Page 204 - Sustainable On-Site CHP Systems Design, Construction, and Operations

The Engineering Pr ocess 177

the engine from the CHP plant. Overhead hoists and cranes can be incorporated into
the plant to ease maintenance operations including pulling heads on IC reciprocating
engines. CTG engine washdown and provisions should be made for storage of the
washdown cart as well as its use.
With a chiller or a HRSG, provision must be made for tube pull and tube cleaning.
On a chiller, the tube pull area often equals the length of the chiller. Vapor compression
chillers and fired devices (e.g., boilers) typically require an area separation due to fire
codes (i.e., a fire rated wall between the latter equipment types). It must be understood
by the CHP design team that everything eventually breaks and needs to be repaired.
CHP plant and equipment layout needs to account for this eventuality.

Future Expansion
Where the proposed initial CHP system includes provisions for owner-operator antici-
pated future expansion to meet future load growth (e.g., due to owner-operator pro-
grammed additional buildings or processes), provision in the initial installation should
include accessible points of connection (POC). This allows additional equipment to be
installed with only minor disruption to existing CHP plant operations.
Planning for future expansion may involve oversizing headers and distribution
piping, power and structure for the future expansion, and includes providing space for
the future equipment or a planned path for expanding the plant to provide that space.
Planning for future expansion includes capped connections with shutoff valves as
future POCs. Note that oversizing the headers and piping may be partially self amortiz-
ing in term of reduced pumping power (energy consumption) requirements. The CHP
engineering team should always consider as an integral part of its initial design that
whatever is constructed today will require some changes, and should plan for 10, 20,
even 30 years or more following initial construction during which utility infrastructure
expansions may be needed from time to time. The planning horizon for an energy plant
in Europe is often 100 years.
Future planning considerations are especially relevant for building underground
cable and piping systems, and should include some provisions to allow installation for
additional prime mover generators and heat recovery needs. The design and construc-
tion of future equipment pads should wait, however, for installation of the actual equip-
ment as codes and specific equipment design may change in the future.

Noise and Vibration Attenuation
Depending on the type of prime mover employed, location of the proposed CHP plant, as
well as the distance to surrounding neighbors and their occupancy (e.g., manufacturing or
residential), noise and vibration mitigation may be required. In a two-dimensional analysis
(which is the case where noise transmission is analyzed in plan view and there are no noise
receptors above or below the CHP unit), noise level drops by the square of the distance from
the source. Low frequency rumble can carry farther than higher pitched sounds. Therefore,
the farther away the proposed CHP system is from a noise receptor, the lower will be the
sound level measured at the receptor. If the CHP system is to be located in a noise sensitive
area (e.g., next to campus dormitories and adjacent residential areas), it is recommended to
include an acoustical engineer as a member of the CHP design team. Noise can be trans-
mitted by either direct “breakout” at the equipment or by translating down ducts and pipes.
Also, noise and vibration can be transmitted directly through pipe, duct, and supports
attachments. Noise mitigation addresses all of the noise transmission paths.