US1573079A - Apparatus for proportionately mixing air and gas - Google Patents

Description

Feb. 16 1926. n 1,573,079

G. w. MCKEE APPARATUSFOR PROPORTIONATELY MIXING AIR AND GAS Filed April 16, 1924 Patented Feb. 16, 1926.

UNITED STATES PATENT OFFICE.

GARNET W. IlllIoKEE, 0F ROCKFORD, ILLINOIS.

Application iled April 16, 1924. Serial No. 707,010.

certain new and useful Improvements in` Apparatus for Proportionately Mixing Air and Gas, of which the following 1s a specification.

This invention relatesin general to apparatus for mixing air and gas and pertains more specifically to apparatus of this character adapted to deliver air and gas in predetermined proportions irrespective of variations in the air flow induced by a variable resistance in the airline or by other causes.

In gas ired furnaces and other apparatus of similar character it is frequently desirable for purposes of economy and e ciency to pass the air constituent of the combustible mixture delivered to the burners, through a recuperator or other apparatus by which heat units from the exhaust gas of the furnace are transferred to the intlowing air. Since the inflowing air passing through the recuperator is expanded to a greater or less degree, depending upon the temperature of the exhaust gases from the furnace, it follows that the recuperator acts as a variable resistance to the How of air through the air line.

The primary purpose of my present invention is to provide a proportional mixing apparatus which will deliver a mixture of air and gas of proper proportions irrespective of fluctuations in the pressure of the air and gas constituents and irrespective of variations in the resistance imposed upon the air line beyond the control point.

Another object is the provision of an apparatus of the character indicated which will be very sensitive to How variations in the air line, one which will be thoroughly reliable in operation, and one in which the volume of mixture maybe controlled by the manipulation of a single valve in the air line.

Another object is to provide an apparatus which will be readily capable of adjustment so as to vary the relative proportions of air and gas delivered in order to produce a combustible mixture of the requisite pro portions.

My invention further contemplates a novel method by which the desirable characteristicsabove mentioned, and others, may be secured. 1

Otherpobjects and advantages' of my invention should be readily appreciated as the same becomes better understood by lreference to the following description, when considered in connection with the accompanying drawing.

vOn the drawing,-

The single gure is a somewhat diagrammatic side elevation, partially in section, of an apparatus constructed in accordance with my invention.

Referring to the drawing more in detail, reference character 5 indicates generally a fragment of the side wall of a furnace or other heating ap aratus into which the delivery nip le 6 o a mixing burner indicated generally y 7 projects. While this mixing burner may be of any preferred construction, it is illustrated as being of the type wherein the air and gas enter the burner casing from opposite sides and are de livered into thev nipple in a series of concentric rings or cylinders of different diameters, the rings of air alternating with the rings of gas as is common in this type of burner.

Gas is supplied to the burner through a gas supply pipe 8 in which is interposed a control device indicated generally by 9 and commercially known as a zero regulator. The regulator comprises a balanced valve 11 suspended from an adjustable spring 12 and connected with a diaphragm 13, the lower face of which communicates through a port 14 with the delivery chamber 15 of the casing and the upper face of which is subjected to air pressure entering through an intermediate pipe 16 and controlled as will be later explained.

Air is supplied under pressure to the burner through an air supply pipe 17 in which is interposed a recuperator 18 or other apparatus adapted to produce a varable resistance in the air line. Since the recuperator or other apparatus may be of any well known or preferred type, the details of construction thereof are not illustrated herein but the apparatus is diagrammatically illustrated only.

The point in the air line to which the gas control is connected is located forwardly of the recuperator, that is, between the recuperator and the fan blower or other apparatus cn'lployed for delivering air through the llille under pressure.

Since the flow of air through the air line will vary in accordance with variations in the. resistance imposed upon the line by the recuperator, m present invention contem-4 plates the utilization of this variation 1 n flow to control the delivery of gas to the burner in accordance with these air vflow wu'iations. vWith this end in view I have im terposed in the air line a Venturi tube 1 9 and have connccted'a pipe 21 to said tube near its intake end and a pipe 22 to the throat of the tube. Since the volume of air flowing through the tube is-a .square root function of the difference in pressures exerted on the pipes 21 and 22 from the t-ube, it will be manifest that through these pipe connections with the tube I obtain a pres-l sure differential which may be utilized for controlling the gas.-

The pipes 21 and 22 are connected to ya diaphragm chamber 23 respectively above and below a diaphragm24 disposed therein. This chamber and diaphragm are part of a control unit indicated generally by 25, comprising also a second dia )hragm chamber 26 in which a diaphragm 2 is mounted, the chamber above the diaphragm being open to atmosphere through a port 28 and the chamber below the diaphragm communiveating through a port 29 with the delivery chamber 31 of a casing to which the air line 17 is connected through a branch. 32. A balanced valve 33 sus ended from an adjustable spring 34 an connected with the diaphragms 24 and 27 regulates the .air pressure entering the chamber 31.` Since the pressures exerted through the pipes 21 and 22 upon the upper and lower faces .of the diaphragm 24 vary in conformity with variations in air flow through the venturi 19 the valve 33 connected to the diaphragm by the rod 2O will be correspondingly opened or closed, thus varying the air pressure in the chamber 31 in accordance with variaclude the delivery of an excessive air pres-- sure through the pipe 16a restriction 34 is interposed in the connection between 'the pipe 16 and the chamber 31. Furthermore,

.in order to variably reduce the pressure transmitted to the controller '9 so that the f movements of the valve 11 inthe gas line,

lthrough the venturi.

delicate control, I have intel osed in the connection between the contro er 9 and the chamber 31 of the main controller anl adj ustable delive orifice 35 throu h which communication etween the interior ofthe pipe 16 and atmosphere'is established. e. This orifice may be manually regulated to per'mitthe escape of anydesired proportion of the air pressure delivered to the connecting pipe 1.6. Consequently by regulating this orifice any desired fraction of the air pressure lating valve 36 or other preferred means of 4 control. The ratio of gas delivered in pro- -portion to this maximum of air may be regulated by the hand valve 37 in the gas line 8. When the desired ratio' has been estabnecting 37 and 7 may be considered as one and the same resistance and this' composite resistance can be varied by manipulating the valve 37. A

Now the amount of gas flowing from v15 to the furnace varies as the square root of the difference in ressure between point 15 and the pressure 1n the furnace. Since the pressure in the furnace is very low-substantially atmospheric pressure-the quantity of gas flowing to the furnace varies as the square root of the pressure at l5. Likewise the flow of air through the .venturi will be a corresponding function of the difference in pressure between the intake end and the throat of the venturi. This ressure difference is transmitted through t e pipes 21 and 22 to the diaphragm 24 which controls the valve 33 so that the pressure in the chamber 31 becomes also a function of the quantity of air flowing through the venturi. This pressure or such fraction thereof as may be determined by the adjustable ori fice 35 is transmitted to the gas controller 9 with the result that the pressure of the gas at the outlet of the controller is likewise a function of the volume of air flowing The pressure on the inlet side of valve 37 varies, therefore, in accordance with variations inthe quantity of air flowing through the venturi, consequently the quantity of gas delivered past -this valve will always bear a simple ratio to the quantity of air delivered and this ratio may be varied by adjusting the valve v37. The predetermined proportions of air and gas in the mixture will., therefore, always be maintained irrespective of variations in the quantity of air delivered.

The structural details illustrated and described may obviously be varied within considerable limits without departing from the essence of the invention as defined in the following claims.

I claim:

l. In'` an apparatus for proportionately mixing air and gas, an airv .supply line, means for producing apressure difere'ntial in said air line, an intermediate pipe, means for varying the iuid pressure in said pipe in' accordance with said diiierential, a gas supply line, andmeans for varying the i'low of gas in said gas supply line in accordance with the pressure in said pipe.

2. In an apparatus for proportionately mixing air and gas, an air supply line, means for producing a pressure differential in said air line, an intermediate pipe, adjustable means for varying the pressure in sai-d pipe in accordance with said differential, a gas supply line, and adjustable means for varying the flow of gas in' said gas supply line in accordance with the pressure in said pipe.'

3. In an apparatus forl proportionately mixing air ,and gas, an air supply line, means for producing a pressure differential in said air line, an intermediate pipe, adjustable means for varying the pressure in said pipe in accordance: with said diierential, a gas supply line, adjustable means for varying the'ow of gas in the gas supply line in accordance with the pressure in said pipe, and adjustable means for stopping the ow of gas in said gas supply line when the pressure differential in Vthe air line decreases below a predetermined value. v 4. In an apparatusv for proportionately mixing air and gas, the combination of an air supply line, a gas supply line, a controller in said gas supply line, means in said air supply line for producing a pressure differential adaptedl to fluctuate in accordance with fluctuations with the flowin said line, a branch line connecting said air supply line with said gas' controller, and means controlled through said pressure differential for regulating said gas controller through the intermediary of the air lin said branch line.

' 5. In an apparatus for proportionately mixing air and gas, the combination of an air supply line, a gas su ply line, a gas con,- troller in said gasl supp y line, a connecting pipe between fiid air supply line and said controller, and means controlled by the low of Iair in said air supply line for regulating said gas controller through the intermediary' of the air in said connecting pi e to thereby regulate the flow of gas in sai -gas Asupply line in accordancev with variations of iow in the air supply line.

6. In an apparatus for proportionately mixing air and gas, the combination of an air supply line, a gas supply line, a controller in said gas supply line, a connection between the air supply line and the controller,

, a regulating valve in said connection, means in the. air supply line for producing a pressure differential in accordance' with variations in the flow through said line, and means actuated by said pressure differential for controlling said regulating valve.

7. In an apparatus for proportionately mining air and gas, the combination of an Iair supply line, a gas supply line, a gas flow 'controller in said line, said controller including a diaphragm controlled valve, an air connectinr pipe between said air line and said diap ragmta regulating valve in said `air connecting pipe, a Venturi tube'in said air supply line, .a diaphragm connected with said regulating valve, and means for stablishing communication between opposite faces of said diaphragm and the intake end ang the throat, respectively, of said Venturi tu e. y

48. In an apparatus for proportionately mixing air and gas, the combination of an air' supply line, a gas supply line,a gas flow controller in said gas supply line, comprising a diaphram controlled valve, a pipe establishing communication between the air supply line and one face of the diaphragm of said controller, a regulating valve in said pipe, the diaphragm controlling said valve,

a Venturi tube in the air supply line, a pipe connecting an end of said tube with one face of said diaphragm, a pipe connecting the throat of said tube with the other face of the diaphragm, and a Variable resistance device interposed in the air supply line at the delivery7 side of said Venturi tube.

9. In an apparatus for proportionately mixing air and gas, the combination of an air supplyline, a gas supply line, a gas flow controller comprising a diaphragm controlled valve in the gas supply line, a recu perator in the air supply line, a Venturi tube 1n the air supply line ahead of the recuperator, a pipe connecting the air supply line with said gas controller,` a primary controller comprising a double diaphragm. controlled valve interposed in said pipe, an adjustable orifice in the pipe `between the said controllers, means for establishing communication between one end of the venturi and one face ofthe diaphragm with the primary control- 1er and means for establishing communicationbetween the throat of said venturi and the other face of said diaphragm.

'p f GARNET W. MCKEE.

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