RU2785322C1 - Apparatus for reagent distribution in the fluidised bed - Google Patents

Abstract

FIELD: liquid handling.

SUBSTANCE: invention is intended for distributing reagents in the fluidised bed for softening water. Reagent distribution apparatus constitutes a vertical cylindrical column, wherein a distribution system with drainage caps for the input of water for softening is installed in the lower part thereof, and an outlet for collecting softened water is installed in the upper part. An apparatus for reagent distribution with a system for supply thereof is installed above the distribution system with drainage caps. The column is filled with a fluidised bed of a fine-grained material. An output for the spent sand — granules is made above the distribution system with drainage caps. The apparatus for reagent distribution is made movable and detachable and is connected through the top of the column with the reagent supply system via a vertical flexible hose and is supported in the fluidised bed by a cable linked with a lifting apparatus configured to adjust the submersion depth and lift the apparatus for reagent distribution through the top of the column.

EFFECT: lower crystal formation on the surface of the plate of the distribution system with drainage caps for water and on the distribution apparatus for the input of reagents.

5 cl, 5 dwg

Description

The present invention relates to devices for distributing flows, namely, for distributing a reagent in a water softening reactor with a fluidized carrier bed, on which hardness salt crystals are deposited, and can be used in installations for softening drinking water, in energy, in chemical and other industries industry.

For reagent softening of water, a number of technological methods and design of devices are used. The most common method is water treatment with milk of lime with iron coagulant and organic flocculant in horizontal and vertical clarifiers of various types.

Another way is to treat water with chemical reagents: milk of lime, alkali or soda in the presence of a special seed, as a rule, this is sand of a given size.

Ca (HCO ₃ ) ₂ + Ca (OH) ₂ → 2CaCO ₃ ↓ + 2H ₂ O,

Ca (HCO ₃ ) ₂ + 2NaOH \u003d CaCO ₃ ↓ + Na ₂ CO ₃ + 2H ₂ O.

Ca (HCO ₃ ) ₂ + Ca (OH) ₂ + Na ₂ CO ₃ \u003d 2CaCO ₃ ↓ + 2NaOH

When the reactant is introduced, the reactions described above occur, which lead to the formation of a solid CaCO ₃ calcium carbonate, which is deposited on the surface of the particles of the carrier - the seed in the fluidized bed.

Devices are known for distributing a reagent in a fluidized carrier bed in so-called pellet reactors, for example, a company from the Netherlands that has implemented a large number of such devices (Softening WATER TREATMENT, https://ocw.tudelft.nl/wp-content/uploads/Softening- 1.pdf) for water softening and decarbonization, or the “Crystalactor” process developed by the Dutch company DHV and implemented in the USA by Procorp (The Crystalactor Efficient Treatment without Waste, https://global.royalhaskoningdhv.com/en/crystalactor) for softening and decarbonization of water and removal of heavy metals, phosphorus, etc. - a special distribution system located at the bottom of the reactor for introducing treated water and a reagent.

The fluidized bed plant is a vertical cylindrical column with a special distribution system located at the bottom for introducing purified water and reagents, and at the top with an extension and a collection tray for collecting purified (softened and decarbonized) water. A branch pipe is provided at the top for introducing the seed material, and at the bottom for the output of the formed calcium carbonate granules.

The operation of such an installation is based on the reaction of the formation of calcium carbonate during the interaction of dissolved calcium salts with he ^- or co ^-2 ₃ ions introduced into the solution at a dosage of alkali or soda. The process is carried out in the presence of a special seed loaded into the reactor. A small heavy material is used as a seed - sand, garnet, calcite, etc. the initial size of its particles is from 0.2 to 0.5 mm.

When water is supplied at a speed of up to 100 m/h, the loading layer is fluidized, and the water moves freely through the expanded layer. The surface of the sand particles is completely washed by water. When the reagent is supplied, the reaction of the formation of calcium carbonate crystals begins, which stick to the surface of the sand particles. When water moves up the layer, the crystals are completely captured by the loading particles. At the exit, the water is completely clean. As the work continues, the size of the formed granules (pellets) constantly increases. When the granules reach a size of 1-5 mm, they are removed from the bottom of the apparatus. In this case, only the largest part of the layer is displayed. A new amount of fine sand is added on top and the process continues.

By adjusting the flow rate of the injected reagent and the speed of the water, it is possible to control the depth of softening or decarbonization or the degree of removal of heavy metals or phosphorus.

Such a device has a high productivity of 50-100 m3 / m2 * h and, accordingly, occupies a small area and building volume. Unlike settling tanks, it does not require the use of coagulants and flocculants, it works quite stably with changes in temperature and water flow, which is very important, it allows you to get a minimum amount of waste - less than 1% in solid form suitable for disposal.

The design of the apparatus is relatively simple. The most complex part is the distribution system. It must provide:

- uniform distribution of water over the cross section of the apparatus;

- uniform input of the reagent over the entire cross section, while the consumption of reagents is only about 1% of the water flow;

- uniform unloading of the formed granules.

This occurs under conditions of a very rapid onset of crystallization and the presence of fine sand that clogs all the holes.

Closely related in design are the “Netherland type” apparatuses operating with dosing of concentrated alkali, which use devices for distributing the reagent in a fluidized bed, including a special double distribution plate and very complex cap devices through which both water and alkali are injected simultaneously. In this case, water is supplied under the lower distribution plate, and alkali is fed into the space between the plates (Softening WATER TREATMENT, pp. 167-168).

The disadvantage of the described device is that the reaction takes place in close proximity to the surface of the upper plate, on which cap devices are installed. The result is the formation of crystals on the surface of the upper plate and cap devices. (Improving CFD modeling of drinking water reactors. Fig. 6-7. https://d1rkab7tlqy5f1.cloudfront.net/3mE/Organisatie/Afdelingen/Process%20%26%20Energy/Education/available%20projects/IRS/180507%20MSc_project %20CFD%20FBI%20nozzles%201.3.pdf ).

The closest analogue is a device for distributing a reagent in a fluidized bed in a reactor for reagent water softening (RF Patent No. 198959 dated 08/05/2020), consisting of a distribution plate with drainage caps and a device for supplying a reagent - a tubular collector with nozzles distributed over its cross section, immersed in the fluidized bed above the drain caps of the distribution plate.

The disadvantage of this solution is the difficulty in cleaning the device for distributing the reagent in the fluidized bed when it is overgrown with calcium carbonate salts. It is necessary not only to stop the operation of the apparatus, but also to unload the formed granules and sand from it.

The objective of the invention is to reduce the formation of crystals on the surface of the plate of the distribution system with drainage caps for water and to reduce the formation of crystals on the distributor for introducing reagents, eliminating the possibility of sand entering the reagent and water supply lines, as well as simplifying the design while maintaining the other positive qualities of the prototype, while maintaining the efficiency of water treatment.

The problem is solved by the fact that the device for distributing reagents in a fluidized bed for softening water is made in the form of: a vertical cylindrical column, expanding towards the top, in the lower part of which a distribution system with drainage caps is installed for introducing softened water, and in the upper part - a system for outputting softened water. water. Also in the column, above the distribution system with drainage caps, a reagent distribution device with its supply system is installed, and the column itself is filled with a fluidized layer of fine-grained material - sand. At the same time, waste sand - granules is removed above the distribution system with drainage caps.

Also, the reagent distribution device is located in a fluidized bed above the surface of the distribution system plate with drainage caps at a distance of more than 5 heights of its drainage caps and is a tubular collector with drainage caps installed on it, distributed evenly over the collector cross section.

And at the same time, the reagent distribution device is made movable and removable, and is connected by a vertical flexible hose, through the top of the column, to the reagent supply system, and is supported in the fluidized bed by a cable connected to the lifting device, which is configured to adjust the immersion depth and lift the reagent distribution device through the top of the column.

In the upper part of the column, preferably, an additional nozzle should be made for supplying fine-grained material to replace the spent material.

The lifting device is made in the form of a hoist.

Reagents can be introduced through a reagent distribution device made in the form of a tubular collector with small section pipes lowered down, uniformly distributed over the cross section of the tubular collector.

Alternatively, the reagents may be introduced through a reagent dispenser constructed as a tubular manifold with caps mounted upwards based on the "natural repose" phenomenon.

Alternatively, reagents can be introduced through a reagent distribution device made in the form of a tubular collector with drain caps of a slotted standard type installed upwards, used in mechanical and ion-exchange filters.

The distribution device is a tubular manifold connected to a flexible reagent supply hose and a cable. The tubular collector is made in the form of tubes connected to each other in a horizontal plane and with caps mounted on them, which should preferably be evenly distributed over all the tubes of the collector. The caps can be either conventional down-turned tubes (as it is done in the nearest analogue), or raised-up tubes with caps based on the “natural slope” phenomenon (caps installed on the inlet nozzles in such a way that the water is injected above the lower hole cap to a height greater than a layer of solid granular material can rise after its deposition), and each is made as follows: the cap is installed on the nozzle for removing liquid from the collector tube and fixed so that its inner tube is connected to the collector tube, and the outer cap is free; and drainage slotted caps of a standard type, used in mechanical and ion-exchange filters.

Due to the intensive mixing of the fluidized bed, the reagents are quickly distributed over the cross section of the reactor.

The inventive device for distributing a reagent in a fluidized bed is shown in FIG. 1 and consists of:

1 - cylindrical column;

2 - distribution plate for water;

3 - device for the distribution of the reagent;

4 - fluidized bed of sand;

5 - cable for extracting and adjusting the height of the device for distributing the reagent;

6 - reagent supply hose;

7 - a branch pipe for an output of the softened water;

8 - branch pipe for supplying fresh sand;

9 - branch pipe for the withdrawal of waste sand - granules;

10 - tubular collector;

11 - branch pipes with open ends, lowered down;

12 - branch pipes equipped with drainage caps, made on the basis of the phenomenon of "natural repose" and directed upwards;

13 - branch pipes equipped with drainage caps of a standard type;

14, 15 - fasteners for the cable;

16 - regent,

17 - treated water.

The inventive device - the reaction apparatus is (Fig. 1) a cylindrical body 1 with a distribution plate 2 located at the bottom, which serves to distribute the purified water over the entire cross section of the apparatus and prevent sand from entering the pipelines supplying water. Above the distribution plate is a fluidized layer of sand 4, which occupies 50-80% of the height of the apparatus. In the thickness of the fluidized bed there is a distribution device 3. It is connected to a cable 5 for its extraction and height adjustment and to a reagent supply hose 6. The cable 5 can be fixed by means of a lifting device (for example, a hoist). In this case, the lifting device regulates the depth of immersion of the switchgear 3 and provides the possibility of its extraction, washing and repair.

The expansion at the top is necessary to reduce water velocity and prevent fine sand from being entrained. Softened water is discharged through the outlet pipe 7.

In the upper part of the apparatus there is a branch pipe for supplying fresh sand 8.

In the lower zone there is a branch pipe for periodic unloading of granules i.e. sand with a layer of calcium carbonate adhering to it, connected to branch pipe 9 and further to the pipeline.

Such an arrangement of the distribution device ensures that the reaction proceeds in a space free from parts of the lower distribution plate.

A solution of alkali, soda ash or lime water is supplied to the switchgear by a pump. The reaction of formation of calcium carbonate occurs in a layer of sand, carbonate is deposited on its particles, enveloping them and forming a solid layer. As the size of the resulting particles, which are called granules, increases, they form a heavier layer at the bottom of the reactor. As large granules accumulate, they are unloaded from the reactor, and a portion of fresh loading is introduced from above.

In FIG. Figures 2-5 show design options for reagent distribution devices 3. The cable 5 for lifting it is rigidly fixed on the collector 10 at points 14 or 15. A flexible reagent supply hose 6 is also connected to it. The reagent is introduced into the sand layer through devices distributed around the perimeter of the collector 10 , which can be both in the form of tubes 11 lowered down in accordance with the patent of the Russian Federation No. 198959 (see Fig. 2), and with tubes and caps 12 raised up, based on the phenomenon of "natural repose" in accordance with the patent of the Russian Federation No. 2752351 (see Fig. 3) and standard type 13 used in the mechanical and ion exchange filters shown in Figs. 4. In this case, the location of the output devices 11,12,13 from the tubular collector 10 is shown in FIG. 5.

Conducted long-term tests of the reactor model with a fluidized bed with a capacity of 3 m ³ /h showed its efficient and stable operation at speeds of 45-110 m/h. At the same time, the formation of deposits on the nodes of the distribution system and the walls of the apparatus was not detected. The degree of softening corresponded to the concentration of temporary hardness, which corresponds to the calculations.

Claims (5)

Fig. 1. A device for distributing reagents in a fluidized bed for water softening, made in the form of: a vertical cylindrical column, expanding upwards, in the lower part of which a distribution system is installed in the form of a plate with drainage caps for introducing softened water, and in the upper part - a system for collecting softened water, also in the column above the distribution system with drainage caps, a device for distributing the reagent with its supply system is installed, and the column itself is filled with a fluidized layer of fine-grained material - sand, while calcium carbonate granules are removed above the distribution system with drainage caps, characterized in that the reagent distribution device is located in a fluidized bed above the surface of the distribution system tray with drainage caps at a distance of more than 5 heights of its drainage caps and is a tubular collector with drainage caps installed on it, distributed evenly over the cross section of the collector, also the reagent distribution device is made movable and removable and is connected by a vertical flexible hose passing through the column to the reagent supply system, and is supported in the fluidized bed by a cable connected to a lifting device, which is configured to adjust the depth of immersion and lifting of the device distribution of reagents through the top of the column. 2. The device according to claim 1, characterized in that the lifting device is made in the form of a waist. 3. The device according to claim 1, characterized in that the reagents are introduced through a reagent distribution device made in the form of a tubular collector with small cross-section pipes lowered down, uniformly distributed over the cross section of the tubular collector. 4. The device according to claim 1, characterized in that the reagents are introduced through a reagent distribution device made in the form of a tubular collector with caps mounted upwards, based on the "natural repose" phenomenon. 5. The device according to claim 1, characterized in that the reagents are introduced through a reagent distribution device made in the form of a tubular collector with drainage slotted caps installed upwards, used in mechanical and ion-exchange filters.

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