Crude Unit Research Articles

Experimental Assessment of Corrosion Properties for Materials Intended for Heavy Crude Processing

Heavy crude oil processing presents significant challenges owing to its complex composition and requirement for processing conditions, which increase the process safety risk in crude processing units, such as fixed equipment, for instance pressure vessels and pipes. The aim of this work is to evaluate the influence of heavy crude oils named A and B and the effect of sulfur-rich compounds and organic acids on the performance at high temperatures of three metallic alloys (5Cr-1/2Mo/ASTM A335GP5, X6CrNiMoTi17122/AISI-SAE 316Ti and Ni66.5Cu31.5/Monel 400) and propose an alternative to be used in pressure vessels and piping in refineries. This work was based on the need to understand the corrosivity of two heavy crude oils (A and B) from eastern Colombia in three materials, evaluated at three temperatures (200 °C, 250 °C and 300 °C) under the same conditions of pressure (200 psi) and rotation velocity (600 rpm) in a dynamic autoclave to simulate atmospheric conditions and conditions in vacuum refinery towers. An understanding of how these factors interact with the fundamental principles of corrosion kinetics is essential for developing an effective corrosion mitigation strategy. The results were interesting for applications requiring high corrosion resistance. X6CrNiMoTi17122/AISI-SAE 316Ti is a solid candidate for this application, with corrosion rates of 0.2 to 0.87 mpy. Ni66.5Cu31.5/Monel 400 exhibited significant corrosion rates up to 74.89 mpy, especially at higher temperatures (300 °C). 5Cr-1/2Mo/ASTM A335GP5 showed a generally moderate corrosion rate (2.04–5.57 mpy) in the evaluated temperature range.

Evaluating the efficiency of oil waste treatment plant in AL- Qayyarah Refinery - Iraq

The study included an evaluation of the efficiency of AL-Qayyarah refinery oil waste treatment plant. For this purpose, monthly samples were collected for a period of six months from October 2023 until March 2024, the first station (before treatment) represents the water coming out of the crude oil filter units. As for the second station (after treatment) it is located in the refinery waste treatment unit, the site represents the treated water. many physical and chemical tests were conducted on water, they ranged of temperature values ​​before the treatment ranged between (17-33) compared to its value after the treatment (15-31), and the electrical conductivity values ​​before the treatment ranged between (295-405)µS/cm, while after the treatment it was (349-471)µS/cm. As for total dissolved solids, their average before the treatment was(182.5)mg/L, while their average after the treatment was(194.6)mg/L as for salinity, its values ​​ranged between(0.7-0.75) mg/L before the treatment and between (0.6 -0.8) mg/L after the treatment ,pH value before the treatment was between)6.12- 7.91( compared to its value after the treatment as it ranged between (6.81-7.95), while the values ​​of the chemical requirement for oxygen before the treatment were (85108)mg/L, Their concentrations values ​​after the treatment amounted to(73_125) mg/L, and polycyclic aromatic hydrocarbons (PAHs) (73.46-155.17) mg/L before the treatment, and after the treatment it reached (35.53-52.53) mg/L, while oils and greases reached values ​​that ranged between (26.16-165.68) mg/L before the treatment compared to their results after the treatment which ranged between (94.15-23.18)mg/L. Finally, the total organic carbon had an average value before treatment (134.1) mg/L, while after treatment their average values ​​reached (120.8) mg/L

Development of a New Method to Optimize Operations of an Existing Crude Unit

A nonlinear optimization method working with the Simplex Method was developed to find optimum operating conditions of a crude oil distillation unit subject to defined process constraints, product specifications and prevailing market conditions. Then the method was applied to a commercial crude unit. This crude unit was modeled using Aspen Hysys V12.1 process simulation software. Two sets of market scenarios designated as the maximum gasoline scenario and minimum gasoline scenario were applied to the simulation model. It was found that the model minimized naphtha production and maximized kerosene production for minimum gasoline scenarios where the price of kerosene and diesel products were higher than naphtha products. Similarly, the model maximized the naphtha product yield for the maximum gasoline scenario where the naphtha price exceeds the mid-distillate product price. The iterative procedure developed for the study monotonically converged to optimum operating conditions for both market scenarios. It was observed that the optimization scheme developed in this study could generate a significant profit increase in the conventional crude unit investigated in this study without and capital investment.

Выращивание суданской травы на дерново-подзолистых песчаных почвах в условиях радиоактивного загрязнения

The results of three years of field research on the effect of potash fertilizers on the yield of green and haylage and the quality indicators of Sudanese grass are presented. The yield of green mass of Sudanese grass in the experiment was 10.3–12.2 t/ha, grain haylage — 9.4–11.0 t/ha, depending on the dose of potassium fertilizers. The maximum yield of green mass and grain haylage of Sudanese grass was noted in the variant with the addition of K240. The highest collection of crude protein (214.1 kg/ha), feed units (1.37 thousand) and metabolizable energy (21.3 GJ/ha) and the content of metabolizable energy per 1 kg of feed (8.0 MJ) were noted in the variant with the addition of potassium at a dose of 240 kg/ha. The content of crude protein in green mass increased with increasing potassium dose. The highest content of 137Cs (224 Bq/kg) was observed in the control variant. Potassium fertilizers reduced the entry of radionuclide into the crop. In general, according to the experiment, the content of 137Cs in the feed did not exceed the permissible level (400 Bq/kg).

Development of crude oil desalination unit by using solar flat plate collectors

To date, two-thirds of the world's crude oil reservoirs need desalination treatment to remove the salt content of crude oil. Ensuring the quality of produced crude oil shows the critical need for desalting units. But, these plants are one of the high-energy consuming processes, especially in the indirect-fired heaters. In this concern, exergy analysis investigated the thermodynamic efficiency of the plant's equipment. Aspen Hysys, and Matlab software are used for simulating and calculating the integrated system based on solar flat plate collectors. Based on exergy analysis, the most inefficient equipment are the skimmer tank, and dual indirect fired heaters by 680, 262 and 216 kW, respectively. Regarding the high rate of exergy destruction in the indirect fired heaters, implementing solar flat plate collectors as alternative equipment that is economically affordable was considered. The desalination unit has significant potential for using solar flat plate collectors, as determined by key solar characteristics such as temperature, clearness index, and daylight length. Mathematical modeling shows that maximum solar irradiation was attained at altitude angle (31°). The economical optimal area was assessed based on the life cycle saving cost parameter. After obtaining the optimal area, it was found that using 52000 m2 of solar flat plate can supply a proper substitute for inefficient heaters. A comprehensive economic analysis of this proposed plan is based on effective indicators, such as purchase side costs, maintenance costs, and fuel inflation rate. The economic results show that the investment cost will be reimbursed 14 years after start-up. This optimum area can reduce CO2 emission of heaters up to 83 %.

Dynamic risk assessment of chemical process systems using the System-Theoretic accident model and process approach (STAMP) in combination with cascading failure propagation model (CFPM)

To maintain continuous production, chemical plant operators may ignore faults or handle faults online rather than shutting down process systems. However, interaction and interdependence links between components in a digitalized process system are substantial. Thus, faults will be propagated to downstream nodes, potentially leading to risk accumulation and major accidents. However, limited attention has been paid to this type of risk. To model the risk accumulation process, a dynamic risk assessment method is proposed by integrating the system-theoretic accident model and process approach (STAMP) and the cascading failure propagation model (CFPM). Firstly, STAMP is used to model and analyze the system safety of a process system. Two CFPMs are then proposed to measure risk accumulation under two different engineering situations. The proposed method is applied to the Chevron Richmond refinery crude unit and its associated upstream process. The results show that the proposed approach can effectively quantify the process of risk accumulation. This method can generate a real-time dynamic risk profile to support auxiliary decision-making.

Environmental impact of fouling for crude oil flow in preheat pipes according to oil blends

Crude oil fouling is a complex process caused by multiple mechanisms. This study examined fouling's environmental impact on a distillation unit's heating tubes and heat exchangers, proposing optimal pollution levels to reduce emissions and achieve sustainability goals. The study evaluated five crude oil blends in terms of API, sulphur, salt content, and other physical properties. Contaminated water was analyzed through biological and chemical means, while CO2, NOx, and SOx emissions were calculated from actual fuel and power consumption. Solid and sludge sediments were observed throughout all plate heat exchangers, consisting primarily of iron hydroxides and manganese oxides. Rationalizing energy use reduced the burden on the environment and fuel consumption by 7 %, with a 2 % reduction in energy needed to refine crude oil feeding units when fouling is removed after maintenance. By optimizing pollution levels and reducing energy consumption, the environmental impact of fouling can be mitigated.

A method for the early prediction of abnormal conditions in chemical processes combined with physical knowledge and the data-driven model

In a chemical process, abnormal conditions may lead to process fluctuations or unplanned shutdowns, resulting in serious economic losses and even safety accidents. Early prediction of abnormal conditions can provide sufficient response time for operators to maintain the smooth operation of the device. This paper proposes an early prediction method for abnormal conditions in chemical processes combining physical knowledge and the data-driven model, which effectively enhances the model's generalizability and interpretability. Firstly, the key variable of abnormal conditions is determined based on physical knowledge. Then, the Spearman ranking correlation coefficient (SRCC) is utilized to extract feature variables related to the key variable. Next, a multivariate time series forecasting model combining long short-term memory (LSTM) and gated recurrent unit (GRU) is constructed to predict future trends of key variable data. Finally, taking the abnormal condition of crude oil with water in the crude unit (CU) as an example, the proposed method is successfully applied, showing better prediction performance and providing operators with sufficient time to take action.

On the installation effects of open ended piles in chalk

Chalk is a highly porous rock formed by cemented calcite grains. It covers areas of the UK and is widespread under the North Sea where offshore wind turbines (OWT) are currently being installed and where future offshore expansion will be sited (Figure 1(a)) [1]. Large piles are often driven in chalk to support OWT. The installation process causes the intact rock below the pile tip to crush into a putty characterised by a mechanical behaviour very different from the intact chalk. The difficulty to predict the final state of the putty and the stress around the pile after installation is the underlying reason for inadequate current design guidance for piles in chalk. Considering that for OWT, foundations account for 20-25% of the total development cost , pile design improvements in chalk, would be extremely beneficial from an economical and environmental perspective.
 Current guidelines for the design of piles in chalk (CIRIA C574) originate from the analysis of a limited number of pile tests [2]. These guidelines suggest crude average ultimate unit shaft friction (tsf) design values of between 20 and 120 kPa for low-medium density and high/very-high density chalk, respectively. tsf estimates are thought to be conservative hence introducing significant increases in cost and carbon footprint (Figure 1(b)). Reducing the level of conservatism (e.g. enabling more confident use of higher tsf) would reflect in significant savings of steel and consequent reduction of the cost and embodied carbon. Such design considerations are possible but require a better understanding of the long-term mechanical behaviour of the damage processes intact chalk experiences during dynamic installation in hydro-mechanical (HM) coupled conditions.
 In this work the coupled HM effects developing during pile installation in chalk are investigated numerically using a robust and mesh-independent implementation of an elasto-plastic constitutive model at large strains. The model, implemented into an open-source Geotechnical Particle Finite Element (G-PFEM) code [3], is shown to be able to capture the damage of the rock until the formation of a chalk putty layer around the shaft of a model piles jacked in chalk. In particular the complex flow processes occurring in the soil around both open and closed ended piles of variable shape jacked into saturated chalk are investigated. A fully coupled hydro-mechanical formulation, based on regularized, mixed low-order linear strain triangles is used [5]. To capture the relevant features of the mechanical response of chalk, a finite deformation, non-associative structured modified cam clay is used [6]. The model formulation is based on a multiplicative decomposition of the deformation gradient and on the adoption of an elastic response based on the existence of a suitable free energy function. Bonding-related internal variables, quantifying the effects of structure on the yield locus, are used to provide a macroscopic description of mechanical destructuration effects. To deal with strain localization phenomena, the model is equipped with a non-local version of the hardening laws [7]. The G-PFEM model is shown to be capable of capturing the destructuration associated with plastic deformations below and around the pile shoulder; the space and time evolution of pore water pressure as the pile advances; the effect of soil permeability on predicted excess pore water pressures, and the effect of chalk putty formation on predicted values of the load displacement curve. Installation effects are highlighted by comparing the axial performance between wished in place piles and piles which considered the full installation process.

Parametric optimization of a crude oil treatment unit to maximize oil production

Early production in oil fields can cause problems related to oil specifications in the existing process unit, especially in the stabilization tower. This study aims to improve the performance of a crude oil treatment unit for an Iranian oil field. The process involves a two-stage desalting unit followed by a stabilizer tower. First, the desalting process was modeled using the population balance equation in MATLAB. Then, the whole process was simulated by linking the numerical code and simulator. The effective parameters of the desalting process were determined by sensitivity analysis. In this research, the desalting and stabilization units were simultaneously optimized due to the existing interactions between the desalters and the stabilizer tower. The goal is to maximize the oil production, optimizing the variables of pressure drop of the mixing valves, electric field intensity, wash water flow rate of the first and second desalters, and the operating temperature of the first desalter. The maximum allowable salt and water contents in the oil entering the stabilizer are 10 PTB and 0.1 %, respectively, considered as optimization constraints. Optimizing the whole process by Genetic Algorithm, the oil production increased by 413 bbl/d (0.68 %) compared to the existing condition.

A virtual experiment for measuring system resilience: A case of chemical process systems

Resilience is an emergent property of a system, which changes with various internal and external factors. Resilience is also a hidden property of a system that cannot be observed. Thus, experiments should be performed for a given system to measure its resilience. However, physical experiments are practically impossible. Inspired by the tensile test for the stress-strain curve in Material Science, this paper proposes a virtual experiment for measuring system resilience and applies it to a chemical process system. The physical parameters of system resilience of a process system are mapped to those of material resilience. A process system is viewed as a 'specimen' in this experiment. The system performance variation caused by disruptions is seen as the displacement of the specimen caused by the applied load. In absorption phase, the decrease speed of system performance is determined by the failure rate of components under disruptive condition. Response time, including fault diagnosis time and resource allocation time, is used to represent adaptation ability. Restoration ability depends on repair rate of components. For simplicity purpose, the proposed method is applied to resilience assessment of a release prevention barrier system used in the Chevron Richmond refinery crude unit and its associated upstream process.

Resilience-based approach to maintenance asset and operational cost planning

Reliability-based and risk-based methods for directing maintenance activities play a critical role in ensuring system safety and reducing unnecessary downtime. Those methods focus on preventive maintenance to avoid component failures and are applicable before unexpected disruptions occur. However, when disruptions are unavoidable, more attention should be paid to systems’ recovery from unwanted changes. As a remedy of preventive maintenance, improving system restoration capacity of resilience through optimizing the system's maintenance asset and operational cost is an efficient way to help system restore from disruption conditions within an optimal cost. In this paper, a resilience-based approach is proposed to optimize maintenance asset and operational cost. A novel resilience metric is developed and utilized to quantify system resilience under various restoration capacities. The minimal acceptable resilience level (MARL) and maximal acceptable restoration time (MART) are proposed to determine the optimal maintenance cost. The proposed approach is applied to the Chevron Richmond refinery crude unit and its upstream process. The results show that it can help practitioners identify the optimal cost to ensure a system is resilient to respond to uncertain disruptions and provide a dynamic resilience profile to support decision-making.

О природе меркаптанов, содержащихся в прямогонных фракциях реактивного топлива

Dependence of mercaptans content in straight-run jet fuel on process mode of column K-1 of crude oil processing unit is shown.When temperature of column K-1 increases the quantity of decomposing unstable sulfuric compounds is also increased, while the decomposition products - mercaptans and hydrogen sulfide are removed with gasoline fraction in column K-1 andunstable sulfur compounds in a lesser degree are moved to column K-2, which decreases the mercaptans content in straight-run kerosene. The comparison of mercaptans content in closed fractions of oil and straight-run jet fuel is performed. It is shown that their content in straight-run jet fuel is higher, and they come both from oil and as a result of decomposition processof unstable sulfur compounds, more likely, disulfides in the first place.

HAZOP Analysis in Terms of Safety Operations Processes for Oil Production Units: A Case Study

The Hazard and Operability Study (HAZOP) methodology is considered one of the most effective techniques for risk analysis, developed fundamentally to provide regular processes with reduced risks that aim to guarantee the safety of activities and the operability of the production units. The study aims to apply the HAZOP methodology in process and safety operations in the oil production industry. A crude oil production unit was divided into smaller sections that were analysed. By applying the HAZOP methodology, 71 possibilities of relevant risks were identified. The environmental, health and economic impacts were estimated to establish safeguard priorities for them. The application of this methodology and the defined safeguards generated 47 recommendations to mitigate the detected problems. The study contributions were to demonstrate the efficacies of HAZOP methodology to identify potential hazards and evaluate the potential hazards obtained for malfunctioning of equipment and property in terms of the resultant impacts either new or existing process facilities, and as a useful tool to provide essential knowledge for the companies’ leaders, decision-maker, and operations managers.

Process system analysis on oil processing facility and economic viability from oil well-to-tank

Hydrocarbon processing from extraction to the final product is an important aspect that needs an optimised technology for consumption-led market growth. This study investigated real data from the oil processing facility and analysed the simulation model for the entire crude oil processing unit based on the process system engineering aspect using Aspen HYSYS. The study mainly emphasises the process optimisation in processing the hydrocarbon for the maximum yield of the product with less energy consumption. The investigation also includes a thorough economic analysis of the processing facility. The datasets for oil properties are obtained from a modern petroleum refinery. The investigation comprises of varying transient conditions, such as well shutdowns using three oil reservoirs (low, intermediate, and heavy oil). The impact of various conditions, including process heating, well shutdown, oil combinations, presence of water on the production, is analysed. The results indicate that the factors involving crude oil processing are significantly affected by the process conditions, such as pressure, volume, and temperature. The vapour recovery unit is integrated with the oil processing model to recover the separator's gas. The optimisation analysis is performed to maximise the liquid recovery with Reid vapour pressure of 7 and minimum water content in oil around 0.5%. Economic analysis provided an overall capital cost of $ 9.7 × 106 and an operating cost of $2.1 × 106 for the process configuration. The model results further investigate the constraints that maximise the overall energy consumption of the process and reduce the operational cost.

Решение проблем высокотемпературной сернистой коррозии на установках первичной переработки нефти

This article reveals the influence of natural sulfur containing oil compounds on corrosion condition of equipment. It is described that the main reason of rapid increase of oil corrosion aggressiveness recently is application of reagents at the stage of oil extraction and transportation to bind hydrogen sulfide and mercaptans. Several solutions are suggested to solve the problem of high temperature sulfur corrosion on crude oil processing units with account of problematic zones isolation.

Prospects of millet crops cultivation for forage purposes in the non-black earth zone North-West area

The article deals with the issues of barnyard millet, Turkestan millet, foxtail millet, and proso millet cultivation in the Novgorod region conditions. In the three research years, positive results were obtained for all studied crops and varieties. Regarding climatic zone conditions, the duration of the period before harvesting ripeness, calendar harvest dates, and the level of the studied crops varieties herbage yield were identified. The herbage analysis for the content of crude protein, fiber, available energy, and feed units was conducted. It was established that the proso millet Sputnik and Regent varieties and foxtail millet Stepnoy Mayak variety ripen for seeds in the Novgorod region. The introduction of new crops in crop rotation will provide an opportunity to expand forage crops range and to strengthen the Non-Black Earth Zone forage base.

Corrosion prevention of crude and vacuum distillation column overheads in a petroleum refinery: A field monitoring study

AbstractThe aim of the present work is to monitor dew point corrosion of crude and vacuum distillation column overhead section in a petroleum refinery. The material of construction of overhead line pipe was carbon steel. The state of art of crude unit process was introduced. The corrosion and associated hydrolyzing mechanisms were briefly described. The crude processing in a petroleum refinery was extremely dynamic and thus field monitoring attempts were made, which provides some useful information on structural integrity of column downstream equipments. The demulsifier, neutralizer, and corrosion inhibitor were mixed in crude unit at specific locations for corrosion prevention. Field monitoring includes evaluation of pH and chloride content of desalter extracted water and overhead condensed water, Base Sediment & Water (BS&W) and chloride content of as‐received & desalted crude, and iron content of overhead condensed water. Furthermore, corrosion coupon was installed in overhead section to obtain the actual corrosion rate. All the field study was conducted for a specified period. The acidity, chloride concentration, and iron loss of condensed water confirmed that acidic corrosion was under control. The corrosion rate of the installed coupons confirmed that corrosion rate was within the specified limit. The results revealed in this paper intended for refinery operators and corrosion engineers involved in understanding of actual process parameters in prevention of overhead acidic corrosion.

Determination of Energy Efficiency Features of Oil Refinery Units and Their Complexes

The index of the process energy efficiency has been introduced to assess the energy efficiency of oil refinery units and their complexes. The index is calculated as the ratio of the payload difference of the hot utilities of the operational unit and the reference unit to the payload of the operational unit. As a reference unit, the examined unit is selected with a thermal energy recuperation system, which has a specified value of driving force for vertical heat transfer. This value of the minimum temperature difference of the heat transfer carrier in the heat-exchange equipment is selected using the best available technologies in heat transfer. Additionally, the energy efficiency index is calculated taking into account the elimination of heat losses to the environment. A simplified method for estimating heat losses from heated surfaces of oil refinery equipment has been developed for this purpose. It is shown that to determine the energy efficiency of a unit complex, it is possible to use the temperature Total Site profile. Indices of energy efficiency for crude oil unit, catalytic reforming with preliminary hydrotreating for the production of stable catalysis unit and hydrotreating of diesel fuel and kerosene unit, as well as their complex, are determined. Indices for economically optimal integration of these processes are decided. The introduced index of the energy efficiency potential of the process is an absolute value indicating the grade of the process perfection. The introduced index can be used to compare the energy efficiency of both individual units and plants.

What can be learned from crude intensive care unit mortality? Methodological implications

Demonstrate the practical range of information that can be obtained about ICU mortality/survival from limited administrative data. Prospectively collected administrative data (length-of stay, survival/mortality, referring service) from a university medical center's General ICU was subjected to retrospective analysis to demonstrate ways of presenting and analyzing mortality/survival information. 16,022 patients (87,624 patient-days) admitted over 23years were included. 28% of all deaths occurred on ICU day 1. When considering all admissions, mortality on ICU day 1 was 2%, while the overall crude mortality rate revealed that the chances of dying during an ICU stay was 8.6%. Mortality rates in the overall population steadily increased over ICU days 1-5, plateaued during days 6 to 50, decreasing after day 50. The general surgery subgroup had a similar pattern. This contrasted with the internal medicine subgroup where mortality steadily increased over the initial 14 ICU days then plateauing at rates of 40-50%. Simple calculations using the few variables found in administrative database enhanced information provided by the crude mortality rate and demonstrated that temporal patterns of mortality change as stay lengthens. These results highlight the limitations of just using overall crude mortality rates.