IMPROVING PERFORMANCE OF FLY ASH PUMP IN COAL BOILERS

Fly ash is a system of dry ash handling system burning coal by boiler before getting to the chimney so as not to pollute the environment (air). Abu will pass the E lecture Static Recipient (ESP) and be temporarily accommodated at hopper. Then the ash will be transferred through the pneumatic AV pump system to fly ash silo. Fly ash transfer system failure occurred due to disruption of the pneumatic control system pump pa da AV system. This is because of the dome valve insert seal on AV pump leak and control system pneumatic fault because of contaminated by fly ash dust. The working intensity of the AV pump system in operation creates friction between the dome valve and dome valve insert seal which can cause erosion and leak on the dome valve insert seal. Frequent leakage at dome valve insert seal, has an impact on the spare part control system pneumatic contaminated by fly ash dust which causes damage to pneumatic spare parts and the cessation of the transfer process of ash to fly ash silos. The research was conducted with the addition of protection to the system pneumatic control AV pump by installing a quick exhaust valve on the system pneumatic AV pump in fly ash system, so that dust does not enter the AV pump's pneumatic control system when a dome valve insert seal leaks.


Introduction
Fly ash system is a system for handling dry ash from burning coal by the boiler before reaching the chimney so that it does not pollute the air. Ash will pass through the electrostatic precipitator (ESP) and be accommodated IJEAT © 2019 www.Inter-Journal.nusaputra.ac.id/IJEAT 2 temporarily in the hopper which will then be transferred through the AV pump line transfer system to the ash storage silo.
The operation of the fly ash transfer is noted several times with disruption to the AV pump transfer system in Units 1-3. This interference is in the form of a leak on the dome valve insert seal which causes the pneumatic control system to fault and impacts the transfer of fly ash dust to a standstill. This will interfere with the performance of the fly ash system. The problem of dome valve insert seal leakage on the AV pump is found in many parts of pneumatic systems contaminated with fly ash dust. When AV pump transfers experience problems, the action taken is to clean and replace the pneumatic control system parts.
To overcome the above problems, it is important to design a protection system on the pneumatic AV pump so that the dry ash from combustion does not enter into pneumatic spare parts so that the fly ash transfer system can be more reliable.
The insert seal dome valve leak on the AV pump Unit 3 caused disruption of the pneumatic control system and the cessation of the fly ash transfer process.
Damage graph of the AV pump pneumatic system based on Work Order made by the Operator regarding the condition of the AV pump is not normal, either from the leak seal insert dome valve problem or from the fault indication on the AV pump can be seen in Figure 1.     Figure 3. AV pump Transfer System

METHODOLOGY
The methodology used in preparing this innovative work is: 1. Make direct observations of problems that occur in the field.
2. Gather information and references regarding the working principles of the system.
3. Conduct analysis to determine the right innovation.
4. Implement innovation in the system.

AV Pump Pneumatic Control System
Pneumatic control system is a drive that uses air pressure as its driving force. In the world of generators, the use of pneumatic control systems is widely used. One of them is the operation of the AV pump transfer system. AV pump transfers an auto-operated system with a pneumatic control system combined with electricity such as a PLC facilitating its application.

Factors determined for the reliability of pneumatic control systems
To be able to guarantee the reliability of pneumatic control systems, pressurized air of sufficient quality must be provided. These factors are determined as follows:  IJEAT © 2019 www.Inter-Journal.nusaputra.ac.id/IJEAT 6

Parts of the AV pump pneumatic system
In operation , the AV pump pneumatic system has several spare parts. The pneumatic spare parts consist of: 1. Manual Valve. Manual valve is a device that regulates, directs or controls the flow of a liquid by opening, closing, or closing part of the flow path.
2. Filter Lubricator. Filter Lubricator in the AV pump is used to filter air (wind) so that the air entering the spare parts is not contaminated with foreign particles that can damage other spare parts. And gives lubrication to moving pneumatic parts such as pistons and solenoids.

Solenoid Directional Valve. Solenoid directional valve is a valve that is controlled by electric current both AC and DC through coils / selenoids.
This solenoid valve is a control element that is most often used in fluid systems.
4. Actuator Cylinder. Cylinder actuators are actuators or mechanical devices that use pressurized air power to produce power in alternating movements of the actuator cylinder in a linear manner, in operation, a pneumatic actuator is controlled by a solenoid directional valve.

Quick Exhaust Valve. The Quick Exhaust Valve function that is installed
here is to accelerate the discharge of pressurized air inside the piston, so that the Actuator Cylinder will move open close quickly.
6. Directional Limit Switch. Directional limit switches are included in the category of mechanical sensors, namely sensors that will provide electrical changes when there is a mechanical change in the sensor. The limit switch will connect when the valve is pressed at a certain pressure limit. it into the text after your paper is styled.

Root Couse Failure Analysis (RCFA) AV Pump Pneumatic Control System
The cessation of the fly ash transfer process is a frequent disruption to the AV pump line transfer (Bonnett, 2000). This was caused by a broken dome valve insert seal which disrupted the pneumatic control system on the AV pump.

Figure 5. Dome Valve Construction
In the process, the insert seal dome functions to close the gap during the dome valve so that no leak occurs during the transfer process of ash. The insert seal dome valve also maintains pressure when transferring fly ash to the Fly Ash Silo.
The insert seal dome valve itself often experiences damage such as tearing or melting, causing disruption to the AV pump transfer system. This is due to the IJEAT © 2019 www.Inter-Journal.nusaputra.ac.id/IJEAT 8 inclusion of fly ash dust into the pneumatic control system and has an impact on the cessation of the transfer process of ash to fly ash silo.

Addition of Protection to the AV Pump Pneumatic Control System
The addition of quick exhaust valve protection with a fluorocarbon diaphragm material on the AV pump's pneumatic system. So that the AV pump

Implementation of design results
The implementation of the AV pump system with the addition of Quick Exhaust Valve has been carried out on January 24, 2017, precisely at AV pump Unit 3, Palabuhan Ratu PLTU and proven to reduce interference due to leakage on the seal seal dome valve. on the AV pump pneumatic control system. The following work order graph regarding AV pump in 2017 can be seen in Figure 10. 1. Solenoid directional valve; 2. Directional limit switch Figure 11. Condition of pneumatic control system spare parts after quick exhaust valve installation

Conclusion
The mechanism for improving the AV pump's performance for fly ash systems has been implemented and monitored for performance. The results show that there is an increase in the performance of the AV pump in handling ash from burning coal boilers. This is expected to increase the performance of the AV pump on the boiler.