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.
Durban branch
SAIMC
At the Durban branch of the SAIMC held in October, Mitch Naidoo took the attendees on an interesting journey on Asset Health Management: Tracking The Pulse Of Your Plant.
Read more...SAIMC: Durban branch SAIMC
SAIMC
At the Durban branch of the SAIMC held in October, Mitch Naidoo took the attendees on an interesting journey on Asset Health Management: Tracking The Pulse Of Your Plant.
Read more...SAIMC: Johannesburg branch SAIMC
SAIMC
The SAIMC Johannesburg Branch technical evening was hosted by Proconics Advanced Solutions. The topic of the session was ‘Turning Big 3D Data into Actionable Engineering Insights – Challenges and Smart Solutions’.
Read more...SAIMC User Advisory Council Annual Summit 2025 SAIMC
SAIMC
October 2025 marked a pivotal moment for the South African automation and manufacturing community as the SAIMC User Advisory Council hosted its first annual summit under the SAIMC banner.
Read more...SAIMC: Johannesburg
SAIMC
The Johannesburg Branch of the SAIMC hosted a successful Technology Evening on 10 September. The event was well attended and generously sponsored by Phoenix Contact.
Read more...SAIMC: Durban branch SAIMC
SAIMC
At SAIMC Durban’s October Technology Evening, Nico Erasmus delivered a thought-provoking presentation on a topic close to every automation professional’s heart: PLC and Drive Manufacturer Generational Hardware - UpGrades, UpGates or UpRates?
Read more...SAIMC: Johannesburg branch SAIMC
SAIMC
The Johannesburg Branch of the SAIMC hosted a successful Technology Evening on 10 September. The event was well attended and generously sponsored by Phoenix Contact.
Read more...Why ECSA matters SAIMC
SAIMC
I always knew I had to register as a Professional Engineer. Then I opened the registration guidelines.
While every effort has been made to ensure the accuracy of the information contained herein, the publisher and its agents cannot be held responsible for any errors contained, or any loss incurred as a result. Articles published do not necessarily reflect the views of the publishers. The editor reserves the right to alter or cut copy. Articles submitted are deemed to have been cleared for publication. Advertisements and company contact details are published as provided by the advertiser. Technews Publishing (Pty) Ltd cannot be held responsible for the accuracy or veracity of supplied material.
printer friendly version