反渗透设备-延长反渗透膜使用寿命的方法
Reverse osmosis equipment - Method of prolonging service life of reverse osmosis membrane
1 防止膜性能的损坏
1 damage prevention of membrane performance
新的反渗透膜元件通常浸润1%NaHSO3和18%的甘油水溶液后贮存在密封的塑料袋中。在塑料袋不破的情况下,贮存1年左右,也不会影响其寿命和性能。当塑料袋开口后,应尽快使用,以免因NaHSO3在空气中氧化,对元件产生不良影响。因此膜应尽量在使用前开封。
The new reverse osmosis membrane elements usually infiltrate 1%NaHSO3 and 18% glycerol aqueous solutions and store them in sealed plastic bags. When plastic bags are not broken, storage for about 1 years will not affect their life and performance. When plastic bags are opened, they should be used as soon as possible so as not to cause adverse effects on components due to oxidation of NaHSO3 in the air. Therefore, the membrane should be opened as far as possible before use.
反渗透设备试机完后,我们采用过两种方法保护膜。设备试机运行两天(15～24h),然后采用2%的甲醛溶液保养;或运行2～6h后,用1%的 NaHSO3的水溶液进行保养(应排尽设备管路中的空气,保证设备不漏,关闭所有的进出口阀)。两种方法均可得到满意的效果。第一种方法成本高些,在闲置时间长时使用,第二种方法在闲置时间较短时使用。
After reverse osmosis equipment trial run, we used two methods to protect the membrane. The equipment test machine runs two days (15 ~ 24h), then uses 2% Formaldehyde Solution maintenance; or after running 2 ~ 6h, use 1% NaHSO3 water solution to maintain (exhaust the air in the equipment pipeline, ensure the equipment does not leak, close all the import and export valves). The two methods can get satisfactory results. The first method is high cost, and it is used for a long time when the idle time is long. The second methods are used in idle time.
2 反渗透设备的操作不当引起膜性能的损坏
2 improper operation of RO equipment causes damage to membrane properties.
2.1 反渗透设备中有残余气体在高压下运行,形成气锤会损坏膜
2.1 reverse osmosis equipment has residual gas running under high pressure, forming air hammer will damage the membrane.
常有两种情况发生:A、设备排空后,重新运行时,气体没有排尽就快速升压运行。应在2～4bar的压力下将余下的空气排尽后,再逐步升压运行。B、在预处理设备与高压泵之间的接头密封不好或漏水时(尤其是微滤器及其后的管路漏水)当预处理供水不很足时,如微滤发生堵塞,在密封不好的地方由于真空会吸进部分空气。应清洗或更换微滤器,保证管路不漏。总之,应在流量计中没有气泡的情况下逐步升压运行,运行中发现气泡应逐渐降压检查原因。
There are two kinds of situations. A, when the equipment is empty, it will run fast when the gas is not discharged. The remaining air should be drained at 2 to 4bar pressure, and then step up operation gradually. B, when the joint seal between the preprocessing equipment and the high pressure pump is not well sealed or leaks (especially the filter and the leakage of the pipe after the filter), when the pre treated water supply is not very sufficient, such as the microfiltration, the vacuum will suck in some air in the bad sealed place. The microfilter should be cleaned or replaced to ensure no leakage in the pipeline. In short, step up operation should be carried out in the flowmeter without bubbles. During operation, bubbles should be checked down step by step.
2.2 反渗透设备关机时的方法不正确
2.2 the method of reverse osmosis equipment is not correct when turning off the machine
A、关机时快速降压没有进行彻底冲洗。由于膜浓水侧的无机盐的浓度高于原水,易结垢而污染膜。B、用投加化学试剂的预处理水冲洗。因含化学试剂的水在设备停运期间可能引起膜污染。
A, fast depressurization without shutdown. Because the concentration of inorganic salt on the membrane concentrated water is higher than that in raw water, it is easy to foul and contaminate the membrane. B, rinse with pre treated water with chemical reagents. Water contaminated with chemical reagent may cause membrane fouling during equipment shutdown.
反渗透设备在准备关机时,应停止投加化学试剂,逐步降压至3bar左右用预处理好的水冲洗10min,直至浓缩水的TDS与原水的TDS很接近为止。
When the reverse osmosis equipment is ready to shut down, the chemical reagents should be stopped and gradually reduced to about 3bar to rinse 10min with pretreated water until the TDS of the concentrated water is close to the TDS of the original water.
2.3 反渗透设备消毒和保养不力导致微生物的污染
2.3 sterilization and ineffective maintenance of reverse osmosis equipment lead to microbial contamination.
这是复合聚酰胺膜使用中普遍存在的问题,因为聚酰胺膜耐余氯性差,在使用中没有正确投加氯等消毒剂,加上用户对微生物的预防重视不够,容易导致微生物的污染。目前许多厂家生产的纯水微生物超标,就是消毒、保养不力造成的。
This is a common problem in the use of polyamide membranes, because the polyamide membrane is poor in chlorine tolerance, and there is no chlorine and other disinfectants in the use of the polyamide. At present, many manufacturers produce pure water microbes exceeding standard, which is caused by poor disinfection and maintenance.
主要表现为:出厂时,RO设备没有采用消毒液保养;设备安装好后没有对整个管路和预处理设备消毒;间断运行不采取消毒和保养措施;没有定期对预处理设备和反渗透设备消毒;保养液失效或浓度不够。
The main manifestations are: when the factory is out of the factory, the RO equipment does not maintain the disinfectant; the equipment does not sterilize the whole pipeline and the pretreatment equipment after the installation is good; the discontinuous operation does not take disinfection and maintenance measures; it does not disinfect the pretreatment equipment and the reverse osmosis equipment regularly; the maintenance fluid is invalid or the concentration is not enough.
2.4 反渗透设备余氯监测不力
2.4 poor monitoring of residual chlorine in reverse osmosis equipment
如投加NaHSO3的泵失灵或药液失效,或活性炭饱和时因余氯损坏膜。
If NaHSO3 pump failure or liquid failure, or when activated carbon saturation, due to residual chlorine damage to the membrane.
3 清洗不及时与清洗方法不正确导致的膜性能的损坏
3 cleaning is not timely and incorrect cleaning methods cause the damage of membrane performance.
设备在使用过程中,除了性能的正常衰减外,由于污染而引起设备性能的衰减更为严重。通常的污染主要有化学垢,有机物及胶体污染,微生物污染等。不同的污染表现出的症状是不同的。不同的膜公司所提出的膜污染的症状也是有一定的差异,如表1所示。
In the process of using the equipment, besides the normal attenuation of the performance, the attenuation of the equipment performance is more serious due to pollution. The main pollution is chemical fouling, organic matter and colloid pollution, microbial contamination and so on. The symptoms of different kinds of pollution are different. The symptoms of membrane fouling presented by different membrane companies are also different, as shown in Table 1.
在工程中我们发现,污染时间的长短不一样,其症状也不一样。如:膜发生碳酸钙垢污染,污染时间为一个星期时,主要表现为脱盐率的迅速下降,压差缓慢增大,而产水量变化不明显,用柠檬酸清洗能完全恢复性能。污染时间为一年(某纯水机),盐通量由最初的2mg/L上升为37mg/L(原水为140mg /L～160mg/L),产水量由230L/h下降为50L/h,用柠檬酸清洗后,盐通量降为7mg/L,产水量上升至210L/h。
In engineering, we find that the duration of pollution is different, and the symptoms are different. For example, the pollution of calcium carbonate fouling in the membrane, when the pollution time is one week, is mainly manifested by the rapid decrease of desalination rate, the slow increase of pressure difference, and no obvious change in water production, and the citric acid cleaning can completely restore the performance. The pollution time is one year (a certain pure water machine), the salt flux rises from the original 2mg/L to 37mg/L (the original water is 140mg /L to 160mg/L), the water yield decreases from 230L/h to 50L/h, after the citric acid cleaning, the salt flux is reduced to 7mg/L, and the water yield increases to 210L/h.
再者污染往往不是单一的,其表现的症状也有一定的差别,使得污染的鉴别更困难。
Moreover, the pollution is often not single, and the symptoms of it are also different, making the identification of pollution more difficult.
鉴别污染类型要综合原水水质,设计参数,污染指数,运行记录,设备性能变化及微生物指标等加以判断:
To identify the types of pollution, we should judge the quality of raw water, design parameters, pollution index, operation records, equipment performance changes and microbiological indicators.
(1)胶体污染:发生胶体污染时,通常伴随着以下两个特性:A、前处理中微滤器堵塞得很快,尤其是压差增大很快,B、SDI值通常在2.5以上。
(1) colloid pollution: when the colloid pollution occurs, the following two characteristics are usually accompanied by the following characteristics: A, the microfiltration device in the pretreatment is blocked very quickly, especially the pressure difference is increased quickly, and the value of B and SDI is usually above 2.5.
(2)微生物污染:发生微生物污染时,RO设备的透过水和浓缩水中的细菌总数都比较高,平时一定没有按要求进行保养和消毒。
(2) microbial contamination: when microbial contamination occurs, the total number of RO equipment through water and in the concentrated water is relatively high, and it must not be maintained and sterilized as required.
(3)钙垢:可依据原水水质及设计参数进行判断。对碳酸盐型水而言,如果回收率为75%时,设计时投加了阻垢剂,浓缩液的LSI应小于1;不投加阻垢剂时浓缩液的LSI应小于零,一般不会产生钙垢。
(3) calcium scale: it can be judged according to the quality and design parameters of raw water. For carbonate water, if the recovery rate is 75%, the scale inhibitor is added in the design, the LSI of the concentrated solution should be less than 1, and the LSI of the concentrated liquid should be less than zero when the scale inhibitor is not added, and the calcium scale will not be produced in general.
(4)可用1/4英寸的PVC塑料管插入组件中测试组件不同部位的性能变化进行判断。
(4) the performance of different parts of the test module can be judged by inserting a 1/4 inch PVC plastic pipe into the assembly.
(5)根据设备性能的变化判断污染的类型。
(5) determine the type of pollution according to the change of equipment performance.
(6)可用酸洗(如柠檬酸、稀HNO3),根据清洗的效果和清洗液判断钙垢,通过清洗液成分分析进一步证实。
(6) acid pickling (e.g. citric acid and dilute HNO3) can be used to determine calcium scale according to the cleaning effect and cleaning solution.
(7)对清洗液进行化学分析:取原水、清洗原液、清洗液,三个样分析。
(7) chemical analysis of cleaning fluid: raw water, cleaning raw fluid, cleaning liquid, and three sample analysis.