[Gasification] Scada (SCADA)

Rex Zietsman rex at whitfieldfarm.co.za
Sat Apr 23 02:14:39 MDT 2016


Mark,

And then for the brave (read mentally retarded, stupid for taking this on), there are microcontrollers that are VERY cheap <$10 each. We have built an Arduino system for the control of our 20kWe gasifier that does the following:
- air to fuel ratio from using an oxygen sensor (as found on modern cars) on the exhaust with a servo motor controlling a ball valve
- throttle control using a pulse detection on the engine flywheel with a servo motor controlling a ball valve
- three K-type temperature sensors: preheated inlet air, syngas outlet and combustion zone temperature. K-type is good to 1250oC
- two waterproof temperature sensors on our cooling water circuit
- 4 combined pressure and temperature sensors. These are absolute pressure sensors with a sensitivity of 30Pa and use temperature to do an adjustment to the pressure measurement algorithm giving you two outputs for one sensor. dP is then by difference
- 2 dP pressure sensors for gas flow measurement using a restriction orifice for dP
- three water level float switches
- three water solenoids for level control
- there are two interfaces - a simple 8 character, 7-segment display split between rpm and mV from the oxygen sensor; and a touchscreen that allows you to view temperatures and pressures
- real time clock with battery back up that gives real time for saving date stamped data
- SD storage module with 32GB back up
- GSM module for sms'ing data as required

Total cost: <$1000

Downside: It takes a while to get on top of the programming and understanding of what the sensors are capable of. Thereafter it is only your imagination that is holding you back.

Rex Zietsman

From: Mark Elliott Ludlow [mailto:mark at ludlow.com] 
Sent: Thursday, 21 April 2016 8:05 PM
To: 'Discussion of biomass pyrolysis and gasification' <gasification at lists.bioenergylists.org>
Subject: Re: [Gasification] Scada (SCADA)

I agree with Leland “Tom” Taylor completely. My last project was a DDS (Distributed Control System) and we employed 19, μ-controllers (microcontrollers), that had digital and analog IO, math primitives, plenty of power and were interconnected by plain old Ethernet. Data collection and storage was a no-brainer. Software development could proceed a subsystem at a time. I would never do anything different, unless I were stuck in a 1970 time warp. We used 19” touch screen monitors, placed wherever they were needed. Histograms of process performance (stability, rate, energy usage, etc.) were available anywhere, including my living room sofa. 
On a later project in MX I used a Siemens Simatic system. Is was much less flexible, cost at least four-times as much and had distributed I/O collectors but not distributed process management intelligence. Tons more wiring. No redundancy. Proprietary architecture. Mostly much slower but that’d not be as much an issue on a gasifier as  it may be on motion control. And Siemens was years ahead of U.S offerings, who only until relatively only offered archaic Ladder Logic programming tools.
Best, Mark

From: Gasification [mailto:gasification-bounces at lists.bioenergylists.org] On Behalf Of mailto:linvent at aol.com
Sent: Thursday, April 21, 2016 7:40 AM
To: mailto:gasification at lists.bioenergylists.org
Subject: Re: [Gasification] Scada

or as those are obsolete, go with  a laptop with touch screen a USB port, a two wire or wireless interface to your sensors and control devices and a program that runs on your computer that doesn't need to be programed like the plc. 
Sorry to hear that there are those out there who are still using the archaic plc architecture as it only makes for more work.
Sincerely,
Leland T. "Tom" Taylor
Thermogenics Inc. 





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