FR3138145A1 - Agrofuel Manden® - Google Patents

Abstract

Device for producing peanut shell pellets.

Description

Agrofuel Manden®

Manden® is a high performance agro pellet meeting the NF ISO 17225-2 to 6 standard.

Manden® agro pellet is an alternative to wood pellets.

Manden® agro pellet is a biofuel that can be used in cogeneration units to replace fossil fuels.

Device for producing granules based on peanut shells comprising:

a) a granulation unit for peanut shells.

b) an organic additive addition unit to reduce the ash content of peanut shell granules, with a view to optimizing the combustion of peanut shells in fluidized bed furnaces.

Peanut (Arachys hypogaea), as well as chickpeas, lentils, beans and peas native to South America, mainly used for culinary purposes, in confectionery products or as nuts, as well as for production cookies, breads, candies, cereals and salads.

Due to its high fat percentage, peanuts are used for industrial products such as oils, flours, inks, creams, lipsticks, etc. According to the FAO Statistical Yearbook 43,982,066 t, produced on 27,660,802 hectares. Peanuts are grown mainly in Asia, with a global production rate of 65.3%, followed by Africa with 26.2%, the Americas with 8.4% and Oceania with 0.1%. The peanut industry is one of the main producers of food industry waste (shellfish). This residual biomass (25-30% of total weight) has a high energy content which is worth exploring

Peanut shell is the main residue in the peanut industry and accounts for between 25% and 30% of the total weight of the legume and is removed as a residue in the final stage of peanut processing. Each year, the peanut industry has not yet explored the global production of this waste, which represents 11 million tonnes.

Therefore, a large amount of peanut industry waste being disposed of can be used as biomass for energy purposes for developing countries at lower costs.

1. Materials and methods

Physical parameters such as humidity are defined as the total quantity of water contained in the total mass of a biomass sample. Moisture can exist on the exterior surface of the biomass or be integrated into it.

Chemical properties mainly concern the composition of the constituent elements of biomass (nitrogen, hydrogen, carbon, oxygen and sulfur). The ash content (inorganic elements) and behavior are also often of interest.

Elemental analysis makes it possible to establish the percentage by weight of the main elements most present in the molecular structure of organic matter: carbon (C), hydrogen (H), nitrogen (N), oxygen (O) and sulfur (S). ). From the knowledge of these constituents, the oxidation reactions can be established, so that, for example, the precise combustion air (stoichiometric air) can be determined. There are also certain empirical formulations which, based on the percentage by weight of each element, make it possible to obtain an approximation of its energy content (calorific value)

2. Quality Settings peanut shell

The UNE-EN 14961-1 standard “Solid biofuels - Fuel specifications and classes - Part 1: General requirements”, established by the Spanish Association for Standardization and Certification (AENOR), was applied to determine the quality parameters of the peanut shells. The parameters of these standards are shown in [Table 1].

A proximate analysis provides moisture, ash, volatile matter and fixed carbon content of the biomass, expressed as percentages by weight. Basically, this analysis serves to identify the fraction of biomass in which its chemical energy (fixed carbon and volatile compounds) and its inert fraction (ash and moisture) are stored.

Volatile matter is the part of the fuel that is released as gases and vapors (hydrocarbons) when the biomass is thermally decomposed. Fixed carbon and ash are the fractions that remain after the volatile material has been released. Fixed carbon, in combustion processes, continues to burn slowly after the release of volatiles.

Ashes are the inorganic residues that remain after the combustion of fixed carbon and whose composition and percentages of participation vary depending on the source of biomass and the collection methods used.

The calorific value is the chemical energy of the fuel which can be transformed directly into thermal energy by a thermochemical oxidation (combustion) process. This property is usually expressed in units of energy per unit mass (usually kJ/kg, MJ/kg or lime/kg). Its value is determined experimentally by a device called a calorimetric pump.

There are two ways to express the calorific value of a fuel. If, after combustion, the water formed in the combustion gases (from humidity or from the oxidation of hydrogen) is in liquid form, the highest calorific value (GCV) is obtained. If it remains in vapor form, the lower calorific value (LCV) is obtained. They can be expressed per unit of wet fuel or dry fuel.

The energetic properties of peanut shells were analyzed based on their main statistical descriptors. Furthermore, these properties were compared to those of other biomass wastes.

3.1. Peanut Shell Quality Parameters Peanut shell samples obtained from the peanut industry were analyzed to evaluate and determine the quality parameters. The first step in applying a fuel is to determine its chemical composition. The chemical composition of a fuel determines its properties, quality, applications, and environmental problems that can cause it to burn. See [Table 2] the mean, median, standard deviation and the minimum and maximum values of the different parameters.

It is important to know the percentage of N, S and Cl of each type of biomass in order to study the environmental impact caused by its combustion, the percentage of ash which poses thermal efficiency problems in boilers, as well as the quantities of C, H, and O to estimate the calorific value of the biomass in question.

Peanut shells contribute to environmental conservation because their emissions into the atmosphere are lower than those of solid fuels due to their low sulfur (0.54%), nitrogen (0.50%) content. and chlorine (0.07%). [Table 3] presents a comparison of the parameters obtained from peanut shells and other biofuels used in boilers, such as olive stones, pine pellets, almond shells or almond kernels. lawyer.

The biggest advantage is the neutral CO2 balance by closing the carbon cycle as the plants started to grow. Therefore, we can say that biomass emissions are not pollutants, because their composition is essentially part of the CO2 captured by the plant from which the biomass and water vapor come.

The accumulation of ash deposits inside biomass boilers poses thermal efficiency problems and can obstruct the ducts through which the combustion gases circulate.

Ash generated after biomass combustion is particularly problematic due to its low melting points and the high concentrations of alkali metals it contains, which promote corrosion of pipes and boiler walls.

The average ash content in peanut shell is 4.26%, which compared to other biomasses, such as olive pits (0.77%), avocado pits (2. 86%), oak pellets (3.32%) and almond hulls (0.55%), it can be observed that although its value is high, it is within the average values of ashes produced by other biofuels used in boilers.

Despite all the advantages of biomass as a fuel, it also poses significant technical problems in boilers. It is very important to consider the Cl content of the biomass, as low melting point ashes are generated, which at 700–800 C, begin to soften and have corrosive properties, therefore the impact of deposition of these ash on the system must be taken into account.

If there is a large amount of ash deposit, this can lead to a failure which may result in boiler shutdown. In this case, expensive manual cleaning of the heat transfer surfaces will be necessary.

If we analyze the chlorine values for peanut shells we can see that these values are much lower than those obtained for almond shells, pine pellets or avocado pits, so its use as a biofuel would improve corrosion problems in furnaces.

Thermal applications with heat and hot water production are the most common in the biomass sector, although they can also be used for electricity production.

Biomass can power an air conditioning system (hot and cold) in the same way as if it were powered by gas, diesel or electricity.

Thermal production can be achieved by:

- Stoves, usually made of pellets or wood, which create a single room and generally act simultaneously as decorative elements.

- Low power boilers for individual homes or small buildings.

- Boilers designed for a block or apartment building, which act as central heating.

- Thermal power plants which heat several buildings or installations (district heating) or a group of houses.

Normally, residual biomass has a high moisture content (over 100% on a dry basis), so it requires prior conditioning for further use for energy purposes. The peanut shell has a very low moisture content (5.79%), which is a great advantage because it does not need to be dried for energy purposes.

The values of PCS and PCI in peanut shells range between 18.572 and 18.522 MJ/kg and 17.122 and 17.100 MJ/kg, respectively. The variations are very small when applying the standard deviation, and they are values similar to those obtained by other authors: 18.920 MJ/kg or 19.2 MJ/kg. It should be noted that the calorific value of peanut shells is similar or even higher than that of other biofuels.

For example, the PCS of peanut shells (18,547 MJ/kg) is higher than that of olive stones (17,885 MJ/kg) or almond shells (18,200 MJ/kg). Table 3 shows this comparison and the PCS biomass/PCS peanut shell ratio, which shows that there are no variations greater than 10%.

Many resources covered by the term solid biofuels for heat and/or electricity production are characterized by their high moisture content. The fact that biofuels always have a certain moisture content is due to two causes. On the one hand, it should be borne in mind that water is the transport vehicle for nutrients in plant matter, that is, water is an inherent component of it. On the other hand, the resources considered here are characterized like all plant matter by their hygroscopicity, that is to say by their capacity to absorb and lose humidity according to the environmental conditions of the surrounding environment to maintain hygrometric balance.

The water content can reach values even higher than 60% of the total weight of the biofuel, increasing the costs linked to its handling (transport, storage and supply to the factory) and making it difficult to carry out all the operations necessary for its energy transformation ( grinding, densification, combustion, etc.).

In the case of peanut shells, its moisture content is very low, meaning that no drying treatment would be required, making it an ideal biofuel for use in heat production in domestic boilers or industrial.

3.2 Predictive models to estimate the PCS of peanut shell

The GCV (high calorific value) of biomass can be calculated theoretically from correlation equations that relate the elemental composition of biomass and other chemical elements. [Table 4] shows 20 correlation equations from relevant authors in this field that were used to calculate the PCS value of different biomasses from the experimental values of their elemental composition, sulfur, ash, fixed carbon and volatile matter.

It should be kept in mind that the analyzed formulas correspond to the PCS prediction for different types of biomass, in which the number of samples or the analysis methodology used must be taken into account. Therefore, it should be noted that despite the different origins of the formulas proposed by different authors, the prediction results of PCS from peanut shells are very similar.

[Table 5] summarizes the results obtained by applying the equations of [Table 4]

These prediction results tell us about the PCS value.

If we observe [Table 5], the best prediction result of PCS value for peanut shell was obtained with equation (12) with a deviation of 0.165%, followed by equation (11), proposed by Demirbas et al. (2004), with a difference of 0.259%. In third place is equation (9), proposed by Tillman (1978), with a deviation of 0.444%, and fourth, equation (18).

Only it should be noted that equations (9), (11), (12) and (18) require only one parameter for their calculation, assuming that the PCS is a linear function of its carbon content, then the algebraic equation has the form PCS = a + b·C, where C is the carbon content (%). This turned out to be the most optimal formula for calculating the PCS, with an expected error of less than 1% in absolute value.

It should be noted that carbon and oxygen almost always make up about 90% of the biomass weight and the correlation between carbon and oxygen is also high, so the results make sense.

Therefore, the main advantage of this equation is that by using data from an elementary component of biomass like carbon, no more sophisticated laboratory equipment is needed, which is not always available everywhere.

3.3 Potential of peanut shell to reduce CO2 emissions

Carbon dioxide emissions into the atmosphere are a major environmental concern. Considered one of the reasons for climate change, an alternative to fossil fuels is making headway: biomass.

The burning of fossil fuels is one of the main reasons for global warming. The search for energy sources to replace coal or oil is necessary to maintain sustainable economic development. This section shows the benefits of using peanut shells as a biofuel to reduce CO2 emissions.

Once the various energy parameters of the peanut shell are known, its energy output can be calculated from the world peanut production using the equation:

Ec = RH Pc PCS fs Uc

where: Ec is the energy production potential using peanut shell as biofuel in each country (MWh); RH is relative humidity (10%); Pc is peanut shell production in each country (kg); PCS is the gross calorific value (18.547 MJ/kg); fs is the shell factor in a whole peanut (30%); Uc is the unit conversion (0.000277778 Wh/D).

The largest energy production from peanut shells is in China (25,579.75 MWh), followed by India (11,440.42 MWh), Nigeria (5,253.69 MWh), United States (3637.60 MWh) and Sudan (2891.79 MWh).

In many industrialized countries, biomass represents more than 50% of national energy consumption. There, biomass energy consumption is often much lower due to the predominant contribution to “fossil fuel” consumption. This situation reached a turning point in the 1970s with the first oil crisis, the contribution of “fossil fuels” which allowed us to glimpse the unsustainability of a model based on the almost exclusive use of the fossil crisis.

Since then, there has been a growing interest in energy saving and energy efficiency such as the consumption of local renewable resources, including biomass, with the dual objective of reduction as well as the consumption of local renewable resources, including biomass, with the dual objective of energy dependence and CO2 emissions. Therefore, to limit this increase in emissions, it is strategic to reduce energy dependence and CO2 emissions.

In order to limit this increase, strategic plans such as the European Union Strategic Framework for 2030 or the Clean Energy Plan have been implemented, in which the United States commits to reducing its CO2 emissions by 32% by 2030.

Energy competitiveness must be complemented by other measures to combat climate change, that is to say, to curb the increase in greenhouse gas emissions without harming economic growth:

- Improved efficiency.

- Limiting inefficient coal-fired power plants

- Decrease in methane emissions from oil and gas.

- Reform of fossil fuel subsidies.

- Increase in renewable energies, without their use leading to a loss of competition compared to other countries where there are no measures to reduce greenhouse gas emissions.

In this work, the CO2 reduction that would result from the use of peanut shells as an energy source was evaluated using the total emissions values for 2014 (latest update) provided by the values of the World Data Bank for 2014 (latest update) (http://databank.worldbank.org/data/home.aspx) and global peanut production data for the same year (2014) provided by FAO were taken as a reference.

It was also considered that if the energy that could be produced from peanut shells was produced from conventional energy sources, these would generate e, 0.357 t of these CO2.

Therefore, global CO2 savings would be equivalent to if the energy produced by the peanut shell was produced by conventional sources.

It makes sense that the greatest savings in CO2 emissions would occur in countries with the highest peanut production, as they would be the largest producers of energy with this biofuel. The top 10 countries are: China (18.22 kt), India (4.08 kt), Nigeria (1.88 kt), Myanmar (0.83 kt), Argentina (0.64 kt), Chad (0.44 kt), Senegal (0.37 kt), Tanzania (0.90 kt) and the United States (1.30 kt).

Biomass residues are a potentially enormous source of energy-producing materials. This study evaluated the energy parameters of peanut shells as a possible solid biofuel applied as an energy source in industrial and residential heating plants, reducing global CO2 emissions that would result from their use.

PCS is a major property of biomass fuels. The GCV of the obtained peanut shells (18,547 MJ/kg) is higher than other biomass sources such as almond shells (18,200 MJ/kg) or olive pits (17,885 MJ/kg) and similar to other biomass sources currently used for industry and homes in heating applications. Different PCS value prediction models proposed by scientists for different types of biomass were analyzed and the one that best fits the peanut shell calculation of biomass was determined. Therefore, among the mathematical equations analyzed for PCS estimation, the best performances were linear equations based only on total carbon content, which showed a deviation of less than 1%; More precisely,

PCS = -3.147 + 0.468 C.

The potential applications of using renewable energy sources such as biomass to replace the combustion of fossil fuels as a primary energy source are vital in all countries around the world. Peanuts are grown mainly in Asia, with a global production rate of 65.3%, followed by Africa with 26.2%, the Americas with 8.4% and Oceania with 0.1%.

The CO2 reduction that would result from using peanut shells as an energy source was evaluated. The 10 countries with the highest CO2 savings, China (18.22 kt), India (4.08 kt), Nigeria (1.88 kt), Myanmar (0.83 kt), Argentina (0.64 kt) , Chad (0.44 kt), Senegal (0.37 kt), United Republic of Tanzania (0.90 kt) and the United States (1.30 kt).

Claims (2)

Device for producing granules based on peanut shells comprising:
a) a granulation unit for peanut shells
b) an organic additive addition unit to reduce the ash content of peanut shell granules, with a view to optimizing combustion in fluidized bed hearths. Agro pellet based on peanut shells obtained in the production device according to claim 1.