TOTAL SALES FOR THE MONTH – $851,417.00

Established OEM gave blanket order for (9) nine CF Pleatjets that the customer trailer mounts for bridge blasting ventilation.

Danny Pepponi – Harding Ind. Sales (Chi) – Regional Manager – Wendy Nora

Repeat customer who manufactures resin coated sand purchased a STJ-1315-10, No. 3 Venturi scrubber and XP-8 Loading Spout for plant expansion.

Tom Harkness – Whitlock Ind. Equip. (Car) – Regional Manager – Bill Kurz

Expansion of existing facility for the recovery of glycol from recycled PET bottles.  System includes (5) five Impinjet scrubbers and (2) STj dust collectors.

design-information.ppt

VENTURI SCRUBBERS

 The venturi scrubber is specifically designed to collect particulate below 3 micron . Again, using inertial impaction as the primary mechanism, the venturi relies on accelerating the gas stream to very high velocities to produce sufficient kinetic energy values for sub-micron particles to be collected efficiently. The throat velocity for a 30″ pressure drop venturi is approximately 200 miles per hour, more than 4 times the whole velocity for an impingement plate. Since the mass of the particles is smaller the velocity must be higher.  To collect more of the fine particles, it is necessary to increase the speed (velocity) of the particles by increasing the speed of the air carrying the particles, as is done in the throat of a Sly VENTURI scrubber.  Higher velocity results in making the light particles “heavier” so that some of them travel in straight lines into the droplets instead of being carried around the droplet by the natural air stream.  This higher efficiency requires higher pressure drops.  For example:             VELOCITY                                  EFFICIENCY                        PRESSURE DROP            FEET/SECOND                      1 MICRON PARTICLES                     ” W.C.                         57                                            80%                                           1.5                       200                                           93%                                          12                       350                                           99%                                          30 Wet scrubbers rely on two mechanisms to accomplish the task of removing particulate matter from the air. These mechanisms are inertial impaction (the primary mechanism) followed by interception. Inertial impaction takes place when an air borne particle is unable to avoid colliding with an object in its flow path. This occurs due to the inertia of the particle and in relative terms its high kinetic energy. Kinetic energy is equal to one halftimes the mass times the velocity squared. Thus, in a gas stream containing a variety of particles of different sizes the larger particles with their higher mass have a higher kinetic energy and are more prone to be collected through inertial impaction.  Interception takes place when an air borne particle, following the air stream path around an obstruction, comes close enough to touch the obstruction and is then collected. This occurs when there is a high population of obstructions (water droplets) present and of similar size or smaller than the particles to be collected. Unlike inertial impaction, particle mass or velocity has little effect on interception.  A third mechanism, brownian diffusion, also has a minor effect. Very small particles, typically smaller than 0.3 microns exhibit essentially random motion, and do not necessarily follow stream lines. The collection of particles in brownian movement is random and will generally occur at very low velocities. As such, this mechanism does not affect the performance of wet scrubbers.  The Sly Venturi uses a “wet” approach design, which means the gas enters the scrubber in such a way that the first contact with water is on the converging walls of the scrubber. The water is distributed across the width of the converging walls using a pair of drilled pipe headers. The normal irrigation rate for venturi scrubbers is 8 gpm per 1000 CFM.  As the gas and liquid converge on the throat of the venturi ,both are accelerated. The water film is sheared by the acceleration of the gas into many fine droplets. The turbulent flow condition that exists in the venturi throat provides thorough mixing of the gas and liquid and producing large numbers of impaction targets for the particles.  The acceleration of the gas stream through the venturi throat also accelerates particulate matter, increasing the particle’s kinetic energy (expressed as 1/2 mass x velocity.  The presence of water in the venturi throat provides an abundance of targets for impaction.  Since kinetic energy is also dependent on mass it is easy to see why impaction type scrubbers have characteristic performance curves showing high efficiencies for larger particles.  Since mass is proportional to the cube of the diameter, a 1 micron size particle has 1/1000^th  the mass of a 10 micron size particle and 1/1000^th the kinetic energy when both are traveling at the same velocity. As with the Impinjet, the Venturi scrubber is sized and selected based on the outlet or saturated  gas flow volume.  The calculation is the same and requires the same input data.  The maximum flow conditions listed for the different sizes of venturi scrubbers is based primarily on the recommended shell velocities required in the cyclonic entrainment separator, not the venturi.  Sufficient velocity is required to establish a cyclonic flow pattern for the gas stream.  If the velocity through the separator is too high the collected droplets can easily be reentrained in the air stream. The specific pressure drop through the venturi throat is a function of the efficiency requirement and the particle size distribution. The same process used for determining the number of impingement stages in an Impinjet is used to calculate the pressure drop required of a venturi scrubber. In addition, we also calculate the apparent throat velocity to insure the scrubber selected will be operating within mid range of the adjustment of the throat damper.  As stated previously, the nominal irrigation rate for a venturi is 8 gpm per 1000 CFM. This can be increased for extreme particle loading conditions. Here too, the water can be recirculated from an external reservoir. The solids loading in the water should be similar to that recommended for the Impinjet not more than 10%. A continuous blowdown is always suggested to maintain a constant solids loading.  Since the processes that typically produce sub-micron particles are high temperature processes (500°F and higher), a pre-quench is recommended. The pre-quench is used to achieve saturation of the gas prior to entering the venturi throat. Adiabatic saturation of a high temperature gas stream usually results in significant changes in volume. If these changes were to occur in the throat the performance of the scrubber could be seriously compromised. In addition, the act of evaporation tends to repel particulate. This repulsion phenomenon is best dealt with prior to the throat.  Pre-quenches may be nothing more than a section of ductwork with two or three spray pipes installed to distribute water across the entire gas cross section. For very high temperature service, in excess of 1000^o F , the pre-quench is coupled with a water seal weir to provide for thermal expansion and contraction of the various system components. Normally the irrigation rate for a quench is determination to be 1.5 to 2 times the calculated evaporative loss. This provides more than sufficient water present to perform the desired function. And, using coarse spray distribution insures that for the most part none of the droplets will be completely evaporated. Complete evaporation of water droplets can leave behind a sub micron aerosol of the solids dissolved in the water, such as, calcium and magnesium salts typically present in hard water.