Treatment technologies for cooling water blowdown: A critical review

Cooling water blowdown (CWBD) generated from different industries and district cooling facilities contains high concentrations of various chemicals (e.g., scale and corrosion inhibitors) and pollutants. These contaminants in CWBD streams deem them unsuitable for discharge into surface water and some wastewater treatment plants. The pollutants present in CWBD, their sources, and the corresponding impacts on the ecosystem are discussed. The international and regional (Gulf states) policies and regulations related to contaminated water discharge standards into water bodies are examined. This paper presents a comprehensive review of the existing and emerging water treatment technologies for the treatment of CWBD. The study presents a comparison between the membrane (membrane distillation (MD), reverse osmosis (RO), nanofiltration (NF), and vibratory shear enhanced membrane process (VSEP)) and nonmembrane-based (electrocoagulation (EC), ballasted sand flocculation (BSF), and electrodialysis (ED)) technologies on the basis of performance, cost, and limitations, along with other factors. Results from the literature revealed that EC and VSEP technologies generate high treatment performance (EC~99.54% reduction in terms of silica ions) compared to other processes (membrane UF with reduction of 65% of colloidal silica). However, the high energy demand of these processes (EC~0.18-3.05 kWh/m3 and VSEP~2.1 kWh/m3) limit their large-scale applications unless connected with renewable sources of energy.Funding: This research is funded by Ministry of Municipality and Environment in Qatar, Project MME contract no. P2020/1.Scopu

Experimental study of optimizing control of continuous chromatographic separation process

This thesis introduced an improved single-column chromatographic (ISCC) separation process with the final objective to make this process distinct from existing single-column chromatographic separation processes by physical modifications and conceptual advances. The performance of this ISCC process was evaluated by experimental implementation to separate a mixture of guaifenesin enantiomers. In ISCC process, different standard HPLC peripherals were used as building blocks and some standard parts of the commercial HPLC system were redesigned to overcome the existing limitations for better performance. Fraction collection schemes and mechanism are the important features of this improvement. This fraction collection system allows accommodation of overlapped peaks from adjacent cycles and reduce the overall time delay of the process. These process design modification provide a wider degree of freedom: injection volume, cycle time, desorbent flow rate, feed concentration and fraction collection intervals. A robust online monitoring system was designed which was relatively inexpensive and was able to offer high frequency and accurate analysis of the samples compared to other devices. The proposed ISCC process was assembled in a laboratory and commissioned successfully. Process performance was optimized by a multi-objective stochastic optimization technique based on genetic algorithm (GA). The optimization problem was appropriately formulated with the aim of maximization of productivity and minimization of desorbent requirement. Performance of the ISCC process was also compared with a similar SMB process. This study provided the basis for reaping the full potential benefits of a single column process that adopts cyclic injection. Besides, relative contribution of the decision variables were ascertained through the study of their effects on the performance indicators. Detector calibration and determination of adsorption isotherm parameters were done simultaneously by adopting a new method named nonlinear direct inverse method, which is relatively fast, and economical technique compared to existing alternatives. A `cycle to cycle’ model predictive control (MPC) scheme was developed in-house to guarantee product and process specifications for obtaining optimized profitability. The performance of this MPC scheme was demonstrated through simulation studies. Finally, the cycle-to-cycle optimizing controller developed for the ISCC process for the separation of a mixture of guaifenesin enantiomers. Key implementation issues were accuracy of the online measurement system and integration and automation of the ISCC process with online measurement system and controller. This was achieved by designing and developing a human machine interface (HMI) that was able to effectively communicate among the three essential components of the control loop. The performance of the controller was tested for set point tracking and disturbance rejection. Results indicate that the designed ISCC process with the online monitoring system was able to run at the optimal operating conditions and deliver the product requirements as confirmed by open-loop and close-loop experiments.DOCTOR OF PHILOSOPHY (SCBE

Environmental sustainability through process integration, control and optimization

[No abstract available]Scopu

Environmental sustainability through process integration, control and optimization

[No abstract available]Scopu

Process safety and abnormal situation management

This review paper summarizes process safety aspects of abnormal situations and incidents in industrial facilities. Major accidents and their negative impacts on health, safety and environment have shown the importance of enhancing safety culture, understanding causes of abnormal situations and determine effective management strategies. Flaring is a safety industry practice to control and manage processes during normal and abnormal operations. This paper identifies current efforts made by industry and researchers toward better management of abnormal situation for flare reductions. These efforts came about because of current and impending environmental legislation. The paper finds that future strategies developed for ASM must consider safety as well as environmental and economic implications; and it highlights the challenges and future guidelines for safer abnormal situation management.This paper was made possible by NPRP grant No 6-678-2-280 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the author[s].Scopu

Crashworthiness optimization of composite hexagonal ring system using random forest classification and artificial neural network

This research aims to enhance the safety level and crash resiliency of targeted woven roving glass/epoxy composite material for various industry 4.0 applications. Advanced machine learning algorithms are used in this study to figure out the complicated relationship between the crashworthiness parameters of the hexagonal composite ring specimens under lateral compressive, energy absorption, and failure modes. These algorithms include random forest (RF) classification and artificial neural networks (ANN). The ultimate target is to develop a robust multi-modal machine learning method to predict the optimum geometry (i.e., hexagonal ring angle) and suitable in-plane crushing arrangements of the hexagonal ring system for targeted crashworthiness parameters. The results demonstrate that the suggested RF-ANN-based technique can predict the optimal composite design with high accuracy (precision, recall, and f1-score for test and train dataset were 1). Furthermore, the confusion matrix validates the random forest classification model's accuracy. At the same time, the mean square error value serves as the loss function for the ANN model (i.e., the loss function values were 2.84 × 10−7 and 6.40 × 10−7, respectively, for X1 and X2 loading conditions at 45° angle). Furthermore, the developed models can predict crashworthiness parameters for any hexagonal ring angle within the range of the trained dataset, requiring no additional experimental effort

Energy integration alternatives for effective use of waste heat associated with flaring during abnormal situation

This work reports a multi-objective optimization frame work for new/modified design solutions for energy integration to manage flares from uncertain sources during abnormal situation. It also suggests some energy integration alternatives for waste streams recovery, for combining heat and power through process integration and for flare gas utilization. This kind of robust optimization framework and energy integration alternatives are very important for utilizing unused resources of the process and for flare gas reduction. Although, governments and companies have had success in reducing flare gas with significant investments; global gas flaring has remained largely stable the past fifteen years in the range of 140-170 billion cubic meters (BCM) which is 5% of global gas production (Kazi et al., 2015). Therefore, much attention is still needed to mitigate and manage industrial flares by innovating green process engineering for sustainable energy and environment. Here, two sustainable energy integration alternatives are proposed and harnessed properly with process for flare management during abnormal situation. First one is cogeneration (COGEN) unit which has become a mainstream practice in different industries due to its high economic and energy-savings potentials. It can produce simultaneous heat and power from a single fuel source. If COGEN unit is designed properly some part of the flare streams can be used as fuel in the boiler instead of fresh fuel like NG. This will reduce the fresh fuel cost and will also increase the energy efficiency of the process itself. Moreover, it will reduce the carbon footprint from compensated fresh fuel. Another energy integration tool is thermal membrane distillation (TMD) unit, which is an emerging technology in the area of high-purity separation especially in water treatment (Elsayed et al., 2013). In TMD, low level heat like waste heat from process or COGEN unit can be used to create the driving force to separate pure water from the raw/waste water. Moreover, it needs small floor area for installation and it is modular in nature. By integrating TMD with the process, the utility costs and the waste water treatment cost can be reduced significantly. Produced water from TMD can be recycled in the process or sold to external users. Using cogeneration (COGEN) and thermal membrane distillation (TMD) unit with industrial processes can offer a potential scope of process and energy integration and can also offer the maximum utilization of flared gas streams. In this work, an ethylene base case study is solved to illustrate the applicability of the proposed optimization framework and the implementation of the proposed energy integration tools for flare management. In final output, the optimization framework provides several Pareto fronts to the policy makers. Therefore, the end user is able to make an informed choice of suitable design, operation conditions and process performances depending on economic, energetic and/or environmental considerations. The results of different scenarios demonstrate the benefits of integrating TMD and COGEN unit with the process plant for flare mitigation approach. It will ensure the maximum use of flared gas streams, reduction of cooling utility load and the creation of recycle/reuse opportunities for the treated waste water.Scopu

Inherently safer design tool (i-SDT): A property-based risk quantification metric for inherently safer design during the early stage of process synthesis

In this work, an Inherently Safer Design Tool (i-SDT) is presented for early stage process synthesis to characterize and track the risk associated with different life-cycle phases of industrial processes. It also helps to develop characteristic equations for different safety parameters (i.e., flammability, explosiveness, toxicity, etc.) under various operating conditions. This property-based inherent safety quantification metric is a tailor made semi-quantitative safety analysis tool which provides safety assessment in a continuous manner to overcome the subjective nature of the existing available safety metrics. The core of this design and safety assessment tool is probabilistic risk quantification using accident and incident investigation (with over 600 incidents and within 27 years of time span), a property integration model and an exponential curve fitting method. The proposed safety metric has the flexibility to operate by identifying the major accident-prone units/sections of a process, as well as the major safety and operating parameters. The final output of this i-SDT tool is a cluster safety parameter score (CSP) which provides insights regarding the investigated unit/section or process for carrying out inherent safer design using a very limited amount of process information. The developed i-SDT tool was applied to compare different technologies of Ammonia processes in order to assess the safer option in terms of risks associated with the accident-prone unit/section and to highlight the areas of safety improvement in any existing process using the inherent safer design principles. In the future, this metric can can be embedded into a techno-economic framework to perform the cost and safety analysis simultaneously using available materials, design and accident information. - 2018 Elsevier LtdThis paper was made possible by NPRP grant No 6-678-2-280 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the author[s]. The author thanks Ahmed AlNouss for his contribution in developing the necessary simulation models for the presented Ammonia case study.Scopu

Nonlinear direct inverse method: A shortcut method for simultaneous calibration and isotherm determination

This work addresses a way to combine isotherm determination and nonlinear calibration. In this method, like the classical inverse method, experimental elution profiles are compared with the results of a detailed model that accounts for nonlinearity in equilibrium, axial dispersion, and mass transfer kinetics. However, unlike the classical inverse method, the calibration of detector is carried out simultaneously with isotherm determination thereby reducing cost and saving time. In this study no limitation is imposed on the linearity of the detector signal or on the overlapping of elution profiles for the separation of enantiomers. The method has been experimentally validated for the separation of a mixture of guaifenesin enantiomers over a wide range of concentration.Scopu

Application of a property-based inherently safety quantification framework for integrating risk assessment into process safety life cycle

Process plant involves different types of risks which need to be managed appropriately to avoid dangerous incidents. Some risks are associated with design decisions such as choice of unit, chemicals or design layout etc. Some are related to the management of proper operating conditions within safely operational limits. It is advantageous to consider the safety aspects and to assess the risks associated with potential hazardous sources from the early stage of process safety life cycle to avoid unfavorable conditions and complexity on the later phase. Process safety metrics provide a good balance between sophisticated quantitative evaluation and simple application. The metrics can be easily adopted, enable comparison between different alternatives and be integrated in optimization for the supply chain. There have been multiple efforts to develop process safety metrics, which are made by both industrial and academic agencies. The concept of inherent safer design is very helpful to reduce the hazardous conditions by safer design principles instead of controlling them by add-on protective systems and procedures. Degree of freedom for the decision for inherently safer process design continuously decreases as life cycle proceeds. Therefore, changing plant design in a later stage will cost more than in the early stage. But the implementing of inherent safer design principles from early stage of design remains challenging due to the lack of proper tool/methodology which can assess the safety performance continuously with the change of mixture properties, operating conditions and even for the unit types. The significant challenges of the problem related to the safety parameters are the possible means to represent the associated results for different scenarios and processes. One safety parameter which is very important to a process may not be the critical issue for others. The scope to identify the key root safety parameters from the historical accidental data base can overcome this limitation. Again, most of the time it is very hard to do the techno-economic analysis simultaneously due to the lack of continuous equations to comply with the whole system's model. In this work, an Inherently Safer Design Tool (i-SDT) is presented for early stage process synthesis to characterize and track the risk associated with different life-cycle phases of industrial processes and products. It also helps to develop characteristic equations for different safety parameters (i.e., flammability, explosiveness, toxicity, etc.) and provides cluster safety parameter score for doing inherent safer design during early stage of design using very limited amount of process information. This property-based inherent safety quantification framework is a tailor made semi-quantitative safety analysis tool which will provide safety assessment in continuous manner to overcome the subjective nature of the existing available safety metric. The proposed safety metric has the flexibility to operate by identifying the major accident-prone units of a process, as well as the major safety and operating parameters. Therefore, in the future it can be embedded to any techno-economic framework to do the cost and safety analysis simultaneously using available materials, design and accidents information. The developed i-SDT tool was used to compare different technologies and variable capacity of ammonia processes to identify the safer alternative in terms of risks associated with the accident-prone unit/section and to highlight the areas of improvement in any existing process using the inherent safer design principles.Scopu