MXPA98009593A - Purification and filtration of liquid and - Google Patents

Abstract

A material is disclosed comprising a base substantially formed of cellulose fibers on which a composition comprising one or more aliphatic carboxylic acids having hydrocarbon chains consisting of 8 to 20 carbon atoms, and a filter material comprising a matrix is absorbed. in which a granular formulation of this material is dispersed, the material can be used to adsorb hydrocarbon contaminants such as oil spills, and the filter material can be used to adsorb such contaminants from a stream of fluids.

Description

PURIFICATION AND FILTRATION OF LIQUID AND GAS DESCRIPTIVE MEMORY The present invention relates to the removal of organic materials and other contaminants from liquids and gases »and in particular, but not exclusively» to the removal of said contaminants by means of a filtration system. Several strategies have been developed in the petrochemical industry to deal with problems such as oil spills and leaks, particularly towards the sea. Some methods, for example the use of detergents, simply help to disperse the oil spill as soon as possible before it has done too much damage. However, it is preferable to remove the oil from the water without dispersing it, since there are many toxic components in the oil that can cause damage to the environment. It is known how to provide a granular material based on cellulose, which has oil absorbing properties, the material being in a suitable form to be sprayed on an oil spill. Once the oil is absorbed, the material accumulates and can be incinerated. Oil spills are not the only environmental problem facing the petrochemical industry. There are many situations in which it is convenient to remove components that include organic pollutants (such as hydrocarbons) and heavy metal water contaminants. produced and drainage water »before this water is released as an effluent. It is also convenient to remove said contaminants from other liquids other than water, and also from gases 5 (e.g., air). According to a first aspect of the present invention, there is provided a filter material comprising a matrix in which a granular formulation of a material comprising a base formed substantially of O cellulose fibers is dispersed, on which is adsorbed a composition comprising one or more aliphatic carboxylic acids having hydrocarbon chains consisting of 8 to 20 carbon atoms. In preferred embodiments, the chains of : L5 hydrocarbon acid or carboxylic acids consist of to 18 carbon atoms. It has been found that particularly effective carboxylic acids include stearic acid CH3 (CHß): LßCOOH, and palmitic acid CH3 (CHa) _ «COOH. According to a second aspect of this invention, a method of producing a material comprising a base substantially comprised of cellulose fibers on which a composition comprising one or more aliphatic carboxylic acids having hydrocarbon chains is adsorbed is adsorbed. which consist of B to 20 atoms of 5 carbon, wherein one or more of the cellulosic materials are combined together with a pulverized formulation of the acid or carboxylic acids. The granular material of the first aspect of the present invention can be formed by mixing together one or more cellulosic materials, for example virgin pulp and wood chips, together with one or more carboxylic acids in the form of powder and, optionally, latex. The mixing is preferably carried out in a hammer mill, in which heat and friction aid the process, whereby the carboxylic acid is adsorbed on the cellulose fibers. It is believed that the carboxylic acids are adsorbed on the surface of cellulose fibers by means of the carboxyl -COOH functional group, either by hydrogen bonds or by the formation of cellulose esters containing a -O-CO-R group formed with the hydroxyl groups -OH on the cellulose rings. However, carboxylic acids bind to cellulose fibers. The result is that the material of the first aspect of the present invention comprises cellulose fibers from which it projects hydrophobic hydrocarbon chains. When the material is applied to a mixture of water and hydrocarbon contaminants, the hydrophobic hydrocarbon tails of the carboxylic acid residues serve to attract hydrocarbon contaminants to the material and to repel water, thus producing the required separation. Then, the material, which incorporates the hydrocarbon contaminants, can be concentrated and used as a fuel supply.

The matrix of the first aspect of the invention can be made of various materials, including nonwoven fibrous materials, open cell foam materials or a cotton or viscose gauze. The unloaded matrix conveniently has a density not greater than 0.25 gcm-3, and preferably from O. OI to 0.18 gcm-2 ». A particularly preferred matrix has a thickness of about 3mm and a density in the region of 0.1 gc -3. The granular formulation of the material of the first aspect of the present invention can be incorporated into the matrix by means of bombardment through a pressure gradient as described in EP 0 504214, the description of which is incorporated by reference in the present application. By incorporating the material of the first aspect of the present invention into a matrix to form a filter material, the available active surface area is increased »in such a way as to add efficiency. In addition »the dispersion of the material in the contaminated fluid is reduced because it is kept inside the matrix. In some embodiments, bands of the filter matrix are loaded at a density of about 1 kgm-58; it has been found that a density of .925 kg -52 is particularly effective under certain circumstances. In other embodiments, it has been found that a density of about 0.5 Kgm-58 is effective, particularly when the band of the filter matrix has a thickness in the region of 3 or 4 mm. Once the filter material has become saturated with contaminants, it is relatively simple to remove the filter and replace it with one new. The filter material can support twice its own weight in hydrocarbons and is therefore useful as a source of energy »for example, in cement kilns. In some situations, the used filter material can be macerated in a form that can be fluidized and injected into ovens as a fuel supply. The filter material can be cut into such forms or discs suitable for installation in filtering apparatuses. Particularly preferred is a filter column comprising a hollow core on which an alternating stack of filter plates and discs of the filter material of the third aspect of the present invention is mounted, wherein the filter plates are adapted to allow the passage of fluid from a circumferential region of the filter column to the hollow core by means of discs of iltro material. Alternatively, filter cartridges can be constructed by winding layers of the filter material around a central core. For example, a cylindrical cartridge can be made to a perforated tubular core by winding it with layers of the filter material, giving a protective outer layer that allows the passage of fluid in or out of the cartridge, and securing everything with a pair of filters. end caps. Fluid can be passed through the filter material in the cartridge either from the central core to the outside "or from the outside towards the central core. One or more of these filter cartridges can conveniently be installed in a filter receptacle comprising a cover internally divided into two chambers by a carrier supporting at least one filter cartridge; the carrier and the cartridge (at least one) are arranged in such a way that only fluid can pass from one chamber to the other "passing through both the hollow tubular core and the filter material of the cartridge (at least one). It is also possible to directly fill the filter cartridges mentioned above with the material of the first aspect of the present invention without using a filter matrix. According to a fourth aspect of the present invention, "a method of cleaning a fluid" is provided by contacting the fluid with a material comprising a substantially formed base of cellulose fibers on which a composition comprising one is adsorbed. or more aliphatic carboxylic acids having hydrocarbon chains consisting of 8 to 20 carbon atoms "wherein one or more cellulosic materials are mixed together with a pulverized formulation of the carboxylic acid or acids. Fluids that can be cleaned by this method include gases such as air and liquids such as water. The material may be in loose form such as a material according to the first aspect of the present invention; or the material can be bound in a matrix »according to the third aspect of the present invention. For a better understanding of the present invention, and to show how it can be carried out, reference will now be made, by way of example, to the accompanying drawings »in which: Figure 1 shows a section through a filter rig at yard scale »which incorporates the material of the first aspect of the present invention. Figure 2 is a schematic view of a filter column incorporating the filter material of the third aspect of the present invention. Figure 3 shows a detail of a filter plate of figure 2. Figure 4 shows a test circuit including a filter column similar to that of figure 2. Figure 5 shows a filter cartridge incorporating the material of the third aspect of the present invention. Figure 6 shows a receptacle q- incorporating an arrangement of the filter cartridges of Figure 5. Figure 7 is a section through the receptacle of Figure 6. Figure 8 shows a filter shoe incorporating two of the receptacles of Figures 6 and 7. Figure 9 shows a filter shoe incorporating eight of the receptacles of figures 6 and 7; and Figure 10 is a graph showing the trends of flow / contamination data against the intervention periods for an eight-receptacle filter skate. 5 Initial small-scale tests The results of small-scale laboratory analysis of a material in accordance with the first aspect of the present invention will be described first, the differential pressure 10 was measured through columns of the material made from different types of materials. cellulose to calibrate the permeability and porosity characteristics of various substrates.The preferred grade showed no increase in differential pressure after 40 days of flow.

Particularly suitable for wood chips in shavings of a soft wood with an average particle size of 30 mm. Hydrocarbon filtration tests at laboratory scale confirmed the petroleum removal properties of the material. Below are two examples of the tests.

EXAMPLE 1 Dissolved hydrocarbons removed by column packed with 12 cr of material -i-i 575 ml of Inde K condensate was added to 10 liters of artificially formed water (Brent's formula) and stirred vigorously using a homogenizer. Separated samples were then drained from a liter, retaining 100 ml of each for triple peak analysis to measure the content of dissolved hydrocarbon before filtration "and adding the remainder to a one liter separatory funnel mounted on top of the column. The triple peak analysis was performed in the filtered water to obtain before and after figures. The results are shown in table 1: TABLE 1 the EXAMPLE 2 Treatment of dry salt contaminated with hydrocarbons from a desalination plant Salts were rehydrated by adding O.3 kg of salt to 1 liter of pure water and passed through 12 g of material at the rate of 1 liter / minute. The results are shown in tables 2 and 3.

OR TABLE 2 TABLE 3 0 , - > This small-scale analysis served to identify the physical nature of the substrate that retained the permeability for long periods »absorbed high levels of hydrocarbons and was incinerable. Therefore, you can start now with larger tests at the yard scale.

Filtration tests through a yard-scale filter Figure 1 shows a yard-scale rig that is used in the following analysis. The rig comprises a pump (1) that pumps polluted water by means of a current meter (2) to a diffuser (3) mounted on a filtration bed (4) provided with a quantity of the material (5) in accordance with the first aspect of the present invention. The filter bed (4) is located inside the receptacle (6), from which the filtered water is passed through a sample valve (7) to a discharge (S).

»EXAMPLE 3 Real water produced from the Sean Papa platform was supplied and lots of lOOO liters were filtered through 0.5 kg of material at 10 liters / minute. Samples were taken from each batch before and samples of filtered water were taken every 10 minutes. Typical results are shown in tables 4 and 5.

TABLE 4 TABLE 5 TABLE 5 Continuation In these two tests »the water had not been passed through any pre-filter or centrifugal coalescing agent» and therefore »the total hydrocarbon levels (26723-1409 pp) were higher than expected. However, in a single pass through the filter, the total hydrocarbon levels were reduced by an average of > 90% Specifically, the dissolved fraction decreased an average of 9254. Suspended solids were regularly 245 pp.

Formation of filter sheets Next, the use of the filter material of the third aspect of the present invention will be described. A granular formulation of a material according to a first aspect of the present invention is passed through a system that joins the loose product, for example to a gauze of viscose or cotton, producing a mat of 3 mm.

Thickness that can be cut into shapes (regularly disks) to fit the existing filter accessories. The process of forming such sheets increases the available surface area of the material, thereby improving performance. A long program of tests was carried out to measure the yield of production grade discs in a commercially viable filtration system. The disks were installed in a filter column of the type shown in Figure 2 »comprising an alternating stack of filter plates (9) and discs (10) of filter material, mounted on a hollow central core < 12 > »Being all compressed by an end plate (11) and placed in a suitable container (not shown). Figure 3 shows a filter plate (9) in greater detail. Contaminated fluid is applied to the filter column in such a way that it passes to the outer edge of each filter plate (9) and from there through an adjacent filter disc (10) before passing into the hollow central core (12). ) for extraction.

EXAMPLE 4 2000 liters of synthetic produced water were filtered with 22 ppm suspended solids (average size 2.5- 19 μ) through a disc filter column of the type shown in Figure 2 »loaded with 16 discs (10) of filter »taking samples before and after filtration. Two tests were run using two different flow rates »series I at 48 liters / minute» and series II at 10 liters / minute; the results are presented in tables 6 and 7, showing table 8 the analysis of the condensate provided.

TABLE 6 Series I - Removal of hydrocarbons 4B liters / minute TABLE 7 Series II- Removal of hydrocarbons liters / minute TABLE B Composition of the Condensate CHART below TABLE B Continuation In the following examples, the objective was to establish the time in which a given quantity of discs of filter material is saturated with hydrocarbons, and to continuously monitor the performance in hydrocarbon removal. These tests used online instruments for fluorescent hydrocarbon monitoring.

EXAMPLE 5 A 16 disc filter using a prototype grade of material according to the first aspect of the present invention was used to treat 50 ppm of condensate in water. This was done by homogenizing the oil in a static volume of water of 25 liters. A laboratory fluorometer recorded: Run 1: 93.5% removal at 5 liters / minute. Run 2: 96% removal at 5 liters / minute. Run 3: > 87% removal at 5 liters / minute. Changes were made to the means of dispersing the oil in water »as shown in the circuit of figure 4» comprising a pollutant metering pump (13), a seven-stage homogenizing pump (14), a filter column ( 15) and a deposit of samples (16) »where the deposit of samples <; 16) generates an overflow current and a monitored current »passing this current through a monitor (17) in line adapted to detect the presence of hydrocarbons by means of luorescence. Production-grade filter discs were manufactured for future testing for a reproducible commercial production formulation weighing 1000 g 58.

EXAMPLE 6 In this example, the column and filter disks of Example 5 were reused. The 16-disk filter was connected in line with a process monitor calibrated for the exact type of condensate. The stream contaminated with hydrocarbons was pumped through the 16-disc filter after dynamic mixing. Contaminants were injected into the water entering at a constant speed through a displacement pump positive directly towards the throat of the homogenizing pump. The outlet pressure was controlled at 6.86 kg / cma. Samples were taken for on-line analysis directly through the downstream current cell; Samples were taken for laboratory analysis before and after filtration. For the first continuous test, the condensate dosing was calibrated at 500 ppm in water with an average droplet size of < 10 μm. During the next two hours »the filter continued to remove > 90% of the condensate in the water supplied at a rate of 8 liters / minute. The test circuit shown in Figure 4 »proved to be a satisfactory system for future analyzes to test the efficiency and capacity of the filter. Production-grade filter discs were used in the following tests: EXAMPLE 7 A nominal condensate of 300 ppm in water was passed at 4 liters / minute through a new filter column; the results are presented in table 9.

TABLE 9 EXAMPLE B This was a repeat of the 300 ppm test at 4 liters / minute, but using new filter discs. This test was run for seven hours before showing signs of saturation; the results are presented in table 10.

TABLE 10 EXAMPLE 9 A nominal 500 ppm condensate was passed through the previous filter stack at the same volumetric flow rate to accelerate saturation; the results are presented in table 11. The filter column shows signs of failure.

TABLE 11 EXAMPLE 10 A nominal condensate of 500 ppm at 6 liters / minute was passed through the filter stack; the results are presented in table 12.

TABLE 12 EXAMPLE 11 Removal of glycol A larger filter housing was connected using 45.7 cm filter disks to the test rig shown in Figure 2. Glycol contaminated with hydrocarbons was supplied; this mixture was injected to the total stream of 14 liters / minute. This level of contamination is beyond the calibration scale of standard online monitor »but it was possible to use the 4-20 mA output for monitor changes in the input flow to the filter. Samples were taken by hand for analysis before and after filtration. The results are shown in the Table 13. Throughout the test »the filters operated at 1.19 kg / cma. The filter elements were online for 150 minutes.

TABLE 13 EXAMPLE 12 Removal of metals In this example, water was used with the following metal levels: Nickel: 1.75 ppm Copper: 0.50 ppm Zinc: 0.40 ppm Lead: 0.30 ppm »and the following was added to the water: Condensate: O.5 ppm Leman sediment: 50 ppm. Samples were taken before and after the filtration; the results are shown in table 14. The increase in the metal content of the pre-filtered water was attributed to the metals in the condensate and sediment.

TABLE 14 Formation of filter cartridges As an alternative to the disc filter column described above, a receptacle including one or more filter cartridges may be employed. As shown in Figure 5, a cartridge (18) is formed by winding filter material (19) around a tubular core (20) and applying a protective outer layer (21) and end caps (22). The outer protective layer (21) and the core < 20) are provided with perforations (23, 24) in such a way as to allow the passage of filtrate, either from the outside of the cartridge (18) through the filter material (19), to the interior of the core (20) (20) or vice versa. A typical cartridge (18) has a diameter of 215 mm, a length of 1300 mm and an internal diameter of 50 mm, and is provided with 10.98 kg of tightly wound sheet filter material, with a density of 0.925 kgm-1? .

EXAMPLE 13 Figures 6 and 7 show a receptacle (25) in which a filter cartridge arrangement (18) is mounted on a carrier (26). The carrier (26) is adapted to allow the entry of filtrate from the bottom (27) of the enclosure (25) to pass only towards the hollow cores (20) of the cartridges (18). The filtrate then passes through the filter material (19) and towards the upper part (28) of the receptacle (25) (which is separated from the bottom (27) of the receptacle (25) by the carrier (26)), from where it leaves the receptacle (25) by means of the outlet (29).

EXAMPLE 14 Figure B shows a filter shoe (30) comprising two filter receptacles (25) »and figure 9 shows a filter shoe (31) comprising eight filter receptacles (25). Figures B and 9 are not to scale. The receptacles (25) can be connected in series or in parallel in several configurations by means of alternative multiples of the connector pipe (32). A typical eight-receptacle skate (31) can accommodate speeds up to 120 m3 / hour at working pressures up to 4 bar. Table 15 shows the results achieved for an eight receptacle skate (31), each receptacle (25) comprising ten filter cartridges (18). and operated according to the following specifications: Weight of the filter material per cartridge: 10.9B Kg. Weight of the filter material per container: 109.8 Kg. Weight of the jump filter material: 878.4 kg. Oil contamination: 500 mg / liter. Oil adsorption: 90%. MEG contamination: 500 mg / liter. Adsorption of MEG: 80%. Flow: 1656 liters / hour.

TABLE 15 Figure 10 shows a graph of the trends of the flow velocity against pollution and the periods of intervention for a typical eight-receptacle skate employing the filter material of the third aspect of the present invention.

Claims (7)

NOVELTY OF THE INVENTION CLAIMS

1. - A filter material comprising a matrix in which a granular formulation of a material comprising a base formed substantially of cellulose fibers is dispersed, onto which a composition comprising one or more aliphatic carboxylic acids having chains of the same is adsorbed. hydrocarbons consisting of 8 to 20 carbon atoms.

2. A material according to claim 1, characterized in that the aliphatic carboxylic acid or acids have hydrocarbon chains consisting of 10 to 18 carbon atoms.

3. A material according to claim 1 or 2 »characterized in that the carboxylic acid or acids are selected from the group comprising stearic acid and palmitic acid.

4. A filter material according to claim 1, 2 or 3, characterized in that the matrix comprises a non-woven fibrous material.

5. A filter material according to claim 1, 2 or 3, characterized in that the matrix comprises open cell foam materials. 6.- A filter material in accordance with the claim 1 »2 or 3» characterized in that the matrix comprises a cotton or viscose gauze. 7. A filter column comprising a hollow core on which is mounted an alternating stack of filter plates and discs of the filter material according to any of the claims 6 »wherein the filter plates are adapted to allow the passage of fluid from a circumferential region of the filter column to the hollow core »by means of the discs of filter material. B. A filter cartridge comprising a hollow core around which is wound one or more layers of a filter material according to any of claims 1 to

6. 9.- A filter receptacle comprising an internally divided cover in two cameras by means of a carrier that supports at least one filter cartridge according to claim 8; the carrier and the cartridge (at least one) are arranged in such a way that it can pass only from one chamber to the other passing through both the hollow tubular core and the filter material of the cartridge (at least one). 10. A method of producing a material comprising a base substantially formed of cellulose fibers on which a composition comprising one or more aliphatic carboxylic acids having hydrocarbon chains consisting of 8 to 20 carbon atoms is adsorbed, in wherein one or more cellulosic materials are mixed together with a pulverized formulation of one or more carboxylic acids. 11. A method according to claim 12 »characterized in that the cellulose material or materials are selected from the group consisting of wood chips and virgin pulp. 12. A method according to claim 10 or 11, characterized in that latex is added to the cellulosic material or materials and the carboxylic acid or acids. 13. A method according to any of claims 10 to 12 »wherein the mixing is carried out in a hammer mill. 14. A method of cleaning a fluid by contacting the fluid with a material comprising a base formed substantially of cellulose fibers on which a composition comprising one or more aliphatic carboxylic acids having hydrocarbon chains is adsorbed. they consist of 8 to 20 carbon atoms »wherein one or more cellulosic materials are mixed together with a pulverized formulation of the carboxylic acid or acids. 15. A method according to claim 14 »characterized in that the fluid is air. 16. A method according to claim 15 »characterized in that the fluid is water. 1

7. A filter cartridge comprising a container having a fluid inlet and an outlet of fluid and includes a quantity of the material of any one of claims 1 to 6 between them.