Effective fault diagnostic and prognostic methods tailor-made for field operating oil-sand pumps
現場油砂泵的故障診斷與剩餘生命預測
Student thesis: Doctoral Thesis
Author(s)
Detail(s)
Awarding Institution | |
---|---|
Supervisors/Advisors |
|
Award date | 15 Jul 2014 |
Link(s)
Permanent Link | https://scholars.cityu.edu.hk/en/theses/theses(056804a6-5731-42f4-9b07-3f1f5635e475).html |
---|---|
Other link(s) | Links |
Abstract
To ensure continued profitability in today's increasingly competitive market,
industries need to work at near-maximum yields while maintaining high reliability and
operational safety. However, production equipment can rarely be maintained at its
maximum capacity because it inevitably deteriorates with use and ageing. Without proper
maintenance, equipment can fail in unexpected ways, leading to the possible termination
of services, loss of production and, in the worst case, human casualties. Hence, it is
important to conduct proper fault diagnosis and prognosis via condition-based
maintenance (CBM) so that the remaining useful life (RUL) of equipment can be
predicted as it degrades.
Slurry pumps are commonly used in mining and heavy industry, such as in the
extraction of synthetic crude oil from oil sands. This kind of slurry pump is referred to
here as an oil-sand pump. The pump impellers and other components are prone to
significant degradation as they are under continuous impact from the sand and small
stones embedded in the oil. Oil-sand pumps are expensive to replace due to the high cost
of manufacturing the pump components, which must be more durable than those of pure water or liquid pumps. Moreover, the unexpected shut-down of an oil-sand pump can
yield a loss of over a million dollars per day in the oil production industry. To reduce the
time required to repair the pump components and the associated financial loss, effective
fault diagnosis and prognosis methods that are tailor-made for the field operation of oilsand
pumps are urgently needed.
Although numerous CBM methods have been developed, most have been verified
only by simulations or experiments conducted in well-controlled laboratory environments,
and few have been tested on equipment that is actually operating in the field. This thesis
presents some fault diagnostic and prognostic methods that are tailor-made to ensure the
effective operation of oil-sand pumps in the field. Three techniques contributed to the
effectiveness of the methods. The first was the application of exponentially weighted
moving average (EWMA) control charts to identify the obvious shift point from the
signal trend for confirming the occurrence of an anomaly in the monitored equipment.
Four types of EWMA chart were studied and compared and charts yielding superior
performance with respect to the detection of incipient anomalies were identified. Second,
two unsupervised clustering ensemble methods were developed to assess the wear status
of a monitored pump and then classify the wear severity. Once the obvious shift point for
confirming the occurrence of an anomaly had been successfully identified and the fault
had been diagnosed, the third technique involved the design of a relevance vector
machine (RVM)-based model to predict the RUL of the damaged pump impeller. All
three techniques were verified using operational data collected from running oil-sand
pumps.
The findings indicate that the oil industry could minimize production downtime and
thus achieve a dramatic decrease in maintenance costs and human casualties by applying
the three techniques identified in this thesis. These methods could also be modified to suit
other types of machines exhibiting similar degradation trends, such as deep hole drillers,
coal milling machines and rock crushers used in mines. Like oil-sand pumps, these
machines suffer from continuously generated severe impacts when handling hard
materials.
- Maintenance and repair, Oil well pumps