Description
The Multi-Phase Dense Phase Pneumatic Conveyor is a low velocity, low turbulence dense phase conveying system, offering users several advantages such as decreased particle attrition, less abrasive wear on conveying equipment, and reduced energy consumption. Hammering, slugging, surging and severe vibrating of the convey line piping are often standard operating conditions for dense phase conveying systems. This “RUN WILD” state causes material breakage and generation of fines in your product. This “RUN WILD” condition is caused by not having control of the pneumatic conveying system air pressures and volumes.
Until now, it was not possible to control dense phase conveying of materials. With The Young Industries, Inc. patented Multi-Phase dense phase systems, control of dense phase conveying is a reality.
Multi-Phase Dense Phase Systems
- True Dense Phase Conveyors
- Low Velocity Dense Phase Conveyors
- Continuous Dense Phase Conveyors
Design
The Young Industries, Inc. Multi-Phase dense phase pneumatic systems are designed to convey material in either the true dense phase conveying regime or in the low-velocity dense phase conveying regime.
In the true dense phase conveying regime, the air velocity is set just below the material’s saltation velocity. Material is conveyed as a bed of product that runs along the bottom of the convey line. The true dense phase velocity range is between 1,400 to 4,500 feet per minute. The velocity selected is based on the physical characteristics of the material, capacity, conveying distances and line size.
In the low velocity dense phase regime, the material nearly fills the convey line and is extruded through the conveying pipe. In longer distance systems, the material in the convey line forms dunes as it moves down the line. These systems have very low average conveying velocities. Yo can set the material velocity as low as 25 feet per minute or up to 1,000 feet per minute.
Control
The great versatility of a Multi-Phase Conveyor results from its multiple control feature. Conveying density of the material is adjustable by controlling the air volume at any of four points – the convey line, transport vessel, location of flow control nozzle, and size of flow control nozzle. The amount of air flow to the convey line, as well as the transport vessel is controlled independently while the material flow control nozzle-with infinite adjustability-controls material flow into the convey line. This combination of control versatility allows the product to be conveyed at maximum density, low turbulence, low velocity and minimum energy consumption.
The Young Industries M/P valve meters the air at a constant volume irrespective of the system operating pressure.
The most valuable feature of Multi-Phase Dense Phase systems is the M/P Valve. The M/P Valve controls the volume of air in the system. This valve meters the air at a constant volume irrespective of the system operating pressure. The valve is adjustable. It is manually adjusted when used on batch transporter systems and automatically when used on rotary valve type continuous dense phase systems.
When customers need a batch operation using a transport vessel, the M/P valve is set to meter the minimum requirement of air to meet the transfer rate. The valve also controls shutdown and purge air volumes, thus eliminating uncontrolled air surges that cause line vibrations and overloading of the system filter.
Reducing Product Breakage
When a low velocity continuous dense phase system is used, the M/P Valve controls the air during the initial start-up, during normal conveying and during system shutdown modes of operation. This ensures slow, gentle conveying and eliminates uncontrolled material surging in the line. The minimum conveying velocity of the product is established based on the material handling characteristics and the conveying distances.
When conveying with the low-velocity rotary valve type continuous dense phase system, high and low level indicators control the M/P valve setting. The high-level switch increases the amount of conveying gas that is metered to the system. The low-level switch decreases the amount of conveying gas that is metered to the system. We have designed the controls to change the M/P air valve setting in restricted steps based on the level switch information. This ensures minimum gas usage and stable extrusion of the product in the convey line. The controls also manage the start-up gas volume and shutdown or purge gas volume setting of the valve. The material is always conveyed at the lowest possible velocity, at the required rate.
The low-velocity rotary valve type continuous dense phase systems use Model DP rotary valves to meter the product into the pressure vessel. Because the material enters the rotary valve rotor from the side, jamming and clipping of the pellets is eliminated. Besides controlling to the M/P valve setting, a high-level indicator prevents material from over filling the vessel and causing material clipping at the bottom of the rotary valve. The low-level indicator makes certain that a solid plug of material is extruded into the convey line. Material is conveyed at the minimum possible velocity.
The control of the continuous transfer of materials using the patented Multi-Phase Low Velocity Rotary Valve type continuous dense phase system is accomplished in several ways. First, the conveying air is metered into the system by high speed, precision control valve. This valve, called an M/P valve, is opened and closed in small increments by a precision stepper motor making it possible for finite control of the air volume. Second, the material is metered into a pressure vessel by a High Pressure/Low leakage rotary valve. This rotary valve sets the thru-put capacity of the system. The unique design of the High Pressure valve ensures that the product is not damaged as it is metered into the vessel and air leakage thru the valve is kept to a minimum.
Why You'll Like the Young Industries Multi-Phase Dense Phase Systems
- You will not break up your product when it is conveyed in this system. You will not get fines, angel hair or change in your material’s particle size in conveying the material to the farthest destination point. You will be conveying the material at the lowest possible velocity.
- You will use less air to convey material.
- You will not experience surging, hammering or vibration of your piping and building supports.
- You can install the system and not worry about set up or operation of the controls. The system will automatically control the start-up and conveying of your product under the various process conditions.
Your next step is to witness the test, using your material, demonstrating this proven low-velocity pneumatic conveying method.