An object of the present invention is to overcome the disadvantages of the prior art by directly contacting a non condensible gas as a feed gas with heated water, thereby humidifying the feed gas, while utilizing the heat possessed by the formaldehyde product gas as {TAIL ~ a heat source} for heating {HEAD ~ the water} 
An object of the present invention is to overcome the disadvantages of the prior art by directly contacting a non condensible gas as a feed gas with heated water , thereby humidifying the feed gas , while utilizing the heat possessed by the formaldehyde product gas as { TAIL ~ a heat source } for heating { HEAD ~ the water }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD