Revamps 2023 Issue

Increasing efficiency of catalytic reformer unit fired heaters Application of ceramic coating on CRU heater tubing and refractory avoids oxidative scale formation, significantly lowering fuel consumption and CO 2 formation

Diyar Kiliç Mert and Alp Zeren Tüpraş Izmit Refinery Anton Korobeynikov and Sergei Merchev Integrated Global Services (IGS)

C atalytic reforming units (CRUs) are one of the high- est margin but most energy-demanding processes in oil refining. This flexible technology can produce high-octane gasoline components and individual aromatic hydrocarbons (xylene, benzene, toluene), which are raw materials for the petrochemical industry. The reforming process involves converting low-octane naphtha into a reformate at high temperatures and relatively low pressure. Catalytic reforming is typically carried out in a series of four reactors. Before entering each reactor, the feedstock is reheated to a temperature of 520-540°C. This reheating is achieved using high heat flux fired heaters consuming sizeable amounts of energy and emitting greenhouse gases (GHGs). Radiant coils within the catalytic reforming fired heater are made of 9%Cr chromium/molybdenum alloy (ASTM A335P9) and are subject to oxidation scale formation under firebox conditions. This oxidation scale may reach up to 1-2 mm thicknesses, reducing radiant coil thermal conductiv - ity, hindering radiant section efficiency, and significantly impacting the entire plant’s economic performance. Enhancing radiant efficiency A CRU with continuous catalyst regeneration (CCR) experiences a high rate of scale formation, approxi - mately reaching metal loss levels of 0.15-0.25 mm/year. The plant team thoroughly tracked the performance and detected an energy efficiency decrease due to scale for - mation. Every four years, during a major turnaround, the plant carried out activities to clean the external tube sur - faces. Nevertheless, a significant decrease in furnace effi - ciency was observed by the end of the second year after the turnaround. A detailed analysis of furnace operational data revealed the feasibility of high-emissivity ceramic coatings applica- tion to the radiant tube and refractory surfaces. The project was executed during a major turnaround, and the furnace performance analysis was carried out two months later. Post-project analysis showed a radiant efficiency gain of 13%, expected to last over the coating’s service life (8-10 years). Achieved radiant efficiency enhancement may be utilised for reducing fuel consumption along with CO2 emissions or throughput/severity increase under the same firing rat e .

Scale formation Refineries seek ways to find energy optimisation solutions in their processes and prioritises projects that are geared towards reducing fuel gas consumption and cutting GHG emissions. These initiatives align with strong commit - ments to a zero-carbon strategy, sustainability, and opti - mised energy usage, especially for units like the catalytic reformer. While catalytic reforming reactions occur in the stacked set of reactors, scale formation is observed on the external tube heater’s surfaces due to oxidation, fuel gas impuri - ties, and high heat flux. Oxidation scale formation results in the non-uniform heat distribution along the tubes and hotspots formation. Moreover, the radiant efficiency of the heater decreases with the corresponding fuel consumption increase. To prevent oxidation scale formation, the refinery decided to apply ceramic coatings to the furnace tube and refractory surfaces on-site during a turnaround.

A detailed analysis of furnace operational data revealed the feasibility of high-emissivity ceramic coatings application to the radiant tube and refractory surfaces

This case study pertains to the application of Cetek High Emissivity Coatings on both radiant tubes and refractory surfaces within the refinery catalytic reforming heaters. The primary objective was to enhance radiant efficiency and facilitate the sustainable operation of the heater for the next 8-10 years. Ceramic coatings nowadays are approved materials to increase the energy efficiency of fired heaters or debot - tleneck the heaters with various limitations, such as bridgewall temperature (BWT), firing duty or uneven heat flux distribution. Initially developed in the 1970s, coatings have found successful use in all heavy industrial appli- cations, including metals processing, aerospace, glass industry, and fertilisers but became especially beneficial in the oil and gas and petrochemical industries.

Revamps 2023