Calculate the gas consumption of the furnace

Hello ,

Topic Headline: Flow Totalizer

Good afternoon, I am doing a project of a reheating furnace and I have to calculate the gas consumption of the furnace, from the information of the flow transmitter that started a signal of 4 ..20mA, I am using a Siemens PLC S7400. There is some block that does this integration and I got the result.

 What you need is to scale the physical data from analog input to floating point value by help of scale function(FC105) and use the totalizer logic,you can use the block in the following link or develop your own code:

How can you accumulate physical flow measurements (e.g. mass flow rate, flow velocity) to an overall value?

I hope it helps,

hdhosseini

Hi

1. for how long do you need to integrate it? if for a vary long time you may need to use 64-bit Real
    to prevent rounding errors (another route is to calculate chunks as integer and add to an dinteger
    value which will prevent errors)
2. first convert flow from AI to engineering units (use SCALE function)
3. use either timed OB (i.e. OB35) or a timer to create a pulse for integrator
4. when pulse is detected calculate chunk of volume = flow * time between pulses.
    convert it to dint or 64-bit real and add to total value.
    if using 64-bit real convert total to normal real for scada display.

for long periods do not use standard 32-bit real because rounding error will occur i.e.

n + a = n where n>>a i.e. 10000000 + 0.000001 will show 10000000 when precision of data type
is not good enough.