## 1 Introduction  
Biomass has been considered as one of the most important primary and renewable energy resources for the production of heat, electricity, hydrogen, chemicals, and liquid fuels due to its carbon-neutral renewable and abundant quantity. Furthermore, the energy production from biomass is advantageous to other renewable sources such as wind energy, hydropower, solar energy, etc. [1]. Gasification is a partial oxidation process at high temperatures, which can convert organic or fossil fuel-based carbonaceous materials into gaseous fuel including mainly H\({}_{2}\), CO, CO\({}_{2}\), and CH\({}_{4}\). In the presence of steam, the product gas has been generated with 30-60% of H\({}_{2}\) content and a calorific value of 10-18 MJ/Nm\({}^{3}\)[2, 3]. Thus, steam gasification of biomass is an effective and efficient technology for sustainable hydrogen production without a carbon footprint [4]. Generally, three reactor configurations can be used for biomass gasification, i.e., the entrained flow, fixed bed, and fluidized bed reactors. The fluidized bed gasifiers show advantages for biomass conversion due to the perfect contact between gas and solid, increasing heat and mass transfer characteristics, and improving temperature control. An experimental investigation of gasification of torrefied woody biomass was conducted by [PERSON] et al. [5] in a pressurized fluidized bed, evaluating the effect of pressure and torrefaction level on the yield and composition of the products. The authors found that the pressure could result in a decline in CO and H\({}_{2}\) levels, whereas CO\({}_{2}\) and CH\({}_{4}\) yield increase. [PERSON] et al. [6] observed that the cold gasification efficiency of torrefied bamboo rose by 88% compared to raw bamboo. Furthermore, char gasification reactions are one of the most important reactions in biomass gasification. Many kinetic studies have been carried out through the thermogravimetric analysis instrument (TGA) to determine the kinetic parameters of char gasification [7; 8; 9; 10; 11; 12]. Some reaction kinetic models have been proposed for char gasification. They could be categorized into two groups such as theoretical and semiempirical models. Four conversion models have been investigated for char gasification reactions, i.e., volumetric model, shrinking core model, random pore model, and Johnson model [9; 13]. Additionally, the Langmuir-Hinshelwood reaction model has been used extensively as a kinetic model for heterogeneous reactions, particularly char gasification with steam and carbon dioxide [14]. Along with the computational progress, the numerical simulation could help bypass a long planning and construction process of experimental studies, provide low-cost methods for the proper design and project realization. Mathematical models are developed to describe the physical and chemical phenomena occurring inside the gasifier and to understand the effect of various operating and design parameters on the process performance. The model also is used to predict the behavior of gasification at off-design conditions and the optimum operating parameters [15]. The main simulation methods can be categorized as the thermal equilibrium model, kinetic model, numerical model, and artificial neural network [15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26; 27]. The thermodynamic equilibrium model is simple and provides the preliminary comparison and assessment of the gasification process [28]. There are three equilibrium modeling approaches, such as the restricted equilibrium model, empirical correlation-based model, and the model based on a combination of hydrodynamic and kinetic aspects [29]. The Aspen Plus process simulator, which is developed to facilitate physical, chemical, and biological calculations, has been used commonly in various studies to simulate coal and biomass gasification. Due to the complex nature of tar, most of the studies in the literature have not considered tar calculations.