What are the ​Most Prominent ​Methods to ​Handle Hard ​Scale Formation ​in Plant Boiler ​?

Hi,

We have a water treatment plant that is designed to treat APO wells water through ion exchange unites to produce water with total hardness < 1PPM.

The treatment water is  feeding two types of boilers- One Through Steam Generation & Heat Recovery steam Generation. 

Hard scales had been collected during the mechanical cleaning with approximately 1- 1.5 ton per each unit. Based on the scale analysis by XRD & EMS the majority of scale are Sodium-calcium silicate – Pectolite ( NaCa2Si3O8(OH)) - Calcium silicate – Wollastonite ( CaSiO3). The BFW Specs as below:-.

1) Chloride 3000 ppm
2) Silica 110 ppm
3) Dissolved O2 2 ppb
4) pH OTSG – 7 - 8, HRSG – 8. 5
5) Total Iron OTSG – 1 ppm, HRSG – 0.25 ppm
6) TSS 1 ppm

What are the most prominent methods to handle Hard scale Formation in plant boiler?

Looking for your valuable feedback.