scholarly journals The Optimization of Heat Exchanger Solidity for Coal-Fired Fluidized Bed Combustors

1979 ◽  
Author(s):  
G. Miller ◽  
V. Zakkay ◽  
S. Rosen
Keyword(s):  
New York ◽  
Heat Exchanger ◽  
Fluidized Bed ◽  
Working Fluid ◽  
Special Importance ◽  
Fluidized Bed Combustion ◽  
New York University ◽  
Efficient Extraction ◽  
Mass Flows ◽  
Fluidized Bed Combustor

The efficient extraction of a high-temperature working fluid from a coal-fired fluidized bed combustor depends, to a great extent, on the design of the immersed heat exchanger. Of special importance is the solidity of the cooling tubes immersed in the bed. The interaction between increasing solidity and the consequent degradation of proper fluidization and circulation is being studied at the New York University fluidized bed combustion facility. It is found that under certain conditions, the solidity of heat exchanger in the bed can be significantly increased and thus one can extract increased mass flows of clean working fluid. In addition, a variation in local solidity may be another mechanism for improving performance.

Experiments on Heat Exchanger Solidity for Coal-Fired Fluidized Bed Applications

1980 ◽  
Vol 102 (4) ◽  
pp. 731-735 ◽  
Author(s):  
G. Miller ◽  
V. Zakkay
Keyword(s):  
New York ◽  
Heat Exchanger ◽  
Fluidized Bed ◽  
Variable Parameter ◽  
Working Fluid ◽  
Special Importance ◽  
Fluidized Bed Combustion ◽  
New York University ◽  
Efficient Extraction ◽  
Fluidized Bed Combustor

The efficient extraction of a high-temperature working fluid from a coal-fired fluidized bed combustor depends, to a great extent, on the design of the immersed heat exchanger. Of special importance is the solidity of the cooling tubes immersed in the bed. The interaction between increasing solidity and the consequent degradation of proper fluidization and circulation is being studied at the New York University fluidized bed combustion facility. In a preliminary set of experiments it was found that under certain conditions, the solidity of heat exchanger in the bed may be significantly increased, giving designers an additional variable parameter.

Materials Selection for Metallic Heat Exchangers in Advanced Coal-Fired Heaters

1982 ◽  
Author(s):  
I. G. Wright ◽  
A. J. Minchener
Keyword(s):  
Heat Exchanger ◽  
Fluidized Bed ◽  
Plant Size ◽  
Working Fluid ◽  
High Temperature Strength ◽  
Fluid Temperature ◽  
Alloy 800 ◽  
Nickel Base ◽  
Fluidized Bed Combustor

The application of advanced coal-fired heaters to heat the working fluid for a closed-cycle gas turbine provides some challenging problems for the selection of metallic heat-exchanger materials. The requirements of a working fluid temperature bf 1550 F (1116 K) at a pressure of 300–600 psig (2.07–4.14 MPa/m2) necessitate the alloys used for the hottest part of the heat exchanger must possess high-temperature strength in excess of that available in widely used alloys like alloy 800. The maximum-duty alloys must therefore be selected from a group of essentially nickel-base alloys for which there is scant information on long term strength or corrosion resistance properties. The susceptibility to corrosion of a series of candidate heat exchanger alloys has been examined in a pilot plant size fluidized-bed combustor. The observed corrosion behavior confirmed that at certain locations in a fluidized-bed combustor nickel-base alloys are susceptible in varying degrees to rapid sulfidation attack, and must be protected by coating or cladding.

Materials Selection for Metallic Heat Exchangers in Advanced Coal-Fired Heaters

1983 ◽  
Vol 105 (3) ◽  
pp. 446-451 ◽  
Author(s):  
I. G. Wright ◽  
A. J. Minchener
Keyword(s):  
Heat Exchanger ◽  
Fluidized Bed ◽  
Plant Size ◽  
Working Fluid ◽  
High Temperature Strength ◽  
Fluid Temperature ◽  
Alloy 800 ◽  
Nickel Base ◽  
Fluidized Bed Combustor

The application of advanced coal-fired heaters to heat the working fluid for a closed-cycle gas turbine provides some challenging problems for the selection of metallic heat exchanger materials. The requirements of a working fluid temperature of 1550°F (1116 K) at a pressure of 300–600 psig (2.07–4.14 MPa/m2) necessitate that the alloys used for the hottest part of the heat exchanger possess high-temperature strength in excess of that available in widely used alloys like alloy 800. The maximum-duty alloys must therefore be selected from a group of essentially nickel-base alloys for which there is scant information on long-term strength or corrosion resistance properties. The susceptibility to corrosion of a series of candidate heat exchanger alloys has been examined in a pilot plant size fluidized-bed combustor. The observed corrosion behavior confirmed that at certain locations in a fluidized-bed combustor nickel-base alloys are susceptible in varying degrees to rapid sulfidation attack, and must be protected by coating or cladding.

Experimental Study on Compact External Heat Exchanger for a 4 MWth Circulating Fluidized Bed Combustor

2013 ◽  
Vol 448-453 ◽  
pp. 3259-3269
Author(s):  
Zhi Wei Li ◽  
Hong Zhou He ◽  
Huang Huang Zhuang
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Fluidized Bed ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Cooling Water ◽  
External Heat ◽  
Circulating Ash ◽  
Fluidized Bed Combustor ◽  
External Heat Exchanger

The characteristics of the external heat exchanger (EHE) for a 4 MWth circulation fluidized bed combustor were studied in the present paper. The length, width and height of EHE were 1.5 m, 0.8 m and 9 m, respectively. The circulating ash flow passing the heating surface bed could be controlled by adjusting the fluidizing air flow and the heating transferred from the circulating ash to the cooling water. The ash flow rate passing through the heat transfer bed was from 0.4 to 2.2 kg/s. The ash average temperature was from 500 to 750 °C. And the heat transfer rate between the ash and the cooling water was between 150 and 300 W/(m2·°C). The relationships among the circulating ash temperature, the heat transfer, heat transfer rate, the heat transfer coefficient and the circulating ash flow passing through the heating exchange cell were also presented and could be used for further commercial EHE design.

A Simulation Study for Fluidized Bed Combustion of Petroleum Coke With CO2 Capture

2003 ◽  
Author(s):  
Jinsheng Wang ◽  
Edward J. Anthony ◽  
J. Carlos Abanades
Keyword(s):  
Power Generation ◽  
Fluidized Bed ◽  
Petroleum Coke ◽  
Co2 Capture ◽  
Low Cost ◽  
Volatile Content ◽  
Fluidized Bed Combustion ◽  
High Carbon ◽  
Overall Efficiency ◽  
Fluidized Bed Combustor

Petroleum coke is regarded as a difficult fuel because of its high sulphur content and low volatile content. However, its low price and increased production, means that there is a powerful economic stimulus to use it for power generation. In this work, a process simulation has been performed as part of a feasibility study on the utilization of petroleum coke for power generation with low-cost CO2 capture. The proposed system employs a pressurized fluidized bed combustor and a calciner. In the combustor itself, the petroleum coke is burned and most of the CO2 generated is captured by a CaO sorbent under pressurized condition to form CaCO3. The CaCO3 is transported into the calciner where limited proportion of the petroleum coke is burned with pure O2, and calcines the spent sorbent back into CaO and CO2. A nearly pure CO2 stream is obtained from the calciner for subsequent disposal or utilization. The predicted overall efficiency of the combustion is near 40%. The proposed system would also be suitable for firing other high carbon and low ash fuel, such as anthracite.

Modelling Fuel and Sorbent Attrition During Circulating Fluidized Bed Combustion of Coal

2003 ◽  
Author(s):  
D. Barletta ◽  
A. Marzocchella ◽  
P. Salatino ◽  
S. G. Kang ◽  
P. T. Stromberg
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Surface Wear ◽  
Fluidized Bed Combustion ◽  
Coal Fuel ◽  
Primary Fragmentation ◽  
The Impact ◽  
Constitutive Parameters ◽  
Fluidized Bed Combustor ◽  
Circulating Fluidized Bed Combustion

A simulation model of a circulating fluidized bed combustor, based on a one-dimensional description of bed hydrodynamics and a simplified formulation of the population balance equation on fuel and bed solids, has been set up. The model specifically aims at assessing the extent of fuel and sorbent attrition during circulating fluidized bed combustion of coal. Fuel attrition is modelled as a function of carbon loading and of the relevant operating variables while taking into account primary fragmentation of coal and secondary fragmentation and attrition by surface wear of its char. Modelling of sorbent attrition accounts for primary fragmentation of limestone upon calcination as well as attrition by surface wear of lime. To this end time- and conversion-dependent attrition rate is averaged over the sorbent particle lifetime in the reactor. Attrition submodels and their constitutive parameters are based on previous work by the research group in Naples. Coal char combustion and lime sulphation are modelled considering intrinsic reaction kinetics as well as boundary layer and intraparticle diffusion of reactants. The impact of attrition phenomena on the performance of the fluidized bed combustor is characterized by looking at carbon combustion efficiency, at sulphur capture efficiency, at the balance between bottom and fly ashes. The influence of operating parameters like fuel particle size, Ca/S ratio, gas superficial velocity, extent of air staging is investigated. The sensitivity of results of model computations to the parameters expressing fuel and sorbent attrition is presented and discussed.

Experimental Studies on Combustion of Cattle Manure in a Fluidized Bed Combustor

1987 ◽  
Vol 109 (2) ◽  
pp. 49-57 ◽  
Author(s):  
K. Annamalai ◽  
M. Y. Ibrahim ◽  
J. M. Sweeten
Keyword(s):  
Fluidized Bed ◽  
Fossil Fuels ◽  
Experimental Studies ◽  
Heat Content ◽  
Fluidized Bed Combustion ◽  
Volatile Solids ◽  
Combustion Technology ◽  
Solids Content ◽  
Combustion Tests ◽  
Fluidized Bed Combustor

Manure from cattle feedlots is a renewable energy source which has the potential of supplementing the existing fossil fuels. But the heat content of manure is rather low. Since, the fluidized bed combustion technology has been used for the energy conversion of marginal fuels, such a technology is being explored for the combustion of feedlot manure. A fluidized bed combustor of 0.15 m (6 in.) diameter was used for the combustion tests on manure. Experiments were conducted with −20 to +20 percent excess air and at bed temperatures ranging from 600°C (1112°F) to 800°C (1472°F). Experimental data revealed that the gasification efficiencies ranged from 90 to 98 percent, while the combustion efficiencies varied from 45 to 85 percent. Higher combustion efficiencies were obtained with decreased volatile solids content of manure. The low combustion efficiencies are attributed to the limited residence time available for the volatiles to burn within the reactor.

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