US1563988A - Pressure-controlled regulating means for furnaces - Google Patents

Description

Dec. 1 1925- c. 1.. HOWSE PRESSURE CONTROLLED REGULATING MEANS- FOR FURNACES Filed March 2', 1922 WATER fKlSSl/AE i 72 07* 606776 SI. fowae q ,55/ MMMMM% Patented Dec. 1, 1925. I

UNITED STATES PATENT oer-mg,-

cunrrs L. nowsn, on Burton, MICHIGAN, ASSIGNOR T0 01mm nmrnnnnoumron cournw, A conroim'rron or DELAWARE.

PRESSURE-CONTROLLED REGULATING MEANS I03 FURNACES.

Application filed March 2, 1922. Serial No. 540,651.

To all whom it may concern:

Be it known that I, CURTIS L. Howsn, a citizen of Great Britain, residing at Detroit, in the county of Wayne and State of Michigan, have invented certain new and useful Improvements in Pressure-Controlled Regulating Means for Furnaces, of which the following is a specification.

In the operation of steam-boiler furnaces, it is desirable automatically to control the conditions which affect combustion-rate so that, as boiler pressure rises above a desired quantit combustion may be decreased, and

whent e boiler pressure falls, the furnace may be conditioned for increased combustion. Two of the regulable conditions affecting a forced-draft furnace are air supply rate and stack-damper adjustment, and 1n many installations it is highly desirable to vary these conditions coincidently to tend to malntain substantially uniform pressure conditions in the combustion space of the furnace.

One of the objects of my invention is to provide a novel and efiicient control system for furnace regulation, accordantly with pressure conditions in the boiler. A further object of my invention is to provide novel and efficient mechanism for control, which will be simple and rugged in construction, adaptable to installations widely varying in detail requirements, and effecting all control operations in a manner at once sensitive, forceful and smooth. Other and further objects of my invention will become apparent from the following description, taken in conjunction with the accompanying drawing, wherein I have illustrated a single embodiment of my invention for purposes of disclosure, in a system of boiler-furnace regulation. I

In the drawings Fig. 1 is a diagrammatic side elevation with parts broken away showing the application of m invention to control of an underfeed-sto er furnace equipment; Fig. 2 is an enlarged view with parts broken away showing control mechanisms detached; Fi 3 is a reduced plan view of the construction shown in Fig. 2.

The boiler 10 is shown as served by a furnace having stack 11 equipped with damper 12 to e regulated, and where, as shown, an underfeed stoker 13, or other grate structure requiring forced draft is employed, the air supply may be afforded such arm 17 may have a sector 19 to which is connected the chain 20 constituting part of a connection to a control-engine 21, the construction and operation of which adapts it for controlling actuation of either or both the rheostat and the stack-damper. The rheostat chain 20 is connected to the vertical extension 22 of piston rod 23, and to such extension is also connected the damperpositionmg means, shown as gear 24 on the damper shaft operated by sector rack 25 of a pivoted lever 26 slotted for variable leverage connection with a link 27 which is pivotally connected to the part 22 or a lug thereon. When piston rod 23 draws down the connection 22, it moves the rheostat arm to cut resistance into the motor circuit 28, to slow the motor 15, and rotates the stack dam er in closing direction.

The regulatlng engine shown comprises a hydraulic cylinder 30 into which liquid may be introduced or from which it may be permitted to escape near one end to act on piston 31, the other end of the cylinder having only a drain connection to a drain pipe 32 liquid-introduction and eductionbeing controlled by a valve structure 33 which is under joint control of a pressure responsive device 34 (connected with the boiler) and of the piston itself.

In the simple and effective form of valve mechanism shown, a single port in the upper end of the cylinder, as shown at 36, serves both for liquid supply and eduction, such port communicating with a valve-cylinder 37 in which slides the double-headed valve 38. The water supply pipe 39, maintained under a constant water-pressure, opens to the valve-clearance between the heads, so that when the valve is depressed below the normal position shown it opens communication between the supply pipe 39 and the port 36. In normal position, as shown, the

valve opens connection between port 36 and a relief port 40 connected with the drain pipe 32. An open channel ,43 may connect this relief area with the space above the upper valve head, so balancing the valve.

The pressure-responsive device 34 and the piston 31 are so, connected with the valve. for joint control thereof, that response of said pressure-responsive device to increase pressure acts to move the valve downward toward in-flow position for admission of more liquid to the cylinder, whereas downward movement of the piston, resulting from such fluid in-fiow, tends to raise the valve toward out-flow or relief position. With such an organization for coaction be tween the valve, the pressure-responsive device, and the piston, it follows that opening of the valve due to action of the pressure responsive device will result in piston-movement which will act upon the valve to neutralize the valve, moving it in a direction opposite to that in which it is moved by the pressure-responsive device. Specific mechanical organization, for this joint, and cooperative, action may take various forms, and as to details of valve structure, pressure-responsive actuating mechanism and mechanism to be actuated by piston movement, many changes may be wrought from the specific construction which I illustratively show.

For operating the single one-piece valve preferably used, lever 45 has pivotal connection 46 to the valve stem and pivotal connections 47 and 48 respectively to the piston-controlled part and to the pressure-responsive part. Pivot 48 receives link 49 adjustable in length as by the turn-buckle 50 and connected at its lower end to the movable element of the pressure-responsive device 34. Such pressure-responsive device may be of bellows-diaphragm type or other character for expansion, but is shown as a gang of parallel Bourdon tubes 51 having at one end a common steam connection 52 to the boiler and at the other end a common closing union 53 to which the lower end of link 49 is pivoted. A weight 67 on lever 45 is movable to variably load the device.

Pivot 47 receives the upper end of a link,

- 55, the lower end of which is vertically movable by the piston 31, This link engages crank pin 56 positioned in one of the holes 57 located at difi'erent radial distances from the center of a .rockin head 58 which is mounted in the bracke 59 and which has a non-circular shaft-portion 60 connectible with a lever 61 so as to bring any one of theholes 57 to appropriate working osition. This lever 61 has its slotted en 62 engaged by a pin on the vertical rod 63 carried by rod 22, movable with piston 31.

Where an electric motor is controlled in the manner hereinbefore stated, it is deances, as follows,

sirable that means be provided whereby rupture of the motor circuit may be made to throw the rheostat to full-resistance condivalve member 38 releasable from the controlling lever system, and independently actuatable, upon rupture of the clrcuit 28, Thus, as shown, lever 45 may carry an electro-magnet 65 connected in the circuit 28, its armature 66 carrying the pivot 46 for the valve stem and being normally frozen or fully attracted so as normally to rigidify the connection of the lever 45 with said valve. Thus, as long as the magnet is energized, the lever element acts as though directly connected with the valve stem, but should the motor circuit break and the magnet become de-energized, it releases its armature 66 which falls, depressing the valve regardless of the position or operation of the lever 45.

The operation of the regulating appliwill now apparent: Under normal operating conditions assume the boiler to be met up to normal pressure and the regulating appliances to be positioned as illustrated in Fig. 2. Demand on the boiler causes a drop in pressure which should be met by an increase of air supply from fan 14 and a commensurate opemng of damper 12 in the stack. 1 The pressure drop is communicated by pipe 52 to the Bourdon spring pressure-responsive device 51, so that the springs contract, drawing down link 49 which rocks lever 45 on pivot 47. The magnetic connections 65, 66 being rigidified under normal conditions, valve member 38 is raised, opening the port 36 to the relief port 40 and outlet pi 32. The liquid normally filling the cyhndis r 30 above piston 31 therefore flows out of the cylinder, pending closure of the valve, since weight 18 on the rheostat arm 17 constantly tends to raise the piston. As the piston rises so does the slotted end of lever 61, and the crank pin 56 draws down the link 55, lowering ulcrum 47 so that lever 45, now fulcruming on pivotal connection 48, has its valvecarrying end depressed, and this action continues until valve 38 closes. Thus the piston comes to rest in a vertical position consistent with the position taken by the ressure-responsive device in its contractlon due to pressure-reduction. The stated piston movement is communicated to both the rheostat arm and the-damper, the movable rheostat contact moving clockwise to cut out resistance, speeding up the motor 15 and therefore the blast fan 14, and the damper 12 being moved toward open position. When, now, boiler ressure rises, the pressure-responsive dance 34 expands, elevating link 49 and rocking lever 45 on point 47 as a fulcrum, so depressing the valve 38. This opens communication between the water suptlon and to this end I preferably make the ply pipe 39 and the cylinder port 36, so that water under adequate pressure flows into the cylinder, forcing down the piston 31, with the result that, through the piston-controlled leverage system, link 55 is forced upward, rocking lever on 48 as a fulcrum until valve 37 is raised to its neutral position shown, cutting off the water supply to port 36. This operation is, of course, converted into a resistance-increasing actuation of the motor-rheostat and a damper-closing operation. Magnet 65 serves only as a protective device in connection with the motor, and in the event of'rupture of the motor circuit the resultant de-energization of the magnet frees its armature 66 to drop, regardless of the position of lever 45, driving own the valve 38 to open communication between liquid supply pipe 39 and the cylinder, so that piston 31 is forced down through its full range of movement, turning the rehostat to full-resistance position and closing the damper. Of course where fanspeed control is effected through some actuating device other than an electric motor, electro-magnetic connection may be eliminated, and where installation is made in a natural draft furnace merely to govern the damper adjustment, the rheostat connections ma be omitted and the counterbalancing weight 18 transferred to the sector-carrying portions of the damper lever 26. Of course I do not limit myself to the variations specifically suggested, as many changes may be made within the spirit of my invention and the scope of the appended claims.

I claim:

1. The combination with a steamboiler, a forced-draft furnace therefor having a draft-fan, an electric motor for driving said fan and speed-changing means for said motor, of a pressure-controlled engine for operating sa1d speed-changing means com rising a cylinder, a piston therein loade to tend to move toward one end of said cylinder and operatively connected with said speed-changing means to'actuate the latter,-

said valve for moving the same in either direction, sa1d connections including a normally energized electro-magnetic device having a part arranged, when de-energized, to move said valve to one extreme of position, operative connections between said piston and said valve-moving connections whereby iston-movement tends to restore said valving means to normal position, and electrical connections between said electro-responsive device and the motor circuit whereby rupture of the latter may de-energize the former.

2. The combination with a steam boiler, a forced-draft furnace having a draft fan, an electric motor for actuating it, and a movable motor-speed varying device, included in the motor circuit, of a pressure-responsive device connected with said boiler, and an engine comprising a cylinder, a piston therein loaded to tend normally to move to one end of said cylinder and operatively connected with said speed-controlling cylinder, valve means normally closing said end of said cylinder movable to open either said pressure or relief connections, a valvemoving lever, an electro-magnet on said lever, an armature on said valve means to be substantially rigidified with said lever when the magnet is energized, said magnet being CURTIS L. HOWSE.

art, pressure j and relief connections for sa1d end of sa1d

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