Locomotive boilers have copper tubes going through them and they're quite a bit larger
i always assumed that was a part of some neglected miniature railroad, like you'd see at a theme park
definitely looks too small to be part of a full sized locomotive based on the door right next to it, but after some cursory googling i found these:
if you stripped away everything but the large horizontal copper cylinders, you'd have something that somewhat resembles that rusted down thing, so i dont think its too far fetched to call it a boiler
