Method and apparatus for using excess heat from power plant flue gas to dry biomass fuel
AssigneeZhongying Changjiang International New Energy Investment Co., Ltd.
InventorsYilong Chen, Shuchuan Hu, Yanfeng Zhang
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Abstract
A method for drying biomass fuel using waste heat of flue gas from a power plant. The method includes: 1) stepwise recovering, by multi-stage condensation, sensible heat of flue gas; stepwise heating air using the sensible heat, to yield first-stage dry air and second-stage dry air; 2) convectively drying and dehydrating biomass fuel using the first-stage dry air having a temperature of between 150 and 180° C.; 3) further convectively drying and dehydrating the biomass fuel using the second-stage dry air having a temperature of between 80 and 100° C.; and 4) drying and dehydrating the biomass fuel using the third-stage dry air having a temperature of less than or equal to 25° C.
Claims14
A method for drying biomass fuel using waste heat of flue gas from a power plant, the method comprising:
- 1) stepwise recovering, by multi-stage condensation, sensible heat of flue gas;
- stepwise heating air using the sensible heat, to yield first-stage dry air and second-stage dry air, wherein a temperature of the first-stage dry air is higher than a temperature of the second-stage dry air;
- recovering latent heat of the flue gas as a heat source to exchange heat with air cooler tubes, to yield third-stage dry air, or collecting ambient cold air as the third-stage dry air, wherein a temperature of the third-stage dry air is lower than the temperature of the second-stage air;
- 2) convectively drying and dehydrating biomass fuel using the first-stage dry air having a temperature of between 150 and 180° C., a moisture content in the biomass fuel being reduced to between 30 and 50%;
- 3) further convectively drying and dehydrating the biomass fuel using the second-stage dry air having a temperature of between 80 and 100° C., the moisture content in the biomass fuel being reduced to between 25 and 30%;
- and
- 4) drying and dehydrating the biomass fuel using the third-stage dry air having a temperature of less than or equal to 25° C., the moisture content in the biomass fuel being reduced to less than 25%.
A device for drying biomass fuel using waste heat of flue gas from a power plant, the device comprising:
- a multi-layer dryer, the multi-layer dryer comprising a drying room comprising multi-layer transversely-disposed conveying belts, at least two transverse baffle plates, and discharge chutes connecting adjacent conveying belts;
- a first-stage flue gas condenser comprising a first water outlet and a first flue gas outlet;
- a first-stage gas-liquid heat exchanger comprising a first air outlet;
- a second-stage flue gas condenser comprising a second water outlet and a second flue gas outlet;
- a second-stage gas-liquid heat exchanger comprising a second air outlet;
- a latent heat recovery unit comprising a third air outlet;
- and
- air cooler tubes comprising a fourth air outlet;
- wherein
- the at least two transverse baffle plates are configured to separate the multi-layer conveying belts in the drying room to form a first drying zone, a second drying zone, and a third drying zone from the top down;
- the first drying zone, the second drying zone, and the third drying zone are independently air-tight;
- a temperature in the second drying zone is higher than a temperature in the third drying zone, and is lower than a temperature in the first drying zone;
- a first-stage dry air inlet is disposed on a front end of the first drying zone, and a first humid air outlet is disposed on a rear end of the first drying zone;
- a second-stage dry air inlet is disposed on a front end of the second drying zone, and a second humid air outlet is disposed on a rear end of the second drying zone;
- a third-stage dry air inlet is disposed on a front end of the third drying zone, and a third humid air outlet is disposed on a rear end of the third drying zone;
- the discharge chutes are disposed between two ends of the adjacent conveying belts, respectively, and the biomass fuel is transmitted from the top down through the discharge chutes in a serpentine mode;
- the multi-layer dryer is connected to the first-stage flue gas condenser;
- the first water outlet of the first-stage flue gas condenser is connected to the first-stage gas-liquid heat exchanger;
- the first air outlet of the first-stage gas-liquid heat exchanger is connected to the first-stage dry air inlet;
- the first flue gas outlet of the first-stage flue gas condenser is connected to the second-stage flue gas condenser;
- the second water outlet of the second-stage flue gas condenser is connected to the second-stage gas-liquid heat exchanger;
- the second air outlet of the second-stage gas-liquid heat exchanger is connected to the second-stage dry air inlet;
- the second flue gas outlet of the second-stage flue gas condenser is connected to the latent heat recovery unit;
- and
- the third air outlet of the latent heat recovery unit is connected to the air cooler tubes;
- and the fourth air outlet of the air cooler tubes is connected to the third-stage dry air inlet.
Dependencies are inferred from the claim text.