The Problem

Control & Metering, Inc. of Illinois, a manufacturer of LIW systems, asked us to design a surge bin to reliably handle pulverized lignite and coal. The end user, Satna Cement Company in India, required that the surge bin have a capacity of 60 metric tons and a maximum diameter of 5m. System requirements made it necessary for the LIW feed hoppers to be filled with 88 cubic feet of material in 10 seconds. This corresponds to an instantaneous discharge rate from the surge bin of approximately 600 tph at a bulk density of 38 pcf.

Jenike & Johanson's Solution

The first step in designing this surge bin was to determine the flow characteristics of the pulverized lignite and coal by testing in our laboratory. By simulating the worst case conditions of moisture and temperature in our laboratory tests, we could provide a design that would reliably handle the materials under those conditions.

We calculated limiting flow rates for various outlet dimensions based on the powders' compressibility and permeability (i.e., how readily air passes through the voids). Our computer analysis indicated that both powders would aerate readily and deaerate rapidly.

Based on the test results and computer analysis, we designed the surge bin that provided mass flow and the required capacity. We recommended that several air pads be positioned on the lower hopper walls to aerate only the material near the outlet.

The Result

The system was installed and has worked as intended for years. Another important aspect of the design was to ensure that the heel of material in the LIW hopper did not become fluidized and causefloodingduring rapid refill. To prevent this, we designed a deflector plate to be placed inside the hopper.

[ Complete Article ]

Email This Article