untility model patent certificate of spiral corrugated plate heat exchanger
letters patent of spray type slag water heat exchanger
letters patent of flat-cover sealed removable spiral plate heat exchanger
letters patent of fully welded wide-channel plate heat exchanger
letters patent of heater for hot mixing heat supply network
letters patent of heater for hot mixing heat supply network
letters patent of heater for hot mixing heat supply network
untility model patent certificate of heat exchanger plates with different corrugated shapes