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

Energy efficiency in practice: HTT thermal oil unit cuts energy costs in half at Xentrys in Leuna

The fired HTT heater with duoblock burner and air preheater offers real benefits with regard to energy efficie

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.

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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. 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.

Seit 1967 steht der Name HTT energy GmbH mit Sitz im ostwestfälischen Herford für Prozesswärmegewinnung mittels Thermalöl-Technologie. Mit seinen Anlagen liefert HTT immer die gradgenaue Temperatur für jede Art von Produktionsprozess: von -120° C bis + 450° C und von 3 bis 30.000 kW – sicher, konstant, effizient und umweltschonend. Bis heute sind weit mehr als 11.000 Anlagen ausgeliefert: Thermalölkessel, Elektroerhitzer und Temperiergeräte, Heiz-Kühl-Tiefkühlanlagen, Abhitzesysteme, Dampferzeuger – von der kleinen Laboranlage bis zur hochkomplexen Reaktortemperierung. Alle wesentlichen Komponenten des thermischen Apparatebaus gehören zum HTT-Lieferprogramm. HTT-Kunden vertrauen auf die langjährige Erfahrung, die konsequent eigen Herstellung, das vielfältige Dienstleistungsspektrum und die Fachkompetenz der interdisziplinären Entwicklungs-Teams

HTT Energy GmbH
Thorsten Stahlberg
Füllenbruchstrasse 183
32051 Herford