Objective The initial aim of the project was to recover the heat from a fat laden vapour removed from potatoes while being cooked and mixed with cooking oil and convert into steam suitable for use in a turbine for power and heat generation. The steam in the form of hot water would be elevated in temperature to 150-170 deg. C.Due to both technical and financial reasons (see Section 3 - Construction for details) the equipment selection was changed to recover the heat in the form of hot thermal oil and hot water to reduce the energy input to the cooking process.The energy saving expected was 360,000 NM3 of natural gas at 38.2 Mj/NM3 or 13.75 million Mj.During the Monitoring Period of the Project, the results were as follows :PERIOD BASIS FOR COMPARISON ACTUAL ACHIEVED REDUCTION SAVING Mj/carton Mj/carton MjSeptember '92 21.71 20.12 445,521October 22.45 21.01 379,489November 23.70 20.93 777,855December 23.65 21.38 471,397January '93 23.76 21.47 654,028February 24.12 21.13 751,145March 22.88 20.86 483,275April 22.84 20.12 774,066May 22.51 20.47 553,664June 22.00 19.97 497,744July 21.86 19.76 590,850August19.51 17.06 695,185 TOTAL SAVINGS: 7,054,219 MjThere have been no additional electricity costs; consumption remained as previously.The results achieved were lower than anticipated with a natural gas saving of 185,000 NM3 over the 12 month period. During the latter stages of the Monitoring and Measurement Phase the results improved. This was achieved with fine tuning of the plant and optimising on the recovery temperatures.With regard to the environmental impact of the project it is considered as a great success; the odours and smells are almost eliminated.Although the fuel saving was lower than predicted the overall financial benefit is considered reasonable with additional cost savings by:- Reduced water usage and discharge.- Eliminating of odour and smell from the cooker discharges.Technically the project has been very successful and has proved the technlque for the industry and highlighted the recovery benefit in terms of standardising on a thermal oil heating system with hot water recovery for blanching.There are two crisp lines at the Coolock Factory where potatoes are peeled/de-stoned, sliced, blanched and finally cooked in vegetable oil.The design was based on the recovery of the heat from the exhaust vapour discharge from both lines and the standardisation of indirect fired thermal oil heating with the removal of the need for separate hot water and steam generation plants.The discharge from No 1 and No 2 cookers have been ducted into a supplementary fired heat recovery unit situated on the floor adjacent to No 2 production line.A specially designed stainless steel duct system was fabricated to convey the fat laden vapour discharge with independent draught and temperature control to maintain the correct conditions over the individual crisp cookers.A new induced draught fan was installed that would cater for the full mass flow of exhaust from both No 1 and No 2 cookers. To facilitate start-up and line cleaning individual dump stacks were added to each line incorporating isolation dampers.The supplementary fired heat recovery unit was of a new innovatory design that had not previously before been adapted for vapour incineration with such a high moisture content. The original proposal was to install a twin tower scrubber arrangement that would recover the heat and fat separately, however, at the detail design stage serious problems occurred indicating that the cost and environmental control were not as envisaged.The fat laden vapour discharge is elevated in temperature to 800 deg. C by the direct firing of natural gas. To ensure the complete burnout of the cooking oil carryover, estimated at 500 kg/day, and to maintain the safe stable combustion process, a new combustion unit had to be manufactured. Inside the combustion chamber the vapour is introduced to give adequate mixing and residence time. The heat is recovered from the supplementary fired incineration unit in 2 forms:- Thermal oil at 280 deg. C.- Hot water at 110 deg. C.A new thermal oilheat exchanger has been installed into the exhaust to recover the heat at the rate of 8 million kj/hr and lower the discharge temperature to 300 deg. C. The heat recovery exchanger has been fully integrated into the existing thermal oil heating system.The second phase of recovery incorporates, into the unit exhaust a fully condensing heat exchanger. The unit condenses the vapours to recovery the latent and sensible heat by lowering the exhaust to 75-85 deg. C. The 13 M3/hr of water required for the blanching of the potato slices is elevated in temperature using the condensing heat exchanger from 10 deg. C up to 110 deg. C; the heat recovery of a further 5 million kj/hr.The new total system removes the need for the steam and hot water boilers and standardises on indirect cooking oil heating using thermal oil.The control system for the plant is fully automatic for the daily operation of the production facility between 0600 hours and 2200 hours (16 hours), 5 days per week. Programme(s) ENG-THERMIE 1 - Programme (EEC) for the promotion of energy technology in Europe (THERMIE), 1990-1994 Topic(s) 2.3 - INDUSTRY Call for proposal Data not available Funding Scheme DEM - Demonstration contracts Coordinator TAYTO LTD EU contribution No data Address GREEN CASTLE ROAD COOLOCK 17 Dublin Ireland See on map Total cost No data
