US1971073A - Apparatus for distilling hydrocarbons - Google Patents

Description

Aug. 2l, 1934. w. o. KEELING APPARATUS FOR DISTILLING HYDROCARBONS Filed July 21. 1950 2 Sheets-Sheet l Q3 mv@ AN. mo

INVENTOR.

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Y nD Aug. 2l, 1934. w, o. KEELING APPARATUS FOR DISTILLING HYDROCARBONS Filed July 2l. 1930 2 Sheets-Sheet 2 Patented Aug. 21, 1934 PATENT OFFICE APPARATUS FOR DISTILLIN G CARBONS unmo- William 0. Keeling, Kansas City, Mo.

Application July 21, 1930, Serial No. 469,963v

4 Claims.

Thisinvention relates to an apparatus for distillation of hydrocarbons as in the manufacture of lubricating oils and similar products, being a continuation. in part of my application on Surface type combustion' burner, led June 7,

1929, Serial No. 369,174, and has for its principal objects to effect maximum thermal efliciency of the fuel consumed in raising the hydrocarbonsto distillation temperatures, and to accurately control the temperatures to produce hydrocarbon fractions of highest quality. A

In accomplishing these and other objects of my invention, I effect substantially perfect combustion of a fluid fuel to provide an inert heating medium, reduce its initial temperature and increase its volume-by mixing therewith cool inert gases, and then disperse the mixture in direct heating contact with the hydrocarbons to distill certain fractions thereof lsuch as the various grades of lubricating oils. A

In carrying out my invention I have provided an apparatus illustrated in the accompanying drawings, wherein:

Fig. 1 is a diagrammatic view of the distlling r apparatus, parts of which are in section to better illustrate the process by which the hydrocarbons are treated.

Fig. 2 is a vertical sectional view through the automatic regulator for controlling flow of combustion-supporting air to the inspirator.

Fig. 3 is a vertical sectional view through the regulator for controlling flow of gas to the inspirator. Y

Fig. 4 is a vertical sectional view through the valve controlling air inlet to the compressor.

Fig. 5 is a sectional view through the valve for controlling admission of gas to the suction side of the gas compressor.

Fig. 6 is a sectional view through the inspirator.

Referring more in detail to the drawings:

1 designates a gas furnace having a combustion chamber 2, and a burner chamber 3 containing a surface type combustion burner 4 for burning an air and gas mixture discharged into the burner from a fuel manifold pipe 5; the mixture of ail'. and gas being proportioned, as later described, lso, as to provide substantially complete combustion, thereby providing an inert heating medium free of carbon monoxide and uncombined oxygen for discharge into a conduit 7 communicating the furnace with the lower end of a fractionating tower designated 8 for treating hydrocarbons as later described.

A heat exchanger 9 is preferably inserted in the conduit for initially heating the charging stock by indirect contact to a temperature sumciently high to enable the hot gases, when they are directly contacted with the hydrocarbons in the tower, to assist in their vaporization mainly by their partial pressure effect. By thus initially heating the hydrocarbons I am enabled to materially reduce the amount of gas required to vaporize the desired hydrocarbon fractions.

The heat exchanger 9 may be of anyordinary construction but preferably comprises an insulated housing having headers 10 and 11 spaced from the ends thereof and connected by a plurality. of tubes 12 through which the charging stock is delivered and around which the hot combustion gases are circulated to interchange heat therewith and properly condition temperature of the gases for treatingA the hydrocarbons after they are discharged from the heat exchanger into the fractionator. 5

`The charging stock, such as petroleum hydrocarbon, from which the lower boiling point hydrocarbons have been removed, is delivered through a pipe 13 into the manifold section 14 of the heat exchanger formed between the end wall l5 and the header 10, and is discharged through the tubes of the'heater into the manifold 16 formed by the header 11 and the opposite end wall 17 of the heat exchanger from whence the hydrocarbon is discharged through a pipe 18 into the fractionating tower.

The fractionating tower' .may be of any ordinary construction but is here illustrated as comprising a vertically positioned cylindrical housing 19 having a group of spaced trays'or 90 partitions 20 extending horizontally across the tower above the gas inlet from the conduit 7. The trays are preferably provided with flanged openings covered by bubble caps 21 similar to an ordinary fractionating column to form baflies for the gas as it travels toward the top of the tower.

lThe initially heated charging stock is delivered into the fractionating tower at a point above the bottom of the tower and above the group of stripping trays 20, so that the charging stock may gravitate downwardly therethrough in counter flow to the hot gases which are being discharged upwardly through the trays.; The liquid hydrocarbons are thus widely dispersed by the trays and caused to come into direct cons tact with a large quantity of the gas heating medium, thu's quickly and enlciently vaporizing the liquid and supplying such heat as is necessary to make up for heat lost by vaporization,

and to maintain temperatures at which the desired cuts are to be made.

In order to control the temperatures in the heat exchanger and fractionating tower to obtain the fractions desired, I provide for tempering the combustion gases from the furnace with cool inert gases so that the required temperature may be carried in the exchanger and tower by simply varying the ratio of hot and cold gases admitted as now described.

22 designates a supply line for delivering cool inert gas to the furnace and 1s provided with a diaphragm actuated valve 23 therein for controlling iiow of gas through a nozzle 24 discharging tangentially into the combustion chamber at a point above the burner so that admission of cool gas will be above the combustion point of the fuel gases and not interfere with complete combustion thereof. The cold gases coming in tangential contact with the hot gases produces violent agitation and assures a complete homogenous gas mixture of uniform density and temperature for delivery through the conduit 7.

The valve 23 is controlled by a pyrometer 25 located in the conduit 7 and connected with the actuating mechanism of the valve to control the amount of cool gases admitted to the furnace and maintain a set temperature of the resultant gas mixture.

The vaporized hydrocarbons, together with the hot inert gases, travel upwardly in the fractionating tower through spaced partitions 26 providing stages from which the desired hydrocarbons are removed.

I' The partitions 26 have central openings 27 to permit passage of the gases from one stage to the next, and located intermediate the partitions are bubble trays between and in which certain of the vapors are condensed by reux liquids flowing downwardly in the tower to be trapped on the partitions 26. The openings 27 in the plates are provided with upwardly extending anges 28 for preventing the condensed vapors from escaping downwardly therethrough and to form a trap to prevent the inert gases from being discharged through pipes 29 connecting the respective stages with suitable coolers 30; liquid of condensation being preferably maintained at a level to seal the outlet lines 29 and thereby prevent escape of gases along with the condensed vapors. As the vapors condensed in the tower are of high boiling point liquids, temperatures will be maintained sufliciently high to prevent condensation of water vapors in the gases, and such vapors are carried over from the tower with the inert gases. While any number of stages may be employed in the tower, the tower here illustrated is provided with three stages whereby heavy, medium and light oils may be obtained.

The uncondensed vapors and the hot inert gases, after passing through the tower, are discharged through a port 31 into a reflux condenser 32 for condensing lighter fractions of the vapors for reflux through the fractionating tower. The reux condenser is illustrated as comprising a cylindrical housing having headers 33-34 spaced from the end walls thereof and connected by a plurality of tubes 35 around which the uncondensed vapors and gases may flow to be cooled by a cooling medium circulated through the tubes. In order to conserve heat of, the vapors I pre fer to utilize the charging stock as a cooling medium for the reux-condenser, and I therefore connect the charging line in series with the reflux condenser.

The uncondensed vapors and inert gases are discharged from the reflux condenser into a pipe 36 communicating with a final Ycondenser designated 37 where the vaporized hydrocarbons are finally condensed and the inert gases cooled before discharging into an oil and gas separator 38.

The oil and gas separator may be of standard construction and is adapted to separate the inert gases from the condensed hydrocarbons, the inert gases being discharged from the separator through a pipe 39 communicating with the suction side of a compressor 40, and the liquid hydrocarbons are discharged through a pipe 4l into a suitable receiver not shown. The compressor 40 compresses and discharges the inert gases under pressure into a gas reservoir designated .42 for storage and discharge into line 22 to be employed in tempering the hot combustion gases in the furnace as previously described.

In order to insure maximum vaporization of the hydrocarbons in the fractionating tower, the reflux liquid collected in the bottom of the tower may'be recirculated through a pipe 43 communieating the bottom of the tower with the inlet of va circulating pump 44 which discharges into the charging stock inlet pipe 18 previously described, so that the unvaporized liquid may be recycled and gravitated through the hot gases, to reclaim remaining fractions which will vaporize at the temperature carried in the tower.

It may also be desirable to by-pass portions of the reflux from the upper stages to the succeeding lower stages in order to have sufficient reflux for condensing all of the hydrocarbon vapors which it is desired to recover in the respective stages, and I therefore provide by-passes 45 communicating the upper side of each partition 26 with the bubble cap trays below the partitions, and control flow through the by-passes by valves 46.

While the distilling process thus far described is a complete process it may be desirable to provide additional stages since additional fractions may be desired from the unvaporized hydrocarbons'collected in the bottom of the fractionating tower, and I therefore may provide a second stage comprising a second fractionating tower through which the unvaporized hydrocarbons may be circulated to be reheated and vaporized,

'to permit recovery of additional fractions or fractions. of dierent values.

The second tower, designated 47, is also provided with a furnace 48 complementary to the furnace previously described and which is provided with a burner 49 connected with the fuel supply line 5 for providing an inert heating medium to treat the hydrocarbons discharged into the second tower 47. The furnace 48 is provided with a gasoutlet 50 communicating with a heat exchanger 51 complementary to the heat exchanger 9 previously described, for reducing temperature of the inert gases and for additionally heating the liquid discharged from the first fractionating tower through a pipe 52 connecting the bottom of the tower with the heat exchanger and through a pipe 53 connecting the heat exchanger with the second fractionator tower 47, the pipe 53 discharging into the fractionating towers similarly to the delivery pipe 18 for the first tower.

The second fractionating tower is provided with bubble trays and a plurality of stages from which certain cuts maybe obtained similiarly to the stages previously described in the flrst fractionating tower, and is also provided witha reflux condenser 54 complementary to the' reflux condenser 32 previously described, and the vapor outlet of the reflux condenser is connected by a connection 55 with the vapor conduit 36. the connection 55 being controlled by a valve 56.

The charging stock is also utilized for cooling the second reflux condenser which may or may not be in series with the reflux condenser in the first stage, and the flow therethrough is controlled by a valve 57 in the charging line 13 ahead of the condenser 54.

The charging line 13 is provided with a line 58 by-passing the second reflux condenser, and which is controlled by a valve 59 so that` in case the second fractionator tower is not connected into the system the valve 57 may be closed and the valve 59 opened to permit flow of charging stock directly through the first reflux condenser 32.

The pressures in the'system may be regulated by a relief valve 60 located in the top of the separator 38 to allow release of gas when thepressure exceeds the amount set by the valve and purge the system of excess gas. The cold gas receiver is also provided with a relief valve 61 to prevent excessive pressure in the receiver.

It is of importance for efficient and safe operation of the system that the air and gas ratio be accurately maintained at all times to provide perfect combustion of fuel and maintain a fixed composition of the products of combustion which is suitable for direct contact with the hydrocarbons being reduced, that is, the gases must be free of carbon monoxide and uncombined oxygen. It is also necessary that the desired ratio be maintained regardless of varying back pressures acting against the burner incidental to combustion of the gases themselves, of changes in temperature in the furnace in the system, of changes in the internal working temperatures in the reduction part of the system, of variable pressure of the cooling gases, and of delivery pressures of the air and gas being consumed.

I have, therefore, provided means for controlling delivery pressures of the air and gas in direct proportion to the resultant pressure of all the combined variable factors so that the fuel mixture is constant regardless of the widely varying pressures in the system.

From actual experiment it has been determined that the resultant furnace pressure against which the burner can operate is from atmosphere to one hundred fty pounds, and, therefore, the air and fuel mixture must be delivered to the furnace at proportional pressures.

62l designates a gas line for supplying a fuel gas to the intake of a gas compressor 63 for compressing gas into a storage tank 64, the storage tank being communicated with the compressor by a pipe 65.

Positioned in the gas line is an automatically operated control valve for cutting off supply of gas -when the tank has reached a certain pressure and for opening the supply when the tank pressure has dropped below the said amount, or when the furnace pressure exceeds the tank pressure. The valve includes a housing 66 having dual valve seats 67 and 68 for seating double balanced valves 69 and 70 which are connected by a valve stem 71 extending upwardly in the casing and connected with a. plurality of diaphragms 72, 73 and 74 having differential di- .of gas to the compressor.

ameters and mounted-,in diaphragm chambers 75, 76 and 77, respectively.

The valves seat downwardly on their seats and the furnace pressure acts Aon the under side of the larger diaphragm through a pipe 78 coml' municating the furnace conduit 7 with the lower half of the diaphragm chamber 76, and tends to open the valves, the gas tank pressure acting on the upper side of the diaphragm through a pipe 79 communicating the tank with the upper half of the diaphragm chamber to close the valves. Pressure in the gas line also tends to open the valves as it acts on the under side of the diaphragm 72 through a port 80, through which the valve stem extends into the diaphragm chambers and the top side of the diaphragm 7 2 is open to furnace pressure through ports 8l communicating the chambers and 76, tending to close the valves against the line pressure.

The top side of the upper diaphragm 74 isopen to atmosphere andI the lower side of the diaphragm is open to tank pressure through ports 82 communicating the chambers 76 and 77 to balance the diaphragm 72. When there lis no pressure acting on the diaphragms other than the line pressure or when the pressures are equal, the valves are normally opened bythe line pressure to permit passage It is thus apparent that any increase in furnace pressure tends to keep the valves open to let more gas into the compressor and build up the tank pressure to a ypoint-where the tank pressure equals or exceeds the furnace pressure.

The air inlet is controlled by a similar valve 83 except that the valve is mounted with the diaphragm below the valve body so that weight of the parts will act to normally retain the valve in open position. The valve 83 includes a valve housing having spaced valve seats 84 and 85. 115 and associated therewith are valves 86 and 87 for controlling passage of air from the inlet connection 88 to the outlet pipe 89 communicatingwith an air storage tank 90. The valves 86 and 87 are connected by a valve stem 91 con- 12 necting a plurality of diaphragms 92, 93 and 94 mounted in diaphragm housings 95, 96 and 97, respectively.

T'he top side of the larger diaphragm 93 is actedl upon by air pressure in the air outlet line 98 later described, to open the valves while the under side of the diaphragm is subjected -to pressure contained in the air storage tank through a pipe 99 communicating the air tank with the diaphragm housing 96. The under side of the small diaphragm 94 is open to atmosphere and the top side of the diaphragm is open to the air tank pressure.

The upper side of the other diaphragm 92 is also open to atmosphere and its under side is open to the air line pressure through ports 101 communicating the valve chambers and 96.

Thus it is apparent that when the air tank pressure becomes greater than the pressure in the air line 98, the valves will close and prevent further compression in the air tank y90, and when the air tank pressure drops below the pressure in the line 98 the valves will open.

The outlet'lines from the gas and air tanks are controlled by differential regulators 103 and 104, respectively.` The gas differential regulator valve comprises a valve housing 105 having an inlet port 4106 connecting with the pipe 102 and an outlet port 107 connected by a pipe 108 communicating lwith an inspirator 109y later described.

Received in the valve casing are seats 110 and 111 having valves 112 and 113 adapted for ccntrolling flow from the inlet port 106 to the outlet port 107, the valves\ being connected by a stem 114 extending through the housing into a diaphragm chamber 115, and fixed to the stem is a diaphragm 116, thel upper side of which is subjected to the furnace pressure through a pipe 117 connected with the pipe 78, and the under side of the valve is open to.pressure in the line 108 through ports 118 communicating the lower half of the valve chamber with the interior of the valvehousing on the outlet side of the valve. f

Thus the furnace pressure acting on the top side of the diaphragm tends to open the valve, and the line pressure acting on the under side of the diaphragm tends to close the valve. As the valve opens downwardly the increase in furnace pressure causes the valve to open and allow more gas to fiow to the inspirator, causing the gas line pressure to build up until it is equal to the furnace pressure but the valves remain open due to weight of the parts continuing feed of gas to the inspirator until the furnace pressure exceeds gas pressure in the line, when the valves will close.

'I'he air outlet differential regulator valve is somewhat similar to the gas regulator and comprises a housing 119 having an inlet port 120 connected with the air tank by, a pipe 121 and an outlet port 122 communicating by a pipe 123 with the line 98 and with the inspirator.

The valve housing is provided with valve seats 124 and-125 for seating valves 126 and 127 controlling air passage through the ports. 'Ihe valves are. connected by a stem 128 projecting through the housing into a diaphragm chamber 129 containing a diaphragm 130 connected with the valve stem which continues through thediaphragm chamber and into a cylindrical housing 131Asupported by the upper side of the diaphragm housing, to carry weights 132 to normally retain the valves in open position and permitpassage of air from the tank 90 through the line 123 to supply air to the inspirator.

The upper side of the diaphragm 130 is open to furnace pressure through a pipe 133 connecting the upper half of the diaphragm chamber with the line 78, and the lower side of the diaphragm is open to air pressure in the line 123 through ports 134 communicating the interior of .the valve housing with the under side of the diaphragm so that when the pressures are balanced the weights retain the valves open.

The inspirator 109 automatically proportions the ratio of the air and gas mixture and may be of any standard construction, but is here illustrated as having a venturi 135 through which the combustion supporting .air is passed for syphoning the gas through an orifice 136 1ocated at a point above the venturi and in communication with the gas pressure line 108. At

this point the static pressure of the air stream is changed into velocity pressure so that the gas is drawn into the air stream and an air and gas mixture issues therefrom and flows into the manifold pipe 5.

Since, due to the regulators, the fuels are delivered to the inspirator at constant pressures-proportionate to the pressures in the furnace, increase in furnace pressure will cause a similar increase in the fuel pressures, maintaining the ratio constant at all times.

Thus increase in furnace pressure will retain all the regulator valves open but decrease' in furnace pressure will cause all of them to throttle and even the pressures.

It is, therefore, apparent that balanced pressure conditions may be lobtained between the furnace pressure and supply lines and that since pressure ratios are maintained between 4the gas and air lines and as both'are controlled by the furnace pressure, any increase in the quantity of air to the inspirator will cause like increase in the quantity of gas drawn into the inspirator, thereby maintaining the air and gas ratio constant.

The pressure in the second furnace may be controlled according to pressure in the first furnace so that pressure therein is proportionate to pressure of the fuel delivered to the burner 49. 'Ihe conduit 50 is provided with a regulating wire 137 actuated by a diaphragm 138 in a diaphragm housing 139 and the upper side of the diaphragm is acted upon by pressure in the first furnace admitted through a pipe 140 to close the valve to build up pressure in the second furnace equal to pressure in the first. When the pressure in the second furnace slightly preponderates over that in the first furnace the increased pressure will act through a pipe 141 on the under side of the diaphragm to open the valves.

In operating the first unit of the system constructed as described, the valves 56, 57, a valve 142 in line 52, and a valve 143 in the line 5 are closed, and the valve 59 and a drain valve 144 communicating with the line 52 are opened to allow the charging stock to flow through the by-pass into the first refiux condenser, and into and through the first heat exchanger to be discharged into the fractionating tower. The burner in the first furnace will be started to combust the air and gas mixture supplied from the air and gas storage tanks to provide a heating medium for vaporizing the charging stock admitted to the fractionating tower.

The temperature of the heating medium will be suitably reduced by cool gas which is admitted to the furnace through the nozzle 24 under control of the automatically controlled valve 23 to reduce the temperature of the gases to approximately 1000 F. before they are discharged into the heat exchanger to exchange heat with the charging stock.

The gases are discharged from the heat ex- 130 changer at a temperature below cracking temperature of the charging stock, and travel upwardly through the bubble trays in the fractionating tower.

The cool gas not only reduces the temperature 135 of the combustion gases but also increases the available quantity of hot gases which are circulated in contact with the hydrocarbons to be vaporized so that the hydrocarbons being dispersed over the bubble trays are thoroughly 140 Vaporized by the hot gases travelling upwardly in the fractionator tower through the respective stages from which certain cuts are to be obtained. The portions of the hydrocarbons condensing are collected by the plates 26 and are 145 removed from the system through the pipes 29.

Some of the vapors which are uncondensed in the fractionator tower are condensed in the refiux condenser to form a refiux for circulation through the fractionator tower. Vapors un- 150 condensed in the reflux condenser are discharged through the line 36 and condensed in the nal condenser 37 and discharged into the oil and gas separator 38 where the inert gases are separated from the condensed oil and pumped into the cool gas reservoir 42 ready for recycling through the furnace.

In case the second stage is required, as when making more than three cuts from the charging stock, the valve 59 in the by-pass line 58 and the valve 144 in the line 52 will be closed and the valves 57, 56, 142, and 143 will be opened. The second furnace will then be placed in operation and the oil collecting in the bottom of the rst fractionator tower will be pumped through the second heat exchanger into the second fractonator tower where additional cuts are made by an operation similar to that in the first fractionating tower.

What I claim and desire to secure by Letters Patent is:

1. In apparatus of the character described, a furnace including a burner, means for supplying an air and gas mixture to the burner includ- 3' ng means for supplying the air and gas mixture at pressures directly proportional to the pressures in the furnace, a fractionator for treating hydrocarbons, means for delivering hydrocarbons to the fractionator, means for discharging products of combustion from the furnace into the fractionator to directly heat hydrocarbons delivered thereto for vaporizing portions thereof, and means for condensing and collecting portions of the vapors.

2. In apparatus of the character described, a furnace, means for supplying an air and gas mixture to the furnace, means for combusting the air and gas mixture to provide an inert heating medium, means for discharging the heating medium from the furnace into indirect contact with hydrocarbons to be reduced, a fractionator tower, means for delivering the hydrocarbons to the fractionator tower, means for delivering the heating medium into the fractionator tower for direct contact with the hydrocarbons to vaporize portions of the hydrocarbons, and means for controlling the pressure of the air and gas mixture proportional to pressures within the fractionator tower.

3. In apparatus of the character described, a fractionator tower, means for delivering hydrocarbons to the fractionating tower, means for burning an air and gas mixture to provide an inert heating medium, means for supplying the air and gas to the burning means proportionate to pressure in the fractionating tower, means for delivering the heating medium into the fractionator tower for direct contact with the hydrocarbons to vaporize portions thereof, and means for condensing and collecting portions of the vapors.

4. In apparatus of the character described, a furnace including a burner, means for supplying an air and gas mixture to the burner including means for supplying the air and gas mixture at pressures directly proportional to the pressures in the furnace, a fractionator tower for treating hydrocarbons, means for discharging products of combustion from the furnace into the fractionator tower to directly heat hydrocarbons delivered thereto for vaporizing portions thereof, a second fractionating tower for treating liquid discharged from the first tower, and means for controlling pressure in the second tower proportional to pressure in the first tower.

WILLIAM O. KEELING.

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