Brick Plant Efficeincy Improvments upwards of 25%
MC- Series Moisture & Hardness Controls - Technical Overview
The MC- Series Moisture Controller is a PC based unit in combination with its accompanying electronics and power sources. The controller is a software driven machine offering the computing power of the standard "off the shelf “ but Cadillac version of a personal computer (PC). The electronics accompanying the PC is also software driven with a Multi-microprocessor (9) based control. The entire system is power interrupt protected by a standard "off the shelf" 750 W UPS.
The control manages the moisture content of the final product by accurately (+/- 0.15%) measuring the moisture content of the incoming raw material through the use of our moisture detecting camera. Before the incoming raw material is presented to the Pug Mill or other mixing device, an in-line belt scale measures the weight of the raw material and transmits this to the MC- Series control. The distances to the Belt Scale from the mixer as well as the distance of the Moisture Camera from the mixer are stored in a set-up table. This allows the MC- Series control to align the moisture content data and weight data in data bundles as the product moves on the belt toward the mixer. The position of each foot of raw material along the belt is know and kept track of for every data package. In the event the belt stops, the MC- Series control knows where the material is in relation to the mixer until it is eventually processed. In the event of a power outage the UPS will keep the MC- Series controller alive for a period long enough to store the positional data of the raw material along the belt and the runtime parameters on it's hard drive. Therefore when power returns, the controller can pick up the process where it left off before the outage. Another advantage of positional tracking is that varying belt speeds and varying weights will not present a problem in metering the final makeup water to the mixer. This is a major problem for Jeffery in that he is unaware of the constant fluctuations in feed weight until it is too late to correct for it. The MCC System at Elgin is equipped with a Raw Feed control system which will closely maintain a constant feed rate using the belt scale, encoder and variable voltage output loop to vary your Toshiba Drive directly. Any error in feed will be compensated for by the standard MCC functional corrections it normally makes for Mass Flow Corrections.
The MC- Series controller will calculate the additional required water in order to bring the desired moisture content of the raw material up to a set point determined by our customer's process needs. Water additions, although continuous and steady, are added in metered packets which correspond to data packets along the belt. After the current packet is added to the mixer, the control measures how accurately it did as a feedback mechanism. The final Moisture content is calculated according to the following formulas:
Determine Dry Weight of Raw Material Weight from conveyor:
Raw Material Moisture Weight = ((%Moisture from camera) / 100) x Raw Material Weight from conveyor)
Dry Weight = (Raw Material Weight from conveyor) - (Raw Material Moisture Weight)
Calculate Required Moisture to make final weight:
Final Extruded Weight = (Dry Material Weight from above) / ((100 – Desired Moisture Set point) / 100)
Final Moisture to Add = (Final Extruded Weight) - (Dry Material Weight from above) - (Raw
Material Moisture Weight)
At a Moisture set point of 15%
Final Extruded Dry Weight = 0.85 x Final Extruded Weight
Final Water Weight including Raw Material Moisture = 0.15 x Final Extruded Weight
The water is delivered via a proportional flow valve supplied by JEC. The flow rate is monitored by a digital flow meter which is also supplied by JEC. The size of the water system is determined from customer hourly tonnage output.
1 Inch System
From 30 tons / hour to 80 tons / hour (0.8gpm to 80 gpm)
The overall accuracy of the water system is about a teaspoon in 80 gal/min.
There is a master cut off solenoid to insure that the water supply is cut off when it should be and there is a 15 Mesh SS Strainer installed to insure that your spay nozzles remain free of clogging debris.
The MC- Series Moisture Control uses the high impedance load cell connection from this Belt Scale for higher accuracy. OEM belt scale controllers are not compatible with the MCC Moisture Control as all belt scale manufactures’ controllers output in rate. The MCC control requires mass only output which is not available. Therefore the MCC only uses the direct load cell connections which, with our amplifier and in conjunction with a high resolution encoder, will provide the MCC with the mass and flow speed required for the positional tracking of the raw material.
The MC- Series Moisture Camera should is installed between 16" to 48” above the product. The distance to the product can vary greatly (at least +10" to - 10") without affecting the readings from the material significantly. This allows for large clumps and piles to pass by the Moisture Camera and still obtain accurate readings from the material. The Moisture Camera uses Far Infra-Red absorption technology in extremely narrow bandwidths (< 20 nm) from multiple wave lengths to determine moisture content in the surface of many different types of materials. Although the MC- Series Moisture Control is capable of accepting billions of curves as standard, only one curve for each type of pure raw material form is needed. The additions of color additives will not require new curves as the MCC is not affected by color. One curve for each type of raw material is sufficient for accurate moisture control.
The Camera aperture and light source are kept dust free by purging the collimating tube and light source cavity with filtered air. The filtered air supply is also monitored by the main control to insure that the purge air is being delivered to the camera. The Main Control cabinet is cooled by the use of a 4000 BTU Air Conditioner which will prolong the life of the control components. The Preventative Maintenance of these cooling systems is monitored by the Main Control Unit and maintenance messages will be displayed when service or filter replacement is needed.
Five separate outputs of 4 to 20 ma. (up to 250 ma.) or any voltage output from 0 to 10 vdc are available as standard which corresponds to the current Dry Weight of the incoming Raw Material Weight. This allows for the accurate dispensing of additives which are based on Dry Weight thereby saving costs generated by guessing. Since most feeders do not produce a linear response to the input signal, all feeders can be profiled to produce a modified signal for the desired feed rates. A Barograph read out on the screen is standard which displays the tons/hour for dry weight as well. These output loops can be reconfigured to vary belt speeds to maintain constant a MASS FLOW if desired. This feature has been activated at your plant for Raw Material Feed.
If a very low water pressure is experienced (< 30 psig.) the Water valve will turn off and the audio alarm will sound. Also, if a low dirt level on the belt scale is sensed, the valves will turn off and a low dirt alarm will sound. The level of low dirt poundage is programmable. Finally, if the belt stops, the valves will also turn off for the duration of this state and will resume adding water when the belt restarts.
A new Penetrometer sensor was developed to allow our Hardness Control to function with low die lube pressures. We also furnish a new Head Pressure Probe as well. The MC-C Control will maintain a consistent Column Temper to an operator adjusted Penetrometer set point. As minor variances in recipe occur due to unpredictable mixing practices or variations in raw material sizing occur, Hardness Control will sense these errors and automatically make corrections to the Water addition rate to correct the extruded hardness or column temper and achieve the desired extruded Hardness set point. With the Hardness Control installed the operator should rarely, if ever, need to make any adjustments at all. Extruded Hardness should always be very tightly held to the customers desired penetrometer target.
The unit will not solve 100% of your dimensional variations because differences in mix makeup and particle sizes imply different absorbability slug to slug. However, eliminating these deviations caused by constantly changing Raw Feed Characteristics and inconsistent moisture absorbability rates, both of which create inconsistent extruded hardness which also implies size variations, will improve scrap rates markedly. The MCC system detects the changing Raw Feed Characteristics as they occur. It will see a changing raw moisture content as it occurs. It will adjust the water valve instantaneously to correct for proper extruded moisture content to obtain a correct column temper. This results in a drastic improvement since the operator cannot see problems until the material is extruded.
As the material is finally extruded the moisture set point of the extruded column will be tailored to keep the column at a constant temper to correct for mix and sizing errors from the grinding dept. No other system on the market can achieve results similar to our MCC System in performance. No other system has any kind of column temper control.
Product can be purchased through Frecon Technologies, Inc. 513-874-8981
President - Journey Electronics Corp.