Improved Coatings to Efficiently Prevent Fouling in Centrifugal Compressors

Improved coatings to Efficiently Prevent Fouling in Centrifugal Compressors

Sergio Ghezzi

Centrifugal Compressors Product Manager

BHGE

Francesca Monti

Petrochemicals Platform Manager

BHGE

Marco Romanelli

Engineering Manager - Materials Science and Engineering

BHGE

Alice Pranzetti

Lead Engineer - Materials Science and Engineering

BHGE

Prepared for Presentation at the 2019 Spring National Meeting

New Orleans, March 30^th 2019

AIChE and EPC shall not be responsible for statements or opinions contained in papers or printed in its publications

Improved Coatings to Efficiently Prevent Fouling in Centrifugal Compressors

Charge gas fouling is not a new challenge for ethylene plant operations. A major contributor to the fouling phenomenon is increased process gas temperature which is typically observed in steam crackers with gas feedstock. In addition, the market focus on capital expenditure is also impacting charge gas temperature in both liquid and gas cracking facilities. To drive down rotating equipment costs, the number of compression sections in the train is being reduced. However, fewer sections of compression increases sectional pressure ratio and results in higher gas temperature which exponentially increases the risk of polymerization.

Polymer deposits in the compressor internals are inhibited by water injection and anti-fouling coatings or removed with solvent injections. The evaporative cooing effect of water is essential for temperature control and to prevent polymerization. However, introducing water or oil solvents into the flow path causes liquid droplet impact erosion on compressor internals, damaging components and removing traditional coatings e.g. traditional organic base and spray PTFE type paintings. To minimize the erosion effect of the frequent washing cycles, electroless nickel plating, with high phosphorous content (ENP-11% P) has been implemented. This metallic coating is erosion resistant and has proven to be an acceptable compromise between durability and fouling resistance.

Fouling resistance is further improved with a modification to the ENP-11%P matrix. PTFE nano-particles are incorporated into the process and distributed homogeneously in the coating surface. The PTFE-doped ENP-11%P is erosion and corrosion resistant and has demonstrated excellent anti-fouling properties versus traditional solutions. Moreover, the coating is applied by chemical deposition yielding a uniform coating thickness over the entire surface of the subject component.

The material properties and fouling-release results for ENP-11%P modified with PTFE nanoparticles are discussed herein including experience in process gas compressor application.