US2174533A - Submerged combustion control system - Google Patents

Description

Oct. 3, 1939.

T. 5. SEE ET AL SUBIIERGED COMBUSTION CONTROL SYSTEM Filed Feb. 23, 1937 3 Sheets-Sheet 1 Oct. 3, 1939. 'r. 5. SEE El AL SUBMERGED COMBUSTION CONTROL SYSTEM Filed Feb. 23, 1937 3 Sheets-Sheet 2 .39, 9 L BS Oct. 3, 1939.

'r. 5. SEE ET AL 2,174,533

SUBHERGED COMBUSTION CONTROL SYSTEI Filed Feb. 23, 1937 3 Sheets-$heet 3 [rule/7129215.- T/Zeodone 6 See, Jo/zzzl/fiduardfgazdeza Patented Oct. 3, 1939 UNITED STATES sumusaosn ooMaUs'rloN cosmos. srs'rnsr Theodore 8. See, Hammond, Ind., John Edward 'legarden, Calumet City, 111., and Arthur Williams, Munster, Ind.

Application February 28, lilil'hflerial No. 127,088

, '8 Claims.

This invention relates to submerged combustion, more particularly submerged combustion control systems and new and improved methods and apparatus for obtaining automatic subbecause of heat losses during the process of transferring the heat from the products of combustion to the liquid,

In so far as is known, none of the submerged combustion burners heretofore described is prov'ided with an automatic control system for regu: lating the thermal output of the burner according to the thermal requirements ofthe liquid being heated. In fact, most of the known submerged combustion burners are so constructed or used that automatic control would be extremely difllcult. In our co-pending application. above re- 80 ferred to, we have described a submerged combustion burner which may be ignited while in place in the liquid and which may be automatically controlled.

It is an object of this invention to provide new combustion burners. A further object is to provide a new and improved method and apparatus for automatically regulating control of a submerged combustion'burner, so that the thermal output of the burner is controlled according to the thermal requirements of the liquid being heated. A more specific object is the provision of a method and apparatus for automatically controlling a submerged combustion burner of the type described in our above identified co-pending application. A still further object is the provision of a new and improved means for controlling the thermal output of a submerged combustion burner by regulation of the fuel ignition. Another object is the provision of a means for controlling the thermal output of a submerged combustlon burner by regulating the fuel flow. Other objects will appear hereinafter.

In accordance with this invention, we have pro- 65 vided a means for automatically regulating and and improved control systems for submerged controlling the thermal output of a submerged combustion burner. This will be illustrated by several control systems, which embody generally: 1) thermostatically regulating the ignition, and (2) thermostatically regulating the flow of fuel. 5 These systems are especially well adapted for application in automatically controlling a submerged combustion burner such as described in our co-pending application, in which the combustion zone of the burner is positioned beneath the m surrounding liquid level and the burner is ignited in place, preferably by first igniting a raw fuel Jet above the liquid level and projecting the flame down to the combustion zone. In this type of burner and in the preferred methods of automatic control herein described, means are provided for agitating and at least partially displacing the liquid in the combustion zone by an air flow which is preferably continuous and preferably substantially constant both before and after ignition.

Other features of the invention will become apparent from a reading of the following specification in the light of the accompanying drawings, in which Figure 1 represents the combustion burner in 25 elevation, partly in section and with parts broken away;

Figure 2 is a plan view of a'section of the burner along the line A-A;

Figure 3 is a plan view of another section of the burneralong the line 3-8:

Figure 4 is a diagrammatic view of an automatic control system which is designated herein as our ignition control system; and

Figure 5 is a diagrammatic view of an automatic control system which is designated herein as our fuel flow control system.

Duscsrr'non or This SUBME-lii'lllill Comms'rron Brianna The burner, as illustrated in Figure 1, comprises an outer manifold 2, an inner manifold 4, a burner plate 8, a combustion chamber 8, equipped with outlets for the combustion gases ii, a .fuel supply line l2, leading to an opening l4 5 in the inner manifold, an air supply line It. leading to an opening it in the inner manifold, a supply line 20 for air or air and fuel mixtures leading to the combustion chamber 8, through the space 22 between the outer manifold and the innet manifold and openings 24 in the burner plate. The igniter 26 is connected with a source of electricity, not shown, through wires 28.

In Figure 2, the plan view of the cross section along the line A--A shows connections 30, which are connected to the igniter 2B (Figure l) and a source of electricity, not shown, through wires 28. The igniter is preferably of the hot wire type in which an ignition element is heated by passage have some similarities. For instance, in each of a low voltage-high amperage current. Alternatively, a high tension spark may be used. The wires 28. illustrated in Figure l, are within the air supply line It and pass around the fuel supply line i2.

As illustrated in Figure 3, which shows a plan of the cross section along the line 3-3, the air or air-fuel mixture, preferably under pressure, from a positive displacement blower. illustrated at C and C in Figures 4 and 5,- passes into the combustion chamber 8, through openings 24 in the burner plate 6.- The size of these openings may be varied to suit the desired fiowof air or airgas mixture.

The entire burner, including the manifolds 2 and I, the burner plate 6 and the combustion chamber 8, may be constructed of the same or different corrosion and heat resisting materials, e. g., iron, steel, alloys, etc., and the various types of stainless or corrosion resisting materials. The choice of material may vary somewhat depending upon the conditions of operation, for example, the temperature and the type oiliquid. Under most severe conditions, as in heating acid pickling baths, especially, desirable results have been obtained by the use of a corrosion resisting alloy sold under the trade-name oi "Hastelloy C", which is a high nickel, molybdenum, chromium, iron alloy. Whereas the usual type of burner involves combustion of the fuel against a refractory material, it has been found in the present burner that refractory materials are unnecessary and uneconomical for ordinary operations. However, they may be used if desired.

Dnscarr'rros or Com-nor. Srsrnns ThetwosystemsshowninFi8ures4and5 system there is a switch box generally indicated at A in Figure 4 and A in Figure 5 This switch box is of the type in which the main contacts are closed by means of a holding magnet m in Figure 4 and m in Figure 5. The holding'magnet in turn is controlled by pushbutton switch I; in Figure 4 and b in Figure 5. v'Ihismagnet may also be controlled by certain safety, devices, as hereinafter more fully described. The push button switchbin Figure4andb'inFigure5ison an electrical circuit which extends to a source of electricity generally illustrated by the transformer BinFigure4 andB'inFigui-e 5. Thistransformer for the purposes of the present invention preferably has two circuits, a 440-volt circuit operating the blower assembly generally indicated at C in Figure'4 and C in Figure 5, and an 110- volt circuit operating the ignition control system generally indicated at D in Figure 4 and D in Figure 5.

The various conduits shown in Figures 4 and 5 connect with conduits in Figure 1 as follows: conduit I! of Figure 1 is an extension of conduit III of Figure 4 and III of Figure 5. Conduit It of Figure 1 is an extension of conduit Ill of Figure 4 and 2 it of Figure 5. Conduit 20 of Figure 1 is an extension of conduit I20, of Figure 4.and 220 of Figure 5; It will be noted that the numerals designating the various parts of the apparatus are belowlOfl in Figures 1, 2 and 8; or above inFigure 4; and 200 or above in Figure 5.

In describing our automatic control systems. we

refer to the system illustrated in Figure 4 as our ignition control system, because in this system each time the solution temperature falls below the minimum temperature fixed by the thermostat, the circuit to the ignition coil is closed and 5 the fuel is reignited. when the proper temperature has been reached, the thermostat, through an electrical circuit to the main control valves, shuts oil the supply of fuel entirely. The system referred to in Figure 5 has been described a fuel flow control system, because in this sys the flow of fuel is never entirely cut oil unless the entire apparatus is shut down, and the ignition inthissystem is not repeated each time the solution temperature falls below the minimum temperature required to actuate the thermostat. In other words. ignition is only required in starting the apparatus. It will be observed of course that both of these systems to some extent involve ignition control but, the second system does not involve repeated use 0! the igniter during each period of operation. It will be further apparentthat a number of variations may be made particularly in the type of apparatus and in the combinations of the various parts of the system. The operation of the submerged burner control systems shown in Figures 4 and 5 as well as various modifications of these systems will be illustrated by the following description in which for convenience we refer to the system of Figure 4 "J Cirm'rron or was Suemmom Counusrnm Conraor.

SYSTEMS System No. 1

Referring to Figure 4, pressing the push button I00 closes the circuit to the holding magnet m, 41

which in turn closes the main contacts to the blower assembly illustrated generally at C and energizes the line to the ignition control generally indicated at D. This starts the blower I02,

which draws in air through an inlet conduit Nil 4;

provided, with a suitable air filter and'forces it out through a line I. provided with a suitable oil separator F. Conduit I08 connects with the main fuel supply line ill through a pressure equalizing line I09 and a governor H0. ,The 5 main fuel supply line It! is connected with an ignition fuel supply line |i2,,which may also be called a pilot'fuel line, and to a main fuel supply conduit I. The air introduced through oon duit I06 passes into an ignition air supply line a:

lit, which may also be referred to as a pilot air line, provided with an orifice plate H8 and also into a main air line I20 provided with an orifice plate I22.

The air blower It! is preferably of the positive cl displacement type and is run at a constant speed by means of an electric motor. With dlil'erent depths of solution, it is necessary to work against diiferent back pressures but with a positive dismains at a pressure of about 20 pounds per square inch, the pressure is usually more than sufficient for ordinary operations. If the gas is only available at a pressure of, say, 5 pounds per square inch, it would probably be necessary to use a blower or booster for the gas. This blower could be started up at the same time as the air blower. It could be a separate blower or on the same shaft as a single unit.

The governor IIO located in the main fuel line I00 is controlled by the air pressure in the line I06 between orifice I22 and the blower I02, so that the pressure in the main fuel line I00 is the same as the pressure in the air line I00 ahead of orifice I22. The drop across orifice I22 is proportional to the flow of air. Since the pressure in the main fuel line I00 is held the same as the air pressure in conduit I00 the drop across orifice I22 will be the same as the drop across orifice I24 in conduit II4. As the drop across orifices I 22 and I24 is always the same, by suitably proportloning the areas of these orifices, any desired ratio of air to fuel can be fixed and maintained.

The ignition fuel in conduit II2 passes to the burner (Figure 1) through conduit I2 and'opening l4 into the inner manifold 4. The main airfuel stream flows from conduit I20 to the burner (Figure 1) through conduit 20, then through the space 22 between the outer manifold 2 and inner manifold 4 of the burner, and mixes with the ignition fuel stream in the combustion zone 8 at a point below the burner plate 0. The pressure drop from the main air conduit I00 (Figure 4) above the orifice I22 to the combustion chamber beneath the burner plate 0 of Figure 1 will depend upon the pressure drops across the orifice I22 and burner plate 0 (Figure 1). Since the pressure in main fuel line I00 (Figure 4) is maintained equal to the pressure in air line I00, the pressure drop across orifice I20 is the ignition fuel line II2 will be the same as the total pressure drop across orifice I 22 and burner plate 0 (Figure 1). By suitably proportioning orifice I20 (Figure 4) to suit orifice I22 and the pressure drop through burner plate 0 (Figure 1), the desired flow of ignition fuei can be fixed and maintained.

It is also desirable to obtain a fixed supply of air to combine with the ignition fuel supply at opening it (Figure 1). This is maintained by orifice H8 (Figure 4) in pilot air line H0. As the main volume of air flows through conduit I20 to conduit 20 (Figure 1) and then through the space 22 between the inner and outer manifolds of the burner and the burner plate 0 to the cornbustion zone B, it clears the burner of all solution which before starting is normally above the burner plate.

Assuming that the solution temperature is lower than desired, thermostat bulb I20 (Figure 4) actuates switch I30, so that the switch is in closed-position. This permits current to flow from the transformer B through the switch box A to the ignition control system illustrated generally at D. Ignition switch 522 is in on-position and the current flows through primary coil 34. By induction, the current is induced in secondary coil I and this current flows through bimetallic timing strip I 30 and wires I to igniter coil 20 (Figure l). The bimetallic strip I30 (Figure 4) bends as it is heated by the heavy current flowing through it and rotates a plate on which the pilot switch I42 and the main switch 0 are mounted. After an interval of time sufficient for the igniter coil to reach the correct temperature, pilot switchl I42 makes contact and so opens solenoid valve I44. The ignition fuel supply flows through the solenoid valve I44, orifice I20, and conduit II2 to the burner (Figure l) where it enters through conduit I2 and opening l4 into inner manifold 4. The jet of fuel is ignited by igniter coil 20, and the flame floats down inner manifold 4. A ring of air, forced by the blower I02 through conduit I00, orifice III and conduit I00, is admitted to the burner through conduit I6 (Figure 1) and enters the inner manifold 4 through opening I0. This air travels down the inner manifold of the burner at approximately the same velocity as the central fuel let, so that combustion takes place slowly at the junction of the fuel and air, which is in the form of a ring. In this way a hollow flame is produced, burning continuously down the inner manifold 4 (Figure 1) to a point beneath the burner plate 6.

After a further interval of time, main switch I40 (Figure 4) makes contact, thereby opening solenoid valve I48, and fuel is admitted through conduit H4 and orifice I24 to mixing 1' I00. The combustible mixture flows through pipe I20 to conduit 20 (Figure 1) and down the space 22 between the inner manifold 4 and main mani fold 2 to burner plate 0. The pilot flame and the main air-fuel mixture are moving at approximately the same velocity. so that ignition of the main air-fuel mixture takes place instantly and quietly. The products of combustion pass down through combustion chamber 0 and holes ill to the solution.

Referring again to the ignition control D (Figure 4), a holding magnet #52 is in series with the main solenoid switch I40, and as soon as the main solenoid switch I40 makes contact, the current passing through holding magnet I52 pulls the ignition switch I32 to off-position and holds the entire system with the ignition switch I32 in ofi-position and the pilot switch I42 and main switch I46 in on-position. Thus, both of the solenoid valves I and I40 are open after ignition and as long at the solution is below the upper temperature setting of the thermostat. This results in combustion in the inner manifold 4 of the burner (Figure l) as well as below burner plate If desired, by a suitable adjustment of mercury switches I42 and I40, switch I42 can be tilted to off-position after switch I40 is in on-position and sufficient time has been allowed for the fuel passing through main solenoid I40 to reach the burner and ignite. Instead of moving switch I42 to off-position, the same result can be attained by providing another mercury switch (not shown) in the circuit to solenoid valve I44 and mounted in such a way that it opens the circuit when the main fuel stream has ignited below the burner plate 6 (Figure 1). In either case, instead of having fuel burning down the inner manifold 4 and also below the burner plate 0 (Figure 1) while the solution is coming up to temperature, the effect is to have all of the combustion taking place below the burner plate 0 in the combustion zone B.

When the solution attains the desired tempera ture, switch I30 is moved by the thermostat to open position, so cutting on the main circuit to the ignition control. The ignition control returns to the ready position, with the solenoid valves closed, so that only air is passing through the burner and solution. The solution will gradu-. ally cool, and after the solution temperature has dropped a predetermined amount, the thermostat bulb I23 actuates a switch mechanism which moves switch I30 to closed position, so starting the ignition cycle again.

As a precautionary measure, the holding magnet m in switch box A, in addition to being controlled by the push button I is also controlled by three mercury switches. One of these mer- I84 is located in the thermostat control generally illustrated at E, and moves with the switch I but is in reversed position. so that when switch I30 goes on, switch I54 will break contact and vice versa. The second mercury switch I58 is located in the ignition control system D on the same mounting plate as pilot switch I42 and main switch I48, so that all three move together. When pilot and main switches I42 and I48 are both oil, switch I58 is making contact. The contact of switch I55 is broken after the pilot switch I42 makes contact and before main switch I48 makes contact. When the ignition control unit D is locked in running position, safety switch I58 is locked in open position.

The third safety switch I58 is controlled in response to the flow of fuel through orifice I25. At the correct rate, a pressure diilerential is set up through conduits I8I, I53, causing switch I58 to make contact. Assume that this diiferential is of the order of 2 inches of mercury. If the rate of flow of pilot fuel should change sufliciently to cause the differential to fall to less than 1% inches, or more than 2 inches of mercury, switch I58 would be thrown to open position. Switches I54, I58 and I58 are conneted in parallel with each other and each one is connected in series with push button switch I00. The way in which these three switches operate is as follows:

With the entire apparatus shut down and the solution temperature below the temperature for which the thermostat is set, it will be noted from the above that switch I54 is in ofiposition, switch I58 is in art-position and switch I58 is in off-position. When push button switch'l00 is depressed current will flow through the push button switch I00 and switch I55 in the ignition controller D, energizing the holding magnet mintheflrststarting switch box A and making contact in the main power circuit. As is usual in starting switches of this type the starting switch button has only to be depressed for a sufficient length of time to energize the holding magnet circuit, after which the circuit is automatically held closed until broken by some other means.

Current is now flowing to the ignition controller D, which is operating in the manner described above. As soon as the pilot switch I42 makes contact. solenoid valve I44 opens and the ignition fuel flows through orifice I28. If the ignition fuel flow is correct, pressure safety switch I50 makes contact immediately. After a few seconds the further movement of the bimetallic strip I38 causes the safety switch I55 to break contact but as switch I58 is in the closed position the holding magnet circuit to the starting swtich box is still unbroken. It, for any reason, the correct pilot fuel flow is not obtained and pressure switch I58 does not make contact, then before the main switch I46 makes contact, switch I55 will break contact, opening the holding magnet circuit to the starting switch box and shutting down the entire apparatus. It will be noted also that when in running position, switch I58 is held in oil-position, .so that any appreciable change from the correct fuel flow will shut down the entire apparatus immediately. In this caseitwiilbe 'torestarttheapparatul bypushingbutton illinswitchboxapresumably after an investigation of the reason for failure.

It was described above how the fuel flow is proportional to the air now. If the air flow changes more than a certain amount the pilot fuel flow will be altered suiliciently to move pressure switch I58 to open position, shutting down the apparatus.

When the solution is at the desired temperature, thermostat switch I30 opens the main circult, thereby closing valves I44 and I48 and shutting off the fuel supply. At the same time, the safety switch I54 closes the safety circuit and holds the starting switch magnet circuit closed.

To open the starting switch magnet circuit and shut down the entire apparatus, it is only necessary to press push button switch I00.

Provision may be made for igniting more than one burner from the same control system. This may be accomplished, for example, by an additional igniter circuit indicated by the lines I80, I82, I84 and I88. This circuit contains an additional induction coil I00. The wires leading to the igniters (not shown) are illustrated by lines I10 anti I12.

It will be observed that the wiring diagram of the apparatus described in Figure 4 comprises five principal circuits exclusive of the circuits to the compressor C and the safety circuits. These circuits just referred to may be readily traced from the contacts 14 and Is in switch box A. The circuits in question comprise (l) a circuit through primary coil I34, (2) a circuit through secondary coil I to the igniter, (3) a valve circuit through solenoid actuated pilot valve I44, and (4) a valve circuit through solenoid actuated main valve I45, and (5) a holding magnet circuit through magnet I52.

The first of these circuits may be traced as follows: Current from a positive source of potential passes from contact 14 in starting box A through line III to temperature control switch I30 in temperature control unit E, from switch I30 through line II3 to contact II5, from contact II5 through conductor I" to switch I32, from switch I32 through conductor II3 to-primary coil I34, from primary coil I34 through conductor I2I to triple contact I23 and from triple contact I23 through conductor I25 to contact I5 in switch box A, which is a negative source of potential.

This circuit serves to energize the primary coil I34, thus creating a current in secondary coil I36 and energizing the second circuit.

The second circuit through secondary oil I38 is connected by conductors I40, I40 to igniter 28 of Figure l.

The circuit mentioned above starts from a source of positive potential at contact II5, which has already been traced from contact 14 in switch box A, and passes through conductor I2'I to pilot switch I42, from pilot switch I42 through conductor I29 to contact I3I, from contact I3I through conductor I83 to pilot solenoid valve I; from pilot solenoid valve I44 through conductor I35 to triple contact I23 which forms a negative source of potential connected to contact Is in switch box A by means of conductor I25. This circuit controls the operation of pilot solenoid valve I44.

A third circuit which controls the operation of main solenoid valve I48 originates at a positive source of potential at contact I3I, passes h from contact I through conductor I43 to I46, I, one side of main solenoid valve I43 and from the other side of main solenoid valve I48 through conductor I to triple contact I23 which is connected to a negative source of potential at I5 in switch box A through conductor I25.

The last of the circuits mentioned above as forming a part of the ignition control system originates at a positive source of potential at contact I4I, passes through conductor I to holding magnet I52, from holding magnet I52 through conductor I41 to triple contact I23 which is connected to a negative source of potential at It in switch box A through conductor I25.

As already stated, the operation of these circuits is such that current passing through the circuit containing the primary coil I34 induces a current in the igniter circuit containing secondary coil I36. In the primary coll circuit, switch I32, which is preferably a mercury type switch, is normally closed in order to complete the circuit.

As current flows through the secondary coil circuit and through bimetallic element I38 this element I38 moves, causing pilot switch I42, which was heretofore open, to close, thus completing the previously traced circuit through solenoid valve I44 and causing said valve to open. By this time the igniter is hot and the gas flowing into the apparatus because of the opening of the pilot valve is ignited. As already described, the switches I42 and I46 are so arranged that switch I46 which controls main solenoid valve I48 is closed after switch I42, thus completing a circuit through main solenoid valve I43 and opening said valve, thereby allowing a mixture of primary gas and air to pass into the apparatus. The operation continues as long as switch I36 is not broken by the thermostatic control.

After the main solenoid valve I43 is open it is no longer necessary to keep the igniter wires hot, and simultaneously with the closing of main solenoid switch F46 to complete a circuit through and open main solenoid valve I48, another circuit is completed as previously described through holding magnet I52, which thereupon causes switch I32 to open and breaks the circuits through primary and secondary coils I34 and I36, respectively.

The safety circuits, as previously stated, comprise three controlling switches, namely, switches I54, I56 and I58, which are connected in parallel with each other and in series with the relay M in switch box A. Hence, if all three of these switches are open at once the apparatus wili automatically shut down. The circuits including these switches may be traced as follows: A positive source of potential from contact 01 in switch box A passes through conductor I49 to contact I5I, from contact i5I through conductor I53 to switch I56, from switch I56 through conductor 55 to contact I51, from contact 55! through conductor III to a negative source of potential at C2 in switch box ,A. Switch I54 in temperature control unit E is connected to a positive source of potential at contact I5I through conductor I65 and to a negative source of potential at contact I51, through conductor I59. Safety switch I58 is connected to a positive source of potential through conductor I61 which is connected to line I65 and to a negative through conductor I31 to main switch thence tl rough conductor I36 to contact source of potential through conductor I69 connected to conductor I59.

The operation of the switch box A is conventional and will be readily understood from the illustration in the drawings. Relay m is controlled by a IOU-volt circuit extending from a positive source of potential through conductor on, contact 104 and conductor m2 and to a negative source of potential through conductor m3, push button contacts b1, b2 and bi, conductor 1124, contact we and conductor me. This circuit, it will be noted, is open until closed by pushing push button switch b, which closes contacts In and 123. When relay m is energized by closing the contact across in and b3, thus completing the circuit previously traced, it closes the con tacts across win, 2027'2, win, wars, and wars. Closing the contacts across win, wars, and war: completes a. circuit from the 440-volt source of potential generally illustrated at B, through lines 11,12 and l: to contacts vi, m and Us and thence to the compressor generally illustrated at C. Likewise, closing contacts can and wars complates a circuit from the 1l0-volt source of potential to contacts 14 and Is as previously traced. Contact Cl is connected to a source of potential through conductor 16, contacts rs and w and conductor me. Contact C: is connected to a. source of potential through conductor l-r, contact b2 and bi, conductor ma, relay m, conductor me, contact wt and conductor 1121.

System No. 2

Referring to Figure 5 of the drawings; air is supplied from a blower assembly shown at C. The blower 202 is driven by an electric motor, controlled by starting switch box A. The air is drawn in through inlet conduit 264 provided with a suitable air filter and forced through outlet conduit 2Il5, which is provided with a suitable oil separator. Fuel is introduced into the system through conduit 268 and a governor 2H) and flows to the burner through conduit 2I2, corresponding to conduit I2 of the burner (Figure 1). A pressure equalizing line 2 is provided between the air conduit 206 and governor 2H].

The air from conduit 206 flows to the burner through two conduits H5 and 220, corresponding to conduits I6 and 20 of the burner (Figure 1). Conduits 2I6 and 226 are provided with orifice plates 2 and 2IB9 respectively.

When the starting button 200 is depressed, the blower motor starts and current flows to the ignition control box generally illustrated at D. Ignition switch 222 is in oif-position and current flows through primary coil 224. By induction, current is induced in secondary coil 226 and this current flows through bimetallic timing strip 228 and wires 236 to igniter coil 26 (Figure l). Bimetallic strip 228 bends as it is heated by the heavy current flowing through it and rotates a plate on which the switch 232 and magnet switch 234 are mounted. After an interval of time sufficient for the igniter coil to reach the correct temperature, valve switch 232 makes contact and opens valve 236. Valve 236 is of the slow opening type and as the valve slowly opens, fuel is allowed to flow through conduit 2| 2 to nozzle or jet I4 (Figure 1). Soon after the valve 236 (Figure 5) is opened the flow through nozzle I4 (Figure 1) is correct for ignition, the fuel will ignite and the flame will burn down inner manifold 4 (Figure 1) to bumer plate 6. A ring of air from conduit I 5 (corresponding to conduit 2I6 (Figure 5)) is adply, instead of being 6 V 3.11am

mittedthrough'openinglltomwmoomw withtheairineonduitlltfnthisrespeet. ticnattheinstantofignition. nirtlieropeninl systemliaslslimilartonntemmlm ofthevalvelliil'lguremincreuuthefuel iiLncwever, l'igureithevalvelflcmfiowuptoanamountcontroliedbythe osition trollinathoilcwoffueito'theigniterisofthe of thermostatically controlled valve m and the slow type. whereas the solenoid valve siaeoforiflcelllhandtheturbulentmixingof lllinligure ihoftherarddopenlngtype. thefuel andairaround burner plateiu'igure 1) Furthermore, the controloiffnel ficrwinrlgure will cause the main part of combustion to take is obtained by a mechanically place at the burner plate.

At a predetermined time interval after valve switch 232 has made contact, magnet switch 2" makes contact and energizes magnet 242. The magnet pulls down ignition switch 222 to offposition and locks the ignition controller D, with the ignition switch 222 011 and valve switch 232 on.

The flow of fuel will be controlled by thermostatic valve 238. if the solution is cold, valve 236 will be wide open and the flow of fuel will be at a maximum, being limited by orifice 2".

As described above for System No. 1, the area of orifice 240, the area of orifices 2H and H8 and the area of burner plate ii will be suitably proportioned to give the correct air-fuel ratio. when the solution is at the approximate temperature desired, valve 228 will assume a controlling position, determined by the thermostat pilot. There will be a set minimum flow past valve 23!. In this way the fuel may vary between minimum and maximum fiows in accordance with the solution temperature. 'It will be noticed that in System No. 2 the igniter only comes into operation at the beginning of each period of running, while in System No. l the igniter comes into operation each time that the thermostat calls for heat.

To guard against failure of the fuel supply a pressure switch 2 is located in the fuel cn duit 208, ahead of governor 2lil. This pressure switch is of the type that closes an electrical contact when the pressure is at a predetermined figure and breaks contact in the switch when the pressure drops. The switch is in series with the holding magnet coil m in starting switch box A. If, for any reason, the fuel pressure drops below a set figure, the holding magnet circuit in the switch box is opened and the entire apparatus is shut down, requiring closing of the push button switch for restarting.

If desired, a second igniter (not shown) may be operated from the same ignition control D. This may be accomplished by adding another circuit as shown by wires 2, 248 and 260 and a second induction coil 252.

System No. 3

By variations in the two systems described above, a third system has been devised. In this system the flow of fuel is controlled by solenoid valves as in System No. l, but the main fuel supmixed with the air before being introduced into the burner, is separately introduced into the burner and becomes mixed with the air therein. This may be accomplished by constructing the apparatus so that conduit i I (Figure 4) instead of being joined to the main air conduit I20, is joined to the ignition fuel conduit H2 at a point between orifice I26 and the burner. Thus, referring to Figure 4, after the solenoid valve I is open, permitting fuel to pass to the igniter and allowing ignition to take place, the main solenoid valve I48 opens and permits fuel to flow through conduit 4 and orifice I24 to conduit H2. All of the fuel then passes through conduit M2 to the burner and is not pro-mixed perature responsive and gvhlch is also preferably employed in System No.

It will be apparent that a number of modifications may be made in the various control systems describedwithout departing from the invention. For instance, in Figure 4 instead of the solenoid valves, other types of electrically operated valves may he used. In the ignition control system shown at D in Figure 4 and D' in Figure 5, it has been found advantageous to use mercury switches. These switches may be mounted in well known ways. The induction coils in the ignition systerns are preferably of the type having a floating primary coil in order to obtain a constant current.

In Figure 5 the temperature responsive control means, generally illustrated at E, may be so constructed as to operate the fuel flow valve by electrical means rather than mechanical means. It will also be recognized that changes may be made in electrical circuits in ways well known to those skilled in the art.

The combustible fuel is preferably'a gaseous fuel, e. g., natural gas, butane, water gas, producer gas, or gas mixtures of the type ordinarily used in household heating and for gas stoves. Instead of gaseous fuels, liquid or powdered fuels may be used, for example, atomized or vaporized oil, gasoline, and the like.

The rate of fiow of the fuel may vary widely depending upon many factors, such as the type of fuel, output of the burner, use of the burner. etc. Good results in practice have been obtained with a relatively low rate of flow of the gas to be ignited, preferably not above 125 cubic feet per hour. We have observed a tendency for the flame to pop out if much higher rates of flow are used on ignition. In heating acid pickling baths by our method of submerged combustion, it is preferable to have a minimum gas fiow of at least 25 cubic feet per hour because of millculties in clogging. with other liquids the flow may be lower. The main fuel flow is normally at a much higher rate. For example, good results have been obtained with a total gas flow within the range of 550 to 650 cubic feet per hour. The rate of flow is regulated by the orifices (not shown) in the supply lines, or by the size of the holes in the burner plate, or in any other suitable way.

The apparatus and control systems described are especially desirable because they do not require a large amount of space and are relatively simple to operate. Moreover, by the control system illustrated it is possible to obtain automatic control of submerged combustion while at the same time maintaining constant agitation of the liquid being heated. The ignition system shown and described above is entirely satisfactory for all practical purposes. The igniter is preferably above the liquid level, because although ignition may be obtained with the igniter below the liquid level, the results are not quite so reliable. Hence the liquid level is normally intermediate between the igniter and the burner plate.v

system, the combination of a submerged combustion burner, means for introducing fuel into the burner, means for introducing air into the burner, ignition control means comprising a mercury ignition switch, a primary and second coil, an igniter element, a bimetallic timing strip. a holding magnet adjacent to the ignition switch and adapted, when energized, to pull the ignition switch to off-position, a pilot solenoidvalve controlling the flow of fuel to the burner for the purpose of ignition, a second mercury switch electrically connected to said solenoid valve controlling the flow of fuel to the burner for the purpose of ignition, a second solenoid valve controlling the main flow of fuel to the burner, a third mercury switch connected to said second solenoid valve controlling the main flow of fuel to the burner after ignition and likewise connected to the ignition switch holding magnet, an electrical circuit through the ignition switch to the primary coil whereby, when the ignition switch is closed, a current flows through the primary coil which generates a current in the secondary coil and thereby operates the igniter element and causes the bimetallic strip to bend, which, as it bends, actuates an arm carrying the second and third mercury switches which are mounted in such a way that the third switch closes after the second switch and after a sulficient time has been allowed for ignition.

2. A submerged combustion burner system for directly heating materials in a liquid state comprising, in combination, a burner having a combustion zone for fuel and air positioned in a liquid to be heated, thermal responsive means associated with said liquid and responsive to the temperature of said liquid, pilot fuel supply means associated with said burner, separate pilot air supply means associated with said burner,

main fuel supply means associated with said burner, main air supply means associated with said burner, pilot fuel control means associated with said pilot fuel supply means, main fuel control means associated with said main fuel supply means, means associated with said thermal responsive means and said pilot fuel control means to cause the amount of pilot fuel introduced into the burner to be automatically controlled, means associated with said thermal responsive means and said main fuel control means to cause the amount of main fuel supply admitted to the bumer to be automatically controlled, pilot fuel ignition means, means associated with said thermal responsive means for energizing and actuating said pilot fuel ignition means, and means associated with said energizing and actuating means for rendering said ignition means inoperative after the pilot fuel has been ignited.

3. A submerged burner system for directly heating materials in a liquid state, comprising, in combination, a burner having a main combustion zone for combustion of fuel and air positioned in a liquid to be heated, a thermal responsive means associated with said liquid, a pilot fuel-supply means associated with said burner, a pilot air supply means associated with said burner, a main fuel supply means associated with said burner, a main air supply means associated with said burner, an electrically actuated valve controlling said pilot fuel supply means, an electrically actuated valve controlling said main fuel supply means, an electrical circuit controlling said electrically actuated valve on the pilot fuel supply means and controlled by said thermal responsive means, another electrical circuit controlling said electrically actuated valve on the main fuel supply means and controlled by said thermal responsive means, an electrical pilot fuel ignition means, a third electrical circuit controlling said electrical ignition means and controlled by said thermal responsive means, and a fourth electrical circuit associated with the main fuel control valve circuit and adapted to render the circuit controlling said ignition means inoperative without affecting the circuits controlling the pilot fuel valve and the main fuel valve.

THEODORE 8. SEE. JOHN EDWARD TEGARDEN. ARTHUR WILLIAMS.

CERTIFICATE OF CORRECTION.

Patent No. 2,17ii,555.

October 5 1959.

THEODORE S. SEE, ET AL. It is hereby certified that error appears in. the printed specification of the above numbered patent requiring correction as follows: Page 5, first column, line 111, for the word "is" insert in; page 1 first column, line 51 for "convicted" read connected,- and second column, line 57, for "011" read coil; page 7, first column, line 16, claim 1, for "second" read secondary;

and that the said Letters Patent shouldbe read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 21st day of November, A. D. 1939.

(Seal) Henry Van Arsdale, Acting Commissionerof Patents.

system, the combination of a submerged combustion burner, means for introducing fuel into the burner, means for introducing air into the burner, ignition control means comprising a mercury ignition switch, a primary and second coil, an igniter element, a bimetallic timing strip. a holding magnet adjacent to the ignition switch and adapted, when energized, to pull the ignition switch to off-position, a pilot solenoidvalve controlling the flow of fuel to the burner for the purpose of ignition, a second mercury switch electrically connected to said solenoid valve controlling the flow of fuel to the burner for the purpose of ignition, a second solenoid valve controlling the main flow of fuel to the burner, a third mercury switch connected to said second solenoid valve controlling the main flow of fuel to the burner after ignition and likewise connected to the ignition switch holding magnet, an electrical circuit through the ignition switch to the primary coil whereby, when the ignition switch is closed, a current flows through the primary coil which generates a current in the secondary coil and thereby operates the igniter element and causes the bimetallic strip to bend, which, as it bends, actuates an arm carrying the second and third mercury switches which are mounted in such a way that the third switch closes after the second switch and after a sulficient time has been allowed for ignition.

2. A submerged combustion burner system for directly heating materials in a liquid state comprising, in combination, a burner having a combustion zone for fuel and air positioned in a liquid to be heated, thermal responsive means associated with said liquid and responsive to the temperature of said liquid, pilot fuel supply means associated with said burner, separate pilot air supply means associated with said burner,

main fuel supply means associated with said burner, main air supply means associated with said burner, pilot fuel control means associated with said pilot fuel supply means, main fuel control means associated with said main fuel supply means, means associated with said thermal responsive means and said pilot fuel control means to cause the amount of pilot fuel introduced into the burner to be automatically controlled, means associated with said thermal responsive means and said main fuel control means to cause the amount of main fuel supply admitted to the bumer to be automatically controlled, pilot fuel ignition means, means associated with said thermal responsive means for energizing and actuating said pilot fuel ignition means, and means associated with said energizing and actuating means for rendering said ignition means inoperative after the pilot fuel has been ignited.

3. A submerged burner system for directly heating materials in a liquid state, comprising, in combination, a burner having a main combustion zone for combustion of fuel and air positioned in a liquid to be heated, a thermal responsive means associated with said liquid, a pilot fuel-supply means associated with said burner, a pilot air supply means associated with said burner, a main fuel supply means associated with said burner, a main air supply means associated with said burner, an electrically actuated valve controlling said pilot fuel supply means, an electrically actuated valve controlling said main fuel supply means, an electrical circuit controlling said electrically actuated valve on the pilot fuel supply means and controlled by said thermal responsive means, another electrical circuit controlling said electrically actuated valve on the main fuel supply means and controlled by said thermal responsive means, an electrical pilot fuel ignition means, a third electrical circuit controlling said electrical ignition means and controlled by said thermal responsive means, and a fourth electrical circuit associated with the main fuel control valve circuit and adapted to render the circuit controlling said ignition means inoperative without affecting the circuits controlling the pilot fuel valve and the main fuel valve.

THEODORE 8. SEE. JOHN EDWARD TEGARDEN. ARTHUR WILLIAMS.

CERTIFICATE OF CORRECTION.

Patent No. 2,17ii,555.

October 5 1959.

THEODORE S. SEE, ET AL. It is hereby certified that error appears in. the printed specification of the above numbered patent requiring correction as follows: Page 5, first column, line 111, for the word "is" insert in; page 1 first column, line 51 for "convicted" read connected,- and second column, line 57, for "011" read coil; page 7, first column, line 16, claim 1, for "second" read secondary;

and that the said Letters Patent shouldbe read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 21st day of November, A. D. 1939.

(Seal) Henry Van Arsdale, Acting Commissionerof Patents.

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