US1736753A

US1736753A - Ments

Info

Publication number: US1736753A
Authority: US
Publication date: 1929-11-19
Anticipated expiration: 1946-11-19

Description

NOV. 19, 1929. R sM|TH 1,736,753

FURNACE REGULATION Original Filed Jan. 19, 1927- 70 OTHER FuRA/A C55 Inventor":

Avthur R Sm'HC h,

y His Attorn ey Patented Nov, 1%, 1929 ARTHUR B. SMITH, F

SCHENECTAD'Y, NEW YORK, ASSIGNGR, BY MESNE ASSIGN- MENTS, T0 BAILEY METER COWANY,

A CORPORATION OF DELAWARE summon naeunarrou Application filed January 19, 1927, Serial l lo. 162,198. Renewed April 10, 1929.

The present invention relates to furnaces used to generate elastic fluid or vapor, such as steam, for example.

The object of the invention is to provide an improved automatic regulating system, and, for the consideration of what I believe to be novel and my invention, attention is directed to the accompanying description and the claims appended thereto.

In the drawing, the figure is a diagrammatic view of a system embodying my inven tion.

Referring to the drawing, 1 indicates a furnace used to generate steam in a boiler 23. Fuel is supplied to the furnace by a suitable fuel feeding means 3 such as, for example, a suitable stolrer. The fuel feeding means is operated by an electric motor at, the arrangement being such that when the speed of the motor increases the amount of the fuel supplied to the furnace increases, and when the speed of the motor decreases the amount of the fuel supplied to the furnace decreases.

Electric motor 4 is connected to supply lines 5 and 6 by conductors 7 and 8. 9 indicates the field of the motor, and in series with it is a regulating resistance 10 adapted to be cut into and out of circuit by a Contact arm 13. which is moved by a reversing electric motor 12. By operating motor 12 in one direction or the other, the speed of motor i can be varied, and hence the amount of fuel fed to the furnace can be increased or decreased.

13 indicates a conduit through which the gases, that is, the products of combustion, from the furnace are discharged, and 14 indicates a suction blower for increasing and decreasing the draft on the .furnace. Suction blower id is driven by electric motor 15 connected to supply lines 5 and (S by

conductors

16 and 17. Wluan the speed of motor 15 is increased, the draft on the furnace increased, and when the speed of motor 15 decreased, the draft on the furnace is decreased. Suction blower it is to be taken typical oi any suitable means "for regulat ing the quantity of air supplied to the furnace.

18 indicates the field of motor 15, and arm ranged series with it is a regulating resistance 19 adapted to be cut into and out of circuit by a contact arm 20 which is moved by a reversing electric motor 21. When motor 21 is operated in one direction, it serves to sheet an increase in the speed of motor 15, and hence the quantity of air supplied to the furnace, while when it is operated in the other directioh it serves to effect a decrease in the speed of motor 15, and hence decreases the amount of air supplied to the furnace.

22 indicates the steam drum of furnace 1. lit is connected by a discharge conduit 23 to a header 2%., Furnace 1 is one furnace of a number, all of which supply steam to common header 24;.

25 is an electric flow meter for measuring the amount of air flowing through the furnace. it may be of any suitable type. in the present instance there is indicated an electric flow meter of the type disclosed in the application of Louis W. Thomson, Serial No. 342,220, filed October 27, 1924:. It comprises casing 26 which contains a movable element which may be in the form of an inverted bell 27, the lower edge of the bell beingsealed by liquid contained in an annular chamberilti. The opposite sides of bell 27 are connected by trailing and leading; pressure pipes 29 and 30 to a conduit 31 through which air for combustion purposes is supplied to they furnace. lln conduit 31 is a steam heating coil 32 which may be utilized for heating the air supplied to the furnace, and in the present instance the air flow meter is shown as having its trailing and leading pipes 29 and 30 con nected on opposite sides or coil 32, the drop in pressure across the coil serving as a measure oi the air flow, as is well understood. Bell 2'? is pivotally connected to a lever 33, one end otwhich is pivoted to a fixed post 3a. the other end ot" lever 33 is connected by a linlr 35 to an armature 36., upon which is a closed winding 37. in operative relation to armature 36 is a field structure comprising a winding 38 which is connected to lead Wires 39 and d0. The tlow meter mechanism illustrated serves to eii'ect oscillating movement oi armature 36 in response to changes in the rate of flow of air to the boiler, and such oseillating movement varies the current in the .rent which is a measure of the air flowing to the furnace.

Conductor 39 is connected to supply line 5.

Conductor 40 is connected to one end of a coil 41 of a balanced relay 42, the other end of the coil being connected by a conductor 43 to supply line 6. There thus flows through c011 41 of balanced relay 42 a current proportional to the amount of air flowing to the furnace.

44 indicates. an electrical coal meter for measuring the amount of coal supplied to the furnace. It may be of any suitable type, the essential thing being that it produces a flow of electric current which is a measure of the amount of coal supplied to the furnace. In the present instance it is shown as being an instrument of the general type of that disclosed in the patent to Thomson & McNairy, No. 1,560,951, patented November 10, 1925. The leg 45 of the meter is connected by a pipe 46 to a device which produces a pressure proportional to the speed at which the stoker is driven, and the leg 46 of the instrument is connected by a pipe 47 to atmosphere. The pressure applied to the liquid in leg 45 effects a deflection of it, causing a fiow of current in the primary winding 48 of the instrument which is proportional to the pressure and hence to the amount-of fuel supplied'to the furnace; this being the mode of operation of the construction disclosed in the above referred to patent, as is now well understood. The circuit of coal meter 44 comprises a conductor 49 which is connected to supply line wire 5 and a conductor 50 which is connected to one'terminal of a coil 51 of relay 42. The other terminal of coil 51 is connected by a conductor 52 to supply'line 6. It will thus be seen that the current flowing in coil 51 is one proportional to the amount of fuel-being supplied to boiler 1. Coils 41 and 51 of relay 42 are oppositely wound so that they tend to oppose each other.

Relay 42 has a movable contact 53 which is connected by conductor 54 to supply line 6,

and two stationary contacts 55 and 56. Contact 55 is connected by a conductor 57 to the field winding 58 of motor 21, and contact 56 is connected by conductor 59 to field winding 60 of motor 21.

Field windings

58 and 60 are connected through the armature of motor 21 to supply line 5 by conductor 61. With this arrangement when movable contact 53 engages contact 55 it operates motor 21 in one direction, while when it engages contact 56 it operates motor 21 in the other direction.

Connected to header 24 is an electric pressure gage 62 of any suitable type. In the present instance,' it is indicated as being an instrument of the same general type as is the coal meter 44; it being understood that as a pressure gage it measures a differential pressure, this being the difference in pressure between that of the atmosphere and that in header24. To this end, the leg 63 of the instrument is connected to header 24 by a pipe 64, and the leg 65 is connected by a pipe 66 to atmosphere. As shown in the drawing, the leg 65 is made long on account of the comparatively high pressure to be measured. It will be understood that the pressure in header 24 maintains a head-of mercury .in leg 65 and that as the pressure in the header increases and decreases the mercury rises and falls in leg 65. In the casing 67 of the instrument is a transformer element the same as that indicated diagrammatically in connection with the casing of coal measuring means 44.

With the foregoing arrangement there is produced in the circuit of the pressure gage a flow of current which is proportional to the pressure in header 24. This circuit coniprises a conductor 68 which is connected to supply line 5, and a conductor 69 which is connected to one terminal of a coil 70 which forms a part of a master relay 71. The other terminal of coil 70 is connected by a con- I ductor 72 to supply line 6. There is thus produced a flow of current in coil 70 whichis a measure of the pressure in header 24. The electric pressure gage indicated is shown only by way of example. Any suitable instrument capable of producing a flow of current proportional to pressure may be utilized.

Master relay 71 comprisesamovable contact 73 connected by a conductor 74 to supply line 6, and adapted to engage either of two stationary contacts 75 and 76. Stationary contact 75 is connected by a conductor 77 to one of the field windings 80 of motor 12, and contact 76 is connected by a conductor 81 to the other field winding 82 of motor 12. Motor field windings 80 and 82 are connected through the armature of motor 12 to supply line 5 by a conductor 83. \Vith this arrangement when movable contact 73 engages contact 75, motor 12 is operated in one direction, while when it engages contact 76, motor 12 -is operated in the other direction.

Relay 71 is a master relay for controlling all the furnaces of a battery in accordance with an operating condition of the furnaces, the operating condition used in the present instance being the pressure in the common steam header. 85 indicates connections leading to other furnaces, and 86 indicates the balance relay for another of the furnaces which has been designated on the drawing furnace No. 2.

Associated with conduit 23 is an electric flow meter in the circuit of which is produced a flow of electric current which is a measure of the flow of steam through conduit 23. Any suitable type of electric flow meter may be used. A flow meter of the type shown in the before-mentioned patent to Thomson & 30 McNairy is indicated in the present instance. It comprises a casing 87 having its leading and trailing legs connected by pipes 88 and 89 to a pressure difference creating device 90 in steam pipe 23. The circuit of this flow meter is connected by conductors 91 to a Winding 92 which forms a part of relay 42. Thus there is a flow of electric current in winding 92 which bears a definite relation to the rate of flow of steam through conduit 23. In other words, the current in coil 92 is proportional to and varies with the load on boiler 2. Coil 92 is wound in a direction opposite to that of coil 41, whereby it tends to oppose coil 41. Or, otherwise considered, it is wound in a direction to assist winding 51. The operation is as follows: Assume that the various furnaces are burning and that each is supplying vapor through its discharge conduit 23 to header 24. Assume also that the desired pressure exists in header 24.

Under these circumstances, the current flowing through the coil 70 of master relay 71 will be such as to maintain contact 73 midway between stationary contacts 75 and 76, and the various parts will be in the positions indicated in the drawing. Motor 4 of each furnace will be running to supply the required amount of fuel to its furnace, and the motor 15 of each furnace will be running to effect the desired supply of air to its furnace. Assuming also that the desired ratio of fuel to air exists in the case of each furnace, then the flow of current through coils 41, 51 and 92 of each balanced relay 42 will be such as to maintain movable contact 53 midway I bet-ween stationary contacts and 56.

If now the pressure in header 24 increases, indicating a decrease in demand for vapor, then pressure gage 67 will be operated to effect an increase in the amount of current flowing through coil 70 to master relay 71. This will cause movable contact 73 to engage one of the stationary contacts 75 or 76, it being assumed in the present instance that it engages a contact 75. When contact 73 engages contact 75 it closes a circuit on the field 80 of motor 12, which ma be traced as follows: supply line 6, con uctor 74, contacts 73 and 75, conductor 77, field winding 80, and conductor 83 to supply line 5. This serves to operate motor 12 in a direction to decrease the rate of fuel supply to the furnace. When the rate of fuel supply to the furnace decreases, the current flowing in the fuel meter circuit decreases, whereupon relay 42 becomes unbalanced, moving its contact 53 into engagement with one of the contacts 55 or 56; for example, contact 55. When contact 53 engages contact 55 it closes the circuit of the field winding 58 of motor 21, operating motor 21 in a direction to decrease the amount of air supplied to the furnace, the operation continuing until relay 42 is again balanced. The decrease in the amount of fuel and air supplied to the furnace efi'ects a decrease in the amount of vapor generated, .and hence brings the pressure in header 24 back to normal value, and relay contact 73 back to its neutral position.

If the pressure in header 24 decreases, indicating an increase in the demand for vapor, then master relay 71 is operated to move contact 73 into engagement with contact 76, thereby operating motor 12 in a direction to effect an increase in the supply of fuel for furnace. When this occurs, relay 42 becomes unbalanced, contact 53 moving into engagement with contact 56, and effecting operation of motor 21 in a direction to effect an increase in the amount of air supplied to the furnace. The increased fuel and air supplied to the furnace serve to effect an increase in the amount of vapor generated, thereby bringing the pressure in header 24 back to normal value.

Balance relay 42 serves to maintain at all times the desired ratio between the fuel flow and the air flow, and, as will be clear, if at any time the desired ratio does not obtain, contact 53 will be moved into engagement with either contact 55 or contact 56 to effect an increase or a decrease in the rate of flow of air to the furnace, the operation continuing until the desired fuel-air ratio is ,again established, when contact 53 will again occu y its central neutral position.

n connection with the operation of a boiler furnace, it is desirable to increase the ratio of air to fuel with increase in the boiler load, to decrease the ratio of air to fuel with decrease in the boiler load. This function in" the present instance is performed by the coil 92 connected to the flow meter which meas ures the flow of vapor through conduit 23. With the arrangement shown, it will be seen that when thesteam flow increases, coil 92 serves to oppose coil 41 to a greater extent, which means, therefore, that with the same fuel flow a larger proportional air flow is re quired in order to balance the relay. 0n the other hand, upon decrease in the amount of steam flowing in conduit 23, coil 92 opposes coil 41 to a lesser extent, which means that a proportionately smaller amount of air will be required in order to balance the relay. With the above described arrangement, therefore, it will be seen that automatically the ratio of air flow to fuel flow is increased and decreased with increase and decrease of rap the boiler load. I regard this as being an important feature of my invention.

In connection with the operation, it should be understood that when the steam pressure varies in header 24, master relay 71 effects operation of all the boiler furnaces connected into the system simultaneously. On the other hand, the balance relay 42 of each furnace serves to adjust only the fuel and air of the furnace to which it isappurtenant.

The subject matter of claims 9 to 15 herein have been divided out from my application- Serial No. 82,625, filed January 20, 1926.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, and I desire to have it understood that the apparatus is only illustrative and that the invention is to be carried out by other means.

What I claim as new, and desire to secure by Letters Patent of the United States, is:

1. In a furnace control system, the combination of means for supplying fuel to the furnace, means for supplying air to the furnace, means which produces a flow of current which is a measure of the fuel supplied to the furnace, means which produces a flow of current which is a measure of the air supplied to the furnace, a balanced relay connected to said two last-named means, means responsive to changes in demand on the furnace for effecting adjustment of the fuel and air in accordance with the load, said fuel and air beingaadjusted relatively to each other through the intermediary of said bal anced relay, and means for modifying the operation of the balanced relay in accordancc with the load on the furnace.

2. In a furnace control system for a plurality of furnaces, the combination of means for supplying fuel to each furnace, means for supplying air to each furnace, means associated with each furnace for effecting a flow of electric current proportional to the fuel and a flow of current proportional to the air, a balanced relay connected to said last-named means, means responsive to changes in the total demand on the furnaces for effecting adjustment of the fuel and air of each furnace in accordance with the total load, the fuel and air for each furnace being adjusted relative'ly to each other through the intermediary of said balanced relays, and means for modifying the operation of the balanced relay of eachfurnace in accordance with theloadon such furnace.

3. In a furnace control system for a plurality of furnaces, the combination of means for supplying fuel to each furnace, means for supplying air to each furnace, a' device which changes upon a change in the total demand on the furnaces, a master relay connected to said device, means controlled by said master relay for regulating the fuel and air-supplying means of each furnace, and means for varying automatically the fuel-air ratio of each furnace in accordance with the loads on the respective furnaces.

4. In a furnace control system for a plurality of furnaces, the combination of means for supplying fuel to each furnace, means for supplying air to each furnace, means associated with each furnace for effecting a flow of electric current proportional to the fuel and a flow of current proportional to the air, a balanced relay connected to said last-named means, a measuring device which produces a flow of electric current which changes upon a change in the total demand on the furnaces, a master relay connected to said measuring device, means controlled by said master relay for effecting regulation of the fuel and air to all the furnaces, the fuel and air to each furnace being adjusted relatively to each other by said balanced relays, and means for modifying the operation of said relays in accordance with the load on the furnace with which it is associated.

5. The combination with a furnace having means for regulating the amount of air and fuel supplied to it, of a measuring device for effecting a flow of electric current proportional to the air supply, a measuring device for effecting a flow of electric current proportional to the fuel supply, a balanced relay connected to said measuring devices, a device responsive to changes in demand on said furnace. means controlled by said last-named device for effecting adjustment of the fuel and air in accordance with the demand. on the furnace, the air and fuel being adjusted relatively to each other by said balanced relay, and means for modifying the operation of said relay in accordance with the load on the furnace.

6. The combination with a furnace having means for supplying fuel and means for supplying air thereto, of a control system comprising means which produces aiiow of electric current which is a measure of the fuel supplied to the furnace, means which produces a flow of electric current which is a measure of the air supplied. to the furnace, a balanced relay connected to said two lastnamed means, means controlled by said balanced relay for adjusting the fuel and air relatively to each other, and means for modifying the operation of said relay in accordance with the load on the furnace.

7. The combination with a furnace having automatic means for. varying the amount of fuel and air supplied to the furnace in accordance with the demand on the furnace, of means for maintaining the desired relation which produces a flow of electric current between fuel and air for all loads comprising an electric circuit having means therein which effects a flow of current whlcn 1s a measure of the airflow, an electric circuit having means therein which effects a flow of current which is a measure of the fuel flow, a balanced relay in said circuits, means controlled by said relay for maintaining the desired ratio between fuel and air at all loads, and automatic means responsive to the load on the furnace for varying the ratio between the fuel and air.

8. The combination with a furnace, of a balanced relay having opposed windings, means for effecting a flow of current in one of said windings which varies with the fuel supplied to the furnace, means for effecting a flow of current in another of said windings which varies with the air supplied to the .furnace, means for effecting a flow of current in another of said windings which varies with the load on the furnace, and means controlled by said relay for maintaining the desired ratio between fuel and air.

9. In a furnace control system, the combination of means for supplying fuel to the furnace, means for supplying air to the furnace, means .which produces a flow of cur-.

rent which is a measure of the fuel supplied to the furnace, means which produces a flow of current which is a measure of the air supplied to the furnace, a balanced relay connected to said two last-named means, and means responsive to changes in demand on the furnace for efiecting adjustment of the fuel and air in accordance with-the load, said fuel and air being adjusted relatively to each other through the intermediary of said balanced relay.

10. In a furnace control system for a plurality of furnaces, the combination of means for supplying fuel to each furnace, means for supplying air to each furnace, means associated with each furnace for effecting a flow of electric current proportional'to the fuel and a flow of current proportional to the air, a balanced relay connected to said last-named means, and means responsive to changes in the total demand on the furnaces for effecting adjustment of the fuel and air of each furnace in accordance with the total load, the fuel and air for each furnace being adjusted relatively to each other through the intermediar of said balanced relays.

11. In a urnace control system for a plu rality of furnaces, the combination of means for supplying fuel to each furnace, means for supplying air to each furnace, means associated with each furnace for effecting a flow of electric current proportional to the fuel and a flow of current proportional to the air, a balanced relay connected to said last-named means, a measuring device which produces a flow of electric current which changes upon a change in the total demand on the furnaces, a master relay connected to said measuring device, and means controlled by said master relay for effecting regulation .and air.

of'the fuel and air to all the furnaces, the

fuel and air to each furnace being adjusted relatively to each other by said balanced relays. v

12. The combination with a furnace having means for regulating the amount of air and fuel supplied to it, of a measuring device for effecting a fiow'of electric current proportional to the air supply, a measuring device for effecting a flow of electric current proportional to the fuel supply, a balanced relay connected to said measuring devices, a device responsive to changes in demand on said furnace, and means controlled by said last-named device for effecting adjustment of the fuel and air in accordance with the demand on the furnace, the air and fuel being adjusted relatively to each other by said balanced relay.

13. The combination with a furnace having means for supplying fuel and means for supplying air thereto, of a control s stem comprising means which produces a ow of electric current which is a measure of the fuel supplied to the furnace, means which produces a flow of electric current which is a measure of the air supplied to the furnace, a balanced relay connected to said two last-named means, and means controlled by said balanced relay for adjusting the fuel and air relatively to each other.

14. The combination with a furnace having automatic means for varying the amount of fuel and air supplied to the furnace in accordance with the demand on the furnace, of means for maintaining the desired relation between fuel and air for all loads comprising an electric circuit having means ing the desired ratio between fuel and air at all loads.

15. The combination with a furnace of a balanced relay havin opposed windings, means for effecting a do of said windings which varies with the fuel su plied to the furnace, means-for effecting a ow of current in another of said windings which varies. with the air supplied to the furnace, and means controlled by said relay for maintaining the desired ratio between fuel means controlled by said relay for maintain- In witness whereof I have hereunto set my w of current in one