Allis-chalmers Corporation

Wisconsin Electric Power Company

Svedala Industries, Inc.

Glenn A Heian

Robert F Kohl

Timothy M Nechvatal

A method for producing a lightweight aggregate by treating flyash and sewage sludge. The flyash and sewage sludge are mixed together and agglomerated into pellets. The pelletized agglomerate is fed into a rotary kiln in a direction that is co-current with the flow of fuel and air through the kiln. The rotary kiln includes at least one port air zone near the infeed end of the rotary kiln to introduce port air beneath the bed of pelletized agglomerate feed stock flowing through the rotary kiln. The introduction of port air beneath the material bed causes the volatized combustible matter to burn in the bed of material, which oxidizes the outer shell of the pelletized agglomerate. As the pelletized agglomerate continues to travel through the rotary kiln, bloating occurs within the interior of the material and results in the formation of the lightweight aggregate material.

Rotary kiln for forming lightweight aggregate from flyash and sewage sludge

A method is shown for producing a lightweight aggregate by treating flyash and sewage sludge. The flyash and sewage sludge are mixed together and then agglomerated into pellets, with or without the use of a binder. The pellets may be coated and then are dried. The dried pellets are introduced into a rotary kiln in a direction that is co-current with the flow of fuel and air through the kiln. The pellets in the kiln will be indurated and will experience complete calcination as well as varying degrees of pyrolizing and sintering. The product of the kiln is a nodular material having a low density but with a hard and porous structure. The product of the kiln is feed to a cooler. The flyash sewage sludge mixture has a significant fuel value that is usable in the kiln. Furthermore, the fuel value available in the kiln off-gases may be used for drying the materials.

Lightweight aggregate from flyash and sewage sludge

A method is shown for producing a lightweight aggregate by treating flyash and sewage sludge. The flyash and sewage sludge are mixed together and then agglomerated into pellets, with or without the use of a binder. The pellets may be coated and then are dried. The dried pellets are introduced into a rotary kiln in a direction that is co-current with the flow of fuel and air through the kiln. The pellets in the kiln witll be indurated and will experience complete calcination as well as varying degrees of pyrolizing and sintering. The product of the kiln is a nodular material having a low density but with a hard and porous structure. The product of the kiln is feed to a cooler. The flyash sewage sludge mixture has a significant fuel value that is usable in the kiln. Furthermore, the fuel value available in the kiln off-gases may be used for drying the materials.

Emission gas to be scrubbed of sulfur dioxide or the like has turbulent flow through a mixing vessel. At a mixing zone in the vessel, comminuted lime is fed into the gas and carried out of the vessel with the gas to a cyclone separator. A substantial portion of the dust from the cyclone is recycled back to the mixing zone of the mixing vessel. The gas from the cyclone is passed through a quench zone and excess dust from the cyclone is introduced into the gas stream for additional sulfur-dioxide removal, and quenching of the gas and dust from the cyclone is accomplished in a quenching zone prior to the gas being utilized in the system. Off-gas from the preheat zone which contains unburned combustibles is burned in a booster heater with the heat being utilized as process heat. Excess preheat off-gas not required for preheat process is delivered to a second combustion furnace for burning the combustibles therein and the heat utilized for drying. From the quench zone the gas passes to two dust separators with the cleansed gas being utilized in up-draft and down-draft drying zones. The dust from the two separators and from the grate is passed to a final dust separator where dust is removed from the gas. Make-up lime is fed to the mixing zone from a suspension calcining furnace, reaching the mixing zone while still heated.

Apparatus for handling and utilizing system gas in a pyro-processing

In a mixing zone of a mixing vessel, comminuted lime is fed into emission gas and carried out of the vessel with the gas to a cyclone separator. Gas from a cyclone is passed through a quench zone and excess dust from the cyclone is introduced into the gas stream for additional sulfur-dioxide removal. Off-gas from the preheat zone which contains unburned combustibles is burned in a booster heater with the heat being utilized as process heat. Excess preheat off-gas not required for preheat process is delivered to a second combustion furnace and the heat utilized for drying. From the quench zone the gas passes to two dust separators with the cleansed gas being utilized in up-draft and down-draft drying zones. Make-up lime is fed to the mixing zone from a suspension calcining furnace, reaching the mixing zone while still heated.

Process for handling and utilizing system gas in a pyro-processing system

Preheat gas is recycled to a booster heater that communicates with the preheat chamber with excess gas being directed to a quench chamber. From the quench chamber gas passes to a dust separator with the cleansed gas being utilized in low- and high-temperature drying chambers. The system is modified so as to have a mixing vessel ahead of the quench chamber in which lime dust is introduced to scrub the gas passing through prior to the gas being quenched. The gas is cleansed and utilized in a drying chamber.

Method and apparatus for handling and utilizing system off-gas in a

Sulfur oxides have a strong affinity for free lime and readily form gypsum anhydrite. By utilizing 2200.degree. F or higher on-gas containing reduced quantities of sulfur to the preheat zone of a material treating apparatus, large quantities of sulfur can be removed from gases evolved in the rotary kiln. Utilizing lower sulfur content on-gas to preheat will substantially improve the ability of the system to lower both sulfur and alkali levels in the clinker. Substantially free lime in the form of fines is introduced into the kiln off-gas stream to form gypsum anhydrite which is removed and has the potential to be utilized as a by-product. Essentially all of the remaining gaseous sulfur that has not been absorbed by the lime bearing dust is absorbed by the free lime in the pellets in the preheat zone of a material treating apparatus.

System for handling high sulfur materials

A strategically located series of spaced apart classifiers set at varying depths within a pelletizer pan operated to classify the forming pellets and also impart controlled energy into the forming pellets producing pellets of improved quality. Controlled classifying of the forming pellets stabilizes pellet output. With a stabilized pellet output obtained the need for driving the pellet pan with a variable speed device can be eliminated since pan rotation can be maintained at a constant speed.

Pan agglomeration with mechanical pellet classification

Sulfur oxides have a strong affinity for free lime and readily form gypsum anhydrite. By utilizing 2200.degree. F. or higher on-gas containing reduced quantities of sulfur to the preheat zone of a material treating apparatus, large quantities of sulfur can be removed from gases evolved in the rotary kiln. Utilizing lower sulfur content on-gas to preheat will substantially improve the ability of the system to lower both sulfur and alkali levels in the clinker. Substantially free lime in the form of fines is introduced into the kiln off-gas stream to form gypsum anhydrite which is removed and has the potential to be utilized as a by-product. Essentially all of the remaining gaseous sulfur that has not been absorbed by the lime bearing dust is absorbed by the free lime in the pellets in the preheat zone of a material treating apparatus.

A means and method for processing cement raw material containing fuel of high volatile content in a reinforced grate preheater kiln system by collecting the unburned volatiles of the high volatile fuel from the pellet bed and utilizing the collected volatiles as a fuel source elsewhere in the system.

Means and method for processing cement raw materials containing fuel of

Grate burner fuel supplies additional heat to the grate preheater for accomplishing more calcining. A cooler recoup system directs cooler recoup air to the grate fuel burner as preheat combustion air for the fuel burner. The cooler recoup air is also directed to the grate preheat zone as preheated combustion air for fuel in the pellet bed. Cooler recoup air is also directed to the drying zone. The cooler recoup system is controlled so that excess cooler recoup air is bypassed to the waste gas system to dump excess air. Also, a cooler recoup fan speed or damper is regulated to control kiln firing hood pressure by varying the flow. In addition, there is provided the cooler recoup excess air bypass damper for controlling duct pressure to stabilize air flow in the system by varying the flow to the waste gas system. The disclosed apparatus operated according to the method herein disclosed provides improved fuel economy, more effective control and reduction in waste gas, thus reducing heat consumption to provide improved fuel economy with better control of the preheating and drying operation.

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Franklin, WI, United States of America

Glenn A Heian