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The interaction of calcination and sulfation in the simultaneous calcination/sulfation of limestone sorbent under circulating fluidized bed boiler conditions was studied. A specially designed constant-temperature reactor which can stop the reaction at a given time was employed. When limestone entered the furnace of mixed gases of CO2, O2, SO2, etc., its weight went down first, then up, so there was...
The use of biomass templating materials with a cheap production method as an enhanced sorbent for CO2 uptake has been proposed recently. However, the attrition and fragmentation behaviour of this type of material, which is a vital parameter for calcium looping sorbents, has not yet been investigated in detail. In this work the fragmentation behaviour of biomass-templated sorbents is investigated....
Co-firing biomass and coal under oxy-fuel combustion in a circulating fluidized bed combustor (CFBC) holds the potential for negative CO2 emission into the atmosphere and is a promising technology to realized atmospheric CO2 reduction. Experiments co-firing coal and three kinds of Chinese biomass, i.e. rice husk (RH), wood chips (WC) and dry wood flour (WF) under oxy-fuel condition were carried out...
The reversible reaction of CaO with CO2 can be used for post- and pre-combustion capture of CO2; however, the reactivity of CaO particles is found to reduce upon repeated use. Hydration has been shown to be an effective method of increasing the reactivity of (or reactivating) CaO to CO2 for CO2 capture. Here, a lab-scale fluidised bed reactor was used to investigate reactivation of sorbent using steam...
Two Greek limestones with different properties were tested to determine their CO 2 and SO 2 capture performance. The reversibility of the sorbents for CO 2 capture was investigated by performing looping cycles in atmospheric and pressurized thermogravimetric reactors, with synthetic gas mixtures containing different partial pressures of CO 2 and SO 2 to simulate...
Petroleum coke may be used as a fuel for entrained-flow slagging gasification. It may be blended with coal to provide a more attractive feedstock. The coal provides the benefits of enhancing reactivity and increasing the amount of slag coating the gasifier walls, while the petroleum coke increases the heating value of the fuel blend. The slagging behaviour of the petroleum coke or blend must be known...
Modified lime-based pellets have been developed as potential regenerable high-temperature CO 2 sorbents using calcium aluminate cement binders to enhance pellet strength. A mechanical pelletizer was used for granulation of the powdered materials, namely quick lime and hydrated lime, produced from Graymont limestone with the addition of spray water. The CO 2 carrying capacity of both...
The existing fluidized bed combustion literature on sulfation shows that above 30% conversion, direct sulfation via reaction with CaCO 3 is faster than indirect sulfation with CaO. However, while this is true for dry flue gases, it is not the case if steam (H 2 O (g) ) is present at realistic levels for coal combustion, and it has been confirmed by experiments employing thermogravimetric...
CaO-based pellets supported with aluminate cements show superior performance in carbonation/calcination cycles for high-temperature CO 2 capture. However, like other CaO-based sorbents, their CO 2 carrying activity is reduced after increasing numbers of cycles under high-temperature, high-CO 2 concentration conditions. In this work the feasibility of their reactivation by steam...
This study examines the loss of sorbent activity caused by sintering under realistic CO 2 capture cycle conditions. The samples tested here included two limestones: Havelock limestone from Canada (New Brunswick) and a Polish (Upper Silesia) limestone (Katowice). Samples were prepared both in a thermogravimetric analyzer (TGA) and a tube furnace (TF). Two calcination conditions were employed:...
Bed and fly ashes originating from industrial-scale fluidized bed combustors (FBCs) were steam hydrated to produce sorbents suitable for further in situ desulphurization. Samples of the hydrated ash were characterized by X-ray diffraction analysis, scanning electron microscopy and porosimetry. Bed ashes were hydrated in a pressure bomb for 30 and 60min at 200°C and 250°C. Fly ash was hydrated in an...
Results are presented on steam hydration of spent residues obtained from a 75kW th dual fluidized bed combustion (FBC) pilot plant unit operating in a CO 2 looping cycle mode. The samples were collected from the unit under various conditions, which included electrical heating of the reactor, as well as firing with coal, and biomass under oxy-fuel combustion conditions. In addition,...
Sulphation and carbonation have been performed on hydrated spent residues from a 75kW th dual fluidized bed combustion (FBC) pilot plant operating as a CO 2 looping cycle unit. The sulphation and carbonation tests were done in an atmospheric pressure thermogravimetric analyzer (TGA), with the sulphation performed using synthetic flue gas (0.45% SO 2 , 3% O 2 , 15% CO...
This work explores the reaction mechanisms for the sonochemical-enhanced carbonation of fluidized bed combustion (FBC) ash. Ashes from Nova Scotia Power’s 165MWe circulating fluidized bed combustor (CFBC) as well as synthetic ash prepared directly from limestone have been used. Acetone tests were carried out using pure acetone as well as acetone/water mixtures (4:1 ratio). Tests with acetone demonstrated...
The steam hydration reactivation characteristics of three limestone samples after multiple CO 2 looping cycles are presented here. The CO 2 cycles were performed in a tube furnace (TF) and the resulting samples were hydrated by steam in a pressure reactor (PR). The reactivation was performed with spent samples after carbonation and calcination stages. The reactivation tests were done...
This series of papers describes the development of technology to convert Hg(0) to Hg(II) in coal-derived flue gas based on the well-known Fenton reactions so that a Hg control strategy can be implemented in a wet scrubber. This effort consists of both bench-scale and pilot-scale work. This first paper reports on the bench-scale tests. The bench-scale results showed that Hg(0) oxidation can be achieved...
This second paper in a series describes results of pilot-scale testing for mercury (Hg) removal from coal combustion flue gas using a scrubbing solution based on the Fenton reactions. The selected reagents contain hydrogen peroxide and iron salts. The mercury scrubbing was performed in a condensing heat exchanger (CHX) with flue gas generated by coal combustion in CANMET’s vertical combustor research...
Two Canadian limestones, Calpo and Luscar, were fully sulphated, and the residues were hydrated with liquid water and steam and then re-sulphated with synthetic flue gas in a thermogravimetric analyzer (TGA). Both sulphated limestones were previously classified as showing uniform sulphation patterns, and it was expected that they would not demonstrate significant reactivation by hydration. However,...
Pilot plant studies were conducted to assess the feasibility of remediation of coal tar-contaminated soil and oil-contaminated gravel by incineration in a fluidized bed combustor and the same equipment converted to a calciner, with environmentally acceptable performance. Besides adequate decontamination and emission control, effort was devoted to treat the special feedstocks with difficult handling...
Ignition tests were conducted with delayed and fluid petroleum cokes, a high volatile bituminous coal and their blends in bench- and pilot-scale fluidized bed combustors. In the bench-scale FBC tests, a visual inspection ignition criterion was developed based on the ‘CO–CO 2 ’ profiles obtained as a function of time and bed temperature. In the pilot-scale unit, the rapid increase in SO ...
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