EP0425853A2 - Aqueous cleaning agent for compressors, particularly gas turbines - Google Patents

Abstract

Aqueous cleaning agents for compressors, in particular for gas turbines, characterised in that they contain heteropolar compounds of alkaline cationic detergents and polymers or copolymers of organic unsaturated acids with a molecular weight of at least 500, and contain non-ionic detergents, have a metal ion content below 25 ppm and a pH between 6 and 8 at the concentration used.

Description

The invention relates to aqueous cleaning agents for compressors, in particular for gas turbines.

The use of Gaturbinen is increasing steadily and is considered to be probably the most economical and flexible way of generating energy from fuels containing carbon and hydrogen for the coming decades. In particular, the so-called "cogeneration", i.e. Generating electricity and steam together has great advantages and is considered the energy system of the future.

Gas turbines basically consist of a compressor and the gas turbine itself. They work according to the Joule cycle, i.e. with constant pressure. Air is compressed in the compressor and introduced into the combustion chamber, where the temperature is raised while the pressure remains constant. The hot gases then operate the turbine.

It is known that the compressors of such gas turbines become dirty and form deposits which impair the efficiency. Accordingly, such compressors must be cleaned continuously, be it during the standstill of the gas turbine or advantageously during operation, i.e. according to a so-called "on-line" system. This latter type of cleaning has arisen from the traditional washing of such turbines outside of their operation (unfired) at a reduced rotational speed ("off-line"). The advantage of "on-line" cleaning is that the compressor performance can be maintained or improved without the need to shut down and cool down the system. Downtimes are avoided and overall performance is improved.

Basically, this should be done more often or regularly with "on-line" cleaning. However, a complete replacement of the "off-line" washing or any dry cleaning is not intended. However, cleaning cycles According to the present invention, this aim is achieved in that the cleaning agents contain heteropolar compounds of alkaline-reactive cationic detergent substances and polymers or copolymers of organic unsaturated acids with a molecular weight of at least 500, as well as nonionic detergent substances, a metal ion content of less than 25 ppm and in Use concentration have a pH between 6 and 8.

The cationic wetting and cleaning agents can include from the group alkylamides, alkylamines, ethylene oxide addition products to alkylamines and alkylamides, and also alkylmethylene diamines, alkyltrimethylene diamine, alkyl-2-imidazolines, 2-alkyl-1- (2-aminoethyl) -2-imidazolines, 2-alkyl-1- (hydroxyethyl) - 2-Imidazolines, ethylenediamine alkoxylates and quaternary basic ammonium compounds can be selected.

The polymer acids which form heteropolar compounds with the above cation-active detergent substances preferably consist of acrylic acid and / or maleic acid or copolymers thereof. They have a molecular weight of at least 500, usually 2,000 to 5,000, although high molecular weights of e.g. 50,000 to 70,000 are possible. These polymeric acids usually have a pH of 1-2 and are characterized by high dispersing capacities of solids, e.g. 150-200 mg of calcium carbonate are dispersed in water by 1 g of such polymers.

Such polymers are advantageously also resistant to higher temperatures, for example up to ^150.degree. C., in order to be able to retain their effect fully and without the occurrence of decomposition products even at higher compressor temperatures.

The nonionic detergent substances are mainly block polymers and those from the group consisting of ethylene oxide addition products with fatty acids, aliphatic alcohols, alkylphenols, polypropylene derivatives, all of which have at least 6 carbon atoms, and optionally correspondingly less necessary, whereby the usual dry cleaners (ground shells of nuts etc., hard rice, plastics) cause an abrasion of the compressor blades and their coatings due to their abrasive properties.

Up to now, the on-line washing was mainly carried out with demineralized water (e.g. condensed water), whereby the total content of dissolved solids max. 5 ppm and on metals (Na + K + Pb + V) max. May be 0.5 ppm.

When cleaning online, it should be noted that there may be deposits on the compressor blades, which can then accumulate in the hot parts of the turbine and have adverse effects there. Depending on the respective environmental conditions, it is therefore necessary to check the use and frequency of such online washes.

With both on-line and traditional off-line washes, however, it is necessary to achieve the most complete and gentle cleaning of all deposits. The more complete the removal of these impurities, the better the efficiency of the system and the less often an abrasive dry cleaning is necessary or it becomes superfluous.

The aim of the invention is therefore to find a cleaning solution that effectively removes the deposits in the compressor, usually consisting of dirt, sand, salts, coal dust, insect corpses, oils, polymers, turbine exhaust gases. Another object is that such cleaning solutions are equally suitable for both the off-line and on-line cleaning of compressors, particularly in gas turbines. These solutions must be both combustible and biodegradable in the wastewater without pollutant formation. can be eliminated by calcium precipitation and adsorption. ethoxylated, sorbitan and sucrose esters.

A preferred feature of the heteropolar compound in combination with the nonionic detergent active substances is that they have a pH of around 6 to 8, preferably 6.5 to 7.5, in their use concentration in deionized water.

The weight ratio between the cationic and nonionic detergent substances is preferably between 20: 1 and 1:20. Although it has been shown that an excess of cationic wetting and emulsifying agents is advantageous, the above relations can be used advantageously.

The proportion of the cleaning concentrate in the cleaning agent used is between 1 and 25 percent by weight in demineralized water, advantageously between 3 and 10 percent by weight.

The polymeric organic acidic dispersants can also be used in excess or in excess, so that initially no neutral reacting cleaning solution with a pH of 6-8, advantageously 6.5 to 7.5, is formed. In such cases it is then necessary to use the excess of the acid polymers with alkaline organic agents such as e.g. Ethanolamines or when deficient with acidic organic substances, e.g. Adjust gluconic or citric acid to the aforementioned pH values.

The following examples are intended to explain the present invention in more detail:

example 1

An off-line cleaning concentrate for compressors of all kinds consists of 14 parts by weight (GT) of laurinamine, ethoxylated with 10 moles of ethylene oxide, 3.5 GT of a modified polyacrylic acid and 7 pbw of C₁₃ alcohol with 9 moles of ethylene oxide.

The modified polyacrylic acid has a molecular weight of 4,000, a pH of 1.5 and a calcium carbonate dispersing capacity of 170 mg CaCO₃ with 1 g polymer and 23 ^o C.

It is a 3.5% aqueous solution in 96.5 weight percent water with a content of max. 5 ppm dissolved solids, less than 0.5 ppm total metals (Na + K + P + V) and a pH value of 6.5 to 7.5.

In a gas turbine with 20 megawatts, this 3.5% aqueous cleaning solution is sprayed on-line for 30 minutes and with water of the above specification by means of 8 nozzles in a quantity of 2 liters per minute at a pressure of 6-7 bar (Condensed water) washed. This method was repeated daily and maintained the compressor efficiency during 40 days of operation. Without such an online wash, there was a 1.5% reduction in efficiency.

Example 2

A 10 megawatt gas turbine is washed off-line with a cleaning solution consisting of 10 pbw of quaternized fatty amine polyglocyl ether, 5 pbw of a copolymer based on maleic acid and 7 pbw of a C₁₀-C₁₈ fatty acid with 11 ethylene oxides. The cleaning solution is used in 5% concentration in water with less than 100 ppm dissolved solids, below 25 ppm Na + K content and a pH of 6 to 8.

The copolymer based on maleic acid has a molecular weight of 2,000, a pH of 2 and a calcium carbonate dispersing capacity of 210 mg CaCO₃ at 23 ^o C or 190 mg CaCO₃ at 60 ^o C per gram of active substance.

The compressor, which showed a loss in performance of 1.7% before cleaning due to contamination, was able to regain its full performance after cleaning with the 5% washing solution described and washing with demineralized water.

Example 3

In the case of a 6.5 MW gas turbine, 40,000 m³ / h of air contaminated with pollutants were also fed to it, in order to save the otherwise complex air pollution control processes.

A 7% wash-active solution in demineralized water is used offline and on-line to clean the compressor with a relatively high proportion of organic polymer impurities.

The wash-active solution consists of 15 pbw of stearylamine with 12 moles of ethylene oxide, 6 pbw of the maleic acid copolymer according to Example 2, 7 pbw of a fatty alcohol-polypropylene oxide addition product with 10 moles of ethylene oxide and 16 pbw of an ester mixture consisting of 17% by weight dimethyl adipate, 66% by weight dimethyl glutarate and 17% Dimethyl succinate.

The ester mixture has the following data: Average molecular weight about 160 Specific weight at 20 ^o C 1,090 g.cm⁻³ Refractive index 1,423 Distillation area 200-230 ^o C Vapor pressure at 20 ^oC 0.08 mbar Dynamic viscosity at 20 ^o C 3 mPa.s Evaporation at 80 ^o C 0.031 g / min Flash point 108 ^o C Autoignition point 360 ^o C Acid number (in mg KOH / g) <0.3 Atomic analysis C, H, O

This cleaning solution, in the form described above, is also good at removing organic polymeric impurities and maintaining the effectiveness of the compressor.

Example 4

15 GT each of basic reacting cationic substances, namely octadecylmethylene diamine, dodecyltrimethylene diamine, decyl-2-imidazoline, 2- (heptyl) -1- (2-hydroxyethyl) -2-imidazoline, 2-octyl-1- (2-aminoethyl) -2 Imidazoline are neutralized in aqueous solution (ad 100 pbw of condensed water) with modified polyacrylic acids (molecular weights between 800 and 70,000) (pH value of the aqueous solution min. 6.8, max. 7.2), further 5-10 pbw of octyl - And nonylphenols with 7 to 12 ethylene oxide additions added.

The cleaning concentrates obtained in this way are used in 3-15% solution in demineralized water for the on-line cleaning of compressors in gas turbines in accordance with Examples 1-3 and give good detergent action for the impurities accumulated in the compressor.

Example 5

Each 12 pbw of ethylenediamine alkoxylate with 10 moles of propylene oxide and 11 moles of ethylene oxide as well as a quaternized talc fatty amine polyglycol ether with a total of 10 attached ethylene oxide molecules are neutralized in aqueous solution (ad 100 pbw of condensed water) with maleic acid copolymers (molecular weight 1,000 to 1o,000). 5-12 parts by weight of ethoxylated (17 moles) sorbitan trioleate and sucrose esters of palm oil / stearic acid mixtures are also added.

The above cleaning concentrates are used for the off-line and on-line cleaning of compressors in 2 to 20% solution in demineralized water with good success.

Claims (8)

1. Aqueous cleaning agents for compressors, in particular for gas turbines, characterized in that they contain heteropolar compounds of alkaline-reacting cation-active detergent substances and polymers or copolymers of organic unsaturated acids with a molecular weight of at least 500, as well as non-ionic detergent substances, a metal ion content of less than 25 ppm and in the application concentration have a pH between 6 and 8. 2. Cleaning agent according to claim 1, characterized in that the cationic detergent substances from the group alkylamides, alkylamines, ethylene oxide addition products of alkylamides and alkylamines, alkylmethylene diamine, alkyltrimethylene diamine, alkyl-2-imidazolines, 2-alkyl-1- (2-hydroxyethyl) - 2-imidazolines, 2-alkyl-1- (2-aminoethyl) -2-imidazoline, ethylenediamine alkoxylates and quaternary basic ammonium compounds are selected. 3. Cleaning agent according to claim 1 or 2, characterized in that the polymers or copolymers are formed from acrylic acid and / or maleic acid. 4. Cleaning agent according to one of claims 1 to 3, characterized in that the nonionic detergent substances from the group of ethylene oxide adducts with fatty acids, aliphatic alcohols, alkylphenols, polypropylene derivatives, all of which have at least 6 carbon atoms, and optionally ethoxylated, sorbitan and sucrose esters is chosen. 5. Cleaning agent according to one of claims 1 to 4, characterized in that it further contains dimethyl esters of adipic, glutaric and succinic acids. 6. Cleaning agent according to one of claims 1 to 5, characterized in that the weight ratio between the cationic and nonionic detergent substances is between 20: 1 and 1:20. 7. Cleaning agent according to one of claims 1 to 6, characterized in that the agent is present in demineralized water in a concentration of between 1 and 25% by weight, preferably between 3 and 10% by weight. 8. Cleaning agent according to one of claims 1 to 7, characterized in that the agent has a pH between 6.5 and 7.5 when used.