The development of a gas delivery system for the transportation of high purity gasses (H2, CO2 & N2) from an auxiliary gas storage location to the main gas power station.
Orbital Fabrications Ltd was approached by a major supplier of gas control systems and equipment to design, develop and produce a gas delivery system on its behalf for a £1bn gas power station project. The gas delivery system had to have the capability of handling high purity H2, CO2 and N2 gases from gas cylinder packs and deliver these gases at very high pressures in a safe and efficient manner from an auxiliary gas storage area to the main power station. Each gas cylinder packs consisted of 15 bottles and was filled with gas to a working pressure of 300 bar.
Scientific and technological advance
Orbital Fabrications Solutions sought to extend the overall knowledge and capability in the field of mechanical engineering and welding fabrication technologies as applied to the design of a high pressure gas delivery system through the adaptation of existing technology into a new application where this adaptation was not readily deducible by its competent professionals (DTI guidelines paragraph 6 & 7). They specifically sought to gain:
- the requisite knowledge and technological capability to develop a robust gas delivery system, capable of handling and delivering high purity gases (H2, CO2 and N2) to deliver at high pressure (300 bar) and flow rates of up to 120 cubic meters per hour from gas cylinder packs in an auxiliary storage area to the main power station
- the requisite knowledge and understanding necessary to develop the appropriate manufacturing processes and welding technologies capable of handling high pressures (300 bar) and meeting the system requirements
- the requisite knowledge and understanding of the new gas power station architecture necessary to design an effective gas delivery system and associated pipework
Orbital Fabrications Ltd undertook an extensive design and development programme to address the technical issues. A project team was formed to analyse the customer requirement and the specification was defined and agreed with the customer. An initial scoping exercise of the technical requirements needed for the gas delivery system was undertaken. Orbital then embarked on an iterative design process which involved the use of 2D and 3D CAD software tools. Alternative design concepts of the gas delivery system and layouts of the pipework were systematically produced and reviewed with the customer. Engineering calculations and volumetric modelling using numerical methods were used by Orbital in order to finalise the design as well as assist in component selection process.
Welding trials were conducted as part of the process development exercise to ensure that the system was capable of handling high gas pressures (300 bar) and that the welding would meet the integrity levels required to satisfy the requirements of the system.
As part of the design process, Orbital utilised Computational Fluid Dynamics modelling to calculate the fluid flows of the gas delivery system and to analyse various factors including:
- the behaviour of the valves and pipe network used in the delivery system, identifying areas of flow restrictions or inhibitors;
- to verify the best possible design by understanding the impact of any possible turbulent flow on the system;
- the design of back-up and safety systems to address issues arising in the unlikely event of a loss in pressure within the system; and
- the effect of peaks and troughs in demand of gas supply from the downstream processes of the new power station.
Hydrogen Distribution Panel Example
The team at Orbital redesigned the gas delivery system based on erroneous product information, supplied by one of its valve suppliers, used previously in its design. Orbital carried out a substantial remedial exercise whereby it had to rework and replace some of the pipework in the gas delivery system.
The testing requirement Orbital had to meet for the gas delivery system was 1.5 times the specified working pressure of 300 bar. In order to perform this Orbital needed to develop a unique test rig to enable it to test the new gas delivery system to these very high-pressure levels. Functional and leak tests were also carried out at its St. Ives facility to ensure the weld integrity of the new gas delivery system were being met prior to shipping. Orbital resolved all the technical challenges and successfully delivered the new gas delivery system to the client ready to be installed into the new Power Station.
The auxiliary gas storage area