Troubleshooting of ion exchangers

Abstract

When the ion exchanger is abnormal, the diagnosis time of equipment failure is often affected due to many factors involved. This paper puts forward the general principles of ion exchanger fault diagnosis, which has certain guiding significance for the operation and maintenance of the water treatment system of the power plant. Readers can judge and deal with this fault diagnosis principle according to the specific situation.

Foreword

Ion exchangers are widely used in the production process of water treatment in power plants. There are many kinds of them, but the basic principles are the same. The ion exchanger is the place where the resin undergoes chemical reaction. Due to many factors affecting the chemical reaction process, it is sometimes difficult to accurately determine the cause of the failure when the equipment has problems such as reduced output, deterioration of effluent quality, and decline in operating economic indicators. Because most power plants do not have many spare ion exchangers, when the equipment fails during the peak water consumption period, if it can be diagnosed in time, it will undoubtedly greatly reduce the troubleshooting time and provide guarantee for the safe production of the power plant. According to the equimolar principle of cation and anion exchange, the author has obtained some superficial experience of ion exchanger fault diagnosis through exploration and summary in production, so as to inform readers. The author believes that the fault diagnosis of water treatment ion exchange equipment should start from the following aspects

1. Cause exclusion of operation and analysis test methods

When the water supply is tight and there are few spare equipment, the operators are prone to nervousness and impatience due to equipment failure. Impatience is not helpful for judging and solving the problem. An incident happened in our factory: that is, the periodic water production of multiple operating cation exchangers dropped significantly within a period of time, and the quality of the effluent water was good and bad. The maintenance personnel opened the equipment to check. After that, it was not found that there was a defect in its internal device. Through the analysis of raw water and resin, the laboratory personnel determined that the water quality and resin performance did not change much. Excluded in time, the production once fell into a passive situation. Later, the technicians found that during the sampling process, the operating analysts often put their fingers into the bottle mouth. The reason is that the number of water treatment operating equipment was large during this period, and the operating personnel could not take so many samples at one time during the sampling process. Therefore, it was opportunistic to put fingers into the bottle mouth, which resulted in the contamination of the sample water by sodium ions in human sweat. It can be seen that when the abnormal operation of the ion exchanger is found, it is necessary to first check whether the results of the water quality sampling and measurement methods are accurate. Whether the situation when the equipment fails is an occasional event or a stable phenomenon. Errors caused by accidental events often make problems appear and disappear from time to time, lack of regularity, and sometimes require careful observation to find out the cause.

2. Analysis of commissioning report and original data

After the ion exchanger is put into operation, the start-up and adjustment test work should generally be completed within 3 months, and the further adjustment and test report of the operation should be completed within 6 months to determine the ion exchange equipment under normal process conditions. Various parameters such as water flow resistance, regeneration consumption level, self-water rate and regeneration conditions, commissioning reports and original data are an important basis for equipment fault diagnosis. Confirmation and judgment of problems in the process of diagnosis.

3. Fault diagnosis under the condition of quality deterioration

The effluent quality is the main indicator to measure the operating conditions of chemical desalination equipment. Deterioration of effluent quality means that during the operation of the equipment, the conductivity and silica content of the demineralized water are significantly higher than the debugging results. At this time, whether the water quality is qualified or not, it can be considered that the water quality of the equipment has deteriorated. When the conductivity or silica content of the demineralized water is obviously high, the pH value of the demineralized water must be measured in order to diagnose the fault.
In the process of fault diagnosis, we can first check whether the conductivity of the system effluent is qualified, and then conduct further investigation according to the qualified conditions of the system effluent silica and pH value Analyze to see if the equipment needs to be tested for repetitive regeneration. Troubleshooting by the exclusion method can shorten the troubleshooting time of the ion exchanger equipment and narrow the scope of troubleshooting. In the diagnosis process, the water quality of the anion exchanger effluent is generally checked first, and the mixing is checked after confirming that the cation and anion exchangers are fault-free. Is the ion exchanger abnormal?

4. Fault diagnosis of equipment output reduction

The reduction of the output of the desalination equipment can be expressed as the reduction of the amount of ions exchanged in the equipment cycle and the reduction of the water production volume of the equipment per unit time. The increase or decrease of the periodic water production is related to the total amount of ions in the raw water. If surface water or multi-source raw water with variable raw water quality is used, attention should be paid to the impact of the change of raw water quality on the periodic water production of the equipment. The power plant needs to conduct a full analysis of raw water every quarter; if there are multiple water sources in the raw water system, if conditions permit, the measurement of raw water quality should be regularly arranged every month to provide a basis for the diagnosis of ion exchange equipment failures. The reduction of water production per unit time period is generally caused by the excessive flow resistance of the ion exchange equipment. It is necessary to check whether the water inlet and outlet water distribution devices and resins inside the exchanger are skewed or blocked. Therefore, during the investigation process It is necessary to make an immediate decision and open the manhole door for the elimination and maintenance of the equipment.
Under normal circumstances, when the desalination equipment fails, it will firstly show that the periodic water production of the ion exchanger gradually decreases, and then the deterioration of the effluent quality occurs. The series desalination system can determine the exchanger with low exchange capacity according to the index of the effluent from the anion bed or the demineralized water when the equipment fails. When the equipment fails, if the silica content of the system effluent increases and the conductivity changes little, it can be judged that the anion bed fails or the anion exchange resin in the mixed bed fails; if the conductivity of the system effluent increases, the silica content does not change much. , it can be judged that the cation exchange resin in the cationic bed or mixed bed has failed. For the parallel desalination system, the periodic exchange volume of the equipment should be calculated according to the periodic water production volume of each device and the ion content of raw water quality.

5. Troubleshooting of the lowering of operating economic indicators

When the water quality of the ion exchanger is occasionally deteriorated or the output is reduced, it is normal to use methods such as repeated regeneration or increasing the amount of regenerant to restore the performance of the equipment. The author said that the failure to reduce the economic indicators of operation means that the specific consumption of the regenerant of the equipment is obviously greater than or exceeds the corresponding value shown.
Generally speaking, the main reasons for the high specific consumption of ion exchanger regenerant are: the resin has been used for a long time or is contaminated by pollution, which reduces the total exchange capacity and working exchange capacity of the resin; the quality of the regenerant is poor, and the content of impurity ions is high. ;In the regeneration process of the ion exchanger, the backwash flow is too large or the water distribution filter leaks and runs off resin, resulting in too little resin in the bed; the regeneration liquid distribution device in the exchanger is damaged, causing the regeneration liquid to flow; the lining of the exchanger Part of the equipment falls off, causing the equipment to have a biased flow of water during regeneration and operation; improper operation by operators or defects in the regeneration system are not discovered in time; the quality of raw water has changed significantly within a period of time, etc. When the equipment fails to reduce the operating economic indicators, it can be checked one by one according to the above items and the original data. During the checking process, the inspection can be carried out in the order of the easier and the more difficult or the higher possibility.

Conclusion

Although there are many failures and reasons affecting the ion exchanger, but according to the classification, there are generally no more than the reduction of output, the deterioration of effluent quality, and the decline of economic indicators of operation. Narrow the scope of the search, and ultimately achieve the goal of solving the problem in a timely manner. Due to the limited level, the inappropriateness of the text is hoped to be criticized and corrected by peers.

Xi’an CHIWATEC Water Treatment Technology is a high-tech enterprise specialized in various water processing devices. Aside from these individual products, which cover a number of types and series, we can also help with related comprehensive engineering projects. Thanks to our hard work and dedication upon our founding, we are now one of the fastest-developing water treatment equipment manufacturers in Western China.

Further reading:

C100E ion exchange resin

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