scholarly journals Experimental and computational evaluation of a gas-solid suspension density distribution under circulating fluidized bed conditions

2021 ◽  
Vol 2130 (1) ◽  
pp. 012025
Author(s):  
P Mirek
Keyword(s):  
Density Distribution ◽  
Combustion Chamber ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Multiphase Model ◽  
Thermal Loads ◽  
Bottom Part ◽  
Boiler Load ◽  
Suspension Density ◽  
Eulerian Multiphase Model

Abstract The paper presents the results of operational measurements of the suspension density distribution in the 966 MWth supercritical Circulating Fluidized Bed boiler. The tests were carried out for four different unit thermal loads, i.e. 40, 60, 80, and 100% MCR. The conducted operational measurements showed that the suspension density distribution of the particulate material in the combustion chamber of the CFB boiler has the form of an exponential curve with maximum values occurring in the bottom part of the furnace. On the basis of the operational data, an attempt was made to reflect the suspension density distribution in the combustion chamber of the boiler using the ANSYS CFD software. The calculations were carried out using the Eulerian multiphase model in an unsteady state condition. As revealed by the simulations, the Eulerian multiphase model allows for a quantitative representation of the suspension density distribution of the granular material only for the maximum boiler load. For other thermal loads, quantitative representation of experimental distributions of suspension density using the Eulerian method is possible except for the dense region.

The effect of circulating fluidized bed boiler load on the emission of mercury

2019 ◽  
Vol 92 (6) ◽  
pp. 1800-1806 ◽  
Author(s):  
Michał Wichliński ◽  
Grzegorz Wielgosz ◽  
Rafał Kobyłecki
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Circulating Fluidized Bed Boiler ◽  
Boiler Load

scholarly journals Production and Characterization of Bio-oil from Bio-mass by Circulating Fluidized Bed Pyrolysis Reactor

1970 ◽  
Vol 46 (3) ◽  
pp. 313-322 ◽  
Author(s):  
ATMK Hasan ◽  
M Mohiuddin ◽  
MB Ahmed ◽  
IJ Poly ◽  
M Asadullah ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Biomass Conversion ◽  
Fixed Bed ◽  
Acid Value ◽  
Reactor System ◽  
Efficient Production ◽  
Bottom Part ◽  
Bio Oil ◽  
Pyrolysis Reactor

The objective of the present work is to install a modified suitable and compatible reactor system for the efficient production of renewable liquid fuel (bio-oil) from agro-based bio-mass. This new type of reactor system contains a combustor connected with the upper end of the reactor chamber. The bottom end of the reactor is connected with the bottom part of the combustor by a stainless steel pipe through which hot sand is circulated by the force of air pump. Thus, effective heat transfer from the continuously circulated heated sand as well as efficient biomass conversion into the reactor can be obtained. In this work, jute stick and bagasse abundantly available in Bangladesh were pyrolyzed separately in a continuous feeding circulating fluidized bed reactor at around 500°C for bio-oil production. The total bio-oil yields from bagasse and jute stick were about 69.5 wt% and 68.2 wt% respectively, which are higher than the yields obtained from fixed bed pyrolysis reactor. The total yields of char contents were 19.4 wt% and 21.7wt% after complete pyrolysis of bagasse and jute stick respectively, which are less than that of char yields obtained from fixed bed pyrolysis reactor. Physical and chemical analyses of bio-oils were carried out by conventional methods. The density, viscosity, pH, acid value, water, lignin, solid and ash contents of bio-oils obtained from both jute stick and bagasse were found to be 1.1 g/cc, 3.1 cp, 4.1, 126.3 mgKOH/g, 14.0 wt%, 2.5wt%, 0.05wt%, 0.03wt%, and 1.12 g/cc, 3.2cp, 4.0, 127.1 mgKOH/g, 13.0 wt%, 2.5wt%, 0.015wt%, 0.025wt%, respectively. Key words: Renewable energy; Bio-mass; Bio-oil; Pyrolysis; Fluid bed circulating reactor DOI: http://dx.doi.org/10.3329/bjsir.v46i3.9036 BJSIR 2011; 46(3): 313-322

Combustion of Refinery Residues in a CFB-Combustor: Measurement of Intermediate Species Using FTIR

2003 ◽  
Author(s):  
Christian Barczus ◽  
Bjo¨rn Henning ◽  
Viktor Scherer
Keyword(s):  
Combustion Chamber ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Combustion Process ◽  
Thermal Capacity ◽  
Liquid Fuels ◽  
Gaseous Species ◽  
Nox Formation ◽  
Secondary Air ◽  
Fluidized Bed Combustor

Investigations have been performed to show the feasibility of burning refinery residues (calcined petroleum coke and liquid residues) in a circulating fluidized bed combustor. These experiments were done in a CFBC system with a thermal capacity of 100 kW. The unit has been equipped with an additional dosing system for liquid fuels including a newly developed fuel lance. The pollutant formation characteristics are determined using axial profile measurements at 19 different ports along the combustion chamber. To optimize the combustion process and to minimize gaseous pollutants, several operating parameters of the system are varied independently. These parameters are the primary to secondary air ratio, the global air to fuel ratio, the residence time in the primary zone, the overall temperature of the combustion chamber and the Ca/S ratio. Measurements of the flue gas components O2, CxHy, CO, CO2, H2, NOx, N2O, NH3 and SO2 are performed by standard gas analysing techniques. It is important to note that the system is equipped with a Fourier Transform Infrared Spectrometer (FTIR) to qualitatively and quantitatively determine selected gaseous species which are essential for the formation and consumption of N2O and other pollutants. The gas species measured by FTIR-Spectroscopy are CH4, C2H2, C2H4, C2H6, C3H6 and C3H8. Also the important precursors for the NOx-formation HCN and NH3 are examined with the FTIR-Spectrometer. The investigations demonstrate that (liquid) refinery residues can be burned successfully as a monofuel within the circulating fluidized bed combustor. The emissions of all pollutants detected are at a low level.

Gas Concentration Measurements in the Combustion Chamber of the 235 MWe Circulating Fluidized Bed Boiler Turow No. 3

2005 ◽  
Author(s):  
E.-U. Hartge ◽  
M. Fehr ◽  
J. Werther ◽  
T. Ochodek ◽  
P. Noskievic ◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Wall Layer ◽  
Front Wall ◽  
Circulating Fluidized Bed Boiler ◽  
Penetration Length ◽  
Cross Sectional ◽  
Gas Concentration ◽  
High Concentrations

Local measurements of concentrations of O2, CO2, CO, NO and SO2 were carried out inside the 235 MWe circulating fluidized bed boiler no. 3 Turow power plant. The combustion chamber had a cross-sectional area of 21.1 × 9.9 m2 and a height of 43 m. Water-cooled probes with a length of 4.7 m were used to take samples from inside the boiler. 20 ports in 5 different heights were used to introduce the probes. The penetration depth inside the boiler was up to 3 m. The sampled gas was led to online analyzers. Even though the number of ports and the penetration length was not sufficient to get a full 3-D mapping of the concentrations the measured horizontal and vertical gas concentration profiles of NO, CO, CO2, O2 and SO2 clearly indicate a core/annulus structure with a wall layer thickness of about 0.5–1 m. Significant differences are observed between gas concentrations near the front wall and those near the rear wall which indicate an uneven distribution of fuel. One consequence is the formation of plumes with high concentrations of CO, NO, CO2 and SO2 near the front wall which extend up to the exit region. The fact that nevertheless the stack emissions are still below the legal limits may be attributed to the excellent performance of the cyclones as gas mixers and post combustion reactors.

Cross Sectional Suspension Density along the Height of a CFB Riser under Fixed and Variable Bed Inventory Conditions

2011 ◽  
Vol 361-363 ◽  
pp. 1882-1886
Author(s):  
Jiraroch Somjun ◽  
Anusorn Chinsuwan
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Average Diameter ◽  
Sectional Area ◽  
Cold Model ◽  
Cross Sectional ◽  
Density Profiles ◽  
Suspension Density ◽  
Bed Material ◽  
Cross Sectional Average

Experiments were performed in a cold model circulating fluidized bed riser having a cross sectional area of 100 x100 mm2 and a height of 4800 mm. Sand having an average diameter of 231m was used as the bed material. The cross sectional average suspension density along the height of the circulating fluidized bed system with a smooth exit was investigated under fixed and variable bed inventory conditions. A model is proposed for predicting the density profiles in the two conditions.

Process Simulation of Oil Shale Circulating Fluidized Bed Boiler Based on Aspen Plus

2012 ◽  
Vol 614-615 ◽  
pp. 49-52
Author(s):  
Qing Wang ◽  
Hai Bo Long ◽  
Hong Peng Liu ◽  
Zhi Feng Wang
Keyword(s):  
Fluidized Bed ◽  
Flue Gas ◽  
Oil Shale ◽  
Circulating Fluidized Bed ◽  
Circulation System ◽  
Performance Parameters ◽  
Gas Emission ◽  
Boiler Load ◽  
Cfb Boiler ◽  
Experimental Values

A model for the combustion of oil shale in the 65t/h circulating fluidized bed (CFB) boiler was developed, consisting of oil shale combustion, steam-water and ash circulation system, calculating the O2 and RO2 content of flue gas emission under three kinds of oil shale combustion in 65t/h CFB boiler. The calculated results indicate that the simulation values are consistent with the experimental values. Effect of boiler load on the temperature of furnace, flue gas emission, inlet and outlet flue gas of economizer was discussed based on the model. Boiler load on the increase results in a increase in temperature of furnace, flue gas emission, inlet and outlet flue gas of economizer. The main performance parameters of 65t/h oil shale CFB boiler system were discussed and preliminarily predicted by the model.

scholarly journals Effect of Connection Resistance between Cyclones and Backpass on Furnace Solids Suspension Density Profile and Circulation Rates in CFB

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6162
Author(s):  
Guanwen Luo ◽  
Leming Cheng ◽  
Liyao Li ◽  
Junfeng Wang ◽  
Xiaoguo Jiang ◽  
...  
Keyword(s):  
Density Distribution ◽  
Circulating Fluidized Bed ◽  
Resistance Coefficient ◽  
Circulation Rate ◽  
Suspension Density ◽  
Solids Suspension ◽  
Overall Resistance ◽  
Fluidized Bed Boilers ◽  
Resistance Coefficients ◽  
Branch Resistance

The connection section between cyclones and backpass is an important configuration in multi-cyclone circulating fluidized bed boilers (CFB). In this work, the resistance coefficient of different connection modes, and connection resistance distribution from each cyclone outlet to backpass (connection branch) in one mode are defined and calculated, in order to investigate their effects on furnace solids suspension density distribution and circulation rates. Three connection modes with different overall resistance coefficients were tested experimentally and analyzed by a 1.5-dimensional model in a four-cyclone scaling CFB apparatus. Both experimental and theoretical results show that, with larger overall resistance of a connection, there are more solids suspended in the furnace bottom and fewer in the top section. The investigation of the C-type connection has revealed that when the branch resistance of the connection decreases from branch No. 1–4, the solids suspension density and circulation rate from corresponding solids recycle loops (No. 1–4) increase. Moreover, the non-uniformity of connection branch resistance distribution will lead to uneven lateral solids suspension density distribution and circulation rates allocation. This effect is enhanced by growing superficial velocity.

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