RayMas® Non-contact Solids Flow Meters
Non-contact Solids Flow Meter for Waste Solids
The feedstocks for gasifiers are diverse solid particulate materials with many properties from particulate size, composition, density and flow characteristics. The feedstock could be sticky such as due to moisture content therefore posing a problem for instrumentation such as meters for measuring mass flow rate. Some new metering technology has been emerging over the past several years to resolve the problems associated with measuring mass flow of solids (particulate mass flow) through process lines and ducts.
This new development in mass flow metering technology is known as the RayMas® meter, i.e., proprietary and patented non-contact solid flow metering technology. Simply stated, the RayMa® meter consists of the following components: a flow tube, a sensor, and controls/instrumentation. A picture of an early version of the meter with components is shown in Figure 4. of a 6”-diameter gravity flow type of meter. As shown, a fine mineral powder is being conveyed by a screw feeder into the top of the Raymas® meter and drops by gravity flow through the meter and discharging out the bottom of the meter into another screw feeder which then feeds the fine mineral powder into a furnace. The fine mineral powder has a particle size range from 0.5 to 1.5 micron.
Fig. 4. RayMas® Non-contact Solids Flow Meter, 6”-diameter, Gravity Flow Type, Metering Material - 0.5 to 1.5 micron Mineral Powder
Referring to the simplified representation of the RayMas® non-contact solids particulate flow meter, Figure 5., the sensor transmits a low energy microwave to the particulate matter passing through a flow tube. The intensity of the reflected Doppler-shifted energy is measured by the sensor converting it into a 4-20 mA signal. This signal is then converted by a unique algorithm in the controller/instrumentation to mass flow rate, such as pounds per hour of particulate material. RayMas measures the intensity of reflected Doppler-shifted energy, which is based upon velocity & flow quantity of material. Thus only moving material is measured and build-up has little influence upon the meter. In RayMas solids flow meter, a proprietary design is used coupled with a unique algorithm to provide a meter with mass flow rate and totalizer (quantity) measurement capabilities for each particular material to be metered. Gravity flow type and pneumatic flow type of meters are available but experience has shown that the gravity flow type to be the most easily adapted to applications.
Fig. 5. RayMas® Solids Flow Meter, Simplified Schematic Representation
A 6”-diameter and an 8”-diameter gravity flow meters are shown in Figure 6. The 8”-diameter meter is being used to meter a corn byproduct material at flow rates from 8,000 to 20,000 lbs/hr
Fig. 6. RayMas® Non-contact Solids Flow Meter, Gravity Flow Type; 6”-diameter metering Whole Corn; Similar 8”-diameter metering Ground Processed Corn
For another gravity flow application, a 20”-diameter meter has been installed for metering a wet corn fibrous material at rates between 15,000 to 40,000 lbs/hour. The 20”-inch diameter meter is shown in Figure 7.
Fig. 7. RayMas® Non-contact Solids Flow Meter, 20-inch Diameter, Gravity Flow Type; Product Material metered – Wet Corn Material
A 4”-diameter meter is shown in Figure 8. for a pneumatic conveying (PC) type of RayMas® Non-contact solids flow meter.
Fig. 8. RayMas® Non-contact Solids Flow Meter, Pneumatic Conveying (P.C.) Type
The RayMas® meter is new technology and of unique and proprietary design. Final accuracy of the RayMas® meter depends upon the material being measured and the particular installation. Gravity flow applications produce a more reliable mass flow reading compared to Pneumatic flow applications. As you likely know, a pneumatic flow application has more variables for a particular installation such as gas flow conditions and suspension of particulates in the conveying line.
The industrial market has many applications for segments such as: chemical, plastics, petroleum, utility (power plants), food, pharmaceutical, cement, mining, precision farming, and others for a gravity type mass meter or a pneumatic conveying type of mass flow meter applications. As the new Raymas® non-contact solids mass flow meter continues to improve from refinements and upgrades via technology, the market potential and need for such process innovation in metering instrumentation will continue to be of much interest.
In the research and development (R&D) of the RayMas® non-contact solids flow meter, many experimental runs were made comparing weigh scale readings with the particular RayMas® meter calibrated on a laboratory test stand. Some tests were conducted to develop the technology and other runs were made for calibration of a meter for a particular customer’s industrial application. The following cases were obtained experimentally and illustrate the future potential for the RayMas® non-contact solids flow meter. Typically, a particulate solids material was passed through the meter and recordings of the meter were compared with those from a weigh scale. The experimental apparatus used for some of the experimental tests and calibrations is shown in Figure 9. for use with a gravity flow type of meter.
Fig. 9. Calibration Equipment for a RayMas® Solids Flow Meter, Gravity Flow Type
A small portable RayMas® non-contact solids flow meter, gravity type, was designed, developed and tested on a test stand. Some high density polyethylene plastic beads were metered into the top of the 2-1/2” diameter vertical gravity flow meter and passed through the flow tube into a bin on a weigh scale. From the mass flow rate of beads and the corresponding microwave sensor output, a unique algorithm was computed for the high density polyethylene plastic beads and for that particular meter. The meter was calibrated for a mass rate range of 0 lbs/hr (no flow) to 1817 lbs/hr. The beads were 5/32”-diameter with a bulk density from 35.78 lbs/ft3 to 36.14 lbs/ft3. Results from this initial development work were successful as shown in Table 2.Table 2. Portable RayMas® Meter Gravity Flow Type, 2-1/2”, Calibration Runs
Meter: RayMas® Solids Flow Meter, 2-1/2” diameter, Gravity Flow Type, Aluminum Product Metered: High Density Polyethylene Plastic Beads, 5/32”-diameter, bulk density (loose) - 35.78 lb/ft3, bulk density (tamped) – 36.14 lb/ft3
|Run No.||RayMas® Meter Reading
|Weigh Scale Reading
Average absolute weighing error = 0.22 +/- %.
Note: The maximum range of mass flow through the meter was designed from 0 lbs/hr to 1817 lbs/hr. This mass rate does not necessarily represent the maximum permissible rate through this meter.
A RayMas® gravity flow meter was designed and calibrated for metering Green Oats. Green Oats has these properties: bulk density from 34.93 lb/ft3 (loose) and 37.67 lb/ft3 (tapped) and particle shape of about ½”-length and 1/8”-width in the center and tapering to the ends to a point. The RayMas® meter is shown as fabricated in Figure 10. The meter mass flow rate data comparing the RayMas® meter readings with the weigh scale readings are shown in Figure 11. The cross sectional dimensions of the flow tube of the meter were 12-1/2” x 22-1/4” I.D.
Fig. 10. RayMas® Non-contact Solids Flow Meter, Calibrated for Metering Green Oats, 12-1/2” x 22-1/4” I.D., Gravity Flow Type
Fig. 11. RayMas® Non-contact Solid Flow Meter, Gravity Type, Metering Green Oats
After installation into a production plant, test runs were made with the RayMas® in a production plant. The results of these runs in the production plant are shown in Table 3.Table 3. RayMas® Non-contact Solids Flow Meter, Metering Green Oats
|1||168||0 to 114,010||19,153,740||19,449,500||1.52|
|2||28||0 to 110,161||3,084,500||3,047,400||-1.22|
Note: Average absolute deviation from customer scale is 1.49 % +/-.
Weights & Measures (pounds)
Note: For Runs 1 and 2, the mass rate was estimated from the totalizer reading and the hours of the run. Operations at the customer’s plant could process Green Oats from no mass flow rate to maximum rate of the meter calibrated. At a test facility, the RayMas® meter was calibrated from as mass rate range from 0 to 175,000 lbs/hour.
The work in designing and calibrating the RayMas® meter for the product, Green Oats, demonstrated the flexibility in the design of the flow tube and microwave sensor when proper design criteria are followed.
A fine powder, an Ore oxide, needed to be metered into a high temperature process operation at a production plant. The Ore oxide had a fine crystalline powder having a particle size range from 0.5 to 1.5 micron. Flowing properties of this powder are poor to caking. The bulk density ranged from 103.8 lb/ft3 (loose) to 129.6 lbs/ft3 (tapped). The meter was designed and fabricated for this application. The installed meter is shown in Figure 4. The meter mass flow rate data comparing the RayMas® meter readings with the weigh scale readings are shown in Figure 12.
Fig. 12. RayMas® Non-contact Solids Flow Meter, 6”- diameter Gravity Type, Fine Powder
Product Metered: Fine Powder Ore, Particle size range between 0.5 to 1.5 micron
Whole Corn was to be metered using a gravity flow type of RayMas®. The whole corn had these properties: bulk density ranging from 56.3 lbs/ft3 (loose) to 58.1 lbs/ft3 (tapped). This whole corn was rather free flowing and had typical particle dimensions as 3/8” wide x 9/16” length and 3/16” thickness. Whole Corn was clean with minimal dust.
Comparison of the mass rate indicated by the RayMas® gravity flow meter and compared with weigh scale readings is shown in Figure 13.
Fig. 13. RayMas® Non-contact Solids Flow Meter, Gravity Flow Type, Metering Whole Corn
A Milled Shelled Corn was to be metered in a Pneumatic Conveying (P.C.) line, 10”-diameter P.C. line. The conveying was by dilute phase. The Shelled Corn was first milled in a Hammer Mill to particles typically 1/16” diameter to some at 1/8” diameter. The bulk density of the Hammer Milled Corn was 37.4 lb/ft3 (loose) to 49.8 lb/ft3 (tapped). The material was conveyed in a 10”-diameter line for about 400-feet with air at about 3500 cubic feet per minute (SCFM). The conveying line operation is under vacuum conditions.
Comparison of the mass rate indicated by the RayMas® Pneumatic Conveying (P.C.) type flow meter with the weigh scale readings is shown in Figure 14. The difficulty of metering this material in P.C. conditions is that the air used for conveying can be at high humidity (fog) atmospheric conditions and becomes rather tacky and sticky. This creates a material flowing through a pipe that sticks and then fluffs-off. Such erratic flow/transport conditions will demonstrate problems which need to be addressed by flow tube design considerations.
A picture of a 4”-diameter P.C. RayMas® meter in a test pneumatic test loop is illustrated in Figure 8.
Fig. 14. RayMas® Non-contact Solids Flow Meter, Pneumatic Conveying (P.C.) Type, 10”- diameter meter, Metering a Hammer Milled Shelled Corn
The RayMas® non-contact solids flow meter technology is in its infancy and of unique and proprietary design. The potential for this meter in the industrial market is substantial in the chemical, plastics, petroleum utility (power plants), food , pharmaceutical, cement, mining, farming for both gravity and pneumatic type of flow meters. As this new technology develops, so will the accuracy, ease of installation and calibration of the RayMas® meter. For more information, various process equipment and applications may be found in “Municipal Solid Waste To Energy Conversion Processes; Economic, Technical, and Renewable Comparisons,” by Dr. Gary C. Young, Ph.D., P.E., John Wiley & Sons, Inc. (publisher), June 2010, 384-pages.