Unit 45 Industrial Systems - Pearson Higher Nationals in Engineering
Learning Outcome 1: Identify and specify the interface requirements between electronic, electrical and mechanical transducers and controllers
Learning Outcome 2: Identify and specify the interface requirements between electronic, electrical and mechanical transducers and controllers
Assignment Brief
Scenario
You have been assigned to a project team which has been charged with the duty of installing a Steam Turbine Generator for a Power Plant which will be placed in a Rural Community. The Community has access to natural gas and a large volume of water from a nearby reservoir. A steam turbine generator was selected because of its reliability and its ability to run continuously with minimum out of service maintenance. The Power Plant will be constructed in a valley which is 200 metres below the lake. Figure1 is a general design of the power station. The water supply for the power station is illustrated in figure2. The water is obtained from the reservoir by a duct which is used to fill two large storage tanks located on a plateau approximately 100 metres above the power station. At any point in time only one storage tank is used to supply the water needed by the power station. The water supplied is used primarily as an input to the power plant condenser and water treatment plant which then supplies the treated water to the power plant boiler.
TASK
a) You have been asked to look at various means of controlling the temperature of a boiler that you are asked in addition to recommend a control system for, in Figure 2. The methods of controlling the boiler temperature have been listed as follows:
i) Electrical
ii) Electronic
iii) Mechanical
Critically investigate the behaviour of the control system for the boiler using each of the above mentioned methods giving the advantages and disadvantages of each method and then making a recommendation as to the preferred method to be used in controlling the temperature of the boiler in the power generation system. Before this is done, you will need to complete the solutions for the following:
b) You are required to recommend transducers for the control system of the Boiler in Figure 2. The boiler temperature can vary from 100oC to 600oC . The boiler temperature would be controlled by a flow valve which would control the flow of the fuel (natural gas) to the burners in the boiler. The following are the list of transducers which you have been asked to consider for use in measuring the temperature of the steam from the boiler:
i) RTD
ii)Thermistor
iii) Thermocouple
These transducers would be interfaced to a digital system which would be used to display the boiler temperature as well as to send the temperature data to the boiler controller.
1) Response time
2) Sensitivity (change in measured characteristic per degree temperature rise)
3) Linearity
4) Accuracy
5) The need for signal conditioning equipment.
Looking at the above with consideration of their characteristics and others that may be applicable. Predict the impact that using each of these transducers may have on the operation of the control system for the boiler and select the best solution.
You are also required to design a system which ensures that both water tanks used by the power station are always full despite the load requirements of the treatment plant and the condenser. You are required to compare the performance of a mechanical, electrical, and electronic controller for this system and the interface requirements between the relevant transducers and their respective controllers. The outlets of each tank will be controlled by a valve which can be remotely opened or closed electronically by an operator in the Control Room of the Power Station. The flow of water from the reservoir is normally greater than the flow of water required by the power station.
Having compared the performance of the mechanical, electrical, and electronic transducers and controllers for the system above. Choose a controller and transducer for the above system and justify your choice.