Executive Summary
Air Liquide Bulgaria EOOD operates as part of Air Liquide Group, a French multinational leader in industrial gases and related services, founded in 1902. The Bulgarian subsidiary has been active since 1999, supplying oxygen, nitrogen, argon, and other gases to key industries such as metallurgy, chemicals, and manufacturing. Its Pirdop Plant, established in partnership with Aurubis Bulgaria, plays a strategic role in the copper smelting sector, ensuring a stable supply of industrial gases for large-scale operations.
With ongoing investments, including a new high-efficiency air separation unit planned for 2027, Air Liquide Bulgaria continues to enhance capacity, reduce energy consumption, and strengthen its position as a reliable and sustainable industrial partner in the region.
In 1998, Air Liquide and Yokogawa reached a global agreement whereby Yokogawa became Air Liquide’s preferred global supplier of process control systems. This was the result of an intensive yearlong technical and commercial evaluation by this company’s headquarters. One of Air Liquide’s basic motives for this agreement was the need to maintain global competitiveness. Yokogawa’s global support organization recognized reputation for superior product quality, and proven track record in consistently delivering high-quality engineering services were all factors leading to this agreement.
To strengthen its competitiveness in an ever-changing industrial gas market, Air Liquide launched a Control System Replacement Project in Pirdop Plant in 2023 to improve flexibility, reliability, and safety of its operations. Yokogawa is supplying and implementing CENTUM VP R6 control systems as a consolidated and complete plant-running approach. This includes engineering, installation, and commissioning of the systems, as well as training for plant operators. The modernization is driven by Air Liquide's need to adapt to changes in the industrial gas market and improve its competitiveness.
The total project execution time frame is Feb 2024 – Aug 2025, and is divided into 4 main phases:
- Phase 1: Site survey
- Phase 2: Project planning
- Phase 3: Basic design
- Phase 4: Complete detailed design, Implementation, Tests, Commissioning and Start-up support for Pirdop Plant.
- Phase 5: Field works and mechanical
The Challenges and the Solutions
Air Liquide Pirdop Plant upgrade and migration scope relied mainly on reverse engineering, since documentation was scarce, incomplete or obsolete (~20% of it was identified for the design phase).
The main project scope was defined from the ground up with a mix of detailed Site Survey, joint team’s efforts and expertise in extensive workshops appliance of KAIZEN principles, throughout the project execution.
Following units in Pirdop Plant were migrated in the new upgraded CENTUM VP R6, from various vendors:
- CVK compressors (2 units - CVK#1 and CVK#2), migrated from Allen Bradley
- PGW – 2 units (3 and 6) from GE Fanuc
- Sigma – 2 units (145 and 190) from Schneider Electric
- Utilities – total re-wiring and integration in the main system
The packages that were integrated in Yokogawa DCS (distributed control system) for a consolidated, optimized and efficient functionality in operations:
- IR air compressor
- FPU unit
- Chiller unit
For all of the above, Field Works phase had the objective to ensure timely:
- Replace and sometimes re-route old and unfit field instrumentation cables
- Install new system cables where needed
- Installation and connection of JB’s
- Network cabinet and equipment for cyber security as well as structured data network and FO tracing and installation
- Ensure plant power redundancy by connecting 2 new UPSs units
- 2 new MCC cabinets for the Sigma interfacing in field
- Troubleshoot and fix hidden flaws in field wiring
- New cable traces mechanical installation
- Re-wiring of existing instrumentation and tests
Swift project execution
Swift project execution was important to Air Liquide, and for this reason the company decided to keep a single point of communication and responsibility. As such, Air Liquide chose to have all the electrical and installation work coordinated and supervised by Yokogawa, acting as a MAC (main automation contractor). This proved to be very successful, and this is now the standard operation mode for all projects.
High flexibility required
Reverse engineering approach inherently brings unexpected findings in both hardware and software that need immediate action and overall agile approach (LEAN). While working in field during commissioning, a lot of items needed on-spot modification, material ordering and quick planning and installation. Hence, Air Liquide and Yokogawa partnered in a gentlemen agreement to solve issue a.s.a.p. and conclude to the related commercial forms later, after the job is finished.
Customer Satisfaction
During the initial discussion in the sales phase, Air Liquide highly appreciated Yokogawa’s explanation of a clear path forward from their current situation that would allow them to meet their future needs without compromising their challenging constraints. This contributed to Air Liquide’s decision to go ahead with this project.
Using Yokogawa CENTUM VP control system, an integrated solution was put in place which increased the plant capacity, stability and removed points of failure. The plant units were automated to ensure a high degree of flexibility in responding to fluctuations in demand and to enable automatic plant start-ups and shutdowns.
System Details
The project team included software and hardware engineers from Yokogawa Romania (MAC) and very supportive personnel from Air Liquide Bulgaria EOOD. Special protection measures were taken in order to ensure team members’ safety and to avoid communication and commissioning disruptions.
Air Liquide Bulgaria EOOD - DCS replacement
- Upgrade to CENTUM VP R6.09
- Field control stations
- Operator station
- Supervisor station
- Engineering station
- Third party subsystem integration (Modbus)
- Time synchronization with GPS master clock
- Network security and alignment with Air Liquide policies and access control
- Full CCR upgrade, including large screen displays for enhanced operation.
Súvisiace odvetvia
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Chemical
Chemical plants rely on continuous and batch production processes, each posing different requirements for a control system. A continuous process calls for a robust and stable control system that will not fail and cause the shutdown of a production line, whereas the emphasis with a batch process is on having a control system that allows great flexibility in making adjustments to formulas, procedures, and the like. Both kinds of systems need to be managed in available quality history of product, and to be able to execute non-routine operations. With its extensive product portfolio, experienced systems engineers, and global sales and service network, Yokogawa has a solution for every plant process.
Súvisiace produkty a riešenia
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Distributed Control System (DCS)
Our distributed control system (DCS) enables automation and control of industrial processes and enhanced business performance. Over 30,000 systems entrust Yokogawa DCS to deliver their production goals.
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Modernization Services
A variety of services that help to strengthen competitiveness by modernizing production system assets and digitalizing operations.