Oven with a mechanism for cascading heated gas successively through separate isolated chambers of the oven

An oven, comprising:

• (a) a plurality of adjacently disposed chambers which are substantially horizontally aligned and sealed from each other and the ambient atmosphere and through which a continuous element is passed for treatment by heated gas therein;
• (b) means for circulating to the chamber of the plurality of chambers last to be encountered by the element as it passes through the oven, gas heated to a predetermined temperature;
• (c) means for cascading the heated gas from the last chamber successively through the remaining chambers of the plurality of chambers in a direction from the last to the first of the plurality of chambers to be encountered by the element as it passes through the oven without reheating said gas;
• (d) means for exhausting heated gas from the chamber to which the heated gas is last cascaded to, the means (c) for cascading heated gas including:
• (I) means for cascading heated gas through the plurality of chambers at a mass flow rate which is correlated to an evaporation rate of a solvent that is carried by the element, and (II) means associated with the means (d) for exhausting heated gas, for continuously monitoring the mass flow of a mixture of heated gas and solvent vapor exhausted from said chamber to which heated gas is last cascaded to, and for adjusting the temperature of gas circulated to at least the last chamber when the mass flow being monitored varies from, a desired norm.

A composite oven, comprising:

• (a) a preheat oven comprising a plurality of adjacently disposed chambers which are substantially horizontally aligned and sealed from each other and the ambient atmosphere, each of the chambers including a pair of confronting rows of nozzles for directing streams of heated gas towards each other at angles of substantially 90.degree. to a plane which is between and parallel to the rows of nozzles;
• (b) a high velocity oven disposed in tandem with the preheat oven and comprising a plurality of adjacently disposed chambers which are substantially sealed from each other and the ambient atmosphere and horizontally aligned with the chambers of the preheat oven, each of the chambers of the high velocity oven including a pair of confronting rows of flotation nozzles for directing streams of gas towards each other at acute angles which are substantially less than 90.degree. to a plane that is between and parallel to the rows of nozzles;
• (c) means for moving a continuous element successively through the chambers of the preheat and high velocity ovens between the rows of nozzles in the chambers;
• (d) means for circulating heated gas to at least a last entry chamber of the high velocity oven to be encountered by the moving element;
• (e) means for cascading heated gas from the last entry chamber of the high velocity oven successively through the other chambers of at least the high velocity oven;
• (f) means associated with each chamber through which gas is cascaded, for monitoring the gas pressure within that chamber and causing cascading of gas from that chamber into the next preceeding upstream chamber;
• (g) means for exhausting heated gas from an exhaust chamber to which heated gas has been cascaded last to;
• (h) a first heat exchanger;
• (i) means for heating to a desired temperature gas exhausted from the exhaust chamber, prior to circulating to the heat exchanger at least a portion of the gas heated to the desired temperature;
• (j) means for circulating through the heat exchanger into heat exchanging relation with heated gas being circulated therethrough from the heating means (i), gas from a source of gas which is substantially cooler and less contaminated than exhaust gas from the exhaust chamber, to heat the cooler gas for circulation at least to the last entry chamber of the high velocity oven;
• (k) means associated with each of the chambers of at least the high velocity oven for removing heated gas from a chamber and recirculating it to the nozzles in that chamber to maintain a continuous flow of gas from the nozzles;
• and
• (l) means for measuring at least the temperature of heated gas cascading through the chambers, comparing the measurement to a predetermined desired norm, and adjusting the temperature of heated intake gas circulated to at least the last entry chamber of the high velocity oven in accordance with a variation of the measurement from the norm.

A method of heat treating a continuous element as it successively travels substantially horizontally through a plurality of adjacent, aligned chambers which are substantially sealed from each other and the ambient atmosphere, comprising:

• (a) heating gas, used in the heat treatment of the element, outside the chambers;
• (b) cascading such heated gas successively through the plurality of chambers in a direction from the last to the first of the plurality of chambers to be encountered by the traveling element without reheating such gas;
• (c) cascading such heated gas through the chambers at a mass flow rate which is correlated to a desired rate of evaporation of solvent carried by the element into the chambers;
• (d) monitoring the mass flow rate of gas exhausted from the chamber to which the heated gas is last cascaded to;
• and
• (e) adjusting the temperature of the heated gas cascading through the chambers, when the mass flow rate of exhausted gas varies from a predetermined mass flow rate.