EQUILIBRIUM MODELING OF HEMP HURD GASIFICATION Simone Pedrazzi 1 , Nicolò Morselli 1 , Marco Puglia 1 , Filippo Ottani 1 , Massimiliano Parenti 1 1 BEELab (Bio energy efficiency laboratory), Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, Via Vivarelli 10/1 – 41125 Modena, Italy. Abstract: The aim of this work is modeling a gasification process where a non-conventional biomass is used as fuel: hemp hurd residues. An equilibrium model of the gasification reaction was implemented in the Phyton TM software environment. Syngas composition, syngas higher heating value, tar production and gasification cold gas efficiency were evaluated at different value of biomass moisture starting from biomass ultimate analysis and reaction equivalence ratio (ER) value. The model is able to predict char and tar production as function of biomass composition, moisture and ER. A comparison with experimental data obtained from hemp hurd gasification was done to validate equilibrium model results. Gasification tests were performed using a low capacity lab- scale gasification reactor designed to use about 1 kg per hour of dry biomass fuel. Results show small errors between model results and experimental result. Several simulations were performed to assess the gasification dependency on selected boundary conditions like biomass moisture and ER of the gasifier. Keywords: bioenergy, gasification, hemp, residues, syngas. 1. Introduction Hemp global sector is a fast growing market, it is projected to grow from USD 4.6 billion in 2019 to USD 26.6 billion by 2025 thanks to the large variety of possible applications hemp is involved into [1,2]. Textile industries as well as sustainable building companies are increasing the demand for hemp fiber [3]. The main by-products of hemp fiber production is hemp hurd: a lignocellulosic residues fragmented in small flakes with a variable length of 1-5 cm. The amount of this biomass is not negligible: literature reports an annual productivity in cold climate conditions of about 10 ton per hectare of dry matter including flowers and seeds that represent a small fraction of the whole plant. Hurd is commonly used as filler for construction material like tiles of bricks and it has a marker value of about 200 €/ton [3]. An alternative way to valorize hemp hurd is the utilization as fuel for combustion biomass facility [3]. This work investigates the use of hemp hurd as fuel for gasification reactor. Gasification is a thermo-chemical reaction that converts a solid or liquid fuel into a gaseous fuel (syngas) using a gasifying agent and heat in sub-stoichiometric environment [4]. Gasification has several advantages compared to other thermochemical processes like pyrolysis and combustion. First, gasification is the most efficient way to convert biomass to electrical energy [5,6], second, it covers a wide range of electrical power output requirement (from 1 kW to 1 MW) [4,6]. Gasification uses not-conventional biomass fuels thanks to some peculiar reactor designs and architectures [7-16]. Furthermore, commercial gasification systems not only convert solid biomass (usually wood chips) into electrical energy and heat but also produce biochar. Biochar consists of charcoal that is disposed from gasification and pyrolysis reactor. It is a highly recalcitrant form of carbon, for this reason its use as soil amendment as also the effect to convert the soil into an effective carbon sink [17,18]. The main problem that afflicts gasification systems is the uncontrolled tar production. Tar is mix of polycyclic aromatic hydrocarbons (PAHs) and it is a pollutant of the syngas stream because it can be dangerous for mechanical components of the gasification power plants. High is the tar amount high is the filtering effort needed to purify the syngas, however a low tar production below 1 g/Nm 3 is difficult to reach with biomass residues because of high moisture, low higher heating content and high ash of the residue [4]. In this paper an equilibrium model based on a general biomass gasification reaction was implemented in Phyton TM software environment. The model was validated using experimental data obtained from hemp hurd gasification test performed with a lab-scale fixed bed gasifier. Furthermore, several simulations were done considering different gasification conditions varying biomass moisture and gasifier equivalence ratio. 2. Material and methods 2.1. Biomass characterization Biomass moisture content was calculated according to UNI EN ISO 18134-1. Chemical composition of the organic part of a dried biomass sample were performed using the FLASH 2000 Organic Elemental CHNS-O Analyzer [19]. Biomass ash content was determined weighing a died sample before and after 8 hours muffle furnace calcination at 600 °C. Biomass higher heating value HHV [kJ/kg] were estimated through the Channiwala and Parikh correlation (Eq.1) [20] and biomass lower heating value LHV [kJ/kg] was determined using Eq. 2 [4].  = 349.1 + 1178.3 + 100.5 − 103.4 − 15.1 − 21.1 (1)  =  − ℎ  [( 9 20 )+(  100 )] (2) where C, H, S, O, N and ASH [% wt.] are respectively the mass percentages of carbon, hydrogen, sulfur, oxygen, nitrogen and ashes of the biomass calculated on a dry basis. hg [kJ/kg] is the latent heat of vaporization of water at ambient pressure and M [% wt.] is the moisture content of the biomass. Table I resumes the results of the previous analysis and Figure 1 show a hemp hurd biomass sample.