Process Simulators: meant for more than just training
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In the past, control systems were used for both engineering and on-the-job-training. Efficiencies at most plants were low and high losses in production time were common, mostly due to mistakes in plant operation. The invention of the training simulator changed this, though. Training simulators were utilized to realize efficiencies whilst ensuring that operators were skilled enough to operate the plant safely during both normal and abnormal situations.
Simulators have come a long way since their inception and today are beneficial for the life of the plant -- from cradle to grave. From initial design through construction and control system design/validation (even throughout replacing the control system many years down the road), operational training simulators (OTS) can bring great value to a company's bottom line. With the recent developments of PCs and hardware, simulators are tied closely to the control system (more now than ever before), specifically for validating design and shortening the lifecycle of particular projects.
Control Design Validation
Control scheme design plays an important role in improving safety and reducing complexity in operations from the perspective of the operators. With an absence of a simulator system, the control scheme is validated theoretically on paper. This approach lends little confidence to the performance of the new control scheme under operating conditions that vary. With the availability of simulators that mimic the actual behavior of the plant, the control schemes can be validated for nearly all possible scenarios and implemented on a real plant, avoiding costly discoveries during commissioning or the steady-state operation phase of the plant
Control System Development and Checkout
For many years control system software on greenfield projects was developed on the actual staged control system. While the hardware was being tested, engineers were able to check HMI graphic displays, alarm settings and certain control functions such as controller action, trip settings and alarm functions.
Control system software today, having the capability of virtual simulation mode coupled with dynamic simulators, helps to validate several aspects: loops and alarm configuration, response time… all the way up to the HMI level, helping to reduce the commissioning time of the plant.
Operation Procedure Validation
Dynamic simulators for greenfield projects play an important role not only in training the operators and validating the control schemes prior to the commissioning stage, but also in significantly helping the operations personnel validate the Standard Operation Procedures (SOP). The SOP can be corrected when the plant startup is carried out using the OTS system, as process improvements and optimizations at this stage will be well understood.
OTS as a Development Platform
Configuring complex control schemes on the live control system presents several risks to the process operation. In facilities where the control engineers do not have a development or test platform, all of their work must be done on the running control system -- No wonder they keep control schemes as simple as possible -- Taking on OTS system support is considered to be extra work by most control engineers, but as engineers we must understand the great benefits in the development and testing of complex control schemes on the OTS and commissioning the loops, without incident or accident.
Platform for Model-based Controls Design and Implementation
Model-Based multivariable controls, or Advanced Process Control (APC), helps in operating the plant safely and efficiently, reducing the operator workload by operating the plant 24/7. Design, development and testing, and implementation of the multivariable controls takes significant amounts of time due to several factors including plant availability, availability of raw materials in desired compositions, process responses, availability of lab technicians to analyze the sample results, etc. By using simulators that mimic real plant behavior, model-based controls can be designed, and testing can be conducted to develop SEED models. These SEED models can be used on the real plant and corrected for accuracy using automated plant test tools, thereby improving safety and efficiency, whilst reducing the cost of model-based control project implementation.
Typically for greenfield projects, the traditional APC project life will be longer due to constraints of plant availability as shown in blue below. Given that simulators are available, the APC project lifecycle can be reduced and the end users can commission the APC controllers ahead of time, as shown in green.
In a nutshell, simulators are well worth the investment for a plant, as it helps to save time and money during plant commissioning and startup, and optimizes the plant quicker than normal.
