powerful antioxidants

Roasting coffee beans a dark brown creates powerful antioxidants

Friday, February 11, 2011 by: S. L. Baker, features writer

 http://www.naturalnews.com/031291_coffee_beans_antioxidants.html

Roasting with the PID

Since I have wried the PID into roaster, I have roasted twice, and just one small batch at a time.
Due to the fact that both gas lines had to be re-routed and modified, and I have been dealing with many leaky gas lines.
The reason for the new gas lines was because I needed to maintain a burning flame on the main burner.
When the PID pulses on and off as it nears the set point, the burner needs to be already lit.

During the first roast, I did have a flare up on the left side where the gas line enter for the main burner, only scorching some electrical wires, but I quickly turned off the main valves and power to the PID. After the flame went out, not wanting to ruin a batch of coffee, I quickly resumed roasting. The Roast was lite.

During the second roast, I located another leak, this one was because I had a 3/8 flare fitting attached to non-flare. This roast turned out better as I didn't need to have the gas pressure set to higher than normal.
But I  did notice that even though the PID turned off, the gas valve was not disengaging properly.
During preliminary  testing using a neon bulb, I notice current was still running through the bulb even when the PID s output was off.
I wonder it that small amount of juice could keep the valve turned on after the initial actuation.

Here are the main parts

MYPIN TA-4 SNR PID Temperature Controller, Dual alarm
Thermo-coupler RTD PT-100, 385
SSR-25 DA Solid State Relay N.C
1/2" 110-120 VAC Brass Electric Solenoid Valve Gas N.C

The PID operates at 110vac and the output is 4-20mA.

For now I'm using just 1 output, pins 3 and 4  wired directly to the SSR inputs.

The thermal coupler is a RTD from Watlow, so it's wired using connector pins 7 and 10 jumpered and 8 and 9 jumpered.
with the output wires from the thermal coupler going to pins 7 and 8.
On the controller I have selected the thermal coupler option PT .
I have also selected Fahrenheit(F), no other changes except for the set point.

Adding a PID to the roaster.

I have decided to add a PID to the roaster, Thus reducing temperature overshoot and in many cases under temps during roast times.

Here are a couple of pictures of the project so far.

PID controller stands for proportional–integral–derivative controller


In simple terms, here's an analogy :

Your driving on the freeway and you see the traffic slowing down ahead,  do you speed forward at normal speed until your there and braking is eminent less you plow into the car in front of you..

Or do you back your foot of the gas, and cruise up to the slowness slowly..until you match the changing traffic speed.