RU152196U1 - DEVICE FOR REGENERATION OF ION EXCHANGE RESINS - Google Patents

Abstract

The utility model relates to countercurrent water treatment technology, and in particular to methods of ion-exchange water purification with regeneration of ion-exchange materials and can be used in energy, hydrometallurgy, chemical, food and other industries. It is proposed to install a modification of the SCHWEBEBETT technology in the chemical water treatment system, which includes a pre-treatment unit and a filter unit, in front of the filtration unit, in addition to a suspension water purification unit. The water purification unit includes a microfiltration or ultrafiltration module. Additionally, this unit may include a coagulant supply system installed in front of this module and a purified water tank installed after the module in front of the filtration unit As the tests showed, using oh technology it is possible to obtain water of improved quality at lower cost.

Description

The utility model relates to countercurrent water treatment technology, and in particular to methods of ion-exchange water purification with regeneration of ion-exchange materials and can be used in energy, hydrometallurgy, chemical, food and other industries.

Currently, there are more than 5 thousand industrial water treatment plants in the world using various types of ion exchanger regeneration. The existing water treatment technologies differ mainly in operational and economic indicators, in particular, in the amount of capital expenditures for creating an industrial water treatment plant and the costs of its operation. At the same time, such indicators as the interval of values of the workload in which the operability of the water treatment scheme are very significant are very significant; utilization rate of net volume; the degree of stringency of the requirements for the quality of the pretreatment of water sent to the ion exchanger; volume of water consumption for own needs; consumption of reagents for the regeneration of ion exchangers, etc. [].

Water treatment schemes are based on the use of a plant based on two filters (H and OH). In this case, the treated water passes from top to bottom sequentially through filters loaded with cateonite (usually strongly acid in the форме form, with water softening in the Na form) and anion exchange resin (for example, strongly basic in the OH form). The volume of active ion-exchange resin is not more than 50-60% of the internal volume of the filter.

If during the regeneration, the direction of supply of the reagents coincides with the direction of supply of the treated water (from top to bottom), then this technology of regeneration of the ion-exchange resin is called direct-flow. It has the following positive qualities: the ability to change the workload in a wide range of values, the freedom to alternate technological shutdowns with the resumption of the work cycle, the ability to remove contaminants accumulated during operation, and fragments of resin grains formed during its destruction during operation (from the mono-exchange resin layer) ( due to the operation of loosening the layer of ion-exchange resin carried out in each cycle), preventing channelization in the loading layer and, finally, the simplicity of the design of the filters. The disadvantages of this scheme are the increased consumption of reagents for regeneration and water used for their own needs.

Countercurrent technologies are known with hydraulic blocking (clamping) of the layer, in which the “clamping” of the ion-exchange resin layer during regeneration was carried out by supplying an additional stream of water, directed from top to bottom, towards the reagent stream. In the operating cycle, the treated water is supplied from top to bottom through a dispenser located in the upper part of the filter, passes through a layer of ion-exchange resin and an inert material, and a filter is discharged through the bottom dispenser. The ion-exchange resin layer fills up to 60% of the volume of the cylindrical part of the filter. During regeneration, the reagent flow is supplied from the bottom up, (to ensure a “clamped” state of the layer through the upper switchgear from top to down towards the reagent flow), an additional blocking water flow is supplied. Both flows are removed from the filter through the middle switchgear. The flow rate of water in the blocking stream should significantly exceed the flow rate of water in the reagent stream (otherwise, the layer of ion-exchange resin will decompress and mix), which requires a significant consumption of water for own needs. At the same time, this water treatment scheme allows you to choose a method of loosening washing: either the entire loading layer (with the obligatory subsequent double regeneration), or only the upper layers of the ion-exchange resin (when feeding water for loosening through a middle distribution device, which is buried in the layer of ion exchanger). Some schemes propose the use of air (pneumatic) blocking of the ion-exchange resin layer, which allowed to significantly reduce water consumption for own needs. [Alekseeva T.V., Fedoseev B.S. Improving the technique of ion exchange based on countercurrent technology // Energetik. 2001. No. 7. S. 17-19 .; www.mediana-filter.ru/ionit_regeneration_tecnology.html].

The advantages of this technology are the possibility of loosening washes without overloading the ion exchanger into an additional tank, as well as the possibility of stopping and resuming the operation of the water treatment plant at any time of the working cycle. The disadvantages are the low value of the coefficient of use of the useful volume of the filter, the difficulty of regulating the process parameters and controlling process flows during the regeneration of the ion-exchange resin.

To increase regeneration efficiency, Degremont proposed a counterflow technology called UFD [FR 7834555, 1978]. According to the UFD technology, the duty cycle is carried out in a top-down direction, and regeneration is carried out in a bottom-up direction. In this case, the entire internal volume of the filter is filled with active ion-exchange resin. (Inert is intended solely to protect the upper switchgear from ionite fines). Thanks to this loading of the filter, the ion exchanger layer is always in a clamped state - both during the working cycle and during regeneration; it is possible to vary the operating flow rates in a very wide range and freedom of action is achieved when alternating technological stops with the resumption of the working cycle.

Such an installation includes a filter and an associated external capacity for washing the ion exchanger. The design of the filter is simple. It is characterized by the presence of upper and lower switchgears, as well as the installation of a nozzle for hydrotransfer of ion exchanger in the upper part of the filter in such a way as to ensure the possibility of removing 30-50% of ion exchanger in an external container for rinsing by loosening. [www.mediana-filter.ru/ionit_regeneration_technology2.html].

The UFD technology allows you to effectively remove suspended matter and ionite fines accumulated during the work cycle, thereby overcoming one of the problems inherent in the counterflow technologies described above. The disadvantage of this technology is the need for double regeneration after each operation of loosening.

The most popular counterflow technology in the CIS today (over 20 operating plants for demineralization and softening processes) is UPCORE technology developed by the Dutch company Esmil B.V. [GB 1471162, 1977 .; GB 1501308, 1977; GB 1539161, 1978] and an improved "Dow Chemical". The features of the technology is that the duty cycle is carried out in a top-down direction, and regeneration is carried out from bottom to top. Suspended substances entering the filter with treated water accumulate mainly on the surface of the loading layer (and partially in the upper layers), from where they are very effectively removed during the operation of clamping the layer at the regeneration stage. [Gromov S.L. - Technological advantages of the process of countercurrent regeneration of ion-exchange resins UPCORE: washing by loosening - "Heat", 1998, No. 3, p. 52-55]

The installation using regeneration of ion-exchange resins using UPCORE technology consists of an ion-exchange filter having two drainage distribution systems at the top and bottom, filled with 85-95% ion exchanger and floating inert material and equipped with a valve system that ensures the sequential supply of the solution to be cleaned in the filter from the top downward and in a counter-flow direction - from bottom to top of water at a high speed, then a regenerating agent and washing water at a lower speed and the final washing of the ion exchanger from above h. At the same time, the inert used in "UPCORE" is intended to trap only whole resin grains in the filter, allowing free movement of finely dispersed suspensions and fragments of grains .. ["The UPCORE System". Engineering Handbook. Trademark of The Dow Chemical Company. May 1995, A1, page 5, 6, B2 page 21; RU 2241542, 2003; RU 2149685, 2000; Gromov S.L., Panteleev A.A. - Countercurrent ionite regeneration technologies for water treatment. Part 2 - Heat power industry No. 11, 2006, p. 50-55]. An extremely important advantage of the technology under consideration is the ability to remove accumulated suspensions from the resin layer directly in the working filter (i.e., without hydroloading of the ion exchanger).

However, with a long filter cycle, the amount of suspension entering the ion exchange filter with treated water, even if their current concentration is insignificant, may turn out to be significantly larger in absolute terms than under a short filter cycle (even if the initial dispersion concentration is higher).

To effectively remove suspensions from the resin layer, it was proposed [RU 2139253, 1999], when implementing the UPCORE technology, to equip the installation with an additional tank for carrying out loosening washing of ion exchanger, periodically taken from the working filter.

The disadvantages of the installation are the insufficient duration of the working filter cycle and the need for increased consumption of the regenerating agent due to incomplete clamping of the layer (up to 10% of the volume of the resin layer in the lower part of the apparatus can remain uncompressed), as well as the risk of longitudinal mixing of ion exchanger particles in the lower part of the layer, which leads to an insufficient degree of regeneration of ion exchanger particles, providing indicators of the quality of treatment of the treated medium.

Closest to the claimed solution is a filtration unit for ion-exchange water purification with ion exchanger regeneration using SCHWEBEBETT technology (Liftbett, Multistep options) of the German company Bayer AG [DE 1442689, 1963], which is currently used in more than 4 thousand industrial water treatment plants for demineralization of water . The installation includes anion and cation exchange filters, a decarbonizer and auxiliary equipment. A feature of this technology is that almost the entire volume of the filter is filled with active ion-exchange resin. A relatively narrow (up to 300 mm high) layer of floating inert material is located in its upper part (directly between the ion-exchange resin and the upper distribution device), therefore, a small free zone (necessary for “breathing” of the ion-exchange resin when moving from one working form to another). Using SCHWEBEBETT technology, ion-exchange resins are regenerated from top to bottom, and the duty cycle from bottom to top. The use of SCHWEBEBETT technology for water softening may be preferable in comparison with UPCORE when: the water supplied for softening is practically free of suspended solids, the plant's performance is constant and there is no need for technological stops, [www .mediana-filter.ru / ionit_regenera-tionjechnology.html]

At the same time, Schwebbebede has a significant drawback - during operation, the water flow goes from bottom to top, which does not allow the resin layer to be tightly clamped (due to the gravitational force, the granule tries to lower, the water stream lifts it up). In order to minimize the probability of transporting cationic fines into the filter with anion exchange resin arising from the destruction of the grains of the ion-exchange resin during operation, an inert material was selected so as to prevent the removal of almost any dispersion (suspension) from the filter. Moreover, due to hydroclassification, the largest (and heaviest) grains of the ion-exchange resin are concentrated in the bottom of the filter, and the smallest and lightest in the top. As a result, in the working cycle, when the source water containing suspensions is supplied from the bottom up, suspended solids, suspended particles and colloids are distributed over the entire height of the ion-exchange resin layer, penetrate deep into the resin layer and accumulate there. Suspensions are practically not washed out of the filter, their amount increases from cycle to cycle, which leads to an increase in the hydraulic resistance of the filter and a deterioration in the quality of regeneration of the ion-exchange resin. It is necessary to reload the resin in a separate container, wash it off from contaminants and then reload it into the filter. After this, it is necessary to do the so-called "double regeneration", i.e. supply 1.5-2 times more reagents, as we mix the “polishing layer” containing finer particles of resin and providing higher quality water. In addition, the operation is usually performed manually, part of the resin is lost, and its physical wear occurs.

The technical problem solved by the authors was to improve the quality of water purification using SCHWEBEBETT technology by eliminating suspensions in the treated water.

The technical result was achieved by installing in a chemical water purification system using SCHWEBEBETT technology, which includes a pre-treatment unit and a filter unit, in front of the filtration unit, in addition to a suspension water purification unit. The microfiltration or ultrafiltration module is included in the water purification unit. enter the coagulant supply system installed in front of this module and the purified water tank installed after the module in front of the filtration unit.

The general installation diagram is shown in FIG. 1, where the following notation is used:

1. Pre-treatment unit - BPO.

2. Membrane block of water purification from suspensions - BOV

3. Filtration unit - BFT

4. Module ultra - or microfiltration - MF

5. Coagulant supply system - SC

6. Tank of purified water - OV

7. Cation exchange filter - NF

8. Decarbonizer - DK

9. Anion-exchange filter - ONF.

10. The regeneration module of the ion exchange resin - MP.

The device operates as follows. The purified water enters BPO 1, the main element of which is a mesh automatic filter, where it is freed from large impurities, then it enters the ultra or microfiltration module 4, where the existing suspensions are removed. If necessary, before introducing into MF 4, a coagulant can be introduced into the water for better removal using the SK 5 pump. After MF 4, water is either additionally sedimented into OB 6 or fed to the filtering unit 3 using SCHWEBEBETT technology. FB 3 includes at least one cationic and anion-exchange filter 7 and 9 and dnacarbonizer 8, where carbon dioxide is removed, as well as auxiliary equipment (ion-exchange resin regeneration module 10, etc., in which, if necessary, reagents are fed into the filters and regeneration spent resin.

The essence and industrial applicability of the claimed device is illustrated by the following example.

Example 1. At the CHPP, 2 chemical water treatment systems HVO-1 and HVO-2 were mounted. HVO-1 used Apkore technology and included several filters - H upstream, H 1st stage, OH - 1st stage, decarbonizer, H 2nd stage, OH 2nd stage - with ion exchange resin regeneration by direct ionization

The HVO-2 was reconstructed using the effective SCHWEBEBETT countercurrent technology, which allows regeneration at an optimal linear speed (approximately 5-8 m / h), which is lower than with technologies with regeneration from the bottom up along the Apkor - 8-12 m / h. A higher speed is necessary in the latter case, so that the resin is pressed against the upper drainage system and does not fall down, taking into account the fact that during regeneration it is necessary to ensure the calculated concentration of the reactants and the contact time of the reactants with the resin (which at It is uniformly the same for all technologies - at least 20 minutes), with a higher linear feed rate of the regeneration solution it is necessary to supply a larger volume.In addition, the greater chemical efficiency of the SCHWEBEBETT technology is ensured due to the fact that smaller resin particles are located in the upper part of the filter , which is a “polishing zone” providing higher water quality and diffusion of reagents and water during cleaning in smaller granules is faster. That is, when using the SCHWEBEBETT technology, the water quality is achieved very high, and the reagent consumption is lower.

SCHWEBEBETT technology has been further enhanced by the introduction of membrane pretreatment by installing a microfiltration module in front of the filtration unit.

As shown by the experiments, membranes well remove suspended and colloids, which allows you to get the best effect on water quality and reagent consumption during ionization.

The test results are given in table. 1 for installation, with a productivity of 700 cubic meters per hour. The source water for HVO-1 and HVO-2 was taken from the same source, which makes the comparison of efficiency very indicative. The properties of water after the membrane module (MF) are shown for HVO-2, with the membrane module turned off - SCHWEBEBETT technology (SB) and with a combination of the membrane module and - SCHWEBEBETT technology (MF + SB)

As shown by tests, when using the inventive technology, it is possible to obtain high-quality water with less cost.

Claims (3)

1. A device for water purification, including a pre-purification unit and a filter unit containing at least one cation exchange and anion exchange filters, a decarbonizer and auxiliary equipment, characterized in that an ultra-suspended membrane water purification unit from the suspensions is installed in front of the filtration unit or microfiltration module. 2. The device according to claim 1, characterized in that the membrane unit for purifying water from suspensions contains a coagulant supply system installed in front of the membrane module. 3. The device according to claim 1, characterized in that the membrane unit for purifying water from suspensions contains a tank of purified water installed after the membrane module.

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