RU2592521C1 - Two-stage method of cleaning surfaces from oil products - Google Patents

Abstract

FIELD: technological processes; oil and gas industry.

SUBSTANCE: invention relates to methods of cleaning surfaces from hydrocarbon contaminants and can be used in various industries for powered washing and cleaning equipment and material ducts during preparation for internal survey, repair and/or changing content. Method includes the first stage consists in supply of working medium in form of a Jet onto treated surface and removal from processing zone products washing and the second stage consists in rinsing washed surface of the second working medium and removing products rinsing. Products of washing and rinsing with both processing stages is discharged in collector-separator for coarse separation into hydrocarbon, water and emulsion layers. Emulsion layer containing direct and reverse emulsion is used as working medium at the first stage of treatment. Water layer is used as working medium at the second stage of treatment. Part of the hydrocarbon layer is directed to the station dehydration to separate water from it and return to compensation of losses of water layer, and dehydrated hydrocarbons is implemented as a commercial product.

EFFECT: efficient cleaning surface with simplification of technology and reduction of total costs.

1 cl, 1 dwg

Description

The invention relates to methods for cleaning the surface of hydrocarbon contaminants, such as oil, oil products, lubricants, oils, technical and household fats, and can be used in various industries for mechanized washing and cleaning of equipment and pipelines.

The traditional method of cleaning apparatuses and material pipelines is steaming, it is accompanied by atmospheric pollution, discharge of “oily” steam condensate, harmful working conditions for washers, high costs of working time and energy resources (A.A. Evdokimov, A.F. Bogdanov, V.M. Smolyanov Highly efficient cleaning technology for railway tank boilers. In the collection “Improving Reliability and Improving Rolling Stock Repair Methods,” St. Petersburg State University of Civil Engineering, 2002).

The most effective method for removing the bulk of contaminants is washing with organic solvents. Universal solvents are most often used: acetone, kerosene, white spirit, which are flammable liquids (B.G. Petrik, P.V. Chulkov, S.I. Kalashnikov. Reference: Solvents and compositions for cleaning machines and mechanisms, M .: Chemistry, 1989). The main operations in these methods: washing the surface to be cleaned, pumping out the resulting solvent mixture with hydrocarbon contaminants, and discharging the saturated waste solution to the treatment plant. However, after removing contaminants, it is necessary, as a rule, to clean the treated surface from residual solvent. To do this, the surface moistened with solvent is dried, for example, with hot air, which must be cleaned before discharge so as not to pollute the atmosphere. In another embodiment, the surface is rinsed, for example, with water, the contaminated part of which will then need to be cleaned, and the film wetting the surface is evaporated during the drying process. It should be noted that the spent solvent, as it is saturated with hydrocarbon contaminants, must also be cleaned so as not to lose it, but reused. Taking into account the need to implement auxiliary processes: solvent regeneration, rinsing and drying the surface, water purification, the considered method as a whole seems to be the most complex and energy-intensive. Other disadvantages of using flammable liquids as liquid organic solvents include: explosion and fire hazard, harmful and even dangerous effects on people and wildlife when released into the atmosphere, soil or body of water.

Another group of methods for cleaning the surface of hydrocarbon contaminants include those that use water and / or aqueous solutions. The authors of these methods suggest not emulsifying, but emulsifying hydrocarbon contaminants. The presence of water really allows you to solve a number of issues. Firstly, the equilibrium vapor phase above the water-hydrocarbon mixture contains more than half of the water vapor, which plays the role of a phlegmatizer, and therefore is non-explosive. Secondly, the high heat capacity and low viscosity of the water make it possible to solve one of the main tasks: to heat and remove from the treatment zone highly viscous, tarred, and dried contaminants that impede surface finish. The main disadvantage of the known methods of processing using water is that they do not solve the problem of capture and subsequent processing resulting from the treatment of water vapor.

A known method of cleaning the surface from hydrocarbon (oil and fat) contaminants based on the use of two liquids (RF patent No. 20139318, IPC B08B 3/08, priority date 07.28.1992, published in 1994). The washing of the surface of products by this method is carried out with a washing solution and the washed impurities are removed from the washing solution with the help of an extractant - auxiliary liquid, which does not form a stable emulsion with a washing solution, but is capable of selectively extracting oil and oil contaminants from it. As the extractant is saturated with hydrocarbon contaminants, it (extract) is sent for distillation. The extractant is distilled off (regenerated) and returned to recycling for reuse. To wash away viscous impurities with a washing solution, the process must proceed at a temperature of> 70 ° C, and to extract them, the solution should be cooled to ~ 30 ° C. Thus, it is only in the main circulation circuit that the entire mass of the washing solution needs to be quickly heated from ~ 25 to 75 ° C, fed to the sink, then cooled from 75 to ~ 25 ° C, sent for extraction, and then separated from the extract and heated again, to reuse. To regenerate the extractant in the second circulation circuit, it will be necessary to significantly complicate the technological scheme, add a few more devices, and increase the already record-breaking energy consumption. All this significantly increases the capital and operating costs of cleaning and allows you to characterize the method as unpromising.

There is also a method of cleaning the surface of petroleum products (AS USSR No. 944685, IPC B08B 3/08, published in 1982). According to this method, surface cleaning is carried out with an aqueous solution of technical detergents (TMS) based on surface-active substances (surfactants) and electrolytes. Such a solution forms a stable emulsion with hydrocarbon contaminants. For regeneration of the washing solution, the emulsion is separated by electroflotation, after which the organic phase is removed and the aqueous solution is recycled for reuse. These processes make up the main circuit in which the entire mass of the washing solution circulates. The specified processing method allows to provide the required degree of surface cleaning and to use the washing solution repeatedly. However, the separation of a stable emulsion is a very difficult task, the solution of which, as a rule, is accompanied by the appearance of new unsolved problems. So, during electroflotation, the corrosive wear of equipment is significantly accelerated, the electrodes are passivated, there is a problem of gas separation, room ventilation. For preliminary electrocoagulation, the costs of materials and electricity are necessary. The equipment of the installation will need to be made of acid-resistant material. In addition, for processing the entire mass of the washing solution, large-capacity large-capacity devices will be required. In particular, to capture water vapor containing not only hydrocarbons, but also hydrogen, it will be necessary to significantly increase the heat transfer surface of the capacitors.

A known method of washing tanks and extracting residual liquid, which includes aspirating and / or pumping out residual liquid, supplying a washing solution to the tank, separating an oil-water mixture with an inert gas supply (flotation) to separate the oil component (RF patent No. 2099156, IPC B08B 9 / 08, priority date 09/23/1993, published on 06/17/1993). The disadvantages of this method: the irreversible loss of expensive inert gas, each of the operations on a separate vehicle, the large overall dimensions of the apparatus, for example, a vapor condenser, greatly diluted with air.

Known methods for cleaning the surface from oil pollution using a coagulant and various depressants, which use additives containing polymers and a hydrocarbon solvent (RF patent No. 2109583, IPC B08B 9/08, priority date 12.03.1997, published 04/27/1998) or an aqueous mixture of hydrocarbons and salts containing nitrogen, phosphorus and potassium, followed by surface treatment with hot water or hot steam (RF patent No. 2104103, IPC B09C 1/10, priority date from 05.21.1996, published in 1998) . The disadvantages of these methods, in addition to those noted earlier, are the high consumption of reagents and heat (t> 95 ° C) and the complexity of the processes.

A known two-stage method of cleaning the surface of hydrocarbon contaminants, including (at the first stage) washing the surface with a heated aqueous solution of TMS, which includes a nonionic surfactant based on alkoxysilicate fatty alcohol 2-4 wt. % and soda ash - the rest, and at the second stage, rinsing the washed surface with clean water to remove residual soda and other components of the washing solution (RF patent No. 2200637, IPC B08B 3/08, priority date 04/23/2001, published in 2003 ) An essential feature of this method is the use of a thin-layer sump for efficient phase separation and maintaining a certain composition of the washing solution with a TMS concentration of 1.5-4 wt. % The specified method is successfully used for internal equipment washing, the contaminated washing solution in a thin-layer sump is completely separated and the purified aqueous solution is sent for reuse completely, there is no discharge of contaminated wastewater. However, the considered method has a number of significant disadvantages. To ensure the required completeness of separation of the entire mass of contaminated washing solution, large-capacity separation equipment is required, and to maintain good washing and demulsifying ability of the solution, unreasonably high costs of TMS and surfactant are required. The issues of trapping oily vapors are not resolved.

Closest to the claimed invention and adopted as a prototype "Method for cleaning the surface of hydrocarbon contamination" (RF patent No. 2262396, IPC B08B 3/02, priority date 02/09/2004, published on 10/20/2005). The specified method consists in two-stage jet cleaning:

- (first stage) for rapid heating and removal of the bulk of hydrocarbon contaminants, a multiphase, multicomponent mixture formed as a result of the previous cleaning is used as a working fluid, where water is used as a dispersion medium, the losses of which are with steam separated by an irrigated hydrocarbon layer and the quantity removed flooded sludge make up;

- (the second stage), the finishing treatment is carried out by a circulating and pre-cleaned of trapped contaminants detergent agent, which is used as water or an aqueous solution of surface-active substances, part of the detergent agent is sent to compensate for water losses in the working fluid as its quality decreases (first stage ), and in return add the appropriate amount of freshly prepared aqueous solution or pure water;

- the part of the flooded hydrocarbon layer separated in the first stage in a separate sump is separated into the water and hydrocarbon layers, the aqueous layer is recycled to replenish the working fluid (first stage), and the separated hydrocarbon layer is sent for disposal.

Other features of the prototype relate to the preparation and maintenance of the required condition of the washing solution for the second stage of processing, as well as the removal and washing of the sludge extracted during washing. All these issues in this application we do not consider for the following reasons:

1. Mechanical impurities are almost completely absent in the transported and used commercial oil products (the same applies to commercial oil and fat products), therefore, in most cases there is no need to separate and process sludge.

2. Industrial water used for the preparation of washing solutions contains a sufficient amount of salts, which prevents the stabilization of water-hydrocarbon emulsions formed during washing.

With the obvious advantages of the prototype, it has significant disadvantages: a rather complicated technological scheme and unreasonably high energy costs associated with the consumption of reagents and the circulation of a fairly large amount of water, not only at the second stage of processing, but also at the first, where, in accordance with the formula, the presence of in the working fluid of an aqueous dispersion medium.

But water, as a component of the working fluid at the first stage of processing, is necessary only for phlegmatization of flushing products that can ignite. For this, it is not necessary that there is more water in the working fluid than there are hydrocarbons. It is known that even separated high-viscosity oil products contain more than 40% of water, not counting emulsified. Such a water content is sufficient to exclude the possibility of ignition of vapors at the temperature of use of the working fluid. And since at the first stage of processing we seek to remove the bulk of hydrocarbon contaminants, it is quite advisable to use an emulsion of water in hydrocarbons for this purpose. Why? Firstly, it is no less effective, since a non-polar solvent more easily destroys impurities even hardened ones, and with a sufficient pressure of the jet, its flushing rate can be reduced, and the presence of water very significantly reduces the viscosity of hydrocarbons, which makes it possible to use even flooded black oil for jet washing. Secondly, it is more economical, since the total consumption of water for processing is reduced by 3-5 times (compare the compositions of the forward and reverse emulsions). The result is a significant reduction in total energy consumption.

At the finishing stage (second stage), it is also not necessary to use clean water and detergent solutions of a specially selected composition, if a sufficient pressure of the jet is ensured and it gets on each of the sections of the washed surface. The presence of a small amount of emulsified hydrocarbons in water does not affect the quality of treatment in any way, since at a high speed of blasting the contact of particles of the dispersed phase with the washed surface and the separation of the emulsion are simultaneously excluded.

The technical problem, the solution of which the invention is directed, is to simplify the technological scheme of cleaning and reduce the overall processing costs.

The essence of the proposed solution lies in the fact that a two-stage method for cleaning the surface of hydrocarbon contaminants includes:

the first stage, which consists in feeding the working fluid in the form of a jet to the surface to be treated and removing the washing products from the treatment zone,

the second stage, which consists in rinsing the washed surface with a second working fluid and removing the washing products.

The washing products from both stages of processing are diverted to a separator for coarse separation into three layers: hydrocarbon, water and emulsion, where both types of emulsions are presented (direct and reverse), dehydration of part of the hydrocarbon layer with the return of the extracted water to recycling to make up for losses and return at least parts of two other layers for reuse.

The collection of washing products at the first and second stages is carried out in one collector-separator, where they are continuously coarsely divided into hydrocarbon, water and emulsion layers. At the first stage of processing, an emulsion layer is used as a working medium, where both types of emulsion are presented (direct and reverse). Finishing (the second stage) is carried out with an aqueous layer of products of the previous cleaning.

At least part of the products of the previous stripping in the form of a hydrocarbon layer is sent to a dewatering station (for example, according to RF patent No. 23237504, BI No. 18, 2008, priority dated 08/31/2006), where water is separated from it (for example, according to RF patent No. 2315803, BI No. 3, 2008, priority dated 11/07/2005) and return it to make up for the loss of the water layer used for finishing, and dehydrated hydrocarbons are sold as a commercial product.

The proposed method allows, while maintaining the quality of surface cleaning, to significantly simplify the technological scheme (by eliminating equipment designed for the special preparation of working fluids and washing the extracted sludge), as well as significantly reduce the cost of energy resources for processing. Indeed, the return to reuse of water separated in the process of dehydration of the hydrocarbon layer, allows you to almost completely stop the consumption of natural water previously spent on the preparation of working bodies.

The essence of the invention is illustrated by the drawing, where in FIG. presents a schematic diagram explaining the essence of the proposed method.

The diagram shows:

1 - processed capacity; 2 and 3 - washing machines; 4 - collector-separator washing products; 5 and 6 - pressure pumps; 7 - heater working fluid 1; 8 - heater working fluid 2; 9 - vapor condenser; 10 - air; 11 - hydrocarbon dehydration station, for example, according to the patent of the Russian Federation No. 23237504 (BI No. 18, 2008, priority from 08.31.2006).

Cleaning the inner surface of the processed tank 1 proceeds as follows. At the first stage of processing, through the nozzles of the washing machine 2, rotating or oscillating according to a special program, from the middle part of the separator 4 the pump 5 serves the working fluid I, which is an emulsion layer heated in the heater 7, which was formed as a result of the separation of the products of the previous washing. Washing products are returned to the separator 4, where they are roughly divided into three layers: upper (hydrocarbon), lower (water) and emulsion, which includes both types of emulsion (direct and reverse).

When the bulk of the hydrocarbon contaminants from the tank 1 is removed, proceed to the second stage of processing - final washing (rinsing). For this, through the nozzles of another washing machine 3, a pump 6 from the lower part of the separator 4 is fed with a working fluid II, which is a water layer heated in a heater 8, which was formed as a result of the separation of the products of the previous washing. This ensures the necessary pressure, and the rotation of the washer 3 is carried out according to a special program that ensures that the jet enters each of the sections of the washed surface. Finishing products are also returned to the separator 4 for coarse separation.

Part of the upper layer (waterlogged hydrocarbons) is sent to dehydration station 11, corresponding, for example, to RF patent No. 23237504, where water is separated from it, for example, in accordance with RF patent No. 2315803 (BI No. 3, 2008), and returned to it for replenishment water loss in the collection 3, closing the recycling. And dehydrated hydrocarbons are sold as a commercial product.

Processing according to the described scheme has several advantages:

1. For the collection and rough separation of washing products from the first and second stages, one collector-separator is used, which greatly simplifies the technological scheme and reduces the number of units of equipment used.

2. Finishing with an aqueous layer that does not require additional preparation allows you to avoid the additional costs associated with the preparation and subsequent regeneration of the components of the washing solutions, as well as significantly reduce production volumes.

Some features of the method in terms of feasibility were tested at two universal mobile washing stations (UMPS), operated in a car depot at the station. Pskov and Art. Morozovskaya. So, the processing time of tanks from under highly viscous petroleum products (fuel oil, paraffins, sour grades of oil, etc.) according to a two-stage processing scheme at st. Morozovskaya decreased from 60-90 to 30-40 minutes, as a result, the throughput of UMPS increased and the specific energy consumption decreased. At the same time, the quality of cleaning the walls of the tanks did not decrease.

The claimed technical solutions were tested in the laboratory and in pilot plants (A. Evdokimov. Cleaning of oil and oil transportation equipment. Problems and solutions. // Ecology and Industry of Russia. No. 2, 2010, p. 7-9; Ioffe OB , Evdokimov A.A. Test results of a pilot plant for the dehydration of viscous oil products // Ecology and Industry of Russia. No. 2, 2010, pp. 22-25).

Thus, the inventive method, solving the main problem (washing the surface from contaminants), can significantly simplify the process flow and significantly reduce the overall processing costs.

Claims (1)

A two-stage method of cleaning the surface from contamination with oil products, including the first stage, which consists in feeding the working fluid in the form of a jet to the surface to be treated and removing washing products from the treatment zone, the second stage, which consists in rinsing the washed surface with the second working fluid and removing rinsing products, characterized in that the products of washing and rinsing from both stages of processing are diverted to a separator for rough separation into hydrocarbon, water and emulsion layers, while an emulsion layer containing direct and reverse emulsions is used as a working fluid at the first processing stage, an aqueous layer is used as a working fluid at the second processing stage, and a part of the hydrocarbon layer is sent to a dewatering station to separate water from it and return it to make up for losses water layer, and dehydrated hydrocarbons are sold as a commercial product.

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