Large electrical generators have used hydrogen as a cooling medium for almost 100 years. Preferred over air because of higher thermal performance, it offers challenges to machine manufacturers, especially when used under pressure.
To remove gas-borne rejected heat manufacturers utilise near conventional finned tubes, much the same as they would air cooled machines. However, the challenges arise when gas tight faces need to be maintained through the thermal cycle and resonance eliminated over the length of the cooler.
The market for hydrogen cooled machines has diminished. Now, it’s generally only reserved for the very largest generators such as those found in the nuclear industry. Consequently, there are very few cooler manufacturers who can claim to have the experience and knowledge to design and build equipment of this type.
How hydrogen coolers work
To cool the generator, hydrogen is circulated through the active parts of the generator. It’s then directed into hydrogen coolers where the gas is cooled by transferring the rejected heat to the water.
The heat transfer takes place on a near standard fin and tube arrangement.
Whilst the heat transfer process is relatively conventional, the mechanical aspects are unique. With extended operational hours often running for months without stopping the mechanical integrity is paramount. Tolerances are tight to ensure that hydrogen cannot escape. Flex is very limited to avoid fatigue and failure.
What to expect from us?
Hydrogen coolers often have a robust frame surrounding the heat transfer components.
Generally built in a jig, it is imperative that both tube plates are set to tight tolerance dimensions with the required levels of flatness, squareness and parallel faces. The frame that supports the two tubeplates not only maintains this but is also required to avoid resonance. Typically, the coolers are supported only on the two tubesheets, often leaving more than 6 metres unsupported. It is absolutely essential that the frame avoids the natural frequencies of the machine.
A combination of air and hydrogen can be explosive. This is why we design and manufacture hydrogen coolers that ensure a perfect airtight installation with the flanges of the generator.
In addition, because of potential vibration induced failure, extra care needs to be taken when it comes to the support of tubes. Our unique design makes sure that each tube is individually supported. Combined with robust Elfin multi-tube plate-fin cores, fatigue is minimised for long and trouble-free service life.
Customised tubes, fins and material
We offer horizontal and vertical hydrogen coolers with a wide variety of geometries and material to your needs.
- Tubes: copper, CuNi90/10 or stainless steel.
- Tube sheets: carbon steel, naval brass or stainless steel
- Fin type: our Elfin plate-fin extended surface tubes, ribbon wound or wire wound
- Fins material: aluminium, copper alloys, stainless steel, or titanium.
Refurbishment of hydrogen coolers
Should you need to refurbish an existing cooler, we can help. Our services include but are not limited to repair and/or replacement of headers or tube sheets, retubing and tube bundle replacement. When possible, we save you money and reduce delivery time by reusing existing components.