EQUIPMENT - 4-INCH-DIAMETER FLUID BED
Hazen's four-inch diameter fluidized bed furnace is used to generate bench-scale process development information while providing test samples representative of continuous-feed processing operations. Various four-inch fluid-bed shells, which are five feet in height, are available in different grades of stainless steel alloys to allow for operating as desired with oxidizing or reducing gas compositions at temperatures up to 1,200°C (2,200°F).
The four-inch fluid bed is externally heated throughout its length by silicon carbide electrical resistance heaters. Controllers are used to maintain the required operating temperatures in the furnace. Primary fluidization gases enter the unit through a windbox and perforated distribution plate at the bottom of the fluid bed. The composition of the fluidizing gas can be oxidizing, inert, or mixed as desired, and the fluidization gas can be preheated to 800°C (1,475°F) in an external heater when required.
The system consists of the four-inch fluidized-bed furnace, an external cyclone and baghouse for disengaging dusts from the process gas stream, and a wet scrubbing circuit for final cleaning of gases before they are exhausted to the atmosphere. An afterburner can be installed for high-temperature oxidation of the process gases, if required. The external baghouse can be equipped with sintered metal filters to allow for retaining five-micron particles at operating temperatures up to 650°C (1,200°F.)
A typical bed weight for this equipment uses about five pounds as a fluidizing medium. Solid feed materials are introduced to the system through the top of the unit and are transported to the bed by a portion of the fluidizing gas. Typical feed rates range from 1 to 12 pounds per hour. Bed-overflow, cyclone, and baghouse products are collected in their respective canisters.
The system is equipped with online instrumentation to obtain operating data. Process temperatures, pressures, and gas compositions, including O2, CO2, CO, SO2, NOx, and total hydrocarbons (THC), are monitored and recorded continuously. A gas chromatograph and mass spectrometer are available for measuring other gaseous constituents, such as water, hydrogen, nitrogen, and methane. Differential pressure is measured between the bed and freeboard to monitor and control the fluidization characteristics of the bed medium. A data-acquisition system is used to monitor and record selected process data. Emission sampling for organic compounds, metals, and other inorganic species can be performed as required, using EPA-approved methods.