The use of residual heat to preheat combustion-air for thermal oil systems

HTT introduces new innovation: The use of residual heat to preheat combustion-air for thermal oil systems with a capacity starting from 300 kW Thermal oil systems from HTT Energy GmbH have been supplying in the industry for many years with safe, energy-efficient process heat. We will be introducing a new innovation for using residual heat in small systems - the first of its kind in the world. It is now possible to preheat combustion air for systems with a capacity starting from 300 kW. The resulting improvement in performance sets new standards in energy efficiency. This kind of process has long since proven its effectiveness in larger systems. Excess heat generated by the production of process heat is used to preheat combustion air for thermal oil heaters. The cycle for process heat recovery therefore remains completely undisturbed. In addition to pre-heating combustion air, a heat recovery system for producing hot water can also be installed. This ensures, that nearly all of the generated heat is used in an efficient way << Small systems can now also reach an above average level of efficiency with very low losses. The excellent price/performance ratio also means a short amortisation period, which opens up new business potential particularly for small or low capacity plants << The system was developed by HTT in partnership with its subsidiary company, HTA, which is well known for its intelligent heat recovery systems. A renowned boiler manufacturer also supplied expertise to help adapt existing technology to lower capacity categories. With its new machine, HTT now enables air to be preheated for thermal oil heaters with a capacity of 300 kW or more. (Photo: HTT) The company: HTT energy GmbH Since 1967 the name HTT energy GmbH based in Herford, eastern Westphalia, has stood for process heat recovery using thermal oil technology. With its systems HTT always delivers temperatures accurate to the degree for every kind of production process: from -120° C to + 450° C and from 3 to 30,000 kW – always reliable, constant, efficient and environmentally friendly. So far many more than 11,000 systems have been delivered. Thermal oil boilers, electric heaters and temperature control devices, heating/cooling/deep freeze equipment, waste heat systems, steam generators - from small laboratory systems to highly complex reactor temperature control. All main components of thermal apparatus construction belong to the HTT delivery range. HTT customers place their trust in the many years of experience, consistent in-house manufacture, diverse service range and specialist competence of the interdisciplinary development team.

HTT thermal oil unit cuts energy costs in half at Xentrys in Leuna

Energy efficiency in practice: HTT thermal oil unit cuts energy costs in half at Xentrys in Leuna The chemical industry is extremely energy-intensive. Xentrys Leuna GmbH in Leuna, which mainly manufactures Polyamide 6, is no exception. In an attempt to lower their energy costs with lasting effect, Xentrys has broken new ground with regard to temperature control in their reactors by using thermal oil fired heaters from HTT Energy GmbH in Herford. Xentrys produces between 140 to 150 tonnes of Polyamide 6 per day using four reactors which must be maintained at a process temperature of 250 to 270° Celsius 24 hours a day. Up until now, one electronic heater has been in operation for each reactor. As a first step HTT replaced this heating set-up with a gas-fired unit, making the existing electronic system completely redundant. Overall efficiency: 92% From September 2010 to May 2011 the first HTT unit was in operation with a power of 1,250 kW. Equipped with an air preheater (LUVO) and speed regulators for the combustion air blower, the temperature control specialists from Herford managed to achieve an overall efficiency of 92%. Accordingly the cost balance was improved: primary energy consumption was cut in half from EUR 700,000 down to a present figure of EUR 350,000. Marcus Weber, production engineer at Xentrys: "The amortisation time of the whole project took less than one year – and that includes the add-on costs for the associated building and infrastructure measures such as general pipeline construction." The production expansion at Xentrys will soon be followed by the installation of the second HTT heating unit, which was also equipped with 1,250 kW, and the additional equipment already mentioned. It will take over the temperature control of two further reactors using double power. The challenge here is to achieve maximum redundancy between the old units and the new production line. If a thermal oil heater goes offline, the new reactors will be powered by the fully operational heater, while the available electronic heaters will supply the old reactors with process heat. Engineering with attention to detail What appears simple when considering the result actually required a high degree of detailed engineering. This included the procedural integration of the expansion tanks belonging to the four lines. At the same time, the four existing single units were converted into secondary circuits by installing corresponding control valves. In addition, the pressurisation of heat exchangers in the existing reactors was limited to specific maximum allowable working pressures. This required precise consideration of the individual pressure losses in the respective units. In spring 2012 all of the six reactors are scheduled to go online with HTT thermal oil technology. This guarantees not only a favourable energy cost balance for many years to come but also a complete back-up to ensure 100% plant availability. All that is possible with an amortisation time which will be of great interest to clever decision-makers. Marcus Weber (on the left), production engineer at Xentrys, and HTT sales manager Thomas Stieber in the Polyamide 6 production centre in Leuna. The fired HTT heater with duoblock burner and air preheater offers real benefits with regard to energy efficiency. The company: HTT energy GmbH Since 1967 the name HTT based in Herford, eastern Westphalia, has stood for process heat recovery using thermal oil technology. With its systems HTT always delivers temperatures accurate to the degree for every kind of production process: from -120° C to + 400° C and from 3 to 30,000 kW ; always reliable, constant, efficient and environmentally friendly. So far many more than 11,000 systems have been delivered.

Energy efficiency means more than

Interview with Hans-Günter Trockels, Managing Director of Kuchenmeister GmbH, Soest, manufacturers of fine confectionary and culinary specialities, with a production area of over 30.000 m² at various production centres. Why is the subject of energy efficiency so important for your company? Today the deliberate application of energy is indispensable for every enterprise. As well as this, environmental protection is also a crucial point because with every kilowatt hour of primary energy saved, the output of greenhouse gases is reduced. However, it is also a matter of exhausting all optimisation potentials when it comesto combating rising energy costs combined with simultaneously high competitive pressure. And there it is, energy efficiency, which rises far above all other considerations at the top on the ranking list of factors to be taken into account. In which areas do you see particular potential for optimisation. In our production centres, above all in the area of heat recovery. It is here that the expenditure for energy-efficient measures stands in a very positive correlation to its use. This has already been proven by HTT in cooperation with its subsidiary company HTA on two of our units at one of our plants. The results exceeded our expectations and so persuasively that we now have implemented these project measures at other locations. What kind of concepts are these and how large are their energy-saving potentials? HTT/HTA technology is intended to put to use the exhaust gas losses caused by oven heating. We aimed to supply the company with hot water using this method and thereby reduce the application of primary energy. Three heat transfer oil heaters were installed in the exhaust gas system, which independently suck the approx. 350 °C hot exhaust gas from the exhaust gas channel and feeds it back again at a temperature of 120°C. The chief attraction: Due to the full bypass ability, the actual baking process is not influenced by this operation in any way. Today, at one of our plants, we are able to cover almost all of our hot-water requirements via these heat recovery arrangements. Do you use any other technologies apart from heat recovery at your production sites? Within the scope of the project engineering of a new heating headquarters for our plant in Thuele, we were persuaded by another of the HTT/HTA concepts. In addition to the hotwater production via heat recovery, a combustion air pre-heater was installed between the heating source and the boiler with the aim of improving heat recovery. The result here was also more than persuasive: Now the entire heating arrangement has attained an efficiency of 96%. With this fact in mind, the whole investment will already have paid for itself after only few years.

High levels of utilisation provide for short armortisation times

The waste heat utilisation offers huge potentials for the improvement of energy efficiency. In this way, the heating system can be supported during the heating period. The supply of utilised energy to a different process within the company ; for example, with a closed loop GGH system, is even better. This provides high levels of utilisation and therefore short amortisation times. Even electricity production from waste heat, called ORC, is possible. It was some time ago that HTT / HTA first realised the first heat extraction process worldwide for an ORC process in the cement industry: This arrangement generates 1.2 MW of electricity from 8.2 MW of extracted heat.