pH Neutralization System

The waste water treatment plant consists of two technological loops: :

  • main tank for neutralization and sedimentation with an pump and two valves for circulating and draining;

  • tank for NaOH with dosing pump, shut-off valve and heater to maintain the required reagent temperature

The process control system consists of a control panel and measuring and control units:

  • control measuring equipment– sensors, probes, transmitters and controllers and a programmable logic controller(PLC);

  • actuators – pumps, valves and heater for (NaOH)

Stages of Neutralization

The neutralization process takes place in several stages – time homogenization, pH neutralization, time settling and draining.

The start of the neutralization process in automatic mode is possible by three conditions: – at a set time of day by an activated astronomical clock in a PLC; – by set up of high level of the main reactor for automatic start; or by START Process button on the front side of control panel.

Measurement

  • pH electrode
  • pH transmitter
  • ATC fot pH
  • Reactor temperature
  • NaOH temperature
  • NaOH level probe
  • Capacitive level probe

Controllers

  • PLC
  • pH controller
  • Reactor level
  • NaOH vessel level
  • Reactor temperature
  • NaOH temperature

Alarms and protections

  • Low level NaOH
  • Low level reactor
  • High temperature reactor
  • Low temperature NaOH
  • Motor protection
  • Thermal protection

Automatic Mode

Превключвател AUTO- MAN в положение AUTO

The start of the neutralization process in automatic mode is possible by three conditions:

  • at a set time of day by an activated astronomical clock in a PLC;

  • by set up of high level of the main reactor for automatic start;

  • by START Process button on the front side of control panel.

Manual Mode

In manual mode, the operator can switch on or switch off pumps P1 and P2 independently of one another and manage valve status V1 (recirculation) and V2 / drain / via a three-position switch.

Alarm Conditions

In both modes the operation of the system is blocked by a number of alarm conditions, which are indicated by the LEDs of the STOP buttons, and in the automatic mode there is an sound alarm.

The sound alarm can be turned off for a certain period of time to repair the fault. After this period, if there is an alarm situation, the sound alarm is switched on again. The sound alarm does not come in manual mode, because it is assumed that the light is sufficient in the presence of an operator.