Scott Bury | The Dow Chemical Company (original) (raw)
Papers by Scott Bury
Marine terminal operations are complex, and evaluating changes is best done using a simulation to... more Marine terminal operations are complex, and evaluating changes is best done using a simulation tool that captures the dynamics and interactions of the system. We have developed a flexible and robust discrete-event simulation of a marine terminal that handles liquid cargo. We used this simulation to investigate proposed changes generated by a Six Sigma project to reduce congestion at the terminal. Our study provided quantitative data to base decisions on the expected operational and financial impact of the proposed changes. The simulation captured the important details of the system and increased the Six Sigma team's confidence in their recommendations. The modular architecture of the simulation allows for easy application of the simulation to different terminal simply by changing a few data tables. The structure of the simulation makes it easy for non-modelers to use the tool to perform continuing studies.
This paper discusses a discrete event simulation model developed to identify and understand the i... more This paper discusses a discrete event simulation model developed to identify and understand the impact of different failures on the overall production capabilities in a chemical plant. The model will be used to understand key equipment components that contribute towards maximum production loss and to analyze the impact of a change policy on production losses. A change policy can be classified in terms of new equipment installation or increasing the stock level for the failure prone components. In this paper, we present the approach used and some preliminary results obtained from available data.
The field of simulation optimization (SO), which deals with optimizing over simulations or experi... more The field of simulation optimization (SO), which deals with optimizing over simulations or experiments, is faced with challenges at every turn. Its use is of import in several engineering and business applications, including inventory management, urban traffic control, manufacturing plant design, and call center operations. Apart from the lack of an explicit functional form for the objective function, and the steep cost of evaluating the objective at a point--the stumbling blocks in derivative-free optimization--SO also involves underlying simulations that are inherently stochastic in nature. Furthermore, the fundamental questions regarding the choice of an appropriate objective to include variability in function value and the characterization of optimal points add to its complexity. We pose the problem as the local minimization of a statistic of a continuous black-box function, assuming that bounds are available on the control variables. Though the setup of the problem prohibits th...
Planners of batch chemical processes face a wide range of challenges when scheduling production t... more Planners of batch chemical processes face a wide range of challenges when scheduling production to ensure adequate product to fill promised orders. Today, solving these scheduling problems using rigorous optimization methods is feasible in the standard business time frame, ie, fast enough that the user perceives that it makes their job easier. This case-study will present multi-product batch optimal scheduling using Resource-Task Networks (RTN). Although this deterministic approach is successful, the stochastic nature of the process inevitably leads to rescheduling. The structure of the RTN allows for nearly one-to-one mapping into a discrete-event simulation (DES). The DES allows us to refine the grid size and input parameters for the optimization. The DES also allows for quantitative comparisons between "by-hand" schedules and the proposed optimal schedules from the RTN. This combined approach of discrete-event simulation and deterministic optimization has provided rapid...
All chemical plants require periodic turnarounds, or planned shutdowns, for maintenance purposes.... more All chemical plants require periodic turnarounds, or planned shutdowns, for maintenance purposes. When dealing with large industrial complexes and integrated sites, the scheduling of such turnarounds becomes important, as each plant may need raw materials in specific ratios that can be sourced from one or more plants in the site, and products from the plant may be required downstream as raw materials to other plants as well. The turnaround time-scale of each turnaround task is on the order of weeks, and intervals between turnarounds are on the order of years. Each specific turnaround can cost millions of dollars to perform, and in addition, incurs lost sales. This makes turnaround scheduling decisions crucial from an economic viewpoint. Thus, the turnaround scheduling task is a long-term plan for managing the operation and preventive maintenance tasks on entire plants that are part of an enterprise-wide or site-wide network. The integrated site can be represented as a network with m...
Integrated sites involve material flow in process networks. The disruption of flow due to planned... more Integrated sites involve material flow in process networks. The disruption of flow due to planned maintenance turnarounds on some process units affects production rates in both upstream as well as downstream units. Due to this, long-term maintenance planning often recommends the alignment of a subset of the turnarounds around the same time in order to make use of synergistic effects. In this paper, we consider a short-term maintenance scheduling setting, where we focus on a time scale of a few months within which a number of turnarounds are scheduled to take place. A major concern during the time leading up to a set of turnarounds is the planning for inventory build-up in anticipation of a turnaround, so as to try and maintain normal operation and satisfy demands during these long outages. Another issue is the allocation of maintenance manpower among various subtasks, which is a scarce resource that has been negotiated for months in advance. The goal of this work is to provide an op...
Proceedings of the 2011 Winter Simulation Conference (WSC), 2011
A generic model is a model that is built for a class of system and can be implemented for a speci... more A generic model is a model that is built for a class of system and can be implemented for a specific system through changes in input data alone, without any structural changes to the model. In this paper, we propose a framework for building such generic model for non-steady state process networks, which are characterized by flow of materials between
Computers & Chemical Engineering, 2015
We propose a data-driven, nonparametric approach to reformulate (conditional) individual and join... more We propose a data-driven, nonparametric approach to reformulate (conditional) individual and joint chance constraints with right-hand side uncertainty into algebraic constraints. The approach consists of using kernel smoothing to approximate unknown true continuous probability density/distribution functions. Given historical data for continuous univariate or multivariate random variables (uncertain parameters in an optimization model), the inverse cumulative distribution function (quantile function) and the joint cumulative distribution function are estimated for the univariate and multivariate cases, respectively. The approach relies on the construction of a confidence set that contains the unknown true distribution. The distance between the true distribution and its estimate is modeled via φ-divergences. We propose a new way of specifying the size of the confidence set (i.e., the φ-divergence tolerance) based on point-wise standard errors of the smoothing estimates. The approach is illustrated with a motivating and an industrial production planning problem with uncertain plant production rates.
Proceedings of the 2011 Winter Simulation Conference (WSC), 2011
The application of discrete event simulation in the process industries is commonly used for the a... more The application of discrete event simulation in the process industries is commonly used for the analysis of reliability and maintenance improvements. However there have been increasing applications that go beyond this traditional area of application to include evaluations for chemical plant expansions, capital investment options, cycle time reduction and safety, in presence of failure prone components. This paper will present
Proceedings of the 2010 Winter Simulation Conference, 2010
... ANALYSIS OF A CHEMICAL PLANT USING DISCRETE EVENT SIMULATION Bikram Sharda and Scott J. Bury ... more ... ANALYSIS OF A CHEMICAL PLANT USING DISCRETE EVENT SIMULATION Bikram Sharda and Scott J. Bury Process Optimization-Engineering Sciences, Core R&D The Dow Chemical Company Freeport, TX, USA 77541 ABSTRACT This paper describes a debottlenecking ...
Computers & Chemical Engineering, 2015
ABSTRACT An integrated chemical site involves a complex network of chemical plants. Typically, th... more ABSTRACT An integrated chemical site involves a complex network of chemical plants. Typically, these plants interact closely, are dependent on each other for raw materials and demand for their products, and have the provision of intermediate storage tanks to help manage inventory at strategic points in the network. Disruptions in the operation of these plants can drastically affect flow of material in the site network. As a result, the choice of sequence and timing of planned periodic turnarounds, which are major disruptions, is important in order to minimize effects on profits and production. We investigate a discrete-time mixed-integer linear programming (MILP) model to perform turnaround optimization. The objective is to recommend potential schedules in order to minimize losses while satisfying network, resource, turnaround, demand, financial and other practical constraints. We propose general formulations to tackle this problem and study an industrial-size site network under various scenarios over a long-term horizon.
2014 Reliability and Maintainability Symposium, 2014
ABSTRACT The Dow Chemical Company is a reliable corporation and sets and performs against very hi... more ABSTRACT The Dow Chemical Company is a reliable corporation and sets and performs against very high standards in the industry. However to meet the challenges of increasing global competition, dynamic markets for products and feedstocks and rising customer expectations, Dow has been on a multi-year journey to achieving the higher levels of enterprise-wide reliability. This is a critical component to Dow's growth strategy. Enterprise Reliability is the activity of designing and achieving reliability in all activities across the entire corporation, regardless of location, function, or business, toward the aspiration of flawlessly meeting all stakeholder commitments each and every time. Decision support tools are an important technology for Enterprise Reliability and we have adapted three traditional reliability modeling and analysis tools to meet this need. This paper presents three aspects this technology: 1) Value Stream Simulation, 2) Value Stream Optimization and 3) Data Analytics in the context of the Dow's Enterprise Reliability. These technologies were discussed in terms of the issues associated with the development, validation and deployment of the technologies to be actively used to make operating and investment decisions. Our conclusion after two years of implementation is that clarity on the data required from the models for decision making, clarity of the owner of decisions, and clarity of the structure and assumption of the models and methodologies are the keys to integrating efforts across divisions and lead to improved decision making across the envelop and lead to opportunities with a significant ROI.
High variability, stringent effluent permits, and often extreme operating conditions define the p... more High variability, stringent effluent permits, and often extreme operating conditions define the practice of wastewater treatment in the chemical industry. This paper reviews the benefits and challenges of applying dynamic simulation to chemical-industry wastewater treatment plants by describing case studies at full-scale wastewater treatment plants (WWTP). The applications range from process troubleshooting to optimization and control. The applications have been valuable and useful in developing a deeper understanding of the plants as integrated systems. However there still remains substantial work to implement the dynamic simulations for daily real-time use by plant engineers and operators. This opportunity to improve plant operations is still largely untapped and will remain so until dynamic state estimation and data reconciliation are incorporated into simulation packages for use in developing the on-line simulations. Keywords Dynamic simulation; industrial activated sludge; mode...
Journal of Industrial Microbiology, 1989
Summary Some metabolic properties of both suspended and immobilized aerobically and anaerobically... more Summary Some metabolic properties of both suspended and immobilized aerobically and anaerobically growingEscherichia coli cells were investigated. Metabolic activity was found to be substantially different whenE. coli cells were immobilized in alginate. Cells grown ...
Computers & Chemical Engineering, 2012
The challenges of supplying advanced materials and performance products are very different from t... more The challenges of supplying advanced materials and performance products are very different from those associated with commodity chemicals. Yet these challenges are well addressed by enterprisewide optimization techniques. This paper discusses the nature of advanced materials and some challenges and solutions related to product design, production scheduling, process reliability, and logistics. Ongoing research in the use of multi-agent systems for batch process management is also reviewed.
Computers & Chemical Engineering, 2012
Integrated sites are tightly interconnected networks of large-scale chemical processes. Given the... more Integrated sites are tightly interconnected networks of large-scale chemical processes. Given the largescale network structure of these sites, disruptions in any of its nodes, or individual chemical processes, can propagate and disrupt the operation of the whole network. Random process failures that reduce or shut down production capacity are among the most common disruptions. The impact of such disruptive events can be mitigated by adding parallel units and/or intermediate storage. In this paper, we address the design of large-scale, integrated sites considering random process failures. In a previous work (Terrazas-Moreno et al., 2010), we proposed a novel mixed-integer linear programming (MILP) model to maximize the average production capacity of an integrated site while minimizing the required capital investment. The present work deals with the solution of large-scale problem instances for which a strategy is proposed that consists of two elements. On one hand, we use Benders decomposition to overcome the combinatorial complexity of the MILP model. On the other hand, we exploit discrete-rate simulation tools to obtain a relevant reduced sample of failure scenarios or states. We first illustrate this strategy in a small example. Next, we address an industrial case study where we use a detailed simulation model to assess the quality of the design obtained from the MILP model.
Proceedings of the 2010 Winter Simulation Conference, 2010
A panel of simulation managers from manufacturing companies discuss the following six topics: (1)... more A panel of simulation managers from manufacturing companies discuss the following six topics: (1) How are managers responsible for manufacturing best persuaded to try simulation? (2) How can capturing the benefits of simulation best be made a regular process? What are the roles of model databases and reuse, input databases, standardization, change management, simulation project management, and training in such a process? (3) What other areas should one consider in addition to the ones listed in item 2 above in such a process? (4) Where should the Simulation Services Department reside in the organizational structure of a manufacturing company? Should it be centralized or decentralized? (5) How can simulation XVDJH ³WKH ILUVW SURMHFW´ EHVW EH XQGHUWDNHQ WR EH D VXFFHVV" +RZ FDQ PRPHQWXP EHVW EH PDLntained after simulation usage is accepted?
Marine terminal operations are complex, and evaluating changes is best done using a simulation to... more Marine terminal operations are complex, and evaluating changes is best done using a simulation tool that captures the dynamics and interactions of the system. We have developed a flexible and robust discrete-event simulation of a marine terminal that handles liquid cargo. We used this simulation to investigate proposed changes generated by a Six Sigma project to reduce congestion at the terminal. Our study provided quantitative data to base decisions on the expected operational and financial impact of the proposed changes. The simulation captured the important details of the system and increased the Six Sigma team's confidence in their recommendations. The modular architecture of the simulation allows for easy application of the simulation to different terminal simply by changing a few data tables. The structure of the simulation makes it easy for non-modelers to use the tool to perform continuing studies.
This paper discusses a discrete event simulation model developed to identify and understand the i... more This paper discusses a discrete event simulation model developed to identify and understand the impact of different failures on the overall production capabilities in a chemical plant. The model will be used to understand key equipment components that contribute towards maximum production loss and to analyze the impact of a change policy on production losses. A change policy can be classified in terms of new equipment installation or increasing the stock level for the failure prone components. In this paper, we present the approach used and some preliminary results obtained from available data.
The field of simulation optimization (SO), which deals with optimizing over simulations or experi... more The field of simulation optimization (SO), which deals with optimizing over simulations or experiments, is faced with challenges at every turn. Its use is of import in several engineering and business applications, including inventory management, urban traffic control, manufacturing plant design, and call center operations. Apart from the lack of an explicit functional form for the objective function, and the steep cost of evaluating the objective at a point--the stumbling blocks in derivative-free optimization--SO also involves underlying simulations that are inherently stochastic in nature. Furthermore, the fundamental questions regarding the choice of an appropriate objective to include variability in function value and the characterization of optimal points add to its complexity. We pose the problem as the local minimization of a statistic of a continuous black-box function, assuming that bounds are available on the control variables. Though the setup of the problem prohibits th...
Planners of batch chemical processes face a wide range of challenges when scheduling production t... more Planners of batch chemical processes face a wide range of challenges when scheduling production to ensure adequate product to fill promised orders. Today, solving these scheduling problems using rigorous optimization methods is feasible in the standard business time frame, ie, fast enough that the user perceives that it makes their job easier. This case-study will present multi-product batch optimal scheduling using Resource-Task Networks (RTN). Although this deterministic approach is successful, the stochastic nature of the process inevitably leads to rescheduling. The structure of the RTN allows for nearly one-to-one mapping into a discrete-event simulation (DES). The DES allows us to refine the grid size and input parameters for the optimization. The DES also allows for quantitative comparisons between "by-hand" schedules and the proposed optimal schedules from the RTN. This combined approach of discrete-event simulation and deterministic optimization has provided rapid...
All chemical plants require periodic turnarounds, or planned shutdowns, for maintenance purposes.... more All chemical plants require periodic turnarounds, or planned shutdowns, for maintenance purposes. When dealing with large industrial complexes and integrated sites, the scheduling of such turnarounds becomes important, as each plant may need raw materials in specific ratios that can be sourced from one or more plants in the site, and products from the plant may be required downstream as raw materials to other plants as well. The turnaround time-scale of each turnaround task is on the order of weeks, and intervals between turnarounds are on the order of years. Each specific turnaround can cost millions of dollars to perform, and in addition, incurs lost sales. This makes turnaround scheduling decisions crucial from an economic viewpoint. Thus, the turnaround scheduling task is a long-term plan for managing the operation and preventive maintenance tasks on entire plants that are part of an enterprise-wide or site-wide network. The integrated site can be represented as a network with m...
Integrated sites involve material flow in process networks. The disruption of flow due to planned... more Integrated sites involve material flow in process networks. The disruption of flow due to planned maintenance turnarounds on some process units affects production rates in both upstream as well as downstream units. Due to this, long-term maintenance planning often recommends the alignment of a subset of the turnarounds around the same time in order to make use of synergistic effects. In this paper, we consider a short-term maintenance scheduling setting, where we focus on a time scale of a few months within which a number of turnarounds are scheduled to take place. A major concern during the time leading up to a set of turnarounds is the planning for inventory build-up in anticipation of a turnaround, so as to try and maintain normal operation and satisfy demands during these long outages. Another issue is the allocation of maintenance manpower among various subtasks, which is a scarce resource that has been negotiated for months in advance. The goal of this work is to provide an op...
Proceedings of the 2011 Winter Simulation Conference (WSC), 2011
A generic model is a model that is built for a class of system and can be implemented for a speci... more A generic model is a model that is built for a class of system and can be implemented for a specific system through changes in input data alone, without any structural changes to the model. In this paper, we propose a framework for building such generic model for non-steady state process networks, which are characterized by flow of materials between
Computers & Chemical Engineering, 2015
We propose a data-driven, nonparametric approach to reformulate (conditional) individual and join... more We propose a data-driven, nonparametric approach to reformulate (conditional) individual and joint chance constraints with right-hand side uncertainty into algebraic constraints. The approach consists of using kernel smoothing to approximate unknown true continuous probability density/distribution functions. Given historical data for continuous univariate or multivariate random variables (uncertain parameters in an optimization model), the inverse cumulative distribution function (quantile function) and the joint cumulative distribution function are estimated for the univariate and multivariate cases, respectively. The approach relies on the construction of a confidence set that contains the unknown true distribution. The distance between the true distribution and its estimate is modeled via φ-divergences. We propose a new way of specifying the size of the confidence set (i.e., the φ-divergence tolerance) based on point-wise standard errors of the smoothing estimates. The approach is illustrated with a motivating and an industrial production planning problem with uncertain plant production rates.
Proceedings of the 2011 Winter Simulation Conference (WSC), 2011
The application of discrete event simulation in the process industries is commonly used for the a... more The application of discrete event simulation in the process industries is commonly used for the analysis of reliability and maintenance improvements. However there have been increasing applications that go beyond this traditional area of application to include evaluations for chemical plant expansions, capital investment options, cycle time reduction and safety, in presence of failure prone components. This paper will present
Proceedings of the 2010 Winter Simulation Conference, 2010
... ANALYSIS OF A CHEMICAL PLANT USING DISCRETE EVENT SIMULATION Bikram Sharda and Scott J. Bury ... more ... ANALYSIS OF A CHEMICAL PLANT USING DISCRETE EVENT SIMULATION Bikram Sharda and Scott J. Bury Process Optimization-Engineering Sciences, Core R&D The Dow Chemical Company Freeport, TX, USA 77541 ABSTRACT This paper describes a debottlenecking ...
Computers & Chemical Engineering, 2015
ABSTRACT An integrated chemical site involves a complex network of chemical plants. Typically, th... more ABSTRACT An integrated chemical site involves a complex network of chemical plants. Typically, these plants interact closely, are dependent on each other for raw materials and demand for their products, and have the provision of intermediate storage tanks to help manage inventory at strategic points in the network. Disruptions in the operation of these plants can drastically affect flow of material in the site network. As a result, the choice of sequence and timing of planned periodic turnarounds, which are major disruptions, is important in order to minimize effects on profits and production. We investigate a discrete-time mixed-integer linear programming (MILP) model to perform turnaround optimization. The objective is to recommend potential schedules in order to minimize losses while satisfying network, resource, turnaround, demand, financial and other practical constraints. We propose general formulations to tackle this problem and study an industrial-size site network under various scenarios over a long-term horizon.
2014 Reliability and Maintainability Symposium, 2014
ABSTRACT The Dow Chemical Company is a reliable corporation and sets and performs against very hi... more ABSTRACT The Dow Chemical Company is a reliable corporation and sets and performs against very high standards in the industry. However to meet the challenges of increasing global competition, dynamic markets for products and feedstocks and rising customer expectations, Dow has been on a multi-year journey to achieving the higher levels of enterprise-wide reliability. This is a critical component to Dow's growth strategy. Enterprise Reliability is the activity of designing and achieving reliability in all activities across the entire corporation, regardless of location, function, or business, toward the aspiration of flawlessly meeting all stakeholder commitments each and every time. Decision support tools are an important technology for Enterprise Reliability and we have adapted three traditional reliability modeling and analysis tools to meet this need. This paper presents three aspects this technology: 1) Value Stream Simulation, 2) Value Stream Optimization and 3) Data Analytics in the context of the Dow's Enterprise Reliability. These technologies were discussed in terms of the issues associated with the development, validation and deployment of the technologies to be actively used to make operating and investment decisions. Our conclusion after two years of implementation is that clarity on the data required from the models for decision making, clarity of the owner of decisions, and clarity of the structure and assumption of the models and methodologies are the keys to integrating efforts across divisions and lead to improved decision making across the envelop and lead to opportunities with a significant ROI.
High variability, stringent effluent permits, and often extreme operating conditions define the p... more High variability, stringent effluent permits, and often extreme operating conditions define the practice of wastewater treatment in the chemical industry. This paper reviews the benefits and challenges of applying dynamic simulation to chemical-industry wastewater treatment plants by describing case studies at full-scale wastewater treatment plants (WWTP). The applications range from process troubleshooting to optimization and control. The applications have been valuable and useful in developing a deeper understanding of the plants as integrated systems. However there still remains substantial work to implement the dynamic simulations for daily real-time use by plant engineers and operators. This opportunity to improve plant operations is still largely untapped and will remain so until dynamic state estimation and data reconciliation are incorporated into simulation packages for use in developing the on-line simulations. Keywords Dynamic simulation; industrial activated sludge; mode...
Journal of Industrial Microbiology, 1989
Summary Some metabolic properties of both suspended and immobilized aerobically and anaerobically... more Summary Some metabolic properties of both suspended and immobilized aerobically and anaerobically growingEscherichia coli cells were investigated. Metabolic activity was found to be substantially different whenE. coli cells were immobilized in alginate. Cells grown ...
Computers & Chemical Engineering, 2012
The challenges of supplying advanced materials and performance products are very different from t... more The challenges of supplying advanced materials and performance products are very different from those associated with commodity chemicals. Yet these challenges are well addressed by enterprisewide optimization techniques. This paper discusses the nature of advanced materials and some challenges and solutions related to product design, production scheduling, process reliability, and logistics. Ongoing research in the use of multi-agent systems for batch process management is also reviewed.
Computers & Chemical Engineering, 2012
Integrated sites are tightly interconnected networks of large-scale chemical processes. Given the... more Integrated sites are tightly interconnected networks of large-scale chemical processes. Given the largescale network structure of these sites, disruptions in any of its nodes, or individual chemical processes, can propagate and disrupt the operation of the whole network. Random process failures that reduce or shut down production capacity are among the most common disruptions. The impact of such disruptive events can be mitigated by adding parallel units and/or intermediate storage. In this paper, we address the design of large-scale, integrated sites considering random process failures. In a previous work (Terrazas-Moreno et al., 2010), we proposed a novel mixed-integer linear programming (MILP) model to maximize the average production capacity of an integrated site while minimizing the required capital investment. The present work deals with the solution of large-scale problem instances for which a strategy is proposed that consists of two elements. On one hand, we use Benders decomposition to overcome the combinatorial complexity of the MILP model. On the other hand, we exploit discrete-rate simulation tools to obtain a relevant reduced sample of failure scenarios or states. We first illustrate this strategy in a small example. Next, we address an industrial case study where we use a detailed simulation model to assess the quality of the design obtained from the MILP model.
Proceedings of the 2010 Winter Simulation Conference, 2010
A panel of simulation managers from manufacturing companies discuss the following six topics: (1)... more A panel of simulation managers from manufacturing companies discuss the following six topics: (1) How are managers responsible for manufacturing best persuaded to try simulation? (2) How can capturing the benefits of simulation best be made a regular process? What are the roles of model databases and reuse, input databases, standardization, change management, simulation project management, and training in such a process? (3) What other areas should one consider in addition to the ones listed in item 2 above in such a process? (4) Where should the Simulation Services Department reside in the organizational structure of a manufacturing company? Should it be centralized or decentralized? (5) How can simulation XVDJH ³WKH ILUVW SURMHFW´ EHVW EH XQGHUWDNHQ WR EH D VXFFHVV" +RZ FDQ PRPHQWXP EHVW EH PDLntained after simulation usage is accepted?