Coating processes – Spraying
Reexamination Certificate
2002-11-01
2004-09-28
Pianalto, Bernard (Department: 1762)
Coating processes
Spraying
C106S002000, C106S014500, C106S311000, C252S363500, C516S156000, C516S157000, C516S160000, C516S162000, C516S163000, C516SDIG001, C516SDIG002, C516SDIG005, C516SDIG007
Reexamination Certificate
active
06797329
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an antifoulant dispersant. The present invention particularly relates to antifoulant dispersants for use with centrifugal compressors used for compression in an ethylene process.
2. Background of the Art
Fouling of compressors is a well-known problem in processes using them. The fouling of compressors can cause damage to the compressors as well as plant down time, both potentially very expensive problems. There has been considerable effort spent by industry to prevent such fouling. For example, U.S. Pat. No. 6,159,547 to McMordie, et al., discloses a method for coating turbomachinery having a metal surface to prevent fouling. The steps of the method are applying to the surface a first slurry containing an acidic aqueous medium containing a galvanically active material and phosphate ions, thereby forming a galvanically sacrificial first layer, curing the first layer, applying to the cured first layer an aqueous non-conductive second slurry containing inorganic phosphate or silicate ions, thereby forming a non-conductive second layer, curing the second layer, applying to the cured second layer a liquid sealer composition containing a thermally stable organic polymer and fluorocarbon, thereby forming a top layer, and curing the top layer.
In some processes, the operating conditions under which the compressors are laboring can foul or even erode compressor blades, no matter how well coated the compressor blades may be. For example, U.S. Pat. No. 5,849,983 to Khatib discloses addition of polyisobutylene to a predominantly gaseous stream for preventing the shearing of hydrocarbon droplets in the stream to aerosol sizes. One advantage of this invention is that when the polyisobutylene is sprayed upstream of compressor stations, it functions to prevent fouling and erosion of the compressor blades.
While a polymer can function to prevent fouling, as is disclosed in U.S. Pat. No. 5,849,983 to Khatib, in some processes, it is the formation of polymers that can cause fouling. For example, in an ethylene process, it is the formation of organic polymers that can cause compressor fouling.
Steam cracking of hydrocarbons accounts for virtually all of the ethylene produced worldwide. Hydrocarbons used as ethylene feedstocks range from natural gas liquids including ethane, propane and butane, to petroleum liquids including gas oils and naphtha. In the process of producing ethylene, as the ethylene is produced and purified, small amounts of polymers can form. These polymers are generally considered contaminants and are undesirable in the product ethylene. One point of isolation of such contaminants is the compressors. Due to pressure changes, the contaminants can be isolated as liquids and sent to knockout pots wherein the contaminants are held until sent for recycle or disposal.
SUMMARY OF THE INVENTION
In one aspect, the present invention is a dispersant prepared from a formulation comprising: (a) the reaction product of a polyalkyl polyamine, an alkylphenol and an aldehyde; and (b) a polyalkyl acrylate polymer; wherein the two components are present in a weight ratio of about 2:1.
In another aspect, the present invention is a process for preventing fouling of compressor blades used to compress gasses comprising depositing a dispersant onto blades of a compressor to be protected from fouling, the dispersant being prepared from a formulation comprising: (a) the reaction product a polyalkyl polyamine, an alkylphenol and an aldehyde; and (b) a polyalkyl acrylate polymer; wherein the two components are present in a weight ratio of about 2:1.
It would be desirable in the art of compressing gasses to prevent fouling of compressor blades. It would be particularly desirable in the art of compressing ethylene to prevent fouling of compressor blades while avoiding creating an emulsion in knockout pots.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In one aspect, the present invention is a process for preventing fouling of compressor blades used to compress gasses. The dispersants of the present invention function to prevent fouling in compressors by forming a film on the surface of the compressor blades that prevents, or at least mitigates, buildup by polymers and other contaminants in the gasses being compressed.
In the practice of the process of the present invention, the dispersants can be applied to compressor blades in any way known to those of ordinary skill in the art of applying such materials to be useful for preventing fouling. Preferably, the dispersants are sprayed onto the compressor blades in the form of an aerosol. More preferably, the dispersants are injected into the gas stream being compressed, upstream of the compressor, as an aerosol that is then carried to the compressor blades by the gas being compressed.
In another aspect, the present invention is a dispersant prepared from a formulation having at least two components. The first component of the dispersant, hereinafter Component A, is the reaction product of a polyalkyl polyamine, an alkylphenol and an aldehyde. The polyalkyl polyamines useful with the present invention have a general formula:
wherein n is an integer of from 0 to 5. Exemplary amines include, but are not limited to ethylene diamines and tetraethylenepentamine, but any compound having the general formula I can be used to prepare Component A of the present invention.
The alkylphenols useful to prepare the Component A of the present invention have the general formula:
wherein R is an alkyl group having from 1 to 120 carbons. Exemplary alkylphenols that can be used to prepare Component A of the present invention include but are not limited to anisole, polybutylphenol and nonylphenol, but any alkylphenol having the above general formula can be used.
The aldehydes useful for preparing the first component of the present invention have the general formula:
wherein R is H or an alkyl group having from 1 to 6 carbons. Preferably the aldehyde is formaldehyde.
Component A is the reaction product of a polyalkyl polyamine, an alkylphenol and an aldehyde. Component A is preferable a Mannich condensation product formed by condensing the alkylphenol of Formula II with an aldehyde of Formula III and a polyalkyl polyamine of Formula I. The condensation reaction may be conducted at a temperature in the range of about 40° C. to about 200° C. The reaction can be conducted in bulk (no diluent or solvent) or in a solvent or diluent. Water is evolved and can be removed by azeotropic distillation during the course of the reaction. The aldehyde is typically present in a molar amount at least equal to the total molar amount of the amine compounds present. Component A can be prepared by any method known to those of ordinary skill in the art of preparing such reaction products to be useful.
Any ratio of alkylphenol to aldehyde to polyalkyl polyamine that will form a stable reaction product can be used to prepare Component A of the present invention. Preferably, the weight ratio of alkylphenol to aldehyde is from 0.1:1 to 60:1. Preferably the weight ratio of aldehyde to polyalkyl polyamine is from 1:1 to 6:1.
The second component of the dispersant of the present invention is a polyalkyl acrylate polymer. For the purposes of the present invention, the term “acrylate polymers” include polymers having repeating acrylate units, methacrylate units and mixtures thereof. The polymer is preferably a copolymer. These copolymers are typically prepared by first preparing an ester of acrylic acid or methacrylic acid and a C
1
-C
10
alcohol and then reacting the ester with a N-vinyl pyrrolidinone or vinylpyridine. For example, VISCOPLEX® 6-917, available from RohMax, is a polyalkyl methacrylate copolymer which can be used as Component B of the present invention.
While copolymers are a preferred embodiment, polyalkyl acrylate polymers are also useful as component B. For example, poly (isodecyl methacrylate) can be used as component B of the present invention. Other polymers having utility as Component B of the present invent
Baker Hughes Incorporated
Madan Mossman & Sriram P.C.
Pianalto Bernard
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