Buell International Fluid-Bed Cyclones

Buell Refinery Cyclones has engaged in the study of cyclone separating technology and the development of application markets since its founding in 1934. Its long history of application engineering practical experience includes numerous patents for cyclone separation technology. The cyclone products are used world wide in fluid catalytic cracking units for all processors. The refinery division produces third stage systems (TSS), recovery cyclones, 4th stage cyclone systems and critical orifice valves and cyclones for the petrochemical industry.

Fisher-Klosterman, Inc. (FKI) consists of a dynamic group of companies providing guarantees solutions for product recovery, air pollution control, dust collection and particle classification. With over a half century of experience and more than 15,000 installations worldwide, FKI is a leader in providing a complete line of custom engineered equipment for product recovery, dust collection and air pollution control for industrial process applications. The Buell APC, Buell Refinery Cyclones and Buell Classifier Divisions represent over 70 years of product excellence serving the air pollution control, product recovery and particle classification needs of the utility power, refinery and aggregate industries respectively. All products are known for their tate-of-the-art design, high standards of quality, long-term reliability and predictable, guaranteed process results.

In early 2007, Fisher-Klosterman, Buell’s parent company acquired a 40,000 square foot fabrication shop and office building in the Pudong New Area of Shanghai, PR China. The Fisher-Klosterman-Buell Shanghai Co., Ltd. Division is able to utilize extensive technology developed by USA-based Buell and Fisher-Klosterman for market development, distribution, production and service in the Pacific Rim and globally.

Buell Fluid-Bed Cyclones for FCC Units, Petrochemical Reactors and Fluid-Bed Boilers
Buell Cyclones are an excellent choice for all fluidized bed processes. Systems have operated continuously at temperatures above 1300 degrees F for more than three years without maintenance. This dependable performance is the result of good design and quality fabrication. Both the Buell patented inlet scroll and custom outlet design reduce erosion and increase efficiency of cyclones. In addition, abrasion resistant castable refractory linings allow Buell cyclones to withstand continuous flow of tons per minute of highly abrasive catalyst. If emissions from FCC regenerator cyclones exceed the limits of local Air Pollution Control regulations, Buell offers a third stage separator located external to the regenerator for additional gas cleaning. This arrangement also reduces the particulate loading such that the gases can be directed through a turbo-expander to generate considerable energy before being exhausted to the atmosphere.

Principles of Buell Cyclone Operation
Buell cyclones are designed to harness the natural flows that occur within a cyclone so that these flows enhance cyclone performance. Dust-laden gases enter at the inlet and are introduced to the cyclone proper through a gradual 180 degree volute turn. Gases making a turn in a rectangular elbow or the rectangular inlet scroll of a conventional cyclone develop currents that are perpendicular to the direction of the gas. These currents result from the fact that in different areas of the elbow, gases must travel different distances in order to complete the turn. Gases on the inside wall of the elbow have a considerably shorter distance to travel than gases on the outside wall of the elbow. Currents perpendicular to the gas flow are developed to balance the gas flows and the kinetic energy in the gas flow.

Uncontrolled Perpendicular Currents in Cyclones
When not controlled, the perpendicular currents retard the flow of particles to the cyclone wall and carry some of the finer particles up to the top of the cyclone. A ring of particles builds up around the top of the cyclone to a point where it can no longer be sustained by the gas flow. It then falls through the cyclone; some of the particles enter the ascending vortex flow and escape from the cyclone. This ring of particles can also cause erosion in this area of the cyclone, shortening cyclone life.

Elimination of Perpendicular Currents in an Elbow

Considerable research was conducted to fine a means of eliminating perpendicular currents in an elbow. If the elbow was designed such that the velocity of the gas in any area times the distance traveled equaled the product of velocity times distance in any other area, perpendicular currents were eliminated. The radius to any area in the elbow is directly proportional to the distance traveled in that area. The velocity in any area is directly proportional to the height of the elbow in that area. Therefore, an elbow designed so that the product remains constant for any radius “c” to a point in the elbow times the height of the elbow at that point “d” will not have perpendicular currents. In Figure 1, the product (a) (b) = (c) (d) = (c’) (d’).

Elimination of Perpendicular Currents in a Patented Cyclone Inlet Scroll

The principal design of an elbow without perpendicular currents has been applied to the Buell patented cyclone inlet scroll. In order to eliminate the need for two curved surfaces (top and bottom), on the inlet scroll, the correction has been made to the bottom shelf of the scroll. This application is shown in Figure 2. Laboratory and field tests on cyclones with this type of inlet have shown that greater efficiencies for the Buell design cyclones than cyclones similar to Buell but without the flat inlet scroll floors.

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