Use of crude oil fouling threshold data in heat exchanger design

The existence of a `threshold' below which chemical reaction fouling of heat transfer surfaces by crude oil does not occur has been identified by Ebert and Panchal [Fouling Mitigation of Industrial Heat-Exchange Equipment, Begell House, 1997, 451–460] and clearly demonstrated by Knudsen et al. [Understanding Heat Exchanger Fouling and its Mitigation, Begell House, 1999, 265–272]. This phenomenon has important implications for the design and operation of heat exchangers in refinery pre-heat trains used for the processing of crudes. In this paper we show how a consideration of the fouling threshold condition can be incorporated into the design procedures for shell-and-tube heat exchangers. We then proceed to show how fouling can be mitigated through attention to heat exchanger design, particularly the choice of configuration. The cost of improperly designed units, based on the conventional use of `fouling factors', is demonstrated.     

Investigation of an alternative operating procedure for fouling management in refinery crude preheat trains

Crude oil atmospheric distillation in petroleum refineries involves a heat exchanger network to heat the crude using hot side streams and pumparounds. This energy integration reduces the furnace load as well as the cold utility consumption, diminishing fuel costs and carbon emissions. During the operation, the effectiveness of the heat exchangers decreases due to fouling. This paper deals with preheat trains composed by multiple parallel branches, where it is investigated an alternative operating policy based on the optimization of stream splits, aiming to manipulate the flow rates according to the fouling status of the existent heat exchangers. The performance of the proposed approach is illustrated by three examples: two networks from the literature and one real network from a Brazilian refinery.     

Neuro-based formulation to predict fouling threshold in crude preheaters

For preheat exchangers of a crude distillation unit (CDU), operating in conditions such that fouling minimized is crucial. A number of semi-empirical models called “threshold fouling models” were developed by various researchers to predict crude oil fouling behavior in crude preheaters of CDUs. In this study, an artificial neural network (ANN) model has been employed to develop a set of mathematical formulations to identify regions where there is less/no fouling. The comparisons between results of the developed neuro-based formulation and three threshold fouling models showed the use of neuro-based model resulted in significant improvements in terms of predicting crude oil fouling behavior of various laboratory and plant data. The approach of developing neuro-based models to predict fouling behavior can be readily applied in CDUs to identify more accurate fouling/no-fouling operating zones leading to an enhancement in the operation of crude preheaters.     

Simulation,exergy analysis and application of diabatic distillation to a tertiary amyl methyl ether production unit of a crude oil refinery

This paper presents the results of a detailed exergy analysis of a tertiary amyl methyl ether (TAME) unit of a crude oil refinery and the application of diabatic distillation to the depentanizer tower of the unit. Diabatic distillation is a separation process in which heat is not only supplied to the reboiler and extracted from the condenser [as in a conventional (adiabatic) distillation column], but is also transferred inside the column. The process enables operation to approach equilibrium conditions, thus reducing exergy losses and increasing exergy effectiveness. In a TAME unit of a refinery, isoamylenes are converted to TAME. Before transforming the isoamylenes in the reactors, it is necessary to recover them from a catalytic gasoline stream by a depentanization process. The exergy losses of this depentanization process represent about 70% of the total exergy losses of the unit. The results of the exergy analysis of the TAME unit are presented and a detailed exergy analysis of the conventional adiabatic depentanizer column is conducted for comparison purposes. Then, the application of diabatic distillation to the system is evaluated by using cooling water circulating in series from tray to tray in the rectification section and by making the steam emanating from the reboiler circulate in series from tray to tray in the stripping section. The results in terms of the reduction of exergy losses, heating and cooling media flow rates, and cost effectiveness of the diabatic option for the depentanizer section of the plant are compared to the original adiabatic system, and the effect of the diabatization on the overall exergy performance parameters of the depentanizer section and on the whole TAME unit, are presented in this paper.     

Scheduling cleaning in a crude oil preheat train subject to fouling: Incorporating desalter control

Fouling is a serious operating problem in oil refinery distillation preheat trains (PHTs) as the reduction in heat transfer effectiveness not only reduces the overall rate of heat transfer but also causes difficulty in maintaining key temperatures in the network within their defined operating envelopes. This work considers the problem of controlling the desalter inlet temperature by using hot stream bypassing, within a PHT fouling mitigation strategy based on heat exchanger cleaning. The formulation of the problem is incorporated in the PHT simulator described by Ishiyama et al. (2009) [1]. The methodology is illustrated using a case study based on an industrial network subject to fouling, where the fouling rates of heat exchangers were extracted through a data reconciliation exercise. The case study scenarios suggest that our simulation-based tool should be effective in controlling desalter inlet temperature within a fouling management strategy.     

Energy and environmental sustainability assessment of a crude oil refinery by thermodynamic analysis

This study presents the assessment of energy and environmental sustainability metrics for a crude oil refinery consisting of three distillation columns. The assessments of the current operation and the retrofits for possible improvements are suggested by the thermodynamic analysis and energy analyzer. The main objective is to explore the scope of reducing the thermal energy consumption and CO₂ emissions for a more sustainable refinery operation. Thermodynamic analysis is carried out by using the thermal analysis capability of ‘column targeting tool’ to address the ‘energy intensity metrics’ and the ‘energy analyzer’ to design and improve the performance of the heat exchanger network system for process heat integration. Environmental pollution impact metrics are estimated from the ‘carbon tracking’ options with a selected CO₂ emission data source of US‐EPA‐Rule‐E9‐5711 and using crude oil as a primary fuel source for the hot utilities. The results indicate that column targeting tool, energy analyzer, and carbon tracking can estimate the energy and environmental sustainability metrics of an existing design and determine the scope of considerable improvements for reducing the costs of thermal energy required and emissions of carbon dioxide in a crude oil refinery operation. Copyright © 2015 John Wiley & Sons, Ltd.     

Modeling and optimization of an industrial hydrogen unit in a crude oil refinery

The main goal of this research is the modeling and optimization of an industrial hydrogen unit in a domestic oil refinery at steady state condition. The considered process consists of steam methane reforming furnace, low and high temperature shift converters, CO₂ absorption column and methanation reactor. In the first step, the reactors are heterogeneously modeled based on the mass and energy balance equations considering heat and mass transfer resistances in the gas and catalyst phases. The CO₂ absorption column is simulated based on the equilibrium non-ideal approach. In the second step, a single objective optimization problem is formulated to maximize hydrogen production in the plant considering operating and economic constraints. The feed temperature, firebox temperature, and steam flow rate in the reformer, feed temperature in shift converters, lean amine flow rate in the absorption column, and feed temperature in the methanator are selected as decision variables. The calculated effectiveness factors and mass transfer coefficients prove that the methane reforming is inertia-particle mass transfer control, while shift and methanation reactions are surface reaction control. The simulation results show that applying the optimal condition on the system increases hydrogen production capacity from 85.93 to 105.5 mol s⁻¹.     

The ACEGES laboratory for energy policy: Exploring the production of crude oil

An agent-based computational laboratory for exploratory energy policy by means of controlled computational experiments is proposed. It is termed the ACEGES (agent-based computational economics of the global energy system). In particular, it is shown how agent-based modelling and simulation can be applied to understand better the challenging outlook for oil production by accounting for uncertainties in resource estimates, demand growth, production growth and peak/decline point. The approach emphasises the idea that the oil system is better modelled not as black-box abode of ‘the invisible hand’ but as a complex system whose macroscopic explananda emerges from the interactions of its constituent components. Given the estimated volumes of oil originally present before any extraction, simulations show that on average the world peak of crude oil production may happen in the broad vicinity of the time region between 2008 and 2027. Using the proposed petroleum market diversity, the market diversity weakness rapidly towards the peak year.     

The energy efficiency of crude oil refining in Brazil: A Brazilian refinery plant case

This article evaluates energy efficiency in Brazilian crude oil refining in comparison with the crude oil refining in the United States between 1930 and 2008. It aims to show that increased refinery complexity reduces the energy consumption of products of high value added. Moreover, the article shows that improvements in energy efficiency result in higher quality products and increased processing of oil. A Brazilian refinery with a capacity of 157,000 barrels per day (kbpd) was modernized in 2008 at a cost of US $1.3 billion. As a result, its capacity increased by 17%, from 157 to 189 kbpd. Its complexity index also rose from 3.2 to 6.8, allowing an improvement in the EII (energy intensity index) from 110% to 93%. In relation to the crude oil processed before being modernized, energy consumption fell from 0.75 to 0.52 MBtu (million British thermal units) per barrel processed. These proceedings show that increases in complexity reduce the energy consumed in the production of final products with high value added, such as gasoline, diesel and jet fuel.     

Nonparametric panel data model for crude oil and stock market prices in net oil importing countries

This paper introduces an innovative nonparametric panel data approach to model the long-run relationship between the monthly oil price index and stock market price indices of ten large net oil importing countries; namely, the United States, Japan, China, South Korea, India, Germany, France, Singapore, Italy and Spain. In the proposed model, we allow the coefficient on the oil price index to be a time-varying function which evolves over time in a way that is assumed to be unknown. We also allow the common trend function to evolve over time, as well as extending the model further to incorporate country-specific trend functions. We employ a data-driven local linear method to estimate these time-varying trend and coefficient functions. The results show that, despite being largely positive, there are several downward trends, reflecting the aftermath of the Iraq war and the recent unprecedented drop in the oil price. Overall, we find that the nonparametric panel data model better captures the way in which the underlying stock-oil price relationship has evolved over time in comparison to the point estimates of the parametric counterpart. Moreover, we find that stock market fundamentals play a significant role in determining the oil-stock price relationship. Our findings have important implication for policymakers and financial speculators.     

Beyond one-step-ahead forecasting: Evaluation of alternative multi-step-ahead forecasting models for crude oil prices

An accurate prediction of crude oil prices over long future horizons is challenging and of great interest to governments, enterprises, and investors. This paper proposes a revised hybrid model built upon empirical mode decomposition (EMD) based on the feed-forward neural network (FNN) modeling framework incorporating the slope-based method (SBM), which is capable of capturing the complex dynamic of crude oil prices. Three commonly used multi-step-ahead prediction strategies proposed in the literature, including iterated strategy, direct strategy, and MIMO (multiple-input multiple-output) strategy, are examined and compared, and practical considerations for the selection of a prediction strategy for multi-step-ahead forecasting relating to crude oil prices are identified. The weekly data from the WTI (West Texas Intermediate) crude oil spot price are used to compare the performance of the alternative models under the EMD–SBM–FNN modeling framework with selected counterparts. The quantitative and comprehensive assessments are performed on the basis of prediction accuracy and computational cost. The results obtained in this study indicate that the proposed EMD–SBM–FNN model using the MIMO strategy is the best in terms of prediction accuracy with accredited computational load.     

特型管换热器在炼油及石化工业上的应用

文章主要介绍T形翅片管高效强化换热器的研制和工程应用效果。特别介绍了T形翅片客小试及工业试验、计算数模的使用范围，并阐述了特型管换热器在石化生产传热过程中的应用和所取得的良好节能节资效果及在生产装置扩能改造解除“瓶颈”中发挥的作用。     

机油光谱数据的分析及在故障诊断中的应用

介绍了机油光谱数据处理和分析的方法，建立柴油机摩擦副主要元素的趋势变化图，形成故障诊断标准。为方便、可靠地处理油液监控数据提供科学依据，以动态标准监控柴油机的状况和发展变化趋势。     

稠油废水降膜蒸发的传热与垢阻

为彻底解决稠油开采带来的废水问题,设计降膜蒸发的实验方案。建立传热系数的物理模型和实验测定的方案,从理论和实验两方面研究稠油废水在降膜蒸发浓缩过程中,传热系数和垢阻的关系。实验结果表明:稠油废水蒸发过程中,蒸发器的传热系数随着蒸发负荷的升高,变化比较小;蒸发器的垢阻受废水线速率和传热温差的影响比较大;传热系数的模型考虑到蒸发侧垢阻的影响是合理的。在选定好阻垢剂的前提下,宜将蒸发负荷控制在20L/(m2·h),线速率控制在1.5~2.0L/(m·s)。     

The dynamics of a nonlinear relationship between crude oil spot and futures prices: A multivariate threshold regression approach

This paper segments daily data from January of 1986 to April of 2007 into three periods based on certain important events. Both periods I and II indicate that the spot prices in general are higher than futures prices as was well-known in the literature. Only period-III (2001/9/11–2007/4/30) displays a reverse phenomenon: futures prices, in general, exceed spot prices. When the absolute value of a basis (futures-spot) is greater than the threshold value in the arbitrage area (regime 1 and 3), at least one of the error correction coefficients, representing adjustment towards equilibrium, is statistically significant. That is, there exists a tendency in the oil market in which prices move toward equilibrium. With respect to the short-run dynamic interaction between spot price change (Δs_t) and futures price change (Δf_t), our results indicate that when the spot price is higher than futures price, and the basis is less than certain threshold value (regime 3), there exists at least one causal relationship between Δs_t and Δf_t. Conversely, when the futures price is higher than spot price and the basis is higher than certain threshold value (regime 1), there exists at least one causal relationship between Δs_t and Δf_t. Finally, we use the method suggested by Diebold and Mariano [Diebold, Francis X., Mariano, Roberto S., 1995. Comparing predictive accuracy. Journal of Business and Economic Statistics 13 (3), 253–263] to compare the predictive power between the linear and nonlinear models. Our empirical results indicate that the in-sample prediction of the nonlinear model is clearly superior to that of the linear model.     

A policy-impact model for the supply of depletable resources with applications to crude oil

In the exploitation of many depletable resources, two separate investment activities can be distinguished that must take place if production is to continue in an orderly fashion: exploration and development. This paper describes a quasi-equilibrium model for these activities, based on competitive behavior within the industry, on slowly rising exploration costs, and on a price-inelastic demand. It is shown that if, with advancing depletion, exploration costs rise markedly and development costs relatively less, a little-recognized user cost arises that can be quantified. This user cost engenders a rental that may exert an even stronger upward pressure on the price of the extracted resource than the better known scarcity rent.The model is useful for examining the evolving characteristics of an extractive industry as the resource declines, such as price, life-reserve index, and investments in exploration and development. It can also be used to predict industry behavior if the price is externally influenced, e.g. by government regulation, by foreign cartel-controlled imports, or through a “back-stop technology” that sets a future ceiling on price.The domestic crude oil industry is used as an example. It is shown that if backstop technologies turn out to be high-priced (e.g. $25 per bbl equivalent), their commercial feasibility may be further off than generally realized. Moreover, their advent may be preceded by a period of enormously burdensome investment needs in the declining crude oil industry, or by increasing dependence on foreign oil.     

型煤锅炉在油田原油加热中的应用

把型煤燃烧技术应用于原油加热,并在加热炉中采用高效相变换热技术,达到了节能和环保效果。采用自然通风燃烧,锅炉呈负压或微正压运行,不但安全可靠,同时避免了以往锅炉强制配风造成的配风过量,排烟热损失增大,或配风过小,不完全燃烧损失增大等问题。     

Pricing the (European) option to switch between two energy sources: An application to crude oil and natural gas

We consider a firm, which can choose between crude oil and natural gas to run its business. The firm selects the energy source, which minimizes its energy or production costs at a given time horizon. Assuming the energy strategy to be established over a fixed time window, the energy choice decision will be made at a given future date T. In this light, the firm's energy cost can be considered as a long position in a risk-free bond by an amount of the terminal oil price, and a short position in a European put option to switch from oil to gas by an amount of the terminal oil price too. As a result, the option to switch from crude oil to natural gas allows for establishing a hedging strategy with respect to energy costs. Modeling stochastically the underlying asset of the European put, we propose a valuation formula of the option to switch and calibrate the pricing formula to empirical data on a daily basis. Hence, our innovative framework handles widely the hedge against the price increase of any given energy source versus the price of another competing energy source (i.e. minimizing energy costs). Moreover, we provide a price for the cost-reducing effect of the capability to switch from one energy source to another one (i.e. hedging energy price risk).     

Short-run and long-run elasticities of import demand for crude oil in Turkey

The aim of this study is to attempt to estimate the short-run and the long-run elasticities of demand for crude oil in Turkey by the recent autoregressive distributed lag (ARDL) bounds testing approach to cointegration. As a developing country, Turkey meets its growing demand for oil principally by foreign suppliers. Thus, the study focuses on modelling the demand for imported crude oil using annual data covering the period 1980–2005. The bounds test results reveal that a long-run cointegration relationship exists between the crude oil import and the explanatory variables: nominal price and income, but not in the model that includes real price in domestic currency. The long-run parameters are estimated through a long-run static solution of the estimated ARDL model, and then the short-run dynamics are estimated by the error correction model. The estimated models pass the diagnostic tests successfully. The findings reveal that the income and price elasticities of import demand for crude oil are inelastic both in the short run and in the long run.     

Numerical investigation of gelled crude oil particle melting in water for hydrogen production

This paper describes a numerical analysis of the melting process of gelled crude oil in water for hydrogen production. The melting characteristics of crude oil particles are analyzed, and the influence of flow velocity, particle radius, and hot water temperature on the melting process is discussed. The results indicate that the melting rate on the surface of the crude oil is different, the oil particles do not melt concentrically, and the monitoring points and rate of increase in temperature are not substantially affected by the phase change interval. The flow rate and particle radius are found to have a significant influence on the phase distribution of the oil droplets, but changes in water temperature have little effect. After validating a model of the melting process, we investigate the influence of oil particle size, water temperature, flow rate, and oil temperature. It is found that increases in water temperature and flow rate, or a decrease in oil particle size, tend to reduce the melting time.