Systems and Methods for Acid Gas Removal

PATENT

Systems and Methods for Acid Gas Removal

Inventors: Ramesh Gupta, Krishnan Sankaranarayanan, Himanshu Gupta, Benjamin A. McCool, Robert B. Fedich, Richard D. Lenz

Original Assignee: EXXONMOBIL RESEARCH AND ENGINEERING COMPANY

Application number: 13/030,576

Publication number: US 2011/0217218 A1

Filing date: Feb 18, 2011

FIELD OF THE DISCLOSURE

This disclosure generally relates to the selective removal of CO2 and/or other acid gases from a gaseous stream containing one or more of these gases.

In particular, this disclosure relates to low capital investment systems and methods for separating an acid gas from a gas mixture using an absorbent solution and one or more liquid spray devices in flow communication with one or more absorbent contactors. The absorbent solution can be treated under conditions suflicient to cause desorption of at least a portion of the acid gas.

DISCUSSION OF THE BACKGROUND ART

[0003] Global climate change concems may necessitate capture of CO2 in flue gases and other process streams. Conventional methods for CO2 capture include cryogenic distillation/ condensation, absorption using liquid solvents, such as amine scrubbing, or sorption using solid sorbents, such as pressure swing absorption (PSA) and/or temperature swing absorption (TSA). A prevalent option for separating CO2 from flue gases or other acid gas streams is scrubbing the gas stream using liquid amine sorbent molecules dissolved in water. These aqueous amine solutions chemically trap the CO2 via fonnation of one or more ammonium salts (carbamate/bicarbonate/carbonate). These salts are thennally unstable, enabling the regeneration of the free amine at elevated temperatures.

[0004] All of these technologies require a relatively low temperature of the gas stream to enable CO2 condensation or sorption. Conventional methods (PSA, TSA, and amine scrubbing) require CO2 uptake at relatively low temperatures (e.g., less than about 50° C.). Sorbent/solvent regeneration (CO2 desorption) is accomplished by a step change decrease in CO2 partial pressure (PSA), and/ or by a temperature increase to above about 100° C. (TSA, amine scrubbing). In all of these cases, CO2 capture costs depend significantly on the required heat exchange capacities for gas cooling/heating, steam generation for CO2 desorption and CO2 recompression costs.

[0005] Amine scrubbing is based on the chemistry of CO2 with amines to generate carbonate/bicarbonate and carbamate salts. Comrnercially, amine scrubbing typically involves contacting the CO2 and/ or H2S containing gas stream with an aqueous solution of one or more amines (e.g., monoethanolamine). The process requires high rates of gas-liquid exchange and the transfer of large liquid inventories between the absorption and regeneration steps and high energy (heating/cooling) requirements for the regeneration of amine solutions. This process is challenged by the corrosive nature of the amine solutions. These challenges limit its economic viability for large-scale applications (e.g., large combustion sources and power plants).

[0006] Aqueous amine scrubbing is economically practiced at small to medium process scales, however, the possibility that the large-scale capture of CO2 from fumaces may soon be mandated and create scenarios where current amine scrubbing technology is economically challenged. The relatively high cost of aqueous amine scrubbing on large volumes of dilute gas results from the need to heat and cool large volumes of solution resulting in large gas-liquid contactor and amine regeneration vessels. Combined with the high corrosivity of the CO2/arnine/water medium, the metallurgical costs for these large vessels become prohibitive. Downstream fouling of process equipment can also become problematic. Finally, the high latent heat of vaporization of water in aqueous absorbent systems greatly increases the energy required to heat the aqueous solution to the required regeneration temperature.

[0007] The growing need to incorporate carbon capture and sequestration (CCS) into fossil fuel-based power generation, has triggered accelerating research into altematives to conventional CO2 removal technology. Cyclic absorption technologies (e.g., PSA and TSA) using solid absorbents are also used in the gas purification industry. These processes avoid many of the limitations of amine scrubbing described above, but suffer from a lack of absorbents having suflicient CO2 adsorption capacities as well as lacking sufficiently selective CO2 absorption characteristics under the humid conditions always present in combustion flue gas.

[0008] Because of the very large volumes of the flue gases from refineries or power plants, use of traditional processes become prohibitively large and expensive. For example, it is estimated that multiple very large absorption towers, each exceeding 40 feet in diameter, would be needed to handle the several million cubic feet per hour of flue gas from a refinery or power plant. Additionally, expensive blower fans would be needed to draft the flue gas through the amine contactors. Since, the required capital investment is a large fraction of the CO2 capture costs, a more compact and less expensive CO2/ amine process is highly desirable. In addition, if anticipated future restrictions on CO2 emissions are mandated, a low cost method for CO2 capture will be a critical need as a part of CCS.

[0009] Carbon dioxide is a ubiquitous and inescapable byproduct of the combustion of hydrocarbons. There is growing concern over CO2 accumulation in the atmosphere and its role in global climate change. Therefore, in addition to the commercial benefits of CO2 recovery, enviromnental factors may soon require its capture and sequestration. For these reasons, the separation of CO2 from mixed gas streams is a rapidly growing area of research.

[0010] Therefore, a need exists for developing comrnercially viable altemative methods for the selective removal of CO2 from gas mixtures, especially alternative methods having economic viability for large-scale applications for CO2 removal (e.g., large combustion sources and power plants).

SUMMARY OF THE DISCLOSURE

[0011] In a preferred embodiment of the present invention, is a method of separating an acid gas component from a feed gas mixture comprising an acid gas, such method comprising: [0012] providing at least one liquid spray device in flow communication with at least one absorbent contactor, and at least one gas feed inlet line in flow communication with said at least one absorbent contactor, wherein said absorbent contactor is comprised of a at least one of a monolithic or packed bed;

[0013] contacting in said absorbent contactor in co-current flow at least a portion of a feed gas mixture containing at least one acid gas with at least a portion of a first absorbent solution under conditions suflicient to cause absorption of at least a portion of said acid gas, wherein said acid gas is comprised of CO2, H2S or a combination thereof;

[0014] removing a first partially scrubbed gas mixture from said absorbent contactor, wherein the molar concentration of acid gas in said first partially scrubbed gas mixture is less than the molar concentration of said acid gas in said feed gas mixture; and

[0015] removing a stream of a first spent absorbent solution from said absorbent contactor, which first spent absorbent solution contains at least a portion of the acid gas from the feed gas mixture.

[0016] Another preferred embodiment is a method of separating an acid gas component from a feed gas mixture comprising and acid gas, such method comprising:

[0017] providing at least a first ejector venturi nozzle in flow communication with at least a first absorbent contactor, and at least a second ejector venturi nozzle in flow comrnunication with at least a second absorbent contactor; said first absorbent contactor in flow communication with said second ejector venturi nozzle and said second absorbent contactor in flow communication with said first ejector venturi nozzle; [0018] ejecting a first ejector stream comprising liquid droplets from said first ejector venturi nozzle into said first absorbent contactor, said first ejector stream comprising a first absorbent solution and a first feed gas mixture containing at least one acid gas;

[0019] contacting in said first absorbent contactor in cocurrent flow at least a portion of said first feed gas mixture containing at least one acid gas with at least a portion of said first absorbent solution under conditions suflicient to cause absorption of at least a portion of said acid gas, wherein said acid gas is comprised of CO2, H2S or a combination thereof; [0020] removing a first partially scrubbed gas mixture from said first absorbent contactor, wherein the molar concentration of said acid gas in said first partially scrubbed gas mixture is less than the molar concentration of said acid gas in said first feed gas mixture;

[0021] ejecting a second ejector stream comprising liquid droplets from said second ejector venturi nozzle into said second absorbent contactor, said second ejector stream comprising a second absorbent solution and a second feed gas mixture containing at least a portion of said first partially scrubbed gas mixture from said first absorbent contactor; [0022] contacting in said second absorbent contactor in co-current flow at least a portion of said first partially scrubbed gas mixture with at least a portion of said second absorbent solution under conditions sufficient to cause absorption of at least a portion of said acid gas from said first partially scrubbed gas mixture; and

[0023] removing a stream of a second spent absorbent solution from said second absorbent contactor, which said second spent absorbent solution contains at least a portion of said acid gas from said first partially scrubbed gas mixture. [0024] In more preferred embodiments, the absorbent contactor is comprised of a monolithic bed containing substantially parallel channels. In other preferred embodiments, the absorbent contactor is operated such that the conditions in the monolithic bed are at or near a Taylor flow or slug flow regime through said parallel chamrels.

[0025] In preferred embodiments, the absorbent solution is selected from the group consisting of: an amine solution comprising a primary amine, a secondary amine, or mixtures thereof; an amine solution comprising a polyamine or mixtures thereof; an alkali or alkaline earth metal hydroxide solution; and an alkali or alkaline earth metal carbonate solution.

[0026] As used herein, the term “acid gas” is defined as any gas mixture that is comprised of (contains) carbon dioxide (CO2), hydrogen sulfide (H2S) or a mixture thereof. Preferably, the acid gas herein is comprised of a “flue gas” (or “combustion gas”) that is the product of the combustion of hydrocarbons. In embodiments herein, most preferably, the acid gas contains carbon dioxide (CO2).

[0027] As used herein, the term “absorbent contactor” (or “packed contactor” or “packed tower”) is defined as a vessel within which the gas mixture contacts the absorbent wherein within the vessel is at least one structured contacting means, such as vessel packing, trays, or monoliths. In preferred embodiments herein, the absorbent contactor vessel contains a monolith which allows the combined gas mixture/ absorbent to flow through paths engineered within the monolith. [0028] In other preferred embodiments, the monolithic beds have screens or inlets suflicient to operate the flow at or near a Taylor flow or slug flow regime through the absorbent contactor. The one or more monolithic beds function as a coalescer and a contactor.

[0029] The absorbent contactor is preferably operated under conditions suflicient for the one or more monolithic beds to demist the liquid droplets from vapor.

[0030] This disclosure yet further relates in part to a system for separating an acid gas component from a gas mixture comprising an acid gas, such method comprising:

[0031] at least one first ejector venturi nozzle;

[0032] at least one first absorbent contactor, wherein the at least one first ejector venturi nozzle is in flow communication with the at least one first absorbent contactor,

[0033] at least one second ejector venturi nozzle; and [0034] at least one second absorbent contactor, wherein the at least one second ejector venturi nozzle is in flow comrnunication with the at least one second absorbent contactor; [0035] wherein the at least one first absorbent contactor is in flow communication with the at least one second ejector venturi nozzle and the at least one second absorbent contactor is in flow communication with the at least one first ejector venturi nozzle.

[0036] In an embodiment, the above system can further comprise multiple absorbent contactors in parallel. In another embodiment of the above system absorbent contactor is comprised of a monolithic bed containing substantially parallel chamrels. In other preferred embodiments, the absorbent contactor is operated such that the conditions in the monolithic bed are at or near a Taylor flow or slug flow regime through said parallel chamrels.

[0037] In preferred embodiments, the absorbent solution is selected from the group consisting of: an amine solution comprising a primary amine, a secondary amine, or mixtures thereof; an amine solution comprising a polyamine or mixtures thereof; an alkali or alkaline earth metal hydroxide solution; and an alkali or alkaline earth metal carbonate solution.

[0038] In other preferred embodiments of the methods and systems herein, the absorbent solution has an absorption capacity of at least about 0.05 millimoles of CO2 absorbed per gram of absorbent solution. Preferably, the operating conditions in the absorbent contactors include a temperature from about 1° C. to about 95° C., and a pressure from about 0.5 bar to about 50 bar (absolute).

[0039] In other preferred embodiments of the methods and systems herein, the feed gas mixture further comprises at least one gas selected from the group consisting of: hydrocarbons, carbon monoxide, H2, O2, N2, and combinations thereof. In other preferred embodiments, the feed gas mixture further comprises at least one hydrocarbon selected from the group consisting of: naphtha, methane, ethane, ethene, and combinations thereof.

[0040] This disclosure also relates in part to a system for separating an acid gas component from a gas mixture, such system comprising at least one ejector venturi nozzle in flow communication with at least one absorbent contactor.

[0041] This disclosure further relates in part to a system for separating an acid gas component from a gas mixture, such system comprising at least one liquid spray device in flow communication with at least one absorbent contactor, wherein said absorbent contactor contains one or more monolithic beds.

[0042] In an embodiment of the above system, the liquid spray device can comprise an ejector venturi nozzle. The monolithic beds can have screens or inlets suflicient to operate the flow at or near a Taylor flow or slug flow regime through said absorbent contactor. In addition, the monolithic beds can function as a coalescer and a contactor.

[0043] The systems and methods of this disclosure provide a low capital investment process for CO2 capture with absorbent solutions, e.g., amines or other solutions that can affect the absorption of CO2. The use of ejector venturi nozzles in the systems and methods of this disclosure eliminates the need for expensive fans/blowers for drafting a gas mixture, e.g., flue gas, into the absorbent contactors and to overcome the pressure drop in the contactors. The kinetic energy for overcoming the pressure drop comes from the high pressure liquid pumps, e.g., ejector venturi nozzles, which are significantly less expensive than fans/blowers. The co-current designs of the present invention also reduce the pressure drop through the systems. The systems and methods of this disclosure also reduce or eliminate the need for expensive demisters.

[0044] In addition, the absorbent contactors can have compact monoliths that operate in the Taylor flow or slug flow regime. The Taylor flow and slug flow regime monoliths have several advantages, for example, very low pressure drop, high mass transfer rates, effective demisting, and minimum backmixing of gas and liquid flows. The Taylor flow and slug flow monoliths thus further reduce the need of fans/blowers or compressors.

[0045] Further objects, features and advantages of the present disclosure will be understood by reference to the following drawings and detailed description.

Free Full Text Source: http://www.google.com/patents/about?id=VUjuAQAAEBAJ&dq=refinery+%22mass+transfer%22

Hydrocarbon Treatment Process

PATENT

Hydrocarbon Treatment Process

United States Patent Application 20110163008

Inventors:

Zhang, Tiejun (Bellaire, TX, US)

Hardy, Michael K. (Humble, TX, US)

Turner, Keith V. (LaPorte, TX, US)

Bincaz, Ignacio C. (Houston, TX, US)

Varadi, Tom (Houston, TX, US)

Application Number: 13/017861

Publication Date: 07/07/2011

Assignee: MERICHEM COMPANY (HOUSTON, TX, US)

FIELD OF INVENTION

The invention relates to a method for treating liquid hydrocarbons in order to convert acidic impurities, such as mercaptans, to less odorous sulfur compounds.

More specifically these impurities are oxidized to disulfide oils by contacting the hydrocarbon in the presence of oxygen with an aqueous treatment solution comprising a polyvalent chelated metal catalyst, an alcohol and an alkali metal hydroxide. An especially preferred treatment solution also includes a carboxylic acid.

BACKGROUND

The treatment of liquid hydrocarbons containing undesirable acidic species such as mercaptans is known and can be performed using either an extraction or a conversion process. The conversion processes are known as “sweetening” processes where an aqueous solution containing a mixture of an alkali metal hydroxide, such as sodium hydroxide, and a chelated metal catalyst is contacted with a hydrocarbon stream in the presence of an oxygen containing gas. An oxidation reaction occurs that converts the mercaptans to disulfide oils, which remain in the hydrocarbon phase during a subsequent step to separate the hydrocarbon from the aqueous solution. These sweetening processes work effectively on light hydrocarbon feeds with light mercaptan impurities.

The extraction processes, such as described in U.S. Pat. Nos. 6,860,999; 6,960,291; 7,014,751; and 7,029,573, requires liquid-liquid mass transfer of the mercaptans from the hydrocarbon to an aqueous solution under anaerobic conditions, i.e., in the substantial absence of added oxygen. Such processes were especially effectively for removal of high molecular weight mercaptans (C 4 and higher) that are typically contained in heavier liquid hydrocarbon feeds. The aqueous solution preferably has two phases where alkylphenols, such as cresols (in the form of the alkali metal salt), are combined with a polyvalent metal catalyst, and an alkali metal hydroxide in an aqueous extractant phase and a denser aqueous bottom phase that is substantially immiscible in the extractant. The alkylphenols were used to enhance the extraction of the heavier mercaptans. The metal catalyst is included in the solution to minimize entrainment of the aqueous solution in the treated hydrocarbon, particularly at the higher viscosities encountered at higher alkali metal hydroxide concentration. During mixing with a “sour” liquid hydrocarbon feed, the mercaptans are physically extracted (not converted) into the aqueous extractant phase, and after separation an upgraded hydrocarbon product is obtained that is substantially lower than the feed in mercaptan content. The extractant phase aqueous solution is then sent to an oxidation process where an oxygen containing gas is added and the metal catalyst present in the solution converts the mercaptans to disulfides. These alkylphenol based extraction processes are more complicated and difficult to operate principally because of the need to use a two-phase aqueous extraction solution, or a single phase compositionally located at the phase boundary between the one and two-phase regions.

There remains a need, therefore, for new hydrocarbon treatment processes that minimize operational difficulty and minimize the need for secondary processes to treat sulfur contaminants.

SUMMARY

Our invention is directed to an improved liquid hydrocarbon treatment process that combines the best of a conventional sweetening process with that of the more complicated extraction processes. Our process converts (as opposed to extracts) mercaptans including higher molecular weight mercaptans (C 4 and higher) to disulfide oils using an aqueous treatment solution and an oxidation reaction. The disulfide oils remain in the separated hydrocarbon product stream removed from the process. More specifically, our invention involves a process comprising a method for treating a hydrocarbon containing mercaptans where the liquid hydrocarbons containing mercaptans are combined with an oxygen containing gas to form a feed stream. That feed is contacted with an aqueous treatment solution comprising water, alkali metal hydroxide, a polyvalent chelated metal catalyst, and at least one alcohol, preferably having atmospheric boiling points of 100° C. to 210° C., in a contactor vessel, where the catalyst and oxygen are used to convert the mercaptans via an oxidation reaction to disulfide oils. The contacting step forms a product admixture that is directed to at least one separation zone, where an upgraded hydrocarbon stream containing the disulfide oils is separated from the admixture. The aqueous treatment solution is recirculated to treat more sour hydrocarbon, when necessary, after being replenished with make-up catalyst and/or other ingredients of the treatment solution.

In another embodiment, our invention involves a two-stage method for treating a hydrocarbon containing mercaptans, comprising, mixing a liquid hydrocarbon with air to form a first feed, then contacting the first feed in a first stage contactor with an aqueous treatment solution comprising water, alkali metal hydroxide, a chelated polyvalent metal catalyst, and at least one alcohol, preferably having atmospheric boiling points of 100° C. to 210° C. The presence of the oxygen from the air and the catalyst oxidize most of the mercaptans in the first feed to disulfide oils to form a first admixture. This admixture is then settled in a first separation zone, where an upgraded hydrocarbon stream is separated that contains the disulfide oils from the settled first admixture. The separated upgraded hydrocarbon stream is then mixed with additional air to form a second feed. This second feed is further contacted in a second stage contactor with a second stream of the aqueous treatment solution to oxidize any remaining mercaptans to disulfide oils to form a second admixture. The second admixture is settled in a second separation zone, where a second upgraded hydrocarbon stream containing the disulfide oils is separated and removed from the process as a product stream. Similar steps may be repeated for the third and fourth stages, if needed.

Preferably, the contacting steps are performed using a contactor that reduces aqueous phase entrainment. Such contactors are configured to cause little or no agitation. One such contacting method employs a mass transfer apparatus comprising substantially continuous elongate fibers mounted in a shroud. The fibers are preferentially wetted by the aqueous treatment solution, and consequently present a large surface area to the hydrocarbon without substantial dispersion of the aqueous phase in the hydrocarbon.

The catalyst composition of our invention is preferably a liquid chelated polyvalent metal catalyst solution. Polyvalent catalysts include, but are not limited to, metal phthalocyanines, wherein the metal cation is selected from the group consisting of manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), ruthenium (Ru), rodium (Rh), palladium (Pd), silver (Ag) etc. Catalyst concentration is from about 10 to about 10,000 ppm, preferably from about 20 to about 4000 ppm. The particular catalyst selected may be included during preparation of the treatment solution and/or later added to the solution at the place of its use.

The aqueous treatment solution of this invention also includes one or more alcohols that have atmospheric boiling points of from 80° C. to 225° C. These alcohols include, but are not limited to, methanol, ethanol, 1-propanol, 2-propanol, 2-methyl-1 propanol, 2-methyl-2-butanol, cyclohexanol, phenol, cresols, xylenols, hydroquinone, resorcinol, catechol, benzyl alcohol, ethylene glycol, propylene glycol. When mixed with an alkali metal hydroxide, an alkali metal salt of the alcohol is formed, preferably in a concentration of from about 5 to about 40 wt %, most preferably from about 10 to about 35 wt %. One type of preferred alcohol is an aromatic alcohol, which are compounds represented by a general formula of aryl-OH. The aryl can be phenyl, thiophenyl, indolyl, tolyl, xylyl, and alike. Preferred aromatic alcohols include phenol, cresols, xylenols, methylethyl phenols, trimethyl phenols, naphthols, alkylnaphthols, thiophenols, alkylthiophenols, and similar phenolics. Non-aromatic alcohols can be primary, secondary or tertiary alcohols, including methanol, ethanol, n-propanol, iso-propanol, cyclohexanol, 2-methyl-1-propanol, 2-methyl-2-butanol. A mixture of different alcohols can also be used. The preferred alcohols have an atmospheric boiling point of from about 100° C. to about 210° C. The preferred alkali metal salts of alcohol include, but are not limited to, potassium cyclohexoxide, potassium iso-propoxide, dipotassium propylene glycoxide, potassium cresylates and mixtures thereof.

In a most preferred treatment solution formulation, one or more carboxylic acids are included. Such acids include, but are not limited to, fatty acids, naphthenic acids, amino acids, keto acids, alpha hydroxy acids, dicarboxylic acids, and tricarboxylic acids. These acids also react with the alkali metal hydroxides to produce their alkali metal salts in concentrations from about 0 to about 40 wt %, preferably from about 5 to about 25 wt %. In general, the carboxylic acids can include alkanoic acids and naphthenic acids, where the alkanoic acids are represented by R—COOH, where R is a hydrogen or an alkyl group ranging from CH3- (i.e. acetic acid) to CH3(CH2)18- (i.e. arachidic acid). Naphthenic acids are a mixture of multiple cyclopentyl and cyclohexyl carboxylic acids with their main fractions preferably having a carbon backbone of 9 to 20 carbons. A mixture of multiple carboxylic acid compounds can also be used as part of the treatment solution.

The aqueous treatment solution of this invention contains an alkali metal hydroxide selected from lithium hydroxide (LiOH), sodium hydroxide (NaOH), potassium hydroxide (KOH), rubidium hydroxide (RbOH), and cesium hydroxide (CsOH). The alkali metal hydroxide is present at a concentration that is more than sufficient to ensure all alcohols and carboxylic acids to form their corresponding alkali metal salts. Sodium hydroxide and especially potassium hydroxide are preferred.

Contacting of hydrocarbon feed with the aqueous treatment solution can be accomplished by any liquid-liquid mixing device, such as packed tower, bubble tray, stirred vessel, plug flow reactor, etc. Preferably, the contacting is performed using a contactor that achieves rapid liquid-liquid mass transfer without causing difficulties in obtaining quick and clean phase separation between the hydrocarbon and the aqueous treatment solution. Such contactors are configured to cause little or no agitation and reduce entrainment of aqueous solution in the hydrocarbon. One such contacting method employs a mass transfer apparatus comprising substantially continuous elongated fibers mounted in a shroud. The fibers are preferentially wetted by the aqueous treatment solution to form a thin film on the surface of fibers, and consequently present a large surface area to the hydrocarbon without substantial dispersion of the aqueous phase in the hydrocarbon. The rapid liquid-liquid mass transfer is enabled by both the large surface area and the functionality of the aqueous solution, which in turn enables the mercaptans to be transferred from the hydrocarbon to contacting with the thin film of the aqueous treatment solution. As mentioned earlier, two or more stages of contacting with an aqueous treatment solution may be adopted to achieve a greater extent of treating efficiency.

Any number of hydrocarbon feeds with boiling point up to about 350° C. can be treated in our process using our aqueous treatment solution, including, but not limited to, kerosene, jet fuel, diesel, light and heavy naphtha. Other feedstocks may include straight run or cracked or selectively hydrotreated, LPG, naphtha, crude, crude condensates, and the like materials. Still another possible feedstock that can be used in the process of our invention would include crude oil, ranging from raw crude oil (i.e., untreated and straight out of ground) to partially or fully treated crudes that have been desalted and/or dewatered and/or de-odorized and mixtures of these. These so-called pipeline-ready crudes or refinery ready crude oil at the end of pipeline transportation can be used in our process as the liquid hydrocarbon feed. By the method of our invention, mercaptans in crude oil with 95 wt % boiling points of up to 600° C. are converted into disulfide oils, prior to any fractionation.

These and other embodiments will become more apparent from the detail description of the preferred embodiment contained below.

Free Full Text Source: http://www.freepatentsonline.com/y2011/0163008.html

Hydrodynamic Characteristic Study of a Three Phase Co-current Trickle-bed Reactor: CFD analysis

THESIS

Hydrodynamic Characteristic Study of a Three Phase Co-current Trickle-bed Reactor: CFD analysis

Meher, Bidhu Bhusan (2011)

A thesis submitted in partial fulfillment of the requirements for the degree of Bachelor of Technology In Chemical Engineering

Department Of Chemical Engineering, National Institute Of Technology, Rourkela, Orissa -769 008, India

Abstract

Trickle-bed has been extensively used in petrochemical and refinery process since it provides flexibility and simplicity of operation as well as high throughputs. The basic parameter for design, scale-up and operations of a trickle bed reactor are the pressure gradient and liquid saturation. Knowledge of these hydrodynamics parameters and prevailing flow regime is essential for design and performance evaluation of the reactor. However, the hydrodynamics of a trickle bed reactor involve complex interaction of gas and liquid phase with packed solids which is very difficult to understand. Many computational models have been developed and extensive CFD study of hydrodynamics parameters has been done in the last few decades to understand the behaviour of the trickle bed reactor.

In the present work an attempt has been made to study the hydrodynamics of a co-current gas-liquid-solid trickle bed reactor using FLUENT 6.3.26.

CFD simulations has been done using Eulerian-Eulerian approach for a trickle bed system with column of height 1 m and diameter 0.194 m containing glass beads of diameter 6mm as solid packing. GAMBIT 2.3.16 has been used to generate a 2D coarse grid. The phase holdup and pressure drop behaviours have been studied and their axial and radial distributions have been illustrated. The results show that liquid holdup increases with increase in liquid velocity and decrease with increase in gas velocity. The trend is reverse for gas holdup i.e. it increases with increase in gas velocity and decrease with increase in liquid velocity. Pressure drop increases with increase in both gas and liquid velocity. Quantification of this behaviour has been done. The results have been compared with previous literature data available and found to agree well.

Free Full Text Source: http://ethesis.nitrkl.ac.in/2960/

Numerical Analysis Of Heat Transfer And Fluid Flow In Heat Exchangers With Emphasis On Pin Fin Technology

THESIS

Mälardalen University Press Dissertations

No. 98

Numerical Analysis Of Heat Transfer And Fluid Flow In Heat Exchangers With Emphasis On Pin Fin Technology

Hamid Nabati (2011)

School of Sustainable Development of Society and Technology, Mälardalen University

Abstract

Despite the existence of well-developed theoretical models for different heat transfer mechanisms, the expanding need for industrial applications requiring the design and optimization of heat exchangers has created a solid demand for experimental work and effort. This thesis concerns the use of numerical approaches to analyze and optimize fluid flow and heat transfer in power generation industry, with emphasis on pin fin technology.

The research begins with an investigation of flow and heat transfer in pin finned surfaces. Different pin fins shapes with various flow boundaries were studied, and thermal and hydraulic performances were investigated. The impact of parameters such as inlet boundary conditions, pin fin shapes, and duct cross-section characteristics on both flow and heat transfer were examined. Two important applications in power generation industry were considered for this study: power transformer cooling, and condenser for CO2 capturing application in oxy-fuel power plants. Available experimental data and correlations in the literature have been used for models validation. For each case, a model based on current configuration was built and verified, and was then used for optimization and new design suggestions. All numerical modeling was performed using commercial CFD software. A basic condenser design was suggested and examined, supplemented by the use of pin fin technology to influence the condensation rate of water vapour from a CO2/H2O flue gas flow. Moreover an extensive review of numerical modeling approaches concerning this condensation issue was conducted and presented.

The analysis results show that the drop-shaped pin fin configuration has heat transfer rates approximating those of the circular pin configuration, and the drop-shaped pressure losses are less than one third those of the circular. Results for the power transformer cooling system show those geometrical defects in the existing system are easily found using modeling. Also, it was found that the installation of pin fins in an internal cooling passage can have the same effect as doubling the radiator’s height, which means a more compact cooling system could be designed.

Results show that a condensation model based on boundary layer theory gives a close value to experimental correlations. It was shown that the heat transfer coefficient decreases due to an increase in CO2 mass fraction for a constant wall temperature, resulting from a higher resistance to diffusion between the flue gas and the condensing boundary layer. It was found that the heat transfer rate sensitivity to inlet temperatures and velocity values decreased when these parameters increased. The application of numerical methods concerning the condensation process for CO2 capturing required significant effort and running time as the complexity of multiphase flow was involved. Also data validation for the CO2/H2O condenser was challenging since this is quite a new application and less experimental data (and theoretical correlations) exist. However, it is shown that models based on numerical approaches are capable of predicting trends in the condensation process as well as the effect of the non-condensable CO2 presence in the flue gas.

The resulting data, conclusions, applied methodology can be applied to the design and optimization of similar industrial heat exchangers, such as oil coolers which are currently working at low efficiency levels. It can also be used in the design of electronic components, turbine blade cooling, or in other design applications requiring high heat flux dissipation. Finally, the finding on water vapour condensation from a binary mixture gas can be referenced for further research and development in this field.

Free Full Text Source: http://mdh.diva-portal.org/smash/get/diva2:407550/FULLTEXT01

Selection and performance comparison of jet fuel surrogates for autothermal reforming

Fuel, Volume 90, Issue 4, April 2011, Pages 1439-1448

Selection and performance comparison of jet fuel surrogates for autothermal reforming

Terry G. DuBois (a), Sen Nieh (b)

terry.dubois@us.army.mil

a US Army Research, Development and Engineering Command, 10125 Gratiot Road, Fort Belvoir, VA 22060-5816, United States

b The Catholic University of America, Department of Mechanical Engineering, 620 Michigan Avenue, NE Washington, DC 20064, United States

Abstract

Reports investigation of three fuel mixtures as possible surrogates for low-sulfur JP-8.

Fuel mixtures were chosen based on a desire to match hydrocarbon chemical composition classes found in real jet fuels. The surrogate fuels selected consisted of single, binary and tertiary-component mixtures of n-dodecane, decalin and toluene in liquid volume ratios of 10:0:0, 9:1:0 and 7:1:2. The hydrocarbon components selected represented the largest chemical classes within JP-8 of normal paraffin, cyclo-paraffin and aromatic. For all fuels investigated fuel conversion of greater than 96% could be achieved. The three-component mixture of n-dodecane/decalin/toluene provided the best correlation to JP-8 and appears to be a good three-component surrogate fuel.

Full Text Source (Subscription or Fee): http://www.sciencedirect.com/science/article/pii/S0016236110007003

Numerical Simulation of Gasoline Blending with Two Different Mixing Systems

Advanced Materials Research (Volumes 317 - 319) Pages 2107-2112

Numerical Simulation of Gasoline Blending with Two Different Mixing Systems

Song Ying Chen, Fu Chao Xie, Jun Jie Mao

School of Mechanical Engineering, Shandong University, Jinan, Shandong, P.R. China

Abstract

Using two different mixing systems, Rotary Jet Mixing (RJM) system and side-entering agitator, two kinds of three-dimensional gasoline components mixing models are established.

The incompressible Reynolds equation is selected as the momentum equation and the algorithm of SIMPLE is used to simulate the jet facility. To get the mixing time, moving mesh and the standard k-e turbulent model has been employed in the multiphase unsteady flow. The results show that the dead areas of RJM are less than side-entering agitator, and the mixing effects are much better.

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Material Transfer Efficiency In The Multistage Packed Distillation And Absorption Columns

Petroleum & Coal 53 (3) 194-205, 2011

Material Transfer Efficiency In The Multistage Packed Distillation And Absorption Columns

Tatjana. N. Mosorinac 1, Jelena J. Djurovic 2 , Jelenka B. Savkovic-Stevanovic 2

tanjadexter@yahoo.com

savkovic@tmf.bg.ac.rs

djurovicj@tmf.bg.ac.rs

1 Oil Refinery, Pancevo, Spoljnostarcevacka bb, Serbia

2 Faculty of Technology and Metallurgy, Belgrade University, Karnegijeva 4,11000 Belgrade, Serbia

Abstract

Reports investigation of material transfer efficiency by height transfer units and height of equivalent theoretical plate.

Several correlation models are studied.  Overall and individual height of transfer units are examined. Based on correlation models of the individual phase material transfer units for the gas and the liquid phases the overall material transfer units are determined. The models are tested with various systems. The various models are used for the prediction of height of transfer units and height of equivalent theoretical plate in packed columns. Results show efficiency of material transfer and it using for column design and operation. These results can be used for packing efficiency determination. 

Free Full Text Source: http://www.vurup.sk/sites/default/files/downloads/pc_3_2011_savkovic_124_0.pdf

Application of artificial neural networks for simulation of experimental CO2 absorption data in a packed column

Journal of Natural Gas Science and Engineering, Volume 3, Issue 3, July 2011, Pages 518-529

Application of artificial neural networks for simulation of experimental CO2 absorption data in a packed column

A. Shahsavand, F. Derakhshan Fard, F. Sotoudeh

shahsavand@um.ac.ir

Department of Chemical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Islamic Republic of Iran

Abstract

By means of several sets of experimental data collected from a pilot scale packed absorption column, the generalization performance of the Back Propagation Multi-Layer Perceptron (BPMLP) and the Radial Basis Function (RBF) neural networks were compared.

Simulation results indicated that the RBF networks can perform more adequately than the MLP networks for filtering the noise (measurement errors) and capturing the true underlying trend, essential for a reliable generalization performance.

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Simulation of Hydrodesulfurization Trickle Bed Reactor

Chemical Product and Process Modeling Vol. 6 (2011) / Issue 1 / Article 7

Simulation of Hydrodesulfurization Trickle Bed Reactor

Hadi F. Farahani, Iran University of Science and Technology

Shahrokh Shahhosseini, Iran University of Science and Technology

Abstract

The existence of sulfur in crude oil and petroleum fractions poses a multitude of threats to the environment and to process equipment. Elimination of these compounds from petroleum cuts has been studied extensively.

The process of hydrodesulfurization of dibenzothiophene is discussed and nonisothermal heterogeneous modeling and simulation of the three-stage trickle bed reactor is performed. The catalyst, used in this operation, is CoMo/Al2O3. A kinetic equation, based on the Langmuir-Hingshelwood method of rate determination is incorporated into the model.  Simulation results demonstrate sulfur conversion of 99% in the final product and good agreement between the simulation results and the experimental data.

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Electrochemical treatment of petroleum refinery wastewater with three-dimensional multi-phase electrode

Desalination, Volume 276, Issues 1-3, 2 August 2011, Pages 397-402

Electrochemical treatment of petroleum refinery wastewater with three-dimensional multi-phase electrode

Long Yan (a, b, c), Hongzhu Ma (a, c), Bo Wang (a, c), Yufei Wang (b), Yashao Chen (a, c)

hxmachem@snnu.edu.cn

a Institute of Energy Chemistry, School of Chemistry and Materials Science, Shaanxi Normal University, Xi'an 710062, China

b School of Chemistry and Chemical Engineering, Yulin University, Yulin 719000, China

c Key Laboratory of Applied Surface and Colloid Chemistry, Shaanxi Normal University, Ministry of Education, Xi'an 710062, China

Abstract

Petroleum refinery wastewater was treated by an electrochemical process with three-dimensional multi-phase electrode, which introduced Fe particle and air into a traditional two-dimensional reactor.

Authors investigated the effect of Fe particle and air on the electrochemical process, and the optimal experimental conditions including initial pH, cell voltage. Results demonstrate that the effluent with a satisfied COD removal efficiency (92.8%) and low salinity (84 µS cm-1) was obtained when the initial pH was 6.5, cell voltage was 12 V and fine Fe particle was introduced.  Results suggest that the electrochemical system with three-dimensional multi-phase electrode was an effective approach to treat petroleum refinery wastewater.

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Hydrodynamics On Chemical Looping Combustion Using Multiphase Cfd With Kinetic Theory Of Granular Flow

The 13th International Conference on Fluidization - New Paradigm in Fluidization Engineering, May 16-21, 2010 - Hotel Hyundai, Gyeong-ju, Korea

Hydrodynamics On Chemical Looping Combustion Using Multiphase Cfd With Kinetic Theory Of Granular Flow

Jonghwun Jung, POSCO

Isaac K. Gamwoy, U.S. Department of Energy

Abstract

The fundamental knowledge of multiphase reactive hydrodynamics of the gas solid flow is essential for the design, optimization, and operation of industrial reactors. The multiphase computational fluid dynamics (CFD) model with the kinetic theory of granular flow, MFIX, developed earlier at the National Energy Technology Laboratory have been adapted to describe a fuel reactor of chemical looping combustion (CLC) processes.

The chemical kinetics and mass transfer in the fuel reactor have been developed, where the reduction reaction is the first order of methane gas and the oxygen in metal oxygen carriers transfer to gas phase. The fuel conversion rate can be varied by reaction temperature, initial static bed height, and inlet velocity of fuel. The reaction temperature in an earlier work was an important factor for the efficient design of the fuel reactor. In this study, the increase of the initial static bed height for catalyst in the fuel reactor results in the enhancement of the fuel conversion rate at a constant temperature. Successful development of validated CLC models will provide the needed base for the development of such a technology.

Free Full Text Source: http://services.bepress.com/eci/fluidization_xiii/52/

Treatment of petroleum refinery wastewater by ultrasound-dispersed nanoscale zero-valent iron particles

Ultrasonics Sonochemistry, Volume 18, Issue 5, September 2011, Pages 1138-1142

Treatment of petroleum refinery wastewater by ultrasound-dispersed nanoscale zero-valent iron particles

Qusay Jaffer Rasheed (a), Kannaiyan Pandian (b), Karuppan Muthukumar (a)

muthukumar@annauniv.edu

a Department of Chemical Engineering, A.C. Tech. Campus, Anna University, Chennai 600 025, India

b Department of Inorganic Chemistry, University of Madras, Guindy Campus, Chennai 600 025, India

Abstract

Petroleum refineries release wastewater rich in organic pollutants and difficult to treat.

Study presents the treatment of petroleum refinery wastewater using nanoscale zero valent iron (NZVI) in the presence of ultrasonication.

NZVI characteristics were analyzed using SEM and XRD.  Results indicate that a dosage of 0.15 g/l and an initial pH are optimum for the effective degradation of effluents. The degradation data were found to follow first order kinetics. Results suggest that using NZVI in combination with ultrasonication is an efficient method for the treatment of petroleum refinery wastewater.

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An Economical Comparative Study of Different Methods for Decrease Cooling Towers Makeup Cost in Oil Refineries

World Applied Sciences Journal 12 (7): 988-998, 2011

An Economical Comparative Study of Different Methods for Decrease Cooling Towers Makeup Cost in Oil Refineries

1 R. Hosseinzadeh Hesas, 2 A.H. Tarighaleslamir, 3 M.R. Omidkhah, 1 M. Sharifzadeh Baei

1 Department of Chemical Engineering, Islamic Azad University, Ayatollah Amoli Branch, Amol, Iran

2 Chemical Engineering Faculty, Islamic Azad University, Mahshahr Branch, Iran

3 Department of Chemical Engineering, Tarbiat Modares University, Iran

Abstract:

Reviews cases of water and energy losses in cooling towers of oil refineries.

Cooling towers are the equipment to set the temperature cooling water service of integrated oil, gas and petrochemical used. In this equipment, heat and mass transfer occur simultaneously to cool water in the vicinity of air. Hence, the significant transfer of air and water to create moist air from the process cycle casualties is removed. The main goal of this research is to reduce water cost of cooling water system of the oil refinery. Economic principles in order to review the definition of an objective function for a Trade-off between construction cost, installation and operation dry cooling tower and reduce the cost of wet cooling tower make-up water is more. Results obtained from studies in the sample case study objective function, the Tabriz refinery cooling towers were selected, expresses that: There is no economic justification for replacement method, also saving cost in series hybrid method is 171,600.00 US$ per year and in split method is 212,400.00 US US$ per year. Presenting the proposed method based on dry bubble temperature variations during the year can be a combination of two methods used to determine the best route in the cold months of the year (December, January and February) split method and the rest months use series method to the cost saving result is expressed 281,100.00 US$ per year. 

Free Full Text Source: http://idosi.org/wasj/wasj12(7)/13.pdf

DECAB: Process development of a phase change absorption process

Energy Procedia, Volume 4, 2011, Pages 868-875

10th International Conference on Greenhouse Gas Control Technologies

GHGT-10

DECAB: Process development of a phase change absorption process

Eva Sanchez Fernandez (a), Earl L.V. Goetheer (a)

eva.sanchezfernandez@tno.nl

a TNO Science and Industry, Leeghwaterstraat 46, 2628 CA Delft, The Netherlands

Abstract

Describes the conceptual design of a novel separation process for CO2 removal from flue gas based on precipitating solvents.

DECAB, the process described, is an enhanced CO2 absorption based on Le Chatelier’s principle. According to the principle, the reaction equilibrium can be shifted by removing one of the constituents in the reaction. Authors develop a conceptual design of the process based on literature data, thermodynamic principles and a limited number of experiments.

Free Full Text Source: http://www.sciencedirect.com/science/article/pii/S1876610211001330

Improving the mass transfer rate in G–L membrane contactors with ionic liquids as absorption medium. Recovery of propylene

Journal of Membrane Science, In Press, Corrected Proof - Note to users

Improving the mass transfer rate in G–L membrane contactors with ionic liquids as absorption medium. Recovery of propylene

Marcos Fallanza, Alfredo Ortiz, Daniel Gorri, Inmaculada Ortiz ,

ortizi@unican.es

Advanced Separation Processes Research Group, Department of Chemical Engineering and Inorganic Chemistry, University of Cantabria, Avenida de los Castros s/n, 39005 Santander, Cantabria, Spain

Abstract

The use of membrane contactors for the G–L separation of olefins by means of reactive absorption with ionic liquid silver complexes presents a great potential to intensify the conventional separation process based on cryogenic distillation.

A key issue to be addressed is the high mass transfer resistance offered by the ionic liquid that flows through the shell side of the membrane contactor. It is critically important to improve the fluid dynamics of the system in order to enhance the mass transfer rate in the liquid film. Reported  here is the analysis of the performance of a gas–liquid transverse flow membrane contactor applied to the reactive absorption of propylene in BMImBF4–Ag+ as reaction media.

Full Text Source (Subscription or Fee): http://www.sciencedirect.com/science/article/pii/S0376738811007332

Hydrodynamic and Mass Transfer Performance of Enhanced Jet Tray

Advanced Materials Research (Volumes 219 - 220) Pages 697-700

Hydrodynamic and Mass Transfer Performance of Enhanced Jet Tray

Jun Li, Lan Yi Sun, Zhan Hua Ma, Sha Xue, Yang Dong Hu

Abstract

Presents an enhanced jet tray (EJT), a new kind of tray ,in order to satisfy the revamping of refinery and chemical equipment.

Investigates the hydrodynamic and mass transfer performances of EJT and new vertical sieve tray (New VST) with air-water-oxygen system in a stainless steel column of 1200mm internal diameter. Correlations of hydrodynamic parameters such as pressure drop, weeping and entrainment of EJT are obtained. Experimental results indicate that EJT has lower pressure drop, fractional weeping, entrainment and higher efficiency compared with New VST because of its special geometry.

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Modeling of Water Contaminants Mass Transfer and Water & Wastewater Minimization in Chemical Processes

Australian Journal of Basic and Applied Sciences, 5(6): 192-200, 2011

Modeling of Water Contaminants Mass Transfer and Water & Wastewater Minimization in Chemical Processes

Afshin Razmjooie, Farhad Shahraki, Seyyed Mahmoud Musavi, Mohammad Khorram,

Department of chemical engineering, University of Sistan and Baluchestan, Zahedan

Abstract:

An introductory survey, this paper attempts to minimize the model of water consumption and wastewater production.

Mass transfer of water contaminants into fresh water and wastewater is undesirable. Although several models have been approved for this problem, their reliance on nonlinear equations leads to failure in optimization of the system.

This study solves the problem by breaking nonlinear equations of model into linear equations. It is first necessary to identify the primary contaminants and their concentration limits. The water system of a refinery was selected as a case study to test the model. Results show that fresh water consumption is reduced by 55 % and wastewater production is reduced by 10%.

Free Full Text Source: http://www.insipub.com/ajbas/2011/june-2011/192-200.pdf