Control Your Product Quality by Controlling Your Product's Conveying Velocity

Size: px

Start display at page:

Download "Control Your Product Quality by Controlling Your Product's Conveying Velocity"

Aileen Spencer
6 years ago
Views:

Bulletin No. 201-201 PH: 717-546-3165 FAX: 717-546-1888 e-mail: mktinfo@younginds.

1 Bulletin No PH: FAX: Multi-Phase Dense Phase Pneumatic tic Conveyor ors Control Your Product Quality by Controlling Your Product's Conveying Velocity The Young Industries, Inc. Multi-Phase dense phase pneumatic systems are designed to convey material in either the low velocity dense phase conveying regime or in the true dense phase conveying regime. In the low velocity dense phase regime, the material nearly fills the convey line, and is extruded through the convey 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. Material velocity can be set as low as 25 feet per minute or up to 1,000 feet per minute. 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 can be set from 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. 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. Transporter vessel for batch transferring of materials in true dense phase and low velocity conveying regimes 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.

2 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 over loading of the system filter. When a low velocity rotary valve type continuous dense phase system is used, the M/P Valve controls the air during the initial startup, during normal conveying and during system shut down 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 a stable extrusion of 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 uses side-entry Rotary Valve Type Continuous Dense Phase for transferring material in true dense phase and low velocity conveying regimes 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, the 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. Contact us for additional information on dense phase conveying or for testing of your material. 3

3 THE Bulletin Defining Pneumatic Conveying System Regimes INDUSTRIES, INC. Muncy, Pennsylvania PH: FAX: Defining Low Velocity, Dense Phase and Dilute Phase Pneumatic Conveying Systems Many people do not agree on the definition of the dense phase and dilute phase mode of pneumatic conveying. Some people define the conveying mode or regime based on the material to air ratio with dense phase having a mass loading of to 1. The current definition of whether a system is dense phase or dilute phase is based on whether the superficial air velocity in the system is above or below the saltation point of the material. Systems with velocities below the saltation point are designed and calculated as a dense phase system. To further complicate the definition of the various conveying modes, low velocity conveying systems are offered. A low velocity conveying system is a dense phase system with the superficial air velocity substantially below the saltation point. Figure No. 1 shows examples of four pneumatics-conveying regimes with an illustration of the flow of the air/solids mixture in a horizontal pipe. If you have any questions, please feel free to contact us at or by at mktinfo@younginds.com. Copyright The Young Industries, Inc A B C D Figure No. 1 Examples of four pneumatic conveying regimes A "TransVair" dilute phase conveying regime: velocity above the saltation velocity 3800 to 8000 ft./min velocity unsuitable for abrasive and fragile materials- for long distances up to 700 ft. B "Multi-Phase" true dense phase conveying regime: highest velocity below the saltation velocity 1400 to 4500 ft./min.velocity suitable for powder and narrow particle size distribution may not be optimum design for fragile or abrasive materials- for long and very long distances up to 8000 ft. C "Multi-Phase" low velocity discontinuous or plug flow dense phase conveying regime: Low material velocity 700 to 2300 ft./min velocity Material moves in dune-like fashion good for fragile or abrasive materials short or long distances up to 1200 ft. D "Multi-Phase" low velocity solid dense phase conveying regime: very low material velocity 200 to 1400 ft./min velocity - pipeline almost full of material excellent for fragile of abrasive materials for short distances up to 300 ft. BULLETIN

Bulletin No. 211-302 PH: 570-546-3165 FAX: 570-546-1888 e-mail: mktinfo@younginds.

8 Bulletin No PH: FAX: Multi- Phase Low Velocity Dense Phase Pneumatic Conveying Reduce product breakage by controlling your conveying air Hammering, slugging, surging and severe vibrating of the convey line piping are to 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. 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 a high speed, precision control valve. This valve, called a 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. High Pressure rotary valve with transport vessel and air control piping The rotary valve discharges the material into a transport vessel. The rate that the material is fed into the convey line is controlled by high and low level indicators located in the transport vessel. Low velocity dense phase pneumatic conveying systems have Four (4) stages that must be controlled

9 for stable conveying. These stages are (1) start up, (2) normal operation, (3) shut down, and (4) emergency shut down. The controls and instruments used in the Multi-Phase Low Velocity Continuous Dense Phase system make automatic adjustments as the system progresses through these stages. The system pressure, vessel high level and vessel low level control the amount of air used to convey the material. This eliminates pulsing, surges and line hammering. The material is conveyed at the lowest possible velocity based on the required thru-put capacity of the system, the inside diameter of the convey line and the handling characteristics of the material. The patented Multi-Phase Low Velocity system electrical controls automatically adjust the conveying air volume and air pressure to the ideal settings for the required conveying capacity. The panel actually teaches itself to find the proper setting for conveying. When the input rate to the system varies; because of a change in the feed conditions like reduced feed rate change in material bulk density or particle size; the electrical control automatically adjusts the air volume to match the new conditions. When material is conveyed to numerous use points, the controls can adjust air volume for the new routing. It sets the air volume to the minimum required for the new conditions. This ensures the product is conveyed at the minimum conveying velocity for the required capacity, distance and line size. You will like the Young Industries Multi-Phase Low Velocity Rotary Valve Type Continuous Dense Phase system because: 1. 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. 2. You will use less air to convey material You will not experience surging, hammering or vibration of your piping and building supports. 4. 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 a test, using your material, demonstrating this proven low velocity pneumatic conveying method. Please contact us, at , to establish a convenient testing date or if you desire any additional information.

Chapter 6 Pneumatic Transport and Standpipes

Chapter 6 Pneumatic Transport and Standpipes 6.1 Pneumatic Transport Use of a gas to transport a particulate solid through pipeline Powder Rotary valve Blower Three major variables for pneumatic conveying