by the ebulh'tion, said Water particles being deposited on the baffle-plates and returned again into contact with thewalls of the steam-tank, so as to be changed into' steam. ing-chamber B is heated by a number of gasjets that are emitted through openings in vertical gas-pipes b. The gas-pipes b are connected with a suitable gas and air mixing chamber C, that is preferably made of cylindricalk shape and supplied with gas by a valved pipe b2 and with air by a valved pipe b3 from a fan b4, as shown clearly in Figs. l and2. The gas and air mixture which is held under pressure in the mixing-chamber Gis conducted from the same to the gas-pipes b and' burned in the heating-chamber, a sufficient quantity of .atmospheric air being supplied to the interior of the heating-chamber by the perforated or gauze-covered end of an The heatair-supply pipe b5, so as to produce the complete combustion of the gaseous fuel. The proper burning of the gas-jets at the interior of the heating-chamber B is controlled by means of a gas-jet that is kept burning at the end of a branch pipe bx, located near the mixing-chamber O outside of the generator, as shown in Fig. l. The air-supply pipe b5 is located centrally between the gas-pipes b' and closed at its upper end, so that the air is supplied uniformly to the different gas-jets in the heating-chamber, whereby the regular combustion of the gas is kept up. The air is supplied by a Root or other blower b, and in such a quantity that the gas-jets burn with the blue color of a Bunsen burner, by which the gas is consumed in the most effective manner. The draft-produced by the fan and the supply-pipe b5 forces the products of combustion in upward direction and prevents back pressure on the gas and air mixing chamber C. The gas-jets impinge on the outer surface of the walls of the heatingchamber B and keep the same at a uniform degree of heat, so as to produce the evaporation of the water supplied to-a series of cups C', that are arranged in the steam-tank A on the Walls of the heating-chamber B. Each cup C is connected with the cup next below the same by a downwardly-extendin g supplypipe C2, so that a certain level of water is secured in the cups. When the generator is to be started, a quantity of water is supplied to the cups by means ofa water-supply pipe e, that passes through the bottom of the steamtank A and terminates by its bent upper end in the uppermost cup C', as shown clearly in Figs. 3 and 4,. from which the water is supplied by the pipesV G2 from cup to cup until collected in the lowermost cup, which sheds its overfiow into the lower part of the steamtank. providedv with exterior depending annular i Between the steam-tank A and the heatingchamber B is arrangedv a coil D, that is coninected at its upper end with the pipe which leads from the crown-sheet of the heatingchamber B to the heating-drum B', said coil .serving for conducting off the products of combustion, so that the heat radiated by the coil D serves-to superheat the steam generated in the steam-tank. When a certain vquantity of live steam of a sufficient pressure -is generated, the same is passed through the steam-pipe A to the cylinder of the steamengine. The live-steam pipe Ais provided with a safety-valve A2, that is arranged in a blow-off pipe A3 of the steam-pipe A', which blow-off pipe terminates in the top part of an exterior tank E, that incloses the steam-tank A. From the live-steam pipe A/ a branch pipe A4 leads tb a steam-engine S, by which the different pumps, blowers, and fans required for my improved generator are operated, as shown in Figs. l and 2.

lVhenever the pressure of the steam in the steam-tank rises above the pressure for which the safety-valve A2 is-adjusted, the latter is yss opened, so that the steam passes through the blow-ott pipe A3 into the tank E, in which it is mingled with the exhaust-steam that is returned from t-he engine by means of the exhaust-steam pipe E. As the temperature of the exhaust-steam is but slightly lowered in its passage through the steam-engine, though its pressure is reduced by the work done in the steam-engine, the exhaust-steam can be etlectively utilized for heating and evaporating the feed-Water. The exhaust-steam and such live steam as escapes through the safetyvalve and blow-oft' pipe fill the reservoir formed between the exterior tank E and the steam -tank A and form thereby aV steamjacket around the walls of the steam-tank, so that any loss of heat by radiation from the latter is entirely obviated. A thermometer t extends into the steam-tank A through the vertical part of the live-steam pipe A', so as to indicate the temperature in the same, while a pressure-gage g indicates the pressure and water-gages w and w indicate the level of the water in the lowerinost evaporating-cup C' and the lower part of the steam-tank, said water-gages being connected by pipes respectively with the lowermost cup O' and the bottom of the steam-tank and with the live-steam pipe A', as shown in l and 3. By means of the accessories just described the temperature of the steam generated in the steamtank, the pressure of the same, and the level of the water in the oups and tank are readily controlled.

The lower end of the coil D is connected with the lower part of the reservoir formed between the steam-tank A and the exterior tank E, so that the products of combustion can mingle with the exhaust and surplus steam. From the bottom of the tank E the mixture ot' the products of combustion and of the exhaust and surplus steam is conducted through a bent pipe D to the exterior pipes of a group of concentric coils F F F2 F3, which are arranged around the taukE and inclosed by a double-Walled jacket J, that is iilled with asbestos or other suitable non-conductor, so as to prevent, as much as possible, the radiation of heat from said coils. In the coils F F F2 F3 are located interior pipes, which are connected with each other by valves f, that are arranged alternately at the upper and lower parts of the coils, and which serve to check the steam, so as to prevent it -from passing from the inner pipe of one coil to the next adjoining one. The valves f are shown in detail in Figs. 5 and G and partake of the nature of check-valves that are closed by the pressure of the steam but open ed by the counter-pressure of the feed-water. The outer end of the interior pipes of the coils is connected by a pipe f 2 with a pump F, by which the supply of feed-Water to the interior pipes of the group of coils is kept up. /Vhen the feed-wateris forced through the interior pipes of the coils at a pressure higher than the pressure exertedby the steam on the valves f, the latter are opened, so that the feed-water is successively supplied from the interior pipe of the outermost coil to the interior pipe of the coil next adjacent thereto, then to the interior pipe of the next coil, and finally to the interior pipe of the innermost coil, from the lower end of which it is supplied by a bent and valved pipe f3, passing through the bottom of the jacket J, to the interior of the steam-tank A. The bent pipe f3 is divided at the interior of the tank into a number of smaller pipes f4, one for each of the evaporating-cups C', which are arranged on the heating-chamber B, as shown clearly in Fig. 4.

As soon as the generation of steam in the steam-tank is sufficiently advanced, so that the live steam has the required pressure to operate the engine that is to be supplied by the steam, the direct supply of water to the evaporating-cups of the steam-tank is shut oft. Owing to the high temperature of the products of combustion and the exhauststeam that are passed through the exterior pipes of the coils, the feed-Water that is forced through the interior pipes of the coils in a counter-current to the direction of the mixture of gases and exhaust-steam is heated up and gradually changed into saturated steam in the pipes, even before it can be delivered into the interior of the steam-tank A. For the purpose of indicating the level ot' the feed-water in the coil, in the convolutions of which the change from water into steam is produced, the connecting-valve f of the iirst and second coils, which is located at the upper part of the coils, is connected bya pipe f5 with the valve f, which connects the interior pipes of the second and third coils, and which is located at the lower part of said coils, as shown clearly in Fig. 3, the connecting-pipe being provided with a water-gage f6, so as to indicate thereby the level of the water in the second coil and the exact point at Which the evaporation of the feed-water commences. The connecting-valvef between the third and fourth coils is arranged at the upper part of said coils and provided with a pressure-gage p, which indicates the pressure in the inner feed-water pipes, so that by the difference of the pressure, indica-ted on the gage p and the live-steam gage g, the pressure at which the `feed-water has to be pumped through the interior pipes on the coils may be readily determined. This is an important feature, as the proper operation of the generator can only take place when the pressure of the feed-water is equal to the pressure of the live steam, so that the feed-water and the steam generated thereby cau be forced through the interior pipes of the coils against the pressure of the steam generated in the steam-tank, so as to produce thereby the supply ot saturated steam to the cups and the superheating of the same by the contact of the walls of the heating-chamber, heating- IOO IIO

IZO

drum, and steam-tank, and with the surface of the interior coil D.

The different pumps and blowers for supplying the feed-water and the atmospheric air are arranged in suitable proximity to the steam-generator and operatedV by the steamengine S, which is supplied with live steam by the pipe A4. The suction end of the blower 126, by which the air is supplied to the interior of the heating-chamber, is connected by apipe f7 with theV outer end of the exterior pipe of the coils7 so as to produce the required suction on the products of combustion and the exhauststeam in the tank E and draw them through the exterior pipes of the coils. The water of condensation that is produced by the gradual lowering of the temperature of the exhaust-steam in its passage through the exterior pipes, owing to the absorption of the thermal units by the feed-Water,is drawn off by pipes from the lower part of the exterior pipes of the coils into suitable traps, so that the products of combustion are entirely free from exhaust-steam when they leave the exterior pipes of the coils, showing thereby that the entire heat that was contained in the exhaust-steam was absorbed by the feed-water and utilized in theheating and evaporating of the same on its way through the interior pipes of the different coils to the steam-tank A. A slide-valve f8 is arranged in va branch pipe of the suction-pipe f7 and serves to draw in a sufiicient quantity of atmospheric air, which is mixed with the products of combustion and forced by the blower into the heating-chamber B, so as to sustain the combustion of the gas in the same.

In the foregoing description of myimproved steam-generator' the same is described as applied to the generation of steam from Water by means of gas; but it is obvious t-hat in place of water any other medium that can be expanded by heat and utilized for the pro` duction of power can be used, while in place of gas any other fuel may be used, the terms Water, steam, and gas beingintended to cover all other media which can be used for the generation of power.

The operation of my improved steam-generator is as follows: For starting the same the valve of the discharge-pipe B2 is opened and the valve f3, that is located below the point of supply of saturated steam through the steam-tank, closed. Vater is then supplied to the different cups and the heatingchamber, and the gas-jets lighted and a regular supply of mixture of gas and air from the mixing-chamber C and of air for the combustion of the gas kept up. The water is generated into steam by the heat of the gasjets, the products of combustion being drawn off through the heating-drum B to the chimney. When live steam of sufficient pressure is obtained, the engine is started and the exhaust-steam returned to the exterior tank. The valve of the exit-pipe B2 is now closed and the valve f3 opened. The direct waterward the source of heat.

supply pipe for the cups is closed and the feed-water pipe fzopened and suction applied to the outermost end of the exterior pipes of the coil system. The length-and surface of the coils have to be in proportion to the size of the steam-tank and to the number of horsepowers to be produced. The products of combustion are now drawn through the coil D and theV initial heat of the same absorbed by the steam in the steam-tank, so that the temperature of the products of combustion is reduced as near as possible to the temperature of the exhaust steam. The exhauststeam is mixed with the products of combus- Y tion in the exterior tank and the mixture of both drawn by suction through the exterior pipes of the coil system7 so that gradually the heat contained in the same is absorbed by the feed-water which is pumped at a pressure sufcient to overcome the counter-pressure of the steam on the connecting-valves of the different coils into the interior pipes of the coil system. The water of condensation that collects in the lower part of the exterior pipes of the coils is trapped off, while the products of combustion are emitted nearly at the temperature of the feed-water. The feed-water in its course through the interior pipes of the coils is moved in opposite direction to the mingled products of combustion and exhaust-steam which are drawn through the exterior pipes of the coils, said heat agencies gradually increasing in temperature to- The temperature of the feed-water is gradually raised by said heat agencies'until it arrives at the boilingpoint, it being changed into saturated steam of low pressure even before it is supplied to the steam-tank, so that saturated steam is supplied to the cups and to the heating-surfaces in the steam-tank. The temperature of the steam is raised by its contact with the heating-surfaces of the tank A, cups C', coil D, and heating-drum B', and the steam transformed into superheated steam of high pressure, which is then conducted through the live-steam pipe to the motor. The cycle is thus completed and the thermal units contained in the fuel utilized entirely, with the.

exception of a small loss by radiation, from which a number of advantages result, namely: first, avery compact arrangement of all the parts of the generator around the steam-tank, so that a great proportion of the loss caused by radiation in the generators heretofore in use is prevented; secondly, economy in fuel by the almost perfect combustion of the fuel and the total absorption of the thermal units in the heating of the feed-water and the generation Of steam from the same; thirdly, the dispensing of the expensive smoke-stacks for creating the draft, also of furnace walls and grates, whereby the expense of the steamgenerating plant is considerably reduced; fourthly, no danger by explosion and the facility of putting up the generator at any suitable point, so that a great number of incon- IOO IIO

Venient regulations may be dispensed With. It follows, therefore, that my improved generator is adapted in a highdegree for all domestic and manufacturing purposes, also for marine and similar purposes, as in the latter of a closed steam-tank having an interior heating-chamber, evaporating-cups on the Walls of the heating-chamber, in the steamtank, and means for heating the Walls of the heating-chamber, substantially as set forth.

2. In a steam-generator, the combination of a closed steam-tank, a heating-chamber located at the interior ofsaid tank, evaporating-cups on the Wall of said heating-chamber, gas-supply pipes extending into the heating-chamber, and an air-supply pipe for supplying the air necessary for combustion, substantially as set forth.

3. The combination, of a closed steam-tank, a heating-chamber located in said steam-tank, evaporating-cups on the Wall of said heatingchamber, means for heating the Walls of said chamber, and a feed-Water pipe for supplying Water to said cups, substantially as set forth.

Ll. The combination of a closed steam-tank, a heating-chamber located in said tank, evaporating-cups on the Wall of said heatingchamber, means for heating said chamber, pipes extending from one eVaporating-cup to the other, and a feed-Water pipe for supplying the uppermost cup, substantially as set forth.

5. The combination with a closed steamtank having a heating-chamber in said tank, evaporating-cups on the Wall of said heatingchamber, means for heating the Walls of the heating-chamber, and pipes leading into each cup for conducting saturated steam into the same, substantially as set forth.

G. The combination with a steam-tank, a heating-chamber located in said tank, evaporating-cups on the Wall of said heatingchamber, means for heating the same, and water-gages connecting the lowermost cup and the bottom of the steam-tank respectively with the live-steam pipe of the steam-tank, substantially as set forth.

7. The combination of a steam-tank, aheating-chamber located in the same, means for heating the Walls of the heating-chamber, evaporating-cups on the walls of the heatingchamber, and a heating-drum in the steamtank, connected with the top of the heatingchamber and provided with a Valved exitpipe leading to the chimney, substantially as set forth.

S. The combination of a steamtank, aheating-chamber located in the same, means for heating the Walls of the heating-chamber, eVaporating-cups on the wall of the heatingchamber, aheating-drum in the steam-tank connected with the top of the heating-chamber, and dependent flanges or baffie-plate eX- tending from the lower part of the drum around the uppermost eVaporating-cup and the top part of the heating-chamber, substantially as set forth.

9. The combination, with a steam-tank, a heating-chamber located in the same, evaporating-cups on the Wall of t-he heating-chamber, means for heating said chamber, and a coil located between the steam-tank and the heating-chamber and connected with the top of the heating-chamber so as to conduct off the products of combustion for further use, substantially asset forth.

l0. The combination, of a steam-tank, a heating-chamber located in said tank, evaporating-cups on the Wall of said heating-chamber, means for heating the heating-chamber, a coil connected with the top of the heatingchamber, and an exterior tank inclosing the steam-tank, said exterior tank being connected with the lower end of the coil, substantially as set forth.

ll. The combination, of a steam-tank, a heating-chamber in said tank, means for heating said chamber, an exterior tank surrounding the steam-tank, an exhaust-pipe terminating in the top of the exterior tank, and a conduit for the products of combustion connecting the top of the heating-chamber With the bottom of the exterior tank, so as to produce the mingling' of the products of combustion and exhaust-steam in the reservoir formed by the Walls of the steam-tank and exterior tank, substantially as set forth.

l2. The combination, of a steam-tank, a heating-chamber in said tank, means for heating said chamber, eVaporating-cups on the Wall of the heating-chamber, a coil located between the heating-chamber and the steamtank and connected with the top of the heating-chamber, an exterior tank inclosing the steam-tank, and being connected with the lower end of said coil, and an exhaust-pipe terminating in said tank, substantially as set forth.

13. The combination, of a steam-tank having an interior heating-chamber, means for heating the Walls of said chamber, evaporating-cups on the walls of the heating-chamber, a live-steam pipe communicating with the top of the steam-tank, an exterior tank inclosing the steam-tank, a blow-off pipe connecting the live-steam pipe with the top of the exterior tank, and a safety-Valve located in said blow-off pi pe, substantially as set forth.

14E. The combination, of a steam-tank, a heating-chamber located in the same, means for heating the Walls of the heating-chamber, an exterior tank inclosing the steam-tank, an exhaust-steam pipe connected with the exterior tank, a coil connecting the heating- IOS XIO

chamber with the space inclosed by the exterior tank, a series of connected coils composed of exterior and interior pipes, the inner end of the exterior pipes being connected with the exterior tank, While the outer end is connected with a suction-pipe, a feed-Watersupply pipe connected to the outer end of the interior pipes, and supply-pipes connecting the inner end of the interior pipes with the steam-tank, substantially as set forth.

l5. The combination7 of a steam-tank, a heating chamber in said tank, means for heating said heating-chamber, an exterior shell inclosing the steam-tank, a coil connecting the heating-chamber with the bottom of the exterior tank, an exhaust-steam pipe connected with the top of the exterior tank, a series of connected coils composed of exterior and interior pipes, a pipe connecting the exterior' tank with the inner end of the exterior pipes of the coils,a suction-pipe connected with the outer end of the exterior pipes, a feed-Water pipe connected With the outer end of the interior pipes, a supply-pipe connecting the inner end of the interior pipes with the steam-tank, and check-valves connecting the interior pipes of the coils, substantially as set forth.

1G. The combination, of a steam-tank, a heatingchamber in said tank, means for heating the heating-chamber, a tank inclosing the steam-tank, an exhaust-steam pipe connected to the top of the exterior tank, a coil connecting the heating-chamber With the bottom of the exterior tank, a series of connected coils formed of exterior and interior pipes, means for drawing the mingled products of combustion and exhaust steam through the exterior pipes, means for forcing the feed-Water through the interior pipes in opposite direction to the direction of the gases in the exterior pipes, check-Valves in the interior pipes at the points of connection of one coil with the adjacent ones, and a Water-gage connecting check-Valves of the coil in which the evaporation of the feed- Water commences, substantially as set forth.

17. The combination, of a steam-tank, a heating-chamber located in said tank, evap- 'oratin-g-cups on the Walls of the heatingchamber, meansV for heating the latter, an exterior tank inclosing the steam-tank, and a series of coils composed of exterior and interior pipes which are connected respectively with the exterior tank and with the steamtank, means for supplying the feed-Water to the interior coils of the pipes, and means for drawing the products of combustion and exhaust and surplus steam through the exterior pipes of the coils in a direction opposite to the direction of the feed-Water, substantially as set forth.

18. The combination, of a steam-tank, a heating-chamber in said tank, an exhauststeam pipe opening into the steam-tank, and a series of coils encompassing the steam-tank and composed of exterior pipes for conducting the products of combustion and the exhauststeam, and of interior pipes for conducting the feed-Water in a counter-current to the products of combustion and exhaust-steam, so that the heat of the products of combustion and exhaust-steam may be absorbed by the feed-Water, substantially as set forth.

In testimony that I claim the foregoing as my invention I have signed my name in presence of two subscribing witnesses.

JOSEPH CORBETT.

lVitnesses:

PAUL GOEPEL, K. R. BRENNAN.