LabJack T7

Frustrated with inconsistencies and poor documentation of the Raspberry Pi and Arduino  boards. Radical decision time! Searched the internet for a better solution, industrial grade, tested and with a real manual. Found LabJack T7 with the ability to measure thermocouples directly.
T7 HW Desc

The T7 family of devices has the resolution and amplification necessary to directly measure raw thermocouple signals.  If you save 1 channel for an external cold junction temperature sensor a single T7 can measure up to 13 thermocouples itself .

 

 

 

 

The power-meting with an ACS712 goes also directly. In the picture below it’s hooked up to AIN0 with a reading of 2.526106 whit no current flowing and 5V power-supply.

1stemeting

It comes with a extensive library with functions to integrate in different programming environments like Python C++ etc.

 

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ACS712 Olimexino-stm32 Powermeter

How to measure AC current in watts.

After a couple of failed attempts to make a reliable power-meter to measure the electricity that is consumed by the infrared heaters I backtracked  and went back to a earlier design. With an Olimexino_stm32 Maple clone board and an ACS712 the last piece of the computer-control is operational.

The ACS712 chip 20A has a linear curve of 100 Mv per ampere between -20 till 20 ampere from 0,5 volt till 4,5 volt by a supply-voltage of 5 volt

asc712 module
asc712 module

The Olimexino_stm32 works only with 3.3 volts. With a resistor divider (potentiometer between 5V and ground trim the output till 3.3V and you have the correct divider)
on the output of the ACS712 is fed into the ADC of the Olimexino-stm32, as long there is no current flowing the division is nearly linear so take at least 4,7K as value.
The Olimexino stm32 has a 12 bit DAC digital analog converter. 2^12 is 4096 the zero-crossing is at 2048
If the measured value is less than 2048 the relevant voltage = 2048 min the measured value (example 2048 – 490 = 1558)
If the measured value is more than 2048 the relevant voltage = the measured value min 2048 ( example 3567 – 2048 = 1519)

olimexino-stm32 The result is only positive values. 3.3 Volts divided by 4096 = 0.00080566 volt per bit step. Multiplication of the measured value with 0.00080566 gives the voltage of the output from the ACS712 every 1 mV = 0.001V = 0.01 amp. So if we measure as value of 1346.5 Millivolt = 1.3465 Volt it’s 13,465 ampere (volts times 10 or millivolts divided by 100)
According to the Law of Ohm P=I*V The voltage of the net in Europe is 230Volt when we combine the previous step volts times 10 with this one we get 23 as multiplication factor
By preforming many measurements in rapid succession(1000)and store every measurement we get a clear picture of the real power that is being used.
after 1000 measurements we calculate the mean value and look is there is any interest in the value. If not we start a new cycle.

Here is the complete working sketch powermeter olimexino stm32 maple sketch

https://www.olimex.com/Products/Duino/STM32/OLIMEXINO-STM32/

http://www.allegromicro.com/en/Products/Current-Sensor-ICs/Zero-To-Fifty-Amp-Integrated-Conductor-Sensor-ICs/ACS712.aspx

 

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Last bits

The last bits are coming together, piece by piece.

Not being able to extent the meter long lead from the thermocouples I used a plastic food-container as cheap box to mount the TC boards on the backside of the testfurnace.

TC Boards
Thermocouples boards

Last step in the software development get a graphic user interface. The furnace has a micro-controller that preforms the measurements and controls the heaters. The micro controller is connected to the mirco-computer that gives the commands and logs the operation.

GUI
Python & Tkinter

After trail and error it seems the furnace will finally get a real KWh meter. From Maxim we got two 78M6613 IC’s for free and Faber Electronics mounted them on the Adafruit breakout boards. It’s a real RMS single phase wattmeter where with a single command you get the used watt’s, precisely!

Two Maxim 78M6613 IC's
Two Maxim 78M6613 IC’s

After the big Arduino one board and the mess that gave in the connection to the UEXT connector on the Olimex boards I ordered a Olimexino-nano

Olimexino-nano Arduino Leonardo compatible mircocontroller board
Olimexino-nano Arduino Leonardo compatible mircocontroller board
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Prototype

After a while we got the 29th April of 2014 our prototype infrared pyrolysis furnace from the metal workshop, next will building the gas-processing and computer controlled electrical parts together.

Prototype pyrolysis furnace outside
Prototype pyrolysis furnace outside
Prototype pyrolysis furnace with door open
Prototype pyrolysis furnace with door open
Air  pump first stage evaporation process
Air pump first stage evaporation process
Air compressor for secondary stage
Air compressor for secondary stage
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Control software

Step by step are the pieces coming together. The Raspberry Pi was not reliably for real time operation so we added an Arduino for the critical timing communication over the I2C bus. The Arduino in combination with the ACS712 samples and calculates the total electrical power consumption of the furnace.

ArduinoUno_R3_Pinouts

acs712 module
acs712 module

ACS712 current sensor

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Assembly test-oven

m4s0n501

Assembly of the test-oven. Nearly everything fits as planned. We’re getting closer to the first public pet-pyrolysis demonstration as an alternative for pet-cremation.

construction parts
The metal parts
door
The 90 mm door isolated with Promasil 1000 calcium silicate board
montage 2
Drilling holes for bottom screws
montage 3
Everything fits together.
montage 4
Vents holes and electrical and thermocouples wires on the backside
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Fu Shou Yuan

Fu Shou Yuan, valued at about $1.4 billion, expects death services in China to become a $16.5 billion industry by 2017. The company said that proceeds from the stock sell-off would be used to purchase land that is suitable for clients’ eternal slumber.

Image Credit: Flickr via Eddie Awad
Image Credit: Flickr via Eddie Awad

Despite its huge success, the Chinese government isn’t too thrilled about Fu Shou Yuan taking up valuable real estate in heavily congested cities. Amid criticism from both state media and members of the public, who assert that some burial service providers charge exorbitant fees and disregard industry standards, the communist government has recommended cremation – even burial at sea – as more sustainable alternatives.

“Despite the government’s disapproval, many Chinese still prefer traditional burial,” wrote Bloomberg. “For them, Fu Shou Yuan offers a wide selection that includes artistic tombs designed, as the company touts on its website, ‘totally according to the customers’ interest and requirements.’ … E-commerce is booming in China, so naturally Fu Shou Yuan has an online shopping option, with customers able to choose from more than 60 different tombstones.”

Those hoping to be enshrined at one of Fu Shou Yuan’s high-class burial facilities must have banks accounts as large as those of the celebrities already resting there. A plot in Shanghai reportedly sells for more than $30,000 – and that is the basic cost of land, without burial fees, headstones, or any other cemetery swag.

On the other hand, the Chinese government has promised to pay Shanghai residents’ families approximately $330 to scatter their ashes over Hangzhou Bay. With more than 9 million deaths a year, China is expected to run out of space to bury them in as little as six years.

source the diplomat

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Calcium Silicate isolation

The calcium silicate isolation, before the final assembly start it’s wise to check if everything is made according to plan. Two pieces are the wrong size. Luckily we have got extra material to experiment with and we can easily correct the problem. The CS board is Promatec 1000L bought by Moors Ovenbouw.  http://www.moorsovenbouw.nl/

Try to fit the pieces together, we have a gap.
Try to fit the pieces together, we have a gap.
Overlapping layers of CS board give a total of 90mm of isolation
Overlapping layers of CS board give a total of 90mm of isolation
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Burial Stress

Burials being delayed as floods create dangerous conditions at graveyards

Floods in Somerset and the Thames Valley have seen funerals put on hold as wet ground is too dangerous for gravediggers

Flooded cemeteries and even those outside flooded areas where the ground is waterlogged are causing difficulties in digging graves. Photograph: Michael Scott/Demotix/Corbis
Flooded cemeteries and even those outside flooded areas where the ground is waterlogged are causing difficulties in digging graves. Photograph: Michael Scott/Demotix/Corbis

 
The flood crisis is causing further anguish for bereaved families as wet ground is making burials impossible in the worst-hit areas.
Authorities say there is little they can do about weather-related funeral delays that have been described as “absolutely abnormal”. While families face the possibility of extra distress, the floods have created dangerous conditions for gravediggers.
Crematoriums have not been immune from the issue either, with one having to close for about two months due to flooding.
Source The Guardian 18-2-12014

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