Liquid Purification System

Abstract

A liquid purification system includes a system raw liquid feed unit and a filtration unit, which includes a liquid concentration device having an internal partition dividing a variable volume collection cavity for raw liquid coming from an initial stage of liquid filtration and for mixing therein concentrate and a raw liquid displacement cavity. The cavity is connected to a secondary line that supplies raw liquid to the cavity to displace concentrate from the collection cavity and to recycle raw liquid from the displacement cavity through the secondary line under pressure exerted by concentrate and raw liquid in the collection cavity. A filtration unit provides long-term contact between raw liquid and concentrate in the variable-volume collection cavity to provide smooth increase in the concentration of liquid supplied to a liquid purification device.

Claims

1. A liquid purification system comprising: a system raw liquid feed unit comprising: a container, a primary raw liquid supply line, and a secondary raw liquid supply line having an inlet connected via a connection element to the primary raw liquid supply line before a pressurizing means mounted in the primary raw liquid supply line, wherein an outlet of the secondary raw liquid supply line is connected to the container; a filtration unit comprising: a mixing line configured to mix concentrate formed by a liquid filtration cycle with raw liquid, the mixing line connected via a connection element to the primary raw liquid supply line after the pressurizing means, at least one liquid purification means connected with liquid velocity increasing means, a recycling line configured to recycle at least a portion of the concentrate to the container, the recycling line connected to a concentrate exit of the at least one liquid purification means, a drain discharge line with a drain discharge valve mounted thereon, a purified liquid supply line connected to a purified liquid exit of the at least one liquid purification means, wherein the system raw liquid feed unit is adapted to displace the concentrate from the container made as a liquid concentration device comprising an internal partition by pressure exerted by the raw liquid on the internal partition, said internal partition configured to divide an inner space of the liquid concentration device into a variable volume collection cavity and a raw liquid displacement cavity, wherein the variable volume collection cavity is configured to receive raw liquid from an initial stage of liquid filtration and to mix therein the concentrate and the raw liquid during a liquid filtration process, wherein the variable volume collection cavity is connected to the mixing line and the recycling line, wherein the raw liquid displacement cavity is connected with the secondary raw liquid supply line and configured to displace the concentrate from the variable volume collection cavity of the liquid concentration device by the raw liquid coming from the secondary raw liquid supply line under pressure exerted by the raw liquid on the internal partition in a drain liquid discharge process and to recycle the raw liquid from the raw liquid displacement cavity of the liquid concentration device through the secondary raw liquid supply line under pressure exerted by a mixture of the concentrate and the raw liquid in the variable volume collection cavity on the internal partition of the liquid concentration device, wherein the filtration unit is adapted to provide long-term contact between the raw liquid and the concentrate in the variable volume collection cavity for the raw liquid coming at the initial stage of liquid filtration and for mixing therein concentrate and raw liquid in the liquid filtration process, to provide smooth increase in a concentration of liquid supplied to the at least one liquid purification means by mixing the raw liquid with the concentrate in the collection cavity of the liquid concentration device, wherein an inlet of the at least one liquid purification means is connected through a line configured to supply the mixture of the concentrate and the raw liquid, and in which a liquid velocity increasing means is mounted, directly to the collection cavity of the liquid concentration device, wherein the recycling line from the at least one liquid purification means to the liquid concentration device is connected via a connection element to the mixing line and to the primary raw liquid supply line.

2. A liquid purification system according to claim 1, wherein the drain discharge valve can be mounted in any point of the filtration unit.

3. A liquid purification system according to claim 1, further comprising an antiscalant and/or auxiliary substances dosed supply unit configured to supply and mix an antiscalant and/or auxiliary substances in the variable volume collection cavity with raw liquid coming into the variable volume collection cavity at the initial stage of liquid filtration, comprising an antiscalant and/or auxiliary substances storage tank connected to an inlet of an antiscalant and/or auxiliary substances supply line before antiscalant and/or auxiliary substances dosing means mounted in the antiscalant and/or auxiliary substances supply line; and an outlet of the antiscalant and/or auxiliary substances supply line is connected to the primary raw liquid supply line before the pressurizing means.

4. A liquid purification system according to claim 1, further comprising a prefilter mounted in the primary raw liquid supply line before the pressurizing means.

5. A liquid purification system according to claim 1, wherein the pressurizing means mounted in the primary raw liquid supply line is configured to create pressure providing low-output operation of the system.

Description

[0018] FIG. 1 shows a schematic diagram of a liquid purification system.

[0019] A liquid purification system (FIG. 1) comprises a system raw liquid feed unit (1) and a liquid filtration unit (8).

[0020] The system raw liquid feed unit (1) includes a primary raw liquid supply line (2), a liquid concentration device (4), a pressurizing means (3), a secondary raw liquid supply line (7), an antiscalant dosed supply unit (15), a prefilter (18), a solenoid valve (19), a low pressure relay (21).

[0021] The primary raw liquid supply line (2) comprises mounted in series a pressure reducer (24), a solenoid valve (19) and pressurizing means (3), and additionally a prefilter (18).

[0022] The prefilter (18) can be, for example, a mechanical liquid purification filter element or an element containing activated carbon.

[0023] The pressurizing means (3) can be, for example, but not limited to, a membrane (diaphragm) pump designed to create pressure that provides low-output operation of the system.

[0024] The liquid concentration device (4) comprises, for example, but not limited to, a housing (not shown in FIG. 1) which is divided by an internal partition (17) into a variable volume collection cavity (5) for raw liquid coming at initial stage of liquid filtration and for mixing therein the concentrate and raw liquid in the liquid filtration process, and a raw liquid displacement cavity (6).

[0025] FIG. 1 shows an embodiment where an internal partition (17) is formed as a chamber defining a collection cavity (5) accommodated in the liquid concentration device (4). Space defined between inner walls of the housing (not shown in FIG. 1) and outer surface of the internal partition (17) of the chamber defining the collection cavity (5) forms a raw liquid displacement cavity (6).

[0026] In another embodiment each cavity in the liquid concentration device can be defined on three sides by inner walls of the housing and on one side by the internal partition (not shown in FIG. 1).

[0027] Structure of the liquid concentration device further allows e.g. the arrangement of the raw liquid displacement cavity inside a chamber defined by walls of the internal partition, and the collection cavity between inner walls of the housing and the outer surface of the chamber defining the displacement cavity (not shown in FIG. 1).

[0028] An inlet of the secondary raw liquid supply line (7) with a low pressure relay (21) mounted thereon is connected, via a tee (not shown in FIG. 1), to the primary raw liquid supply line (2), and an outlet is connected to the raw liquid displacement cavity (6) of the liquid concentration device (4).

[0029] Further connected to the primary raw liquid supply line (2) is an antiscalant and/or auxiliary substances dosed supply unit (15) comprising an antiscalant and/or auxiliary substances storage tank (not shown in FIG. 1) connected to an inlet of the antiscalant and/or auxiliary substances supply line (26) before means for dosing antiscalant and/or auxiliary substances such as a metering pump (not shown in FIG. 1) mounted in the antiscalant and/or auxiliary substances supply line (26); an outlet of the antiscalant and/or auxiliary substances supply line (26) is connected to the primary raw liquid supply line (2) before the pressurizing means (3). Auxiliary substances can be e.g. coagulants, oxidants, and catalysts.

[0030] The liquid filtration unit comprises a concentrate and raw liquid mixture supply line (9), liquid velocity increasing means (10), at least one liquid purification means (11), a concentrate recycling line (12), a line (13) for mixing the concentrate with raw liquid, a drain discharge line (23), a purified liquid supply line (14), and a purified liquid storage tank (20).

[0031] A liquid velocity increasing means (10), e.g. a centrifugal pump, is mounted in the concentrate and raw liquid mixture supply line (9).

[0032] An inlet of the concentrate and raw liquid mixture supply line (9) is connected to the collection cavity (5), an outlet of the concentrate and raw liquid mixture supply line (9) is connected to at least one liquid purification means (11). A purified liquid exit of the at least one liquid purification means (11) is connected to an inlet of a purified liquid supply line (14) with a check valve (29) mounted thereon, which is connected to means (28) for supplying purified liquid to a consumer and to a purified liquid storage tank (20), which can be, for example, but not limited to, a water-air tank, a non-pressure tank or a liquid storage cavity provided with a compressor.

[0033] A concentrate exit of at least one liquid purification means (11) is connected to an inlet of the concentrate recycling line (12), an outlet of which is connected, via a connection element such as a tee (27), to an outlet of the primary raw liquid supply line (2) and an inlet of the concentrate and raw liquid mixing line (13). An outlet of the concentrate and raw liquid mixing line (13) is connected to a collection cavity (5) of the liquid concentration device (4). A check valve (25) is mounted in the concentrate recycling line (12) to pass the concentrate only towards the collection cavity (5).

[0034] The liquid purification means (11) comprises, for example, but not limited to, a membrane element (reverse osmosis or nano-filtration membrane in a casing) or a cascade of membrane elements.

[0035] An outlet of the secondary line (7) is connected to the raw liquid displacement cavity (6) of the liquid concentration device (4).

[0036] The drain discharge line (23) with a solenoid valve (16) mounted thereon can be connected to the concentrate and raw liquid mixture supply line (9) before the liquid velocity increasing means (10) (FIG. 1), after the liquid velocity increasing means (10) (not shown in FIG. 1). Otherwise, the drain discharge line (23) with a solenoid valve (16) mounted thereon can be connected to the concentrate recycling line (12). In the latter case such connection of the drain discharge line (23) will allow flushing of the liquid purification means (11) with raw liquid (not shown in FIG. 1).

[0037] Within the scope of distinctive features, the liquid purification system is intended to implement the following liquid filtration process.

[0038] At start-up of the liquid purification system raw liquid flows from a source to the inlet of the primary raw liquid supply line (2) and further, via the prefilter (18), to the pressurizing means (3). When raw liquid passes through the primary raw liquid supply line (2) a predetermined amount of antiscalant and/or auxiliary substances is fed to it from the antiscalant and/or auxiliary substances supply unit (15). The pre-purified raw liquid comprising an antiscalant is supplied through the concentrate and raw liquid mixing line (13) into the collection cavity (5) of the liquid concentration device (4). Owing to the fact that the pressurizing means (3) is disposed before the liquid concentration device (4), raw liquid enters the collection cavity (5) under a pressure that is kept constant during the liquid filtration cycle and is sufficient for passing the liquid through the at least one liquid purification means (11). As mentioned above, the liquid velocity increasing means (10) is mounted in the concentrate and raw liquid mixture supply line (9). Flow of raw liquid coming through the concentrate and raw liquid mixture supply line (9) from the collection cavity (5) passes through the liquid velocity increasing means (10) and acquires a velocity, at which the time of passage of the liquid through the liquid purification means (11) will be minimal. This is necessary to reduce the amount of contaminants remaining in the liquid purification means, and thereby to extend the service life of the at least one liquid purification means (11). After the liquid purification means (11) the purified liquid flows through the purified liquid supply line (14) into the purified liquid storage tank (20) or directly to consumers.

[0039] After the liquid purification means (11) the concentrate formed in the filtration process passes, through the concentrate recycling line (12), to the line (13) for mixing the concentrate with raw liquid and further to the collection cavity (5). As mentioned earlier, an inlet of the line (13) for mixing concentrate and raw liquid is connected to an outlet of the primary raw liquid supply line (2).

[0040] After the first passage of raw liquid through the liquid purification system, a ternary mixture of concentrate and raw liquid, which comprises a predetermined amount of an antiscalant, is formed in the filtration unit (8). The ternary mixture is formed owing to the fact that the collection cavity (5) receives the concentrate from the liquid purification means (11) via the line (13) for mixing concentrate with raw liquid through the concentrate recycling line (12), and raw liquid from a source through the primary raw liquid supply line (2) during the filtration cycle. Antiscalant is fed to the primary raw liquid supply line (2) once at the beginning of each filtration cycle. During one filtration cycle the ternary mixture passes through the liquid concentration device (4) and the at least one liquid purification means (11) several times. In this process the salt content (concentration of mixture) in the ternary mixture increases. Liquid filtration process stops when a predetermined volume of purified liquid is obtained.

[0041] Then process of refreshing the system starts. The valve (19) mounted in the primary raw liquid supply line (2) shuts off the flow of raw liquid to the collection cavity (5); the pressurizing means (3) and the liquid velocity increasing means (10) are switched off. As a result, pressure on the concentrate and raw liquid mixing line (13) decreases. As pressure in the collection cavity (5) becomes lower than pressure in the raw liquid source, raw liquid starts flowing through the secondary line (7) to the displacement cavity (6) and gradually displaces the concentrated ternary mixture via the drain discharge line (23) through the open drain discharge valve (16) from the system.

[0042] In the embodiment where the drain discharge line (23) is disposed in the concentrate recycling line (12) (not shown in FIG. 1), liquid remaining in the line (9) for supplying the mixture of concentrate an raw liquid passes, under residual pressure, through the liquid purification means (11); in this case a small amount of purified liquid is formed, which increases the efficiency of the system. Also, before starting a new filtration cycle, the at least one liquid purification means (11) can be flushed with raw liquid. In this case, raw liquid coming into the collection cavity (5) passes through the at least one liquid purification means (11) and is removed from the system through the valve (16).

[0043] Upon completion of the system cleaning process, the valve (16) closes, the valve (19) opens and the pressurizing means (3) and the liquid velocity increasing means (10) are actuated. Liquid filtration cycle starts. As pressure in the collection cavity (5) increases with admission of liquid into it, raw liquid from the raw liquid displacement cavity (6) returns, via the secondary line (7), to the primary raw liquid supply line (2), and comes with the main raw liquid flow into the collection cavity (5) and further into the liquid purification means (11).

[0044] Unlike the most relevant prior art, the system raw liquid feed unit is adapted to displace concentrate from the liquid concentration device (4) comprising an internal partition (17) under the pressure exerted by raw liquid on outer wall of the chamber (internal partition (17) of the collection cavity (5)). In this case, raw liquid used to refresh the system is not mixed with concentrate and not discharged to drain, but is recycled back to the liquid purification system for filtration, thereby reducing the consumption of raw liquid used. In addition, unlike the prior art, pressure in the liquid purification system is kept constant during the filtration cycle.

[0045] The fact that the line (13) for mixing concentrate with raw liquid of the filtration unit is connected to the collection cavity (5) provides long-term mixing (contact) of raw liquid with concentrate and smooth increase in the load on at least one liquid purification means (11) with increasing concentration of salts in the mixture; therefore the service life of the at least one liquid purification means (11) can be extended.

[0046] In the most relevant prior art, at the instant when the system switches from the large closed liquid purification circuit to the small purification circuit, the concentration of contaminants coming to at least one purification means dramatically increases, which decreases the effectiveness of its operation. The increased concentration of contaminants coming to at least one purification means increases the load on the pressurizing means and the liquid velocity increasing means, therefore, the amount of energy needed to make them work increases as well.

[0047] As mentioned earlier, unlike the most relevant prior art, in the present invention pressure is kept constant during the entire filtration cycle and sufficient for passage of liquid through at least one liquid purification means (11). Such pressure is created by the pressurizing means (3) disposed, in contrast to the prior art, before the liquid concentration device (4). Operation of the pressurizing means (3) consumes a small amount of energy. Also in the filtration cycle the ternary mixture comes into the collection cavity (5) of the liquid concentration device (4), where the antiscalant-containing raw liquid is additionally mixed with concentrate; this provides uniformly increasing load on at least one liquid purification means (11) during each passage of the mixture through liquid purification means (11) and does not require increasing the pressure for passage of liquid through it. Therefore, in addition to reduced consumption of raw liquid, the liquid purification system reduces the energy consumed for its operation.

[0048] The present description discloses a preferred embodiment of the invention. It can be modified within the scope of the claims thereby providing its wide applicability.