District Energy - 2010 Second Quarter

Courtesy Citizens Thermal Engineering Group.

Since we do not inject amines, we needed to ensure that the pH of the condensate would not erode or corrode the new condensate system piping. In reviewing different types of piping for condensate, it was noted immediately that we had to keep the temperature of the returning condensate below 200 degrees F in order to use a pipe that had a resistance to low pH for long-term use. The pipe we chose was a preinsulated PEX and polyethylene with an oxygen diffusion barrier rated at 204 F. Our specifications for the customers are that the condensate needs to be returned at temperatures between 140 F and 200 F. In addition there are some specifications related to the conductivity of the condensate to ensure water quality.

The Perry K Steam Plant houses the condensate receiver and pumpout units for the condensate returning from the Lucas Oil Stadium, convention center expansion and other future customers.

At the same time, we decided not to allow traps from the distribution system to discharge directly into the condensate return system. At our Perry K Steam Plant, we installed a condensate receiver tank complete with pumpout units to return the condensate into the Perry K system.

the stadium and convention center up to 5 percent off their
existing steam bill – a discount that has been available in our
rate structure for many years but was not until recently in
use due to the lack of any condensate return system. (In the
future, other customers may also be able to take advantage
of this discount if we and they develop an economically sound
plan to install a return line or system from their buildings
back to Perry K. Customers who are very close to this new
system will be able to connect as long as the cost is right
for both of us.)

We hope that we will eventually be able to connect other existing and new customers to the system. We know that expansion of the condensate system is not possible in many areas, but our goal is to install a system that is reasonable in cost and at the same time benefits our customers. So far, our efforts are succeeding: Ever since the condensate return system has been in place, Lucas Oil Stadium and the Indiana Convention Center have seen both energy and cost savings. From October 2008 through December 2009, they purchased 102,200 Mlb of steam and returned 8.28 million gal (68,800 Mlb) of condensate back to Perry K. The amount

Citizens Thermal’s Downtown Systems

Number of Customers
Number of Buildings Served
Central Plant
Central Plant Capacity
Satellite Plant Capacity
Number of Boilers/Chillers
Energy Sales
Fuel Types

Length of Distribution Network
Piping Diameter Range
Steam Pressure
Supply Temperature
Return Temperature
System Water Volume

Source: Citizens Thermal.

Steam System 230 278 Perry K 2,000,000 lb/hr N/A 8 7,449,907 MMBtu Coal, natural gas and steam from Covanta waste-to-energy plant 27 miles total piping 1 to 30 inches 600, 400, 250, 15 psig N/A N/A N/A

Chilled-Water System
57
130
West Street
36,000 tons
38,000 tons (four satellite plants)
27 (central plant plus satellite plants)
151,000 ton-hr total from all plants
Steam and electric