1 Case Study - Dairy Installation Installation of Desuperheater for Dairy for ‘FREE’ hot water generation Refrigeration and boiler constitute more than 75 % of operating energy cost of dairy. As much as dependability of these systems is important, operating plant efficiency and consistency in performance is also required to limit processing cost of milk. Built-in improvement in operating efficiency constitutes major saving opportunities in dairy utility system. Installation of desuperheater for recovery of waste heat is major step in this direction. REFRECON has more than 18 successful desuperheater installations in operation since past three years. The technology is successfully implemented for various systems using ammonia and R 22 refrigerants. Dairy cooling requirement Pasteurisation Cold storage Milk chilling Hot water requirement Boiler feed water Crate / Can washing Tanker washing CIP Conventional mode of hot water generation Use of direct fuel fired hot water heaters Direct steam injection Condensate recovery after steam use in plant Desuperheater mode of “ FREE “ hot water generation With cold storage and IBT in operation, chilling plants and refrigeration compressors operate almost 24 hours per day in dairy. IBT takes care for fluctuating cooling demand by generating appropriate ice thickness in IBT to maintain cold storage temperature protecting product quality. 2 Adiabatic compression in ammonia compressor results in high discharge gas temperatures at compressor outlet. (1200 C and above) This gas is cooled and condensed in condenser and stored in receiver at 12 to 16 - kg/cm2 pressure and atmospheric temperature. Condensing temperature (varying between 300to450 C) vary depending upon type of condenser cooling and atmospheric conditions. Desuperheater installed in ammonia circuit between compressor discharge and condenser, removes high temperature gas heat and passes entire gas to condenser to condense similar to normal refrigeration cycle. Gas heat removed in desuperheater heats circulating water up to 550 – 700 C. This recovered heat in the form of hot water is available free of cost for various requirement in dairy. Refrigeration plant operates almost 24 hours per day generating hot water at specific rate. This hot water is stored in adequately sized hot water tank to meet demand of hot water in plant as and when required. Schematic process diagram of desuperheater installation is enclosed for ready reference. ADS series of REFRECON desuperheater is specifically designed for ammonia compressors. MOC and process parameters are appropriately matched for life long consistency in performance. The fully welded construction of desuperheater has complete safeties required for installation and infinite life of operation. The desuperheater is capable to withstand 40 bar pressure and is tested for bubble-tight leak-proof performance at 25 bar pressure in the manufacturing process. The perfected design results in flaw less commissioning during field installation. The performance consistency has been proven with number of installations and the recent one of 75 TR capacity is jointly monitored with NDDB staff for six months. The results are tabulated in one of the case studies listed bellow. 3 Case study I Installation cooling load Installed capacity Operating load Desuperheater installation 120 TR nominal 90 TR Suitable for 90 TR nominal (3 X 30 TR) First installation August 2003 Balance two units March 2004 Type of savings established Free Hot water generation Fuel saving confirmed Compressor operation Avoided investment Water Saving 18 kL per day @ 700 C 40 – 50 lit. of FO per day (steam boiler fuel) 30 – 35 lit Diesel / day (hot water boiler fuel) Reduced operating hours 2 hrs. per day 90 TR compressors / condensers working with 60 TR evaporating condenser. Avoided additional 30 TR condenser installation. Saved 1250 liters /day evaporation loss of water in cooling tower Savings achieved Fuel oil savings Rs. 5,00,000 /- per year Electricity saving Rs 75,000 /- per year 30 TR condenser installation = Rs. 1.2 lac Avoided investment Investment for desuperheater and hot Rs. 7,50,000 /water system, including tank and piping Simple Pay back 13 months Benefits (additional) that are obvious but not quantified above 1. Reduced boiler operating hours 2. Reduced or avoided maintenance of hot water generator & boiler 3. Avoided maintenance contract for hot water generator including spares cost. 4. Reduced heat loss and CO2 emission to atmosphere 5. Benefits drawn as eco-friendly organisation image 4 Case study II: Installed capacity Compressor Operating hrs. Desuperheater installation Free Hot water generation Fuel saving confirmed (in 75 TR 16 hours per day average Suitable for 75 TR Compressor operation Fuel oil savings Electricity saving Reduced operating hours 2 hrs. per day Rs. 2,60,000 /- per year Simple Pay back Less than 6 months due to improved condenser performance that was poor on account of poor water quality and excess scaling on condenser. form of steam boiler fuel) 15 kL /day @ 530 C – 16 hrs /day working Six months monitoring confirms consistent savings equivalent of 58 kg of FO per day Condenser inlet temperature dropped from 1300 C to 1150 C. Ammonia condensing temperature reduced from 400 C to 350 C. Estimated electrical savings are more than Rs. 9 lac. Per annum Investment for desuperheater system Rs. 4,50,000 /- Conclusion: Looking at benefits as above installation of desuperheater in dairy as retrofitting as well as new is commercially viable proposal. Simple Pay back of less than 15 months and consistency in performance is assured. Desuperheater system also offers sizable improvement in refrigeration cycle and reduced maintenance of condenser as well as compressor. This also enhances life of compressors as well as hot water generating equipments. V. V. Kanetkar Director Refrecon Magic Systems Pvt. Ltd. 37/3 Vadgaon Khurd, Sinhgad Road, Pune. 411 041 Ph 91 20 2439 3418 / 2439 2545 Email: kvrajlal@vsnl.com 4 March 2005