US2027942A - Combustion control means - Google Patents

Description

Jan. 14, 5 5 WEEKS COMBUSTION CONTROL MEANS Filed July 5, 1932 5 Sheets-Sheet l km W WM A

mm 9 E Jan, 14, HOBO.

COMBUSTION CONTROL MEANS s. 8. WEEKS Filed July 5, 1952 5 Sheets-Sheet 2 Jan... M, 1%.. S 5, WEE I 2mm COMBUSTION CONTROL MEANS Filed July 5, 1932 v 3 Sheets-Sheet 3 M H i /ai /ama Patented Jan. 14, 1936 UNITED STATES ATENT OFFICE 4 Claims.

This invention relates to combustion control means. More especially it relates to means for controlling fire conditions in predetermined steps rather than by a gradual increase or decrease and in particular the invention has to do with improved adjusting means for a fuel regulator and a draft compensator associated therewith.

It is an object of this invention to provide in connection with automatic fuel controlling apparatus which functions on the step-by-step principle, improved adjusting means which enable separate adjustments of any one of the step actions to be made for that step alone without affecting the firing conditions of any other step, albeit it is a feature of the invention to provide for the simultaneous adjustment of all steps if that be desired.

It is also an object to provide in connection with a draft compensator which operates on the counterbalanced damper principle, novel means for automatically changing the counterbalance of the damper in accordance with the draft conditions desired for each step effected by the fuel regulator.

It is a feature of the invention that the fuel supply is regulated by a single control valve and that the same actuating means which regulate the movements of this valve also effect the automatic adjustment of the draft compensator and in such manner that an increase of draft through the furnace or boiler will take place before an increase of fuel supply and a decrease of said draft will occur after the fuel supply is cut down. This feature insures most favorable conditions for complete combustion during the change-over from one step to another.

The invention is herein particularly shown in its application to a liquid fuel system but this is merely illustrative of the principles involved and it is to be understood that these principles may be applied to other automatic firing apparatus and that it is intended to cover by suitable expression in the appended claims whatever features of patentable novelty exist in the invention disclosed.

In the accompanying drawings:

Figure 1 is a front elevation of a boiler installation comprising apparatus embodying the present invention;

Figure 2 is a side elevation of the upper portion of the boiler;

Figure 3 is a side elevation, in section as on line 3-3 of Figure 1, of the draft compensator;

Figure 4 is an elevation of the improved regulator;

Figure 5 is an elevation of a portion of this regulator showing the relative positions of the parts when a minimum fire is desired;

Figure 6 is another elevation in section of portions of the fuel regulator showing the relative positions of the operative parts when a medium fire is desired.

Figure '7 is a side elevation of the draft compensator showing its adjustment corresponding to the position of the regulator shown in Figure 6; v

Figure 8 is still another sectional elevation of portions of the regulator, when the parts have been shifted for maximum fire conditions; and

Figure 9 is another side elevation of the compensator adjusted to correspond with the position of the regulator seen in Figure 8.

Referring more particularly to the drawings Figures 1 and 2 show a boiler l (which may be one of a battery) having a steam dome or header 2, an uptake flue 3 and fluid fuel burners 4 of any desired construction. A master controller of the type disclosed in United States Letters Patent 1,197,053 is connected to the steam header by pipe 5 and has a controller unit 6 (6') for each step or fire condition to be established besides the lowest or minimum fire condition. For the purpose of this case the apparatus disclosed is capable of producing three different fire conditions-to be hereinafter termed minimum, medium and maximumbut it is to be understood that any number of steps or different fire conditions from two up may be attained by adding additional units. The controller unit 6 is adjusted so that when a predetermined steam pressure occurs it will act to bring about the estab- I lishment of the medium fire condition and its companion unit 6' is adjusted to respond to a different steam pressure to produce the maximum fire condition.

The controller units 6, 6' are connected to a fluid pressure supply line I and to a waste line or open drain pipe 8. Each unit 6, 6' is also connected by pipes 9 and I0 respectively, to an improved regulator II which embodies the novel fuel adjusting means of this invention. In pipes 9 and ll] are restriction valves 30, and lila by which the flow of fluid pressure to the regulator may be adjusted.

This regulator (see Figures 3 and 4) has a single control valve I2 of the piston type movable in an open ended cylinder l3 provided in the valve body. In the wall of this cylinder is a triangular-shaped opening M, with vertex downward, which, when opened by the piston, establishes connection between the main fuel supply line I5 and the pipe l6 leading to the burners 4.

The piston valve is acted upon from below by a coiled spring H which constantly urges the valve upward, or in other words, tends to open the valve by uncovering more of the triangular port M. The upper end of the valve stem l8 has an adjusting nut 19 thereon which rests against an adjusting screw 28 associated with a cross-bar 2|.

This crossbar has an extended hollow hub Zia which telescopes a tubular post 22 depending from the frame of the regulator. A coiled spring 23 interposed between the frame and crossbar tends always to move the latter toward the adjusting nut E9 on the stem of the piston valve, its downward movement being limited by its engaging the head 23a of the adjusting screw 26. This screw extends into the hollow of the tubular post 22 and has at its inner or upper end a nut 24 which rests on an internal annular shoulder 22a of the post. The post andhub are suitably slotted, as at 221) and 2H) respectively, to accommodate a screw 25 which extends through the slots into the nut 24 and prevents rotation of the latter while permitting axial movement thereof. By turning the screw 20 the downward limit of the crossbar can thus be adjusted as desired.

The arms of the crossbar are provided with threaded holes Zlc, 2| (1 into which are threaded duplicate adjusting screws 26, 26'. Each of these screws is associated with an assembly which is identically like the other, and therefor but one of these assemblies will be described in detail. It is to be understood, however, that parts having a reference number with a prime added are identically like other parts having the same number without the prime.

Attached to the frame, in axial alignment with the adjusting screws 26, 26 are cylinders 21, 21 to whose upper ends are connected the pipes 9 and i respectively leading from the controller units 6, 6. The lower ends of the cylinders are vented through pipes 28, 28 to any convenient drain. Each cylinder is provided with a piston 29, 29 from which extends upward through a suitable packing gland 39, 3G a hollow piston rod 3|, 3!. Each piston head has an axial bore into the bottom end of which is threaded a hollow screw 32, 32'.

In the hollow of each piston rod is another rod 33 (33) which has an enlarged upper end 33a (33's and extends downward through the screw 32 (32') through a packing box 34 (34) and through the adjusting screw 26 (26) being provided at its lower end with a nut 33b (33b).

When there is no appreciable demand for steam from the boiler both controller units 6, 6 will be set so that the fluid pressure supply is connected through pipes 9 and Ill with the cylinders 27, 21. Under such conditions, the pistons 29, 29 are both held at the bottom of their respective cylinders by the fluid pressure therein. The crossbar will be in its lowermost adjusted position, seen in Figure 4, and the fuel control valve l2 will be open only wide enough to maintain the minimum fire condition in the boiler. If now a load comes on the boiler which causes a drop of pressure sufficient to actuate the con troller unit 6, a valve thereof will be shifted to shut off the fluid pressure from pipe 9 and connect the latter with the waste line 8. The release of pressure thus effected from cylinder 2'! will permit its piston to move to its uppermost position, as seen in Figure 6, where it will remain until the fluid pressure is again admitted to the cylinder. As the piston moves upward, no change of the fuel valve !2 occurs until near the end of the piston stroke, but then the screw 32 engages the enlarged end 33a of the rod 33 and lifts the latter to bring its nut 3312 against the head of adjusting screw 26. Movement of the latter carries with it the crossbar and as this moves upward, the piston valve follows under the influence of spring ll, thus opening a greater portion of port M. The added fuel thus permitted to pass to the burner establishes the socalled medium fire condition which of course effects a greater generation of steam in the boiler. If the steam pressure as thus increased is sufl'icient to carry the load, the parts will remain as shown in Figure until either the load falls off or more steam is demanded.

If the load increases the other controller unit (5 responds to shut off the fluid pressure to pipe l3 and connect it with the waste 8. As just described, this permits piston 29' to move upward and near the end of its stroke to effect further upward movement of its rod 33 and the cross bar 2| with consequent further opening of the port M, as shown in Figure 8. This will establish the maximum fire condition and ought to result in a generation of steam in excess of the increased demand, it being assumed that this latter demand is not the maximum of which the boiler is capable of supplying. If the load is equal to or in excess of the maximum capacity of the boiler, the parts will remain as seen in Figure 8 with the valve in its most open position.

In practice, however, an excess load is most unusual and the normal maximum load can be more than satisfied by the boiler when the maximum fire conditions prevail. In fact, it is a feature of the invention that the regulator can be particularly adjusted to give a maximum fire condition which will exceed the maximum load normally encountered. This is accomplished by adjusting the screw 26 so that when its rod 33' is raised by the piston as the crossbar will be lifted and the piston valve opened so as to supply sufficient fuel to keep the fire at the intensity necessary to exceed the said load. Thus the invention provides for the individual adjustment of the fuel control valve in accordance with the demand of the maximum load.

If the load is reduced below the maximum and an excess of steam thereby results, the controller unit 6 will respond to again connect pipe [0 with the fluid pressure supply and thus cause piston 29 to descend to its lowermost position. As it starts downward, the rod 33' travels with it under the influence of spring 23 as exerted through the crossbar and screw 26' on the nut 33b at the end of the rod. When the crossbar reaches the position where the adjusting screw 26 engages nut 33b on the other rod 33, the bar comes to rest. Thus the piston valve is returned to its intermediate position corresponding to medium fire conditions. Here again the invention provides for individual adjustment to obtain a preferred medium fire condition. By adjusting the screw 25 the position of the crossbar and necessarily the piston valve !2 can be determined as desired.

If the demand for steam is further reduced and the medium fire condition no longer needed, the controller unit 6 thereupon connects pipe 8 with the fluid pressure supply thus bringing about the downward travel of piston 29 and a further closing of the fuel supply valve l2. To adjust the latter fora desired minimum fire condition, screw 20 can be turned in its nut 24 to vary the relative position of the screw with respect to the frame. Adjustment of this screw 20 also changes the positions of the crossbar and the two adjusting screwsZB, 285' but note that no change is made in respect to rods 33 and 33 because of the lost motion provided between screws 26, 26 and nuts 33b and 33'b respectively. And when these latter nuts are again raised by subsequent operation of the pistons, they will again set the piston valve in the same position as before described for medium or maximumfire conditions. Thus it is that the invention provides for the individual or separate adjustment for each fire condition without any effect on the settings for the other fire conditions.

If it should be determined that the piston valve shouldbe opened wider for all fire conditions, as when the burner begins to clog up or a different fuelis used, this may be accomplished by simply adjusting the nut IS on the end of the piston valve stem l8. This varies the position of the valve I2 with respect to the crossbar 2| so that when the latter is positioned by the operation of the pistons the supply valve will be opened more or less in accordance with the setting of the nut I9. Thus the invention provides for the simultaneous adjustment of all fire conditions if desired.

In well equipped boiler installations today it is desirable to have what is known as a draft compensator. for counteracting the varying effects in the air flow caused by conditions beyond the control of the apparatus. For example, changes in atmospheric conditions, change in flue gas temperature, changes in the number of boilers operating or in the number of burners used all influence the draft and of course the wind factor is a variable that is almost continually in action. The usual draft compensator is a nearly counterbalanced-damper controlling what may be called an auxiliary'opening into the gas passage of the boiler. This damper may be on the supply side of the fire box when forced draft is used or in the discharge flue if natural draft or a blower on the discharge side is relied upon for induced air flow through the furnace. These compensators may be set or adjusted initially for any desired air flow through the furnace and, so long as this particular air flow is maintained, are generally satisfactory. But if a different air flow through the furnace is desired and the compensator is not again adjusted. for this changed air flow, the compensator will at once become a source of trouble rather than a helpful device. In other words, if the compensator is initially adjusted for the air flow through the boiler when a minimum fire is maintained, it will act as a true compensator only so long as this air flow continues. If the fuel supply is increased to produce a medium or maximum fire condition, it is necessary to increase the air flow through the furnace correspondingly. If this is attempted with the ordinary compensator, the latter opens wider and the result is that more air is taken in from the outside beyond the boiler, or more air is deflected out of the air passage if the compensator is between the forced draft blower and the furnace. In either case the desired increase of air flow actually through the boiler is not accomplished and incomplete and ineffective combustion results.

The present invention avoids such an undesirable result by providing for the automatic adjustment of a compensator in keeping with the air flow change accompanying a change in fire conditions. Moreover, it effects the automatic adjustment of the compensator in a manner most favorable to the changing fire conditions.

The upper ends of the piston rods 3|, 3! are I connected to chain 35 which extends through casings 36, 36 at the top of the regulator. This chain is provided with adjustable stops 31, 31 which engage the ends of its respective casings and enable the stroke of each piston to be adjusted. Chain 35 passes over a sprocket 38 journaled at the bottom end of a rod or cable 39. The latter is attached to a lever it on a shaft M which also carries another lever 42. These levers are of different lengths so that the linear travel of the end of the shorter lever may be multiplied in the linear travel of the end of the longer lever. To the latter is attached another chain or cable 43 which passes around a grooved pulley A4 and leads to levers 45, 56 mounted on the compensator.

This draft compensator has a simple damper 41 mounted near its ends on a horizontal axle 48 at the lower edge of an auxiliary opening 49 into the flue 3. (See Figure 3.) Attached to the damper proper is a plate 553 having an arcuate slot 59a concentric with the axle 48. The levers 55, 46 and a third lever 5| are mounted rotatably on the axle 48 and are so disposed that they may swing beside the plate 50. In the slots Ella are stop pins 52, 53, 54, one for each of the levers. The latter are 'providedwith weights 45a, 35a and Ella respectively which are manually adjustable along the said levers to vary the counterbalancing effect of each on the damper proper. The latter with its plate and stop pins are first counterbalanced by a suitable weight 52 and then stop pin 54 is adjusted so that when lever 5i rests against it, the weight of the lever will counteract the force of the air draft on the damper when the latter is open approximately 45 as seen in Figure 3. This is the desired position of the damper when a minimum fire condition prevails. If the flue draft fluctuates, the damper swings in or out to let in more or less air through opening G9 and thus keep the draft through the boiler substantially constant.

If now the load on the boiler demands a medium fire condition the regulator acts as heretofore described to permit piston 29 to rise and open the fuel valve to admit more fuel to the furnace. This necessitates an increase of air flow through the furnace and this the invention insures :by automatically adjusting the draft compensator.

As the piston 29 moves upward through its stroke sprocket 38 is also drawn upward by the cable 39 acting under the combined influence of a weight 55 on shaft M and the weighted levers 45 and 46. But the sprocket will move upward only one-half the length of the piston stroke because while the chain 38 on one side of the sprocket is moving upward, the other end of the chain remains still, and so the sprocket can travel upward only one-half the travel of the piston. This upward movement of the sprocket and rod allows shaft 4| and levers 4i] and 52 to turn sufliciently to lower the weighted levers s5 and 46 so that lever 46 rests on its stop pin 53 on the damper plate. This at once adds more counterbalance against the air flow through opening 49 and causes the damper to swing to the position indicate-d by the dot and dash line pl in Figure 3 and actually shown in Figure '7. Accordingly, less air will be drawn in through the opening and more air will pass through the boiler.

Likewise if the other piston 29 is raised to establish maximum fire condition, its piston rod moves upward and again the sprocket ascends a distance equal to one-half the travel of the piston. But this is enough to allow the third weighted lever 45 to rest on its stop pin 32 and thus impose another additional counterbalance on the damper. This causes the damper to swing to the position indicated by the dot and dash line 102 in Figure 3 and shown in Figure 9. With the damper thus more nearly closed still less air will enter through opening 49 and still more will pass through the boiler.

It is of course understood that in adjusting the weights 45a, 46a and am on the respective levers each will be set so that its counterbalancing effect on the damper will correspond with the desired air fiow through the fire box, but after once so set, the levers themselves will be automatically lifted or lowered as the apparatus operates to establish the desired fire condition. And it is to be noted that when a piston rises to increase the fire its respective lever is lowered to its stop pin before the control valve is actually opened to supply more fuel. This is so because as soon as the piston starts to move upward its counterbalancing lever begins to descend and will have reached the stop pin before the contact screw (32, 32') in the piston head has engaged the shoulder on the rod (3|, 3|). Conversely when either piston moves downward to reduce the fire condition, the control valve is shifted to its more closed position before the respective weighted lever is lifted clear of the stop pin. Thus it is that the automatic adjustment of the compensator occurs before the valve is opened wider and after it has been partly closed.

Where rather violent and extremely sudden changes in the flue draft are apt to occur, it may be beneficial to employ a light brake on the compensator such as the dash pot 56 shown in Figures 1 and 2. This is a simple cylinder with a piston therein whose rod 51 is connected by a link 58 and crank 59 to the axle shaft 48. The opposite ends of the cylinder are connected by a bypass 60 of restricted size which enables the fiuid in the cylinder to be transferred from one side of the piston to the other with retarding or braking effect on the damper movements.

Although the drawings disclose but a single boiler, it is to be understood that the control apparatus as a whole may be applied to several boilers. Each would have its own valve control unit and its own compensator, but all might be connected to the same steam actuated master controller in which event the latter would receive its pressure influence from a common steam header into which the several boilers would be connected. Thus the control valve units of each boiler and their respective draft compensators can be adjusted in accordance with the characteristics of the individual boiler, the apparatus being set for each fire condition as respects both the fuel feed and the desired action of the draft compensator.

I claim:

1. Combustion control means for a boiler comprising, in combination, mechanism for regulating the feed of fuel to the furnace; apparatus for compensating the gas flow through the boiler comprising an opening in the passage for said flow; a free-swinging counterbalanced damper in said opening movable in response to changes of pressure of said gas; and means actuated by the said regulating mechanism for changing the counterbalance of said damper in accordance with the regulation of said fuel.

2. Combustion control means for a boiler comprising, in combination, mechanism operating on the step-by-step principle for regulating the feed of fuel to the furnace; apparatus for compensating the gas flow through the boiler comprising an opening in the passage for said flow; a free-swinging counterbalanced damper in said opening movable in response to changes of pressure of said gas, and means for changing the counterbalancing weight of said compensator with each step in the regulation of the fuel.

3. Combustion control means for a boiler comprising, in combination, mechanism for regulating the feed of fuel to the furnace; a draft compensator comprising an opening in the passage for gas flow through the boiler, a free-swinging counterbalanced damper in said opening movable in response to changes of pressure of the gas flowing in said passage; means actuated by the said mechanism for changing the counterbalance of said damper in accordance with the regulation of fuel; and braking means associated with said damper.

4. Combustion control means for a boiler comprising a draft compensator having a free-swinging counterbalanced damper movable in response to variations in pressure of the gas flowing through the furnace; and means for changing the counter-weight of said damper to correspond with predetermined changes in the fire conditions of said boiler. 55

SHIRLEY S. WEEKS.

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