Aftermarket Heater Technology Continuous innovation in regenerative heat exchangers

Rotary heater upgrade or enhancement is usually the most cost effective way to improve existing boiler performance. Howden’s programme of continuous product development enables us to improve the performance not only of our own equipment but also that of other manufacturers. Our upgrade and retrofit proposals draw on state-ofthe-art technology to bring your existing equipment up to the performance level of a new unit.

Upgrading air preheaters to the latest technology standards brings a wide range of benefits: Leakage reduction reduces the power demands of the fans and reduces the onward flow rate to the gas cleaning equipment increasing its performance. Optimising the heat transfer element profile and height can improve overall performance significantly. Enamelled elements offer both excellent corrosion protection and cleanabilty. Highly efficient cleaning devices minimise pressure drop drift and maximise availability. It is common for plant operating conditions to change over the years. Changes such as the...

The leading manufacturer of heating elements Howden manufactures all types of heating elements for rotary regenerative air and gas heaters irrespective of the original manufacturer. From research and development, through tender preparation, manufacture, installation and commissioning, we enforce rigorous quality standards. Our focus is on product performance and reliability. A reputation for quality and service We are accredited to ISO 9001, ISO 14001 and OHSAS 18001 and are regularly audited by major customers and internationally recognised assessment organisations. Howden have manufactured...

Element design and technology We currently have a wide range of profiles available, enabling us to offer the right balance of thermodynamic performance, pressure drop and ease of cleaning for any situation. We can supply elements in a variety of materials, including: Howden expertise is available to recommend alternative profiles or arrangements that can improve the performance of the regenerative heat exchanger, particularly if the operating conditions have been changed since the original elements were specified. Decarburised steel enamelled The right profile at the right time Elements can be...

Element fouling solutions Hot end elements can be prone to fouling as a result of large particles of fused ‘popcorn’ ash becoming lodged in the element passages and smaller particles compacting behind them. This is generally caused through insufficient ash being present in the flue gas to absorb the condensing sulphuric acid arising from the combustion and oxidation of sulphur in the fuel. With excessively low cold end element temperatures, this condensation can produce problems with cold end fouling. The use of a aerodynamically ‘closed’ profile elements as embodied in our range of HC Element™...

SurePack Elements As heat transfer elements are regularly subjected to high energy excitation forces from the sootblowers used to clean the elements, it is essential that these elements are sufficiently tightly packed in their containers to minimise the element vibration and consequent fatigue damage. Whenever enamelled elements are used, it is equally important that the element packs are not over compressed as this can cause localised damage to the enamel coating that can lead to subsequent pack loosening during heater operation. As part of our commitment to the ongoing development of our element...

Enamel coating produces an element with the combination of both corrosion protection and good cleanliness when used in the rigorous environments experienced in the low temperature, cold end layers of air heaters, and the even more aggressive regimes associated with FGD gas heaters and air heaters located after SCR DeNOx installations. In a continuous and ongoing development programme, Howden have optimised the appropriate parameters of enamelling processes, quality, cost and service life and, consequently, can offer our customers a highly competitive product for all air and gas heaters, to a...

Enamelling process Rotary heat exchanger elements are frequently exposed to very severe fouling and corrosive conditions. High quality acid-resistant vitreous enamelling provides effective resistance to these hazards and Howden works closely with specialist suppliers to offer coatings of the highest quality. The quality and life of the enamel coating depends on a number of critical factors including: Base material Enamel constituents Enamel thickness Enamelling technique. Howden’s vitreous enamel is produced from natural, inorganic raw materials and has a minimum amount of additives in order...

SureCoat™ Plus (enamelled mild steel) and SureCoat™ Premium (enamelled LACR steel) In the past, it was not possible to manufacture high quality enamelled cold end elements for heaters using standard mild steel or Low Alloy Corrosion Resistant Steel (LACR). After carrying out extensive research, we have now developed the breakthrough technology that allows us to meet customer demands for these elements. Standard mild steel and LACR are more widely available. The new materials enable effective washing or sootblowing. Greater strength and corrosion resistance increases element life. Reduced fouling...

Air preheater technology and experience Leakage sealing systems Over the many years of our ongoing heater applications experience, Howden have investigated and developed a large number of different leakage sealing system designs to both minimise leakage level and eliminate the 'leakage drift' that inevitably occurs in actuated systems with time. In that respect, the sealing system for which Howden is most renowned is our advanced VN sealing system which keeps leakage consistently low for extended periods. The original VN sealing system was developed as a result of Howden’s experience which showed...

Enerjet™ cleaning system The Howden Enerjet cleaning system is method of on-line high pressure water washing of air preheaters designed to provide effective and efficient cleaning of severely fouled heat exchanger elements while the air preheater is in normal use. It is has been designed to be used as an emergency fallback alternative in the event that normal sootblowing practices prove inadequate to keep the heat transfer elements clean. By eliminating the problems of lost availability that arise due to excessive fouling, the Enerjet™ system can repay its initial investment in well under a year,...