AC/DC Conversion Unit And Polariser For Caustic Soda Plant

AC/DC Conversion Unit And Polariser For Caustic Soda Plant

AC/DC conversion unit and polariser for caustic soda plant provided by Green Power has the advantages of high reliability, stable output current, power saving etc.

Product Details

AC/DC conversion unit and polariser for caustic soda plant

1. AC/DC conversion unit and polariser for caustic soda plant

Sodium hydroxide (NaOH), also known as caustic soda is a widely used chemical produced by electrolysis of an aqueous NaCl salt solution (brine). The resulting product is caustic soda lye or liquor, a NaOH solution in demineralised water.

As an industrial commodity, caustic soda holds a pivotal position in the manufacture of a wide range of industrial and consumer products.

AC/DC conversion unit provide stable DC current for caustic soda Ionic membrane electrolyzer shown below, it is critical part of the electrolysis process to produce caustic soda. 


2. Why Choose Green Power?

  • Rich experience: More than 20 years design, production and service experience for caustic soda

  • Meet international Standards:  products exported to more than 40 countries.

  • Strong technical ability:PhD technical team, more than 20 years technology accumulation, first class technology. Self developed DSP digital controller.

  • Reliable quality:Designed, manufactured, tested as per strict reliability standard, ensure reliable running

  • Considerate service: Professional service before, during and after sales. Lifelong after service system. Customer management system

  • High performance price ratio:With Europe/USA quality, competitive price than Europe. 

  • Fluent English communication: the team has excellent writing and oral English communication ability.

3. AC/DC conversion unit and polariser for caustic soda plant Block Diagram

AC/DC conversion unit and polariser for caustic soda plant includes high voltage switchgear, rectifier transformers, Rectifier, control panel, heat exchanger, high current DC current measurement sensor, polarization rectifier, DC disconnector, connection copper busbars, computer monitoring unit. Harmonic filter and power factor compensation facility is optional. 


4. AC/DC conversion unit and polariser for caustic soda plant typical main circuit configuration


6. Proposal Summary of AC/DC conversion unit and polariser for caustic soda plant 

  • The power source is designed to supply DC current for Caustic Soda production.

  • The Power supply(Rectifier) system with input voltage 30kV or other input voltage, rated output DC according to customer's requirement, it is 12 pulse, three phase bridge circuit.

  • The rectifier transformers primary side adopt star connection, secondary has two windings, one adopt star connection, the other adopts adopt delta connection. Vector group is Y,d11y0. Or other vector group.

  • Transformer is equipped with voltage regulation transformer and on load tap changer 27 taps, regulation range 50%-100%.

  • Transformer is OFWF cooling.

  • Transformer tank material where LV and NPT terminals are brought out non-magnetic (SS304)

  • Thyristor Rectifier adopt 3 phase bridge, 12 pulse. Thyristors are N+1 redudancy design, if one thyristor fails per phase, the unit could continue to give rted output(n-1 thyristor in operation).

  • Each thyristor is series connected with one fast action fuse, isolate faulty thyristor without damage to the other thyristors, and there is fuse protection.

  • Thyristor is protected from over voltage surges by connecting RC snubber and Surge Arrestor.

  • Rectifier is cooled by demineralized(DM) water, cooling system has 100% redundancy for DM water pump, heat exchanger and associated instrumentation and piping. Pipes are stainless steel material. 

  • Separate control panel is provided, computer monitoring unit is provided.

  • PLC is Siemens S7-300 series

  • Winding in transformer and bus bar in rectifier is copper material.


7. Main Technical Parameters of Rectifier for Caustic Soda



Technical parameters



Green Power Co., Ltd.


Part number






No. of cubicles



Nominal current

DC 17.2kA


Nominal voltage

DC 300V


Semiconductor element to be used



Type of rectifier

Three phase bridge


Number of pulses



Short time overload capacity

150% for 60 seconds once in 24 hrs.


Continuous with n elements in operation



Continuous with “n-1” elements in operation



Type of control

Digital control


Type and mode of control

Constant current/voltage


Remote control communication with DCS through

RS485 or other communication specified by customer



One thyristor fault per arm alarm, two thyristor fault on same arm trip.

One fuse fault per arm alarm, two fuses fault on same arm trip.

DM water very high temp. Trip

DM water flow low, alarm

DM water flow very low, trip

Mixed cartridge and filter is provided to maintain the conductivity of DM water

Interlocks through DCS

Emergency trip push button station

Earthing fault monitoring

Surge arrestor

Thyristor RC snubber

Fast action fuses

Phase loss

Input over/under voltage

Short circuit

Output current limit

Bus bar temperature

Rectifier over heat

Output over voltage

Output over current

Cooling water low pressure

Cooling water high temperature

Insulation protection

And others required by purchaser


Water cooling system

Pump and heat exchanger N+1 spare



Color touch panel





Mechanical Structure

Control parts are in control panel

The doors is provided with suitable transparent cover

All bolts and nuts in rectifier are stainless steel material.

Aluminum alloy material or powder coating steel carbon or stainless steel material for cabinet

8. Company Introduction Video

Contact us:

Reply you within 1 hour during Beijing time 7:00 a.m to 10:00 p.m.

Whatsapp: +86 13810151476

Wechat: 65044167

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