Standpipes and Nonmechanical Valves

Knowlton, T

doi:10.1201/9780203912744.ch21

Cited by 4 publications

(5 citation statements)

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“…The separation efficiencies of the cyclones and the CS are given in Table 4. Values using typical correlations from the literature are used for the cyclones [39,40]. The efficiency of the particle separation in the CS is based on experimental results [24].…”

Section: Process Model and Simulationsmentioning

confidence: 99%

Modeling and Simulation of an Industrial-Scale 525 MWth Petcoke Chemical Looping Combustion Power Plant

et al. 2023

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This paper presents the modeling and simulation of an industrial-scale chemical looping combustion (CLC) power plant, including all process units (reactors, flue gas treatment units, heat integration, steam cycle, and CO2 compression train). A model of a 525 MWth CLC power plant was built using a rigorous representation of the solid fuel and oxygen carrier. Petcoke was considered the main fuel of interest in this study, and it is compared with other solid fuels. The flue gas compositions obtained with the model show that cleanup units are mandatory to comply with CO2 quality requirements. High levels of flue gas treatment, including 97.1% deNOx and 99.4% deSOx, are needed to achieve typical specifications for captured CO2. This is mainly due to the high level of contaminants in the fuel, but also to the absence of nitrogen in the CLC flue gas, thus resulting in higher concentrations for all substances. The high level of flue gas treatment is thus one of the important challenges for solid fuel combustion in CLC. The overall CO2 capture efficiency of the plant is estimated to be as high as 94%. Regarding the energy balance, a process net efficiency of 38% is obtained. Comparing the results with other available technologies shows that CLC exhibits one of the highest net plant efficiencies and carbon capture rates. CLC is thus a promising technology to produce clean energy from solid fuels. Finally, based on a sensitivity analysis, it is shown that process efficiency is mainly affected by the design and performance of the CLC furnace, the steam injection rate in the fuel reactor, the char separation efficiency, and the excess oxygen in the air reactor.

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Section: Process Model and Simulationsmentioning

confidence: 99%

Modeling and Simulation of an Industrial-Scale 525 MWth Petcoke Chemical Looping Combustion Power Plant

et al. 2023

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“…There are four basic types of standpipes. Three of them are used in circulation systems [3]. The four basic types of standpipes are shown in Tab.…”

Section: Types Of Standpipesmentioning

confidence: 99%

“…1) adjusts the pressure drop across it by varying the level of the fluidized solids (commonly referred to as seal height) in the standpipe. An underflow, packed-bed standpipe adjusts the pressure drop across it by varying the relative gas-solids velocity in the standpipe [3].…”

Section: Types Of Standpipesmentioning

confidence: 99%

How Underflow Standpipes Adjust to Maintain Pressure Balance Around a Circulation Loop

Knowlton

Karri

2022

Chemie Ingenieur Technik

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The standpipe has become a standard element of most circulation loops. In the past, standpipes have been thought of as a device to only allow solids to transfer from a low to a higher-pressure region. However, it also has another function in a solids circulation loop. It is also the device that adjusts its operation to balance the pressure around the solids circulation loop. An overflow standpipe adjusts the pressure drop across it by raising or lowering the solids level in the standpipe. However, the operation of the underflow standpipe is more complex. This self-adjusting function can cause underflow standpipe pressure drops to be negative, which seems counter-intuitive. How an underflow standpipe operating with a negative pressure build can occur in a circulation loop is described below using two commercial unit examples as illustrations of this phenomenon.

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“…They have no moving mechanical parts, which are subject to wear and seizure. This feature is especially beneficial when operating at elevated temperatures and pressures . These are also inexpensive and can be fabricated in-house because of their construction in the form of simple pipes and fittings.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Solid Discharge Rate from a Nonmechanical Solid Feeding System

Bhowmick

Baveja

Varshney

et al. 2013

Ind. Eng. Chem. Res.

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A nonmechanical solid feeding device uses aeration gas in combination with its geometrical shape to cause particulate solids to flow through it. Serious erosion of moving parts, high solid flow rate requirement, and high operating temperature preclude the use of mechanical solid feeders. A nonmechanical solid feeding system was designed and developed in the Chemical Engineering Division of Bhabha Atomic Research Centre for continuous solid addition to the fluidized bed. The controlled continuous solid addition fulfills various purposes − maintain proper particle size distribution inside fluidized bed, provide make up for entrained solids, and supply solid reactant where solids are consumed in reaction. A solid circulation vessel which works on the principle of compartmented fluidized bed was the heart of this solid feeding system. It consists of two compartments (main and riser), and the compartments were connected through an orifice. Solid discharge rate from solid circulation vessel was regulated by adjusting the fluidizing air flow rates to main and riser compartments and solid level in the main compartment. Theoretical and experimental investigations were carried out to evaluate performance characteristics of solid circulation vessel. Experimental results showed that a wide range of solid discharge rate (6−80 kg/h) could be achieved by changing aeration rates of two compartments and fluidized solid level in the main compartment. The experimental data were used to develop a correlation between solid mass flow rate through an orifice and pressure drop across an orifice. A mathematical model was also developed to predict the solid discharge rate from solid circulation vessel for a range of operating parameters.

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Standpipes and Nonmechanical Valves

Cited by 4 publications

References 0 publications

Modeling and Simulation of an Industrial-Scale 525 MWth Petcoke Chemical Looping Combustion Power Plant

Modeling and Simulation of an Industrial-Scale 525 MWth Petcoke Chemical Looping Combustion Power Plant

How Underflow Standpipes Adjust to Maintain Pressure Balance Around a Circulation Loop

Experimental Study on Solid Discharge Rate from a Nonmechanical Solid Feeding System

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