Oil Refinery Process Research Articles

Catalyzing mesophase formation by transition metals

In this work, environmentally-benign mesophase pitches were prepared from feed stocks obtained from two different petroleum refinery processes namely ‘clarified oil’ (CLO) from fluid catalytic cracking (FCC) unit of Fuel Block and ‘heavy extract’ (HE) from solvent extraction unit of Lube Block by giving thermal treatment at 370°C. The effect of thermal treatment and role of transition metal catalysts on development of mesophase in petroleum feed stocks have been discussed in this paper. Mesophase formation behavior in the feed stocks and microstructures of mesophase pitches produced were investigated by optical microscopic imaging. It was observed that mesophase formation in the feed stocks was slow under the influence of thermal soaking only. The addition of divalent transition metal salts of cobalt and nickel during thermal soaking accelerates the mesophase formation in pitches. The addition of 3wt% of cobalt catalyst enhanced the mesophase content (MC) from below countable limit (BCL) to 16vol% in CLO pitch and from 10 to 40vol% in HE pitch and also reduced thermal soaking time in both the cases. The 3wt% of nickel catalyst also showed similar behaviour and enhanced the mesophase content (MC) from below countable limit (BCL) to 13vol% in CLO pitch and from 10 to 18vol% in HE pitch in shorter thermal soaking time. The study further revealed that cobalt catalyst exhibited greater catalytic activity for mesophase formation than nickel catalyst. These catalysts also help to increase the yield of mesophase pitches. Pitch yield in case of uncatalysed pitch CLO-0-0 is 11.88wt% which increases to 16.22wt% (CLO-Co-3) and 15.08wt% (CLO-Ni-3), whereas in case of heavy extract pitch yield increases from 24.41wt% (HE-0-0) to 24.79wt% (HE-Co-3) and 26.16wt% (HE-Ni-3) by the addition of Co and Ni catalysts. The effect of transition metal catalysts on mesophase pitch properties such as elemental analyses (CHNS), softening point (SP), coking value (CV), toluene insolubles (TI) and quinoline insolubles (QI) have also been studied. The mesophase pitches were also characterized using NMR spectroscopy, FT-IR spectroscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy, X-ray diffraction (XRD) and thermogravimetric analyses (TG/DTG).

A Method for Automatic Detection of Controller Tuning Issues

A modern complex industrial process, such as petroleum refinery, petrochemical plant, pulp & paper process and power plant, usually include hundreds or thousands of control loops. It is a well-known fact that many controllers in a process plant are not tuned properly (Desborough and Miller, 2001). Badly tuned controllers would lead to loss in production as well as quality (Bialkowski, 1993; Ender, 1993). Therefore, it is necessary to detect the controllers that are poorly tuned and diagnose their behavior as sluggish or aggressive (oscillatory) and make the operators aware of it so that appropriate retuning actions can be initiated. There are methods in the literature for diagnosing aggressive (Thornhill and Horch, 2007) or sluggish (Hugglund, 1995; Kuehl and Horch, 2005) controller behavior. However, each of these methods has its own limitations and none of them addresses the improper controller tuning issues (sluggish and aggressive behavior) in a unified framework. Here, we have proposed a non-invasive method to automatically detect the badly tuned controller and identify its tuning issue as sluggish or aggressive directly from the routine plant operation data. The effectiveness of the proposed method is demonstrated on both simulated as well as industrial control loop examples.

High‐Resolution Single‐Molecule Fluorescence Imaging of Zeolite Aggregates within Real‐Life Fluid Catalytic Cracking Particles

AbstractFluid catalytic cracking (FCC) is a major process in oil refineries to produce gasoline and base chemicals from crude oil fractions. The spatial distribution and acidity of zeolite aggregates embedded within the 50–150 μm‐sized FCC spheres heavily influence their catalytic performance. Single‐molecule fluorescence‐based imaging methods, namely nanometer accuracy by stochastic chemical reactions (NASCA) and super‐resolution optical fluctuation imaging (SOFI) were used to study the catalytic activity of sub‐micrometer zeolite ZSM‐5 domains within real‐life FCC catalyst particles. The formation of fluorescent product molecules taking place at Brønsted acid sites was monitored with single turnover sensitivity and high spatiotemporal resolution, providing detailed insight in dispersion and catalytic activity of zeolite ZSM‐5 aggregates. The results point towards substantial differences in turnover frequencies between the zeolite aggregates, revealing significant intraparticle heterogeneities in Brønsted reactivity.

Statistical method for the fatigue life estimation of coke drums

Coke drums are vertical pressure vessels used in the delayed coking process in petroleum refineries. They are operated under severe thermal–mechanical conditions by cyclic heating and quenching processes, which make them susceptible to damage. To accurately predict the safety lives of coke drums, a statistical fatigue life evaluation method is proposed in this study. To develop this method, thermal–mechanical cyclic fatigue tests of coke drum materials were firstly conducted to obtain strain-life curves, then simplified thermal-elasto-plastic analytical models were developed to calculate maximum equivalent strain amplitudes for global cycling and local hot and cold spot events. Statistical analysis of temperature data on a coke drum shell was also performed to get the probability distributions of the hot and cold spot events. The final statistical fatigue life evaluation model is based on Palmgren-Miner’s damage accumulation rule. The fatigue life of a selected coke drum is hereafter estimated according to the maximum equivalent strain amplitudes in both cladding and base plate. The predicted fatigue life of the coke drum is about 5000 operation cycles, which is within the range of operation cycles to the first-through-thickness crack in coke drums, reported by American Petroleum Institute (API) survey. The evaluation methodology developed in this study can be employed to predict the safety lives of coke drums and is expected to be helpful for the design and maintenance of the equipment.

Hydrodesulfurization enhancement of heavy and light S-hydrocarbons on NiMo/HMS catalysts modified with Al and P

Deep hydrodesulfurization (HDS) of oil fractions is a key process in petroleum refineries due to the increasing demand for S-free diesel and gasoline fractions. In this work, a series of NiMo catalysts supported on Al- and P-modified HMS mesoporous substrate were tested in the HDS of thiophene and 4,6-dimethyldibenzothiophene (4,6-DMDBT) to evaluate the effect of Al and P additives on the catalyst response in HDS reactions (thiophene at 1bar and 4,6-DMDBT at 5.5MPa). The catalysts were characterized by a variety of techniques (XRD, N2 adsorption–desorption, TPR, TPS, FT-IR of adsorbed pyridine, UV–vis and H2 chemisorption). NiMo/Al-HMS-P catalyst containing 1.0wt.% of P exhibited the best performance in both HDS reactions as a consequence of the proper balance between the active phase dispersion and the largest hydrogenation ability among the studied catalysts. The 4,6-DMDBT HDS reaction proceeded toward direct desulfurization (DDS) and hydrogenation (HYD) reaction routes. Concerning the HDS of thiophene, the increase of the catalyst acidity led to the formation of butadiene and diminished the hydrogenation of olefins (formation of butane). At the reaction temperature of 320°C, the NiMo/Al-HMS-P1.0 catalyst exhibited the highest activity and the lowest butane formation among the catalysts studied. The isomerization of olefins in the thiophene HDS reaction did not occur, in line with the observed absence of isomerization in the 4,6-DMDBT HDS reaction.

Presenting of failure probability assessment pattern by FTA in Fuzzy logic (case study: Distillation tower unit of oil refinery process)

Fault Tree Analysis (FTA) is an appropriate tool for failure analysis and failure rate determination. In some cases, it is difficult or even impossible to determine the relationships among the main factors of system failure. Moreover manual calculation of subsystem failure probability rate is hard or impossible. Also, in some situation for the lack of information about the process and main event obtained results are uncertain. This is where fuzzy tool can be best exploited. In this study with matching of FTA and fuzzy for determination of failure probability, we can obtain accurate and certain results. Refinery industry is one of the most dangerous industries in Iran and in some places it is located near the crowded cities. The distillation unit, as one of the most dangerous units in this industry, was evaluated by Fuzzy Fault tree analysis (FFTA) tool. The findings of this study can be used in risk management method.

Thermal Conductivity of Transformer Oil From 253 K to 363 K

Transport properties of transformer oil are important parameters for electric equipment designing. In this work, thermal conductivity was measured from 253 K to 363 K by single transient hot-wire technique. And influence of transformer oil's thermal conductivity was investigated. It is found that the thermal conductivity decreases linearly with increasing temperature. When different oils are mixed together, the thermal conductivity shows additive property. For different oils with about the same viscosities, their thermal conductivities are directly related to alkane and aromatic content, while for oils with the same oil source, oil refinery process, similar carbon type, and different boiling range, the thermal conductivity increases with its viscosity.

Fatigue behaviour of coke drum materials under thermal-mechanical cyclic loading

Coke drums are vertical pressure vessels used in the delayed coking process in petroleum refineries. Significant temperature variation during the delayed coking process causes damage in coke drums in the form of bulging and cracking. There were some studies on the fatigue life estimation for the coke drums, but most of them were based on strain-fatigue life curves at constant temperatures, which do not consider simultaneous cyclic temperature and mechanical loading conditions. In this study, a fatigue testing system is successfully developed to allow performing thermal-mechanical fatigue (TMF) test similar to the coke drum loading condition. Two commonly used base and one clad materials of coke drums are then experimentally investigated. In addition, a comparative study between isothermal and TMF lives of these materials is conducted. The experimental findings lead to better understanding of the damage mechanisms occurring in coke drums and more accurate prediction of fatigue life of coke drum materials.

Short Duration Overheating in a Steam Reformer: Consequences to the Catalyst Tubes

Catalytic reformer furnaces (steam reformers) produce hydrogen-rich gas by cracking natural gas or naphtha in the presence of steam and a catalyst. This hydrogen-rich gas is a raw material in different petrochemical processes and is also used in the hydrotreating process in petroleum refineries. Unexpected operational failures of these reformers can cause major economic losses. These failures can happen when the feedstock flow, that cools the catalyst tubes located in the radiation chamber, is unintentionally restricted without also reducing the fuel burn rate. The thermal imbalance created in this situation can quickly produce a temperature surge large enough to cause the failure of the catalyst tubes through formation of large longitudinal cracks. This paper discusses a case of a temperature surge followed by the rupture of 13 catalyst tubes. The data show that the catalyst tubes that survived the event may retain sufficient structural integrity to return to normal operation.

SCADA system for oil refinery control

A Supervisory Control and Data Acquisition (SCADA)/Programmable Logic Control (PLC) system is always used to control small industries like water treatment stations; electric power stations and irrigation systems. Oil and gas refineries generally rely on a Distributed Control System (DCS) to provide all process and equipment control functionality. In this paper, a SCADA/PLC system is used to control a whole oil refinery instead of the conventional control through DCS. The design and specific implementation method of a SCADA/PLC real system in an oil refinery process is introduced. It consists of four main units: a crude oil storage unit, a crude oil pretreatment unit, a distillation unit and products storage/dispatch unit. The output products from crude oil refinery process are Liquefied Petroleum Gas (LPG), Naphtha, Gasoline, Kerosene and Diesel that have a great usage in our daily life. The reason for using the Multipoint Interface/Decentralized Peripherals (MPI/DP) connection in main control loop instead of Ethernet connection is that MPI/DP speed is 185kbps and Ethernet connection speed is 10/100kbps, which increases the speed of transfer data through the system. Displacer level transmitters and automatic servo level gauging transmitters are used for measuring levels in the crude oil refinery process. Also differential pressure flow transmitters are used for measuring flow rate. Temperature transmitters with thermocouple temperature elements are used for temperature control. Constructing a highly stable and reliable SCADA/PLC system instead of DCS must realize automatic management and control of oil refinery process in order to avoid the waste of manpower, physical resources, and also to increase the safety of workers.

Simulation, Sensitivity Analysis and Optimization of an Industrial Continuous Catalytic Naphtha Reforming process

Continuous catalytic regeneration (CCR) is a key process in petroleum refineries to produce high octane gasoline. In this article, a commercial scale CCR plant with the nominal capacity of 22000 bbl/day was simulated using Ref-sim module and Petro-sim simulator. The validity of this plant wide simulator was evaluated by actual test runs obtained during 6 months of operation. Simulation results showed that the AAD% of momentous output variables i.e. outlet temperature of reactors, product volume yield, product RON, H 2 purity of recycle gas and coke deposition on the catalyst against actual data were 0.5%, 0.94%, 1.098%, 0.57% and 0.347%, respectively. Then, the optimal values for reactor temperatures, feed flow rate and recycle flow rate were determined using sensitivity analysis approach. After setting these decision variables on the proposed optimal values, the actual RON and volume yield of the CCR plant enhanced from 99.55 and 82.04% to 99.67 and 82.4%, respectively.

Friction Characteristic of Mineral Oil Containing Palm Fatty Acid Distillate Using Four Ball Tribo-tester

Vegetable oil was one of the main sources of lubricating oil before the discovery of petroleum. Nowadays, due to vegetable oil's poor performance at high temperatures and oxidation, it has not been widely used in the industrial sector. However, the fatty acids contained in vegetable oils may significantly reduce the frictional coefficient. To optimize lubrication, vegetable oil can be mixed with mineral oil. In this paper, palm fatty acid distillate (PFAD) was mixed in mineral oil and it lubricating properties were tested. Palm oil is one of the major vegetable oils produced in the world, and PFAD is one of the by-products of the palm oil refinery process. It is classified as a non-edible oil, and therefore, the increased use of this product for mechanical lubrication would not affect the production of cooking oil, the food chain or increase food prices. The mixing percentage (PFAD to mineral oil) varies from 5% to 25% of the total mass. Testing was conducted using a four-ball tribotester accordance with the American Society for Testing and Materials (ASTM) standard 4172. The results show that by mixing a 20% total mass of palm oil in the mineral oil, the coefficient of friction reached its lowest value. The wear scars on the ball bearings lubricated with this mix of oil also showed acceptable diameter values when compared to other conditions. From these results, it can be concluded that the performance of the mineral oil could be enhanced by mixing it with vegetable oil (instead of mineral oil). However, the percentages should be determined properly.

Multi-period design of heat exchanger networks

Heat exchanger networks are an integral part of chemical processes as they recover available heat and reduce utility consumption, thereby improving the overall economics of an industrial plant. This paper focuses on heat exchanger network design for multi-period operation wherein the operating conditions of a process may vary with time. A typical example is the hydrotreating process in petroleum refineries where the operators increase reactor temperature to compensate for catalyst deactivation. Superstructure based multi-period models for heat exchanger network design have been proposed previously employing deterministic optimisation algorithms, e.g. (Aaltola, 2002; Verheyen and Zhang, 2006). Stochastic optimisation algorithms have also been applied for the design of flexible heat exchanger networks recently (Ma et al., 2007, 2008). The present work develops an optimisation approach using simulated annealing for design of heat exchanger networks for multi-period operation. A comparison of the new optimisation approach with previous deterministic optimisation based design approaches is presented to illustrate the utilisation of simulated annealing in design of optimal heat exchanger network configurations for multi-period operation.

Correlations between SARA Fractions, Density, and RI to Investigate the Stability of Asphaltene

Asphaltene precipitation is one of the most common problems in both oil recovery and refinery processes. Its deposition causes many problems mainly because of the fuzzy nature of asphaltene and the large number of parameters affecting precipitation. Unfortunately there is not a predictive technique for screening it. Refractive index (RI) was used as a stability test for asphaltene which makes a quantitative judgment for asphaltene stability. In our study, we first represent a novel correlation between SARA fractions and density and then demonstrate the relation between density and RI; second we developed a relation for SARA and RI, by utilizing RI to investigate the stability of asphaltene.

Simulation and planning of a petroleum refinery based on carbon rejection processes

A superstructure for the simulation of a typical petroleum refinery process scheme is developed in this work. The model consists of hydrotreating of naphtha, jet fuel, kerosene, light gas oil and FCC feed. It also includes catalytic reforming and catalytic cracking. For the processing of bottom-of-barrel the model considers delayed coking, visbreaking and gasification. The superstructure is capable to select those processes that will meet the products specifications. The processing units have operating variables which affect the product flow rates and properties. The objective function is to maximize the profitability of the entire refinery, optimizing the operating variables of the units and vacuum residue flow rate sent to each upgrading process. The best process scheme resulted that with the combination of delayed coking and gasification.

Development of Bio Hydro-fined Diesel (BHD) Technology: Hydrodeoxygenation of Palm Oil and Adaptability of BHD for Diesel Fuel

From the viewpoint of primary energy diversification and CO2 reduction, interests of using biomass fuel for transportation fuels are rising. Some kinds of FAME (Fatty Acid Methyl Esters), which are obtained from oil fats like vegetable oil using transesterification reaction with methanol, are getting popular for bio-diesel recently. As FAME has unsaturated carbon–carbon bonds which come from feed materials, its performance such as storage stability is concerned. And there are other points of concern, namely, effects of impurities in FAME on car components. In this current situation, technologies to produce high quality fuels from renewable sources, especially from vegetable oils, using petroleum refinery processes should be promising. In our study of the hydrotreatment of palm oil, what we called "Bio hydro-fined diesel (BHD)," it is possible to obtain from vegetable oil hydrocarbons nearly equal to conventional diesel fuel. BHD consists of alkyl chains derived from fatty acids in vegetable oil. BHD has higher oxidation stability than that of FAME. Evaluation of exhaust gases in engine tests on conventional diesel mixed with 10 % BHD showed same THC (total hydrocarbons), CO, and PM (particulate matter) emission as with base diesel alone. LCA (life cycle assessment) evaluation of BHD, petroleum diesel oil, and FAME produced from palm, although Wheel-to-Tank-CO2 of hydrogenated and FAME is higher than that of diesel, Well-to-Wheel-CO2 is lower due to the application of the biomass zero count rule. On the other hand, Well-to-Tank energy efficiency was same as FAME.

COMPARISON STUDY OF EXPERIMENTAL AND SIMULATION TEMPERATURE DATA IN THE ESTERIFICATION PROCESS OF PALM FATTY ACID DISTILLATE (PFAD) IN A FLUIDISED REACTOR

Palm Oil Fatty Acid Distillate (PFAD) is a by-product from palm oil refinery process and normally used as ingredient of making candles, soap and others. Recently, many researchers have been carried out to diversify the utilisation of PFAD in industry. Among others is the enzimatically production of sugar ester using PFAD as substrate. However, limited kinetic and simulation data hindered the effort of large scale production. Hence, this study was executed to determine the kinetic parameters of the esterification process based on the simplified Ping-pong Bi-Bi model under the temperature range of 30°C ~ 45°C where immobilised lipase (Lipozyme 1M) was used as biocatalyst and isopropyl alcohol was used as solvent. The reaction was conducted in a cylinder resemble a fluidised reactor. Kinetic parameters derived from the experiments were used to simulate the production of sugar ester. The optimum temperature for the production of sugar ester was found to be at 40°C. The experimental results deviate slightly from the simulation results with error percentage of less than 11%. The model can be used to predict the production of sugar ester when the concentrations of the reactants are varied.

Update on OSHA's PSM national emphasis programs

AbstractSince 2007, the US Occupational Safety and Health Administration (OSHA) has initiated two major national emphasis programs (NEPs) in process safety. The Petroleum Refinery Process Safety Management (PSM) NEP (Refinery NEP) was effective on June 7, 2007; the PSM Covered Chemical Facilities NEP (Chemical NEP) was effective on July 27, 2009. This article provides an update on the findings of these NEPs, including specific items cited and challenges encountered. Published 2011 American Institute of Chemical Engineers Process Saf Prog, 2011

Inhibition of Asphaltene Precipitation by TiO2, SiO2, and ZrO2 Nanofluids

Asphaltene precipitation causes several problems during crude oil production, transportation, and refinery processes. Therefore, finding an inhibitor to prevent or delay asphaltene precipitation is of paramount importance. In this work, effects of TiO2, ZrO2, and SiO2 fine nanoparticles in organic-based nanofluids have been investigated to study their potential for stabilizing asphaltene particles in oil. To this end, polarized light microscopy has been applied to determine the onset of asphaltene precipitation by titration of dead oil samples from Iranian crude oil reservoirs with n-heptane in the presence of nanofluids. Results show that rutile (TiO2) fine nanoparticles can effectively enhance the asphaltene stability in acidic conditions and act inversely in basic conditions. It was found that the required amount of n-heptane for destabilizing the colloidal asphaltene is considerably higher in presence of TiO2 nanofluids at pH below 4. The FTIR spectroscopy indicates changes in n-heptane insoluble asph...

A new approach to averaging level control

In this paper, a new simple algorithm for averaging level control is presented. The proposed algorithm is based on the use of a static nonlinear controller to improve the input flow filtering by reducing the slope of the controller around the average input flow. In order to adapt the controller to changes in the average input flow, a low-pass filtered value of the estimated input flow is used to update the nonlinear function that defines the static controller. The stability of the closed loop is demonstrated, and the validity of the proposed strategy is tested in simulations and on a real oil refinery process.