We use a converted beer keg in between the kettle and the heat exchanger. The keg has an open top so there is open, easy access to the inside. On the side is a tri-clamp fitting and there's one at the bottom side of the keg as well.
We attach a tee on the inside and attach (2) nylon fine mesh bags to act as in-line filters to collect pellet residue and trub so it will not pass to the heat exchanger. Originaly, we used this process to put hop pellets in the bags to create an in-line hopback to create more hop aroma for our IPA. The bags work well, but have to be replaced every so often due to rips and tears.
After finishing the brew, we would backflush the heat exchanger with 180F hot water. At each keg washing, we would backflush hot caustic through it as well. The heat exhanger is portable and on a cart in our process.
As well as all this works, we still remove the heat exchanger plates on a periodic basis to clean any film and debris.