NEWS RELEASE                                                                                        October 2019

True Cost of Limestone FGD Recycle Pumps

The McIlvaine Company is working with associations, media and suppliers to create true cost analyses of combust, flow and treat products and services. One such initiative is the “True Cost of Limestone FGD Recycle Pumps”.

80,000 MW of limestone FGD recycle pumps will be purchased in India over the next three years. Over 1.5 million MW of these large pumps are continually being operated at power plants around the world. Their  true cost (total cost of ownership) is a substantial percentage of the true cost for electricity production. One reason is the choice of pump energy over fan energy.

 It can be argued that scrubbers using less recycling slurry but more fan energy are a better choice but the coal fired power industry has standardized on the spray tower type of limestone scrubber.  For a 1000 MW scrubber the recycled slurry will be as much as 200,000 gpm  delivered to the top of a spray tower at a 50-100 ft elevation. This slurry is an abrasive, corrosive combination of gypsum, calcium sulfite and limestone particles along with some residual flyash.  The pumps are expected to remain functional for 20 years or more.

The true cost of the pump purchase is impacted by many factors

  • System design: the piping design, pump location, valve resistance, spray tower nozzle type, chloride bleed provisions, requirement for spares and other factors
  • Pump design including initial efficiency, deterioration characteristics, and pump characteristics
  • Energy consumption for the new pump and during the cycle prior to repair
  • Cost of energy
  • Cost of repair parts and frequency of replacement
  • Cost for service
  • Operational factors such as maintenance quality, hours of operation per year etc.
  • Downtime costs
  • Labor rates
  • Related costs such as greater use of limestone or treatment chemicals with varying pump performance

India has adopted specifications with minor modifications which were first written decades ago for projects in the U.S. or Japan. A recent BHEL specification for an FGD system in Bangladesh Is for two generators each 660 MW and each unit with one FGD system. Each FGD system will be provided with five recirculation pump (4 working + 1 standby) which are located inside the Recirculation Pump & Oxidation Blower House.

The specifications for the recirculating pump allow for rubber lining, stainless alloys or silicon carbide materials in contact with the sulfite slurry with a maximum of 27,000 ppm chlorides.

This worldwide standardization of scrubber designs and pump requirements means that there is ample evidence of true cost of the various pumps which have been utilized and the ability to project true costs for future installations.

True cost is impacted by the location where the pump is manufactured and the location where the pump is repaired. It is also impacted by the service personnel proximity and the option for remote monitoring and support.

Libra Fluid Equipment Co., Ltd is home based in China. It was founded in 1999 and provides pumps and parts for various industries. It  supplies pump parts for any pump where the patents have expired.  It supplies ceramic, alloy and rubber lined impellers. This has true cost implications. The true cost of a pump purchased from any company without recently patented parts may be reduced with the option of purchasing parts from others such as Libra.

Parts and repair is a major true cost factor. Duechting Pump manufactures pumps in Germany but has regional service centers around the world. Is the true cost greater or the same for pumps supplied in the U.S and Asia? 

KSB is a German based company but purchased GIW and manufactures pumps in the U.S.  

Trillium has multiple manufacturing and service locations.

Suppliers are being asked to provide true cost analyses which will be published in Coal Fired Power Plant Decision  This is a service which is free of charge to utilities around the world.

The service already includes recorded webinars and case histories of FGD pump performance compiled over decades. The Utility Tracking System identifies every FGD system in the world and includes the pump supplier for many of them.

This is a continuing process. As suppliers gain additional evidence it can be incorporated. The process is likened to a criminal trial where the supplier is the prosecutor and the jury is the purchaser. The difference is that the jury is periodically asked to review its decision based on new evidence such as life of impellers and casings in this recent case history.

The scrubber recycle pumps in this plant have operated at a flow rate of 1,310 cubic meters per hour (m3/h), 21.1 meters (m) of head and 630 revolutions per minute (rpm) for nearly 20 years, requiring minimum attention and service. Of course, the mechanical seals were exchanged from time to time. Apart from that, four impellers, one casing cover and some minor components were replaced. An additional 24 pumps are installed in the second scrubber system and other applications in the plant.

There should be separate true cost analyses for each location.  It is particularly important to analyze the cost in India.  A good example is the analysis by SHI FW relative to wet vs dry scrubbers for Indian power plants.

Sumitomo SHI FW has made a detailed analysis comparing CFB scrubbers to wet limestone scrubbers without wallboard quality gypsum production. 

The  lower quality of limestone available, the expected 15-year life for the older plants to which the system may be applied, and the much lower capital cost of the CFB design are key aspects in the determination. Here are the factors and calculations for a 300 MWe  pulverized boiler contained in the linked paper.

The analyses are being pursued with personal discussions including  at the upcoming PowerGen in New Orleans - There will be a PowerGen University half day session on Monday where McIlvaine will advise suppliers interested in reaching the international market to prepare detailed true cost analyses of their offerings. There will also be a tour guide. Speakers, exhibitors, and attendees interested in FGD recycle pumps will be listed in the directory with emails and mobile phone numbers to facilitate discussions during the conference.

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To participate in the True Cost of Limestone FGD Recycle Pumps  contact Bob McIlvaine at This email address is being protected from spambots. You need JavaScript enabled to view it.  direct 847 784 0013 cell 847 226 2391.