General Data Furnace Applications
A data furnace is made from computers. What those computers can do is no different to those computers being located in a data center. They are therefore useful for pretty much anything a data center computer is used for. In real world practical applications there will be limitations for some specific applications based on the chosen hardware platform, network connection speed, latency, etc, in the same way a data center operator chooses their hardware and infrastructure to optimize towards their customers needs. This is a design based decision, down to the creator of a data furnace.
Specific Use Cases
Mining Proof Of Work (POW) crypto coins can be argued as a really well suited application for a data furnace, after all the CPU’s or more often GPU’s work very intensively, use a lot of power and therefore generate a lot of heat. However the whole concept of a Proof Of Work crypto coin flies completely against the point of a data furnace. Mining of the coins uses huge amounts of electricity for no actual useful purpose, the calculations performed only serve to generate income for successful miners. When the computers are fossil fuel powered thats awful, but even when they are renewable electricity powered they are typically taking renewable energy away from another less profitable users who could be using it for actually useful purposes instead. A data furnace is a green technology, its purpose is to capture waste heat and re-use it where it is wanted to help the environment, its hard to see how partnering it with such an environmentally damaging industry serving no useful purpose other than running pointless computations just to use the maximum amount of electricity possible to the point that a tiny profit can be made over what it costs can be considered an environmental benefit!
That said, Proof Of Work crypto coins such as Bitcoin, will be replaced by Proof Of Stake (POS) coins, such as Cardano ADA, in the not too distant future at which point the massively wasteful use of electricity for crypto coin mining will be largely eradicated. At that point the use of crypto coins may well have data furnace applications, as the block chain networks they are based on use smart contracts and decentralized applications to carry out all sorts of useful compute intensive tasks.