This article was originally published in the November issue of COMPRESSORtech2. We only publish a fraction of our magazine content online, so for more great content, get every issue in your inbox/mailbox and access to our digital archives with a free subscription.
Editor’s Note: This paper is condensed from a technical paper that was presented at the 2018 Gas Machinery Conference in Pittsburgh, Pennsylvania.
By Chas Ogden
It is common in the industry to use periodic analysis of lubricating oil with two fundamental objectives in mind. Firstly, this periodic analysis is used to gauge the suitability of the oil for continued use with the goal of performing condition-based oil changes. Secondly, best practices of oil analysis represent a powerful reliability tool and yields information about wear metals and contaminants, which may be used to identify mechanical issues and prevent catastrophic failures.
A key limitation of traditional oil analysis programs is the lag time from the collection of each sample (typically collected monthly), and the delivery of meaningful results by the lab (this lag time typically is seven to 45 days). Use of an automated oil sampling system for real-time oil condition monitoring offers advantages for operators. This paper explores how such a system was able to help understand and resolve oil fouling issues in a natural gas engine.
The real-time oil sensors measure metrics such as pressure, temperature, viscosity, dielectric constant, particle loading and flow rates for makeup oil (engine) and compressor lube oil (frame, cylinders and packing cases). Using data collection and communication systems, this data is transmitted to a proprietary “dashboard” where this real-time information and analytical results are available to secure web users.
The system features the ability to automatically fill oil sample bottles, which can be set for automatic sample collection either based on a routine operating time interval or based on a sample by exception. If the oil condition monitor’s edge processing yields a potentially dangerous trend in any measured parameter(s), such as viscosity, the system automatically fills a bottle and instantly notifies key personnel via email and SMS messaging. This sample is then processed by a laboratory with same-day turnaround so that results are available to the customer within days as opposed to one or more weeks.
LogiLube LLC, the system manufacturer, and DCP undertook a field demonstration of the monitoring system on a key gas engine-driven propane refrigeration compressor in DCP’s East Texas Complex gas-processing facility outside of Carthage, Texas. Given that this machine plays a pivotal role in the production of liquid products in East Texas, it was expected that valuable information could be obtained that would help the reliability team at DCP ensure this asset’s availability by making real-time decisions about equipment condition and lube system performance.
Engine 1202 (E1202), a GE-Waukesha L-7044GSI engine, and Compressor 1202 (C1202), a two-stage Ariel JGK-4 compressor, were instrumented with the SmartOil systems for the duration of the 26-week test project (Figure 1).
Real-time oil quality measurements, oil consumption metrics, tangible machine events and laboratory analysis of physical oil samples are combined within a single database to provide data analysis and comparisons relating to an almost unlimited combination of parameters (i.e., particle count vs. number of shutdowns) and across different assets (i.e., oil viscosity of C1202 vs. E1202).
As a note, the two mechanical systems consisting of E1202 and C1202 share a common oil source. Given that the oil feeding both machines is guaranteed to be consistent, analytics can make comparisons relating to the effects of operating conditions (engine vs. compressor) on both the rate of oil degradation and the levels of measurement noise — interference — introduced into the real-time measurements.
Throughout the pilot, real-time oil quality and machine data was measured and recorded almost constantly throughout the 26-week project, interrupted by several small outages because of severe weather and/or unrelated power issues within the plant.
As part of the monitoring process, a real-time web dashboard is always available to the customer, allowing them to view data metrics and analytics results regarding their equipment instantly.