What is RCBC System
RCBC Global Inc and RCBC Technologies Inc have developed a proprietary technology which is applicable to many situations where intimate contact between gases and solids is required. The mechanical unit incorporating this technology is known as the Rotary Cascading Bed Combustor (RCBC). We have designed RCBCs for use as incinerators, hot gas generators, oil shale retorts, and cascading bed boilers capable of cleanly utilizing high-sulfur coal. All these devices are based on the same fundamental principals, although details differ.
The RCBC utilizes a combination of proven concepts. Similar rotary units have been in use by industry for several decades, particularly in the phosphate and fertilizer industries. Large units such as rotary kilns, rotary dryers, and ball and rod mills have been utilized and developed to satisfactory levels of mechanical reliability through many years of operation.
The RCBC consists of a hollow cylinder, which may be single- or multi-compartmental, depending upon the application, rotating at 8 to 20 revolutions per minute. This is considerably faster than the conventional rotating kilns to which it bears a superficial resemblance. The latter generally operate at less than 1 revolution per minute.
The RCBC provides excellent contact between solids and gases by cascading the solids through gases and thereby effecting high rates of heat transfer. Solids can be readily recycled or transferred from one compartment to another and gases can be introduced or withdrawn as desired. This provides great flexibility and allows designs to be optimized for a particular processing operation.
Cascading solids through the surrounding media ensures complex mixing and intimate contact. This provides the mechanism to transfer heat between the substances. For example, desired solid/gas reactions, such as combustion and SO2 absorption, are enhanced by the cascading.
The drawings above show the cascading action of the particles when the unit is operated at various speeds. When the unit operates of speeds producing a centrifugal force of less than 0.05 G, no cascading occurs and particle contact is limited. Cascading increases with speed of rotation. Maximum cascading, producing greatest solid/gas contacting, occurs at approximately 0.5 G. When the centrifugal force approaches 1.0 G, cascading is suppressed as particles are forced against the walls of the cylinder.
The RCBC’s internal design is varied to provide a variety of features specific to each application. Material movement, retention, cascading, backflow, gas/solids contact, temperature control, compartments, reaction kinetics, and a variety of combustion conditions can be controlled to desired levels by varying the design features.
The RCBC technology can provide high thermal efficiency by recovering much of the heat generated within the system. In most cases, the hot products of combustion (both gas and solids) are used to preheat the feed gases and/or solids. Due to its high contact efficiency and ease of adjustment, the RCBC can be readily controlled. Combustion conditions such as temperature and flue gas composition can be closely controlled. Feed variations can readily be compensated for and turndown can be accomplished without loss of control.
When burning sulfur-containing feedstock such as high-sulfur coal, the addition of limestone to the combusting solid lowers the sulfur dioxide content of the exhaust gases, eliminating the necessity for external scrubbing equipment. A similar approach can be employed to neutralize acidic vapors or remove reactants from the flue gases. This results in an environmentally acceptable, economically attractive installation.
Two corporate entities have been charged with responsibility for the RCBC development program. The first, RCBC Technologies, is charged with engineering of the RCBC for each application. The second, RCBC Global Inc., is responsible for market development and sale of the RCBC.