(90d) Enhance Cracked Gas Compressor Reliability with Novel Antifoulant Technology

 
It is widely known that there is a potential for fouling in Cracked Gas Compressors within Ethylene plants. Gas crackers have generally had a higher fouling potential than liquid crackers due to the lack of aromatic gasoline formed in the cracking process. Typical fouling preventive measures have been to inject wash oil and/or wash water. While the cracked gas compressor remains a major reliability concern in operating units, it has been observed that fouling rates in liquid crackers have increased substantially over the years. As a result, refiners are ever more concerned with optimum compressor performance. Costs associated with such fouling run high and can increase exponentially.

As the compressor section of any ethylene plant is the most energy intense unit of the plant and yet the most unreliable, it has been the cause for many a shut-downs. Significant losses in terms of energy and economics are incurred by ethylene plants due to CGC system fouling. 

Compressor Fouling is a vicious cycle and so the onset of fouling needs to be better managed to ensure no subsequent hindrances occur. Conventional chemical programs, though popular, have had limited success as insoluble polymers continue to form and hamper normal operations. As a result of the imperative nature of this fouling control, Dorf Ketal has conducted extensive research on the fouling seen in the compressors.

The fouling mechanisms and foulant pre-cursors have been studied in detail in a bid to understand the root cause of fouling and to develop cost effective mitigation plans. Over the last few years, a multi-purpose singly formulated antifoulant has been created such that it can also work in synergy with wash oil injection and help reduce the insolubility of the polymers formed. This is a big step in improving compressor run-lengths and reducing total cost of ownerships.  

This paper will present the variety of fouling species and the characteristics of fouling found in plants operating with different feeds. The paper shall also discuss improved field monitoring and support to help determine the efficiency of the program.  Monitoring of the operating conditions and machine monitoring through statistical modeling of dependent variables have been under-taken in the past. This paper will however present improvements that shall help identify cause of real time fouling and fouling rates.

It has been our experience in several plants that the deposition of polymers on the surface of after coolers have had a significant impact on the run-length of the plant and using a properly chosen program helps improve overall system reliability. The paper shall discuss a few case studies where such improvements have been delivered leading to improved production and reliability resulting in significant profitability increase.