WO2014116124A1

WO2014116124A1 - Method for converting residual biomass into biobriquettes and biobriquette produced by means of said method

Info

Publication number: WO2014116124A1
Application number: PCT/PE2013/000008
Authority: WO
Inventors: Estela De La Gracia Assureira Espinoza; Marco A. ASSUREIRA ESPINOZA
Original assignee: Pontificia Universidad Catolica Del Peru
Priority date: 2013-01-22
Filing date: 2013-07-22
Publication date: 2014-07-31
Also published as: PE20141487A1

Abstract

The invention relates to a method for producing a biobriquette from residual biomass of agricultural, agroindustrial and forest origin, and to a biobriquette produced by means of said method. Said method basically consists in: taking a representative sample and performing the physicochemical characterisation thereof, performing a first conditioning operation, performing a second conditioning operation, performing a grinding operation and a final screening operation, agglomerating the conditioned biomass, performing the pressing operation and finally curing the previously pressed biobriquette. The second conditioning consists of a roasting step and is carried out in a rotary reactor with a horizontal axis, in a non-pressurised environment, which lets in a small amount of air and does not require any external agent to inert the atmosphere wherein the process is carried out. The heating speed, the heating temperature and the period of residence at said latter temperature will depend on the type of residue and on other variables, the preferred values being: a heating speed of 20°C/min, a temperature of 270°C, and a period of residence of 40 minutes.

Description

PROCEDURE FOR TRANSFORMING RESIDUAL BIOMASS IN BIOBRIOUETS AND A PREPARED BIOBRIOUTE BY MEANS

SAID PROCEDURE

FIELD OF THE INVENTION

The invention consists of a process for manufacturing bio-labels from residual biomass of agricultural, agro-industrial and forestry origin and a bio-label manufactured by means of said process, which has been developed in the area of recycling processes, specifically in the area of manufacturing of solid fuels with residual organic matter. The invention is aimed at the agribusiness sector and the wood industry, both for small producers and for large companies.

STATE OF THE TECHNIQUE

The energy use of residual biomass, of agricultural, agroindustrial and forestry origin, in our country is very important, both for its economic value and for the social and environmental impact that can be generated. Currently, in some cases depending on the residue, there are other non-energy applications for these materials such as feed for livestock, fertilizer input, material for bedding for example, but the required volumes are reduced so that large amounts of residual biomass is wasted and for its elimination burns or throws into the rivers what generates environmental pollution.

The material is called a cubic, polyhedral or cylindrical form, with or without additives, bio-labeled, obtained by applying pressure to pulverized or ground biomasic elements which can be performed by means of piston presses or by other means well known in the state of the art such As the extrusion.

The shapes and dimensions of biobriquettes (cylindrical, cubic and polyhedral) will depend on the equipment used, mold and application. In the case of cylindrical elements, the diameter must be at least 25 mm. Likewise, a biolabel has a higher bulk density than the source material, which translates into a higher energy content per unit volume, and this facilitates handling and transport. Prior art biobriquettes made from residual biomass of agricultural, agroindustrial and forest origin (husks, shavings, etc.) without prior treatment, that is, only through the crushing or grinding and agglomeration stages, generally have the following disadvantages:

Contain a high percentage of volatile matter, which causes the production of fumes during combustion, unwanted aspects for being harmful to health and pollutants of the environment.

- Present the problem of biodegradation due to moisture.

On the other hand, in some European countries such as the Netherlands, research is carried out on the development of roasted wood pellets and their application in co-generation processes with mineral coal. "Roasting" is a process of moderate pyrolysis in an inert atmosphere to improve the characteristics of the source material.

However, this process is complex by involving a system to make the atmosphere inert and a sophisticated vertical tower type reactor.

BRIEF DESCRIPTION OF THE INVENTION

The solution proposed by the invention consists of a process or procedure to produce bio-labels from solid waste of agricultural, agro-industrial and forestry origin.

The procedure basically consists of taking a representative sample and performing its physical-chemical characterization, performing a first conditioning, performing a second conditioning, performing a final grinding and sieving, agglomerating the conditioned biomass, pressing and finally curing the already pressed biolabel .

In the second conditioning, an indirect flame roasting of the virgin material is carried out by means of a horizontal axis rotating furnace or reactor, applying a specific heating curve, in a non-pressurized environment, that is, it can be at atmospheric pressure, in which admits a slight amount of air by not requiring any external agent to inertize the atmosphere where the process takes place. With this roasting stage, better quality biolabels have been found than those made using unroasted virgin material. In fact, it is the process of roasting the residue that increases the calorific value of the biolabel by comparing it with that made from a residue in a virgin state, that is, without having been roasted.

Also, another advantage is that the new invented process is simpler than the processes known in the prior art which makes it replicable in regions of limited resources where this technology is also expected to be introduced.

In particular compared to that of roasting, the invention employs a horizontal rotating shaft reactor without the need for an inert atmosphere and tolerating a slight presence of oxygen. Our goal was to achieve a process that obtained the same results as those obtained in roasting but in a simpler way, so that it can be easily replicated in our environment.

Also, the process is advantageous because it facilitates the grinding of the materials as it is the most friable roasted material. Not all waste is equal. There are some that are abrasive, hard or fibrous. This makes grinding work difficult, which translates into longer grinding time and therefore greater energy expenditure. Also in greater wear of the mill parts in contact with the material. As is known, there are different types of mill: hammers, balls, discs, etc. Due to this, the contact elements are chosen depending on each material to be ground or crushed, and require a constant replacement due to their rapid wear. On the other hand, with the roasted materials the same type of contact elements can be used in any product and have greater durability.

Another aspect of the invention is a fuel, in particular a biolabel, manufactured by the process described above.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 Process flow.

Figure 2 Temperature curves during the tests.

Figure 3 Composition of initial waste. Figure 4: Composition of the final biolabel.

DETAILED DESCRIPTION OF THE INVENTION Figure 1 describes the general process, which consists of the following stages:

to. obtain a representative sample of the residue which will then be subjected to a series of tests for its chemical physical characterization in order to establish the required conditioning processes and the characteristics of the fuel.

b. perform a first conditioning that consists of performing at least one of the following operations: drying, crushing, preliminary grinding and sieving,

C. perform a second conditioning comprising the stage of roasting the previously conditioned biomass,

d. perform the final grinding of the roasted material until the material size is less than 149 microns (Tyler 100 mesh),

and. agglomerate the conditioned biomass using an organic gel,

F. perform the pressing of the mixture,

g. perform the healing of the already pressed biolabel.

The sampling and the physical-chemical characterization consists in determining in the sample the moisture content, the volatile content, the fixed carbon, the ash content, the calorific value, to perform an elementary, granulometry, density analysis, among others. characteristics, based on the results define the conditioning process to be carried out, among other things. This is done through essays widely known in the state of the art. This stage is critical because poor sampling would lead to erroneous results.

The first conditioning depends on the characteristics found in the sampling stage, depending on the size, shape and amount of moisture. For example, in the case of wood chips, it is only necessary to apply a sieving process in order to eliminate dust and obtain fractions greater than 3 mm, which turns out to be the most appropriate grain size for subsequent roasting. In the case of the coffee husk, this residue does not require any drying or crushing process due to its initial characteristics. On the other hand, in the case of barley bran coming from the brewing process, because the residue shows a high humidity, it is necessary to perform a pre-drying process to the sieving operation to reduce its humidity to values less than 15%. The stage of roasting the residue, which is a thermochemical transformation process, consists of a slow heating of the biomass by means of an indirect flame in an unpressurized atmosphere, that is, it can be at atmospheric pressure, with limited presence of oxygen. This process is carried out in a rotating horizontal cylindrical reactor heated by a gas burner. The application of this process allows to reduce humidity and volatiles, as well as to increase the calorific value, which generates significant improvements of its properties as fuel. It also makes it more friable, which facilitates grinding, and hydrophobic, which makes it more resistant to biodegradation. This step comprises the step of roasting the material at a temperature between 250 to 300 ° C, the preferred temperature being 270 ° C, with a residence or permanence time between 30 to 90 minutes, a residence time of 40 minutes being preferred, and a heating rate in the range of 10 ° C / min to 30 ° C / min, the preferred speed being 20 ° C / min. Temperatures, heating rates and residence times depend, among other aspects, on the waste and the cost of the process, however, the preferred values optimize many aspects.

In the next stage, the roasted material must be ground to a granulometry of less than 149 microns (0.149mm) using a laboratory hammer mill. An organic binder in the form of a gel is prepared, which for the present invention consists of a binder based on cornstarch and water. Then, this solution is mixed with the roasted and ground waste in the final milling, in proportions that do not exceed 15% by weight of this last component with respect to the total weight of the mixture. The use of this type of binder has the advantage of not affecting the energy content of the bio-labels so that the calorific value of the bio-label turns out to be equivalent to that of the raw material, that is the roasted residue, used for its production, in addition to present a low ash content.

The waste used in bio-labels can be, without being limited to them:

- coffee husk,

- barley bran, or

- wood chip.

The forms of biobriquettes can be: cubic, polyhedral or cylindrical. In a preferred embodiment of the invention the cylindrical biolabel has, on average, the following measures: 36 mm in diameter with a central hole of 1 1.5 mm and a height between 30 to 40 mm. The pressing stage is performed with conventional manual or hydraulic presses well known in the state of the art.

Finally, the obtained biobriquettes are subjected to a curing process at 160 ° C, for 30 minutes, in an electric oven, being able to reduce the moisture content present and improve its mechanical properties.

Execution Example

We worked with the three types of waste, coffee husk, barley bran, wood chips, being in the virgin matter humidity between 10% and 17%, a high percentage of volatile matter of at least 75% and a low ash and fixed carbon content (see figure 3).

In the case of barley bran, drying prior to sieving was done naturally under the sun.

The fundamental roasting stage was carried out in a horizontal axis rotary coffee roaster, heated by indirect flame, and adapted for the process.

The binder used was organic, based on cornstarch and water.

In our example, pressing or compaction was performed in a piston press, easy to operate, typical in low to medium pressure processes.

The developed biobriquettes were cylindrical in shape, 36 mm outside diameter with a central hole of 1.5 mm and a height between 30-40 mm on average. In figure 4, a table is presented with the results of the analysis applied to the bio-labels developed from the residues of coffee husk, barley bran and wood chips. These results show that volatile matter was reduced and represented 60%, ashes increased slightly, and fixed carbon, a factor that directly affects the calorific value of biofuel, increased to 30 to 40%. The calorific powers of the samples obtained measured on a dry basis were 4536 kcal / kg (coffee husk), 5127 kcal / kg (barley bran) and 4865 kcal / kg (wood chip), respectively. As can be seen in all cases, a reduction in volatile matter content and a significant increase in fixed carbon content have been achieved with respect to the values recorded in virgin waste.

In conclusion, the developed bio-labels showed advantages over the bio-labels developed by the prior art procedures, since they showed a density greater than 550 kg / m3 in the case of wood chips and barley bran and greater than 700 kg / m3 in the case of the coffee husk, a durability greater than 97%, a greater caloric power than the base material and resistance to biodegradation (fungus formation). The durability was measured by placing the biobriquettes in a vibrating device that simulates real conditions that occur during the handling and transport of the fuel (impacts between briquettes and, of the briquettes with the walls of the container), the durability index being measured as the ratio of the Briquette weight after the test and before the test. Biodegradation resistance was measured by observation with respect to the emergence of fungi several days after the biolabel was produced. This problem is very frequent when the briquettes are prepared with virgin material, that is, without prior roasting treatment. Toasted biobriquettes did not present this problem. The results obtained broadly satisfy the international quality standards set for this type of fuel and allow the use of solid agricultural, agroindustrial and forestry wastes as organic biofuels, promoting industrial development and improving living conditions.

Claims

Claim 1

Procedure to prepare a biolabel from solid waste biomass of agricultural, agroindustrial and forestry origin, which includes the following stages: a) Obtain a representative sample of the residue for its adequate chemical physical characterization in order to establish the required conditioning processes and the characteristics of the fuel.

b) Carry out a first conditioning that consists of performing at least one of the following operations: drying, crushing, preliminary grinding and sieving,

c) Perform a second conditioning comprising the stage of roasting the previously conditioned biomass,

d) Grind and sift the roasted material to a particle size of less than 149 microns.

e) Agglomerate the conditioned biomass using an organic gel

f) Perform the pressing of the mixture

Characterized by roasting in a horizontal axis reactor with a heating rate of 10 to 30 ° C / min until reaching a roasting temperature between 250 to 300 ° C with a residence time at this temperature between 30 to 90 minutes

Claim 2

Procedure to prepare a biolabel from biomass of solid waste of agricultural, agroindustrial and forestry origin, which includes the following stages: a) Obtain a representative sample of the residue for its adequate chemical physical characterization in order to establish the conditioning processes required and fuel characteristics.

c) Perform a second conditioning,

e) Agglomerate the conditioned biomass using an organic gel

f) Perform the pressing of the mixture Characterized because the second conditioning consists in roasting the previously conditioned biomass.

Claim 3

Procedure for preparing a biolabel from solid waste biomass of agricultural, agroindustrial and forestry origin according to claim 2, characterized in that the roasting stage is carried out in a horizontal axis reactor and with a heating rate of 10 to 30 ° C / min until reaching a roasting temperature between 250 to 300 ° C with a residence time at this temperature between 30 to 90 minutes.

Claim 4

Procedure for preparing a biolabel from solid waste biomass of agricultural, agroindustrial and forestry origin according to claims 1 or 3, characterized in that the heating rate is 20 ° C / min, the roasting temperature is 270 ° C and the residence time at this temperature is 40 minutes.

Claim 5

Procedure for preparing a biolabel from solid waste biomass of agricultural, agroindustrial and forestry origin according to any of the preceding claims, characterized in that the residue can be one of the following: coffee husk, wood chips or barley bran . Claim 6

Procedure for preparing a biolabel from solid waste biomass of agricultural, agroindustrial and forestry origin according to any of the preceding claims, characterized in that the obtained biolabels have a density of at least 550 kg / m3. Claim 7

Procedure for preparing a biolabel from solid waste biomass of agricultural, agroindustrial and forestry origin according to any of the preceding claims, characterized in that the curing process is carried out at 160 ° C for 30 minutes. Claim 8

Biolabel made by any of the methods described in claims 1 characterized in that it has a density of at least 550 kg / m3.