1 year ago

MDA Technologies 2/2016

MDA Technologies 2/2016


COMPRESSED AIR NEWS Optimized compressed air supply concept with heat recovery provides high savings The Thyssen-Krupp Presta Schönebeck GmbH optimized its compressed air supply using compressors and heat recovery modules from Atlas Copco. This concept can be used effectively to send compression heat into the production cycle almost without any loss. We have perfect conditions for heat recovery – when they were not perfect, we have made them perfect“, says Olaf Naupert, who is responsible for energy management of Thyssen-Krupp Presta Schönebeck GmbH. The year-round requirement for process heat is one of the perfect requirements for automobile suppliers. This has been present since 2009, as Naupert decided to change the washing machines for cleaning the manufactured metal parts from electrical heating to community heating. “I asked myself the question – Why should I go for electric heating paying 15.368 Cent per kilowatt hour, when I can use community heating for 9.5 Cent per kilowatt hour?”, says the automation expert. “Later we had the idea to reduce 9.5 Cent further and generate heat ourselves”. In Schönebeck plant, more than 700 employees manufacture electromechanical and hydraulic steering systems for automobile industry. The individual parts such as pinions, control bushings, rotary vanes, racks or ball nuts are turned, milled, polished, hardened and cleaned. Large amount of compressed air is required for these manufacturing processes as well as for final assembly. Between 400 MDA Technologies 2/2016

COMPRESSED AIR NEWS 01 The GA compressors were upgraded in September 2014 with external ER heat recovery units. This measure amortised itself in February 2015 02 If the oil in the compressor is hotter than the water of the heating return flow, a pump supplies the return heated water to the heat exchanger of the ER unit. Thus, water is pre-heated for heating. This reduced the amount of community heating required 03 The visualisation programmed by Olaf Naupert himself provides information about all the relevant system in real time – even the compressed air stations to 1200 litres/second is generated with a total of twelve oil-injected GA screw compressors. They have a rating of 30 to 90 kilowatt, three of the compressors work with variable speed. The dozen compressors are distributed to three compressor stations and supply compressed air to the entire network. “I control the system with four different pressure bands between 5.7 and 6.3 bar”, says Naupert. “We normally operate at 6.3 bars. But if the energy consumption is at a peak in the plant, I can reduce the pressure in an automated way. That is one of the measures, which we use to cushion power peaks, because in principle I have to pay my highest monthly output”. Energy savings through network optimisation However, the fact that compressed air is provided nowadays in the plant with high efficiency and safety is not a sure-fire way to success. “There is lot work that goes behind our compressed air supply”, reports Naupert. “We went through a merger in October 2012. Previously there were two companies on the factory premises: Thyssen-Krupp Presta SteerTec Schönebeck GmbH and BMB Steering Innovation GmbH.” At this point, twelve compressors supplied three networks, which have almost similar operating pressure. There was no higher level control. “At the time of merger, we were confronted with the question of whether we have to invest in compressed air generation or combine the networks”, says Naupert about the discussion. “Because one network had excellent design, but had very less generation energy. The second network had lot of generation energy, but had very small diameters.” The first major project with Dr. Weigel Anlagenbau GmbH (WAB) from Magdeburg was started under this situation, who is a longterm partner of Schönebeck and dealer of Atlas Copco. “We have invested approx. 30,000 Euros for combination of the two nets, Efficiency pays off n Energy saving through optimization of compressed air: 460,000 kW/h per year, i.e. 70,000 Euros per year n Amortisation of heat recovery in less than six months n Reduction of community heat consumption by 25 percent mainly for pipeline”, says Naupert. “Based on need-based expansion of the lines, installation of higher level controller ES 16 and influence on pressure band, we are saving enormous amount of energy, i.e. more than 460,000 kilowatt hours or 70,000 Euros per year.” Heat recovery is amortised quickly In addition, there are savings due to heat recovery since 2014. At present there are seven washing machines in the plant and a huge hall fan connected to community heating-waste heating network. Ten more washing machines will be added. “Our temperature level in the baths is 60°C and this temperature can also be generated with community heating”, describes Naupert about the requirement for conversion. “Only the electrical heating elements in the basin have to be replaced with a hydraulic element.” It takes minimal effort: in general 8000 Euros was enough for one machine, which pays for itself. “Our conversion from electrical to community heating saves us 6 cents per kilowatt hour and heat recovery saves further 2 to 3.5 cents. We have started heat recovery in the first four compressors on 10th September 2014”, says Naupert. “The overall costs amounted to 36,500 Euros without own financing and 20th February 2015 was the effective data for amortisation.” Community heating consumption reduces drastically In the first project phase, WAB has equipped two GA 30 FF compressors – both with fixed speed – and a speed-controlled GA 30 VSD FF with an energy recovery unit ER-S1 from Atlas Copco. A fourth GA 55 delivers its waste heat to the heating system of the company via a larger ER-S2 module. The second project phase was completed on time during Christmas 2014. Two GA 90 FF compressors are equipped with an integrated heat recovery unit and connected to heating return flow. Project phase 3 was completed in the first quarter of 2015 – with three ER-S2 units, which provide usable waste heat from three GA 55 FF. Naupert cannot summarise the amount of future heat requirement through heat recovery. “It is different each month, because these figures depend on external temperature”, says the energy manager. “But seen over a period of one year, we are now generating 25 percent of heat ourselves.” MDA Technologies 2/2016


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