FIELD OF THE INVENTION:

The present invention relates to a corrosion inhibitor composition. Specifically, the present invention relates to a corrosion inhibitor composition which acts as a corrosion inhibitor additive for hydrocarbon fuel transportation through pipelines. Further, the corrosion inhibitor composition inhibit corrosion when dosed into an aqueous interface in fuel pipelines such as an aqueous interface plug in a multi-product petrochemical fuel pipeline.

BACKGROUND OF THE INVENTION:

Pipelines are the most cost effective, energy efficient, safe and environment friendly mode of transportation of petroleum products. They ease the overburdened Rail & Road infrastructure and minimize the environmental impacts arising out of Rail & Road transportation. Pipelines play a significant role in meeting the demand and supply of petroleum products around the world.

Pipelines are further made effective by transporting multiple products (at least two) in a single pipeline e.g., Motor spirit (MS) and High-speed diesel (HSD). However, HSD contaminated MS affects the performance of MS especially in terms of octane. As a result, a plug is used between MS and HSD to retain the specifications of these products transported through pipelines. Currently, superior kerosene oil (SKO) is being used as a plug. However, there are two limitations for SKO plug usage. For successful implementation of BSVI norms for MS and HSD, SKO quality also needs to be upgraded, which involves recurring costs. In addition, the demand for domestic SKO is decreasing and its liquidation would be difficult. Hence, an economic and non- interfering plug is desirable to provide operational flexibility.

Hence, water can be envisaged as an interface plug which is economic as well as non-interfering. However, the main bottleneck while water being used as interface plug is its corrosivity and emulsification with the petrochemical products. Accordingly, a suitable formulation is required that acts as corrosion inhibitor when water is used as interface plug. Some of the known corrosion inhibiting compositions are described hereinbelow. US5849220A discloses a corrosion inhibiting composition for use in inhibiting corrosion of metallic surfaces, the composition comprising a first surfactant wherein the first surfactant includes at least one sorbitan fatty acid ester and a second surfactant, wherein, the second surfactant includes at least one polyoxyethylene derivative of a sorbitan fatty acid ester.

B. Balanaga Karthik et al. in Asian Journal of Chemistry 24(8):3303-3308, title “Phosphonic Acids used as Corrosion Inhibitors-A Review” discloses that inhibition of corrosion and scaling can be done by the application of inhibitors. It is noted that the effect of corrosion inhibitors is always caused by change in the state of surface being protected due to adsorption or formation of hardly soluble compounds with metal cations. Several phosphonic acids have been used as corrosion inhibitor along with metal cation such as Zn ²⁺ . The synergistic effect between the inhibitors gives more inhibition efficiency. Phosphonic acids are inhibitors, which have been used due to their stability, ability to form complexes with metal cations. They are adsorbed on metal surface through these polar atoms. The adsorption obeys various adsorption isotherms. The film has been analyzed by many technologies such as, FTIR, SEM, UV-Visible spectra, EIS and electrochemical studies like polarization and AC impedance.

The above disclosed corrosion inhibiting compositions are useful in inhibiting corrosion of metallic surfaces. However, there is a need for a corrosion inhibiting composition which inhibit corrosion arising due to an inert aqueous interface in fuel pipelines such as an aqueous interface plug in a multi-product petrochemical fuel pipeline.

SUMMARY OF THE PRESENT INVENTION:

The present invention relates to a corrosion inhibitor composition containing 1 -Hydroxy -Ethane- 1, 1-Diphosphonic Acid (HEDP) in 70-99% by weight, Polysorbates in 1-20% by weight, and Benzalkonium chloride (BKC) in 1 - 10% by weight.

The present invention relates to a corrosion inhibitor composition having 1 -Hydroxy-Ethane- 1, 1- Diphosphonic Acid (HEDP) in 94-97% by weight, Polysorbates in 2-5% by weight, and Benzalkonium chloride (BKC) in 0.5-3% by weight. Further, the present invention relates to a corrosion inhibitor composition having 1 -Hydroxy - Ethane-1, 1-Diphosphonic Acid (HEDP) in 95-96% by weight, the Polysorbates in 3-4% by weight, and the Benzalkonium chloride (BKC) in 1 -2% by weight.

In the present corrosion inhibitor composition, the polysorbates are selected from polysorbate 20, polysorbate 40 and a mixture thereof. Specifically, the polysorbates includes a mixture of polysorbate 20 and polysorbate 40 in a weight ratio of 1 : 1.

The corrosion inhibitor composition acts as a corrosion inhibitor additive in an aqueous interface as such but not limited to an interface plug in a multi-product petrochemical pipeline. The said interface plug consists of an aqueous medium selected from tap water, brine water, seawater, or a combination thereof. When the said corrosion inhibitor composition is added into an interface plug, the said composition prevents emulsification between the aqueous interface and a petrochemical product. Further, the said corrosion inhibitor composition inhibits a microbial induced corrosion.

The present invention also relates to a method for inhibiting corrosion, wherein, the method includes adding the corrosion inhibitor composition into the aqueous interface. Specifically, the corrosion inhibitor composition is added in a range of 400 ppm to 1100 ppm for achieving at least 90% corrosion inhibition efficiency.

The said corrosion inhibitor composition acts as a corrosion inhibitor additive in an aqueous interface selected from an interface plug in a multi-product petrochemical pipeline. The corrosion inhibitor composition when added in the aqueous interface prevents emulsification between the aqueous interface and a hydrocarbon product.

Further, the said corrosion inhibitor composition also inhibits a microbial induced corrosion.

OBJECTIVES OF THE PRESENT INVENTION:

It is the primary objective of the present invention to provide a hydrocarbon fuel additive composition which acts as a corrosion inhibitor. It is further objective of the present invention to provide a corrosion inhibitor composition for inhibiting corrosion in an inert aqueous interface selected from an interface plug in a multi-product petrochemical fuel pipeline.

It is further objective of the present invention to provide a corrosion inhibitor composition which prevents emulsification between the aqueous interface and a hydrocarbon fuel product.

It is further objective of the present invention to provide a corrosion inhibitor composition which also inhibits microbial induced corrosion in a multi-product petrochemical pipeline.

DESCRIPTION OF THE INVENTION:

The present invention provides a corrosion inhibiting composition to overcome the corrosion problems of metallic surfaces, especially, the corrosion due to an inert aqueous interface in fuel pipelines such as an aqueous interface plug in a multi-product petrochemical fuel pipeline.

Accordingly, the present invention relates to a hydrocarbon fuel additive composition which acts as a corrosion inhibitor in an aqueous interface selected from an interface plug in a multi-product pipeline.

Specifically, the present invention provides a corrosion inhibitor composition containing 1- Hydroxy-Ethane-1, 1-Diphosphonic Acid (HEDP) in 70-99% by weight, Polysorbates in 1-20% by weight, and Benzalkonium chloride (BKC) in 1-10% by weight.

More specifically, the present invention provides a corrosion inhibitor composition containing 1- Hydroxy-Ethane-1, 1-Diphosphonic Acid (HEDP) in 94-97% by weight, Polysorbates in 2-5% by weight, and Benzalkonium chloride (BKC) in 0.5-3% by weight.

In another specific embodiment, the corrosion inhibitor composition contains 1 -Hydroxy-Ethane- 1, 1-Diphosphonic Acid (HEDP) in 95-96% by weight, the Polysorbates in 3-4% by weight, and the Benzalkonium chloride (BKC) in 1-2% by weight. In the present corrosion inhibitor composition, the polysorbates are selected from polysorbate 20, polysorbate 40 and a combination thereof. In another example, the polysorbates are polysorbate 20 and polysorbate 40 in a weight ratio of 1 : 1.

The corrosion inhibitor composition acts as a corrosion inhibitor additive in an aqueous interface such as but not limited to an interface plug in a multi-product petrochemical pipeline. The said interface plug consists of an aqueous medium selected from tap water, brine water, seawater, or a combination thereof. When the said corrosion inhibitor composition is added into an interface plug, the said composition prevents emulsification between the aqueous interface and a petrochemical product. Further, the said corrosion inhibitor composition inhibits a microbial induced corrosion.

The present invention provides a method for inhibiting corrosion in an aqueous interface, wherein, the method comprises adding the said corrosion inhibitor composition into the aqueous interface, wherein, the aqueous interface is an interface plug having an aqueous medium selected from tap water, brine water, seawater, or a combination thereof.

Wherein, the corrosion inhibitor composition is added in the said interface plug in a dosage range of 300 ppm to 1500 ppm. In an embodiment, the corrosion inhibitor composition dosage of 300 ppm to 600 ppm provides corrosion inhibition efficiency for tap water medium. For synthetic brine, the corrosion inhibitor composition dosage of 400 ppm to 700 ppm provides corrosion inhibition efficiency. For natural sea water, the corrosion inhibitor composition dosage of 800 ppm to 1500 ppm provides corrosion inhibition efficiency.

Further, the corrosion inhibitor composition is added in the said interface plug in a dosage range of 325 ppm to 1025 ppm.

When the interface plug consists of tap water, the corrosion inhibitor composition is added in a dosage range of 300 ppm to 525 ppm. Further, when the interface plug consists of tap water, the corrosion inhibitor composition is added in a dosage range of 325 ppm to 425 ppm. Furthermore, when the interface plug consists of brine water, the corrosion inhibitor composition is added in a dosage range of 425 ppm to 525 ppm.

Moreover, when the interface plug consists of seawater, the corrosion inhibitor composition is added in a dosage range of 525 ppm to 1025 ppm. Furthermore, when the interface plug consists of seawater, the corrosion inhibitor composition is added in a dosage range of 725 ppm to 1025 ppm.

Methodology:

The efficacy of the corrosion inhibitor composition as disclosed herein was evaluated by four different methodologies.

1. Rotating cage experiments (RC) (as per ASTM G184): It involves a standard practice for evaluating and qualifying oil field and refinery corrosion inhibitors using rotating cage.

2. Rotating cylinder electrode (RCE) (as per ASTM G185): It involves a standard practice for evaluating and qualifying oil field and refinery corrosion inhibitors using the rotating cylinder electrode.

3. Rust prevention equipment (RPE) (as per NACE TM0172): It involves determining corrosive properties of insoluble petroleum product pipeline cargoes.

4. Static tests (Internal method): It involves bottle tests to evaluate corrosiveness of the medium at stagnant locations for long durations (10-14 weeks).

Results:

Further, the efficacy of the corrosion inhibitor composition for different types of aqueous interfaces were also evaluated with varied dosages depending on the aqueous medium. Below provided the various aqueous mediums which were analyzed to determine the optimized quantity of the said corrosion inhibitor composition as required to give higher corrosion inhibition efficacy for each of the aqueous medium.

1. Tap water

2. Synthetic brine (prepared as per ASTM DI 141)

3. Natural Sea water (from Vizag area, India) The below Table 1 provides properties of the tap water used to determine the optimized quantity of the said corrosion inhibitor composition as required when the aqueous interface contains tap water. Further, the table 2 discloses various dosage and their corrosion inhibition efficiency as per the ASTM G184 (Rotating Cage Method) for the tap water.

From table 2, it can be concluded that for tap water the corrosion inhibition efficiency was 83.6% when dosage of the said corrosion inhibitor composition was 225ppm. Similarly, for tap water the corrosion inhibition efficiency was 91.3% when dosage of the said corrosion inhibitor composition was 425ppm. Further, table 3 indicates outcome of the various test results with tap water and the efficacy of the corrosion inhibitor composition when dosage of the said composition is 425ppm.

Table 1: Properties of tap water

Table 2: Corrosion inhibitor composition dosage optimization for Tap water

Table 3: Corrosion inhibition results with tap water by various methods The table 4 discloses various dosage and their corrosion inhibition efficiency as per the ASTM G184 (Rotating Cage Method) for the synthetic brine water. From table 4, it can be concluded that for synthetic brine water the corrosion inhibition efficiency was 88.9% when dosage of the said corrosion inhibitor composition is 425ppm. Similarly, for synthetic brine water the corrosion inhibition efficiency was 90.5% when dosage of the said corrosion inhibitor composition is 525ppm. The table 5 indicates outcome of the various test results with synthetic brine and the efficacy of the corrosion inhibitor composition when dosage of the said composition was 520ppm. Accordingly, the dosage of the composition optimized for synthetic brine medium was 520ppm to 525 ppm.

Table 4: Corrosion inhibitor composition dosage optimization for synthetic brine water

Table 5: Corrosion inhibition results with synthetic brine water by various methods

Further, test results were conducted with seawater and the table 6 discloses various dosage and their corrosion inhibition efficiency as per the ASTM G184 (Rotating Cage Method) for the synthetic brine water. From table 6, it can be concluded that for seawater the corrosion inhibition efficiency was 77.2% when dosage of the said corrosion inhibitor composition is 525ppm. Similarly, for seawater the corrosion inhibition efficiency was 90% when dosage of the said corrosion inhibitor composition is 1025ppm. Further, table 7 indicates outcome of the various test results with natural seawater and the efficacy of the corrosion inhibitor composition when dosage of the said composition was 1025ppm. Accordingly, the dosage of the corrosion inhibitor composition optimized for natural seawater medium was 1025 ppm. Table 6: Corrosion inhibitor composition dosage optimization for Seawater

Table 7: Corrosion inhibition results with natural sea water by various methods From the above study and the table 1-7, it was concluded that in tap water medium, the corrosion inhibition efficiency was observed to be more than 90% at corrosion inhibitor composition dosage of 420 ppm to 425 ppm. For synthetic brine and natural sea water the corrosion inhibitor composition dosage was 520 ppm to 525 ppm and 1020 ppm to 1025 ppm respectively for achieving at least 90% corrosion inhibition efficiency.

Accordingly, the corrosion inhibitor composition as disclosed herein provides higher corrosion inhibition efficacy for different types of the aqueous interfaces as used between fuel pipelines.

Further, the corrosion inhibitor composition prevents emulsification between the aqueous interface and a hydrocarbon fuel product. Further, the corrosion inhibitor composition as disclosed herein inhibits microbial induced corrosion.