BOILERS, PUMPS AND VALVES
THE COMBUSTION OF TOMORROW
he 23rd of June marks International Women in Engineering Day. Here, we celebrate the work of two women engineers in driving combustion technology to accommodate new fuel types and reduce environmental impact.
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Virtually all forms of manufacturing require a heat process, provided by a burner and a boiler. However, industrial burners generate two types of unwanted by-products: CO2 and pollutants in the form of methane, sulphur and nitrogen oxides. Reducing both, without negatively impacting the burner’s ability to function efficiently, has been a focus of recent work at Babcock Wanson, along with substituting fossil fuels with alternative energies. At the core of the development of these technologies are two senior engineers: Delphine Morel-Chevillet, Burners Product Line Manager and Cecilia Sebastiani, Product Technology & Innovation Manager.
NOx REDUCTION: CATCH-22? Limiting NOx in burners is straightforward: you increase the amount of air. However, this decreases efficiency. To improve efficiency, you preheat the combustion air, but this increases the flame temperature and the production of NOx. It seems to be something of a catch-22 situation. “A number of people have said that it does not make sense, that you cannot both limit NOx emissions and optimise the efficiency of the boiler” comments Cecilia. “Since efficiency and nitrogen oxide containment are really antagonists, it is just that you must find an optimum point which delivers the best solution for both. Also, efficient combustion is not only energy-saving and money- saving, it is also CO2 saving and, of course, we have to reduce the carbon footprint. This is the greatest challenge we have faced.” At Babcock Wanson, a new approach has been
taken that is based on a flue gas recirculation system (FGR), developed by Delphine and her team. “Gas recirculation, where we inject through gas and the burner, is very well known, but what we are doing that is unique is that we inject it back into the boiler” states Delphine. “Because we are the only company that designs and manufactures burners and boilers, we are the only company that can do this; we have a unique advantage!” Two innovative solutions have emerged from
this work to date. The R-Eco solution is a combustion air
preheater that recovers heat from the combustion fumes and uses an FGR system. This
technology increases the overall efficiency of the boiler up to 98%, and significantly reduces the formation of NOx emissions in the flue gas. It is the ideal solution when condensate returns are high and do not allow the use of conventional economisers to recover heat from the flue gas. R-Eco is compatible with installations that run on natural gas, with a flue gas inlet temperature above 130°C, and an outlet temperature ≈ 100°C. The second solution is the Good Loop
concept. Good Loop extracts the flue gases at the boiler outlet before reinjecting the recycled gases directly into the furnace, upstream of the refractory block, thanks to an additional dedicated fan. This directly reduces NOx emissions from Babcock Wanson natural gas boilers by 20-30 mg/Nm3, which is firmly at the forefront of innovation in this area. Babcock Wanson’s Optimo 2 burner, for example, designed for medium size firetube Steam Boilers ranging from 2 to 4t/h, has emission rates in standard form that are less than 100mg/Nm3 NOx throughout the firing range when burning natural gas. The Good Loop unique technology is not only being used in new Babcock Wanson systems, but can also be applied to an existing burner and improve its performance without any design changes.
ALTERNATIVE FUELS: THE OPTIONS
One of the major stumbling blocks in replacing fossil fuels with more sustainable alternatives is the infrastructure to deliver them. In the case of biomethane, the existing distribution networks and equipment can be utilised. Standard biogas, on the other hand, requires adaptations and quality control (moisture content, existence of hydrogen sulphide). When it comes to hydrogen, however, its technical characteristics (density, PCI, etc.) are quite different from those of natural gas, so its distribution and combustion require substantial infrastructure and equipment adaptations. Looking at the emissions for these different
fuel types, biogas and biomethane fuelled combustion produces the same emissions as that of natural gas. The combustion of hydrogen no longer produces CO2 but simply water vapour, so scores big points when it comes to emissions. Where the reverse is currently true, is when it comes to production methods. Biogas and
8 JUNE 2022 | FACTORY&HANDLINGSOLUTIONS DELPHINE MOREL-CHEVILLET
Burners Product Line Manager
CECILIA SEBASTIANI
Product Technology & Innovations Manager
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