PROCESS FOR PRODUCING BIOMASS BY TREATMENT OF ORGANIC WASTE WITH TWO-STEP DRYING

Abstract

The continuous process of the present invention is intended to obtain dry biomass from two treatment steps by drying organic waste. The waste previously sieved and crushed waste are dumped into a first dryer, inside of which temperatures are between 280° C. and 300° C. at the inlet thereof and between 90° C. and 100° C. at the outlet, then passing to a conveyor belt where at room temperature a partial cool-down occurs and the waste is dumped into a second dryer inside of which the temperatures are between 180° C. and 200° C. at the inlet and between 75° C. and 85° C. at the exit, completing the process, during which the interior of the dryers is maintained in negative pressure through exhaust flow and the oxygen content is kept between 5 and 7%.

Claims

1. A PROCESS FOR OBTAINING DRY BIOMASS UPON TREATING ORGANIC WASTE THROUGH TWO DRYING STEPS, characterized by comprising continuous steps, said steps being controlled using controllers, said controllers adjusting load quantity, firing temperature, passage speed and negative pressure to be employed, the process further comprising the passage of the mass through tubes with cooling properties, said tubes through which the object mass of present process passes comprising two concentric cylindrical tubes, the tube of smaller diameter carrying the mass and the larger diameter tube comprising the passage of a cooling element that cools the outer wall of the smaller diameter tube and, consequently, the mass carried by it, the steps comprising: continuously transporting wet waste through conveyor belts containing mostly organic waste, previously sieved and crushed, dumping them into the inlet located at one end of a first rotating cylindrical dryer provided inside with fins that conduct waste towards the dryer outlet located at the other end thereof, the interior of the dryer showing temperatures, generated by hot air supplied by a furnace coupled to the inlet end, between 250° C. and 300° C. at the dryer inlet and between 90° C. and 100° C. at the exit thereof; subjecting the waste to pre-drying treatment during the dwell time in their displacement in the first dryer, between 20 and 30 minutes, the first dryer being provided at the exit thereof from a powered exhaust fan to produce hot air flow in exhaust depression (negative pressure), removing above 50% from the wet load present in the waste; removing from the interior of the first dryer during the pre-drying step the wet load released in the form of steam through the exhaust duct positioned near the exit of the dryer; dumping the pre-dried waste on a conveyor belt where it will move at room temperature, being cooled down during the dwell time thereof, which will be between 20 and 30 minutes, and at the end continuously dumped into the inlet of a second rotating cylindrical reactor provided with guiding fins of the waste located at one end of the dryer, the interior of the dryer showing temperatures generated by hot air supplied by a furnace coupled to its inlet end between 180° C. and 200° C. at the entrance thereof and between 75° C. and 85° C. at the outlet thereof; carrying the pre-dried waste through the second dryer for a dwell time around 20 minutes, subjecting it to final drying, the dryer at the outlet thereof located at the other end thereof being provided with a powered exhaust fan to produce hot air flow in depression by exhaustion (negative pressure), thus removing the rest of wet waste load; removing from the interior of the second dryer during the final drying step the remainder of the wet load released in the form of steam through an exhaust duct provided with an exhaust fan; transporting the dry biomass resulting from the previous steps to a storage silo, said process further comprising the transportation of cargo by cased transport ducts for cooling the mass in the passage between furnace/burners and between the second burner and the storage silo, the casing comprising the casing of transport ducts for cooling by the cooling element.

2. The PROCESS according to claim 1, characterized in that the cooling element is water.

3. (canceled)

4. The PROCESS, according to claim 1, characterized in that the intensity of the flames of the burners of the furnaces of the dryers are controlled by computerized control means from temperature data collected by sensors installed at the outlet ends of the dryers, said controllers being adjusted according to the load to be subjected to the treatment process and/or according to the behavior of the material during the passage through the dryer/burner.

5. The PROCESS, according to claim 1, characterized in that the oxygen content inside the dryers upon flow of hot air in depression by exhaustion (negative pressure) is kept around 5% to 7%, preferably 6%.

6-7. (canceled)

8. The PROCESS, according to claim 1, characterized by comprising the reaction of calcium hydroxide (Ca(OH).sub.2) with carbon dioxide (CO.sub.2), the reaction taking place in a separate circuit, in the same organic waste processing plant, using CO2 resulting from the burning in the furnaces.

9. (canceled)

10. The PROCESS, according to claim 1, characterized in that the burners are fed by the dried biomass by product.

11. The PROCESS, according to claim 1, characterized in that the organic waste subjected to treatment of pre-drying sterilization and drying are organic waste of household waste.

12. The PROCESS, according to claim 1, characterized in that the organic waste subjected to pre-drying and drying treatment is organic waste of household waste that was previously separated from the non-organic waste present in the waste, submitted to drainage of slurry present therein, and subjected to crushing.

Description

[0031] For illustrative purposes of the present invention, the FIGURE is presented, which represents a flowchart of the process described above in the preferred embodiment thereof.

[0032] The present invention further provides the reaction of calcium hydroxide (Ca(OH).sub.2) with carbon dioxide (CO.sub.2).

[0033] As explained, calcium hydroxide—CaO+H.sub.2O->Ca(OH)2—is previously formed, which is then reacted with carbon dioxide, forming Calcium Carbonate and water—Ca(OH).sub.2+CO2->CaCO.sub.3+H.sub.2O.

[0034] These procedures take place in a separate circuit, in the same organic waste processing plant, using CO.sub.2 from the burning in the furnaces.

[0035] Another point is to feed the burners with the biomass produced. Once the process has started with, for example, LPG to produce the first tons of biomass, the furnace is then fed with the biomass produced in the process.

[0036] Notwithstanding the present invention being illustrated according to a currently preferred embodiment, it is understood that the same is not a limitation of the invention since changes and modifications will be readily apparent to those skilled in the art at each application of the process considering the foregoing. Therefore, the invention should be limited only by the scope of the following claims.