Inlet duct

Fig. 11. Two-truck tray dryer. A, air inlet duct B, air-exhaust duct with damper C, axial flow fan D, fan motor, 2—15 kW E, air heaters F, air-distribution plenum G, distribution slots and H, wheeled tmcks and trays. The arrows iadicate air and vapor flow pattern.

FIG. 12-48 Doiible-tnick dryer. (A) Air-inlet duct. (B) Air-exhaiist duct with damper. (C) Adjnstahle-pitch fan 1 to 15 hp. (D) Fan motor. (E) Fin heaters. (F) Plenum chamber. (G) Adjustable air-blast nozzles. (H) Trucks and trays. (J) Turning vanes. 

The collection efficiency of cyclones varies as a function of particle size and cyclone design. Cyclone efficiency generally increases with (1) particle size and/or density, (2) inlet duct velocity, (3) cyclone body length, (4) number of gas revolutions in the cyclone, (5) ratio of cyclone body diameter to gas exit diameter, (6) dust loading, and (7) smoothness of the cyclone inner wall. Cyclone efficiency will decrease with increases in (1) gas viscosity, (2) body diameter, (3) gas exit diameter, (4) gas inlet duct area, and (5) gas density. A common factor contributing to decreased control efficiencies in cyclones is leakage of air into the dust outlet (EPA, 1998). 

Inlet bells or boxes Aerodynamically shaped inlet ducts for a fan. 

Wind stop A flat plate or a cone fitted over an outlet or inlet duct in order to reduce the possibility of flow reversal due to wind pressure. 

Cyclone inlet V elocity head, in. water Height of a segment of a circle, ft Height of rectangular cyclone inlet duct, ft Height of dispersion band, ft Width of interface, ft... 

V = Settling velocity for hindered uniform spherical particle, ft/s or m/s Wi= Width of rectangular cone inlet duct, ft Z], = Heavy phase outlet dimensions of decanter measured from horizontal bottom, shotvn on Figure 4-12... 

An open pipe-ventilated machine is an open machine except that openings for the admission of the ventilating air are so arranged that inlet ducts or pipes can be connected to them. Open pipe-ventilated machines shall be self-ventilated (air circulated by means integral with the machine (ICll) or forced-ventilated (air circulated by means external to and not a part of the machine) (IC17). Enclosures shall be as defined in 1.25.1a to 1.25.5a, inclusive. 

Penetration of the gas outlet tube into each cyclone should be at least 80% of the cyclone inlet duct height. 

Consider a volume of gas flowing into the compressor. Compression work W, is required to force the gas into the system. The constant force exerted on the gas is P At, where A is the cross-sectional area of the inlet duct. The distance through which the gas is forced as it enters the system is - V / A. The negative value of - V /A results from the force acting from the surroundings on the system. Thus ... 

In the spiral or tangential cyclone inlet duct, the particles are accelerated to a velocity which is related to the inlet gas velocity Ue. Neglecting as a first approximation the slip between solids and gas, the kinetic energy of the solids which is transported per unit time into the cyclone is approximately given by... 

The traditional (Rosin, et al., 1932) mechanistic approach equates the time necessary for a particle to settle at a Stokes law velocity across the width of a cyclone s inlet duct, to the available residence time of the carrier gas stream in its number of spiral traverses within the barrel. With reference to Fig. 1, this permits solving for the smallest particle size able to cross the entire width and reach the wall in the available time. 

On the inherent assumptions that (a) all entering particles are uniformly dispersed over the area of the inlet duct, (b) the barrel is a perfect cylinder with a straight inlet duct entering tangentially, (c) the trajectory of die incoming particles will not result in any impingement on the gas outlet duct, (d) that the velocity of the downwardly spiraling gas... 

The equipment operates by negative pressure differential generated by a turbine. Air is drawn in the inlet duct, throttled at the inlet flap, cleaned at the inlet filter, heated at the steam heated coils, and then used to fluidize the material resting on the screen in the bottom of the product bowl. The air is then cleaned at the outlet filter, throttled at the outlet flap, and accelerated through the turbine to the atmosphere. 

On October 30, 1998, a flammable gas release led to gas migration to a non-electrically classified Electrical and Instrumentation (E l) Room. The flammable gas was ingested into the exterior heating and ventilation inlet duct. When the 480 volt primary power switch, within the E l room was remotely shut off, an explosion resulted. The E l module explosion led to a subsequent fire in adjacent production buildings. There were no injuries to personnel. The root cause of the incident was determined to be the failure of management systems... 

Dpmin = critical particle diameter p = gas viscosity B, = inlet duct width... 

Decreasing inlet duct width (BJ and increasing aspect ratio (inlet height/ width). 

Sampling. Four aerosol samples were collected isokinetically on July 26, 1979, at ports on the inlet duct of the ESP at Plant A two were taken with 62-mm fluoropore filters and two were taken with the University of Washington MKV Cascade impactor (1 ). At plant D, samples were collected over a 6-day period at ports both in the outlet duct of the ESP (i.e., upstream of the FGD system) and at the 91-m level of the stack. Eleven fluoropore filter, 1 MKV, and 4 MKIII impactor samples at each location, giving a total of 22 filter, and 8 MKIII samples. A single MKV sample was also collected in-stack at reduced pressure at plant D during the 6-day period. Polycarbonate material coated with apiezon L vacuum grease and 62 or 47-mm-diam, l-pm pore Fluoropore filters were used as back-up filters in the MKV impactor. 

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