DRAFT FAN WITH DRAFT CONTROL FOR OWB DRIVER
VSDs and VFDs match driver speed to load demands and thus improve operating efficiency dramatically.īecause many centrifugal machines operate at a reduced load for an extended period of time, significant energy savings can be realized by reducing their operating speeds.
Fortunately, there is a more efficient option: variable speed/frequency drives (VSDs/VFDs). To offset this, anti-spin baffles are placed in the inlet box.Īll restricting type flow control devices waste energy to varying degrees. Inlet box dampers may be subject to stall conditions at maximum turndown. To offset this, dorsal fins are added to the vortex dampers to break up the pre-spin effect, reducing the efficiency factor of the pre-spin. However, on a lot of large industrial fans where there are large volumes and pressures, secondary vortex shedding may occur. The main reason for this is because a VIV damper is placed in the inlet cone closer to the eye of the wheel, whereas an MLPB damper is further away.īy placing a damper in the eye, greater pre-spin can be induced, thus allowing airflow to enter the eye of the wheel more efficiently.
Many consider VIVs worth all this extra hassle because they are generally understood to be more efficient than the MLPB dampers. This means that VIV components are exposed to the dirty gases, elevated operating temperatures, and high gas velocities, and that the inspection, maintenance and replacement of VIV components require the fan to be shut down, causing expensive downtime. Access to linkages and bearings is through the fan casing only. VIV dampers, on the other hand, are often placed inside the fan inlet cones. Inspection, maintenance, and replacement of these components can be performed while the fan is operating. Moreover, all of the bearings and linkage assemblies for the MLPB dampers are outside of the duct so they can be easily accessed for maintenance and replacement. The required torque for an MLPB damper is usually lower than a comparable VIV, which makes the actuator less expensive. Installation of an MLPB also costs less since some VIVs have to be placed around the shaft and lowered into place.
DRAFT FAN WITH DRAFT CONTROL FOR OWB FULL
Minimum resistance is experienced when the MLPB blades are positioned in the full open position.Ī MLPB damper is typically less expensive than a VIV counterpart for the same size fan.
They reduce net effective flow area in the cone with a defined profile that increases the gas flow velocity, resulting in additional resistance.īy contrast, MLPB dampers are located in the fan inlet box with only their blades coming in direct contact with the gas flow. VIVs – also known as vortex dampers – are typically located in the fan inlet cones. Inlet box multi-louver parallel blade (MLPB) damper controls Inlet damper controls can be categorized into two types: While common, these throttling devices can be inefficient and waste energy. This involves using damper controls for throttling or restricting flow at the fan inlet and outlet with inlet and outlet dampers. Inlet damper controls are used to adjust flow to meet fluctuating load demand. Here, we’ll compare several common flow control devices used in air handling solutions in order to better understand their effects on mechanical draft fan performance and efficiency. Flow control devices are crucial because they have a direct effect on power savings in terms of how effectively these devices can control flow and pressure through the fan. One factor that plays a role in the efficiency of mechanical draft fans is the type of flow control device used in the system. They are essential to moving large amounts of air and gases through a system duct and components, but they use a large amount of power and can result in serious inefficiencies if not properly designed and managed. Mechanical draft fans are integral parts of a plant’s operations. Comparing Different Flow Control Devices for Mechanical Draft Fans
0 kommentar(er)
