US1374796A

US1374796A - Gas-furnace

Info

Publication number: US1374796A
Authority: US
Publication date: 1921-04-12
Anticipated expiration: 1938-04-12

Description

C. J. WRIGHT.

GAS FURNACE.

APPLICATION FILED JUNE 11. 1919.

1,374,796. Patented Apr. 12, 1921.

4 SHEETS-SHEET 1.

|' 4l li 1 Smumakoz C. J. WRIGHT.

GAS FURNACE,

APPLICATION FILED JUNE n 1919.

1,374,796. Patented Apr. 12, 1921.

4 SHEETSSHEET 2.

G. J WRIGHT.

GAS FURNACE.

APPLICATION HLED JUNE 1!. 1919.

1,374,796. Patfinted Apr. 12, 1921.

4 SHEETS-SHEET 3.

amueutoz 6' I C. J. WRIGHT.

GAS FURNACE. APPLICATlON FILED JUNE 1|. 1919.

1 74,79fi. Patented Apr. 12, 1921.

, 4 SHEETS*SHEET 4.

/ 7* ma m an we idol PATENT OFFICE.

CARL J. WRIGHT,

01E TOLEDO, OHIO.

GAS-FURNACE Application filed June 11, 1919.

To all whom it may concern:

Be it known that I, CARL J. WVRIGHT, a citizen of the United States, residing at Toledo, in the county of Lucas, State of Ohio, have invented certain new and useful Improvements in Gas-Furnaces; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to gas furnaces and more particularly to a method of and apparatus for controlling the temperature in gas fired regenerative furnaces.

In the application of gas as a fuel for heating high temperature, metallurgical and similar furnaces, it is necessary to preheat the air supplied to the furnace in order to obtain suiliciently high temperatures without using an excessive amount of gas. Although the temperatures may be increased in this manner, the heating systems at present in use do not provide an accurate control of the tcniperature'of the furnace as a whole nor of the flame temperatures in different parts of the furnace. The temperature obtained in a furnace will depend to a certain extent on the amount of gas supplied to the furnace, and may be roughly controlled by controlling the rate of supply of fuel gas, but will depend more directly on the temperature of the preheated air supplied to the furnace and on the character of the flame produced in the furnace. Even though the supply of air and fuel be kept substantially constant, therefore, the temperature of the furnace may vary at different times'and the temperatures in different parts of the furnace may be different at any given time.

The primary object of the present invention is to provide a process of heating furnaces by which the temperature in the furnace may be accurately and automatically controlled.

A further object of the invention is to provide a regenerative heating apparatus for a furnace by which the furnace temperature may be kept at any desired temperature.

A further object of the invention is to provide a process and apparatus for heating an open hearth regenerative furnace by which the character of the flame may be controlled to obtain any desired temperature in the furnace While maintaining corre- Specification of Iietters Patent.

Patented Apr. 12, 1921.

Serial No. 303,365.

'sponding temperature conditions in the regenerators.

WVith these and other objects in View the invention consists in the process and apparatus set forth in the following specification and claims. 1

The various features of the invention are shown in the accompanying drawings, in Which- Figure 1 is a lan View in section, taken on line 1-1 of ig. 2, of the furnace and temperature controlling apparatus embodying the preferred form of the invention.

Fig. 2 is a vertical section of the furnace taken on the line 22 of Fig. 3.

Fig. 3 is a vertical sectional view of the furnace taken on the line 3-3 of Fig. 2.

Fig. 4 is a detailed view of an anemometer gas measuring device and a portion of an electrical valve controlling mechanism.

Fig. 5 is a detailed view in side elevation of the valve shifting apparatus, and

Fig. 6 is a detailed sectional View of the gas burners for the furnace.

The particular furnace illustrated in the drawings is of the open hearth type in which iron or steel forgings are heated while some forgings are being placed on the hearth and other heated forgings are being removed from the hearth continuously The forgings rest on a hearth 10 (Fig. 2) which is heated by gas admitted through sets of burners positioned at opposite sides of the hearth. The air for burning the gas is alternately heated in one of a pair of

regenerators

14 and 16 and at the same time one of the regenerators is heated by hot combustion products leaving the hearth. The two sets of burners are placed in operation alternately in accordance with the direction of flow of the air for combustion and the supply of gas to the corresponding set of burners is shifted from one set of burners to the other at the time flow of air is reversed. To secure any required uniform temperature over the hearth, the reversal of the direction of flow of the gas and air is accomplished automatically by a control depending upon the quantity of gas being burned. The flame temperature and the course of the flame over the hearth, also, are controlled by a secondary air supply which is admitted to the burners through pipes 18. I

With a given rate of supply of air and gas, the temperature obtained in the furnace will be increased or decreased by a corresponding increase or decrease in the temperature of the air from the regenerators.

n order, therefore, that the furnace maybe kept at any desired constant temperature, it is necessary that the regenerators be kept at correspondingly even temperatures. This may be accomplished by burning equal quantities of fuel gas in the furnace during the intervals when the regenerators are heated by the waste products of combustion, since the combustion of equal quantities of gas will produce equal quantities of heat in the combustion gases which serve to heat the regenerators.

In the embodiment of the invention described below the quantity of gas burned in the furnace during each regenerator heating interval is kept constant by stopping the passage of combustion gases to the regenerator being heated and directing the gases I to another regenerator when a predetermined quantity of gas has been supplied to the furnace. Inasmuch, as the ratio of gas to air supplied for combustion is constant for any given gas the length of intervals of heating the regenerators may be controlled by either the flow of air or of fuel gas to the furnace. In the following description and in the claims, therefore, when gas is specified this may designate either the fuel gas which is to be burned or the air supplied to support combustion.

In the process and apparatus described below the gases for combustion are passed through an anemometer or other suitable gas measuring device before passing to the furnace. Each time a predetermined volume of gas has passed to the furnace the measuring device actuates an electric control mechanism governing a valve shifting apparatus by which the course of flow of the hot products of combustion is reversed to direct the products through a regenerator that has just previously been used to preheat air for supporting combustion. At the same time the valve shifting mechanism reverses the course of the air to be preheated, and directs it through the regenerator which has just been heated by the hot products of combustion. The gas measuring device or anemometer wheel preferably consists of a rather delicate mechanism which cannot be used to directly govern an electric current sufliciently powerful to operate the electric control mechanism. The auemometer therefore directly controls a weak current, and this in turn governs a comparatively heavier current which operates the valve shifting control mechanism.

The fuel gas for heating the furnace hearth 1Q (Figs. 1, 4 and 5) is supplied through a gas pipe 20. The gas passing through the pipe 20 is directed by a nozzle 22 in the pipe 20 against the blades of an anemometer wheel 24 which is rigidly supported on a rotatable shaft 26. The shaft 26 extends through the pipe 20 and into a gas tight gear box 28 contained in a larger box 30. The rotating shaft 26 drives a speed reducing worm and gear mechanism 32 in the box 28 connecting the shaft 26 to an arm 3 L in such a way that the arm 3 f will be rotated through 180 degrees upon the passage of a predetermined quantity of fuel through the nozzle 22 and pipe 20. As the arm 34: rotates through each half revolution it contacts alternately with con.-

tact pieces

36 and 38 on the gear box 28. The rotating arm 34 is connected through the gear box 28 to a wire 40 leading from a battery or other low voltage generator furnishing an electric current. The low voltage current is used to operate or control a heavier electric current directly controlling the valve shifting apparatus. As the arm 34L comes in contact with the contact point 36 an electric current flows through the wire 40, box 28, arm 34 and contact 36 to a wire l2 connected to the contact point 36 and insulated from the metal box 28. From the wire l2 the current passes through a solenoid 44 and returns to the battery or low voltage generator through the

wires

46 and 48. \Vhen the current flows through the circuit, as above described, it energizes the solenoid and draws an armature core 50 down into the solenoid. The armature core 50 is pivotally connected to one end of a lever which is pivoted at its center on a pivot 54. As the armature core 50 is drawn down into the solenoid ll, it tilts the lever 52 on the pivot 5a against the action of a spring 56 which tends to hold the lever 52 in a horizontal position. When the lever 52 is deflected through the action of the solenoid 4e}.- and armature core 50, two

contact pieces

58 and 60 on the lever 52 are brought into contact with

contact pieces

62 and 64 respectively supported on the box 30. Upon making these contacts an electric circuit is closed through an electric main 66 leading to a source of power and an electric main 68 leading to a valve shifting apparatus. In

similar way, as the arm 34 is given another half revolution by the anemometer 24: it comes into contact with the contact piece 38 on the box 28. The current then flows from the wire 40 through the box 28. arm 84; and contact piece 38 to a wire 70. connected to the contact piece 88. From the wire 70 the current enters a solenoid 72 and passes back to the low voltage generator or battery through wires 74 and 48. In passing through this circuit the current energizes the solenoid 7 2 so as to draw downwardly an armature core 76 connected to the end of the lever 52. As the armature core 7 6 is drawn downwardly into the soles noid 72 the lever 52 is tilted to bring the contact piece 58 into contact with a contact piece 7 8 connected to the electric main 66 and to bring thecontact piece 60 into contact with a contact piece 80 connected to a wire 82 leading to the valve shifting apparatus. The apparatus contained in the box 30 therefore acts as an electro-magnetic switch to place the electric main 66 alternately into contact with the wiresi68 and 82 upon each half revolution of the arm 34 by the anemometer wheel 24.

hen the electric main 66 is placed in communication with the wire 68 (Fig. 4) an electric current for controlling the valve shifting mechanism will flow through the main 66 and wire 68 to a solenoid 84 (Fig. 1) and will return from the solenoid 84 to the electric generator through wire 86 and main 88. Similarly, as the main 66 is put into communication with the wire 82 the controlling current will pass through the main 66 and wire 82 to a second solenoid 90 (Fig. 1) and will pass from the solenoid 90 through wire 92 and main 88 back to the electric generator. As the current is sent through the

solenoids

84 and 90 it alternately energizes first one and then the other. When each solenoid is energized it attracts a slide 04 which acts as an armature core in each of the

solenoids

84 and 90 so that the slide 94 is shifted at each reversal of the current.

Each time that the slide 94 is shifted it acts through a crank arm 96 to operate a four-way valve 98 which controls a supply of fluid under pressure for operating the valve shifting mechanism. pressure is supplied to the four-way valve 98 through a pipe 100 and is directed througl'i the four-way valve 98 into either a pipe 102 or a pipe 104 in accordance with the setting of the valve. The

pipes

102 and 104 communicate with opposite ends of a cylinder 106 and are arranged to direct fluid against the opposite sides of a piston 108 sliclably mounted in the cylinder. When the pipe 100 is put into communication with one of the

pipes

102 and 104 to direct fluid against one side of the piston 108, simultaneously the fluid atthe other side of the piston passes out of the cylinder through the other pipe and then through the valve 98 into a waste pipe 110. As the slide 94 moves back and forth therefore it alternately places opposite ends of the cylinder 106 into communication with the supply pipe 100 and the waste pipe 110.

When the piston 108 is reciprocated by the pressure fluid, a piston rod 112 attached to the piston 108 is actuated to operate the valves for controlling the supply of air and gas to the regenerators. The valve for controlling theflow of air to the regenerators may be any one of the commonly used Fluid under I moved by the reciprocation of the piston rod 112; To accomplish this, arms 124 and 126 (Figs; 1 and 5) are fixed at their lower ends to a shaft 128 rotatably mounted in the valve chamber and the upper ends of the arms engage pins 130 projecting from the side of the valve. An arm 132 is fixed on the outer end of the shaft 128 and has a slot 134 at its upper end which engages a pin 136 mounted in the piston rod 112. With this construction, as the piston rod 112 is moved back and forth it rotates the shaft 128 by means of the crank arm 132 and shifts the valve 114 to alternately cover the

ports

118 and 122 and the

ports

118 and 120.

A regulated supply of air is forced by a blower 138 through the port'118 and under the valve 114, and flows into either the port 120 or the port 122 according to the position of the valve 114. In the position of the valve-shown in Figs. 1 and 5, the air entering into the port 118 will be directed to the port 122. The air flowing through the port 122 will then enter a flue 140 leading down under the hearth 10, as shown in Figs. 2 and 3. From the flue 140 the air meets gas entering through burners 18. The. burning gas and alr then pass over the furnace hearth 10. The hot products of combustion leave the hearth 10 through openings 146 and pass downwardly into a regenerator chamber 14 which is filled with checkerbrick. As the hot products of combustion pass through the regenerator 14 theygive up a part of their heat and serve to heat the regenerator checkerbrick. From the regenerator 14 the gases then pass into a flue 148 (Fig. 2) which leads to the port 120, from which the waste gases are exhausted to the atmosphere. When the valve 114 is shifted through the action of the piston rod 112 so as to cover the

ports

118 and 120, the air flows from the port 118 through the valve 114 to the port 120 and through the flue 148 and regenerator 14 to the furnace hearth 10. From the furnace hearth the hot products of combustion pass hausted and the ingoing air will be preheated to substantially the temperature of the combustion products entering the regenerator chamber.

The sets of gas burners at opposite sides of the hearth are burned alternately to supply gas to the heated air entering the hearth from a regenerator. The gas supply is controlled to supply the gas to the different sets of burners to correspond to the air circulation. The gas for the burners is led in through the pipe 20 to a T 150 which is connected to

pipes

152 and 154 leading respectively to

burners

156 and 158 on opposite sides of the furnace. Valves 160 and 162, mounted in the

pipes

152 and 154, are arranged to be alternately opened and closed so as to direct the fuel gas either into pipe 152 or pipe 154. To this end valve stems 164 and 166, extendin from the valves 160 and 162 are connected with crank

arms

168 and 170 which are provided with slots 172 and 174 arranged to engage pins 176 and 178 on the piston rod 112. As the piston rod 112 is shifted back and forth it gives the crank

arms

168 and 170 and the shafts 164 and 166 a quarter turn so as to close one and open the other of the valves 160 and 162. The valves 160 and 162 may be so arranged to open and close in any desired sequence. Thus one valve may be closed a short time before the other is opened in order to allow the gas to burn out on one side before it is put on the other.

The air supplied to the furnace is placed under a positive pressure by the blower 138 and passes through the port 118 and the

regenerators

14 and 16 with a small drop in pressure. The air as it enters the hearth chamber is still under a pressure higher than that of the atmosphere and moves with a comparatively slow velocity. There is a tendency, therefore, for a large part of the combustion gases to pass out of the furnace directly to the atmosphere through an open ing 180 which is provided in the front of the hearth chamber for introducing and removing the articles to be treated on the hearth. There is a consequent loss of heat from the front of the hearth chamber eausing an unevenness in the heating of the furnace. The loss of hot combustion gases, through the opening 180, also interferes with the heating of the regenerators, and makes it diflicult for the workmen to approach the opening 180.

In order to prevent this escape of the hot combustion gases through the opening 180 the course of the flame is controlled to carry it directly across the furnace chamber and to direct it to any desired portion of the hearth. Forthis purpose a secondary supply of air, under pressure, is admitted to the burners to which the gas is supplied. This secondary air enters the hearth chamber with a high velocity and controls the flame in the same manner in which a flame is controlled by a blow pipe. Secondary air for the burners is supplied through a pipe 182 (Fig. 5) mounted between the furnace and the valve shifting chamber. From the pipe 182 the air flows through a T 184 to

pipes

186 and 188 which lead to the opposite sides of the furnace and are connected with

burner pipes

190 and 192 respectively, surrounding the gas inlet pipes. Valves 194 and 196, arranged similarly to the valves 160 and 162 in the gas supply pipe, are mounted in the

pipes

186 and 188. The valve stems of the valves 194 and 196 extend through the valves 160 and 162 and are connected to the valve stems 164 and 166 respectively. With this construction the valves 194 and 196 will be operated at the same time that the gas valves 160 and 162 are operated. The amount and pressure of the air supplied is controlled by means of a valve 198 in the supply pipe 182. By varying the pressure and volume of the secondary supply of air the velocity of the gases across the chamber may be controlled and the flame may be shortened or contracted in much the same manner as the flame of a blast lamp may be controlled. In this manner the temperature throughout the furnace may be controlled independently of the fuel supply or the temperatures in the regenerators. y varying both the fuel supply and the additional air supply the flame will be varied so that within certain limits any amount of fuel may be burned at any desired space, thereby allowing a greater latitude of the temperature regulation over that possible in the ordinary regenerative furnace.

The operation of the entire apparatus is V briefly as follows '34 and the contact pieces 36 and 38 a small electric current is sent alternately through the

solenoids

44 and 72 contained in the box 30 so as to alternately deflect the lever 52 in opposite directions and connect the main 66 of the stronger electric current alternately with the

wires

68 and 82. When the current is sent through the wire 68 or wire 82 to the

solenoid

84 or 90, the

solenoids

84 and 90 are alternately energized and shift the rod 94 to the right or left. The rod 94, through the crank arm 96, operates the fourway valve 98 to deliver fluid under pressure to one end or the other of the cylinder 106 and to thereby shift the piston rod 112 to the right or left. The back and forth movement of the pistonrod 112 simultaneously rotates the crank

arms

132, 168 and 170 and the shaft 128 and valve stems 16 1 and 166 a quarter of a turn. Through the connections described above the shaft 128 shifts the slide valve 114 to connect the port 118 to either the

port

120 or 122, and at the same time the valve stems 16 i and 166 serve to simultaneously open the valves 160 and 194C and close the valves 162 and 196 or to close the valves 160 and 194i and to open the valves 162 and 196. In this way both the gas from the pipe 20 and the air under pressure from the pipe 182 are conducted to that side of the furnace through which the air enters from the regenerators.

As mentioned above the anemometer may be placed in the air supply pipe for the furnace and other types of meters may be employed. With other types of meters it may be necessary to employ but one electric current or employ entirely different means for controlling the valve shifting apparatus. The valve shifting means may also be oper ated by other motive power than the fluid under pressure, as described in the above specification. These and other similar changes in the mechanical details of the furnace may be made without departing from the spirit of the invention.

In the above specification it has been stated that the valve-shifting control mechanism is operated upon the passage of equal amounts of gas through pipe 20. In case the

regenerators

14 and 16 do not have the same heat absorbing capacity and that it may require a slightly greater amount of hot products of combustion to heat one of the regenerators than it does to heat'the other,

the'contact pieces

36 and 38 in the box 28 may be shifted slightly so that contact between the arm 34 and the

contact pieces

36 and 38 will be made in correspondingly slightly unequal times. In such case the regenerator heating effects of the gases burned in each interval will be equal, and, the term equal is used in the specification and claims rather in the sense of this heating equality than in the sense of an exact mathematical equality of the volumes of air.

I claim 1. The combination with a furnace of a pair of heat regenerators adapted to alternately heat the air passing to the furnace a gas supply for said furnace, the combination of a valve for reversing the direction of flow of the gases through said regenerators and furnace, and means controlled by the volume of gas supplied to the furnace for shifting the valves.

3., In an open hearth regenerative furnace having a set of heat regenerators adapted to alternately heat the air supplied to the said furnace and to be heated by the hot products of combustion from said furnace, the combination of means for supplying gas to either side of said furnace, a reversing valve for reversing the direction of flow of the gases through said regenerators and furnace, and means controlled by the volume of gas supplied to the furnace for automatically shifting the reversing valve and alternately opening and closing the supply of gas to either side of said furnace.

4;. In an open hearth regenerative furnace having a set of heat regenerators adapted to alternately heat the air supplied to said furnace and to be heated by the hot prod ucts of combustion from said furnace, the combination of means for supplying gas to either sid of said furnace, a valve for reversing the direction of the flow of gases through said regenerator and furnace, and means actuated by the passage of gas to the furnace for automatically shifting the reversing valve and alternately opening and closing the supply of gas to opposite sides of the furnace after the passage of predetermined quantities of gas to the furnace 5. In an open hearth regenerative furnace having a set of heat regenerators adapted to alternately heat the air supplied to said furnace and to be heated by the hot products of combustion from said furnace and a series of gas burners on either side of said furnace, the combination of a valve for reversing the direction of flow of gases to said regenerator and furnace, means for supplying air and gas to said burners, and means fo automatically shifting the reversing valve, and alternately opening and closing the gas and air supply to the burners'on either side of said furnace after the passage of predetermined quantities of gas to the furnace. l

6. In an open hearth regenerative furnace having a set of heat regenerators adapted to alternately heat the air supplied to said furnace and'to be heated by the hot products of combustion from said furnace and a series of gas burners on either side of said furnace, the combination of a valve for reversing the direction of flow of gas through said regenerators and furnace, means for supplying air and gas to the burners, and means actuated by the passage of gas to the furnace for automatically shifting the reversing valve, and alternately opening and closing the gas supply to either side of said furnace after the passage of predetermined quantities of gas to the furnace.

7. In an open hearth regenerative furnace having a set of heat re enerators adapted to alternately heat the an supplied to said furnace and to be heated by the hot products of combustion from said furnace, gas burners for said furnace, a direct gas and air supply for said burners, means for reversing the direction of flow of gas and air through said burners, means for supplying air to said burners through said regenerators, and means for reversing said regenerator air when the burner gas and air is reversed.

8. In an open hearth regenerative furnace having a set of heat regenerators adapted to alternately heat the air supplied to said furnace, and to be heated by the hot products of combustion from said furnace, gas burners for said furnace, a fuel gas and air supply for said burners, a valve for reversing the direction of flow of gases through said regenerator and furnace, means controlled by the volume of gas supplied to the furnace for automatically shifting the valve after. the passage of predetermined quantities of gas to the furnace, and means for supplying additional air to said burners through said regenerators.

9. In a gas fired regenerative furnace having a reversing valve for alternately reversing the flow of the gases through the regenerators, means for governing the revers- 1ng valve by the gas supply comprising a rotating element actuated by the flow of the gas supply to the furnace, means actuated by the said rotating element to make and break a contact in an electric circuit, and means governed by the electric current in said circuit for shifting said reversing valve.

10. In a gas fired regenerati e furnace adapted to alternately supply preheated air from the regenerators to opposite sides of the furnace and to supply air and gas to burners on opposite sides of the furnace, the combination of a reversing valve for alternately reversing the flow of gases through the regenerators and furnace, valves for alternately opening and closing the gas and air supply to the sets of burners on each side of the furnace, means for shifting said reversing valve and for alter-' nately opening and closing said air and gas valves, a fluid actuated piston for operating said shifting means, a valve for alternately admitting fluid under pressure to one side of the piston and exhausting fluid from the other side of said piston, means actuated by an electric circuit for operating said fluid valve, a switch adapted to alternately make and break the circuits to said operating means, solenoids adapted to operate said switch, a second electric circuit for operating said solenoids, a contact means for opening and closing said second circuit, and a rotating element actuated by the passag of gas to said burners for operating said contact means.

11. In combination with a gas fired regenerative furnace adapted to alternately sup ply preheated air from the regenerators to opposite sides of the furnace and to supply air and gas to burners on opposite sides of the furnace, the combination of a reversing valve for alternately reversing the flow of the gases through the regenerators and furnace, a valve for opening and closing the gas supply to the sets of burners on each side of the furnace, means for shifting said reversing valve and for alternately opening and closing said gas valve, a fluid actuated piston for operating said shifting means, a valve for alternately admitting fluid under pressure to one side of the piston and exhausting fluid from the other side of said piston, means actuated by an electric circuit for operating said valve, a switch adapted to alternately make and break the circuits to said operating means, small solenoids adapted to operate said switch, a second circuit for operating said solenoids, a contact means for opening and closing said second circuit, and a rotating element actuated by the passage of gas to said burners for operating said contact means to alternately close and open the circuits of said solenoids upon the passage of predetermined quantities of gas to said furnace.

12. In a regenerative furnace adapted to alternately supply preheated air from the regenerators to opposite sides of the furnace and to supply air and gas to burners on opposite sides of the furnace, the combination of a reversing valve adapted to alternately reverse the flow of gas through the regenerators and furnace, means for shifting said reversing valve, a fluid actuated piston for operating said shifting means, a valve for alternately admitting fluid under pressure to one side of the piston and exhausting fluid from the other side of said piston, means actuated by an electric circuit for operating said valve, a switch adapted to alternately make and break the circuits to said operating means, solenoids adapted to operate said switch, a second circuit for operating said solenoids, contact means for opening and closing said second circuit, and a rotating element actuated by the passage of gas to said burners for operating said contact means upon the passage of predetermined quantities of gas to said furnace.

13. In a gas fired regenerative furnace adapted to alternately supply preheated air from the regenerators to opposite sides of the furnace and to supply air and gas to burners on opposite sides of the furnace, the combination of a reversing valve for alternately reversing the flow of the gases through the regenerators and furnace, valves for opening and closing the gas and air supply to the sets of burners on each side of the furnace, means for shifting said reversing valve and for alternately opening and closing said air and gas valves, electrically operated means for operating said shifting mechanism and air and gas valves, an electromagnetic switch for controlling said electrically operated means, an electric circuit for controlling said electromagnetic switch, means for opening and closing said electric circuit, and a rotating element actuated by the passage of gas to said burners for operating said means for opening and closing said circuit.

14. In a regenerative furnace adapted to alternately supply preheated air from the regenerators to opposite sides of the furnace and to supply air and gas to burners on opposite sides of the furnace, the combination of a reversing valve for alternately reversing the flow of the gases through the regenerators and furnace, sets of valves for opening and closing the gas and air supply to the sets of burners on each side of the furnace, means for shifting said reversing valve and for alternately opening and closing said air and gas valves, electrically operated means for operating said shifting mechanism and air and gas valves, an electromagnetic switch for controlling said electrically operated means, an electric circuit for controlling said electromagnetic switch, contact means for opening and closing said electric circuit, an aneniometer wheel in said gas supply, pipe and actuated by the flow of gas, anda speed reducing connection between said anemometer wheel and said means for opening and closing said electric circuit.

15. In a regenerative furnace adapted to alternately supply preheated air from the regcnerators to opposite sides of the furnace and to supply air and gas to burners on opposite sides of the furnace, the combination of a reversing valve for alternately reversing the flow of the gases through the regenerators and furnace, valves for opening and closing the gas and air supply to the sets of burners on each side of the furnace, means for shifting said reversing valve and for alternately opening and closing said air and valves, electrically operated means for operating said shifting mechanism and alternately opening and closing said air and gas valves, an electromagnetic switch for controlling said electrically operated means, an electric circuit for controlling said electromagnetic switch, means for opening and closing said electric circuit, an anemometer wheel in said gas supply pipe and actuated by the flow of gas, a speed reducing connection between said anemometer wheel, and ssi d means for opening andclosing said electric circuit, and means for directing all vof the gas against the driving side of said anemometer wheels.

16. A process of controlling the temperatures in gas fired regenerative furnaces comprising passing air through a heat storage element to a furnace to preheat the air for combustion, withdrawing the products of combustion through a second heat storage element, supplying gas to be burned to said furnace, and reversing the flow of the air and gas at the end of each period in which a predetermined quantity of gas has been supplied to the furnace.

17. A process of controlling the temparature in a gas fired regenerative furnace comprising passing air through a heat storage element to the furnace to support combustion, withdrawing the products of combustion through a second heat storage element, reversing the flow of 'the air and products of combustion in the furnace and heat storage elements after each passage of a predetermined quantity of gas to the furnace, and supplying the fuel gas to that side of the furnace to which the air passes from the heat storage element.

18. The combination with a furnace of a pair of regenerators adapted to alternately heat the air passing to the furnace and to be heated by the products of combustion from said furnace, blast burners on opposite sides of said furnace, means for supplying fuel gas to said burners, means controlled by the volume of gas supplied to the furnace for reversing the flow of air through said regenerators, and means for supplying air at any desired pressureto said burners.

19. A. process of controlling the temperature in a gas fired regenerative furnace comprising passing air through a heat storage element to the furnace to support combustion, withdrawing the products of combustion through a second heat storage element. reversing the flow of the air and products of combustion in the furnace and heat storage elements after each passage of a predetermined quantity of gas to the furnace, supplying fuel gas to that side of the furnace to which'the air passes to the heat storage element and supplying additional air under pressure to the furnace at the points where the fuel gas enters.

20. A process of controlling the temperature in a gas fired regenerative furnace comprising passing air through a heat storage velement to the furnace to support combustion, withdrawing the products of combustion through a second heat storage element, reversing the flow of air and products of combustion in the furnace and heat storage elements after each passage of a predetermined quantity of gas to the furnace, supplying fuel gas to that side of the furnace to which the air passes from the heat storage element, supplying additional air under pressure to the furnace at the points Where the fuel gas enters, and controlling the sup ply of additional air to control the character of the flame.

21. A process of controlling the temperature in a gas fired regenerative furnace in which preheated air is supplied from the regenerators alternately to opposite sides of the furnace which comprises supplying the fuel gas to that side of the furnace to which the preheated air passes from the regenerators, supplying additional air under pressure to the furnace at the points Where the fuel gas enters, and varying the supply of additional air and gas to control the temperature of the furnace.

22. In an open hearth gas fired regenerative furnace having a set of heat regenerators adapted to alternately heat the air supplied to said furnace and to be heated by the hot products of combustion from said furnace and a series of gas burners on either side of said furnace, the combination of a valve for reversing the direction of flow of gas through said regenerators and furnace, means for supplying air and gas to the burners and means actuated by the passage of gas to the furnace for automatically shifting in any desired sequence the reversing valve and alternately opening and closing the gas supply to either side of said furnace.

In testimony whereof I afiix my signature.

CARL J. WRIGHT.