Vacuum Distillation Unit Research Articles

Simulation of Vacuum Distillation Unit in Oil Refinery: Operational Strategies for Optimal Yield Efficiency

Simulation of Vacuum Distillation Unit in Oil Refinery: Operational Strategies for Optimal Yield Efficiency

An optimization study on enhancing the vacuum distillation unit using MPC in comparison with PID controller

An optimization study on enhancing the vacuum distillation unit using MPC in comparison with PID controller

Simultaneous optimization of crude oil refinery vacuum distillation column and corresponding ejector system

A vacuum distillation unit (VDU) is a relatively complex crude oil refining process that usually overlooked in researches. A detailed review of the corresponding literature reveals that most of the limited existing researches focus on either the study of the vacuum tower alone or its vacuum creating ejector system. For the first time, the combination of VDU tower and corresponding ejectors are studied in this article by resorting to coupling of Aspen-HYSYS simulation software with Ansys-FLUENT computational fluid dynamic. Both simulations were initially validated by using two sets of experimental and industrial data, borrowed from literature.Optimization of an industrial unit improved its process economics by boosting the heavy vacuum gasoil production around 38% and reducing the less valuable cut of vacuum residue by 28%, which increases the overall earnings of the optimal VDU column economics over 140 MM$/year. Furthermore, sensitivity analysis of the VDU ejector system revealed that the primary steam cost does not depend on the corresponding temperature, while, it rapidly rises, when the motive fluid pressure increases. The overall simulation results of the VDU tower and corresponding ejector system concluded that the lower primary steam pressures are more favorable both from operational and economical standpoints.

Optimisation of Vacuum Distillation Units in Oil Refineries Using Surrogate Models

To ensure the optimum performance of downstream processes in a petrochemical refinery, the operation of a vacuum distillation unit (VDU) is critical. It needs to satisfy the yield and quality requirements of the downstream process. Otherwise, it will result in a loss of profitability in the refinery. Hence, it is important to optimise the operation of the VDU to ensure optimum performance. Traditionally, VDU is operated within the design envelope, and its operation condition is fine-tuned based on the operator’s experience. However, such action does not guarantee the optimum performance of the entire refinery as it only considers the operation of VDU without understanding the effects towards downstream processes. Therefore, this work presents a framework to optimise VDU operations with consideration of the downstream processes. The framework consists of process simulation, surrogate modelling, and multi-objective optimisation. The developed framework aims to determine trade-offs between high vacuum gas oil (HVGO) yield and total annualised cost (TAC) of a refinery that considers the needs of downstream operations. In this work, crude oil blending ratio, furnace outlet temperature, flash zone temperature, column top pressure, column bottom pressure, stripping steam flowrate, HVGO pump-around flowrate, and light vacuum gas oil (LVGO) pump-around flowrate of the VDU are to be optimised. Based on the optimised result, the heavy-light crude blend achieves higher HVGO yield and lower TAC, and the optimised results were validated with the simulation results via Aspen HYSYS. The proposed methodology was proven to have accurate estimations of the VDU operation in the process simulation environment. Moreover, the optimised results can provide insight into the optimal process conditions of VDU for the refiners. With this insight, effective operating strategies can be developed to overcome the limitations present in real VDU operations.

Implementation of vacuum distillation system at PPLi: A case study on high-concentrated waste treatment and water recycling

This case study presents the successful implementation of a vacuum distillation system at PPLi for treatment of high-concentrated waste, with a focus on water recycling. The vacuum distillation unit employs advanced thermal heating and evaporation processes, facilitated by reduced pressure, to effectively separate contaminants from the waste stream. Operational parameters, including waste type, feed rate, temperature settings, and vacuum level, were meticulously optimized to achieve optimal treatment efficiency. The study conducted experimental trials over six months, rigorously monitoring and analyzing the treated water quality for chemical composition, total dissolved solids (TDS), and other relevant parameters. Results showed a remarkable reduction in TDS and chemical contaminants, ensuring compliance with stringent regulatory standards. Additionally, the case study explored potential reuse and recovery options for the separated concentrated waste. Laboratory tests examined the feasibility of utilizing the waste residues for energy generation or as raw materials for other processes. The successful implementation of the vacuum distillation system at PPLi underscores its practicality and effectiveness in treating high-concentrated waste while facilitating water recycling. This achievement represents a significant step towards reducing environmental impacts associated with waste disposal and conserving precious water resources. The insights gained from this study serve as a valuable reference for industrial facilities seeking sustainable waste management solutions, fostering a circular economy approach and promoting responsible environmental stewardship.

Modular Refineries Offer Advantages for Product Availability in Nigeria

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 211932, “Imperatives of Modular Refineries and Their Impact on Product Availability in Nigeria,” by Evelyn Bose Ekeinde and Adewale Dosunmu, SPE, Federal University Otuoke, and Diepiriye Chenaboso Okujagu, University of Port Harcourt, et al. The paper has not been peer reviewed. _ Nigeria is rich in crude oil, with a proven reserve of 37 billion bbl. Despite the abundance of this resource, Nigeria has lacked the capacity to meet the country’s demand for petroleum products locally and has resorted to their importation. Establishing conventional refineries is highly capital-intensive, and they take a significant amount of time to build and commission. The modular refinery option is a less capital-intensive alternative. The complete paper discusses the promise of modular refineries and their potential effects on the availability of petroleum products in Nigeria. Introduction Despite its large reserves of crude oil and a combined in-country refining capacity of 445,000 B/D from four state-owned refineries, Nigeria has been plagued with challenges in local refinement. These refineries have operated grossly below installed capacity for decades, operating at a capacity hovering between 15 and 25%. The inability to harness local refining to meet demands for petroleum products has turned Nigeria into a net importer. Modular Refineries A modular refinery is a processing plant composed entirely of skid-mounted structures, each of which comprises a part of the entire processing plant. Various components are connected through interstitial pipes to create a highly manageable process. They are smaller than conventional refineries, with processing capacities ranging from 1,000 to 30,000 B/D. Essentially, modular refineries are mini-refineries. Modular topping plants or crude distillation units are the most straightforward and cost-effective method of extracting valuable fuels from crude oil. Within 14 months of contract execution, a topping plant can be operational, providing host communities with vital fuels for automobiles, power generation, and job possibilities. Furthermore, construction of a modular refinery is less capital-intensive, ranging from $1 million to $15 million, compared with a conventional refinery, which could cost up to hundreds of millions or even billions of dollars, depending on the refinery’s complexity and configuration. Many configurations featuring different degrees of sophistication exist for modular mini-refineries. They include the following: - Atmospheric topping unit—This is an inexpensive distillation unit that can make diesel and kerosene from raw crude oil. Naphtha and fuel oil also can be byproducts. - Topping unit with gasoline train—This option features the addition of regenerative agents or hydrotherapy, thus producing high-octane unleaded gasoline and high-octane liquefied petroleum gas. This configuration can put together isomerization units to make more premium unleaded gasoline. It also can make more gasoline with a higher octane rating. - Vacuum distillation unit—The addition of a second distillation tower to separate the fuel components from the atmospheric tower results in clean heavy diesel (vacuum gas oil) and dirty heavy residual oil. - Hydrocracker unit, full conversion—The hydrocracker unit (which has a high capital cost) transforms light and heavy gas oils into more-marketable products with a lower boiling point. The yield of a hydrocracker unit may add to the profitability of a refinery.

Standard diesel production from mixed waste plastics through thermal pyrolysis and vacuum distillation

Plastic pyrolysis oil (PPO) was produced in a pilot-scale batch pyrolysis reactor at 540 °C from mixed waste plastic (MWP) (high-density polyethylene (HDPE), polypropylene (PP) and polystyrene (PS)). The produced PPO was then distilled in a vacuum distillation unit and diesel was obtained at temperatures between 170 and 380 °C along with light petrol (<170 °C) and heavy residue (>380 °C). This study found that MWP can produce over 80% liquid oils without operational problems or wax formation. Distilled PPO produces 49.5–53% diesel, 39 – 46.5% petrol and residue 1.5 – 8% by weight. Although PPO has calorific value ranging from 43.85 to 45.26 MJ/kg like commercial diesel however, PPO is not suitable for direct use in diesel engine for low kinematic viscosity (KV) and density values at 1.1–1.26 mm2/s and 0.78 – 0.83 gm/cm3 respectively. For the distilled diesel cut (DC), KV, density, higher heating value (HHV), cetane index (CI), aromatic hydrocarbon (AH) and poli-aromatic hydrocarbon (PAH) were found 1.95–2.15 mm2/s, 0.81 – 0.85 gm/cm3, 44.92–46.36 MJ/kg, 46 – 58, 18.81 – 35.1% and 4.81 – 11.9% respectively indicating better option for direct use as automobile diesel with significant effect of HDPE amount present in feedstock.

Fingerprint characteristics of refined oils and their traceability in the groundwater environment

Chemical fingerprinting is essential for identifying the presence and responding to oil spills that frequently contaminate the groundwater environment of refineries. In this study, crude oil and oil products from the atmospheric and vacuum distillation units of a refinery were analyzed by gas chromatography-mass spectrometry (GC-MS) to evaluate their chemical variability before and after refinery. A series of experiments involving evaporation and soil column penetration were conducted to simulate refined oil spilling into groundwater and determine appropriate characteristic ratios (CRs) for principal component analysis (PCA) for oil source identification. The simulated study demonstrated that all products had bell-shaped n-alkane distributions, with dominant peaks that remained unchanged or shifted towards longer chain lengths compared to the source oil. Similarly, naphthalene and dibenzothiophene series remained the main PAH components like the source oil. Ten relatively stable CRs were selected for PCA to identify different oil products through the simulated experiments. The chosen CRs were then utilized to identify the sources for two groundwater oil spills recently occurred, one that occurred in an oil depot area, and another near a continuous catalytic reforming unit in a refinery. This study showed that the components with long-chain n-alkanes (n ≥ C18), pristane, phytane, and phenanthrene and dibenzothiophene series PAHs played an important role in the identification of refined oil products spilling into the groundwater environment. The selected CRs provide an effective tool for rapid and accurate identification of oil spills, especially for newly occurring spills in the groundwater environment, which can aid in developing appropriate response strategies.

SCALING OF THE SYNTHESIS PROCESS OF BENZO-15-CROWN-5 IN THE CONDITIONS OF PILOT PRODUCTION

This article describes the development of a method for the synthesis of benzo-15-crown-5, a promising extractant of lithium isotopes that are widely used in various fields of nuclear technology. The synthesis of benzo-15-crown-5 was carried out by the method of two-component condensation of pyrocatechol and tetraethylene glycol dichloride in the presence of a template agent sodium hydroxide, followed by extraction of crown ether by hexane or isolation by vacuum distillation. Optimal synthesis conditions were determined, impurities were chromatographically identified, the technological reaction time was determined and methods of introducing raw materials into the reaction mass were investigated. The study showed that the drip addition of tetraethylene glycol dichloride leads to the fact that the content of benzo-15-crown-5 reaches 82.1% in the reaction mass. The optimal holding time of the reaction mass is 7 h at boiling point. The processes of isolation of the target product (hexane extraction, vacuum distillation) were selected and studied. The proven technique has been fully adapted to a pilot industrial plant for the synthesis of crown ethers, consisting of three mixing reactors, nutch filters, measuring tanks and a vacuum distillation unit. The developed installation allows to receive up to 25 kg of high-quality product per month. The product was identified using NMR and IR spectroscopy and elemental analysis. At the pilot plant, it was possible to obtain a product whose yield was 41%, compared with 48% at the laboratory plant, which is a very good indicator for scaling, without loss of quality of the synthesis product. The purity of benzo-15-crown-5 was more than 98% according to gas-liquid chromatography.

Optimization of Process Economics in Mini Oil Refinery for Remote Areas

The effects of the energy crisis and the rising energy demand have sparked development to improve efficiency in using fuel oil. According to Indonesia's oil resources, increasing refinery capacity and building mini refineries is essential to secure local refinery production. It is more effective and cost-effective to construct a small refinery with a configuration starting with a flash unit or pre-fractionator, to an atmospheric distillation unit, and a vacuum distillation unit as the last process in each oil-producing region than construct a large-scale refinery. The optimization concerned a variety of preflash furnace temperatures simulated by Aspen Plus software. The increasing temperature will change the production rate and the utility needed, which could change sales and operating costs. The result describes that the optimum profit for the mini-refinery plant is performed preflash furnace at 533 K with 108.20 US$/m3 crude oil profit.

Development of inferential sensor and real-time optimizer for a vacuum distillation unit by recurrent neural network modeling of time series data

In lube base oil production, a vacuum distillation unit (VDU) is a crucial unit operation which must be controlled tightly to meet final product specifications. To address this requirement, model-based optimal control can be employed, which requires an accurate model relating to the operation and quality variables involved. However, the mathematical modeling of VDU is hampered by the lack of process knowledge and the limited online data acquisition capability for key quality variables. As a recourse, data-based modeling can be attempted to develop inferential sensors and controllers but one is faced with the problem of temporal credit assignment due to the complex characteristics of the VDU process dynamics, e.g., varying time-lags among the variables. To overcome this difficulty, the use of a stacked RNN structure with sequence length is proposed for the prediction of kinematic viscosity. In addition, regression models for the product's distillation temperatures are constructed by testing a large number of regression model structures. Then, these quality predictors are applied in developing a real-time optimizer which adjusts key operating variables in order to satisfy the product specifications despite various disturbances. Accuracies of the soft sensor and the optimization model are evaluated, first offline and then, online through a commercial plant test performed at SK Ulsan Refinery Complex in Korea. The overall approach and framework are general and can be used for the development of inferential sensors and controllers in other similar situations.

Preliminary Design of Mini Oil Refinery Plant

As an archipelagic country, Indonesia faces challenges in supplying fuel to various regions. Some regions have small oil reserves and small fuel demand. Other regions have greater fuel demands. One solution to overcome the issue of fuel supply is to build and develop mini refineries with a scale of 6,000 – 20,000 barrels per day to maximize the potential of existing oil reserves, reach remote areas, and meet domestic demands. This study aims to analyze the feasibility of a mini oil refinery from a technical and economic perspective. The feed used for this plant is light crude oil with API gravity 47.3002 from the Belida block, South Sumatra. The plant is designed with a capacity of 10,000 barrels per day to produce intermediate products. The production process at this plant uses a simple process to reduce capital costs, which consists of a Preheater, Pre-Flash Distillation Unit, Atmospheric Distillation Unit, and Vacuum Distillation Unit. From the results of economic analysis, the obtained capital cost of IDR 517,640 million and operational cost of IDR 2,860,622 million. Meanwhile, the payback period is 4.5 years, and the break-even point is 48%. By considering the economic and technical aspects, this Mini Oil Refinery is feasible to be built.

Optimization Study on Enhancing Deep-Cut Effect of the Vacuum Distillation Unit (VDU)

The vacuum distillation unit (VDU) is the key unit to produce vacuum gas oil and vacuum residue, which has a very important impact on the downstream secondary processing units. The optimization of deep-cut vacuum distillation seeks to improve the yield of heavy vacuum gas oil (HVGO) and its dry point temperature, which is related to the economic benefits of the refinery. In this study, we first established a simple model of a VDU by using the Aspen HYSYS Process simulation software. Then, we built a rigorous model with fast convergence by using the initial values obtained by the simple model. The rigorous model can accurately reflect the refinery’s operation and can make predictions. Then, based on the rigorous model, we increased the flash section temperature (FST) to 420 °C and the steam flow rate (SFR) of the stripping to 26 t/h. We eventually increased the yield of HVGO by 6.3 percentage points to 43.4%, while increasing its D86 95%-point temperature by 31.9 °C to 570.9 °C. In this way, the refinery can effectively optimize the deep-cut vacuum distillation and obtain greater economic benefits.

СРАВНИТЕЛЬНЫЙ АНАЛИЗ РЕКУРРЕНТНЫХ НЕЙРОННЫХ СЕТЕЙ И МОДЕЛИ АВТОРЕГРЕССИИ ARIMA ПРИ ПРОГНОЗИРОВАНИИ НЕСТАЦИОНАРНЫХ ВРЕМЕННЫХ РЯДОВ

А comparative analysis of the recurrent neural network model and the ARIMA autoregression model was carried out to predict light fractions output produced by the crude and vacuum distillation unit. There is a mathematical description of these models. There are the implementation of models using Keras and Pmdarima libraries in Python. A series of experiments was carried out, values of K-2 column cube temperature, crude oil consumption and gasoline fraction consumption were used as input data. The conclusion is made about the superiority of prediction quality of neural networks over ARIMA.

Technology of Producing Petroleum Coking Additives to Replace Coking Coal.

Coke chemical companies often have a deficit of coals of particularly valuable grades, the coking coals. This work studies the opportunity of producing petroleum coking additives using delayed coking during heavy petroleum residue processing. Experiments for the production of a carbon material were conducted using three kinds of heavy petroleum residues of the oil refinery plant Ltd Kinef: the vacuum residue from crude atmospheric and vacuum distillation units (VR1), the vacuum residue from the vacuum distillation hydrocracking unit (VR2), and the visbreaker residue from the visbreaking unit (VR3). For the produced carbon material, the quality indicators were determined, and X-ray diffraction, thermogravimetric, and differential thermal analyses were conducted. The petroleum coking additive produced instead of the typical petroleum coke under a milder temperature regime had the required quality indicators, particularly, the volatile-matter yield within the range from 15 to 25 wt %, to be used in metallurgical production for partial replacement of coking coals in the charge to produce metallurgical coke.

Sn–Pb alloy processing for commercial tin production

The aim of the research is to develop an optimal method for Sn–Pb alloy processing to obtain a marketable product – high-grade tin O1–O3 (Sn  98.5 %). Laboratory studies were conducted on the refining of the Sn–Pb alloy with the following composition, wt.%: 53–60 Sn; 18–29 Pb, first by vacuum distillation (t = 1085÷1300 °C, P = 15÷100 Рa; τ = 3÷36 h) for As, Sb and Pb sublimation, then by reagent deposition with elemental sulfur and aluminum as part of the Al–Sn master alloy in the presence of NH4Cl for Cu, Fe and Sb separation. This resulted in obtaining a Sn-containing residue (yield ~60 %) of the following composition, wt.%: 92.39 Sn; 0.46 Pb that was subjected to reagent refining to obtain O3 grade tin (metal yield ~68 %) with the following composition, wt.%: 99.5 Sn; 0.009 Pb. It was found that it is feasible to carry out refining from a preliminarily decopperized Sn–Pb alloy to obtain a finished O1 grade product with a direct extraction of 90 %. A schematic diagram was developed and recommendations were formulated for the process regulations on Sn–Pb alloy processing to obtain commercial tin and recover resulting intermediate products and waste. A furnace with separate production of As, Sb, Pb condensates with the following composition, wt.%: 94.2–98.3 As; 5.1–14.5 Sb; 78.9–86.4 Pb, respectively, was chosen as a vacuum distillation unit. The economic effect of processing ~480 ton/year of Sn–Pb alloy (~50.8 % Sn) with the production of ~235 ton/year of O1–O3 grade tin is ~39 million rubles/year.

Mini-Refinery Vacuum Unit: Functional Analysis and Improvement of Vacuum Overhead System

The purpose of this study was to analyze the functioning of the vacuum distillation unit of a mini-refinery and to develop recommendations for improving the vacuum overhead system with the aim to reduce the cost of creating and maintaining a vacuum in the fuel oil separation column. A calculation model of the vacuum unit was developed in the Unisim Design R451 software package, which was identified by comparing the calculated data with the data from an industrial study for two operating modes of the installation. Replacing the existing steam-ejector pump with a liquid-ring vacuum pump was proposed. A numerical experiment was carried out on the developed model, the purpose of which was to determine the “bottlenecks” of the scheme. The peculiarity of the experiment was that the vacuum column and the vacuum overhead system were considered as a single whole. As a result, it was determined that the “bottleneck” is the condenser, which was proposed to be replaced. During the technical and economic analysis, two possible vacuum overhead system schemes were considered; according to the results, it was determined that the vacuum overhead system scheme based on a liquid-ring vacuum pump will help reduce operating costs by 78%.

Investigation of Heavy and Trace Metals in Some Kurdistan Region Crude Oils by Spectroscan MAX-G

Four types of Kurdistan crude oils have been studied to determine the heavy and trace metals. The significance of determining trace elements that exist in crude oils is helpful for further information about exploration, production and the refining process. In this work crude oil can be separated into products such as (gasoline, kerosene, diesel, and atmospheric distillation residue +350°C) by using atmospheric distillation unit and vacuum distillation unit. The trace metals can be determined with acceptable accuracy and precision by spectroscan MAX-G. However, the values of Ni concentration were the best in accuracy among the group of metals of interest. The average values of the results will be employed as reference values of the trace metal content in the coming discussion and using Ni and V as test elements. The crude oil samples are characterized by with a dominance of V over Ni with a V/Ni ratio of 3.7 to 2.5. Trace element analysis of the five metals in crude oils and atmospheric distillation residues +350°C, for each crude oils and atmospheric distillation residues +350°C is investigated, samples of these areas has not been previously examined for trace element contents. In this study to find the relation between metals in crude oils and atmospheric distillation residue of samples. To detect the concentration of trace elements by using this instrument.

Optimising of vacuum distillation units using surrogate models

Crude oil blending is an important step for the operation of crude distillation systems in the refinery to improve the yield and profitability of the products. The product’s yield and quality are strongly dependent on the properties of the crude oil. However, the products of crude distillation units, especially the vacuum distillation unit (VDU) need to satisfy the yield and quality requirements of the downstream process units in the refinery. Otherwise, the performance of downstream processes will be affected, and loss of profitability in the refinery. Hence, it is important to optimise the performance of the VDU to ensure the optimum operation of VDU. This work covers the process simulation of VDU, surrogate modelling and mathematical optimisation model. The objective of the developed optimisation model is to determine an optimal for maximum high vacuum gas oil (HVGO) yield and minimum total annualised cost (TAC) respectively. To do this, crude oil blending ratio, column temperature, column pressure, stripping steam flowrate, pump-around flowrate in the VDU are optimised. Based on the optimised result, the heavy-light crude blend achieves higher HVGO yield and lower TAC as compared to the heavy-medium crude blend and heavy-medium-light crude blend. The optimised results can provide insight into the optimal process conditions of VDU for the refiners. With this insight, effective operating strategies can be developed to overcome the limitations present in real VDU operations.

OPTIMISING FOR VIABILITY – REVAMPING VACUUM DISTILLATION UNIT IN A BROWNFIELD PROJECT

Revamping an existing column in an operating plant for higher throughput is always challenging, especially when operating at its rated capacity. This is particularly true for a Vacuum Distillation Unit (VDU) column which involves multiple product and pump-around streams and associated auxiliary units like a steam ejector system. Optimising the design and operation of the column, hence, is inevitable to ensure the viability of a brownfield project as it avoids major modifications required to the column and its associated auxiliary systems. This paper discusses how optimisation was done on an existing VDU column design and operation in an oil refinery, avoiding major modifications of the associated ejector, steam, cooling water, sour water systems, and heat exchanger network, allowing a brownfield project to stay commercially viable.