Available online at www.sciencedirect.com ScienceDirect Procedia Computer Science 105 (2017 ) 296 303 2016 IEEE International Symposium on Robotics and Intelligent Sensors, IRIS 2016, 17-20 December 2016, Tokyo, Japan Design and Development of Platform Deployment Arm (PDA) For Boiler Header Inspection at Thermal Power Plant by Using the House of Quality (HOQ) Approach Iszmir Nazmi Ismail a, Khairurrijal Ab. Halim a, Khairul Salleh Mohamed Sahari a, *, Adzly Anuar a, Muhammad Fairuz Abdul Jalal a, Fevi Syaifoelida a, M. R. Eqwan a a Centre for Advanced Mechatronics and Robotic, Universiti Tenaga Nasional, Kajang, Selangor, Malaysia Abstract Power plant inspection is a regular activity for repair and maintenance purposes. Boiler headers serve as to tie multiple steam mains to one boiler or multiple boilers to one or more steam mains. The challenge to do inspection inside boiler headers is they come with different configuration of inspection entry. A special Platform Deployment Arm (PDA) is built to latch the inspection robot inside the boiler header. A House of Quality (HOQ) approach is applied the design the PDA in order to construct the relationship between engineering or technical aspects with the customer requirements. Those requirements displayed in the form of matrix before translating it into the final design. All the designs and development selection process of PDA based on HOQ are shown in this study. Several lab tests were done to validate the workability of the PDA. 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license 2016 The Authors. Published by Elsevier B.V. (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review Peer-review under under responsibility responsibility of organizing of organizing committee committee of the of 2016 the 2016 IEEE IEEE International International Symposium Symposium on Robotics on Robotics and Intelligent and Intelligent Sensors(IRIS (IRIS 2016). 2016). Keywords: Platform Deployment Arm (PDA), House of Quality (HOQ), boiler header, robot inspection 1. Introduction Power plant or power station is a heart of electricity generation. Until today various sources of power electric generation comes to selection. A thermal power station or a coal fired thermal power plant is by far, the most conventional method of generating electric power with reasonably high efficiency. It uses coal or other fossil-fuel based as the primary fuel to boil the water available to superheated steam for driving the steam turbine. In a thermal * Corresponding author. Tel.: +60-3-8921-2020; fax: +60-3-8921-2116. E-mail address: khairuls@uniten.edu.my 1877-0509 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of organizing committee of the 2016 IEEE International Symposium on Robotics and Intelligent Sensors(IRIS 2016). doi:10.1016/j.procs.2017.01.225
Iszmir Nazmi Ismail et al. / Procedia Computer Science 105 ( 2017 ) 296 303 297 power plant, where multiple boilers exist, boiler headers function to tie multiple steam mains to one boiler or multiple boilers to one or more steam mains. In conjunction to its thick wall and expose to various operating conditions, it is very important to inspect the boiler headers from time to time to prevent failures due to creep, thermo-mechanical and other malfunctioning issues. A routine inspection needs to be done during power plant maintenance period in order to fulfil the demand of electricity from the customers which increases everyday around the world. Since boiler headers are exposed to a very high temperature and pressure, it is important to ensure that the vessel is tightly sealed. In order to fulfil safety precautions, only a small opening is allowed during the routine maintenance check. This is either achieved by cutting the nipple part of the boiler header or a dedicated handheld nipple which can be from the front, bottom, top or the side of the vessel. Due to the possible big gap between the entry point and the boiler header, the various entry positions, and the length of the boiler header, it is very difficult and tedious for technicians and engineers to inspect the boiler headers manually. This leads to the idea of developing an in-pipe robot for boiler inspection purposes. At the moment, prototypes robots for inspection has been developed in the previous project which are MK-02 [1] and LS-01 [2]. Besides building an inspection robot, a special robot deployment device need to be created in order to dispatch the robot safely and efficient inside the boiler header to do inspection. Several in-pipe inspection robots are reviewed to make as the reference on the conceptual [3]. This technical paper specifically focuses on developing of deployment device to release the robot inside the boiler headers for inspection task. Table 1 shows the working condition of a boiler header during maintenance period at thermal power plant [4]. Table 1. Working condition at thermal power plant during maintenance operation. No Criteria Description 1 Temperature 25 0 C-60 0 C 2 Pressure Atmospheric Pressure 3 Surrounding Gases 20.9% Oxygen, no presence any flammable gases 4 Other Chemical Presences Small percentage of phosphate 5 Inspection Entry Must be from inspection nipple either at top, side and in front of boiler headers 6 Other Precaution Boiler header s inner magnetize layer cannot be damaged during maintenance and inspection work During the inspection period, the boiler header will be at ambient temperature, normal humidity and atmospheric pressure. A possibility presence of water deposits and other chemicals residue such as precipitate phosphate need to be considered. The boiler headers are exposed to very high temperature and pressure, therefore it is important to ensure that the vessel is tightly sealed. Considering of the critical condition, only a small opening is allowed when maintenance work is done. This is either be achieved by cutting the nipple part of the boiler header or a dedicated handheld nipple which can be from the front, bottom, top or the side of the vessel. From the visit at various thermal power plants, it is observed that boiler headers come with different types of configuration. The configuration depends where the boiler header is located for example at high pressure path or low pressure path inside the steam cycle flow. Difference in load generated by the power plant is one of the factor that caused boiler header comes with different type of arrangement. The bigger the load, a bigger size boiler header is needed to occupy the demand of steam required to rotate the turbine to generate more power. The working conditions and boiler headers configurations are the key factors in extracting the information to produce the design requirements and specification. Types of boiler header are summarized in Fig. 1 [5].
298 Iszmir Nazmi Ismail et al. / Procedia Computer Science 105 ( 2017 ) 296 303 Fig 1. Summary of boiler header configuration at selected thermal power plants. 1.1. Design requirement A design requirement was constructed base on the working conditions which the data has been collected during the technical visit to several thermal power plants. An input from the discussions with the power plants personnel is also considered as the customer requirements. Table 2 shows the summary of specific requirement based on the scale of importance from 1 (lowest) to 5 (highest). Table 2. Specific requirement in the development of a platform deployment arm (PDA). No. Criteria Requirement Details Imp. 1. Operating Temperature Ambient temperature 5 Condition (Offline) -inner surface temperature -inner ambient temperature Atmospheric pressure Oxygen Content 20.9% No toxic gas No flammable gas Humidity Normal humidity at atmospheric pressure 5 Chemical Composition The boiler header may consist of water and other chemicals such precipitate 5 phosphate and rust 2. Functional Safety Technical Must be able to go in and come out safely. Components must not detach easily. 5 Entrance and Inside BH Must not stuck at entrance. 5 Must not damage thin magnetize layer at the inner wall of BH 3. Working Space BH Entry ( Nipple/ BH Diameter: 89 mm (smallest) 5 Configuration - Boiler Header (BH) entry Front /Inspection Nozzle) Configuration: Reducer, Perpendicular, Hemispherical Head, Pin Type, Flat, Nipple Entry 90 o perpendicular
Iszmir Nazmi Ismail et al. / Procedia Computer Science 105 ( 2017 ) 296 303 299 Top & side entry BH Geometry Length: 10230 mm (shortest), 22080 mm (longest) 4 BH Orientation: Diameter: 118.3 mm (smallest) 700 mm (largest) Horizontal only and straight BH Material Alloy Steel (P91, P92, P991) 3 Carbon Steel Stainless Steel Low Alloy Steel 4. Mobility Portability Can be carried by one person 2 Easy to be kept/stored Adaptability Can integrate with existing system 1 Mass 2 kg (preferable as light as possible) 1 Based on the data gathered, boiler header configuration can be broadly grouped into 3 categories in Table 3. From the observation during the site visit, the design of PDA will follow to the description of boiler header in Category 3 because most occurrence configurations of boiler headers fall under this category. Table 3. Configurations of boiler headers. Categories Descriptions Category 1 Nipple type configuration: Entry from nipple which is parallel with the boiler header Nipple diameter range (70 mm to 80 mm) BH diameter range (150 mm to 200 mm) Category 2 The entry diameter almost the same as BH diameter Uniform diameter through BH body BH diameter is relatively bigger (250 mm to 600 mm) Category 3 Inspection nozzle entry: 90 o / perpendicular to BH (left or right) with diameter of 89 mm to 100 mm BH diameter size varies (about 100 mm to 700 mm) Happened to have at all power plants. 1.2. Engineering specification From the specific requirements, the engineering specifications of the proposed PDA are extracted and summarized as in Table 4. Importance scale ranges from 1 which is the lowest to 5 the highest. Quality Function Deployment (QFD) method is used to generate engineering specifications of the proposed PDA which it comes from customer s requirement by focusing on the customer s needs [6]. Quality function deployment (QFD) is an efficient and useful approach for constructing new product designs or modifying existing products [7].The purpose of this method is to correlate between customer requirement which shown previously in Table 2 and engineering specification which been tabulated in Table 4. By applying the QFD method, a house of quality (HOQ) is built as shown in Fig. 2 [8]. Table 4. Engineering specifications of the platform deployment arm. No. Engineering Specifications Imp. 1. Temperature 5 2. Toughness of case material 5
300 Iszmir Nazmi Ismail et al. / Procedia Computer Science 105 ( 2017 ) 296 303 3. Weight 5 4. Ability to turn 180 0 (90 0 for a side 5 5. Safety factor 4 6. Width 4 7. Length 4 8. Height 4 9. Strength of material 4 10. Failure rate 4 11. Operational lifetime 4 12. Efficiency 3 Fig. 2. House of quality (HOQ) for platform deployment arm (PDA). PDA attributes are generated from the HOQ. From the score of total marks, it shows the safety factor is the most important feature and follows by the size (width x length x height) in building the final prototype. The priority of the other attributes will be followed according to the scores. The final prototype of PDA will be designed and manufactured by considering all the attributes extracted from the HOQ.
Iszmir Nazmi Ismail et al. / Procedia Computer Science 105 ( 2017 ) 296 303 301 1.3. PDA Mechanism After PDA is manufactured, a test was done to verify the workability of PDA mechanism. PDA is used to hold the robot when entering the boiler header. The robot will be released once it is properly placed at the bottom surface of the boiler header. PDA consists of two major parts, the holding arm and the robot holder or platform. Fig. 3 shows the general configuration of the PDA holding the robot. Fig. 3. Actual PDA with inspection robot. PDA plays its part by deploying the robot for different entry configurations whether the entrance or inspection nozzle is 90 degree (perpendicular) to the boiler headers or the entrance nipple is parallel to the boiler header. PDA is fitted with supporting castor to provide smooth insertion process. Fig. 4 shows the entry position during deployment of the inspection robot. Fig. 4. PDA with inspection robot entry position prior entering boiler. When the robot reaches at the center of the boiler header, the platform on the deployment arm is rotated 90 0 to align the robot with the direction of the boiler header. Before the PDA is turned 90 0, the PDA s platform is locked to securely position the robot at the center of the boiler header pipe. The rotating handle will rotate the PDA s rotating elbow to align the platform parallel to the boiler header direction as shown in Fig 5. Fig. 5. Inspection robot reaches the center of the boiler header and turned 90 0 parallel to boiler header direction. Once the robot is properly aligned, the holding arm is tilted and the robot is will be released. The robot will slowly move away from the robot holder until its wheels are fully in contact with the bottom surface of the boiler header. The inspection robot will then traverse along the boiler header Fig. 6.
302 Iszmir Nazmi Ismail et al. / Procedia Computer Science 105 ( 2017 ) 296 303 2. Result and discussion 2.1. PDA Holding Angle Fig. 6. PDA tilts to form a ramp and release the inspection robot. A lab test was conducted to verify the reliability of the PDA to hold the weight of the robot when releasing it inside the boiler header. Release angle is a very important parameter in order to ensure the robot will be released safely and well deploy at the targeted inspection location. From the test, the PDA can hold the robot up to 50 0 angle of release. This results show the PDA is able to withstand the robot s weight and the rubber track on the platform is adhesive enough to prevent the robot to from falling down. Even though PDA can hold the robot up to 50 0, it is advisable to release the robot during inspection for not exceeding 40 0 due to safety reason. Table 5 shows the ability of PDA to hold the robot at various release angles. Table 5. PDA holding the inspection robot at various release angle.
Iszmir Nazmi Ismail et al. / Procedia Computer Science 105 ( 2017 ) 296 303 303 3. Conclusion Boiler headers at thermal power plant come with several entries of configurations. Most occurrences configuration for the boiler headers are the parallel entry and perpendicular entry. In order to assist the inspection robot enters the boiler header, a portable deployment arm (PDA) is proposed. A list of working conditions need to be consider before executing the design process. Specific requirement and engineering specifications are extracted after considering all the working conditions. House of Quality (HOQ) method is introduced to quantify the relationship between specific requirement and engineering specification in order to produce the final design. Lab test was conducted to verify the capability and the performance of the PDA. The PDA can be further improve by designing different module for releasing the inspection robot in objective to cater all type of boiler headers configurations. Acknowledgements The authors would like to sincerely thank the Tenaga Nasional Berhad (TNB) and TNB Research, Malaysia for the provision of a Design and Development of Boiler Header Inspection Robot Grant to support this work as well as access to TNB power plant and TNB lab facilities. References 1. A. Anuar, N.S. Roslin, K.S. Mohamed Sahari and M.A. Aziz, "Inspection Robot for Parallel Entry Boiler Header Pipe." In Soft Computing in Advanced Robotics, Springer International Publishing, 2014, pp. 105-114. 2. M.Z. Baharuddin, J. Md Saad, A. Anuar, I.N. Ismail, N.M. Hassan Basri, N.S.Roslin, S.S. Kaja Mohideen, M.F. Abdul Jalal and K.S. Mohamed Sahari, Robot for Boiler Header Inspection LS-01, Procedia Engineering, vol. 41, 2012, pp. 1483-1489. 3. Ismail, I.N., Anuar, A., Sahari, K.S.M., Baharuddin, M.Z., Fairuz, M., Saad, J., et al.: Development of in-pipe inspection robot: a review. In: IEEE Conference on Sustainable Utilization and Development in Engineering and Technology (STUDENT), pp. 310 315. IEEE (2012) 4. Ismail, I.N., Anuar, A., Baharuddin, M.Z., S.S. Kaja Mohideen, Fairuz, M., Saad, J., et al.: Boiler Header Data Book, Mobile Robotic Group Universiti Tenaga Nasional. 2010. 5. Sahari, K.S.M., Baharuddin, M.Z., Fairuz, M., Saad, J. Ismail, I.N., Anuar, A., S.S. Kaja Mohideen et al.: TNBR Design & Development of Boiler Header Inspection Robot Prototype Final Report. 2011. 6. Mohammad Molani Aghdam; Iraj Mahdavi; Babak shirazi; Javad Vahidi, House of quality improvement by new design requirements generation., Proceedings of the 2015 International Conference on Industrial Engineering and Operations Management Dubai, United Arab Emirates (UAE), 2015, pp.1-9 7. Liang-Hsuan Chen; Wen-Chang Ko; Chien-Yao Tseng, Fuzzy Approaches for Constructing House of Quality in QFD and Its Applications: A Group Decision-Making Method., IEEE Transactions on Engineering Management, Volume: 60, Issue: 1, pp. 77 87. 2013 8. D.G. Ulman, The Mechanical Design Process, Third Edition, McGraw-Hill, 2004