Boiler Steam Water Drum Automation using D.C.S

Transcription

1 Boiler Steam Water Drum Automation using D.C.S Karamallh Gafer Aliman Mhammed 1 and Dr. Eltahir Mohamed Hussein 2 1 Control Engineering Department, El-Neelain University, Khartoum, Sudan karamallh123@gmail.com 2 College of Engineering, Sudan University of Science and Technology (SUST), Khartoum, Sudan 2 Faculty of Engineering, El-Neelain University, Khartoum, Sudan altahir_33@yahoo.com Publishing Date: March 08, 2017 Abstract This paper is to control of boiler's water/steam drum in order to product the steam with high quality, has been controlled of level of water/steam drum and kept at 10mm which means that no any quantity of water in the steam. Distributed control system (DCS) has been developed by produce the screens for monitoring and controlling the water/steam drum level by uses optimal control 4000(OC4000), and also through this study to understand how to connect the control software distributor network central control room of the station., and it is through this proposed program can engineer unit in charge of monitoring and controlling effectively in the steam for this station in active way. Keywords: PLCs, OC4000 Program, SCADA, DPU15, (DCS), Power Station (PS). 1. Introduction Automatic control system has played an vital role in the advancement of Science and Engineering. Generally several automation techniques are implemented to control and monitor the industrial plants which include petrochemical plants, oil refining, and thermally electric generation plants[1]. Examples of these techniques include Programmable Logic Controllers (PLCs), Supervisory Control and Data Acquisition (SCADA) and Distributed Control System (DCS). In this project the DCS software is used to make optimal controlling in boiler such as level of water in Power Station (PS). Boiler is a very important equipment in any process industry.the control of a boiler is very complicated because it involves the measurement and control of a number of parameters like drum level, air fuel ratio, steam pressure,steam temperature,oxygen content in flue gas, air flow into the furnace and the firing rate etc. The control was initially done manually for small capacity boiler but, as the capacity of steam increased the process demanded computer based automation to be done which was done by magnetic relays and the controllers were all pneumatic based systems it was then replaced by electrical controller which reduced the size and complexity of the hardware involved[2]. The latest automation techniques like which involved microcomputers made the controls easier but was not redundant all the task was assigned to a single computer. The latest automation technique in the field of process automation is the Distributed Control System is redundant and also is a decentralized control which makes the implementation of complex controls possible. The distributed control system consists of a central computer which is assigned with the main task the work is shared among different systems. The DCS is the most feasible technique for control of complex systems like boiler. There are different types of designs available in boiler based on the specification we have taken a water tube boiler for our analysis.the automation is done using the OC4000 software. The boiler water/steam drum is an integral part of the boiler s design. This vessel has three specific purposes; provide a volume space to hold the boiling water in the boiler, provide enough water volume to allow for good thermal mixing of the cooler bottom drum water with the hotter surface interface water and provide surface area and volume for the efficient release of the entrained steam bubbles from the boiler water. The surface area and volume of the vapor space in the water/steam drum is critical to the efficient separation of the steam bubbles from the water. 122

2 2. Methodology To achieve the objectives of this paper, DCS program is constructed by using optimal control (OC 4000) DCS software that is produced by American company named Generation Electrical (GE). The FBD program designed to control and monitors the water steam drum level. 2.1 Control Philosophy of the System The level transmitters are used to measure the actual drum level. The average of these transmitters output are compensated for the drum pressure this measured level is compared with the set value and the error (single element level error) is applied to the controller The control valve position signal is used as negative feedback for improving the response of the control system. it is effective to use single element control in which the feed water controller is by passed and the drum level controller directly controls the feed water control valve. One valve and pump are used to control the steam drum according to the ultrasonic sensor readings placed in the water drum.the control valve still open until reach the optimal level. Firstly the pump used to supply the water drum with the feed water, in between the control valve used to control the amount of the feed water. The control valve's position is changing according to the transmitter's readings. According to the level transmitter readings: The Halm goes on when the level is (>=30) and the HHalm goes on when the level is (>=50). The Lalm goes on when the level is (<=-70) and the LLalm goes on when the level is (<=-90). Figure 1: Flowchart of the System 123

3 2.2 The Process Configuration 2.4 DPU15 DCS proposed program implemented to control water drum The DPU15 contained four pages to represent the configuration level is divided into two parts first one is include control of the close loop control system, level's set point, the simulation configuration and the second to control human machine of the feedback of the control valve status, the H, HH, L and LL interface (HMI). alarms, the simulation of the actual water level, full and reset command and Control valve alarm for high alarm. 2.3 Control Algorithm 2.5 DPU Configurations The OC4000 program used provides the control algorithm language which especially intensifies the graphical The configurations of DPU means all the logic functions that configuration and the debugging language that base on the must be used until system working properly. This functions are graphic function blocks. The DCS software provides all kinds of working together and constructed by engineer unit based on the common function blocks. The required blocks are selected from system requirements The Figures below shows the DPU the tools of the functional software of the DCS. The logic and configurations: the simulation are constructed DPU15. Figure 2: The close loop control system 124

4 Figure 3: The feedback of the control valve status and alarms Figure 4: The simulation of the actual level 125

5 Figure 5: Full and reset command Figure 6: Control valve alarm for halm 126

6 3. Result and Discussion 3.1 Start System When the system is started in automatic mode the control valve is opened in order to reach the set point at (10mm) as shown in the Figure 7. Figure 7: Starting system to reach set point. 3.2 Low Alarm Signal The Lalm signal goes on to indicate the decreasing of the water level (<=-70) with a control valve response as shown in the Figure 8. Figure 8: Low Alarm 127

7 3.3 Low Low Alarm Signal The LLalm signal goes on to indicate the decreasing of the water level(<=-90) with a control valve response as shown in the Figure 9. Figure 9. Low Low Alarm 3.4 High Alarm Signal The Halm signal goes on to indicate the increasing of the water level(>=30) with a control valve response as shown in the Figure 10. Figure10: High Alarm 128

8 3.5 High High Alarm Signal The HHalm signal goes on to indicate the decreasing of the water level(>=50) with a control valve response as shown in the Figure 11. Figure 11: High High Alarm 3.6 System Trend Figure 12: System Trend 129

9 4. Conclusion International Journal of Engineering, Applied and Management Sciences Paradigms, Vol. 45, Issue 01 This paper uses OC 4000 to maintain the water drum level at the normal line using the control valve position depending on measuring the actual level using ultrasonic sensor, according to the ultrasonic readings and the level set point the water must be pumped to the drum and controlled by the control valve to reach the set level (10mm). A complete modification is made in the DCS system. The results obtained by running the modified program justify the possibility of this project to be added to the main program used in MSPS. References [1] Wenzel, Olivia, et al. "Nanoscale characterization of CSH gel pores with scanning transmission electron microscopy." Young Researchers Forum III 2016 Innovation in Construction Materials [2] Wenzel, Olivia, Matthias Schwotzer, Andreas Gerdes, Torsten Scherer, and Venkata SK Chakravadhanula. "Nanoscale characterization of CSH gel pores with scanning transmission electron microscopy." In Young Researchers Forum III 2016 Innovation in Construction Materials [3] Webster, John G., and Halit Eren, eds. Measurement, instrumentation, and sensors handbook: electromagnetic, optical, radiation, chemical, and biomedical measurement. CRC press, [4] Katte, Nagabhushana, et al. "An Integrated Expert Controller for the Oven Temperature Control System." Sensors & Transducers [5] Katte, Nagabhushana, et al. "An Integrated Expert Controller for the Oven Temperature Control System." Sensors & Transducers [6] GE Energy Company, OC 4000 DCS OPERATION & MAINTEN manual for Khartoum North power station (MSPS) [7] John G. Webster, Lessons In Industrial Instrumentation, Handbook CRC net BASE