Heat recovery from a biomass heat source

The method of clam 1 comprising recycling the unflashed first hot biomass component comprising the steps of:

• (i) withdrawing the unflashed first hot biomass component from the flash cooler, where the unflashed first hot biomass component has a temperature that is less than the first temperature;
• (j) increasing the temperature of the unflashed first hot biomass component to the first temperature of the first hot biomass stream;
• and
• (k) pretreating the unflashed first hot biomass component heated to the first temperature to form a third hot biomass stream.

A method for controlled and incremental transfer of heat from a hot biomass to a cold biomass, comprising the steps of:

• (a) providing a heat recovery system comprising a plurality of flash coolers configured in series to permit the flow of an unflashed hot biomass component from a first flash cooler to one or more downstream flash coolers and a plurality of direct contact condensers configured in series to permit the flow of a flashed hot biomass from a first direct contact condenser to one or more downstream direct contact condensers, wherein each of the plurality of flash coolers is operably connected to a corresponding direct contact condenser;
• (b) generating an unflashed hot biomass component in the first flash cooler and subsequently sequentially passing the hot biomass through the plurality of flash coolers;
• (c) heating a cold biomass and sequentially passing the cold biomass through the plurality of direct contact condensers;
• (d) flashing a liquid portion of the hot biomass into a vapor within each of the plurality of flash coolers that the hot biomass passes through;
• (e) removing the vapor from each of the plurality of flash coolers;
• (f) transferring the vapor from each of the plurality of flash coolers to the corresponding direct contact condenser;
• (g) contacting the vapor with the cold biomass in each of the corresponding direct contact condensers the cold biomass sequentially passes through;
• and
• (h) condensing the vapor onto a surface of the cold biomass, thereby heating the cold biomass sequentially passing through each of the corresponding direct contact condensers.

A method for controlled and incremental transfer of heat from a hot biomass stream to a cold biomass stream, comprising the steps of:

• (a) providing a heat recovery system, comprising:
• a first flash cooler;
• a second flash cooler;
• and
• a direct contact condenser;
• (b) providing the hot biomass stream characterized by a first temperature and a first pressure, and having a liquid with a first saturation water vapor pressure at the first temperature
• (c) introducing the hot biomass stream into the first flash cooler, the first flash cooler having a second pressure, where the second pressure is less than the first saturation water vapor pressure and the second pressure is less than the first pressure;
• (d) flashing a portion of the liquid of the first hot biomass stream to form a first hot biomass vapor and an unflashed first hot biomass component, the first hot biomass vapor having a second temperature that is less than the first temperature;
• (e) removing the first hot biomass vapor from the first flash cooler;
• (f) transferring the unflashed first hot biomass component having the second temperature into the second flash cooler;
• (g) flashing a liquid portion of the unflashed first hot biomass component to form a second hot biomass vapor and an unflashed second hot biomass component, the second hot biomass vapor having a third temperature less than the second temperature;
• (h) transferring the first hot biomass vapor from the first flash cooler and the second hot biomass vapor from the second flash cooler into the direct contact condenser;
• (i) introducing a cold biomass stream into the direct contact condenser, the cold biomass having a fourth temperature, where the fourth temperature is less than the second temperature of the first hot biomass vapor and the third temperature of the second hot biomass vapor;
• and
• (j) contacting the first hot biomass vapor and the second hot biomass vapor with the cold biomass for a time sufficient to transfer heat from the first hot biomass vapor and heat from the second hot biomass vapor to the cold biomass, wherein absorption of the heats from the first and second hot biomass vapors by the cold biomass condenses the first and second hot biomass vapors onto the surface of the cold biomass, wherein the transfer of heat to the cold biomass increases the fourth temperature of the cold biomass to form a heated cold biomass having a fifth temperature, wherein the fifth temperature of the heated cold biomass is greater than the fourth temperature of the cold biomass.