Supervisory controllers

Most new autoclaves now come with supervisory controllers, and there is no question that these could improve the reliability of temperature-based recipes. The primary advantage is that these controllers allow for control of the condition of the resin rather than the condition of 

---

Control Devices. Control devices have advanced from manual control to sophisticated computet-assisted operation. Radiation pyrometers in conjunction with thermocouples monitor furnace temperatures at several locations (see Temperature measurement). Batch tilting is usually automatically controlled. Combustion air and fuel are metered and controlled for optimum efficiency. For regeneration-type units, furnace reversal also operates on a timed program. Data acquisition and digital display of operating parameters are part of a supervisory control system. The grouping of display information at the control center is typical of modem furnaces. 

Process control philosophy (e.g., computerization that removes supervisory control from the operator and may lead to inability of the operator to respond effectively to an abnormal situation)... 

In this short initial communication we wish to describe a general purpose continuous-flow stirred-tank reactor (CSTR) system which incorporates a digital computer for supervisory control purposes and which has been constructed for use with radical and other polymerization processes. The performance of the system has been tested by attempting to control the MWD of the product from free-radically initiated solution polymerizations of methyl methacrylate (MMA) using oscillatory feed-forward control strategies for the reagent feeds. This reaction has been selected for study because of the ease of experimentation which it affords and because the theoretical aspects of the control of MWD in radical polymerizations has attracted much attention in the scientific literature. 

Real-time synthesis of operating procedures. Most of the ideas and methodologies, presented in this chapter, are applicable to the a priori, off-line, synthesis of operating procedures. There is a need though to address similar problems during the operation of a chemical plant. Typical examples are the synthesis of operational response (i.e., operating procedure) to process upsets, real-time recovery from a fallback position, and supervisory control for constrained optimum operation. 

Any learning procedure, aimed to address and solve problems given by the problem statement (2) at the supervisory control level of decisionmaking, can be expressed by the following quartuple ... 

In this chapter we revisited an old problem, namely, exploring the information provided by a set of (x, y) operation data records and learn from it how to improve the behavior of the performance variable, y. Although some of the ideas and methodologies presented can be applied to other types of situations, we defined as our primary target an analysis at the supervisory control level of (x, y) data, generated by systems that cannot be described effectively through first-principles models, and whose performance depends to a large extent on quality-related issues and measurements. 

The correct interpretation of measured process data is essential for the satisfactory execution of many computer-aided, intelligent decision support systems that modern processing plants require. In supervisory control, detection and diagnosis of faults, adaptive control, product quality control, and recovery from large operational deviations, determining the mapping from process trends to operational conditions is the pivotal task. Plant operators skilled in the extraction of real-time patterns of process data and the identification of distinguishing features in process trends, can form a mental model on the operational status and its anticipated evolution in time. 

Bakshi, B. R., and Stephanopoulos, G., Representation of process trends. Part IV. Induction of real-time patterns from operating data for diagnosis and supervisory control. Comput. Chem. Eng. 18 303 (1994b). 

Application of the Data Reconciliation and Gross Error Detection Procedure within a Supervisory Control Scheme for the Column... 

In supervisory control, process and economic models of the plant are used to optimize the plant operation by maximizing daily profit, yields, or production rates. The computer program reviews operating conditions periodically, computes the new conditions that optimize a chosen objective function, and adjusts plant controller set points, thus implementing the new improved conditions. This scheme will obviously require a model of the plant, current information about operating conditions from the plant s control system, and finally, sophisticated optimization software. 

Determination of critical assets that might be subject to malevolent acts that could result in undesired consequences What are the malevolent acts that could reasonably cause undesired consequences on these assets electronic, computer, or other automated systems that are utilized by the public water system (e.g., Supervisory Control and Data Acquisition (SCADA)) the use, storage, or handling of various chemicals the operation and maintenance of such systems... 

Ezell, B. C. 1998. Risks of cyber attack to supervisory control and data acquisition for water supply. PhD diss., University of Virginia. 

Intrusion through Supervisory Control and Data Acquisition (SCADA)... 

W. Cyber-security/Supervisory Control and Data Acquisition (SCADA) system attack response (other than incident-specific, e.g., hacker)... 

---