DE102013003467A1 - Liquid cleaning agent useful for chemical cleaning of plant parts in refineries and petrochemical plants comprises organic solvents, and surfactants and/or dispersants - Google Patents

Abstract

Liquid cleaning agent comprises 70-99.9 wt.% organic solvents except 1-3 alcohol, and 0.5-30 wt.% surfactants and/or 0.1-30 wt.% dispersants. An independent claim is also included for chemical cleaning of plant parts in refineries and petrochemical plants, comprising providing the liquid cleaning agent, circulating the cleaning agent in the plant parts and removing the cleaning agent from the plant parts.

Description

The present invention relates to a cleaning agent and a method for cleaning oil refining equipment such as heat exchangers in refineries.

• • Verminderung des Durchflusses
• • Druckverlust
• • Verminderung des Wärmeübergangs und hierdurch Energieverlust.

Refineries and petrochemical plants for petroleum processing often deposit on plant surfaces, which is also called fouling. Affected plant components are z. As heat exchangers, columns, containers, pipelines and filters. Deposits are always undesirable as they have a number of negative effects on the production processes, including:

• • reduction of flow
• • pressure loss
• • Reduction of heat transfer and thus energy loss.

• • anorganische Salze wie Erdalkalicarbonate, -phosphate, -sulfate und -silikate
• • Sand, Schlamm, Sedimente
• • Korrosionsprodukte wie Eisenoxide, Hydroxidoxide, Eisensulfide
• • hochmolekulare organische Komponenten wie Alkane, Paraffine, polyzyklische Verbindungen, Asphaltene und Heterozyklen
• • Koks.

The deposits can consist of different substances of inorganic and organic nature. These include, among others:

• • inorganic salts such as alkaline earth carbonates, phosphates, sulfates and silicates
• • sand, mud, sediments
• • Corrosion products such as iron oxides, hydroxide oxides, iron sulfides
• • high molecular weight organic compounds such as alkanes, paraffins, polycyclic compounds, asphaltenes and heterocycles
• • coke.

Typically, the deposits in technical plants for petroleum processing consist of complex mixtures of both organic and inorganic nature. If predominantly organic deposits are subjected to a high degree of thermal stress over an extended period of time, they dehydrate into a hard, coke-like mass which is virtually impossible to remove by means of chemical cleaning measures. Rather, the affected system components must be disassembled and mechanically cleaned.

Deposits can severely disrupt production processes, including unplanned plant shutdowns. Types of heat exchangers Plate heat exchangers and shell and tube heat exchangers are particularly affected by deposits, as the flow rates of the media are sometimes quite low in these parts of the system. Particularly affected are the hot preheating trains in crude oil distillation plants. This is a series of series-connected heat exchangers, in which the crude oil is heated from about 150 ° C to the oven inlet temperature of about 250 ° C. As a heating medium typically serve lower side streams of distillation columns such as vacuum gas oil and bottom streams, z. B. vacuum residue. These are "heavy", d. H. high-boiling, mixtures that are characterized by a high density, high viscosity and a high proportion of asphaltenes, metals and other critical constituents. Therefore, they are highly prone to fouling of the heat exchanger surfaces, particularly when passed over the shell side of shell and tube heat exchangers on which the flow velocities are lower than on the tube side. Fouling in the preheaters leads to a gradual loss of heat transfer, which requires more heating medium such as natural gas or heavy oil to be burned in the downstream furnace to heat the crude oil to the distillation temperature of about 350 ° C. This deteriorates the energy balance of the entire distillation plant. Therefore, the affected heat exchangers are cleaned at regular intervals, which is a time consuming and costly procedure.

Two methods are available for cleaning the affected parts of the plant: mechanical cleaning on the one hand and dry cleaning on the other.

In mechanical cleaning, the affected parts of the system are disassembled, cleaned by machine or manually by applying high shear forces or other mechanical forces and then reassembled. This cleaning method is very thorough, but also very laborious and time consuming. For shell-and-tube heat exchangers, this method requires capturing the exchangers from the production process, removing the tube bundles from the shell, cleaning them, then reinstalling them, and reconnecting to the process. Mechanical methods also include the widespread cleaning of heat exchangers by means of high-pressure water jet technology at specially designed "washing places".

A modification of the mechanical cleaning is the Pigchen (English "pigging"). In this method, which is only applicable to pipelines of a certain diameter, a cleaning device, which z. As scrapers or brushes, performed in the pipes to be cleaned and drives them remotely controlled if necessary. The tubes of tube bundle heat exchangers can also be cleaned by means of special cleaning projectiles, which are shot through the tubes by means of compressed air. Of course, this is only possible with straight tube bundles, ie not with so-called U-bend tubes, and generally not on the shell side. Among the mechanical cleaning methods is cleaning with CO ₂ snow or CO ₂ pellets, which can be used for special tasks.

Due to the high workload, the mechanical cleaning, for example, heat exchangers from hot preheating trains is preferably carried out during plant downtime, but which may be several years apart. Thus, mechanical cleaning can not always be used for currently necessary measures.

Compared to mechanical cleaning processes, dry cleaning offers a number of advantages. So the component to be cleaned does not have to be disassembled, which saves a considerable amount of work. In addition, hard to reach parts of the system are also recorded by the cleaning. The cleaning medium can be adapted in composition and concentration to the respective task. In practice, dry cleaning is achieved by the "cleaning in place" (CIP) process. Here, a cleaning medium is circulated from a tank by means of a pump and fixed or flexible lines in the system to be cleaned until the desired cleaning performance has been achieved. The cleaning medium may be replaced several times, depending on the degree of contamination of the system. Typically, one works at elevated temperature, about 40-100 ° C and selects the recirculation rate so that the entire volume of the system parts to be cleaned is circulated several times within one hour. Such cleaning takes about 2-10 hours. Before and after the main cleaning, separate process steps z. B. with steam ("steam out") are performed. This serves, inter alia, to remove volatile components before the main cleaning.

The cleaning medium may be aqueous or organic, depending on the nature of the deposits. In aqueous cleaning solutions, cleaning products are added to the water, which typically consist of surfactants, complexing agents, acids or bases and optionally other additives such as corrosion inhibitors. Partial enzyme cleaners are also used.

If protic acids such as mineral acids (for example hydrochloric acid or sulfuric acid) or organic acids such as acetic acid are used in aqueous cleaning liquids, this is referred to as pickling. Pickling processes are widely used to remove acid soluble deposits such as carbonates and usually require the addition of a corrosion inhibitor to minimize corrosion on the equipment itself. This is called inhibited acids. Pickling processes are basically critical because of the associated risk of corrosion. If the cleaning agent is not optimally matched to the metallurgy to be cleaned, considerable corrosion damage is possible. The cleaning power of aqueous cleaning media against high-viscosity, tarry deposits, which occur for example in heat exchangers of oil processing plants, is also limited.

As organic cleaning agents solvents such as gasoline, kerosene, aromatic mixtures or certain petroleum fractions are used. These are usually non-corrosive and have better organic solvent solubility. Frequently, material streams from the refinery itself, such as directly distilled heavy gasoline, gas oil or kerosene are used as organic cleaning agents. Although these cleaning media are economically favorable for the operators, they have only a limited effect against stubborn, tarry deposits.

Mamedov et al. "Selection of solvents for the chemical cleaning of heat exchangers used for processing petroleum in the fields"; Izvestiya Vysshikh Uchebnykh Zavedenii, Neft i Gaz (1978), 21 (1), 55-8 , Describe method for the chemical purification of heat exchangers, being first pre-cleaned with organic solvents such as gasoline, kerosene or diesel and then pickled with inhibited hydrochloric acid. This also describes additives that - added in the percentage range - to enhance the cleaning effect. In the case of these classic pickling processes, there is a considerable risk of corrosion due to the strong mineral acid used, despite the inhibition.

CN 102242028 describes neutral, aqueous cleaner solutions for use in gas-gas heaters.

KR 20110077208 describes a complex mixture of amines, nonionic surfactants and alcohols in an aqueous cleaning medium.

US 2004/0102351 and US 2005/0211274 describe a method of cleaning heat exchangers using steam as a cleaning medium. To the vapor is added a mixture of terpenes and nonionic surfactants.

However, the process is expensive and terpenes are expensive as active ingredients.

In general, water-based chemical processes have the disadvantage that a polluted aqueous solution is formed, which must be fed to a regulated disposal, eg. B. in an in-house wastewater treatment plant. When polluted solutions are introduced into sewage treatment plants, the type and concentration of pollutants must be carefully controlled to avoid damaging the biological stages.

• • sehr gute Reinigungswirkung gegen hauptsächlich organische Ablagerungen in Raffinerie- und petrochemischen Anlagen, insbesondere auch gegen polymerisierte und kondensierte organische Verbindungen mit teerartiger und pastöser Konsistenz
• • einfach und sicher anzuwenden
• • thermisch und chemisch stabil
• • ökonomisch für den Betreiber der Anlagen
• • in betriebsinternen Prozessen zu entsorgen.

It is an object of the present invention to provide a cleaning agent and a process for purification which have at least one, preferably more and in particular all of the following properties:

• • Very good cleaning action against mainly organic deposits in refinery and petrochemical plants, in particular against polymerized and condensed organic compounds with a tarry and pasty consistency
• • easy and safe to use
• • thermally and chemically stable
• • economical for the operator of the plants
• • Dispose of in-house processes.

Furthermore, there was the task of analytically monitoring the cleaning performance by means of a simple method in order to determine optimal times for changing the cleaning solution and the duration of the cleaning steps.

The object was surprisingly achieved by a liquid detergent containing 70 to 99.9% by weight of organic solvent, with the exception of C1-C3-alcohols, and 0.5 to 30% by weight of surfactants and / or 0.1-30% by weight. % Dispersants are dissolved. The object is further achieved by a process for the purification of technical equipment in which a liquid detergent containing 70 to 99.9 wt .-% organic solvent, except C1-C3 alcohols, and 0.5 to 30 wt .-% surfactants and / or 0.1-30 wt .-% dispersants is circulated in a part of the system to be cleaned.

To optimize the cleaning effect, the cleaning agent contains 0.5-30% by weight of surfactants and 0.1-30% by weight of dispersants. In addition, it is advantageous if the circulating detergent contains up to 10 wt .-% water.

• • schweres, direkt destilliertes Benzin („heavy straight run naphtha”, HSRN)
• • mittelschwere bis schwere Seitenströme aus der atmosphärischen Destillation wie Kerosin und Gasöl
• • rohe Aromatenschnitte wie Roh-BTX (Benzol, Toluol, Xylol, Ethylbenzol)
• • schwere Aromatenschnitte wie schweres aromatisches Naphtha.

The function of the solvent is to serve as a basic dissolution medium and to provide some capacity for the uptake of organic matter. The organic solvents used are preferably unrefined material streams from the refineries and petrochemical plants themselves. They may be mainly paraffinic, naphthenic and aromatic mixtures, for example:

• • Heavy, straight-distilled gasoline (HSRN)
• • medium to heavy sidestreams from atmospheric distillation such as kerosene and gas oil
• • crude aromatic cuts such as crude BTX (benzene, toluene, xylene, ethylbenzene)
• • heavy aromatic cuts like heavy aromatic naphtha.

Preferably, heavy gas oil having a boiling range of about 250-350 ° C or heavy aromatic mixtures having an initial boiling point of at least 150 ° C are used. These non-polar (gas oil) to medium-polar (aromatic) solvents are characterized by a better solubility of typical deposits such as teeartigen substances compared to polar solvents such as C1-C3 alcohols. C1-C3 alcohols are also unsafe to use because of their low boiling points and coupled very low flash points. For safety reasons, it is advantageous to use a high-boiling solvent, so that the flash point of the cleaning agent is at least 20 ° C above the cleaning temperature.

At least 80% by weight, in particular at least 90% by weight and very particularly preferably at least 95% by weight, of solvent are preferably used. The content of organic solvent is preferably at most 99 wt .-%, particularly preferably at most 98 wt .-% and in particular at most 97 wt .-%.

• • aliphatische Glykolether wie Polyethylenglykol (PEG), Polypropylenglykol (PPG) sowie deren endgruppenverschlossene Ether und Ester
• • lineare oder verzweigte Succinsäurederivate sowie
• • Mischungen hiervon.

In addition, the organic solvent may include other components, including:

• Aliphatic glycol ethers such as polyethylene glycol (PEG), polypropylene glycol (PPG) and their end-capped ethers and esters
• • linear or branched succinic acid derivatives as well
• • mixtures thereof.

The function of the surfactants is to provide surface activity and attack and soften deposits. Surfactants are, for. For example, according to Rompp Online, Version 3.29, amphiphilic (bifunctional) compounds having at least one hydrophobic and one hydrophilic moiety. The hydrophobic residue is usually a - possibly linear - hydrocarbon chain with 8 to 22 carbon atoms. Special surfactants also have (dimethyl) siloxane chains (silicon surfactants) or perfluorinated hydrocarbon chains (fluorosurfactants) as the hydrophobic moiety. The hydrophilic moiety is either a negatively or positively electrically charged (hydratable) or a neutral polar head group. Surfactant betaines or amino acid surfactants (amphoteric or zwitterionic surfactants) carry negatively and positively charged groups in a molecule. Basic properties of the surfactants are the oriented adsorption at interfaces and the aggregation to micelles and the formation of lyotropic phases.

As a surfactant, both individual surfactants, as well as mixtures can be used. Nonionic and / or anionic surfactants are preferably used, particularly preferably anionic surfactants.

The proportion of surfactants in the cleaning agent is preferably from 0.5 to 30 wt .-%. Preferably, at least 1 wt .-%, in particular at least 3 wt .-% surfactant is used. The maximum content is preferably 15 wt .-%, particularly preferably 10 wt .-% and in particular 5 wt .-%.

• • Alkylsulfate und Alkylethersulfate
• • mittel- bis langkettige Carbonsäuren und deren Salze
• • organische Sulfonsäuren sowie deren Salze.

Suitable anionic surfactants are, for example

• • alkyl sulfates and alkyl ether sulfates
• • medium to long-chain carboxylic acids and their salts
• • organic sulfonic acids and their salts.

As anionic surfactants, organic sulfonic acids are particularly well suited. As organic sulfonic acids, both linear and branched alkylbenzenesulfonic acids (ABS) can be used. The alkyl chain may have a distribution in the range C ₈ -C ₁₈ . Preference is given to n-alkylbenzenesulfonic acids, which have their distribution center of gravity in the range between C ₁₀ and C ₁₃ . However, it is also possible to use single or multiple branched, saturated or unsaturated and also widely distributed alkylbenzenesulfonic acids. Fully saturated (non-aromatic) alkyl sulfonic acids can also be used. A particular advantage of organic sulfonic acids is that in combination with emulsified water they dissolve inorganic, acid-soluble constituents of the deposits, such as carbonates and corrosion products.

• • Fettalkoholalkoxylate
• • Fettaminalkoxylate
• • Alkylphenolalkoxylate
• • Copolymere von Ethylenoxid und Propylenoxid (EO/PO Copolymere).

As nonionic surfactants, it is possible to use all compounds which have at least one C ₆ -C ₁₈ -alkyl chain (saturated or unsaturated), at least one heteroatom, such as nitrogen (N) or oxygen (O), and several units of ethylene oxide (EO) or propylene oxide (PO ) feature. Suitable z. B .:

• • fatty alcohol alkoxylates
• • fatty amine alkoxylates
• • Alkylphenol alkoxylates
• Copolymers of ethylene oxide and propylene oxide (EO / PO copolymers).

For example, fatty alcohol ethoxylates, fatty amine ethoxylates or alkylphenol ethoxylates having degrees of ethoxylation between 3 and 30 can be used. Instead of EO, the molecules may also contain PO and / or combinations of EO and PO. Suitable EO / PO copolymers are both those with EO-PO-EO basic structure, as well as those with PO-EO-PO (inverse) basic structure. The nonionic surfactants used can be open (end groups = free OH groups) or end group-capped (end groups = ethers or esters). Preferred nonionic surfactants are fatty amine ethoxylates with alkyl chains between C ₈ and C ₁₆ and degrees of ethoxylation between 3 and 20.

The function of the dispersant is to attack and disperse asphaltenes and other organic particles in the deposits and to keep them suspended in the detergent. Dispersants, also referred to as dispersing aids, are, for. B. after Rompp Online, Version 3.29, surface-active Substances which allow the dispersion of a powdery substance, eg. As a pigment or a filler, facilitate in a liquid dispersion medium by lowering the interfacial tension between the two components. Thus, they protect the primary particles by complete wetting and formation of a protective colloid sheath or electrochemical (Helmholtz or star) bilayer against reagglomeration or flocculation.

Polyisobutylene succinimides (PIBSI), polyisobutylene succinic acid esters (PIBSE) or polyisobutylene amines (PIBA) can be used as dispersants. Other polar modified polyisobutylene derivatives are also usable. Both individual compounds and mixtures can be used. The proportion of dispersants in the cleaning agent is from 0.1 to 20 wt .-%, preferably from 0.5 to 10 wt .-%, particularly preferably from 0.5 to 3 wt .-%.

Water can occur in the detergent both as process-related residual amount, as well as be added specifically. Process-related residual quantities occur in the affected plant components z. For example, after "steam out" process steps. The water is finely dispersed and emulsified in the organic solvent due to the typically high forced flow rates used. The presence of water in the cleaning agent is not mandatory, but may be beneficial if acid soluble components such as carbonates and corrosion products are contained in the deposits.

When alkylsulfonic acid is used as the surfactant, a low pH is produced in the emulsified water, whereby the water dissolves acid-soluble constituents even better and these are absorbed in the cleaning medium.

However, the proportion of water in the cleaning medium must not be too high, since otherwise a free water phase may form in parts of the plant, which has a corrosive effect. Therefore, the proportion of water in the range of 0 to 10 wt .-%, preferably from 0 to 5 wt .-%, more preferably below 1 wt .-%.

In a preferred embodiment, water in the system is allowed to leak freely before the main cleaning. The remaining amount of water is then emulsified in the circulation of the detergent in this. Usually results in this approach, a water content in the preferred range.

If the plant itself is practically anhydrous before the beginning of the cleaning, water can also be added to the cleaning agent in a targeted manner in order to achieve a dissolving effect against acid-soluble constituents of the deposit with the aid of the organic sulfonic acid preferably used as surfactant.

The detergent according to the invention is used according to established standard procedures for chemical cleaning in refineries and petrochemical plants. The following is a brief description of a standard procedure. There are many variations possible.

The plant components to be cleaned are sealed off from the production process, emptied of organic media and possibly pre-cleaned by steam out or other process steps. The liquid cleaning agent is in a suitable container, such as a stainless steel tank or a plastic IBC, set and circulated by means of a strong circulation pump in the polluted parts of the system. Here, the temperature is typically increased to 40-60 ° C, for example with a small heat exchanger, which can be heated with low-pressure steam from the plant itself. The circulation is continued until the cleaning step or the cleaning is completed. Then the detergent is drained. If further cleaning steps are to be carried out, the procedure is repeated one or more times with fresh cleaning agent until the desired result is achieved. It follows, if necessary, a final cleaning z. B. by means of "steam out" method. Finally, the cleaned part of the plant is re-connected to the process.

Disposal of the contaminated cleaning agent may be carried out in dilute form either in a refinery-owned waste oil system (slop oil) or in the crude oil distillation plant itself by mixing the waste solution into the crude to be processed before the desalinators. Thus, a load on in-house wastewater treatment plants can be avoided.

In an advantageous embodiment, the inventive method allows monitoring of the cleaning process. At the beginning of the cleaning procedure and then at intervals, samples of the cleaning agent are withdrawn and examined photometrically or visually. The sampling can z. B. every 10 to 60 minutes, preferably every 15 or every 30 minutes. The sample quantity directs according to the selected evaluation. For a visual assessment, sample volumes of 0.5 to 1 liter are well suited. For photometric analyzes usually 50 to 200 ml, preferably about 100 ml are withdrawn.

Suitable photometers are all commercially available photometers with an optical layer thickness (cuvette diameter) between 1 and 5 cm. The preferred layer thickness is 1 cm. The absorbance (light absorption) of a sample is measured at a predetermined wavelength against a sample of the fresh detergent as a blank. It is preferred to operate at about 600 nm, but other wavelengths in the range of about 500 to 700 nm are also well suited. The absorbance E of the sample gives a statement about the content of dissolved or emulsified contamination. The higher the absorbance value, the more contamination the cleaning agent has already absorbed. If the measured absorbance value is outside the measurement range of the photometer, the sample is diluted with a colorless and turbid-free organic solvent and the absorbance measurement is repeated. The extinction corrected by the dilution factor is then calculated according to: E _k = E _g · f with E _k = corrected extinction, E _g = measured absorbance, f = volumetric dilution factor.

In the course of a cleaning step, the E _g and E _k values initially increase continuously and then typically reach a saturation state, ie after a certain cleaning time the values remain practically constant. This indicates the end of a cleaning step, the amount of cleaning agent used can no longer absorb further impurities. Then the cleaning is either stopped or continued with fresh detergent.

If no photometer is available, the evaluation can be done visually. In this case, the samples are withdrawn, filled into always equal, transparent containers and evaluated visually. The procedure can only be roughly monitored in this simplified way, which is quite sufficient for many applications.

The invention will be explained with reference to the following examples, but without being limited to the specifically described embodiments. Unless otherwise stated or necessarily different from the context, percentages are based on weight, in case of doubt on the total weight of the mixture.

The invention also relates to all combinations of preferred embodiments, as far as these are not mutually exclusive. The terms "about" or "approx." In conjunction with a numerical value mean that at least 10% by weight higher or lower values or by 5% by weight higher or lower values and in each case by 1% by weight. higher or lower values are included.

example 1

A crude oil sample of the variety REB was distilled in the laboratory with the aid of an automatic distillation apparatus and a gas oil fraction with a boiling range between 250 and 350 ° C was recovered. From this gas oil, the following detergents were prepared: cleaning supplies the solvent added additives 1 none, comparative experiment 2 3% by weight of n-alkylbenzenesulfonic acid (focus C ₁₀ -C ₁₃ ) (ABS); for example, Marion AS 3 (Sasol) 3 3 wt .-% calcium sulfonate, for example LUBRIZOL ADX 511 C 4 3% by weight PIBSI, for example Kerocom PIBSI (BASF) 5 3% by weight of C ₁₂ -C ₁₄ fatty amine ethoxylate, for example Lutensol FA 12 K (BASF) 6 1.5% by weight of fatty amine ethoxylate + 1.5% by weight of ABS

Detergents 2 to 6 were stirred at ambient temperature until a clear solution was obtained.

Example 2

Heavy gasoline (boiling point 145-150 ° C) was mixed with 3 wt .-% of a mixture of nC ₁₀ -C ₁₃ alkyl benzene sulfonic acid and PIBSI (weight ratio 90:10) and stirred at ambient temperature to a clear solution.

Example 3

The cleaning effect was investigated in the laboratory. The test was carried out with a deposit from a hot preheating train of a refinery. The deposit was about half of organic material and half of corrosion products. Each 0.5 g of the dried deposit was weighed, wrapped in a rectangular piece of plastic filter paper and placed in 25 ml glass bottles with a small magnetic stir bar. 20 ml of Detergents 1-6 from Example 1 were added and the solutions were stirred for 24 hours at ambient temperature with the magnetic stir bar not in contact with the filter.

The absorbance of the solutions was measured at the beginning of the tests at 600 nm in 1 cm cuvettes and the starting values recorded. After 24 h, the measurements were repeated, with the treated samples being diluted with xylene in a factor of 2 to 10, depending on the extinction. When evaluating the samples, the starting values were used as reference. In this way, the inherent color of the added additives was taken into account. The evaluation gave the following results: cleaning supplies corrected extinction E _k 1 0.1 2 6.1 3 1.8 4 1.6 5 0.8 6 4.5

While cleaning agent 1 had scarcely changed optically, the color intensity of the treated cleaning agents 2 to 6 had increased considerably and the coloration changed in the direction of black. It follows that both surfactants and dispersants alone and in combination significantly enhance the cleaning effect of the solvent. Particularly effective are alkylbenzenesulfonic acid surfactants.

Example 4

The cleaning agent according to Example 2 was tested on a deposition sample from an ethylene plant. The deposit was a brown-black solid and consisted almost entirely of organic material as analyzed for loss on ignition at 550 ° C. Infrared spectroscopic analysis showed a high proportion of polystyrene from the petrochemical process. The test was carried out according to Example 3, wherein each 1 g of the dried deposit and 70 ml each of the detergent or heavy fuel with no additives (blank) were used. The evaluation gave the following results (mean values from duplicate determinations): Blank values: E _k = 0.07 (f = 1) treated samples: E _k = 1.90 (f = 5)

The cleaning performance, ie the solubility, of the cleaning agent for this deposition was considerably higher with the inventive combination of solvent with surfactant and dispersant than with the solvent alone.

Example 5

• • Reinigungslastwagen mit starker Pumpe (20 m³/h Rezirkulationsrate)
• • 1 m³ Plastik-IBC als Puffertank
• • 4 zusätzliche IBC's zur Zwischenlagerung von Reinigungslösung
• • kleiner, dampfbeheizter Wärmetauscher
• • Schläuche und Verbinder
• • Photometer.

In the hot preheating train of a crude oil distillation plant, there was a significant deterioration in the heat transfer, especially in two heat exchangers connected in series at the end of the train observed. An analyzed sample of the deposits consisted of about 40% by weight of organic components, about 30% by weight of corrosion products and about 10% by weight of silicates. The organic fraction was characterized by IR spectroscopy as a mixture of heavy aliphatic hydrocarbons. In the affected tube bundle heat exchangers, crude oil of the "Russian Export Blend" (REB) variety had previously been heated from about 220 to about 250 ° C on the tube side. On the jacket side, vacuum residue had been cooled from 360 to 240 ° C. On the basis of this process configuration, a relatively heavy contamination on the shell side and a correspondingly lighter contamination on the tube side was suspected. The equipment used consisted of the following basic components:

• • Cleaning truck with heavy pump (20 m ³ / h recirculation rate)
• • 1 m ³ plastic IBC as buffer tank
• • 4 additional IBCs for intermediate storage of cleaning solution
• • small, steam-heated heat exchanger
• • hoses and connectors
• • photometer.

The exchangers were sealed off from the production process and emptied as far as possible. The cleaning agent consisted of gas oil (flash point> 80 ° C) as a solvent and 5 wt .-% of a mixture of C ₁₀ -C ₁₃ alkyl benzene sulfonic acid and PIBSI (weight ratio 90:10). The heat exchangers were connected on the shell side to the tank, the pump and the heating heat exchanger and circulated the cleaning agent at about 50 ° C. The total volume of cleaning agent used was about 5 m ³ . The progress of the procedure was followed photometrically by means of samples, whereby a rapid strong darkening of the solution was noted. After only about 5 minutes, the solution was black, so that it had to be diluted by the factor f = 50 for the photometric measurement. After 30 minutes, the cleaning had to be interrupted for operational reasons. The detergent remained overnight in the sealed enclosure. The next morning the cleaning was continued. The course of the extinction is in 1 shown.

After exposure to the detergent overnight, it was necessary to dilute the sample by a factor f = 100 before the photometric measurement. During the following 30 minutes circulation time (temperature about 50 ° C), the detergent became very dark, indicating a very heavy load of contaminants. A sample of the detergent that was drawn the previous afternoon and had stood overnight showed a large amount of black sludge / sediment which had sedimented over time. This also indicates a high loading of the detergent with dispersed solids. The loaded detergent was drained into the slop oil system of the refinery, a fresh batch was prepared in the same way and the shell-side cleaning continued. The measured absorbance is in 2 shown.

After the start of the second cycle, the solution again blackened very quickly, showing the residual contaminant / slurry dissolution from the previous step. After 90 minutes of cleaning time, the process was stopped and another fresh batch of detergent produced. The measured absorbance is in 3 shown.

After 45 minutes of cleaning time, no significant increase in absorbance was observed, concluding that the cleaning was complete. After a further 15 minutes of circulation time, the process was stopped, the loaded solution drained and the heat exchangers coupled back to the process.

The heavily soiled shell side was cleaned very efficiently and thoroughly by this process. The heat transfer was improved by cleaning by about 10%. No corrosion was observed on the equipment.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• CN 102242028 [0015]
• KR 20110077208 [0016]
• US 2004/0102351 [0017]
• US 2005/0211274 [0017]

Cited non-patent literature

• Mamedov et al. "Selection of solvents for the chemical cleaning of heat exchangers used for processing petroleum in the fields"; Izvestiya Vysshikh Uchebnykh Zavedenii, Neft i Gaz (1978), 21 (1), 55-8 [0014]

Claims (15)

Liquid detergent containing 70 to 99.9 wt .-% organic solvents, except C1-C3 alcohols, and 0.5-30 wt .-% surfactants and / or 0.1-30 wt .-% dispersants. Detergent according to claim 1, characterized in that it contains water in an amount of up to 10 wt .-%, preferably up to 5 wt .-% and in particular up to 1 wt .-%. Detergent according to claim 1 or 2, characterized in that from 0.5 to 30 wt .-%, preferably from 1 to 15 wt .-%, particularly preferably from 3 to 10 wt .-% of one or more surfactants are included. Detergent according to claim 1, 2 or 3, characterized in that from 0.1 to 20 wt .-%, preferably from 0.5 to 10 wt .-% and in particular from 0.5 to 3 wt .-% of one or more Dispersants are included. Detergent according to claim 4, characterized in that the dispersant (s) is (are) selected from polyisobutylene succinimides, polyisobutylene succinic acid esters, polyisobutyleneamines, polar modified polyisobutylene derivatives and mixtures thereof. Detergent according to at least one of claims 1 to 5, characterized in that the organic solvent consists of paraffinic, naphthenic or aromatic mixtures, in particular selected from heavy, directly distilled gasoline; medium to heavy side streams from atmospheric distillation such as kerosene and gas oil; crude aromatic cuts such as crude BTX (benzene, toluene, xylene, ethylbenzene); heavy aromatic cuts such as aromatic naphtha or mixtures thereof. Cleaning agent according to at least one of claims 1 to 6, characterized in that the organic solvent comprises aliphatic glycol ethers such as polyethylene glycol (PEG), polypropylene glycol (PPG) and their end-capped ethers and / or esters. Cleaning agent according to at least one of claims 1 to 7, characterized in that the organic solvent comprises linear or branched Succinsäurederivate. Cleaning agent according to at least one of claims 1 to 8, characterized in that at least one organic alkylsulfonic acid is used as the surfactant, selected from linear or mono- or polysubstituted, saturated or unsaturated alkylbenzenesulfonic acids having a C chain distribution in the range of C ₈ to C ₁₈ and non-aromatic alkyl sulfonic acids having a C chain distribution in the range of C ₈ to C ₁₈ . Detergent according to at least one of Claims 1 to 9, characterized in that the surfactant used is at least one nonionic surfactant chosen from fatty alcohol alkoxylates, fatty amine alkoxylates, alkylphenol alkoxylates, copolymers of ethylene oxide and propylene oxide and mixtures thereof. Process for the dry cleaning of plant components, in particular in refineries and petrochemical plants, comprising the steps: Provision of a liquid cleaning agent according to one of claims 1 to 10, circulating the cleaning agent in the plant parts and discharging the cleaning agent from the plant parts. A method according to claim 11, characterized in that the cleaning temperature between 20 and 80 ° C, preferably between 40 and 70 ° C. A method according to claim 11 or 12, characterized in that the cleaning is carried out in one or more cycles, wherein fresh detergent is used for each cycle and wherein a cycle lasts from 1 to 24 hours, preferably from 1 to 4 hours. A method according to claim 11, 12 or 13, characterized in that taken before and during cleaning samples of the cleaning agent and visually or photometrically on their content Contaminants are examined, the cleaning or a cleaning cycle is terminated when the content of impurities does not increase. A method according to claim 14, characterized in that the samples are examined photometrically, wherein the photometric evaluation is carried out at a wavelength of 500 to 700 nm, preferably at about 600 nm.

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