MXPA97003815A - Apparatus for the purification of water contaminadacon petro - Google Patents

Abstract

The present invention relates to an installation for cleaning water contaminated with oil, in particular oil and gas production plants, it is provided with a distillation column (20) having contaminated water supply (21) and at least one packing contact (23) above which the outlet of the contaminated water supply is located, a steam discharge (39) and a clean water outlet (27), and a measuring device (33, 34) for the analysis of the Water from the water outlet limp

Description

APPARATUS FOR THE PURIFICATION OF PETROLEUM CONTAMINATED WATER DESCRIPTION OF THE INVENTION The invention relates to an installation for cleaning water contaminated with oil, in particular near gas and oil production plants. Currently, coastal and onshore production platforms use facilities such as suckers, flotation units, hydrocyclones, centrifuges, etc., to separate dispersed oil from production water released during oil and gas production. These installers are usually not able to continuously decrease the concentration of oil in the water to approximately 40 ppm. This limit of 40 ppm is the maximum value allowed by many authorities. It is the object of the invention to provide an installation of the type mentioned in the preamble, by which not only can a high standard of cleanliness be achieved, but also because this cleaning is achieved in an efficient form of high energy and therefore also automatic control is possible. For this purpose, the installation according to the invention is characterized by a distillation column, which comprises contaminated water supply and at least one contact packing above which leaves the contaminated water supply, a steam discharge and a clean water outlet; and a measuring device for water analysis of the clean water outlet. By means of the energy-efficiency separation of the distillation column a higher percentage of aromatic and aliphatic compounds of water is achieved; in this way fulfilling high cleaning requirements. Currently the continuous line equipment is available for measurement. In this way, the oil content in the water can be measured continuously instead of 16 times a month, as is now required by many authorities. By means of certain types of analytical devices, the content of aliphatic and aromatic compounds in clean water can be measured separately or combined. In addition, the output signals of both devices can be continuously transmitted to a central platform. The operation of the cleaning facility can therefore be monitored and controlled from a distance. Helicopter flights to the various production platforms without personnel, to take samples for laboratory analysis, as is the case with known coastal facilities, therefore they are no longer necessary. The weekly or monthly calibration of the measuring device according to the invention is sufficient. The distillation column is preferably provided with internal or external heating means as well as means for the generation of a controlled underpressure in the distillation column. The applied internal heating means can, for example, be electric heating. However, sometimes the application of external heating means may be more advantageous; for example, if the gas is released in the platform, it can be used for heating by means of a separate boiler. The installation according to the invention is capable of effectively separating the oil from the water, so that the heating means and the means that decreases the pressure together perform at least the partial evaporation of the contaminated water, leading to the optimum separation. In addition, the underpressure lowers the boiling point of the volatile hydrocarbon components, such that, for example, in the distillation column, instead of heating to the boiling point of water, a much lower temperature in the range of 40-60 ° C and in some applications even smaller, it is enough. For some organic components the separation factor is substantially improved, if the separation is carried out at decreased pressure and temperature. Because many organic compounds have boiling points below that of water, most organic compounds will be concentrated in the vapor phase. However, since many organic compounds together with water form azeotropic compounds, heavy organic compounds with boiling points greater than water will also leave the column in the vapor phase. In this way, most of the organic compounds in the contaminated water supply will be eliminated without all the water having to evaporate. The object of the invention is still to evaporate less than 20% of the water that enters. Under certain conditions, even only 5% evaporation is possible. Due to the packing, there is a large contact surface between the fluid and the vapor phase. This ensures that the water flowing downward, in counterflow to the rising steam, will be cleaned substantially, in a very efficient manner, so that the outlet of the clean water can be directly connected to the bottom of the distillation column . After, cleaning is usually unnecessary; however, a subsequent cleaner in the form of a UV light oxidation unit can be incorporated in the outlet of the clean water, which will then be placed before the measuring device. Furthermore, according to the invention a pre-cleaning plant can be incorporated in the contaminated water supply to supply the distillation column with water from which the dust particles and part of the oil have been removed, in such a way that the distillation column is a little less heavily loaded.

The invention in the following will be clarified by means of the drawings illustrating three modalities of the installation according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS Figures 1, 2 and 3 are process diagrams of three modalities of an installation for cleaning water contaminated with oil according to the invention. In the different modalities, the comparable parts are indicated by the same reference number. Figure 1 shows a first embodiment of the installation according to the invention. In 1 the contaminated water arrives from a collection tank (not shown) and is collected in a contaminated water tank 2. With the help of a pump 4 provided in line 3, the contaminated water is taken to a pre-treatment unit 5. -separation, where either mechanically or hydraulically the solid particles and possibly the oil are separated from the water. This pre-separation unit can take the form of a filter, a hydrocyclone, a centrifuge or a screen separator or the like. Such a pre-separation unit can already considerably reduce the amount of contamination. With the help of pump 6, the separated oil phase is transported via pipe 7 to a tank 8 for dirty oil. With the help of the pump 9, the clean water is drained away from the pre-separation unit 5 by means of the pipe 10, and the oil content in the water of the pipe 10 is measured by means of an analysis facility 11. If the oil content in the water exceeds a predetermined level, then the production water is, by means of a pipe 13, carried back to the contaminated water tank 2 by means of a three-way valve 12, controlled by the analysis facility 11. If the oil content in the water remains below the predetermined limit, then the water is further pumped via the three-way valve 12 through the pipe 10 to an intermediate storage tank 14. A pipe 15 provided with a pump 16 for pumping in the pre-treated production water is connected to the intermediate storage tank 14. The pipe 15 is finally connected to a pipe 17, on the supply side 1 8 from which the seawater can be supplied, which by means of a pump 19 can be pumped to the outlet side of the pipe 17. The outlet side of this pipe 17, by means of which optionally seawater fresh (in the case of a coastal installation) for the purpose of starting the complete installation or pre-treated production water from the pipeline 15 may be drained away, the ends in the distillation column 20, which is the heart of the installation. The outlet side of the pipe 17 is provided with an upper sprinkler 21 which distributes the water supplied to the distillation column 20, whose water is preferably sprayed onto a fluid distributor 22, such as a grate or a perforated plate, for promote a uniform distribution of moisture. Under the fluid distributor 22 a gasket 23 of known construction is provided, whose packing serves to provide a very large contact area in a small space. The fluid distributor ensures that the gasket 23 is wetted even better. The pressure prevailing in the distillation column 20 is preferably a vacuum to achieve the evaporation of the components contained in the production of supplied water without needing a considerable increase in temperature by means, in this case, of an electric heating installation 24 near the bottom of the distillation column 20. Most organic compounds will be concentrated in the vapor phase because the boiling point of many organic compounds is lower than that of water. However, many organic compounds together with water form azeotropic compounds, such that heavy organic compounds that have boiling points greater than water, they will also leave the distillation column 20 in the vapor phase. In this way most of the organic compounds present in the water of production supplied, will be eliminated without evaporation of too much water. The purpose is that the water itself in less than 20% and preferably only 5% is evaporated. This decreases the considerable energy consumption. Water that does not evaporate and from which most of the organic compounds are removed will be collected at the bottom of the distillation column 20. The electric heating installation is located below the surface of this collected water and controls of level 25 ensure that the water level of the bottom of the distillation column 20 remains within certain limits when controlling a pump 26 in an outlet pipe 27 or a valve 54 therein. The outlet pipe 27 further comprises a heat exchanger 28 through which, in a separate pipe system, the pre-cleaned water from the pipe 15 flows, to preheat the pre-clean water 15 with the help of the water which is heated in the distillation column 20. From the outlet pipe 27, clean water flows into the tank 29. A pipe 31 provided with a pump 30 is connected to the tank 29, to pump the clean water to a post-cleaning installation optional and usually superfluous, which in this case consists of a unit 32 of oxidation by UV light. This unit of oxidation by UV light removes any of the remaining aromatic compounds in the water. Before the water coming from this oxidation unit 32 is actually discharged, the content of aliphatic and aromatic compounds is measured in the analysis facility 33 for aliphatic compounds and in the analysis facility 34 for aromatic compounds. These analysis facilities 33 and 34 constantly monitor the contents of aliphatic and aromatic materials allowing them, with the help of the three-way valve to be controlled by them, to determine if sufficiently clean water is discharged at 37 by means of pipe 36 inside. , for example from the sea or if it is not clean enough, it is returned by means of a pipe 38 to an intermediary tank 14 for the pre-cleaned water to be portrayed in the distillation column 20. The complete installation can be monitored and controlled from a distance because the output signals from the analysis facilities 33 and 34 can be sent to a central control platform. Returning to the distillation column 20, the drawing further shows that the steam rises vertically upwards, in this way in counterflow with the water flowing downwards and therefore establishing a good contact, can be discharged at the top of the column. the distillation column 20 with the aid of a vapor discharge pipe 39 comprising a vacuum pump 40 for generating the underpressure in the distillation column 20 and for extracting the steam through the vapor discharge pipe 39. The Vapor discharged from the vacuum pump 40 is in most cases very hot and can be used in the heat exchanger 41 to preheat additionally the pre-cleaned production water flowing through the pipe 15 and the exchanger heat 41. The low-cooled steam is sufficiently condensed by the cooling medium in a cooling installation 42, whereby the condensate is divided into two phases, for example, in an organic phase and a water phase. The two phases are then separated in a two-phase separator 43, such as a settler or a hydrocyclone, a centrifuge, a settling plant or the like. With the help of a pump 44, the organic phase is then drained by separating it by means of a pipe 45 to a tank 8 for dirty oil. The pump 47 pumps the water phase through the pipe 46 to the pipe 15 to be returned to the distillation column 20. Of course, as is usual with such installations, all types of safety stipulations (not shown here) They are provided. However, Figure 1 shows that all tanks (2, 8, 14 and 29) are provided with level 48 controls which, when the level in a particular tank is too high, will open a corresponding overfill pipe 49 for Allow the excess fluid flow to move 50 to the collection tank for the production water The fluid collected in tank 8 as dirty oil is during normal operation, drained by means of pipe 51 and in oil 52 dirty is either taken to a special tank in which the oil is collected for another treatment or drained, or is returned to the production process Figure 2 shows a slightly adapted variant of the installation according to Figure 1. In this variant, the installation column 20 is provided with two gaskets 23 and 23A, in which the sprinkler element 21 for the production of pre-cleaned water and the fresh sea water discharges above the lower gasket 23, while a sprinkler element 53, attached to the end of the pipe 46, discharges above the upper packing 23A by returning the water phase of the two phase separator directly into the distillation column 20 and preferably in a fluid distributor 22A such like a grid or a perforated plate. In this way, the returned water is brought through a heat exchanger 41 and thus overheated. It will be obvious that, depending on the application, the distillation column 20 can be provided with even more packages 23, 23A and fluid distributors 22, 22A. It is also possible in certain applications, where the production water does not contain too many particles of dust or oil, to omit the pre-separation installation and to carry out the production of water directly in the distillation column 20. Other additions or omissions They are also conceivable. This is illustrated in Figure 3, which shows an alternative embodiment of the installation according to the invention, in which the number of installation parts applied is considerably reduced. In reference number 1 the contaminated water arrives at the installation from a production platform and is received in the contaminated water tank 2. From this tank 2, the contaminated water is carried by means of pipe 3 through a filter 5 for the removal of the solid particles, whereby the transport energy for transporting the contaminated water is provided by the pump 16. To be heated the contaminated water is taken through a heat exchanger 28 and furthermore by means of the pipe 15 to a sprinkler element 21 in the distillation column 20. The heat exchanger 28, on the other hand, is fed with heated clean water, which is obtained from the distillation column 20 by means of the pipe 27 by means of a pump 26 and is carried to the tank 29, from which by means of the pump 30, the clean water is taken to the analysis facilities 33 and 34 to measure the content of aliphatic compounds and romatics The contaminated water which is carried in the distillation column 20 by means of the sprinkler element 21, is sprayed onto a fluid distributor 22, under which a packing 23 is provided where the intense interaction is obtained between the contaminated water and the fraction steam generated in the distillation column 20. This vapor fraction is obtained with the help of the heating means 24 placed outside the distillation column 20 and comprises a boiler fed with electricity or gas and which serves to heat clean water from the distillation column 20, whose water leaves it in the lower part by means of the pipe 27 and is returned, after passing the heating means 24, to the distillation column 20 under the packing 23. The steam fraction it leaves the distillation column 20 in the upper part by means of the pipe 39 and is carried through a condenser 42, where this vapor fraction is condensed and divided into two phases. is, for example, an organic phase and a water phase. The two phases are subsequently separated into a two-phase separator 43, for example in a settler, to which a vacuum pump 40 is connected to provide both of the underpressure in the distillation column 20 and to implement the transport of the fraction of steam. It is preferable to place the vacuum pump 40 after the two-phase separator 43 instead of the pipe 39 immediately after the distillation column 20, because the pump 40 can be much smaller, so that an substantial savings in spending. The fraction of oil separated in the separator 43 of two phases is transported by means of a pump 44 to a tank 8. The aqueous fraction, which may still contain petroleum particles, is returned by means of a pump 47 to the water tank contaminated 2 by means of a pipe 46, which is connected to the two-phase separator 43. The foregoing shows that the invention provides an installation which, by means of relatively simple equipment achieves very good cleaning of the production water, in such a way that clean water can be discharged directly. Of course, the installation according to the invention is not only useful with the production of gas and oil at sea, but also with similar production on land. The installation can also be adapted for use with different ordinary installations on land for the separation of oil and water. The invention is not limited to the modalities shown in the drawings and described in the examples of the modality, which may be varied in different ways without departing from the scope of the invention as specified in the appended claims.

Claims (16)

1. CLAIMS 1. An installation for cleaning water contaminated with oil, in particular in oil and gas production plants, characterized by a distillation column that has contaminated water supply and at least one contact packing above which the exit of the contaminated water supply is located, a steam discharge and a clean water outlet; and a measuring device for water analysis of the clean water outlet. The installation according to claim 1, characterized in that the distillation column is provided with internal or external heating means. 3. The installation according to claim 2, characterized in that the external heating means is a boiler, which is connected for the supply as well as for the reception with the distillation column. The installation according to any of claims 1-3, characterized in that the contaminated water supply in the distillation column is discharged by means of a spray element, preferably above a fluid distributor, such as a perforated plate. 5. The installation according to any of the preceding claims, characterized in that - the steam discharge comprises a cooling installation, a two-phase separator and a return of water. The installation according to any of the preceding claims, provided with means for the generation of a controlled underpressure in the distillation column. The installation according to claim 6, characterized in that the means for establishing a controlled underpressure in the distillation column are provided downstream of the two-phase separator. The installation according to any of the preceding claims, characterized in that the discharge of steam and the supply of contaminated water and / or the exit of clean water and the contaminated water fed and / or the discharge of steam and the return of water they are allowed to pass each other in a heat exchanger. 9. The installation according to any of claims 4-8, characterized in that the return of water is discharged into the contaminated water supply. The installation according to any of claims 4-8, characterized in that the return of the water is discharged into the distillation column by means of another sprinkler element, preferably above the sprinkler element of the contaminated water supply and another packaging located above it. 11. The installation according to any of claims 4-8, characterized in that the return of water is discharged into a contaminated water tank, which, during operation, feeds the contaminated water supply. The installation according to any of the preceding claims, characterized in that the clean water outlet is connected to the bottom of the distillation column. The installation according to any of the preceding claims, characterized in that the clean water outlet is provided with a UV light oxidation unit after the cleaner, which is located before the measuring installation. The installation according to any of the preceding claims, characterized in that the contaminated water supply is provided with a pre-separation facility. 15. The installation according to any of the preceding claims, characterized in that the measuring device comprises an analyzer for aliphatic compounds and an analyzer for aromatic compounds and sends signals to a control room located at a distance. 16. The installation according to any of the preceding claims, characterized in that during the operation, the discharge of steam is discharged from the distillation column to a maximum of 20% and preferably a maximum of 5% of the water fed in this column distillation by feeding contaminated water.