The article presents a solution for solving the problems of eco-efficient combustion of pelletized or chopped and dried agricultural and forest residual biomass, using the TopLit UpDraft (TLUD) gasification process. By using this solution, thermal energy is produced, and about 10�20% residual charcoal, not transformed into gas, called biochar, too. Biochar is a good amendment for agricultural soils and reduces the concentration of CO2 in the environment by capturing carbon in the soil for long periods. Biochar acts in the soil like a sponge that can absorb up to five times its own weight; it stores water and nutrients and allows microorganisms to settle inside its pores. A bench for testing combustion in TLUD gasifiers, developed in is equipped with a data acquisition program, designed in LabView, with a user-friendly our laboratory, is presented; it graphical interface that displays all acquired parameters and the related graphs in real time for various operating modes and for various types of biomass. The production temperature and the amount of air in the gasifier are the main factors that impinge on the physico-chemical properties of the biochar. The data acquired from two combustion tests carried out with a primary air / secondary air ratio of 1/3 and 1/2, respectively, are presented, from which it turns out that that gasification (in our case, gasification of pellets) with lower speed results in a larger amount of biochar, hence a more eco-efficient combustion, with significant benefits for the environment.

Biomass stores solar energy that man can convert into electricity, fuel or heat, resulting in cheap, clean energy with a negative carbon balance. The use of biomass from agricultural secondary production as a potential energy source can improve soil quality and reduce greenhouse gas emissions in a complementary, non-competing way. The paper presents a piece of combustion equipment performing the burning process by biomass gasification on the TLUD (Top-Lit UpDraft) principle, from which hot air and biochar are obtained. The main function of this type of gas generator set on the TLUD principle is to generate a syngas flame which can be used as a heat source. The biochar obtained as a by-product is a sterile, active carbon with a large adsorption surface which is used as a soil amendment in environments with limited capacity for carbon sequestration and in soils depleted of resources. Gasification on the TLUD principle occurs when the biomass layer is introduced into the reactor and rests on a grate through which the air flow for gasification passes from bottom to top. Priming of the gasification process is done by igniting the upper layer of biomass in the reactor. The oxidation front continuously descends consuming the biomass in the reactor. Due to the heat radiated by the oxidation front the biomass is heated, dried, and then it enters a fast pyrolysis process from which volatiles emerge and unconverted carbon remains there. When the combustion front reached the grate, all the volatiles in the biomass were gasified and some of the carbon fixed was reduced; about 10 - 20% of the initial mass in the form of sterile charcoal, called biochar, remains on the grill. Compared to wood direct combustion or gasification combustion processes, the TLUD gasification process is characterized by very low values of the superficial velocity of gas passing through the pyrolysis front. The slow process maintains superficial velocity of the generator gas produced at very low values, which ensures reduced carrying away of free ash of approximate size below PM2.5 and maxim values of 5 mg/MJbm when leaving the burner; such values are well below the target imposed in the EU in 2015 for biomass combustion processes, which is below 25 mg/MJ. The result of monitoring the gasification process can be used to automate and optimize the TLUD process in order to achieve green energy, for carbon sequestration in the obtained biochar and to reduce greenhouse gas emissions, thus contributing to achieving efficient protection of the environment and to ensuring sustainable energy development

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The recovery of vegetal waste for energy purposes is one of the ways to increase the amount of energy obtained from renewable sources. The Top-Lit Updraft (TLUD) gasification and combustion process is recognized as the least polluting of all other combustion processes, resulting in a sterile charcoal called biochar, which can be used as an amendment in agricultural soils. The purpose of this research was to determine the influence of excess air in the combustion area compared to the (theoretical) calculated requirement for a TLUD energy module. Most scientific publications on this topic recommend primary/secondary air flow rate ratios of 1/3 or 1/4. In this study, the two recommended ratios were tested, and it was found that better energy results correspond to the ratio of 1/3. For this 1/3 ratio, the investigations continued in order to optimize the combustion process. The results achieved demonstrate that the excess combustion air flow of 30% improves the performance of the energy module due to the increase in oxygen supply and the increase in air speed in the combustion area of the syngas resulting from gasification. Increasing the excess combustion air flow rate by +50% had the effect of lowering the temperature in the flame due to the cooling of the combustion gases caused by a too high rate of excess cold air flow.

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