Steam turbine control was the subject of the last technology evening presented by Moore Process Controls.
A steam turbine is a device that extracts thermal energy from pressurised steam and uses it to do mechanical work on a rotating output shaft. The modern manifestation was invented by Sir Charles Parsons back in 1884.
There are two main types: impulse and reaction turbines. The main difference is the manner in which the steam is expanded through the turbine. Modern steam turbines frequently employ both reaction and impulse in the same unit, typically varying the degree of reaction and impulse to improve the efficiency.
For any steam turbine to operate there must be a pressure difference between the steam supply and exhaust. There are different classifications of turbines depending on their purpose and working pressures. The different classes are:
• Condensing steam turbine.
• Back-pressure steam turbine.
• Reheat steam turbine.
• Extraction turbine (steam extraction).
Turbine control is important to prevent catastrophic failures. The typical IO control inputs used for turbines are speed and steam valve output. The following IO are optional to improve the controls of the speed of the turbine: steam valve feedback; upstream steam pressure and temperature; downstream steam pressure and temperature; steam flow; and turbine casing temperature.
Up to three speed measurements can be used for speed control and will most commonly be implemented as follows:
• When three inputs are available – use the average.
• When two inputs are available – use highest of the two.
• When one input is available – use that measurement.
• When zero inputs are available – stop the turbine.
It is important to start and stop a turbine in auto to ensure that each start-up or shutdown is identical for the same process conditions. A turbine typically has three start-up sequences: hot, warm and cold. A turbine typically has two shutdown sequences: normal and fast stop. Data for these sequences is typically provided by the OEM.
The presentation also included a demonstration of steam turbine speed control.
SAIMC: From the office of the CEO June 2021, SAIMC
It was interesting to see the comments around Cuban engineers being imported to do engineering work in South Africa. This brings me to the Identification of Engineering Work and Professional Registration ...
Read more...SAIMC: Zambia branch June 2021, SAIMC
SAIMC Zambia held customer training sessions via Zoom with VEGA Controls of South Africa, presented by Chris Van den Heever. The sessions tackled were as follows: 1. Radar basics on Vegapuls 64: applications ...
Read more...SAIMC: Durban branch June 2021, SAIMC
‘IIoT Ecosystem – from sensors to digital services’ was the topic of the May technology evening. Held via zoom and open to all branches throughout the country, it attracted record attendance from an attentive ...
Read more...SAIMC: Cape Town branch June 2021, SAIMC
n integrated geared unit that combines the recently launched Nord IE5+ synchronous motor and a single-stage helical gear unit offers optimum system efficiency.
Read more...SAIMC: From the office of the CEO May 2021, SAIMC
In my last letter, I discussed the lack of skills available to operate and maintain our infrastructure. This month, I present a more specific look at the critical skills required in manufacturing, which ...
Read more...SAIMC: Durban branch May 2021, SAIMC
The branch held its April (virtual) technology evening on 7 April where SAIMC CEO, Johan Maartens, discussed the new skills trust fund initiative: how it works, how we will all benefit from it and how ...
Read more...SAIMC: Cape Town branch April 2021, SAIMC
We had an interesting presentation last month given by Allan Pead from Microsoft on the open source platform from Microsoft Azure Sphere – a secure IoT platform.
Allan is currently an Xamarin ...
Read more...SAIMC: Johannesburg branch April 2021, SAIMC
The technology evening was once again hosted virtually and this time it was the turn of Albert Louw from ifm electronic, presenting on the topic: Systems for mobile machinery.
One could ask the question, ...
Read more...SAIMC: Durban branch April 2021, SAIMC
Members and visitors were treated to a Zoom presentation that had the understated title: Introduction to ultrasonic flow measurement, by Marco Lopes of NIC KZN. Marco was ably backed up by Howard Lister, ...
Read more...SAIMC: Durban branch March 2021, SAIMC
The branch held its first virtual technology meeting of the year on 10 February, where John de Castro (a long-time friend of the Durban SAIMC) gave us some insight into his experiences working abroad. ...