Method and composition to decrease iron sulfide deposits in pipe lines

Inactive Publication Date: 2005-12-01
GREENES ENERGY GROUP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0062] The compositions of this invention can be introduced into conduits by any means, or combination of means, necessary to bring the compositions into contact with iron sulfide deposits. The compositions can be introduced continuously or intermittently, i.e., batch-wise, into operating gas or fluid pipelines, for example. Alternatively, batch introduction is effective for offline pipelines, which have been temporarily taken out of service for cleaning. Industrial procedures include pigging, which is effective for the treatment of pipelines. The compositions can even be introduced into pipelines following the conventional pigging procedure to remove residual iron sulfide. Additionally, the compositions can be used in the ongoing treatment of such pipelines to maintain low levels of iron sulfide.
[0063] While the use of any particular composition of this invention is effective in removing iron sulfide from conduits, the optimum molar ratio of phosphorus to iron for a given composition is about 5:1. The optimum molar ratio can depend somewhat upon the amine or ammonium derivative contained in t

Problems solved by technology

The corrosive nature of H2S typically leads to the accumulation of particulate iron sulfide, which can become easily entrained in hydrocarbons as well as in glycol, salts, and other contaminants, forming intractable deposits on the surfaces of conduits such as pipelines.
Such deposits present a significant problem to the oil and gas industries because the pipelines must be cleaned physically.
Additionally, the iron sulfide deposits hinder accurate determinations of pipeline structural integrity, which can be assessed by instrumentation known as SMART PIGS.
A limited repertoire of techniques has been available for reducing or removing iron sulfide deposits from pipelines.
In the case of iron (II) sulfide, however, this method results in the evolution of hydrogen sulfide, and if in sufficient amount (greater than 437 cm3/L at 0° C.) to its r

Method used

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  • Method and composition to decrease iron sulfide deposits in pipe lines
  • Method and composition to decrease iron sulfide deposits in pipe lines
  • Method and composition to decrease iron sulfide deposits in pipe lines

Examples

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Example

Composition

[0018] The compositions of this invention are particularly effective at complexing and solubilizing iron sulfide. According to one aspect of the invention, this result is readily achieved by providing one or more compounds of Formula (I) in admixture with at least one amine or ammonium derivative thereof. The anion X balances the net positive charge of one or more

phosphonium cations. Typically, n in Formula (I) is 1, 2, or 3. Thus, X is typically a monoanion, dianion, or trianion, respectively.

[0019] While any routinely accessible anion X can be used, it is preferred that X is chosen such that compounds of Formula (I) are soluble in water, alcohols, or in mixtures thereof. Thus, suitable monoanions include halides such as chloride, bromide, and iodide. Also contemplated are lower alkyl carboxylates, wherein the term “lower alkyl” refers to a straight or branched C1-C6 alkyl group. Exemplary lower alkyl carboxylates are methyl carboxylate (i.e., acetate), ethyl carbo...

Example

EXAMPLE 1

Composition Generated from Tetrakis(hydroxymethyl)phosphonium sulfate (THPS) and Ammonium Chloride

[0065] A. Tetrakis(hydroxymethyl)phosphonium sulfate (THPS) is obtained commercially as a 75-90 weight % aqueous solution with pH that varies below 4. The following procedure yielded 1000 g of a 5% aqueous composition able to complex iron sulfide. 66.6 grams of 75 weight % THPS (in water) and 0.5 grams ammonium chloride were combined, diluted with 90 grams of water, and then mixed. A sufficient amount of a 30% weight aqueous solution of sodium or potassium hydroxide was added to raise the pH to about 6.5. The total weight of the product was brought to 1000 grams by adding water, whereupon the pH was remeasured. After dilution, pH can be readjusted slightly, if necessary, to the desired value.

[0066] In this example, water can be replaced with methanol in varying amounts to produce solutions with as little as 0% water and as much as 95% water, depending upon the overall relati...

Example

EXAMPLE 2

Composition Generated from Tetrakis(hydroxymethyl)phosphonium sulfate (THPS) and Methylamine

[0068] Following the procedure in Example 1, a 5% by weight composition was prepared by 1) combining 6.66 g of tetrakis(hydroxymethyl)phosphonium sulfate in the form of its 75% aqueous solution by weight with enough water to make 90 mL of solution, 2) adding concentrated (12M aqueous KOH) caustic to form TRIS (95% conversion) at a pH of 7.7, 3) diluting with water to 100 mL, 4) adding 0.263 grams of methylamine, and 5) mixing. The mole ratio of TRIS to amine in this mixture is 2.6:1.

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Abstract

The levels of iron sulfide present in a conduit, such as a pipeline, are reduced by contacting the conduit, on an inner surface, with a composition obtained from an aqueous solution containing at least one compound of Formula (I)
and at least one amine or corresponding ammonium derivative in the presence of a solvent, wherein X is an anion of valency n. Preferably, the pH of the solution is about 8. Alternatively, the method employs a composition comprising tris(hydroxymethyl)phosphine (TRIS) and at least one amine or corresponding ammonium derivative. The amine preferably is ammonia or a primary alkylamine. The compositions readily complex and thereby dissolve deposits of iron(II) sulfide, removing them from the conduit.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS [0001] This application claims benefit of priority to U.S. provisional applications Ser. No. 60 / 373,381, filed Apr. 17, 2002, and No. 60 / 312,647, filed Aug. 15, 2001.BACKGROUND OF THE INVENTION [0002] This invention relates to methods and compositions to decrease or remove iron sulfide deposits in or on a conduit of a gas stream. [0003] Hydrogen sulfide (H2S) is a pernicious, naturally occurring contaminant of fluids that is encountered, for example, during the manipulation of oil or gas. The corrosive nature of H2S typically leads to the accumulation of particulate iron sulfide, which can become easily entrained in hydrocarbons as well as in glycol, salts, and other contaminants, forming intractable deposits on the surfaces of conduits such as pipelines. Such deposits present a significant problem to the oil and gas industries because the pipelines must be cleaned physically. Additionally, the iron sulfide deposits hinder accurate dete...

Claims

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Application Information

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IPC IPC(8): C09K3/00B08B9/02C09K8/528C09K13/00C09K13/02C10G75/04C11D7/06C11D7/36C11D11/00C23F11/167C23F14/02C23G1/24F16L58/10
CPCB08B9/032C09K8/528C09K2208/20C10G75/04C11D7/06C11D7/36Y10S210/912C23F14/02C23G1/18C23G1/24C23G1/26F16L58/1009C11D11/0041Y10T137/0391
Inventor MATTOX, MARK ANDREWVALENTE, EDWARD J.
Owner GREENES ENERGY GROUP
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