A step toward saving energy using thermal modification of crude oil preheat network: A case study (original) (raw)
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Asia-Pacific Journal of Chemical Engineering, 2013
The heat integration and retrofit analysis of Arabian light crude distillation units was carried out to identify opportunity for energy savings using different design options, to achieve optimum heat exchanger network. Data used were extracted from an existing and operating crude oil refining plant. The pinch analysis of existing plant using process integration software (Heat-Int) Process Integration Limited, Cheshire, United Kingdom revealed that the hot and cold utilities consumptions at the prevailing ΔT min of 77°F in the plant were 680.23 and 521 MMBtu/h, respectively. Economic evaluation of existing plant revealed total operating cost of $4 829 625/year. Retrofit of existing plant using different design options generated an optimal network comprised four additional heat exchangers with reduction in ΔT min from 77°F to 57°F
Optimization of Existing Heat-Integrated Refinery Distillation Systems
Chemical Engineering Research & Design, 2003
E xisting re nery distillation systems are highly energy-intensive, and have complex column con gurations that interact strongly with the associated heat exchanger network. An optimization approach is developed for existing re nery distillation processes. The optimization framework includes shortcut models developed for the simulation of the existing distillation column, and a retro t shortcut model for the heat exchanger network. The existing distillation process is optimized by changing key operating parameters, while simultaneously accounting for hydraulic limitations and the design and the performance of the existing heat exchanger network. A case study shows that a reduction in energy consumption and operating costs of over 25% can be achieved.
Optimization of Heat-Integrated Crude Oil Distillation Systems. Part III: Optimization Framework
Industrial & Engineering Chemistry Research, 2015
This work presents a methodology for optimizing heat-integrated crude oil distillation systems. Part I of this threepart series presents a modeling strategy where artificial neural networks are used to represent the distillation process. Part II presents a new methodology to retrofit heat exchanger networks (HENs) and Part III presents the application of this distillation model to perform operational optimization of the crude oil distillation unit while proposing retrofit modifications to the associated HEN. Independent variables of the distillation model include flow rates of products, stripping steam, pump-around specifications, and furnace exit temperature. Dependent variables include those related to product quality, and temperatures, duties, and heat capacities of process streams involved in heat integration. The resulting neural network model is able to overcome convergence problems presented by rigorous or simplified models. Simulation time is significantly improved using neural networks, compared to rigorous models, with practically no detriment to model accuracy.
Simulation–Optimization-Based Design of Crude Oil Distillation Systems with Preflash Units
Industrial & Engineering Chemistry Research, 2018
Crude oil distillation systems are energy intensive processes. A crude oil distillation system typically comprises a preheat train, a preflash unit and an atmospheric distillation unit. Preflash units in a crude oil distillation system create opportunities to reduce demand for fired heating. This work aims to develop a new design approach to enhance production and to reduce energy consumption and operating cost. Existing design methodologies do not allow systematic design optimisation of crude oil distillation systems with preflash units. Thus, a systematic approach is proposed that exploits interactions between the separation units and the heat recovery system, while meeting product quality specifications. The optimisation framework applies a stochastic optimisation algorithm (simulated annealing) to minimise utility consumption by selecting optimal values for operational variables: stripping steam, pump-around duties, pump-around temperature drops, column feed inlet temperature and preflash temperature. An interface between Aspen HYSYS v8.6 and MatLab R2016a facilitates integration of modelling and optimisation. Heat recovery is systematically evaluated using pinch analysis (grand composite curve) to account for the impact of operational variables on energy demand. A case study demonstrates the capabilities of the approach and illustrates that implementing preflash units can reduce hot utility demand.
Exergy and economic analyses of crude oil distillation unit
The Journal of Engineering Research, 2015
Simulation of a crude distillation unit of a refinery is done using Aspen HYSYS V8.4 software. The exergy and economic analyses of the process are done using Microsoft Excel Spreadsheet and energy-capital costs trade-off approach, respectively. The results of exergy analysis showed that the crude distillation unit has the lowest exergy efficiency of 52.1% and highest irreversibility of 313670.11 kW. This is followed by the pre-flash drum and furnace with exergy efficiency of 74.1 and 75.1% and irreversibility of 195763.10 and 39259.06 kW, respectively. The economic analysis of the process for varying number of trays shows that the minimum number of trays for profitable operation of the plant is 40. It is concluded from the study that the economic operation of the process must consider improving the performance of the crude distillation unit and pre-flash drum and operating the process at practicable minimum number of trays.
Revamping of Crude Distillation Unit
This paper thoroughly discusses the revamping of an existing crude distillation unit. The main aim is to increase the capacity of the existing unit whilst keeping the energy consumption to a minimum so that the furnace isn’t bottlenecked, also the CO2 emissions and waste water are kept at authorized and environmentally regulated levels to keep this project as green as possible. This was mainly done by optimizing and adjusting the network of heat exchangers to reach a higher level of energy integration using pinch analysis in this revamping process. The work was reinforced by powerful simulation software Aspen HYSYS, Aspen Energy Analyzer and Aspen Exchanger Design and Rating. Energy efficiency has become an important feature in the design of process plants due to the rising cost of energy and the more stringent environmental regulations being implemented worldwide. In many countries most of the chemical plants were built during the era of cheap energy with little emphasis placed on energy efficiency due to the abundance of cheap utility sources such as coal and crude oil. This study applies the Pinch Technology approach to retrofit the heat exchangers network of the Crude Distillation Unit of a complex petroleum refinery with the aim to reduce utilities requirement and the associated gaseous pollutants emission.
Journal of Petroleum and Mining Engineering, 2021
Since the last few decades, global energy demand has steadily increased, creating a critical issue, particularly in the industrial sector. Energy conservation is an important issue in process design. Heat exchanger networks (HENs) synthesis have been the most studied in recent decades as its effect on energy recovery between process streams is significantly important. Pinch analysis and mathematical programming have been used for the synthesis of HENs. The proposed approaches can achieve the target of minimum utility consumption and develop networks to obtain a minimum number of heat exchange units. This paper presents a study to compare the performance of the heat exchanger network synthesized via pinch technology and mathematical programming for a crude oil plant. In addition, an application of a ready program like THEN is utilized to solve the problem. Based on the extracted data, the HEN is designed via the above-mentioned techniques, then, the results are analyzed and discussed...
Economic application of heat pumps in integrated distillation systems
Heat Recovery Systems and CHP, 1994
ABSTRACT The influence of relevant parameters on the economics of distillation plants involving distinct heat pump cycles is scrutinised and the results are compared to conventional and integrated schemes. On the basis of the COP, energy costs and efficiencies, simple expressions are proposed for preliminary economic analysis and design of heat pump assisted distillation. The influence of heat pump type, purity requirement, column pressure drop, feed rate, energy cost, relative volatility etc. on the energetic aspects and economic range of application is presented. Heat pumps can be economical substitutes for conventional distillation process design whenever direct refrigeration or chilled water are required for condensation and for separating close boiling mixtures in columns of small pressure drop. A design strategy for selecting the most economical distillation system, considering different types of heat pump structures (vapour recompression, bottom flash, closed cycle, absorption cycle), is proposed, based on pinch technology, primary energy rate, energy cost factor and estimated payback time of excess capital. The strategy is demonstrated by industrial case studies.
2018
In a heat-integrated crude oil distillation system with an atmospheric distillation unit and heat recovery system, pre-separation units (a preflash or prefractionator) can help to reduce the furnace duty and improve energy efficiency of the system. The high operating and equipment cost and complexity of the system motivate the development of systematic approaches for optimal design. The approach needs to consider both design of the distillation unit and the optimisation of operating conditions in the system, including those related to the preflash unit. This work introduces an optimisation-based methodology for the design of crude oil distillation systems with preflash units. The objective is to minimise fired heat demand of the system while meeting product quality and yield specifications, where pinch analysis is applied to estimate minimum utility requirements. A stochastic optimisation algorithm (a genetic algorithm) is applied to identify the feed location of the flash vapour, t...