Ecopreneur

Monitoring And Process Control

Currently, it is possible to monitor and control a plant’s process worldwide, 24 hours a day. This includes all variables involved: temperature, pH, dissolved oxygen (DO), turbidity, level, flow rate, products generated, time involved, disconnection, waiting, failure, state of equipment, start-up and stop, among others.

This information can make a difference to production planning and operational management of a plant, since real insight of the process over time can be obtained, which enables to:

  • Maximize plant performance
  • Control what it is treated/produced
  • Conduct preventive maintenance programs for equipment
  • Adjust the variables of interest
  • Optimize reagent consumption

Flow and Level Measurement

Flow and level measurement (as an indirect flow measurement) is one of the main plant control parameters, as well as distribution network leak detection.
There are different kinds of technologies available depending on water quality and where the measurement is required.

Channels and distribution network
At the entrance of raw water plants, there are several options for measurement technology:

• Radar
Radar’s main use is to measure flow in channels, chambers and open pipe lines. It is installed without contact with the fluid, which is a great advantage.

• Transit time. For water with turbidity less than 50NTU.
This option is advantageous to measure flows in an open pipeline or in channels with variation in the water level. In these cases, in addition to flow rate measurement, which is made by a pair of sensors, it is necessary to have an external level measurement connected to the controller to instantly calculate the wet area and to recalculate the flow rate.

• Electromagnetic
This kind of flow meter is only used to measure flow in conductive fluids. These devices are used in filled pipes (under pressure), and they measure liquids having a conductivity higher than 50 μS/cm.

Sewage Water Collectors
It is essential to know the wastewater flow from a community to define the pumping and collection facilities that will be required.The collector and network for sewage measurement mainly consists of electromagnetic and external measurement equipment. The technologies to be used include the following:

• Electromagnetic

• Doppler
This method works only with fluid containing particles, gas bubbles or others reflecting sound waves. Its application is focused on channels and pipes filled with constant flow conditions.

• Correlation
Equipment can be portable or stationary, and submerged or using insertion sensor.
Portable devices allow the periodic record of conditions in a collector with varying autonomy, depending on the configured measurement cycle. They work optimally in places where there isn’t an electric grid supply.

Hydroelectric
To measure the power factor of a hydroelectric plant and to perform efficiency tests on generating units, it is essential to measure the flow in pressure or conduction pipes from power plants, as well as in the inlet piping to a run-of-river hydropower station.

Water Quality for Irrigation

The quality of irrigation water and proper management of irrigation is necessary to obtain successful crop production.

Irrigation water quality affects both crop yield and soil conditions, even if all other conditions and production practices are auspicious and optimal.

The quality of some water sources may vary according to the season (dry or rainy), which is why online measurement is recommended to provide a quick response to such changes.

Depending on the crop kind, it is necessary to control the concentration of certain parameters such as:

• pH

• Conductivity

• Total, Free or Combined Chlorine

• Peracetic Acid

Drinking Water Quality

The measurement of process parameters in water purification depends on the type of process carried out and also on the quality of the water to be treated. Some processes include:

Desalination and Reuse

Turbidity removal

Arsenic removal

Iron and Manganese removal

In the following charts, different stages of water purification can be observed, along with those parameters which are controlling each operation in the generic process:

Parameter to be measured/Process Stage

Plant Inlet

Coagulation & Flocculation

Clarification & Filtering

Disinfection

Distribution network

pH

X

X

X

X

X

Conductivity

X

X

X

X

X

ORP

X

X

X

X

X

Turbidity

X

 

X

 

 

Free Chlorine

 

 

 

X

X

Fluor

 

 

 

X

X

Ozone

 

 

 

X

X

Flow and/or Level (Flow and Level Measurement)

X

 

 

X

X

 

Quality in Sewage Water

Measurement of process parameters in either domestic or industrial wastewater treatment is determined by the sort of process carried out according to the quality of the water to be treated.

The chart below shows different stages of a generic wastewater treatment process and the parameters which are measured in each operation:

Parameter to be measured/Process Stage Plant Inlet Aeration Primary

& Secondary Clarifier

Nitrification Aerobic or anaerobic digestion Disinfection Distribution Network
pH X X X X X
Conductivity X X X
ORP X X X
Turbidity X X
Total Suspended Solids (TSS) X
Dissolved Oxygen (DO) X X
Free Chlorine X X
Fluor X X
Ozone X X
Flow and/or Level (See Flow and Level measurement) X X X
Gas Detection

Fixed Gas Detector 

Portable Gas Detector 

H2S Meter