Hello Tamer, I guess you want to decrease the LSI of your water to reduce CaCO3 formation tendency. You can use sulfuric acid for pH adjustment i.e. LSI reducing. You will still need aniscalant. Consult your chemicals supplier for the proper choice of aniscalant. You also can pilot the process for evaluation. Regards, Taha
here is attached chemical analysis for the feed water to plate and frame heat exchanger, knowing that the operating temperature ranging from 80 up to 100 degree .
Citric Acid Dosing proposal to prevent scaling depending on [decreasing pH which by the same time decrease the alkalinity and by the way decrease the scale tendency.] is this assumption true or not
it's taken into consideration because other acids will cause problems as sulphoric will increase the sulphate ions leading to more scale concentrations and HCL will increase chlorides leading to corrosion
This analysis is not what we asked for. It shows only that anions of strong acids (not including nitrates) concentration is extremely high, making the water highly corrossive, especially for stainless steel.
We need additionally p-alkalinity, m-alkalinity, Ca++, Mg++ and cooling liquid temperaure (what water is cooling).
In which degrees you mention the temperature (80-100)?
> Of course, citric acid will lower the m-alkalinity and pH, resulting in lower scaling, but you already have highly corrossive water and if you add more acid it will be even more corrossive. I suppose you have much corrosion under scale formations.
The formation of calcium sulphate and calcium carbonate scale poses major problems in heat exchangers and water cooling systems, thereby affecting the performance of these types of equipment. In order to inhibit these scale formations, new types of biodegradable water soluble single polymer and dual poly (aspartic acid-citric acid) polymers are used.Silica Scale Removal is a powder based additive for descaling solutions for silica or silicates scales removal from heat exchangers,. The citric acid is inhibited with corrosion inhibitors but special care must be taken towards handling and storage.
Citric acid is an environment-friendly monomer since it derived from natural resources. Citrate has used as scale inhibitor for calcium carbonate (CaCO3). In order to inhibit these scale formations, new types of biodegradable water soluble single polymer and dual poly (aspartic acid- citric acid )
Citric acid is an efficient descaling agent that helps to remove scale, rust and grime deposits from various metal parts and still is safe for humans and in food grade applications. Citric Acid is also used as a cleaning agent or as a Descalant for cleaning of Heatexcahngers etc.
In Plate type Heat exchanger the circulation of citric acid with pump collecting tank and piping system, time to time (interval) iron analysis to be done for corrosion)
Care must be taken
Citric Acid is a weak organic acid, but is still corrosive to metal parts when used for cleaning or descaling purpose. Hence it should be used along with Citric Acid Inhibitor. The inhibitor functions as a corrosion preventive agent that does not allow the acid to corrode the metallurgy while descaling of the heat exchanger or metal.
AVOID LOW pH for corrosion control
The polymerization has confirmed to perform well and there are suspended carboxylic groups on the polymer molecules. Inhibition performance of new obtained poly (citric acid) for CaSO4 scale has evaluated by static scale inhibition method. When the dosage of polymer scale inhibitor is 2.5 mg/L in initial simulated scaling aqueous solution in which the ion concentrations of Ca2 + and SO42 − are both 2040 mg/L, the scale inhibition rate exceeds to 90%. When the dosage of polymer scale inhibitor is 25 mg/L, the scale inhibition rate is up to 98.8%.
Citric acid can be used for cleaning the scaling after its formation. Other acids canbe used for cleaning (sulphamic, formic, hydrochloric) and the choice is based on the material of the tubes. All these cleaners are effective for carbonates and magnesium hydroxide with negigible efficiency for calcium sulphate.
The prevention of the scaling by carbonates can be carried out in two alternative ways:
a) by venting all CO2 out before heating. According to the carbon curves, the carbon Equilibrium is 100% to free CO2 for acid pH (below about 5,8). Acidification is typically achieved by injecting Sulphuric acid (rather inexpensive)
b) by dosing antiscalant (typically a few ppm of polyphosphates or other brands such as Nalco 72990 or Belgard V)
Scaling by Sulphates is much more critical and the best prevention is to keep the temperature and Ca++ concentration below the precipitation curves (curves available). Some efficiency is ensured by special antiscalant brands (like Genesys) which are effective anyhow only at low working temperature (let's say below 60°C). After the formation, the only effective cleaning technique is the mechanical brushing.
In some cases, Ca++ was reduced by a pre-treatment of Nano-Filtration, thus preventing the formation of both sulphates and carbonates.
Mg(OH)2 scales only for very high temperature or very high alkalinity (curves available) but may scale along with carbonates and form a composite incrustation
Tamer, Take a look at the WSA Engineered System web site at www.wsaes.com . They offer a system known as ABS. They have many installation in US and prevents scaling and fouling in the plate and frame heat exchangers, without using any chemical. They also offer systems for the shell and tube heat exchangers.
Tamer, Hydroflow electronic technology has cleaned up and prevented scaling in many heat exchangers with no chemical use and can be fitted onto existing piping. www.hydroflow-usa.com or Hydropath in the UK. Take Care!
Hello Tamer, you can use a Water-Activator. He helps to:
Reduce of lime residue in pipelines.
Easy removal of lime residue on tiles, fixtures, etc.
Longer operating period for technical equipment .
No intervention in the plumbing systems.
Fast and simple installation; can be easily done by yourself.
No operating or maintenance costs.
This product is not based on any chemical, magnetic, radioactive or electrical processes whatsoever.
The LEKRA Water - Activator can be used in every possible plumbing setting: individual mains (sinks, showers, washers, etc.), one-room apartments, family homes, apartment buildings or even business or industrial buildings.After years of research, development and applications, all effects ascertained to be connected with the use of a LEKRA Water Activator have been positive.
Лучший способ предотвратить карбонатов в оборудование . Предлагает инновационный фильтр без сменных картриджей для удаления солей жесткости из воды снижает жесткость 7 раз. И началось оборудование для работы намного лучше.
Dear Tamer, you are not specified MOC of heat exchanger and applicable Temp.
you can use NaOH as scale softener before Descaling with 10% solution for 4-6 hrs as volume of system then use Sulfamic acid with 10% solution maintain pH 2-3 for cleaning till max. 4-6hr.
You need to do complete analysis of the scale and based on that and water chemistry parameters the reasons of scaling are to be correlated. There are good antiscalants available such as phosphonates, polymers. Based on water chemistry, operating conditions correct antiscalant can be identified. Inhibited sulphamic acid can be used for cleaning the existing scale deposits
Citric Acid serves better as a scale cleaner or Descaler not as a scale inhibitor. For Boiler Water Treatment Scale Inhibitor, you can use Sodium Hydroxide 5%, if the pH of the water needs to be adjusted with alkaline to avoid scaling. Sodium Hydroxide 5% and Sodium Molybdate 5% (in de-ionized water 90%) are good combination/formulation for Boiler Water Treatment Scale Inhibitor.
As previously stated, citric acid is a weak acid and must be used only for removing iron and manganese. It's not going to avoid calcium sulphate or silica scaling.
The problem is due to the inverse solubility of the calcium carbonate and sulphate, where the solubility decreases when the temperature increases.
Citric acid could avoid the calcium carbonate scaling if you reach the right pH ( Negative Langelier Index) but has nothing to do against Calcium Sulphate or Silica.
The solution is using the apropiate anti scalant from a recognized company like King Lee, Nalco, Genesys, etc, which have a battery of antiscalants for different scenarios.
Send the water analysis to them and they will solve your problem.
.. but for a verified answer we need the TH, alkalinity, Ca concentration, pH, TDS, temperature of water, skin temperature of exchanger (or higher temperature of cooling liquid) and construction material of piping and heat exchanger, in order to calculate the LSI and antiscaling treatment.