Modelling and optimisation of oxidative desulphurization process for model sulphur compounds and heavy gas oil. Determination of Rate of Reaction and Partition Coefficient via Pilot Plant Experiment; Modelling of Oxidation and Solvent Extraction Processes; Heat Integration of Oxidation Process; Economic Evaluation of the Total Process.
AuthorKhalfalla, Hamza Abdulmagid
SupervisorMujtaba, Iqbal M.
Model sulphur compounds
Heavy gas oil
Rights© 2009 Khalfalla, H. A. This work is licensed under a Creative Commons Attribution-Non-Commercial-Share-Alike License (http://creativecommons.org/licenses/by-nc-nd/2.0/uk).
InstitutionUniversity of Bradford
DepartmentSchool of Engineering, Design and Technology
MetadataShow full item record
AbstractHeightened concerns for cleaner air and increasingly more stringent regulations on sulphur content in transportation fuels will make desulphurization more and more important. The sulphur problem is becoming more serious in general, particularly for diesel fuels as the regulated sulphur content is getting an order of magnitude lower, while the sulphur contents of crude oils are becoming higher. This thesis aimed to develop a desulphurisation process (based on oxidation followed by extraction) with high efficiency, selectivity and minimum energy consumption leading to minimum environmental impact via laboratory batch experiments, mathematical modelling and optimisation. Deep desulphurization of model sulphur compounds (di-n-butyl sulphide, dimethyl sulfoxide and dibenzothiophene) and heavy gas oils (HGO) derived from Libyan crude oil were conducted. A series of batch experiments were carried out using a small reactor operating at various temperatures (40 ¿ 100 0C) with hydrogen peroxide (H2O2) as oxidant and formic acid (HCOOH) as catalyst. Kinetic models for the oxidation process are then developed based on `total sulphur approach¿. Extraction of unoxidised and oxidised gas oils was also investigated using methanol, dimethylformamide (DMF) and N-methyl pyrolidone (NMP) as solvents. For each solvent, the `measures¿ such as: the partition coefficient (KP), effectiveness factor (Kf) and extractor factor (Ef) are used to select the best/effective solvent and to find the effective heavy gas oil/solvent ratios. A CSTR model is then developed for the process for evaluating viability of the large scale operation. It is noted that while the energy consumption and recovery issues could be ignored for batch experiments these could not be ignored for large scale operation. Large amount of heating is necessary even to carry out the reaction at 30-40 0C, the recovery of which is very important for maximising the profitability of operation and also to minimise environmental impact by reducing net CO2 release. Here the heat integration of the oxidation process is considered to recover most of the external energy input. However, this leads to putting a number of heat exchangers in the oxidation process requiring capital investment. Optimisation problem is formulated using gPROMS modelling tool to optimise some of the design and operating parameters (such as reaction temperature, residence time and splitter ratio) of integrated process while minimising an objective function which is a coupled function of capital and operating costs involving design and operating parameters. Two cases are studied: where (i) HGO and catalyst are fed as one feed stream and (ii) HGO and catalyst are treated as two feed streams. A liquid-liquid extraction model is then developed for the extraction of sulphur compounds from the oxidised heavy gas oil. With the experimentally determined KP multi stage liquid-liquid extraction process is modelled using gPROMS software and the process is simulated for three different solvents at different oil/solvent ratios to select the best solvent, and to obtain the best heavy gas oil to solvent ratio and number of extraction stages to reduce the sulphur content to less than 10 ppm. Finally, an integrated oxidation and extraction steps of ODS process is developed based on the batch experiments and modelling. The recovery of oxidant, catalyst and solvent are considered and preliminary economic analysis for the integrated ODS process is presented.
Showing items related by title, author, creator and subject.
A study of the prescribing, dispensing and administration of medicines with reference to medication errors in the Armed Forces Hospital, Kuwait. An experimental investigation to determine the accuracy of the prescribing process, dispensing process and nurse administration of medication as compared with the prescriptions of physicians in the Armed Forces Hospital in Kuwait.Naylor, Robert J.; Naylor, Ian; Al-Hameli, Fahad M. (University of BradfordDepartment of Pharmacy, 2010-11-23)Introduction: Medication errors are a major cause of illness and hospitalization of patients throughout the world. This study examines the situation regarding medication errors in the Armed Forces Hospital, Kuwait since no literature exists of any such studies for this country. Several types of potential errors were studied by physicians, nurses and pharmacists. Their attitudes to the commission of errors and possible consequences were surveyed using questionnaires. Additionally, patient medical records were reviewed for possible errors arising from such actions such as the co-administration of interacting drugs. Methods: This study included direct observations of physicians during the prescribing process, pharmacists while they dispensed medications and nurses as they distributed and administered drugs to patients. Data were collected and compiled on Microsoft Excel spreadsheet and analyses were performed using SPSS. Where applicable, results were reported as counts and/ or percentages of error rates. Nurses, pharmacists and physicians survey questionnaires: From the 200 staff sent questionnaires a total of 149 respondents comprising nurses (52.3%), physicians (32.2%) and pharmacists (16.1%) returned the questionnaires a total response rate of 74.5%. All responses were analyzed and compared item-by-item to see if there were any significant differences between the three groups for each questionnaire item. All three groups were most in agreement about their perception of hospital administration as making patient safety a top priority with regard to communicating with staff and taking action when medication errors were reported (all means 3.0 and p > 0.05). Pharmacists were most assured of administration support when an error was reported whereas nurses were least likely to see the administration as being supportive ( p < 0.001), and were more afraid of the negative consequences associated with reporting of medication errors (p = 0.026). Although nurses were generally less likely to perceive themselves as being able to communicate freely regarding reporting of errors compared to pharmacists there was no significant difference between the two groups. Both however were significantly different from physicians (p< 0.001). Physicians had the most favorable response to perceiving new technology as helping to create a safer environment for patients and to the full utilization of such technologies within the institution in order to help prevent medical errors. Scenario response - Responses to two scenarios outlining possible consequences, should a staff member commit a medication error, tended to be very similar among the three groups and followed the same general trend in which the later the error was discovered and the more grievous the patient harm, the more severe would be the consequences to the staff member. Interestingly, physicians saw themselves as less likely to suffer consequences and nurses saw themselves as more likely to suffer consequences should they have committed a medication error. All three groups were more likely to see themselves as facing dismissal from their job if the patient were to die. RESULTS OF ALL THREE OBSERVATIONS: Result of Nursing observations: For 1124 doses studied, 194 resulted in some form of error. The error rate was 17.2% and the accuracy was 82.8%. The commonest errors in a descending order were: wrong time, wrong drug, omission, wrong strength/ dose, wrong route, wrong instruction and wrong technique. No wrong drug form was actually administered in the observational period. These were the total number of errors observed for the entire month period of the study. IV Result of Pharmacist observations: A total of 2472 doses were observed during the one month period. Observations were done for 3 hours per day each day that the study was carried out. The study showed that there were 118 errors detected which were in the following categories respectively: 52 no instructions, 28 wrong drug/unordered, 21 wrong strength/dose, ignored/omission 13, shortage of medication 3 and expired date 1. Result of Prescribers in Chart review for drug-drug interactions: The analysis of the drug-drug interactions showed that out of a total of 1000 prescriptions, 124 had drug-drug interactions. None were found to fall into the highest severity rating i.e. 4 (contraindicated). Only twenty-one interactions were rated 3 (major), 87 interactions were rated moderate and 15 interactions were rated minor according the modified Micromedex scale. Patient education: All health care such as physician, pharmacist, and nurses have a responsibility to educate patient about their medication use and their health conditions to protecting them from any error can occur by wrong using drugs. Conclusion This study has contributed to the field of medication errors by providing data for a Middle Eastern country for the very first time. The views and opinions of the nurses, pharmacists and physicians should be considered to enhance the systems to minimize any errors in the future.
In-process monitoring of micromoulding - assessment of process variation.Whiteside, Benjamin R.; Coates, Philip D.; Martyn, Michael T. (2005)Advances in micromoulding technology are leading to complex,net-shape products having sub-milligramme masses with micro-scale surface features in a range of polymer and nano-composite materials.For such small components subjected to the extreme stress,strain-rate and temperature gradients encountered in the micromoulding process,detailed process monitoring is desirable to highlight variations in moulding conditions and assist in creating a viable manufacturing process with acceptable quality products.This paper covers the implementation of a suite of sensors on a commercial micromoulding machine and detailed computer monitoring during processing of a polyacetal component over a range of processing conditions.The results determined that cavity pressure curve integral data provides the most sensitive factor for characterisation of a moulding process of a 0.34 mm~3(0.49 mg)product.The repeatability of the process is directly compared with that of a 15.6mm~3(22.2 mg)product and shown to beinferior.DSC measurements of the whole products indicated little variation in average crystallinity of the products manufactured over a mould temperature range of 30 to 130deg C.
MSF process modelling, simulation and optimisation : impact of non-condensable gases and fouling factor on design and operation. Optimal design and operation of MSF desalination process with non-condensable gases and calcium carbonate fouling, flexible design operation and scheduling under variable demand and seawater temperature using gPROMS.Mujtaba, Iqbal M.; Said, Said Alforjani R. (University of BradfordSchool of Engineering, Design and Technology, 2013-11-27)Desalination is a technique of producing fresh water from the saline water. Industrial desalination of sea water is becoming an essential part in providing sustainable source of fresh water for a large number of countries around the world. Thermal process being the oldest and most dominating for large scale production of freshwater in today¿s world. Multi-Stage Flash (MSF) distillation process has been used for many years and is now the largest sector in the desalination industry. In this work, a steady state mathematical model of Multistage Flash (MSF) desalination process is developed and validated against the results reported in the literature using gPROMS software. The model is then used for further investigation. First, a steady state calcium carbonate fouling resistance model has been developed and implemented in the full MSF mathematical model developed above using gPROMS modeling tool. This model takes into consideration the effect of stage temperature on the calcium carbonate fouling resistance in the flashing chambers in the heat recovery section, heat rejection section, and brine heaters of MSF desalination plants. The effect of seasonal variation of seawater temperature and top brine temperature on the calcium carbonate fouling resistance has been studied throughout the flashing stage. In addition, the total annual operating cost of the MSF process is selected to minimise, while optimising the operating parameters such as seawater rejected flow rate, brine recycle flow rate and steam temperature at different seawater temperature and fouling resistance. Secondly, an intermediate storage between the plant and the client is considered to provide additional flexibility in design and operation of the MSF process throughout the day. A simple polynomial based dynamic seawater temperature and different freshwater demand correlations are developed based on actual data. For different number of flash stages, operating parameters such as seawater rejected flow rate and brine recycle flow rate are optimised, while the total annual operating cost of the MSF process is selected to minimise.The results clearly show that the advantage of using the intermediate storage tank adds flexible scheduling in the MSF plant design and operation parameters to meet the variation in freshwater demand with varying seawater temperatures without interrupting or fully shutting down the plant at any time during the day by adjusting the number of stages. Furthermore, the effect of non-condensable gases (NCG) on the steady state mathematical model of MSF process is developed and implemented in the MSF model developed earlier. Then the model is used to study effect of NCG on the overall heat transfer coefficient. The simulation results showed a decrease in the overall heat transfer coefficient values as NCG concentrations increased. The model is then used to study the effect of NCG on the design and operation parameters of MSF process for fixed water demand. For a given plant configuration (fixed design) and at different seawater and steam temperatures, a 0.015 wt. % of NCG results in significantly different plant operations when compared with those obtained without the presence of NCG. Finally, for fixed water demand and in the presence of 0.015 wt. % NCGs, the performance is evaluated for different plant configurations and seawater temperature and compared with those obtained without the presence of NCG.