Claims:We Claim:
1. A polymer coating material for preventing corrosion, the coating material comprises:
novolac epoxy filled with ceramic; and
Titanium Carbide and Novolac vinyl ester epoxy filled with glass flakes.
2. The polymer coating material for preventing corrosion as claimed in claim 1, wherein the polymer coating material comprises Novolac filled with ceramic reinforced with 2.4% to 2.6% TiC powder and Novolac vinyl ester epoxy filled with glass flakes reinforced with 2.4% to 2.6% TiC powder
3. The polymer coating material for preventing corrosion as claimed in claim 1 or 2, wherein the polymer coating has a thickness of 1.5mm to 2mm.
4. The polymer coating material for preventing corrosion as claimed in claims 1-3, wherein the polymer coating has a bond strength of 2500-3100.
5. The polymer coating material for preventing corrosion as claimed in claims 1-4, wherein the polymer coating has a shore hardness in the range of 80-85.
6. A method of preparing polymer coating material for preventing corrosion comprising the steps of:
preparing coating surface by sand blasting of surface;
mixing of novolac epoxy filled with ceramic, Titanium Carbide and Novolac vinyl ester epoxy filled with glass flakes to prepare a mixture;
applying the mixture on the coating surface; and
drying of coating surface.
7. The method as claimed in claim 6, wherein the drying of coating surface is carried out for atleast 72 hours.
8. The method as claimed in claim 6 or 7, wherein the mixture is applied on the coating surface by airless spray/ hand roller/ brush.

Dated this 04th day of March 2022
, Description:CORROSION RESISTANT POLYMER COATING AND METHOD OF APPLICATION THEREOF

FIELD OF INVENTION
[001] The present subject matter described herein, relates to a corrosion resistant polymer coating on carbon steel rods and plates or similar steel products without restricting scope of the invention to the same and method for applying for preventing corrosion in FGD Absorber.
BACKGROUND AND PRIOR ART OF THE INVENTION
[002] Since Flue gas desulfurizing (FGD) system in thermal power plants is used to reduce SOX and NOX level in the flue gases. FGD system majorly comprises of components like Absorber, Pumps, FGD duct and Stack. All these components experience severe corrosive atmosphere. Hence there are number of measures in the form of coatings/Linings to prevent the corrosion of Absorber, Duct and Stack wall materials. FGD absorber is most affected with corrosion and erosion due to gypsum slurry formed in it. To prevent absorber from corrosion and erosion, it is made of Hastelloy C276 material which is highly expensive.
[003] Through extensive literature search was made to replace C276 cladding with coatings similar in performance but lower in cost. It is found that Polymer coating (NOVOLAC Epoxy) is one such coating which is highly corrosion, chemical and erosion resistant and much lower in cost when compared with C276 claddings. Hence, this triggered us to develop polymer coatings for FGD absorber.
[004] Flue-gas desulfurization (FGD) is used to remove sulfur dioxide (SO2) from exhaust flue gases in thermal power plant. To remove SO2 from the flue gas, lime stone slurry is sprayed, which comes in contact with flue gas and reacts with SO2. Gypsum is produced as a byproduct along with the H2SO4 which settles in the absorber. Due to presence of H2So4 the absorber will be prone to sever corrosion. To avoid this corrosion, currently C276 cladding is being used which is complex process and imported at high costs.
[005] Further, FGD absorber is prone to severe corrosion and erosion due to presence of H2SO4 in the gypsum slurry. Currently C276 cladding is being used on carbon steel plate to prevent this corrosion and erosion. However C276 cladding is highly expensive and it is to be imported. Polymer coatings are highly corrosion, chemical and erosion resistant and much lower in cost when compared with C276 claddings.
[006] Patent Application No: CN1789351A directing to a glass flake clay paint is being used for FGD application. Another prior art discloses a method of preventing corrosion in FGD duct and Chimney liner by advanced polymer coating as a replacement of titanium cladding developed for the application of FGD duct and Chimney liner.
[007] None of the above prior arts can fulfill the requirements of the invention for which it is designed. Hence, the present invention has been introduced.
OBJECTS OF THE INVENTION
[008] It is therefore the object of the invention to overcome the aforementioned and other drawbacks in prior art.
[001] The principal objective of the present invention is to develop a suitable and cost effective polymer coating to replace C276 in the FGD absorber.
[002] Still another object of the invention is to provide corrosion resistant polymer coating, which is simple in composition and easy to prepare.
[003] These and other objects and advantages of the present subject matter would be apparent to a person skilled in the art after consideration of the following detailed description taken into consideration with accompanying drawings in which preferred embodiments of the present subject matter are illustrated.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[001] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter, and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods or structure in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[002] Figure 1a illustrates Novolac filled with ceramic reinforced with 2.4% to 2.6% TiC powder in accordance with an embodiment of the present disclosure;
[003] Figure 1b illustrates Novolac vinyl ester filled with glass flake reinforced with 2.4% to 2.6% TiC powder in accordance with an embodiment of the present disclosure;
[004] Figure 2 illustrates Immersion testing as per the ASTM D543 carried out on polymer coted samples, C276, Titanium, carbon steel and Stainless steel in accordance with an embodiment of the present disclosure;
[005] Figure 3 illustrates Immersion test weight loss vs Samples in accordance with an embodiment of the present disclosure;
[006] Figure 4 illustrates Acid spray test carried out polymer samples along with C276, titanium, carbon steel and stainless steel in accordance with an embodiment of the present disclosure;
[007] Figure 5 illustrates Taber wear test for checking the wear resistance of the polymer samples in accordance with an embodiment of the present disclosure;
[008] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
SUMMARY OF THE INVENTION
[009] One or more drawbacks of the conventional technology based on existing apparatus and processes are overcome, and additional advantages are provided through a novel a corrosion resistant polymer coating and method for applying for preventing corrosion in FGD Absorber.
[0010] Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be a part of the claimed disclosure.
[0011] In an embodiment of the present subject matter, the polymer coating material for preventing corrosion comprises novolac epoxy filled with ceramic , TiC and Novolac vinyl ester epoxy filled with glass flakes.
[0012] In another embodiment of the present subject matter, the the polymer coating material comprises novolac epoxy filled with ceramic reinforced with 2.4% to 2.6% TiC powder and Novolac vinyl ester epoxy filled with glass flakes reinforced with 2.4% to 2.6% TiC powder
[0013] In another embodiment of the present subject matter, the polymer coating has a thickness of 1.5mm to 2mm.
[0014] In another embodiment of the present subject matter, the polymer coating has a bond strength of 2500-3100.
[0015] In another embodiment of the present subject matter, the polymer coating has a shore hardness in the range 80-85.
[0016] In another embodiment of the present subject matter, the method of preparing polymer coating material for preventing corrosion comprising the steps of preparing coating surface by sand blasting of surface, mixing of novolac epoxy filled with ceramic, TiC and Novolac vinyl ester epoxy filled with glass flakes to prepare a mixture, applying the mixture on the coating surface and drying of coating surface.
[0017] In another embodiment of the present subject matter, the drying of coating surface is carried out for atleast 72 hours.
[0018] In another embodiment of the present subject matter, the mixture is applied on the coating surface by airless spray or hand roller or brush.
[0019] It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined to form a further embodiment of the disclosure.
[0020] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS
[0021] The detailed description of various exemplary embodiments of the disclosure is described herein with reference to the accompanying drawings. It should be noted that the embodiments are described herein in such details as to clearly communicate the disclosure. However, the amount of details provided herein are not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the present disclosure as defined by the appended claims.
[0022] It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and embodiments of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof.
[0023] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a",” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
[0024] It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
[0025] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
[0026] FGD absorber is prone to severe corrosion and erosion due to presence of H2SO4 in the gypsum slurry. Currently C276 cladding is being used on carbon steel plate to prevent this corrosion and erosion. However, C276 cladding is highly expensive and it is to be imported. Polymer coatings are highly corrosion, chemical and erosion resistant and much lower in cost when compared with C276 claddings. Therefore, the present disclosure discloses a novel corrosion resistant polymer coating to replace C276 cladded plate in FGD absorber.
[0027] In accordance with an examplary embodiment of the present subject matter, the different polymer coatings are coated on the carbon steel rods of size 15mm (d) X 150mm (l) and carbon steel plate of dimensions 100mm X 100mm X 3mm. A polymer coating material for preventing corrosion comprises novolac epoxy filled with ceramic and Titanium Carbide and Novolac vinyl ester epoxy filled with glass flakes.
[0028] In another embodiment, the polymer coating material comprises Novolac epoxy filled with ceramic reinforced with 2.4% to 2.6% Titanium Carbide powder and Novolac vinyl ester epoxy filled with glass flakes reinforced with 2.4% to 2.6% Titanium Carbide powder. The polymer coating has a thickness of 1.5mm to 2mm. The polymer coating has a bond strength of 2500-3100. The polymer coating material has a shore hardness in the range of 80-85.
[0029] In another embodiment of the present subject matter, a method of of preparing polymer coating material for preventing corrosion comprising the steps of preparing coating surface by sand blasting of surface, mixing of novolac epoxy filled with ceramic, Titanium Carbide and Novolac vinyl ester epoxy filled with glass flakes to prepare a mixture, applying the mixture on the coating surface, and drying of coating surface. The the drying of coating surface is carried out for at least 72 hours. The mixture is applied on the coating surface by airless spray or hand roller or brush.
EXPERIMENTAL TESTS
[0030] Table 1- List of polymer coating samples
S. No Supplier Name Composition
1 Sample 1 Multi-functional epoxy with ceramic filled.
2 Sample 2 Novolac filled with ceramic,
3 Sample 3 Novolac vinyl ester filled with glass flake
4 Sample 4 Novolac vinyl ester filled with glass flake
5 Sample 5 Grafted co-polymer

[0031] Immersion corrosion test:
[0032] Immersion testing as per the ASTM D543 is carried out on polymer coted samples, C276, Titanium, carbon steel and Stainless steel. Table 2- Immersion test typical parameters
Chemical Solution Temperature Duration PH Value
30% H2SO4 700C 10:00 hrs 0.5-0.8

[0033] Each sample is washed thoroughly with running water and completely dried. Visual observations are noted for each sample like, blister formation, color changes, crack in coatings, etc. Weights of each samples are measured before and after the test with 0.01gm accuracy weighing machine. A fresh 30% H2SO4 is prepared and replaced.
[0034] The samples before and after 1000 hrs of immersion testing are shown in the figure 1 and weight loss is shown in the figure 2. It can be observed that, multi-functional epoxy and acrylic co-polymer coatings are failed and also weight loss is more in comparison with other samples. Carbon steel and Stainless steel samples were completely dissolved in the solution by the end of 200hrs. Novolac filled with ceramic, Novolac vinyl ester filled with glass flake and C276 sample are intact and no weight loss was observed. Weight loss in titanium is about 30 gms.
Pull off adhesion test (ASTM D4541)
[0035] Pull of adhesion known as bond strength is conducted on each polymer coating. In this test a dolly of 15mm dia was glued on flat carbon steel plate with polymer. After full curing the dolly was pulled using portable pull odd adhesion tester. This test was conducted 3 times on all polymer samples and the results are tabulated in table 3. In this all the coatings are intact except Grafted co-polymer.
[0036] Table 3: Pull off adhesion test results
Sl No Supplier Name Composition Bond strength (PSI)
1 Sample 1 Multi functional epoxy with ceramic filled. 3000-3100
2 Sample 2 Novolac filled with ceramic, 2800-2900
3 Sample 3 Novolac vinyl ester filled with glass flake 2500-2600
4 Sample 4 Novolac vinyl ester filled with glass flake 2900-3000
5 Sample 5 Grafted co-polymer 700-900

Shore hardness - Scale D test (ASTM D2240):
[0037] Shore hardness of the polymer samples was tested on scale D though digital shore hardness tester. It is observed that shore hardness is in the range of 80-85 which is satisfactory.
Taber wear test (ASTM D4060):
Taber wear test is done to check the wear resistance of the polymer. Samples were prepared by applying polymer coating on a 100x100x3mm carbon steel plates. Taber wear test was done for 3000 cycles on a load of 1000kg and results are shown in figure 5. From figure 5 it can be observed that, all polymers showed satisfactory results for taber abrasion except co-polymer (sample 5) and it lost more weight in comparison to other polymers.
Addition of Titanium Caribe (TiC)
Based on above experiments, we can observe that Novolac filled with ceramic and Novolac vinyl ester filled with glass flake have shown excellent chemical, corrosion and were resistance. To improve properties further Titanium carbide (TiC) was mixed in different proportion with the Novolac filled with ceramic and Novolac vinyl ester filled with glass flake coatings. These TiC added coatings were also tested for all the above tests and showed better results to chemical, corrosion and were resistance in comparison with without TiC addition.
Advantages of The Invention
1) The polymer coatings developed in this invention can replace the expensive C276 cladding in the FGD absorber. Hence, there will be reduction of cost of coating is approximately 1/3rd of C276 cladding.
2) These polymer coatings can be applied easily using airless spray gun whereas C276 cladding is complex process.
3) Weight of polymer coating is less compared with C276 cladding. Hence there will be overall weight reduction of the FGD absorber.
Working of The Invention
[009] The method of preparing polymer coating material for preventing corrosion comprises the steps of preparing coating surface by sand blasting of surface, mixing of novolac epoxy filled with ceramic, Titanium Carbide and Novolac vinyl ester epoxy filled with glass flakes to prepare a mixture, applying the mixture on the coating surface, and drying of coating surface. The drying of coating surface is carried out for at least 72 hours. The mixture is applied on the coating surface by airless spray or hand roller or brush.
[0010] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0011] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”
[0038] It will be further appreciated that functions or structures of a plurality of components or steps may be combined into a single component or step, or the functions or structures of one-step or component may be split among plural steps or components. The present invention contemplates all of these combinations. Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. In addition, while a feature of the present invention may have been described in the context of only one of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention. The present invention also encompasses intermediate and end products resulting from the practice of the methods herein. The use of “comprising” or “including” also contemplates embodiments that “consist essentially of” or “consist of” the recited feature.
[0039] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations, which fall within the scope of the present subject matter.