Title of Invention	PROCESS FOR REFINING CONDENSATE OF MINERAL ORIGIN IN EXISTING CRUDE OIL DISTILLATION UNIT
Abstract	This invention describes a new process for the refining of Condensate of mineral origin in Crude Oil Distillation Units, by drawing various fractions of naphtha as S5 from preflash distillation K1 and S6, S10 and S11 from the main crude distillation K2 and blending them into a single Naphtha product S14, as detailed in drawing.

Full Text

3. Process for refining Condensate of mineral origin in Crude Oil Distillation Unit This invention relates to a new manner of manufacturing process for refining Condensate of mineral origin into various fractions of differing boiling ranges at unit capacities ranging from 70% to 100% or more as compared to about 30% by conventional methods in Crude Oil Distillation Units. Condensate can be of two origins, viz., one associated with Natural Gas and the other associated with crude oil production. Unlike crude oil which contains very little of Naphtha, (of the order of less than 15%), condensate contains a large amount of low boiling hydrocarbons of the Naphtha range and very little of heavy residual oil. This makes it difficult to process condensate in crude oil distillation unit at reasonable" capacities by following the conventional methods. Growing discovery of Natural gas compared to crude oil, has made it almost compulsory for many refiners in some parts of the world, to process more and more condensates in their crude oil distillation units in stead of crude, but at a stiff penalty of lower throughputs. This patent describes a novel method for attaining higher capacities in crude distillation units while processing condensate. The novelty of our invention lies in separating the various fractions contained in condensate without involving any costly modifications or without significant reduction in the processing capacity of crude oil distillation unit. The process described here uses as feed any condensate, which contains a large quantity of naphtha (about 30% to 70%) boiling below 140 °C. Description of the related Prior Art: In the conventional prior art processing of condensate in a crude distillation unit to recover petroleum fractions either as components of finished petroleum products or as feed stock for secondary processing or quality upgradation processes, the condensate is first distilled or fractionated in an atmospheric crude distillation. In such an operation, while gases and naphtha are recovered as overhead products of the crude distillation, kerosene and light gas oils are drawn out as side cuts of the atmospheric distillation and the residual material is recovered from the bottom of the same as reduced crude. Each of these streams has distinct boiling point ranges, flash points and vapour pressures. The typical boiling ranges of the various streams are expressed as True Boiling Point (TBP) cut ranges of the crude/condensate feed as follows: ft will be clear to those skilled in the art of hydrocarbon processing, that if condensate is processed in crude distillation units by conventional methods, the unit capacity will be reduced by 30 to 50% of the normal capacity, as the Naphtha section (since Naphtha quantity in condensate is about three times as compared to that in a normal crude) of the distillation will get limited by flooding of the trays while the downstream piping/pumps will get hydraulically limited due to higher flow of Naphtha vapours and liquid respectively. In addition the downstream stabilizer section will be overloaded by about 300%, as the Naphtha quantity is that much more in case of condensate processing. Thus the prior art has a limitation in processing capacity of condensate in the crude distillation units. A detailed search was made of patents to find the improved processing techniques for crude oil and condensate distillation, which are described hereinafter. The distillation process described in US patent No.4082653 does not describe how to increase the refining rate of condensate but discusses only a more efficient form of heating of the feed so that the heat exchanger system becomes more efficient with less fouling. Similarly the US patent No.4239618 does not concern itself with processing capacity but only with providing twin tower distillation for lowering the requirements of both heat and steam required for fractionation. in the same way, the US patent No.4321132 also skips on the capacity increase but describes the utilization of a heat exchange scheme in which the heat for the main fractionator is provided by the vaporized stream as well as the liquid stream from the heater outlet without letting in the heater outlet directly into the fractionator. At the same time the feed stream cools main fractionator condenser. Similarly, the US patent No.4308130 also does not give any importance to the increasing of refining capacity but describes the column internal wash methods to improve the quality of products from distillation. Thus it was found that there is no process in published patents or literature to refine high naphtha content condensate in crude units while maintaining the processing capacity near to normal rates associated with crude oil. Setting up new distillation units for processing condensate is both capital intensive and leads to wastage of existing assets due to non-utilization. Summary of the invented process: In accordance with the present invention, there is provided a new manufacturing technique with a novel distillation scheme, to refine condensates in crude distillation units with good throughputs. In one embodiment of the invention, this is achieved by drawing out the ultra light naphtha fraction from the preflash distillation ahead of the main crude distillation followed by drawing the three more fractions of naphtha from the main crude distillation with completely different boiling ranges as top and side cuts as compared to a single top cut in conventional crude oil distillation. Thus the crude distillation column"s top Naphtha section is unloaded from the large amount of naphtha vapours that is the bane of conventional processing technique. This invention is illustrated in the accompanying drawing Fig.l, through out which like reference letters indicate the corresponding flow streams in the descriptions, below. This invented process is characterized in that (a) The condensate S1 after being preheated in Elis fed to the first distillation called preflash distillation K1. (b) 5-10% of condensate called ultra light naphtha S5 is drawn from the top of Kl by controlling Kl top temperature at 80-100° C and at a pressure of 1 - 3 kg/square cm gauge. (c) The balance portion of condensate is drawn from bottom of K1 as stream S4. (d) The stream S4 is heated in Fired Heater F1 to 200-300°" C before being fed to the main crude distillation K2. (e) 10-30% of condensate is drawn from the top of the main crude distillation K2 as light naphtha S6 by controlling Kl top temperature at 80- 120° C and at a pressure of 1-2 kg/square cm gauge. (f) 10-30% of condensate is drawn as the first side cut of the main crude distillation K2 as medium naphtha S10 by controlling the flow of first side cut at a temperature of at 110- 160° C and at a pressure of 1-2 kg/square cm gauge. (g) 10-30% of condensate is drawn as the second side cut of the main crude distillation K2 as heavy naphtha S11 by controlling the flow of second side cut at a temperature of at 135- 200° C and at a pressure of 1-2 kg/square cm gauge. (h) The lighter streams of Naphtha S5 from Kl and S6 from K2 are stabilized in stabilizer distillation K3 producing a stabilized naphtha stream S9 from the bottom. (i) The stabilized Naphtha stream S9, first side cut S10 and second side cut Sll are blended into a single Naphtha product S14. The product streams from the preflash distillation Kl are in the sequence as given in the following table, where the boiling ranges represent the corresponding True Boiling Point (TBP) cut ranges of the feed condensate: The product streams from the main crude distillation K2 are in the sequence as given in the following table, where the boiling ranges represent the corresponding True Boiling Point (TBP) cut ranges of the feed condensate: This process utilizes the technique of splitting full range Naphtha into more fractions to increase the distillation column capacity without exceeding any equipment limitations. It does not require any additional tray or any increase in column diameter, except for minor modifications for blending of the various cuts at the battery limit. Thus it involves minimum fixed cost. Brief Description of the Drawings: Fig. 1 comprises diagrammatic flow diagram according to the present invention. The preferred embodiment of the process of the invention is shown by way of example in Fig. 1. In this figure, pressure, flow and temperature control devices are not shown for the sake of greater clarity. The same symbols refer to the equipments and streams in the drawings as in the descriptions and examples. Fig. 1 shows the preferred embodiment of the invented process, in which there is a crude distillation K2 with a preflash distillation K1 and stabilization distillation K3 operating with condensate in the novel mode. The streams in Fig.1 are as follows: S1 : Condensate Feed S2 : Hot Condensate Feed to the preflash distillation K1 S3 : Off Gas from the preflash distillation K1 S4 : Bottom stream from the preflash distillation K1 S5 : Overhead liquid from the preflash distillation K1, called ultra light Naphtha S6 : Overhead liquid from the crude distillation K2, called light Naphtha S7 : Stabilization feed which is a blend of streams S5 and S6 S8 : Overhead liquid from the Stabilization distillation K3, called LPG S9 : Bottom liquid from the Stabilization distillation K3, called stabilized light naphtha S10: First side cut from the crude distillation K2, called medium Naphtha S11: Second side cut from the crude distillation K2, called heavy Naphtha S12: Third side cut from the crude distillation K2, called ATF S13: Bottom liquid from the crude distillation K2, called Gas oil or residue S14: Bulk Naphtha which is a blend of streams S9, S10 and S11 The pumps in Fig. 1 are as follows: P1 : Condensate Feed pump P2 : Preflash distillation K1 bottom pump P3 : Preflash distillation K1 top product pump P4 : Crude distillation K2 top product pump P5 : Crude distillation K2 first Side cut Medium Naphtha pump P6 : Crude distillation K2 second Side cut Heavy Naphtha pump P7 : Crude distillation K2 third Side cut ATF pump P8 : Crude distillation K2 bottom pump The heat exchangers in Fig.1 are as follows: El : Preheat exchangers before Preflash distillation K1 E2 : Preheat exchangers before Fired Heater F1 E3 : Preheat exchangers between condensate and Medium Naphtha S10 E4 : Preheat exchangers between condensate and Heavy Naphtha S11 E5 : Preheat exchangers between condensate and ATF S12 E6 : Preheat exchangers between condensate and Gas oil or residue S13 E7 : Preheat exchangers between stabilizer bottom S9 and stabilizer feed S7 E8 : Preheat exchangers between stabilizer bottom S9 and stabilizer feed S7 The vessels in Fig. 1 are as follows: D1: Overhead vessel of Preflash distillation K1 D2 : Overhead vessel of Crude distillation K2 D3 : Overhead vessel of Stabilization K3 The condensers in Fig.l are as follows: C1 : Overhead condensers of Preflash distillation K1 C2 : Overhead condensers of Crude distillation K2 C3 : Overhead condensers of Stabilization K3 The coolers in Fig.l are as follows: W1 : Cooler on stabilizer bottom stream S9 W2 : Cooler on Medium Naphtha stream S10 W3 : Cooler on Heavy Naphtha stream S11 W4: Cooler on ATF stream S12 W5 : Cooler on Gas oil or residue stream S13 The best method of carrying out the invented process is described below: Detailed Description of the preferred embodiment of the Invented Process with reference to the Flow Diagram shown in Fig.l: Pre flash distillation K-1 Section: The feed condensate, namely Stream S1, being pumped by pump P-1 after being heated in feed pre-heat exchanger train E-1, is fed to the feed tray and is distilled in Pre flash distillation, namely K-1, in the figure as partially vaporized stream S2, limited to the capacity of the flooding limit of the system. The top vapors which consist of the light gases and a very light naphtha, are condensed in overhead condenser C-1 and collected in reflux drum D-1 before being refluxed back, above top tray. The lighter vapours are routed out from the drum D-1 as stream S3 to either fuel gas or to the main distillation K- 2. The balance overhead product Stream S5, of boiling below 60 ° C of about 5-10% of the feed, is pumped by pump P-3 to the stabilizer distillation K-3 as feed. The heavier hydrocarbons cut is produced as a bottom stream, namely Stream S4 in figure and pumped by pump P-2. It is further heated in feed pre-heat exchanger train E-2, before entering the fired heater F-1. The feed is heated to about 250 ° C and all the lighter distillates except the diesel or residue boiling range are vaporized in the heater before entering the distillation K-2 on the feed tray. Atmospheric distillation K-2 Section: This section fractionates the vapor coming from the heater into various fractions narrow boiling ranges. The top vapors consisting of light naphtha of boiling range of about 60-90 ° C along with some gas from the distillation K-2 are condensed in overhead condenser C-2 and collected in reflux drum D-2 before being refluxed back, above the top tray. The lightest vapours are routed out from the drum D-2 to either fuel gas or to the flare header depending upon the pressure. It may also be processed in a gas concentration section to recover all the valuable hydrocarbons in liquid form. The balance overhead product, namely Stream S6 in figure, is pumped by pump P-4 to the stabilizer distillation K-3 as feed. The first side cut product, namely Stream S10 in figure, called Medium Naphtha of boiling range of about 90-110 ° C is drawn from the first side cut tray via a stripper K-4 and pumped by pump P-S to storage or other process units before being cooled in preheat exchanger E-3 and cooler W-2. The second side cut product, namely Stream S11 in figure, called Heavy Naphtha of boiling range of about 110-140 ° C is drawn from the second side cut tray via a stripper K-5 and pumped by pump P-6 to storage or other process units before being cooled in preheat exchanger E-4 and cooler W-3. The third side cut product, namely Stream S12 in figure, called Aviation Turbine fuel or kerosene of boiling range of about 140-240 ° C is drawn from the third side cut tray via a stripper K-6 and pumped by pump P-7 to storage or other process units before being cooled in preheat exchanger E-5 and cooler W-4. All the side strippers are steam stripped to remove the lighter products from the side cuts. The heavier hydrocarbons cut boiling above 240° C is produced as a bottom stream from K-6, namely Stream S13 in figure and pumped by pump P-8. It is further cooled in feed pre-heat exchanger E-6 and cooler W-5, before being routed to storage. The preheat exchanger trains E-1 and E-2 represent notionally the exchangers E-3,4,5,6 arranged in an optimal manner to achieve high thermal efficiency. Stabilizer distillation K-3 Section: The feed Stream S7 consisting a mixture of Stream S5 and Stream S6 from distillations K-1 and K-2 respectively, after being heated in feed pre-heat exchanger E-7, is fed to the feed tray of the stabilizer distillation and is distilled. The top vapors are condensed in overhead condenser C-3 and collected in reflux drum D-3 before being refluxed back, above the top tray. The lighter vapours are routed out from the drum D-3 to either fuel gas or to the gas concentration section. The balance overhead liquid product is to the storage section, namely Stream S8 in figure, as LPG, which are mainly C3 and C4 hydrocarbons. The heavier hydrocarbons cut called gasoline of boiling range of about 30- 90 ° C is produced as a bottom stream, namely Stream S9 in figure. It is further cooled in feed pre-heat exchanger E-8 and cooler W-1, before being routed to storage. At the battery limit of unit, the medium and Heavy Naphtha cut streams S10 and Sll either from the main crude distillation K2, and or from the side stripping K4, K5 and K6, and or stabilizer bottom stream S9 are blended together to produce either a single bulk naphtha product stream S14 or combined in various proportions and combinations to form multiple finished products or other intermediate streams as described below: The novelty of the process is that instead of separating the various side streams as per the conventional refinery distillation boiling range, they are fractionated as per the plant section capacities capability to handle the maximum throughput. This avoids the unnecessary under capacity utilization of various section of the fractionator equipment. General Description: All the various distillations described above can be carried out in typical industrial distillation columns having either conventional sieve trays or valve or bubble cap or any other specialized high efficiency tray, like MD tray, or different types of packed beds, without affecting the basic nature of the invention but with the aim of only increasing the distillation efficiency thus reducing overall cost of equipment for the required separation efficiency. Further these distillations may also be carried out in dividing wall columns or thermally coupled columns to increase the thermal efficiency. The tray locations may be at any location depending on the tray efficiency, feed composition and feed tray location at every stage of distillation, but still achieving the basic requirements of the invention with cost and thermal effectiveness. Example of the invented process: A typical case of the invented process with reference to the figure Fig. 1 is described below: Pre flash distillation K-1 Section: About 70000 kilograms per hour of condensate, namely Stream S1, being pumped by pump P-1 to about 13.0 kg/square cm, after being heated in feed pre-heat exchanger train E-1 to about 140 ° C, is fed to the feed tray and is distilled in Pre flash distillation, namely K-1, in the figure as partially vaporized stream S2. The top vapors are condensed in overhead condenser C-1 at about 40° C and at a pressure of 2.0 kg/square cm and collected in reflux drum D-1 before being refluxed back above top tray. About 10 kilograms per hour of the lighter vapours are routed out from the drum D-1 as stream S3 to either fuel gas or to the main distillation K-2. The balance overhead product Stream S5 of boiling range of about 30- 60 ° C of about 6000 kilograms per hour is pumped by pump P-3 to the stabilizer section as feed. About 64000 kilograms per hour of the heavier hydrocarbons cut is produced as a bottom stream, namely Stream S4 in figure and pumped by pump P-2. It is further heated in feed pre-heat exchanger train E-2 to about 150 ° C, before entering the fired heater F-1. The feed is heated to about 250 ° C and all the lighter distillates except the diesel or residue boiling range are vaporized in the heater before entering the distillation K-2 on feed tray. Atmospheric distillation K-2 Section: This section fractionates the vapor coming from the heater into various fractions narrow boiling ranges. The top vapors from the distillation K-2 are condensed in overhead condenser C-2 at about 50 ° C and at a pressure of 1.0 kg/square cm and collected in reflux drum D-2 before being refluxed back, above top tray. About 10 kilograms per hour of the lighter vapours are routed out from the drum D-2 to either fuel gas or to the flare header depending upon the pressure. It may also be processed in a gas concentration section to recover ail the valuable hydrocarbons in liquid form. The balance overhead product of about 8000 kilograms per hour of light naphtha, namely Stream S6 in figure of boiling range of about 60- 90 ° C, is pumped by pump P-4 to the stabilizer section as feed. The first side cut product about 14000 kilograms per hour, namely Stream S10 in figure, called Medium Naphtha of boiling range of about 90- 110 ° C is drawn from the first side cut tray via a stripper K-4 and pumped by pump P-5 to storage or other process units before being cooled in preheat exchanger E-3 and cooler W-2. The second side cut product of about 19000 kilograms per hour, namely Stream S11 in figure, called Heavy Naphtha of boiling range of about 110-140 ° C is drawn from the second side cut tray via a stripper K-5 and pumped by pump P-6 to storage or other process units before being cooled in preheat exchanger E-4 and cooler W-3. The third side cut product of about 9000 kilograms per hour, namely Stream S12 in figure, called Aviation Turbine fuel or kerosene of boiling range of about 140- 240 ° C is drawn from the third side cut tray via a stripper K-6 and pumped by pump P-7 to storage or other process units before being cooled in preheat exchanger E-5 and cooler W-4. A11 the side strippers are steam stripped to remove the lighter products from the side cuts. The heavier hydrocarbons cut of about 13000 kilograms per hour is produced as a bottom stream from K-6 at about 230 ° C, namely Stream S13 in figure, called Gas oil boiling above about 240 ° C and pumped by pump P-8. It is further cooled in feed pre-heat exchanger E-6 and cooler W-S, before being routed to storage. All the side strippers are provided with a good amount of stripping steam to remove the lighter fractions from the side cuts. Stabilizer distillation K-3 Section: About 14000 kilograms per hour of the feed Stream S7 consisting a mixture of Stream S5 and Stream S6 of boiling range of about lBP - 90 ° C from distillations K-1 and K-2 respectively, after being heated in feed pre-heat exchanger E-7 to about 90 ° C, is fed to the feed tray of the stabilizer distillation and is distilled. The top vapors are condensed in overhead condenser C-3 at about 50 ° C and at a pressure of 7.0 kg/square cm and collected in reflux drum D-3 before being refluxed back, above top tray. About 150 kilograms per hour of the lighter vapors are routed out from the drum D-3 to either fuel gas or to the gas concentration section. The balance overhead liquid product of about 600 kilograms per hour is to the storage section, namely Stream S8 in figure, as LPG. The heavier hydrocarbons cut of about 13000 kilograms per hour, called stabilized Naphtha of boiling range of about 30- 90 ° C is produced as a bottom stream, namely Stream S9 in figure. It is further cooled in feed pre-heat exchanger E-8 and cooler W-1, before being routed to storage. At the battery limit of unit, the Naphtha side cut streams S10 and S11, and stabilizer bottom stream S9 are blended into stream S14 as per the finished product specifications of vapour pressure, boiling range and flash point before being treated in secondary processing units as per the specification requirements of finished final products. Aviation Turbine fuel or kerosene stream S12 is further treated in secondary processing units as per the specification requirements of finished final products. Gas oil stream S13 is routed to the refinery diesel or fuel oil pool. Weclaim: 1. The process for refining condensate of mineral origin in crude distillation unit characterized in that (a) The condensate S1 after being preheated in E1is fed to the first distillation called preflash distillation K1. (b) 5-10% of condensate called ultra light naphtha S5 is drawn from the top of K1 by controlling K1 top temperature at 80-100° C and at a pressure of 1- 3 kg/square cm gauge. (c) The balance portion of condensate is drawn from bottom of Kl as stream S4. (d) The stream S4 is heated in Fired Heater F1 to 200-300° C before being fed to the main crude distillation K2. (e) 10-30% of condensate is drawn from the top of the main crude distillation K2 as light naphtha S6 by controlling Kl top temperature at 80-120° C and at a pressure of 1-2 kg/square cm gauge. (f) 10-30% of condensate is drawn as the first side cut of the main crude distillation K2 as medium naphtha S10 by controlling the flow of first side cut at a temperature of at 110-160° C and at a pressure of I -2 kg/square cm gauge. (g) 10-30% of condensate is drawn as the second side cut of the main crude distillation K2 as heavy naphtha S11 by controlling the flow of second side cut at a temperature of at 135- 200° C and at a pressure of 1-2 kg/square cm gauge. (h) The lighter streams of Naphtha S5 from K1 and S6 from K2 are stabilized in stabilizer distillation K3 producing a stabilized naphtha stream S9 from the bottom. (i) The stabilized Naphtha stream S9, first side cut S10 and second side cut Sll are blended into a single Naphtha product S14. 2. The process according to claim 1 wherein the distillation Kl is optionally bypassed and the condensate S1 after being preheated is fed to the Fired Heater F1 and heated to 200-300° C before being fed to the main crude distillation K2 with consequent steps (e) to (i). 3. The process according to claim 1 wherein the distillations Kl, K2 and K3 may have different types of fractionating elements as herein described. 4. The process according to claims 1 and 2 wherein the number of side cuts of Naphtha from main crude distillation K2 may be more or less than that mentioned in claim 1 but there is provided at least one side cut Naphtha stream from main crude distillation K2. 5. The process according to claims 1,2 and 3, wherein the side cuts from the main crude distillation K2 are further optionally distilled in additional distillations K4, KS and K6 conventionally called stripping. 6. The process according to claim 1 wherein the hydrocarbon condensate feed S1 to the first distillation Kl consists of 30% or more hydrocarbons having boiling point less than 140 °C and derived from either a gas field or a crude oil field. 7. The process according to claim 1 wherein the overhead streams S3 and S5 from preflash distillation K1 and overhead stream S6 from crude distillation K2 are optionally processed in a gas concentration unit to separate the light gases and various boiling point naphthas. 8. The process according to claim 1, wherein the temperatures and pressures are substantially similar to the ones mentioned in the examples. 9. A process for refining condensate of mineral origin in crude distillation unit, substantially as herein described with reference to foregoing examples and drawing. This invention describes a new process for the refining of Condensate of mineral origin in Crude Oil Distillation Units, by drawing various fractions of naphtha as side cuts in the main crude distillation, as detailed in figure attached.

Documents:

00940-kol-2005-abstract.pdf

00940-kol-2005-claims.pdf

00940-kol-2005-description (complete).pdf

00940-kol-2005-drawings.pdf

00940-kol-2005-form 1.pdf

00940-kol-2005-form 18.pdf

00940-kol-2005-form 2.pdf

00940-kol-2005-form 3.pdf

00940-kol-2005-letter patent.pdf

00940-kol-2005-rply f.e.r.pdf