Water Network Synthesis Using Mutation-Enhanced Particle Swarm Optimization

Different techniques for the synthesis of industrial water reuse/recycle networks have been developed in recent process integration research. These tools range from graphical pinch analysis approaches to mathematical programming models. The latter have the advantage of being flexible enough to incorporate various water network constraints, but in many cases these are often non-linear, thus making the identification of global optima difficult. Recent work has demonstrated the effectiveness of metaheuristic algorithms such as particle swarm optimization (PSO), for finding good solutions these problems. This work describes the use of a modified PSO for solving mixed integer non-linear programming (MINLP) models for water network synthesis. By incorporating a mutation operator for the binary variables in the model, the algorithm is able to escape sub-optimal network topologies and proceed towards better solutions than can be found with ordinary PSO. Two case studies involving water recycle/reuse are used to demonstrate the new design methodology.     

Reduction of water usage in industry by using the MINLP coordinates technique

Natural resources are limited, so we need to handle them carefully. Wastewater also belongs as a significant natural resource. The re-usage of wastewater is to save fresh water and for the preparation of raw materials or/and utilities. The wastewater re-usage distribution can be optimised using mixed-integer nonlinear programming (MINLP), as a tool in combinations using the coordinates technique. The main goal of this MINLP coordinates technique was: i) wastewater and condensate, as produced during different industrial processes, could be collected for: utilities for steam-generation, and the preparations of raw materials; ii) wastewater and condensate could be collected within the main reservoir; iii) distributions from the main reservoir could be used with including different alternatives, which can reduce pollution, based on the re-usage of wastewater. Alternatives included in the optimization model represent potential solutions, which need to be evaluated on appropriate way.The MINLP coordinates technique for wastewater re-usage distribution was tested on existing formalin and methanol industrial processes, thus allowing the saving of water and generated by 280 kEUR/a profit.     

Targeting for optimal grid-wide deployment of carbon capture and storage (CCS) technology

Carbon capture and storage (CCS) techniques are considered as one of the promising approaches to reduce carbon dioxide (CO₂) emissions from fossil fuel based power generation, which still accounts for a significant portion of greenhouse gas emissions in the world. CCS technology can be used to mitigate greenhouse gas emissions, with the additional advantage that it allows continuing use reliable and inexpensive fossil fuels. However, CCS retrofit entails major capital costs as well as a reduction of overall thermal efficiency and power output. Thus, it is essential for planning purposes to implement the minimal extent of CCS retrofit while meeting the specified carbon emission limits for the power sector. At the same time, it is necessary to plan for compensatory power generation capacity to offset energy losses resulting from CCS retrofit. In this paper, an algebraic targeting technique is presented for planning of grid-wide CCS retrofits in the power generation sector with compensatory power. The targeting technique is developed based on pinch analysis. In addition, the proposed methodologies are illustrated through case studies based on grid data in India and the Philippines. Sensitivity analysis is carried out to determine the suitable CCS technology and compensatory power source which satisfy emission limits.     

Process analysis of an industrial waste-to-energy plant: Theory and experiments

Thermal conversion is fundamental in an integrated waste management system due to the capability of reducing mass and volume of waste and recovering energy content from unrecyclable materials. Indeed, power generation from industrial solid wastes (ISW) is a topic of great interest for its appeal in the field of renewable energy production as well as for an increasing public concern related to its emissions. This paper is based on the process engineering and optimization analysis, commissioned to the University Campus-Biomedico of Rome by the MIDA Tecnologie Ambientali S.r.l. enterprise, ended up in the construction of an ISW thermo-conversion plant in Crotone (Southern Italy), where it is nowadays operating. The scientific approach to the process analysis is founded on a novel cascade numerical simulation of each plant section and it has been used initially in the process design step and after to simulate the performances of the industrial plant. In this paper, the plant process scheme is described together with the values of main operating parameters monitored during the experimental test runs. The thermodynamic and kinetic basics of the mathematical model for the simulation of the energy recovery and flue gas treatment sections are presented. Moreover, the simulation results, together with the implemented parameters, are given and compared to the experimental data for 10 specific plant test runs. It was found that the model is capable to predict the process performances in the energy production as well as in the gas treatment sections with high accuracy by knowing a set of measurable input variables. In the paper fundamental plant variables have been considered such as steam temperature, steam flow rate, power generated as well as temperature, flow rate and composition of the resulting flue gas; therefore, the mathematical model can be simply implemented as a reliable and efficient tool for management optimization of this kind of plants.     

New methodologies for security risk assessment of oil and gas industry

The oil and gas industry forms a vital and large part of the economy of any country. It provides crucial support to transport, manufacturing and energy sectors, produces valuable exports and provides huge employment. This industry along with fertilizer plants, petrochemical plants, etc., which handle hazardous chemicals, are potential targets for deliberate actions by terrorists, criminals and disgruntled employees. The process industries face different levels of threats. It is imperative to analyze the entire threat scenario before taking steps to counter it, otherwise each and every threat will have to be treated as most severe, thus resulting in a huge and wasteful expenditure.The Security Risk Factor Table (SRFT) and a Stepped Matrix Procedure (SMP) have been developed to assess the security risk of oil and gas industry as well as the other chemical process industries. While the SRFT deals with the effects of individual threats, the SMP deals with the cascading/domino effects which a lone, low probability event can cause. A case study of a refinery has been performed to show the application of the ideas presented.     

Power system planning with emission constraints: Effects of CCS retrofitting

Today, the world's energy needs are still supplied mainly from fossil fuel based resources. This is true for electricity generation as well, thus making the power sector responsible for 45% of greenhouse gas emissions. The present climate crisis has made it necessary to minimise emissions in power generation, with low-carbon energy sources taking on greater significance in recent years. However, most low-carbon sources have inherent problems, like intermittency and high capital expenditure. A suitable alternative is carbon capture and storage (CCS) technology which allows continued fossil fuel-based electricity generation at much lower rates of emission. Two approaches are possible in the deployment of CCS technology. The first is to introduce new power plants equipped for carbon dioxide (CO₂) capture, while systematically shutting down existing coal power plants. Another is to retrofit existing power plants for CO₂ capture. These approaches are compared in this work. The study shows that allowing CCS retrofitting of existing power plants can reduce the overall cost requirement significantly. In addition, a sensitivity analysis is also done to study the effect of nuclear energy on the overall energy mix.     

Thermodynamics,economics and systems thinking: What role for air capture of CO2?

Air capture has recently been advanced by several parties as a solution to the problem of constraining – and ultimately reducing – atmospheric CO₂ in response to climate change. However, there are significant barriers pertaining to scale, energy needs and cost, which will hugely challenge the effectiveness and practicality of air capture. This paper examines the thermodynamics, energetics and economics and politics of air capture. These compare unfavourably with alternative approaches to atmospheric greenhouse gas reduction. An analysis is made of the energy cost of the one favoured DAC technology for which experimental results are available in the open literature – temperature/vacuum swing adsorption, and of one point source capture technology – oxyfiring of refinery FCCUs. We also examine the engineering effort required to implement atmospheric capture on a scale at which it could significantly reduce atmospheric levels of CO₂; and questions are addressed regarding its practicability and appropriateness. The analysis demonstrates that air capture remains at best a peripheral activity, at worst a distraction, until point sources of greenhouse gas emissions such as power stations, industrial flue gases, shale gas wellheads, anaerobic digestion plants and landfill sites have been completely decarbonised. When these and so many other unaddressed factors are affecting our global climate, the pursuit air capture, the ultimate “end-of-pipe” solution, is inappropriate.     

高硫炼油装置硫化氢泄漏场景集定量分析

随机规划方法已成为解决不确定条件下高硫炼油装置气体检测报警仪布置优化问题的重要途径,而构建接近真实情况的泄漏场景集则是实现随机规划的基础。目前,有毒气体泄漏场景集构建方面的研究鲜有报道,且传统以典型泄漏场景为代表的做法未能体现真实风险。为此给出一种融合泄漏概率和风场联合分布概率的定量构建硫化氢泄漏场景集的方法,使场景集包括重要泄漏场景并运用DNV的LEAK软件和历史气象数据定量预测场景的实现概率,为实现后续的气体泄漏检测报警仪布置随机规划提供技术支持。并以某柴油加氢装置为例,定量构建其硫化氢泄漏场景集,为后续的气体检测报警仪布置优化及其它基于定量风险分析的控制决策提供支持。     

Analysis of injury events with fuzzy cognitive maps

Issues related to health and safety at work, such as accidents at work, are one of the most important areas of action for global social policy. This paper presents a fuzzy cognitive map (FCM) approach to explore the importance of the relevant factors in industrial plants. For this purpose, industrial plants are described in terms of factors that affect injury risk and the causal relationships involved.In this work, the injuries in an Italian refinery have been studied. The company in this account has a system for monitoring and controlling the machinery but has a large number of minor injuries at work. The causes of these injuries have been found in human behaviours. To analyse the injuries, it is necessary to investigate what individual-level concerns are involved in the perception of risk. For this investigation, an FCM permits us to build a schema of the perception of risk. The resulting analysis of all of these schemas has allowed us to define a method that generically permits a determination of the causes for each type of injury. In fact, it has been possible to determine that factors such as poor attention and concentration or fatigue are the main causes of injuries at work.In light of the results obtained, managers can define appropriate control procedures to diminish the occurrences of the injuries.     

采用高压水射流技术清洗炼油催化装置油汽管线

炼油厂催化裂化装置沉降器至分馏塔之间的油气管线,在生产过程中容易结焦而影响装置的正常运转。通过几种方案的分析对比,选择并采用高压水射流技术进行清洗。结合多年的清洗实践,提出了该工况条件下,高压水射流清洗工装的设计设置、清洗装备器材的选配、清洗工艺参数的确定、清洗方案实施的业绩以及清洗作业的安全措施要点。指出了采用高压水射流技术清洗油气管线结焦是行之有效的方法。     

RCNet: An optimisation software for the synthesis of resource conservation networks

RCNet is a spreadsheet-based software for the synthesis of resource conversation networks (RCNs) for planning the efficient use of material resources (e.g., water, utility gases, solvents) in industrial plants. The software is developed based on the well-established process integration tools, namely pinch analysis and mathematical programming techniques. In the first stage, pinch analysis is used to determine maximum resource conservation targets prior to detailed RCN design. In the second stage, mathematical optimisation is then used to determine the optimal flowrate allocation between process sources and sinks of the RCN, to achieve the performance targets. RCNet is applicable for various industrial applications. To date, no generic software has been developed to handle water minimisation, hydrogen recovery and property integration, which is the main subject of this work. In the developed software, same interface and platform can be used to solve abovementioned problems independently. For illustration, three literature examples on water minimisation, hydrogen recovery and property integration, as well as an industrial case study are solved using RCNet.     

A new multiple-risk map approach to solve process plant layout considering safety and economic aspects

Mathematical models used to optimize the process plant layout (PPL) with risk reduction have four primary objectives, which are related to the minimization of land, pumping (pipe system), protection system devices, and risk costs. Moreover, these models are of two types: continuous plane models (CPM) and grid-based models (GBM); however, the nonconvexity of the CPM models makes difficult to achieve the global optimum, because it is formulated as Mixed-Integer Nonlinear Programming (MINLP). Thus, the risk map approach has been implemented with the grid-based models to solve problems of process plant layout focused on finding the best possible solution. However, these risk map formulations present important limitations, mainly related with the use of protection devices and the occupied area. Therefore, a new GBM-MILP formulation is proposed to optimize the selection of protection devices and minimize the occupied area. The risk is reduced through the investment on safety devices instead of considering the increase of separation distances. The proposed model was used to solve the layout problem of an ethylene oxide process, and the results was compared with a process layout reported in the literature. The results show that the model can provide the best possible solution; however, the time spent in the calculation is considerably greater than that reported for continuous plane models. Finally, the model can be used by decision-makers to evaluate different layout options for several explosion scenarios, during the early stages of the plant design.     

炼油厂环境风险评价的实践和思考

按照《建设项目环境风险评价导则》要求,对某炼油厂环境风险评价的部分内容进行了介绍,指出了炼油厂环境风险评价重大危险源、最大可信事故源等评价结果.同时就工作中存在的问题,从环境的观点出发,就石油炼制行业的环境风险评价分级,事故概率的确定,事故状态下采取水体风险防范措施后源强的确定,事故危害后果定量分析,预测模式的研究方向等方面提出了相应意见.     

Influence of wind speed profile and roughness parameters on the downwind extension of vulnerable zones during dispersion of toxic dense gases

The accidental release of toxic chemicals, which are heavier than air and stored under pressure, may create an emergency scenario in an industrial plant. The extension of vulnerable distance in the downwind direction is an important criterion in framing an emergency management plan of that industrial area. There are several studies showing the role of surface level meteorological and topographical features on its propagation and dispersion just after its release from a container. In the present study, vertical variation of wind speed in the atmospheric boundary layer and surface roughness parameter have been considered to study their roles on the impact of downwind extension of vulnerable distances. A catastrophic release from a tonner having 900 kg of liquid chlorine has been considered, and SAFETI Micro developed by DNV Technica, UK has been utilized in the consequence analysis of this release. The analysis results have been explained for various atmospheric stability classes and surface wind speeds.     

On the failure of steam-side oxide scales in high temperature components of boilers during unsteady thermal processes

Failure of steam-side oxide scales in high temperature components of boilers such as superheater and reheater tubes has significant effect on the safety of thermal power plants. Taking into account the influence that temperature has on physical properties of metal substrate and oxide scale, transient heat transfer model as well as multi-layered hollow cylinder stress model is successively developed in this work. Employing the Advanced Oxide Scale Failure Diagram (AOSFD) as failure criterion, a systematic analysis model for the failure behavior of steam-side oxide scales in T92 superheater tubes during unsteady thermal processes is established. Focusing on different steam temperature variation processes, the effects of steam-side oxide scale thickness as well as different steam temperature variation modes and variation durations on oxide scale failure issues have been analyzed. Besides, critical steam temperature drops leading to failure of oxide scales when steam temperature decreases linearly have also been investigated. Based on the analysis results, feasible measures such as selecting reasonable steam temperature variation mode and appropriately lengthening variation duration are subsequently proposed. The analysis results as well as the suggested measures in this work can provide valuable guidance for the solution of steam-side oxide scale failure issues in thermal power plants.     

炼油污水的深度处理

对炼油污水深度处理常用技术——过滤、膜分离、化学氧化技术进行了详细的论述，并结合中试试验，对动态砂滤系统、PAN膜处理系统和高级氧化系统处理炼油厂二级排放水的适用性进行了论证。     

Integration of techniques for early fault detection and diagnosis for improving process safety: Application to a Fluid Catalytic Cracking refinery process

In this paper we show the integration of techniques for early fault detection and diagnosis of operational faults in industrial processes, and we show an application example in a Fluid Catalytic Cracking refinery process. The early fault detection and diagnosis allow the operators in an industrial process to take the best actions during the real state of the process, avoiding incipient faults to scale to critical situations where there is risk of human lives and economical lost.     

Systematic incorporation of inherent safety in hazardous chemicals supply chain optimization

Increasing globalization has made many chemical supply chains large, interdependent and complex. Process incidents often affect the reliability of a supply chain and can cause large disruptions at different segments of the industry. We propose an optimization-based framework that systematically takes into account the trade-offs between process safety and supply chain economics for decision-making. We quantify the hazard at various supply chain echelons in the form of a safety index that takes both fire and toxic hazards into account. A mixed-integer nonlinear programming (MINLP)-based model is developed to either maximize profit for specified hazard limits, or to minimize hazard in a supply chain with multiple production plants, technological options, warehouses and distribution nodes. The MINLP model is used to generate trade-off optimal solutions for various toxic and fire hazard limits. The framework is demonstrated by applying it to an end-to-end ammonia supply chain case study which resulted in several non-intuitive observations regarding hazardous supply chain design and optimization.     

Challenges in risk management in multi-company industrial parks

The trend of companies focusing ever stronger on their core businesses has led to outsourcing of certain activities, e.g. maintenance, and even to selling out parts of industrial plants. This is the case also in Finland. Clusters of neighbouring companies, commonly called industrial parks, have been formed. In these multi-company parks safety and environmental responsibilities are not always clear and the risk map has changed. It has become evident that Finnish legislation has not followed this development of the industrial sector and the formation of industrial and technology parks.A Finnish project on the safety in chemical industrial parks has studied how safety and environmental issues can be best managed in multi-company chemical parks, and how the current legislation in Finland supports companies facing problems accentuated in or specific to industrial parks. The outcome outlines the identified challenges as well as the benefits of cooperation between the independent companies in industrial parks.     

Fuzzy risk modeling of process operations in the oil and gas refineries

Operating several assets has resulted in more complexity and so occurrence of some major accidents in the refining industries. The process operations risk factors including failure frequency and the consequence components like employees' safety and environment impacts, operation downtime, direct and indirect cost of operations and maintenance, and mean time to repair should be considered in the analysis of these major accidents in any refinery. Considering all of these factors, the risk based maintenance (RBM) as a proper risk assessment methodology minimizes the risk resulting from asset failures. But, one of the main engineering problems in risk modeling of the complex industries like refineries is uncertainty due to the lack of information. This paper proposes a model for the risk of the process operations in the oil and gas refineries. The fuzzy logic system (FLS) was proposed for risk modeling. The merit of using fuzzy model is to overcome the uncertainty of the RBM components. This approach also can be accounted as a benchmark for future failures. A unified risk number would be obtained to show how the criticality of units is. The case study of a gas plant in an oil refinery is performed to illustrate the application of the proposed model and a comparison between the results of both traditional RBM and fuzzy method is made.For the case study, 26 asset failures were identified. The fuzzy risk results show that 3 failures have semi-critical level and other 23 failures are non-critical. In both traditional and fuzzy RBM methods, some condenser failures had the highest risk number and some pumps were prioritized to have the lowest risk level. The unit with unified risk number less than 40 is in the non-critical conditions. Proposed methodology is also applicable to other industries dealing with process operations risks.