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Textile manufacturer can breathe easy thanks to LTB

State-of-the-art regenerative thermal oxidiser (RTO) technology with external waste heat recovery (WHR) reduces emissions, utilises waste energy, and lowers operating costs of a textile manufacturing process.

Sustainability Challenge:

Reducing energy consumption and optimising operating costs whilst meeting statutory exhaust emissions limits are priorities for most manufacturing companies in the industrialised world. Typically, air purification is regarded a necessary evil rather than part of the solution itself. However, under the right circumstances, combining air pollution control and energy recovery in an integrated system can provide significant, sustainable, economical and environmental benefits.

By making better use of process energy through more intelligent application of the state-of- the-art air pollution control technology combined with external waste heat recovery systems, operating costs can be lowered, emissions can be further reduced whilst enhancing scope for future, sustainable increases in manufacturing output.

Using engineering skills and know-how derived from over fifty years in the air purification business, LTB, Luft- und Thermotechnik Bayreuth GmbH in Goldkronach was able to design, develop, manufacture, install and commission and an energy-efficient air pollution control system which paid for itself within the first two-and-a half years of operation.  Indeed, so significant were the savings that, five years on, and on the back of increased capacity demands, the client opted to install a second, turn-key ROxiTHERM RTO system from LTB.  This will operate in parallel to the first with the added benefit that production downtime can be reduced during routine RTO servicing and maintenance.

Situation Overview:

A European textile manufacturer specialising in the production of continuous polymer sheets for automotive, pharmaceutical and construction industries and proofed (coated) fabrics for automotive and stationary applications was spending an inordinate amount of money on fuel costs to run and maintain an old, inefficient, air purification system.  The system was also struggling to cope with the growing demands of the expanding business.

Installed with the primary objective of meeting statutory emissions limits, subsequent modifications to make use of waste heat energy by delivering steam to the dryers and heat to the production building were only partially successful.  The result was considerable system inefficiencies, spiralling fuel costs and major operational issues as production requirements increased.

The Solution:

The LTB solution provided for the replacement of the old thermal oxidiser (TO) unit with a compact RTO system, engineered to fit a tight space immediately adjacent the existing unit.  The LTB ROxiTHERM RTO system was installed and commissioned in 2008 and featured:

  • Compact 3-bed RTO system suitable for flow rate of 50,000 Nm3/h (and autothermal operation < 2g/m3)
  • 5t/h steam boiler and warm water heat exchanger for excess energy re-use
  • Special access platform and "burn-out" mode for maintenance purposes

By replacing the old TO with a state-of-the-art thermal gas cleaning system with integrated regenerative pre-heating (RTO), it was possible to reduce the overall fossil fuel energy requirements by ca.60% whilst increasing volumetric flow capacity from 25,000 to 50,000 Nm³/h.  ROxiTHERM RTO technology also enabled regulatory limits to be safely maintained at relatively low operating costs - even at low VOC concentrations and high flows.  

Use of the RTO resulted in autothermal operation at concentrations of less than 2 g/m³ - as opposed to 8 g/m³ with the TO.  This meant the burner system was typically only required during start-up owing to the high internal heat utilisation and (>1:5) control range of the new plant. Indeed, even, at minimum loads, no additional fuel was required for air purification.  

LTB's scope of supply also included delivery of a hot water heat exchanger, an integrated steam boiler, as well as a new air supply system. The hot water (instead of air-to-air) heat exchanger was installed on the clean gas side to avoid formation of condensate and prevent corrosion without increasing material costs. This utilised the residual heat from the temperature differential between clean gas downstream of the RTO and steam boiler (ca.150°C) and that of the process air stream (ca.80°C) to warm the fresh air to the production facility.

Average solvent emissions levels from the process were ca.5-6 g/ m³, hence excess energy was available. Since this correlated well with the steam requirements in the production process, this heat from the solvent oxidation could, thus, be optimally used in the steam boiler. This steam generator was installed to generate process heat in the form of saturated steam from the excess energy from the solvent combustion.   When the amount of steam produced was insufficient, auxiliary burners in the ROxiTHERM unit were fired-up.  In this way, only as much vapour was generated as was actually required.  This was a key advantage of the RTO over the old system.

The capacity of the existing water treatment system was also adapted to the new steam boiler, thereby saving the cost of a new treatment system.

These new features ensured the system fulfilled the customer's requirement for continuous operation of the production process.  The reduced operating costs resulted in a return on investment within 2½ years

Sustainable Strengths:

The combination of state-of-the art ROxiTHERM RTO technology with suitable external WHR techniques was able to provide clear, sustainable economic and technical benefits for the textile producer, as well as significantly lower fuel costs.  The turn-key air purification systems from LTB saved energy by delivering stream to the dryers and heat to the production building only when required whilst also meeting required exhaust emissions levels with capacity to spare thereby providing scope for further production growth at the client.

Thanks to the flexibility of the energy-efficient air purification system from LTB, the business was able to meet increasing demand for its products and initiate further expansion plans sooner than expected owing to an impressive payback period of just two-and-a-half years.

Above all, this project demonstrates that under the right conditions, suitably-designed and optimised energy-efficient air pollution control systems can deliver both sustainable economical and environmental benefits, highlighting what can be achieved by taking an integrated approach to energy and emissions - where aftertreatment is no longer just an afterthought.

Sustainable Solution Provider:

As one of the leading engineering companies in the field of industrial air pollution control with almost 300 ROxiTHERM RTO systems installed worldwide, LTB, Luft- und Thermotechnik Bayreuth GmbH was well-placed to understand both the economic and environmental issues facing the client and to develop a suitable energy-efficient turn-key air purification system solution to this particular problem

Having developed solutions across a wide range of industry applications, LTB engineers were quickly able to identify the key issues and to design the optimum solution for this particular textile manufacturing process. In-house Engineering Design, Process Engineering, Manufacturing Electrical Engineering, and Installation & Commissioning teams co-ordinated by LTB Project Management engineers ensured the highly-efficient, multi-component, turn-key system met all client expectations including the need to engineer the system in the tight space around the existing unit at the plant.

LTB, Luft- und Thermotechnik Bayreuth GmbH employs over 130 highly-skilled engineers in and technical staff in two locations, generating annual sales revenues of ca. 25 million €.

LTB™, Breathe Easy™ and ROxiTHERM™ are trademarks of LTB, Luft- und Thermotechnik Bayreuth GmbH, Goldkronach, Germany.

* since end-use applications of client's coated/proofed textile products  include roofing materials for convertible cars, folding bellows on "bendy-buses" and tarpaulin covers for heavy-duty trucks)

Brief profile of the company:

Name: LTB, Luft- und Thermotechnik Bayreuth GmbH
Headquarters: 95497 Goldkronach / Germany
Year established: 1958
Employees: 130
Solutions: Waste Gas Cleaning Systems
Internationality: LTB America