DESC:FIELD
The present disclosure relates to the field of separation technologies.
DEFINITIONS
As used in the present disclosure, the following terms are generally intended to have the meaning as set forth below, except to the extent that the context in which they are used, indicate otherwise.
Continuous phase: The term “continuous phase” refers to the medium in which another substance (dispersed phase) is distributed. The continuous phase forms the bulk of the system and surrounds the dispersed particles.
Dispersed phase: The term “dispersed phase” refers to particles or droplets distributed throughout the continuous phase. These particles are generally smaller and dispersed within the continuous phase.
Delayed coker units (DCU): The term ‘delayed coker unit” refers to a coker unit that is used for heating a residual oil feed to its thermal cracking temperature in a furnace with multiple parallel passes.
Down-comer: The term ‘down-comer’ refers to a vertical obstruction that extends downward from the edges of the perforated trays forming a flow passage within a vessel to direct the flow of fluid from a location above a tray to a location below the tray. It has a function to distribute a continuous phase in a downward direction. The term down-comer can alternatively be referred to as an up-comer, depending on the direction of fluid flow within the vessel.
Up-comer: The term ‘up-comer’ refers to a vertical obstruction that extends upward from the edges of the perforated trays forming a flow passage within a vessel to direct the flow of fluid from a location below a tray to a location above the tray. It has a function to distribute a continuous phase in an upward direction.
Fluid catalytic cracking (FCC): The term “fluid catalytic cracking (FCC)” refers to an oil refinery process that converts heavy petroleum fractions into lighter hydrocarbon products inside a reactor.
Fluid catalytic cracking unit (FCCU): The term “Fluid catalytic cracking unit (FCCU)” refers to refining equipment that is used to convert heavy petroleum fractions into lighter hydrocarbon products.
Liquid seal: The term “liquid seal” refers to a vertical obstruction that extends downward from a weir or a down-comer to eliminate the bypass of a light phase or a heavy phase through the tray.
Light phase fluid: The term “light phase fluid” refers to a substance with a lower density compared to another immiscible phase in a separation process. The term "light phase fluid" herein particularly refers to liquified petroleum gas (LPG).
Perforated tray: The term “perforated tray” refers to a flat plate with a plurality of perforations for the passage of vapour/liquid that is commonly used in contacting devices such as a gas-liquid contacting device or a liquid-liquid extraction/contacting device respectively.
Sauter mean diameter: The term “Sauter mean diameter” refers to an average measure of particle size. Sauter mean diameter is defined as the diameter of a sphere that has the same volume to surface area ratio as a particle of interest.
Total superficial velocity: The term “total superficial velocity” also known as ‘total flux rate’ refers to as the sum of the total volumetric flow rates of a lighter phase and a heavier phase divided by the cross-section area of a column.
Visbreaker: The term “Visbreaker” refers to a processing unit in an oil refinery that is used to reduce the quantity of residual oil produced in the distillation of crude oil and to increase the yield of more valuable middle distillates (heating oil and diesel) by the refinery.
Weir: The term “weir” refers to a vertical obstruction that extends upward or downward from the edges of the perforated trays and has the function of maintaining a desired liquid level on or below the tray.
Aperture size: The term “aperture size” refers to the diameter of a perforation. Specifically, it denotes the physical measurement across the widest part of the perforation, measured from one edge to the opposite edge through the center of the opening.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
One of the downstream hydrocarbon lighter phase products of the petroleum and petrochemical industries is liquefied petroleum gas, or LPG. The main sources of LPG are a variety of units, including fluid catalytic cracking, coker, and crude distillation units. LPG contains a variety of sulfur species impurities depending on its source, including hydrogen sulfide (H2S)/mercaptans, carbonyl sulfide (COS or OCS), methyl and ethyl mercaptans, dimerization products of the mercaptans (such as di- and tri-sulfides), and similar substances. The most crucial job for the petrochemical and petroleum refineries is to remove these sulfur impurities from light phase fluid such as LPG. Traditionally, the sulfur impurities are eliminated by reacting with absorbents in extraction columns while the impurities are present.
Three steps are involved in the known process to remove these impurities: (i) LPG is first contacted with amine in an absorber column to remove acidic impurities like H2S and COS; this is followed by washing the product LPG in water wash drum to remove any soluble amine; (ii) LPG exiting water wash drum is then contacted with diluted caustic in a prewash column to remove any remaining H2S; and (iii) LPG exiting the prewash column is then contacted with aqueous caustic solution in a liquid-liquid extractor to remove acidic impurities like RSH.
Further, the existing apparatus of the amine absorber and caustic extractor is a cylindrical column provided with sieve trays. The design of sieve trays provided in the cylindrical column is such that the column is limited by the maximum total flux rate of 30 m3/hr/m2 to 35 m3/hr/m2. Beyond this total flux rate, the cylindrical column faces amine carryover along with the overhead LPG and the desired sulfur species specification in the LPG is not achieved. This carryover of amine from the absorber increases the concentration of amine in water wash drum. When LPG from the absorber column is passed through such a relatively higher concentration of solution of amine in the water wash drum, the amine being carried over along with LPG does not dissolve in water present in the wash water drum. Thus, a significant amount of amine is carried over by LPG leaving the water wash drum and lands in the prewash column or even further down into the extractor column. This not only results in permanent loss of amine from the system but also requires higher amine makeup leading to significant economic penalty.
During the carryover events of amine from the absorber, H2S specification in LPG is not achieved and H2S ingress into the prewash column demands frequent changeover of caustic thus leading to increased blowdown frequency of spent caustic to Wet Air Oxidation (WAO) unit in Effluent Treatment Plant (ETP). In addition to this, the amine slippage in the prewash and extraction columns results in the amine ingress in the blowdown spent caustic which increases the chemical oxygen demand (COD) of the effluent stream going to ETP. ETP units are constrained by the processing capacity as well as the severity to deal with such effluent streams.
Frequent slippage of H2S from the prewash column to the extractor causes the formation of sodium sulfide (Na2S) which in the presence of oxygen, subsequently forms sodium thiosulfate (Na2S2O3) solid which in turn precipitates in the extractor causing sudden caustic carryover events. The deposition of these salts stops caustic flow from the extractor bottom resulting in caustic carryover along with LPG at the top. The restoration of the unit to normal operation in such a scenario, sometimes requires lowering throughput and replacing the entire inventory of caustic in the extractor column. The slippage of H2S in the extractor column also consumes more caustic and results in more spent caustic as well as make-up caustic leading to further economic penalties.
The spent caustic from the extractor is regenerated in the regeneration unit where the spent caustic is contacted with air (molecular oxygen) in the presence of a catalyst to convert sodium mercaptides (NaSR) formed in the extraction column to disulfides (RSSR) and caustic (NaOH). The excessive concentration of Na2S in caustic results in inefficient regeneration of caustic, accumulation of solids, and increase in the concentration of surfactants, such as sodium mercaptides; which in turn aggravates the issue of caustic carryover from the extractor.
Therefore, the throughput to the entire LPG processing unit (involving absorber, prewash, extractor, and regenerator) thus gets limited because of the above-mentioned issues. The existing sulfur impurities removal process is unable to push the fluid at higher flow rates which compromises throughput. Further, the reduction in severity and throughput of upstream LPG-producing units such as FCC, Visbreaker, Delayed Coker, and the like shall lead to a significant loss of revenue due to a lack of efficient sulfur impurities removal process.
There is, therefore, felt a need to develop an apparatus for removing sulfur impurities from an LPG and a process thereof that mitigates the drawback mentioned herein above or at least provides a useful alternative.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
It is an object of the present disclosure to ameliorate one or more problems of the background or to at least provide a useful alternative.
An object of the present disclosure is to provide an apparatus for removal of sulfur impurities from LPG.
Another object of the present disclosure is to provide an apparatus for removal of sulfur impurities from LPG that is designed to enhance the interaction between LPG and a scrubbing fluid.
Still another object of the present disclosure is to provide an apparatus for removal of sulfur impurities from LPG that has high throughput with no carry-over of scrubbing fluid.
Yet another object of the present disclosure is to provide a process for removing sulfur impurities from LPG.
Still another object of the present disclosure is to provide a process for removing sulfur impurities from LPG that is efficient and minimizes downstream contamination.
Yet another object of the present disclosure is to provide a process for removing sulfur impurities from LPG that is simple, environment friendly and economical.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure relates to an apparatus to remove sulfur impurities from a liquified petroleum gas (LPG). The apparatus comprises:
(a) a housing defined by an operative vertical tubular body extending between an operative top and an operative base;
(b) a first inlet located proximal to the operative base, configured to introduce the LPG with sulfur impurities at a predetermined pressure;
(c) a second inlet located proximal to the operative top, configured to introduce a scrubbing fluid;
(d) a plurality of perforated trays extending radially inwards within the housing located above the first inlet arranged in a zig-zag pattern, wherein each tray is spaced apart from the other at a distance ranging from 500 mm to 1500 mm, the trays configured with perforations having an aperture size ranging from 2 mm to 15 mm, wherein the perforations are arranged to allow the passage of the LPG and the scrubbing fluid in a dispersed phase at a velocity ranging from 0.2 m/s to 1.5 m/s;
(e) at least one weir along with a down-comer or an up-comer attached to the perforated trays, configured to direct the flow of the LPG or the scrubbing fluid;
(f) a first outlet located at an operative top of the housing to discharge LPG having reduced amount of sulfur impurities; and
(g) a second outlet located at an operative base of the housing to discharge a scrubbing fluid containing sulfur impurities.
In accordance with the present disclosure, at least one perforated tray is configured above the second inlet to enhance the separation between the LPG and the scrubbing fluid in the dispersed phase.
In accordance with the present disclosure, the plurality of perforated trays are in the range of 4 to 15.
In accordance with the present disclosure, the predetermined pressure is in the range of 10 bar to 15 bar.
In accordance with the present disclosure, the at least one weir along with the up-comer is configured to direct the flow of the LPG received from the first inlet in an upward direction in a continuous phase and wherein the scrubbing fluid received from the second inlet is configured to flow in a downward direction through the perforations in a dispersed phase.
In accordance with the present disclosure, the at least one weir along with the down-comer is configured to direct the flow of the scrubbing fluid received from the second inlet in a downward direction in a continuous phase and wherein the LPG received from the first inlet is configured to flow in an upward direction through the perforations in a dispersed phase.
In accordance with the present disclosure, the weir has a height in the range of 45 mm to 300 mm above a perforated tray to which it is attached.
In accordance with the present disclosure, the down-comer or the up-comer is spaced in the range of 50 mm to 1500 mm from a perforated tray to which it is attached.
In accordance with the present disclosure, the at least one down-comer is attached to at least one liquid seal to eliminate bypass of either the LPG or the scrubbing fluid through the tray.
In accordance with the present disclosure, the total height of the down-comer and the liquid seal is in the range of 500 mm to 1500 mm.
In accordance with the present disclosure, the scrubbing fluid is selected from liquid alkanol amine absorbent and caustic; wherein the liquid alkanol amine absorbent is selected from the group consisting of monoethanol amine (MEA), diethanol amine (DEA), and methyl diethanol amine (MDEA).
The present disclosure further relates to a process for removing impurities from a liquified petroleum gas (LPG). The process comprising the following steps:
(i) feeding LPG at a first predetermined pressure with sulfur impurities through a first inlet located proximal to an operative base of housing, and feeding a scrubbing fluid through a second inlet located proximal to an operative top of the housing at a predetermined total flux rate; the housing has a plurality of perforated trays extending radially inwards within the housing spaced apart from each other at a distance ranging from 500 mm to 1500 mm; and the perforated trays have perforations having an aperture size ranging from 2 mm to 15 mm;
(ii) contacting the LPG with the scrubbing fluid at a predetermined temperature and a second predetermined pressure in the housing by at least one weir along with a down-comer or an up-comer or the perforations of the plurality of perforated trays; wherein the contacting facilitates the removal of impurities from the LPG and the transfer of the impurities into the scrubbing fluid;
(iii) obtaining an LPG having reduced amount of sulfur impurities from a first outlet located at an operative top of the housing; and
(iv) discharging a scrubbing fluid containing sulfur impurities from a second outlet located at an operative base of the housing.
In accordance with the present disclosure, the weir along with the up-comer is configured to direct the flow of the LPG received from the first inlet in an upward direction in a continuous phase, and wherein the scrubbing fluid received from the second inlet is configured to flow in a downward direction through the perforations in a dispersed phase at a first predetermined velocity.
In accordance with the present disclosure, the weir along with the down-comer is configured to direct the flow of the scrubbing fluid received from the second inlet in a downward direction in a continuous phase, and wherein the LPG received from the first inlet is configured to flow in an upward direction through the perforations in a dispersed phase at a second predetermined velocity.
In accordance with the present disclosure, an operative bottom portion of the housing is configured to have the scrubbing fluid as a continuous phase and the LPG as a dispersed phase fluid, and an operative top portion of the housing is configured to have the LPG as a continuous phase and the scrubbing fluid as a dispersed phase fluid forming an active interface.
In accordance with the present disclosure, the first predetermined pressure is in the range of 10 bar to 15 bar.
In accordance with the present disclosure, the predetermined total flux rate is in the range of 25 m3/hr/m2 to 60 m3/hr/m2.
In accordance with the present disclosure, the predetermined temperature is in the range of 35 oC to 50 oC.
In accordance with the present disclosure, the second predetermined pressure is in the range of 10 bar to 15 bar.
In accordance with the present disclosure, the first predetermined velocity is in the range of 0.2 m/s to 1.5 m/s.
In accordance with the present disclosure, the second predetermined velocity is in the range of 0.2 m/s to 1.5 m/s.
In accordance with the present disclosure, 4 to 15 perforated trays are present in the housing (100).
In accordance with the present disclosure, the scrubbing fluid is selected from liquid alkanolamine absorbent and caustic; the liquid alkanolamine absorbent is selected from monoethanol amine (MEA), diethanol amine (DEA), and methyl diethanol amine (MDEA).
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
The present disclosure will now be described with the help of the accompanying drawing, in which:
Fig. 1 illustrates an apparatus for the removal of sulfur impurities from an LPG in accordance with the present disclosure;
Fig. 2 illustrates a perforated tray having a punched active tray hole (perforation) area in a triangular pitch in accordance with the present disclosure;
Fig. 3a illustrates a type I perforated tray arrangement and the direction of flow in accordance with an embodiment of the present disclosure;
Fig. 3b illustrates a type II perforated tray arrangement and the direction of flow in accordance with an embodiment of the present disclosure; and
Fig. 3c illustrates a type III perforated tray arrangement and the direction of flow in accordance with an embodiment of the present disclosure.
LIST OF REFERENCE NUMERALS
Reference no. Reference
1000 apparatus for the removal of sulfur impurities
10 liquified petroleum gas (LPG)
20 scrubbing fluid
100 housing defined by an operative vertical tubular body
200 active tray hole area with perforation arranged in a triangular pitch
202 perforated tray submerged in the scrubbing fluid
204 perforated tray with down-comer, liquid seal and weir
206 perforated tray submerged in the LPG
208 perforated tray (additional tray above inlet for scrubbing fluid)
250 weir
252 down-comer/ up-comer
254 liquid seal
300 inlet for LPG with sulfur impurities (first inlet)
400 inlet for scrubbing fluid (second inlet)
600 outlet for LPG with reduced sulfur impurities (first outlet)
700 outlet for scrubbing fluid with sulfur impurities (second outlet)
800 active interface
DETAILED DESCRIPTION
The present disclosure relates to the field of separation technologies.
Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.
As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed elements.
The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
A light phase fluid such as Liquefied Petroleum Gas (LPG) is one of the downstream hydrocarbon products of the petroleum and petrochemical industry. LPG is primarily obtained from various units such as a crude distillation unit, a coker unit, a fluid catalytic cracking unit and the like. Depending upon the source of the light phase fluid such as LPG contains different sulfur impurities such as hydrogen sulfide (H2S)/mercaptans, carbonyl sulfide (COS or OCS), methyl and ethyl mercaptans, dimerization products of the mercaptans (e.g., di-sulfides and tri-sulfides) and the like. Removal of these sulfur impurities from the light phase is the most important task for petroleum refineries/petrochemical industry. Conventionally, the impurities are removed by using extraction columns, by reacting the sulfur species with absorbents.
The existing processes for LPG involve the removal of impurities in three stages: (i) contacting of LPG initially with a heavy phase fluid such as amine in an absorber column to remove impurities such as H2S, and COS, followed by water wash of product LPG in a water wash drum to remove any soluble amine, (ii) contacting of LPG coming out of the water wash drum with dilute caustic in prewash column to remove the traces of H2S present in LPG, and (iii) contacting of LPG coming out of the prewash column with aqueous caustic solution in liquid-liquid extractor to remove acidic impurities such as RSH.
The existing apparatus for amine absorption and caustic extraction consists of a cylindrical column equipped with perforated trays. The design of these trays limits the column to a maximum total flux of 30 to 35 m3/hr/m2. Exceeding this flux leads to amine carryover with the overhead LPG, preventing the LPG from meeting the desired sulfur species specifications. This carryover increases the amine concentration in the wash water drum. When LPG from the absorber column passes through this higher concentration of amine solution in the drum, the amine does not dissolve in the water, resulting in a significant amount of amine being carried over with the LPG. This amine may end up in the prewash column or even further into the extractor column, leading to permanent amine loss from the system. Consequently, additional amine makeup is required, resulting in considerable economic costs.
In an aspect, the present disclosure provides an apparatus (1000) to remove sulfur impurities from a liquified petroleum gas (LPG). The apparatus (1000) of the present disclosure is explained below in detail with reference to Fig. 1 to Fig. 3.
The apparatus (1000) is configured to enable contact between the LPG with sulfur impurities and a scrubbing fluid.
As illustrated in Fig. 1, the apparatus (1000) comprises a housing (100), a first inlet (300), a second inlet (400), a plurality of perforated trays (202, 204, 206, 208), at least one weir (250) along with a down-comer or an up-comer (252), a first outlet (600) and a second outlet (700).
In accordance with the present disclosure, the housing (100) is defined by an operative vertical tubular body extending between an operative top and an operative base.
In accordance with the present disclosure, the first inlet (300) is located proximal to the operative base of the housing (100). The first inlet is configured to introduce the LPG which is with sulfur impurity at a predetermined pressure. In an embodiment of the present disclosure, the first inlet (300) is located below the bottommost tray of the plurality of perforated trays.
In accordance with the present disclosure, the predetermined pressure is in the range of 10 bar to 15 bar. In an embodiment, the predetermined pressure is 14 bar.
In accordance with the present disclosure, the second inlet (400) is located proximal to the operative top of the housing (100). The second inlet is configured to introduce the scrubbing fluid.
In accordance with the present disclosure, the plurality of perforated trays (202, 204, 206, 208) are placed perpendicular to a central axis of the housing (100) inside the housing (100). The plurality of perforated trays (202, 204, 206, 208) extends radially inwards within the housing (100) from the wall of the housing (100). The plurality of perforated trays are located above the first inlet (300) arranged in a zig-zag pattern. Each tray is spaced apart from the other at a distance ranging from 500 mm to 1500 mm.
In accordance with the present disclosure, the plurality of perforated trays are configured with perforations having an aperture size ranging from 2 mm to 15 mm. The perforations are arranged in a predetermined pattern to allow the passage of the LPG and the scrubbing fluid to flow in a dispersed phase at a velocity ranging from 0.2 m/s to 1.5 m/s.
In accordance with the present disclosure, at least one weir (250) along with a down-comer or an up-comer (252) is attached to the perforated trays. The weir along with the down-comer or the up-comer (252) is configured to direct the flow of the LPG or the scrubbing fluid in the dispersed phase.
In accordance with an embodiment of the present disclosure, the at least one weir (250) along with an up-comer (252) is attached to the perforated trays and is configured to direct the flow of the LPG received from the first inlet (300) in an upward direction in a continuous phase and the scrubbing fluid received from the second inlet (400) is configured to flow in a downward direction through the plurality of perforations in a dispersed phase.
In accordance with another embodiment of the present disclosure, the at least one weir (250) along with a down-comer (252) is attached to the perforated trays and is configured to direct the flow of the scrubbing fluid received from the second inlet (400) in a downward direction in a continuous phase and the LPG received from the first inlet (300) is configured to flow in an upward direction through the plurality of perforations in a dispersed phase.
In accordance with the present disclosure, the first outlet (600) is located at an operative top of the housing (100) to discharge LPG having a reduced amount of sulfur impurities.
In accordance with the present disclosure, the second outlet (700) is located at an operative base of the housing (100) to discharge the scrubbing fluid containing sulfur impurities.
In accordance with the embodiments of the present disclosure, the liquefied petroleum gas (LPG) is a light phase fluid.
In accordance with the embodiments of the present disclosure, the sulfur impurities are selected from the group consisting of hydrogen sulfide (H2S), mercaptan (RSH) and carbonyl sulfide (COS).
In accordance with the embodiments of the present disclosure, the scrubbing fluid is selected from liquid alkanol amine absorbent and caustic, wherein the liquid alkanol amine absorbent is selected from the group consisting of monoethanol amine (MEA), diethanol amine (DEA), and methyl diethanol amine (MDEA). In an exemplary embodiment, the scrubbing fluid is methyl diethanol amine (MDEA). In another exemplary embodiment, the scrubbing fluid is caustic. In an embodiment, the scrubbing fluid is monoethanol amine (MEA). In another embodiment, the scrubbing fluid is diethanol amine (DEA).
In accordance with the present disclosure, the phase that is distributed over the perforated tray is a continuous phase and the phase that is passed through the perforations of the perforated trays in the form of droplets is a dispersed phase.
In accordance with the embodiments of the present disclosure, the apparatus (1000) has at least one perforated tray (208) configured above the second inlet (400) to enhance the separation between the LPG and the scrubbing fluid. In an embodiment, the apparatus (1000) has one perforated tray (208) configured above the second inlet (400) to enhance the separation between the LPG and the scrubbing fluid. In another embodiment, the apparatus (1000) has two perforated trays configured above the second inlet (400) to enhance the separation between the LPG and the scrubbing fluid.
The additional perforated trays are provided above the second inlet (400) to promote coalescence and disengagement of the higher phase fluid (scrubbing fluid) which might get carried over along with the lighter phase fluid (LPG).
In accordance with the embodiments of the present disclosure, the distance between the consecutive perforated trays provides enough length between the trays for the jet of the pressurized fluid to break and to be able to provide the droplets which in turn would have enough time for mass transfer and disengagement between two liquid phases to achieve the desired sulfur specification in product LPG without any scrubbing fluid (heavy phase) carryover along with LPG.
In accordance with the embodiments of the present disclosure, the plurality of perforated trays in the housing (100) of the apparatus (1000) are in the range of 4 to 15 (has a count of 4 to 15). The number of perforated trays are calculated in such a way that when the amine is scrubbing fluid, it reduces the H2S sulfur impurities from the typical value of 2 mol% in the LPG to less than 20 mol ppm and more preferably less than 10 mol ppm in the LPG and in case of caustic extractor, it handles LPG containing the typical value of 2000 mol ppm of RSH and reduces it to less than 10 mol ppm.
In accordance with the embodiments of the present disclosure, the weir (250) has a height in the range of 45 mm to 300 mm above a perforated tray to which it is attached; and the down-comer or the up-comer (252) is spaced in the range of 50 mm to 1500 mm from a perforated tray to which it is attached. In an exemplary embodiment, the weir has a height of 50 mm. In another exemplary embodiment, the weir has a height of 200 mm. In still another exemplary embodiment, the weir has a height of 250 mm. In an embodiment, the down-comer is attached to a perforated tray and extends from the tray with a space of 100 mm.
In accordance with the present disclosure, a perforated tray is provided with a weir to create a desired liquid level of scrubbing fluid on the tray. The perforated trays are provided with a weir creating an additional mass transfer path for the lighter phase (LPG) enabling higher contact time and larger surface area for mass transfer. This results in a longer residence time of dispersed phase droplets inside the layer of continuous phase thus providing not only enough contact time but also the ability of the heavier phase liquid (scrubbing fluid) to reach towards equilibria with respect to the concentration of sulfur impurities in the light phase fluid.
In accordance with an embodiment of the present disclosure, a down-comer is configured to allow passage of the scrubbing fluid in a downward direction and over the perforated trays to form a continuous phase. In this case, the LPG is passed through the perforations to form a jet of droplets of the LPG in an upward direction to be dispersed in the continuous scrubbing fluid.
In accordance with another embodiment of the present disclosure, a perforated tray is provided with a down-comer to create a desired liquid level of LPG below the tray. The down-comer works as an up-comer and is configured to allow passage of the LPG in an upward direction and below the perforated trays to form a continuous phase. In this case, the scrubbing fluid is passed through the perforations to form a jet of droplets of the scrubbing fluid in a downward direction to dispersed in the continuous LPG.
In accordance with the embodiments of the present disclosure, the at least one down-comer (252) is attached to at least one liquid seal (254) to eliminate the bypass of the LPG or the scrubbing fluid through the tray. The total height of the down-comer and the liquid seal (254) is in the range of 500 mm to 1500 mm. The liquid seal is provided below the down-comer or above the weir to eliminate the bypass of the LPG or the scrubbing fluid through the perforated trays.
In accordance with the embodiments of the present disclosure, a perforation has a diameter in the range of 2 mm to 15 mm. In an exemplary embodiment, a perforation has a diameter of 5 mm. In another exemplary embodiment, a perforation has a diameter of 10 mm.
This plurality of the perforation on the perforated trays provides the jets of a phase of required diameter which on breakage upon contact with other phases provides the droplets of the size creating optimum surface area per unit volume without forming smaller droplets which leads to a stable emulsion.
In accordance with an embodiment of the present disclosure, the perforations are arranged in a triangular pitch.
In accordance with an embodiment of the present disclosure, the inlets (300, 400) and outlets (600, 700) are configured to have nozzles.
In accordance with an embodiment of the present disclosure, the perforated trays (202) located near the bottom of the housing (100) of the apparatus (1000) are submerged in the scrubbing fluid (heavy phase fluid), and the perforated trays (206) located near the top of the housing (100) of the apparatus (1000) are submerged in the LPG (light phase fluid).
In one scenario, the scrubbing fluid is the continuous phase, it flows from the top of the housing (100) to the bottom of the housing (100) through the down-comer (252) on the tray while the LPG which is now dispersed in the scrubbing fluid flows from housing (100) bottom to top in the form of droplets through perforated tray designed to allow contact between the scrubbing fluid and LPG when submerged in the scrubbing fluid.
In another scenario, LPG is the continuous phase, the LPG flows from the bottom to the top of the housing (100) through the down-comer (252) on the perforated tray while the scrubbing fluid which is now the dispersed phase and flows from the top to bottom in the form of droplets through perforated tray designed to allow contact between the scrubbing fluid and LPG when submerged in lighter phase (LPG).
In accordance with an embodiment of the present disclosure, some of the perforated trays at the bottom of the housing (100) are submerged in the scrubbing fluid with the objective of providing initial turbulence and effective mass transfer between the light and the scrubbing fluid by distributing light phase (LPG) into a pool of heavy phase (scrubbing fluid) thereby removing the major portion of the sulfur impurities present in LPG and then passing such a lean LPG after having washed though the pool of scrubbing fluid into the perforated trays above.
In accordance with an embodiment of the present disclosure, the sulfur impurities from the LPG interact with the scrubbing fluid for the removal of sulfur impurities from the LPG. For example, H2S in the LPG after interacting with scrubbing fluid (amine/caustic) dissociates into bisulfide ion (HS-) by a proton transfer reaction, which remains in the scrubbing fluid. RSH in the LPG after interacting with the caustic of the scrubbing fluid forms sodium mercaptides, which remain in the scrubbing fluid.
Fig. 3 illustrates the perforated tray arrangement and flow of the fluids, having three types as follows:
Type I: The perforated trays, 202, located near the operative bottom portion of the housing (100) are submerged in the scrubbing fluid (20) (amine/caustic). The scrubbing fluid is the continuous phase and it flows from the top to the bottom of the housing (100) through the down-comer and the dispersed LPG (10) (light phase fluid) flows from bottom to top in the form of droplets through the perforations of the perforated tray, 202, designed to allow contact between the scrubbing fluid and LPG when submerged in the scrubbing fluid (Fig. 3a).
Type II: The perforated trays, 206, located at the operative top portion of the housing (100) are submerged in the continuous phase. The LPG (10) (light phase fluid) is the continuous phase and it flows from the bottom to the top of the housing (100) through the up-comer (252) and the dispersed scrubbing fluid (20) flows from top to bottom in the form of droplets through the perforations of perforated tray, 206, designed to allow contact between the scrubbing fluid and LPG when submerged in the LPG (light phase fluid) (Fig. 3b).
Type III: In addition to type I or type II, the perforated trays, 204, are provided with a liquid seal (254) at the down-comer bottom (252) to eliminate bypass of LPG (10) (light phase fluid) fluid through the tray. Also, the perforated trays are provided with the weir (250) to create an additional mass transfer path for the LPG enabling larger surface area for mass transfer.
One or two additional trays, 208, are provided on top of the contacting zone to promote disengagement of the scrubbing fluid from the lighter phase (Fig. 3c).
In another aspect, the present disclosure provides a process for removing sulfur impurities from LPG.
The process comprises the following steps:
LPG with sulfur impurities is fed through a first inlet (300) at a first predetermined pressure located proximal to an operative base of housing (100) and a scrubbing fluid is fed through a second inlet (400) located proximal to an operative top of the housing (100) at a predetermined total flux rate.
In accordance with the present disclosure, the first predetermined pressure is in the range of 10 bar to 15 bar. In an embodiment, the first predetermined pressure is 14 bar.
In accordance with the embodiments of the present disclosure, the predetermined total flux rate is in the range of 25 m3/hr/m2 to 60 m3/hr/m2. In an exemplary embodiment, the total flux rate is 34 m3/hr/m2. In another exemplary embodiment, the total flux rate is 48 m3/hr/m2. In still another exemplary embodiment, the total flux rate is 52 m3/hr/m2. In yet another exemplary embodiment, the total flux rate is 28 m3/hr/m2. In another exemplary embodiment, the total flux rate is 56 m3/hr/m2.
In accordance with the present disclosure, the feed ratio of the LPG to the scrubbing fluid is in the range of 2:1 to 35:1 (v/v). In an exemplary embodiment, the feed ratio of the LPG to the scrubbing fluid is 5:1 (v/v). In another exemplary embodiment, the feed ratio of the LPG to the scrubbing fluid is 30:1 (v/v).
The process of the present disclosure allows the total flux rate at a higher total superficial velocity, thereby improving the throughput of the process.
In accordance with the present disclosure, the housing (100) has a plurality of perforated trays (202, 204, 206, 208) extending radially inwards within the housing (100). The perforated trays are spaced apart from each other at a distance ranging from 500 mm to 1500 mm.
In accordance with the embodiments of the present disclosure, the perforated trays have perforations having an aperture size ranging from 2 mm to 15 mm. In an exemplary embodiment, a perforation on the perforated tray has a diameter of 5 mm. In another exemplary embodiment, a perforation on the perforated tray has a diameter of 10 mm.
In accordance with the present disclosure, the first inlet (300) is located below the bottom-most perforated tray inside the housing (100).
In accordance with the embodiments of the present disclosure, the plurality of perforated trays in the housing (100) of the apparatus (1000) are in the range of 4 to 15 (has a count of 4 to 15).
The LPG is contacted with the scrubbing fluid at a predetermined temperature and at a second predetermined pressure in the housing (100) by at least one weir (250) along with a down-comer or an up-comer (252) or through the perforations of the plurality of perforated trays. The contacting facilitates the removal of impurities from the LPG and the transfer of the impurities into the scrubbing fluid.
In accordance with the embodiments of the present disclosure, the predetermined temperature is in the range of 35 oC to 50 oC. In an embodiment, the predetermined temperature is 50 oC.
In accordance with the embodiments of the present disclosure, the second predetermined pressure is in the range of 10 bar to 15 bar. In an embodiment, the second predetermined pressure is 14 bar.
In an embodiment of the present disclosure, the weir (250) along with the up-comer (252) is configured to direct the flow of the LPG received from the first inlet (300) in an upward direction in a continuous phase and the scrubbing fluid received from the second inlet (400) is configured to flow in a downward direction through the perforations in a dispersed phase at a first predetermined velocity.
In accordance with the embodiments of the present disclosure, the first predetermined velocity of the scrubbing fluid is in the range of 0.2 m/s to 1.5 m/s.
In another embodiment, the weir (250) along with the down-comer (252) is configured to direct the flow of the scrubbing fluid received from the second inlet (400) in a downward direction in a continuous phase and the LPG received from the first inlet (300) is configured to flow in an upward direction through the perforations in a dispersed phase at a second predetermined velocity.
In accordance with the embodiments of the present disclosure, the second predetermined velocity of the LPG is in the range of 0.2 m/s to 1.5 m/s. In an exemplary embodiment, the velocity of the LPG through the perforations of the perforated trays is 0.24 m/s. In another exemplary embodiment, the velocity of the LPG through the perforations of the perforated trays is 0.37 m/s. In still another exemplary embodiment, the velocity of the LPG through the perforations of the perforated trays is 0.55 m/s. In yet another exemplary embodiment, the velocity of the LPG through the perforations of the perforated trays is 1.41 m/s. In still another exemplary embodiment, the velocity of the LPG through the perforations of the perforated trays is 1.35 m/s.
This velocity provides the jet length of adequate height so that the dispersion of the scrubbing fluid into the LPG and alternatively the dispersion of the LPG into the scrubbing fluid such that the droplet size distribution and Sauter mean diameter of droplets provide not only enough surface area but also avoids the formation of any emulsion thus leading to elimination of scrubbing fluid carryover along with the LPG.
LPG having a reduced amount of sulfur impurities is obtained from a first outlet (600) attached at an operative top of the housing (100).
A scrubbing fluid containing sulfur impurities is discharged from a second outlet (700) attached at an operative base of the housing (100).
In accordance with an embodiment of the present disclosure, the LPG is a light phase fluid and the scrubbing fluid is a heavy phase fluid.
In accordance with an embodiment of the present disclosure, the sulfur impurities are selected from the group consisting of hydrogen sulfide (H2S), mercaptan (RSH) and carbonyl sulfide (COS).
In accordance with the embodiments of the present disclosure, the scrubbing fluid is selected from liquid alkanol amine absorbent and caustic, wherein the liquid alkanol amine absorbent is selected from the group consisting of monoethanol amine (MEA), diethanol amine (DEA), and methyl diethanol amine (MDEA). In an exemplary embodiment, the scrubbing fluid is methyl diethanol amine (MDEA). In another exemplary embodiment, the scrubbing fluid is caustic. In an embodiment, the scrubbing fluid is monoethanol amine (MEA). In another embodiment, the scrubbing fluid is diethanol amine (DEA).
In accordance with an embodiment of the present disclosure, an operative bottom portion of the housing (100) is configured to have the scrubbing fluid as a continuous phase and the LPG as a dispersed phase fluid, and an operative top portion of the housing (100) is configured to have the LPG as a continuous phase and the scrubbing fluid as a dispersed phase fluid forming an active interface (800).
In accordance with an embodiment of the present disclosure, an active interface (800) between the LPG and the scrubbing fluid is maintained higher up in the housing (100) with few perforated trays submerged in the LPG (light phase fluid).
In accordance with another embodiment of the present disclosure, the active interface (800) between the LPG and the scrubbing fluid is maintained near the bottom of the housing (100) with a few perforated trays submerged in the scrubbing fluid. In an embodiment of the present disclosure, the LPG is a light phase fluid and the scrubbing fluid is an absorbent such as amines and caustic.
The housing (100) and process for removal of the sulfur impurities from the raw LPG in accordance with the embodiment are described.
The apparatus comprising housing (100) is configured with 8 perforated trays for liquid-liquid contacting of raw LPG containing sulfur impurities with the scrubbing such as amines and caustic in order to create a large surface contact area between the two liquid phases at a temperature varying from 35 oC to 50 oC (preferably 40 oC to 45 oC) and pressure varying from 10.78 bar to 14.71 bar (11 kg/cm2(g) to 15 kg/cm2(g)) or more. The raw LPG enters the apparatus from the first inlet (300), located at an operative bottom portion of the housing (100) below the bottom-most tray and leaves the housing (100) from the first outlet (600), located at the top of the housing (100). The scrubbing fluid enters the housing (100) from the second inlet (400), located at an operative top portion of the housing (100) and exits the housing (100) from the second outlet (700), at the base of the housing (100). The perforated tray design consists of perforation of diameter preferably in the range of 5 mm to 12 mm and more preferably in the range of 8 mm to 10 mm, arranged by punching/drilling perforation in a triangular pitch on active tray hole area, which is demonstrated in Fig. 2.
Further, the perforated tray design also consists of specifying the number of perforation in such a way that the velocity of LPG through any given hole on the tray is in the range of 0.2 m/s to 1.5 m/s and more preferably in the range of 0.5 m/s to 0.9 m/s. The tray-to-tray spacing is kept in the range of 500 to 1500 mm. The total superficial velocity of LPG and scrubbing fluid (total volumetric flow of light and heavy liquid phases divided by the cross-section area of housing) is kept in the range of 25 to 60 m3/hr/m2 more preferably in the range of 40 to 55 m3/hr/m2. The H2S in LPG feed is as high as 2 mol% and the RSH in LPG feed can be as high as 2000 mol ppm.
The apparatus and the process of the present disclosure enable the LPG processing unit to operate at higher severity or throughput to increase the profit margin of refinery.
The apparatus and the process of the present disclosure eliminates the carryover of the scrubbing fluid (heavy phase) along with the product LPG which in turn, eliminates the associated issues such as amine and caustic inventory loss, salt deposition in extractor and oxidizer, emulsion formation in extractor, increase in chemical oxygen demand (COD) of effluent streams going to effluent treatment plant (ETP), increase in quantity of effluent going to ETP and the like.
The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment but are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
The present disclosure is further described in light of the following experiments which are set forth for illustration purposes only and not to be construed for limiting the scope of the disclosure. The following experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial scale.
EXPERIMENTAL DETAILS:
Removal of sulfur impurities from raw LPG (containing sulfur impurities) in accordance with the process of the present disclosure
Example 1: The apparatus was configured to combine type 1 and type 2 arrangement of perforated trays for the liquid flux of 34 m3/hr/m2 for contacting LPG and MDEA. LPG to amine ratio was kept at 5.0 vol/vol at flow rates. The diameter of the perforations of the perforated trays was kept at 5 mm so that the tray hole velocity of LPG was kept at around 0.24 m/s for the bottom 5 trays, which were submerged in amine. The interface level was kept between the 4th and 5th tray (counting trays 1 to 10 from the top). An additional tray was provided on top above the inlet of the scrubbing fluid to enhance the separation between scrubbing fluid and LPG. The apparatus gave average H2S content in LPG at 7 mol ppm. Initially, when the interface was kept above 4th tray, the column could not operate with the total liquid flux above 29 m3/hr/m2. For higher flow rates the interface level was further dropped between 6th and 7th tray. The apparatus operated up to the liquid flux of 48 m3/hr/m2 resulting in an LPG tray hole velocity of about 0.34 m/s with no carryover of amine along with product LPG leaving from the top of the apparatus while providing average H2S in product LPG at 9.3 mol ppm.
Example 2: The apparatus was configured to operate with a type 3 arrangement of perforated trays with 10 number of trays. The total liquid flux rate was kept at 34 m3/hr/m2 with the diameter of the perforations of the perforated trays of 10 mm. The weir height of 50 mm was provided on top of each tray to form an MDEA layer on each tray so that LPG flows through it at a velocity of about 0.24 m/s. An additional tray was provided on top above the inlet of the scrubbing fluid to enhance the separation between the scrubbing fluid and LPG. LPG to amine ratio was kept at 5.0 vol/vol at design flow rates. The interface level was kept at the bottom below the 10th tray as well as above between the 9th tray and 10th tray. The apparatus processed the total liquid flux of 52 m3/hr/m2 resulting in LPG tray hole velocity of about 0.37 m/s with no carryover of amine along with product LPG while providing average H2S in product LPG at 13.5 mol ppm even at LPG to amine ratio of about 6.1 vol/vol.
Example 3: The apparatus was configured to operate with a type 3 arrangement of perforated trays with 8 number of trays. The liquid flux was kept at about 28 m3/hr/m2 with the diameter of the perforations of the perforated trays of 10 mm. LPG to caustic ratio was kept at 30 vol/vol at design flow rates. The weir height of 250 mm was provided on some trays at the bottom and 200 mm for the remaining trays at the top of each tray to form a caustic layer on each tray so that LPG flows through it at a velocity of about 0.55 m/s. The interface level was kept at the bottom below the 8th tray initially and later it was increased such that the 8th tray was submerged in caustic. The apparatus processed liquid flux of 28 m3/hr/m2 with various flow rates of LPG at tray hole velocity ranging from about 0.46 m/s to 0.55 m/s without any carryover of caustic along with product LPG while providing average RSH content in product LPG at around 41 mol ppm when the interface was at bottom and about 18 mol ppm when 8th tray was submerged in caustic.
Example 4: The apparatus was configured to operate with a type 3 arrangement of perforated trays with 8 number of trays. The liquid flux was kept at about 28 m3/hr/m2 with the diameter of the perforations of the perforated trays of 10 mm. LPG to caustic ratio was kept at 30 vol/vol at design flow rates. The weir height of 250 mm was provided on some trays at the bottom and 200 mm for the remaining trays at the top of each tray to form a caustic layer on each tray so that LPG flows through it at a velocity of about 1.33 m/s. The interface level was kept at the bottom below the 8th tray initially and later it was increased such that the 8th tray was submerged in caustic. The apparatus could process liquid flux of 28 m3/hr/m2 with various flow rates of LPG at tray hole velocity ranging from about 1.35 m/s to 1.41 m/s without any carryover of caustic along with product LPG while providing average RSH content in product LPG at around 24 mol ppm when the interface was at bottom and about 11 mol ppm when 8th tray was submerged in caustic.
The performance analysis of the apparatus in accordance with the present disclosure for all examples is provided in Table 1.
Table 1: Performance analysis of the apparatus in accordance with the present disclosure:
Examples
Hole Velocity Total Liquid Flux Interface Position
H2S/RSH in LPG Product (mol ppm/wtppm) Carryover
cm/s m3/hr/m2 Avg Yes/No
Combination of Type 1 and Type 2 Trays
Example 1 21.9 31.7 Above 1st Tray 9 Yes
20.3 29.3 Above 4th Tray < 1 Yes
23.6 34.1 Above 5th Tray 7 No
33.8 48 Above 6th Tray Yes
33.8 48 Above 7th Tray 9.3 No
Type 3 Trays
Example 2 37.1 52 Below 10th Tray 12.3 No
37.1 52 Above 10th Tray 13.8 No
Type 3 Trays
Example 3 47.7 24.8 Above 6th Tray 18.2 No
54.7 28.5 Below 8th Tray 41.2 No
Type 3 Trays
Example 4 141.5 28.5 Below 8th Tray 23.6 No
135.2 27.2 Above 8th Tray 11.4 No

TECHNICAL ADVANCEMENTS
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of;
? an apparatus for removal of sulfur impurities from LPG that:
• allows the LPG or the scrubbing fluid to pass through the perforations at a higher velocity, and allows high superficial velocity of the contacting liquids, thereby improving throughput of the entire LPG processing unit;
• provides the desired specification of the product;
• does not contain any carryover of scrubbing fluid such as amine and caustic inventory loss in the LPG product; and
• avoids salt deposition in an extractor and oxidizer of the LPG processing unit, reduces emulsion formation in the extractor, increases in chemical oxygen demand (COD) of effluent streams going to effluent treatment plant (ETP), increases in the quantity of streams going to ETP, which results in avoidance of significant economic penalty due to improvement in throughput and severity of LPG processing units;
and
? a process for removal of sulfur impurities from LPG that is simple, efficient and economic.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The foregoing description of the specific embodiments so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired object or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation. ,CLAIMS:WE CLAIM:
1. An apparatus (1000) to remove sulfur impurities from a liquified petroleum gas (LPG), said apparatus (1000) comprising:
(a) a housing (100) defined by an operative vertical tubular body extending between an operative top and an operative base;
(b) a first inlet (300) located proximal to said operative base, configured to introduce said LPG with sulfur impurities at a predetermined pressure;
(c) a second inlet (400) located proximal to said operative top, configured to introduce a scrubbing fluid;
(d) a plurality of perforated trays (202, 204, 206, 208) extending radially inwards within said housing (100) located above said first inlet (300) arranged in a zig-zag pattern, wherein each tray is spaced apart from the other at a distance ranging from 500 mm to 1500 mm, said trays configured with perforations having an aperture size ranging from 2 mm to 15 mm, wherein said perforations are arranged to allow the passage of said LPG and said scrubbing fluid in a dispersed phase at a velocity ranging from 0.2 m/s to 1.5 m/s;
(e) at least one weir (250) along with a down-comer or an up-comer (252) attached to said perforated trays, configured to direct the flow of said LPG or said scrubbing fluid;
(f) a first outlet (600) located at an operative top of said housing (100) to discharge LPG having reduced amount of sulfur impurities; and
(g) a second outlet (700) located at an operative base of said housing (100) to discharge a scrubbing fluid containing sulfur impurities.
2. The apparatus as claimed in claim 1, wherein at least one perforated tray (208) is configured above said second inlet (400) to enhance the separation between said LPG and said scrubbing fluid in the dispersed phase.
3. The apparatus as claimed in claim 1, wherein said plurality of perforated trays are in the range of 4 to 15.
4. The apparatus as claimed in claim 1, wherein said predetermined pressure is in the range of 10 bar to 15 bar.
5. The apparatus as claimed in claim 1, wherein said at least one weir (250) along with said up-comer (252) is configured to direct the flow of said LPG received from said first inlet (300) in an upward direction in a continuous phase, and wherein said scrubbing fluid received from said second inlet (400) is configured to flow in a downward direction through said perforations in a dispersed phase.
6. The apparatus as claimed in claim 1, wherein said at least one weir (250) along with said down-comer (252) is configured to direct the flow of said scrubbing fluid received from said second inlet (400) in a downward direction in a continuous phase, and wherein said LPG received from said first inlet (300) is configured to flow in an upward direction through said perforations in a dispersed phase.
7. The apparatus as claimed in claim 1, wherein
• said weir (250) has a height in the range of 45 mm to 300 mm above a perforated tray to which it is attached; and
• said down-comer or said up-comer (252) is spaced in the range of 50 mm to 1500 mm from a perforated tray to which it is attached.
8. The apparatus as claimed in claim 1, wherein said at least one down-comer (252) is attached to at least one liquid seal (254) to eliminate bypass of either said LPG or said scrubbing fluid through the tray; wherein a total height of said down-comer and said liquid seal (254) is in the range of 500 mm to 1500 mm.
9. The apparatus as claimed in claim 1, wherein said scrubbing fluid is selected from liquid alkanol amine absorbent and caustic; wherein said liquid alkanol amine absorbent is selected from the group consisting of monoethanol amine (MEA), diethanol amine (DEA), and methyl diethanol amine (MDEA).
10. A process for removing impurities from liquified petroleum gas (LPG), said process comprising the following steps:
(i) feeding LPG at a first predetermined pressure with sulfur impurities through a first inlet (300) located proximal to an operative base of housing (100), and feeding a scrubbing fluid through a second inlet (400) located proximal to an operative top of said housing (100) at a predetermined total flux rate; said housing (100) has a plurality of perforated trays (202, 204, 206, 208) extending radially inwards within said housing (100) spaced apart from each other at a distance ranging from 500 mm to 1500 mm; and said perforated trays have perforations having an aperture size ranging from 2 mm to 15 mm;
(ii) contacting said LPG with said scrubbing fluid at a predetermined temperature and a second predetermined pressure in said housing (100) by at least one weir (250) along with a down-comer or an up-comer (252) or said perforations of said plurality of perforated trays (202, 204, 206, 208); wherein said contacting facilitates the removal of impurities from said LPG and the transfer of said impurities into said scrubbing fluid;
(iii) obtaining an LPG having reduced amount of sulfur impurities from a first outlet (600) located at an operative top of said housing (100); and
(iv) discharging a scrubbing fluid containing sulfur impurities from a second outlet (700) located at an operative base of said housing (100).
11. The process as claimed in claim 10, wherein said weir (250) along with said up-comer (252) is configured to direct the flow of said LPG received from said first inlet (300) in an upward direction in a continuous phase, and wherein said scrubbing fluid received from said second inlet (400) is configured to flow in a downward direction through said perforations in a dispersed phase at a first predetermined velocity.
12. The process as claimed in claim 10, wherein said weir (250) along with said down-comer (252) is configured to direct the flow of said scrubbing fluid received from said second inlet (400) in a downward direction in a continuous phase, and wherein said LPG received from said first inlet (300) is configured to flow in an upward direction through said perforations in a dispersed phase at a second predetermined velocity.
13. The process as claimed in claim 10, wherein an operative bottom portion of said housing (100) is configured to have said scrubbing fluid as a continuous phase and said LPG as a dispersed phase fluid, and an operative top portion of said housing (100) is configured to have said LPG as a continuous phase and said scrubbing fluid as a dispersed phase fluid forming an active interface (800).
14. The process as claimed in claim 10, wherein said first predetermined pressure is in the range of 10 bar to 15 bar.
15. The process as claimed in claim 10, wherein said predetermined total flux rate is in the range of 25 m3/hr/m2 to 60 m3/hr/m2.
16. The process as claimed in claim 10, wherein said predetermined temperature is in the range of 35 oC to 50 oC.
17. The process as claimed in claim 10, wherein said second predetermined pressure is in the range of 10 bar to 15 bar.
18. The process as claimed in claim 11, wherein said first predetermined velocity is in the range of 0.2 m/s to 1.5 m/s.
19. The process as claimed in claim 12, wherein said second predetermined velocity is in the range of 0.2 m/s to 1.5 m/s.
20. The process as claimed in claim 10, wherein said scrubbing fluid is selected from liquid alkanolamine absorbent and caustic; said liquid alkanolamine absorbent is selected from monoethanol amine (MEA), diethanol amine (DEA), and methyl diethanol amine (MDEA).

Dated this 11th Day of October, 2024

_______________________________
MOHAN RAJKUMAR DEWAN, IN/PA – 25
OF R. K. DEWAN & CO.
AUTHORIZED AGENT OF APPLICANT

TO,
THE CONTROLLER OF PATENTS
THE PATENT OFFICE, AT MUMBAI