When a leading academic at one of the world’s best universities needed a valve that would enable very tightly controlled flow of gas for his research, he couldn’t find one – so he created it himself, writes Chris Leonard
Tom Povey, Oxford Flow Technical Director
Credit: Oxford Flow
In the power industry, downtime can be the difference between profit and loss. High reliability and availability of equipment are key ingredients to success.
A core component of many power generation applications including natural gas, hydropower and nuclear, the humble pressure regulator or control valve has provided sterling service for many years. However, the reliability of these pressure regulators is not necessarily inherent and is achieved, in many instances, by frequent maintenance to replace worn elastomer diaphragms.
Maintenance means downtime, and with increasing demands on plant productivity and availability this sometimes unavoidable activity has set the limits of performance.
Given just how crucial proper flow regulation is in not just the power generation industry, but for virtually every industry that involves manipulating and distributing matter, the lack of innovation in this sector has been startling.
Oxford Flow Regulator
Credit: Oxford Flow
While the 20th century and, indeed, the beginning of this one have seen innovations our forebears could only have dreamed of, pressure regulation has witnessed very little innovation since the Victorian age, when, in 1886, the venerable Bryan Donkin submitted his patent declaring “Be it known that I, Edwin Bryan Donkin, a subject of the Queen of Great Britain, residing at Bermondsey, in the county of Surrey, England, mechanical engineer, have invented certain new and useful Improvements in Valves for Regulating the Flow of Gas in Mains and other Passages”.
A great leap forward for flow regulation. Unfortunately, since then little has fundamentally changed and pressure and flow regulators still need their Achilles heel in order to function – an elastomer diaphragm.
A typical flow regulator uses a diaphragm that constantly modulates in order to manage pressure, enabled by a limited range of elastomers, which flex as required in order to provide accurate control. The flexibility required is enabled by the elastomers, but unfortunately it is this very flexibility that leads to the potential for erosion, embrittlement, bursts and other risks to reliability.
This is caused by something rather mundane, and something that anyone familiar with any elasticated or rubber product will be too familiar. Stretch the elastomers too far, or just use them for too long, and this will lead to fatigue, erosion and eventually breakage.
The very quality that makes engineers seize on elastomers to enable all sorts of things is also, unfortunately, the fatal flaw that leads to their eventual downfall. And in the valves that are used in the power generation field, the very thing that makes elastomers such a useful tool is also the thing that makes them so very capricious. They cannot cope with steam or gas at very high pressures, or at least not for a period of time that makes their use viable. This has meant that until now, the power industry has needed to fall back on actuated valves. However, while these are able to withstand many of the pressures of the industry, this comes, quite literally, at a price. Powered as they are by electricity, these actuators require generators and backup generators in order to function.
Oil and gas isn’t the only industry to find itself thwarted by the limitations of the valves currently on the market. It was the limitations of the conventional pressure regulation valve that Oxford University’s Professor Thomas Povey found his own endeavours limited by as he carried out research into jet engine performance for a household name industrial partner at the world-famous Osney Thermo-Fluids laboratory.
Here, when trying to undertake very precise measurement of heat transfer in turbine blades in order to enable the development of more efficient jet engines and gas turbines, he needed a valve that would enable a very tightly controlled flow of gas if he and his team were to be able to effectively capture the data they needed.
Unfortunately for Professor Povey, no such valve was forthcoming. Even the current market-leading regulators were not accurate or efficient enough to meet the standards required as part of these experiments.
As you might expect from a leading academic at one of the world’s best universities, Professor Povey was undeterred. If he required a higher performance valve, he would just have to create one himself. And that is precisely what he did.
Fitting an Oxford Flow Regulator
Credit: Oxford Flow
Swapping elastomers for pistons
In the Oxford Flow model, the diaphragm is replaced by a direct sensing piston actuator, which greatly simplifies the design of the regulator as well as eliminating the main reason for failure in these devices.
One side of the piston is exposed to downstream pipeline pressure while the other side is balanced against a pressure cavity controlled by a pilot regulator. This piston actuator operates over an optimized feed-hole configuration to provide precise, stable control across the entire operating range. During operation, the piston moves inward, reducing the size of the cavity when the downstream pipeline pressure exceeds that within the pressure cavity set by the pilot regulator.
The movement of the piston actuator in closing reduces the flow rate to maintain a stable downstream pressure. When demand increases, the downstream pressure falls below that set by the pilot and the reverse operation occurs: the cavity contracts as the pilot feeds it, opening the flow path, which increases flow and maintains a stable downstream pressure.
Meticulous testing revealed that, as well as being a much more efficient, durable way of regulating pressure, these designs also bring with them a host of other benefits, including reduced hunting, lower noise emissions, minimized flow turbulence and reduced minimum pressure head-drop. What Professor Povey had invented was something which, in short, maximized the positive aspects of flow regulation technology while significantly mitigating the downsides.
The possibilities if this device were to be commercialized were readily apparent, and it attracted the attention of Oxford Sciences Innovation (OSI), the new $420 million company created to support ambitious Oxford technology companies. Backed by innovation stalwarts such as Google and the Wellcome Trust, the fund aims to ensure that the breakthroughs made in the laboratories of the university filter out into industry.
With the support of OSI, what is now Oxford Flow, which is still based at the Osney Mead Thermo-Fluids laboratory, has developed a range of pressure regulation valves aimed at the energy and water industries: the IHF Series Oxford Regulator for Gas, IP Series Oxford PRV for Water, IM Series High Pressure Wafer Type Regulator for Gas or Liquid, and the IHP Series Wafer Type High-Pressure Regulator.
The Oxford Flow model is an elegantly simple solution which enables companies working in a wide range of market sectors to hit the holy trinity of production: doing more, for less, sustainably.
For example, the Oxford Pressure Regulator’s light weight (typically, an Oxford Pressure Regulator will weigh less than a quarter of the weight of traditional regulators) reduces installation costs by removing the need for lifting equipment for either installation or maintenance. Indeed, many models can be held in the palm of the hand.
The devices can also be retrofitted into existing infrastructure, easily fitting into the current strainers and filters used in the industry. For example, the IM Series wafer-type and IHF Series can both be installed between PN or ANSI flanges to minimize installation footprint. Similarly, both designs have just one moving part, which simultaneously maximizes reliability while, again, significantly lowering both installation and maintenance costs. And while not the primary aim, an attendant benefit of the more ‘hands off’ approach enabled by the new style valve also includes a significantly lowered carbon footprint.
This new technology has the potential to be truly transformative. It is self-powered, self-regulating, self-controlling and simpler in its construction than any other valve on the market. It can greatly reduce costs and its simple design, with just one moving part, means that the risk of failure in service and the requirement for frequent replacement and maintenance are removed.
Indeed, it offers tangible improvements in running costs and reliability while making no sacrifices in terms of performance. In an age when operators are under constant pressure to do more for less, innovations like this can be genuinely game-changing.
Chris Leonard is Business Development Director at Oxford Flow. www.oxford-flow.com