Abench-scale updraft gasifier was used as a fluidizedand FIXED-BED gasification unit in three modes (fluidizedBED at equivalence ratios (ER) =0. 2 and 0. 25, and a mode in FIXED-BED). The experiments were done in five different temperatures (650, 700, 750, 800 and 850oC). To obtain the required data to develop a thermodynamic equilibrium model, the proximate and ultimate analysis were carried out on potato shoot as feedstock. Since the developed model is a temperature-based model, it gives different outcomes in different temperatures. The model gave a completely exact result to predict CH4 in fluidized-BED at ER=0. 25. The average error for the difference between each produced gas in experiments and the model showed the best result of the model for CO with the error of just 0. 7%. Regarding each experiment data difference with the model data, the model was more accurate to be used in fluidized-BED, especially at ER=0. 25 than the other two modes. Moreover, the best performance of the model was obtained for CO, N2 and CO2, according to the average errors. Since the maximum amount of high heating value (HHV) and carbon conversion efficiency (CCE) was observed at higher temperatures, it can be contended that the model has better performance at higher temperatures.

In this research, carbon dioxide absorption by 13x zeolite was studied in a FIXED BED reactor. The adsorption experiments were carried out in a FIXED BED with 1 m height and 10 cm diameter. The adsorption experiments were carried out to investigate adsorption operating parameters including temprature, pressure, gas flow rate and adsorbent amount. The analyses result showed that adsorbent diameter avarege is 1.92 nm and interface area is 697 m2/gr. The EXPERIMENTAL result showed that adsorption rate of carbon dioxide was increased by increasing pressure and BED height and decreasing temperature. The evaltuation of adsorption isotherm data showed that the CO2 adsorption is physical and the adsorbent has high capacity. Also the isotherm data was evaluated with different isotherm models and the results showed that Frendlich model with correlation coeffient 0.999 has good agreement with EXPERIMENTAL data.

The first step in producing eco-friendly biodegradable detergents is the dehydrogenation process of heavy paraffins. Despite its importance, a few studies have been conducted on the process. In this paper, the heavy paraffin dehydrogenation process was elucidated using Computational Fluid Dynamics (CFD) to simulate the performance of a pilot-scale FIXED-BED reactor, investigate the effects of key operating parameters (temperature, pressure, LHSV, and H₂/HC ratio), and identify the best operating conditions for maximizing mono-olefin yield and selectivity. The validation of CFD simulation results was performed by comparing them with pilot plant data; The absolute relative deviations were less than 5.5%, indicating the adequacy of the simulation was confirmed. The CFD simulation results showed that the paraffin conversion and mono-olefin yield are higher at a lower Hydrogen-to-Hydrocarbon molar ratio (H2/HC). However, the mono-olefin selectivity is higher at higher H2/HC ratios. Therefore, an H2/HC between 4 and 6 would be suggested as the best condition. Also, the conditions to achieve the best system performance were the temperature between 460 and 470 oC and LHSV of 15 hr-1.

In this work, zeolite 13X with a porosity structure has been used as an adsorbent for adsorption of CO2 flue gas. The effects of operating conditions, including pressure and time, on adsorption capacity were investigated. The EXPERIMENTAL conditions include constant temperature, the range of pressure of 1-9 bars, and the registration of adsorption capacity with the passage of time. EXPERIMENTAL data were adjusted with adsorption isotherm models including two-and threeparameter isotherms. In addition, the process was studied in terms of kinetic models; after the implementation of the EXPERIMENTAL data with kinetic models, the speed of the process equations was obtained. The first-order equation was selected as the best kinetic model for this process. The results showed that the adsorption capacity of 13X was 71. 5 mg/g at a pressure of 8 bars. Also, the results indicate that 13X has a high capacity at low pressures. With regard to achieved results for adsorption isotherm modeling, the adsorption isotherm followed the three parameters and, among the three-parameter models, Toth isotherm can interpret the process. Also, the results of the FIXED BED indicate very high adsorbent selectivity to carbon dioxide adsorption, and there is little oxygen and nitrogen adsorption.

This paper investigated the possibilities of using birch wood chips for FIXED-BED downdraft gasification. The preliminary air gasification resulted producer gas with an average composition of 11.5% CO, 5.4% CO2, 5.9% H2, 0.38% CH4 corresponding to a mean lower heating value of about 2 MJ/kg. The approximate size of woodchips used for gasification was around 11.5 mm for a maximum solid throughput of 0.65 kg/h. The obtained equivalence ratio (ratio between actual air fuel ratio and stoichometric air fuel ratio) as a result of air and biomass feed was close to 0.45 which was stable throughout the test. Producer gas left the gasifier at ca. 150oC and was diverted for flaring owing to the level of low energy content. Despite availability, the option for gas to generate heat and electricity via integrated gas engine has not been utilized in the present case and remained for further ongoing research.

The aim of this project is to study the wastewater treatment system of Sahand dairy products factory and to provide a solution for the problem. The existing wastewater treatment system in this factory is an anaerobic and aerobic system, where the aerobic system is an extended activated sludge. This study had two phases as follows: Phase One: This phase lasted from February 1, 2003 to September 1, 2004. Based on the integrated sampling, the company's wastewater was estimated to be approximately 100m3 per day. In this phase, the efficiency of anaerobic treatment system was investigated. The parameters measured in this study were BOO, COD, N03, P04, TS, OIL, and grease. After the samples were analyzed, the removal efficiency of the organic elements turned out to be low for the anaerobic system in winter. Phase Two: This phase lasted from September 1, 2004 to December 29, 2004. To increase the efficiency of the anaerobic system, a FIXED-BED was installed. As a result of the improvement of the system, the following findings were obtained for the two years of 2003 and 2004: - An increase in the BOd removal efficiency from 30% to 61.4% - An increase in the COD removal efficiency from 45% to 64.6% - An increase in the N03 removal efficiency from 58.5% 82.8% - An increase in the TS removal efficiency from 63.8% to 67.9% - For the P04 removal efficiency, no significant difference was observed. The results for the aerobic system after its improvement are as follows: - An increase in the BOd removal efficiency from 83% to 90.5% - An increase in the COD removal efficiency from 82.2% to 92.2% - An increase in the TS removal efficiency from 72% to 80% - For the P04 and the N03 removal efficiency, no significant difference was observed.

In this study, tea waste (TW) is employed for the removal of Congo red (CR) from aqueous solutions in a FIXED-BED column at 30oC. The breakthrough curves of the adsorption process of CR on TW at three different flow rates are determined. The results revealed that the breakthrough curves were dependent on flow rates in a manner in which a lower flow rate was in favor of the CR adsorption in the column-mode process. As the flow rate increased from 4.6 to 6.6 mL/min, the amount of dye uptake capacity decreased from 1.78 to 1.53 mg/g. The effect of the presence of Fe2O3 on the adsorption of CR on TW is also studied at 30oC. The results showed that the presence of nanoparticles increased the adsorption uptake of CR by about 32%. Moreover, four novel models are developed for the prediction of the breakthrough curves resulted from the EXPERIMENTAL data. The results of the models were in good agreement with EXPERIMENTAL data (R2>0.99). The statistical parameters confirm the suitability of the models.

Removal of copper ions from aqueous solutions was carried out using a synthesized hydrogel polymeric made by sodium alginate/zeolite/chitosan. At first, a batch experiment was done to determine the diffusion coefficient. And then a column with radial feeding was designed and made. The continuous experiment was carried out with a feed by 500 ppm concentration, a flow rate of 16 cm3/min, and hydrogel beads with a radius of 1. 5 mm during the 97 min. Mass transfer and sphere diffusion equations were extracted in the BED and solved numerically. Concentration profile versus time derived from this model. To evaluate the model the results were compared by EXPERIMENTAL data. The results show that the model has 9. 8% error. The effects of parameters including concentration (350, 500, and 700 ppm), a flow rate of 30, 16, 7. 5 mL /min, and particle radius of 1. 1. 5 and 2mm were investigated via model. The results showed that with increasing initial concentration, the lifetime of the BED was increased from 70 minutes to 76 minutes. As the flow rate increased, the filling time of the column decreased from 167 minutes to 37 minutes, and as the radius increased, the life span of the column has not sensible changes.

The transport of sediment in open channels is a complex process, and the physics of this phenomenon have not been completely explored. The majority of research work on sediment transport has been concentrated on BEDs formed of the same mobile sediment and only a few researchers have been concerned with sediment motion over FIXED BED. This paper reviews the state of the problem and focuses on some practical points. Sediment threshold experiments were conducted in the two types of V-shaped bottom channels. Sand and gravel particle movements were considered and the relationship between flow discharge and BED shear stress, as well as channel BED slope were found at the threshold condition. Some practical and design equations were found to be more appropriate. It may be found that the effect of cross sectional shape on sediment threshold in FIXED BED channels should be examined.