Hot blast stove process model and model-based controller

This paper describes the process model and model-based control techniques implemented on the hot blast stoves for the No. 7 Blast Furnace at the Inland Steel facility in East Chicago, Indiana. A detailed heat transfer model of the stoves is developed and verified using plant data. This model is used as part of a predictive control scheme to determine the minimum amount of fuel necessary to achieve the blast air requirements. The model is also used to predict maximum and minimum temperature constraint violations within the stove so that the controller can take corrective actions while still achieving the required stove performance

State estimation of chemical engineering systems tending to multiple solutions

A well-evaluated state covariance matrix avoids error propagation due to divergence issues and, thereby, it is crucial for a successful state estimator design. In this paper we investigate the performance of the state covariance matrices used in three unconstrained Extended Kalman Filter (EKF) formulations and one constrained EKF formulation (CEKF). As benchmark case studies we have chosen: a) a batch chemical reactor with reversible reactions whose system model and measurement are such that multiple states satisfy the equilibrium condition and b) a CSTR with exothermic irreversible reactions and cooling jacket energy balance whose nonlinear behavior includes multiple steady-states and limit cycles. The results have shown that CEKF is in general the best choice of EKF formulations (even if they are constrained with an ad hoc clipping strategy which avoids undesired states) for such case studies. Contrary to a clipped EKF formulation, CEKF incorporates constraints into an optimization problem, which minimizes the noise in a least square sense preventing a bad noise distribution. It is also shown that, although the Moving Horizon Estimation (MHE) provides greater robustness to a poor guess of the initial state, converging in less steps to the actual states, it is not justified for our examples due to the high additional computational effort

Family Businesses and Adaptation: A Dynamic Capabilities Approach

The main objective of this research was to propose a framework centred on the dynamic capabilities approach, and to be applied in the context of family businesses’ adaption to their changing business environment. Data were gathered through interviews with ten FBs operating in Western Australia. Based on the findings, the clusters of activities, sensing, seizing, and transforming emerged as key factors for firms’ adaptation, and were reinforced by firms’ open culture, signature processes, idiosyncratic knowledge, and valuable, rare, inimitable and non-substitutable attributes. Thus, the usefulness of the proposed framework was confirmed. Implications and future research opportunities are presented. © 2018, The Author(s)

Implicit Newton-Krylov methods for modeling blast furnace stoves

In this paper the authors discuss the use of an implicit Newton-Krylov method to solve a set of partial differential equations representing a physical model of a blast furnace stove. The blast furnace stove is an integral part of the iron making process in the steel industry. These stoves are used to heat air which is then used in the blast furnace to chemically reduce iron ore to iron metal. The solution technique used to solve the discrete representations of the model and control PDE`s must be robust to linear systems with disparate eigenvalues, and must converge rapidly without using tuning parameters. The disparity in eigenvalues is created by the different time scales for convection in the gas, and conduction in the brick; combined with a difference between the scaling of the model and control PDE`s. A preconditioned implicit Newton-Krylov solution technique was employed. The procedure employs Newton`s method, where the update to the current solution at each stage is computed by solving a linear system. This linear system is obtained by linearizing the discrete approximation to the PDE`s, using a numerical approximation for the Jacobian of the discretized system. This linear system is then solved for the needed update using a preconditioned Krylov subspace projection method

Electron Beam Evaporation of Silicon for Poly Silicon SiO2 Passivated Contacts

We assess the use of electron beam physical vapor deposition EB PVD for the deposition of silicon layers to be used in doped poly Si SiO2 passivated carrier selective contacts. It is shown that the crystallinity of the deposited layer can be tuned by the substrate temperature. Nano crystalline nc Si intrinsic layers deposited at substantially different deposition rates of 25 nm min and 500 nm min show similar doping profiles after an ex situ doping by POCl3 diffusion and similar passivation quality with iVoc gt; 715 mV for symmetrical lifetime samples on a n type substrate. Best passivation characteristics with iVoc of 732 mV and J0e of 3 fA cm2 are achieved for in situ doped layers with an active phosphorous concentration of [P] 2 1020cm 3 after annealing. A low sheet resistance of 142 amp; 937; sq for a 100 nm thick layer make this stack eligible for ready integration into a screen printed solar cell. While layer properties are shown to be similar to those of parallel processed LPCVD layers, the single sided deposition characteristic EB PVD constitutes a significant advantage for easy integration of the process step into a lean industrial process flo

Implicit Newton-Krylov Methods for Modeling Blast Furnace Stoves

In this paper we discuss the use of an implicit Newton-Krylov method to solve a set of partial differential equations representing a physical model of a blast furnace stove. The blast furnace stove is an integral part of the iron making process in the steel industry. These stoves are used to heat air which is then used in the blast furnace to chemically reduce iron ore to iron metal. The simulation of the stove's behavior is the first step in a program to reduce the cost of operating these stoves by minimizing the natural gas consumption during the heating cycle, while still maintaining a high enough output air temperature in the cooling cycle to drive the needed chemical reaction in the blast furnace. The formulation and solution of this optimal control problem will also be discussed. The solution technique used to solve the discrete representations of the model and control PDE's must be robust to linear systems with disparate eigenvalues, and must convergence rapidly without using tu..