RU2322402C2 - System for ion-exchange chemical purification and reverse-osmosis water desalting for boilers at heat-and-power stations - Google Patents

Abstract

FIELD: water treatment.

SUBSTANCE: objective of invention is providing consumers with chemically purified and/or desalted water or mixture thereof. System according to invention comprises, in series connected, water clarification unit, ion-exchange filter unit including chemically purified water line, and reverse-osmosis desalting unit including permeate and concentrate lines. In addition, system comprises supplementary unit for concentrating solutions and producing desalted water with concentrate and desalted water line. Concentrate line and line for withdrawal of concentrate from boilers are linked to solution concentration and desalted water production unit. Concentrate line of the latter unit is linked to ion-exchange filter unit and desalted water line from the same to boiler feed water line. Preferably, when productivity of reverse-osmosis desalting unit is insufficient, chemically purified water line can be connected to unit for concentrating solutions and producing desalted water.

EFFECT: reduced up to complete elimination consumption of commercial sodium chloride for regeneration of filters (at ion-exchange filter unit), reduced up to complete elimination waste water stream, increased percentage of desalted water obtained from chemically purified water, and reduced consumption of fresh water.

2 cl, 3 dwg, 1 tbl

Description

The invention relates to the field of thermal and industrial energy and can be used to obtain chemically purified and / or demineralized water or a mixture thereof for boilers of thermal power plants (TPPs).

Currently, at a number of TPPs, a system is used to obtain demineralized water, which contains a series-connected water clarification (UO) installation, a chemical purification (treatment) installation of clarified water on Na-, H-Na-cationite or Na-Cl-ionite filters (UIF) , desalting installation of reverse osmosis (UOO) [1] - analogue. Desalted water is supplied from the treatment system to the power of high-pressure steam boilers (13.8 MPa).

At a number of other TPPs, to obtain a mixture of demineralized (decremedized) and chemically purified water, a system is used that contains sequentially activated carbon monoxide, a chemical treatment (treatment) unit for clarified water at a UIF (Na-cation filter), and a demineralized UVR [2] - an analogue. The resulting mixture is also fed to high pressure boilers (9.8 MPa). The disadvantages of these known systems are: significant consumption of salable NaCl for the regeneration of Na-filters; increased discharge of salt effluents (UO concentrate, spent Na-filter solution); significant discharge of salts with the purge water of the boilers (as applied to the analogue [2]).

Known for the purpose and technical essence of the proposed invention is a system of ion-exchange chemical treatment and reverse osmosis desalination of water for powering boilers of thermal power plants, each of which is equipped with a drainage line of desalted water concentrate containing serially connected UO of water, a UIF with a line of chemically purified water and a desalting UO with permeate lines and concentrate [3] is a prototype. According to the latter, softened water after the installation of Na-cation is supplied to the UO and to the power of medium-pressure boilers, demineralized water after the UO is supplied to the power of high-pressure boilers. Thus, at the facility under consideration there are boilers - consumers of both chemically purified and demineralized water. The disadvantages of the prototype are the same as those of the analogues: the non-use of the large reserve of sodium salts in the system in the form of dilute solutions (UO concentrate, purging medium-pressure boilers), increased discharge of salt effluents and water consumption for own needs. In addition, the autonomy of work on water consumption and sanitation of boilers - consumers of demineralized and chemically purified water leads to a low value of the coefficient of desalinated water from chemically purified. In general, the system according to the prototype is characterized by insufficient environmental perfection.

Achievable results of the invention are: a significant reduction up to the complete elimination of the cost of salable NaCl for regeneration of UIF Na filters due to the use of the sodium salt reserve in the system in the form of dilute solutions; a significant reduction up to the complete exclusion of wastewater costs (concentrate from DOE and purge water from boilers - consumers of chemically treated water); reduction of water consumption for own needs of a chemical treatment and desalination system; increase in the rate of desalted water from chemically purified; reduction in source water consumption.

These results are ensured by the fact that the system of ion-exchange chemical treatment and reverse osmosis desalination of water for powering boilers of thermal power plants, each of which is equipped with a drainage line for demineralized water concentrate containing serially connected UO of water, a UIF with a line of chemically purified water and UO with lines of permeate and concentrate, according to the invention contains an additional installation for concentrating solutions and obtaining demineralized water (UKiO) with lines of concentrate and demineralized water, and the line of concentrate UO O and the concentrate discharge line from the boilers are connected to the UKiO, the UKiO concentrate line is connected to the UIF, and the demineralized water line from UKiO is connected to the boiler feed water line. In this case, a chemically purified water line can be connected to the UKiO.

Figure 1 as an example implementation of the invention schematically depicts a system of ion-exchange chemical treatment and reverse osmosis desalination of water to feed chemically purified water UO and medium pressure boilers and permeate UO - high pressure boilers. This system additionally provides for UKiO; figure 2 - as another example implementation of the invention is a system for supplying high pressure boilers with a mixture of demineralized and chemically purified water; figure 3 - as another example implementation of the invention, a system for supplying chemically purified water UOO and permeate UO - high pressure boilers.

The system according to the invention contains serially connected UO 1 as part of a clarifier (O) 2, a clarified water tank (BOV) 3, mechanical (clarifying) filters (M) 4, as well as a source water line 5, a clarified water line 6, a water supply line 7 washing mechanical filters 4, lines 8 of the drain from the filters 4 washed contaminants; installation of UIF 9 as a part of Na-cation exchange filters (Na) 10, softened water tank (BFS) 11, line 12 for the removal of softened water from Na-cation exchange filters 10 in BUV 11, line 13 of chemically purified (softened) water to supply UOO, line 14 drainage of regeneration solution (PP) to clarifier 2, line 15 of drainage of excess PP to discharge and line 16 of chemically purified (softened) water for supply to the consumer; desalting UOO 17 with permeate and concentrate lines 18 and 19, permeate tank (BP) 20 and permeate discharge line 21 to the consumer, respectively; additional installation for concentrating solutions and obtaining demineralized water (UKiO) 22 as part of the purge water collection tank (BSP) 23, evaporator (I) 24, condenser (K) 25, evaporator concentrate tank (BKI) 26, purge water supply line 27 from tank 23 to the evaporator 24, the distillate discharge line 28 through the condenser 25 to the permeate discharge line 21 to the consumer, the evaporator concentrate discharge line 29 to the BKI 26 and the supply line 30 of the specified concentrate for regeneration of the Na-cation exchange filter 10. The demineralized water consumer in FIG. 1 represented by steam high-pressure scrap (HPC) 31 with feed water deaerator (D) 32, and a consumer of chemically treated water with a medium-pressure steam boiler (KSD) 33 with deaerator 34. KVD 31 and KSD 33 have steam pipelines of 35 and 36 hot steam (OD), respectively as well as lines 37 and 38 respectively purge boiler water; deaerators 32 and 34 are lines 39 and 40 of the supply of heating steam (GP), respectively, lines 41 and 42 of the discharge of the steam-air mixture (PVA), respectively, and lines 43 and 44 of the supply of deaerated water to the respective boilers, respectively. In FIGS. 2 and 3, the consumer is represented only by HPC 31, moreover, in the examples of FIGS. 1 and 3, the power of these boilers is made with demineralized water, and in the example of FIG. 2 - with a mixture of demineralized and chemically purified water, for which the BUV 11 is connected to the deaerator 32 line 16.

The system according to the invention (figures 1, 2, 3) works as follows. The initial water is preliminarily supplied to UO 1, where clarifier 2 and mechanical filters 4 are passed sequentially. The clarified water enters UIF 9 with Na-cation exchange filters 10. Chemically purified (softened) water through line 13 is supplied to UOE 17 and through line 16 to KSD 33 through the deaerator 34 (figure 1). Permeate from UOO 17 through BP 20 through line 21 through deaerator 32 is supplied to the HPC 31, concentrate along line 19 is sent to concentration in UKO 22 (in this example, evaporator 24). There also purge water (concentrate) KSD 33 enters along line 38 (Fig. 1) or purge water KVD 31 along line 37 (Fig. 2). Concentrate UKiO 22 through line 29 is fed to the regeneration of Na-cation exchange filters 10. The distillate UKiO 22 through line 28 is fed to HPC 31. The purge of the latter (Fig. 1), which is actually demineralized water, is fed through line 37 to power KSD 33. When insufficient productivity UOO 17 (Fig. 3) chemically purified water along line 13 (shown in dotted lines in Fig. 3) is also supplied to UKiO 22, which makes it possible to increase the production of demineralized water and sodium salt concentrate for the regeneration of Na-cation exchange filters.

Example. Water r. Kama after processing in UO 1 (Fig. 1) enters the UIF and undergoes Na-cation on countercurrent filters 10 loaded with strongly acid cation exchange resin (KU-2-8). Then 30% of deeply softened water is supplied for reverse osmosis desalination in UOO 17 and 70% for power supply of KSD 33. UOO 17 is equipped with BW membrane elements operating at pressures up to 1.6 MPa. The resulting permeate is fed to the HPC 31. The concentrate UOO 17 and the purge KSD 33 are fed to the evaporator 24 UKiO 22. The table shows the compositions of clarified, Na-cationized water, permeate and concentrate UO, purge water KSD and the concentrate of the evaporator. As can be seen from Table 1, the sodium content in clarified water exceeds the hardness content by 2.8 times (in equivalent units) with respect to stoichiometry, which is quite sufficient for the regeneration of Na-cation exchange filters. In softened water after Na-cation exchange filters, the sodium content increases by the amount of hardness. Thus, provided that the softened water is concentrated by a factor of 5 by 10% and by 10 times by KSD ~ and a concentration of a mixture of these concentrates is evaporated by a factor of ~ 40, we obtain an evaporator concentrate with a sodium salt content of 9.9%.

Table 1 Composition indicators Clarified water Na-cationic water Concentrate OOU Blowdown KSD Evaporator Concentrate Hardness, mEq / dm ³ 1.4 0.005 0,025 0.05 0.15 Ca ²⁺ , - "- 0.6 0.003 0.015 0,03 0.09 Mg ^2+, - «- 0.4 0.002 0.01 0.02 0.06 Alkalinity, - "- 1,0 1,0 5,0 7.0 16,0 Na, mg / dm ³ 91.2 137 665 1330 3990 Cl ^{-, - «-} 122 122 610 1220 3660 SO ₄ ^2- , - “- 43 43 210 420 1260 SiO ₃ ^2- , - “- 3.0 3.0 14.8 29.0 87.0 Salt content, - "- 318 325 1550 3300 9900 Conducting., - "- - 570 - - - COD, mgO / dm ³ 1,2 1,0 3,5 5,0 10.0

The indicated concentration is quite acceptable for the regeneration of Na-cation exchange filters, and the sodium content in the evaporator concentrate will be 3.8 times higher than the number of hardness cations absorbed by the Na-cation exchange filters per unit time. Since the indicated amount of sodium significantly exceeds the needs of Na-cation exchange filters for regeneration, part of the purge water of KSD or UO can be used for own needs (loosening leaching) of Na-cation exchange filters.

Information sources

1. Experience in the implementation of the reverse osmosis installation OOU-166 at Nizhnekamsk TPP-1 / B.N. Khodyrev, B.S. Fedoseev, A.I. Kalashnikov et al. // Electric stations. 2002, No. 6, p. 51, 61.

2. Operating experience of reverse osmosis water desalination plants at thermal power plants and in industrial boiler houses / Askernia AA, Malakhov IA, Korabelnikov VM // Thermal engineering, 2005, No. 7, p.20.

3. Operating experience of reverse osmosis water desalination plants at thermal power plants and industrial boiler rooms / Askernia AA, Malakhov IA, Korabelnikov VM // Thermal engineering, 2005, No. 7, p.24.

Claims (2)

1. The system of ion-exchange chemical treatment and reverse osmosis desalination of water for feeding boilers of thermal power plants, each of which is equipped with a drainage line for desalted water concentrate, containing a water clarification unit (UO), a clarified water treatment unit on ion-exchange filters (UIF) with a chemically purified water line and a desalination reverse osmosis unit (UOO) with lines of permeate and concentrate, characterized in that it contains an additional installation for concentrating Hur and producing desalinated water (UKIO) with lines concentrate and demineralized water, the DOE concentrate line and concentrate outlet line from boiler connected to UKIO, UKIO concentrate line is connected to the UIF, and demineralized water from line UKIO - a boiler feedwater lines. 2. The system according to claim 1, characterized in that a chemically purified water line is connected to the UKiO.

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