The latest in our series of articles exploring IFRF’s archives…

As part of our commemmoration of IFRF at 70, and following on from contributions to our ‘Reigniting the…’ series in January, February, March and April from Neil Fricker, Giovanni Coraggio, Jarek Hercog and Peter Roberts respectively, we have now travelled backwards in time in discreet steps from the 2010s to the mid-1990s, and geographically from Livorno in Italy to IJmuiden in the Netherlands.

This month, our ‘guide’ is IFRF stalwart, Professor Roman Weber.  Roman joined the IFRF Research Team in IJmuiden in 1985, working there in different capacities as an Investigator, Senior Scientist and Scientific Manager.  In 1995, he was appointed to the Research Station’s Directorate as Technical Manager, leaving in 2001 to become a professor at the Institute for Energy Process Engineering and Fuel Technology at TU Clausthal in Germany.  The time period that Roman will ‘reignite’ for us (the 1990s) partly overlaps with the period that Peter re-lived with us last month, i.e. the mid-1990s to the mid-2000s, but Roman’s focus is different – some parallel research threads around the world that wove together through a chance encounter, and led to what Roman describes as a “brilliant cooperation”…!

Reigniting the… 1990s and a brilliant cooperation with Japan – a perspective from Roman Weber, former IFRF Scientific/Technical Manager

Hello MNM readers!

The 1973 ‘oil crisis’ highlighted to all the need for more efficient combustion.  In a scenario of rapidly increasing fuel prices, opportunities arose to make money from the application of heat recovery systems.  However, it wasn’t until 1982 that R&D at British Gas (BG) and Hotwork International resulted in the ‘regeneration principle’ being applied to a pair of burners close-linked to a pair of compact regenerator beds.  These burners served as both waste-gas flues and burners.

The first (1982) BG/Hotwork prototype system (firing natural gas) was built using a packed-bed of ceramic balls heated-up and cooled-down in cycles of about 30 seconds.  From the very beginning of the development, the high fuel-saving potential of such a burner system was realised, offering 60-70% fuel savings.  The regenerators produced combustion air preheated to around 1200^oC, with an exit furnace temperature of around 1400oC.  This 1982 prototype regenerative burner system was sent to Nippon Furnace Kogyo Ltd (NFK) with a request to examine its applicability to the Japanese steelmaking industry.  NFK immediately recognised the fuel-saving potential of the BG/Hotwork regenerative burner system, although their enthusiasm was tempered on observing NO_x emission levels in excess of 1000ppm – unless this could be addressed, there was no possibility of industrial applications in Japan…

Meanwhile, I joined the IFRF research team at IJmuiden in April 1985, on secondment from the University of Sheffield.  Among the numerous research activities underway at IFRF at that time, one of the key topics was the development of NO_x reduction methods for a large variety of fuels.  In 1991, I designed a series of natural gas burners for the so-called ‘Scaling 400’ study (looking at scaling of natural gas flames spanning the thermal input range 30kW to 12MW).  For the 12MW_th version of the burner, very low NO_x emissions of 18ppm at 3% O₂ were achieved when 100% of the natural gas was provided through the individual gas injectors.  In this case, the fuel gas was injected into hot combustion products containing typically not more than 4% oxygen.  Furthermore, at these conditions the NO_x emissions remained very low even if the combustion air temperature was increased to 200oC.  The research team (Jacque Dugué, Alan Sayre, Henk Horsman and me) which carried out the 12MW_thexperiments at Tulsa (John Zink Co., USA) was very proud, indeed – we realised that a new method of NO_x reduction had been discovered!

One day in about 1993, Ryoichi Tanaka, President of Nippon Furnace Kogyo Kaisha Ltd, visited IJmuiden to talk about our research (note – Mr Tanaka had been instrumental in establishing the Japanese Flame Research Committee in 1978).  He was received by the then IFRF Director Peter Roberts and me, and the conversation went something like this:

Mr Tanaka: “Do you work on heat recuperation and regeneration?”
Me: “No, our current topic is  NO_x reduction,” and I proudly showed him the burner design and a chart of the NO_x reduction we had achieved. “What do you think?”
Mr Tanaka (having looked at the burner design and the NOx figures for a while): “Primitive technology.”
Me (barely retaining my composure): “What do you mean by primitive technology? Look at the extremely low NO_x figures!”
Mr Tanaka: “You do not have heat regenerators in your burner design and therefore excessive fuel costs will limit its applications.  Your NO_x reduction method must be combined with heat regeneration – at NFK we do a lot of work on that subject.”

And so it was that a very successful co-operation began…

A  few months later and I was working with Toshiaki Hasegawa and Susumu Mochida, two excellent NFK research engineers, on the new combustion technology which, at that time, was given the name ‘Excess Enthalpy Combustion’ (following Felix Weinberg of Imperial College, London) and was meant to achieve high fuel efficiency (through heat regeneration) and low NO_x emissions.  As a matter of fact, under the leadership of Mr Tanaka, a large R&D programme on ‘High Performance Industrial Furnaces” was executed (1993-1999) to develop and promote this novel combustion technology in Japan.  Later on, the technology was renamed ‘High Temperature Air Combustion’ (HiTAC).  The R&D programme was undertaken under the auspices of the Japan Industrial Furnace Manufacturers Association (JIFMA), with sponsorship from the New Energy and Industrial Technology Development Organisation (NEDO).  Ashwani Gupta of the University of Maryland (USA) became the scientific director of the programme.

I think it is fair to state that the basis of HiTAC was developed jointly by NFK (Ryoichi Tanaka, Toshiaki Hasegawa, Susumu Mochida), the University of Maryland (Ashwani Gupta) and the IFRF Research Station.  In this context, IFRF carried out three semi-industrial trials concerning natural gas combustion (research team: AL Verlaan, S Orsino, NA Lallemant and R Weber), light and heavy fuel oil combustion (AL Verlaan, G Deus Vázguez, M Kösters, NA Lallemant, S Orsino and R Weber), and coal combustion (S Orsino, M Tamura, P Stabat, S Costantini, O Prado and R Weber) under HiTAC conditions, pushing the air preheat to 1200oC.   The principal HiTAC features determined in this cooperation could be summarised as follows:

• (a) a recuperator, or (preferably) a regenerator is used to recover the exhaust gas enthalpy to minimise the fuel consumption per unit of (process) product;
• (b) the fuel is injected into hot combustion products of low-oxygen concentration, typically 2-5 vol%;
• (c) fuel jets entrain large quantities of combustion products before their mixing with air jets takes place so that a substantial dilution of the fuel jet occurs prior to ignition;
• (d) combustion takes place all over the furnace and often no flame is visible.  The in-furnace temperatures are uniform, with only small gradients appearing in the burner vicinity.  The same is applicable to the in-furnace oxygen field;
• (e) the radiative fluxes are uniform – there are no substantial differences in the fluxes in the near burner region and downstream of the furnace;
• (f) for gaseous- and liquid-fuels containing no N-species, the technology provides NO_x emissions typically lower than 30-40ppm (3%O2), even when the combustion air temperature is in excess of 1000°C;
• (g) application of the technology to heavy fuel oil firing is limited due to excessive particulates emissions which typically exceed (by far) 50mg/Nm³; and
• (h) for the  high-volatile coal (1.49%N) tested, low combustion rates are observed under locally sub-stoichiometric conditions.  The lowest NO_x emissions are in the range 160-175ppm (at 3%O₂), indicating the very high NO_x reduction potential of the technology also for nitrogen- containing fuels.

For those that want to know more, please see the following reports/papers in the IFRF archive:

• New progress of energy saving technology towards the 21st century.  Frontier of combustion and heat transfer technology: Advanced combustion technology for industry (Tanaka) – Proceedings of 11^th Members Conference, IFRF, May 1995
• Fluid flow and mixing in a furnace equipped with the low-NO_x regenerative burner of Nippon Furnace Kogyo – the results of the NEDO-1 trials (Verlaan, Orsino, Lallemant, Weber) – IFRF Doc. No. F 46/y/1, 1998

Now, more than twenty years after the NEDO project initiation, it is easy to see its impact.  The HiTAC technology has been deployed widely, firstly in the Japanese steelmaking industry and then in China, Taiwan and Korea.  A number of burner and furnace manufacturers have been established in China to serve the huge domestic steelmaking market, where applications with thermal inputs as large as 8MW per a pair of burners are common.  The impact in the European steelmaking industry was not as large as in Asia, although numerous applications in Nordic countries took place due to both the Royal Institute of Technology, Stockholm (Wlodzimierz Blasiak) and Jernkontoret.  Combustion scientists gradually became involved, providing both the required scientific insight and new mathematical models.  In the theoretical work of the University of Napoli (Antonio Cavaliere and Maria De Joannon) the technology was renamed ‘MILD combustion’ (Moderate and Intensive Low-oxygen Dilution); often it is simply called ‘mild combustion’.  During the cooperation with Japan, IFRF had formulated a technology transfer project involving CORUS and Gas Unie to apply this novel technology at the CORUS steelworks at IJmuiden [Editor:  this project was also referred to by Peter Roberts in his ‘Reigniting the… mid-1990s to mid-2000s’ article last month].  This large investment was approved in 2001 (I left the IFRF a few month later) and was, in the end, carried out almost exclusively by CORUS personnel.  Subsequently, this project was recognised as one of the key NOVEM (Dutch organisation for financing R&D) exemplars for energy savings.  Almost a decade later, a national research project aiming at establishing the fundamentals of mild combustion has been initiated in the Netherlands.

Furthermore, there has been a proliferation of scientific papers which not only refine the specified requirements (points (a)-(h) above), but also extend the HiTAC concept to gasification, internal combustion engines and gas turbines.

During the NEDO project, and in parallel to the technical work I was doing with NFK and UM, I interacted with Mitsunobu Morita, who was in charge of administration and financing.  Each of the three (rather expensive) trials at IJmuiden was executed on the basis of a ‘hand-shake’; after agreeing both the scope and price, each trial was preceded with a substantial prepayment transferred to IJmuiden.  Appropriate formal agreements and the transfer of remaining sums were finalised long after the experiments had been completed; such was the trust between the parties involved.  Indeed, current project/programme administrative and financial practices make me a bit nostalgic about the times when a hand-shake between partners meant so much!

I will close with a retrospective remark that I think is necessary.  While designing the ‘Scaling 400’ burner in 1991 (see above), I was unaware of the brilliant Tokyo Gas patent (I Nakamachi et al, 1990) proposing fuel gas injection into hot combustion products.  A number of years later, this patent was explained to me by Tokyo Gas engineer and former IFRF investigator Tsuneaki Nakamura.  However, it seems very likely that NFK research engineers and Mr Tanaka knew about the patent.  To what extent the Tokyo Gas patent affected the NFK designs is hard for me to judge.  As a matter of fact, the North American Manufacturing Company (John Newby) licensed the Tokyo Gas patent and applied it to BG/Hotwork regenerators:  In this way HiTAC reached the USA – although under the name ‘Direct Fuel Injection’.

Due to the NEDO project, I was a part of the research team that formulated the basis of HiTAC technology.  Needless to say, none of us made money on the development, however the feeling of having produced a novel technology that results in huge fuel savings combined with drastic CO₂ and NO_x emission reductions is very rewarding.  Due to this project the world became a better place!

My dear Japanese friends – I salute you for this.

Roman