Operator Training Simulator in Chemical Processes

High fidelity dynamic process simulators have been widely used by all major oil and gas industries not only within process design studies, detailed engineering studies, process debottlenecking and control system verification but also for operator training (Cameron et al., 2002; Bessiris et al., 2011). In other industries such as palm oil mills, automation is quite limited. Sivasothy and Lim (1985) reported that this

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was not due to hardware limitations or reluctance by the industry to adopt automation, but rather due to software limitations.

In the late 1980's and early 1990's, implementation of OTS in the chemical industry has become the common practice. Cameron et al. (2002) reported that training simulators have been widely adopted in industries such as offshore oil & gas industry and power & energy industry, where capital investment is high, processes are complex and the consequences of plant or operator failure are severe. As reported by Cameron et al. (2002), older training laboratories for training in the oil industry were based on physical replicas of the control room which are now expensive and unnecessary.

In industries, object linking and embedding for process control (OPC) is commonly used as industrial communication standard that enables the exchange of data between the server and clients.OPC is a client-server technology that acts as an interface between the server and the client. One application acts as the server providing data while another acts as a client that uses the data. Using OPC standards, applications (e.g. control applications) from different vendors can be linked as they share common standards. Table 2.3 summarizes the applications and main feature(s) of OTS in relevant chemical industries/processes which use modular softwares for the OTS development. However, very limited studies on OTS have been found in the open literature, the number of papers published in this area has increased considerably in the last decade.

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Table 2.3 Applications and highlights of OTS in chemical industries.

System/Industry Main feature(s) Software used/

programming

Reference

1 Blending process and distillation process

 Designing and tuning advanced process the effects of the operating variables.

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Table 2.3 Applications and highlights of OTS in chemical industries (continued).

 A virtual environment for industrial process and data the combination of a coding framework and a process

EcosimPro Santos et al.

(2008)

 User interfaces were designed, on which the user could adjust process control parameters such as for pumps, valves etc., and gain information about

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Table 2.3 Applications and highlights of OTS in chemical industries (continued).

Ye et al. (2000) developed an OTS for the blending process and distillation column using SimSuite Pro software. The dynamic simulation of the process is carried using SimSuite Pro software that is modular in nature. The OTS included a complete dynamic model of the process and advanced process control system. The OTS was used in operators’ training for tuning the advanced process controllers and for pre-configuring the connection between the APC controllers and the DCS systems. An OTS for the industrial cracking furnaces in an ethylene plant is developed by Joo et al (2000). OTS also included a feed characterization module that is built using artificial neural network; This is able to estimate the composition of conventional components from the commercially available indices such as ASTM,

11 Petroplus coryton

 OTS included simulations of a heat exchanger and a distillation column.

Simulator by

 Integrated a dynamic process simulator with a dynamic accident simulator for training operators.

 Studied the influence of process control and automation strategies on the sustainable operation of a

bioethanol process.

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specific gravity etc. An OTS ‘CRACKER’ developed by them has a user-friendly graphic interface. Park et al. (2001) developed an OTS for batch chemical processes using gPROMS, which they called as ‘yOTS’. OTS is built in the INIX environment.

Important feature of this OTS was that they included a virtual environent similar to a real DCS system. yOTS is a network-based training simulator, where several trainee can be trained on a single network. The main features of the yOTS include: tutoring the principles of target processes and evaluating the trainee’s performance.

Yang et al. (2001) developed an OTS for methyl tertiary butyl ether (MTBE) process. The developed OTS is tested for startup, normal operation and shut down.

However, many emergency scenarios, such as utility failure, pump/valve malfunction, etc, are not studied by them. The developed OTS provided valuable experiences on dealing with non-standard operations and in enabling effective start-up policies to be developed. An OTS for the sovent production plant at the Colombian Petroleum Company refinery is developed by Torres et al. (2004) using Hysys. Process model is developed with the interfaces emulating the DCS of the real plant. This enhances the effectivity of the training as emulated DCS is used. They concluded that improved operators’ skills, faster plant startups, checking of the DCS configuration, pre-tuning of control loops, modifications design for operation improvements and reduced risk, were obtained.

Vasconcelos et al. (2005) developed an OTS for ethanol dehydration process using Hysys.Plant. They created a virtual environment for industrial process and data representations for operator and engineer training. The virtual environment provided the real feel of the process to make the OTS training more effective. Hass et al.

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(2005) developed an OTS for the bioreactor. The model was developed, parameterized and tested using eStIM (a coding framework specialized for the rapid prototyping of dynamic models). WinErs® (process control software) is used for the user interface in the transformation of a standalone process model into an operator training system. Santos et al. (2008) used EcosimPro in the development of an OTS for sugar factory. They described a distributed continuous simulation of an industrial scale case study using DCOM components (DCOM is the Microsoft solution for a component software bus, used by the environments for the creation of distributed simulation).

Pereira et al. (2009) developed an OTS for the PETROBRAS’ oil & gas production process and utilities simulator environment called AMBTREI (Training Environment) that imitated the actual control room of an E&P semi-submersible platform at a very high fidelity level. They used Hysys for process model development. However, they have not studied the transients of the process under emergency scenarios, such as pressure relief valve, bursting disks, fire, utility failure etc. Kuntzch (2010) used FORTRAN source code and compiled it with the eStIM-software package for the development of an OTS for Bioethanol fermentation process. The individual models are combined and supplemented by WinErs-control structures to form an overall-process model. Munn et al (2012) used Simulator (by Simulation Solutions, Inc) for the OTS development for Petroplus coryton (heat exchanger and distillation column). The heat exchanger and distillation modules are accompanied by a virtual reality (VR) outside operator view in which the students can locate, monitor, and operate various field devices such hand valves, block valve, pumps, etc. Application of UniSim is also found in the OTS development. Manca et

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al. (2013) developed an OTS for the Hydro-dealkylation (HDA) using UniSim sodtware. They presented a training solution based on Virtual Reality (VR) and Augmented Virtual Reality (AVR), specifically addressing the process industry.

Balaton et al. (2013) also used UniSim in the OTS development for a batch processing unit. The different modelling solutions, for example, a mixture of water and ethylene glycol, for the batch reactor vessel and the effect of measuring instrument models were studied. Recently, Hass (2014) developed an OTS for the bioethanol plant. They used eStIM for kinetic and sub-unit models, which are implemented in WinErs process control system. The OTS is based on mechanistic and dynamic process models describing the unit operations and equipment such as valves, pumps, etc.

To conclude, this literature review shows that OTS has found it application in the wide areas of chemical process industry. Also, it is concluded from Table 2.3 that most of the OTS development has utilized the flowsheeting tools, such as hysys, UniSim, EcosimPro, ProSim, SimSuite Pro and D-Spice. This is due to modular structure of these flowsheeting tools that offer the flexibility in the vent of the plant modification or scaleup. Also, these tools have capability of being interlinked with control systems (e.g. DCS) via OPC. However, these published studies do not present the transients of the process under emergency scenarios, such as pressure relief valve, fire, steam failure etc. The industries that have mainly adopted the OTS are: petroleum industry, oil and gas industry, petrochemical industry, and power/energy producing industries. The main reasons behind these industries adopting OTS can be listed as: the high risk in terms of the safety and capital.

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On the other hand, the OTS is not commonly used in the field of bioprocess engineering (such as enzymatic processes) possibly because: 1) normally, the operating conditions are moderate in bioprocesses and so the associated risk is relatively lower, and 2) bioprocesses are usually specialized and operated on a small scale, most on bach scale. Consequently, the benefits of using OTS in bioprocess field have not been properly evaluated. Also, it is worth noticing that the OTS has been reported for biodiesel production from WCO. In addition, sectors such as oil mills and other small-scale chemical industries, have not adopted OTS significantly.

This could be due to the reasonably lower risk associated with such processes and the higher cost of OTS. Additionally, it can be concluded that Aspen Plus Dynamics and Aspen OTS Framework has not been used for the OTS development for any chemical process. Therefore, there are enough scopes for the exploration of the OTS development. Also, it is important to note that the benefits of process models can be greatly extended by transferring them into an OTS. The issues related to the OTS development and implementation are described in the following section.

2.5.4 Issues Related to the Development and Implementation of