US1492604A - Regulation of combustion - Google Patents

Description

May 5, 1924, 1,4926% T. A. PEEBLES REGULAT ION OF COMBUSTION Filed Dec. 18, 1922 ZSheets-Sheet 1 T. A. PEEBLES REGULATION OF COMBUSTION Filed Dec. 18. 1 122 2 Sheets-Sheet 2 Patented May 6, i924.

SFATES aerate aaeuaarrou or comeusrron.

Application filed December To all whom it may concern.

Be it knownthat I, THOMAS A. Pnnenns, residing at Pittsburgh in the county of Al- 1 legheny and-State of Pennsylvania, a citizen to a characteristic of the fan most generally used for producing the forced draught. Such characteristic being due to the fact that if when such a fan is operated at a given speed and the pressure against which the air is delivered is increased, the volume of air delivered by the fan will decrease. It is a general practice for all forced draft stokers to so operate the fan that a pressure of 5 or 6 inches (Water gauge) is maintained in.the conduit leading to the underside of the fuel bed where the demand on the boiler is high. When the demand for steam is com. paratively small the stack damper will be opened only a small amount and the damper controlling the flow of air to the fuel bed will be in a corresponding position, reducing the delivery of air to the fuel bed. This reduction in the rate of delivery of the air to the fuel increases, for the reasons above stated the pressure against which the air is delivered by the fan into a conduit. The demand may be such that it requires an air pressure of onl one inch under the fuel bed to compensate or the pressure above the fuel bed, due to the esca e of gases from the stack. In such case t e air damper will be nearly closed so as toreduce the pressure under the fuel from 7 or 8 inches in the conduit .to which it would be increased following the closin of the air damper, to l'inch.

In other wor s, a condition would be estabe lished in which there will be a drop of pressure of 6 or 7 inches across the air damper and a very high velocity of air flowing through a small opening. If now, the demand on the generator be increased slightly, the stack damper would be slightly opened reducing the pressure in the furnace and 18, 1922. Serial No. 607,628.

this reduction of furnace pressure will cause a shifting of the air damper. The drop of the pressure in the furnace being small, the movement of the air damper will also be small, but on account of the high pressure on the fan side of the'air damper, this small opening of the air damper will admit such a volume of air. that the pressure above the fuel bed in the furnace will be increased beyond that required to compensate. This increase of pressure will cause an operation of the furnace machine to 0 close the air damper that there will be a reduction of pressure in the furnace chamber below normal and not due to escape of products of combustion and this back and fdrthmovement of the air damper will continue although there has been no change in the demandon the boiler. w

The invention described herein has for its object a primary regulation of the supply of air in accordance with the demand I on the generator whereby the rate of flow to the conduit will be varied in the same direction as the rate of flow of products of combustion from the furnace and then regulatin the flow of air to the under side of theuel bed; by and in accordance with changes of pressure-of gases in the furnace above'the fuel bed. The invention is hereinafter more fully described and claimed.

In the accompan 'ng drawings formiii a part ofthisspeci cation, Fig. 1 is a iagrammatic viewshowing the automatic mechanism for controlling the escape of products ofcombustion from the furnace,

the rimary and secondary air supply to the A furnace and the feeding of fuel; Fig. 2 is a view similar to ig. 1 illustrating a modification of the construction shown in Fig. 1.

In the practice of the invention a master regulator A is employed, said regulator being operated by and in accordance with changes of the ressure of the steam and preferably of t e type and construction shown and described in Letters-Patent No. 1,371,243, granted March 15', 1921, to John M. Hopwood. This master regulator is connectd b so'tl iat by variation in pressure of steam the mechanism .will be operated as described in said patent to shiftthe frame 4 of'the master regulator upanddown as the steam ressure increases or diminishes. This rame 4 is connected by a rod 5 and a bell pipe 2 to'the outlet pipe 3 of the boiler crank lever 61:0 an arm 7 on the shaft of the damper 8 in the outlet stack 9 so that by the operation of this mechanism this damper will be shifted towards opened or closed position as the demand on the boiler changes. This frame 4 is also connected by a chain 10 passing over suitable pulleys bed of the furnace.

- tion as to move toward open to a lever 11, operating a valve mechanism, preferably of the roto-reciprocating type shown and described in Letters Patent No. 1,247,217, granted November 20th, 1917, to Brown and Reeser. This valve mechanism controls the flow of steam or other fluid pressure throu h a pipe 13 to a motor 14 preferably of t e turbine type, operating a fan 15, whose outlet is connected to a conduit 16 leading to the underside of the fuel In the construction shown in Fig. 1 the frame 4 is also connected by a chain 17 to alever 18 of a rheostat 19 controlling a circuit including the motor 20 for operatln the fuel feeding mechanism 21, whic may e of any desired type or const'ruction.

A furnace machine B, preferably of the type or construction described and shown in the right in Fig. 3 of the Patent No. 1,338,924, granted May 4, 1920, to John M. Hopwood, is connected by a pipe 22 to the interior of the furnace at a point above the fuel bed. This mechanism is so constructed as described in said Letters Patent, that by variation of pressure in the furnace a piston of the pressure cylinder 23 will be moved up or down in accordancewith pressure of the furnace as it decreases or increases, thereby shiftin the frame 24, said frame being connecte by a rod 25 to an arm 26 on the shaft of the damper 27 in the air conduit 16.

In the operation of this apparatus a change of steam pressure, say an increase in demand, will cause such a movement of the frame 4 of the master regulator as to move the stack dam er 8 towards open position thereby permitting a freer escape of products of. combustion and a consequent reduction of pressure in the furnace of the generator. This movement of the frame 4 will also so operate the lever 11 connected,

'the damper 27 proportional or approximately proportional to the flow of products Of'COIIlbllSlJlOI! from the stack. On the reduction of pressure in the furnace due to opening of the stack damper 8, the furnace machine B will be operated in such direcosition the damper 27 thereby admitting air in greater quantities -to the underside of the fuel bed.

It will be understood that these mechanisms when installed are so adjusted that under normal conditions the fan will deliver air to the conduit 16 or anterior to the damper 27, at a pressure a little in excess of that desired under the fuel bed under normal conditions of the fuel in the fuel bed, and by the operation of the furnace machine the damper 27 will be shifted to adjust the pressure under the fuel bed to the point required. In other words in this construction of apparatus there is a primary control of the air supplied in accordance with changes in the demand on the generator and a secondary control effected by and in accordance with changes in pressure above the fuel bed.

In the construction shown in Fig. 1 the speed of the fan is varied in accordance with changes in the demand on the generator. In lieu of employings'uch a fan, having a variable rate of operation, a fan having a constant rate of operation or other suitable means adapted to deliver to the conduit a volume of air slightly in excess of the expected maximum demand is employed, and the reduction of this high pressure to a pressure variable in accordance with changes in demand from time to time on the generator, is effected by means of a damper 28 in the conduit intermediate the source of supply and the master damper 27, said damper eing, operated by the master regulator A,

by means of a rod 29 connecting the frame 4 of the master regulator with an arm 30 En th; shaft of the damper 28 as shown in In the construction shown in Fig. 2 the feed of fuel is controlled by the master regulator. which is operatively connected by an arm 31 to a valve 32 controlling the flow of fluid pressure to the motor 33 from any suitable source. i

I claim herein as my invention:

1. The method herein described for regu lating the combustion of fuel in a vapor generator which consists in regulating the escape of ases by and in accordance with the demand on the generator, effecting a primary regulation of the air for combustion by and in accordance with the demand on the generator, and effecting a further regulation of the air for combustion, by and in accordance with the the fuel bed.

2. The method herein described of regu pressure of gases above eaeoa to the point where the flow of air to the underside of the fuel bed is regulated.

8. The method herein described of regulating the combustion. of fuel in' a vapor generator which consists in providing a supply of air at a pressure required for the operation of the generator at a maximum rating, regulating the flow of air to the underside of the fuel bed by and in accordance with the pressure of gases above the fuel bed, regulating by and inacco-rdance with the demand on the generator the 7 How of gases from the combustion chamber,

the flow of air from the point of supply to the point where the flow of air to the underside of the fuel bed is regulated, and the supply of fuel.

4. The method herein described of regulating the combustion of fuel in a vapor generator which consists in regulating the escape of products of combustion and the feed of fuel by and in accordance with the demand on the generator, effecting a primary regulation of the supply of air for combustion by and in accordance with the demand on the generator and effecting a further regulation of the supply of air by and in accordance with the pressure of gases above the fuel bed. Y

5. The combination of a vapor generator having a furnace, means for controlling the escape of gases from the furnace, means adapted to supply air for combustion at a pressure greater than that required for operating the generator at maximum rating,

means operative by and in accordance wit changes in the pressure of gases above the fuel bed for regulating the pressure of air s under the fuel bed, means operative by and in accordance with the demand on the generator for regulating the pressure of air anterior to the point where flow to the underside of the fuel bed is effected, and means for regulating the means employed for controlling the escape of gases from the fur nace by and in accordance with the demand on the generator. v

6. The combination of a: vapor generator having a furnace, means for supplying fuel, mean for controlling the escape of gases from the furnace, means adapted to supply to the underside of the fuel bed is regulated.

7. The method herein described of regulatingthe generation of steam which. consists in regulating the escape of gases generated and the combustion of fuel by and in accordance with the pressure of steam, effecting a primary regulation pf the air for combustion of the'fuel by and in accordance with the pressure of steam and efiect-- ing a further regulation of the air for combustion by and in accordance with the pressure of furnace gases.

8. The combination of a vapor generator having a furnace with means operative by and in accordance with the pressure of steam in the generator for regulating the escape of gases from the furnace, means operative by and in accordance with the pressure of steam for effecting a primary regulation of the air for combustion and means operative by and in accordance with the pressure of' gases above the fuel bed for effecting a fur ther regulation of the air for combustion.

9. The combination of a vapor generator having a furnace with means operative by and in accordance with the pressure of steam for regulating the escape of products of combustion from the furnace and the feed of fuel to the furnace, means operative by and in accordance with the pressure of steam for effecting a primary regulation of the supply of air for combustion, and means operative by and in accordance with the pressure of gases above the fuel bed foreifecting a further regulation of the supply of airfor combustion.

my hand.

rHoMAs A. rnnstss.

In testimony whereof, I have hereunto set

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