Commercial heating
For over 60 years, North Sea gas gave the UK a stable fuel supply with a narrow quality band which enabled high efficiency and high levels of safety. As North Sea gas started to tail off, we began importing liquefied natural gas (LNG) to ensure security of supply, which raised issues regarding the quality of the specification. In particular, LNG needs to comply with our Gas Safety (Management)
ViewPoint O
It’s gas, gas, gas
ne of the main issues affecting the UK heating industry is that of gas – in all its forms. Ross Anderson of ICOM explains.
Regulation for it to be injected into the grid, potentially requiring addition of nitrogen or propane to give suitable calorific values and Wobbe Index. Suppliers are now looking for ways to reduce the cost of doing this. One such project by gas distribution company SGN, in the Scottish town of Oban, has shown that when gas appliances were installed, maintained and operated in accordance with manufacturers’ instructions, they operated safely at a higher level of Wobbe Index than currently allowed. The initial project focused mainly on domestic appliances and SGN has now begun to investigate commercial and industrial appliances. The use of a wider range on Wobbe Index natural gases would
certainly help in the security of supply in the UK as long as there are no negative repercussions. However, it will not help to meet the UK’s commitment to achieving an 80% reduction in greenhouse gases by 2050. For that, we also need to consider ‘green gases’.
Green gases
In relation to green gases, the Government is investing in a number of projects to investigate the use of hydrogen. There are two options: firstly 100% and, secondly, a hydrogen/natural gas blend. A publication by the Department of Business, Energy and Industrial
Strategy (BEIS), entitled “Hydrogen supply chain evidence base & modelling tool”, attempts to put costs against the various elements of the supply chain. Furthermore, BEIS has launched a £25m fund to look at developing the supply chain. Another project, known as “HyDeploy”, is designed to determine the optimum level of hydrogen that can be added to the natural gas grid to ensure currently installed appliances operate safely. Additionally, Loughborough University is exploring how to odourise
hydrogen without the currently-used sulphur based chemicals that would damage the catalysts in fuel cells. Also, Cadent is considering manufacturing hydrogen and supplying industrial users in the north west of England, using de-commissioned gas fields to store the resulting carbon dioxide. All these projects around hydrogen will give more information as to the safety of using hydrogen, the costs and the feasibility. Other considerations include increasing production of bio-methane, both for local use and injection into the grid, whilst synthetic natural gas and propane also have a place in achieving the 2050 goals. Probably the best scenario to achieve 2050 targets is the use of
hydrogen in the natural gas grid at a level determined by “HyDeploy”, local use of 100% hydrogen in mainly industrial installations with a high gas demand, and then the addition of the various green gases. Just how this scenario will unfold is still unclear, but there are several ways to ensure that we have a gas industry for the foreseeable future.
Energy Association ICOM ICOM 24 November 2017
Material metal matters
Manufacturers make their boiler heat exchangers out of stainless steel or aluminium across their ranges. Indeed, there is often discussion within the industry over which metal is better. One manufacturer, Potterton Commercial uses both which qualifies it to see both sides of the story. National sales manager Steven Evans explains
resistant properties and how these impact on the performance and longevity of a boiler’s heat exchanger. Many prefer to stick to one or the other, but does stainless really ‘steal’ the show, or is aluminium the alpha metal? The truth is that there is little evidence to suggest that one is more reliable or long lasting than the other. Both materials offer excellent performance, so heat exchanger material shouldn’t govern choice of boiler. Here’s why.
C Stainless steel
As the British Stainless Steel Association (BSSA) points out “Stainless is a generic name for a range of steel types and grades for corrosion or oxidation resistant applications.” As a family, they are iron alloys with a minimum chromium content of 10.5%, which is the key element in corrosion resistance. Other elements, including nickel, molybdenum, titanium and copper are also added to enhance their structure and properties. Choosing the correct grade of stainless steel for a demanding application such as a heat exchanger is critical. While chromium is the key
omparisons are often made between stainless steel and aluminium, their corrosion-
element in resisting the oxidisation process that causes corrosion, this is further enhanced by the addition of the metal molybdenum to create stainless grade 316/316L. The heat exchangers used in
Potterton Commercial’s Sirius boilers are the low-carbon stainless steel grade 316L, which is a high-alloyed steel with a chromium content of over 18%. When the chromium is oxidised, it forms a thin surface layer which
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