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Master Plan Utilities Summary

Document Origin
The following is the write up of the Central Heating and Chilling Plant’s in initial UWM infrastructure survey report, put together by the Master Planning team. It is a reproduction of their first draft report with a few minor corrections. The corrections that were made can be viewed at the end of this document.

6.1 SUMMARY OF UTILITY AND INFRASTRUCTURE ISSUES

Introduction
The purpose of the infrastructure assessment is to determine the configuration and capacity of the existing utilities that serve University facilities; assess whether these existing utilities are adequate to serve existing facilities; identify maintenance upgrades that need to be made to the existing systems; and identify any immediate improvements that could be made to the existing systems. Utility systems have a big impact on yearly expenditures for UWM. 

6.2 KENWOOD CAMPUS

The following sections summarize our findings on the utility and infrastructure systems on the Kenwood Campus. Diagrammatic plans indicating utility routes have been included in the appendix of this section.

Steam System

Basic System Description:
Three (3) 120,000 lbm/hr, water tube, dual fuel (natural gas and number 2 fuel oil) high-pressure steam boilers were installed in 1969. These boilers operate at 130 psig and distribute steam at 125 psig to the Main UW-M campus. These boilers have excessive vibration at high steam flows, so operate derated to a capacity of 90,000 lbm/hr each. The boiler duration does not pose a capacity or reliability problem for the campus. With the derated performance the campus has N+1 redundancy in boiler capacity with room for growth.

The boilers are meticulously cared for and have been partially retubed. Tube damage occurred while the boilers were operated using number 5 fuel oil. This fuel is no longer used. New dual fuel burners were installed in 1998, along with an oxygen trim system. No. 2 fuel oil is steam atomized.
Each boiler has an independent stack with a stack economizer. Combustion efficiency is approximately 84%, and overall plant efficiency was about 81.5% in February 2008.

Economizer Tube Protection Screens Retrofitted by UWM
Figure 6.1 Economizer Tube Protection Screens Retrofitted by UWM


Boiler stacks have internal access platforms for maintenance. Mark Kazmierski, Chief Engineer for the plant, designed a stainless steel screen system to protect economizer tubes from plugging due to falling stack corrosion deposits. To reduce condensation during at start-up, when burning fuel oil or during low load conditions, low pressure steam feedwater heaters are available to preheat boiler feed water before it enters the economizer tubes.

 Well maintained boiler feed pumps
Figure 6.2 Well maintained boiler feed pumps

 

Four multi-stage boiler feed pumps located in the basement take a suction from the two deaerators and discharge into the common feedwater header located below the main operating floor.

Two 240,000 lbm/hr tray-type Deaerators are installed in the upper level, providing nearly complete redundancy. These units have also been well maintained. Deaerator vent lines discharging directly above the deaerator experience water slugging when operated in cold weather. Condensing steam drips down the vent line and eventually gets expelled as slugs, creating an ice problem around the deaerator vent. Mr. Kazmierski addressed this problem by designing a condensing pot above the deaerator, allowing the condensate to be drained away, reducing slugging.

Deaerator vent arrangement to eliminate icing
Figure 6.3 Deaerator vent arrangement to eliminate icing

 

The deaerator is served by four (4) condensate pumps, pumping condensate return water stored in a 20,000 gallon storage tank, located in the basement of the plant. A surface blowdown heat recovery system preheats make-up water before it enters the condensate receiver. A blowdown cooler tempers hot condensate leaving the surface blowdown heat exchanger and bottom blowdown prior to discharging into the sanitary system.

Blowdown Cooler and Heat Recovery Heat Exchanger
Figure 6.4 Blowdown Cooler and Heat Recovery Heat Exchanger

 


System Capacity:
Steam generation capacity with boiler derating is 270,000 lbm/hr. Peak historical steam demand is about 130,000 lbm/hr. With boiler derating, N+1 redundancy can be maintained with a 50,000 lbm/hr increase in load. Thus, the campus size could increase nearly 40% on the existing boilers and still have a back-up boiler on the coldest day of the year. Elimination of one steam driven chiller will make an additional 17,500 lbm/hr of steam available to serve campus expansion plans in the summer. Peak steam loads experienced in the winter would not be affected by elimination of a steam chiller.

Piping Distribution System:
Steam is distributed through the tunnels to campus buildings through a 16- inch high pressure steam (HPS) main operated at 125 psig (140 psia). The HPS main is sized to handle the full capacity of all three boilers. Because the piping is operated at a high temperature, it not as susceptible to the type of damage experienced by the chilled water lines, as any water penetrating the insulation would typically evaporate prior to reaching the pipe. Road salt dripping on the piping and supports can lead to problems. Tunnel steam piping did not appear to have corrosion problems. Support problems were identified in a 2007 tunnel report and our site observations are shown in later sections.

Maintenance Upgrades:
Steam tunnel issues are identified in other sections of this report. The packed-joint expansion joints of the steam system have seen very few cycles, as the system is pressurized all year, with the exception of an annual one-week shutdown. Expansion joints will require replacement over the next
twenty years, although there is currently no pressing reason to do this work until it is needed. UW-M already has a plan to replace expansion joints when they become a problem.

System Improvements:
The production side of the system is in excellent condition and very well maintained. Mark Kazmierski and his staff maintain the boiler plant very well and can keep the equipment efficiently operating for years to come with their current practices. Key steam system improvements are found in the load
sides. Several areas should be investigated:

1) Conversion of air side systems to Variable Air Volume (VAV),
2) Reduction or elimination of reheat,
3) Coordination of building occupancy/ building use to reduce wasteful operation of almost empty buildings during non-peak periods.


Corrections made

These boilers operate at 150 psig and distribute steam at 140 psig to the Main UW-M campus.
Was corrected to:
Boilers are designed for 150 psig but we operate at about 130 psig and send 125 psig to the main campus.

Boiler stacks have internal access platforms for maintenance. Mark Kasmierski, Chief Engineer for the plant, designed a baffle system to protect economizer tubes from condensation and rain water. To reduce condensation during start-up, low pressure steam to feedwater heat exchangers are available to further preheat boiler feed water before it enters the economizer tubes.
Was corrected to:
Boiler stacks have internal access platforms for maintenance. Mark Kazmierski, Chief Engineer for the plant, designed a stainless steel screen system to protect economizer tubes from plugging due to falling stack corrosion deposits. To reduce condensation during at start-up, when burning fuel oil or during low load conditions, low pressure steam feedwater heaters are available to preheat boiler feed water before it enters the economizer tubes.

2) Reduction or elimination or reheat,
Was corrected to:
2) Reduction or elimination or reheat,