Crumbler Head Temperature Sensor

The purpose of this project is to develop a method of monitoring the surface temperature of a biomass grinder drum to notify the operator when product could potentially become damaged.

Background
Forest Concepts LLC. is a company that manufactures and maintains Biomass grinders for use around the country. Biomass is produced by taking chips of a variety of materials that can range from wood chips to corn stalks and running them through a grinder to reduce the chips into a size that can be rapidly burned for a heat source. Forest Concepts came to the University of Idaho seeking a design that could measure the surface temperature of the two rotating drums that grind up the material to monitor for overheating which could potentially damage their product.

Deliverables
Forest Concepts has asked for the following deliverables:
 * A reliable method of measuring temperature to ensure the product is not damaged
 * A cheap sensor array for a permanent fixture that can be implemented on all crumblers or
 * A removable sensor array that can be easily swapped between grinders if need be
 * A sensor output that is readable by industry standard PLC's
 * A method of verifying the temperature reading is accurate

Specifications
After communicating further with Forest Concepts, the following specifications were determined:
 * Maximum allowable temperature of 200 degrees Celsius


 * Common running temperature of 100 – 150 Degrees Celsius


 * Accuracy of +/- 10 -15 Degrees Celsius
 * 4-20mA industry standard for Sensors


 * 0-5 DC volts works for our operating system with their PLC


 * The main products are Wood Chips, and Corn Stock


 * The ash from these products is usually less than 3%


 * Crumblerhead is made of A2 Tool Steel


 * The teeth of the Crumblerhead are a Carbide Tip


 * Must have a method for the verification of effectiveness of our Temperature Sensor System


 * Prototype Sensor system will be tested on Forest Concepts Research Head

#1: IR Sensors
Design Idea: With each crumblerhead there are two cylindrical teethed rotating drums. So, for each of these drums we would have 5 IR sensors of Forest Concepts approval which would be evenly spaced out lengthwise along the drum. Each of these sensors will pick up a temperature for each section of the drum and whichever sensor is reading the highest temperature of the 5 will be displayed ion the PLC of the crumblerhead. The 5 sensors will be housed on the outside of the metal plates surrounding the crumbler head on either side of the drums for a total of 10 sensors per crumbler.


 * Pros


 * 1) Is a Permanent fixture to the system
 * 2) Cheap/easy maintenance
 * 3) Accurate to Forest Concepts wanted Specs
 * 4) Simple and effective


 * Cons


 * 1) Possible errors when high ash in-between the sensors and the drums
 * 2) Could have coding errors when trying to create functions to show max temperature with the sensor array

#2 Thermocouple on end product
Design Idea: At the end of the conveyor belt where the product is eventually drop into a container or bailer, we would have a thermocouple rod that as the product falls by it or passes by it on the conveyor it makes contact and the thermocouple would readout that temperature to the PLC.


 * Pros


 * 1) Directly measuring the product rather than the crumblerhead drum
 * 2) Simple to setup and install
 * 3) Cheap
 * 4) Is a permanent fixture on the system


 * Cons


 * 1) Hard to make sure your temperature readout function is accurate
 * 2) The time between the product leaving the crumblerhead and where the thermocouple is at may give the product time to cool down, providing inaccuracy.
 * 3) Possibly not very durable