US2100687A - Heating apparatus - Google Patents

Description

Nov. 30, 1937. F. H. CORNELIUS HEATING APPARATUS Filed Feb. 16, 1931 '7 SheetsSheet l INVENTOR ATToRNE g Nov. 30, 1937. F. H. CORNELIUS HEATING APPARATUS Filed Feb. 16, 1931 '7 She e'tsSheet 2 R O R INVENTOR w 0.. H m w A W W Nov. 30, 1937' F. H. CORNELIUS HEATING APPARATUS Filed Feb. 16, 1931 7 Sheets-Sheet 5 NOV. 30, 1937. CORNELIUS 2,100,687

HEATING APPARATUS Filed Feb. 16, 1931 7 Sheets-Sheet 4 m R w WITNESSZ Q g g INVENTOR Fm/M HCome/fus.

ATTORNEY Nov. 30, 1937. F, H; @RNEUUS 2,100,687

HEATING APPARATUS Filed Feb. 16, 1931 '7 Sheets-Sheet 5 WITNESS; INVENTOR ATTORNEY Patented Nov. 30, 1937 UNITED STATES PATENT OFFiCE 9 Claims.

My invention relates to heating apparatus, and it has particular relation to furnaces or the like for melting various materials or transferring heat thereto, in the course of certain commercial and industrial processes.

One object of my invention is to provide an apparatus adapted to be used in processing asphaltum, candy, resins, waxes, sterilized and evaporated milk, canning of fruits and vegetables, etc., which shall materially reduce the time required to complete the process and thus increase the production, and furthermore, whereby hydrocarbon materials may be properly heated and melted without burning, scorching or coking.

A second object of my invention is to provide a heating apparatus of the type set forth, in which two cooperative tanks are employed, in one of which the melting or heating is partially completed, and in the other of which additional heating to the required temperature is effected while the material is being vacuum treated.

A further object of my invention is to provide a heating apparatus, in which heated gas is passed along a heat-transferring area, at least a portion of the gas being recirculated along that area.

Another object of my invention is to provide a heating apparatus, in which heated gas is conducted in heat-transferring relation to a meltable or other material, at least a portion of the gas being recirculated to vary the temperature of the material.

A further object of my invention is to provide an apparatus of the character set forth, in which the material also is circulated, when melted, past the heat-transferring devices.

Another object of my invention is to provide an apparatus of the type in question, in which the portion of heated gas so recirculated may be determined or varied at will.

A further object of my invention is to provide a novel automatic control system for apparatus of the type set forth above, whereby the heating apparatus may be operated automatically and intermittently to best perform its functions.

Other objects of my invention will become evident from the following detailed description, taken in conjunction with the accompanying drawings, wherein,

Figure 1 is a top plan view of a heating apparatus constructed in accordance with my present invention,

Figure 2 is a view, in end elevation, with parts broken away for clearness, of the apparatus shown in Figure 1,

Figure 3 is a view, in longitudinal section, taken at right angles to Figure 1,

VI-VI of Figure 3, and

Figure '7 is a diagrammatic view of a system of control utilized in connection with the apparatus shown in the other figures.

Referring to the drawings, the structure here shown comprises a charging tank I, and a vacuum tank 2, which are placed side by side within a furnace or outer casing 3, together with gas or other fuel inlet and control means 4, draft-inducing or heated gas circulating apparatus 5, a pump motor 6 which is utilized in connection with the vacuum tank 2, and a propeller apparatus 1 that is utilized in connection with the charging tank 1.

The furnace or outer casing 3 is, in general, rectangular in shape, but at the front end is provided with a depressed shelf or ledge 8, upon which the circulating apparatus 5 is mounted.

This casing may be of any suitable doublewalled, heat-insulated construction, and is shown as comprising heavy structural steel angles 12 at the lower corners, which are joined by a heavy plate l3 and upon which rest the main supporting transverse members or H-bars l5. The plate or sheet l4, marking the bottom wall of the two compartments within the casing 3, rests upon these H-bars l 5 and the space between the plates l3 and I4 is filled with a suitable heat-insulating material Hi. In a similar way, the remainder of the furnace or casing is composed of double steel walls I1, l8, l1, l8, etc., between which the heat-insulating material i6 is packed.

3 The charging tank I is about twice as large as the Vacuum tank 2, and occupies a correspondingly larger compartment within the outer casing, the two spaces corresponding to the charging and the vacuum tank being fully separated by a heavy vertical plate II, which extends the full length of the apparatus. The plate H is secured to the top and bottom inner plates of the furnace, by means of suitable angles or the like l9.

The charging tank comprises a rectangular box having side and end plates or walls 20 and 2|, which are rigidly held in position by means of suitable angles 22 and 23, mitered at their abutting ends and welded or bolted to the walls. For

the purpose of laterally stiifening the charging 5 tank, a plurality of channel members 24 extend at intervals across the tank, about midway between the top and bottom thereof, the ends of these channels resting upon suitable angles 25, which also are secured to the side plates 20.

The vacuum tank 2 is likewise of rectangular form, and comprises side and end walls 26 and 21. The remainder of the construction of this tank is similar to that of the charging tank which has just been set forth, and no further description of these portions of the vacuum tank is, therefore, deemed necessary here. It will be noted that, whereas the charging and vacuum tanks abut against the top and bottom inner walls of the furnace, vertical side spaces 39 to 33, inclusive, are provided on each side of the two tanks, that is, a space 30 is provided between one vertical inner wall of the furnace and the corresponding vertical inner wall of the tank i, while a corresponding space 31 is provided between the tank and the separating plate II. Spaces 32 and 33, on each side of the vacuum tank 2, correspond to spaces 31 and 39, just described.

The charging tank I is provided with a charging door mechanism 3 of peculiar construction, comprising two quarter-round spaced vertical side walls 29, resting upon the top of the furnace above the middle section of the charging tank l. Between these walls is located the door proper, having an upper side or wall 3? and a lower side or wall 39, separated by heat insulating material 39. The door is hinged at the inner edge of its upper wall 37 and may be opened by means of a counter-weighted handle 49. The door proper is beveled or inclined downwardly on all four sides, as indicated at 4!, to fit correspondingly incline-d surfaces 42 in the top wall of the furnace. Thus, when closed, the door proper tightly fits the inclined surfaces d2. When it is desired to deposit material in the charging tank, this door may be opened by its handle M, as previously mentioned, to permit this deposit of material from the adjacent outer side of the charging tank.

The purpose of the door is primarily to provide a simple self-cleaning equipment. The door proper fits closely within the illustrated quarter-round walls 29, whereby any material, such as asphaltum, clinging to the door, will be scraped off two sides when the door is rotated into its closed position, around its hinges. -At the same time, the heavy door proper, with its beveled edges, serves, upon being closed, to squeeze any material away from the inclined surfaces 42, in the upper tank wall, thus providing means for further automatically cleaning both the door and its receiving opening, without requiring any special attention.

Near the bottom of the charging tank I, and extending completely through it, is placed a tubular apparatus or hollow device 43, for receiving heated gases and rapidly passing them in heat-transferring relation with the asphaltum or other material to be heated or melted, as subsequently described.

The device 43 comprises a top plate or wall 44 resting upon angles 49 and extending for something over half of the length of the charging tank, from the rear wall thereof, as clearly shown in Figure 4. Attached to the inner end of the plate 44, and forming a continuation thereof, is a coarse mesh screen 45, through which the liquid material being heated may pour onto one end of the heating tubes 56, about to be described.

The tubes 46 are very narrowin the transverse direction of the tank, and relatively long in the vertical direction. Each rectangular tube is welded or otherwise secured at its top wall to the plate M, and is divided into three longitudinal sections 41, byfmeans of spacers 48. The receivconstruction shown ing end of the tubes 46 is located just outside the front end of the charging tank, and the delivery end just beyond the rear wall of the tank.

In'front of the charging tank is located a fire box or combustion chamber 55, which is shown in plan view, with parts broken away, in Figure 4, while a companion chamber 5|, disposed in front of the vacuum tank 2, is shown in vertical section in Figure 3. In order to simplify the drawings, it will be noted that corresponding parts in the fire boxes 5| and 5! in the ensuing description, are correspondingly designated; that is, parts in the vacuum tank fire box 5| corresponding to parts in the charging tank fire box 5!, will bear a corresponding reference character with a prime.

The fire boxes lead into the receiving ends of the tubular heat-transferring devices 43 in the charging tank, and 93 in the vacuum tank, the latter device 93 being a similar one in every way to the device 43, but, of course, being smaller in its lateral dimension because of the smaller width of the vacuum tank. To prevent heated gases from initially flowing anywhere except through the tubes in question, the vertical front walls 59 and 59 of the charging and vacuum tanks, are disposed near the inner ends of the fire boxes, extending otherwise from the inner bottom wall of the furnace to the inner top wall thereof. The top walls 64 and 6-4 of the two fire boxes are disposed some distances below the shelf or ledge 8 of the furnace, in order to leave spaces 66 and 66 above the top walls 54 and 94. The inner ends of these spaces are closed off by transversely extending plates 52 and 52, which extend downwardly on each side of the charging tank and the vacuum tank proper, being secured to the furnace side walls by angles 53 and 53', through the side spaces 39 to 33, inclusive.

In this way, the products of combustion in the fire box must enter the tubular devices at the receiving ends thereof, and, after passing through them and into the several side spaces 39 to 33, inclusive, and thus through the circulating apparatus 5, into the spaces 86 and 69' above the fire boxes, will return, at least in part, above the fire boxes to the receiving ends of the tubular devices 43 and 93, as hereinafter more fully set forth.

The combustion chambers proper are designated by reference characters and 54' in the charging and vacuum tanks respectively, and

near the bottoms thereof, inclined perforated grids or batteries of perforated tubes 55 and 55' are located. These tubes are connected to the fuel gas intake apparatus 4, and thus provide the source of heat for the entire apparatus.

Sloping upwardly from points on the bottom wall [4 of the furnace, near the receiving end of the tubular devices 43 and 93, are baffles 56 and 56', which are respectively held in position on the sides of the fire boxes by suitable brackets 51 and 51. Extending substantially horizontally from the upper edges of the front walls 6| and 6! of the fire boxes proper 54 and 54, are second baflles 58 and 58', the inner ends 59 and 59 of which are bent downwardly in parallel relation to, and spaced a short distance from, the upper ends of the corresponding bafiles 56 and 58. The horizontal baffles 58 and 58' may be held in position in any suitable way, as by brackets 62 and 62' associated with the vertical walls 6| and GI and brackets 60 and 60 located near the bent ends 59 and 59. A narrow channel or passage i2 is thus provided as the only outlet from each fire-box between the corresponding baffles,

whereby the heated gas in each fire-box is directed at high speed towards the receiving end of the corresponding tubular apparatus 43 or 93.

It will be noted that openings and 65, extending transversely across the respective fireboxes, effect communication between the respective spaces 66 and 66' and the spaces above the horizontal brackets 62 and 62', for a purpose to be hereinafter set forth. An opening 63 in the vertical wall 6|, for example, is normally closed by a vertical gate hinged at its upper end and tightly resting against the upwardly curved end of a support or plate 69 for the gas burners or tubes 55'. A chain H connects the lower end of the door 70 to a door 13', having a plurality of louvres therein, whereby air is normally admitted from the outside through the space between the doors 73 and 10, under the plate 69', and thus upwardly through its central perforated portion 15' to the burner 55'.

The purpose of the inner door 70' is to permit inspection and repair, as, upon movement of the louvered door 13 on the hinges at its upper end, the chain ll causes the inner door 70 to likewise open, thus giving the desired access. Normally, however, as illustrated, the only passage for air to be drawn in and unite with the fuel gas, is through the passage mentioned above. No damper or air regulator is needed in this particular part of the furnace, as, of course, the amount of air drawn in is dependent upon the amount which is vented by the circulating apparatus 5, as subsequently set forth.

During normal operation, the charging and vacuum tanks are filled, at least half full, with melted asphaltum or other material being heated, and the temperatures thereof are recorded by thermostats 14, inserted through the sides of the furnace, near the bottom thereof, into the charging tank and the vacuum tank, respectively, as indicated in Fig. 4. These thermostats are used to automatically control the operation of the furnace in accordance with the temperature of the liquid, as hereinafter more fully described. In addition, automatic control devices af a similar character, for regulating the maximum temperature of the liquid, are indicated at 61 and 61, at the front of the furnace, above the doors leading respectively to; the charging and vacuum tanks, these control devices extending into the passages 66 and 66'.

Near the rear end of the charging tank I, and at the bottom thereof, a plurality of pipes 76 extend rearwardly and, by means of an elbow T! and Ts 18, forming a sort of manifold, are connected to a large centrally located pipe 79, from which extends a vertical pipe 80, into a propeller box 8|, which, by means of a suitable nipple 82, communicates with the charging tank I, at a point just above the tubular device 43, as clearly shown in Figure 3.

Within the propeller box 8| is disposed a suitable propeller 83, near the nipple 82, to draw liquid through the pipes 76, up into the box 8|, and thence discharge it through the nipple 82 onto the plate 44, constituting the top wall of the tubular device 43. This liquid is then discharged through the screen 45, over the front end of the tubes 46, thence horizontally along the tubes, and then to the bottom of the charging tank, where it may again circulate through the pipes 16, etc. In this way, a rapid circulation of the liquid in the charging tank I may be effected, keeping it in close contact with the heattransferring tubes 46 at all times.

The propeller 83 is attached to the end of a shaft 84, which passes through a suitable stuffing-box 85 and is coupled to a propeller motor 86, resting upon a shelf 81, which is supported on the rear end of the furnace 3 by means of suitable brackets 88, for example.

From one end of the manifold into which the pipes 16 extend, that is, near the separating plate II, a pipe 89 extends vertically, being provided with a valve 98, having a handle 9! extending outside of the furnace, the pipe 89 being connected to a pipe 92, at right angles thereto, which extends into the vacuum tank 2, for a purpose to be described.

As previously mentioned, near the bottom of the vacuum tank 2 is disposed the tubular apparatus 93, comprising a plurality of tubes similar to the tubes 46 of the tubular apparatus 43 in the charging tank I, together with a top plate 94 of substantially the same length as the top plate 44 of the apparatus 43 and a coarse mesh screen 95, forming a continuation of the plate 94 on the end next to the fire box 5!. The function of this screen is to permit liquid to flow down over the tubes of the apparatus 93, near the receiving end thereof, for a purpose to be hereinafter set forth.

Near the top of the vacuum tank 2, are disposed two screens extending the .full length thereof, and respectively numbered $9 and 1%.

although not as coarse as the small screen 95 of the tubular apparatus 93, while the upper screen we is of relatively fine mesh and is located just below the top wall of the tank.

The function of these screens is to break up any bubbles on top of the hot liquid in the vacuum tank 2, by means of capillary action. Without these screens, large bubbles which form would eventually get into the vacuum system and clog it up, particularly where the material being treated is asphaltum, for example, or any material having a tendency to foam or form large bubbles. By the provision of these two screens, however, first a coarse one and then a fine one, all such bubbles are entirely broken up and the remains drip down into the tank again, so that the vacuum system is maintained free from such clogging deposits.

Above the inner end of the vacuum tank 2, and 5 forming a portion of the upper wall thereof, is a transparent plate IGI, preferably of plate glass, which is suitably bound around the edges by metallic strips H12 and bolted in place through such strips by means of bolts me. In the nar- I row area between one edge of the plate I64 and the corresponding upper corner of the vacuum tank 2, is disposed a vacuum intake pipe its, which leads to a vacuum pump (not shown) of any suitable type. This pump operates continuo-usly during the operation of the illustrated furnace, in order to maintain a suitable degree of vacuum within the tank 2 and thus assist in completing the heat treatment of the asphaltuni or other material being processed.

By means of the plate till, the operation of the vacuum tank 2, in particular the spray from the perforated pipe loop M8, to be subsequently described, may be readily observed, and at the same time, because of the use of two separate tanks in this furnace, including a charging door apparatus 34 on top of the charging tank only, the vacuum tank is maintained air tight at all times, since the glass plate EQI does not need to be disturbed for charging or the like, and never needs to be removed, except in case of repairs to the apparatus inside the vacuum tank.

The fuel intake mechanism 4 is shown as adapted for supplying fuel gas to the fire box burners and 55', and comprises an intake pipe I05, which divides into two branches I06 and Il'l'l, which, in turn, communicate through electric gas valves IE8 and N19 to pipes Hi3 and III, which respectively lead into the charging tank and vacuum tank burners 55 and 55.

The electric gas valves may be of any well known type, merely comprising coils for operating suitable gas valves, whereby the flow of fuel gas into the respective burners may be controlled as desired. These particular valves are controlled automatically in accordance with certain operating conditions, as described in connection with Figure '7.

The draft-inducing, or gas-circulating apparatus 5 comprises two portions, respectively functioning in connection with the charging tank and the vacuum tank, but interconnected for certain reasons disclosed below. All of the apparatus 5 is conveniently disposed upon the ledge or shelf 8 at the front end of the furnace.

For the charging tank, a. suitable electric motor H2 is disposed to drive a centrifugal fan or circulating means H3, the motor and fan being mounted on a suitable pedestal or base I I4. The inlet for the fan H3, leading into the central portion thereof, is numbered I33, and extends into the upper portion of the space just in front of the charging tank I. The outlet H5 for the fan communicates with a central pipe or conduit I I8, which also communicates with the other portion of the circulating apparatus 5. A butterfiy valve or damper H1 is disposed within a horizontal opening H8, leading to the space 86 above the fire box 5I, while a second butterfly valve or damper H9 serves to regulate the communication between the outlet pipe H5 and the central pipe H6. These butterfly valves may be provided with any suitable operating handles or quadrants, whereby they may be placed and secured in any desired position, for a purpose to be subsequently set forth.

Leading out of the upper middle portion of the central pipe H6 is an exhaust pipe I20 for venting the desired portion of the gases generated in the two tanks to the atmosphere, as hereinafter explained.

The vacuum tank 2 is associated with the other portion of the circulating apparatus 5, comprising an electric motor IZEE for driving a centrifugal fan IZ'I, similar to the fan H3 and provided with similar inlet and delivery pipes, respectively designated as I2I and I29. The pipe I29 likewise leads into the central pipe H6, through a butterfly valve I32, and also communicates, through a butterfly valve I363, to a horizontal opening I3I leading into the space 66 above the firebox 5| It will be understood that the valves I30 and I32 may be similar in construction and operation to the previously described valves II! and H9.

The operation of the circulating apparatus 5 may be described as follows. Depending upon the relative setting of the butterfly valves H1 and H9 in the case of the charging tank, and I3il and I32 in the case of the vacuum tank, any desired portion of the gases drawn into or created within the respective fire boxes may be exhausted to the atmosphere through the central pipe I28 or recirculated into the fire boxes and thence through the tubular apparatus 43 or 93,

as the case may be. So long as the gas burners 55 and 55' are operating, it is, of course, necessary to draw air through the louvred doors I3 and I3 to furnish the requisite oxygen for the combustion of the gas and a quantity of gas must be expelled by the centrifugal fans H3 and I21, out through the exhaust pipe I28, corresponding to the amount of air that is drawn in to each of the fire boxes.

In other words, taking the charging tank, for example, assume that under given conditions the fan I I3 is producing a working pressure sufficient to handle I5 pounds of products of combustion in a certain period of time and that it is required to concurrently draw 1 pound of air and gases to be burned into the fire box, thus necessitating the concurrent venting of gas of this same weight through the exhaust pipe I20, and that it is thus further required to recirculate 14 pounds of gases through the space 66 above the fire box into the tubular apparatus 43, thence around the sides thereof through the spaces 30 and SI, as previously described, and then into the inlet pipe I33 of the centrifugal pump H3, whence the recirculated gas is blown past the butterfly valve I I1 into the space 66 again. Stated in greater detail, the recirculated gas will flow through the opening H8 into the space 66 above the fire box, and thence through the opening 65 over the horizontal baffle 62 and along the inclined baflle 56 to the receiving end of the tubular apparatus 43. This portion of the gas thus again flows along with the newly-created gas through the heat-transferring tubes 46 and thence, as previously described, back to the centrifugal fan HE. A recirculation of this particular portion of the gas is thus effected, the remainder of the gas being exhausted to the atmosphere.

The purpose of this recirculation of heated gas is to modify, downwardly, the temperature of the liquid or other material being treated or melted. The gases coming directly from the fire boxes, of course, are at the highest temperature of anything in the furnace and initially flow through the tubular apparatus 43, for example, to transfer a portion of their heat to the liquid or other medium surrounding the apparatus 43. A recirculation of a portion of the gas after it has thus been cooled by reason of its heat-transferring activity,

reduces the temperature of the resultant gases 5 flowing through the tubes 46 and therefore the resultant temperature of the surrounding liquid or other material. This cooling of the resultant gas is especially important when treating material such as asphaltum or the a temperature would cause coking or scorching of the material.

The amount of air to be drawn in and the amount to be recirculated is dependent upon or determined by the fiue gas temperatures at the receiving and delivery ends of the tubular apparatus 43. At the receiving end, the gas temperature should be the maximum required to produce the desired treatment of the asphaltum, for example, whereas at the delivery end, the temperature of the gas, in the interest of efliciency, should not be much higher than that of the material being treated.

If the temperature of the resultant or mixed gases entering the tubular apparatus 43 is too high, the amount of fuel gas being burned may, of course be reduced. However, the preferred method is not to vary the rate of admission of fuel gas after this has once been set in connection with treating a given material, but to so adjust like, where too hot the butterfly valves I I1 and M9, for example, as to produce the desired variation of recirculated gas and, therefore, the temperatures of the gases at the two ends of the tubular apparatus 43.

The results accruing from this adjustment of the butterfly valves I I I and I I9 may be explained as follows.

Since the volume of gas within the charging tank and its fire box is the same at all times, it follows that variations in the portion or weight of the gas recirculated is dependent upon the pressure within the charging tank, as determined by the setting of these valves and the resultant pres-- sure that is built up by the centrifugal fan H3. The more nearly closed the valve I I l, the greater the pressure that is delivered by the fan and the less the weight of gas per second that passes through the valve I I! along the path of recirculation, and the nearer to the maximum temperature of the fire box gases will the temperature of the resultant or mixed gases passing through the tubular apparatus become, by reason of being mixed with a correspondingly small weight of the cooler recirculated gases.

On the other hand, if the valve II! is opened wide, the pressure delivered by the fan will be low, and the weight of the recirculated gas flowing through the large opening past the valve will be accordingly increased to cause a corresponding cooling of the resultant or mixed gases flowing through the tubular apparatus 43.

In all cases, the adjustment of the other valve I I9 is such as to vent to the exhaust pipe I20 the proper weight of gas at the then existent pressure, this weight corresponding to the required weight of air and fuel gas drawn into the fire-box.

In general, therefore, the temperature of the gas traversing the tubular apparatus 43, for example,

and therefore, the ultimate temperature of theliquid or material being treated may be varied over a wide range.

The electric motor 6, disposed on top of the furnace, near the rear end thereof, and above the vacuum tank 2, is provided with a suitable shaft I38, which extends downwardly into the vacuum tank through a. suitable stufiing box I31 into a centrifugal pump or impeller I38, resting upon the top plate 94 of the tubular apparatus 93. The pump I38 is provided with a suitable inlet pipe I35, which extends downwardly near one side of the vacuum tank next to the side space 33, to substantially the bottom of the tank, whereby liquid from the bottom of the tank may be drawn into the center of the centrifugal pump I38.

For the purpose of preventing the operating shaft I36 from rotating in the body of liquid at times contained in the vacuum tank, a cylindrical enclosing pipe or shell Iii! extends between the top of the pump I38 and the bottom of the stufiing box I 31, the fit at the ends of the pipe, of course, being fluid tight. The operating shaft I 36 is thus free to rotate within an air shaft, and any leakage of air through the stufiing box I3'I into the pipe Ifiiii is conducted through a side pipe I l-I, located just below the coarse lower screen 39, to a space in the vacuum tank that is always above the liquid level. This construction prevents the leakage of air bubbles through the liquid, which would be an undesirable condition. Any air thus leaking into the tank is, of course, readily exhausted through the vacuum pump intake I84.

The delivery pipe I42, for the pump I38, is suitably connected to the outer shell thereof, and communicates with a manual discharge pipe I43,

having a hand operated valve I44, located outside the furnace and fitted with a suitable nozzle I45, whereby heated liquid, after the completion of its treatment, may be manually drawn olf into suitable receptacles at any time. The delivery plpe near the top of the vacuum tank, provided, of course, the valve I45 is open, the valve being controlled by means of handle I4? located outside the furnace.

From Figure 4, it will be noted that the pipe loop I it? comprises a pipe I49, extending alongside the outer wall of the vacuum tank, a shorter pipe I50 extending transversely across the tank, a second long pipe I5I on the other side of the vacuum tank, and a second short pipe I52 returning to the pipe I49, close to the point where the pipe I I-2 communicates with it.

The loop I48 occupies a substantially horizontal plane, and the lower walls of the entire loop are suitably perforated, as illustrated at I55 in Figure 3, whereby the liquid delivered to this loop in the vacuum tank may be suitably sprayed downwardly onto the top wall 94 of the tubular apparatus 93.

This spray is the most efficient method of increasing the surface of the material without changing its volume and is particularly valuable in the case of material such as asphaltum, having a tendency to foam. Furthermore, the spray is adapted to remove all volatile matter in a short period of time, which is exhausted through the vacuum pump intake I04.

The pipe 89, extending from the manifold at the lower rear corner or the charging tank I, was previously described as extending upwardly through the manually operated valve 99 to a hori zontally extending pipe 92. This pipe, in turn, after extending into the vacuum tank 2, communicates with a horizontallyextending pipe I53, located in the same plane as the pipe loop I48.

Thus, upon opening the valve 90, when the material in the charging tank has reached the proper temperature, liquid will be drawn, by reason of the reduced pressure in the vacuum tank, through the pipes 89, 92 and I53, into the spray loop I48. The sprayed liquid falls upon the top plate 94 of the tubular apparatus 93 and then pours downwardly through the screen 95, over the receiving end of the corresponding tubes and thence to the bottom of the vacuum tank. Liquid is thus transferred from the charging tank to the vacuum tank until the desired quantity is deposited in the vacuum tank, when the communicating valve 90 is closed.

It will be understood that the valve I46 in the delivery pipe I42 from pump I35, is closed until the liquid has been deposited in the vacuum tank, and it is desired to subject the liquid to further treatment. In this case, the valve I46 is oper ated by the handle I41, and the pump I38, which is started at about the same time by connecting the electric motor 5 to the supply circuit, then delivers liquid to the pipe loop I48. The liquid sprayed from this loop falls on the plate 94 on the tubular apparatus 93, and thence through screen 95 and along the tubes to the bottom of the tank, as just described. The inlet pipe I39 of the pump I38 then sucks it up upwardly and effects a recirculation through the pipe loop, etc., as long as the pump is operating.

Referring to the electrical diagram of Figure 7., it will be noted that a supply circuit I55 is connected to two branch circuits I5! and I58.

The branch circuit I51 includes, in series relation, the contact members of thermostat I4 in the charging tank and the contact members of the maximum temperature control apparatus 91 in the fire box corresponding to the charging tank. The coil of the electric gas valve I98, the propeller motor 86 and the circulating motor I I2, all of which again correspond to the charging tank, are connected in parallel relation beyond the thermostat and maximum temperature control contact members. Consequently, upon closure of the thermostat, which is closed except when the temperature of the liquid is too high, and upon closure of the maximum temperature control, which is likewise closed except when the temperature in the space above the fire box is too high, the fuel gas is admitted to the burner, the circulator motor is operated to induce a draft and the propeller motor is operated to circulate liquid in the charging tank. In this way, the temperature of the liquid and of the fire box are automatically maintained within predetermined limits, dependent upon the setting of the devices I4 and 61.

In a similar way, the branch circuit I58 includes, in series relation, the contact members of the thermostat I4, and of the maximum temperature control device 61', to the vacuum tank 2. The coil of the electric gas valve I99 and the circulating fan I26 are connected in parallel relation beyond the contact members just mentioned. Consequently, upon operation of the thermostat I4, when the liquid in the tank is too hot, or upon operation of the device 61', when the fire box temperature, corresponding to the vacuum tank, is too high, the fuel gas intake and the circulating motor are temporarily cut out of operation.

The motor 6, for the pump I38 in the vacuum tank, is normally operated continuously, while the vacuum tank is in operation, being controlled, for example, by a switch I59 which connects it directly to the branch circuit I58.

It will be seen, therefore, that I have provided afurnace for melting or heat-treating various materials, such as asphaltum, candy, milk, fruits, etc., whereby the material is first dumped through a self-cleaning door structure 34, into the charging tank, in the bottom of which heattransferring tubular apparatus 43 is disposed to receive heat directly from a fire box 5| and rapidly transfer the heat to the surrounding liquid or solid material. Depending upon the setting of the valves in the circulating apparatus 5, any desired amount of heated gas may be recirculated, as previously described, thus correspondingly modifying the temperatures of the material being treated to any desired degree. At the same time, the liquid in the charging tank is circulated over the tubular apparatus 43 and between the tubes thereof, by means of the propeller 83.

When conditions are proper, the valve 90 isopened and liquid is drawn into the spray loop M3 in the vacuum tank 2, to be sprayed onto and through the tubular apparatus 93 and thence, when the new conditions are proper and valve I46 is opened, drawn through the pump I38, back to the loop spray I48, and recirculated, as previously set forth. The material is thus heat treated in the charging tank for a certain period, and then the remainder of the treatment is carried on under a suitable vacuum in the vacuum tank 2.

It will be appreciated that, by substituting for which correspond valve 90, a float to maintain a given level in the vacuum tank, the material may be transferred automatically from the charging tank to the vacuum tank.

At the same time, there is a circulation and recirculation of heated gas in the vacuum tank, which is provided with its own fire box 5|, whereby the heated gas is drawn through the tubular apparatus 93 and thence around the sides thereof to the corresponding fan I2'I of the circulating apparatus 5. Here again, the setting of the valves I39 and I32 determines the rate of heat transfer through the tubular apparatus 93.

The efficiency and effectiveness of my furnace is testified to by the fact that, heated treating tanks for asphaltum, for example, it is necessary to apply steam heat at 200 pounds pressure for about 40 hours and then vacuum treat the material while being steamheated for 8 hours more, or a total of 48 hours, my apparatus will successfully perform the same complete process in a total of 4 hours, about 2 hours being spent in the charging tank and 2 hours in the vacuum tank.

It will be noted that the vacuum tank is about one-half as large as the charging tank. Nevertheless an efiicient continuous process is maintained in the furnace, for the following reasons. As material is drawn from the charging tank to be treated in the vacuum tank, there is a large enough body of liquid remaining in the charging tank to permit submersion of additional new material, such as lumps of asphaltum, within the heated liquid, so that a quick melting of this new material is provided for, and by the time this new material is thoroughly mixed and melted, liquid may be drawn out of the vacuum tank for use, and new material transferred. from the charging tank to the vacuum tank.

I do not desire to be restricted to the specific structural details or arrangements of parts herein set forth, as various modifications thereof may be effected Without departing from the spirit and scope of my invention. I desire, therefore, that only such limitations shall be imposed as are indicated in the appended claims.

I claim as my invention:

1. In a heating apparatus, the combination with means for producing heated gas, of means for containing a meltable material, means for conducting said gas in heat-transferring relation to said material, means for recirculating at least a portion of said gas to said conducting means to vary the temperature of the gas therein, means for exhausting any remaining portion of' said gas, means for circulating said material, when melted, on top of and past said gas-conducting means, and means responsive to the temperature of said gas at a predetermined point for controlling the circulation of said material.

2. In a heating apparatus, the combination with means for producing hot gas, of means for containing a meltable material, hollow means extending through said containing means for initially receiving said gas and transferring heat to said material, means for recirculating a portion of said gas through said hollow means to modify the temperature of the gas therein, means for exhausting the remaining portion of said gas, walls spaced from said containing means, conduit means positioned in the space between said containing means and communicating with said containing means above whereas in steamone of said walls and and below said hollow means, further conduit means for connecting said other conduit means, and a motor-driven impeller located in said further means for circulating said material, When melted, over and under said hollow means.

3. In a heating apparatus, the combination with means for producing heated gas, of a first receptacle for containing a meltable material, means for conducting said gas in heat-transferring relation to said material to melt the same, a second receptacle of substantially smaller capacity than said first receptacle constituting a vacuum tank for receiving and treating only a portion of said material when melted to thereby leave a body of melted material in said first receptacle for immersing new solid material to be melted and providing a high rate of heat exchange for said new solid material.

4. A heating apparatus comprising a receptacle for receiving a meltable material, means for producing a heated gas and conducting it in heat-transferring relation to said material to melt the same, a second receptacle, means for conveying said material when melted to a certain level in said second receptacle, vacuumproducing means for withdrawing the air from above the level of said material in said second receptacle, and screen means above the level of said material in said second receptacle and also above said certain level and below the point of application of said vacuum-producing means for breaking up any bubbles formed on said material during the operation of said vacuum-producing means.

5. A heating apparatus comprising a container for receiving a meltable material, means for producing a heated gas and conducting it in heattransferring relation to said material to melt the same, a second container, means for conveying said medium, when melted, to a certain level in said second container, vacuum-producing means for withdrawing the air from above the level of said material in said second container, and screen means comprising a relatively coarse mesh screen above the level of said material in said second container and a finer mesh screen above said coarse mesh screen for breaking up any bubbles on said material during the operation of said vacuum-producing means, said screens both being located between said certain level and the point of application of said vacuumproducing means.

6. In a heating apparatus, the combination with means for producing hot gases, of means for containing a meltable material, means for circulating said material therein when melted, means for conducting said gases in heat transferring relation to said material, means for recirculating at least a portion of said gases to said conducting means to vary the temperature of the gases therein, adjustable means for exhausting a portion of said gases, thermostatic means responsive to the temperature of said gases ad- 7 jacent the region of their production, and thermostatic means responsive to the temperature of said material, said thermostatic means being in series relationship and controlling simultaneously said material circulating and gas conducting means.

'7. In a heating apparatus, the combination with means for producing hot gases, a burner therefor, and an electrically controlled valve for said burner, of means for containing a meltable material, means for circulating said material therein when melted, means for conducting said gases in heat transferring relation to said material, means for recirculating at least a portion of said gases to said conducting means to vary the temperature of the gases therein, adjustable means for exhausting a portion of said gases, thermostatic means responsive to the temperature of said gases adjacent the region of their production, and thermostatic means responsive to the temperature of said material, said thercontrolling simultaneously said material circulating and gas conducting means and said burner valve.

8. In a heating apparatus, the combination with means to supply fuel and air thereto for combustion thereof, means for producing heated gas from said fuel, means for turning on and off the supply of fuel, of means for containing a meltable material, means for conducting said gas in heat-transferring relation to said material, means for recirculating at least a portion of said gas to said conducting means to vary the temperature of the gas therein, means for exhausting any remaining portion of said gas, means for circulating said material, when melted, on top of and past said gas-conducting means, and means responsive to the temperature of said gas at a predetermined point for controlling the circulation of said material and said means for turning on and off the supply of fuel.

9. In a heating apparatus, the combination with means to supply fuel and air thereto for combustion thereof at substantially fixed rates, means for producing heated gas from said fuel, means for turning on and oif the supply of fuel, of means for containing a meltable material, means for conducting said gas in heattransferring relation to said material, means for recirculating at least a portion of said gas to said conducting means to vary the temperature of the gas therein, means for exhausting any remaining portion of said gas, means for circulating said material, when melted, at a substantially fixed rate on top of and past said gas-conducting means, and means responsive to the temperature of said gas at a predetermined point for controlling the circulation of said material and said means for turning on and off the supply of fuel.

FRANK H. CORNELIUS.

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