JPH0814499A - Decontaminating method of vessel - Google Patents

Abstract

PURPOSE: To easily remove the contaminant from a device of a chemical treatment passage by feeding an high-temperature aqueous solution of extraction agent/surface active agent mixture such as terpene and the like capable of trapping the contaminant. CONSTITUTION: In a case when the contaminant trapped in the scale residue of a process container or an auxiliary device is to be removed, an aqueous solution mixture for cleaning or its vapor is contacted with the scale on the surface of the process container or the autiliary device. This aqueous solution mixture includes an effective amount of terpene extraction agent and in some case, an effective amount of surface active agent, and has the high vapor pressure sufficient for dispersing the extraction agent and the surface active agent in the container under treatment conditions. The aqueous solution mixture is heated to about 165-230 deg. F, and dispersed in the process container or the device, so that it intrudes into the clearance of the scale residue to extract the contaminant, and captures the scale in a broken state into the aqueous solution mixture.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention removes contaminants, especially benzene, during routine repairs to clean the equipment and to secure personnel exposed to the equipment during internal inspections, maintenance and repairs. The present invention relates to a decontamination method for a hydrogen process device and a container. Specifically, the present invention introduces an extractant-based decontamination solution into the treatment system at the beginning of the process stream to be cleaned and recovers the solution from the end of the process for disposal or reuse. , A single cleaning method for all or part of the process flow path.

[0002]

BACKGROUND OF THE INVENTION In the chemical process and petroleum refining industries, maintenance and often capital improvement of process plants is performed every two years, or less often, if possible, to completely shut down the operating unit and inspect all aspects of its operation. And occurs on a scheduled basis at the scheduled time for maintenance. The operation unit is composed of various vessels, that is, a tank in fluid communication with each other, a heat exchanger, a distillation column, a reactor, and the like. Characteristically, in refining and petrochemical operations, feedstock such as crude oil is introduced at one end of the plant and the hydrocarbon product stream is removed at the other end for storage or transportation. Of course, any similar process flow device is also cleaned. This large maintenance effort at each unit is called routine repair and the maximum speed at which the unit can be put back into service is essential to plant economics. The reason is that, even if it is expensive in itself, the main cost of such an operation is the time during which this operating unit does not produce a purified product that can be sold. The speed at which work is done is, of course, determined by the need to maintain worker safety throughout the operation.

During routine repairs, the operating process cannot simply be stopped and drained to allow maintenance and repair personnel to enter. First, the process equipment
Decontamination of residue in the equipment that can be harmful and even fatal to personnel who must enter the equipment's internal structure to be inspected and maintained, even if not safe and refurbished. I won't. In maintaining and repairing processing equipment, it was usually necessary to clean and decontaminate a single container or groups of containers before entering for maintenance and repair. Current practice is that, depending on the equipment, a light hydrocarbon solvent is first used to remove heavy oil and tar, and then the hazardous equipment presents an explosion hazard to workers who must work in this environment. Has been infused with steam for a period of time until it shows that there is no residue left. The process equipment is also flushed with water where applicable to remove contaminants and degassed of the container to allow humans to safely enter for inspection and repair, often with steaming and flushing. Both are included. These processes often take a lot of time to achieve, even multiple days, and lost days of production. Repeated ineffective steam purging steps are eliminated, even after the solvent step. Of course, it is desirable to effectively clean and decontaminate all process channels at once.

After degassing, prior art methods of cleaning treatment systems typically rely on chemical reactions in which strong or weak inorganic or organic acids, bases or chelating agents ( HF, HCl, H2 SO
4, citric acid, acetic acid and hydroacetic acid or EDTA,
DTPA and similar chelating agents) are pumped through the process vessels and equipment to remove inorganic metal oxide scales, corrosion products and hydrocarbon deposits. Unfortunately, corrosion chemicals not only attack scale and contaminants aggressively, but also structural materials as well as contaminants, which can cause damage to pump mechanical seals. So it will not be pumpable through existing process pumps or lines.
In order to achieve the cleaning method it is necessary to incorporate independent smaller pumps and smaller lines,
It led to a slower and less efficient cleaning. And, of course, the acid cleaning process required a flushing step, a neutralization step and another flushing step-all requiring the handling of difficult-to-dispose chemicals and causing additional time delays. Low reactivity chemicals also did not necessarily clean the equipment. Neither treatment method achieves gas phase cleaning and does not remove hazardous volatile organic contaminants.

Removal of benzene and other volatile organic carbon components from process vessels is of particular importance to worker safety. It has long been recognized that chronic human exposure to high amounts of benzene in chemical and petrochemical workplaces leads to bone marrow depression, aplastic anemia, and leukemia.
Although absorption of benzene through the skin as vapor or in aqueous media can occur, benzene toxicity in process systems can most often be caused by inhalation of benzene that escapes removal. The current controlled safety standard for eight working days is set to benzene 1.0 ppm (average). National Institute of Occupational Safety and Health (NIO
SH) recommends an occupational long-term exposure limit of benzene 0.1 ppm in air (1989). That's not enough. The reason is that the workers employed by the repair service company are constantly exposed inside the process vessel. Worker safety regulations now limit such exposure.

Therefore, one of the major goals of the present invention is to
Benzene 0pp even if this standard is exceeded
It is to provide a decontamination method for process equipment approaching m. Benzene is often found everywhere along the process flow stream (in piping, valves, and pumps, as well as in towers,
Trapped under scale and other contaminants in reactors, tanks and heat exchangers and seeping out of the fouling deposit gap after cleaning is considered complete.
It was found to only be collected in the headspace of the container. Until now, there was no single method for decontamination of all process channels.

Even though there are many conflicting problems that converge on process equipment, the overriding requirement is still safety and speed, and the practice of the present invention provides a more effective way of protecting the environment. Achieve these while giving. The present invention allows near complete cleaning of process equipment (from crude oil feed pumps to product storage tanks) without having to open them in many cases until safe decontamination of hazardous substances, especially benzene etc. .

[0008]

SUMMARY OF THE INVENTION The present invention proceeds through an entire process stream that includes aqueous solutions, including piping, pumps and process equipment (except equipment that can be harmed by the introduction of non-process materials and is selected by plant personnel). An aqueous solution of an extractant and a surfactant having an affinity for pollutants is introduced into the process equipment, preferably at the feed stream position of the work piece when the equipment is online, and then the aqueous solution is environmentally friendly. To dispose in a good way
Or include improvements over conventional methods of decontaminating and cleaning process equipment by cleaning and reusing it back at the product end of such process streams. The method of the present invention uses materials that are non-hazardous, do not produce additional waste and can simply be disposed of by introducing them into a plant biological wastewater system that can be handled by the biosystem on a routine basis. To do.

Initially, the processing system equipment, although not required for the practice of the invention, may be drained when hot and flushed with a light hydrocarbon solvent for initial cleaning.
A sufficient amount of water will be introduced into the process stream device to provide a pump, preferably a process pump head, to be used to circulate it through the process stream device to be cleaned. The steam then injects into the system to circulate the now circulating water and process equipment from the feed inlet to the outlet equipment at a temperature of about 160 ° F (about 71 ° C) to about 270 ° F (about 132 ° C). Would heat up.
A wash injection is an extractant that is steam and has an affinity for the contaminant to be removed under steam conditions so that the steam and extractant condense on the inner surface of the device in the process flow path to remove and trap the contaminants. Continue by blending into steam. Surfactants that boil at the same temperature parameter or have a high vapor pressure within the same temperature parameter can also be blended with steam to penetrate deposit contaminant-containing voids and process equipment in both condensate and extractant. It is preferable to enhance the cleaning of the inner surface. The circulating water heated by steam also contains an extractant and, if present, a surfactant, and in addition to sweeping contaminants from the system, performs a cleaning function on the surface in contact with the circulating water. To help.

The terpene extractant is preferred for its boiling point and vapor pressure and the solubility of hydrocarbon contaminants in the extractant. Even if the surfactant and extractant do not boil within the steam temperature range, if the partial pressures of these two components are high enough at the cleaning conditions, the vapor will disperse throughout the process flow path and It will condense and penetrate into the contaminant gaps and hydrocarbon scale matrix to ensure the extraction and removal of contaminants. The method has been found to be particularly effective in completely removing benzene from the equipment. Condensation of vapor across closed process equipment produces sufficient force to extract contaminants from the interstices and even destroy the scale particles themselves. The chemical formulation is capable of uniformly delivering fine solids or colloidal solids with the hydrocarbons to the emulsion so that damage to the pump seals and fills is minimized. The emulsifiability of a particular contaminant surfactant is considered in the selection of the particular material used.

The chemical formulations useful in the present invention are usually removed using aromatic or aliphatic solvents (some of which may be carcinogenic or teratogenic) and detergents based on strong alkali. Tar, resin,
A wide range of typical hydrocarbon process industrial contaminants such as asphaltene, organic polymers and the like can be emulsified and dissolved. The decontamination solution of the present invention is not aggressive; it is non-reactive and safe for use with the metallurgy normally found in hydrocarbon processing units. This property allows circulation of decontamination solutions using standard process pumps already in place, thus pumping seals and packings that have been experienced during cleaning with reactive chemicals. Allows full maximum use of system pressure and flow rating without damage. In fact, the chemical formulation flow of the present invention is
It can be controlled and monitored from its own control room of the chemical plant. Surprisingly, the observation inside the device after cleaning resembles the appearance of the new device. The surface is so clean that in the case of mild steel an oxidising patina develops quickly.

The cleaning method of the present invention is applicable to almost any, if not all, hydrocarbon treatment system. For example, a method having the choices made within the art to select the extractant and, if used, the surfactant, should be used to clean any unit within the ordinary refining and hydrocarbon processing industry. May be. For example, the unit is not limited to a crude oil unit, a visbreaker system, a hydrocracking device, a hydrotreating device (including a reactor), a fluid catalytic cracking system (excluding the cracking unit itself), a delayed coking unit. , Ethylene pyrolysis units, amine units and other associated vessels. For example, each of the units will have a heat exchanger associated with them and some will include a direct heating furnace, such as a crude oil unit train.
It has been found that if a high temperature hydrocarbon treater is used, coking prospects occur and, surprisingly, the method of the present invention has a beneficial effect on the decoking of heaters and equipment.

In the oil refining method, the usual refining method is
Start with a crude oil preheater with a heat exchanger and furnace before entering the atmospheric distillation column for straight run cut of gasoline, then use a number of process vessels depending on the materials to be processed and the process steps used in the refining process To do. Traditionally, these containers are either cleaned with an aggressive acid as described above or shut down,
Separately cleaned using the appropriate cleaning method for the included contaminants. Surprisingly, the method of the invention decontaminates the device by circulating the solution to the initial feed system and through the system after the hydrocarbon flow path,
Make workers safe. Of course, it can be fed to other parts of the system and removed from the system at the product outlet or at any other suitable point. Although the solution circulation occurs at high temperatures, the extractant and surfactant evaporate and enter the area of the process to condense, trap and remove contaminants.

One of the major advantages of the cleaning method of the present invention is that
Flexibility in the ability to clean all process equipment or any part thereof. Simply stated, the process of the invention from the beginning of a routine repair situation involves shutting down and draining the entire process plant (whether a petroleum refinery, a petrochemical plant, etc.). Usually, this effluent will occur when the plant equipment is still hot and is then subjected to an optional flush with a light solvent to remove soluble hydrocarbons. A sufficient amount of water to provide a pump, preferably a process pump head, to circulate through the process stream device to be cleaned will be introduced into the process stream device. Circulation through the system would best be at least approximately turbulent velocity. Generally, this flow rate will be from 500 to about 5,000 gallons / minute, depending on the size of plant equipment and pumps used to achieve circulation. A preferred flow rate is about 8
It will be from 00 to about 1,400 gallons per minute. If the flow rate is too static, entrained contaminants can fall off. The amount of water introduced into the device to be cleaned will usually be sufficient so that cavitation does not occur due to lack of fluid in the intake of the pump when the pump is running at the desired flow rate. Typically, the amount of water introduced is from about 5% to about 25% of the internal volume of the process flow stream to be cleaned.
Will. Preferably, the amount is about 10% of the internal volume.
~ About 18%.

After this, the entire unit is heated by circulating water and then injecting steam through the process, usually into both the water and the void space of the unit. This is a matter of choice and convenience based on experience gathered from the particular method. The advantage is that this heats the entire single process including both shell side and tube side heat exchangers if both are in the process flow path. This allows the device to reach approximately 160 ° F.
(About 71 ° C) to about 270 ° F (about 132 ° C), preferably about 185 ° F (about 85 ° C) to about 225 ° F (about 107).
C.) until heated to a temperature of. The steam temperature can be up to about 375 ° F (about 191 ° C) to achieve the heating process. The extractant and surfactant, as defined herein, is then added to the steam and evaporated throughout the system to eventually condense the extractant and surfactant on the inner surface, leaving the process pump for a sufficient period of time, preferably about 8
Used to heat water to be circulated through the entire treatment system for a period of time or until the contaminants are removed. Circulation time about 6 ~
It was found that about 16 hours was sufficient for the normally effective first round of cleaning. The solution may be tested at circulation using known methods for emulsifying activity remaining in solution. If the activity is reduced or exhausted, the solution can be reconstituted by adding an extractant and / or a surfactant,
Or all can be replaced with fresh heated aqueous solution.

By adding a known amount of surfactant when testing the emulsifying activity, the decrease in activity can be indicative of the level of cleaning. Once complete cleaning is shown,
The entire process stream is drained and rinsed with water.

The removed contaminants, other than the larger solid particles, are retained in the aqueous emulsion so that the emulsion breaker can be used using known techniques to separate water from hydrocarbons and solids. It One of the most troublesome contaminants, benzene, is water soluble and must be removed from water and captured. The removed hydrocarbons can be sent to a conventional slop tank in the refinery and the recovered water can be sent to a biopond for bioremediation treatment.

If a significant amount of larger size solids is recovered, it is advantageous to connect the circulating filter unit to one of the purge points in the process (the circulating solution should be removed from the solution to be cleaned). Can be diverted to knockdown tanks and filters for removal of particles that are removed from the surface during the conversion process). Preferably, particles having a size greater than about 40μ should be removed to protect the plant process pump from wear and abrasion caused by pumping solids. Where the outer pump is adapted to achieve circulation without the use of a process pump, the preferred embodiment would involve the removal of greater solids, but the criticality of such removal is significantly reduced. To do.

Thus, the method of the present invention solves the total disposal problem of a plant. The reason is that solids can be handled in the plant in a safe disposal method; hydrocarbons can go to the slop pit or API sludge; volatile hydrocarbons including benzene are stripped from water, activated carbon, etc. Of the filter; and because the stripped water can be disposed of at the plant biopond. Traditionally, when prior art methods were used to clean the interior of the process, a large amount of hazardous waste remained, especially in the gas phase, creating additional disposal problems at the operating facility as well as to the operator. Failed to eliminate dangerous benzene exposure.

The use of the process of the present invention as described above allows for a shorter feed pump to product storage tank compared to prior art methods while maintaining strict safety standards for cleaning personnel. Results in almost clean cleaning of process equipment. Typically, a full routine repair of a hydrocarbon process system can be completed in about 3 days less than previous chemical or steam cleaning techniques.

In such routine repair situations, the plant is rarely contaminated with residual amounts of carcinogens such as benzene, xylene, toluene, and other hydrocarbons, both aromatic and aliphatic. Absent. The presence of these gases has been detected by various devices and limits have been set by health and environmental standards for safe human contact or how much each can be released into the environment. As such, these materials must be removed before work maintenance personnel can safely enter the container. Other cleaning methods and attempts, even with the use of surfactants,
It ameliorate and undermine the problems caused by volatile organics.

The processing system is typically equipped with accessories, where it ranges from about 212 ° F (about 100 ° C) to about 375 °.
F (about 191 ° C), preferably about 215 ° F (about 102 ° C)
℃) -about 350 ° F (about 177 ° C) steam,
A time may be introduced to condense on the interior surfaces of the equipment, pipes, heat exchangers and all process equipment and clean the interior surfaces to the point where contaminants can be collected. Alternatively, steam may be injected directly into the water to achieve heating. In the practice of the present invention, the cleaning fluid may be removed at the end of the process that normally collects the product. Additional washing with water and surfactant to collect residual contaminants is often necessary.
The steam used to heat the solution and equipment is
It is also preferably used for injecting a fumes of extractant, preferably with a surfactant. The extractant can be introduced into the column with steam or atomized into any vessel along the process stream, where it evaporates in steam,
It is carried to the process equipment where it condenses on the inside with steam and flows down inside the vessel. The solution pushes through the flow path by the action of the pump and floods the inner surface of the plant device to come into contact with the contaminants, thus removing the contaminants.

The extractant may be introduced into the steam and either injected into the system or added to the circulating water. Yet another method is to collect water from the bottom of the tower and the process low point, and recycle water from about 160 ° F to about 270 ° F.
C.), preferably about 185.degree. F. (about 85.degree. C.) to about 210.
Inject steam at a convenient location to heat to a temperature of ° F (about 99 ° C) and then about 0.1 to about 7% by volume,
Preferably, the extractant is circulated back through the system while adding circulating water to obtain a concentration of about 1.5 to about 5% by volume.

The extractant is selected from those having an affinity for the contaminant to be removed. The selection criteria are the boiling point of the extractant (which will condense on the surface of the metal and in the interstices in the metal such that the solubility of the material to be removed in the extractant, the vapor pressure and the temperature of the steam will be (preferably Before the condensation of steam), and therefore the inner surface of the vessel is washed as the water condensate flows down and meets the solution flowing through the device]. The extractant material is non-toxic and non-hazardous and has a high vapor pressure or boiling point that is within the range of steam available in a particular plant for use when steam injection is to be performed, preferably about 212 ° F ( About 100 ℃) 〜
About 375 ° F (about 191 ° C), preferably about 275 ° F
It should be selected to have (about 135 ° C.) to about 350 ° F. (about 177 ° C.). Thus, the partial pressure of extractant will be significant at cleaning conditions.

Preferred extractants having an affinity for scales and contaminants commonly found in hydrocarbon treatment units include various terpenes and other materials such as dipentene, sinene, kayapten, diamylene, bergamot oil, geranium, citronella, Jill, and caraways and related terpenes, such as hermiterpenes (isoprenes), sesquiterpenes (caryophyllenes),
Examples include diterpenes, and polyterpenes. A preferred extractant is limonene, especially d-limonene. Mixtures of several extractants may be satisfactorily used on the same basis as set forth above. Consultation with a table with vapor pressure information and a simple experiment to determine the affinity of an extractant for contaminants is all that is needed to select a mixture and determine its relative properties.

The matter of choosing a satisfactory surfactant is also within the skill of the art. The boiling point and vapor pressure criteria remain the same, that is, up to about 375 ° F (about 191 ° C) so that the surfactant will also condense at substantially the same time as the steam and extractant materials condense. is there. This means that metal cracks and fissures, including interstices in the matrix of scale-like contaminants, and the interior of the entire process system are all penetrated by the components of this cleaning system to destroy the scale and dissolve the contaminants in solution (microemulsion). ) And remove nuisance contaminants, especially volatile organics such as benzene. Heretofore, cleaning and decontamination of whole process plants with disposable and non-hazardous materials friendly to the environment and process sealing equipment, especially seals etc., has not been available. The available methods did not safely remove hazardous VOS, especially benzene, to allow the workers quick access to the equipment for inspection and maintenance. The ability to clean as well as decontaminate the entire process from one end to the other in the same manner is a great advantage of the present invention.

The given surfactant may be an anionic surfactant, a cationic surfactant, an amphoteric surfactant, or a nonionic surfactant, or a mixture of several species, but is selected. Are within the experience of the experienced chemist, depending in particular on the substances to be removed as pollutants, the extractant to be used and the relative amounts expected to be picked up in the wash liquor from the condensation steam or circulating water wash. . The HLB (hydrophilic / lipophilic balance) of the selected surfactant is preferably 6 to 1 for optimal results in the practice of the present invention.
It should be 8, preferably about 7.5-12. The properties of members of these classes of surfactants are well known as many compounds fall within these classes. Many surfactants and / or emulsifiers may be selected for use in the practice of this invention depending upon the many different process streams that can be cleaned using this invention.

The preferred surfactants are selected from ethoxylated alkylphenols having an average of about 6 to about 12 moles of ethylene oxide per mole of alkylphenol (the alkyl group has 8 to 10 carbon atoms). Another preferred ingredient in the surfactant mixture has a molecular weight of about 1,5.
It is a block copolymer of ethylene oxide and propylene oxide having from 0 to about 2,500. In a particularly preferred embodiment, the third component is a fatty acid alkanolamide, which is sometimes and often available in commercial solution as a 50/50 mixture with linear alkylbenzene sulfonic acids. Many variations on this subject are well within the practice of the invention and the components may be modified in their configuration as well, without departing from the practice of the invention. The combination of substances described above is particularly useful in preparing stable microemulsions with the preferred extractants, namely terpenes and especially d-limonene. It has been found that such mixtures have a high range of volatility and are useful in contacting and removing many different types of contaminants found in hydrocarbon processing units.

Mixtures of surfactants in some of the types described above can be successfully used, especially in situations where a premix of extractant and surfactant is used. This premix will usually be in the form of a microemulsion of several extractants and a surfactant. Often, some surfactants will be needed to enhance shelf life as a homogeneous fluid, especially as a microemulsion with water acting as a discontinuous phase in a continuous phase terpene. Of course, the emulsion inverts in the presence of large amounts of water. Such a mixture will be infused in an amount of about 0.2 to about 0.4 pounds / lb steam, preferably about 0.25 to about 0.33 pounds / lb steam. When added to the circulating liquid, the amount is usually about 0.1% to about 7%, preferably 1.5.
To about 5%, more preferably about 2% to about 4%, will yield an effective amount of extractant and surfactant to be present. The emulsification of contaminants is an important factor of the present invention and given knowledge of the contaminants and the description herein, those skilled in the art will be able to select useful mixtures with a few experiments.

In carrying out the method of the present invention, from about 0.06 pounds to about 0.1 pounds per pound of steam (or water).
3 pounds, preferably about 0.1 pounds to about 0.20 pounds of extractant should be present. Similarly, the surfactant should be introduced at a ratio of about 0.001 pounds to about 0.01 pounds, preferably about 0.003 pounds to about 0.005 pounds per pound of steam. When both an extractant and a surfactant are present, they are present at about 0.
It is present at a ratio of 5 to about 30 pounds, preferably about 1.5 to about 10 pounds per pound of surfactant. As mentioned above, all of the substances may be introduced at the same time as steam, or one may be introduced with steam and the other or both the extractant and the surfactant may be picked up by steam and vaporized. , May be transported through the device with steam until condensed. The steam and extractant can be premixed prior to injection into the container or injected at separate points in the container. Similarly, the extractant, surfactant and steam, all three, may be premixed prior to injection. In yet another method, the extractant and surfactant, either separately or as a mixture, may be mixed with water at temperatures as described above and circulated through the device to be cleaned.

Many of the methods in which the present invention is useful include distillation columns having a reflux system and a demister pad of woven metal strands at the top of the column, which must also be decontaminated. By carrying the extractant / surfactant steam mixture of the present invention upward through the vessel (condensation occurs at or near the top and even in the reflux apparatus itself), all columns are contacted and flushed by the practice of the present invention. It is possible to leave only liquid residue at the bottom of the column for removal by the circulating liquid solution. Similarly, when an embodiment involves the use of circulating a solution of extractant and surfactant through the tray and / or column packings during or after steaming, a relatively small amount of contaminant-containing While only the water emulsion remains for disposal,
A safe and clean tower remains. After implementation of any of these operating methods for closed decontamination of the process tower, entry of personnel for inspection, maintenance and repair may be achieved. After cycling through the entire process, the system may be tested for safety and then disassembled for such repair or maintenance as needed. As another advantage of practicing the present invention, routine repair maintenance involving a portion of the device may be performed on a bi-annual basis for excellent cleaning.

In one aspect of the invention, about 2.9-
Until a pressure of 8.7 kPa (20 to about 60 psig) is reached,
Steam is poured into the container. The injection is stopped and the column is kept so that condensation occurs on the inner surface. The condensed steam, extractant and surfactant, in use, condense on the inner surface to form a pool of condensed liquid and chemical residues that contaminate the container. Remove this pool of condensed liquid,
The container is then tested to determine if the amount of contaminants is such that human entry would still be unsafe. If this is the case, the process repeats.

In another embodiment, a cascade or circulation method is used to clean the vessel. Closed vessels, usually packed columns or tray-like distillation columns, are first partially filled with enough water to wet the packing or fill the tray and still keep the pump intake covered during circulation ( Usually about 8% to 15% of the tower capacity). A water circulation loop is provided by connecting the line from the bottom of the container to the top of the container. This loop causes water to flow down through the fill in the container or onto a tray, aspirating from the bottom, and pumping back up to the top of the container for drainage. The water is recirculated through the circulation loop at a rate sufficient to submerge the fill or fill the tray, preferably about 1000 GPM, while simultaneously pouring steam into the base of the vessel. Once the water temperature reaches about 85 ° C (185 ° F), an effective amount of extractant and surfactant material is injected into the water circulation loop. The circulation continues at a temperature of about 85 ° C (185 ° F) or higher for about 3 hours. As before, the circulation or agitation is stopped, the circulating liquid is collected or removed at the bottom of the column and the vessel is rinsed with fresh water. Again, the container is tested before entering.

The practice of the present invention substantially reduces the time and enhances the cleaning results, allowing the process equipment to be brought back into service immediately. As a particular advantage, the process equipment does not contain volatile organic compounds (VOCs), especially the known carcinogen benzene. Previous attempts at decontamination have left residual benzene contaminants endangering workers in the equipment.
VOCs will traditionally be trapped in the headspace of the vessel, which they later purged into the atmosphere. Such purging is no longer possible under current environmental standards. Using the method of the invention, benzene is trapped in solution and removed. After practicing the invention, testing on the device
It showed undetectable amounts of benzene or other VOCs even without purging the hazardous material into the atmosphere. After recovering the water, breaking the emulsion and separating the phases, the water can be stripped using known techniques and the benzene and VOC captured in a suitable system.

For example, a preferred extractant-surfactant mixture for cleaning the reactor was prepared using the following ingredients: Table I (Mixture A) wt% d-limonene 57% nonionic Copolymer 19% Monamulse 653-C2 17% Butyl Cellosolve 3% Nonionic Surfactant 35 5% Water 9% 100% 1 Block Copolymer of Ethylene Oxide and Propylene Oxide with Molecular Weight 1950 and HLB 12-18. Coalescing. 50/50 of ethanolamide of C12 fatty acid and linear alkylbenzene sulfonic acid in 10% isopropanol
90% active ingredient of 50 mixture, bp 205 ° F (about 96
° C). 3 Nonylphenol ethylene oxide 10 mol adduct In another embodiment (Mixture B), it is represented by butylcellosolve and a nonionic surfactant in the mixture 8
% Replaces ethylene oxide 6 mol adduct of nonylphenol with HLB 10.8.

The above components have a long shelf life when mixed together and include light substances such as benzene, toluene, xylenes, oils or greases (these are process flow devices which perform cleaning despite the high temperatures). A stable microemulsion of water in terpene is prepared which has good dissolving power for being trapped and retained in the emulsion until it is removed. In cleaning the column, one of the above microemulsions is injected into the column with steam at a rate of 0.5 kg / steam to 1.4 to 1.8 kg (1 lb / 3 to 4 lbs). Injection continues until the column is cleaned and the amount of surfactant / extractant and steam is determined by the size of the column and the degree of contamination therein.

The effluent from the decontamination process is scrubbed using conventional gas stripping operations where hydrocarbons can be recovered and water containing soluble light hydrocarbons (especially benzene) is suitable for environmentally safe disposal. Or it could be redissolved in hydrocarbons, solids and the aqueous phase so that it could be stripped. Solids can be removed for incineration and landfill disposal.

The following examples are introduced for the purpose of the present invention to further illustrate the advantages of the present invention and should not be considered as limitations on the scope of local application of the present invention.

Example 1 This example illustrates the decontamination of a petroleum crude oil treatment stream, including a furnace, crude oil vapor distillation column, and vacuum column with associated heat exchangers, using the process of the present invention.

A circulation loop was set up to pump a heated aqueous solution containing about 2% of surfactant, extractant, and mixture B (above) at a temperature of about 210 ° F (about 99 ° C) through the process system. A flow line was formed by connecting a filter track, a series of preheat heat exchangers, a petroleum furnace, a crude oil vaporization tower and a vacuum tower and returning to the filtration track. A pump on the filter truck initiates the flow of the surfactant, extractant, heated aqueous solution of the invention through the crude oil process flow path in the circulation loop. After cycling for about 10 hours, the system was drained and opened for inspection and appeared to be noticeably clean to experienced personnel.

The usual procedure was then followed for decoking the furnace except that no pre-burning was performed. Despite the changes, the decoking time in the furnace was reduced by about 4 hours and the pre-combustion step was unnecessary.

Example 2 This example illustrates the decontamination of a naphtha splitter tower to allow entry for maintenance inside the tower.
Excess liquid hydrocarbons were first flushed from the tower with hydrant water. The tower was then filled with water to 10% by volume.

A filter / pump trailer was connected to the column, with suction from the bottom removal line of the column and discharge to the top tray of the column to provide a continuous recirculation cascade effect through the column. At the same time the steam was injected at the base of the tower using the steam available in the refinery, the water circulation was started at 3860 liters / minute (1000 GPM), resulting in agitation between the solution and the surface. Once the water temperature reached 85 ° C (185 ° F), the decontamination mixture of the present invention (Mixture B above) was injected into the water loop to a concentration of 2.0.
% Was given. Circulation was continued for 3.5 hours, maintaining the temperature at 85 ° C (185 ° F).

The circulation was then stopped and the liquid containing hydrocarbon scale and contaminants was pumped directly to the refinery "slop" storage. The tower was rinsed twice with water and again all contaminated water was pumped into the slop. Water 10 in the tower
Refill to volume% and add cleaning mixture B again,
A 2.0% solution was given and the circulation step was repeated for 3.5 hours. As before, all "waste" liquor and rinse water was pumped into the slop.

The bottom connection was opened and a large amount of heavy debris was flushed from the bottom of the column and removed by vacuum truck. It took only 17 hours from the start of circulation to complete the final flush and drain the safe decontamination naphtha tower.

When the tower was opened by refinery personnel for inspection, the refinery personnel asserted that it was gas-free, hydrocarbon-free and cleaner than previous decontamination methods. Internal work could start immediately. The entire project, including filter / pump trailer assembly and disconnection and removal, took only 24 operating hours.

Example 3 Decontamination was performed with 23 trays having a bubble cup design, diameter 1.7 m (5 feet 6 inches), height 19
It was done in a 62-foot m bisbreaker tower. 82 ° C. containing 3.0% cleaning mixture B using a filter truck connected to the column as described in Example 1 above.
Approximately 10598 liters (2800 gallons) (25% of column volume) of (180 ° F.) water was circulated through the entire column for 8 hours. Samples of circulating water were collected at hourly intervals to test how well the emulsification of contaminants in the tower proceeded.
After 8 hours, the waste liquid from the tower was removed and transported by vacuum truck to a portable tank. The tower was then rinsed with fresh water and the rinsed water was also carried away by vacuum truck to a portable tank. The tower personnel path was opened immediately upon completion of the rinse cycle. The tower was inspected and appeared to be clean to bare metal. In the tower, the walls were felt to be grease-free and hydrocarbon-free on contact. The next morning, refinery officials inspected the tower and declared it safe to enter. There was no odor of hydrocarbons present and there was no detectable amount by instrument.

Example 4 This example illustrates cleaning a heat exchanger bundle with a visbreaker bottom on the shell side and crude oil on the tube side. 8.2m x 2.2m x 2.9m (27ft x
Build an 8ft x 9.6ft "bat",
The bundle was cleaned by installing steam and air lines. This is an auxiliary heat exchanger for the visbreaker tower described in Example 2.

About 30280 liters of water (8
000 gallons). Water temperature is about 82 ° C (180 °
Steam was injected into the water through the steam line until F) was reached. Cleaning mixture B 4 drums "bat"
To prepare a solution of about 3%.

The bundle had a heavy coat of viscous tar and coke on the shell side. In some places, the accumulation is
The thickness was about 7.6 cm to 10.2 cm (3 inches to 4 inches). The drawn bundle was then placed in a "bat" containing the hot 3% aqueous solution. The "vat" was covered with tarpaulin (to avoid air pollution) and an air line was connected to the vat and activated to provide agitation. Bubbling occurred, shutting off the air line. The bundle was soaked in a vat for 8 hours without stirring. After 8 hours, the bundles were taken on a hydroblasting pad for hydroblasting with high pressure water.

The hydroblast of the bundle is foulant.
Shows that the top layer of the is easily removed, but that the coke layer between and on the tubes prevents the penetration of the cleaning mixture, so that the viscous tar-like dirt between the tubes is not emulsified by the cleaning mixture solution. Indicated. The old (ie, first) 3% cleaning mixture solution was completely depleted during the first soaking cycle.

The bunches are placed in a fresh 3% solution of cleaning mixture B 4
Soaked again for hours. The second soaking of the bundle was greatly facilitated as the cleaning mixture solution could now penetrate the scale, destroy the hydrocarbon matrix and emulsify the tar between the tubes. Subsequent hydroblasting helped remove the previously impermeable coke layer. It took about 1.5-2 days to clean the bundles (usually up to 8 days). Refinery staff were pleased with the results.

Example 5 Liquid circulation tubes of a fan cooler with two fins were connected in series and the capacity of the tubes was calculated to be about 7
It was 570 liters (2000 gallons). A holding tank (baker) was filled with about 11355 liters (3000 gallons) of water and a steam line was attached to the tank. The water in the tank is heated to 82 ° C (180 ° F) and the cleaning mixture B about 303 liters (1.5 drums) (about 8
0 gallons) was added to the tank. The solution thus prepared (cleaning mixture about 2.75%) was passed through a fin fan tube connected in series at about 82 ° C (180 ° F).
) For 6 hours. After circulating the solution, it was drained and returned to the tank. The fin fan was rinsed with fresh water from the hydrant. The fin fan exhaust was inspected and looked very clean. Once again, the refinery staff were very pleased with the work. Two additional fin fans were cleaned later in the same manner. Excellent results have been obtained. Hydrocarbon fouling was not observed.

Example 6 This example relates to the successful decontamination of a complete hydrocracker process system in a refinery. The decontaminated hydrocracker process system consisted of the following 10 units plus all heat exchangers and units and associated piping.

1) First step reactor feed 2) Second stage reactor feed / effluent 3) Stabilizer overhead 4) Splitter tower 5) H2 S stripper tower 6) Feed surge drum 7) Splitter overhead integration Equipment 8) Low Pressure Separator 9) H2 S Stripper Overhead 10) Stabilizer Tower Using 1.0% of Cleaning Mixture B cycled at 82 ° C (180 ° F) for about 6-8 hours, each of the above units was used. Decontamination was performed according to the applicable steps of the above example. The unit was then drained and rinsed with fresh water. The effluent and rinse water were sent to a holding tank where they were disposed of with other refinery wastewater.

Upon opening, each of the units was found to have no detectable benzene. After the decontamination process, the H2 S stripper column, the overhead integrator, and the stripper column are not only benzene-free, but also H2 S-free and FeS at the bottom.
It had little sludge. Refinery staff
I was very pleased with the result.

In the H 2 S stripper column and first stage reactor feed / effluent, sodium carbonate was added to the circulating 1% solution of mixture B to neutralize any acid that might be present.

There were 10 freestanding pumps with separate filter units for circulating the Mixture B solution. Each unit was treated individually. Some of the larger units, for example, 49.4 m (162 ft high) stabilizer column and 49.4 m (162 ft high) stripper column, are installed above the column to circulate the mixture B solution.
Individual freestanding pumps and reflux pumps were used.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Richard, W, Krajchek, Texas, USA, Houston, Harman, Drive, No. 29, 1111

Claims (26)

[Claims] 1. A method for removing contaminants trapped in scale residue of a process vessel or auxiliary equipment, wherein the scale on the surface of the process vessel or equipment comprises a cleaning aqueous liquid mixture or its vapor (wherein the mixture is (Containing an effective amount of terpene extractant and optionally an effective amount of surfactant, each having a vapor pressure high enough to disperse such extractant and surfactant in a container at processing conditions) Contacting the aqueous liquid mixture with the aqueous liquid mixture from about 165 ° F. to about 230 ° F.
Heating to a temperature of 10 ° C.) to disperse such extractants and surfactants in the process vessel or equipment to penetrate the interstices of scale residue, extract contaminants, destroy scale and contaminate scales. A method for removing contaminants, which comprises trapping a product and a scale residue in the aqueous liquid mixture. 2. A method according to claim 1, characterized in that the aqueous liquid mixture is recycled during processing conditions. 3. The process wherein the contaminant is benzene, the aqueous liquid mixture contains a surfactant having an HLB of from about 6 to about 18, and the method is in contact with the surface thereof. Circulating the aqueous liquid mixture in a container to allow the aqueous liquid mixture to enter the interstices of a time scale sufficient to break the scale and trap benzene contaminants in the aqueous liquid mixture, Such extractants and surfactants as vapors are dispersed in the process vessel and condensed on the surface of the vessel to break the scale, trap layers and scale residues in the aqueous liquid mixture, and the aqueous liquid mixture to the process vessel. Or a step of separating from the surface of an auxiliary device and removing the benzene contaminant from the vessel and the device by the aqueous liquid mixture. The method according to 1 or 2. 4. The method of claim 3, wherein the aqueous liquid mixture is circulated for about 1 to about 8 hours. 5. A method of removing benzene contaminants from a process vessel that has been shut down and drained, while fully permitting human entry into the vessel for repairs and maintenance, the method comprising: ) Is injected into the container for a time sufficient to reduce benzene contamination due to the presence of chemical residues so that it is safe to be exposed to humans, up to the temperature of the injected steam. A terpene extractant for a chemical residue in a vessel having a boiling point of about 0.06 pounds to about 0.3 pounds per pound of steam is injected into the vessel in the presence of steam, and HLB as an optional ingredient in the presence of steam. Up to about 0.2 pounds of surfactant having about 6 to about 18 pounds per pound of steam is injected into the container (provided that both extractant and surfactant, if present, are about 0.5 to about 10 parts of extractant About 30 pounds / world The surfactant, present in a ratio of 1 lb), vapor, extractant and surfactant are condensed in the vessel on the inner surface and penetrate the gaps in the scale on the surface to extract and trap the benzene contaminants, the condensed liquid. And a step of forming a pool of chemical residues and removing the condensed liquid and the chemical residues from the container. 6. A terpene extractant from about 0.1 pounds to about 0.2.
Pounds injected per pound of steam, HLB about 7.5-
A nonionic surfactant, an anionic surfactant, a cationic surfactant or an amphoteric surfactant having about 12 about 0.0003 to about 0.005 pounds of a mixture thereof is injected per pound of steam. The method according to 5. 7. A step of limiting the escape of vapor from the vessel while condensing the vapor, extractant and surfactant.
The method of claim 6. 8. The step of stopping the injection of steam when the pressure in the container reaches about 20 to about 60 psig and holding the steam in the container for a time sufficient to cause condensation.
Or the method according to 7. 9. A process according to claim 6, 7 or 8 wherein the vapor and extractant are premixed prior to injection into the container and are preferably injected into the container at several separate locations. 10. The method according to claim 6, wherein the injection point of the vapor is separate from the injection points of the extractant and the surfactant. 11. The method of any one of claims 6-10, wherein the extractant / surfactant mixture is injected at a rate of about 0.2 to about 0.4 pounds per pound of steam. 12. The method of any one of claims 6-11, wherein the concentration of the extractant / surfactant mixture is from about 1.5% to about 5%. 13. A circulation loop connected from the bottom to the top of the vessel, partially filled with water sufficient to provide continuous circulation to the vessel, and passed through the loop at a rate sufficient to produce a uniform flow in the vessel. Circulate the water and heat the water to a temperature of about 165 ° F (about 74 ° C) to about 230 ° F (about 110 ° C) using the steam injected into the container and inject the heated water into the container. About 1.5 to about 7 with the extracted agent and surfactant.
13. A method according to any one of claims 6 to 12, comprising the step of circulating the benzene trapped condensed liquid from the vessel for a period of time. 14. The method of claim 13 comprising injecting the extractant into the vessel at the same time as the vapor. 15. The method of claim 13 or 14, wherein the circulation rate is from about 800 to about 1400 gallons / minute. 16. A method of simultaneously decontaminating chemicals in fluid communication or purifying process equipment to remove adherent contaminants and cleaning process flow equipment for use, maintenance or repair. Draining the flow path to be cleaned and pumping a hot aqueous solution along the process flow path of the device in fluid communication along such process flow path (wherein the aqueous solution is Contacting the inner surface of the device (containing an effective amount of extractant with affinity and at least one surfactant having emulsifying activity between the contaminant and water) to trap the contaminant in the solution Allow the extractant and surfactant to penetrate the deposit gap at temperatures and times sufficient to drain the solution from the process flow path to be cleaned and contaminate the process equipment with the solution. Method characterized by comprising the step of removing. 17. The method of claim 16 comprising recirculating water, extractant and surfactant in the process flow path for about 6 to about 16 hours using a process equipment pump. 18. The temperature of the circulating solution is about 160 ° F. (about 7 ° C.).
1 ° C. to about 230 ° F. (about 110 ° C.).
7. The method according to 7. 19. The method of claim 16, 17 or 18 wherein the extractant is a terpene and the surfactant has an HLB of about 6 to about 18. 20. The terpene is d-limonene, the surfactant is a 6 to 12 mol ethylene oxide adduct of alkylphenol (wherein the alkyl group has 8 to 10 carbon atoms), the molecular weight is about 1,500 to about 2. 20. The method of claim 19, comprising a block copolymer of ethylene oxide and propylene oxide having a 500, 500 and a fatty acid alkanolamide. 21. Hydrocarbon residue from a refinery for processing crude oil hydrocarbons to produce a straight run fractionation product through a flow path including a heat exchanger, a crude oil furnace and a rectification column in fluid communication with each other, and Claim 1 for cleaning coke
21. The method according to any one of 6 to 20, wherein an aqueous solution containing a surfactant having an emulsifying activity between crude oil, coke deposit and water passing through a process device from a crude oil inlet to a refiner system. Pumping it into contact with the contaminated interior surface of the crude oil flow path device, allowing the extractant and surfactant to penetrate into the fouling deposit gap for a time sufficient to trap the contaminant in the solution; The aqueous solution is passed through a crude oil furnace and brought into contact with coke and carbon deposits in a crude oil hydrocarbon flow path, and the contaminated solution is allowed to flow into a crude oil rectification column, where a heavy bottom solution containing solids and a light emulsification overhead solution. Flow into the crude oil treatment equipment flow path, the bottom solution is circulated through the solids removal system, and extracted for return to the crude oil hydrocarbon inlet. A method comprising providing an aqueous solution of an agent and a surfactant. 22. A bottoms stream containing solids is removed from the rectification column and pumped through a knockout drum and a filter to remove the solids, and an aqueous stream substantially free of solids is rectified through a connection. 22. The method of claim 21, pumped to the column reflux line. 23. The emulsified overhead solution is treated to break the emulsion and the aqueous solution recovered from the emulsified hydrocarbon is contacted with countercurrent flow of gas in a stripping vessel to remove benzene contaminant overhead, 23. A method according to claim 21 or 22, characterized in that an upper benzene-free aqueous stream is left, and the method comprises the step of capturing benzene in a carbon filter and discarding substantially benzene-free water. 24. A method of removing chemical contaminants from all or a portion of a fluid communication system that has been shut down and drained to allow sufficient human entry into the system equipment for repair and maintenance. At about 5% to about 25% of the system capacity while heating water by steam injection at temperatures up to about 375 ° F (about 191 ° C).
A terpene extractant for chemical residues in a system having a boiling point up to about the temperature of the injected steam is circulated through a fluid path of a given system to charge about 0.06 pounds to about 0.3 pounds / One pound of steam is added to the water circulating through the system in the presence of steam and optionally HLB from about 6 to about 1 in the presence of steam.
Approximately 0.2 lbs of surfactant mixture having 8 up to 1 lb of steam is circulated through the system (provided that when both extractant and surfactant are present, they are about 0.5 to about 30 eq. Present at a ratio of 1 lb / lb of surfactant), heated water, extractant and surfactant in the system in contact with the inner surface of the device and circulated for a sufficient time to trap chemical contaminants To form a mixture of liquids containing trapped contaminants and pump the heated liquid into the system at a rate low enough to sweep the liquids and contaminants out of the system. A method comprising removing an object from a system. 25. The method of claim 24, wherein the flow rate is about 800 to about 1,400 gallons / minute. 26. About 0.06 to about 0.3 pounds of extractant / one pound of steam and about 0.001 to about 0.01 surfactant.
26. A method according to claim 24 or 25, wherein 1 pound / lb steam is injected.