CN217287929U - Cleaning and regenerating device for waste reverse osmosis membrane of thermal power plant - Google Patents
Cleaning and regenerating device for waste reverse osmosis membrane of thermal power plant Download PDFInfo
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Abstract
The utility model discloses a cleaning and regenerating device of a waste reverse osmosis membrane of a thermal power plant, which comprises a membrane component, a chemical cleaning component, a clear water washing component and a gas washing component, wherein the chemical cleaning component, the clear water washing component and the gas washing component are communicated with the membrane component; the chemical cleaning component comprises a cleaning water tank, a pipeline I, a booster pump, a pipeline II, a pipeline III, a pipeline IV, a pipeline V, a pipeline VI and a pipeline VII which are sequentially communicated; the clear water washing component comprises a washing water tank, a pipeline eight, a pipeline nine and a drain pipe I; the air washing component comprises a compressed air source and a pipeline ten; the flushing water tank and the cleaning water tank are both communicated with a water replenishing pipe and a trench; the cleaning regeneration process adopts a mode of combining physical cleaning and chemical cleaning to carry out off-line cleaning on the abandoned reverse osmosis element, and carries out deep cleaning on the abandoned reverse osmosis element by a process mode of combining positive and negative cleaning of a cleaning solution and combining gas-liquid two-phase cleaning, so that the cleaning effect is good, the cleaning efficiency is high, and the regeneration of the abandoned reverse osmosis element can be realized.
Description
Technical Field
The utility model relates to a permeable membrane treatment technical field, more specifically the washing regenerating unit who relates to a waste reverse osmosis membrane of steam power plant that says so.
Background
The reverse osmosis technology is the most efficient and widely applied water desalination technology in the field of boiler water preparation of thermal power plants at present. However, the composite polyamide membrane inevitably generates membrane pollution after running for a certain time. The service life of a general commercial low-pressure reverse osmosis membrane is about 3 to 5 years, and the number of membrane elements discarded each year after exceeding the service life is millions, which not only brings high membrane replacement and waste membrane treatment cost to a thermal power plant, but also may bring huge environmental risks. Although the rejection rate, the filtering performance and the like of the waste reverse osmosis membrane are reduced to some extent, the waste reverse osmosis membrane still keeps a complete main body structure and can be recycled in a scene with low requirement on the quality of produced water through proper treatment.
The membrane cleaning is a key step of the pretreatment of the cyclic utilization of the waste reverse osmosis membrane. The transmembrane pressure difference of the waste membrane is reduced through membrane cleaning, so that the operation cost of waste membrane recycling can be reduced, and the economy of waste membrane recycling is improved. In the conventional cleaning process, most of cleaning agents enter the membrane from the water inlet end of the membrane, and after the cleaning agents contact and react with pollutants on the membrane surface, the cleaning agents are flushed out of the membrane from the concentrated water end of the membrane along with water flow. However, for organic matters and microorganism pollution mainly concentrated at the water inlet end of the membrane, the cleaning agent is adopted to reversely enter the membrane from the concentrated water end of the membrane (namely the cleaning agent is used for forward washing), so that pollutants are instantly flushed out of the membrane from the water inlet end of the membrane, and the pollutants can be prevented from adhering to the surface of the membrane again along with the downstream flow of the cleaning agent. Zulili provides a bidirectional reverse osmosis cleaning device in which cleaning fluid can enter from a water inlet end and also can enter from a concentrated water end, but related literature reports are few. In addition, in the gas-liquid two-phase cleaning process, the introduction of gas increases the shearing force of the membrane surface and the turbulence degree of the cleaning liquid, so that the pollution layer is loosened and falls off to achieve a better cleaning effect. The gas-liquid two-phase cleaning is more mature in the micro-filtration and ultrafiltration membrane cleaning, but the related research aiming at the roll type reverse osmosis membrane cleaning is less.
Therefore, the problem to be solved by the technical personnel in the field is how to provide a reasonable cleaning device for cleaning a rolled reverse osmosis membrane to achieve the best cleaning effect so that the reverse osmosis membrane can be recycled.
SUMMERY OF THE UTILITY MODEL
In view of this, the utility model provides a steam power plant abandonment reverse osmosis membrane's washing regenerating unit, this washing regeneration technology adopt physics to wash and carry out the off-line washing to the dumped reverse osmosis component with the mode that chemical cleaning combined together, carry out the deep cleaning through the washing liquid positive and negative washing and the process method that the double-phase washing of gas-liquid combined together to the dumped reverse osmosis membrane component, and the cleaning performance is good, and the cleaning efficiency is high, can realize the regeneration of dumped reverse osmosis membrane component.
In order to achieve the above purpose, the utility model adopts the following technical scheme:
the utility model provides a cleaning and regenerating unit of waste reverse osmosis membrane of steam power plant, includes the membrane module, still includes: the chemical cleaning component, the clear water washing component and the air washing component are communicated with the membrane component;
the chemical cleaning component comprises a cleaning water tank, a pipeline I, a booster pump, a pipeline II, a pipeline III, a pipeline IV, a pipeline V, a pipeline VI and a pipeline VII which are sequentially communicated, the pipeline II is communicated with the water inlet end of the membrane component, and the pipeline III is communicated with the concentrated water end of the membrane component; the water inlet end of the first pipeline is provided with a valve V1, the water outlet end of the first pipeline is communicated with the second pipeline through a valve V2, the booster pump is arranged on the first pipeline, the third pipeline is communicated with the fourth pipeline through a valve V6, the fourth pipeline is communicated with the fifth pipeline through a valve V10, the water outlet end of the fifth pipeline is communicated with the cleaning water tank, the water outlet end of the fifth pipeline is provided with a valve V11, the sixth pipeline is communicated with the first pipeline and is provided with a valve V3, the water outlet end of the sixth pipeline is communicated with the fourth pipeline, and the seventh pipeline is communicated with the water inlet end of the membrane component, is provided with a valve V5, and the water outlet end of the seventh pipeline is communicated with the fifth pipeline;
the clear water flushing assembly comprises a flushing water tank, a pipeline eight, a pipeline nine and a drain pipe I, wherein the water inlet end of the pipeline eight is communicated with the flushing water tank and is provided with a valve V12, the water outlet end of the pipeline eight is communicated with the pipeline I, the water inlet end of the pipeline nine is communicated with the pipeline five, the water outlet end of the pipeline nine is communicated with the flushing water tank and is provided with a valve V13, and the drain pipe I is communicated with the pipeline three and the trench through a valve V8;
the gas washing assembly comprises a compressed gas source and a pipeline ten, wherein the gas inlet end of the pipeline ten is communicated with the compressed gas source, the gas outlet end of the pipeline ten is communicated with the pipeline two, and a valve V4 is arranged;
the flushing water tank and the cleaning water tank are communicated with a water replenishing pipe and a trench.
Further, the device also comprises a performance testing component;
the performance testing assembly comprises a testing water tank, an eleventh pipeline, a twelfth pipeline, a thirteenth pipeline, a pressure transmitter, an electromagnetic flowmeter, a conductivity meter, a vortex shedding flowmeter, a second drain pipe and a stop valve, wherein the water inlet end of the eleventh pipeline is communicated with the testing water tank and is provided with a valve V14, the water outlet end of the eleventh pipeline is communicated with the first pipeline, the water inlet end of the twelfth pipeline is communicated with the fifth pipeline and is provided with a valve V15, the water inlet end of the thirteenth pipeline is communicated with the water producing end and the water outlet end of the membrane assembly are communicated with the fourth pipeline through a valve V7, the pressure transmitter and the electromagnetic flowmeter are sequentially arranged on the third pipeline between the water inlet end and a connecting point of the drain pipe, the second drain pipe is communicated with the thirteenth pipeline and a trench through a valve V9, and the vortex shedding flowmeter and the conductivity meter are sequentially arranged on the thirteenth pipeline, the stop valve is arranged on the third pipeline between the pressure transmitter and the electromagnetic flowmeter.
Furthermore, the test water tank is connected with a first electric heater.
Furthermore, the cleaning water tank is connected with a second electric heater.
Furthermore, a security filter is arranged on the first pipeline and is arranged between the booster pump and a connection point of the sixth pipeline and the first pipeline.
Furthermore, a conductivity meter and a pressure transmitter are arranged on the second pipeline.
The utility model also provides a regenerating unit's waste reverse osmosis membrane's washing regeneration method of steam power plant based on as above technical scheme, including following step:
the method comprises the following steps: preparing a medicament: preparing a cleaning agent in a cleaning water tank for later use;
step two: washing machine
Washing in a normal way: opening a valve V1, a valve V2, a valve V6, a valve V10, a valve V11 and a booster pump, opening a compressed air source and a valve V4 for air washing, closing the other valves, performing forward washing, and closing all the valves and the booster pump after the forward washing is finished;
backwashing: opening a valve V1, a valve V3, a valve V6, a valve V5, a valve V11 and a booster pump, carrying out backwashing, and closing all the valves and the booster pump after the backwashing is finished;
step three: rinsing with clean water
Opening the valve V12, the valve V2, the valve V8 and the booster pump for flushing, and closing all the valves and the booster pump after flushing is finished;
step four: performance testing
Opening a valve V14, a valve V2, a valve V6, a valve V7, a valve V10, a valve V15 and a booster pump, closing other valves, configuring 2000mg/L NaCl solution as test solution in a test water tank, adjusting the opening degree of a stop valve at a concentrated water end of a membrane module and the frequency of the booster pump to ensure that the water yield of the membrane module is fixed at 1.73m3/h and the recovery rate is fixed at 15 percent, and recording the water inlet pressure, transmembrane pressure difference and desalination rate by tests to obtain a regenerated membrane meeting the requirements,
wherein, the calculation formula is as follows:
transmembrane pressure difference calculation formula:
dP＝P f -P conc
in the formula P f For the pressure of water intake, P conc Is the pressure of the concentrated water, and the unit is KPa;
salt rejection calculation formula:
SR＝(uS f -uS p )/uS f ×100％
wherein SR is the salt rejection, uS f For water conductivity, uS p The water production conductance is in uS/cm.
Preferably, the cleaning agent is 0.1 wt% NaOH solution, 0.1 wt% NaOH +0.025 wt% SDS-Na solution or 0.2 wt% HCl, and the specific positive and negative cleaning comprises the following steps:
(8.1) after a cleaning agent solution is prepared in a cleaning water tank, opening a valve V1, a valve V2, a valve V6, a valve V10, a valve V11 and a booster pump, closing other valves, carrying out forward washing for 1h, and closing all the valves and the booster pump after the forward washing is finished;
(8.2) opening a valve V1, a valve V3, a valve V6, a valve V5, a valve V11 and a booster pump, backwashing for 1h, and closing the booster pump after backwashing is finished;
(8.3) standing and soaking for 2 hours, and then closing all valves;
(8.2) repeating steps (8.1) and (8.2) once, and then closing all valves and the booster pump.
Preferably, the cleaning agent is 0.1 wt% NaOH + compressed gas, and the specific washing comprises the following steps:
(9.1) after 0.1 wt% NaOH cleaning agent solution is prepared in the cleaning water tank, opening a valve V1, a valve V2, a valve V6, a valve V10, a valve V11, a valve V4, a booster pump and a compressed air source, carrying out forward cleaning for 1h, and closing the booster pump and the compressed air source;
(9.2) standing and soaking for 2 hours, opening the compressed air source and the booster pump, forward washing for 1 hour again, and then closing the booster pump, the compressed air source and all valves.
Preferably, the air inlet quantity of the compressed air source is 1-1.5m 3 The inlet pressure is 80-150kPa
Can know via foretell technical scheme, compared with the prior art, the utility model discloses a belt cleaning device and cleaning method of steam power plant's abandonment reverse osmosis membrane, through optimizing device structure and washing technological parameter, reach best effect, adopt the washing mode that different cleaner forward and reverse washing combined together to wash, transmembrane pressure difference to reducing the waste membrane has obvious effect, and it is lower to the membrane desalination damage, waste membrane element water production volume after the washing is about 1.5-2.5 times of new membrane, the desalination can reach 95-97.5%, can be at low energy consumption, high flux, recycle in the scene that the low desalination required, higher environmental protection value has.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is an overall structure diagram of a cleaning device for a waste reverse osmosis membrane of a thermal power plant of the present invention;
FIG. 2 is a diagram showing the effect of NaOH on cleaning waste films in the embodiment of the present invention;
FIG. 3 is a diagram showing the effect of NaOH + SDS-Na on the cleaning of waste membranes in the examples of the present invention;
FIG. 4 is a diagram illustrating the cleaning effect of HCl on waste films in the embodiment of the present invention;
FIG. 5 is a diagram showing the effect of NaOH + gas source on cleaning waste membranes in the embodiment of the present invention;
FIG. 6 is a comparison graph of water yield after the waste membrane is cleaned by NaOH, NaOH + SDS-Na, HCl, NaOH + air source in the embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
As shown in fig. 1, a cleaning and regenerating device for a waste reverse osmosis membrane of a thermal power plant comprises a membrane module 1, and further comprises: the chemical cleaning component, the clear water washing component and the air washing component are communicated with the membrane component 1;
the chemical cleaning component comprises a cleaning water tank 21, a first pipeline 22, a booster pump 23, a second pipeline 24, a third pipeline 25, a fourth pipeline 26, a fifth pipeline 27, a sixth pipeline 28 and a seventh pipeline 29 which are sequentially communicated, wherein the second pipeline 24 is communicated with a water inlet end of the membrane component 1, and the third pipeline 25 is communicated with a concentrated water end of the membrane component 1; the water inlet end of the first pipeline 22 is provided with a valve V1, the water outlet end of the first pipeline is communicated with the second pipeline 24 through a valve V2, the booster pump 23 is arranged on the first pipeline 22, the third pipeline 25 is communicated with the fourth pipeline 26 through a valve V6, the fourth pipeline 26 is communicated with the fifth pipeline 27 through a valve V10, the water outlet of the fifth pipeline 27 is communicated with the cleaning water tank 21, the water outlet end of the fifth pipeline is provided with a valve V11, the water inlet end of the sixth pipeline 28 is communicated with the first pipeline 22 and is provided with a valve V3, the water outlet end of the sixth pipeline is communicated with the fourth pipeline 26, the water inlet end of the seventh pipeline 29 is communicated with the water inlet end of the membrane module 1 and is provided with a valve V5, and the water outlet end of the seventh pipeline 27 is communicated with the first pipeline 27;
the clear water flushing assembly comprises a flushing water tank 31, a pipeline eight 32, a pipeline nine 33 and a drain pipe one 34, wherein the water inlet end of the pipeline eight 32 is communicated with the flushing water tank 31 and is provided with a valve V12, the water outlet end of the pipeline eight 32 is communicated with the pipeline one 22, the water inlet end of the pipeline nine 33 is communicated with the pipeline five 27, the water outlet end of the pipeline nine 33 is communicated with the flushing water tank 21 and is provided with a valve V13, and the drain pipe one 34 is communicated with the pipeline three 25 and the trench through a valve V8;
the gas washing assembly comprises a compressed gas source 41 and a pipeline ten 42, wherein the gas inlet end of the pipeline ten 42 is communicated with the compressed gas source 41, the gas outlet end of the pipeline ten 42 is communicated with the pipeline two 24, and a valve V4 is arranged;
the flushing water tank 21 and the cleaning water tank 31 are both communicated with a water replenishing pipe and a trench.
The device also comprises a performance testing component;
the performance testing assembly comprises a testing water tank 51, a pipeline eleven 52, a pipeline twelve 53, a pipeline thirteen 54, a pressure transmitter 55, an electromagnetic flow meter 56, a conductivity meter 57, a vortex flow meter 58, a drain pipe two 59 and a stop valve 60, wherein the water inlet end of the pipeline eleven 52 is communicated with the testing water tank 51 and is provided with a valve V14, the water outlet end of the pipeline eleven 52 is communicated with the pipeline one 52, the water inlet end of the pipeline twelve 53 is communicated with the pipeline five 27, the water outlet end of the pipeline twelve 53 is communicated with the testing water tank 51 and is provided with a valve V15, the water inlet end of the pipeline thirteen 54 is communicated with the water production end of the membrane assembly 1, the water outlet end of the pipeline thirteen 54 is communicated with the pipeline four 26 through a valve V7, the pressure transmitter 55 and the electromagnetic flow meter 56 are sequentially arranged on the pipeline three 25 and positioned between the connection points of the water inlet end and the drain pipe one 34, the drain pipe two 59 is communicated with the pipeline thirteen pipeline 54 and a trench through a valve V9, the vortex flowmeter 58 and the conductivity meter 57 are sequentially arranged on the pipeline thirteen 54, and the stop valve 60 is arranged on the pipeline three 25 between the pressure transmitter 55 and the electromagnetic flowmeter 56.
In some specific modified schemes, an electric heater one 7 is connected to the test water tank 51.
In some specific modified schemes, the second electric heater 8 is connected with the cleaning water tank 31.
In some specific modified schemes, a security filter 9 is arranged on the pipeline one 22, and the security filter 9 is arranged between the booster pump 23 and the connection point of the pipeline six 28 and the pipeline one 22.
In some specific modified schemes, a first conductivity meter 241 and a first pressure transmitter 242 are arranged on the second pipeline 24.
The technical scheme of the utility model wash the test based on above-mentioned device, specifically wash regeneration object for by the high chemical durability of the model of east Li company of Lanxingdong TM720D-400, high desalination, high flux reverse osmosis membrane element. The membrane element is put into use as pretreatment of boiler make-up water in a certain thermal power plant in 2016, the filling position in the system is the first section, and the membrane element is replaced after running for 4 years. The type of a water source of the thermal power plant is surface water, and the pretreatment process before the reverse osmosis membrane is high-density sedimentation tank → air scrubbing filter tank → disc filter → ultrafiltration. In the pretreatment process, continuously adding a coagulant PAC into a high-density sedimentation tank; respectively and continuously adding oxidizing bactericide NaClO into a water inlet pipe of the high-density sedimentation tank and a UF water inlet pipe; and continuously adding a reducing agent and a scale inhibitor on the reverse osmosis water inlet main pipe.
The specific cleaning method comprises the following steps:
chemical cleaning: the cleaning modes are divided into three categories: forward washing, gas-liquid flushing and back washing. During forward washing, the valves V1, V2, V6, V10 and V11 are opened, the other valves are closed, and at the moment, the cleaning agent enters the waste membrane from the water inlet end of the membrane element after being pressurized by the booster pump, and flows back to the cleaning water tank from the concentrated water end after passing through the membrane element. When gas-liquid flushing is carried out, the valve V4 is opened, the opening and closing states of other valves are consistent with those of forward flushing, and at the moment, compressed air and a cleaning agent are mixed and then enter the membrane element; during backwashing, the valves V1, V3, V6, V5 and V11 are opened, and other valves are closed, so that the cleaning agent flows into the waste membrane from the concentrated water end and then flows out of the water inlet end into the cleaning water tank. The circulating flow is maintained at 9m by adjusting the frequency of the booster pump during circulating cleaning 3 /h～10m 3 The water inlet pressure is about 80kPa to 90 kPa.
Rinsing with clear water: opening valves V12, V2 and V8, and closing other valves, wherein clear water flows in from the water inlet end of the waste film, passes through the waste film and flows out from the concentrated water end to be discharged into a trench;
and (3) testing the performance of the membrane element: opening valves V14, V2, V6,V7, V10, V15, the other valves are closed. According to the performance test conditions of the membrane elements of the same type on Dongli handbook [5 ]]: 2000mg/LNaCl solution is prepared as a test solution, the opening degree of a stop valve at a concentrated water end and the frequency of a high-pressure pump are adjusted, so that the water yield of the membrane element is fixed at 1.73m 3 The recovery rate is fixed at 15 percent, and the temperature of the test solution is heated to 25 ℃; and testing and recording experimental data such as water inlet pressure, transmembrane pressure difference, desalination rate and the like.
Chemical cleaning can be divided into 4 types according to different selected agents and cleaning modes: 0.1 wt% NaOH, 0.1 wt% NaOH +0.025 wt% SDS-Na, 0.2 wt% HCl, 0.1% wtNaOH + air wash.
The 0.1 wt% NaOH cleaning and cleaning process comprises the steps of firstly carrying out forward backwashing for 1 hour respectively, then stopping pressure supply by the booster pump, standing and soaking the membrane element for 2 hours, then repeating forward backwashing for 1 hour respectively, and totally and completely cleaning for one time for 6 hours.
The washing procedure was the same as 0.1% NaOH, 0.025% SDS-Na and 0.2% HCl, 0.1% NaOH.
When the washing is carried out by 0.1 wt% NaOH and air, the washing process comprises the steps of forward washing for 1h, standing and soaking for 2h, and forward washing for 1h, wherein the time required for one-time complete washing is 4 h. The gas-liquid cleaning parameters are shown in table 1:
TABLE 1 gas-liquid cleaning parameters
According to the changes of the air inlet pressure, the air inlet flow and the cleaning liquid temperature, the most appropriate cleaning parameters are explored by combining the cleaning time.
The sequence of the total cleaning process is as follows: 0.1 wt% NaOH positive backwash, 0.1 wt% NaOH +0.025 wt% SDS-Na positive backwash, 0.2 wt% HCl positive backwash, 0.1 wt% NaOH + gas wash.
Firstly, data processing:
1) data normalization
The apparent performance of membrane elements is affected by the feed water composition, feed water pressure, temperature and recovery, for example: it is normal that the water yield decreases by about 3% for every 1 ℃ drop in temperature. The conditions of the concentration, the water inlet pressure, the temperature and the like of the test solution during the test can not be ensured to be completely consistent when the performance of the membrane element is tested every time. To distinguish such normal phenomena from the true changes in membrane element performance, the test data should be standardized. The initial performance of the new membrane element with the same model is taken as the reference performance for standardization, so that the influence of test parameters is considered, and the difference between the real performance of the membrane element and the reference performance can be reflected better. The data were standardized by Toray's professional standardization software Toray Trak software, including 3 items of standardized water yield, standardized salt rejection and standardized pressure difference.
2) Formula for calculation
Transmembrane pressure difference calculation formula:
dP＝P f -P conc
in the formula P f For water inlet pressure, P conc Is the pressure of the concentrated water, and the unit is KPa;
salt rejection calculation formula:
SR＝(uS f -uS p )/uS f ×100％
wherein SR is the salt rejection, uS f For water conductivity, uS p The water production conductance is uS/cm; II, testing results:
the cleaning effect of each cleaning agent is shown in figures 2-6,
effect of NaOH on cleaning waste film
The NaOH solution can react with microbial dirt, colloidal dirt and most of organic dirt such as grease, protein, algae and the like to loosen, emulsify and disperse the sediments. In the process of firstly cleaning the waste membrane by using 0.1 wt% of NaOH, the cleaning liquid is not obviously changed during forward cleaning, and the cleaning liquid is quickly and obviously turbid shortly after the forward cleaning is switched to the backwashing, so that pollutants are flushed out of the membrane, and a relatively ideal cleaning effect is achieved; in the process of cleaning the waste membrane again by using NaOH with the same concentration, the cleaning liquid has no obvious change no matter in the process of forward washing or back washing, which indicates that the cleaning effect is not ideal.
The changes in transmembrane pressure difference and salt rejection of the waste membrane after NaOH washing are shown in FIG. 2. After the membrane element is cleaned for 6 hours for the first time, the transmembrane pressure difference of the membrane element is reduced by about 10 percent, after the membrane element is cleaned for 6 hours continuously, the transmembrane pressure difference is almost unchanged, and the cleaning effect reflected by the transmembrane pressure difference is consistent with the change of the cleaning liquid in the cleaning process. After the membrane element is cleaned for the first time, the desalination rate of the membrane element is reduced by 1.1%, and after the membrane element is cleaned for the second time, the desalination rate is further reduced by 0.8%.
In conclusion: (1) the effect is ideal by adopting a mode of combining the forward washing and the reverse washing of the cleaning solution, and when the forward washing is switched to the reverse washing, the cleaning solution becomes turbid obviously, which indicates that pollutants are flushed out of the membrane; (2) the cleaning is carried out by adopting 0.1 wt% of NaOH, which has certain effect on reducing transmembrane pressure difference of the waste membrane, but can cause the reduction of the desalination rate of the waste membrane; (3) in addition, the cleaning time is prolonged by adopting NaOH, so that the effect of continuously reducing transmembrane pressure difference is not achieved, and the desalination rate of the membrane element is further damaged by the washing time, so that the cleaning time is not suitable to be too long.
Cleaning effect of (II) NaOH + SDS-Na on waste membrane
SDS-Na as the surface active agent can reduce the surface tension of molecules and improve the surface hydrophilicity of the membrane, so the SDS-Na can be matched with NaOH to effectively remove microorganisms and organic pollutants. When the waste film is cleaned for the first time by NaOH and SDS-Na, similar to the alkali cleaning process, after the forward cleaning is switched to the back cleaning, a large amount of yellow solid matters are adhered to the foam of the cleaning liquid, and the cleaning liquid is turned into turbid from clear; during the second cleaning, part of yellow solid matters still adhere to the foam of the cleaning liquid, and the cleaning liquid becomes turbid; during the third cleaning, the foam of the cleaning solution is basically free of yellow substances, and the cleaning solution still becomes turbid; and in the fourth cleaning, the foam of the cleaning liquid and the cleaning liquid are not obviously changed.
After the NaOH + SDS-Na washing, the transmembrane pressure difference and salt rejection of the waste membrane elements were varied as shown in FIG. 3, and the data of the last NaOH washing was used as the initial data of 0 point. After three times of cleaning, transmembrane pressure difference of the waste membrane is stably reduced, and is reduced by 6.4%, 6.8% and 5.1% in sequence from 47kPa of an initial value, and is finally reduced to 39kPa, and the total reduction is 17%; after the fourth wash, the transmembrane pressure difference did not decrease further than the last wash. The desalination rate of the waste membrane is basically maintained unchanged in the cleaning process, even slightly increased, and after 18 hours of accumulated cleaning, the desalination rate is increased by about 0.3% compared with that at the end of alkaline cleaning, and is recovered to 95.6%.
In conclusion: (1) the adoption of 0.1 wt% NaOH +0.025 wt% SDS-Na has a relatively ideal cleaning effect on the waste membrane, the transmembrane pressure difference of the cleaned waste membrane is obviously reduced, and the desalination rate of the waste membrane is kept unchanged or even slightly recovered before and after cleaning. (2) Comparing the results of the simple NaOH cleaning and the NaOH + SDS-Na cleaning, the NaOH + SDS-Na is warmer than the simple NaOH cleaning, can reduce the transmembrane pressure difference and does not damage the desalination rate of the waste membrane, and is more recommended cleaning agent. (3) When NaOH + SDS-Na is adopted to clean the waste membrane, the cleaning time needs to be ensured to be long enough, and the cleaning and soaking time in the experiment is recommended to be not less than 18 h.
(III) cleaning effect of HCl on waste film
The acidic reagent is mainly used for removing inorganic salt precipitate deposited on the surface of the film and can enable Mg 2+ 、Ca 2+ And dissolving inorganic salt scale. In the three cleaning processes of the waste film by using 0.2 wt% HCl solution, the cleaning solution has no obvious turbidity phenomenon. The transmembrane pressure difference and salt rejection of the spent membrane elements after acid washing were varied as shown in FIG. 4, with the results of the last NaOH + SDS-Na washing as initial data at 0. After three times of HCl pickling, transmembrane pressure difference of the waste membrane is further reduced slightly, and is reduced by about 7.7% in total compared with that before pickling; the desalination rate of the waste membrane is partially recovered after acid cleaning, the desalination rate is recovered to 97 percent from 95.9 percent before acid cleaning, and the desalination rate after recovery is equivalent to that of the waste membrane before cleaning. It can be seen that the recovery effect of the acid washing on the desalination rate of the membrane is better. This is because when the polyamide membrane having a low degree of crosslinking is brought into contact with a strongly alkaline solution, the oligomer packed between the membrane pores is dissolved under strongly alkaline conditions, causing the membrane pores to increase and the membrane surface to swell, resulting in a temporary decrease in the salt rejection rate of the membrane. This phenomenon is generally reversible, and the salt rejection of the membrane can be properly recovered by continuously flushing with clear water for a long time after alkaline washing; and the recovery of the desalination rate of the membrane can be accelerated by acid washing after alkali washing.
(IV) cleaning effect of gas-liquid two-phase cleaning on waste film
The steam-water pulse takes water as a medium, compressed air is injected into the pipeline as a driving force, the steam-water mixed fluid forms impact force and oscillation waves in the pipeline through the compression and expansion of the air, the violent flocculation flow increases the shearing force of the original water flow, and pollutants attached to the membrane and the grids can be effectively stripped. The cleaning liquid becomes turbid obviously during the first gas-liquid cleaning, and the cleaning liquid does not change obviously during the later gas-liquid cleaning. The cleaning effect of the gas-liquid two-phase cleaning on the waste film is shown in fig. 5, using the last 0.2 wt% HCl cleaning result as reference data. After the first gas-liquid cleaning, the differential pressure of the waste membrane is further reduced to 31kPa, which is almost the same as the differential pressure of a new membrane with the same type; the salt rejection increased slightly to 0.3%, to 97.3%, consistent with the salt rejection of the waste membranes before washing. When the gas-liquid cleaning is carried out for the second time, the air inlet pressure of the compressed air is improved; when the third and fourth times of gas-liquid cleaning are carried out, the air inlet pressure and the air inlet amount of the compressed air are improved simultaneously; and heating the cleaning liquid to raise the temperature during the fifth gas-liquid cleaning. The transmembrane pressure difference and the salt rejection rate of the waste membrane hardly change in the subsequent gas-liquid cleaning processes.
As a result, (1) 0.1 wt% NaOH and 1m were used 3 H, the gas-liquid two-phase cleaning combined with the compressed air of 100kPa can further reduce the transmembrane pressure difference of the waste membrane until the transmembrane pressure difference is the same as that of the new membrane; (2) the air inlet pressure, the air inflow, the cleaning time and the temperature of the cleaning liquid of the compressed air are improved, and the waste film performance is not further improved.
FIG. 6 shows the water yield variation of the waste membrane element in the above-mentioned combined cleaning process, and the standardized water yield of the waste membrane element after the final gas-liquid cleaning is 4.14m 3 The/h is 2.4 times of that of the new membrane of the same type.
In conclusion, (1) aiming at the waste reverse osmosis membrane mainly polluted by organic pollution in the experiment, 0.1 wt% of NaOH +0.025 wt% of SDS-Na and 0.1 wt% of HCl are used as cleaning agents, and a cleaning mode combining forward cleaning and reverse cleaning of the cleaning agents is adopted for cleaning, so that the effect of reducing the transmembrane pressure difference of the waste membrane is obvious, and the damage to the membrane desalination rate is low.
(2) Further using 0.1 wt% NaOH supplemented with 100kPa, 1m 3 The waste membrane is cleaned in a gas-liquid two-phase cleaning mode of the compressed air, and the transmembrane pressure difference can be reduced to the same level as that of a new membrane。
(3) Before cleaning, the weight of the waste film is 16.45 kg; after cleaning, the weight of the membrane is 14.9kg, which is close to the weight of a new membrane; the pollutants are peeled off from the waste film after cleaning, and the cleaning effect is obvious.
(4) After cleaning, the water yield of the waste membrane element is about 2.4 times of that of the new membrane, the desalination rate is about 97.3%, and the waste membrane element can be recycled in scenes with low energy consumption, high flux and low desalination rate requirements.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (6)
1. The utility model provides a cleaning and regenerating unit of waste reverse osmosis membrane of steam power plant, includes the membrane module, its characterized in that still includes: the chemical cleaning component, the clear water washing component and the air washing component are communicated with the membrane component;
the chemical cleaning component comprises a cleaning water tank, a pipeline I, a booster pump, a pipeline II, a pipeline III, a pipeline IV, a pipeline V, a pipeline VI and a pipeline VII which are sequentially communicated, the pipeline II is communicated with the water inlet end of the membrane component, and the pipeline III is communicated with the concentrated water end of the membrane component; the water inlet end of the first pipeline is provided with a valve V1, the water outlet end of the first pipeline is communicated with the second pipeline through a valve V2, the booster pump is arranged on the first pipeline, the third pipeline is communicated with the fourth pipeline through a valve V6, the fourth pipeline is communicated with the fifth pipeline through a valve V10, the water outlet end of the fifth pipeline is communicated with the cleaning water tank, the water outlet end of the fifth pipeline is provided with a valve V11, the sixth pipeline is communicated with the first pipeline and is provided with a valve V3, the water outlet end of the sixth pipeline is communicated with the fourth pipeline, and the seventh pipeline is communicated with the water inlet end of the membrane component, is provided with a valve V5, and the water outlet end of the seventh pipeline is communicated with the fifth pipeline;
the clear water flushing assembly comprises a flushing water tank, a pipeline eight, a pipeline nine and a drain pipe I, wherein the water inlet end of the pipeline eight is communicated with the flushing water tank and is provided with a valve V12, the water outlet end of the pipeline eight is communicated with the pipeline I, the water inlet end of the pipeline nine is communicated with the pipeline five, the water outlet end of the pipeline nine is communicated with the flushing water tank and is provided with a valve V13, and the drain pipe I is communicated with the pipeline three and the trench through a valve V8;
the gas washing assembly comprises a compressed gas source and a pipeline ten, wherein the gas inlet end of the pipeline ten is communicated with the compressed gas source, the gas outlet end of the pipeline ten is communicated with the pipeline two, and a valve V4 is arranged;
the flushing water tank and the cleaning water tank are communicated with a water replenishing pipe and a trench.
2. The cleaning and regenerating device of the discarded reverse osmosis membrane of the thermal power plant as claimed in claim 1, further comprising a performance testing component;
the performance testing assembly comprises a testing water tank, a pipeline eleven, a pipeline twelve, a pipeline thirteen, a pressure transmitter, an electromagnetic flowmeter, a conductivity meter, a vortex street flowmeter, a drain pipe two and a stop valve, wherein the water inlet end of the pipeline eleven is communicated with the testing water tank and is provided with a valve V14, the water outlet end of the pipeline eleven is communicated with the pipeline I, the water inlet end of the pipeline twelve is communicated with the pipeline five and the water outlet end of the testing water tank and is provided with a valve V15, the water inlet end of the pipeline thirteen is communicated with the water producing end and the water outlet end of the membrane component are communicated with the pipeline IV through a valve V7, the pressure transmitter and the electromagnetic flowmeter are sequentially arranged on the pipeline III and are positioned between the water inlet end and the connecting point of the drain pipe, the drain pipe II is communicated with the pipeline thirteen and a trench through a valve V9, and the vortex street flowmeter and the conductivity meter are sequentially arranged on the pipeline thirteen, the stop valve is arranged on the third pipeline between the pressure transmitter and the electromagnetic flowmeter.
3. The cleaning and regenerating device for the discarded reverse osmosis membrane of the thermal power plant as claimed in claim 2, wherein the test water tank is connected with a first electric heater.
4. The device for cleaning and regenerating the waste reverse osmosis membrane of the thermal power plant as claimed in claim 1, wherein the second electric heater is connected to the cleaning water tank.
5. The cleaning and regenerating device for the waste reverse osmosis membrane of the thermal power plant as claimed in claim 1, characterized in that a cartridge filter is arranged on the first pipeline, and the cartridge filter is arranged between the booster pump and the connection point of the sixth pipeline and the first pipeline.
6. The cleaning and regenerating device for the discarded reverse osmosis membrane of the thermal power plant as claimed in claim 1, wherein a first conductivity meter and a first pressure transmitter are arranged on the second pipeline.
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| CN202121348582.4U CN217287929U (en) | 2021-06-17 | 2021-06-17 | Cleaning and regenerating device for waste reverse osmosis membrane of thermal power plant |
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| CN202121348582.4U CN217287929U (en) | 2021-06-17 | 2021-06-17 | Cleaning and regenerating device for waste reverse osmosis membrane of thermal power plant |
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