Inlet vane

Fig. 7. Control of fan performance with inlet vane control. SoHd lines marked A and N show normal performance without vanes (vanes wide open). As vanes are progressively closed, static and power curves are modified as indicated by dashed lines. Intersection ( - ) of the system resistance curve with these reduced pressure curves at points B, C, D, and E shows how imparting more spin to the inlet air reduces flow. Projecting points A to E vertically downward to the corresponding power curve locates fan power points A through E7 Power savings achieved over throttling control can be estimated by projecting points B through E vertically downward to the A power curve and comparing the value with that from the proper reduced power curve. To...

If the turbine is not out of alignment, or the shaft bowed as determined by the vertical and horizontal clearance checks or the appearance of the bearing surfaces, it is not recommended that the rotor be removed. Some turbine designs, however, may require removal of the rotor to facilitate the removal of some bottom sections of the diaphragms or inlet vanes. If the rotor is... 

When high-efficiency (which requires small cyclone diameter) and large throughput are both desired, a number of cyclones can be operated in parallel. In a multiple tube cyclone, the housing contains a large number of tubes that have a common gas inlet and outlet in the chamber. The gas enters the tubes through axial inlet vanes which impart a circular motion (AWMA, 1992). 

Vane control Fan inlet vanes alter fan perform.ance by controlling the swirl. 

Inlet vane dampers Dampers inserted in the airstrearn at the inlet of a fan. 

Inlet vanes Specially-designed adjustable vanes inserted in the airstrearn entering a fan inlet to control fan performance by producing a swirl of the gas in the direction of the rotation of the impeller. 

If inlet vane is formed with inlet connection ... 

Figure 12-44B. Single-stage centrifugal compressor with variable inlet vanes, diaphragm, and diffuser vanes illustrated. (Used by permission Worthington Power and Fluids, V. 8., No. 2, Winter, 1965. Dresser-Rand Company. All rights reserved.)...

Stationary or moveable inlet vanes, if used, attach to the inlet beU. These are also dieformed for uniformity and are welded in place for the stationary type and attached to a spider that is attached to the beU for the movable type. Figures 12-127A-B. The discharge damper. Figure 12-127C, is used for system volume and pressure control and is discussed later in regard to comparative performance with inlet vanes. 

Figure 12-120D. Fan assembly with double-width wheel, inlet vane dampers, and belt drive with guard. (Used by permission Bui. 141, 1995. The New York Blower Co. For more information, contact the company at www.nyb.com.)...

Figure 12-127A. Stationary inlet vanes. (Used by permission The Howden Fan Co.)...

Figure 12-134. Typical variable inlet vane performance curves. (Used by permission Elliott Company, Jeannette, PA.)...

Air handling unit fans should contain a provision for modulating airflow to compensate for increased static pressure losses as the loading of filters increases. This is usually accomplished through the use of inlet vanes other methods would be discharge dampers and variable speed drives. 

Air handling unit fans are able to modulate air flow by using inlet vanes, discharge dampers, or variable speed drives. 

Figure 7.23. Performances of fans with several kinds of controls (American Standard Co. Inc.), (a) A damper in the duct with constant-speed fan drive, (b) two-speed fan driver, (c) inlet vanes or inlet louvers with a constant-speed fan drive, (d) multiple-step variable-speed fan drive, and (e) hydraulic or electric coupling with constant-speed driver giving wide control over fan speed.

Plot the power-input curve AFED for inlet-vane control on the forced-draft fan or inlet-louvre control on induced-draft fans. The data for plotting this curve can be obtained from the fan manufacturer. 

CONTROL (SPEED SUCTION VALVE. INLET VANES) ... 

Steam turbines with compressors are used for providing process gas flow at a required pressure in high throughput processes. The process demand is determined by a pressure controller, which adjusts the setpoint on the turbine speed controller. In smaller processes, fixed speed compressors may be used by adjusting either an inlet or discharge valve to achieve pressure control. It is more energy efficient to adjust an inlet valve, or better yet to adjust inlet vanes which provide a pre-rotation to the gas. However, adjustment of speed is the most energy-efficient method control. 

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