USRE20091E - Vaporizer for vapor burners - Google Patents

Description

Sept. 1,1936. 5. G. KNOX VAPORIZER FOR VAPOR BURNERS Original Filed Jun so, 1928 2 Sheets-Sheet. 1

Y INVEVNTOR SAMUEL L. 6. lovax ATTORNEYS Sept. 1, 1936.

S. L. G. KNOX VAPORIZER FOR VAPOR BURNERS Original Filed June so, 192a 2 Sheets-Sheet 2 INVENTOR JAMUEL L. 6. lflvox Reissued Sept. 1, 1936 PATENT OFFICE VAPORIZEB. FOR VAPOR BURNERS Samuel L. G. Knox, Englewood, N. 1.

Original No. 1,840,588, dated January 12, 1932, Serial No. 289,556, June 30, 1928. Application for reissue March 25, 1935, Serial No. 13,003

10 Claims. (Cl. 122-32) v However, any installation for vaporizing the This invention relates to vaporizing hydrocarbon oils, so that they may be burned, under a boiler or otherwise, as vapors.

When a source of heat requires close regulation to wide and sudden changes in load, as for example in steam actuated excavating machinery, itis for'several reasons highly desirable to use oil for fuel. Oil is everywhere available, is easier than coal to transport and handle, and can be burned without an ash residue and with practically no smoke. An oil flame is more easily adapted to widely varying loads, on account of the elimination of the heavy fire bed necessary with solid fuel, and because of the very great ease with which the rate of burning of oil can be suddenly and considerably increased or diminished.

Being more readily adaptable to automatic control, an oil burner will require less attention than solid fuels, thereby allowing a reduction in the number of men required to run the machinery.

When petroleum oils are used to fire a boiler, the oil may be burned as an atomized fluid, or it may first be vaporized and then burned as a gas.

' In the ordinary types of atomizing oil burner, the necessary draft must be obtained by a tall stack, a steam jet, or an air jet. A tall stack is generally undesirable, often impossible; and at best,-since'the draft is to a large extent dependent on atmospheric conditions, it is uncertain andwill frequently cause an excessive flow of air, which is detrimental to economy. A steam jet uses up watera serious consideration in a condensing engineand requires an independent source'of power when starting up with a cold boiler. An air jet is an added complication, and, when used with a steam plant, also requires an independent source of power at starting. All these would also, for eflicient work, require additional means to regulate the draft in proportion to the-amount of fuel burned.'

Thisdifliculty of forced draft can be obviated by vaporizing the oil before burning it, since, by means of a tube having an air inlet, oil vapor can be made to entrain the right amount of air tocause complete combustion; In a properly designed burner burning fuel supplied to it in the form of vapor or gas, the amount of air drawn in can be made to balance the amount of gas burned so closely that additional regulating means is not required. Since the air and the vaporized oil are intimately mixed before combustion begins, the flame produced is quite short, allowing;the use-of a-relatively small firebox.

oil to be burned must guard against the following source of grave difliculty. Overheating the petroleum oils beyond a certain temperature will cause a troublesome amount of cracking", i. e. of separation into simpler compounds of the same hydrocarbon series. Such separation is always accompanied by the liberation of carbon. This is deposited as soot, which tends to clog the burners, and makes necessary automatic apparatus or personal attention for cleaning the jets.

The cracking of crude petroleum, or of oils derived from petroleum, is dependent upon the temperature, the pressure, and the length of time the oil is subjected to the particular temperature and pressure.

It is the object of my invention to avoid this difliculty with vapor type burners, and to this end I ensure that the oil shall not be subjected to a temperature suflicient, at the'given pressure, to crack the oil within the time in which it is so subjected. This .I, accomplish by a device which makes use of the following principles:

The boiling point of mercury, as likewise that of various other easily available substances, at or near atmospheric pressure, is below the temperature at which petroleum oils will crack, given even the maximum pressure on the oil and the length of time of heating the oil at that pressure, which may be expected in a vaporizing apparatus such as that with which I am dealing.

I purpose to make use 01 this property of mercury in order to resolve oilsinto vapor-for delivery to burners of the vapor type without appreciable cracking, by interposing, as a heat barrier, between the oil and the sourceof heat, mercury in a closed system; so proportloning the dimensions of the apparatus that the temperaturedrop necessary to transfer the'heat from the mercury to the .oil at the rate desired will not allow the oil to reach the cracking temperature for the particular pressure to which the oil is being subjected. v

In the consideration of this problem, it should be borne in mind that two totally distinct pres sures are to be considered; namely, that to which the mercury is subjected and which thereby afiects the boiling point of the mercury, and that to which the oil is subjected and which thereby afiects the vaporizing point and the cracking point of the oil.

If there should occur any sudden, or even progressive, formation of mercury vapor in the mercury chamber, in suflicient quantity materially to raise thepressure in that chamber, the boilcontains only gases, by a jacket in which water is circulated for the purpose of condensing the By providing this condenser mercury vapor. chamber with an inlet pipe and an outlet pipe at different levels, circulation results; and thus the surplus heat is carried off by mere convection,

without the use of any pumping device. I also contemplate that, if the vaporizer is toibe' used in conjunction with a steam plant, the ,heat thus. carried away by the water may be conserved by directly-connecting said inlet and outlet pipes to the boiler; since the boiling point of mercury, at and near-atmospheric pressure, is considerably above the boiling point of water at anyordinarily practical pressure.

The relation between the area of the mercurycondensing surface and that of the mercury-heating surface is made such that, with the given cooling water temperature, the condenser will have ample capacity to condense the mercury vapor as fast as it can be formed, even if the main burner is shut off, and practically all the heat of the vaporizer burner is being used in vaporizing the mercury.

It is an additional object of my invention to provide for the possibility of greatly varying use .of power, without the necessity for any device to govern my vaporizer. The oil chamber being directly and freely connected to an oil reservoir in which pre'ssureis maintained approximately constant by' anair cushion, any diminution of :the amount of oil vapor being consumed at the boiler will result in an increase of vapor, and therefore of pressure in the oilchamber of the vaporizer. .This increase of pressure will force down the level'of the oil, driving some of the oil .back to the reservoir, thus decreasing the quantity of oil being subjected to vaporization. Correcspondingl'y, an increase of consumption of the boiler will lower'the pressure, and allow the oil to rise in its chamber, thus increasing the surface at whichoil isb'ein'g' subjectedto vaporizing temperature. Thus the amount of liquid-heating surface, andrhence the rate of vaporization, is automatically regulated to suit the demand.

, The supply ofoil in'the pressure-reservoir can be maintained-by a pump, drawing from an oil supply. The pump will serve as a one-way valve preventing the backing-up of the oil. Excess pressure in the reservoir can be relieved by safety valve in a by-pass around the pump. I

' Itis also obvious that my invention is 'so responsive to changes in the demands upon it, that any given apparatus embodying my invention will have avery wide scope; so that the same apparatus can be applied to plants designed for fairly widely varying purposes.

' -The accompanying drawings'iillustrate a preferred embodiment of my invention, whereby I attain the advantages hereinbefore set forth.

Figure 1 shows, in vertical cross section, the vaporizer containing "rny heat barrier.

Figure 2 shows a horizontal cross section through the vaporizer, taken in the plane indicated in Figure 1 by the 'line- 2-'-2.

or reservoir l0.

Figure 3 shows merely schematically the vaporizer, boiler, reservoir, etc., and the connections between them.

Throughout, the same reference numbers indicate the same or similar members.

Referring to Figure 3, it is seen that H] represents an oil reservoir, from which a pipe I I conveys theoil to a pump I2. The pump forces the oil through a pipe |3 to the pressure chamber I4. The chamber I4 is only partially filled with oil,

the remainder containing air, which therefore "acts as an air-cushion, tending to even off any rapid fluctuations in the pressuresuch, for instance, as are caused by the strokes of the pump.

A pipe I 5 communicates at one of its ends with pipe I3, its other end opening freely into the tank This pipe I5 has a safety valve 16, which relieves any excessive pressure in the air chamber I4 by allowing some of the oil to flow back into the reservoir ID. The safety valve .|6 may be set to blow off at any one of a fairly large range of pressures by the well-known device of a screw take-up acting against a compression spring.

From the base of the pressure chamber H a pipe ll feeds the oil into the vaporizer I8. The construction ofthe vaporizer is completely shown in Figures 1 and 2. It may be said to consist of a set of three more or less concentric cylindrical tubes, which form several chambers within the vaporizer.

The innermost cylindrical space is, the fire chamber or flue "I 9, in which oil vapor is burned, after being mixed with air at the burner 20, the amount of air entrained being subject to regulation in the same manner as in the ordinary Bunsen burner. The wall of this fire chamber 19 is the cylindrical metal tube 2| which extends the whole length of -the vaporizer and is open at both ends. The tube 2| may, if desired, be provided with fins, integral with 2| and projecting into the flue |9,'as shown at 22, Figure 2, but omitted from Figure 1 for the sake of clearness. These fins may be of any desired size and shape, and serve the purpose of increasing the proportion of the heat of the flame taken up by the tube 2|.

' Surrounding the tube 2| is achamber 23, which is to be'filied with mercury for a portion of .its

height as will be later pointed out. This chaml ber extends the entire length of thevaporizer, being closed at the bottom by the bottom plate 24.

The outer wall 25 of the mercury chamber 23 has attached thereto on one side of said chamber and extending for a portion of its length, a tube 26, which is open at the top and is closed at the bottom by the bottom plate 24. Just above the bottom plate 24 a hole 2'! through the wall connects the tube 26 with the mercury chamber'23.

Just above the level to which the chamber 23 is to be filled with mercury, the wall 25 is pierced by a number of holes 28, and the wall 25 does not extend upwardly quite to the head 29. There is thus free communication between the mercury chamber 23 and a condensation chamber 36 which immediately surrounds the upper part of the mercury chamber. The cond'ensa'tion chamber 30 is closed at the bottom by a partition 3|.

cylindrical wall 32, joined at the'bottom to'the partition 3|, and at the top to the head 29. The chambers 23 and 30, and the tube 25 thus communicate freely with one another, though they are closed-off air-tight by walls "2|,25'and32. and the head 29. and bottom plate 24. Access to this space is obtained through a hole 33 in the head 29, the hole being closed by a screw plug 34, or by a section of pipe containing a valve. By means of such a pipe and valve; it is possible, if desired, to adjust the pressure inthe mercury chamber before beginning operations, above or below atmospheric pressure, thereby varying the boiling point of the mercury. Such a variation, by producing a higher or lower heat gradient or maximum temperature, in the mercury barrier, would increase or decrease the rate of vaporization. 3 v

The condensation chamber is surrounded by a water jacket 35, which is'closed in by the head 29, the outer wall 36, and thefpartition 3|. A pipe 31. at the topand a second pipe 33 at the bottom of the water jacket provide circulation of. water, the other ends of these pipes being connected to the boiler or other reservoir of water.

Below the partition 3| and surrounding the lower, or mercury containing, portion of the mercurychamber 23 and the tube 25,. is the oil chamber 39. Into the bottom of this chamber the oil supply pipe before mentioned opens, and from the top the pipe 40 delivers the vapor by branches to the burner 20 at the vaporizer and to the burner 4| at the boiler 42, there being valves 43, 44, one in each branch.

The method of using the apparatus is as follows:

Plug 34 is removed for the introduction of the mercury, the level of which should stand a little below the partition 3|. Plug 34 is then reinserted. i V

The pump I2, actuated by any convenient means, forces a supply of oil from the tank l0 into the'pressure chamber l4 and thus intothe oil chamber 39. For starting from a cold vaporizer, "any convenient method may be used For instance, the burner 20 may be temporarily removed from its position" and a blow-torch used, the flame being directed up the fire chamber l9. When the mercury and oil have been heated to produce suflicient pressure of vapor in the top of'the oil chamber, the blow torch is removed and burner 20' restored to its position; valve 4313 opened and the vapor at burner 2|) is ignited; and thereafter by proper regulation of the valve 43 and of the action of the pump l2, this portion of the apparatus-will take care of itself with a minimum of attention.

Valve 44 is then opened and the vapor at bumer 4| ignited. Any one of a number of well-known devices may be utilized to govern valve 44 according to the amount of steam being used. j

When very little vapor is bei'ng'burned, it will accumulate in the oil chamber 39, thusforcing down the oil level by driving the oil back into the pressure chamber l4, and therefore a less oil surface will be exposed to the heat -ofthe mercury. In order that this action may be pronounced, Iprefer that the space containing the oil (e. 'g'. oil chamber'39) have a vaporizing wall of extended vertical dimension, as illustrated in 'the preferred form of device shown in the drawings. If the period when little oil is used is sufficiently prolonged, the mercury chamber 23 will'boiL'will condense in chamber 39, and flow backthroug'h the tube 26 to the bottom of the mercury chamber, the heat of vaporization of the mercury being thus transferred to the water in the: water. jacket and the boiler.

-' When the. burner 4| is again turned full on, more vaporbeing burned, the level of the oil in chamber 39 will rise, and a greater surface of oil will be exposed to the heat of the mercury, and the vaporization will be accelerated.

Theentire vaporizer I8 is covered with lagging (not showmg' to prevent loss of heat to the surrounding air.'-

As an adequate water circulation may easily be maintained in the water jacket. 35, it is obvious that the oil will be vaporized without being appreciably cracked. WhileI have herein discussed the use of mercury as a heat barrier, it is to be understood that my devicemight'make use, instead of mercury, of any one of a number of other substances. The only necessary condition is that the substance used shall have a boiling point below the danger point of the oil to be vaporized. For instance, sulphur, which under ordinary pressures melts. at I29 degrees centigrade and boils at about 445 degrees centigrade, might be used. It is obvious that I have provided an oil vaporizer in which. there is no possibility of troublesome cracking; economical-and efllcient, and one whichfurthermore will require only a minimum of attention.

Having now particularly described and illustrated one form of my invention, I wish it to be understood that I have not thereby limited myself to that particular embodiment, but have reserved to 'myself the right to make modifications and changes within the scope of the appended claims.

= I claim:

1. In an oil-vapor-burning steam boiler, the combination of: the boiler proper, means for burning the oil vapor to' heat the water in the boiler, a chamber for the oil which is to be vaporized, abarrier chamber in heat-exchangeable relation with the oil chamber, means for heating this barrier chamber, a liquid within the barrier chamber, the boiling point of the liquid being such that the liquid at the pressure to which it is subiected, would be vaporized at a temperature below the cracking point of the oil for the pressure to which the oil is subjected, means for carrying the oil vapor from the oil chamber to the means for burning, means for carrying away the vapor of the barrier liquid from the barrier chamber, thereby preventing the temperature of the contents of the barrier chamber from exceeding the boiling point of the barrier liquidf and a. condenser for the vapor of the barrier liquid, said condenser having a water'jacket in series with the boiler, to impart to the water in 'the boiler the heat liberated by the condensation, whereby all the heat imparted to the barrier liquid is conserved and utilized.

2. In an oil-vapor-burning steam boiler, the combination of: the boiler proper, means for burning the oil vapor to heat the water in the boiler, a chamber for the oil which is to be vaporized, an inlet pipe to admit oil to the lower part of this chamber, an outlet pipe to con duct oil vapor from the upper part of this chamber to the means for burning the vapor, a barrier chamber, in heat-exchangeable relation with one that is relatively simple,

the oil chamber, means for'heating*this"ban'ier chamber, a liquid within the barrier chamber, the boiling point of the liquid being such that the liquid, at the pressure .to 'whichzit is subjected, would be vaporized at a temperature be low the cracking: point of the :oil for thecpressure to which the -oil is subjected, means for carrying the'oil vapor from the oil (chamber to the means forburnin'g, means for carrying away the vapor of the barrierliquid from the barrier chamber, thereby preventing the temperature of the contents of the barrier chamber :from exceeding the boiling point of the barrierliquid, a condenser forthe vapor of thebarrier liquid, 2, Water jacket for cooling the condenser, said jacket being in circuit with the water chamber of the steam boiler, and a return pipe for returning the condensed vapor to the lower: part of the barrier chambeiz.

- 3. In a liquid fuel vaporizer-adapted to supply fuel in. vapor form to a burner=,-the combination of means providi-nga chamber for the liquid fuel to be vaporized, a liquid fuel, inlet line to said chamber, an outlet line for delivering vapor fuel from said chamber tothe burner, a' source of vaporizing heat,.means providing a barrier chamber arranged in heat exchange relation with and between the heat source and the liquid fuel chamber, and, contained in said barrier chamber and carrying vaporizing heat from the heat source to the liquid fuel in'the first'chamben'a vaporizable substance which, at it's working pressure, vaporizes at a temperature below the cracking temperature of the liquid fuel as determined by the, ,pressure to which the fuel is subjected and the length of time it is heated at that pressure, and a condenser arranged in closed circuit with the barrier chamber and ,capableof condensing the vapor formed upon vaporization of the substance.

4. In a liquid fuel vaporizer adapted: to supply fuel in vapor form to a burner, the combination of means providing a chamber for the liquid fuel to be vaporized, a liquid fuel inlet line to said chamber, an outlet line-for delivering vapor fuel from said chamber to the burner, a source of vaporizing heat, means providing a barrier chamber arranged in heat exchange relation with and between the heat source and the liquid fuel chamber, and, contained in said barrier cham her and carrying vaporizing heat from the heat source to the liquid fuel in the first chamber, a vaporizable substance which, at its working pressure, vaporizes at a temperature below the cracking temperature of the liquid fuel as de termined by. the pressure to which the fuel is, subjected and the length of time it is heated at that pressure, the partsbeing so constructed and arranged as to maintain a desired temperature differential between thesubstance and the liquid fuel in the first chamber, and acondenser arranged in closed circuit with the barrier chamher and capable of condensing the vapor formed upon vaporization of the substance.

5. In a liquid fuel vaporizer adapted to supply fuel in'vapor form to a burner, the combination of means providing a chamber for the liquid fuel to be vaporized, a source of vaporizing heat, means providing a barrier chamberarrangedin heat exchange relation with and between the heat source and the liquid fuel chamber, and, contained in said barrier chamber and carrying vaporizing heat from the heatsource to. the liquid fuel in the first chamber; avaporizable substance which, at its working pressure, va-

mrizes at. a temperature below the cracking temperature of'theliquid fuel'as determined by the pressure to which the fuel is subjected and the length of time it is heated at that pressure, a llq'uidfuel inlet line to theflrst chamber, an outlet line for delivering fuel vapor f'rom the firstchamber tothe burner at :a rate determined by the ,burner demand, means regulating automatically the raterof vaporization of the liquid fuel in accordance the aforesaid rate of delivery of: fuelyapor, and a condenser arranged in closed circuit with said barrier chamber and capablezof; condensing the-vaporformed upon vaporizationof the substance.

:-6..';In' a liquid fuel-vaporizer adapted to supply fuel in vapor form to a burnenthe combination of means providing ':a. chamber for the .liquid fuel to be vaporized, a source of vaporizing heat, means providing a barrier chamber arranged in heatv exchange? relation with .and between the heat source and the'liquid fuel chamber, and, contained in said barrier chamber-and carrying vaporizing heat from the heatsource to the liquid fuel in the first chamber, a vaporizable substance which, .atits-working pressure, vaporizes at a temperature below the cracking temperature of the liquid fuel as determined by the pressure to which the fuel is subjected and the length of time it is heated at that pressure, the parts being so constructed and arranged as to maintain a .desiredtemperature differential between the substance: and the liquid fuel in the first chamber, a liquid fuel inlet line to-the first chamber, an outlet line for delivering fuel vapor from the first chamber to the burner at a rate; determined by the burner demand, means regulating automatically the rate of vaporization of the liquid fuel in accordance with the aforesaid rate of delivery of the fuel vapor, and a'cQndenser arranged in closed circuit with said barrier chamber and capable of condensing the vapor formed upon vaporization of the substance. Y

j 7, In a liquid fuel vaporizer adapted to supply fuel in vapor formto a burner, the combination of means providing a chamber for'the liquidfuel the liquid-fuelas determined by the pressure to which the fuel is subjected and the length of time it isheated at that pressure, a-liquid'fuel inlet line to the first chamber, an outlet line for delivering vapor fuel from the firstc'hamber to the burner, means regulating the quantity of fuel maintained in said chamber for vaporization therein in accordance with the aforesaid rate of delivery-of the fuel vapor, and .a. condenser arranged in; closed circuit with said barrier chamher and capable of condensing the vapor formed upon vaporization of the substance. Y

8. In a liquid fuel vaporizer adapted to supply fuel in vaporform to a burner,- the combination of means providing a chamber for theliquid fuel tohbe vaporized, a source. of vaporizing heat, means providing a barrier chamber arranged in heat-exchange relation with and between the heat source and the. liquid fuel chamber, and, contained inlsa'id barrier chamber and carrying vaporizing heat from the heat source to the liquid fuel in the first chamber, a vaporizable substance which, at its working pressure, vaporizes at a temperature below the cracking temperature of the liquid fuel as determined by the pressure to which the fuel is subjected and the length of time it is heated at that pressure, the parts being so constructed and arranged as to maintain a desired temperature differential between the substance and the liquid fuel in said chamber, a liquid fuel inlet line to the first chamber, an outlet line for delivering vapor fuel from the first chamber to the burner, means regulating the quantity of fuel maintained in said chamber for vaporization therein in accordance with the aforesaid rate of delivery of the fuel vapor, and a condenser arranged in closed circuit with said barrier chamber and capable of condensing the vapor formed upon vaporization of the substance.

9. In a liquid fuel vaporizer adapted tosupply fuel in vapor form to a burner, the combination of means providing a chamber for the liquid fuel to be vaporized, a source of vaporizing heat, means providing a barrier chamber arranged in heat exchange relation with and between the heat source and the liquid fuel chamber, and, contained in said barrier chamber and carrying vaporizing heat from the heat source to the liquid fuel in the first chamber, a. vaporizable substance which, at its working pressure, vaporizes at a temperature below the cracking temperature of the liquid fuel as determined by the pressure to which the fuel is subjected and the length of time it is heated at that pressure, a liquid fuel reservoir in which liquid fuel is maintained under substantially constant pressure, a liquid fuel line between the reservoir and the first chamber, an outlet line for delivering vapor fuel from said chamber to the burner at a rate determined by the burner demand, means including said first chamber, reservoir and liquid fuel line for regulating the quantity of liquid fuel maintained in the first chamber for vaporization therein in accordance with the aforesaid rate of delivery of the fuel vapor, and a condenser arranged in closed circuit with said barrier chamber and capable of condensing the vapor formed upon vaporization of the substance.

10. In a liquid fuel vaporizer adapted to supply fuel in vapor form to a burner, the combination of means providing a chamber for the liquid fuel to be vaporized, a source of vaporizing heat, means providing a barrier chamber arranged in heat exchange relation with and between the heat source and the liquid fuel chamber, and, con tained in said barrier chamber and carrying vaporizing heat from the heat source to the liquid fuel in the first chamber, a vaporizable substance which, at its working pressure, vaporizes at a temperature below the cracking temperature of the liquid fuel as determined by the pressure to which the fuel is subjected and the length of time it is heated at that pressure, the parts being so constructed and arranged as to maintain a desired temperature differential between the substance and the liquid fuel in said chamber, a liquid fuel reservoir in which liquid fuel is maintained under substantially constant pressure, a liquid fuel line between the reservoir and the first, chamber, an outlet line for delivering vapor fuel from said chamber to the burner at a rate determined by the burner demand, means including said first chamber, reservoir and liquid fuel line for regulating the quantity of liquid fuel maintained in the first chamber for vaporization therein in accordance with the aforesaid rate of delivery of the fuel vapor, and a condenser arranged in closed circuit with said barrier chamber and capable of condensing the vapor formed upon vaporization of the substance.

SAMUEL L. G. KNOX.

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