Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
2000-11-30
2001-10-30
Gupta, Yogendra N. (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C134S002000, C134S003000, C252S175000, C510S245000, C510S254000, C510S401000, C510S477000, C510S506000
Reexamination Certificate
active
06310022
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a chemical cleaning solution for gas turbine blades. In particular, the present invention relates to a cleaning composition comprising a hydroxylated wetting agent, a chelating agent, an emulsifier, an optional crown ether, and an optional non-aromatic solvent.
2. Description of the Prior Art
Industrial gas turbine engines are used worldwide. An example of a gas turbine is a Mars Gas Turbine or a Taurus 70 Gas Turbine, manufactured by Solar Turbines, Inc. A Mars turbine has a 15 stage compressor and each stage is comprised of a stationary row of blades (stator blades) and a rotating row of blades. The blades are the largest at stage 1 and the smallest at stage 15. During operation, air is drawn into the compressor's divergent passage and compressed through every stage.
The stator blades direct the compressed air at each stage across its companion row of rotating blades. The air foil of the stator and rotating blades have been designed for maximum efficiency. However, as a result of continuous operation, contaminants build up on the leading edge of these air foils. Consequently, overall efficiency is lost in the compressor section. This in turn reduces the horsepower available for consumer use. The Mars turbine engine compresses approximately 90 pounds per second of air at full rated horsepower. There is only a small amount of airborne contaminants per standard cubic foot of air. However, with the massive amounts of air passing through the turbine these contaminants are multiplied. Moreover, the air enters the turbine at room temperature and leaves the compressor at approximately 630° F. Most of the lost efficiency is across the first three or four stages and it is very difficult to clean the blades once the contaminants have adhered to them.
Accordingly, gas turbines must be cleaned, usually monthly, to maintain operating efficiency and maximum available horsepower. There exists two main ways to clean a gas turbine. One of these is crank washing and the other is on-line washing. Crank washing is the more common of the two. During cleaning, each turbine uses about 2 gallons of cleaner to clean the turbine and an additional 1-2 gallons to clean the package. The same cleaner may also be used for general cleaning purposes in the operating plant. Accordingly, there exists a large need for a superior gas turbine cleaner.
Gas turbine crank washing is a method whereby a cleaning solution is introduced into the turbine compressor inlet of a turbine while slow cranking. This slow cranking occurs cold without ignition or fuel being introduced. There are many types of turbine compressor cleaners on the market. These include Penetone® 19, by Penetone Corporation; Connect® 5000, by Conntect, Inc.; Turco® 6783 Series, by Turco Products, Inc.; ZOK® 27, by ZOK Incorporated; and Fyrewash®, by Rochem Corporation.
However, current cleaning products have several disadvantages. These disadvantages include excessive foaming, extended soaking periods, low water solubility, residual cleaner, failure to remove adhered particles of less than 35 micrometers, and the absence of a 100% biodegradable. Current products cure some of these disadvantages; however, none have been able to cure all of these properties. Of importance in view of current trends of environmental safety is a product that is 100% biodegradable. Current products are biodegradable but none are 100% biodegradable. Moreover, current water-based products are not capable of removing adhered particles having a particle size of less than 35 micrometers. These types of particles cannot be removed unless some type of solvent-based chemical is used. Thus, there is no cleaning solution which is water-based and can remove particles less than 35 micrometers.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a gas turbine cleaner which cures all of the above disadvantages including being 100% biodegradable, water-based, and able to remove adhered particles having a particle size of less than 35 micrometers.
In one embodiment, the present invention relates to a composition comprising a hydroxylated wetting agent, a chelating agent, an emulsifier, and a crown ether. In an embodiment of the present invention, the present composition comprises (1) about 10% to about 60%, preferably about 30% to about 50%, more preferably about 38% to about 42% by weight of the hydroxylated wetting agent, (2) about 20% to about 40%, preferably about 25% to about 35%, more preferably about 29% to about 31% by weight of the chelating agent, (3) about 1% to about 45%, preferably about 15% to about 35%, more preferably about 20% to about 30% by weight of the emulsifier, and (4) about 0.01% to about 2%, preferably about 0.05% to about 1.25%, more preferably about 0.5% to about 1% by weight of the crown ether. Each of these % by weight values are based on the total weight of the composition.
In another embodiment of the present invention, the present composition comprises a hydroxylated wetting agent, a chelating agent, and an emulsifier. A crown ether is absent from this embodiment of the present invention.
In another embodiment, the present composition comprises a hydroxylated wetting agent, a chelating agent, an emulsifier, a crown ether, and a non-aromatic solvent. In this embodiment the present composition comprises (1) about 10% to about 60%, preferably about 30% to about 50%, more preferably about 38% to about 42% by weight of the hydroxylated wetting agent, (2) about 1% to about 30%, preferably about 15% to about 25%, more preferably about 19% to about 21% by weight of the chelating agent, (3) about 1% to about 45%, preferably about 15% to about 35%, more preferably about 20% to about 30% by weight of the emulsifier, (4) about 0.01% to about 2%, preferably about 0.05% to about 1.25%, more preferably about 0.5% to about 1% by weight of the crown ether, and (5) about 1% to about 20%, preferably about 5% to about 15%, more preferably about 9% to about 11% of the non-aromatic solvent. Each of these % by weight values are based on the total weight of the composition.
In yet another embodiment, the present composition comprises a hydroxylated wetting agent, a chelating agent, an emulsifier, and a non-aromatic solvent. A crown ether is absent from this embodiment of the present invention.
In one embodiment, the hydroxylated wetting agent of the present invention is a hydroxylated hydrocarbon containing 2 to 6 carbon atoms and 2 to 4 hydroxyl groups. In particular, the ratio of the carbon atoms to the hydroxyl groups is between 1.0 and 0.75. In a preferred embodiment, the hydroxylated wetting agent is one or more of polypropyleneglycol, polyethyleneglycol, glycerine, ethylene glycol, or propylene glycol.
In another embodiment, the chelating agent is EDTA and the emulsifier is a non-ionic surfactant.
In an embodiment of the present invention, the crown ether is a C
8
-C
30
crown ether, preferably a C
10
-C
20
crown ether, and more preferably a C
13
-C
19
crown ether.
In yet another embodiment, the non-aromatic solvent is a linear or non-linear alcohol having 1 to 6 carbons and from 1 to 5 ethoxylations; a mono-, di-, or tri-ester of mono-, di-, or tri-carboxylic acid; or a mono-, di-, or tri-alkyl ester. Specific examples include methyl ester, ethyl ester, ethyl acetate, methyl laurate, dimethyl citric acid, ethyl propionate, lauryl acetate, methyl glutamate, diethoxy-2-ethyl propyl alcohol, diethoxy pentyl alcohol, triethoxy pentyl alcohol, and diethoxylated isobutyl alcohol. In a preferred embodiment, the non-aromatic solvent is an ethoxylated non-linear alcohol such as di-ethoxylated isobutyl alcohol, C
8
H
19
O
2
, or an organic ester such as methyl laurate.
The present composition may also optionally contain a water-soluble organic solvent and a non-silicon based anti-foam agent. The water-soluble organic solvent may be isopropanol and the anti-foam agent may be an ethoxylated linear alcohol. The present invention further provides for a process for cleanin
BioGenesis Enterprises, Inc.
Birch & Stewart Kolasch & Birch, LLP
Gupta Yogendra N.
Webb Gregory E.
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