RU2366615C2 - System for desalting of natural waters using reserve modules of reverse osmosis desalting in operating modes (versions) - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: system for natural waters desalting contains the pretreatment device and reverse osmosis device based on a membrane elements containing at least one desalting stage. Every stage includes paralleled at least one working and one reserve module. At the outlet stage of reversed osmosis device the collectors of permeate and/or concentrate in the division of working modules connection are connected through additional cutoff devices on-line with inlet of at least one reserve module of the same stage.

EFFECT: maximal usage of all installed membrane modules.

10 cl, 4 dwg, 4 tbl, 3 ex

Description

The invention relates to the field of power engineering and can be used in water treatment systems for producing demineralized water from natural waters.

Currently, a number of TPPs and industrial enterprises use water desalination systems for desalination of water with sequentially included pretreatment unit (UPR) and reverse osmosis unit (UOE) on membrane elements. At the same time, the norms of designing water supply systems [1] provide for the mandatory reservation of water purification equipment to ensure maximum design capacity of the system when a part of the equipment is taken out for repair.

Known is taken as a prototype of the invention, the system of desalination of natural waters, containing UPR and DOE on membrane elements with at least one stage of desalination, and each stage includes at least one working collector of purified water, permeate and concentrate connected in parallel through cutoff valves and at least one redundant module [2].

The disadvantages of the prototype include the inefficient use of backup equipment (membrane modules), included in the work, mainly during periods of short-term failure of the main equipment. The disadvantages of the prototype are also the inefficient use of not only reserve, but also working membrane modules, since if it is necessary to reduce system performance, some of the working modules are additionally put into reserve, and the inability to control the quality of demineralized water when changing the composition of the source water. Another disadvantage of the prototype is the need for periodic inclusion in the operation of redundant modules (regardless of the presence of a greater or lesser need for demineralized water) due to the inadmissibility of their long downtime.

Achievable results of the invention are: maximum beneficial use of all installed membrane modules, including redundant; improving the quality of demineralized water, including hardness; reduction in the volume of spent concentrate UOO; the possibility of generating additional amounts of demineralized water; reduction of reagent costs (acid, alkali or NaCl) for permeate treatment in the presence of an additional H-OH-ionization or Na-cation after UO.

These results are ensured by the fact that in a natural water desalination system containing UPR and UO on membrane elements with at least one desalination step, each step comprising at least one purified water, permeate and concentrate collectors connected in parallel through cutoff valves working and at least one redundant modules, according to the invention, at least at the output stage of the UOO, permeate or concentrate collectors in the connection section of the working modules enes via a further shut-off valve in series with the input of at least one backup module of the same stage.

In another embodiment, a natural water desalination system comprising UPR and UO on membrane elements with at least one desalination step, each step comprising at least one working and at least one working and at least one working and at least one collector of purified water, permeate and concentrate at least two redundant modules, according to the invention, at least at the output stage of the UOO, the permeate and / or concentrate collectors in the connection section of the working modules are connected through an additional tsechnuyu armature series with the input of at least one backup module of the same stage.

Moreover, in both versions, each working module of at least the OOE output stage can be additionally connected through shut-off valves in series with each of the other working and reserve modules of the same stage along the permeate or along the concentrate; between the concentrate collector of the output stage of the DOE and the backup modules, an intermediate tank and a filter unit for purifying the concentrate of metal oxides and / or organic compounds can be sequentially connected; between the concentrate collector of the output stage of the DOE and the backup modules, a dosing unit for the reagent - scale inhibitor can be switched on.

Possible embodiments of the DOE according to the invention are shown in table 1.

Table 1 Productivity UOO, m ³ / h Range of change slave.
costs, m ³ / h DOE working part Reserve part of UOO % reservation Number of modules Units production mod., m ³ / h Number of modules Units production mod., m ³ / h fifty fifty one fifty one fifty one hundred 25-50 2 25 one 25 fifty one hundred one hundred one one hundred one one hundred one hundred 50-100 2 fifty one fifty fifty 25-100 four 25 one 25 25 200 200 2 one hundred one one hundred fifty 100-200 2 one hundred one one hundred fifty 50-200 four fifty one fifty 25 300 300 3 one hundred one one hundred 33 200-300 2 one hundred one one hundred 100-300 2 fifty one fifty fifty 2 one hundred one one hundred 400 400 four one hundred one one hundred 25 200-400 3 one hundred one one hundred 100-400 2 fifty one fifty 3 3 one hundred one one hundred 500 500 5 one hundred one one hundred twenty 400-500 four one hundred one one hundred 200-500 2 fifty one fifty thirty 3 one hundred one one hundred four fifty one fifty thirty

As can be seen from table 1, for the UE relatively low productivity of 50-100 m ³ / h, the value of the reserve is 50-100%. For high-capacity UOEs with an output of 200-400 m ³ / h, the capacity can vary over a wide range of workloads, and therefore UOs can include work modules of various unit capacities, and correspondingly similar combinations will also occur in the reserve modules. For example, with one or two working modules with a capacity of 50 or 100 m ³ / h, as a rule, the DOE includes one more standby module, designed for 50-100% redundancy, which during periods of prolonged downtime, it is advisable to use it as the second stage of DOE for permeate.

The same organization of the scheme can take place with a stable productivity of UOO of 400 m ³ / h, i.e. with four working modules of 100 m ³ / h and two reserve ones of 100 m ³ / h.

With a DOE productivity, for example, in the range of 100-300 m ³ / h, the working modules can include one module 100 m ³ / h and four modules of 50 m ³ / h each, and only one module with a capacity of 50 m ³ / can be redundant hours In this case, the optimal organization scheme for DOE will include the supply of concentrate of all working modules to the standby module of 50 m ³ / h. The same organization of the scheme can take place with a stable productivity of UOO of 400 m ³ / h, i.e. with four working modules of 100 m ³ / h and one standby - 100 m ³ / h.

With four or more working modules of different unit capacities, two or more redundant modules of different capacities can also be included in the DOE structure. For example, with a DOE capacity in the range of 300-400 m ³ / h, the working modules may include three modules of 100 m ³ / h and two modules of 50 m ³ / h, and the backup modules may include one module with a capacity of 100 m ³ / h and one module 50 m ³ / h. In this case, the optimal organization scheme for the DOE will include the permeate supply of all working modules to the standby module with a capacity of 100 m ³ / h, and the concentrate of all working modules to the standby module 50 m ³ / h.

Possible options for the implementation of DOE with a high degree of maneuverability of the working modules. So, when changing the productivity of the DOE in a wide range, for example, from 50-100 m ³ / h to 300-500 m ³ / h, as well as when the operating mode of the DOE, providing for long periods of work with a low of 50-100 or an average of 200-250 m ³ / h capacity, idle working modules are connected in series to working modules through the line of permeate or concentrate.

Figure 1, as one example of the implementation of the invention, schematically depicts a demineralization system with DOE, in which all redundant modules are used to further desalinate part of the permeate of the working modules; figure 2 is the same with DOE, in which the backup module is used for additional desalination of the concentrate of the working modules; figure 3 is the same with DOE, in which one of the two backup modules is used for additional desalination of a part of the permeate of the working modules, and the other for additional desalination of the concentrate of the working modules; figure 4 is the same with the DOE, in which on the concentrate line an intermediate tank and a filter unit are additionally included for purifying the concentrate from metal oxides and organic compounds before being fed to the reserve module. Also provided is a variant of the UO system not shown in the drawing, in which each working module can be used for additional desalination of permeate or concentrate of other working modules.

The natural water desalination system according to the invention comprises a pretreatment unit UPR 1 with a feed line 2 for supplying water thereto. The UPR may include clarifiers and clarification filters and / or micro- and / or ultrafiltration units not shown in the drawing. In addition, the UPR may include an antiscalant dosing unit or an ion-exchange unit (Na-cationite with acidification or H-cationite). The desalination system also contains connected to the UPR 1 line 3 of purified water UOO 4 with membrane modules, respectively 5-10, some of which (5-8 in figures 1, 3, 4; 5-9 in figure 2) are working, and the rest - backup. Each module is equipped with a source water supply line 11, a permeate line 12 and a concentrate line 13. Lines 11 of all membrane modules are connected by a purified water collector 14, lines 12 by a permeate collector 15, lines 13 by a concentrate collector 16 (FIGS. 2, 4). In the embodiment of FIG. 1, the collector 16 combines the lines 13 of only the working modules 5-8, and the lines 13 of the redundant modules 9, 10 are combined by the collector 17. In the embodiment of FIG. 3, the collector 16 combines the lines 13 of all modules except the backup module 9, line 13 of which connected to line 3 at the entrance to DOE 4. In all cases, a permeate discharge line 18 to the demineralized water consumer is connected to the collector 15. In the embodiment of FIG. 2, line 19 connects the permeate line 12 of the standby module 10 to the purified water line 3. According to the variant of figure 3, the collector 15 in the area of the working modules 5-8, the line 20 is connected to the line 11 of the backup module 9, and the line 12 of the latter is connected to the permeate removal line 18 to the consumer by a separate line 21. The line 11 of the backup module 10 is connected to the concentrate collector 16 on the site of the working modules 5-8, and line 12 of this backup module is connected by line 19 to line 3 of purified water. According to the embodiment of FIG. 4, the desalination system further comprises an intermediate container 22 for collecting the concentrate of working and reserve modules coming from the collector 16 via line 23, a filtering unit 24 for cleaning the concentrate coming from the tank 22, and a tank 25 with a scale inhibitor connected to line 11 standby module 9 using line 26. In all cases, a discharge line 27 is connected to the concentrate collector 16. To provide the ability to switch backup and working modules to parallel or sequential operation, shut-off valves are provided in the form of shut-off valves, in particular, on manifold 14, valves 28 (Figs. 1-4) and 29 (Figs. 3, 4), on collector 15 - valves 30 (Figs. 1-4), 31 (Figs. 1, 3, 4) and 32 (Fig. 3), on manifold 16 - valve 33 (Figs. 2, 3, 4), on manifold 17 - valve 34 (figure 1), on line 19 - valve 35 (figure 2, 4), on line 20 - valve 36 (figure 1, 3, 4), on line 21 - valve 37 (figure 1, 3) , on the line 23 - the valve 38 (figure 4), on the line 27 - the valve 39. In an embodiment not shown in the drawing systems With DO, in which each working module can be used for additional desalination of permeate or concentrate of other working modules, all the necessary strapping lines are equipped with similar shut-off valves.

The desalination system according to the invention (Figs. 1-4) works as follows. The source water treated on the UPR 1, enters the working modules 5-8 (figure 1, 3, 4), 5-9 (figure 2) UOO 4. Part of the permeate of the working modules (or the entire permeate flow rate at 100% redundancy) is supplied to the redundant modules 9, 10 (Fig. 1, 3), 10 (Fig. 2), 9 (Fig. 4) in the absence of the need to connect them for their intended purpose. The permeate of the backup modules can be mixed with the permeate of the working modules (or demineralized water tanks not shown in the drawing). According to the variant of FIG. 1, the permeate of the working modules 5-8 can be partially supplied via line 20 to the inputs of the backup modules 9, 10, and part of the concentrate of the latter through the collector 17 to the UOO 4 input to the purified water line 3 or to an intermediate tank not shown in the drawing purified water after the UPR 1. According to the variant of FIG. 2, part of the permeate of the working modules 5-9 through line 19 can be fed into line 3 before entering the UOF 4, and part of the concentrate through valve 33 to the input of the backup module 10. According to the variant of FIG. 3 part of permeate of working modules 5-8 can be filed according to AI 20 to the input of the backup module 9, and part of the concentrate through the valve 33 to the input of another backup module 10. According to the variant of figure 4, the concentrate of the working modules 5-8 in order to avoid disturbance of the hydraulic uniformity of supply to the backup modules can be assembled in an intermediate tank 22, and then fed to the input of the backup module 9. Depending on the content of various impurities in the treated water, the concentrate of the working modules can be further purified from metal oxides and organic impurities before entering the reserve module 9 on the filter unit 24, which can be a clarification, micro- or ultrafiltration unit, or ion-exchange filters. If the concentrate contains poorly soluble compounds close to the state of supersaturation, it can additionally be treated with a scale inhibitor coming from tank 25, for example, a complexing agent with cations of poorly soluble compounds.

Example 1. The clarified water after pre-treatment, treated with an antiscalant dose of 3-4 g / m ³ , is fed to UOO 4, which operates with a stable capacity of 420 m ³ / h (Fig. 1). The UE structure includes modules with a single capacity of 110 m ³ / h (4 workers, 2 standby). Part of the permeate of the working modules 5-8 with a flow rate of 220 m ³ / h is fed to the input of the backup modules 9,10, the permeate of which in the amount of 200 m ³ / h is fed to the mixing with the permeate of the working modules 220 m ³ / h. The concentrate of reserve modules in the amount of 20 m ³ / h is discharged for mixing with clarified water before DOE 4. Table 2 shows the composition of clarified water, permeate of working and standby modules, demineralized water of DOE and concentrate of working modules. As can be seen from table 2, the use of redundant modules improved the permeate quality by about 1.8 times in almost all indicators. When preparing additional water for boilers of medium (4.0 MPa) and high (9.8 MPa) pressure, UOO permeate, as a rule, is softened with Na filters. In the preparation of additional water for boilers with high (13.8 MPa) pressure, UOO permeate, as a rule, is further desalted on H-OH filters. Improving the quality of permeate by 1.8 times can accordingly reduce the ionic load on these filters and reduce the consumption of reagents (NaCl in the first case, acid and alkali in the second), as well as reduce the permeate consumption for own needs.

table 2 Quality indicators Cleanse. water before uoo Permeate Concentrate slave. modules work modules backup modules UOO Na, mg / dm ³ 13.0 0.26 0.016 0.144 63.8 Mg, "-" 16.1 0.16 0.01 0,088 79.8 Ca, "-" 66.6 0.66 0.04 0.36 330,4 CO ₃ , "-" 0.36 0,0 0,0 0,0 9,4 HCO ₃ , "-" 198.0 2.7 0.32 1,56 1150 Cl, "-" 18.9 0.38 0,03 0.21 94.0 SO ₄ , “-” 38.8 0.4 0,03 0.22 193.0 SiO ₂ , "-" 6.6 0,07 0.007 0,039 32.6 CO ₂ , “-” 14.95 2.79 2.66 2.74 18.6 Saline. 395 6.6 0.46 3.65 1955 pH 7.35 6.0 5.31 5.75 7.86 Electric wire. æ, μS / cm - 13,2 0.92 7.3 -

Example 2. Softened and decarbonized water after the UPR 1 is fed to UOO 4, operating with a stable capacity of ~ 250 m ³ / h (figure 2). The UE structure includes modules with a single capacity of 50 m ³ / h (5 workers, 1 standby). In the operating mode using the backup module 9 for concentrating the concentrate of working modules 5-8, 65 m ³ / h of softened decarbonized water is supplied to each working module. The entire concentrate of working modules with a flow rate of 54 m ³ / h is fed to the input of the backup module, the permeate of which in the amount of 48.1 m ³ / h is fed to mix with the source water of the working modules. The concentrate of the backup module 9 in the amount of 5.9 m ³ / h according to one of the options (not shown in the drawing) can be collected in a tank with its subsequent supply to the regeneration of Na-cation exchange filters. Table 3 shows the indicators of the composition of softened and decarbonized water before DOE, permeate of workers and reserve module and concentrate of workers and reserve module. As can be seen from table 3, the use of the backup module allowed to reduce the concentrate consumption by ~ 10 times, and it is also useful to utilize it for the regeneration of Na-cation exchange filters. In addition, the utilization of the permeate of the working module by mixing with the source water of the working modules improves the quality of their permeate and reduces the need for purified water after UPR.

Table 3 Composition indicators Cleanse. water before uoo Permeate Concentrate working m-lei reserve. modules work modules reserve. module Hardness, mg / DM ³ 0.08 0,00084 0,048 0.48 4.4 Ca ²⁺ , "-" 0.06 0,0006 0,036 0.36 3.3 Mg ²⁺ , "-" 0.02 0,00024 0.012 0.12 1,1 Na, - "-" 192 3.0 12 1156 10607 CO ₃ ^2- , "-" 0,0 0,0 0,0 2.1 19.8 HCO ₃ , "-" 12,2 0.5 1.4 70 626 Cl ^- , "-" 141.4 2.0 9 846 7756 SO ₄ ^2- , "-" 200 2.0 13 1190 11136 SO ₃ ^2- , "-" 3,5 0.04 0.25 21 196 CO ₂ , “-” 3.95 3.8 four 5,0 11.6 Salinity, "-" 549.2 7.6 40 3309 30346 æ, μS / cm 1090 15,2 80 6620 60700 We oxidize., MgO / dm ³ 0.5 0,0 0,0 3 27.5 Fe, μg / dm ³ 5,0 0,0 0,0 thirty 275

Example 3. Softened and decarbonized water after UPR 1 with a high content of iron oxides and organic compounds is fed to UOO 4, operating with a stable capacity of 250 m ³ / h (Fig. 4). The composition of the DOE and the sequence of operations using the backup module are similar to example 2. The difference is that the concentrate of the working modules, containing elevated concentrations of iron oxides and organic compounds, is collected in a tank 22 and is cleaned in a filter unit 24 before being fed to the backup module 9. Table 4 shows the indicators of the composition of softened and decarbonized feed water UOO, permeate workers and reserve module, demineralized water UOO, concentrate working modules before and after purification tissue and concentrate backup module. As can be seen from table 4, the purification of the concentrate of the working modules on the filter unit allows you to deeply remove contaminants (organic and iron) that impede further concentration of the concentrate on the backup module. The achieved positive results in this example are similar to example 2.

Table 4 Composition indicators Cleanse.
water before uoo Permeate Concentrate slave m-lei reserve. m-lei working modules backup module before cleaning. after cleaning Hardness, mg / DM ³ 0.08 0,0008 0,048 0.48 0.48 4.4 Ca ²⁺ , "-" 0.06 four 0,036 0.36 0.36 3.3 Mg ²⁺ "-" 0.02 0,0006 0.012 0.12 0.12 1,1 Na, - "-" 192 0,0002 12 1156 1156 10607 CO ₃ ^2- , "-" 0,0 four 0,0 2.1 2.1 19.8 HCO ₃ , "-" 12,2 3.0 1.4 70 70 626 Cl ^- , "-" 141.4 0,0 9 846 846 7756 SO ₄ ^2- , "-" 200 0.5 13 1190 1190 11136 SiO ₃ ^2- , "-" 3,5 2.0 0.25 21 21 196 CO ₂ , “-” 3.95 2.0 four 5,0 5,0 11.6 Salinity, "-" 549.2 0.04 40 3309 3309 30346 æ, μS / cm 1090 3.8 80 6620 6620 60700 We oxidize., MgO / dm ³ 2.5 7.6 0,0 14.5 2.9 26.5 Fe, μg / dm ³ 50,0 15,2 0,0 300 thirty 275

Information sources

1. Building norms and rules (SNiP 2.04.02-84). Water supply. External networks and facilities. Section 6.7. Moscow. 1984.

2. Patent SU 1820895, C02F 1/42, 1991.

Claims (10)

1. A natural water desalination system comprising a pre-treatment unit and a reverse osmosis unit on membrane elements with at least one desalination stage, each stage comprising at least one working water, permeate and concentrate collectors connected in parallel with cut-off valves and at least one working and at least one redundant module, characterized in that at least at the output stage of the reverse osmosis installation, permeate or concentrate collectors in the connection section p These modules are connected through an additional shutoff valve in series with the input of at least one backup module of the same stage. 2. The system according to claim 1, characterized in that each working module of at least the output stage of the reverse osmosis installation is additionally connected through shut-off valves in series with each of the other working and backup modules of the same stage along the permeate or along the concentrate. 3. The system according to claim 1 or 2, characterized in that between the concentrate collector of the output stage of the reverse osmosis unit and the backup modules, an intermediate tank and a filter unit for cleaning the concentrate from metal oxides and / or organic compounds are sequentially connected. 4. The system according to claim 1 or 2, characterized in that between the concentrate collector of the output stage of the reverse osmosis unit and the backup modules, the dosing unit of the reagent - scale inhibitor is turned on. 5. The system according to claim 3, characterized in that between the filter unit and the backup modules, a dosing unit of a reagent - scale inhibitor is turned on. 6. A natural water desalination system, comprising a pre-treatment unit and reverse osmosis unit on membrane elements with at least one desalination stage, each stage comprising at least one working water, permeate and concentrate collectors connected in parallel with cut-off valves and at least two redundant modules, characterized in that at least at the output stage of the reverse osmosis installation, permeate and / or concentrate collectors in the connection section Static preparation modules are connected via a further shut-off valve in series with the input of at least one backup module of the same stage. 7. The system according to claim 6, characterized in that each working module of at least the output stage of the reverse osmosis installation is additionally connected through shut-off valves in series with each of the other working and backup modules of the same stage along the permeate or along the concentrate. 8. The system according to claim 6 or 7, characterized in that between the concentrate collector of the output stage of the reverse osmosis unit and the backup modules, an intermediate tank and a filter unit are sequentially connected for cleaning the concentrate from metal oxides and / or organic compounds. 9. The system according to claim 6 or 7, characterized in that between the concentrate collector of the output stage of the reverse osmosis unit and the backup modules, the dosing unit of the reagent - scale inhibitor is turned on. 10. The system of claim 8, characterized in that between the filter unit and the backup modules, a dosing unit of a reagent - scale inhibitor is turned on.

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