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Four representative pretreatment methods, water washing (WW), acid washing (AW), dilute acid hydrolysis (DH), and microwave assisted organosolv pretreatment (MOP), were adopted to alter eucalyptus ...

In the present era of continually increasing energy demand, Europe faces many challenges, such as high and unstable energy prices, growing global energy demand, increasing threat of climate change, sluggish progress within energy efficiency and issues related to increasing demand for the use of renewable energy sources. It is desirable to seek opportunities to use energy consumed most reasonably, thus ensuring continuous improvement of energy efficiency in the industry. The scope of the research includes reviewing studies in this matter and analysing the most beneficial solutions for the plant. The work aims to assess possible undertakings to modernise the energy management of an industrial plant on the example of Bulten Poland S.A. rationally and profitably for the plant. The work contains an analysis of the profitability of the potentially most beneficial solutions in terms of improving the energy efficiency of the plant. Mentioned in the article solutions, aiming increasing energy efficiency, helped become the plant independent within heating up facilities. Total heat recovery potential in amount of 18 965 GJ is motivation for further activities. This is a great opportunity to reduce significantly carbon footprint (replacing lightening into LED technology reduced CO2 by 206.3 Mg/year) and be more competitive on the market by reducing costs of product.

In recent years solar-thermal methods of waste biomass conversion are promptly gaining on attention. For researchers working in areas that suffer from lack of natural solar power, the choice of proper solar simulator for the study is crucial. Solar simulator consist of artificial light source enclosed in proper housing with optical and cooling system, powered by dedicated power supply. Solar simulators are not only granting independence from external conditions, yet provide possibility of research expand due to tuneable output power and emissive spectrum. Over the years, solar simulators were powered by different types of lamps. Throughout the history, the solar simulators were used mainly in photovoltaic and space research, crystal growth industry, and the material testing. For mentioned purposes, the total thermal output power of simulator was playing secondary role in comparison to urgent need of spectral match, irradiance distribution and beam uniformity with terrestrial or extra-terrestrial sunlight. For thermal applications, solar simulators are facing the challenge of providing high output power, described by high radiant heat flux and high heat flux density over the specified target area. In presented paper the comparison of xenon arc, metal halide lams and tungsten halogen for thermal applications has been presented with emphasis on available thermal power, spectral match with natural sunlight and operational issues. The course of decision taken during the selection of artificial light source for construction of laboratory-scale solar pyrolytic reactor is proposed.

The thermal decomposition kinetics of two energy crops Miscanthus x giganteus and Sida hermaphrodita biomass materials harvested from a phytoremediation study in Polish and Germany have been studied, assuming a three-pseudocomponent model. The kinetic parameters extracted from the study are realistic and within reasonable ranges. The activation energies are within 20 - 103.55 kJ/mol. The reaction orders are within 1.01-1.99. The result shows that the energy crops from the Polish site exhibited higher conversion rates than the samples from Germany. A negative effect of the ash content on the biomass reactivity is observed.

Increasing problems associated with sewage sludge disposal are observed nowadays. As the thermal conversion of sewage sludge (combustion, co-combustion, gasification and pyrolysis) appears to be the most promising alternative for its management, the solid residues left after gasification were examined. The present study evaluates the potential of this waste as an alternative phosphorus source in the context of phosphorus recovery. The obtained solid gasification residues were characterised (chemical and phase composition, thermal properties, surface properties and technological parameters used for phosphorus raw materials) and compared to commercial phosphate raw materials. It was revealed that gasification residue is a valuable source of phosphorus and microelements, comparable to sewage sludge ash (SSA) considered nowadays as secondary phosphorus raw materials. Chemical properties as well as technological parameters characteristic for natural phosphate ores are different. Solid gasification residue was leached with mineral acids (phosphoric and nitric) according to the patented method of phosphorus recovery - PolFerAsh, developed by Cracow University of Technology. It was revealed that phosphorus can be selectively leached from solid gasification residue with high efficiency (73-82%); moreover, most of the iron and heavy metals stay in the solid phase due to the low concentration of acids and proper solid to liquid phase ratio. The obtained leachates are valuable products that can be considered for the production of fertilisers. Combining the gasification process with nutrient recovery provides the opportunity for more environmentally efficient technologies driven by sustainable development rules.

Thermal Analysis determines a set of methods for the study of the selected physical properties of the substance under the influence of temperature or atmosphere. Thermogravimetric (TG) analysis is very useful for studying the kinetics of gasification processes. However, by itself TG does not allow the direct identification of the gases released from the sample during the thermal treatment. For this purpose, coupling TG to a spectroscopic interrogation method, such as Fourier-Transform-Infrared (FT-IR) spectroscopy, is an excellent solution. The objective of this paper is to ascertain the usefulness and limitations of TG-FTIR technique in the study of biomass gasification and to determine gasification product evolution patterns and yields for heavy metal contaminated (HMC) samples of Miscanthu s x giganteus , Sida hermaphrodita , Spartina pectinata and Panicum virgatum . In experiments reported in this paper, biomass samples were heated at 10° C min −1 in a nitrogen environment and the volatile products were swept immediately into a cooler gas cell, which minimized secondary reactions. Process products were quantitatively analysed by gas-phase Fourier transform infrared (FT-IR) spectroscopy. This gas analysis combined with weight loss measurements of the heated material ensured generally good mass-balance closure. The paper discusses the techniques employed to identify the evolved products and presents the product evolution patterns and yields.

A fixed-bed based solar pyrolysis of three waste biomass types: waste wood (WW), waste straw (WS), and sewage sludge (SS) was performed with emphasis on heating behaviour description, products yields, and quality. Laboratory solar pyrolysis reactor setup consists of a copper block indirectly heated by research-grade 1.6 kW xenon lamp radiation. Actual heating rates observed for 90, 95 and 100% xenon lamp power are 4.51, 5.32, and 5.49 K/min for WS; 5.10, 5.19, and 5.37 K/min for WW; and 3.95, 4.48, and 5.25 K/min for SS, respectively. Solar pyrolysis product yields (bio-oil, gas, char) were 51.68, 9.53, and 38.79 wt% for SS, 69.23, 9.18, and 21.59 wt% for WW, 62.30, 10.64, and 27.06 wt% for WS, denoted for the specific heating rates in ascending order. The highest quality bio-oil was obtained from WW pyrolysis with the lowest oxygen to carbon fraction and higher heating value (HHV) of 21.99 MJ/kg. Obtained chars, especially after solar pyrolysis of lignocellulosic biomass, presented HHV of 27.09 MJ/kg and 22.02 MJ/kg for WW and WS respectively, showed significant potential for renewable solid fuel. The increase of the lamp power, and long process time, caused degradation of porous structures within the biomass, where among the samples the highest specific surface area (BET) was denoted for WW samples at 5.2 K/min with 145.09 m2/g. Correlation between model-free kinetic predictions and gaseous species evolution was found, proving the value of apparent isoconversional activation energy profiles in describing actual solar pyrolysis gas compound formation at the laboratory scale.

Biomass is one of the major sources of energy that is estimated to contribute between 10% and 14% of the world’s energy supply. Over the past several years, many societies have established policy targets to increase their production of renewable energy from biomass. The thermo-chemical utilization of biomass includes 4 technologies: the most popular combustion and co-firing, and unconventional: pyrolysis and gasification. Gasification is considered to be the perspective technology because has many advantages in comparison to traditional process of combustion: (1) limited emission of the SO2, NOx, oxides of the heavy metals and no risk of the dioxins and furans emission due to reducing atmosphere in the gasification reactor, (2) volume of the gasification gas is smaller in comparison to flue gases from combustion due to the reducing atmosphere, (3) gasification process produce gas which is potential gaseous fuel in power engineering (engines, gas turbines and boilers) and chemistry. Unfortunately, composition of the gasification gas is always described as a variable. Moreover, it depends on the conditions of the process and quality of the base fuel. For this reason, the use of gasification gas can’t be very easy. For this reason, the knowledge of the basic properties of the gas is very important. Laminar burning velocity is assumed as an important quantity for in the process of the design equipment for the gas utilization. The numerical and experimental results of the laminar burning velocity of sewage sludge gasification gases were presented. Experimental Bunsen burner method was used. Cosilab 3© software for numerical analysis was used. GRI-Mech 3.0 mechanism of gas oxidation was implemented. As a result of the work, the set of the parameters where the sewage sludge gasification gas combustion process is stable with effective heat release, were presented.

Thermal conversion (combustion, co-combustion, gasification and pyrolysis) appears to be the most promising alternative for sewage sludge management in the future. Nevertheless, safe and ecological usage of sewage sludge as a fuel requires information about their contamination. The aim of this paper is to present the photoacoustic spectroscopy (PAS) as a good method for contamination assessments of dried sewage sludge. Two types of granular sewage sludge: Sewage sludge 1 (SS1) taken from Polish wastewater treatment plant operating in the mechanical-biological system and sewage sludge 2 (SS2) taken from mechanical-biological-chemical wastewater treatment plant with phosphorus precipitation were analysed. The spectrophotometer FTIR Nicolet 6700 equipped with photoacoustic cell (Model 300, MTEC, USA) was used. The comparison with the most popular analytical methods (GC-MS) was also done. The results of PAS studies confirm the difference between the SS1 and SS2 which is in agreement with the GC-MS analysis. Higher absorbance was observed at each wavelength characteristics for the oscillator of chemical moieties for the SS1 with respect to the SS2.

Biomass obtained from phytoremediation energy crops Miscanthus x giganteus and Sida hermaphrodita planted on different soils contaminated with heavy metals was thermogravimetrically studied and kinetically analyzed, assuming a three-pseudocomponent model. The results showed that Miscanthus x giganteus was able to uptake more heavy metals than Sida hermaphrodita. Soil influences on the fuel and thermal properties the crops were observed. The ash content of the biomass exhibited a negative effect on its reactivity. The extracted kinetic data are realistic and within reasonable ranges. The activation energies are within 20–103.55 kJ mol−1. The reaction orders are within 1.01–1.99.

The Sewage Sludge Directive 86/278/EEC was adopted about 30 years ago with a view to encourage sewage sludge reuse in agriculture and to regulate its use. Meanwhile, some EU Member States have adopted stricter standards and management practices than those specified in the Directive. In particular, the majority of Member States has introduced more stringent standards for sludge quality, including stricter limits for most potentially toxic elements, organic contaminants and other elements. In general, untreated sludge is no longer applied and in several Member States it is prohibited. In some cases, stringent standards have resulted in an effective ban on use of sludge in agriculture. Moreover, the implementation of the Urban Wastewater Treatment Directive 91/271/EC should increase EU production of sewage sludge, thus enhancing problems related to sustainable sewage sludge management. Additionally, European legislation prohibits the landfill and water deposits of sewage sludge. The latest trends in the field of sludge management, ie combustion, pyrolysis, gasification and co-combustion, have generated significant scientific interest. This trend is specially strong visible in “new” EU Members countries which have to introduce strong EU Directive in their low system. Here the review the state of knowledge and technology in thermal methods for the utilization of municipal sewage sludge to obtain useful forms of energy such as pyrolysis, gasification, combustion, and co-combustion taking into consideration Poland situation is presented.

Nitrogen oxides can be formed in various combustion systems. Strategies for the control of NOx emissions in hard coal boilers include the primary (during the combustion) and secondary measures (after combustion). Reburning is the one of the most attractive techniques for reducing NOx emissions. In the last several years, reburning technology has been widely studied but almost only in power engineering big load boilers. Nevertheless, NOx emission is an issue that needs to be considered for small capacity boilers as nitrogen oxides resulting from the combustion of any fossil fuels contribute to the formation of acid rain and photochemical smog, which are significant causes of air pollution. Poland is among the largest coal producing country in Europe. Due to this fact, coal fired boilers are very popular in power engineering and also in the municipal sector. Simultaneously, Poland is characterized by the lack of sewage sludge thermal treatment installation. Gasification is considered as a one of the most perspective method of thermal utilization any carbon-containing material. Syngas, which is the main product of gasification, can be used as a supplemental fuel to reduce the consumption of main fuel in boilers, and it has the potential to reduce NOx emissions. The paper proposes to link those two Polish features so the aim of the work is an experimental investigation of the reburning process of sewage sludge gasification gas in a small capacity domestic coal-fired boiler. The results obtained show how the addition of the reburning fuel influences on NOx reduction efficiency

Dried sewage sludge and solid gasification byproducts (ash) were evaluated in terms of their application to the removal of phenol from aqueous solutions by adsorption. The adsorption was carried out under static conditions at 20°C. The following properties of the tested unconventional adsorbent materials were determined: susceptibility of phenol to adsorption, the equilibration time and the adsorption isotherms based on the Langmuir and Freundlich equations. Additionally, leaching of primary inorganic and organic substances from adsorption materials was studied including the determination of a toxic effect of the solution (without the addition of phenol). It was found that the gasification ash adsorbs phenol better than dried sewage sludge. The results obtained for the adsorption of phenol on the ash were described by both isotherms with great accuracy. In the case of dried sludge, the Freundlich isotherm made it possible to obtain a better correlation coefficient. It was observed that organic and...

Municipal wastewater treatment results in the production of large quantities of sewage sludge, which requires proper environmentally accepted management before final disposal. Sewage sludge is a by-product of current wastewater treatment technologies. Sewage sludge disposal depends on the sludge treatment methods used in the wastewater treatment plant (anaerobic or aerobic digestion, drying, etc.). Taking into consideration presented given this information, a study concerning the effects of wastewater treatment processes and sewage sludge drying method on the sewage sludge gasification gas parameters was performed. Gasification is a prospective alternative method of sludge thermal treatment. For the purpose of experimental investigations, a laboratory fixed bed gasifier installation was designed and built. Two types of sewage sludge feedstock, SS1 and SS2, were analyzed. Sewage sludge SS1 came from a wastewater treatment plant operating in the mechanical and biological system while sewage sludge SS2 was collected in a mechanical, biological and chemical wastewater treatment plant with simultaneous phosphorus precipitation. The sludge produced at the plants was subject to fermentation and then, after being dehydrated, dried in a cylindrical drier on shelves heated up to 260ºC (sewage sludge SS1) and using hot air at a temperature of 150ºC in a belt drier (sewage SS2). The analysis shows that the sewage sludge properties strongly depend on the wastewater sources and the wastewater treatment processes. The gasification results, presented as a function of the amount of gasification agent, show that the greater oxygen content of SS1 caused a reduction in the reaction temperature. Paradoxically, this effect caused an increase in the quantity of combustible components in the gas. As expected, increasing the air flow rate caused a decrease in the heating value of the gas produced. A higher amount of oxidizer increases the amounts of noncombustible species and the volumetric fraction of nitrogen, thus reducing the heating value of the obtained gas. The higher hydrogen content in SS1 affects the gasification gas composition. As a result, combustible components are the majority of the syngas.

Organic and inorganic contaminants in sewage sludge may cause their presence also in the by-products formed during gasification processes. Thus, this paper presents multidirectional chemical instrumental activation analyses of dried sewage sludge as well as both solid (ash, char coal) and liquid (tar) by-products formed during sewage gasification in a fixed bed reactor which was carried out to assess the extent of that phenomenon. Significant differences were observed in the type of contaminants present in the solid and liquid by-products from the dried sewage sludge gasification. Except for heavy metals, the characteristics of the contaminants in the by-products, irrespective of their form (solid and liquid), were different from those initially determined in the sewage sludge. It has been found that gasification promotes the migration of certain valuable inorganic compounds from sewage sludge into solid by-products which might be recovered. On the other hand, the liquid by-products resulting from sewage sludge gasification require a separate process for their treatment or disposal due to their considerable loading with toxic and hazardous organic compounds (phenols and their derivatives).

In this study, the combustion and pyrolysis processes of three sewage sludge were investigated. The sewage sludge came from three wastewater treatment plants. Proximate and ultimate analyses were performed. The thermal behaviour of studied sewage sludge was investigated by thermogravimetric analysis with mass spectrometry (TGA-MS). The samples were heated from ambient temperature to 800 °C at a constant rate 10 °C/min in air (combustion process) and argon flows (pyrolysis process). The thermal profiles presented in form of TG/DTG curves were comparable for studied sludges. All TG/DTG curves were divided into three stages. The main decomposition of sewage sludge during the combustion process took place in the range 180–580 °C with c.a. 70% mass loss. The pyrolysis process occurred in lower temperature but with less mass loss. The evolved gaseous products (H2, CH4, CO2, H2O) from the decomposition of sewage sludge were identified on-line.

In the paper, a numerical simulation of the co-combustion process of sewage sludge gasifi cation syngas in a hard coal-fi red boiler was done. Two different syngases (SS1 and SS2) were taken in consideration. Additional (reburning) fuel was injected into the combustion chamber, which was modeled as a plug fl ow reactor (PFR). The molar fl ow rates ratio of reburning fuel is assumed to be 5.0%, 7.5%, 10.0%, 12.5% and 15.0% of the whole exhaust. The simulations were conducted for constant pressure equal to 1atm for temperatures range from 600 to 1400 K. It was assumed that a fl ue gases which enters the reburning zone contains 300 ppm of NO and that during combustion only NO is formed without other NOx. Results show that that gas from sewage sludge gasifi cation gives reburning effi ciency of up to 90%. Calculation shows also an optimum value of temperature reburning for gas from sewage sludge gasifi cation which is equal to 1200 K. The type of the sewage sludge has no strong infl uence on the NO reduction.

The use of low-calorific value gases is a way to gaseous fuels supply diversification. LCV gases present an application potential in various technologies e.g. reburning process. The experimental investigation of the reburning process in small scale coal-fired boiler using sewage sludge-derived syngas was carried out. The influence of the LCV gas stream on the nitrogen oxides emission reduction was analyzed. The emission reduction reached almost 30% with 11% gas share in thermal input.

In this investigation, ignition processes of methane (CH 4 > 98%) and propane (C 3 H 8 > 95%) using a high-temperature oxidizer ( T oxi > T ai ) with a varying oxygen concentration ( z O 2 = 0.05 ÷ 0.21 ), applying two types of experimental installations, viz. a constant–volume bomb (CVB) and a co-flow reactor (CFR) were investigated. The influence of the initial temperature of the oxidizer (for methane T oxi = 960 ÷ 1234 K and for propane T oxi = 803 ÷ 1055 K), the equivalence ratio and oxygen concentration in the oxidizer on ignition of gaseous fuels is analyzed and discussed. It is shown that in order to achieve an effective reaction of ignition (taking into account the minimum value of ignition delay time τ ig and maximal value of the increment of temperature Δ T ) the oxidizer temperature need not be maximized. There are optimal values of temperature of the oxidizer (for methane T oxi ≈ 1100 K and for propane T oxi ≈ 950 K) in which the parameters mentioned above reach their extreme values.

This paper presents an investigation of sewage sludge gasification in a fixed bed gasifier. Experiments were conducted on a laboratory scale fixed bed gasifier. In the experiments, two types of dried sewage sludge were tested and their properties were analysed. Parameters such as air ratio λ = 0.12 to 0.27, gasification agent temperature t = 50 to 250 °C and gasification agent composition ( = 0.21 and &gt, 0.21) were found to influence on temperature distribution, syngas Lower Heating Value (LHV) and syngas composition. The results indicate that the syngas LHV was found to decrease with increased air ratio for all analyzed cases: cold and preheated air and cold enriched air. The increase in the percentage of the main combustible components was accompanied by a decrease in the concentration of carbon dioxide. Increasing oxygen concentration increased the temperature, which tended to favor the formation of smaller molecules in the gas mixture. Thus, the enriched air medium produced a gas with a higher LHV. In contrast to conventional gasification, gasification process with gasification agent preheating causes that the flux of heat necessary to support endothermic gasification reactions is producing more effective. Air preheating causes increases hydrogen and carbon monoxide production.

The motivation for this work was to define the reburning potential of sewage sludge (SS) gasification gas (syngas). A numerical simulation of the co-combustion process of syngas in a hard coal-fired boiler was made. All calculations were performed using the Chemkin program and a plug-flow reactor model was used. The calculations were modelled using the GRI-Mech 3.0 mechanism. The highest conversions for nitric oxide (NO) were obtained at temperatures of approximately 1000 K to 1200 K. The highest reduction efficiency was achieved when the molar flow-ratio of the syngas was 15 %. The combustion of hard coal with sewage sludge-derived syngas reduces NO emissions and the amount of coal needed to produce electricity and heat. Furthermore, advanced reburning, a more complex process, achieved an efficiency of up to 80 %. Calculations show that the syngas thus analysed can provide better results.

In this investigation, ignition processes of the methane and the propane using a high-temperature oxidizer (Toxi > Tai) with a varying oxygen concentration zO2 - the HTAC (High Temperature Air Combustion) conditions, applying a constant-volume bomb (CVB) was investigated. The influence of the initial temperature of the oxidizer Toxi was analyzed and discussed. It is shown that in order to achieve an effective reaction of ignition the oxidizer temperature needn't be maximized. Detailed evolution of ignition delay time with equivalence ratio τig was presented. It can be concluded that increment of oxygen concentration zO2 in oxidizer results in decrease of τig. Trials with propane are characterizing lower values of ignition delay time τig in comparison with methane.

This work presents the results of a modeling study of the ignition process of methane under Mild Combustion conditions. A mathematical model was formulated to predict the dependence of the equivalence ratio Φ and the initial temperature of oxidizer t on the temperature increment ΔT=t max -t. The increment of temperature was assumed as parameter characterizing the process of ignition. The model incorporates the basic principles of the energy and mass balance. The results of calculation were compared with the experiments which have been done on constant volume bomb (CVB) reactor. It is shown that in order to achieve the effective reaction of ignition it is not necessary to maximize the initial oxidizer temperature. There are optimal values of temperature oxidizer (t≈830 o C) in which parameters mentioned above reaches its extreme values.