Atmospheric Distillation Column Research Articles

СПЕКТР БАГАТОВИМІРНИХ МОДЕЛЕЙ ДИНАМІКИ КОЛОНИ РЕКТИФІКАЦІЇ НАФТИ ДЛЯ СИНТЕЗУ РОБАСТНИХ СИСТЕМ УПРАВЛІННЯ

Classical automatic control systems of crude oil distillation columns are used to stabilize indirect parameters (temperature, pressure, level) which are considered as independent. Such systems can be used in case of small disturbances and fluctuation of oil composition. The article describes the set of linear mathematical dynamical models of multi-component crude oil atmospheric distillation column K-2 which is based on direct parameters of material balance. For development of modern multivariable automatic control systems it’s preferable to use direct material balance parameters because change of products flow ratios leads to economical loses. Developed models shows that the plant is significantly multivariable with big lag, so effective automatic control system can be designed only with use of modern control theory. The developed set of models can be used for research of robustness and quality of multivariable automatic control systems (optimal, suboptimal, model-predictive, etc) of crude oil distillations columns which oriented on material balance parameters

Robust control system design of crude oil atmospheric distillation column

The robust control system of multi-component oil atmospheric distillation column was designed. Since the dynamics of the column can not be accurately modeled, a set of models, used at different design stages of the control system was developed. In the paper, the robustness of the control system means the preservation of its high quality when connecting any model of the developed set. The big advantage of the system is the fact that it is based on a multi-dimensional digital linear-quadratic regulator and the parameters that determine the material balance of the column are used as controlled variables. Such a system is easy to implement and can successfully replace traditional control systems of oil distillation columns and modern commercial control systems, which are based on model-predictive controllers popular in the global oil and gas industry.

Exergetic improvement and environmental impact assessment of crude oil distillation unit of Shazand-Arak oil refinery

In this study, the crude oil distillation unit (CDU) of the phase 1 Shazand-Arak oil refinery has been studied by the exergy point of view. Exergy analysis specifies the system exergy loss points. The considered CDU has been designed twice due to a feed change during the past two decades. Both designs of the unit are simulated by Aspen PLUS software to gather required data for the calculations and evaluate exergy efficiency improvement by suggesting new strategies for the system. Furthermore, the effect of the proposed process changes on CO2 emission rate reduction is explored. The analysis indicated that the atmospheric distillation column and the main furnace sections owned the lowest exergy efficiency among the studied sections of the unit. Finally, the most achieved improvements were ∼1.2% gain for the exergy efficiency and 5.5% reductions in CO2 emission rate in comparison to the last design of the unit.

A Sliding Mixed-Integer Linear Programming Approach for the Optimization of the Cleaning Schedule of Crude Preheat Trains

The fuel consumption in the fired heaters of atmospheric distillation columns for petroleum refining increases during the refinery operation. This effect is a consequence of fouling in the heat exchangers of the crude preheat train. The application of a cleaning schedule to the crude preheat train can reduce fouling costs. However, the management of the cleanings for the entire set of interconnected heat exchangers is a complex problem. Aiming to contribute to the solution of this problem, this paper presents an optimization approach based on the resolution of a sequence of mixed-integer linear programming problems. Each problem indicates the set of heat exchangers that must be cleaned in a certain time instant. The structure of the crude preheat train is described using an incidence matrix, encompassing supply and demand nodes, heat exchangers, mixers, splitters, and desalters. The sequence of problems is associated to a sliding horizon, where the concatenation of the solutions composes the complete heat exchanger cleaning schedule. Although the present approach cannot guarantee the global optimality of the solution, the linear structure avoids nonconvergence problems. The performance of the proposed approach is illustrated through its application in an example of a crude preheat train from a Brazilian refinery.

Accidental Risk Assessment on Atmospheric Distillation Column in Oil Refinery

Accidental Risk Assessment on Atmospheric Distillation Column in Oil Refinery

Operational optimization of a simulated atmospheric distillation column using support vector regression models and information analysis

Like any other production processes, atmospheric distillation of crude oil is too complex to be accurately described with first principle models, and on-site experiments guided by some statistical optimization method are often necessary to achieve the optimum operating conditions. In this study, the design of experiment (DOE) optimization procedure proposed originally by Chen et al. (1998) and extended later by Chu et al. (2003) has been revised by using support vector regression (SVR) to build models for target processes. The location of future experiments is suggested through information analysis which is based on SVR models for the performance index and observed variables and reduces significantly the number of experiments needed. A simulated atmospheric distillation column (ADC) is built with Aspen Plus (version 11.1) for a real operating ADC. Kernel functions and parameters are investigated for SVR models to represent suitably the behavior of the simulated ADC. To verify the effectiveness of the revised DOE optimization procedure, three case studies are carried out: (1) The modified Himmelblau function is minimized under a circle constraint; (2) the net profit of the simulated ADC is maximized with all the 15 controlled variables free for adjusting in their operational ranges; (3) the net profit of the simulated ADC is maximized with fixed production rates for the three side-draws.

Efficient and clean production of fuels and biofuels: a summary

This special issue (SI) offers selected papers from the PRES’11 conference, on exergy and process integration methodologies, integrated membranes and fibrous separation. Areas covered by these papers are related to renewables and include: biofineries, bioethanol, biogas, biodiesel, biowaste treatment, carbon and nitrogen tradeoffs, decarbonised coal energy system, solar energy integration and CO2 capture. The manuscripts have been selected to provide insight into various fields related to environmental policies and pollution reduction technologies. The methodologies and applications presented here demonstrate important diversity of technical and policy issues. Crude oil atmospheric distillation columns in oil refineries consume huge amount of energy taken from crude oil, generating emissions including large amount of CO2 .A group of researchers: Amir Hossein Tarighaleslami from Islamic Azad University, Mahshar, Iran; Mohammad Reza

Thermodynamic evaluation of distillation columns using exergy loss profiles: a case study on the crude oil atmospheric distillation column

This paper presents a case study on the crude oil atmospheric distillation column of Tabriz refinery plant to show the applicability of exergy loss profiles in thermodynamic examination of the different retrofit options. The atmospheric distillation column of Tabriz refinery has been revamped as a consequence of increase of the plant capacity to 100,000 bpd. To cover the deficit of feedstock of the revamped unit, a blend of the existing feedstock with imported crude oil is used as a feedstock. However, to investigate how the blend of these two different types of crudes as a feedstock has an influence on the operating conditions, the examination of the column is needed. Exergy as a comprehensive thermodynamic property which translates the temperature, pressure and composition change into a common unit has been chosen to evaluate the distillation column thermodynamically. Furthermore, the exergy loss profile of the base case serves as a scoping tool to pinpoint the source of inefficiencies. Then, the exergy loss profile as a screening tool has found the retrofit options which are likely to yield greatest energy saving from a list of retrofit options proposed by the industrial partner. In the presented case study, the exergy loss profile identifies the best retrofit option with 17.16% reduction in exergy losses, which finally lead to 3.6% reduction of primary fuel demand.

Application of the self-heat recuperation technology to crude oil distillation

Crude oil distillation is an atmospheric distillation column using a furnace. It consumes about 50% of the energy required in an oil refinery plant. To reduce energy requirements, it is necessary to investigate crude oil distillation and to retrofit it with energy saving processes. Recently, the authors developed an innovative process design technology, termed self-heat recuperation technology for saving energy. To apply this technology, whole-process heat is recirculated within the process without heat addition, leading to large energy savings. In this paper, crude oil distillation is analyzed and a crude oil distillation model for an energy saving design is developed. Furthermore, the feasibility of application of self-heat recuperation technology is investigated and self-heat recuperative crude oil distillation is proposed.

Energy Saving in Crude Oil Atmospheric Distillation Columns by Modifying the Vapor Feed Inlet Tray

AbstractOptimization of a typical crude oil atmospheric distillation unit and reduction of energy conservation were carried out through modifying the implementation and change in the flash zone of the tower. A conventional procedure in such units involves the combination of liquid and vapor product of the prefractionation train surge drum upon introduction to the tower. However, it is theoretically illustrated and represented by simulation means that introducing the vapor feed into the upper stages of the distillation column separately can lead to an energy saving of 12.6 % in the condenser duty, an increased liquid‐to‐gas flow (L/G) at certain points of the column, and hence to a reduction in diameter and investment costs of new tower designs of approximately US$ 0.7 million a–1. The proposal can be put into practice without the need of additional equipments or additional cost of difficult rerouting the streams. An industrial case study of a steady‐state crude oil distillation unit is given by simulation provision of AspenHysys™.

Optimization of crude distillation system using aspen plus: Effect of binary feed selection on grass-root design

With an objective to supplement guidelines available as general rules of thumb for the grass-root design of crude distillation unit (CDU) using binary crude mixtures, this work presents the optimization of crude distillation unit using commercial Aspen Plus software. The crude distillation unit constituted a pre-flash tower (PF), an atmospheric distillation unit (ADU) and a vacuum distillation unit (VDU). Optimization model constituted a rigorous simulation model supplemented with suitable objective functions with and without product flow rate constraints. Three different feed stocks namely Bombay crude, Araby crude and Nigeria crude were considered in this work along with various binary combinations of these crudes. The objective function considered was profit function (subjected to maximization) for cases without product flow rate constraints and raw-materials and energy cost (subjected to minimization) for cases with product flow rate constraints. Parametric study pertaining to feed selection and composition has been conducted in this work to further benefit refinery planning and scheduling. Simulation study inferred that the product flow rate constraints sensitively affect atmospheric distillation column diameter and crude feed flow rate calculations. Based on all simulation studies, a generalized inference confirms that it is difficult to judge upon the quality of the solutions obtained as far as their global optimality is concerned.

Pyrolysis of Polyvinyl Chloride (PVC)-Containing Mixed Plastic Wastes for Recovery of Hydrocarbons

The pyrolysis of mixed plastic waste (high-density polyethylene, polypropylene, polystyrene, and polyvinyl chloride) using a long residence time (25 min) in a horizontal tube reactor at 530 °C has been investigated. The reactor was fitted with atmospheric and vacuum distillation columns, so that the pyrolysis products could be separated into heavy oil, light oil, gasoline, and gases. The effect of the polyvinyl chloride (PVC) concentration on the properties of products was investigated. Products were characterized using gas chromatography, infrared spectroscopy, and energy-dispersive X-ray spectroscopy, whereas some other standardized methods were used to determine the main properties of hydrocarbons. Results show that the mixed plastic waste samples could be converted into gases, gasoline, and light oil with yields of 36.9−59.6% depending upon the composition of feed polymers, and the conversion of decomposition is significantly increased with an increasing concentration of PVC. It was found that product...

Sizing of vacuum relief valves for atmospheric distillation columns

Abstract A distillation column operating under pressurized conditions may not be designed for full vacuum. A vacuum relief valve on such column must, therefore, be sized to prevent negative pressures in the shell under the worst case scenario, i.e. when the feed, bottoms, distillate and reboiler steam are cut off, but the condenser still operates. The valve can be sized considering that the inflowing air (or other gas) first accumulates in the condenser, which is the vacuum source, and blankets the heat exchange area stopping the condensation. A conservative estimate of the amount of air required to blanket the condenser is given by the condenser volume. The rate at which this inflow must occur can be found from a transient total energy balance around the column, as described below. This method has been applied for valve sizing in real columns and results in reasonable valve sizes. To the best of our knowledge, no other method for carrying out this calculation is available in the open literature.

Modelling of a crude distillation column

An algorithm and a FORTRAN program have been developed for modelling of crude distillation and vacuum columns on smaller computers. Wang-Henke and Sum of Rates methods are combined in a new way. The memory requirement is low even in the case of a great number of pseudocomponents. An atmospheric crude distillation column has been simulated. Crude oil is described with 50 pseudocomponents chosen on the basis of the TBP curve of the feed. Calcula and experimental results are compared.

Coal liquids distillation tower corrosion. Analysis of SRC atmospheric distillation column samples for the presence of a highly corrosive organic chloride compound class

Samples from the Wilsonville, Alabama, demonstration plant were chemically separated into phenolic, amine and neutral fractions. Each fraction was analyzed for total chloride. The results indicate that the high corrosion rates in the atmospheric distillation tower were not due to the formation of a highly corrosive organic chloride.