US3850743A

US3850743A - Catalytic hydrodesulfurization process

Info

Publication number: US3850743A
Application number: US00340492A
Authority: US
Inventors: A Peiser; M Antal; G Weiss
Original assignee: Mobil Oil Corp
Current assignee: ExxonMobil Oil Corp
Priority date: 1973-03-12
Filing date: 1973-03-12
Publication date: 1974-11-26
Anticipated expiration: 1991-11-26

Abstract

A catalytic hydrodesulfurization process is described with particular concern for the distribution of various process streams in a manner to improve upon heat recovery thereby providing a substantially higher temperature reactor effluent recovery operation promoting reductions in investment and operating costs.

Description

United States Patent [191 [1111 3,850,743 Peiser et al. 1 Nov. 26, 1974 [54] CATALYTIC HYDRODESULFURIZATION 3,356.608 12/1967 Franklin 208/212 3,382,168 5/1968 Wood et a1. 208/212 PROCESS 3,723,301 3/1973 Rice 208/143 [75] Inventors: Alfred M. Peiser, Rocky Hill;

Michael J. Antal, Trenton, both of N.J.; Gustave J. Weiss, New York, Primary Examiner-C. Davis N.Y. Attorney, Agent, or FirmAndrew L. Gaboriault; Car] [73] Assignee: Mobil Oil Corporation, New York, Famsworth [22] Filed: Mar. 12, 1973 [57] ABSTRACT [21] Appl. No.: 340,492

A catalytic hydrodesulfurization process is described [52] Cl 208/209, 208/212, 208/213 with particular concern for the distribution of various 208/254 H process streams in a manner to improve upon heat re- 51 rm. CI. Cl0g 23/00 Covery thereby Providing a Substantially higher [58] Field of Search 208/209 212 213, 143, perature reactor effluent recovery operation promot- 208/254 H, 255 ing reductions in investment and operating costs.

[56] References Cited 9 Claims, 3 Drawing Figures UNITED STATES PATENTS 3,340,182 9/1967 Berkman et al. 208/212 rel-1 g /2 36 Ll E E 5 52 A D 2 56 E 8 5a /6 y 34 1:3 I j); 54 (1 o 3 "P" LLiJ F 2 66 CATALYTIC HYDRODESULFURIZATION PROCESS BACKGROUND OF THE INVENTION It has long been known that petroleum stocks and other carbonaceous material can be upgraded by hydrogenation. Hydrogenation reactions progress relatively easily in the presence of suitable catalysts and include the removal of foreign elements such as sulfur, nitrogen, oxygen and halogen material from the hydrocarbon material. Since sulfur is present in one form or another in almost all crude oils and straight run fractions thereof, the removal of sulfur therefrom has been a necessary petroleum refinery operation and this sulfur removal has become even more important with the demand for improving our surrounding atmosphere. In desulfurization processes it is preferred to maintain a relatively high ratio of hydrogen to sulfur containing hydrocarbon charge since a high hydrogen partial pressure in the reaction zone has a favorable influence on the efficiency of the desulfurization reaction, the life of the catalyst and the amount of carbonaceous deposits produced and deposited on the catalyst in the reaction zone.

SUMMARY OF THE INVENTION The present invention is concerned with the desulfurization of hydrocarbon feed materials in the vapor, liqaid, or mixed vapor/liquid phase condition and the recovery of products thereof in an integrated refinery operation promoting a reduction in investment and particularly operating costs. More particularly the present invention is directed to an improved arrangement of processing steps for the recovery of valuable liquid products from a product effluent stream containing vapor-liquid components including non-condensable gaseous material. The product effluent of a desulfurizing reaction being at an elevated temperature and pressure is thereafter passed through a sequence of heat exchange steps tailored to effect an efficient partial cooling thereof before separation by flashing in a high temperature flash zone maintained at a temperature approaching the bottom operating temperature of the product fractionating zone and relying upon the hot flash vaporous material to effect indirect heat of hydrogen rich recycle gas introduced to the process in conjunction with providing a portion of the fractionating tower reflux liquid requirements in one or more upper portions thereof.

In practicing the processing concepts in this invention the hydrocarbon reactant material passed with hydrogen rich gas in contact with the desulfurizing catalyst may be in either a liquid, vapor or mixed liquid/vapor phase condition under the reaction conditions employed. In this operation the temperature of the hydrogenating reaction conditions may be selected from within the upper range of conditions of about 350F. up to about l,250F. at a pressure selected from-about 1 atmosphere up to about 2,000 psig or higher. A weight hourly space velocity in the range of 0.01 to about 25 measured as pounds of hydrocarbon charge per pound of catalyst per hour in the reactor may also be employed. More specifically. the desulfurizing of hydrocarbons by hydrogenation in the presence ofa hydroge nating catalyst may employ temperatures selected from within the range of 550F. to about l,000F. but more preferably the temperature is selected from within the range of 600F. to about 800F. A preferred pressure may be selected from within the range of 300 to 1,000 psig and a weight hourly space velocity selected from within the range of 0.5 to about 10 may be employed.

Catalytic materials which may be successfully employed in the desulfurization of hydrocarbon materials are many at this stage of the art. More usually these catalysts are known to have significant hydrogenation activity which promote the conversion of sulfur to form hydrogen sulfide which is thereafter removed separately from the desulfurized product of the process. Catalysts suitable for the purpose include, for example, siliceous catalyst including silica-alumina, platinumalumina type catalyst, chromia type catalyst, molybdenum-trioxide, nickel-molybdate supported on alumina, nickel-tungstate on alumina, cobalt-molybdate on alumina and nickel-cobalt-molybdate catalysts. Other catalysts which may be used for the purpose of this invention include platinum and/or palladium supported on alumina type catalyst, a Group VI metal compound including, for example, the oxide and/or sulfide of the left hand elements thereof, specifically chromia and/or molybdenum trioxide supported on alumina; the Group Vl metal compound can be promoted with a compound ofa metal of Group VIII such as, for example, the oxides and/or sulfides of iron, cobalt or nickel. Other suitable classes of catalysts are those which have molybdenum, chromium, vanadium and/or tungsten as an outer acid-forming element in combination with phosphorous, silicon, germanium and platinum as the central acid-forming element.

Hydrocarbon materials which may be successfully.

desulfurized in the process of the present invention include those referred to as straight run hydrocarbons or hydrocarbon materials of cracking operations including kerosene, gas oil, cycle stocks from catalytic cracking or thermal cracking operations, residual oils, thermal and coker distillates. It is known that the sulfur concentration of these hydrocarbon stocks may vary from about 0.03 to about 10 weight percent or higher. It is also contemplated desulfurizing hydrocarbon stocks having an API gravity in the range of from about 20 to about 58 API having a heavier concentration in the range of from about 0.25 to about 6.0 percent by weight. The initial boiling point of the hydrocarbon feed passed to the desulfurizing process of this invention may vary from 300F. up to about 450F. and the end boiling point may vary from about 450F. up to about 750F. and as high as 1,050F. at atmospheric pressure conditions.

One of the primary contributions of the processing sequence of the present invention resides in the arrangement of the desulfurizing reactor effluent heat exchange system to provide a more efficient utilization of available heat contributing to a significant savings in utility expenses without increasing the use of expensive special alloy equipment. More usually the present invention effects a reduction in the need for special alloy equipment and/or the size thereof. In the processing arrangement of the present invention the furnace duty for the product fractionating zone and feed furnace pre heat is kept to a desired low minimum by a judicious selection of heat exchange arrangements and product separations which will optimize use of heat available in the product effluent stream.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a diagrammatic illustration of one embodiment of the desulfurizing process of this invention which permits a significant reduction in utility and investment costs.

FIG. 2 is a diagrammatic illustration of a second embodiment of the present invention particularly concerned with handling vaporous components of the reactor effluent separated and recovered from the high chamber flash drum identified in FIG. 1.

FIG. 3 is a diagrammatic illustration of a third embodiment of the present invention concerned with a sequence of processing steps for handling the vaporous component removed from the high temperature flash drum of FIG. 1.

DISCUSSION OF SPECIFIC EMBODIMENTS A principal feature of the new and improved ap' proach to catalytic hydrodesulfurization (CHD) process design is concerned with a redistribution of the flow of material streams and heat exchange thereof in such a way that one can reap a substantial reduction in investment and operating costs. Referring now to FIG. 1 by way of example, a hydrocarbon charge boiling in the range of about 350F. to about 850F. and introduced by conduit 2 is preheated by indirect heat exchange with desulfurized product passed through heat exchanger E-l to raise the temperature of the feed up to about 560F. Thereafter the preheated feed is further indirectly heated by indirect heat exchange with reactor effluent in exchanger E-2 downstream of conduit 4 to further raise the temperature of the hydrocarbon charge up to about 672F. The hydrocarbon charge is then brought up to about 725F. in furnace F-l, supplied by conduit 6 to achieve a required desulfurization reactor inlet temperature of about 690F. The charge heated in furnace F-l is then passed by conduit 8 and conduit 10 to the desulfurizing reactor housing a suitable desulfurizing catalyst. Catalysts suitable for this purpose are discussed in another portion of the application.

Hydrogen rich gas introduced to the process by conduit I2 is heated to an elevated temperature in the sequence of indirect heat exchange steps. That is, the hydrogen rich gas in conduit 12 is first indirectly heated in exchanger E-4 against hot vapors separated from drum D-I and supplied thereto by conduit 24. The hydrogen rich gas heated in heat exchanger E4 to a temperature of about 536F. is then passed by conduit 14 to heat exchanger E-3 in the reactor effluent stream supplied by conduit 18 wherein the hydrogen rich gas is further indirectly heated to a temperature of about 702F. The reactor effluent in conduit 18 passed to heat exchanger E-3 is about 7l0F. The thus preheated hydrogen is withdrawn and passed by conduit 16 to join with hydrocarbon feed in conduit 8 and form a reactor feed passed to the reactor by conduit 10. Conversion ofsulfur in the hydrocarbon charge to hydrogen sulfide with or without the conversion of nitrogen takes place within the desulfurizing reactor and produces a reactor effluent of elevated temperature removed by conduit 18. The effluent withdrawn by conduit 18 is then cooled in sequence of heat exchangers E3 and E-2 to a temperature of about 702F. in E-2 before passage thereof by conduit 20 to indirect heat exchanger B2. In heat exchanger E-2 the reactor effluent is further cooled to a temperature of 620F. by indirect heat exchange with hydrocarbon charge material as discussed above. The effluent cooled to a temperature of about 620F. is then passed by conduit 22 to a high temperature flash drum D-l. In high temperature drum D-l, product vapors are separated and removed from the upper portion thereof by conduit 24 with the liquid portion of the effluent being removed from the drum by conduit 26. The high temperature vapor stream is then passed by conduit 24 to exchanger E-4 wherein it is cooled to a temperature of about 536F. by indirect heat exchange with hydrogen rich recycle gas introduced to the process by conduit 12.

A first step in the evolution of the new processing concepts of this invention is concerned with a realization that the heat duty Q of the reboiler furnace F-2 connected to tower 28 is directly affected by the temperature of the hydrocarbon stream such as, for example, that in conduit 26 at its point of entry to the tower. If the temperature T-9 is increased, heat duty Q is decreased. Therefore, in the interest of reducing fuel consumption and cost it is clear that the temperature T-9 of a hydrocarbon stream introduced to the tower should be as high as is reasonably possible within the constraints of the process operation, However, the limiting factor in increasing temperature T-9 in many prior art processes has been the temperature of the tower bottoms T-l0 withdrawn as by conduit 30 and with which it has previously been passed in indirect heat exchange therewith. Thus, as T9 approaches T10, the size and costs of the exchanger increased sharply and fuel savings were not significantly realized. Thus, once the heat exchanger is removed the temperature of drum D-l can be retained as high as is feasible in order to reduce the heat duty ()2 of the reboiler F-2. In view of the above, it immediately became evident that it would be desirable to eliminate the prior art heat exchange (Tm-T and the hot liquid stream 26 should go directly to the tower from drum D1. A tower bottom temperature of about 650F. has been found to be most satisfactory. Thus the closer the temperature of drum D-l can be operated to this temperature the more is the heat duty of boiler F-2 reduced.

The elimination of heat exchange step T, T above discussed and the subsequent increase in the temperature of drum D-l produces a second benefit considered to be equally as important as the reduction on the heat duty of furnace F-2. For example, the temperature T-I of the hydrocarbon charge in conduit 6 entering preheat furnace F-l is limited by the direct effluent temperature T4 in conduit 20 and thus the size of heat exchanger E-2. This is considered to be a particularly serious limitation because of the relatively higher costs of the special alloys and high construction costs required. However, an increase in the temperature of drum D-l is achieved by lowering the heat exchange duty of heat exchanger E-2. This increase is a trend in the right direction. This means that for the same heat exchanger size and cost a closer heat exchange approach temperature can be achieved. The process heat exchanger E-Z must necessarily be constructed of special alloys and at high construction costs. Therefore any efforts to increase the temperature of the charge T-l in conduit 6 in order to reduce the heat duty of preheat furnace F-l such as by increasing the size of heat exchanger E-2 is not looked upon favorably. In the concept of this invention, however, the hydrocarbon feed temperature E-l in conduit 6 can be brought closer in temperature to the temperature of the reactor effluent T-4 in conduit 20 and the heat duty Q, of furnace F-l is correspondingly reduced without any increase in cost of the special alloy heat exchanger E-2. Of course depending upon the relative values of fuel and investment costs the heat duty of furnace F-l can alternatively be maintained at substantially the same level in order to obtain a significant reduction in the size and cost of heat exchanger E-2.

In order to increase the temperature T-l of the feed in conduit 6 in the process arrangement of FIG. 1, it is necessary to increase the temperature of the feed in conduit 4 passed to heat exchange E-2 and thus the temperature of the hydrocarbon charge leaving heat exchanger E-l. Two factors make it economically attractive to do this. First, with the removal of the heat exchanger T T above discussed, the tower bottoms in conduit 30 is immediately available for use at its highest temperature in heat exchanger E-I thus providing the greatest possible driving force in this heat exchange step. Second, heat exchanger E-l can be constructed largely of less expensive carbon steel at a much lower construction cost than that available in heat exchanger E-2 above discussed. Furthermore, the incremental investment cost for increasing the size of heat exchanger E-l as compared to heat exchanger E-2 permits a much greater fuel saving in furnace F-l for the same investment cost. Thus it can be seen from the above that the process design and operating parameters of this invention are arranged to optimize a temperature of effluent components passed in indirect heat exchange with another process component to optimize temperature level of hydrocarbon effluent material passed to the stripping tower associated therewith.

The vaporous material withdrawn from high temperature drum D-1 and used in heat exchanger E4 to preheat hydrogen rich recycle gas is withdrawn from exchanger E-4 at a temperature of about 536F. and passed by conduit 32 to a cooler E-S within the temperature ofthe various material is reduced to about 115F. The thus cooled material is then passed by conduit 34 to a separator drum D-2 wherein a separation is made between non-condensable gaseous material and liquid material. The gasiform material or non-condensable gases comprise low boiling hydrocarbons, hydrogen sulfide ammonia and hydrogen is withdrawn by conduit 36. These gases may be treated to separate a hydrogen rich gaseous stream from hydrogen sulfide and other undesired components before recycle of the hydrogen rich gases to the reactor. On the other hand. the gases withdrawn by conduit 36 with or without further treatment may be used in other refinery processes.

On the other hand. the vaporous material withdrawn from E-4 by conduit 32 may pass through an additional heat exchanger not shown to generate refinery process steam and cool the effluent to a temperature in the range of 360F. to about 400F. The thus cooled mate rial is then passed to exchanger E-5 wherein its temperature is reduced to about 1 F. before passage to drum D2. 7

A relatively light liquid stream comprising products is withdrawn from drum D2 and conveyed by conduit 38 to fractionating tower 28 for discharge to an upper portion thereof substantially as a reflux fluid. A study of the performance characteristics of the fractionating tower shows that for maximum distillation efficiency,

the relatively light liquid stream in conduit 38 should be introduced to the tower at a much higher point than the higher boiling liquid stream separated and withdrawn from high temperature drum D-l by conduit 26. Thus liquid streams in conduit 38 and conduit 26 are introduced to temperature zones of the fractionating zone more compatible for efficiency utilization and separation in the fractionating zone. Thus the temperature of the liquid stream in conduit 26 approaches a bottom lower temperature of about 650F. maintained in tower 28. It is to be noted that with the increase in separating temperature for flash drum D-l there is necessarily an excess of liquid subsequently condensed above that required for use as reflux in the fractionating tower 28. Thus the excess or remainder of condensable liquid separated from the overhead vapor stream of D-l is reheated by indirect heat conditions and introduced to the tower at a lower point than reflux liquid and in a temperature region of the tower most suitable for the introduction of this component stream. Thus the excess liquid at a relatively high temperature of about 444F. is introduced intermediate to the point of introduction of reflux fluid and the higher boiling liquid component of the process introduced by conduit 26. To accomplish the heating of the excess compatible liquid above identified there are at least two alternate ways in which heat may be added to this excess liquid portion and FIGS. 2 and 3 are particularly directed to this portion of alternate embodiments.

In the arrangement of FIG. 2 which is specific to the vaporous stream withdrawn from 0-1 of FIG. 1, the vaporous material separated from heat exchanger E-4 is passed by conduit 32 to heat exchanger E-6 wherein the excess condensed liquid in conduit 38 is passed by conduit 40 so as to raise the temperature thereof up to about 444F. and eventual passage by conduit 42 to the fractionating tower beneath the point of reflux introduced by conduit 38. The partially cooled vaporous material removed from heat exchanger E-6 by conduit 44 is further cooled in cooler E-S to a temperature of about 1 15F. as discussed with respect to FIG. 1 before passage thereof to drum D-2. In drum D-2 separation of noncondensable gases from condensable material is accomplished as discussed hereinbefore. In the second alternate operating embodiment represented by FIG. 3 and pertaining to the vaporous stream withdrawn from drum D-l of FIG. 1 the need to reheat the excess condensed liquid is avoided by providing an additional flash drum D-4 between heat exchangers E-5 and B6. In this arrangement excess reflux liquid is obtained by partially cooling of the vaporous stream of exchanger E-6 which material is then passed by conduit 46 to flash drum B4. In this arrangement the vaporous material is cooled by exchanger B6 to a lower temperature so that in drum D-4, a separation is made between condensable and non-condensable material with the liquid condensate recovered at a temperature of about 444F. and passed by conduit 48 to the fractionating tower for introduction in a temperature zone compatible for handling the temperature of the thus introduced stream. The vaporous or non-condensable portion removed from flash drum D-4 is passed by conduit 50 to a cooler E-S and thence by conduit 52 after cooling to a temperature of about I 15F. to flash drum D-2. In flash drum D-2 a separation is made between non-condensable and condensable materials as discussed hereinbefore with respect to FIG. 1. In the arrangement of FIG. 3 it is contemplated using exchanger E-6 to generate low pressure refinery steam thereby further contributing to the economies of the operation. Referring now to FIG. 1 and particularly fractionating tower 28 shown therein, it will be observed that a vaporous stream is withdrawn from the top of the tower by conduit 56 for passage to cooler E-S and thence to a separator drum D-3 wherein a separation is made between gaseous components and condensable liquid material. Generally drum D-3 will be maintained at a temperature of about 1I5F. Any non-condensed gasiform material is withdrawn from drum D-3 by conduit 58. Condensable liquid is withdrawn from D-3 by conduit 60 with a portion thereof recycled to the tower as reflux by conduit 62 and the remaining portion withdrawn by conduit 64. In an operation involving the desulfurization of gas oil boiling range materials conversion thereof to lower boiling range components will be realized during the desulfurizing operation. In such an operation, gasoline product of conversion will normally be recovered by conduit 64. The bottom portion of tower 28 is provided with a reboiler furnace F-2 to which liquid withdrawn from the tower is passed by conduit 66 and then returned to the tower by conduit 68. As provided herein and shown in attached table I the heat duty of furnace F-2 is considerably reduced commensurate with the objectives of the process conversion above described. Furthermore, the heat duty of furnace F-l is also reduced commensurate with the objectives of the process above discussed.

Table I FUEL REQUIREMENT (ALL FIGURES ARE BASED UPON A CHARGE RATE OF I000 Having thus provided a general discussion of the improved method and sequence of processing steps of this invention and provided a discussion of specific embodiments going to the very essence thereof, it is to be understood that no undue restrictions are to be imposed by reasons thereof except as defined in the following claims.

We claim:

1. In a process for desulfurizing hydrocarbons and separating the product effluent thereof into noncondensable hydrogen containing gas, hydrocarbon conversion products boiling below the hydrocarbon charge and a high boiling desulfurized product a method for improving the operating efficiency of the process which comprises passing the effluent of the desulfurization reaction sequentially through a plurality of indirect heat exchange zones, the first heat exchange zone being relied upon to provide heat to a hydrogen rich recycle gas stream and the second heat exchange zone being relied upon to provide heat to the hydrocarbon charge to be desulfurized, said sequence ofindirect heat exchange zones being heated duty sized to reduce the temperature of the desulfurization effluent only sufficient to recover a liquid product stream thereof at an elevated temperature substantially supporting the temperature maintained in the bottom portion of a downstream product fractionating zone, recovering a high temperature vaporous material stream from the liquid product thus obtained, using the high temperature vaporous material to indirectly preheat hydrogen rich gas introduced to the process, further coding the vaporous material to a temperature permitting the separation of non-condensable hydrogen containing gaseous components from condensable liquid material, passing condensable liquid material to an upper portion of said fractionating zone as reflux material and passing the liquid product stream of elevated temperature separated from said high temperature vaporous material to a lower portion of said fractionating zone.

2. The process of claim 1 wherein a high temperature desulfurized bottom product is recovered from the fractionating zone and passed in indirect heat exchange with the hydrocarbon charge to the process.

3. The process of claim 1 wherein a portion of the condensable liquid material in excess of that needed as reflux in the fractionating zone is indirectly reheated with the vaporous material following said heat exchange with hydrogen rich gas introduced to the process and passing the thus reheated condensable liquid portion to said fractionating zone beneath said introduction of said reflux level.

4. The process of claim I wherein hot vaporous material recovered from heat exchange with hydrogen rich recycle gas introduced to the process is partially cooled to recover condensate from vaporous material, the condensate is passed to the fractionating zone beneath the level of reflux added thereto and the vaporous material is then further cooled to form a condensate material suitable for use as reflux fluid in an upper portion of the fractionating zone.

5. The process of claim 2 wherein the hydrocarbon charge to the desulfurizing process is indirectly heated by the fractionating zone bottoms before indirect heat exchange with the desulfurizing zone effluent.

6. In a process for desulfurizing hydrocarbons and recovering desulfurized products the improvement which comprises withdrawing an effluent from a desulfurization zone at an elevated desulfurizing temperature, partially cooling said effluent in a sequence of heat exchange zones to a temperature providing a high temperature vaporous stream and a high temperature liquid stream thereof at a temperature substantially supporting the bottom temperature ofa downstream product fractionating zone, passing the high temperature liquid portion directly to a lower portion of said fractionating zone, partially cooling said vaporous stream by indirectly heating hydrogen rich gas introduced to the process, further cooling said partially cooled vaporous stream to obtain liquid condensate separated from a gasiform fraction comprising hydrogen, passing liquid condensate to an upper portion of said fractionating tower as reflux, and passing another portion of liquid condensate to a lower zone of said fractionating zone than said reflux inlet zone.

7. The process of claim 6 wherein high temperature process streams are used to indirectly preheat the incoming hydrocarbon feed stream and hydrogen rich gases introduced to the process.

8. The process of claim 6 wherein a desulfurized bottoms fraction is withdrawn from the fractionating zone and is used to preheat the hydrocarbon charge prior to stream is then passed through one of said sequence heat exchange zones to further heat the hydrogen rich gas thereafter introduced to the desulfurizing zone.

Claims

1. IN A PROCESS FOR DESULFURIZING HYDROCARBONS AND SEPARATING THE PRODUCT EFFLUENT THEREOF INTO NON-CONDENSABLE HYDROGEN CONTAINING GAS, HYDROCARBON CONVERSION PRODUCTS BOILING BELOW THE HYDROCARBON CHARGE AND A HIGH BOILING DESULFURIZED PRODUCT A METHOD FOR IMPROVING THE OPERATING EFFICIENCY OF THE PROCESS WHICH COMPRISES PASSING THE EFFLUENT OF THE DESULFURIZATION REACTION SEQUENTIALLY THROUGH A PLURALITY OF INDIRECT HEAT EXCHANGE ZONES, THE FIRST HEAT EXCHANGE ZONE BEING RELIED UPON TO PROVIDE HEAT TO A HYDROGEN RICH RECYCLE GAS STREAM AND THE SECOND HEAT EXCHANGE ZONE BEING RELIED UPON TO PROVIDE HEAT THE HYDROCARBON CHARGE TO BE DESULFURIZED, SAID SEQUENCE OF INDIRECT HEAT EXCHANGE ZONES BEING HEATED DUTY SIZED TO REDUCE THE TEMPERATURE OF THE DESULFURIZATION EFFLUENT ONLY SUFFICIENT TO RECOVER A LIQUID PRODUCT STREAM THEREOF AT AN ELEVATED TEMPERATURE SUBSTANTIALLY SUPPORTING THE TEMPERATURE MAINTAINED IN THE BOTTOM PORTION OF A DOWNSTREAM PRODUCT FRACTIONATING ZONE, RECOVERING A HIGH TEMPERATURE VAPOROUS MATERIAL STREAM FROM THE LIQUID PRODUCT THUS OBTAINED, USING THE HIGH TEMPERATURE VAPOROUS MATERIAL TO INDIRECTLY PREHEAT HYDROEN RICH GAS INTRODUCED TO THE PROCESS, FURTHER CODING THE VAPOROUS MATERIAL TO A TEMPERATURE PERMITTING THE SEPARATION OF NON-CONDESABLE HYDROGEN CONTAINING GASEOUS COMPONENTS FROM CONDENSABLE LIQUID MATERIAL, PASSING CONDENSABLE LIQUID MATERIAL TO AN UPPER PORTION OF SAID FRACTIONATING ZONE AS REFLUX MATERIAL AND PASSING THE LIQUID PRODUCT STREAM OF ELEVATED TEMPERATURE SEPARATED FROM SAID HIG TEMPERATURE VAPOROUS MATERIAL TO A LOWER PORTION OF SAID FRACTIONATING ZONE.

4. The process of claim 1 wherein hot vaporous material recovered from heat exchange with hydrogen rich recycle gas introduced to the process is partially cooled to recover condensate from vaporous material, the condensate is passed to the fractionating zone beneath the level of reflux added thereto and the vaporous material is then further cooled to form a condensate material suitable for use as reflux fluid in an upper portion of the fractionating zone.

6. In a process for desulfurizing hydrocarbons and recovering desulfurized products the improvement which comprises withdrawing an effluent from a desulfurization zone at an elevated desulfurizing temperature, partially cooling said effluent in a sequence of heat exchange zones to a temperature providing a high temperature vaporous stream and a high temperature liquid stream thereof at a temperature substantially supporting the bottom temperature of a downstream product fractionating zone, passing the high temperature liquid portion directly to a lower portion of said fractionating zone, partially cooling said vaporous stream by indirectly heating hydrogen rich gas introduced to the pRocess, further cooling said partially cooled vaporous stream to obtain liquid condensate separated from a gasiform fraction comprising hydrogen, passing liquid condensate to an upper portion of said fractionating tower as reflux, and passing another portion of liquid condensate to a lower zone of said fractionating zone than said reflux inlet zone.

8. The process of claim 6 wherein a desulfurized bottoms fraction is withdrawn from the fractionating zone and is used to preheat the hydrocarbon charge prior to the hydrocarbon charge passing through one of said sequence of heat exchange zones.

9. The process of claim 6 wherein hydrogen rich gas indirectly heated by said high temperature vaporous stream is then passed through one of said sequence heat exchange zones to further heat the hydrogen rich gas thereafter introduced to the desulfurizing zone.