US2375840A - Liquid heating apparatus - Google Patents

Description

R. A. EKSTROM, JR

LIQUID HEATING APPARATUS 5 Sheets-Sheet 1 Filed Dec. 23, 1941 @w -1 g E H T11 llxl'! 6 r w. it mw P l PM}! w -W\m\\ WM w l I w W N. Q wr /Mfi E W y 1945- R. A. EKSTROM, JR 2,375,840

LIQUID HEATING APPARATUS Filed Dec. 23, 1941 I 5 Sheets-Sheet 2 my 5' 27 9i y 1945- R. A. EKSTROM, JR I ,375,840

I LIQUID HEATING APPARATUS Filed Dec. 23, 1941 5 Sheets-Sheet 4 a 1945- R. A. EKSTROM, JR 2,375,340

LIQUID HEATING APPARATUS Filed Dec. 23, 1941 5 Sheets-Sheet 5 j #1 LA 1770a 7230 71' Patented May 15, 1945 LIQUID HEATING APPARATUS Regner A. Ekstrom, Jr., Markham, 11]., assignor to Elematic Corporation, Chicago, Ill.,

ration oi Illinois Application December 23, 1941, Serial No. 424,120

Claims.

This invention relates to an apparatus for heating liquids by means of a gas burner in which the burner or portions thereof are submerged or extend into the liquid and some or all of the products of combustion arepreferably discharged into the liquid causing agitation of the same.

The principal objects of the invention are to provide an improved burner or apparatus of the character indicated which will be particularly simple in construction and durable and efiicient in operation.

Other objects are to provide improved means for controlling the input of the gases to the burner; to improve the combustion characteristics of the burner and to distribute and control the output or exhaust of the gases of combustion; to provide improved means for mixing the gases and preventing danger from back-firing; to provide an improved pilot light and ignition therefor; to provide means for continuous indication of the efiiciency of the flame or combustion; to provide means for visually observing the combustion or flames in the burner; to provide means for dispensing the heated or exhaust gases throughout the area of the liquid whereby the gases will be discharged at temperatures close to that of the surrounding liquid; to provide an exhaust pipe or conduit with fins to dissipate the heating; to provide an improved flame sleeve enclosing the fiame which becomes heated sufficiently to maintain combustion after the burner has been started; to provide means for automatically controlling the temperature of the liquid; to provide means for increasing the temperature of the liquid without undue agitation thereof; to provide means for automatically shutting off the supply of gases to the burner if the flame becomes extinguished; to provide an improved spark ignition electrode and means to observe the operation of the spark and the flame produced adjacent thereto; to provide a neon indicator which will give continuous indication of the presence of the electric spark in the igniter and whereby the operator will know that the combustible mixture will be fired upon admission; to provide a burner which may be readily lifted out of the tank or liquid as for changing or repairs; to provide certain protective features; and to provide such other advantages and improvements as will be described more fully hereinafter.

While my improved apparatus may be used for various purposes and for heating various liquids, one of the particular uses for which it is intended is the heating of liquids used [for pickling metals such as the sulphuric acid solution used for pickling steel, and the description will be directed mainly to the burners installed for such uses.

In the accompanying drawings illustrating this invention, I

Fig. 1 is a plan view of a tank such as used for pickling steel with my improved apparatus positione therein;

Fig. 2 is a vertical sectional view taken substantially on the line 22 of Fig, 1;

Fig. 3 is an'enlarged vertical sectional view of a portion of the tank and burner taken substantially on the line -33 of Fig. 4;

Fig, 4 is an elevational sectional view taken from the right hand side of Fig. 3;

Fig, 5 is an enlarged sectional view taken substantially on the line 55 of Fig. 3;

Fig. 6 is a sectional detail of a gas mixing and protective device;

Fig. 7 is a plan view of a tank with a modified form of the burner mounted therein;

Fig. 8 is a sectional view taken on the line 8-8 of Fig. '7; i

Fig. 9 is a diagrammatic view illustrating the .burner and certain control, indicating, and protecting features; and

Fig. 10 is a detail showing a modified form of gas feeding means.

The tank l5 shown in the drawings represents a pickling tank but may indicate any suitable container for holding liquid to be heated. The burner indicated generally by the numeral I6 is of the Venturi type, although I prefer to use gas under substantial pressure instead of the zero or low pressure commonly used in such burners. The burner has a body portion I! with an enlarged combustion chamber l8. The body portion has a flange l9 which is engaged by a closure disc 20 secured thereto in any suitable manner. The venturi 2| is carried by the disc or plate 20 and projects into the cylindrical part of the body portion I! as shown in Fig. 3. The inner end of the Venturi has a burner sleeve 22 secured or aflixed thereto. This sleeve is preferably made of cast stainless steel and is of conical form with its larger end terminating in the combustion chamber. This sleeve is intended to attain a red heat when the burner is in operation which is suflicient to maintain combustion, and it also tends to properly form the flame.

The Venturi 2| is engaged by a T or coupling head 23 having a branch or inlet 24 for the air inlet pipe 25. This pipe is controlled by the valve 26 and is also preferably provided with a transverse disc or closure-21 having a reduced orifice II. The purpose of the orifice is to prevent any undue back pressure in the supply pipe which might cause injury to the air pump or other parts.

The outer end of the coupling head It has a plug or closure 29 which carries the gas jet or nozzle It that projects into the venturi as shown. 1

Gas is supplied to the jet by a supply pipe 3| having a controlling valve 82. This supply pipe may be introduced under any desired pressures.

The combustion chamber l3 has an inlet opening 34 in the wall of a bulge or projection 35 which is preferably slightly above the inner end of the sleeve 22. One end of a pilot tube 36 engages with the inlet 34 as shown in Fig. 5. The outer end of this tube has a head 31 with a conical or tapered tubular portion or extension 38 that projects into the tube 33 as shown and terminates adjacent to the inlet 34. The outer end of the tubular portion is closed by a disc 39 preferably formed of glass or transparent material and held in position by an expansion ring 40. The outer end of the head 31 is also closed by a disc 4| preferably formed of glass or transparent material, held in position by a ring 42. The disc 33 carries an electrode or terminal 43 which is supplied with high tensioned electricity through the supply wire 44 receiving current from any suitable source.

The ignition sparks are formed between the irmer or exposed end of the electrode and the adiacent walls of the extension 33 as indicated at 45.

Air is supplied through a. pipe 46 to a mixing chamber 41 where it is mixed with gas supplied through a pipe 48. These pipes are preferably provided with the reduced orifice devices 49 and 50 respectively for protecting the main lines and apparatus connected therewith. The mixed gases pass from the chamber 41 through a pipe which connects with the tube 36 at a point just below the head 31 as shown in Fig. 5. It will be noted that the space 52 between the tube 33 and the conical extension 38 gradually increases so that the gas mixture is progressively expanded toward the end of the extension where it is ignited by the electric spark which is preferably maintained in constant operation while the burner is in use. The burning gases pass into the combustion chamber i8 and ignite the mixture in the main burner which is supplied with air and gas as above described. After the main burner is in operation for a short time, the sleeve 22 becomes red hot and will maintain combustion in the main burner even if the electrode ceasedto function. The glass discs 33 and 4| provide windows so that the operation of the ignition and pilot light may be readily seen. A branch pipe 53 leads from the air pipe 48 to the cone or extension 33 slightly below the disc 39 and provides a stream of air which is introduced to the inside of the cone to keep the insulating glass disc dry and free from moisture.

I also provide means for indicating or measuring the intensity of the gas flame in the burner. For this purpose, a tube 54 i mounted adjacent to the tube 36 with its inner end connected with the bulge or projection 35 as shown in Fig. 5.

The other end of the tube is closed by means of a head II which is secured therein in any suitable manner. head II and held against a shoulder therein by means of an expansion ring 51. The end of the head II is closed by means of another glass or transparent disc 83 which is held in position by a ring II. The disc 63 serves as an insulating support for a pair of thermocouple wires 80 and 3| which preferably extend into the projection 3! for a short distance beyond the end or the tube as shown. The thermocouple wires are connected in the usual manner by means of wires 32 and 83 to an instrument 34 (Fig. 9) of the type commonly used for pyrometers but which is preferably calibrated to indicate the burner efilciency. The thermocouple wires preferably do not extend into the main flame of the burner but are adapted to measure the confined heat in and around the burner. This heat is directly proportional to the amount of gas and air being properly burned. The instrument 64 serves as a B. t. u." indicator and shows when the flame is hottest for any given setting of the air and gas and-.in this ,way is a true indicator of burner efilciency. The sight opening provided by the discs 68 and 58 permits visual inspection of the flame in the main burner whereby the operator may readily see the actual conditions of combustion.

As a further means for readily indicating the spark or ignition operation, I provide a neon tube 65 (Fig. 9) which may be mounted on an instrument panel and is preferably of spiral form. One end of this tube is connected to the high tension terminal or circuit by means of a wire 36 while the opposite end is not connected.

, Whenthe ignition is operating, the gas in the neon tube is thereby excited, causing a progressive undulating light around the spiral which is readily visible to the operator from a considerable distance. If the current is flowing and the electrode does not spark, the neon spiral will glow uniformly. If the spark electrode circuit fails or is short-circuited, the neon spiral will fail to glow or be illuminated. The use of a neon tube for indicating the condition of an ignition system provides a particularly desirable feature and is entirely novel.

The gas inlet pipe 3| may also be provided with an additional safety device comprising an automatic valve 61 which will close automatically upon failure of the gas pressure and which can only be opened manually as by means of a lever 33, such automatic valves being of well known construction.

The combustion chamber or body of the burner connects with a pipe or burner housing extension 69' which in turn is connected by means of an elbow 10 with a horizontal discharge pipe H. The discharge pipe is supported adjacent to the bottom of the tank as shown in Fig. 2 and may be provided with holes for discharging the heated gases or gases of combustion directly into the liquid to be heated as shown at 12. When the burner is to be used for pickling tanks for pickling steel, in which the liquid is dilute sulphuric acid, I have found that such direct discharge into the liquid is apt to be objectionable as causing. oo great agitation for ebullition and that it is preferable to distribute the discharge more uniformly throughout the bottom of the tank. For this purpose, I provide branch pipes or ducts 13 which lead from the main discharge pipe ll outwardly or to the sides of the tank. These pipes are closed at their outer ends by caps or plugs 14 A glass disc I4 is mounted in the and are provided with large number of small discharge holes I whereby a small quantity of gas will be discharged from each opening and the gas will be uniformly distributed throughout the area of the tank. This will tend to permit cooling of the gases or transfer the heat to the liquid so that the gases will be at substantially the same temperature as the liquid when they escape to the atmosphere.

The outer end of the pipe H is connected with a riser pipe 16 which extends to the top of the tank and is provided with a valve 11 for controlling the exhaust from the pipe to the atmosphere. This exhaust pipe and valve serves to control the agitation in the tank as by opening the valve, the pressure in the outlet ducts will be reduced and by closing the valve, the pressure will be increased, thereby increasing the volume of the gas which escapes into the liquid. This control outlet also serves to regulate the B. t. u. output of the burner and serves to exhaust the products of combustion over and above the amount required for agitation and permits the combustion of larger quantities of gas and air to raise the temperature of the liquid. It is important to know that in an apparatus of this type, the temperature ceiling is limited by the agitation for the reason that as a hotter flame is produced, the products of combustion are increased and if allowed to discharge through the liquid causing excess agitation, the increased amount of evaporation absorbs the heat gain, thus limiting the attainable heat to about 150 F. regardless of the amount of combustion. By means of my atmosphere exhaust, air and gas can be burned to the full capacity of the burner and the main portion of the products of combustion exhausted directly into the air using only a small portion for agitating the liquid. In this way, the temperature can be raised to approximately the boiling point or any desired degree and the amount of agitation easily controlled. Undue agitation caused by excess exhaust in pickling tanks is also haze ardous as the liquid is apt to be thrown out with a possible causing of acid burns to the workmen. My cooling and dispersing ducts permit control of the size of the bubbles rising from the distribution pipes, keeping them small in size and in intimate contact with the solution, thereby transferring the greatest amount of heat possible to the solution.

It will be particularly noted that a large portion of the burner and the pipesof the exhaust system are subjected to intense heat and also to the action of the dilute sulphuric acid when the burner is used in a pickling tank and the acid will flow back into the system when the ganese, silicon, carbon or iron. These alloying elements are adjusted or varied as desired, and

in some cases, aluminum bronze may also be used.

When the burner is to be operated, the valve 26 will be opened and air will be forced into the system, thereby driving the liquid out of the burner and parts connected therewith. Current will be supplied to the ignition electrode preparatory to introducing the combustible mixture to the pilot. When such mixture is admitted through the pipe 5|, it will be ignited and the name will extend down into the combustion chamber l8. Thereupon the main gas supply will be admitted through the pipe 3| and combustion will occur in the burner to the products being exhausted through the exhaust system above described. When the pilot light and burner are in operation, the combustion may be observed through the sight openings provided by the tubes 36 and 54 and the neon tube will also indicate the condition of the spark so that the entire operation is well under the observation and control oi. the operator. This is particularly important in view of the comparatively large amount of gas used and the consequent possibility of danger in the event of failure of operation.

In the pickling of steel, it has been found that the proper agitation of the pickling liquid will greatly expedite the pickling operation. The action is also particularly efiective when the liquid is heated ,to the desired temperature which may be effectively and economically done with my imconnected with a burner head 19 having an air inlet pipe 80. The burner head is closed at its upper end by a plug or closure 8| which carries the nozzle 32 that projects down into the venturi in the usual manner. A pipe 83 extends upwardly from the plug 8| as-shown in Fig. 6 and passes, through the chamber 84 which is supplied with gas through an inlet pipe 85. The

gas passes from the chamber 84 into the pipe 83 through a series of jets 86, the ends of which are beveled or tapered as shown. The amount of gas entering the pipe may be regulated by means of an adjustable sleeve 81 which fits closely over the pipe 83 and extends outwardly through a gland or packing 88 and has aflange 89 at the upper end thereof. Air at high pressure is supplied to the pipe 83 and as it passes inwardly over the tapered ends of the jets 86, will entrain the desired amount of gas for proper combustion which amount may be regulated by opening or closing more or less of the jets by means of the sleeve 81. The auxiliary or additional air supply through the pipe is in excess of the air required for combustion and its purpose is to keep the burner ducts clear when the combustible mixture of air and gas is shut off. In actual practice, the secondary stream supplies some of the air for combustion and will dilute the mixture if it is too rich. This will effect more perfect and dependable ignition and combustion. The beveled ends of the jets which extend into the high pressure air stream, provide a low pressure on the lower or feed side, so that the gas will be drawn in and be thoroughly mixed with the air. These small ports also prevent or eliminate back pressure which might cause explosive concussions to carry back to the gas pressure regulator and compressor. Such back pressure would be apt to cause damage to This figure shows a motor driven blower or compressor 80 which supplies air to the supply pipe 28. This pipe is provided with a control device 8| commonly known as a pressurestat which will open the circuit in the main supply line if the air pressure falls below a predetermined point. This device has a lever 82 for manually closing the circuit,

The air supply pipe 08 which leads to the mixing T 41 has a shut oil valve 88 which is operated by a solenoid 80. The gas pipe 48 is provided with a shut-off valve 85 which is actuated by a solenoid 88.

The gas intake valve 82 and the air intake valve 20' are operatively connected with a motor 81 which is adapted to simultaneously open and close the valves, such motor operated valves being in common use.

Current is supplied for all of the electro-responsive devices from main supply wires 80 and 88. Branch wires'I00, IOI lead from the main wires to a switch I02 which is adapted to Open and close the circuit through, the wires I03 and Ill to the motor of the blower or turbine 80. A switch I08 is positioned beyond the motor switch and controls the main circuit. The wire 88 leads directly to the pressurestat 8| and the circuit is continued from the pressurestat through wire I08. Wires I01 and I08 lead from the wires 88 and I80 respectively to the solenoid 84. Branch wires I08 and H lead to the solenoid 86 as shown. Branch wires III and II2 lead to the transformer H3 which supplies current for the ignition electrode. The wires 88 and I00 lead to a thermostatic controlled instrument I I4 which is of common or well known construction and which serves to control the operation of the motor 81. Three wires H5, H6 and Ill lead from the thermostatic instrument II to' the motor. A bulb H8 is inserted in the liquid in the tank and operates the thermostat through a suitable connection II8. This arrangement is such that when the temperature in the bulb reaches a predetermined amount, the thermostat instrument will close the circuit to the motor 81 which causes the same to close the valves 26 and 82, thus cutting off the supply to the main burner. When the temperature of the bulb falls to a predetermined degree, another circuit to the motor is closed, causing the motor to again operate and open the valves, thus again supplying gases to the main burner. The solenoids 80 and 86 will hold their respective valves open when current is supplied, but in the event of failure of current, these valves will automatically close, thus providing a desirable safety feature for the pilot.

The apparatus shown in Figs. 7 and 8 is substantially the same as that just described, but in this form of the invention, the entire burner I20 is positioned horizontally on the bottom of the tank and the air supply pipe I2I and gas pipe I22 lead up to the top of the tank where they are provided with couplings I28 and I24 so that they may be readily disconnected. The burner is connected directly with the discharge or outlet pipe I20 as shown. The outer end of this pipe or conduit is connected with a riser pipe I26 having a control valve I21 and also having a coupling I28 so that it may be readily disconnected. In the event that any repairs or replacements are needed, the couplings to the several pipes may be disconnected and the entire burner and parts connected therewith may be raised out of the tank by means of ropes or cables I28 fastened to the pipes III and I2.

The steam which is formed when water is heated in tanks such as used for various commercial purposes often becomes highly objectionable. In the operation of pickling tanks or other tanks for cleaning or treating metals, the steam or vapor is often particularly objectionable and destructive as it may contain some of the acid or alkali used in the bath. While my improved apparatus will prevent excessive discharge of steam or vapor, there will, of course, always be some formed when the liquid is heated to operating temperatures. I have discovered that such steam or vapor may be reduced or dissipated by subjecting the same to a blast or current of dehydrated air or hot gases such as the gases of combustion. When ablast of such gases is directed against the vapor rising from the evaporation, the vapor is dissipated. This apparently is caused by the greater absorptive quality of the heated and dried gases, but in any event the dissipation of such vapor is highly desirable. In utilizing this principle in the present apparatus. I provide the pipe I26 with branches or extensions I30 which will be around the top of the tank and are provided with holes I 8| directed inwardly over the liquid. Any moisture or vapor arising from the liquid may be subjected to the dehydrated air and gases of combustion being discharged through the pipe I26 and will be dissipated as by absorption, or the like.

The discharge pipe I25 is shown in Figs. 7 and 8 as being provided with radiation fins or discs I82 which may be cast integrally therewith or may be applied thereto in any well known manner. These fins or such additional radiation or heat transfer devices are intended particularly for use in heating cleaning baths, or the like, containing various chemicals or cleaning composi-- tions. The fins tend to quickly dissipate the heat from the pipe or conduit and keep its temperature close to that of the surrounding liquid thereby preventing chemical disassociation of the constituents dissolved in the liquid.

I claim:

1. In an apparatus of the character set forth, the combination of a combustion chamber,.a pipe for conducting the gases of combustion below the surface of a liquid to be heated, means for discharging some of the gases of combustion from said pipe into the liquid, an outlet pipe extending from the first named pipe above the surface of the liquid, a valve for said outlet pipe and means for directing the discharge gases from the outlet pipe over the surface of the liquid for dissipating vapor caused by the heating of the liquid.

2. In an apparatus for heating liquids, the combination of a burner having a combustion chamber, a pilot tube leading from the combustion chamber to a point above the level of the liquid which is being heated, an electric spark igniter for lighting fuel in the pilot tube and keeping it lighted, and means for indicating the operation of the spark, comprising a neon tube and a wire connecting one end of the tube with the igniter circuit whereby the gas in the tube will be caused to produce a light when the igniter is in operation.

3. A burner of the character set forth, particularly adapted for heating large quantities of liquids including a body portion having a combustion chamber and closed at one end, a venturi secured to the closed end and projecting inwardly into the body portion and having a sleeve portion extending into the combustion chamber, said sleeve portion being adapted to become sufflciently heated when the burner is in operation, to maintain combustion, means for supplying air to the venturi, a gas nozzle projecting into the venturi, means for supplying gas to said nozzle which is mixed with the air in the venturi, electric ignition means for igniting the gas and air in the combustion chamber and a discharge conduit leading from the chamber beneath the liquid to be heated, the arrangement being such that after the burner has been lighted, the projecting sleeve portion will become sufficiently hot to maintain combustion without the use of the electric ignition means.

4. A submerged burner for heating and agitating liquids comprising in combination a combustion chamber, a conduit leading from the combustion chamber for a substantial distance along below the surface of the liquid to be heated, outlet orifices spaced apart along the conduit for discharging gases of combustion into the liquid over said surface to dispel the vapor caused by I the heating of the liquid.

5. The combination with a burner having a combustion chamber, of means for supplying fuel and air to said chamber, a pilot tube opening into said chamber, means for supplying air and fuel to said pilot tube to maintain a pilot light, an electric spark igniter coacting with the pilot tube for igniting the fuel in said tube and keeping the pilot lighted, means for supplying electric current to the igniter, and a gas tube having one end connected with the circuit to the igniter and serving to indicate the operation of the igniter.

REGNER A. EKSTROM, JR.

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