Fluidized Bed Test Rig Research Articles

Heat transfer behavior of an immersed tube with sCO2 working fluid in a hot fluidized bed at high pressure

• A pilot-scale pressurized fluidized bed test rig with sCO 2 closed cycle was built. • Heat transfer behavior of an immersed tube with sCO 2 working fluid has been studied. • A bed-to-tube heat transfer model was proposed for pressurized fluidized bed. • Buoyancy can explain the heat transfer deterioration of sCO 2 . In this work, a pilot-scale pressurized fluidized bed test rig was built to test the heat transfer performance between the supercritical CO 2 (sCO 2 ) loaded immersed tube with the dense bed. Results showed that the bed-to-tube heat transfer coefficient (HTC) in CO 2 atmosphere was slightly larger than that in air atmosphere. The HTC increased with the increase of pressure and bed temperature, respectively. The increase of pressure did not change the circumferential distribution of HTC, but the increase of fluidization number improved it. A bed-to-tube heat transfer model was proposed on the basis of the partial heat penetration theory with the accuracy in ±25 %. For the heat transfer of sCO 2 within the immersed tube deteriorated due to the buoyancy effect.

Chemical looping gasification of torrefied woodchips in a bubbling fluidized bed test rig using iron-based oxygen carriers

Chemical looping gasification is an efficient technology to convert biomass into valuable syngas. The iron-based oxygen carriers are a promising option for large-scale commercial applications due to their low cost and environmentally-friendly properties. The present study aims at evaluating the performance of the syngas production from the chemical looping gasification of torrefied woodchips in a pilot-scale bubbling fluidized bed reactor using iron ore and ilmenite as oxygen carriers. The effects of the operating parameters were investigated in this study. The results show that an increase in operating parameters could favor the process performance. Carbon conversion efficiency and the yields accelerate at high operating conditions. Carbon conversion efficiency showed a maximum value of 91.42% for iron ore at the ratio of oxygen carrier-to-biomass of 6, while the gas yield reaches the peak at SBR of 1.4 for ilmenite. The addition of steam in biomass chemical looping gasification improves hydrogen production and syngas quality in the product gas. Despite ilmenite provides better performance for hydrogen production, it characterizes by a lower reactivity compared to iron ore. It is also found that iron ore performs better at lower values of steam-to-biomass ratios and temperatures, while ilmenite shows good results at higher those parameters. • Chemical looping gasification of torrefied woodchips using iron-based oxygen carriers was investigated experimentally. • Higher ratios of oxygen carrier-to-biomass do not favor syngas production. • Higher gasification temperatures significantly enhance the process performance. • The content and yield of H 2 in the product gas are proportional to the ratio of steam-to-biomas. • Superficial velocity considerably affects the performance of chemical looping gasification.

Online measurement of particle charge density in a gas-solid bubbling fluidized bed through electrostatic and pressure sensing

Abstract Electrostatic phenomena widely exist in various olefin polymerization fluidized bed reactors, due to the continuous collision and friction of dielectric particles and the low-humidity reaction environment. The measurement of particle charge density is essential for monitoring and controlling the electrostatic level as well as probing the hydrodynamic characteristics in a fluidized bed. In this work, a non-intrusive online measurement system, employing ring-shaped sensing electrodes and a pressure transducer, is designed and implemented on a fluidized bed test rig. A modified model considering the influence of spatial sensitivity of the electrodes is proposed to predict the particle charge density in the fluidized bed, based on the measured induced electrostatic current and pressure drop signals. Experimental results have demonstrated that the induced electrostatic current and pressure drop signals show remarkable similarity, with the two PSDs both mainly distributed within 0.5–5 Hz, which indicates close relationship between the two signals. The predicted particle charge density increases with the superficial gas velocity and decreases with the injection content of liquid anti-static agent (LAA), showing the same variation tendencies as that measured through a Faraday cup. When the electrode width is 20 mm, the mean absolute relative errors for the direct method, area method and envelope method are 12.7%, 14.7% and 13.5%, respectively, indicating that the direct method is the most reliable signal processing approach proposed in this work.

Pyrolysis Of Saudi Arabian Date Palm Waste: A Viable Option For Converting Waste Into Wealth

Saudi Arabia has about 23 million palm trees and it is the second largest producer of dates. The biomass from the trimmed branches of palm trees amount to more than 200,000 tons/year. This biomass waste can be used to produce many commercial products. There are several relevant technologies for conversion of biomass and solid wastes into higher value products. The starting point of the project is the pretreatment of palm solid wastes. Thermogravimetric analysis has been done to understand the pyrolysis behavior of palm date wastes. A fluidized bed (FB) has been designed and to study hydrodynamics and develop optimum conditions for the pyrolysis of palm wastes. A novel fluidized bed test rig has been designed and fabricated to carry out the pyrolysis of palm wastes. The pyrolysis is used to produce activated carbon and the waste can also be readily converted to liquid phenolic products. Liquid products are particularly interesting because they have a higher energy density and can be used to produce adhesives as well as biofuels for use in power generation and transport sector. Experimental results have indicated potential opportunities of using the date biomass waste as a potential fuel in the Kingdom of Saudi Arabia. (Ahmad Hussain, Aamir Farooq, Mohammad Ismail Bassyouni, Hani Hussain Sait, Mahmoud Abo El-Wafa, Syed Waheedul Hasan, Farid Nasir Ani. Pyrolysis Of Saudi Arabian Date Palm Waste: A Viable Option For Converting Waste Into Wealth. Life Sci J 2014;11(12):667-671). (ISSN:1097-8135). http://www.lifesciencesite.com . 126

New CO2 Capture Process with Gas–Liquid–Solid Three-Phase Circulating Fluidized Bed

The idea of applying the gas–liquid–solid (GLS) three-phase circulating fluidized bed to CO2 capture by aqueous ammonia is proposed in this work. A three-phase circulating fluidized bed test rig wa...

Effect of Phosphorus on Desulfurization of Limestone during Sewage Sludge Combustion

Experiments of desulfurization of limestone during sewage sludge combustion with different phosphorus contents were conducted in a 15 kW circulating fluidized bed test rig to investigate the effect of phosphorus on desulfurization. Chemical thermodynamic analysis was performed to compare with the experimental results. Chemical thermodynamic analysis indicates that relatively high content of phosphorus in sewage sludge will affect desulfurization because calcium will first react with phosphorus and then the rest is available for reaction with sulfur, which agrees well with the experimental results. The experimental results also show that relatively high content of phosphorus in sewage sludge affects self-desulfurization of calcium in sewage sludge and desulfurization of limestone. The effect of phosphorus on desulfurization must be taken into account during sewage sludge combustion.

Numerical and Experimental Investigation of Bubbling Gas–Solid Fluidized Beds with Dense Immersed Tube Bundles

Numerical simulations of gas–solid bubbling fluidized beds with and without dense immersed horizontal tubes were performed using the Eulerian-Eulerian Two Fluid Model (TFM) and applying the Kinetic Theory of Granular Flow (KTGF). The results were compared with experimental data obtained from a pseudo-2D fluidized bed test rig using a developed digital image analysis technique (DIAT). The influences of dense immersed horizontal tubes on bed properties (bed pressure drop and expansion ratio) and bubble hydrodynamics (bubble size, rise velocity, aspect ratio, and shape factor) were investigated numerically as well as experimentally. In the first part grid sensitivity with different mesh sizes was checked and effects using 2D and 3D domains were examined. Simulations with 3D domains gave better agreement with experimental data but were seen to be computationally expensive. For conducting intensive parametric studies of fluidized bed behavior the use of 2D domains remains indispensable. In the second part it could be shown that dense tube arrangements in the fluidized bed lead to repeated bubble break-up and coalescence in the tube bank region and therefore to fluctuating values of bubble size, rise velocity, aspect ratio, and shape factor. For different superficial velocities similar results were found which shows the high influence of dense immersed tubes on fluidized bed behavior. In addition no significant differences between staggered and in-line tube arrangement were observed. In general the simulations based on the Two Fluid Model showed good agreement with the experimental results.

Experimental study on flue gas purifying of MSW incineration using in-pipe jet adsorption techniques

This paper presents the experimental research process and results about flue gas purifying of municipal solid wastes (MSW) incineration using in-pipe jet adsorption techniques. MSW incineration was carried out in a fluidized bed test rig, and the flue gas purifying was carried out in an in-pipe jet adsorption test rig. The experimental results are as follows: when the feedstock of activated carbon is 1.6g/Nm(3), the desulfurization efficiency is 83%, the denitrification efficiency is 41%, and the dechlorination efficiency is 27%. The order of purifying effect of the three kinds of adsorbents on acidic gases from MSW incineration is activated carbon>activated bauxite>kaolin. Comparison of adsorption capabilities of the three kinds of adsorbents to heavy metals shows that activated carbon is the best additive to remove Cd, Pb and Cu, kaolin is inferior, and activated bauxite is the worst one. However, activated bauxite is the best additive to remove Hg, and it can remove Cd effectively. PAHs in fly ash are dominated by three-, four-, and five-ringed PAHs, and PAHs in the flue gas mainly include three- and four-ringed PAHs. When the injected quantity of additive is constant, the order of cleaning effect on PAHs is kaolin>activated carbon>activated bauxite. These three kinds of adsorbents have different purifying effects on acidic gases, heavy metals and PAHs in the flue gas from MSW incineration. In general, activated carbon has a better adsorption capability.

Erosion–corrosion of Fe- and Ni-based tubes and coatings in a fluidized bed test rig during exposure to HCl- and SO 2-containing atmospheres

Abstract Tubes made from five commercial alloys (Fe9Cr1Mo, 304L, Esshete 1250, 353 MA and Inconel 625) as well as two coating materials (Inconel 625 and Metco 8443) deposited on low alloyed steel tubes were exposed to different atmospheres in a laboratory fluidized bed test rig at 550 °C for 3 weeks (504 h). The atmospheres were air, air + 50 ppm HCl and air + 50 ppm SO 2 . Excluding the Metco 8443 coating, all materials show the lowest wastage rate in the SO 2 -containing atmosphere. For all exposure conditions, the best overall performance is shown by the Fe9Cr1Mo alloy. The circumferential wastage profiles recorded on tubes exposed in air and air + 50 ppm HCl show an erosion pattern with two maxima (Type A behaviour), while the tubes recorded in the SO 2 -containing atmosphere display only one maximum (Type B behaviour).

Study on Emission Control of NOx and N2O in a Fly‐ash Recycle Fluidized Bed Test Rig

AbstractExperiments on NOx and N2O release characteristics and emission control were studied in a fly‐ash recycle fluidized bed test rig. The total height of the fluidized bed is 4.4m. The fluidization section is 1.2m high with a cross‐section 0.23mx0.23m. The freeboard is 3.0m high with a cross‐section 0.460mx0.345m. The coal‐fired weight of the test rig is 30 kg/h, and coal is fed by a screw feeder. Fine ash is collected by a cyclone and recycled to the bed surface through a J‐valve, slag is then removed from the bottom. An oil‐fired start‐up burner is also used. Test fuels are Xuzhou bituminite and Kenan anthracite from China with particle range of 0‐8mm. When the bed temperature rises, NOx increases and N2O decreases. At the same temperature, N2O emission of bituminite is less than that of anthracite. While the secondary air ratio reached 15% under staged combustion, NOx emission decreased to 14% and N2O emission decreased to 24%. As the Ca/S molar ratio increases, NOx emission also increases while N2O emission decreases. Ammonia injection decreases NOx emission significantly, but it has no effect on the emission of N2O.

Strong HCl effect on tube wastage in a simulated bubbling fluidized bed environment

This paper reports initial results from a laboratory fluidized bed test rig where HCl gas was incorporated into the bed. The rig simulates the particle hammering interactions between in-bed particles and tubes within bubbling fluidized bed combustors (BFBCs). A significant increase in material wastage rates in the presence of HCl was found at 450°C as well as at 200°C. The detrimental effect decreased with decreasing HCl concentration.

Fluidized-bed char from Australian coals

The effects of process variables and coal characteristics on the yields and properties of char made from 15 coals in a 50 lb/h (25 kg/h) fluidized-bed test rig at 500 °C were examined. Carbonization was virtually complete within 20 min. Char yield was maximal when fluidizing with air at an oxygen/coal ratio ( w w ) of 0.06; higher reactant ratios and longer residence times resulted in loss through combustion without affecting the volatilematter content (ash-free basis) of the char. Char yield was about 2% less when fluidizing with recycle gas; the presence of oxygen inhibited devolatilization. Chars from bituminous coking coal (crucible swelling number ⩾ 1) had low bulk densities (10–20 lb/ft 3 ; 160–320 kg/m 3 ) and were easy to grind (Hardgrove grindability index 140–160). Expressions for predicting char yield and properties from coal analyses are derived.