I used blockchain in a project successfully, but it is not a distributed consensus application. My problem was file sharing. Torrent files send a big list of SHA1 hashes, one for each piece of the file. I replaced that idea with a single block which contains the hash of the next block (as well as two other blocks so verification isn't linear one block to the next). This allows a single block to represent the entire file, allowing you to get blocks from many peers while verifying them. You can just send out a coverage map of what you have, and your peers can calculate what you can verify and send you a random block from that set.

If anyone is interested, [1] and [2] are the project. No one is using it, but it's a peer to peer chat and file sharing system.

1. https://party-line.lol 2. https://github.com/tacixat/party-line