Lessons Learned, Best Practices and Observations Plant Winterization Visits

Transcription

1 Lessons Learned, Best Practices and Observations Plant Winterization Visits

2 EQUIPMENT PROTECTION: Although some of the observations and practices were unique to an entity, the following can be generally applied: Installation of additional freeze protection. Erecting wind barriers. Fabricating new enclosures or modifying existing ones. Utilizing double insulation. Replacing damaged equipment with a more reliable design. Adding kerosene to fuel oil system to minimize gelling. Treating coal and/or limestone systems with anti-freezing solutions. 2

3 Utilizing the system/equipment Resistance Temperature Detectors (RTDs) as ambient temperature indicators to confirm operation of area heaters during periods of unit shutdown. Ensuring that end-of-line heat trace indicators are installed on all plant piping susceptible to freezing conditions. Upgrading the original 3-watt heat trace design with a more effective 5-watt system. Remote monitoring and alarming of all transmitter enclosures exists from a Distributed Control System (DCS) display in the plant control room. Remote monitoring of heat trace circuit amperage from a dedicated display in the plant control room. 3

4 IMPROVING OPERATIONS: Although some of the observations and practices were unique to an entity, the following can be generally applied: Conducting meetings with staff to discuss lessons learned. Completing pre-winterization walk-downs of entire facility. Increasing frequency of operator rounds. Reviewing troubleshooting instructions between electricians and plant operators for heat trace panels/systems. Assigning a dedicated individual to monitor critical areas. Assigning contractors to observe and maintain portable heaters. 4

5 Commencing winter preparations in late summer/early fall to ensure sufficient time to address any deficiencies. Conducting additional winter pre-job briefs prior to beginning outside work to ensure personnel safety. Use of an Operator Actions Matrix to indicate and describe the necessary actions based on different ambient air temperatures. Use of plant staff for installing heat tracing who are more readily available and better understand the impact to plant operations instead of contractors. Use of a Heat Trace Equipment simulator for training personnel on proper installation and troubleshooting techniques. 5

6 Although the winterization program has provisions for twoman operation based on ambient temperature, in order to ensure personnel safety, a corporate work-alone policy dictates the allowable tasks and responsibilities when operating staff are required to work alone. Attempting to resolve inherent design issues with other vendors when the OEM is unable to provide a better or permanent solution. Effectively utilizing the knowledge and skills of a relatively small staff to accomplish all winter readiness objectives. Installation of a new 500 gallon kerosene tank to ensure an adequate supply of kerosene is available for all portable space heaters if fuel delivery is delayed. 6

7 Design and installation of permanent enclosures surrounding the drum level transmitters will provisions to remove ceiling and floor when cold weather preparedness is no longer required. Ensuring that a formal and thorough heat trace and insulation audit was conducted to ensure winter readiness. 7

8 Vent/Drain Line Trough Cover was designed by plant personnel to prevent water overflow causing the formation of large ice build-ups which when broken free, caused line breaks, piping damage and ice accumulation on equipment below. 8

9 Although other critical transmitters such as those for measuring boiler drum pressure were insulated and heat-traced, an additional enclosure was designed by plant personnel to prevent future freezing. The six protrusions on the front panel are where isolation valve hand-wheels were removed to prevent a penetration for cold air in-leakage. 9

10 Double-insulated installation designed by plant personnel for boiler drum level transmitters exposed to extreme cold and wind chill effects. 10

11 Heater Tracing Cabinets are located throughout plant site for monitoring, control and alarming of heat tracing circuits. List of system or equipment is provided for operator s reference. Panel provides means for operator to select a specific heat tracing circuit for observing current and temperature of circuit or detecting abnormal conditions such ground faults. 11

12 View of a typical heat tracing panel. The system is normally operating in automatic mode based on a thermostat setting, but can also be operated in manual. A strobe on top of the panel makes it easy for anyone to identify when there is a failure of one of the heat traces. Trending and comparison of heat trace currents are used to detect failing heat traces. 12

13 Newly installed insulated weather barrier in boiler room to prevent the entry of cold air which caused freezing of feedwater flow transmitter. 13

14 Newly fabricated enclosure for Unit No. 2 feedwater flow transmitter. 14

15 Temporary heaters rented by entity to be used as backup or to supplement existing heaters at various locations of plant. 15

16 Portable heaters are brought in to keep the Heat Recovery Steam Generator (HRSG) from freezing when the units are off line. Without these heaters the boiler would need to be drained. This also helps to shorten the start up of the boiler since it is kept warm. 16

17 Rerouting of sensing lines, insulating, heat tracing and relocation of HRSG drum level and pressure transmitters. 17

18 Replacement of various transmitter enclosures with improved design to maintain internal temperatures above freezing conditions. 18

19 Remote monitoring and alarming of all transmitter enclosures from Distributed Control System (DCS) display in plant control room. 19

20 Remote monitoring of each heat trace circuit amperage from a dedicated display in the plant control room. 20

21 Permanent enclosures surrounding the steam drum ends for site glasses and transmitters. The floors and ceilings of the enclosures are only installed in preparation for winter readiness. 21

22 New O Brien Heat Trace system with exterior clamps. Old design utilized metal clamps that were internally secured to the transmitter sensing lines and directly connected to the structural steel which acted as a heat sink and resulted in freezing of the sensing lines. 22

23 Temporary heaters and ducting utilized to prevent the formation of ice and snow on the surface of the air inlet filters. 23

24 Gutters/downspout system used to divert rain water/moisture accumulation away from being draw into the inlet air filters. 24

25 Specially designed heated blankets are used to prevent the Demin lines from freezing. These blankets use Velcro fasteners to attach to the hoses. They can be removed to prevent damage to the blankets during the summer. 25

26 Areas For Improvement Due to the extensive work done by the entities to ensure winter readiness, only three areas of improvement were identified: Routinely operate any idle or standby equipment to ensure availability. Ensure heat tracing or freeze protection is installed on all equipment that has the potential to freeze. Ensure plant instrument air system is providing a continuous supply of moisture-free air to ensure proper operation of valve actuators. 26

27 Questions & Answers Forward Together ReliabilityFirst 27