Boiler demineralized water equipment is a raw water pretreatment device launched for boiler scale, which removes calcium and magnesium ions in raw water and elements causing boiler scale.

Water quality treatment is very important for the safe and economic operation of boiler equipment. But sometimes the boiler softened water is unqualified. What is the reason? How to deal with it?

Unqualified phenomenon and treatment method of boiler demineralized water:

1、 The water outlet of the soft water equipment is qualified, and the water in the soft water tank exceeds the standard

The test at the sampling port of the softened water equipment is qualified, but the water hardness in the soft water tank exceeds the standard, indicating that the water making effect of the soft water equipment is unstable, and the water exceeding the standard has been injected into the soft water tank.

The reason may be:

1. The setting of regeneration cycle is too large (time type), or the metering is inaccurate (flow type) caused by flowmeter failure, so that the resin cannot be regenerated in time when it should be regenerated, resulting in the injection of excessive water into the soft water tank. If the impeller is stuck by rust or the water quality is too dirty, the rotation of the impeller is not smooth.

2. The washing time is too short, so that the waste brine that should have been washed out in the washing is partially brought to the soft water tank.

3. The salt tank caused by unstable water supply pressure has too little make-up water, too little salt absorption and insufficient washing. Any of the above items can cause the effluent hardness after this regeneration to exceed the standard and affect the water quality of the soft water tank.

4. When salt is not added to the tank in time, the regeneration effect is poor.

5. Improper operation, close the feedwater valve during a regeneration process.

6. The bypass ball valve is open or leaking.

2、 The sampling port of the soft water equipment was tested for many times and was unqualified

1. The initial water test hardness of newly installed soft water equipment exceeds the standard,

The reason may be:

※ the O-ring of the center pipe does not form a seal.

※ whether the length and outer diameter of the central pipe meet the requirements (glue the central pipe of the lower water distributor into the tank).

※ the end of the central pipe shall not be 2mm higher than the tank mouth and 5mm lower than the tank mouth).

Note: due to the difference between national standard and American Standard central pipe, the connection size of valve and central pipe must adopt the same standard.

※ forget to install the O-ring of the central pipe or the O-ring falls off during installation.

※ the O-ring of the central pipe is damaged.

※ the central pipe is damaged or cracked.

2. The ratio of feed water TDS value to resin layer height is too large. The inlet water hardness of primary sodium ion exchanger shall be less than 6.5mmol/l.

3. The ratio of feed water TDS value to resin exchange capacity is too large.

4. The running flow rate is too fast. It is forbidden to work at the maximum flow rate allowed by the equipment for a long time.

5. The water inlet and outlet are connected reversely.

Note: the operating flow rate of the downstream regeneration fixed bed specified in GB / t18300 is 20 ~ 30m / h, and its upper limit is the instantaneous maximum value. It is strictly prohibited to work for a long time at this flow rate.

3、 The hardness of soft water of soft water equipment in use exceeds the standard, mainly due to:

1. The ratio of feed water TDS value to resin layer height or resin exchange capacity is too large.

Compared with the initial water test of new resin, the in-service soft water equipment has more strict requirements on the TDS value of feed water. When the height of resin layer is 1.5m, the total hardness is 10mmol / L, and the TDS value of feed water is ≥ 900MG / L, it will be difficult to ensure that the hardness of soft water is ≤ 0.03mmol/l.

2. Resin poisoning, loss of exchange capacity.

The high content of Fe3 + and Al3 + in raw water causes resin poisoning (at this time, the resin color becomes dark red), resulting in the reduction of resin exchange capacity and periodic water production. The excessive hardness of soft water caused by this reason is a gradual process, not a sudden obvious excessive.

3. Poor resin regeneration leads to the gradual reduction of periodic water production, and the water output is unqualified in the later stage of the set water production cycle.

※ the amount of salt in the salt tank is too small. When the amount of water in the salt tank is normal and the height of the salt is less than 1 / 3 of the height of the water, the salt water absorbed in the middle and late stage of the salt suction step is likely to be unsaturated, resulting in the concentration of the salt water diluted by the jet is lower than the regeneration requirements, affecting the regeneration effect.

※ the total amount of water in the salt tank is too small. For every 100L of resin in the resin tank, the minimum amount of water in the salt tank is 40L. Too much lower than this value will lead to insufficient regeneration.

※ salt water is sucked too slowly, and enough salt water cannot be sucked in the normal time.  

※ the regeneration flow rate is too fast or the regeneration method is wrong, that is, the tank body is not matched with the ejector.

4. There is a large amount of gas in the resin tank, which may come from the gas in the feed water, or the air check valve in the slow washing process is not tightly closed.

5. Large iodine free salt was not used.

6. The backwashing is not complete, and the exchanger is polluted by suspended solids, with agglomeration and bias current.

7. Internal leakage of control valve: when the internal leakage of general control valve is hard, the soft water outlet and waste water outlet often discharge water at the same time.

The above are some unqualified phenomena and treatment methods of boiler demineralized water. If you have more opinions and treatment methods, please leave a message below and communicate with each other! Popularizing boiler demineralized water treatment is of great significance to ensure the safe and economic operation of boilers, improve boiler efficiency, prolong the service life of boilers and save energy.