Ali Altway

Effect of Particle Size on Simulation of Three-Dimensional Solid Dispersion in Stirred Tank

This work concerns the effect of particle size on three-dimensional solid dispersion in a baffled tank stirred with a disc turbine. The system studied consists of a cylindrical flat bottom four-baffled tank, 30 cm in diameter, with a six-blade disc turbine impeller, 10 cm in diameter, filled with water. Baffle width is 0.1-tank diameter and impeller clearance from tank bottom is 0.3-tank diameter. The height of liquid level in the tank is equal to tank diameter. The density of solid particle used is 2360 kg m −3 and the diameters are 87 μm, 50 μm and l0μm. Average solid concentration in the tank is 5% and 20% by volume. The impeller rotation speed is 13.3rps. In this work the three-dimensional solid concentration distribution was predicted using the Algebraic Slip Mixture model (ASM model) under FLUENT 1 5.1 facility. Standard k-ɛ turbulent model is used to model fluid flow field in the tank, and swirling radial jet model (SRJ model) approximates the velocity profile at the impeller tip. The simulation results are presented as concentration contour on r-z plane and r-θ plane in several positions in the tank for different average solid concentration and particle sizes. The solid concentration contour for 87 μm diameter solid and 5% average concentration shows that there is still a rather high solid concentration in the centre of the tank bottom, while in the liquid surface around the shaft the solid concentration is very low. This indicates the accumulation of solid particles in the centre of the tank bottom. For the other particle sizes the pattern of solid concentration distribution is similar. Below the impeller region the solid concentration near to the shaft is higher than the concentration far from the shaft. However, in the above impeller region the solid concentration near to the shaft is lower than the concentration far from the shaft. The distribution of the smaller particles is more uniform than the larger particles. Under the same rotation speed of 13.3 rps the distribution of l0 μ mon particles is almost uniform. The simulation result was verified using experimental data 2 . The simulation result agreed very well with experimental data up to average solid concentration, 20% by volume.

Production of Ethanol as a Renewable Energy by Extractive Fermentation

One issue with batch fermentation is that product inhibition causes low yields and ethanol productivity. The objective of this study was to increase the yield and ethanol productivity via continuous fermentation in a packed bed bioreactor with both an integrated extraction process and recycling of the raffinate into the fermenter. Molasses was used as the feedstock, and the immobilized cells were supported by ĸ-carrageenan. This process used n-amyl alcohol, 1-octanol, and 1-dodecanol as solvents. The yield and ethanol productivity increased from 8.79% to 20.03% and 34.54 g/L·h to 118.16 g/L·h for experiments using n-amyl alcohol, 9.05% to 12.67% and 35.59 g/L·h to 74.71 g/L·h, for 1-dodecanol, 8.89% to 13.45% and 34.93 g/L·h to 84.62 g/L·h, for1-octanol by increasing recycle ratio from 0 to 0.5. Based on these results, n-amyl alcohol was the best solvent for the extractive fermentation process.

Technique of ethanol food grade production with batch distillation and dehydration using starch-based adsorbent

Development and innovation of ethanol food grade production are becoming the reasearch priority to increase economy growth. Moreover, the government of Indonesia has established regulation for increasing the renewable energy as primary energy. Sorghum is cerealia plant that contains 11-16% sugar that is optimum for fermentation process, it is potential to be cultivated, especially at barren area in Indonesia. The purpose of this experiment is to learn about the effect of microorganisms in fermentation process. Fermentation process was carried out batchwise in bioreactor and used 150g/L initial sugar concentration. Microorganisms used in this experiment are Zymomonas mobilis mutation (A3), Saccharomyces cerevisiae and mixed of Pichia stipitis. The yield of ethanol can be obtained from this experiment. For ethanol purification result, distillation process from fermentation process has been done to search the best operation condition for efficiency energy consumption. The experiment for purification was divided into two parts, which are distillation with structured packing steel wool and adsorption (dehydration) sequencely. In distillation part, parameters evaluation (HETP and pressure drop) of distillation column that can be used for scale up are needed. The experiment was operated at pressure of 1 atm. The distillation stage was carried out at 85 °C and reflux ratio of 0.92 with variety porosities of 20%, 40%, and 60%. Then the adsorption process was done at 120°C and two types of adsorbent, which are starch – based adsorbent with ingredient of cassava and molecular sieve 3A, were used. The adsorption process was then continued to purify the ethanol from impurities by using activated carbon. This research shows that the batch fermentation process with Zymomonas mobilis A3 obtain higher % yield of ethanol of 40,92%. In addition to that, for purification process, the best operation condition is by using 40% of porosity of stuctured packing steel wool in distillation stage and starch-based adsorbent in adsorption stage, which can obtain ethanol content of 92,15% with acetic acid percentage of 0,001% and the rest is water. This result is qualified for ethanol food grade specification which is between 90 - 94 % of ethanol with maximum percentage of acetic acid is 0,003%, and passes in fusel oil and isopropyl alcohol test.

Biodegradation of Soils Contaminated with Naphthalene in Petroleum Hydrocarbons Using Bioslurry Reactors

Soil contaminated with naphthalene by the activities of exploration, production and disposal of petroleum waste into the environment causes serious damage to ecosystems environment. This is the target of processing by the bacteria as a model for remediation of soil contaminated with naphthalene. Thus, the study was focused on naphthalene biodegradation in soil contaminated with polyaromatic hydrocarbons with measurement parameters: the bacterial growth and dissolved oxygen. The research was conducted in a slurry bioreactor with soil to water ratio of 20:80 (%wt) with the addition of a consortia of Bacillus cereus and Pseudomonas putida bacteria with a concentration of 10% (v/v) and 15% (v/v). The slurry bioreactor was aerated, stirred with stirring of 100 rpm and temperature range of 26°C – 35°C. Naphthalene residue in petroleum hydrocarbons were measured using GC-MS. The result of identification with naphthalene initial concentration of 115.646 ng/uL, after 49 days of incubation for bacterial consortium 10% (v/v) with a bacteria ratio 3:2; 1:1; 2:3; and control showed the reduction to 33.77 ng/uL; 0.77 ng/uL; 10.28 ng/uL and 23.88 ng/uL, respectively with biodegradation percentages of 70.80%; 99.33%; 91.11%; and 79.35%. As for the bacterial consortium 15% (v/v) with the same ratio and control, the naphthalene concentration was reduced to 0.31 ng/uL; 0.19 ng/uL; 5.12 ng/uL and 23.88 ng/uL, respectively and biodegradation percentages of 99.73%; 99.84%; 95.57%; and 79.35%. This finding shows that percentage of crude low degraded considering the concentration crude oil increased.

Desain Pabrik Sodium Karbonat Dari CO2 Flue Gas Pabrik Semen

Dengan semakin meningkatnya kebutuhan energi di Indonesia selama beberapa tahunn terakhir ini, semakin juga meningkatkan bertambahnya gas rumah kaca yang dihasilkan. Gas rumah kaca (GRK) yang terdiri dari CO2, CH4, N2O, HCFC, dan CFC serta uap air (H2O), dimana yang menjadi sumber utama terjadinya pemasan global. Terutama pada pabrik yang menghasilkan GRK itu sendiri selama proses produksi, seperti pabrik semen 15.107.267 ton, pabrik produksi kapur 3.688.147 ton, dan pabrik kaca/gelas 170.000 ton. Prospek soda abu (nama pasar sodium karbonat) di Indonesia masih dalam kondisi baik karena kebutuhan komoditas ini semakin bertambah dengan rate 3,4% pertahun untuk industri kapur, industri gelas, dan industri keramik. Selama ini kebutuhan soda abu di Indonesia masih dipenuhi dengan adanya impor dari negara lain, karena belum adanya produsen natrium karbonat di dalam negeri yang menjadikan komoditas ini sebagai produk utama dari pabriknya. Pabrik ini direncanakan akan didirikan di Kabupaten Tuban, JawaTimur dengan estimasi waktu mulai produksi pada tahun 2017. Penentuan lokasi pabrik berdasarkan pada sumber bahan baku. Hal ini karena bahan baku yang digunakan adalah flue gas dari pabrik semen. Untuk menemuhi kebutuhan akan sodium karbonat kapasitas produk sodium karbonat ini sebesar 86,37 ton/jam. Pabrik beroperasi selama 24 jam per hari dengan hari kerja 330 hari per tahun. Proses pembuatan soda abu dengan proses karbonasi terdiri dari empat unit proses, yaitu dust removal unit, absorption unit, crystalization unit, dan soda ash unit. Dari analisa perhitungan ekonomi didapat Investasi Rp79.285.526.850, IRR sebesar 26%, POT selama 4,39 tahun, dan NPV positif 15 tahun sebesar Rp589.068.911.634. Umur dari pabrik ini diperkirakan selama 15 tahun dengan masa periode pembangunannya selama 2 tahun di mana operasi pabrik ini 330 hari/tahun.

Extractive Fermentation of Sugarcane Juice to Produce High Yield and Productivity of Bioethanol

Ethanol production by batch fermentation requires a simple process and it is widely used. Batch fermentation produces ethanol with low yield and productivity due to the accumulation of ethanol in which poisons microorganisms in the fermenter. Extractive fermentation technique is applied to solve the microorganism inhibition problem by ethanol. Extractive fermentation technique can produce ethanol with high yield and productivity. In this process raffinate still, contains much sugar because conversion in the fermentation process is not perfect. Thus, to enhance ethanol yield and productivity, recycle system is applied by returning the raffinate from the extraction process to the fermentation process. This raffinate also contains ethanol which would inhibit the performance of microorganisms in producing ethanol during the fermentation process. Therefore, this study aims to find the optimum condition for the amount of solvent to broth ratio (S: B) and recycle to fresh feed ratio (R: F) which enter the fermenter to produce high yield and productivity. This research was carried out by experiment. In the experiment, sugarcane juice was fermented using Zymomonasmobilis mutant. The fermentation broth was extracted using amyl alcohol. The process was integrated with the recycle system by varying the recycle ratio. The highest yield and productivity is 22.3901% and 103.115 g / L.h respectively, obtained in a process that uses recycle to fresh feed ratio (R: F) of 50:50 and solvents to both ratio of 1.

Kinetics study of carbon dioxide absorption reaction into the promoted methyldiethanolamine solution

The absorption of carbon dioxide (CO2) is important in the industrial world. In industries, especially petrochemical, oil, and natural gas sectors, separation process of CO2 gas which is a corrosive gas (acid gas) is required. So, the separation process of CO2 gas stream is important, one of the methods used to remove CO2 from the gas stream is reactive absorption process using the promoted methyldiethanolamine (MDEA) solution. Therefore, this study is aimed to obtain the reaction kinetics data of CO2 absorption in MDEA solution using arginine as a promoter. Arginine was chosen because of its amino acid molecule which is reactive, so it can accelerate the reaction rate of MDEA. Moreover, this study also made a comparison between the reactivity of MDEA solution using arginine and MDEA solution using other promoters (glycine and piperazine) for CO2 absorption. The method used is absorption using laboratory scale of Wetted Wall Column (WWC) equipment at 1 atm. This study provides the reaction kinetics data i...

Simulation and optimization of continuous extractive fermentation with recycle system

Extractive fermentation is continuous fermentation method which is believed to be able to substitute conventional fermentation method (batch). The recovery system and ethanol refinery will be easier. Continuous process of fermentation will make the productivity increase although the unconverted sugar in continuous fermentation is still in high concentration. In order to make this process more efficient, the recycle process was used. Increasing recycle flow will enhance the probability of sugar to be re-fermented. However, this will make ethanol enter fermentation column. As a result, the accumulated ethanol will inhibit the growth of microorganism. This research aims to find optimum conditions of solvent to broth ratio (S:B) and recycle flow to fresh feed ratio in order to produce the best yield and productivity. This study employed optimization by Hooke Jeeves method using Matlab 7.8 software. The result indicated that optimum condition occured in S: B=2.615 and R: F=1.495 with yield = 50.2439 %.

Biogas production from pretreated coffee-pulp waste by mixture of cow dung and rumen fluid in co-digestion

Coffee is an excellent commodity in Indonesia that has big problem in utilizing its wastes. As the solution, the abundant coffee pulp waste from processing of coffee bean industry has been used as a substrate of biogas production. Coffee pulp waste (CPW) was approximately 48% of total weight, consisting 42% of the coffee pulp and 6% of the seed coat. CPW holds good composition as biogas substrate that is consist of cellulose (63%), hemicellulose (2.3%) and protein (11.5%). Methane production from coffee pulp waste still has much problems because of toxic chemicals content such as caffeine, tannin, and total phenol which can inhibit the biogas production. In this case, CPW was pretreated by ethanol/water (50/50, v/v) at room temperature to remove those inhibitors. This study was to compare the methane production by microbial consortium of cow dung and rumen fluid mixture coffee pulp waste as a substrate with and without pretreatment. The pretreated CPW was fermented with mixture of Cow Dung (CD) and Rumen ...

Simulation and modeling CO2 absorption in biogas with DEA promoted K2CO3 solution in packed column

Absorption of carbon dioxide (CO2) using potassium carbonate (K2CO3) is one of biogas purification method. However, K2CO3 have slow mass transfer in liquid phase. So it is necessary to eliminate the disadvantage of CO2 absorption using K2CO3 by adding promotor (activator). Diethanol amine (DEA) is one of promotor which can increase its reaction rate. Simulation and modeling research of the CO2 absorption from biogas with DEA promoted K2CO3 solution has not been conducted. Thus, the main goal of this research is create model and simulation for the CO2 absorption from biogas with DEA promoted K2CO3 solution, then observe the influence of promoter concentration. DEA concentration varies between 1-5 %wt. From the simulation, we concluded that the CO2 removal rise with the increasing of promoter concentration. The highest CO2 removal is 54.5318 % at 5 % wt DEA concentration.