Total control
Process automation played a key role in ensuring operational efficiency, safety and reliability at the 200,000m3/day Tlemcen-Honaine desalination plant
Javier Casado
GEIDA, a consortium of Spanish companies made up of Befesa Agua from Abengoa and Sadyt from Sacyr Vallehermoso, focuses on the construction and operation of desalination plants in Algeria. Together with Algerian Energy Company (AEC), GEIDA is developing the 200,000 m3/day seawater reverse osmosis (SWRO) desalination plant in Honaine, Tlemcen under a 25-year Build, Own, Operate (BOO) contract. In addition to the desalination plant, the Tlemcen-Honaine complex also includes a ‘University of Water’ and a development centre.
At its third plant in Algeria, GEIDA took on the huge challenge to build the plant (its third such project in Algeria) that would treat seawater and produce drinking water for more than 750,000 people in the region. In order to accomplish this task, the company decided to partner with Honeywell Process Solutions as its automation and control provider.
Miguel Larrinaga, Instrumentation, Control & Electricity Assembly Manager, Befesa Agua International División, said: “We had specific requirements of the automation and control provider that we would select. The company had to demonstrate its ability to execute a project of size and scope and provide the maintenance and onsite staff, which we felt were imperative to make this project a success.”
Desalination is a continuous process, from sea water intake to product output; hence, the process control is similar to other industrial processes. However, desalination is also different from typical industrial processes due to discontinuous processes in the filtration stage, related to the cleaning operation of those filters.
Honeywell’s scope included Experion PKS automation system with an operator console, engineering station and six C300 redundant controllers. The controllers are centralised, while four remote locations, physically distributed and communicating through a redundant fibre optic, accomplish the I/O integration.
Javier Casado, Account Manager-Business Development, Honeywell Process Solutions said: “The operational priorities for an RO desalination plant operator are maximum plant availability, minimum downtime, production adjustment to demand and reduction of electricity consumption. This justifies the need for remote operation and visualisation. Experion PKS, through the DSA (Distributed Server Architecture) integration, facilitates monitoring and integration of plants located in different control centres, while maintaining a unique database. Experion PKS allows integration, through the plant information network, with other control networks.”
The equipment managed by the controllers includes field process instrumentation with HART communications and a motor control centre for command and diagnostics and monitoring of the electrical substation.
The four locations are physically sequenced, following the entire desalination process as follows:
- First, the location where the seawater intake happens
- Second, the two-phase filtration process
- Third, the main osmosis process
- Fourth, where the pure water is mixed with additives like salt to make it fit for human consumption.
Honeywell also installed a second fibre optic network for integrating electrical information from motor control centres (MCCs), both low and medium voltage. This is also subdivided in the four phases with the integration allowing the C300 controllers to perform commands to the MCC through Modbus protocol communications, where the auxiliary motor information is coming from. Experion controllers can directly communicate with these devices without the need for cumbersome gateways. The Ethernet electrical network also travels to the main location where an electrical substation is integrated.
The sequential control was implemented through Experion Control Builder by configuring control modules and sequential control modules that also provide real-time graphical monitoring of control execution to greatly ease process troubleshooting. Additionally, the project incorporates Honeywell eServer and a Honeywell Field Device Manager (FDM) for management of smart devices using HART.
Drawing attention to some of the project-highlights, Casado said: “There was a significant use of generic control programming, as well as generic operation graphics, sometimes referred to as templating. A specially designed asset tree gives operators an overview of the Experion PKS and sub-system assets. This templating system has been extensively used in the filter network, leading to a significant reduction in time for implementation of work and tests. It will also further simplify maintenance tasks in the system application.”
On the incorporation of redundancy, Casado pointed out that redundant controllers have been taken into account. He said, “Input and output modules are non-redundant, although a line distribution for filtration and reverse osmosis was designed in order to ensure availability and to maintain production plant capacity at 80%.”
Elaborating on the networking and communication protocols used in this project, Casado said, “A Modbus TCP helps integrate the MCC diagnostics and substation. HART has been used for field instrumentation. There was also a need for long-distance communications with a destination tank approximately 15 kilometres away from the site. In this case, flow, level variables and plant data will be transmitted via Profibus in order to have a set point for production regulation as per demand. This will allow the operator to automatically regulate production as required. A night plant operation is also being considered in order to take advantage of the night consumption rate.”
Larrinaga praised Honeywell’s role as a key factor in GEIDA being “able to start up this facility ahead of time and on budget and achieve the reliability, safety and efficiency expected at our desalination plant.”
Casado added: “Honeywell’s Experion system is tailored to the needs of remotely located and distributed plants. As a result, our system architecture has been optimised to become better adapted to the installation. Another factor is the marshalling of cables. Honeywell has designed the input and output signals to I/O processors/channels in order to allow for the assignment of multiple cables. In this way, cross-wiring in marshalling cabinets has been minimised and helped speed up the deployment process.”
Given the concerns about securing critical national assets like desalination plants against threats originating in the networks (all the more important if one takes into account remote operations), how does Experion PKS address this issue? Casado pointed out that the plant’s assets are secured by a firewall at the FTE (Fault Tolerant Network) level. In addition to this, C300 control processor integrity is ensured through the use of the exclusive Experion Control Firewall.
Category: Utility Management
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