Volumetric flow monitoring of a CIP plant using moneo RTM

The initial situation:

ifm performs tests with process sensors in a real environment using their own CIP plant. Before moneo was introduced, the plant was operated via analogue signals and controlled via a PLC. Visualisation of the process was only possible on site at the plant's HMI. Surveillance was restricted to the analogue 4...20mA signal value.

Implementation:

moneo is already installed centrally on a server and the necessary modules, including moneo RTM, are activated. The IO-Link masters are connected to the server via an internal VLAN.

An already installed analogue sensor from Endress & Hauser (Promag 50) was used to record the flow. It was made IO-Link capable by retrofitting (ifm Y path). An evaluation system and display for analogue signals (DP2200) was used. This has an analogue input 4...20mA. The signal can additionally be looped through the unit and is thus still available for the plant’s PLC. This enables easy integration without affecting the plant control.

Bottom line:

The plant was digitised successfully without any changes or interventions to the existing PLC or software.

The moneo dashboard provides the user with an overview of the relevant process values for this plant. The following dashboard visualises the primary parameters (flow, temperature and conductivity) in the inlet:

1. Pressure at the feed pump in bar
2. Conductivity in the inlet in µS/cm
3. Flow in L/min
4. Flow velocity in m/s
5. Temperature in the inlet before the heat exchanger in °C
6. Temperature in the inlet after the heat exchanger in °C

Another dashboard shows more details about the flow.

1. Current pressure at the feed pump in bar
2. Comparison of pump pressure and flow in a line diagram
3. Raw value of the DP2200 input signal in mA
4. Calculated flow rate from the analogue current value in L/min
5. Calculated flow velocity from the flow rate in m/s

The following values are calculated additionally based on the volumetric flow.

Current flow in L/min

The start and stop values of the analogue sensor were determined using the data sheet:

• Start value 4mA = 0 L/min
• Stop value 20mA = 200 L/min

This results in a valency per milliamp of 12.5 L/min.

This 12.5 L/min per milliamp is now used as a factor for calculation.

1. Present current value in mA
2. Factor 12.5 l/min per mA
3. Offset -4 for conversion from 4...20mA to 0...16mA
4. Multiplication factor with current value
5. Result of the calculation in L/min

Conversion flow (L/min) to velocity (m/s)

The flow velocity is a decisive parameter for the success of the cleaning process; this value can be determined on the basis of the current flow and the constant cross-sectional area of the pipe.

V = velocity in metres per second [m/s]

Q = flow in cubic metres per second [m³/s]

A = cross-sectional area in square metres [m²]

Example with pipe radius 0.02m and a flow of 200L/min:

1. Current flow in L/min
2. Factor for converting L/min into m³/s (1 minute = 60 seconds, 1,000 litres = 1m³)
3. Constant radius of the pipeline in m
4. Constant Pi (3.1415)
5. Flow in L/min divided by 60,000 gives flow in m³/s
6. Squaring the radius (r²)
7. Multiplication r² by Pi, result cross-sectional area in square metres
8. Flow in m³/s divided by cross-sectional area (m²)
9. Result of the calculation in m/s