# Investigation of technical usability of wine residues

Maximilien Valente, Cornelius Schonnenbeck, Gwenaelle Trouve, Alain Brillard, Jean-François Brilhac

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Maximilien Valente, Cornelius Schonnenbeck, Gwenaelle Trouve, Alain Brillard, Jean-François Brilhac. Investigation of technical usability of wine residues. Innovations for sustainable biomass utilisation in the Upper Rhine Region, KIT - Karlsruher Intitut für Technologie, pp.74-86, 2017, 978-3-7315-0423-8. 10.5445/KSP/1000048433 . hal-03321677

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Submitted on 18 Aug 2021

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<figure><img src="image_1.png" /></figure>
Preliminary results indicated that the Ni/ceria-based catalyst developed at ICPEES is active for co-methanation. The last results confirm that, even at high velocity and high hydrogen deficiency, and under conditions simulating the syngas composition expected from wine residues pyrolysis at high temperature, the developed catalyst is efficient and stable. This catalytic material is then totally adapted to be used in a methanation reaction, online with a pyrolysis unit for the energetic valorisation of wine residues.

### 3.2.2 Investigation of technical usability of wine residues

Maximilien Valente, Cornelius Schönnenbeck, Gwenaëlle Trouvé, Alain Brillard, Jean-François Brilhac

Laboratoire de Gestion des Risques et Environnement (GRE), Université de Haute Alsace, Mulhouse, France.

The Alsace Region (France) is known for wine production (15 600 hectares) leading to large quantities of grape marc. Using the factors given by Toscano et al. (2013), the calculated corresponding dry matter is 12 000 tons per years. Different pathways (Saidur et al. 2011) are developed for the valorization of the wine residues (distillery, large scale thermal facility for energy recovery, etc.). Beside them, wine residue presents a great interest for energy recovery. Celma et al. (2007) assessed the use of grape marc in Extremadura (Spain) and calculated good economical specific costs and on site availabilities for this surrogate fuel. Toscano et al. (2013) examined the physical-chemical composition (especially carbon content) of grape marc residues in Italy and exhibited values close to wood chips, beech chips or wheat straw. Considering biomass combustion, a lot of recent works point out domestic boilers as an important source of particles emissions. Favez et al. (2009) demonstrated that in Paris, during winter, 20±10% of the ambient PM₂.₅ mass can be attributed to biomass burning.
Hence a constant assessment of combustion quality, especially at the domestic boiler scale, has to be performed in order to limit pollutants emission.

Burning of wine residues in a domestic biomass boiler can be considered as an alternative pathway for grape marc recovery. The winemakers could then use directly part of the waste produced during wine production as a fuel. The present contribution is devoted to the study of grape marc combustion for a low environmental impact. To our knowledge, this study is the first considering grape marc combustion in a domestic scale boiler. The aim is to characterise the thermal degradation of grape marc by thermogravimetric analysis and to analyse the energy recovery in a domestic boiler focusing on the emission factors of gas and particulate matter.

### 3.2.2.1 Material and methods

#### Samples and characterisation

Wine residues were collected directly after the pressing step and delivered by a winemaker located in Orshwir (Alsace, France). For the thermogravimetric analysis (TGA), three different varieties of grape marc were tested: Sylvaner, Chasselat and Pinot Gris. Gewürztraminer variety was used for the experiments in the multi-fuel boiler. In addition, two different biomasses were used in this study for multi-fuels experiments in the boiler: miscanthus giganteus locally produced at Ammertzwiller (Alsace, France) and DIN CERTCO pellets, purchased from SOFAG (Arc sous Cicon, France). Physical and chemical characterisations of the different samples were performed. Ultimate analysis was carried out to determine carbon, hydrogen, oxygen, nitrogen and sulfur weight fractions. Table 3.5 gives the results for Gewürztraminer variety. The results obtained for the other grape marc varieties are presented in Valente *et al.* (2015).

Samples were characterised following the standard XP CEN/TS for the moisture, ash contents and the low heating value (LHV). A calorimetric bomb (IKA) was used to determine the high heating value (HHV). Low heating values (LHV) were calculated based on free ash and water contents.
<table><caption>Table 3.5: Fuel characteristics.</caption><thead><tr><th rowspan="2"></th><th rowspan="2">LHV<sup>V</sup><br>MJ.kg<sup>-1</sup></th><th rowspan="2">Moisture<br>%</th><th rowspan="2">Ash<sup>c</sup><br>%</th><th colspan="4">Ultimate Analysis on dry basis (%)</th></tr><tr><th>C</th><th>H</th><th>O</th><th>N</th><th>S</th></tr></thead><tbody><tr><td>Pellets (DIN CERTCO)</td><td>17.7</td><td>8</td><td>0.3</td><td>47.1</td><td>6.1</td><td>46.6<sup>b</sup></td><td>&lt;0.1</td><td>&lt;0.1</td></tr><tr><td>Pellets/Grape 66/33</td><td>13.2<sup>a</sup></td><td>27</td><td>0.8</td><td>48.0<sup>a</sup></td><td>6.3<sup>a</sup></td><td>n.d.</td><td>n.d.</td><td>n.d.</td></tr><tr><td>Pellets/Grape 50/50</td><td>10.9<sup>a</sup></td><td>37.5<sup>a</sup></td><td>n.d.</td><td>48.6<sup>a</sup></td><td>6.3<sup>a</sup></td><td>n.d.</td><td>n.d.</td><td>n.d.</td></tr><tr><td>Grape (27% humidity)</td><td>14</td><td>27</td><td>0.8</td><td>50.04</td><td>6.42</td><td>36.48<sup>b</sup></td><td>2.49</td><td>&lt;0.3</td></tr><tr><td>Beech wood chips</td><td>16.5</td><td>5</td><td>0.4</td><td>47.6<sup>d</sup></td><td>5.7<sup>d</sup></td><td>44.8<sup>d</sup></td><td>0.42<sup>d</sup></td><td>0.01<sup>d</sup></td></tr><tr><td>Miscanthus</td><td>16.7</td><td>10</td><td>1.4</td><td>47.7</td><td>5.89</td><td>43.7</td><td>&lt;0.3</td><td>0.12</td></tr><tr><td>Misc/Grape 75/25</td><td>13.5<sup>a</sup></td><td>24.25<sup>a</sup></td><td>n.d.</td><td>49<sup>a</sup></td><td>6<sup>a</sup></td><td>n.d.</td><td>n.d.</td><td>n.d.</td></tr><tr><td>Misc/Grape 66/33</td><td>12.5<sup>a</sup></td><td>32</td><td>1.5</td><td>49.1<sup>a</sup></td><td>6.1<sup>a</sup></td><td>n.d.</td><td>n.d.</td><td>n.d.</td></tr><tr><td>Misc/Grape 50/50</td><td>10.4<sup>a</sup></td><td>38.5<sup>a</sup></td><td>n.d.</td><td>49.4<sup>a</sup></td><td>6.2<sup>a</sup></td><td>n.d.</td><td>n.d.</td><td>n.d.</td></tr><tr><td>Grape (67 % humidity)</td><td>4</td><td>67</td><td>0.4<sup>a</sup></td><td>50.04</td><td>6.42</td><td>36.48<sup>b</sup></td><td>2.49</td><td>&lt;0.3</td></tr></tbody></table>

<footnote><sup>a</sup>: calculated, <sup>b</sup>: calculated by difference, <sup>c</sup>: on raw basis, <sup>d</sup>: www.ecn.nl/phyllis2/Browse/Standard ECN-Phyllis Beech #64, n.d.: non determine</footnote>
The boiler is devoted to multi-fuels presenting humidity up to 30-35%. Hence combustion tests of raw grape marc exhibiting a moisture content of 67% were not performed. Raw grape marc was then dried in order to reduce its humidity from 67% to 27%. In the current study, this dry grape marc was combusted in the REKA boiler and thermal and environmental performances were compared to those of DIN CERTCO pellets and miscanthus in preliminary experiments. Blends of miscanthus/dry grape marc and DIN pellets/dry grape marc in weight proportions 75/25, 66/33 and 50/50 were also prepared and tested in the REKA boiler. The fuel properties of the blends are given in the Table 3.5.

## Thermogravimetric analysis (TGA)

The pyrolysis and the combustion of different parts of grape marc (skin, seed and stalk) were investigated by TGA in order to propose a relevant kinetic model and the corresponding kinetic parameters. For the last purpose, an extended Independent Parallel Reaction (IPR) model is proposed assuming that the biomass structure is decomposed according to the lignocellulosic material representation. The IPR kinetic model is indeed extended in order to take into account both the devolatilisation and the char combustion stages. Experiments were performed in a thermobalance TA Q500 at heating rates of 5, 10, 20 and 50°C/min, in the temperature range 30–800°C, and under a synthetic air flow of 3.6 NL/h (20% O2, 80% N2). Some experiments were also performed under pure nitrogen. Small sample masses (10–30 mg) were used in order to reduce as far as possible mass and heat transfer limitations by diffusion inside the solid fuel bed.

## Combustion tests in a multi-fuel boiler

Combustion tests were performed in a multi-fuel boiler (HKRST-FSK) supplied by REKA (Aars, Denmark) equipped for combustion studies. Performance of the boiler ranges from 30 to 40 kW. The boiler basis is a moving stepped grate. The step grate permits to use almost any biomass fuel since the grate movement prevents the possible slag formation. As the boiler and the fitted hopper were located on a balance, the mass loss and then the consumption of the biomass (pellets/ wood chips/ grape marc)
were recorded. First experiments were performed using grape marc with 27% of relative humidity. Then combustion was performed with grape marc blended with wood pellets and miscanthus. Due to the heterogeneity of the samples it was not possible to stabilise the combustion of these blended samples. As a consequence new blended samples were prepared by grinding the grape marc with Miscanthus or Pellets and thus homogenizing the blended fuel. Thermal behaviour of the boiler was tested with samples at steady state during 30 min for experiments repeated at least three times. Considering the LHV and the heat losses during combustion, it is possible to evaluate the input and output powers. The combustion efficiency was then estimated using the NF EN 303-5 standard (revised 2012) related to boilers with a heating power lower than 500 kW and corresponding to the class 5. For fuels or blended fuels with low water content (up to 33%) the boiler efficiency was found always higher than 90% and this value is totally relevant considering the NF EN 12809 standard requiring an efficiency of at least 85%.

## Gas emissions and particle matter analysis

Emissions were measured in the chimney according to EN-304 standard (NF EN 304/A1, 1998) during experiments on the REKA boiler. Flue gas temperatures were continuously recorded. O₂, CO, CO₂ and NOₓ were analysed respectively by paramagnetic and specific infrared analysers (ROSEMOUNT NGA 2000). According to EN 303-5 (NF EN 303-5, 2012) standard, concentrations expressed in mg. Nm⁻³ were referred to 10% of O₂ in the exhaust. An Electrical Low Pressure Impactor (ELPI) manufactured by DEKATI Ltd. (Tampere, Finland) was used to collect particles from 7 nm to 10 µm into 12 size fractions. Particle number and concentrations calculated accounts for this particularity using 1 g. cm⁻³ of density value (Marjamäki et al., 2000). The total mass fraction of Total Suspended Particles (TSP) was measured by gravimetry according to DIN CERTCO certification rules (DIN CERTCO, 2008).
### 3.2.2.2 Results and discussion

#### Investigation of thermal degradation of grape marc by TGA

Experiments were performed with each part of the grape marc (skin, seed and stalk) under air and pure nitrogen from ambient temperature to 950°C. Figure 3.7 reports TGA and DTG curves for the different parts of the grape marc for Sylvaner variety. The DTG analysis shows that each constituent reacts at different temperatures. The devolatilisation steps occur from 150°C to 400°C. The different peaks observed correspond to the degradation of Hemicellulose, Cellulose and Lignin, respectively. The char combustion step (from 400°C to 600°C) starts earlier and is faster for stalks (0.1 %/s at 401°C) than for the other parts. For grape skins and seeds, the oxidation peaks are about 0.06 %/s at 460 and 500°C respectively.

<figure><img src="image_2.png" /><figcaption>Figure 3.7: TG (Weight, %) and DTG (Deriv. Weight, %/s) for the different parts of Sylvaner grape marc (skin, seed and stalk); Heating rate: 5°C/mn under air. (Valente et al. 2015).</figcaption></figure>

An Extended Independent Parallel Reaction (EIPR) model was proposed for the thermal decomposition of grape marc using its lignocellulosic repre-
sentation under an oxidative atmosphere. The overall mass conversion rate during thermal degradation is expressed according to a first-order reaction system. This deterministic model compares the overall mass loss rates obtained from the experiments and from the model. The assumption and the equations of the model are presented in detail in Valente et al. (2015) and Brillard et al. (2015).

$$ \frac{dm(t)}{dt} = \sum_{i=H, C, L} \left\{ k_i(T(t)) \left( m_i(0) - \frac{1}{\tau_{voli}} m_{voli}^e(t) \right) + k_{comb}(T(t)) \left( \frac{\tau_{char,i}}{\tau_{voli}} m_{voli}^e(t) - m_{char,i}^e(t) \right) P_{O_2} \right\} $$

A coupled system of six ordinary differential equations (ODE) is defined and has to be solved. The overall mass rate is then computed as: $m_i(0)$ is the mass of the volatiles and char contained in the constituent i at t=0, $m_{vol,i}^e(t)$ is the mass of volatiles emitted by the constituent i of the sample at time t, $m_{char,i}^e(t)$ represents the mass of char consumed at t among that produced from the constituent i of the sample (i=H, C, L). $\tau_{char,i}$ and $\tau_{vol,i}$ are respectively the volatiles and char mass fractions in constituent i. The kinetic parameters $k_i(T)$ and $k_{comb}(T)$ are supposed to obey Arrhenius equations:

$$ k_i(T) = A_i \exp\left(-\frac{Ea_i}{RT}\right) \quad \text{and} \quad k_{comb}(T) = A_{comb} \exp\left(-\frac{Ea_{comb}}{RT}\right) $$

The numerical resolution of the system of ODEs was done using the routine ode of the SCILAB software and the best kinetic constants were determined using the routine datafit. Table 3.6 presents the results obtained for the different parts of the grape marc at the heating rate of 5°C/min. The activation energy obtained for char combustion is consistent with literature data (see Valente et al. 2015) and is higher to these obtained for the thermal degradation of cellulose, hemicellulose and lignin.
<table><caption>Table 3.6: Kinetic parameters extracted for grape skins, stalks and seeds for Sylvaner variety (Brillard *et al.* 2015).</caption><thead><tr><th>Skins</th><th>m<sub>i</sub>(0) (mg)</th><th>τ<sub>vol,i</sub></th><th>A (s<sup>-1</sup>)</th><th>Ea (J/mol)</th></tr></thead><tbody><tr><td>Hemicellulose</td><td>0.5000</td><td>0.6</td><td>25 000</td><td>70 000</td></tr><tr><td>Cellulose</td><td>2.0000</td><td>0.7</td><td>69 000</td><td>83 000</td></tr><tr><td>Lignin</td><td>2.2695</td><td>0.6</td><td>39</td><td>63 000</td></tr><tr><td>Combustion</td><td></td><td></td><td>6 000 000</td><td>190 000</td></tr></tbody></table>

<table><thead><tr><th>Stalks</th><th>m<sub>i</sub>(0) (mg)</th><th>τ<sub>vol,i</sub></th><th>A (s<sup>-1</sup>)</th><th>Ea (J/mol)</th></tr></thead><tbody><tr><td>Hemicellulose</td><td>0.4500</td><td>0.7</td><td>25 000</td><td>73 000</td></tr><tr><td>Cellulose</td><td>3.6000</td><td>0.9</td><td>40 000</td><td>75 000</td></tr><tr><td>Lignin</td><td>7.2094</td><td>0.3</td><td>40</td><td>65 000</td></tr><tr><td>Combustion</td><td></td><td></td><td>5 000 000</td><td>172 000</td></tr></tbody></table>

<table><thead><tr><th>Seeds</th><th>m<sub>i</sub>(0) (mg)</th><th>τ<sub>vol,i</sub></th><th>A (s<sup>-1</sup>)</th><th>Ea (J/mol)</th></tr></thead><tbody><tr><td>Hemicellulose</td><td>0.5000</td><td>0.6</td><td>25 000</td><td>70 000</td></tr><tr><td>Cellulose</td><td>3.5000</td><td>0.8</td><td>69 000</td><td>85 000</td></tr><tr><td>Lignin</td><td>16.0432</td><td>0.5</td><td>39</td><td>61 000</td></tr><tr><td>Combustion</td><td></td><td></td><td>1 000 000</td><td>190 000</td></tr></tbody></table>

As shown in Figure 3.8 for grape skin, a good agreement between calculated and experimental data is obtained with this set of kinetic parameter.
<figure><img src="image_3.png" /><figcaption>Figure 3.8: Grape skin DTG (Deriv. Weight, mg/s); 5°C/min. Experimental (symbol) and simulated (line) curves (Brillard et al. 2015).</figcaption></figure>

### 3.2.2.3 Pollutants emissions for the combustion tests in a multi-fuel-boiler

#### Gaseous emissions and total suspended particles (TSP) concentrations

Exhaust emissions were recorded with the REKA multi-fuels boiler to estimate the impact of an addition of grape marc in the blended fuels. Figure 3.9 gives the average values of gas concentrations and TSP in the flue gas at steady state. The values obtained with conventional fuels such as miscanthus, beech chips and pellets are also presented for comparison. Limit values for the standard EN 303-5 are reported. CO concentrations are of the same order of magnitude than those described in literature for conventional dry fuels as pellets, miscanthus and beech chips (Verma et al., 2011) and close to standard values. The combustion process is not significantly modified with an addition of grape marc since CO emission in the exhaust are still very low for blend ratio (%wt) miscanthus/ grape ranging from 75/25 to 67/33. For higher proportion of grape marc (50/50), CO concentration in the exhaust is higher and consequently the thermal per-
formance of the boiler is affected due to the high relative humidity of the sample. Moreover, as shown in Figure 3.9, CO concentration is higher for the pellets/grape mixture than for the miscanthus/grape mixture whatever the mass ratio considered. This may be explained by how the grape marc is distributed in the biomass. Since miscanthus is constituted of fine particles, the grape marc is more homogeneously mixed in the miscanthus/grape mixture than in the pellets/grape mixture. The shape of the natural bio-masses used acts strongly on combustion efficiency. The reactive surface in the miscanthus blends may be higher than for pellet blends. This enhances the combustion. Excepted for the DIN CERTCO pellets, mean values of NOx are higher than standards. This result may be linked to the relatively high nitrogen content in the fuels.

<figure><img src="image_4.png" /><figcaption>Figure 3.9: Concentrations of CO, NOx and TSP compared to standards.</figcaption></figure>

The total mass concentration of TSP is presented at 10% O₂ in Figure 3.9. TSP is ranging from 20 to 40 mg Nm⁻³ for most of the fuel tested excepted for grape marc with 27% of humidity and beech chips with 220 and 150 mg Nm⁻³, respectively. For conventional biomass such as pellets and miscan-
thus but also for blends with a proportion of marc equal to 33 % by weight,
TSP are close to the limit values of the actual standard EN 303-5. One can
conclude that the presence of 33% of grape marc in the blends has no sig-
nificant influence on dust emission. However for higher content of grape
marc in the blends, the emission of dust and CO will be surely higher.

Fine and ultrafine particle emissions

Figure 3.10 gives the total number PM₁₀ size distributions for raw and
blended miscanthus samples. Quite similar distributions were also obtained
for raw and blended pellets samples. The aerosols emitted during the com-
bustion process of these samples primarily consisted of fine submicron
particles with a nucleation mode dominating. The number distribution for
raw pellets and miscanthus are centered between 0.12 and 0.2 µm. These
distributions are very close to data found in literature during combustion of
various woody fuels and biomasses as energy crops (Dorge et al. 2011;
Johansson et al. 2004).

<figure><img src="image_5.png" /><figcaption>Figure 3.10: Influence of grape marc proportion to the number size distribution of particles emitted during the combustion of Miscanthus (Valente et al. 2014).</figcaption></figure>

Addition of grape marc in miscanthus slightly modifies the number size
distribution as described in Figure 3.10. This distribution is moved toward
bigger particles. However, particles with diameters in the range 0.1 to 1 µm still dominate. The fraction PM<sub>2.5-10</sub> is totally negligible. Particle matters (PM<sub>0.1</sub> to PM<sub>2.5</sub>) recorded during tests show that the main particles emitted are ultrafine particles (PM<sub>0.1</sub> and PM<sub>0.1-1</sub>). PM<sub>1</sub> represents more than 99% of the total number of particles for all samples. The fraction PM<sub>1-2.5</sub> is below 0.1% of the total number of particle. From the number size distribution presented in Figure 3.10, the total PM<sub>2.5</sub> number concentration is calculated. It varies from 1.0 10<sup>13</sup> particles per m<sup>-3</sup> to 1.5 10<sup>13</sup> particles per Nm<sup>-3</sup> related to 10% of O<sub>2</sub> in the flue gas for raw pellets and miscanthus, respectively. Considering a relative standard deviation close to 20%, the total PM<sub>2.5</sub> number concentration is not significantly impacted by the addition of grape marc in the miscanthus blends.

### 3.2.2.4 Conclusion of subsection 3.2.2

The use of grape marc for energy recovery could be relevant for the wine makers as it is renewable and has an almost neutral CO<sub>2</sub> balance. This study is the first demonstrating the feasibility of grape marc combustion in a small domestic scale boiler (40kW).

The first part of the work was devoted to the investigation of the thermal decomposition of the grape marc by TGA. The main theoretical contribution and input was to characterise accurately this biomass (Valente *et al.* 2015) and to develop a model simulating its decomposition including the reaction of char combustion (Brillard *et al.* 2015). Corresponding kinetic parameters were proposed for each part of the grape marc.

The investigation of grape marc combustion in a multi-fuel boiler was then performed. Concerning pollutant emissions, this study pointed out the influence of the humidity of raw wine residues on the thermal process and consequently on the emission of gaseous pollutants and particulate matter. The moisture content of raw grape marc (between 65-80%) is an issue for the combustion process since it leads to high concentrations of carbon monoxide in the fumes as well as volatile organic compounds and particles in the exhaust line. Hence, only blended fuels Miscanthus/Grape marc and Pellets/Grape marc are relevant for combustion. Using such a blended
fuels, the emission of gas and particulate matter are more or less similar to
these observed for other biomass resources or co-products. Such a result
indicates that the use of grape marc in a multi-fuel system is fully relevant
for energy recovery.

Further studies of emissions factors of grape marc burning regarding air
excesses, optimized fuel appearance, or perhaps a pelleting process could
lead to an optimisation of the combustion process and therefore a new
source of energy in the Alsace region but also throughout the world in
vineyard areas.

3.2.3 Biomass conversion technologies

Christian Bidart, Russell McKenna and Wolf Fichtner

French-German Institute for Environmental Research (DFIU), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany.

The three uses of biomass for energy utilisation are basically heating, fuels and electricity. These are useful forms of energy; they can, consequently, be distributed, traded and commercialised. Being produced on a large scale and traded at a relatively low price, they are normally categorised as commodities. The generation of any of these energy carriers demands generation processes which transform the primary energy (i.e. biomass, crude oil, natural gas, etc.) into secondary energy (i.e. heat, fuels or electricity).

Biomass can be classified into lignocellulosic biomass and biochemical biomass. Although these terms are not standard and differences can be found in definitions in the literature, they can be employed to denominate, for the former, biomass with a high lignin content, and for the latter, bio- mass that can undergo reaction by the action of enzymes, thus being con- verted by microorganisms. As Figure 3.11 shows, lignocellulosic biomass can be converted by processes such as combustion, gasification or pyroly- sis. In gasification, for instance, the main product is a mixture of gases that can be utilised either as a gaseous fuel to be burnt in a gas turbine or engine