US1645350A - Apparatus for regulating air supply - Google Patents

Description

1 645 350 Oct. J' H I APPARATUS FOR REGULATING AIR SUPPLY Filed March 23, 1926 IN VEN TOR Josef f/e/nz flame/he ATT NEY Patented Oct. 11, 1927.

UNITED STATES 1,645,350 PATENT OFFICE.

JOSEF HEINZ REINEKE, OF BOCHUM, GERMANY.

APPARATUS FOR REGULATING AIR SUPPLY.

Application filed March 23, 1926, Serial No. 96,825, and in Germany April 11, 1925 This invention relates to apparatus for the regulation of the air supply to burners for the purpose of maintaining proper combustion conditions and particularly to the provision of means whereby such regulation is dependent upon the compositionof the combustion gases. The chief object of the inven-- tion is to provide for continual maintenance of the necessary air supply forperfeot combustion, that is to say sufficient to ensure complete combustion with the minimum of excess air.

It is well known that there are apparatus for the regulation of air supply to burners,

which provide for regulation dependent on the composition of the gases. Inasmuch as these are so arranged as to be dependent on the CO content of the gases only, and do not take any consideration of the other components, especially CO, they have found little or no application in industry. The CO content of the gases cannot be considered a criterion for proper burning, as a decrease of CO content may be caused by 2.5 lack of air supply as well as by excess of air supply. With an excess of air supply there is substantially complete combustion of the gases, but the non-utilized air also causes an increase in the gas volume (flue gases) so that the percentage of CO in the flue gases is decreased. With insufficient air, it is the unburned combustible gas which causes decrease in CO content, and also the incomplete combustion, combined with a formation of high 00 content, at the cost of the CO content. Whenever a regulator is controlled only by the ()0 content of the flue gases, the combustible air supply is therefore frequently increased when it should be decreased, and vice versa. It is therefore necessary that the CO content of the flue gases be taken into consideration in the control of the regulator.

It is an important object of the present nvention to provide means whereby the variation in the air supply upon a decrease in the CO content of the combustion gases is always caused to take place in the proper direction, so that if the decrease in the CO content is due to" excess air then the air supply is decreased, while if the decrease in' CO content is due to insufficient air then the air supply is increased. This object is accomplished by making the regulation dependent upon GO content of the gases as wellas upon CO content, in such manner that if the flue gases are free from G0 a decrease in the CO content causes a decrease in the supply of air for combustion while on the other hand if CO is present in the flue gases a decrease in CO content causes an increase n the air supply. An equilibrium condition 1s thus always maintained such that the flue gas is free from C0 or that the CO content 1s at a minimum, while the CO, content is at a maximum. r

The accompanying drawings illustrate embodiments of this invention and referring thereto:

Fig. 1 is a semi-diagrammatic representation of apparatus according to my invention.

Fig. 2 indicates the manner of connection of such apparatus to a furnace.

The apparatus shown in Fig. 1 comprises a burner or combustion chamber 1, gas supply means 2 for supplying combustible as thereto and air supply means 3 for supp y- -ing air to the burner for combustion of such gas. A suitable flow-controlling device, such as damper 4, is provided in air suppl flue 3 and is connected by means of sha t 5 suitable operating or regulating means which may for example be of the two-motor type as described in my United States Patent No. 1,480,837. In such case the shaft 5 may be connected through suitable differential gearing in gear casing 6 to the shafts of two electric motors 7 and 8 as described in my said patent, in such manner that when the two motors are running at equal speed shaft 5 is held stationary, while an increase in speed of motor 7 causes said shaft to turn in such direction as to close damper 4 and an increase in speed of motor 8 causes the shaft to turn in the opposite direction and open said damper. Said motors are operated by electric current supplied thereto through wires 9 and 10 from any suitable source of electric current. The motors 7 and 8 may be of the wound rotor induction type, so as to provide for variation in speed thereof. The rotor circuit of motor 7 may be connected by wires 13 and 14 to opposite ends of resistance 15, While the rotor circuit of motor 8 may be connected by wires 16 and 17 to resistance 18. As shown in Fig. 2, a flue gas analysis device 19, for example a Siemens flue gas recorder which measures electrically both the CO and CO content of the flue gases, ma be connected by pipe 20 to the flue or stac 21 leading from fur- 45, and wire 14, back to the motor.

nace or other combustion or heating device 22 with which the burner 1 is associated, so asto continually conduct through such gas analysis device a certain small proportion of the products of combustion from said burner. Such gas recorder is provided with a needle or indicator 24 indicating 002C011- tent of the gases, and with an indicator 25 for the CO content. Needle 24 may be pivoted at 26 and may be so operated that its lower endmoves to the right with increasing CO content. Contact members 27 and 28 may be provided at the' lower end of said needle, adapted to make contact respectively with fixed contact members 29 and 30 upon movement of the needle. Needle 25 may be pivoted at 32 and may be so operated that its lower end moves to the left with increasing CO content. Contact members 33 and 34 may be provided at its lower end vfor making contact with contact members 35 and 36 respectively in the movement of the needle. Theelectrical connections may be completed as follows. WVire 38 may lead from contact 29 to wire 13; wire 39 from contact 27 to the mid-point of resistance 15; wire 40 from such mid-point to contact 36; wire 41 from contact 28 to the mid-point of resistance 18; wire 42 from contact 30 to wire 16; wire 43 from contact 35 to wire 17; wire 44 from contact 33 to wire 16; and wire .45 from contact 34 to wire 14.

The operation of the apparatus above described ma be described as follows:

The position of the contact members is such that under perfect combustion conditions, that is to say when there is substantially no CO in the flue gases and when the CO content is at a maximum, contact member 34 is in contact with contact member 36 and contact member 28 is in contact with contact member 30. Under these conditions the rotor circuit of motor 7 is as follows: wire 13, the upper half of resistance 15, wire 40, contact members 36 and 34, wire The rotor circuit of motor 8 is at this time as follows: wire 16, wire 42, contact members 30 and 28, wire 41, the lower half of resistance 18, and wire 17 back to the motor. Resistances 15 and 18 being of the same value it is therefore seen that the rotor circuits of the-two motors contain equal resistances and that the motors therefore rotate at equal speed and hold the damper in the same position. Theaction of the device is such that as long as there is no CO in the flue vgases and contact therefore remains closed between members 34 and .36, a decrease in CO content causes the regulator to operate in one direction while upon breaking connection between members 34 and 36 due to the presence of CO in the flue gases a decrease in the CO content causes a reverse operation of the regulator.

Assuming first a condition of no CO in the flue gases so that contact remains closed between members 34 and 36, if the CO content decreases the first efiect is to break the connection between members 28 and 30 so that the whole of resistance 18 is placed in the rotor circuit of motor 8. This causes a decrease in the speed of said motor which in turn causes the damper to be moved toward closed position and thus decreases the air supply. It is seen that this is the desired effect since an increase in CO content without any CO in the gases indicates an excess of air. If the movement of damper 4 effected by this operation is not sufliciently rapid to quickly restore the CO content to the desired value indicator needle 24 will continue to move to the left and close connection between members 27 and 29. Resistance 15 is thus completely short-circuited causing an increase in the speed of motor 7. Motor 7 will then be rotating at a higher speed than normal while motor 8 rotates at a speed below normal giving a still more rapid movement of damper 4 to decrease the air supply. This motion is continued until the CO content is restored to the desired value.

Assume next that the air supply becomes deficient causing the presence of suflicient CO inthe flue gases to break connection between contacts 34 and 36 and close connection between contacts 33 and 35. It will be understood that under these conditions the CO content will decrease, breaking connection between contact members 28 and 30. The rotor circuit of motor 7 will therefore include the entire resistance 15 while resistance 18 will be entirely short-circuited from the circuit of motor 8 through wire 43, contact members 35 and 33, and wire 44. The speed of motor 8 will thus be increased while the speed of motor 7 will be decreased, causing damper 4 to be moved toward open osition and increasing the air supply suficient- 1y to again provide complete combustion together with absence of CO and maximum GO content.

It will be understood, of course, that other types of regulators may be used in connection with my invention, and that any suitable device may be employed for measuring the CO and CO content of the combustion monoxide content of the combustion gases produced by said burner, and means associated with said measuring means and adapted to so control the operation of said regulating means as to maintain such an air supply to the burner as to provide a maximum carbon dioxide content and a minimum carbon monoxide content in said combustion gases.

2. An apparatus comprising, in combination with a burner and with means for supplying air and combustible gas thereto and means for receiving products of combustion therefrom, a flow-controlling device in said air supplying means, a regulator for said flow-controlling device, means for measuring the carbon dioxide and carbon monoxide content'of said products of combustion, control means associated with said carbon diox- 1de measuring means and adapted to control said regulator so as to cause operatlon thereof 1n accordance with variations 1n the carbon dioxide content of the gases, and control means associated with said carbon monoxide measuring means and adapted to cause said first-named control means to cause operation of said regulator in one direction upon a decrease of carbon dioxide content in the absence of carbon monoxide and in the other direction upon a decrease of carbon dioxide content in the presence of carbon monoxide.

In testimony whereof I have hereunto subscribed my name this 23rd day of February,

J OSEF HEINZ REINEKE.

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