US2098585A - Reversing furnace control - Google Patents

Description

Nov. 9, 1937. F. H. LOFTUS REVERSING FURNACE CONTROL Filed May 15, 1937 INVENTOR ATTORNEYS Patented Nov. 9, 1937 UNITED STATES z assss PATENT OFFICE 7 4 Claims.

My invention relates to reversing furnaces, and in exemplary way I shall describe the invention as it is practised in an open-hearth furnace of usual sort.

An open-hearth furnace consists in a chamber constructed of refractory masonry, tied and reinforced withstructural steel and tie-rods. The floor of the chamber comprises a dished hearth, adapted to receive a charge of steel-forming materials, and through the opposite end walls of the chamber open ports that communicate with regenerator chambers arranged below. In known way a combustion-sustaining mixture of fuel and air is introduced through one port, and the hot products of combustion are drawn off through the other. From time to time the operation is reversed: The port which had been serving as the firing port becomes the outgo port, and the port which had been the outgo pert becomes the firing port. The invention concerns this furnacereversing operation, and consists in means for effecting the reversal readily and in minimu time.

In the accompanying drawing Fig. I is a diagrammatic View of the fuel-feedingap'paratus of a furnace equipped with control apparatus embodying my invention; Fig. II is'a view part y in side elevation and partly in vertical section, showing a portion of the apparatus to larger scale; and Figs. III and IV are severally views comparable with Fig. II, illustrating permissive modifications.

The invention has been particularly developed for use in the fuel-feeding equipment of an openhearth furnace which burns liquid fuel, and in such embodiment it is described below, with the understanding that within the terms of the appended claims a wider field of application is contemplated.

Referring to Fig. I, two oil burners I and 2 are shown. The burners are normally arranged in opposing relation, one at each of the opposite ends of the furnace (not shown), and for purposes of illustration the burners have been swung from the opposing vertical Planes in which they normally extend and are shown lying in the common plane of the drawing. Each burner includes an inlet 3, through which fuel oil is in known way jetted by means of steam, or other gas, under pressure. The fuel is delivered to the burners, by means of pipes 5, leading from a fuel supply tank 6, and steam under pressure is delivered through conduits I from a steam supply line 9. In usual way the fuel in the supply tank is preheated by means of a steam coil, whose inlet and outlet leads are indicated at l8. It will be understood from what has been said above that one burner is idle while the other is in operation.

The lines 5 and 1 leading to the two burners port which had been serving as the firing port is interrupted, and fuel, steam, and air are caused to flow into the port which had been serving as the outgo port.

It will be understood that the reversal of the regenerator reversing valves is electrically controlled in known way, by means of one or more switches l0 mounted on the usual instrument panel in a remotely located control station S, and the time required in effecting such reversal is negligible. In the case of the burner-controlling valves 8, however, it takes the furnace attendants from twenty seconds to over a minute to' effect the required adjustments. In accordance with my invention, I provide means, controlled at station S, for effecting instantaneous control of the fuel-feeding lines 50f the two burners. Advantageously, though not necessarily, such means are responsive in operation to the conditions of steam pressure within the conduits I.

More particularly, I provide in each of the fuel pipes 5 a valve 80 of the sort illustrated in Fig. II, and with such valve I organize a chest or cylinder l l, including a. plunger l2, whose plunger rod i3 is connected to the valve-member 8| that controls flow through the valve. 0n the valve side of the plunger II, a compression spring 40 bears, tending normally to urge the plunger in such direction that the valve-member 8! is held in closed position; on the opposite side of the plunger, the cylinder is subject to the pressure existing in steam conduit 1, a pipe l4 serving to establish the communication. In normal furnace operation with my apparatus, all four valves 8 are set in open positions. In the control station S, I provide a two-way valve l5, having a handle I6 movable between alternate positions. In one position of the handle, the conduit 1 leading to one burner is blanked, while communication is established between the conduit 1 leading to the other burner and the steam supply line 9, andin the alternate position of the handle, the situation is reversed, as regards communication between the steam supply line 9 and the respective conduits 1, I of the two burners. The pressure of the steam in the conduit 1 leading to the active burner is, by way of pipe I4, efiective in the valveoperating unit H, I2 of such burner, and such pressurea pressure in the order of forty pounds 4 per square inch-acts upon the plunger l2, overpowering the spring 40 and holding the valvemember 8| from its seat. Thus, the valve 80 is automatically held in open position and fuel flows into the burner, so long as steam is flowing under operating pressure to such burner. In the valveoperating unit II, l2 of the inactive burner, the spring! is effective to hold fuel-controlling valve 80 in closed position, it being understood that the steam conduit I of the inactive burner is blanked from the steam supply (and may also be vented to the atmosphere), by means of the valve l5, and

that the pressure within the cylinder II is, therefore, reduced to ineffective value.

By virtue of my apparatus, a complete furnace reversal may be effected in five seconds. The attendant merely throws the switches l0 and the valve-handle l6. Immediately, the usual reversing valves of the regenerators are swung into alternate positions. Steam supply to the active burner is cut oil; the fuel-controlling valve 80 closes, under the influence of spring 40, and operation of the active burner is arrested. And simultaneously steam is supplied to the other burner, with the consequence and effect that its fuelcontroiling valve 80 opens and its operation as the active burner of the furnace begins. Once initiated, the operation continues until the next furnace reversal.

In addition to the manifest advantages of quick furnace-reversing operation, my apparatus permits the fuel-controlling valves (80) to'be em-" bodied in immediate association with the burners at the opposite ends of the furnace. Accordingly, when one or the other burner is shut down, the column of oil remaining in the pipe 5 between the valve (80) and the fuel outlet in the burner is a relatively short column.

In burner-controlling apparatus of the sort employed hitherto, the fuel-controlling valves are not arranged in such close relation to the burners, and the column of oil left standing in the blanked fuel pipe is relatively long, in some cases reaching 75 feet in length. Under the influence of heat radiated by the furnace, this dormant body of oil expands and partially gasifles, causing fuel to drip and ooze from the burner into the outgo port of the furnace. Obviously, such a waste of fuel is objectionable. Additionally, the stationary column of oil tends to congeal and solidify in the fuel line under the influence of furnace heat, with the consequence and effect that such fuel line must be blown-out and purged, with steam or compressed air, when the furnace is reversed. It will be readily perceived that in the use of my apparatus these objections are eliminated or minimized, inasmuch as the valves 80 are arranged practically at the discharge ends of the fuel-delivering pipes 5.

In Fig. III, I illustrate that a bellows-and-yoke of well-known structure may be arranged within the steam chest I I of each valve-operating unit, in such manner that the valve-stem I3 shall shift, as already described, to open and close the valve 80.

In further modification, I propose to organize an electromagnet 40 with each valve 80, as illustrated in Fig. IV. The armature 44 of the magnet is rigidly mounted on, and in axialalignment with, the projecting end of the valve-stem l3. Themagnet will be normally deenergized, and a spring 4i acting on a collar 45 on the valve-stem l3, will normally hold the valve-stem in valveclosing position. Upon the closing of a switch 42, which'will be mounted on the instrument panel in station S, an energizing circuit 43 forthe m net will be closed, whereby the magnet will become effective to shift its armature 44, against the resistance of spring 4i, and open the valve. The magnet will remain energized and the valve will stand in open position, so long as the switch 42 remains closed. Thus, by means of a switch, or switches, on the instrument panel in station S, the attendant may effect the operations deoperable for effecting selective operation of said valve-operating means, while interrupting the flow of fluid in one of said conduits and initiating flow in the other of said conduits in coordination with the operation of said valve-operating means.

2. The combination with pipes for supplying fluid fuel to two ports of a regenerative furnace, valves for severally controlling the flow of fuel into said ports, valve-operating means organized with each valve adjacent to the respective ports, and conduits arranged to deliver fluid under pressure for jetting the fuel supplied by said pipes into said ports, of a remote control station including means for selectively controlling the supply of fluid under pressure to said conduits and effecting the energizing of said valve-operating means, to open one of said valves while closing the other.

3. The combination with pipes for supplying fluid fuel to two ports of a furnace, valves for severally controlling the flow of fuel into said ports, and conduits arranged to deliver fluid under pressure for jetting the fuel supplied by said pipes into said ports, of means for operating said valves, said means including members responding to alternate conditions of pressure established in said conduits for opening one of said valves and closing the other.

4. The combination with pipes for supplying fluid fuel to two ports of a furnace, valves for severally controlling the flow of fuel into said ports, and conduits arranged to deliver fluid under pressure for jetting the fuel supplied by said pipes into said ports, of valve-operating means arranged with each valve, said means comprising chests severally communicating with said conduits and including valve-shifting members movable between alternate positions upon changing from one to the other of alternate conditions of pressure in said conduits, a control station, and means in said control station for effecting such change in conditions of pressure, whereby said valve-operating means are effective to open one of said fuel-controlling valves while closing the other.

FRED H. LOFI'US.

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