US1338927A - Controlling combustion by flow and pressure - Google Patents

Description

J. M. HOPWOOD. CONTROLLING COMBUSTION BY FLOW AND PRESSURE. APPLICATION FILED S EPLZO, 1918.

1,338,927. Patented May 4, 1920.

2 SHEETS-SHEET l- FIBJ- I WINVENTOR J. M. HOPWOODJ CONTROLLING COMBUSTION BY FLOW AND PRESSURE. APPLICATION FILED SEPT-20, 1918.

1,338,927. P tented May 4,1920.

2 SHEETS-SHEET 2- ITNESSES INVENTOR MLUBM JOHN M. HOPWOOD, OF DORMONT, PENNSYLVANIA.

CONTROLLING COMBUSTION BY FLOW .AND PRESSURE.

Specification of Letters Patent.

Patented May 4, 1920.

Application filed September 20, 1918. Serial No. 254,979.

To all whom it may concern: 7

Be it known that 1, JOHN M. Horwooo, residing at Dormont, in the county of Allegheny and State of Pennsylvania, a citizen of the United States, have invented or discovered certain new and useful Improvements in Controlling Combustion by Flow and Pressure, of which improvements the.

following is a specification.-

The invention described herein relates to a method of controlling combustion in fur naces of generators of steam, etc., and consists generally stated in controlling the feed of fuel and air for combustion to a furnace by and in accordance with changes in the components of the total pressure of vapor flowing from the generator, 6. 6., changes in the rate of flow of fluid from the generator and with changes of the normal working pressure of such fluid, and controlling the escape of products of combustion from the It is oneof the advantages of the methoddescribed herein that regulation is effected by primary results, i. 0., a change of rate of use and a change in static pressure. While regulation can be and is in practice effected by and in accordance with each of the above stated resultants of use, it is also effected by both, one supplementing the other.

vIn the accompanying drawings forming a part of this specification, Figure 1 is a diagrammatic view showing a boiler-in combination with regulating mechanism suit able for the practice of the invention claimed herein, and Fig. 2 is a similar view showing combinations applied to a plurality of boilers.

In the practice of the invention the stack da per 1 is connected by any'suitable means sudli for example as the cord2 passed around guide pulleys to a suitable mechanism op-' erative by and in accordance with changes of pressure of gases in the furnace'3 of the than by a secondary boiler. It is preferred to employ mocha nism of the construction shown and described in an application Serial Number 254,97 5, filed of even date herewith. The cord is connected to a frame 4 carried by the rod of'the piston in the cylinder 5, as shown and described in said application, the flow of fluid pressure to such cylinder being controlled .by a pilot valve which has its movable member connected to an arm ofa rocking shaft pivotally mounted in a rocking frame adapted to be shifted to move the movable member of the pilot valve by means of a lever provided with inverted cups extending below the level of the water in a" tank 6. A nozzle connected by a pipe 13 to the furnace extends'up above the level of the water in one of the cups so that the latter with its lever 10 will be shifted by and in accordance. with changes of pressure in the furnace. ()n the rock shaft is secured a second'arm which is connected by a link toa swinging member- 15 carrying atits upper end a mounted shoe through which slides a bar 16 adjustably secured to the frame. This mechanism is adapted to shift the rocking shaft in the frame so as to close the valve after a predetermined movement of the piston in the cylinder, the-bar 16 being adjusted at such an angle to the axis of the cylinder as to move the swinging member after thedesired movement of the piston. It is characteristic of this arrangement that the movement of the frame 4 is incremental and hence the damper in the stack will be shifted incrementally and not from full open to closed and vice versa.

The feed of fueland of air is controlled by and in accordance with changes in rate of flow of steam in the outlet pipe C from the boiler and also by changes in static pressure of the steam. The mechanism pre ferred for effecting this regulation is that shown and described, in the application .above referred to and consists of two motor diaphragms one of which is adapted to be shifted solelyby 'dynamic pressure in the steam flowing through the outlet pipe, the chamber above such diaphragm being connected to the outlet pipe by a Pitot tube arranged in the outlet pipe of the boiler. The other diaphragm is subjected on one side to a yielding pressure which will be at all times substantially equal to the static working pressure in the boiler and to a pressure on its opposite side maintained in t e chamber intermediate the two diaphragms, said chamber being connected by a pipe 12 to the boiler in such manner that any change of pressure in the boiler will be transmitted to the second diaphragm. As described in said application, the upper diaphragm is connected in a suitable manner to a pivotally mounted frame in which is mounted a rocking shaft provided with two arms, one connected to the stem of the movable member of a pilot mechanism and the other to a swinging member 21 which carries at its upper end a pivotally mounted shoe slidably engaging a bar 23 carried by a frame 24 and adapted to be adjusted to an angular position relative to the axis of the fluid pressure cylinder 25. This cylinder to which the flow of fluid under pressure is controlled by the pilot valve,

is provided with a piston connected by its rod to the frame 24. On a change of position-of the upper diaphragm, consequent on a change of flow of steam in the outlet pipe,

the rocking frame will be shiftedthereby opening the pilot valve to admit fluid sure to one or the other end of the fluid pressure cylinder 25. As the frame carried by the piston of this cylinder is moved, the angularly arranged bar 23 will shift the swinging member 24 and the movement of the swinging member will through the link and second arm of the rocking shaft of the frame, close the pilot valve. The second or lower diaphragm is suitably connected to an arm of a bell crank lever 26 to the other arm of which is pivotally connected a lower end of the swinging'member 21 so that by the shifting of the lower diaphragm theswinging member will be so shifted that operating through the-rock shaft the movable member of the pilot valve mechanism will be moved to open position thereby admitting pressure to one or the other end of thecylinder. After a predetermined movement of the piston and frame 24 carried thereby, the swinging member 21 is shifted by the angular-1y arranged bar 23 in such .direction as to close the pilot valve. The frame carried by the piston in the fluid pressure cylinder 25 is connected by any suitable means such as a cord 27 to a valve or damper 28 arranged in the conduit 29 through which air is supplied to the under side of the fuel bed in the furnace. The feed of fuel is controlled by the movement of the same frame 24 operating through a valve mechanism 31, the movable member of which is connected by a lever 30 to the frame. This valve mechan sm is preferably of the roto-reciprocating type as shown and described in Letters Patent No. 1,247 ,217, dated November 20th, 1917 and consists of a shell connected to a fluid pressure supply by a pipe 36 and hav ing an annular passage connected to the cylinder of the stoking mechanism by the pipe 35. Within the latter is arranged an 1npres- .herein that the rate of verted cup-shaped valve connected by its stem to the lever 30 operated by the frame. On the movement of this valve by the lever, the port in the valve 'and that leading from the annular chamber are connected -or brought into register but the amount of reg-' ister of these ports is controlled by rotary movements of the 'valve, such movement being effected by an angularly arranged bar carried in an adjustable frame 34 and having a sleeve or shoe slidable there along and connected by an arm 37 to the stem of the valve, all as described inthe patent referred to. The outlet from this valve is connected to the piston of the stoking mechanism em ployed for feeding the coal to the furnace.

When applying the invention described herein to a plurality of boilers as shown in Fig. 2, the stack dampers 1 and 1", etc., are connected respectively to the furnaces 4 and 4 of regulating mechanisms operative by and in accordance with changes of pressure of the gases posterior to the fuel beds in the furnaces 3, 3', etc, of the boilers forming a group. In such an installation the feed of fuel and the flow of air for combustion is controlled by and in accordance with changes both in the rate of flow of steam along a conduit connected to all the boilers of the group and changes from the working pressure of the steam. As shown in Fig. 2, the operations of all the stoking mechanisms are controlled by the frame 24' of the regulating mechanism which is operatively-connected by pipes 11 and 12 to the common steam conduit C. It will be understood that any suitable form of stoking mechanism may be employed and that connections from the frame'24 of the regulating mechanism to the stoking mechanism will be adapted to the style or type of mechanism employed. In the construction shown the stoking mech anisms are of the type operative by fluid pressure having their cylinders connected by pipes 35 to a valve mechanism preferably of the roto-reciprocating type, and by a pipe 36 to a suitable source of supply. The supply of air for combustion to the furnaces of the group is controlled by suitable means as dampers 28, 28 in the respective conduits 29, 1 15 29, said dampers being connected by a cord 27 to the frame 24 of the regulating mechanism, which as before'stated is operative by and" in accordance withchanges in dynamic and static pressures in the common 120 conduit 0.

It is characteristic of themethod described steam consumption rather than a change insteam pressure primarily controls the rate of fuel and air 125 supply, while the furnace pressure regulates the discharge of products of combustion so as to maintain uniform, at varying rates of combustion, any desired predetermined furnace pressure which may be set at a point 130 that will prevent infiltration of air into the furnace or boiler setting.

It is characteristic of the invention described herein that the operations controlling combustion, as the feed of air and the feed of fuel will be adjusted directly or indirectly to increase combustion both by an increase in the rate of flow of and drop in static pressure while an increase of static pressure and a decrease in the rate of flow, will each of them bring about a reduction of combustion.

When installing mechanisms for the practice of the invention described and claimed herein the position which the stack damper should occupy under normal working conditions is determined and the regulating mechanism is so adjusted that the predetermined or normal static pressure in the boiler will, operating through the regulating mechanism, hold the damper in such position. After such adjustment, variations in flow will cause a fluctuation of the piston of cylinder 28 from its normal position, the range of the fluctuation being proportionalto the changes in the rate of flow of steam from theboiler. In case of a change in static pressure the piston will assume another position and changes of flow will produce fluctuations of the piston relative to its new position. In other words,

' the field of movement of the piston due to changes of flow, will be largely determined by the static pressure of the steam.

As is well known, the pressure of the steam and the rate of flow of steam from the boiler are the factors which determine the horse power developed by a boiler and hence it is characteristic of the invention described herein that regulation of combustion is effected in accordance with the horse power developed.

While the invention has been described I and shown in connection with apparatus for the generation of steam, it will be apparent that the improvements can be used for controlling combustion with vapor generators generally.

I claim herein asmy invention: 1. The combination of a generator of steam, having a furnace with means for controlling the discharge of gases from the furnace of the generator by and in accordance with the pressure of gases in the furnace and means for controlling the feed of fuel and air for combustion by and in accordance with the dynamic and static pressures of the fluid flowing from the generator.

2. The combination of a plurality of generators of steam, having a furnace with means for controlling the discharge of products of combustion from the furnace of each generator by and in accordance with the pressure of gases in the respective furnaces and means forcontrolling the feed of fuel and air for combustion to all the furnaces by and in accordance with the dynamic and static pressures of fluid flowing from all the generators.

3. The combination of a generator of steam, having a furnace means for supplying air and a fuel to the combustion chamber of the enerator in accordance with variations 0 pressure components of the steam flowing from the generator, means for establishing a. predetermined pressure in the combustion chamber and for automatically maintaining said pressure substantially constant under any varying rates of combustion.

4. The combination of a generator of vapor having a furnace with means for controlling the discharge of gases from the furnace of, the generator by and in accordance with the pressure of gases in the furnace,

means for controlling the feed of air to the furnace by andin accordance with dynamic and static pressure of the fluid flowing from the generator.

5. The combination of a generator of vapor having a furnace with means for controlling the discharge of gases from the furnace of the generator by and in accordance with the pressure of gases in the furnace and means for controlling the feed of fuel to the furnace by and in accordance with the dynamic and static pressure of the fluid flowing from the generator.

In testimony whereof I have hereunto set my hand.

JOHN M. HOPWOOD.

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