WO2015075282A1

WO2015075282A1 - Removable sampling device for carrying out non-destructive autopsies in spiral membranes

Info

Publication number: WO2015075282A1
Application number: PCT/ES2014/000176
Authority: WO
Inventors: Juan Antonio LOPEZ RAMIREZ
Original assignee: Universidad De Cádiz (Otri)
Priority date: 2013-11-22
Filing date: 2014-10-22
Publication date: 2015-05-28
Also published as: ES2540574A1; ES2540574B2

Abstract

Fouling of desalination membranes poses a serious problem for the water-treatment industry. In order to identify the level of membrane fouling, a device has been developed that permits the retrieval of significant membrane samples for analysis in a laboratory, without having to extract, transfer and sacrifice one or more membrane elements of the system. The distribution of the device at different points of an installation allows for preventative and corrective monitoring of the fouling. The device comprises a hollow plastic tube that is perforated around the outside, and which can be opened at both ends when being substituted for the inter-connector having an external outlet, or closed at one end when being substituted for an end-cap of the permeate collector, a polymeric membrane, a spacer and an impermeable plastic.

Description

REMOVABLE SAMPLING DEVICE FOR THE PERFORMANCE OF NON-DESTRUCTIVE AUTOPSIES IN SPIRAL CONFIGURATION MEMBERS

SECTOR OF THE TECHNIQUE.

The scientific area to which this invention is intended is in engineering, more specifically in water treatment.

The industrial sector is that of water desalination, which includes any type of industry that uses spiral membrane systems for water treatment.

STATE OF THE TECHNIQUE.

The fouling of membranes is a major problem in membrane technologies. Water and its constituents are in contact with the membranes during the filtration processes. As a result, some of these constituents may adhere reversibly or irreversibly to the surface of the membranes, due to adsorption, precipitation, diffusion, etc. The result is that the surface, or part of it, is occupied by these materials and is reduced, reducing the useful area of filtration. This superficial reduction is manifested in multiple ways, affecting the unit's operating parameters: decrease in production, increase in energy consumption, loss of the quality of the water produced ... All this ultimately leads to an increase in production costs.

The physical-chemical and microbiological nature of water varies from one facility to another, so it is impossible to point to a common fouling agent, since it depends on the characteristics of the water to be treated. The best way to reduce the problem of fouling in the membranes is to know the nature of the water very well and avoid the critical conditions that lead to it. But the operating conditions applied to the treatment unit are imposed by aspects related to production needs, water quality, etc. It is these conditions and a good or bad execution that minimize or intensify the degree of fouling of the membranes. Once the membranes are dirty it is possible to apply cleaning systems and sequences to fully or partially recover the initial conditions of the membranes. Although these actions can have great benefits, they involve technical and productive shutdowns and reagent consumption, which implies a subsequent discharge and an environmental impact. All this entails, in short, production losses and increased costs.

When the agent causing the fouling is well known, it can be attacked specifically with certain cleaning agents, but when its nature is unknown, general cleaning agents and sequences are applied, which do not always achieve the desired effect.

Unfortunately, the only way to know which agents are deposited on the membranes is to perform autopsies of the membrane elements. This operation involves stopping the unit, opening the pressure containers and extracting a membrane element, or several, and sacrificing it in order to have samples that will be analyzed later in the laboratory. Logically, this implies having to replace that membrane element with a new one. Due to the design of the membrane elements (which can only be placed advancing in a single direction) it is necessary to remove all the elements at one end and put them back in the same order but at the other end. Once the extracted membrane element is taken to the laboratory for analysis it is opened to allow observation of the interior and the extraction of samples from the membrane surface for analysis, which implies its destruction,

From all of the above, the need to have a system that facilitates the performance of autopsies on membrane technology for water treatment, that allows to know its level of fouling and the agents deposited on the membranes, without producing a high consumption of time and replacement costs of the sacrificed elements, this being the object of the present invention. At present the existence of devices of these characteristics is unknown.

DESCRIPTION OF THE INVENTION

The fouling of the membranes is intrinsic to their functioning, in other words it is inevitable. But at least it can be minimized with good management of the membrane unit. For this, good monitoring of the system's operating parameters and water quality is essential. A deviation from the design conditions can lead to fouling that seriously impairs the operation of the unit. The fouling and its variants (organic, inorganic, colloidal, precipitation and microbiological) can be counteracted by performing chemical cleaning, either in situ or outside the place of operations, but in any case they involve the stoppage of the unit and the loss of production. Sometimes, a late diagnosis in the development of a fouling can lead to an unrecoverable situation due to the delay of the response and can be very expensive for the ownership of the installation, with all the damages that this entails. But even a quick response based on a misdiagnosis can be even worse because it could cause irreparable damage to the membranes. That is why a reliable, simple and economical system is needed to solve these types of situations, helping to manage and make appropriate decisions to prevent and fight against fouling and the problems it generates.

The present invention relates to a sampling device, which allows non-destructive autopsies to be performed on spiral configuration membranes, easy to place and remove, that provides pieces of membranes representative of what is happening within a given unit, allowing the Autopsy performed without destroying a membrane element. The information generated by these autopsies will help to take the more appropriate decisions on the most suitable cleaning agents and sequences for a good control of the membrane unit.

The device object of the present invention must be placed inside the pressure containers of the membrane water treatment units in spiral configuration, such as reverse osmosis, nanofiltration, ultrafiltration, etc. This device, easy to install and remove, incorporates a piece of membrane for analysis. Thanks to the configuration of the device, the portion of the membrane that it carries inside supports the same conditions as the membranes placed in the plant under study, so it is representative of what is happening and can be subjected to autopsy analysis to know the degree and the fouling mechanism the unit is experiencing. In this way the device facilitates the most appropriate decision making. Once what happens with that membrane is known, the most appropriate decision is chosen, which can be: do nothing, proceed to change the operating conditions, perform preventive or corrective cleaning, intensify the pretreatment, etc. In short, it allows the membrane unit to be managed more adequately.

The membrane elements in spiral configuration are placed in series inside a cylindrical pressure container that has two lids, one at each end, which seals said container, being only crossed by the tubes that lead the water to be treated, the treated water and The water rejected. It is necessary that one of the permeate collector ends of a membrane element of the end be blinded or plugged to prevent the outflow of the treated water and its mixing with the other water streams, which would spoil the process. The placement of the sampling device is carried out on the tubes called permeate collectors of the membrane elements of the ends of a pressure container. There is no standardized model in the form of pressure containers and in their closing lids, which can present various forms. However, they usually have a feed inlet tube at one end of the pressure vessel, which conducts the water to be treated, and two outlet tubes at the other end or end, which correspond to the permeate outlet (treated water ) and rejection (water rejected by the membrane). Therefore, the sampling device can have two different forms: in one of them it covers the permeate collector and seals it tightly to avoid water mixtures and in the other, it connects the permeate collector of the membrane element with the outside to extract the treated water from the pressure container. That is, one is shaped like a plug and the other has a hollow tube that connects to the permeate pipe.

Several sampling devices can be placed in the same installation. These devices can be placed in one or both ends of the same pressure container, or in several containers of a system that works in one, two or three stages. In this way, if the devices are distributed throughout the installation, it is possible to characterize the degree of fouling of the entire system at any given time by removing all the devices at once. But if you want to know the evolution of the fouling of the membranes of the treatment plant over time, you can select different devices and remove them sequentially over a certain period of time.

For proper placement of the devices, the container must be opened at one or both ends. The placement can be initial, when the plant is going to start up for the first time, or once its operations have begun. Depending on the place where the device is going to be placed, we can have two variants:

If the device is to be placed on the capped permeate collector, the piece that covers it must be removed and the device replaced, taking into account that the permeate collector is inserted at one end and blind at the other end .

If the device is to be placed at the opposite end of the container, which contacts the permeate collector with the outside, the interconnector must be removed and replaced by the device, which must have a shape compatible with the replaced part of such way to join the permeate pipe. Once the devices are placed, the correct sealing of the permeate collectors must be checked.

Finally, the end or ends of the pressure container is closed with the lid or lids thereof and the tightness of the system is checked.

The form of operation of the device is the same as any membrane element of the container where it has been placed. This ensures that its subsequent analysis reflects the actual operating conditions of the system. However, the device can incorporate a system of layers equal to the membranes of the unit whose behavior you want to analyze, or as mentioned above, you can incorporate a different layer system that you want to test in the unit, in case one day You want to change the type of membranes.

The device object of the present invention comprises a support formed by a hollow plastic tube perforated around it to a length less than the width of the piece of membrane to be used. These holes allow the permeate to pass through the membrane and be collected by the permeate collector. A very dense plastic mesh, known as a permeate or carrier mesh, is placed on the tube, allowing the permeate to easily pass through with a minimum pressure loss through it. This mesh has a rectangular shape and is placed on the ring-shaped plastic tube, glued or welded by its shorter ends. The union at its ends of the mesh with the support can be done in several ways, chemical, physical, thermal, etc., but should not interfere with its proper functioning. The surface used for the joint must be minimal and the bonding is done on a line parallel to the longitudinal axis of the plastic tube. The rectangular piece of membrane to be studied is placed on the mesh, forming a ring, and placing the joining lines of each layer on the previous one, to minimize the loss of active surface. The membrane will also be glued by its ends directly on the perforated plastic support so that there is sealing and forces the permeate to cross the active layer of the membrane, covering the permeate mesh entirely. On The membrane is placed a plastic mesh called a spacer that allows the water to mix avoiding problems related to the laminar flow within the membrane elements. This material is rolled and glued in the same way as the previous ones. Finally, a layer of waterproof plastic material is wound and glued on the spacer. Its placement ensures that the flow of water and hydrodynamic conditions on the surface of the membrane and spacer are equal to those of the adjacent membrane element because it simulates an active layer of another membrane.

Thanks to its configuration and design, the device faithfully reproduces the conditions of the adjacent membrane element so it is representative of what happens to it, regardless of whether it is placed at the beginning or at the end of the pressure container. Thus, when it is suspected that a type of fouling problem may exist in a membrane unit, a strategically placed sampling device can be extracted, which allows to evaluate, after laboratory analysis, the type of fouling that has developed in the unit and prepare the best cleaning strategy for correction. Once the device is removed, it can easily be replaced by a new one for later analysis or monitoring of the unit over time.

DESCRIPTION OF THE CONTENT OF THE FIGURES.

Figure 1 shows a partial perspective of the end of a pressure container with a single inlet or outlet and its lid together with the elements that make up the quick-release device in the form of a cap.

Figure 2 shows a partial perspective of the end of a pressure container with an inlet and outlet or two outlets and its lid together with the elements that make up the quick-disconnect device in the form of an interconnector.

Figure 3 shows elements of Figure 1 in their operating position inside the sectional and elevation container. Figure 4 shows elements of Figure 2 in their operating position inside the sectional and elevation container.

The elements shown in the different figures have the following references:

1. Pressure container.

2. O-ring.

3. Support with interconnector configuration, with holes and exit to the outside of the container.

4. Support with plug-shaped configuration with holes.

5. Permeate or carrier mesh.

6. Piece of membrane to be evaluated.

7. Membrane spacer.

8. Waterproof plastic layer.

9. Pressure container lid with an inlet or outlet.

10. Permeate collector of the membrane element.

11. Pressure container lid with one inlet and one outlet or two outlets.

12. Feed inlet tube or rejection outlet.

13. Mechanical closure of the pressure container lid.

14. O-ring of the pressure container lid.

15. Holes on the surface of the support with a plug-shaped configuration that allow permeate to pass through.

16. Holes on the surface of the support with an interconnector configuration that allow the permeate to pass through.

17. Membrane element.

18. Anti-telescope system of the membrane element. 19. Holes of the telescope system.

20. Section of the membrane element of the system to be evaluated.

21. Outward exit of the device in the form of an interconnector.

22. Glue rings to join the membrane to the plastic device generate tightness.

MODE OF EMBODIMENT OF THE INVENTION.

This device is valid for those pressure containers (1) that have a distance of a few centimeters between the anti-telescope device or "endcap" (18) and the closing lid of the pressure container (9,11). It can even be used on angled permeate interconnects.

The construction of the device is done from the inside out.

As previously mentioned, depending on the place where it is placed, the device can have two configurations: the "plug form" (4) when replacing the blind plug that blocks one end of the permeate collector, and the "interconnecting form" (3), when replacing the interconnector with output to the outside. The shape of both is different but the method of realization is the same for both devices. In both cases, the plastic tube that, in addition to fulfilling its function as a plug or interconnector, serves as support for the rest of the components of the device, must be constructed of a material resistant to the working pressure of the water treatment unit. The curved surface of the tube is perforated (15, 16) so that the water that passes through the membrane (6) can circulate towards the permeate collector (10). In the case of the cap-shaped device the flat face of the cylinder will be unperforated. The extension of the perforated surface will be less than the surface of the membrane deposited on them and between the ring-shaped joints of the adhesives (22) that join the membrane to the support (3, 4) so that there is a seal. The internal diameter of the support, both in its plug-shaped and interconnected configuration, must be slightly larger than the external diameter of the permeate manifold (10) of the membrane element (17) so that it can slide and fix on it. The tightness of the manifold-device assembly is ensured by the use of O-rings (2).

On the support (3, 4) a rectangular piece of permeate mesh or carrier (5) is placed all around and concentrically. The longest side of the rectangle to be placed will be a few millimeters greater than the length of the outer circumference of the plastic device, so that the remaining part can overlap and be used for joining. Thus this rectangle bends to form a cylinder. This joint also allows fixing on the plastic device by gluing. The permeate mesh must cover the entire perforated surface of the support (15, 16). A piece of membrane (6) will be deposited on this assembly, which can be of the same model as the one used in the installation under study or of any other one that you wish to test.

This piece of rectangular membrane (6) is placed concentrically to the permeate mesh (5) and joins in the same way as this one on the shortest side of the rectangle forming a cylinder. But in this case, it will also be glued additionally with glue (22) on the outer circular edges of said cylinder so that the water that passes inside crosses the device and is collected only by the permeate collector, thus ensuring the tightness of those unions. This requires that the surface of the membrane be slightly larger than that of the permeate mesh. The glue joints will form concentric rings (22) to the longitudinal axis of the plastic devices. A piece of spacer mesh (7) will be placed on the membrane (6). This spacer allows water to circulate in turbulent flow over the membrane, just as it happens inside the membrane elements. The union will be done in the same way as with the permeate mesh (5).

An impermeable layer of plastic material (8), glued in the same way as the previous meshes and membrane, is to be placed on this set. As far as possible all these joints will be placed on top of each other so that the useful surface of filtration with the water is maximum and is not affected by the different unions. This plastic layer must serve, in addition to protecting the entire device for handling, to generate a space equal to that of the existing water passage channel on the membranes of the membrane elements that are in the pressure container.

The length of the device depends on the distance between the permeate manifolds and the pressure container lids. In an indicative and non-limiting manner, this length can range between five and ten centimeters.

INDUSTRIAL APPLICATION

The fouling of membranes is the operating variable that is most related to the increase in the costs of membrane systems. Membrane systems get dirty throughout their operation. It is impossible for a system to not get dirty, but it is possible to keep dirtying under control. For this, a triple strategy is carried out: a good pretreatment, a rapid diagnosis of the development of fouling and a good membrane cleaning technique.

The devices object of this invention, placed throughout the entire membrane system, allow a rapid diagnosis of the degree and type of fouling that is occurring in the membrane unit to be carried out with a minimum loss of time and materials.

The possibility that they are extracted in a simple way to perform autopsy studies on them eliminates the need to have to open the pressure container, remove all the membrane elements and place them in the same order as they were, replacing one or two old elements (the first and the last) for new ones with the cost that this entails.

The design of the proposed device allows it to work in exactly the same conditions as the membranes that are next to it, which provides the information on the degree of fouling that the membranes of the unit are suffering.

Another advantage provided by the device is that, depending on the place of installation where it is placed, it will provide different information. Thus, if placed at the beginning of a container of a first, second or third stage it provides a type of information about the type of fouling that is occurring on the first membranes. And if it is placed at the end of a container of a first, second or third stage, it gives information about the type of fouling that is occurring in the last membranes.

The use of this device facilitates the extraction and obtaining of representative samples for laboratory analysis, being its handling much simpler than the cumbersome procedure of having to extract, move and open one or several membrane elements of many square meters.

This device can be used in seawater desalination plants, brackish water and any type of industrial installation that desalinates water by means of reverse osmosis or nanofiltration membranes, but also to those ultrafiltration and microfiltration units that use spiral-shaped membranes, since all they are subject to fouling of their membranes and have similar shapes.

Claims

CLAIMS.

1. Removable sampling device for performing non-destructive autopsies on spiral configuration membranes that comprises:

a) A hollow plastic tube perforated around it, called a support, which can be opened at both ends

(3) when replacing the interconnector with exit to the outside, or closed by one of them

(4) when replacing the plug on one end of the permeate collector.

b) A very tight plastic mesh of rectangular shape, called permeate mesh

(5), which will be placed concentrically on the hollow perforated plastic tube and glued to it by its shortest ends.

c) A rectangular piece of the membrane

(6) that you want to study, which is placed concentrically on the permeate mesh and will be attached to it by its shorter ends, while by the longer ends it is attached directly to the support, ensuring tightness and forcing the permeate to cross the active layer of the membrane

d) A plastic mesh, called a spacer

(7), which is rolled and glued at its shortest ends, matching its union with those of the previous layers.

e) A layer of waterproof plastic material

(8) which is rolled and glued on the spacer, making its union coincide with those of the previous layers. Removable sampling device for performing non-destructive autopsies on membranes with a spiral configuration, according to claim 1, characterized in that the internal diameter of the support must be slightly larger than the external diameter of the permeate collector of the membrane element on which it will be fixed by plugging it. .

Removable sampling device for performing non-destructive autopsies on spiral configuration membranes, according to claim

2, characterized in that the extension of the perforated surface of the support will be less than the surface of the membrane deposited on them and will be included between the ring-shaped joints of the glues (22) that join the membrane to the tube.

3, characterized in that the tightness between the permeate collector and the device is ensured through the use of O-rings (2) housed inside the support.

Removable sampling device for performing non-destructive autopsies on spiral configuration membranes, according to claim 1, characterized in that the longest side of the permeate mesh is slightly greater than the length of the external circumference of the support using the excess part that is flap for union.

Removable sampling device for carrying out non-destructive autopsies on membranes with a spiral configuration, according to claim 5, characterized in that the surface of the permeate mesh covers the entire perforated surface of the support. Removable sampling device for carrying out non-destructive autopsies on membranes with a spiral configuration, according to claim 1, characterized in that the membrane used in the device can be the same model as the one used in the installation under study or any other that is used. want to try.

Procedure for installing the device in a membrane system, according to claims 1 to 7, which includes the following steps:

a) Open the container at one or both ends.

b) Replace the interconnector or the plug that closes the permeate collector with the sampling device, fixing it on the permeate collector using O-rings.

c) Check the correct sealing of the permeate collectors. d) Closing the end or ends of the pressure container with its lid or lids.

e) Check the tightness of the system.

9. Use of the device, according to claims 1 to 8, to obtain significant samples of membranes for analysis in the laboratory, without the need to extract, transfer and sacrifice one or more membrane elements of the system.

10. Use of the device according to claim 9, to know the state of fouling of membranes in seawater desalination plants, brackish water plants and any type of industrial installation that desalinate water through reverse osmosis or nanofiltration membranes, but also in those units of ultrafiltration and microfiltration that use membranes in a spiral configuration.

11. Use of the device, according to claims 9, placing it at the beginning of a container of a first, second or third stage to obtain information about the type of fouling that is occurring on the first membranes.

12. Use of the device, according to claims 9, placing it at the end of a container of a first, second or third stage to obtain information about the type of fouling that is occurring on the last membranes.