Abstract
The use of conventional correlation for pressure drop and dispersion coefficient calculation may result in inaccurate values for zeolite packed bed as the correlations are generally developed for regularly shaped and uniformly sized particles. To support the research on the application of modified natural zeolite as tar cracking catalyst, the research on the hydrodynamic behaviour of zeolite packed bed has been conducted. Experiments were carried out using a glass column with diameter of 37.8 mm. Natural zeolite with particle size of about 2.91 to 6.4 mm was applied as packing material in the column, and the bed height was varied at 9, 19 and 29 cm. Air was used as the fluid that flows through the bed and nitrogen was used as a tracer for residence time distribution determination. Air flow rates were in the range of 20 to 100 mL/s which correspond to the laminar-transitional flow regime. The pressure drops through the bed were in the range of 1.7 to 95.6 Pa, depending on the air flow rate and bed height. From these values, the parameters in the Ergun equation were estimated, taking into account the contribution by wall effect when the ratio of column to particle diameter is low. The viscous and inertial term constants in the Ergun equation calculated ranges from 179 to 199 and 1.41 to 1.47 respectively while the particle sphericity ranges from 0.56 to 0.59. The reactor Peclet number were determined to range from 5.2 to 5.5, which indicated significant deviation from a plug flow condition.
Highlights
Syngas produced through biomass gasification will generally contains tar which must be removed prior to utilization as tar may cause various problems when it condense in the downstream equipment
The first and second type originated from Sukabumi (West Java) and will be referred to as Zeolite 1A (Z1A) and Zeolite 1B (Z1B) respectively to distinguish the two from Zeolite 2 (Z2) that originates from Klaten (Central Java)
The results from the parameter estimation using the method that involves the use of volume mean diameter, and Equation 5 and 6 to calculate for the Ergun equation constants is presented in Table 2 along with other methods, presented and discussed in the previous work [13], for comparison
Summary
Syngas produced through biomass gasification will generally contains tar which must be removed prior to utilization as tar may cause various problems when it condense in the downstream equipment. Gasification Group of ITB Chemical Engineering Department is currently working on the development of tar cracking catalyst through the modification of domestic natural zeolite. Natural zeolite particles are irregularly shaped and distributed in size. The measurement of pressure drop and determination of retention time distribution by tracer injection experiment were conducted by applying the particles in a glass column. The results from the tracer injection experiment were used to calculate for the reactor Peclet number. The reactor Peclet number was subsequently used to predict the effect of dispersion on the reactor performance using the kinetic data of several tar cracking catalyst tabulated by [1]. More details on the particle characterization, pressure drop measurement and tracer injection experiment can be found in the previous work [13]
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