Ennore Foundries Ltd, a leading foundry and subsidiary of Ashok Leyland Ltd, manufactures Engine Castings and moulded parts for Ashok Leyland Vehicles etc.

Problem

The factory is located at Ennore, 15, Kms., north of Madras close to the seashore and is equipped with SKL 1100 / 1150 KVA SKL DG sets which are cooled through water circuits which is recirculated through cooling towers. The cooling water is taken from a borewell and has the following analysis.
 

                                                                                                               pH              7. -7.7

                                                                              Total Dissolved solids          3040 ppm

                                                                                          Total hardness          1080 ppm

                                                                                    Calcium hardness             690 ppm

                                                                              Magnesium hardness            390 ppm

                                                                                           Total Alkalinity            210 ppm

                                                                                                   Chlorides             880 ppm

                                                                                                  Sulphates             845 ppm

as the water was very hard, tough white scale formation was observed in the heat exchanger tubes and the water passages. Scale being very hard to be removed, it had to be drilled, chiselled and taken out after soaking in acid for a few hours, once in every 1000 running hours. Since DG Set was operated in an overheated condition, the fuel consumption replacement of costly spares, shot up.

The Solution

In order to prevent this formation of hard scale on the heat transfer areas a 3" COLLOID-A-TRON was installed on the secondary circuit and 2 1/2" CAT was installed on the primary circuit of the SKL II DG Set during November 1988.

After installation of COLLOID-A-TRONs in the SKL II DG set, the performance was closely monitored. The raw water and recirculating water were analysed regularly and the engine water temperature was closely observed. There was no increase in the engine water temperature during the period. The concentration level in the cooling tower was kept at 2.5. After 1000 running hours of installation COLLOID-A-TRON, the Heat Exchanger and the water passage in the engine side were opened and found to be totally free of scale.

The Saving

Since the installation of COLLOID-A-TRONs in the circuit there has been no scale formation for several thousand running hrs, until now, thereby saving the cost of Down time. Excess fuel consumption, replacement of costly imported spare parts and man power lor descaling.