Zainuddin Abdul Manan

Optimization of thermo-alkaline disintegration of sewage sludge for enhanced biogas yield

Optimization of thermo-alkaline disintegration of sewage sludge for enhanced biogas yield was carried out using response surface methodology (RSM) and Box-Behnken design of experiment. The individual linear and quadratic effects as well as the interactive effects of temperature, NaOH concentration and time on the degree of disintegration were investigated. The optimum degree of disintegration achieved was 61.45% at 88.50 °C, 2.29 M NaOH (24.23%w/w total solids) and 21 min retention time. Linear and quadratic effects of temperature are most significant in affecting the degree of disintegration. The coefficient of determination (R(2)) of 99.5% confirms that the model used in predicting the degree of disintegration process has a very good fitness with the experimental variables. The disintegrated sludge increased the biogas yield by 36%v/v compared to non-disintegrated sludge. The RSM with Box-Behnken design is an effective tool in predicting the optimum degree of disintegration of sewage sludge for increased biogas yield.

Centralised utility system planning for a Total Site Heat Integration network

Total Site Heat Integration (TSHI) is a technique of exchanging heat among multiple processes via a centralised utility system. An analysis of the integrated multiple processes, also known as the Total Site (TS) system sensitivity, is needed to characterise the effects of a plant maintenance shutdown, to determine the operational changes needed for the utility production and to plan mitigation actions. This paper presents an improved Total Site Sensitivity Table (TSST) to be used as a systematic tool for this purpose. The TSST can be used to consider various ‘what if’ scenarios. This tool can be used to determine the optimum size of a utility generation system, to design the backup generators and piping needed in the system and to assess the external utilities that might need to be bought and stored. The methodology is demonstrated by using an Illustrated Case Study consisting of three processes. During the TS normal operation, the Total Site Problem Table Algorithm (TS-PTA) shows that the system requires 1065 kW of High Pressure Steam and 645.5 kW of Medium Pressure Steam as the heating utility, while for the cooling utility, 553.5 kW of Low Pressure Steam and 3085 kW of cooling water are required. The results of the modified TSST proposed that a boiler and a cooling tower with the system design requiring a maximum capacity of 2.172 MW of steam and 4.1865 MW of cooling water are needed to ensure an operational flexibility between the three integrated processes.

Assessing the sensitivity of water networks to noisy mass loads using Monte Carlo simulation

For many water-intensive processes, water reuse can reduce water consumption as well as effluent generation. Process integration approach based on graphical pinch methodology for targeting and water network synthesis is often employed. The integrity of water network design to achieve the minimum water targets is highly sensitive to the availability of reliable process data. Existing network design process, however, assume that process data are fixed and well-defined, whereas the actual operating conditions such as water flowrate and the corresponding mass loads may fluctuate over time. These fluctuations in processing conditions can lead to process disruptions and product quality problems. This work demonstrates the use of Monte Carlo simulation in assessing the vulnerability of water networks to noisy mass loads. A case study illustrates the procedure of selecting the most robust network configuration from three alternative designs that achieve comparable water savings.

Process Integration and Intensification: Saving Energy, Water and Resources

Process Integration and Intensification (PII) is one of the most timely topics in chemical and process engineering leading to energy efficient, substantially smaller, cleaner, safer and optimized processes. The book covers optimization fundamentals and industrial applications. It is an authoritative overview meant to help graduate students as well as professionals to effectively apply PII in plant design and operation.

Heat exchanger network cost optimization considering multiple utilities and different types of heat exchangers

Abstract Supertargeting based on composite curves (CC) is widely used to determine the optimum approach temperature (Δ T min ) that yields the minimum total cost for heat exchange networks (HEN). Supertargeting using CC has two key limitations. Firstly, the HEN area calculations are drastically simplified through the assumption that CC segments may be considered as pseudo-single hot and cold streams exchanging heat via only one exchanger that is governed by a single cost correlation. Secondly, the current Supertargeting approach of considering only one hot and one cold utility level may lead to a crude estimation of the total HEN cost and the optimum Δ T min . This work presents the stream temperature vs. enthalpy plot supertargeting (STEPS) method that overcomes these limitations. This paper proves that supertargeting based on CC can lead to up to 50% error in the total cost target and poor Δ T min estimations.

A multi-period model for optimal planning of an integrated, resource-efficient rice mill

Abstract Rice is one of the worlds most important staple foods. Previous studies have focused on the yield improvement for an individual rice mill. There is a need to develop a framework to address the multitude of variables influencing the design of a rice mill complex, which include fluctuating thermal and electrical energy demands, diverse energy supply options, fluctuating product demands, resource availability and product degradation. The objective of this study is to develop a framework for the optimal design and planning of the product portfolio and processing route of an integrated, resource-efficient (IRE) rice mill complex. The objective function is to maximise the profitability of the rice mill by using the developed multi-period mathematical model. Sensitivity analysis was performed on the case study to evaluate the impact of fluctuating product demands, product prices and electricity cost on the production throughput, process configuration and profitability of the IRE rice mill complex.

Design of green diesel from biofuels using computer aided technique

This paper presents a systematic computer aided technique to design a sustainable (safe, environmentally friendly and economical) tailor-made “green diesel” blend that satisfies a set of desirable target properties. In this work, the software, Integrated Computer Aided System (ICAS) was used to predict the green diesel properties. The blending model is formulated to identify a set of feasible mixture blends that satisfy the desirable target properties such as density and viscosity. The blend design problem is formulated as an NLP problem and solved through GAMS. Application of the systematic technique yields several promising green diesel blends. Four final candidate blends were selected based on three key criterion, i.e. cost, sulfur content and carbon dioxide emissions. The results show that the best diesel contains 82.4% diesel, 16.6% butanol and 1% butyl levulinate. This diesel blend contributes to the reduction of CO2 emission and sulfur content by up to 15% and 17%, respectively.

Pinch Analysis targeting for CO2 Total Site planning

Rising CO2 emissions that have been primarily attributed to fossil fuel utilisation have motivated extensive research on optimal CO2 reduction planning and management. Carbon (more precisely CO2) capture and storage (CCS) and carbon capture and utilisation (CCU) have been the potential solutions to control CO2 emissions. However, mitigating CO2 emissions via CO2 storage in geological reservoirs without utilisation is merely a technology transition, and CO2 utilisation is limited due to the short lifespan of products. The integration of CCS and CCU, described as carbon capture, utilisation and storage (CCUS), has recently been introduced as a better option to mitigate CO2 emission. This study introduces a new algebraic targeting method for optimal CCUS network based on a Pinch Analysis–Total Site CO2 integration approach. A new concept of Total Site CO2 Integration is introduced within the CCS development. The CO2 captured with a certain quality from the largest CO2 emissions sources or plants is injected into a CO2 pipeline header to match the CO2 demands for utilising by various industries. The CO2 sources and demands are matched, and the maximum CCU potential is targeted before the remaining captured CO2 is injected into a dedicated geological storage. One or more headers are divided into certain composition ranges based on the purity level of the CO2 sources and demands. The CO2 header can satisfy the CO2 demands for various industries located along the headers, which require CO2 as their raw material. The CO2 can be further regenerated, and mixed as needed with pure CO2 generated from one or multiple centralised CO2 plants if required. The main consideration for the problem is the CO2 purity composition of targeted sources and demands. The proper estimation of CO2 integration will reduce the amount of CO2 emission needed to be stored and introduced to systematic CO2 planning and management network.Graphical Abstract

Water Pinch Analysis for Water Management and Minimisation: An Introduction

This chapter describes approaches for water management and minimisation based on the Water Pinch Analysis (WPA) concept. The chapter presents the step-wise procedure for implementing WPA. The significance of WPA and its applications in the industrial sector are also discussed.

SePTA—A new numerical tool for simultaneous targeting and design of heat exchanger networks

Pinch Analysis is an established insight-based methodology for design of energy-efficient processes. The Composite Curves (CCs) is a popular Pinch Analysis tool to target the minimum energy requirements. An alternative to the CCs is a numerical technique known as the Problem Table Algorithm (PTA). The PTA however, does not show individual hot and cold streams heat cascades and cannot be used for design of heat exchanger networks (HEN). This paper introduces the Segregated Problem Table Algorithm (SePTA) as a new numerical tool for simultaneous targeting and design of a HEN. SePTA shows profiles of heat cascade across temperature intervals for individual hot and cold streams, and can be used to simultaneously locate pinch points, calculate utility targets and perform SePTA Heat Allocation (SHA). The SHA can be represented on a new SePTA Network Diagram (SND) that graphically shows a heat exchanger network together with the amount of heat exchange on a temperature interval scale. This paper also shows that SePTA and SND can be a vital combination of numerical and graphical visualisation tools for targeting and design of complex HENs involving stream splitting, threshold problems and multiple pinches.