BR-112016019054-B1 - METHOD FOR CONTROLLING, PREVENTING AND/OR INHIBITING THE FORMATION OF SCALE AND/OR DEPOSITS IN A REGULATED EVAPORATIVE SYSTEM

Abstract

METHOD FOR CONTROLLING, PREVENTING AND/OR INHIBITING THE FORMATION OF SCALE AND/OR DEPOSITS IN AN AQUEOUS SYSTEM AND COMPOSITION. The present invention relates to a synergistic mixture consisting of a polyamino acid and an anionic carboxylic polymer. The mixture is capable of effectively stabilizing calcium salts that lead to scale formation in evaporative systems. This mixture exhibits high levels of effectiveness in acidic, highly conductive waters found in many evaporative systems such as biorefining and sugar processing.

Inventors

• Christian Flocken
• JAY C. HENDERSON
• Christina Moering

Assignees

• SOLENIS TECHNOLOGIES CAYMAN, L.P

Dates

Publication Date

20260317

Application Date

20140411

Priority Date

20140306

Claims (8)

1. 1. A method for controlling, preventing and/or inhibiting the formation of scale and/or deposits in a regulated evaporative system, characterized in that it comprises: adding to the regulated evaporative system a composition comprising: (a) a polyaspartic acid; and (b) a polyacrylate having an average molecular weight of 500 to 50,000; wherein the polyaspartic acid and the polyacrylate may be added to the regulated evaporative system pre-mixed, simultaneously or sequentially, provided that they have sufficient residence time between them; wherein the regulated evaporative system has a pH of 1.0 to 5.0, wherein the weight ratio of solids of component (a) to component (b) is 3:1 to 1:1, and wherein the concentration of the composition added to the aqueous system is 0.1 ppm to 50 ppm based on the active ingredients, thus avoiding and/or inhibiting the formation of scale and/or deposits in the regulated evaporative system.
2. 2. Method according to claim 1, characterized in that polyaspartic acid and polyacrylic acid are premixed before being added to the system.
3. 3. Method according to claim 1 or 2, characterized in that the incrustations and/or deposits are calcium, magnesium, oxalate, sulfate and phosphate salts.
4. 4. Method according to claim 3, characterized in that the calcium and/or magnesium incrustations are of oxalates, carbonates and silicates.
5. 5. Method according to claim 1, characterized in that component (a) of the composition has an average molecular weight of 500 to 10,000.
6. 6. Method, according to claim 1, characterized in that the regulated evaporative system is selected from the group consisting of regulated food processing for direct or indirect consumption; biofinery and fuel ethanol processes; sugar processing; fruit and vegetable juice concentration processes; and food and alcohol fermentation processes.
7. 7. Method according to claim 6, characterized in that the alcohol or fermentation process comprises beer, wine and concentrated liquors.
8. 8. Method according to claim 6, characterized in that the regulated food processes comprise milk and dairy processes.

Description

[0001] This Patent Application claims the benefit of United States Provisional Patent Application No. US 61/948,829, filed March 6, 2014, the entire content of which is hereby incorporated herein by reference. FIELD OF THE INVENTION [0002] This invention relates to a composition comprising a polyamino acid and an anionic carboxylic polymer for controlling fouling in aqueous systems, for example, in evaporative equipment and heat exchangers such as those found in regulated markets. The invention also relates to a method for removing, cleaning, preventing, and/or inhibiting the formation of scale (fouling) such as calcium, magnesium, oxalate, sulfate, and phosphate scale from an aqueous system. [0003] These systems have unique demands due to their high conductivities, high levels of insoluble materials, and low pH regimes. BACKGROUND OF THE INVENTION [0004] Scale formation originates essentially from the presence of dissolved inorganic salts in the aqueous system that exist under supersaturated process conditions. Salts are formed when water is heated or cooled in heat transfer equipment such as heat exchangers, condensers, evaporators, cooling towers, boilers, and tube walls. Changes in temperature or pH lead to scale formation and fouling through the accumulation of unwanted solid materials at the interfaces. Scale accumulation on heated surfaces causes the heat transfer coefficient to decline over time and eventually, under heavy fouling, will cause production rates to be missed. Ultimately, the only option is often to shut down the process and perform a cleanup. This requires a production shutdown as well as the use of corrosive acids and chelating agents. Economic loss due to fouling is one of the biggest problems in all industries that deal with heat transfer equipment. Fouling formation is responsible for equipment failures, production losses, expensive repairs, increased operating costs, and shutdowns for maintenance. [0005] In order to prevent scale formation, a number of scale inhibitors are frequently employed in the field to prevent, delay, inhibit or otherwise control the scale formation process. The presence of scale inhibitors can have a significant effect on nucleation, crystal growth rate and morphology, even when the additive is present in very low concentrations. However, these effects are not easily predicted since subtle changes in pH, temperature, or scale type can have a significant impact. [0006] In the food and beverage industry (such as beer, wine, concentrated liquors, vegetable and fruit juices, fuel ethanol, and sugar refining), one of the most common components of scale formation is calcium oxalate. Oxalate is a natural component in plant life and can occur at high levels. During processing, oxalate is extracted and becomes part of the process water. In evaporators, a small amount of oxalate will become concentrated and begin to form scale after supersaturation. In the laboratory, we have found that calcium levels between 75 and 100 parts per million (ppm) are sufficient to cause oxalate scale precipitation. Calcium oxalate, also known as beerstone, and silica are the main components of compound scale formed in the later stages of the evaporation process and sugar mills, and form one of the most intractable scales to remove either by mechanical or chemical means. Removing scale is both expensive and time-consuming due to the tenacious nature of the deposit. [0007] Known methods for treating calcium scale in evaporative systems include a number of chelating mechanisms. Most commonly these have been polymers containing carboxylic acids, polymers containing phosphonates, chelating agents such as ethylenediaminetetraacetic acid (EDTA), or small organic acids such as citric acid. Polyaspartic acid has also been used in some applications. [0008] In some cases these materials have been mixed in order to increase performance. Phosphonates and polycarboxylates (United States Patent No. US 4,575,425), mixtures of citric, gluconic, and gluconolactone (United States Patent No. US 3,328,304), polyacrylamide and alginate or phosphonate (United States Patent No. US 3,483,033), phosphonic acids and EDTA (United States Patent Application No. US 20100000579 A1), mixtures of chelating agents including EDTA (International Patent Application No. WO 2012/142396 A1), and hydroxycarboxylic acids with citric acid (United States Patent Application No. US 20120277141 A1). It has been shown that many of these compositions are effective to some extent, but they often require high doses or materials that do not have appropriate regulatory clearance for food and beverage products. [0009] Polyaspartic acid has shown some level of effectiveness in inhibiting calcium fouling in sugar applications, but it required synthetic modifications to achieve higher performance (U.S. Patent No. 5,747,635). Polyacrylates have also been applied to similar fouling (U.S. Patent No. 4,452,703). The use of these materials has been