US2685332A - Fluid-fuel furnace plant for steamdriven vehicles - Google Patents

Description

Aug; 3, 1954 FLUID-FUEL Filed Nov. 1, 1950 5 Sheets-Sheet l lN VEN TOR [Zia/ix; cfipreggex" I WYM 8 1954 E. SP-RENGER 2,685,332

FLUID-FUEL FURNACE PLANT FOR STEAM -DRIVEN VEHICLES Filed Nov. 1, 1950 5 Sheets-Sheet 2 Aug. 3, 1954 E. SPRENGER FLUID-FUEL FURNACE PLANT FOR STEAM-DRIVEN VEHICLES Filed Nov. 1, 1950 5 SheetwSheet 3 INVENT OR w aaza,

Aug. 3, 1954 E. SPRENGER 2,685,332

FLUID-FUEL FURNACE PLANT FOR STEAM-DRIVEN VEHICLES Filed Nov. 1, 1950 I 5 Sheets-Sheet 4 H JINVENTORL' 42 Fawz'n 5prenger Patented Aug. 3, 1954 FLUID-FUEL FURNACE PLANT FOR STEAM- DRIVEN VEHICLES Edwin Sprenger, Zurich, Switzerland Application November 1, 1950, Serial No. 193,449

Claims priority, application Switzerland November 17, 1949 2 Claims. 1

My present invention relates to a furnace plant for steam-driven vehicles, especially steam locomotives, operated by fiuid fuel. Such furnace plant mainly is intended for incorporation in vehicles originally built for coal-firing, for example locomotives or ships, without requiring any mechanical changes in existing furnace plants, i. e. solely by inserting or replacing certain attachments. Such incorporation requires no technically diflicult and time-consuming work, nor special tools, and thus may be accomplished in one to two days.

It is well known in the art that the greatest difficulties encountered in such furnace plants is the control of the fuel supply, i. e. the establishment of the most favorable fuel and air mixtures under all operating conditions. In known furnace plants, involving for example oil heating, the fuel is controlled in accordance with the pressure prevailing at a certain point in the upper portion of the firebox. The fuel and air mixtures generated in the fire box are burned in different manners, depending on the various fluctuating conditions of mixture, draft and temperature. The most diversified pressure conditions thus arise in such a fire box, and zones of positive and negative pressure may be closely adjacent to each other. The respective pressure values may change abruptly from a minimum to a maximum and the fuel supply control cannot be adapted to these rapidly changing conditions.

In such mobile furnace plants, in contrast to stationary plants the air supply cannot be kept constant, the volume of air required for optimum combustion being very great, due to the relatively small dimensions of fire box and grate; ordinarily amounting to from 50 to 100 times the amount of air required in stationary plants. Such air throughput moreover is highly variable and may abruptly vary from a maximum to a minimum (from zero to 16- inches water-column subpressure). When, in this connection, the amount of fuel required for an optimum fuel and air mixture is not also adapted forthwith to the given air volumes, the entire boiler aggregate may be cooled down to a point at which boiler and fire box may become seriously damaged. On the other hand, an excess of fuel may generate an excessive amount of smoke so as to soot up the entire boiler system and soil the entire train with a pitch-like deposit. Aside from the foregoing disadvantages, such uncontrolled operation is, of course, very uneconomical and annihilates the advantages obtainable in such a furnace plant by fluid fuels. In order to attain an automatic regulation of the fuel supply in correspondence with the abruptly and frequently varying pressure conditions in the fire box, it has been proposed to employ control devices using fiaps or diaphragms. Rotary flaps for example have been incorporated in the fire door, which swing into the open or closed position in accordance with the pressure conditions in the fire box. No attention, however, has been given to the fact that, as mentioned before, pressure zones and subpressure zones may be closely adjacent to each 1 other and that therefore, the pressure-responsive flaps in the fire door give results which vary according to the angular position. Since, moreover, when the flaps are open, the interior of the fire box communicates with the atmosphere, the subpressure existing in the fire box may be completely, or at least partly, destroyed, quite apart from the detrimental effect of the inflowing cold upper air on the entire boiler-tube and boilersystem. The required fuel supply control in correspondence with the given air conditions, thus is not attainable by these means.

From what has been said above, there follows that a positive connection has to be provided between the fire-box air intake and the control elements in order to exactly adjust the fuel supply at any moment to the air supply. In order, however, to create in the fire box air conditions, corresponding to those in the air intake, i. e. to the air conditions instrumental for the control, there has to be provided between the air intake and the fire box a substantially constant air resistance, and the air flowing into the fire box has to be distributed at a constant rate and uniformly with respect to the grate cross-section.

Certain safety means have been provided to ensure a positive operation of the plant. It is very important for the engineer to be able to continuously survey the control movements produced in the air intake. Further, means should be provided for overriding this automatic control arrangement by a manually operated control means. Further means should be provided to take each individual fuel valve and its associated nozzle out of operation for a short time and to blow same out by a simple manipulation, for example by superheated steam from the boiler or by compressed air from the brake system, and to again put the same into operation. It thus is possible to prevent beforehand the valves and nozzles from becoming blocked and the operation from being interrupted.

Additional difficulties arise from the variation of the fuel viscosity during operation, or from using a different fuel. When all other conditions of the plant remain unchanged, it is possible to also vary the amount of fuel in proportion to the changed viscosity without influencing the action of the control means itself. This is of special importance where the climatic conditions, for example the outside temperatures, are liable to vary much in operation, or when very different fuels are used. Such variations, for example in case of varying steam generation (excess or lack of steam) may be read directly from the manometer, and the corresponding adjustment may be applied, for example by actuating a handlever, with the aid of a corresponding scale.

Another point of importance in such plants is the assurance of a steadily occurring ignition of the fuel and air mixture so as to completely eliminate an extinction of the flame and thus also the occurrence of explosions.

Further means are provided to vary the air supply, i. e. the cross-section of the air intake, from a maximum down to zero independently of the adjustment of the control of the furnace plant. All the members for actuating the various control elements, suitably are combined in a single control unit, for example a control pillar, which unit may be mounted in a simple manner in the drivers cab. All the parts and portions of the furnace plant may be fully assembled prior to being mounted into the corresponding vehicle. The instruments and apparatus already present in the vehicle, may be further used. When such installation has been made once, the Vehicle may be used, as desired, in connection with either fluid or solid fuels by simply and rapidly replacing certain parts, for example the grate, the ash box or air box, and the fuel tank. Such conversion from coal to fluid fuel, or vice versa, may be accomplished within two to three hours.

In order to fulfill all the said requirements and objects, the furnace plant disclosed by my present invention, as applied to steam-operated vehicles, and in particular to steam locomotives, cornprises an air intake having a variable cross-section and associated with a fire-box grate-bed provided with a plurality of superposed layers of adjacent balls made of a refractory material and forming a constant and uniform air resistance. In said air inlet there is disposed a device responding to a torque produced by the velocity of the infiowing air, which velocity varies exactly in relation to the variable suction effect of the vehicle waste-steam. The said device serves for applying a control movement proportional to the square of the air velocity in the inlet, to a first converter. The latter converts the said control movement into a contro1 movement which is linearly proportional to the said air velocity, and applies the latter movement to an element of a clutch. By means of said clutch a control shaft disposed in a casing may be alternatively connected to said device or to a manually operated regulating member. The plant further comprises an indicating means associated with said first converter and adapted to indicate the linearly proportional control movement of said converter, and an adjusting mechanism connected to the control shaft and adapted to alter the control movement of the control shaft in proportion to a variation of the viscosity or change of state of the fluid fuel. Further, a second converter is connected to said adjusting mechanism for converting the control movement thereof into a control movement proportional to the fuel flow through the fuel valves. Moreover, transmission means are provided for transmitting the last-mentioned control motion to the valves, and a burner system for injecting the fuel into the fire box, a compressed gas, for example steam or air, being supplied to the burner system, which gas may serve for cleaning the burner system and the valve systern as well as for being mixed with the fuel or atomizing the same respectively.

The arrangement disclosed by my present invention is adapted to produce an optimum fueland-air mixture under all operating conditions since the control movement transmitted to the valves and, therefore, the rate of fuel flow through these valves, at any moment of operation, is adjusted to the velocity of air flowing through the intake and, therefore, to the air available for combustion.

The special structure of the grate bed affords an air distribution which is uniform over the entire grate cross-section. The grate bed which is made up of refractory balls, also forms an effective heat storage means in that, for example when starting up the plant, a large part of this heat is stored in the balls, and is only gradually delivered to the fire-box walls, thus preventing inadmissible heat stresses therein. When combustion is stopped, the ball bed serves as heat storage means which causes the boiler system to cool down only gradually by virtue of continued heat delivery. As shown by tests, the steam pressure will drop to zero only after about 10-12 hours, when the air intake is closed. The ball bed which during operation is white hot, may prevent the flame from tearing off, even when air is supplied in surges. Even after a longer interruption of operation, i. e. as long as the balls are still red hot, this grate-bed ensures a quick and reliable ignition of the fuel. In operation, the ball bed serves as preheater for the inflowing cold air. By correspondingly arranging the balls, the flames may be guided in accordance with the construction of the fire box, the flames moreover being intercepted by the balls, torn apart and uniformly distributed over the grate-surface, whereby they are uniformly lifted by the hot grate. The flames, thus, may be prevented from squarely impinging with full force against the fire-box rearwall, which otherwise might cause local over-heating, cracks or bumps.

The said first converter further permits of converting the control movement applied to the said torque-responsive means, which movement is proportional to the square of the intake air velocity, into a control movement which is linearly proportional and, thus, easily controllable.

One form of my present invention, namely, an oil-fired furnace structure incorporated in an originally coal-fired steam locomotive, is shown schematically in the accompanying drawings, in which- Fig. l is a perspective phantom view,

Fig. 2 is a similar view of the head of the control casing,

Fig. 3 is a similar view of the control arrangement,

Fig. 4 shows an axial section of the valve box according to Figs. 1 and 3,

Fig. 5 is a view of the piping, representing a flow sheet for a first method of firing the locomotive,

Fig. 6 is a View similar to Fig. 5, but for a sec-- ond method of firing,

Fig. '7 is a similar view for a third method of firing,

Fig. 8 is a similar view for normal operation.

In Fig. 1, the ash box of the originally coalfired fire box I has been removed and a Wind box 2 built in by means of the existing wedges 3. In place of the usual grate, a permeable special grate 4 has been installed on the peripheral flange of the wind box 2, which grate may for example be formed of a plurality of grate plates provided with alined openings 5. Above these plates a grate bed is provided which comprises a plurality of layers of balls 6 made of a refractory material. An angular flange I of the wind box 2 carries an angle joist 8, on which the combuster is disposed. That leg of joist 8 which bears on flange I carries a plurality of fuel nozzles iii. The orifices of the latter are substantially at right angles to the orifices of spray nozzles II (one only being shown in Fig. 1), which are arranged on the free leg of joist 8. The spray nozzles I I are connected to a superheater tube I2 which extends over the entire width of fire box I.

The wind box 2 comprises an inlet conduit I3 which serves as air intake for the entire air throughput of the furnace. The lower, conically flared edge of inlet I3 is provided with bafile rings I3u. The latter are intended to equalise, before the intake, the air inflow under all the various flow conditions as defined by the speed of the locomotive, the wind velocity, the wind direction and the like, by destroying any undesirable flow tending to alter the conditions in the intake independently Of the suction action in the chimney, by producing whirls and eddies in the infiowing air. Thus, when the locomotive stands still, the same flow conditions may be produced in the air intake as at full speed.

A blade wheel I4 fixed to a torsion bar I5 is disposed in the intake I3 and is capable of turning against spring action through an angle of 180 for example. The torsion bar I5 is mounted in cross-arms I6. The shaft I5 on its free end extending into the wind box 2, carries a rotary disc II which is engaged by a pull element IS. The latter on one hand is connected through an equalizing spring I9 to the corresponding control members disposed in a control casing 20, and on the other hand is acted on by an adjustable regulating spring 2 I (Fig. 3), this spring 2| being connected to an adjusting screw I42 threading into the wall of casing 20. The pull element I8 may be enclosed in a protecting tube. The control casin 28 at its central portion is connected to a corresponding step on the floor 23 of the drivers cab of the locomotive L and on its upper part carries the operating levers a, b, c, d and e.

According to Figs. 5-8, fuel is supplied to the injection nozzles I I3 via the following elements: a main fuel tank 24 is disposed in the tender T of the locomotive L, in the place formerly occupied by the coal, which via a reducing valve 25 and a' pipe 26 is connected to an air-equalizing tank 21 associated with the Westinghouse brake. A pipe 23 runs from the bottom of the tank 24 Via a three-way cock 29, a fuel-filter 36 and a manometer 3I into the jacket 32 of a heat exchanger. The latter is connected to a float chamber 33, which serves for establishing a constant-pressure level, and from which a fuel pipe 34 runs into a header S5. A number of branch pipes 36, corresponding to the number of injection nozzles III, are connected to the header 35, and each branch 335 comprises a three-way cock 31 and a fuel valve 38, and communicates with an injection nozzle Ifl.

A steam pipe 40 runs from the head of the steam boiler 39 through the jacket 32 of the heat exchanger and comprises a three-way cock II. The pipe 40 on one hand opens to the atmosphere through a drain cock 42, and, on the other hand,

is connected to the superheater tube I2 disposedon the angle joist 8. A pipe 43 is branched 01f pipe 40 and passes through the floor 23 of the drivers cab and comprises a three-way cook 44, from which a forked branch 44a on one hand runs into the air-equalizing tank ZI, and on the other hand, to a reversing cock 43a to which a pipe Me is connected. The three-way cocks 31, the fuel valves 38 and their respective supply lines are disposed in a square casing 22 (Figs. 3 and 4) the cocks 3! being actuated for example by means of a square key (Fig. 4). v

The drain cock 42 of line 40 serves for draining any condensate in the line and is actuable (see Figs. 1 and 3) through the lever 45 and a pull element 46 by the hand lever d. A line 40a also is connected to line 40.

The tank 24 via a stop cock 20a is connected to an auxiliary tank 2411 from which a branch 29a runs to the three-way cook 29 and a branch 28a to a hand-pump 30a. (In Fig. 1 only a portion of the flow scheme is shown.)

Closable louvres 41 and 48 (Fig. 1) are provided in the air inlet I3, being pivoted at 49. The louvres 41 ar pivotable through a pull element 59, and the louvres 48 through a pull element 5i. The pull elements 50 and 5| are hinged to rackrods 52 and 53 respectively, which on their part engage a gearwheel I54 journaled in the engine frame. The gearwheel 54 through a shaft 55 is connected to a roller 51 which is engaged by a pull element 56. The latter is actuable by means of an air lever e which is pivoted to the control casing 20. The closing movement of the louvres 41 and 48 may for example be aided by corresponding springs. The transmission shaft (II) (Fig. 2) which is excentrically journaled in the casing 20 and to the lower end of which a disc 58 is secured, which latter coacts with the pull element I8, carries a cam 62 above a horizontal partition 6|. The cam 62 together with a follower 63 forms the f rst converter A. The follower 63 comprises a roller 64, which engages the cam 62 and is pivoted on two arms 65 of the follower. The latter is pivoted on a stud 66 secured to the partition GI, and has a third arm 6! to which a spring 68 is secured, the other end of the spring being secured to the partition 6|. The follower 63 also comprises a toothed segment 69 which engages a pinion ill of an element II of a clutch B. The latter by means of a ball bearing I2 is freely rotatable on the top shoulder of a vertical control shaft I3 to which a bush I5 having a flange I4 is rigidly secured. A coupling sleeve I6 having two terminal flanges II and I8 is axially movable within limits over the bush I5. The two terminal flanges II, I8 are provided with two diametrically opposite bores each for receiving two coupling pins I9 which at both ends project beyond the two flanges. The two pins I9 are pointed at both ends to coact with corresponding bores Bil, in element II, and are axially movable in bores provided in the flange I4 of bush I5 which is fixed to the control shaft I3.

The axially movable sleeve It thus is positively connected to control shaft I3 for rotation therewith. A helical spring BI abuts against the upper end face of bush I5, and at the other end bears against the inner side of flange II, thus tending to push the coupling sleeve upwardly into th coupling position.

A forked lever b fulcrumed to a stud 82 on partition GI serves for actuating the clutch B. In the disengaged position shown in Fig. 2, the

arms .83 with their downwardly bent ends bear on'the terminal flange 18 against the action of spring 8 I. In such disengaged position, the lever b is retained by means of a sliding pawl 82, the lock pin 85 of which is engaged in an upper aperture 85 of the casing 29. The lever in is vertically tiltable in a recess -81 of casing to, the sliding pawl 84 by means of a knob 88 being in wardly movable against the actionof a spring 89, whereby the pin 85 is withdrawn from the opening 86. After tilting the lever 1) into the lower, 1. e. the clutching position and releasing the knob 38, th pin 85 is engaged in a lower opening 90. Due to such clockwise rocking of the lever b, the fork arms '83 are raised from flange 18 and the spring BI pushes the coupling sleeve 16 upwardly whereby the pins 19 are engaged in the bores 30 of element II. The control shaft 13 thus is positively coupled for rotation to the firstconverter A through the elements 14, 19, H, and 10, and therefore also with the fan I l (Fig. 1).

In order to permit-at otherwise stable conditions in the plant-of varying the rate of fuel supply in direct proportion to any changes in the viscosity of the fuel without biasing the control efiect, ther is provided an adjusting mechanism C in the casing 29. The said mechanism comprises a toothed segment 9| horizontally pivoted to casing 29 and engaging a pinion 92 fixed to control shaft 13. The latter in its lower portion passes through a sleev 93 of which the upper terminal flange 94 abuts against a horizontal partition 95, and carries a ball bearing 96 for the control shaft 13. In the segment 3I a radial slot 91 is provided, in which is guided a pin 98 of a rack rod 99. The latter is axially movable on a spindle IIlfl which is arranged in a slide IIlI transversally of shaft 13. The slide IBI is movably mounted in the casing 29 in a horizontal plane, transversely of control shaft 13 and of the directionof movement of rack 99.

The latter also is in engagement with a toothed roller I03, secured to a shaft Hi2 which is journaled in casing 20 at right angles to rack. 99. In order to move the slide Ii)! on the guide pins HM, a toothed flange IE is provided on the slide, which engages a toothed segment I08 of the adjusting lever c. The latter is swingable on sleeve 93 in an are limited by a pin IE1 of sleeve 93, which pin coacts with a slot IE8 of lever c.

The second converter D comprises a cam I69 fixed to shaft I92 and coacting with a roller Hi3 of a follower II I, which on its uppermost part is fixed to an axle pin H2. The latter is mounted in a boss H3 secured to partition 95 and on its free end is fixed to an arm H4. The latter is pivoted to a push rod H5 of the transmission means E (Fig. 3).

The push rod H5 passes downwardly through the bottom of control casing 29 and on its free end is hinged to an arm H6 (Fig. 3) which is fixed to a transmission shaft H1 journaled in a casing 20a attached to box 22. The transmission shaft H1 comprises a plurality of rockers H9 (Fig. 4) of a number corresponding to that of the nozzles II] or valves 38. The rockers H9 act through adjustable screws I20 on valve rods I2I. Such a valve 38 is shown in detail in Fig. 4. The valve casing is subdivided by a ring wall I22, the inner edge of which serves as a seat for a conical valve body 123 disposed on the shouldered valve rod I2I, into an inlet chamber I24 .and an outlet chamber $25, an inlet port I26 and an outlet port I21 being provided. A spring I28 in 8 th inlet chamber I23 .holds the ring wall (valve seat) I22 in its proper position, whereby a spring I39 acting on the valve body I23 and on a bearing ring 129 tends to hold the valve body I23 in the closed position. The control casing 20 further comprise an indicating device F (Fig. 2) involving a segmental inset in the partition 6%, which inset is provided with an outer and an inner graduation I3I and I32. A pointer I33 fixed to clutch element 1I coacts with scale I32 and permits of reading therefrom the control movement which has been transformed by the first converter A and which is linearly proportional to the air velocity through inlet I3. The extent of graduation I32 is such that a deflection of pointer I33 through corresponds to a swing of (for example) of the blade wheel I4 and torsion bar I5 against the action of spring 2 I, which swing embraces all the possible operating conditions.

A further pointer I32 coacting with the outer, similar graduation I5, is secured to the lever a of the regulating member G, which lever is movable in a slot I35 of casing 29 on the flange .94 of sleeve 93, which flange is embraced by an arm I36 of lever a. The terminalfiange 18 of clutch bush 1G is recessed at I31 to receive a sliding pawl I38 of lever a. The pawl I38 by'means of a handle I39 may be axially moved in a groove of lever 11 against the action of a spring I40 secured at one end to the pawl and at the other end to lever a, i. e. the pawl may be engaged in or disengaged from recess I31.

The mode of operation of the arrangement described otherwise is as follows:

Various methods are possible for starting the plant so as to take into account the most diversified conditions and possibilities. In the example shown in Fig, 5, the locomotive is put under steam by means of another locomotive which is already under steam, e. g. a locomotive available in the depot. The pipe Ma is connected to the corresponding compressed air line (dotted line), and the pipe 19a is connected to the corresponding steam line (dash-and-dot lines) of this auxiliary locomotive. The main tank 23 thus is under pressure via the open reversing cock 43a, the branch pipe Ma, the air-equalizing tank 21 and the pipe 26. When the cock 26a is closed, the fuel (dotted line) flows through the three-way cook 23, pipe 23, filter 3B, manometer 3! and through the jacket 32 of the heat exchanger into the float tank 33, thence through the header 35, pipe the three-way cocks 31, the pipes 36 and the valves 38 into the fuel nozzles II]. The steam flows from the auxiliary locomotive through the branch pipe 48a, pipe 49, three-way cock EI, and heat exchanger 32 into the superheater tube I2 and the spray nozzles connected thereto. This method of getting up steam is suitable wherever locomotives under steam are available.

A further method of getting the engine under steam is shown in Fig. 6. It is applicable where no engine under steam is available, but where compressed air is available for supply to the branch-pipe 43. The locomotive thus is started without steam, but solely by air and fuel. Compressed air (dotted line) on one hand flows through the three-way cook 34, branch pipe 44a. the air-equalizing tank 21, pipe 26 and cook 25 into the main tank 24 and puts the fuel under pressure. Compressed air on the other hand also flows through pipe 43 and the heat exchanger 32 into the superheater tube l2 and the spray nozzles .I I. The pressurized fuel flows into the nozzles to over a similar way (dotted line) as in the example shown in Fig. 5.

Fig. 7 shows a method of restarting the engine after an interruption of several hours, provided that steam pressure of /2 atm. is still available, but no compressed air. The compressed air required for fuel supply is produced by means of a hand pump Bila connected to the auxiliary tank Ma. The hand pump suffices for pressurizing the small amount of fuel available in the auxiliary tank 24a (dotted line) so as to attain the required fuel pressure at the nozzle Hi. The fuel flows from the auxiliary tank 24a through pipe 29a and three-way cock is into the pressure pipe 28 and thence into the nozzles l!) as in the preceding examples. At the same time, steam is supplied from boiler 39 through the three-way cock 4! and the heat exchanger 32 into the pipe 4.!) and the spray nOZZles ii. The engine thus may be started without the aid of foreign operating means. In order to facilitate this operation, the air equalizing tank should, in case of interruption of operation of the installation, be put under the full brake operatin pressure (7-8 atm.. gauge) when stopping the engine. When reaching a working pressure of about 4 atm. gauge, the locomotive piston air pump may be used for the fuel supply, where upon normal operation the installation may begin.

When putting the engine under steam, the air flaps 41 and 48 are opened and the lever b moved into clutching position. The sleeve 16 therefore is in its upper terminal position, i. e. the pins 19 are engaged in the element H and the pawl I38 and, thus, the manual regulating member G are disengaged from the control shaft '13. The slide valves of the engine are assumed to be also closed. Since there is no suction in the chimney I 4| nor in the air inlet I3, no torque acts on blade wheel l4. Fuel and steam or air respectively, now, is supplied to the nozzles in any one of the ways described, any condensate present being blown off. After opening a fuel cock, an oil-soaked burning cloth' or the like may be thrown through a door la of the fire box on the grate bed by means of a rod to ignite the fuel air mixture be ng formed.

A firing time of only half an hour approximately is needed to build up a steam pressure of about 12 atmospheres gauge. Firing also may be I accomplished by simply introducing kindlingwood into the fire box and igniting same. In normal operation of the plant the piping is connected as shown in Fig. 8. The compressed air supplied (dash line) by means of the Westinghouse-pump into the air-equalizing tank, puts the main tank 24 under pressure, whereby fuel (dotted line) flows into the nozzles iii as previously described, where it is atomized by the steam (dash-and-dot line) taken from the steam boiler 39. The locomotive slide-valves are temporarily opened during driving, so that steam escapes through the chimney l H in the direction of the arrows r (Fig. 1), which causes the flue gases to be entrained in direction of the arrows y. A subpressure thus is produced in the fire box i as well as in the air inlet it, which subpressure defines a certain entrance velocity of the air flowing into the fire box. Depending on the magnitude of said velocity, the torque acting on blade wheel M varies, which torque after overcoming the force of spring 2| is transmitted via pull element i8 onto the shaft 60 and, thus, onto the first converter A, where it causes a corresponding rotation of cam 62. The latter is so designed that the follower 63 transforms the quadratic increase in the control movement of the device into a linear increase so that pointer 33 of the indicating device is set in proportion to the air velocity through intake l3, i. e. in accordance with the rate of inflowing air. Such rotation is transmitted via clutch B to the control shaft 73 and via the adjusting mechanism 0 onto the second converter D. The cam m9 of the latter is shaped so that not the entire linearly proportional control movement-which, owing to the proportional stroke of the valves I23 produced thereby would give rise to a rate of fuel flow through the valves 38 not in proportion to the rate of air flow through intake l3-is transmitted onto follower I l l and, thus, onto the valve rods I2 I, but rather a control movement proportional to the rate of fuel throughput. This control movement is transmitted to the valve rods I21 via the transmission means E, and, therefore, causes an instantaneous and exact adjustment of the amount of fuel to the amount of air present. As mentioned before, this air, passes uniformly distributed through the grate bed formed of balls 6, being preheated by the latter which in operation become white hot. Any excess air desired or required for complete combustion may be adjusted by means of the flaps 41 and 48.

The fuel flowing from the nozzles l0 and being atomized by the steam flowing from the nozzles II, is raised above the grate during its combustion by the inflowing air stream, thus producing a good and uniform intermixing of the flue gases and of the fuel-air mixture respectively. By correspondingly arranging the balls 6 in the front portion of fire box I, for example as shown in Fig. l, the direction taken by the flue gases may be biased toward the flue outlet pipes lb.

It follows from the above that the rate of fuel passing into the nozzles l0 and, thus, into the furnace, at any moment, accurately corresponds to the air available in the fire box, even when the flow conditions change abruptly as mostly happens in such locomotive and ship furnaces. In this way, the fuel-and-air mixture required for complete combustion is attainable.

When another fuel having a different viscosity is used, or when the viscosity of a given fuel varies in operation, which variation for example may be read from manometer 3| by virtue of the varying steam generation, the lever 0 may for example be moved on a scale in a slot of casing 2i! in accordance with a given table of settings. The lever 0 thereby is freely rotated on sleeve 93, and the toothed segment "16 via toothed flange I05 moves the slide lill on the guides I64 and, thus, also the rack 99. This causes the pin 98 to move in slot 9! of toothed segment 9i, whereby the transmission ratio between control shaft it and second converter D may be varied within the limits defined by the extent of radial slot 91. This mechanism C, when using a gaseous fuel, may be used in a similar manner in order to compensate for any variation of a variable for example of the fuel temperature.

When it is desired for any reason, to dispense with the automatic control of the fuel valves, the clutch B may simply be disengaged by means of lever 19. The lock openings 86 and $0, which are adapted to coact with pin of pawl 84, are spaced from each other so that the downwardlybent ends of the fork arms 83 of lever b in the engaged position of said lever, no longer rest on flange 18 so as to eliminate any disturbing frictional resistance between said parts; Prior to disengaging the pins 19, the-lever a and thus the pointer I34 may be set according'to the momentary position ofpointer- [33. The pawl 536, therefore, is positioned exactly underneath the recess I31, so-that the two elements 138 and 31 on declutching are engaged to each other. However, when on declutching the pawl 138 is withdrawn by means of lever 139, the regulating member G may also be adjusted after declutching. Due to suchdeclutching, the control shaft 73 and thus also the valverods I2 lthen may be manipulated independently of blade wheel M.

When, in operationof the plant one or more fuel nozzles are-blocked by dirt and the like, such nozzle or nozzles-by means of the appurtenant three-way cock 3! may be disconnected from the fuel line 34 and connected to the steam line 49 without interrupting the operation and without appreciable change of the fuel feed, so that the said nozzle or nozzles and valve 38 may be cleared by steam subjected to the full boiler pressure. Such, clearing, which is accomplished by-simply turning the cock 3?, is very effective and requires only a few seconds. Even when a plurality of nozzles are simultaneously cleaned in this manner, thefiame in the fire box will not be extinguished dueto the white-hot balls 6.

It follows from the description that all possible and necessary precautions have been taken in order to ensure a positive and optimum operation of the plant, even in-case of different and rapidly changing operating. conditions. It further will be appreciated that when converting a steam engine originally built for the use of coal, only the windbox (equipped with the grate, the combustion unit and the blade wheel) has to be attached underneath the fire box in lieu of the ash box. After installation of the control'casing and the piping system which comprises relatively few and simply mountable elements, and after establishing the necessary connections of the pipes and the pull elements, the plant is ready for operation. When the plant later has to be reconverted to coal-firing the piping which requires only little space, and the control pillar may be left in place, since they do not in any way impair the operation.

It is to be noted that studs 3 already present on the fire box I, are used for securing the wind box 2, and thus there is no need for providing new bores and connections on the fire box, which otherwisewould contribute to a reduction in the strength of the fire box.

What I claim is:

1. In a fluid-fuel furnace structure for steamdriven vehicles having a fire box including a grate, a burner system for injecting atomized fuel into the fire box, a steam producing system for cooperation with said burner system, and an exhaust system for exhausting combustion gases by the vehicle waste steam and thereby creating a suction effect in said fire box to suck air into the latter, the combinationcomprising a general air intake conduit positioned below said fire box, means positioned in said general air intake conduit and operable to vary the effective crosssectional area thereof, a plurality of superposed layers of balls made of refractory material disposed on said grate to afford a constant and uniform air resistance therethrough, means disposed in said intake and responsive to a torque produced by the velocity of the air flowing upwardly through the intake and varying in direct relation to the variable suction effect created by the vehicle waste steam exhaust system, a first converter adapted to receive from said means a control movement proportional to the square of the air velocity in the said intake and to convert the said movement into a control movement linearly proportional to said air velocity, a clutch adapted to receive the latter control movement, a control pillar in form of a casing, a manually operable regulating element disposed in the latter, a control shaft disposed in said casing and alternatively connectable to said means or said regulating element, a device operatively connected to said first converter for indicating the linear- 1y proportional control movement thereof, an adjusting mechanism connected to said shaft to vary the control movement thereof proportionally to any variation in the viscosity of the fuel, a plurality of fuel valves included in said burner system, a second converter connected with said adjusting mechanism for converting the control movement thereof into a control movement proportional to the rate of fuel flow through said fuel valves, means for transmitting the last-mentioned control movement to said valves, and means included between the steam producing system and the burner system to deliver steam under pressure to said fuel valves to clean the same and to be mixed with the fuel for atomizing the same.

2. A furnace plant as set out in claim 1, in which closable flaps are disposed between the grate and the said torque-responsive means, a lever mounted on said casing, and pull elements connected between said lever and flaps, said flaps through operation of said lever being operable to vary the cross-sectional area of said air-intake.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 702,529 Best June 17, 1902 779,985 Alwood Jan. 10, 1905 1,295,077 Stewart et al. Feb. 18, 1919 1,377,308 Buerger May 10, 1921 1,599,137 McLean Sept. 7, 1926 2,104,221 Colston Jan. 4, 1938 2,165,182 Luhrs July 4, 1939 2,228,769 Klinker Jan. 14, 1941 FOREIGN PATENTS Number Country Date 104,045 Australia June 9, 1938

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