What is RCBC System
RCBC Global Inc. and its partners have developed a proprietary rotary cascading fuel bed reactor ideally designed for maximum thermal extraction or nearly 100% thermal conversion to heat energy. The mechanical unit is known as the Rotary Cascading Bed Combustor (RCBC). We have tested over 30 single-stream and mixed waste fuel types with optimal results. Variations in the process configurations all share the same fundamental principals, although details can adapt based on project objectives.
The RCBC utilizes a combination of proven concepts. Similar style rotary units have been in use for decades, particularly in the phosphate, fertilizer, cement and industrial drying sectors. 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 for optimal drying, air mixture and hot char. This is considerably faster than the conventional slow rotation kilns to which it bears an exterior 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 hot 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 Solids can be readily recycled or transferred from one compartment to another and gases can be introduced or withdrawn as desired.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. Moisture content and fuel variability can be PLC control adjusted on the fly for consistent production results.
Another key feature is the automatic injection of various sorbents with the fuels for ideal mixing conditions to lower unwanted gaseous formation, thus reducing the gas cleanup load for external scrubbing equipment. This results in an environmentally acceptable, economically attractive installation that outperforms EPA and NSPS standards.