Brine Concentrator Scaling

Published on by in Academic

We have a problem with anhydrite (CaSO4) scaling on heat transfer surfaces of a series of brine concentrators (mostly MgSO4 at 20 – 40% TDS and pH 0.8 – 2.0).

How can we reduce scaling?

The usual approach of controlling elevated total suspended solids (TSS) is only partially successful.

Taxonomy

17 Answers

  1. Our company has developed and manufactures a cost-effective, green-rated, non-toxic, non-hazardous, bio-degradable scale remover. This should eliminate your scale problem without damaging surfaces, pipework, seals, membranes or other equipment.

    Please email me at andrew@waterandoilsolutions.com.au for more details.

  2. Interesting problem and some of the responses. Several mentions of polyacrylate - which is a well known, quite effective calcium sulfate precipitation inhibitor.  Look at PAA of ~3000 molecular weight...you might also test a blend with a higher molecular weight - maybe approaching 10,000.   The MWs do not need to be tight...but the 3,000 realm is generally better known for inhibition performance.

    Years ago a Amino   amino hexamethylene phosphonic acid was also rated quite highly as a calcium sulfate inhibitor.

    Answered on by

    1 Comment

  5. You can reduce the SO4 concentration by passing the brine through Lewatit A365 resin.

  7. Check out the following.  http://www.merusonline.com/

    I don't know if this device really works as they are claiming, but you have nothing to lose and might as well try it. If you are going to try it, please let me know how it performs as I have been looking for an application to try it.

  8. Dear  Stephen,

    The disposal or management of desalination brine (concentrate) is expensive and faces major environmental challenges. In spite of the scale of this economical and environmental problem, the options for brine management have been limited. This brief review presents an overview of the existing methods on brine treatment, minimization, and disposal practices based on the newest and most updated technologies. Calcium sulfate is the predominant chemical compound present in the feed to the brine concentrator.It is desirable to maintain operation at design conditions to help prevent scale deposits.calcium sulfate scale is more soluble than other mineral scales such as CaCO3, BaSO4, and SrSO4, once it has developed it is difficult to eradicate mechanically and is insoluble in mineral acids and other conventional solvents.

    High TDS and saturation of low-solubility scaling salts such as calcium sulphate (CaSO4) and silica (SiO2) limit the percentage of water that can be recovered in a conventional evaporator system.The brine concentrator uses a unique process called seeded slurry evaporation to overcome the limitation imposed on conventional evaporators by the saturation limits of low solubility scaling compounds. The seeded slurry process involves establishing and maintaining slurry of CaSO4 seed crystals in the circulating brine in the evaporator. With careful thermal and mechanical design, CaSO4 and SiO2 can precipitate preferentially on the recirculating seed crystals instead on the tubes. The ultimate concentration achievable in the brine concentrator is limited by the boiling point elevation of the brine, the relative concentrations of sulphate and chloride (e.g. the double salt, CaSO4•Na2SO4 does not form), and the solubility of the sodium salts. The brine discharged from the brine concentrator is further concentrated in the crystallizer.

    Following are the procedure of Scaling removing,

    1. Muraitic acid to be used for descaling
    2. Vinegar also to be used for descaling
    3. High pressure water jetting about 300-400 bar to be used.
    4. ​Install a ball cleaning system to keep the ​internal walls. Intermediate brine treatment process to remove scale-forming chemicals
    5. Mechanical brushing to be done.
    6. To prevent the scale formation sulfuric acid is added to the feed tank to react with the calcium carbonate.
    7. Addition of anti-scale compounds such as sodium hexametaphosphate (NaPO3)
    8. The high tubes velocities help reduce scale formation. Low velocity promotes sedimentation of the salts causing scaling.
    9. Lime softening is used for the removal of sulfate via the precipitation of gypsum (CaSO4•2H2O).

     

  10. Use "SMBS"

    Sodium meta bi-sulfate

    Dose it 3 to 5 ppm per liter of water

     

    Any doubts contact

    Email:abdulgaffar557.ag@gmail.com

  11. GMXINTERNATIONAL.COM magnets on your pipes will ELIMINATE SCALE PERMANENTLY without the use of chemicals ever again. Check it out.http://GMXINTERNATIONAL.com

  12. Use a SweepCLEAR separator in conjunction with a HydroFLOW water conditioning.  HydroFLOW removes calcium ions from the water turning them into crystals which SweepCLEAR can remove.  Www.sweepclear.com ,   www.hydroflow-usa.com 

  14. Dear Stephen,

    I am involved in this problem since decades, and I found as follows:

    There are no safe techniques to prevent scaling by CaSO4 besides limiting the concentration of the brine below the saturation by CaSO4. The solubility is rather indipendent from pH but is heavily influenced by the temperature. The silubility is about 4200 ppm up to 45°C, then it sharply decreases to about 2500 ppm at 75°C, 1600 ppm at 100°C and below 1000 ppm at 150°C. The weight of Ca on CaSO4 is about 29%, hence the concentration of Ca in the brine should be less than 1200 ppm below 45°C, less than 725 ppm at 75 °C and lesst than 460 ppm at 100°C.

    The oversaturation is always a very risky situation and the antiscalant for carbonates are ineffective for CaSO4. There is an antiscalant produced by Genesys effective for CaSO4 but the effectiveness is significant only up to 50°C and eventually zero above 60°C (Hence it is mostly used for ambient temperature processes like RO)

    You may try to reduce the working temperature thus increasing the solubility and therefore to improve the Max brine concentration before scaling.

    Alternatively you may try to install a ball cleaning system to keep the internal walls of the tubes bright through the continuous brushing of abrasive balls (details in the website of Taprogge and Others)

    In any case my advice is not to work in risky conditions because the removal of scaling by CaSO4 cannot be made satisfactorily by acid cleaning and eventually requires for mechanical brushing. The adheramce of scaling on non-passivated tubes (like Titanium) is lower (easier brushing) than on passivated tubes.

    Should you need any additional information, please contact me privately

  15. Dear Stephen,

    First I will pay attention to the temperature of the water as most of the time this is the cause! Check also wind and any nutrient coming into the water. As it was said, analyzing PH and Chlorine is a basic start.

  16. Dear Stephen 

    Would be useful to know the analysis of the raw water , including the turbidity and SDI , the concentration factors at each evaporator ,  and the final rejected water analysis  to better estimate the required solution.

    We may add the frequency of cleaning , what are you cleaning with,  and what you get from the cleaning (what is the type of deposits you get). Cleaning solution before and after cleaning  analysis would be of a great value.  

  17. using antiscalant which would remove the scale formation.

    1 Comment

    1. Dibya. Scale inhibitor will not remove the scaling layer of CaSO4. Once it has been formed, Poly acrylic acid or poly phosphonate will not dissolve the scaled layer.

      Scale inhibitor only controls the scaling phenomena in the early stage (Nucleation step) or in moderate stage through adsorption on the particles that intended to form crystals and prevent the crystal growth.

      Only the optimum solution to prevent scale is to revise the operation parameters and design, and try to keep the recovery under the limit that initiate scale. There are many programs that predict the scale and giving alarm for the treatment and operation process. 

      Calcium sulfate scaled layers are not dissolved in mineral acid such HCl & H2SO4, using an alkaline solution such NaOH which increases the solubility of sulfate scale.

      Calcium sulfate scaled layer is different than other scale such calcium carbonate which is easily dissolved in diluted mineral acid, sometimes sulfate scaled layer becomes a hard and rough which almost difficult to be cleaned.