Heat-r Rate-r Engineering
Example Study - Furnace Coil Replacement
Client’s HP Steam Superheat Coil in Ammonia Plant
Chem-Engineering Services’ client desired to upgrade an existing Ammonia Plant furnace
convection section to achieve greater High Pressure Steam superheat to improve plant capacity
and furnace efficiency.  The client requested an Energy Optimization Study of the entire furnace to
improve its performance.

The existing furnace, was operating with aged Low Temperature and High Temperature Steam
Superheat coils at the following conditions.  (All of the other coils were analyzed for improvement)
The client commissioned Chem-Engineering Services to perform a total furnace Energy Optimization Study, to decide how
best to upgrade an aged furnace.  Several options were considered, including cleaning of the furnace coils as well as
replacement of either the Low Temperature Steam Superheat Coil or the High Temperature Steam Superheat Coil to obtain
higher steam superheat.  Overall furnace studies were performed to establish the best course of action to achieve the highest
energy savings and improve plant capacity.

The upgrade coil design selected with the client was a replacement Low Temperature Steam Superheat Coil, designed to
operate as illustrated below.  Energy savings results from lower steam requirement at higher steam superheat.  The new LT
Steam Superheat Coil is calculated to operate with the cleaned existing HT Steam Superheat coil as follows.  (All furnace
convection coils performance were calculated with cleaning)
From overall furnace performance calculations with the upgrade LT Steam Coil installed, the Energy savings for the Ammonia
Plant is predicted to be 0.27 Million Btu/ST Ammonia, equivalent to approximately $680,000 to $1,530,000 US currency
annualized savings, for energy costs between $4.00 to $9.00 per Million Btu (HHV).

All of the furnace convection coils were studied and other coil changes were recommended for replacement as well.  The
client included those changes in the overall furnace retrofit project scope.
Heat-r Rate-r software is designed to investigate Chem-Engineering Services client's plant
operating problems and provide reliable solutions and equipment improvements to reach the
plant's goals.
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