Compressor Fouling Monitoring Methods Identify Changes in Fouling Mechanism to Direct Mitigation Performance Improvement

Fouling within an olefin plant’s cracked gas compressor is a relatively common occurrence. Almost all gas crackers report some concern with compressor fouling, while significant percentages of liquid and mixed feed crackers also report fouling concerns. In some plants, the fouling occurs to a degree that imposes minimal operational limitations. The primary concerns in these plants are an increase in energy consumption and throughput limitations should something cause the rate of fouling to increase. However, other plants consistently struggle with fouling that limits operational reliability and throughput capacity. A variety of fouling mitigation methods are available: internal coatings, specialty wash-oils, antifoulant additives, etc. In most cases, the fouling is caused by a reactive polymerization mechanism. Quite often, this is a free radical mechanism, but Diels-Alder mechanisms have also been identified. Changes in feedstock and/or cracking severity can change or shift the dominant fouling mechanism. As the fouling mechanism changes, the effectiveness of the mitigation method may also change. In this paper, we will discuss fundamental monitoring methods to aid evaluation of compressor performance and possible changes in fouling mechanism in order to direct changes in fouling mitigation techniques. Laboratory tests on process stream samples and operational data analysis procedures will be demonstrated. A case history will be presented to demonstrate how this methodology was used to facilitate performance improvement with an additive antifoulant mitigation method.