Mimi Haryani Hassim

Artificial neural networks: applications in chemical engineering

Abstract Artificial neural networks (ANN) provide a range of powerful new techniques for solving problems in sensor data analysis, fault detection, process identification, and control and have been used in a diverse range of chemical engineering applications. This paper aims to provide a comprehensive review of various ANN applications within the field of chemical engineering (CE). It deals with the significant aspects of ANN (architecture, methods of developing and training, and modeling strategies) in correlation with various types of applications. A systematic classification scheme is also presented, which uncovers, classifies, and interprets the existing works related to the ANN methodologies and applications within the CE domain. Based on this scheme, 717 scholarly papers from 169 journals are categorized into specific application areas and general (other) applications, including the following topics: petrochemicals, oil and gas industry, biotechnology, cellular industry, environment, health and safety, fuel and energy, mineral industry, nanotechnology, pharmaceutical industry, and polymer industry. It is hoped that this paper will serve as a comprehensive state-of-the-art reference for chemical engineers besides highlighting the potential applications of ANN in CE-related problems and consequently enhancing the future ANN research in CE field.

Understanding selected trace elements behavior in a coal-fired power plant in Malaysia for assessment of abatement technologies

The Proposed New Environmental Quality (Clean Air) Regulation 201X (Draft), which replaces the Malaysia Environmental Quality (Clean Air) 1978, specifies limits to additional pollutants from power generation using fossil fuel. The new pollutants include Hg, HCl, and HF with limits of 0.03, 100, and 15 mg/N-m3 at 6% O2, respectively. These pollutants are normally present in very small concentrations (known as trace elements [TEs]), and hence are often neglected in environmental air quality monitoring in Malaysia. Following the enactment of the new regulation, it is now imperative to understand the TEs behavior and to assess the capability of the existing abatement technologies to comply with the new emission limits. This paper presents the comparison of TEs behavior of the most volatile (Hg, Cl, F) and less volatile (As, Be, Cd, Cr, Ni, Se, Pb) elements in subbituminous and bituminous coal and coal combustion products (CCP) (i.e., fly ash and bottom ash) from separate firing of subbituminous and bituminous coal in a coal-fired power plant in Malaysia. The effect of air pollution control devices configuration in removal of TEs was also investigated to evaluate the effectiveness of abatement technologies used in the plant. This study showed that subbituminous and bituminous coals and their CCPs have different TEs behavior. It is speculated that ash content could be a factor for such diverse behavior. In addition, the type of coal and the concentrations of TEs in feed coal were to some extent influenced by the emission of TEs in flue gas. The electrostatic precipitator (ESP) and seawater flue gas desulfurization (FGD) used in the studied coal-fired power plant were found effective in removing TEs in particulate and vapor form, respectively, as well as complying with the new specified emission limits. Implications: Coals used by power plants in Peninsular Malaysia come from the same supplier (Tenaga Nasional Berhad Fuel Services), which is a subsidiary of the Malaysia electricity provider (Tenaga Nasional Berhad). Therefore, this study on trace elements behavior in a coal-fired power plant in Malaysia could represent emission from other plants in Peninsular Malaysia. By adhering to the current coal specifications and installation of electrostatic precipitator (ESP) and flue gas desulfurization, the plants could comply with the limits specified in the Malaysian Department of Environment (DOE) Scheduled Waste Guideline for bottom ash and fly ash and the Proposed New Environmental Quality (Clean Air) Regulation 201X (Draft).

Computer aided design of occupationally healthier processes

Abstract Computer alded approaches for assessing inherent occupational health hazards and ranking process concepts based on their health properties were developed for the first stages of a process lifecycle; the process development, preliminary design, and basic engineering steps. The methods are tailored to the process design lifecycle steps in terms of their principle and information requirement. The methods can be integrated with existing computer aided design tools as described. A case study is given to illustrate the approach.

Technical Analysis of Accident in Chemical Process Industry and Lessons Learnt

A study of past accidents in the chemical process industry (CPI) has been carried out. It is found that the majority (73%) of the accidents were caused by technical and engineering failures. Based on the causes of accident and types of equipment failures, five common features of accident in the CPI were identified. The analysis reveals that the contribution of the design to accidents is significant and the advancement of knowledge/technology is not shared effectively by practitioners. Dependency on the add-on control strategy should be reduced and inherently safer or passive engineered must be considered as premier risk reduction strategy to lessen the safety load, for better design and to prevent accident effectively.

Prioritizing HAZOP analysis using analytic hierarchy process (AHP)

Hazard and operability (HAZOP) analysis is one of the most widely used methods for process hazard analysis. However, the outcome of HAZOP analysis could result in identifying large number of hazards, thus posing a challenge for assessors to take actions in dealing with all the hazards. The common practice in prioritizing the critical hazards is based on assessors’ experience through deductive judgment using rating scale, taking into consideration safety and the associated costs. Although being simple and straightforward, HAZOP has the disadvantage of lacking systematic approach to elucidate different conclusions into an integrated outcome, thus susceptible to inaccurate and unjustified decisions. In this paper, we present a structured methodology for incorporating prioritization in HAZOP analysis using analytic hierarchy process. Through this approach, the hazards of a process identified using HAZOP will be quantitatively weighted and ranked based on their priority along with the appropriate counter measures to be taken. The proposed methodology is a thorough decision-making tool as it does not only prioritize the hazards identified from the HAZOP assessment, but also provides medium for the assessors to quantitatively analyze the hazards. To show its efficacy, the approach will be applied to a simple reactor unit and a more complex system of dividing wall column pilot plant as case studies. The result shows that the proposed methodology is capable of identifying and ranking the most significant hazards in a process following HAZOP analysis. This is particularly useful, especially to process designers/engineers in prioritizing their efforts and resources on more significant hazards, hence aiding toward achieving an inherently safer chemical process.

P-graph methodology for Bi-objective optimisation of bioenergy supply chains: Economic and safety perspectives

Widespread adoption of bioenergy for electricity generation could lead to a globally greener environment, with significant climatic and waste management benefits. Numerous methodologies have been developed to optimize the performance of bioenergy supply chains with different objective functions (e.g., profitability, carbon footprint, etc.) usually based on conventional optimization techniques. Such techniques are usually based on single-objective formulations, and are able to determine unique optimal solutions. Process graph (P-graph) is a graph-theoretic methodology which has been applied towards various network optimization problems in different domains. It offers advantages of computational efficiency for large-scale combinatorial problems, as well as the capability to identify both optimal and near-optimal solutions; the latter feature is especially good for decision-makers in practical applications. This paper presents an approach to the planning of bioenergy supply chains, taking into account both total cost minimization and supply chain risk reduction. The supply chain risk is accounted for in terms of transportation fatalities computed in an actuarial manner. An illustrative example based on Malaysian palm-based bioenergy supply chain is solved to illustrate the proposed approach.

Multi-objective Design of Industrial Symbiosis in Palm Oil Industry

Abstract This paper presents a systematic approach for synthesising and designing multiple owners of bioenergy system in palm oil industry. The concept of industrial symbiosis (IS) is adapted to enhance the interaction of processing plants as well as to facilitate processing plants’ cooperation. The decision of processing plants’ participation in IS system can be affirmed via disjunctive fuzzy optimisation approach based on processing plants’ declared economic interests and inherent safety of entire IS system. In cases where the interest (either economic or safety aspects) of any processing plant is not satisfied, that party can elect to withdraw from the IS scheme. The optimum network configuration with the maximum individual economic interests and minimum individual inherent safety is determined prior to the proposed approach. An industrial case study based on palm oil industry is solved to illustrate the proposed approach.

Designing an inherently healthier process based on inherently safer design (ISD) concept: research and development stage

The rate of people dying due to occupational-related diseases is increasing each year. Although designing an inherently safer process can help in reducing the hazard level of a process by its nature without any additional protective, the aspects of health issues still remain unaddressed due to less research work carried out. Having said this, it is always a good and preferred practice to assess the health hazards as early as research and development (R&D) stage. At this stage, selection of the chemical synthesis routes is yet to be decided, and therefore, any modifications required can be done with minimal cost impact. Thus far, several works have been done in relation to occupational health especially by adapting the inherently safer design (ISD) principles (minimization, substitution, moderation, and simplification). However, most of them were only applicable for later stages of process design (preliminary design and basic engineering) and not in R&D stage. This paper proposes a systematic methodology for designing an inherently healthier process during the R&D stage using ISD principles. A flowchart that summarizes the proposed methodology is developed in guiding the user to reduce the hazard level of a process by analyzing the outcome of the prior health hazard assessment conducted to design a safer and healthier process. A case study on methyl methacrylate production is used to demonstrate the proposed methodology.Graphical Abstract

A Heuristic Framework for Inherent Occupational Health Assessment in Chemical Process Design

This paper presents a systematic heuristic framework to assist process designers and engineers in assessing inherent occupational health during process development and design. Different methods for inherent occupational health assessment are available and can be selected based on the availability of the most comprehensive data at the stage of the assessment. A more detailed and accurate assessment can be performed in the process and instrumentation diagrams (P&IDs) stage via the Occupational Health Index method (OHI) due to the availability of more precise data on the process (i.e., detailed piping, instruments and equipment). In the event of P&ID is not available, Health Quotient Index (HQI) method can be adopted to assess chronic inhalative health risk due to fugitive emission from process components (e.g., valve, flange, etc.) in the stage where process flow sheet diagrams (PFDs) are already generated. A qualitative health assessment can be conducted using the Inherent Occupational Health Index (IOHI) if the detailed information is still lacking because it only requires the data from process reaction chemistries and the properties of the chemical substances present. It is worth mentioning that the proposed framework acts as a guideline for design engineers in systematically selecting the appropriate index and methodology to assess inherent occupational health in process industry.

Review on sustainability assessment of integrated biorefineries based on environmental, health and safety perspectives

The depletion of fossil fuel reserves and increment of concern on environmental sustainability has motivated industries to search for alternatives for both energy generation and production of chemicals and materials. Among the alternative sources which are deemed to be viable, biomass has been identified as one of those with the highest potential sources to replace fossil fuel. In order to convert biomass into biofuels, bioenergy and biochemical, a sustainable integrated biorefinery is needed to integrate multiple biomass conversion processes with minimum impact to the environment, health and safety aspects. Currently, integrated biorefinery is designed primarily based on economic performance and environmental impact as these are the most important factors for decision makers especially for the development of new processes. However, the challenge is mounted up in a way that the design of an integrated biorefinery needs to also simultaneously consider other factors such as energy utilization, inherent occupational health and safety hazard. The increasing number of technologies available in the market will add to the complexities in the synthesis and design of an integrated biorefinery. Hence, the aim of the current paper is to conduct a review on the sustainability assessment methodologies which was used during the process synthesis of an integrated biorefinery system.