Energy conservation has assumed vital importance in the industry particularly in Petroleum and Petrochemicals, Fertilizers and other Process Industries. With exponential rise in the energy consumption and consequent surge in the crude oil prices, energy conservation measures have become more relevant. Fired Heaters are major consumers of energy and it is of utmost importance to increase their thermal efficiency to the best possible level. Preheating of combustion air is the best option to raise a heater’s thermal efficiency and thereby recovering waste heat.
The industry norms have changed over the years and thermal efficiencies of 90-92% have become imperative for the heaters. It has been required to design and operate heaters to dispose off flue gases at lowest possible temperature. Typically, flue gases leave the convection section of the heaters at around 350 to 450°C and a cast type air pre-heater can bring down it’s temperature to around 200°C, resulting in ~10% increase in the efficiency (1% increase in efficiency for every 20°C drop in flue gas temperature). The temperature of flue gas can be brought down further to around 160°C or less in a glass tube air pre-heater, resulting in further efficiency improvement of ~2% or more. Many fired heaters working in the industry today are more than 20 years old operating at thermal efficiency of 75-80% or lower. These heaters can be considered for retrofitting with new air pre-heaters to raise the thermal efficiency to maximum level.
At today’s cost of energy, the pay off period for an air pre-heater system could be less than a year besides the advantage of controlled pollution.
Cast Tube Air Preheater (CTAP)
Cast Tube Air Preheater is recuperative type heat exchange equipment where flue gas exchanges heat with combustion air by convective heat transfer. It is an assembly of rectangular cast tubes with integral fins on both internal and external surfaces. The tubes are assembled inside a structural frame. To ensure that no leakage of air takes place, gaskets are provided on all mating parts and all tube sealing surfaces are machined. The equipment is fully shop assembled in modules and tested for leak tightness before dispatch to project site. A modular construction is used to shorten the erection time at site.
KEC has supplied more than 150 Cast Tube Air Pre-heaters to date giving satisfactory and uninterrupted service to clients under varied process conditions.
Some of the major advantages of Cast Air Pre-heaters supplied by KEC are:
- Higher base metal thickness for extra corrosion allowance enhancing the equipment life
- Customized design in modular construction, easy to install, with minimum site work
- Machining of all tube mating surfaces and use of high quality ceramic gaskets for leak tightness
- Fully shop-assembled modules, tested for leak tightness before dispatch
- Ensuring no cold-end corrosion of the equipment while firing sulfur-bearing fuels
- Provision of ladder type water wash arrangement for cleaning of soots from tube surface
Glass Tube Air Preheater (GTAP)
Glass Air Preheater is also recuperative type heat exchange equipment used for low temperature heat recovery. It comprises of borosilicate glass tubes inserted into tube sheets of carbon steel metallurgy lined with Teflon. The other sides are cladded with SS904L sheets. Tube-to-tube sheet joints are provided with special bush / glands to minimize leakage. Glass Air Pre-heaters recover additional heat from flue gases at lower temperature and are resistant to cold end corrosion.
KEC has supplied more than 30 Glass Tube Air Pre-heaters to date giving satisfactory and uninterrupted service to clients under varied low temperature process conditions.
Some of the major advantages of Glass Tube Air Pre-heaters supplied by KEC are:
- Customized design in modular construction, easy to install, with minimum site work
- Fully shop-assembled modules, tested for leak tightness before dispatch
- Providing specially-designed tube-to-tube sheet joint and acid-resistant lining on tube sheets as well as on casing to ensure no damage to the equipment even during operational upsets
- Provision of ladder type water wash arrangement for cleaning of soots from tube surface
Click here if you would like to receive a copy of KEC Cast & Glass Reference List |
