摘要:
A method for treating cement kiln dust containing alkaline metal salts includes the steps of hydration (formation of calcium hydroxide), dehydration i.e. drying, fractionation by sieving and carbonation (reaction of the fractionated moistened cement kiln dust) with CO2 gas in a fluidized bed reactor.
摘要:
An installation comprising a combustion chamber having a device for introducing the mineral load and that is connected to a preheater, a combustion device to maintain the chamber at a temperature between 700° C. and 900° C., a treatment gas introducing device, the gas having a controlled carbon dioxide content in order to oppose the dissociation of the carbonate in the chamber and a device for removing the calcined mineral load guided into a cooler. The chamber also forms a fluidized bed. The treatment gas introducing device is supplied, at least partially, by a bypass duct, with some of the flue gases from the chamber coming from a device for discharging these gases into the atmosphere. This may be used in the production of a cement-type hydraulic binder.
摘要:
The invention relates to a method for heat treatment of fine calcium carbonate bearing material comprising preheating fine material containing a coarse and a fine fraction. The preheated material is delivered into a fluidized bed calcining means wherein the coarse fraction is calcined and the fine fraction is delivered by process air to an adjacent vertically arranged gas flash calciner furnace in which it is calcined.
摘要:
Method and apparatus for obtaining finely pulverized quicklime powder having high reactivity by calcining fine limestone powder, particularly, of particle sizes 1-100 micrometers. Coarse particles of inert substance, particularly, those having diameters of 100-1500 micrometers, are fluidized with high temperature gas to form a fluidized bed, and fine limestone powder is supplied into the fluidized bed. The fine limestone powder captured by the fluidized bed is calcined therein and the resulting quicklime powder is carried away by the stream of fluidizing gas and recovered with cyclone and bag filter. Coarse limestone may be used instead of or together with the coarse inert substance particles.
摘要:
Method and apparatus for treating small size particulate solids in a fluidized bed, and the calcining of particulate magnesium carbonate and magnesium hydroxide, or a mixture thereof in a fluidized bed, wherein the apparatus may include an upstanding tubular member of substantially greater length than width defining a bed area or reaction vessel and means for heating the bed by driving heat through the walls of the tubular member, and including means coacting with the incoming fluidizing gas to enhance even fluidization.
摘要:
IN AN ENDOTHERMIC PROCES, RAW SOLIDS ARE FIRST DRIED IN A SUSPENSION-TYPE HEAT-EXCHANGER SYSTEM BY HOT GAS COMING FROM A FLUIDIZED-BED FURNACE WITH MATERIAL RECYCLING AND THEN INTRODUCED INTO THE FLUIDIZED BED. HOT SOLIDS TAKEN FROM THE FLUIDIZED BED ARE USED IN HEAT
EXCHANGER TO PREHEAT FRESH AIR WHICH IS USED AS THE FLUIDIZING GAS FOR THE FLUIDIZED BED. ANOTHER PORTION OF AIR IS ALSO HEATED IN THE HEAT EXCHANGER AND INTRODUCED IN THE FLUIDIZED BED AS SECONDARY AIR.
摘要:
A method and system for the generation of a medium-Btu, clean and renewable fuel gas to replace fossil fuels in existing lime kilns with minimal retrofitting without significantly compromising the kiln capacity. A steam-blown dual fluidized bed gasifier produces renewable fuel gas from a carbonaceous feedstock such as woody biomass. A gas cleanup process purifies the raw fuel gas, resulting in a clean fuel gas for mitigation of lime contamination and environmental issues. The adiabatic flame temperature and flue gas volume/GJ for the combustion of the renewable fuel gas are similar to values for natural gas, making retrofitting of fossil fuel-fired lime kilns relatively straightforward.
摘要:
A method for treating cement kiln dust containing alkaline metal salts includes the steps of hydration (formation of calcium hydroxide), dehydration i.e. drying, fractionation by sieving and carbonation (reaction of the fractionated moistened cement kiln dust) with CO2 gas in a fluidized bed reactor.
摘要:
The invention features methods and systems for producing commercial quality carbon dioxide (CO2) of 90% to +99% purity using, wet, fine particle limestone produced in a manufacturing operation, for instance, a limestone quarry as a feedstock to a multi-stage limestone calcination process. This process may be fueled with negative cost waste water treatment plant (WWTP) sludge, biomass, coal, or other low cost solid fuels. High reactivity lime product required in the an adjacent paper mill's PCC manufacturing plant is also produced, and steam and heated boiler feed-water is generated and exported to the mill's steam distribution and generation system as well as hot process water for use in the mill's manufacturing operation. The system for calcining fine particle limestone produced in a quarry manufacturing operation and converting it to lime and CO2 comprises a calciner and a combustor linked by a moving media heat transfer (MMHT) system or apparatus. The MMHT system or apparatus thermally links separate fluid bed combustion (exothermic) and calcination (endothermic) stages with a solid particulate media. The fluid bed calcination stage is fluidized with steam. The system further comprises a dryer/pre-heater that utilizes exhausted heat from the calcination stage.
摘要:
This is a process and a device making use of a process for forming calcium oxide from pulverulent calcium carbonate, according to which an initial bath of pulverulent calcium oxide is produced in a reactor (1, 31) in the form of a fluidized bed which is heated electrically to a temperature higher than of the order of 900.degree. C., and the said pulverulent calcium carbonate is then introduced continuously into the bath while the temperature of the bath is always kept higher than of the order of 860.degree. C. by electrical heating, to dissociate the said calcium carbonate into calcium oxide and carbon dioxide.