Abstract: A device for converting solar energy into process heat has a number of heat xchanging pipes traversing a heat exchanger chamber. A first partial stream of gas to be heated is delivered to inlets of the pipes via an upper distribution chamber, and the first partial stream of gas is subsequently collected from outlets of the pipes in a lower distribution chamber. An inlet aperture of the heat exchanger chamber receives sunlight radiation and a second partial stream of gas to be heated, the second partial stream of gas flowing around the heat exchanger pipes. The heat exchanging pipes absorb the solar radiation and heat both the first partial stream flowing through the pipes and the second partial stream flowing around the pipes. The heated second partial stream is collected by a heated gas outlet conduit connected to the heat exchanger chamber.

Abstract: A hot blast stove installation for heating cold blast to form hot blast includes a plurality of hot blast stoves each alternately operable during a heating phase and a blowing phase, a cold blast main for supplying cold blast to respective of the stoves during the blowing phases thereof, and combustion air and fuel gas mains for supplying combustion air and fuel gas to respective of the stoves during the heating phases thereof. The cold blast in the cold blast main has a relatively high temperature compared to ambient temperature, for example a temperature of from 100.degree. C. to 300.degree. C. A heat exchanger is connected to the cold blast main to remove heat from the cold blast therein prior to the supply of the cold blast to the stoves, thereby reducing the men and/or maximum waste gas temperature in the stoves during the heating phase of operation thereof.