"Cooling Towers and Cooling Water" Hot Topic Hour November 1, 2012

 

This Hot Topic Hour was divided into two parts. One part focused on cooling devices and the other part on cooling water cleanliness. It started with a discussion by Air Cooled Condenser (ACC) Users Group with Andrew Howell and assistance from David Rettke. We then moved on to Ovivo approaches to water treatment with Trent Gathright and Richard Coniglio. We had hoped to discuss trends such as ACC for new shale gas CCGT, ozone for cooling water treatment, zero liquid discharge, co-location of sewage treatment and power plants, process considerations with carbon sequestration and other relevant topics but time ran out. Fortunately, we conduct a Hot Topic Hour each week, so we can address these issues later.

 

ACC Users Group was established in 2009 to foster collaboration among owner/operators of power plants with air-cooled condensers. It is the only user group dedicated to resolving issues with air-cooled condensers. User participants include water chemists and O&M personnel at steam plants, combined-cycle facilities, and other types of generating stations relying on dry cooling. http://acc-usersgroup.org/

 

 

Andrew Howell, Senior Systems Chemist Xcel Energy, started the discussions with a good overview of the ACC Users Group and its recent conference. Andy’s responsibilities at Xcel Energy and its predecessor companies since 1982 have included problem-solving investigations concerned with (1) failure analyses and materials-degradation evaluations; (2) mitigation of scale, corrosion, and deposits in boilers, turbines, and other power plant equipment; and (3) prevention of condenser air inleakage. The last involved organizing and directing a condenser tube fouling and failure team to identify the root causes of problems and to recommend system improvements. Deliverables included a best practices document to help plant personnel minimize tube failures and maximize condenser performance.

 

Andy has written or co-authored company best-practices guidelines for steam cycle chemistry, systems with copper alloys, boiler makeup chemistry, online instrumentation, etc. Recently he developed cycle chemistry guidelines for a new supercritical power plant with hybrid air/water cooling system. Andy briefly reviewed some of the maintenance problems and corrosion related issues in the operation of a large supercritical coal-fired boiler. At the same time we sequenced through his power points which are accessed below:

 

Power Points for Initial Post-Operational Inspection of Comanche Unit 3 ACC

 

 

David Rettke, Maintenance Specialist Walter M Higgins Generating Station, NV Energy.

 

Dave has more than 30 years of industrial maintenance experience as a machinist, millwright, mechanic, and welder in various industries — the last six years in generating facilities. At Higgins Station, where he is intimately involved in ACC maintenance, Dave champions the plant’s continuous performance improvement, root cause analysis, vibration monitoring, and condition-based maintenance programs. Among Dave’s certifications: ISO Level 2, ANST Level 2 vibration analyst, Level 1 airborne ultrasound, balancing of rotating equipment. Click on the following for Dave’s slides. What is the condition of your ACC?

 

 

Trent T. Gathright, Sales & Marketing Manager Cooling Water Products for Ovivo, provided extensive information on intake water screen.

 

Trent T. Gathright has served 34 years in the field of mechanical water filtration for cooling water intakes and condenser protection. His experience with screening plant equipment includes design, manufacturing, rebuilding, installation and research & development. He commonly assists EPC & A/E firms with cooling water system designs and upgrades. Research includes underwater studies of fish behavior when encountering rotating screening devices leading to the development of hydraulically stabilized screening elements to increase survivability of juvenile fishes, (EPRI Proceedings, March 1988). This is commonly known as the S.I.M.P.L.E.® design, and is recognized as BTA for 316(b). Other developments include a patent for a “Retractable Traversing Trash Rake” (RTTR) for adaptability to existing structures to mitigate loss of cooling water at the primary intake. These are currently installed at multiple nuclear power stations. Mr. Gathright is currently employed by Ovivo USA, serving as the Sales & Marketing Manager in the Energy Group for Cooling Water Products.

 

Ovivo has extensive experience supplying intake screening for nuclear, hydropower and fossil fuel power plants, which incorporate the Brackett Green® and Brackett Bosker® Racking Machine, Thru-Flow/Dual Flow/ Drum type screens, StopGatesT technology, HR Debris filters, automatic tube cleaning systems, Brackett BriedenT automatic back flushing filters, Fish Guidance/Fish Recovery/Return systems as well as a range of Automatic Debris Racking Machines, intake screening technologies and Condenser Protection systems. In addition to the environmental benefits, these systems can cut the owner’s trash disposal costs and reduce the chances of disruption to generation due to the loss of cooling water as a result of massive inundations of schooling species, debris accumulation and micro and macro fouling of condensers.

 

Trent reviewed various options and compared initial cost to life cycle cost for alternatives. Some options with slightly higher initial cost are much more economical over the plant life. Some options depend upon the conditions of the source water including flow. Barr Engineering pointed out that they encounter river conditions which are nearly stagnant and do not provide a cleaning mechanism for a passive screen.

 

 

Richard Coniglio, Business Product Manager Energy Group Americas Ovivo USA, holds a Bachelors and a Masters degree in Civil Engineering from Cornell University and has twenty five years of global experience in the design, manufacture and service of water and wastewater treatment equipment.

 

Richard reviewed the various treatment needs for municipal wastewater used in power plants. The biggest problem is potentially biological due to the nutrient load. Ovivo has systems to handle the full range of contaminants. Each component was reviewed by Richard.

 

Following the presentation there was a discussion of the potential for utilizing treated municipal wastewater in power plants. Richard pointed to a study showing that almost all the power plants are within a short distance to a municipal wastewater treatment plant. Bob McIlvaine made a case for co-location of municipal wastewater treatment plants and power plants. Low pressure power plant steam can be used to dry sewage sludge which can then substitute for some of the coal. Sewer mining is a concept which dictates that wastewater treatment plant additions should be at the power plant site.

 

The entire November 1 recording can be heard at: Cooling Towers and Cooling Water Issues – 83 minutes – Password: hth168

 

The individual presentations are as follows: