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CARBERY MILK PRODUCTS BALLINEEN Co. Cork. Energy Saving Programme Application of “Pinch” Technology. Typical Energy/Product Flows. Pinch Technology.
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CARBERY MILK PRODUCTSBALLINEENCo. Cork Energy Saving Programme Application of “Pinch” Technology
Pinch Technology Pinch technology presents a simple methodology for systematically analysing chemical processes and the surrounding utility systems with the help of the First and Second Laws of Thermodynamics.
Objectives of Pinch Analysis The prime objective of pinch analysis is to achieve financial savings by better process heat integration. This requires the maximization of process-to-process heat recovery, which will in turn reduce all the external utility loads.
Concept No.1 Do not start and energy saving programme by first undertaking a detailed analysis of all the services and utilities The optimum selection and operation of the services and utilities can only be determined after a detailed analysis of all the processes has been completed.
Concept No.2 Every process cooling load represents a heating opportunity, thereby achieving both: Free Cooling & Free Heating
Concept No.3 Operate with the minimum economic pinch point temperatures. The pinch point temperature is defined as the minimum approach temperature between the 2 fluid streams in a heat exchanger.
Carbery Methodology • It was decided to undertake a detailed thermodynamic analysis of all factory heating and cooling loads and then attempt to integrate these into a single heat exchanger network. • It would then be possible to maximise regeneration across the whole site and thereby minimise all heating and cooling loads. • The total project is by far incomplete and it will take at least another 6–12 months before the factory becomes reasonably energy efficient.
Steam Production • It was apparent from an analysis of the energy reports that steam was not being produced in the most economical manner. • Supplementary firing on the CHP plant was not being maximised. • Heat was being dumped from the CHP plant at the same time as steam was being produced on the steam boilers. • Biogas was being burnt in combination with natural gas. • There were too many boilers on line.
Steam Production (ctd) • Most of these problems have now been overcome. • 3 boilers have been taken of-line • The utilisation of the CHP plant has been increased from 43% to 75% • Further improvements will limit all steam production to the CHP plant and Biogas Boiler • It is estimated that the improvements in steam production efficiency are in the order of €300,000 per annum.
Distillery • The Distillery accounted for 41% of all energy used on the site. • It was considered that by improved regeneration of the Product (Beer) Infeed and the Spent Wash, that a significant reduction in steam could be made.
Distillery • Once this was achieved it became apparent that the energy being rejected through the condensers to the cooling towers was virtually equal to the steam supply to the Distillery. • The condensers therefore represented the virtual equivalent of another Boiler House.
Distillery • The total potential rate of heat recovery from the condensers is 8,000 kW, which is equivalent to 11 tonnes of steam per hour. • It was decided to install 2 new condensers, one supplying a hot water ring main around the factory @ 92 Deg.C and the second a ring main @ 76 Deg.C. • To date only 2 condensers have been installed, a 3rd being installled this winter to augment the heat supply to the 76 Deg.C line. • The 3 condensers will then capture virtually all of the 8,000 kW available heat.
Comments on Heat Utilisation • It will be noted that the utilisation of the recovered heat on the 76 Deg.C Line is reasonably satisfactory. As there are a considerable number of additional uses for this heat, it was decided to install the 3rd condenser. • The 92 Deg.C Line is only currently being used for achieving the final pasteurisation of all milk and whey processing streams. During the periods when these processing streams are not in operation (daily cleaning) this line will be usd for boiler feed water heating and filling large hot water tanks, which will be later used for process plant cleaning et. • An automatic monitoring and management system is to be installed which will programme the heating loads, so as to ensure a constant utilisation of all this heat throughout the day.
Ultra Filtration Department • An examination of the energy flows and temperatues will show that the Permeate, which is cooled in the Distillery to 36 Deg.C prior to fermentation, has considerable heating potential. • The annual flow of permeate is 430,000,000 litres and the cost of operating the associated cooler and cooling tower was €25,000 per annum. • With the installation of new heat exchangers, the permeate has now replaced steam in heating all purchased whey, providing low grade heating to the pasteuriser and pre-heating difiltration water to 48 Deg.C. • The final high temperature heating to the pasteurisers is now accomplished using 92 Deg.C water from the Distillery. • The cooling of the WPC is also used for pre-heating some of the difiltration water to 48 Deg.C and the enhanced heat exchanger has also provided significant savings in chilled water for cooling.
Ultra Filtration Department (ctd.) • The Ultrafiltration Department was the second largest energy user on the site. • Regeneration of the Permeate stream and heat recovery from the Distillery has virtually eliminated the process requirement for steam. • The current installation of a 140 cu.m tank for storing 78 Deg.C hot water, which will be supplied from the 76 and 92 deg.C lines, will then virtually eliminate the requirement for any steam in this department.
Milk Intake and Cheese Production • In the Cheese Dept. all steam was replaced in all pasteurisers by a combination of: 1. Effluent water @ 30 Deg.C 2. 76 Deg.C water from the Distillery 3. 92 deg.C water from the Distillery. • The Cheese Department provides significant scope for additional energy savings and these will be implemented during the off-season.
Pinch Technology • One of the guiding principles of the techniques employed in Carbery is to operate with the minimum economic pinch point temperature. • In most systems the pinch point temperatures employed have been between 3 Deg.C and 4 Deg.C. • The other principle has been not to use a hot fluid stream at say 80 Deg.C to heat a cold stream to only 40 Deg.C The following schematic will illustrate the principle:-
Annual Savings On an annualised basis the current audited energy savings are: €2,100,000per annum Based on current energy costs it is anticipated that the final annual savings will be approximately: €3,000,000 per annum
Summary • With the possible exception of improvements made to the steam raising facility, all individual projects interlink into what is virtually a single integrated project. • By undertaking a thorough thermodynamic examination of all heating and cooling processes and then integrating these into a single heat exchanger network, it has been possible, by maximising regeneration across the whole site, to significantly reduce the use of all utilities, including steam, refrigeration and electricity. • The project is far from complete and a number of additional energy saving projects are planned for installation during the off-season.
