| 摘要 |
<p>METHOD AND APPARATUS TO IMPROVE CIRCULATION CONTROL IN FLUIDIZED SYSTEMS Methods of and apparatus for improving fluidization of a particulate material flowing through a fluid conductor is provided by controlling the rate of addition of fluid, such as aerating gas or steam at a plurality of spaced apart locations along the conduit. The composition and rate of flow of the fluidized particles, such as catalyst shale, coal, or tar sand, is controlled by positioning a source of penetrative radiation such as neutrons, gamma rays, or X-rays at any location along the conduit so that the radiation traverses the fluidized particulate material flowing therein. A radiation detector is positioned opposite the source so that radiation absorbed in the conduit by the fluidized mixture may be measured as an electrical quantity. This electrical quantity may represent the total numbers of gamma rays of a preselected energy interacting with a detector in a given time interval or the average number of all gamma rays generating electrical pulses by interaction with the radiation detector. In accordance with such measured electrical quantity, the rate of flow of fluid into the conduit is adjusted in an amount and to an extent necessary to maintain the measured electrical quantity within preselectable range of values representative of stable composition and desired flow rate of the particulate material. In an apparatus form, the method is applicable to a fluid catalytic cracking system to control continuously circulated catalyst in an aeration gas, such as steam. By proper control of steam at a plurality of positions along the conduits a homogeneous dispersion of gas bubbles and particulate material at a given mixture is obtained. This prevents slumping or bridging of particulate material in the conduit by inadequate gas flow, or over-aeration of the mixture or generation of bubbles which either decrease catalyst flow or result in unstable operation by forming expanding and collapsing gas bubbles, which may in turn set up mechanical vibrations in the conduit and interconnected vessels. The result is a substantial increase in system processing capacity at reduced costs in steam and plant maintenance.</p> |
