Low-Cost Tweaks Yield Big-Time Savings

Once Jack Dale Associates (JDA) quantified mechanical-system interactions for Texaco's data center, specified techniques were employed to upgrade the plant while avoiding disruptions to data-processing operations. Total construction costs for chiller-plant renovations commissioned by JDA were less than $600,000.

11/01/2000


Once Jack Dale Associates (JDA) quantified mechanical-system interactions for Texaco's data center, specified techniques were employed to upgrade the plant while avoiding disruptions to data-processing operations. Total construction costs for chiller-plant renovations commissioned by JDA were less than $600,000.

Procedures outlined by the engineering team improved energy efficiency and continue to save the petrochemical company more than $100,000 per year in utility costs. The design not only solved operating problems, but also improved the facility's ability to increase its chilled-water reserve for future expansions. Best of all, the upgrades reduced energy consumption. Key features include:

 

The upgrades help set system demand and to ensure that only the required amount of chilled water is distributed.

Before JDA began work on the project, Texaco had received a number of proposals for resolving the facility's system problems. The least onerous of the proposals would have required a two-week shutdown of the entire 5,000-ton chiller plant and over $2 million to complete.

Table 1 - Existing HVAC System Parameters


TimeBypass positionB riser flowB supply tempB return tempMain CHW supply temp FChilled water flow (gpm)Flow to labs (gpm)BAX flow (gpm)East-West riser flow (gpm)Main return header pressure (psi)Main supply header pressure (psi)IBM CDU flow (L/M)


13:00


Closed


1584


44.6


52.7


43.6


2778


414


617


1610


66


65


190


13:15


10% open


1665


44.7


52.1


43.7


2787


426


626


1661


65


64


190


13:20


15% open


1634


44.6


52.1


43.6


2737


432


637


1655


65


65


190


13:30


20% open


1666


45.0


52.0


43.7


2645


505


636


1704


65


65


200


13:38


25% open


1686


45.0


52.1


43.9


2655


504


630


1713


65


66


200


13:43


35% open


1669


44.4


52.3


44.0


2635


504


637


1728


65


66


200


13:49


Full open


1662


44.6


52.7


44.3


2671


502


630


1778


66


67


200


13:57


Full open


1363


44.1


54.5


44.3


2631


513


627


1864


68


68


145


14:08


Full open


1333


43.5


54.1


43.8


2611


517


635


930


69


70


130


Table 2 - Savings from Mechanical Plant Re-engineering


Original designRe-engineered design


HP


kW


HP


kW


Subtotal:


972


611


Subtotal:


223


118


Chiller loads:


2,200


1,760


Chiller loads:


1,600


1,280


Total HP & kW:


3,172


2,371


Total HP & kW:


1,832


1,398


Dead head factor:


0.90


Pump kW saved:


973


Total kW Demand:


2,134 kW


Total kW demand:


1,398


Use factor:


0.80


Use factor:


0.80


Annual pump utility cost:


$235,462


Annual pump utility cost:


$45,530


Added utility cost for new office space:


$79,684


Net annual utility savings after chiller plant renovations:


$110,248


Average cost per kWh: 0.055 $/kWh





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