Answer EKG Question 36

Q36. With reference to Boiler water tests carried out on board:
A. Discuss the possible reasons for the following changes in boiler water test results, and state what actions should be taken in each case;
1. Reduction in total dissolved solids and chemical reserves.
2. Reduction in phosphate reserve, with increase in chlorides and total dissolved solids;
3. Reduction in alkalinity reserve only.
4. Increase in oxygen levels only.

B. State why the complete results of boiler water tests are logged or entered into a data retrieval system rather than a note being made of any particular result which may be outside set limits.

Answer: (A) Possible reasons and actions:-

1. T.D.S and Chemical reserve in the boiler can be reduced because of the water leakage from leaking tubes or because of any other source of water leakage. Actions to be taken:- water leakage from tube can be seen as white smoke from the boiler funnel along with frequent level drop in boiler drums which leads to frequent requirement to refill the cascade tank. Also the boiler may fail to fulfill the required demand of steam. Trace the leakage and repair the same, carry out adequate chemical treatment.

2. Reduction in phosphate reserve, with increase in chloride and T.D.S can take place if the sea water leakage in the system. Actions to be taken:- sea water can enter in the system through condenser system. Trace the source of sea water leakage in the system.

3. Reduction in alkalinity reserve only takes place when lube oil with high alkalinity leaks in. Actions to be taken:- lube oil can enter through the purifier feed heater. same needed to be traced and rectified.

4. Increase in oxygen levels only takes place when ingress of air takes place. where de-aeration system uses vacuum principle it is more prone to air ingress. Actions to be taken:- Trace the source of air ingress and it can be from defective flanges, gaskets, uncovered cascade tank or cracked valve bonnets. Maintain temperature of hot-well and check for the ventilation of the from de-aerator.

(B) By logging the boiler water test results we can follow the gradual trend of value deviation within the normal range. This record is helpful in scheduling the chemical treatment.