Modified Ergun Equation for Airflow through Packed Bed of Loblolly Pine Grinds

The packed bed columns with non-Newtonian liquid are increasing importance as a simple and inexpensive means of achieving yield of different chemical and biochemical processes though their hydrodynamic behavior is complex and not yet fully understood. In this article non-Newtonian flow behavior on frictional pressure was investigated in packed bed within a range of liquid velocity 0.004-0.04 m/s. The frictional pressure loss in non-Newtonian liquid system has been analyzed by modified Ergun equation. The modification of the Ergun equation is incorporated with the flow behavior index of non-Newtonian liquid. The degree of frictional pressure loss decreases with increase in flow behavior index. A correlation has been developed to interpret the degree of effect on the frictional pressure loss. The correlation may be useful for further understanding and scale-up of the packed bed column for its industrial application.

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Experimental Study on Pressure Drop and Flow Dispersion in Packed Bed of Natural Zeolite

MATEC Web of Conferences ◽

10.1051/matecconf/201815602006 ◽

2018 ◽

Vol 156 ◽

pp. 02006

Author(s):

Petric Marc Ruya ◽

Herri Susanto ◽

Mubiar Purwasasmita

Keyword(s):

Pressure Drop ◽

Natural Zeolite ◽

Air Flow ◽

Plug Flow ◽

Particle Diameter ◽

Packed Bed ◽

Transitional Flow ◽

Ergun Equation ◽

Hydrodynamic Behaviour ◽

Bed Height

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.

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Analytical quantification of coefficients in the Ergun equation for fluid friction in a packed bed

Transport in Porous Media ◽

10.1007/bf00617551 ◽

1994 ◽

Vol 16 (2) ◽

pp. 189-207 ◽

Cited By ~ 76

Author(s):

J. Prieur Du Plessis

Keyword(s):

Packed Bed ◽

Fluid Friction ◽

Ergun Equation ◽

Analytical Quantification

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Polysulfide-borohydride modification of southern pine alkaline pulping integrated with hydrothermal pre-extraction of hemicelluloses

TAPPI Journal ◽

10.32964/tj10.7.9 ◽

2011 ◽

Vol 10 (7) ◽

pp. 9-16

Author(s):

SUNG-HOON YOON ◽

HARRY CULLINAN ◽

GOPAL A. KRISHNAGOPALAN

Keyword(s):

Loblolly Pine ◽

Sodium Borohydride ◽

Kraft Pulping ◽

Hot Water ◽

Pulp Yield ◽

Paper Strength ◽

Southern Pine ◽

Two Stage ◽

Simultaneous Treatment ◽

Process Modification

We studied three process modifications to investigate their effects on the property and yield recovery capabilities of kraft pulping integrated with hemicellulose pre-extraction of southern pine. Loblolly pine chips were pre-extracted with hot water until the sugar extraction yield reached the targeted value of 10% and then subjected to conventional and modified kraft pulping. Modification included polysulfide pretreatment; polysulfide-sodium borohydride dual pretreatment, and polysulfide followed by polysulfide-sodium borohydride dual pretreatment two-stage pretreatments prior to kraft pulping. In the first modification, about 5% of the lost pulp yield (total 7%) caused by hemicellulose pre-extraction could be recovered with 15%-20% polysulfide pretreatment. Complete recovery (7%) was achieved with simultaneous pretreatment using 15% polysulfide and 0.5% sodium borohydride with 0.1% anthraquinone in polysulfide-sodium borohydride dual pretreatment. Two-stage pretreatment using recycled 15% polysulfide followed by simultaneous treatment of 6% polysulfide and 0.4%–0.5% sodium borohydride with 0.1% anthraquinone also achieved 100% yield recovery. Continuous recycling of 15% polysulfide employed in the two-stage process modification maintained its yield protection efficiency in a repeated recycling cycle. No significant changes in paper strength were found in handsheets prepared from the three process modifications, except for a minor reduction in tear strength.

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Managing total reduced sulfur emissions at a Canadian kraft pulp mill

TAPPI Journal ◽

10.32964/tj15.4.265 ◽

2016 ◽

Vol 15 (4) ◽

pp. 265-272 ◽

Cited By ~ 1

Author(s):

ROHAN BANDEKAR ◽

JIM FREDERICK ◽

JAROSLAV STAVIK

Keyword(s):

Direct Contact ◽

Black Liquor ◽

Pulp Mill ◽

Packed Bed ◽

Average Value ◽

Emission Limit ◽

Total Reduced Sulfur ◽

Reduced Sulfur ◽

Air Ingress ◽

Solids Content

This study addresses the challenges a dissolving-grade pulp mill in Canada faced in 2014 in meeting its total reduced sulfur (TRS) gas emission limit. These emissions from the recovery boiler exit are controlled by passing the boiler exit gas through a TRS scrubber system. The mill employs a cyclonic direct contact evaporator to concentrate black liquor to firing solids content. The off-gases from the direct contact evaporator flow to the effluent gas control system that consists of a venturi scrubber, a packed bed scrubber, and a heat recovery unit. Emissions of TRS greater than the regulated limit of 15 ppm were observed for a 4-month period in 2014. The level of emissions measured during this period was significantly higher than about 12 ppm, the expected average value based on historic experience. The problem persisted from mid-June 2014 until the annual mill shutdown in October 2014. The main TRS components detected and the performance of the Teller scrubber in capturing them are examined. Other potential causes for these emissions are identified, including mechanical problems such as broken packing in the TRS packed bed scrubber, broken baffle plates in the scrubber, and cyclone evaporator leaks causing air ingress. Repairs were carried out during the mill shutdown, which eliminated the TRS emissions problem.

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