Analysis of Boiler Start-Up Failure Risk with Grey FMEA and RCA Methods in Pt. PLTU Nagan Raya
Teuku Al Kautsar a, 1,*, Arie Saputra b,2
a,bTeuku Umar University, Alue Peunyareng streets, Ujong Tanoh Darat, 23681, Indonesia
1 [email protected]*; 2 [email protected]
I. Introduction
PT. PLN Nagan Raya is a Steam Power Plant (PLTU) in the Sumatra region. The process of generating electrical energy at the Nagan Raya power plant is using coal, where coal is used as Boiler fuel to produce thermal energy [1] . In PLTU, Boilers play an important role because they function to convert water (feed water) into advanced hot steam (superheated steam) In simple terms, the steam produced by the Boiler can rotate the turbine engine to drive a generator that can convert mechanical energy into electrical energy [2]. units operating daily must have at some time been faulty or damage to the system causing the unit to be inoperative [3].
Boiler Start up System is the initial part of 3 Boiler Operation activities, namely Start up, Process and Shuttingdown. In order for the functions of the machine to work optimally, it is necessary to carry out maintenance to protect, prevent, or eliminate degradation during operation.
In the process of electricity production at PT. PLTU Nagan Raya Obtained a failure that occurred during the Boiler start-up process due to damage to Boiler components so that Boiler start-up operations could not run. Based on WO (Work Order) Rendal HAR data, it is known that many Boiler components experience problems in the operation of Boiler start-ups in 2021 in unit 1 so that
ARTICLE INFO A B S T R A C T
Article history:
Accepted
PT. PLN (Persero) UPK Nagan Raya is a Steam Power Plant (PLTU) that uses coal as Boiler fuel to produce thermal energy. one of the initial stages of the Boiler is Start up as the basis for the start of Boiler operations. The purpose of this study is to analyze and avoid the risks that can make the operating system not run. Based on the research conducted, there are 8 risks that can cause failure. Based on the Grey FMEA method, the priority risk that occurs is that the FO fast shut off cannot be O / C CCR with a value of 0.491 and also in the flexible joint line of the lower burner air there is a leak of 0.503.
The result of the Root Cause Analysis method, the cause of the FO fast shut off cannot be O / C CCR is the limited facilities and infrastructure for device maintenance which causes obstacles for workers so that the results worked on are not effective and efficient.
Meanwhile, the risk that the flexible joint line air lower burner has a leak because it is not a critical equipment only used at certain times so that the check is neglected which makes the flexible joint leak.
The solution that can be done is that as much as possible the operator must carry out routine maintenance / overhaul on the flexible joint so that there is no failure that can hinder the operation.
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Keywords:
Risk analysis Boiler start up Grey FMEA RCA PLTU
research is carried out focusing on Boiler unit 1. There are several problems that can be found in the Boiler engine at start-up including flexible joint line air lower burner there is a leak, lower burner 3 high temperature and Flue gas system ID fan A leakage flexible joint at line outlet. In a previous study by kholil (2013) identified the risk of failure in Boiler start-up at the Krakatau power plant with Enterprise Risk Management, it is known that one of the components that most often occurs disturbances is the pult control which is the control table of the Boiler operator [4].
Based on the above concerns, it is necessary to identify the risk of Boiler start-up failure and look for the causes and effects of these risks, with the aim of avoiding and analyzing the risks that can make the operating system not running, so that the author is motivated to identify risks in Boiler start-up failure using the Gray Failure Mode and Effect Analysis (FMEA) method and also to find the root of the problem using the Root method using the Root method Cause Analysis (RCA).
Grey FMEA is a method for identifying failures or risks that occur in a system (Isaac, 2014) [5]. In the research conducted by (Rizki, 2022) using the Grey FMEA method to analyze the risk of Supply Chain Management at PT Pertamina Fuel Terminal Meulaboh [6]. The process of finding out the root of the problem and how the solution to the failure can be done with the Root Cause Analysis (RCA) method type 5 why tools have been carried out by (Syaeful Haq, 2020) and (Widodo, 2019). In the study (Syaeful Haq, 2020) used the RCA method to analyze the root cause of Dorr Packing damage to sterilizer tubes in the Kupang River mill [7]. and (Widodo, 2019) using the RCA method to analyze electrical power transmission disturbances in PT. PLN APP Purwokerto Substation 150 kV Pekalongan [8]. Meanwhile, the author uses the RCA method to analyze the root cause of failure in the Boiler start-up.
Therefore, this article aims to determine the factors that cause failures related to Boiler engine start-up with the Gray Failure Mode and Effect Analysis and Root Cause Analysis methods.
II. Method
Conducted this research at PT. PLTU Nagan Raya, The object of this study focuses on damage to Boiler components at start-up, data on Boiler component problems are obtained from the results of observations and interviews with workers who are experienced in the Boiler field. The following is a research flow chart that can be seen in Figure 1.
Figure 1. Research FlowChart Source: Stages of research (2022)
FMEA Grey Method Data Analysis
Grey FMEA is a method combined from the FMEA method and Grey theory, FMEA is a method established as an engineering technique to eliminate known failures by considering factors of severity, occurrence and detection [9], while Grey theory is used to solve problems related to decision characteristics in the form of incomplete information [10]. So Grey FMEA is the process of identifying failures of a component that can lead to malfunctions of the system [11]. Here are the steps to work on the FMEA gray method:
1) Establish a comparison series by filling in the severity, occurrence, and detection values of each of the following failures.
X=
2) Setting a standard series with the smallest value set that has been set is as follows:
X0 = [ X0 (1) X0 (2) X0 (3) ]
Start
Preliminary Research
Field Study PT. PLTU Nagan Raya
Formulation of the problem
Determination of Research Objectives
Data collection
Data processing
Method Failure Mode and Effect Analysis
Method Root Cause Analysis
Analysis and Discussion
Conclusions and recommendations
Done
3) Looking for the difference between the standard series and the comparison series, at this stage a reduction in the value of the comparison series with the standard series is carried out as follows:
Where Δ0j (k) = || X0 (k) - Xj (k) ||
4) Calculating the relational coefficient of grey through:
1. looking for the highest and smallest values of the equation (3).Δmin and Δmax 2. ζ for identification that can affect the relative value of a risk and does not have
to change its priorities. The value of the ζ used is 0.5. Here is the equation in calculating the relational coefficient of gray:
Where, j = 1,…..,m k = 1,….,n
5) Determining the degree of relationship, through the following equation:
Г(Xi, Xj) = ( (𝑘), xj (𝑘)) Г0i(k) =
6) Prioritizing the priority risk level based on the risk order of the gray relationship degree value with the smallest value as a priority for improvement.
Root Cause Analysis (RCA) Data Method Analysis
Root Cause Analysis (RCA) is a process to identify and determine the root cause of the problem as the purpose of building and implementing solutions to prevent the recurrence of the problem [12]. This method is carried out in order to avoid undesired outcomes [13]. One way to find out the root cause of a problem is to conduct an interview using the 5 Whys, namely the repetition of up to five times the question why (why) to understand the root cause of a problem [14]. Identifying the main factors causing Boiler start-up failure using the Root Cause Analysis method can obtain precise and systematic results [15].
III. Results and Discussion
3.1. Identification of Boiler Start up failure risks
Risk identification data is obtained from the results of seeing and checking the field and interviews in the Rendal HAR section in the Boiler field, so the risk of failure of the Boiler start-up is obtained which can stop the company's operations. the following is a recapitulation of the risk data that exists in Boiler start-up failure.
Table 1. Risks on Boiler Start up failure
No Failure/Risk
1 flexible joint line air lower burner has a leak 2 lower burner 3 high temperature
3 Flue gas system ID fan A leakage of flexible joint at line outlet 4 no.1 lower igniting burner mix air mcv can't O/C from CCR/local 5 lower burner switch panel cannot be remote/local
6 lower igniting return oil valve cannot O/C CCR 7 FO shut off can't O/C CCR
8 no.3 lower igniting mix air MCV can't O/C from CCR/Local Source : Identification data (2022)
3.2. Risk Priority Calculation
The risk calculation begins with determining the smallest value of grey FMEA as a priority to find the root of the problem. Therefore, the severity, occurence, and detection values are needed to determine the severity. The value data was obtained from a consultation with Rendal HAR in the Boiler sector. The following are the results of the recapitulation of values from severity, occurance, and detection.
Table 2. Results of recapitulation of severity, occurrence, and detection values
No Failure/Risk S O D
1 flexible joint line air lower burner has a leak 9 10 1
2 lower burner 3 high temperature 9 9 1
3 Flue gas system ID fan A leakage of flexible joint at line outlet 8 8 1 4 no.1 lower igniting burner mix air mcv can't O/C from CCR/local 6 5 4 5 lower burner switch panel cannot be remote/local 5 4 3 6 lower igniting return oil valve cannot O/C CCR 5 5 3
7 FO shut off can't O/C CCR 6 5 6
8 no.3 lower igniting mix air MCV can't O/C from CCR/Local 6 5 5 Source : Identification data (2022)
After finding the severity, occurrence, and detection values, the next RPN (Risk Priority Number) calculation is carried out with the Grey FMEA method to sort from the smallest RPN value to the largest. Here are the steps to work on it:
• Building a comparison series
for this work is included the results of the values of severity, occurrence, and detection on each of the risks that occur.
Risiko =
• Setting a standardized series
standards that are done by setting the smallest values of severity, occurrence, and detection, namely with a value of 1.
• Determining the difference between a standard series and a comparison series
For this work is carried out through the reduction of the value of the comparison series with the balanced standard series through the equation (3). Then the result obtained is:
(S1) = (O1) = (D1) =
(S2) = (O2) = (D2) =
(S3) = (O3) = (D3) =
(S4) = (O4) = (D4) =
(S5) = (O5) = (D5) =
(S6) = (O6) = (D6) =
(S7) = (O7) = (D7) =
(S8) = (O8) = (D8) =
• Estimating the relational coefficient of Grey and the degree of relationship of Gray
The relational coefficient of grey is obtained from equation (4), as first looking for the smallest and highest values of the third step above, then get:
∆0i min = 0
∆0i max = 9
so that the result of the recapitulation of the value of the relational coefficient of gray obtained is:
(S1) = 0,36 (O1) = 0,333 (D1) = 0,818
(S2) = 0,36 (O2) = 0,36 (D2) = 1
(S3) = 0,391 (O3) = 0,391 (D3) = 1
(S4) = 0,473 (O4) = 0,529 (D4) = 0,6
(S5) = 0,529 (O5) = 0,6 (D5) = 0,692
(S6) = 0,529 (O6) = 0,529 (D6) = 0,692
(S7) = 0,473 (O7) = 0,529 (D7) = 0,473
(S8) = 0,473 (O8) = 0,529 (D8) = 0,529
• Calculating the Degree of Grey Relationship
regarding this step is done by estimating the result of the degree of the gray relationship based on equation (5), which is obtained the following results:
= 0,503 = 0,534 = 0,491
= 0,573 = 0,607 = 0,510
= 0,594 = 0,583
After obtaining the results of the grey relationship, the last action taken is to line up the degree of the relationship from the smallest to the largest. Here is the result of the smallest to largest order of degrees of grey relationship in Table 3.
Table 3. The result of the ranking of the degree of gray relationship
No Failure/Risk
1 flexible joint line air lower burner has a leak 0,503
2 lower burner 3 high temperature 0,573
3 Flue gas system ID fan A leakage of flexible joint at line outlet 0,594 4 no.1 lower igniting burner mix air mcv can't O/C from CCR/local 0,534 5 lower burner switch panel cannot be remote/local 0,607 6 lower igniting return oil valve cannot O/C CCR 0,583
7 FO shut off can't O/C CCR 0,491
8 no.3 lower igniting mix air MCV can't O/C from CCR/Local 0,510 Source : Gray FMEA method processing results (2022)
Based on Table 3, it is known that there are 2 risks as the smallest gray is that the FO fast shut off cannot O/C CCR and the second smallest is the flexible joint line air lower burner there is a leak. The risks recorded must be searched to find the root of the problem so that improvements can be made.
Root Cause Analysis with Root Cause Analysis Method
After finding the priority of the problem in the Boiler start-up that has the smallest gray relationship, then look for the root cause of the problem through a root cause analysis type 5 whys as follows:
FO fast shut off cannot O/C CCR
FO fast shut off cannot O/C CCR is one of the components that must be prioritized at the risk of Boiler start up. Here are the results of the analysis of RCA 5 why against the risk of FO fast shut off cannot O/C CCR:
Table 4. RCA analysis 5 Why FO fast shut off cannot O/C CCR
Failure Why 1 Why 2 Why 3 Why 4 Why 5
FO fast shut off can't O/C
CCR
Current voltage power
error
The occurrence of damage to
the solenoid head
Solenoid head device not
working properly
Lack of routine maintenance on
the device
Limited equipment maintenance facilities and infrastructure Source : Root cause search results (2022)
Based on the results of the RCA 5 analysis, the risk of FO (Flue oil) fast shut off cannot be O/C (Open Close) CCR (Central Control Room) due to limited device maintenance facilities and infrastructure. Limited equipment maintenance facilities and infrastructure can cause obstacles for workers so that the results worked on are not effective and efficient. This results in a lack of routine maintenance on devices, such as solenoids, pneumatic valves, command cables, pressure gauges and other devices so that they do not function properly. In order not to occur failures, therefore, a maintenance strategy is needed to determine the sequence of actions that must be carried out related to the state of operation of the manufacturing system as its object.
flexible joint line air lower burner there is a leak
The results of the grey FMEA show that the risk support of the lower burner air joint line has a leakage occupying the second lowest risk, as noted risks that deserve to be prioritized so that in the future it is taken care of and a root cause analysis is needed. And to analyze the RCA 5 why is as follows:
Table 5. RCA analysis 5 Why flexible joint line air lower burner has leakage
Failure Why 1 Why 2 Why 3 Why 4 Why 5
flexible joint line air lower burner has a
leak
Technical error in flexible joint
tool
Implementati on is not in accordance with SOP
Lack of stock of goods
Haven't entered the scope of detail maintenance/o
verhaul
Not a critical equipment
Source : The result of the search for the root of the problem (2022)
Based on the results of the 5 whys risk analysis on the risk of flexible joint line air lower burner there is a leak, it is known that there is a root problem that occurs, namely flexible joint is not critical equipment. basically critical equipment for equipment that is often used / used during operation while flexible joints that are not critical equipment are only used at certain times so that checks are neglected which makes flexible joints leak. In this case, as much as possible, the operator must carry out routine maintenance / overhaul on the flexible joint so that there is no failure that can hinder the operation.
IV. Conclusion
The risk effect that hinders operation based on the degree of gray relationship on the Boiler unit 1 component during the start-up process which as it goes on in 2021 is that the FO fast shut off
cannot be O/C CCR with a value of 0.491 and the flexible joint line air lower burner there is a leak with a value of 0.503. The analysis that occurs at the risk of FO fast shut off cannot be O / C CCR, namely the limited facilities and infrastructure for device maintenance that causes obstacles for workers so that the results worked on are not effective and efficient. Mitigation that can be done by the company is the need for a maintenance strategy to determine the sequence of actions that must be carried out related to the state of operation of the manufacturing system as its object.
The next root of the problem is that the flexible joint which is not a critical equipment is only used at certain times so that the check is neglected which makes the flexible joint leak. So the proposal is to reduce the risk as much as possible for the operator to carry out routine maintenance / overhaul on the flexible joint so that there is no failure that can hinder the operation.
Acknowledgment
The author expresses his deepest gratitude to PT. PLTU Nagan Raya and article supervisors who have helped take the time to provide insight and energy in completing this research.
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