Case Study: High-Accuracy Chemical Dosing System for Refinery Applications

Snapshot

- Client: Major Australian refinery

- Application: Corrosion control chemical dosing (Crude Flash Column & Stripper)

- Legacy issue: Inaccurate dosing from pneumatic metering pumps

- Solution: Pulsafeeder PulsaPro PP680-SE diaphragm metering system

- Key results: ±0.5% dosing accuracy, improved reliability, enhanced safety & access

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Client and Application Overview

Australia's largest transport fuel supplier and convenience retailer commissioned Kelair Pumps to design and supply a replacement metering system for its Crude Flash Column and associated Stripper units. The existing system utilised air-driven piston-type metering pumps to dose process chemicals critical to corrosion control.

This case study is particularly relevant for process engineers, reliability teams and maintenance planners working in refining and petrochemical plants.

The chemicals injected include:

• A neutraliser for controlling acidic corrosion and mitigating salt formation
• A corrosion inhibitor to reduce material degradation and extend equipment service life

The legacy system consisted of a stainless steel bunded enclosure containing a fixed lower IBC, process pipework, metering pumps, and a visual level indication system. A secondary IBC was mounted above the enclosure, providing gravity-fed replenishment to the primary container. Once depleted, the upper IBC was removed via forklift and replaced, maintaining batch-style replenishment.

A key limitation of the existing configuration was the reliance on pneumatic metering pumps. These systems are inherently sensitive to variations in plant air supply pressure, resulting in fluctuating stroke characteristics and reduced dosing accuracy. This variability introduced risk in maintaining consistent chemical concentration within the process.

Similar legacy pneumatic systems are still widely installed in refineries and petrochemical plants, where they can be a hidden contributor to inconsistent corrosion control and higher chemical consumption.

Design Challenge

The primary engineering objective was to deliver a dosing system capable of:

• High-accuracy, repeatable chemical injection under varying operating conditions
• Improved process stability compared to pneumatic systems
• Safe handling and containment of hazardous chemicals
• Maintainability and operator accessibility in accordance with relevant standards

Additionally, the system needed to integrate with existing operational practices, including IBC handling and replenishment.

Engineering Approach and Technology Selection

The key requirement for the upgraded system was to achieve a high level of dosing accuracy and repeatability under varying operating conditions, while also improving reliability, safety, and maintainability.

Drawing on our experience with refinery chemical injection systems, Kelair Pumps team engineered a solution that maintained familiar site handling practices while significantly improving dosing accuracy, safety and maintainability.

To meet these objectives, Kelair Pumps selected technology from Pulsafeeder, incorporating the PulsaPro PP680-SE as the core metering device.

The PulsaPro platform utilises a hydraulically actuated diaphragm design, enabling precise volumetric displacement largely independent of discharge pressure fluctuations. This operating principle removes the dependency on compressed air and eliminates the variability associated with pneumatic systems. As a result, the pump can maintain a dosing accuracy of ±0.5% of the set point, with a high degree of repeatability across its operating range.

This helps minimise both under-dosing (risking corrosion) and over-dosing (wasting expensive chemicals), directly impacting lifecycle cost and asset protection.

This level of control is particularly important in refinery processes where even small deviations in chemical dosing can have cumulative effects on corrosion rates and downstream equipment integrity.

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Technical performance highlights:

• Flow accuracy of ±0.5% of set point
• High repeatability across the operating range
• Reduced susceptibility to process disturbances
• The noise generated from the pneumatic pump is eliminated

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Operational and business benefits:

• More consistent corrosion control and asset protection
• Reduced risk of over-dosing expensive chemicals
• Quieter, safer working environment for operators
• Less operator intervention to “chase” dosing variations

System Design and Integration

The dosing system was engineered as a skid-mounted, fully bunded package to ensure safe handling and containment of chemicals. The bunded base provides secondary containment in the event of leaks or spills, aligning with standard industry safety practices for hazardous fluid systems.

At the core of the system are 1500-litre “mother tanks”, which serve as the primary chemical reservoirs. These are replenished from IBCs positioned on an elevated structural platform integrated into the skid. The elevated arrangement allows gravity-assisted transfer into the mother tanks while maintaining the existing operational approach familiar to site personnel.

The structure includes:

• Stairways, walkways, and access platforms
• Handrails designed in accordance with AS1657
• Safe and compliant access for inspection, maintenance, and IBC changeover

From a process perspective, the system incorporates a comprehensive arrangement of mechanical and instrumentation components to support stable and reliable operation, including:

• Suction strainers – installed upstream of the pumps to prevent particulate ingress and protect internal components
• Calibration columns – allow manual verification of flow rate and pump performance during commissioning and periodic validation
• Pulsation dampeners – minimise pressure fluctuations in the discharge line, improving flow stability and reducing mechanical stress on the piping system
• Pressure gauges – provide operators with real-time system feedback at key locations
• Check valves – ensure correct flow direction and prevent backflow
• Pressure relief valves – provide overpressure protection for both equipment and personnel
• Isolation ball valves – enable maintenance and servicing of individual components without requiring a full system shutdown

All process pipework is constructed from stainless steel to ensure chemical compatibility and provide long-term corrosion resistance.

Performance Outcome and Benefits

The upgraded dosing system delivers a significant improvement in process control and reliability. By replacing pneumatic driven metering with an electric motor driven diaphragm system, our client achieved:

• Stable and precise chemical dosing independent of air supply conditions
• Improved corrosion control through consistent inhibitor and neutraliser injection
• Enhanced operational safety via integrated bunding and compliant access systems
• Precision metering to drive operational reliability and maximum system availability

Overall, the project demonstrates the value of modern metering technology in refining applications where precision, reliability, and safety are critical to long-term performance.

Site feedback has highlighted more stable dosing performance, fewer manual adjustments and reduced troubleshooting compared to the legacy pneumatic system, reinforcing the benefits of the upgrade in day-to-day operation.