High-Pressure Injection Skid for Microgravity Process Control
For an aerospace research partner, IRIAN MECATRONICS designed and built a multi-fluid injection skid to feed a supercritical water oxidation (SCWO) reactor in a microgravity environment.
The system ensures precise, programmable injection of three separate fluids (water, hydrogen peroxide, ethanol) and regulates process pressure up to 330 bar.
The Challenge: Stable Injection When Gravity Disappears
Supercritical water oxidation is a promising technology for treating organic waste in confined environments. It requires the controlled injection of reagents into a chamber held at high pressure and temperature. This project’s challenge was to design an injection system capable of operating reliably in an onboard laboratory, in the absence of gravity.
In such an environment, the basic principles of fluid management no longer apply: – Open-surface reservoirs are unusable, as liquids do not settle. – Any unmanaged gas bubble can block a circuit or compromise an injection. – Pumps must guarantee a stable, pulse-free flow rate, regardless of their orientation.
Standard laboratory equipment, which implicitly relies on gravity, is not an option. An architecture designed from the ground up for positive control of every milliliter of fluid was required.
Our Bespoke Engineering Approach
Faced with these constraints, our engineering team developed a fully deterministic fluidic architecture.
1. Positive-Pressure, Free-Surface-Free Storage The first challenge is fluid storage. We solved it using three 200 mL bladder accumulators. A gas pressure (compressed air up to 10 bar) applied to the exterior of the Viton bladder forces the liquid out, ensuring a stable supply to the pumps, independent of the skid’s orientation. This approach eliminates any contact between the pressurizing gas and the process fluid.
2. Precision Dosing with Dedicated Syringe Pumps Injection is handled by four high-pressure syringe pumps, each with a defined role: one for ethanol, one for hydrogen peroxide, one for pure water (used for dilution and flushing), and a fourth dedicated to piloting the pressure regulator. These positive displacement pumps guarantee a perfectly continuous and programmable flow up to 330 bar, a critical factor for mastering the reaction’s stoichiometry. Each pump is pressure-monitored to cut motor power in case of overpressure, ensuring the system’s intrinsic safety.
3. Integrated Pressure Control and System Management Maintaining a stable pressure in the reactor is as critical as controlling the injection. A dome-loaded back-pressure regulator is installed at the reactor outlet. Rather than piloting it with a gas source, which could be limited in the target environment, we opted for hydraulic piloting. The fourth syringe pump applies a precise setpoint pressure to the regulator’s dome, providing fine, autonomous control. A 4-position rotary valve, controlled by the PLC, manages the line flushing sequences—an essential function for the reliability and safety of equipment handling reactive fluids.
Transferability and Future Projects
The expertise developed for this skid is directly applicable to other fields facing precision injection constraints in non-standard environments.
- Continuous Flow Chemistry: For lab pilots or fine chemical production units where stoichiometric precision and pulse-free flow are necessary to ensure reaction selectivity in microreactors or tubular reactors.
- Geosciences: For core flooding experiments in HPHT rigs, where the system can be adapted to inject brines, polymers, or supercritical CO₂ with fine control over flow and pressure.
- Onboard Systems (Marine, Subsea): For any onboard chemical dosing or treatment system where the equipment must remain operational and safe despite roll, pitch, and vibration.
Technical Specifications
- Maximum operating pressure: 330 bar (approx. 4785 psi)
- Number of injection lines: 3 (H₂O, H₂O₂, EtOH) + 1 pilot line
- Pump type: 4 syringe pumps, 3.5 mL volume
- Flow rate range per pump: 0.1 to 100 mL/min
- Feed reservoirs: 3 x 200 mL with internal bladder
- Reservoir pre-charge pressure: up to 10 bar (approx. 145 psi)
- Wetted materials: 316 Stainless Steel, PEEK, Viton
- Fittings and tubing: Low dead-volume type, 1/16″ OD
- Control: Programmable Logic Controller (PLC), EtherCAT and RS485 communication
Does your process demand stable multi-fluid injection, but your test environment rules out standard solutions? Do you need to guarantee reliable operation despite vibration, orientation changes, or a confined space?
Describe your constraint. Our engineering team will analyze the physics of your problem to define a fluidic and control architecture that precisely meets your specifications.
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