Alkylation Unit Research Articles

Application of the IHMPC to an industrial process system

Abstract Abstract This paper addresses the application of a new MPC to a distillation system where isobutane and light butenes are separated from butane and heavier compounds. This system is located in the alkylation unit of an oil refinery. The MPC considered here is based on the infinite horizon MPC extended to the case where the system has stable and integrating modes. The controller is developed based on a particular state space model in the incremental form, which considers the existence of time delays. The proposed controller provides nominal stability to the closed loop system. Practical tests in a distillation system show that the performance of the new controller, which can be extended to consider robustness to model uncertainty is similar to the performance of the conventional MPC with finite prediction horizon.

A scenario-based clean gasoline production strategy for China National Petroleum Corporation

Facing increasingly strict environmental regulations on transportation fuels, China National Petroleum Corp. (CNPC), the second largest supplier of petroleum products in China, needs to upgrade its transportation fuels. Using the scenario-based analysis method, this paper analyzes how the emission related properties, including antiknock index, and sulfur, olefin, benzene and aromatics contents of gasoline produced by CNPC, vary with the change in the configuration of gasoline production units in the future 5–15 years. The results showed that for CNPC to upgrade its gasoline, the share of fluid catalytic cracking (FCC) naphtha must be reduced, but just increasing reformate or alkylate and isomerate will result in excessive increase in benzene and aromatics contents or a great loss of gasoline octane number. Therefore, CNPC should suitably control the capacity of its FCC units and increase the capacity of reformer, alkylation and isomerization units. Most importantly, CNPC should dramatically expand the capacity of its hydrotreating or non-hydrotreating gasoline upgrading units to decrease the olefin and sulfur contents in FCC gasoline that takes a dominant share of about 80% in the gasoline pool of China.

Assessment of cleaner process options: A case study from petroleum refining

AbstractAssessment of process changes to reduce, recycle or avoid wastes requires attention to systems which are broader than the immediate process; that is, it is necessary to take a life cycle perspective. Definition of the system boundary for such an assessment can be problematic in itself. A real case study is presented to illustrate the problem of assessing clean technologies: possible modifications to an alkylation unit at a UK refinery. The process uses hydrogen fluoride as alkylation catalyst, and generates fluoridic wastes which are hazardous and require treatment both on‐ and off‐site. Possible changes to avoid, reduce or enable partial recycling of the waste are identified, representing different levels of change in the process and therefore requiring assessment with different system boundaries. The different system definitions lead to differences in the ways data must be compiled for quantitative environmental life cycle assessment, and in the range of stakeholders explicitly or implicitly involved in assessing and implementing the changes. The case study demonstrates some of the less familiar challenges introduced by the “pollution prevention” or “clean technology” paradigms of chemical processing.

Benzene Reduction in a Fuels Refinery: An Unconventional Approach

The benzene content of motor-gasoline is regulated by fuel specifications that are becoming increasingly stringent. Acid catalyzed alkylation of benzene by olefins in commonly found refinery units was explored as a low cost benzene reduction strategy. Cofeeding benzene to aliphatic alkylation, etherification, and olefin oligomerization processes were evaluated. Benzene can be alkylated in a sulfuric acid-based aliphatic alkylation unit at 5 °C, but significant disruption of the aliphatic alkylation reaction occurs if the feed contains more than 3% benzene. No benzene alkylation was found during reaction at 90 °C in an acidic resin based etherification process, since the alcohol is the proton carrier. When the same process was operated as an olefin oligomerization process (no alcohol in feed), alkylation proceeded. Benzene was also successfully alkylated during H-ZSM-5 based oligomerization (180–280 °C, 4 MPa), but the pore constrained geometry of the zeolite resulted in <5% alkylation selectivity with a hexene feed. Catalysts with a more open pore structure should rather be considered for the industrial application of benzene alkylation in an oligomerization process. Alkylation of benzene by cofeeding it to a solid phosphoric acid catalyzed oligomerization process (220 °C, 3.8 MPa, and benzene to olefin ratio in the range 1:6−6:1) was successful.

Evolution of a more reliable gasket for HF alkylation units

The requirement to minimize flange face corrosion, overcome handling problems and improve sealing performance has led to the evolution of a new type of gasket for use in Hydrofluoric (HF) Alkylation Units to replace the standard spiral-wound type. The carbon steel flange face can now be protected from aggressive HF acid corrosion and the resulting iron fluoride scaling, accompanied by an increase in both the reliability and sealability of the flange joints. The benefits include a reduction of costly flange damage, potential leakage and the associated unit shutdowns required for repairs. This feature highlights the stages in the development of the new gasket design.

Synthesis of New Family of Dialkylaryl Disulfonate Gemini Anionic Surfactant

Abstract A new family of dialkylaryl disulfonate Gemini-type anionic surfactant were synthesized based on the reaction of olefin sulfonic acid (C14AOS acid) with different aromatics. New synthesis route do not require the conventional alkylation unit and strong acid catalysts, and the resulting Gemini-type anionic surfactant differ from existing products by having the sulfonyl group attached to the alkyl chain rather than the aromatic ring. To optimizing reaction condition, a reliable double-wavelength spectrophotometric method and iodine value method were employed for measurement the conversion of the aromatics. The experimental has confirmed that the reaction time and temperature are mainly the factors of the effect of conversion. Under 150°C, C14AOS acid reacts with different aromatics for 4 or 5 hours to form dialkyaryl disulfonic acid, and dialkyaryl disulfonic acid was then neutralized to dialkyaryl disulfonate Gemini-type anionic surfactant. Some surface active property has been investigated too. The critical micelle concentration of ditetradecylbenzene disulfonate, ditetradecylnaphthalene disulfonate, ditetradecylmethylnaphthalene disulfonate, ditetradecylphenanthrene disulfonate, ditetradecyldiphenylether sulfonate, ditetradecyldiphenylmethane sulfonate and ditetradecylbenzophenone sulfonate were 1.7 × 10−4, 8.082 × 10−6, 2 × 10−5, 2.158 × 10−3, 5.0 × 10−6, 1.0 × 10−5 and 1.33 × 10−5 mol l−1. Above datum showed the aromatics of the surfactant may effect on surface active property obviously. Among these, some dialkylaryl disulfonate gemini anionic surfactant have very higher surface active than conventional dodecylbenzene sulfonate and may be widely used in industry and household.

Synthesis of a novel dialkylaryl disulfonate gemini surfactant

AbstractA single‐step route was developed for synthesizing a dialkylaryl disulfonate gemini surfactant using α‐olefin sulfonic acid. The new process is very simple and effective, requiring neither the conventional alkylation unit nor strong acid catalysts. The resulting dialkylaryl disulfonica acids differ from existing products by having the sulfonyl group attached to the alkyl chain rather than the aromatic ring. To optimize the reaction conditions, a reliable double‐wavelength spectrophotometric method was studied to analyze the conversion of an aromatic (benzene or methylnaphthalene) based on the difference in ultraviolet absorption spectra between the aromatic and the corresponding dialkylaryl disulfonate. The experiments suggested that the reaction time and temperature affected the conversion and optimal condition; a reaction time of 5 h (or 4 h) and a reaction temperature of 150°C were obtained and applied to the products ditetradecylmethylnaphthalene disulfonate (DTMNDS) and ditetradecylbenzene disulfonate (DTBDS). In addition, the surface‐active properties of DTMNDS and DTBDS were investigated in detail. Their critical micelle concentrations were 2×10−5 and 1.7×10−4 mol·L−1, respectively. The data showed that the two new dialkylaryl disulfonate gemini surfactants had higher surface activities than the conventional dodecylbenzene sulfonate, suggesting they will have broad utility in industrial and household applications in the future.

Enhancement of Propylene Production in a Downer FCC Operation using a ZSM‐5 Additive

AbstractThe effects of high severity operation and ZSM‐5 addition on the FCC product yield distribution have been studied in a down‐flow reactor unit. VGO cracking at high reaction temperatures of 500–650 °C increases the yield of light olefins (propylene and butenes) with a corresponding loss in gasoline yield and increase in dry gas formation. Similar behavior is observed with the addition of 0–20 wt % ZSM‐5 additive, however, with no increase in dry gas. The combination of the two effects (high severity and ZSM‐5 addition) makes the FCC unit an excellent source of light olefins for downstream petrochemical and alkylation units. The novel process configuration increased the light olefin yield without significant loss in gasoline by suppressing thermal cracking reactions and dry gas formation.

Experience in Designing Sulfuric Acid Alkylation Units

Experience in Designing Sulfuric Acid Alkylation Units

New anionic alkylaryl surfactants based on olefin sulfonic acids

AbstractA new family of anionic surfactants has been produced by the simultaneous sulfonation and alkylation of aromatic compounds using olefin sulfonic acid(s). This new process does not require the conventional alkylation unit and the strong acid catalysts, such as AlCl3 or HF, normally used for alkylation. The resulting alkylaryl sulfonic acids differ from existing prodeucts by having the sulfonate group attached to the alkyl chain rather than the aromatic ring. This allows for further derivatization of the aromatic compounds by leaving more positions open on the ring. Aromatic compounds that lend themselves to the new process include benzene, toluene, xylene, alkylbenzenes, phenol, alkylphenols, alkoxylated phenols, alkoxylated alkylphenols, alkoxylated alkylphenol/formaldehyde resins, naphthalene, and alkylnaphthalenes. Any type of olefin that can be sulfonated can be used as the starting material. These include internal and α‐olefins, linear and branched olefins, polyolefins, and vinylidenes. Mono‐ and disulfonated compounds, as well as geminitype surfactants, are easily prepared.

CRACKER, PIPELINE DREAMS SOON REAL

BIG IS BEAUTIFUL IS HOW Rudi Schnur, senior vice president for petrochemi-cals at BASF Corp., views the world's largest single-train naphtha cracker, recently completed in Port Arthur, Texas. BASF and 40% partner Atofina Petrochemicals created their BASF Fina Petrochemicals joint venture in 1997 to build the cracker. As its operator, BASF is currently commissioning—cleaning, drying, and testing—the unit in preparation for start-up next quarter. Once the cracker is operational, BASF Fina will have invested about $1 billion to produce 2 billion lb per year of ethylene and 1.2 billion lb of propylene. Another venture between BASF, Atofina, and Shell Chemical, called Sabina Petrochemicals, will very soon start building butadiene extraction and alkylation units next door. They are scheduled to open in 2003 along with a BASF Fina metathesis-based olefins conversion unit (OCU) that will shift ethylene output at the site to 1.8 billion lb and propylene to 1.9 billion lb. LOCATED IN the heart ...

Minimum time constrained control of acid strength on a sulfuric acid alkylation unit

We detail here the controller of the acid strength that we implemented in the Elf-Antar France refinery in Feyzin (France). The control technique used is new. It relies on the flatness property of the system to solve a constrained minimum time objective as successive linear-programming problems. This controller is in full service since January 1997. We detail the control technique, including the estimation and numerical problems and then give industrial results over 6 months.

Maximization of FCC light olefins by high severity operation and ZSM-5 addition

The effects of high severity operation and ZSM-5 addition on the FCC product yield structure have been studied in a MAT unit. VGO cracking at high reaction temperatures of 500–650°C increases the yield of light olefins (propylene and butenes) with a corresponding loss in gasoline yield and increase in dry gas formation. Similar behavior is observed with the addition of 0–20 wt.% ZSM-5 additive, however, with no increase in dry gas. The combination of the two effects (high severity and ZSM-5 addition) makes the FCC unit an excellent source of light olefins for downstream petrochemical and alkylation units. A novel downer reactor FCC configuration is proposed to suppress thermal cracking reactions and dry gas formation during high severity operation.

Troubleshooting HF Alkylation Units

Good design criteria, an excellent clean-up and the best knowledge with regard to the philosophy of operation allows a fast start-up and a reduction of the time to reach the designed steady-state conditions in the alkylation units. Presented are the findings after starting-up three new alkylation units as well as the difficulties encountered and their possible solutions.

Corrosion Abatement in Sulfuric Acid Alkylation Unit Horizontal Contactors

Abstract A leak to the atmosphere in the hydraulic end cone of a horizontal contactor and the realization that basic corrosion data are not available for high-throughput process conditions in alkylation units prompted a laboratory study to develop the lacking expertise. Corrosion in the horizontal contractor of an alkylation unit was mitigated successfully by saturating fresh alkylation acid with ferrous sulfate (FeSO4).

Viscosity as the basic process control parameter in the alkylation of phenol

We have conducted experiments in a pilot alkylation unit at MASMA Scientific Research Institute for Petroleum Processing, this unit consisting of four series-connected reactors. As the alkylating agent we used a mixture of propylene trimers and tetramers. In the course of the process, we took simultaneous samples of the alkylated product at the exit from each reactor and determined the product viscosity at 50°C in a VPZh type capillary viscometer, the electrical conductivity by means of an OK-102 conductivity meter, and the dielectric constant by means of a Q-factor meter of the E9-4 type.

Interfacial Area of Dispersions of Sulfuric Acid and Hydrocarbons

Dispersions containing 10-85% H 2 SO 4 and the remainder 2,2,4-trimethylpentane (2,2,4-TMP) were investigated in a well-agitated reactor mainly at 10°C. 2,2,4-TMP degrades and isomerizes because of reactions that occur in the vicinity of the interface between the liquid phases. The interfacial areas of these dispersions were calculated by comparing the kinetics of these reactions in the dispersions with those in a cell (whose cross-sectional area equals the interfacial area between the two phases). Some area measurements were also made for nonreacting dispersions in an image analysis system. The interfacial areas were highly dependent on the volume percent acid in the dispersions, acid composition, agitation rate, and temperature. For acid-continuous dispersions, the maximum interfacial area occurred at about 75% acid by volume. To model the area data, the following physical properties were measured: acid viscosity, acid density, and interfacial tension of acid-hydrocarbon interfaces. The model developed may be applicable to dispersions in alkylation reactors. Methods of improving the operation and design of alkylation units are proposed.

95/00213 Degradation and isomerization of isoparaffins while in contact with sulfuric acid in alkylation units: Chemistry and reaction kinetics

The densities and surface tensions of [Bmim][TFO]/H2SO4, [Hmim][TFO]/H2SO4 and [Omim][TFO]/H2SO4 binary mixtures were measured by pycnometer and Wilhelmy plate method respectively. The results show that densities and surface tensions of the mixtures decreased monotonously with increasing temperatures and increasing ionic liquid (IL) molar fraction. IL with longer alkyl side-chain length brings a lower density and a smaller surface tension to the ILs/H2SO4 binary mixtures. The densities and surface tensions of the mixtures are fitted well by Jouyban–Acree (JAM) model and LWW model respectively. Redlich−Kister (R–K) equation and modified Redlich−Kister (R–K) equation describe the excess molar volumes and excess surface tensions of the mixtures well respectively. Adding a small amount of ILs (xIL < 0.1) into sulfuric acid brings an obvious decrease to the density and the surface tension. The results imply that the densities and surface tensions of ILs/H2SO4 binary mixtures can be modulated by changing the IL dosage or tailoring the IL structure.

Degradation and Isomerization of Isoparaffins while in Contact with Sulfuric Acid in Alkylation Units: chemistry and Reaction Kinetics

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDegradation and Isomerization of Isoparaffins while in Contact with Sulfuric Acid in Alkylation Units: chemistry and Reaction KineticsDavid J. am Ende and Lyle F. AlbrightCite this: Ind. Eng. Chem. Res. 1994, 33, 4, 840–848Publication Date (Print):April 1, 1994Publication History Published online1 May 2002Published inissue 1 April 1994https://doi.org/10.1021/ie00028a009RIGHTS & PERMISSIONSArticle Views232Altmetric-Citations16LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts

Frequency estimates for transport‐related hydrofluoric and sulfuric acid release scenarios

AbstractAn analysis was performed to predict the frequency of release associated with transportation scenarios for four refineries and a chemical plant in the South Coast Basin using hydrofluoric acid (HF) in the alkylation process/ chemical process. The analysis considers two settings. The first is the set of ongoing HF transportation scenarios, and the second is a projected set of HF and sulfuric acid transportation scenarios if the HF alkylation units of the refineries are replaced by sulfuric acid alkylation units.