Cetek Ceramic Technologies have been applied at more than 200 refining/ chemical processing sites around the world. Cetek has been developed by pioneers in the ceramic coating industry to improve and sustain the efficiency of heat transfer in fired heaters. Facilities that choose to apply Cetek can expect long-term performance and significant ROI.
As an integral and unique part of IGS’ Cetek Ceramic Coating service, a complimentary technical evaluation is performed on all fired heaters before a proposal is provided.
Data is collected by IGS technicians from the plant. It comprises an IR Thermography inspection completed by IGS with operating data corresponding to the precise time and date of the IR inspection.
To determine how close current operating conditions are to design, complete design specifications are required, together with general arrangement drawings of the fired heater.
The evaluation can also project further, more reaching benefits in flexibility of operation, such as C5 + RONC Octane increase at current production/firing rates and potential for leaner feedstock flexibility, or lower cost naphtha.
Cetek High Emissivity and Thin-Film Coatings
Cetek Ceramic Coatings will prevent process tube oxidation and carburization and maintain heat transfer to the process. High Emissivity Cetek Coatings for refractory surfaces will increase radiant absorbed duty and encapsulate fiber surfaces. The application of Cetek Coatings will maximize radiant absorbed duty and optimize heater operation alleviating bottlenecks and decreasing fuel usage and CO2 & NOx emissions.
Is your fired heater limited by bridge wall temperature, tube metal temperature or firing duty? The cause could be excessive fouling/scale formation on the radiant tubes. Cetek’s Tube-Coat service addresses all these issues and brings the tubes back to an as-new condition. The High Emissivity Ceramic Coatings ensure that the tubes remain in this clean state for an extended period.
Cetek Ceramic Coatings provide a durable, protective, thin-film layer on the outer surfaces of process tubes, which prevents oxidation, corrosion, and carburization of the metal and maintains the tube thermal conductivity coefficient close to new tube conditions.
Oxidation and scale formation on the outer surfaces of process tubes reduces conductive heat transfer, resulting in low production rates and/or excessive fuel consumption.
Cetek’s High Emissivity Ceramic Coating system ensures optimum maximum conductive heat transfer for the process.
An industry trend to operate fired heaters more efficiently, at lower excess oxygen levels, to save fuel and reduce CO2 emissions has increased the potential for carburization of external surfaces of radiant section tubes.
This leads to grain boundary penetration of carbon, carbide formation, embrittlement of the surface, crack formation and loss of metal.
The result is a reduced service life of the radiant tubes.
Radiant tube external surfaces were protected from carburization by Cetek Ceramic Coatings in applications in major refineries in Asia Pacific and India.
In each case, the life of the coating was at least 10 years, during which time there was no evidence of carburization.
If process tube life is limited by wall thickness reduction caused by oxidation or carburization, Cetek’s High Emissivity Ceramic Coatings will overcome this limitation and extend tube life.
Measuring tube metal temperatures is vital to the reliable operation of fired heaters. The presence of oxidation and layers of scale on the tube surfaces interferes with the accurate determination using IR thermography, or optical pyrometers, since the external surface of the fouling layer could be significantly higher than the actual metal temperature.
Cetek’s high emissivity ceramic coatings prevent oxidation and scale formation and provide a consistent temperature gradient between the coating surface and the metal. This allows an accurate determination of the actual metal temperature and a return to reliable operation.
Increasing Radiant Section Heat Transfer Efficiency
Cetek’s high emissivity ceramic coatings applied to the process tubes and refractory surfaces provide a significant improvement in radiant section heat transfer efficiency, which varies for different types and designs of fired heaters, or tubular reformers. To derive the most benefit, it is important that a complete technical analysis/evaluation of the effects of the application is completed beforehand.
The benefit in the radiant section and the effects on the convection section are studied and reported before any commitment is made by the client or Cetek.
Typical high emissivity ceramic coating applications to the tube and refractory surfaces show heat transfer efficiency benefits ranging from 5% to 15%, depending on service and heater configuration.
Why High Emissivity?
In the radiant section of a fired heater, much of the radiant energy from the flame/flue gas is transferred directly to the process/catalyst tubes; however, a significant proportion interacts with the refractory surfaces. The mechanism of this interaction has an appreciable effect on the overall efficiency of radiant heat transfer. A major factor in determining the radiant efficiency is the emissivity of the refractory surface.
Cetek pioneered the use of high emissivity ceramic coatings applied to the refractory surfaces in radiant sections of fired heaters and tubular reformers. It has now become an accepted means of improving the efficiency of radiant heat transfer, leading to energy savings as well as environmental and reliability benefits. We have developed and used reliably for many years a range of ceramic coatings for different substrate types, operating environments and targeted application benefits.
In fired heaters and tubular reformers, the necessary thermal energy to drive the endothermic processes is provided by burning a fuel/air mixture and transferred to the process by three heat transfer mechanisms: radiation, convection, and conduction. The primary means of heat transfer is by radiation.
The increase in radiant heat transfer efficiency may be used by Cetek’s clients to save fuel consumption, while maintaining production rate. Energy savings range from 5% to 15%, depending on service and heater configuration.
The increase in radiant heat transfer efficiency may be used by Cetek’s clients to increase production rate, while maintaining fuel consumption. Production increases range from 5% to 15%, depending on service and heater configuration.
By improving radiant section heat transfer efficiency, more of the available heat generated by the burners is absorbed by the process. This means that the flue gas temperature leaving the radiant section (BWT – Bridgewall Temperature) will be lower. If your fired heater is limited by BWT, Cetek’s high emissivity ceramic coatings are a simple, cost-effective fix.
Firing Duty Limited
More efficient heat transfer in the radiant section will overcome any firing duty limitation – a solution readily available from an application of Cetek’s high emissivity ceramic coatings.
Reducing emissions while ensuring adequate supply of hydrocarbon derivatives is a complex issue for the refinery operators and chemical producers. At a company level, Environmental, Social, and Corporate Governance (ESG) initiatives have been put in place to provide practical solutions to these emissions issues, while continuing daily operations. Many industries and economies rely on hydrocarbon derived products. Our everyday products, including medicine, clothing, toothpaste, and even solar panels start their lifecycle as unrefined petroleum. Demand for most of these items is not expected to drop with our growing population, while initiatives focusing on production from plant-based materials are still in their infancy.
In coking sensitive fired heaters, etc., the coking reaction is initiated by high tube wall temperatures. The coke is laid down on the internal surface of affected tubes and leads to progressive increases in tube metal temperature and accelerated coke formation and oxidation/scale formation on the external surfaces. The result is a reduction in production and a necessary shutdown, or halt to decoke the tubes.
Cetek’s dual emissivity ceramic coating system allows an effective heat flux manipulation, reducing tube metal temperatures in high heat flux areas and reducing the rate of coke formation. This results in an extension of run length between decoking activities.
The process consists of the application of high emissivity ceramic coatings to selected areas of the refractory surfaces and a combination of high and low emissivity ceramic coatings to the tube surfaces.
This Dual Emissivity Coating System effectively shields the tube surfaces in high heat flux areas but increases heat absorption in lower heat flux areas. This prevents rapid coke formation while at the same time eliminating uneven scale formation, thus allowing accurate tube metal temperature measurements.