Method and system for compounding fertilizer from manure without nutrient emission
To produce fertilizer, a system and method concentrates manure slurry in a mechanical vapor recompression evaporator (“MVR”) having a heat exchanger. The MVR receives the manure slurry within a first side to evaporate ammonia laden-water vapor from the slurry, leaving a nutrient concentrate. A compressor raises the evaporated ammonia-laden water vapor to a higher energy state. Within a second side of the heat exchanger, the compressed water vapor conveys heat to the slurry. Ammonia-laden water condenses in the second side at a process temperature to be conveyed to an ammonia stripping tower where the ammonia-laden water is dispersed into ammonia-laden water droplets. In the tower, a flow of air is directed across a surface of the ammonia-laden water droplets, the process temperature having been selected to promote the escape of ammonia gas from the ammonia-laden water droplets, the flow of air provided to entrain ammonia gas in the flow.
1. A system to produce fertilizer from manure, the system comprising:
a heat exchanger configured to extract heat from compressed ammonia-laden water vapor received on a second side to impart heat to a manure slurry received on a first side thereby to evaporate ammonia-laden water vapor from the slurry, leaving a nutrient concentrate, the second side of the heat exchanger configured to cool, by transferring energy to heat the manure slurry in the first side, the ammonia-laden water vapor giving up its energy as heat through a phase change to ammonia-laden water leaving the second side at a process temperature;
a compressor to receive the evaporated ammonia-laden water vapor from the second side of the heat exchanger, compressing the evaporated ammonia-laden water vapor to raise its energy state and to feed it into the first side of the heat exchanger;
a reservoir for collecting the nutrient concentrate from the first side of the heat exchanger, thereby, segregating the nutrient concentrate from the manure slurry; and
an in-vessel composter for receiving the nutrient concentrate drawn from the reservoir as feedstock for composting therein.
2. The system of claim 1 , wherein in-vessel composter includes a manifold for receiving at least one constituent, the constituents comprising:
aerobic thermophilic microorganisms inoculating the feedstock; and
retained organic solids for augmenting the feedstock.
3. The system of claim 1 , further comprising:
a dryer for drying the nutrient concentrate to a fertilizer product, the degree of drying being selected to contain a proportion of solids in a range selected from a pair of ranges consisting of:
“moist” having a solids content of between 30% to 70%; and
“dry” having a solids content in excess of “moist”.
4. The system of claim 1 , including a primary separator configured to separate manure into each of a solid fraction and a liquid fraction, including a liquid fraction conduit to convey the liquid fraction to the first side of the heat exchanger to join the manure slurry, the primary separator being selected from a group consisting of:
screen separators;
filters; and
presses configured to dewater manure slurry.
5. The system of claim 4 , wherein the solid fraction from the primary separator is retained as organic solids.
6. The system of claim 1 , further comprising a secondary separator including a centrifuge to separate a secondary liquid fraction from a secondary solid fraction, the system to include a secondary liquid fraction conduit to convey the secondary liquid fraction to the first side of the heat exchanger to join the manure slurry.
7. The system of claim 6 , wherein the solid fraction from the secondary separator is retained as organic solids.
8. A system for converting manure to fertilizer, the system comprising:
a mechanical vapor recompression evaporator (“MVR”) for receiving a manure slurry, the MVR configured to separate ammonia-laden water as condensate from the manure slurry, yielding a nutrient concentrate, the condensate leaving the MVR at a selected process temperature;
an in-vessel composter to receive and compost the nutrient concentrate from the MVR;
an ammonia stripping tower to receive the ammonia-laden water, the ammonia stripping tower comprising a flow of air to liberate ammonia gas from the ammonia-laden water, the ammonia gas being entrained in the flow of air to be conveyed out of the ammonia stripping tower;
a buffering tower comprising a mist of sulfuric acid, the mist configured to intercept the flow of air, thereby to facilitate a chemical reaction precipitating the ammonia gas as ammonium sulfate from the flow of air.
9. The system of claim 8 , further comprising a primary separator configured to separate manure into each of a solid fraction and a liquid fraction, the liquid fraction being conveyed to the MVR to join the manure slurry, the primary separator being selected from a group consisting of:
screen separators;
filters; and
presses configured to dewater manure slurry.
10. The system of claim 8 , further comprising a secondary separator comprising a centrifuge to separate a secondary liquid fraction and a secondary solid fraction, the secondary liquid fraction being conveyed to the MVR to join the manure slurry.