US1338925A

US1338925A - Controlling combustion

Info

Publication number: US1338925A
Authority: US
Publication date: 1920-05-04
Anticipated expiration: 1937-05-04

Description

J. M HOPWOOD.

CONTROLLING COMBUSTION BY FLOW AND PRESSURE.

APPLICATION FILED sEPT.20, 1916.

1,338,925. Patented M y 4,1920. I

3 SHEETS-SHEET V.

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FIE .1-

FROM BLOWER C WITNESSES INVENTOR FIE-3.2-

WITNESSES J. M. HOPWOOD.

CONTROLLING COMBUSTION BY FLOW AND PRESSURE.

APPLICATION FILED SEN-20.1918.

Patented May 4, 1920.

3 SHEETS-SHEET 2.

v Q Emil 9 INVENTOR [1.

km MAM I. M. HOPWOOD.

CONTROLLING COMBUSTION BY FLOW AND PRESSURE.

Patented May 4,1920.

3 SHEETS-SHEET 3.

APPLICATION FILED SEPT-20, 1918.

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. 254,977.

To all "Ir/ i 02a it may camera.

Be it known that I, JOHN M. I-lorwoon, residin at Dormont, in the county of Allegheny and State of Pennsylvania, a citizen of the Jnited 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 of fuel for the generation of steam or other gaseous product and consists generally stated in maintaining the products of combustion in the furnace of the generator under a suitable pressure by regulating the disz'harge of such products by and in accordance with changes in the components of the total pressure of the steam or vapor flowing from the generator, 2'. 0., with changes in the rate of flow of the generated product as steam from the generator and the variations from normal of the static pressure of such products in the generator, and also regulating the feed of 5 1 th p ly of air for combustion being.

pr1. portionalto the rate of discharge of products of combustion.

This method is well adapted to use where single unit boiler control is desirable and where gaseous or liquid fuels are employed. This method presents decided advantages in simplicity of equipment and generally satisfactory results in practice. by calibrating the air duct damper when employing forced draft to conform to the sitting of the stack damper, a predetermined furnace pressure or condition may be established, dependent upon the rating, and with the use of a fairly uniform grade and size of fuel may be successfully maintained under ordinary load variations. The fuel feed, the air supply and the escape of the products of combustion are each and all instantly and simultaneously controlled by and in accordance with flow and pressure variation in the steam outlet of each individual boiler. These incremental adjustments of the stack damper, air supply and fuel supply, are instantaneously effected in the direction of meeting the load demands irrespective of the steam pressure, but at the same time any change in the steam pressure, with constant steam flow, will bring about the necessary adjustments of the controlling means to restore predetermined normal pressure conditions, it being characteristic of the invention described herein that the mechanism controlling combustion such as the stack damper, stoking mechanism and devices controlling the feed of air, will be adjusted directly or indirectly to increase combustion both by an increase in the rate of flow and a drop of static pressure while an increase of static pressure and a decrease in the rate of flow will each of them bring about a, invention The described and reduction of combustion. is hereinafter more fully claimed.

in the accompanying drawings forming a part of this specification, Figure 1 is a view partly in section and partly in elevation showing a boiler combined with regulating apparatus adapted to the practice of the method claimed herein; Fig. 2 is a similar view illustrating apparatus for the practice of the method in connection with natural draft; Fig. 3 is a view on an enlarged scale partly in elevation and partly in section of the regulating or controlling mechanism, and Fig. i is a diagrammatic View illustrating regulating connections when cmployin g liquid or gaseous fuel.

In the practice of the invention suitable means are employed for regulating the damper 61 controlling the escape of products of combustion from the furnace and also for controlling the feed of fuel to the furnace, such means being operative by and in accordance with the variations in the rate of flow of steam from the boiler and by and in accordance with the working pressure of the steam. Air for combustion may 'be forced into the fire box or a natural draft may be used. lVhen a forced draft is employed the rate of supply will be controlled directly by and in accordance with the rate of flow of steam to the point of use and the static pressure of the steam, but when natural draft is employed, its flow to the furnace will be approximately proportional to the flow of products of combustion from the furnace, and as the escape of products of combustion is controlled by the flow and pressure of steam, the supply of air under natural draft will be also, though indirectly, under the control of the steam flowing from the boiler.

In the combination shown herein the stack damper 61 is connected by a cord or other suitable meansto a frame 29 which is connected to the piston rod of the cylinder 28. Theflow of fluid pressure to the respective ends of this cylinder is controlled by a pilot valve 25, the movable member of such valve mechanism being connected by a link to an arm extending from the rock shaft 21 mounted in a frame 20 which has a pivotal support. The frame 20 is adapted to be shifted to open the valve in the pilot mechanism by a lever 15 which is connected to one member of a double diaphragm motor of substantially the construction shown and described: in an application Serial Number 254,975 filed of even date herewith. The diaphragms of the motor are arranged intermediate a cap pi ce 2 which is preferably integral'with the bed plate 3, and a shell 4, the, diaphragms being spaced a substantial distance apart .by an annular block 5. The chainberabove the upper diaphragm is so connected by a pipe 11 to the outlet pipe (J from the boiler that, there will be maintained in such chamber and operative upon the upper diaphragm a pressure equal to the static pressure of the steam plus or minus the dynamic pressure of the steam flowing throughithis pipe dependent upon the arrangement of the Pitot tube within the pipe C.

The chamber intermediate the diaphragms is connected by a pipe 12 to the outlet pipe C insuch manner as to maintain within suchintermediate chamber a static pressure equalto that of the steam flowing along the outlet pipe 0. Within the shell -1lis arrangedan inverted cup 13 and the shell. is so filled with a fluid as to form an air space at'the upper end of the (up. This body of air is maintained at a pressure substantially equal to. the normal working pressure of the steam and in order to establish such pressure within the shell, thepipe is connected by a valvedpipe 141- with the shell and prior to the apparatus being started into op tionthe valves in the pipe l-el are opened while steam is flowing along the outlet pipe or, pipe 12 may be connected directly to the boiler, so as to subiect the air cushion in the shell to the pressure desired and when the pressure has been attained, the valves in the bii'anchggl l are closed so that thereafter the underside of the lower diaphragm will be subjected to a yielding pressure substantially equal to the normal. static pressure of the steam.

In case ofv a variation in the rate of flow of steam from the boiler. the upper diaphragnravill be shifted in ac-ordiincc w i such variations, thereby through the .lGVP/I 15,-shifting the frame it) to so move the pilot valve 25 as to admit steam to the upper or lower end of the cylinder 28 (leper out on the direction of the change of rate or flow of steam in the outlet pipe, 2'. 0., whether the rate of flow is increased or decreased By the movement. 0% the pilot valve fluid pressure admitted tothe cylinder and the pis ton and frame 29 shifted. By this movement of the frame .29 an angularly arranged. bar is shifted along a shoe pivotally mounted on the upper end of a swinging member 26. By the movement of the bar through the shoe this swinging member is shifted which in turn will so shift thearm which as before stated is on the rock shaft with the valve shifting arm 22, as to close the previously opened ilot valve and stop further movement of the piston. is will be seen in Fig. 8, the swinging member has its lower end pivotally 'lOUIllLPAl on the arm of the bell crank lever Bl which has its opposite arm connected to the lever 16 adapted to be shifted by a movement of, the lower diaphragm on a change of static pressure in the intermediate chamber. .:s the pressure in this chamber which follows that of the out-- flowing steam changes the lower end ofthe swinging member 26 will be swung-in or out and thereby through the link arm and thereby open the on the movement of the piston in the cylinder 26 following the opening of the pilot valve. the rod 32 will move through the shoe 33 and shift the Li per end of the swinging member in a direction to effect a closing of the pilot valve through the link 2. and arm rate of How or the static pressure of the steam flowing through the outlet pipe (.3 chan esv there will be a corresponding shifting o the frame 29, but this movement will be simply incremental, the extent of movement being dependent upon the angular arrangement of the rod 32 with reference to the axis of the cylinder. As hereinbefore stated, the frame 29 connerted by a cord 60 to the stack damper 61 so that the mere mental movement of the frame 29 will cause a corresponding incremental movement of the stack damper, thereby permitting an increase or decrease of the rate of flow of products oi. combustion from the furnace.

The feed of. fuel to the furnace is controlled by a suitable mechanism whose oppilot valve oration will be regulated by the movement of the frame 29, the connections extending from the frame being dependent on the characterof the stoking mechanism employed. ll hen employing a steam opera-ted stoking mechanism. (36, a roto-reciprocating valve meeluinism such. as described in Letters Patent No. 12%? ,217 dated November 20th, 191.? is preferably employed. This valve mechanism consists generally stated in-an external shell 67, having an annular chamber 68 connected by the pipe 69 to the cylin der of the stoking mechanism, the shell 67 being connected by a pipeTO, to a suitable soiirre of supply. l vithinj the shell is arranged an inverted cupTl secured tov a r0d72 passing nirough the shell and provided with ports adapted to be moved into and out of 2? shift thev Thus it will be seen that where the.

register with the ports leading from the annular chamber when the cup shaped valve the valve is effected by the frame 29 operating through the lever 73 connected to the frame and to the lower end of the valve stem. The rotary movement of the valve is effected by connecting the upper end of the valve to a sleeve T l slidable along a rod 75 carried in a frame '76 which can be adjusted to assume an angular position relative to the axis of the valve shell. As the movement of the valve of the roto-reciprocating Inechn nism is effected by the frame 29 it follows that the feed of fuel is controlled by and in accordance with changes in the rate of flow of steam through the pipe U and changes of pressure of the steam. As here inbefore stated, either a forced or a natural draft may be employed for supporting combustion in the furnace as shown in Figs. 1 and 2. lVhen a forced draft is employed, a valve or damper 64: arranged in the conduit for conducting air to the furnace is operatively connected by a cord to the frame 29 so that the admission of air also is controlled by and in accordance with changes in the rate of flow and changes in the static pressure of the steam. The movements of the stack and air duct dampers are calibrated so that the inflow of air will bear a definite relation to the discharge of products of combustion so as to maintain a substantially uniform furnace pressure.

lVhen it is desired to employ a fluid fuel as oil or gas, the

valves

77 and 78 controlling respectively the flow of fluid-fuel and steam or air to the burner 79 are suitably connected to the regulating mechanism. In the construction shown in Fig. t, the operating handles of the valves '77 and 78 are connected to the cord 60 leading from the frame 29 of the regulating mechanism, said cord being also operatively connected to the stack damper 61.

lVhen 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 proportional to the changes in the rate of flow of steam from the boiler. In case of a change in static pressure, the piston will assume another po sition and changes of flow will produce fluctuations of the piston relative to its new position. In other words, the field of move ment 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 a 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 withth'e horse power developed.

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

In the practice of the invention described and claimed herein combustion is affected by any one of the following operations: the discharge of gases from the furnace, the feed of fuel to the furnace and the supply of air for combustion of fuel in the furnace, and provision is made for controlling each of said operations.

I claim as my invention:

1. The combination of a generator of vapor having a furnace with means for controlling the escape of products of combustion from the furnace of the generator, means for controlling the feed of fuel to the furnace, means for feeding air under pressure to the furnace and mechanisms operative by and in accordance with changes in the rate of flow of vapor from the generator and with changes in the static pressure of the vapor for regulating the operation of the combustion products controlling means and the fuel and air feeding means.

2. The combination of a generator of vapor having a furnace, means for controlling the escape of products of combustion from the furnace of the generator, fuel feeding means, a fluid pressure cylinder having its piston operatively connected to the damper and to the fuel feeding means, a valve mechanism for controlling the flow of fluid under pressure to said cylinder, means operative by and in accordance with changes in the rate of flow of steam from the generator for opening said valve and operative by and in accordance with changes in static pressure of the vapor for opening the valve, and means operative on a predetermined movement of the piston of said cylinder for closing the said valve.

3. The combination of a generator of vapor having a furnace, means for controlling the escape of products of combustion from the furnace of the generator, air feeding means, fuel feeding means, a fluid pressure cylinder having the piston operatively connected to the damper and to the fuel and air feeding means, a valve mechanism for controlling the flow of fluid under pressure to said cylinder, means operative by and in accordance with -hanges in the rate of flow of vapor from the generatorfor opening. said valve and operative by and in accordance with changes in static pressure of the vapor for opening the valve and means ope 'ative on a predetermined movement of the piston of said cylinder for closing the valve.

a. The combination of a vapor generator having a furnace with means for changing the pressure of gases in the'furnace and operative by and in accordance with changes in the rate of flow of vapor from the generator and by and in accordance with changes in the static pressure of vapor in. the generator.

5. The combination of a vapor generator 7 having a furnace with means for regulating the pressure of gases in the furnace. means for feeding fuel to the furnace and means operative by and in accordance with changes in each of the components forming the total pressure of vapor flowing from the Q'BIL orator for regulating the operation oi? the furnace pressure controlling means and the fuel feeding means.

6. The combination of a vapor generator having a furnace with means for controlling the discharge of gases from the furnace, means for feeding fuel to the furnace, means for supplying air to the furnace, mechanism for adjusting one of said means by and in accordance with variations of static pressure of the vapor and mechanism for changing such adjusted means by and in accordance with changes in the rate of flow of vapor from the boiler.

7. Thecombination of a vapor generator having a furnace with a stack damper, means operative by and in accordance with the static pressure of the vapor for adjusting the position of the damoer and means operative by and in acca nee with the rate vapor rater for shifting the dar 1 to position given by the static 1 es 8. The combination of a vapor generator having a furnace, means for feeding fuel the furnace, means operative by and in. accordance with changes in the static pressure of the vapor for adjusti the oper ion of the fuel feeding means and means operative by and in accordance with changes in the rate of flow of vapor from the generator for varying the rate of feed of fuel as es tablished by the static pressure.

9. The combination of a vapor generator having a furnace, means for coding air to the furnace, means operative by and in ac cordance with char in the static pressure of the vapor for adjusting the operation of the air feeding means and means operative by and in accordance with changes in the rate of flow of vapor from the generator for varying the rate of feed of air as established by the static pressure.

10. The combination of a vapor gen" a having a furnace with means for e1 v the regulation of one of the operations aflecting combustion, mechanism operat' by and in accordance with the changes in the rate of low of steam from the generator, mecha nism operative by and in accordance with changes in the static pressure of seam in the generator, both of said mechanisms being adapted to operate the regulating means in the same direction on an increase in the rate of flow or a decrease in static pressure or vice versa.

In testimony whereof, I have hereunto set my hand.

JOHN M. lriill ftlfll).