performance evaluation of technos cleaning balls in rdc msf pilot

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testing, Technos balls were tested in Jeddah III Unit 9 for 4 weeks at a TBT of 107°C and in Al-Jubail II Unit 16 for 6 weeks at a TBT of 98°C. Heat transfer coefficients, fouling factors, plant performances and balls physical integrity were monitored during the tests. The reduction in size of the balls due to normal wear and loss of balls in the system during test period was found low and within acceptable limits. The distiller performance and the inspection of the balls during the tests at Jeddah and Al-Jubail plants showed that Technos balls were effective and suitable for use in MSF distillers. It was therefore, recommended to place the product on approved bidders’ list for Al-Jubail Phase II and Jeddah Phase III Plants. Due to successful test of the Technos balls, it is also recommended to use and evaluate long-term performance of Technos balls in other SWCC plants. 1. INTRODUCTION Cleanliness of water side tube surfaces is a significant factor affecting the heat transfer capacity of seawater/brine cooled condensers in MSF distillation plants. Substances, which adhere to the heat transfer surface, decrease tube cleanliness and impede transfer of heat. These include precipitation fouling or scaling, biological fouling and particulate fouling. Though the formation of scale, which is the main source of fouling in MSF distillers, is combated and controlled by threshold treatment using antiscalant, its complete prevention is impracticable. Sludge or distorted scale is also formed as a result of threshold treatment and gets deposited on tube metallic surfaces thus creates resistance to heat transfer. If not removed early after formation, these soft deposits could convert into solid scale. Sludge can be easily removed by employing on-line cleaning of the tubes. The combined use of antiscalant and on-line tube cleaning has proved to be the most effective and economical means to avoid fouling of internal surfaces of tubes. This leads to reduced cost of additives where lower dose rate could suffice. The most effective on-line tube cleaning system that is currently in use in MSF desalination plants is the sponge rubber ball circulation system. At an optimum sponge ball cleaning in additive dosed MSF plant, the tube fouling can be maintained as low as 0.04 m 2 K/kW resulting in over 40% of the mean energy saving [1]. 2
There are many manufacturers of sponge cleaning balls such as Taprogge, Technos, Water Science of America (WSA), Remington and Schimitz. They produce many types like polishing, granulate, high temperature and corundum ring or total coated sponge balls. Technos has developed a technique to blend the balls with the special materials that were previously used as coating on abrasive balls. The grain size of the abrasive material is small enough to avoid the risk of scratching the tube metal surface, which could trigger erosion-corrosion phenomena. The technique is claimed to provide a major advantage over ball coating technique since the desired abrasive effectiveness remains unchanged while the balls are being used [2]. The scale/sludge removal ability of sponge rubber balls depends on many factors such as size, number, hardness, surface texture and age of the balls, the frequency and duration of treatment, and nature of metallic surface. Based on the operating experience, the average ball life in Al-Jubail Phase II Plant is 5-6 weeks with 8 cycles of ball circulation per shift while in Jeddah plant, it is 4 weeks with 6 cycles per shift. Al-Sofi et al. reported from operational experiences that the number of balls, which can be fed to the system, could be as high as 60% of the number of tubes. He suggested that 30% or even less would be adequate, yet much lower percentages be insufficient to reach all the tubes while a higher percentage would lead to tube blockage, crowding at strainer and accelerated wear at tube mouth [3]. The frequency and cycles of ball cleaning and ball to tube ratio used in SWCC MSF plants are reported by Dr. Hamed O.A. el al. [4] and are given in Annexure 1. In this project, for the first time Technos balls were evaluated at Research and Development Center (RDC) of SWCC by conducting test run at MSF pilot plant. Performance evaluation tests of Technos balls were further conducted in Jeddah III and Al-Jubail II commercial plants. Preliminary evaluation test of Technos balls in MSF pilot plant was conducted at a TBT of 110 o C and DSB(M) dose rate of 2 ppm over a test period of three weeks. After the successful test at pilot plant, balls were evaluated in Jeddah III Plant (Unit 9) at a TBT of 107°C and in Al-Jubail II Plant (Unit 16) at TBT of 98°C. Physical integrity of the balls such as mechanical damage, shrinkage, surface wear, deformation or loss of texture were monitored closely during the tests in both Jeddah and Al-Jubail plants. The effectiveness of balls in removing soft scale and sludge was also checked by calculating heat transfer coefficients and fouling factors. 3
Page 1: PERFORMANCE EVALUATION OF TECHNOS C
Page 5 and 6: 3.1.3 Al-Jubail Plant Phase II Al-J
Page 7 and 8: all cleaning frequency were kept sa
Page 9 and 10: alls once received certain wear in
Page 11 and 12: all cleaning system. The high fluct
Page 13 and 14: Table 1. Operating Conditions for T
Page 15 and 16: Table 3. Technos Balls Inspection R
Page 17 and 18: 2000 Number of Damaged Balls 1500 1
Page 19 and 20: pH LTA 2.00 9 1.00 8.9 0.00 8.8 -1.
Page 21 and 22: Heat Transfer Heat Transfer Coeff.,
Page 23 and 24: REFERENCES 1. Bohmer, H., (1993), O

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