A BIOMASS PYROLYSIS GASIFIER APPLICABLE TO RURAL CHINA

A pyrolsis gasifier was developed to make use of indigenous biomass to help solve the problem of rural energy shortage particularly in engine fuel shortage and to reduce pollution. First, (low diagram of pyrolysis gasification system was designed and the sketch of gasifier was drawn. Second, the gasifier thus drawn was made. It was successfully operated with corncob feeding. Its performance parameters were measured in an experimental scheme designed according to an orthogonal test table. A variance analysis was taken of the results were taken to sort out the best experimental condition. A run on such conditions gave a heating value of the gas as high as 12.4MJ/nm³ and without tar, a conversion rate about 60.2%, and a total energy efficiency about 59.3%. Regressive analysis of the data that shows the flow rate of the gas is an exponential function of time. Finally, explanations to the analysis results of the data and what problems of the gasiSSfier to be tackled were given.     

CATALYTIC CRACKING OF TARS FROM COAL DEVOLATILIZATION

ABSTRACT

A set of runs were performed on the catalytic and thermal cracking of the tars present fn the gasifier off-gas stream; the cracking referred to here Js essentially hydrocracking, in view of the considerable amount of hydrogen being present in the gas stream. The catalyst evaluated for tar cracking was a commercial cobalt-molybdenum catalyst, suppported on γ-Al₂O₃(Katalco-477). It was observed that there was a decrease in the amount of tar obtained with the cracking unit on-line with the gasifier; the tars were cracked to gaseous products in the presence of catalyst. Furthermore, it appeared that higher ring structures were transformed to less heavier components; thus cracking could become beneficial in downstream processing of the gas stream coming out of a gasifier.     

A MODEL OF A PYROLYSIS GASIFIER FOR PREDICTION COMPOSITIONS AND FLOU RATE OF PRODUCED GAS

ABSTRACT

A model of pyrolysis gasifier, which is mainly composed of a pyrolysis, a cracking and a combustion chamber, it developed to predict its performance parameters and to simulate its operation. Toe model consists of a pyrolysis-cracking sub-model, a secondary gasification sub-model and a combustion sub- model, of which the pyrolysis-cracking sub-model is modified to predict components of tbe pyrolysis gas. Then, It with the other two sub-models can predict components, heating value and flow rate of the produced gas, thermal efficiency and total energy efficiency of the gasifier as ell. Crank-Nicolson Scheme (half implicit difference formulation) in which the time step is not confined by stability and the cutting error is small, is applied to solving the model whose differential equations are nonlinear and have no analytic solution. Theo, the nonlinear difference algebraic equations are solved by interalions, which requires less storage of computer. Underrelaxation is applied to avoiding divergence of Causs-Seidel interations. Finally, the simulated results are input to Software Lotus 1-2-3, by which the results are printed and graphed so as to compare with the experimental ooes, and it shots acceptable agreement, thus validate the model.     

Auto-Design of Neural Network–Based GAs for Manipulating the Khangiran Gas Refinery Sweetening Absorption Column Outputs

Abstract

In this work, a new approach for the auto-design of neural network-based genetic algorithm (GA) has been adopted to manipulate the products of an absorption column in the Khangiran gas refinery located in northeastern Iran. The experimental input data included gas flow rate, gas pressure, gas temperature, amine temperature, amine flow rate. In order to construct a GA–artificial neural network (ANN)-based model, the H₂S flow rate and dirty amine flow rate were selected for the output. The proposed method was assessed by the data taken from a case study in the Khangiran gas refinery. Design of topology and parameters of the neural networks as decision variables was first achieved by a trial-and-error procedure followed by genetic algorithms, which enhances the effectiveness of the forecasting scheme. The results reveal that the testing results from the model were in good agreement with the experimental data.     

Catalytic gasification of oil sludge with calcined dolomite

Abstract

Gasification of carbon-based residues for synthesis gas production is one of the most important strategies for clean energy production and environmental management. Currently, China is the world's largest net oil importer which is a result of China's added refinery capacity. In this article, a simulation model of oil sludge gasification with a combination of air and steam was developed using Aspen Plus software. Effect of dolomite as an active catalyst on gas composition was studied at various operating conditions. Results showed that H₂ and CO increased with reaction temperature, while CH₄ decreased from 9.1 to 4.71?vol% because of increased steam reforming of CH₄. By adding steam to the gasifier, H₂ content increased significantly, while CO content showed an opposite trend.     

LIGNITE RETORTING USING SOLID HEAT CARRIER

ABSTRACT

A retorting pilot plant with capacity of 10 kg/h using hot char as solid heat carrier was constructed. This paper describes experimental results using four different lignites. The product char was used as solid heat carrier and the retorting temperature range was 450^°C-670^°C. The maximum yield of tar was up to 92% of the value of Fischer Assay. Produced gas and tar can be used as chemical feedstock and they are clean energy.     

DELAYED COKING OF HYDROTREATED REDUCED CRUDE

ABSTRACT

A laboratory coking unit was designed and constructed for an experimental study of the delayed coking process of hydrotreated Kirkuk reduced crude. The yield and analysis of coke, gases and liquid products were obtained for each experiment. The gas < C₄. and gasoline yield decrease by increasing Liquid hourly space velocity (LHSV) while the yields of kerosene and gas oil increase and no effect of LHSV on petroleum coke yield was observed, The specific gravity of gasoline, kerosene and gas oil decreases by increasing LHSV. The increase in LHSV (decrease in residence time) decreases the olefinic hydrocarbons of produced gas oil and fraction 350-450^°C. Sulfur content of produced coke and coking residue increases by increasing residence time while it changes slightly for kerosene and gas oil. By increasing the recycle ratio (RR), the yield of gas decreases while the coke yield increases. Sulfur content of gas oil and coking residue increases with an increase in the recycle ratio while it decreases for coke. Metals content of coke decreases with an increase in the recycle ratio and coke with accepted properties for aluminum anode manufacture could be produced when a recycle ratio of 1.4 was used.     

KINETICS OF HYDRODESULFURIZATION OF HEAVY GAS OIL DERIVED FROM OIL-SANDS BITUMEN

ABSTRACT

With gradual shortage in the supply of crude oil, the importance of producing synthetic crude oil from oil sands and shale oil is increasing day by day. In the present paper, the effects of various process variables such as temperature, liquid hourly space velocity and hydrogen/heavy gas oil volumetric ratio on the removal of sulfur compounds from oil sands derived heavy gas oil has been studied. The experiments have been carried out in a micro scale trickle bed reactor over a commercial Ni–Mo catalyst. The temperature, liquid hourly space velocity and hydrogen/heavy gas oil volumetric ratio have been varied from 365 to 415°C, 0.5 to 1.9 h^?1 and 400 to 1000 ml, respectively. Under optimum reaction conditions over 96% conversion of sulfur compounds was achieved. The kinetics of the rate of sulfur removal from the oil sands derived heavy gas oil has also been discussed in this article.     

Hydrogen production by catalytic gasification of petroleum residue

The liquid fuel gasification to obtain a clean flue gas for power generation and produce chemicals such as methanol is a most promising attempt to reduce the greenhouse gas emissions and air pollutants. In this paper, an equilibrium model of liquid fuel gasification was developed by the method of Gibbs free energy minimization. Two kinds of catalysts: Ni/CeO₂/Al₂O₃ and Ni/Al₂O₃ were used to explore the influence of catalysts and operating conditions on hydrogen yield and char conversion. Over the ranges of operating conditions studied, the maximum hydrogen yield reached 52.47 vol%, whereas the char conversion varied between 45.2% and 98.5%. The results indicated that an appropriate reaction temperature is favorable for higher hydrogen production and char conversion. The model was validated with experimental data obtained from a fluidized bed gasifier.     

An Investigation to Using a Pump for Gas Injection Into a Core

Abstract

Gas injection is one of the methods used in enhanced oil recovery. A pump is usually used for injection of gas into a core in the laboratory. For precision of the experimental results, it is important to keep experimental errors at the minimum value.

In this work, an approach for reduction of one of the most important and effective parameters in the generation of experimental errors during gas injection is presented. One of the main goals of this study is to increase the accuracy of gas injection into a core by using a pump at the experimental scale. In gas injection into a core, if the pump is adjusted to a constant rate, under some conditions, gas injection cannot be conducted with a constant rate and therefore deviation from the constant rate occurs. The value of deviation from the constant rate is different with respect to rock and fluid properties and operating conditions.

In this investigation, experiments were carried out on a carbonate core with low permeability. Experimental data and effective parameters on the error in using a pump for gas injection with a constant rate were studied.     

Aromatization Reaction of Liquefied Petroleum Gas

Abstract

The aromatization reaction of liquefied petroleum gas has been studied by using Huabei liquefied petroleum gas as raw material and LBO-A as catalyst, and the four lumped kinetics models network have been put up forward on the basis of lumped theory and the aromatization reaction mechanism. In the network, the aromatization reaction species were firstly lumped into C₄, propylene, low-molecular hydrocarbon, liquid, and coke. A mathematical method is first introduced to study on the product distribution of liquefied petroleum gas aromatization reaction. The results from experimental data are in accordance with the quantitatively analytical conclusions drawn from the calculated data.     

关井阶段CO2作储气库垫层气的动态影响规律

目的为应对地下储气库中的垫层气损失,采用经济气体CO₂作为垫层气,目前,CO₂作垫层气在实际应用中存在各种条件限制,且对其在关井阶段的应用研究较少,有必要对在关井阶段CO₂作垫层气对天然气储气库的运行影响因素进行研究。 方法利用有限元模拟CO₂作储气库垫层气时,研究关井阶段储气库动态参数(注气压力、注气速率和CO₂垫层气比例)对混气带的影响规律。 结果注气压力对混气带的影响不大,将其控制在12 MPa左右最为合理,此时混气带占储气面积的比例为23.731 5%;混气带面积占比随注气速率的增大而减小,但是在注气口附近会出现混合区域,导致回采天然气时出现大量的混合气体,所以注气速率控制在0.7×10⁸ m³/d时最为合理,这时混气带面积占比为18.324 6%;CO₂作垫层气的比例对天然气-CO₂之间的混合影响明显,当CO₂垫层气比例为20%时,混气带面积占比为7.236 5%。 结论根据实验结果设计针对混气带的控制措施,当注气压力控制为12 MPa时,注气速率为0.7×10⁸ m³/d,当CO₂垫层气比例为20%时,能让储气库的运作更为经济,实验结果可为实际储气库的建设提供参考。      

EXPERIMENTAL VERIFICATION FOR PROCESS MODELING OF COKING HEATER INNER TUBE

ABSTRACT

The flow and reaction processes of vacuum residue were simulated in an electric heated tube for coking heater. The vacuum residue was pumped into the tube, and heated up to about 500°C to carry out thermal conversion. Gaseous products were measured by gas meter and analyzed by gas chromatography. The liquid products were first quenched and collected by a specially designed sampling tube, and then analyzed by liquid chromatography. Therefore, the conversion fraction of every narrow fraction was obtained experimentally. Both flow and reaction processes were simulated using a dynamic model, the simulated conversion at exit of the tube is near to the experimental data under three dynamic conditions. This indicates that the model for flow and reaction processes used in this paper is reasonable.     

Dissociation behavior of （CH4 ＋ C2H4） hydrate in the presence of sodium dodecyl sulfate

Separation of a mixture of CH4+C2H4 gas by forming hydrate in ethylene production has become of interest,and the dissociation behavior of(CH4+C2H4) hydrate is of great importance for this process. The hydrate formation rate could be increased by adding a small amount of sodium dodecyl sulfate(SDS) into water. In this work,the kinetic data of CH4(18.5 mol%) +C2H4(81.5 mol%) hydrate decomposition in the presence of 1000 mg·L-1 SDS at different temperatures and pressures were measured with the depressurizing m...     

SOLVENT EXTRACTION OF COALS THROUGH ATD3 REACTION UNDER AMBIENT PRESSURE CONDITION

ABSTRACT

A novel reaction such as ATD³ reaction which has been recently found to be an attractive reaction for rendering more 50% coal extractable, has been tested on different bituminous coals and a lignite. The reaction has been found to be generally applicable on coals and lignite to render about 50% coal extractable. The reaction proceeds under industrially convenient conditions and involves the use of only coal or petroleum derived solvents. Reaction of % carbon, % volatile matter and atomic O/C ratio of coals with the extractability of coal through ATD³ reaction has been drawn.     

SOME REMARKS ON SURFACE FREE ENERGY OF POLISH COALS

ABSTRACT

On the basis of the studies concerning the determination of the surface free energy of Polish coals published earlier analyses of the equilibrium state of three-phase system were carried out. The three-phase systems were:

1) coal - liquid drop - air, 2) coal - water drop -air, 3) coal - water drop - hydrocarbon, 4) coal -hydrocarbon drop - water and 5) coal - air bubble -water.

Analysing the measured values of the contact angles in the systems studied the occurrence of a liquid film on the coal surface was taken into account. The surface free energy. of Polish coals results from both dispersion (T_s ^d) and nondispersion (T_s ⁿ) intermolecular interaction. A distinct relationship was found between the dispersion components of the surface free energy and coal ranks.     

Rheology of Doped Nigerian Niger-Delta Waxy Crude Oil

Abstract

Precipitation and deposition of wax, which usually results from temperature lowering, has detrimental effects on petroleum industry operations. To appreciate and understand the physicochemical mechanics of wax precipitation, rheological experiments were carried out on three doped and undoped Nigerian waxy crude oils. The characteristic shear stress straining rate shows an initial constant shear stress below 50 sec^?1 shear rate, followed by a gradual increase above 50 sec^?1 which is indicative of energy consumption in the partial break-up of wax matrix bonds. Doping greatly ameliorates the rheological properties and pour points of the crude oils. The Bingham plastic model excellently fit the experimental data, with a correlation coefficient ≥ 0.97721.     

MASS TRANSFER IN THE LIQUID PHASE METHANOL SYNTHESIS PROCESS

ABSTRACT

The mass transfer characteristics of the liquid phase methanol synthesis process were experimentally investigated using a one-liter, mechanically agitated slurry reactor. The CuO/ZnO/Al₂O₃ catalyst was crushed to -140 mesh and suspended in an inert mineral oil (Witco # 40). The catalyst loading was varied within limits of experimental feasibility. The effects of temperature, pressure, level of oil, impeller speed, and gas flow rate on the overall gas-liquid mass transfer coefficient K_Lia_B were studied

The results obtained using a two-level, half-fractional factorial design of experiments indicated that the impeller speed, feed flow rate, and temperature had significant effects on the mass transfer coefficient at the experimental conditions examined. Correlations were developed for the Sherwood number based on the Reynolds number, the Schmidt number, the reciprocal gas flow number, the gas-liquid viscosity ratio, and the dimensionless temperature. A simplified power-law type approach was also used to correlate the overall gas-liquid mass transfer coefficient with the impeller speed, gas flow rate, and dimensionless temperature.     

Application of RBF-ANN in prediction of natural gas density in different operational conditions

Abstract

The degree of accuracy in prediction of different processes of gas engineering is extensively dependent on gas properties. One of the dominant properties which has straight effects on calculation and performance of different parts of gas industries is natural gas density. Due to this fact, in this paper, radial basis function artificial neural network (RBF-ANN) was used as novel approach to estimate gas density in terms of molecular weight, critical pressure and critical temperature of gas, pressure and temperature. To prepare and validate RBF-ANN model, a large and reliable experimental data bank was gathered from literature. A comprehensive analysis which include statistical and different graphical analysis were done to evaluate the performance. The coefficients of determination (R²) were determined as 0.99995 and 0.99993 for training and testing phases respectively. The comparisons illustrate that the RBF-ANN has great potential in prediction of natural gas density at different operational conditions.     

The Optimization of Underground Gas Storage in a Partially Depleted Gas Reservoir

Abstract

Underground gas storage (UGS) is a well-known technology to supply variable demand of natural gas market. The objective of this work is to demonstrate the feasibility of UGS development in an Iranian depleted fractured gas reservoir. For this purpose, gas demand analysis was conducted based on yearly consumption, and the peak condition demand was obtained. Then, a full-field multicomponent reservoir model was constructed based on the rock and fluid data and comprehensive production history. A modified Peng-Robinson equation was used to estimate the phase behavior of the reservoir and injection fluid. The compositional model was verified through performing history matching on gas production rate.

After history matching, an injection/withdrawal (I/W) schedule was designed to meet necessary gas consumption. Production scenarios were conducted to obtain optimum operating conditions for this reservoir. It was determined that at least four new wells are required to establish successful UGS plan to meet the target withdrawal rate. Results show that the use of a horizontal well is superior to a vertical well because of less water production during storage cycles. Water cut, productivity, and injectivity indexes of individual wells were considered as prominent factors to find the optimum well pattern, using a connection transmissibility factor to compare the capacity of each well to produce. In addition to constant I/W rate, a variable I/W rate scenario was proposed whose result showed no difference compare to the results obtained in previous runs.

Results show that the reservoir under study is capable of providing peak gas consumption during the cold months in Iran.