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Making hydrogen more efficiently – with improved heat transfer
Feature Articles, Nov 26 2009 (The Hydrogen Journal)
- Ohio company Catacel is developing ways to improve heat transfer in hydrogen reforming by fixing catalyst to the walls of a heat exchanging foil structure – potentially increasing hydrogen production by 3-6 per cent for the same amount of natural gas
Ohio company Catacel has developed ways to fix catalyst to the walls of a heat exchanging foil structure, leading to increases of efficiency of heat exchange of 10 to 20 per cent.
Bill Whittenberger, president and founder, Catacel
This could be very useful in reforming (making hydrogen from natural gas).
Reforming reactions need a lot of heat – and for every unit of natural gas which is put through the reactor to make hydrogen and carbon dioxide, half a unit of natural gas is burned to make the necessary heat.
The reaction to convert natural gas into hydrogen and carbon dioxide usually uses a catalyst – a material added to the reactor which can help move the reaction along. It is usually nickel based.
Catacel had the idea of fixing the catalyst material directly to the walls of a heat exchanging foil structure, where hot gases generated from combustion of natural gas transfer their heat more efficiently to the catalyst surface inside the reactor.
Catacel's heat exchanging foil structure
By doing this, the amount of natural gas needed to make heat for a given volume of natural gas is reduced by 10-20 per cent, says company president and founder Bill Whittenberger.
This means that the overall amount of natural gas required to make a given volume of hydrogen can be reduced by 3-6 per cent.
The system could enable more hydrogen to be produced from the same size reactor – about 30 to 40 per cent more, Mr Whittenberger says. “If you need more capacity – you get a lot more capacity for very low cost.”
It can also enable some reaction systems to work which otherwise would not work because of limitations in how much heat transfer can be achieved.
The system can also make it easier to control reactions, Mr Whittenberger says – for example when it is necessary to keep a reaction temperature within a certain window so the catalyst works properly. “If you do that reaction on a heat exchange foil surface, you can get rid of that heat.”
The cost of the catalytic heat exchanging material is approximately 4 to 5 times the cost of a normal catalyst, he says.
The system is being used on one pilot project at the moment, a hydrogen reformer in Turkey, which has been running since July 2008. “It’s been running well ever since,” he says.
“We’re talking to other plant builders now about other potential plants.”
Fuel cells
The same technology could also be used in fuel cells – both when the fuel cell needs to be raised to a certain temperature to work, and also when there is tailgas generated at the anode. Rather than create a disposal problem, it can be combusted to create useful heat.
With tail gas, “the best thing to do is to burn it, and take that heat – and push that back into your system somewhere,” he says. With the Catacel system you can “burn that off gas catalytically on a heat transferring surface.”
“When you burn that tail gas it gets a little interesting – it hits the hot catalyst – it will burn at a very high temperature if you don’t know what you’re doing – the trick is to get the heat out gradually,” he says.
The system can also be used in combined reformer – fuel cell units, where natural gas is reformed to hydrogen in a first stage to be added to the fuel cell in the second stage, so the whole unit can be used to make electricity efficiently from natural gas.
Catalyst particles
There is nothing special about the catalyst material itself – it is nickel based catalyst, similar to what all natural gas reformers use – but instead of being in the form of ceramic pellets, it is attached to the metal walls of a heat exchanging foil structure.
The catalyst particles are placed on the structure’s metal foil fins.
The hard part of the technology development was working out how the catalyst should be “displayed”, or attached on the metal foil, Mr Whittenberger says.
“We displayed them on a honey comb structure – to give dramatic results.”
The technology of attaching catalyst to metal was first developed for use in catalytic converters to remove carbon monoxide from gas power plant emissions. Mr Whittenberger has been working on catalytic systems since 1986.
Other applications
There are many potential industrial applications for improved heat exchange involving catalysts, but Catacel is looking at the hydrogen industry in particular because there is a lot of new development going on.
“It's easy, it’s the low hanging fruit, the hydrogen market is growing, a lot of people are doing things,” he says.
The company is looking at a range of other industries, but mainly where reforming (producing useful products such as hydrogen or ethylene from fossil fuels) is involved.
The company is also looking at using the technology in gas to liquid processing, which also uses reactors that require heat transfer.
The company currently has 28 employees.
