The following is a continuation of our previous discussion on rubs. We will begin with a brief review of some basic concepts and then give an example of a rub with supporting data plots. In upcoming blog articles which will continue this discussion, additional rub examples will be depicted.
Damping helps remove energy from a system through resistance to motion. For rotating equipment, damping is necessary to prevent vibrations from damaging the rotor, bearing or other components. Unlike rolling element bearings, fluid film bearings have a significant amount of damping. But even the damping provided by fluid film bearings is not sufficient for all rotating machinery. The stiffness of the fluid film bearing can counter the damping capability. Therefore, an additional means of increasing “effective” damping to the system is needed.
Usually, turbomachines show satisfactory vibration levels during test runs at the manufacturer’s shop. However, vibration levels after the commissioning could be higher than desirable levels. Too often, after several months of operation, vibration could show some increasing trends.
Nozzle repair is something that combustion Turbine Operators Task Force (CTOTF) group members are very familiar with. At this year’s spring conference, CTOTF invited Aaron Frost, Technical Director at Allied Power Group, to go into the details of 7FA Stage 1 nozzle repair. He warned the audience that the new 7FA.04 has lots of cooling holes and is made of GTD-111 material that is essentially unweldable.
The IPP3, said to be the world’s largest internal combustion engine (ICE) power plant, was recently inaugurated at the plant site near Amman, Jordan. The plant is powered by 38 Wärtsilä 50DF multi-fuel engines with a combined capacity of 573 MW.
In the second part of this series, the author highlighted the uses of ASCS and discussed multi-point and mono-point systems. This article focuses on the vibration control unit, speed controller and surge controller unit.
Vibration control unit
Radial bearing vibrations:
In the first part of this series, the author explained the significance of the anti-surge protection system in a compressor. In this article, he compares multi-point systems with mono-point systems and highlights the uses of ASCS.
The parameters affecting the anti-surge control system are discharge pressure, suction pressure, flow rate and suction temperature.
Surge control systems
Vishal Jariwala, Daryll Turner and James Hardin of Elliott Group presented a paper titled, ‘Computational Investigation of Coupling Guard Heating and Mitigation’ at the 43rd Turbomachinery & 30th Pump Users Symposia (Pump & Turbo 2014) that took place from September 23-25, 2014 at Houston, TX. Below are some of the excerpts:
Centrifugal pumps are widely used in industrial applications. Pumps driven by medium-to-low-power motors (70kW), for example, represent almost all of the installed machines deployed in oil & gas process plants.
In our last column, we talked about nitrous oxide as a potent greenhouse gas and how it was often mistakenly associated with power plant emissions. In this column, we will continue with the topic of greenhouse gases (GHGs) but focus on natural gas leakage and unburned hydrocarbons from the U.S. energy infrastructure.
Mitsubishi and Hitachi have traditionally focused on different market sectors. Where Mitsubishi targeted large gas turbines such as the 501G and 501J, Hitachi focused on the small and medium-size market with its H-25 and H-100 (formerly known as H-80) models, often referred to as the H-series.
Screw compressors are categorized as intermittent motion compressors (non-continuous flow). They can also be categorized with medium flow and medium pressure compressors compared with other types of compressors on pressure /flow chart for compressor types.
Turbomachinery International just visited GE Power & Water’s Greenville campus which is dedicated to the development and manufacture of heavy-duty gas turbines. The big news was the result of validation testing on the 9HA.01 gas turbine.
Below are excerpts from a paper titled, ‘Save your centrifugal machinery during commissioning’ presented at the 43rd Turbomachinery & 30th Pump Users Symposia (Pump & Turbo 2014) in Houston, TX from September 23 to 25, 2014.
Below are excerpts from a paper titled, ‘Save your centrifugal machinery during commissioning’ presented at the 43rd Turbomachinery & 30th Pump Users Symposia (Pump & Turbo 2014) in Houston, TX from September 23 to 25, 2014. It was presented by Arun Kumar, Deputy General Manager, Maintenance & Reliability, and Mohit Sabharwal, Assistant General Manager, Maintenance & Reliability, HPCL- Mittal Energy Ltd., India.
Below are excerpts from a paper titled, ‘Babbitted bearing health assessment’ presented at this year’s Middle East Turbomachinery Symposium by John K. Whalen of John Crane, Thomas D Hess Jr of DuPont Engineering Research & Technology Rotating Machinery Group, Jim Allen Nova Chemicals Corporation, Jack Craighton, Schneider Electric.
Below are excerpts from the tutorial, “Shop rotordynamic testing: Options, objectives, benefits and practices” presented by John A Kocur, Jr., of ExxonMobile Research and Engineering and C Hunter Cloud of BRG Machinery Consulting at METS III in Qatar.