Boiler Superheater tubes precleaning & passivation?

Published on by in Technology

A power plant that is going to have a new boiler asking if there is any procedure to clean/preserve/passivate the super-heater tube before it is put into operation.

Since the super-heater tube is not meant to be submerged under water, I am not sure if there is any procedure that can be done to clean/preserve/passivate the super-heater tube.

Thanks in advance for your input.  

7 Answers

  1. We have supplied a protective solution to a nuclear power station to protect and stop corrosion in the tubes. It is done before installing the tubes.

    What are the tubes made of and what was the problem found with the old boiler and tubes?

    If you email me at office@gictechs.com I will pass it on to our tech boys to make sure we can help

     

  2. Typical cleaning of the entire system including the steam superheating section, is a caustic boil out, where a service company comes in with circulating pumps, the necessary chemicals, and you supply sufficient quantity and quality water for the cleaning solution, to be circulated on a schedule of concentration, pH, temperature, and time.  After the solution, it is very important to rinse until no residues of the chemical are found in the return water.

    System is then drained completely, and the superheated steam output header is provided with what is known as a steam blow line with impingement target.  The target is changed after each prescribed steam blow, checked for signs of particles issuing forth with the steam, and steam blows continue until the last target out come back clean, and undamaged.

  3. I have a different perspective. 

    If the superheater was manufactured without any metalworking oils and the manufacturer did not apply any protective coatings to the surfaces, then you might be able to allow the superheater to passivate during commissioning and normal operation IF you can confirm that there is no carryover and that the hydro test was conducted with deionized water.

    If the superheater has oil residue or the hydro test was conducted with water quality that was NOT deioinized, - AND the superheater IS DRAINABLE - you will have to isolate the superheater and conduct a boil out procedure for oil or rinse the superheater with deionized water. 

    If the superheater is not drainable - then you either have to clean the superheater before installation or take a risk and not clean or rinse the superheater. And, I hope that the superheater has an isolation valve so you can clean and passivate the boiler without having water enter the superheater.

    Clean superheaters will passivate during normal operation. The challenge is - knowing if the superheater is clean.

  4. Boilers operating above 900 psig, driving steam turbines, and having super heaters should be pre-cleaned and pre-passivated prior to startup - including the superheater.  There are many qualified cleaning companies and water treatment consultants that can provide specific recommendations.  These may include either liquid or vapor phase cleaning/passivation, depending upon the needs of the particular boiler.

  6. HI,Before boiler  The pre-commissioning cleaning involves Alkali cleaning-HI PH and followed by LO PH cleaning.

    When the Superheated tubes installed Nitrogen gas packing is important to remove oxygen or moisture.

    High pressure boilers are designed to produce steam at a specified quality. Improper steam quality can lead to tube failures in the boiler, as well as turbine blade damage, resulting in large availability loss. The cleaning of internal surface of high pressure boiler can be grouped into two main methods, one pre-commissioning and the other post-commissioning cleaning.

  7. Of course, superheater should be passivated before start up, as well as steam and condensate piping. As each water treatment Chemical producer has different types mixtures for such application, you should contact with the most trusted one in your area.

    If you need to passivate only the superheater, it can be performed making a closed circuit, recirculating the passivating agent, following appropriate instructions. 

    1 Comment

    1. Hi, what pasivation agent could be used?