Carrier 16DF013-050 - Manual (Page 3)

CONTENTS (cont)
Page
MAINTENANCE PROCEDURES . . . . . . . . . . . . . 46-53
Log Sheets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Absorber Loss Determination . . . . . . . . . . . . . . . . 46
Machine Leak Test . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Machine Evacuation . . . . . . . . . . . . . . . . . . . . . . . . . 48
Purge Exhaust Procedure . . . . . . . . . . . . . . . . . . . 48
Solution or Refrigerant Sampling . . . . . . . . . . . . 48
• SOLUTION SAMPLE
• REFRIGERANT SAMPLE
Solution Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Inhibitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Adding Octyl Alcohol . . . . . . . . . . . . . . . . . . . . . . . . 49
Removing Lithium Bromide from Refrigerant . 49
Refrigerant Charge Adjustment . . . . . . . . . . . . . . 49
Page
Capacity Control Adjustment . . . . . . . . . . . . . . . . 49
Operating and Limit Controls . . . . . . . . . . . . . . . . 49
Burner Checks and Adjustments . . . . . . . . . . . . . 50
Service Valve Diaphragm Replacement . . . . . . . 50
Hermetic Pump Inspection . . . . . . . . . . . . . . . . . . . 50
• DISASSEMBLY
• INSPECTION
• REASSEMBLY
• COMPLETION
Condensing Water Tube Scale . . . . . . . . . . . . . . . 53
Water Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Solution Decrystallization . . . . . . . . . . . . . . . . . . . 53
Internal Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
TROUBLESHOOTING GUIDE . . . . . . . . . . . . . . . 54-56
INTRODUCTION
Everyone involved in the start-up, operation, and main-
tenance of the 16DF machine should be thoroughly familiar
with these instructions, the separate burner instructions, and
other necessary job data before initial start-up, and before
operating the machine or performing machine maintenance.
Procedures are arranged in the sequence required for proper
machine start-up and operation.
NOTE: In this manual, temperatures are shown in °C first,
with °F given in parentheses (
), when a temperature dis-
play is in °C or a control set point scale is in °C values.
MACHINE DESCRIPTION
Basic Absorption Cooling Cycle — The 16DF ab-
sorption chiller uses water as the refrigerant in vessels main-
tained under a deep vacuum. The chiller operates on the simple
principle that under low absolute pressure (vacuum), water
takes up heat and vaporizes (boils) at a low temperature. For
example, at the very deep vacuum of 0.25 in. (6.4 mm) of
mercury absolute pressure, water boils at the relatively cool
temperature of only 40 F (4 C). To obtain the energy re-
quired for this boiling, it takes heat from, and therefore chills,
another fluid (usually water). The chilled fluid then can be
used for cooling purposes.
To make the cooling process continuous, the refrigerant
vapor must be removed as it is produced. For this, a solution
of lithium bromide salt in water is used to absorb the water
vapor. Lithium bromide has a high affinity for water, and
will absorb it in large quantities under the right conditions.
The removal of the refrigerant vapor by absorption keeps
the machine pressure low enough for the cooling vaporiza-
tion to continue. However, this process dilutes the solution
and reduces its absorption capacity. Therefore, the diluted
lithium bromide solution is pumped to separate vessels where
it is heated to release (boil off) the previously absorbed wa-
ter. Relatively cool condensing water from a cooling tower
or other source removes enough heat from this vapor to con-
dense it again into liquid for reuse in the cooling cycle. The
reconcentrated lithium bromide solution is returned to the
original vessel to continue the absorption process.
Double Effect Reconcentration — With this chiller,
reconcentration of the solution is done in 2 stages to im-
prove the operating efficiency. Approximately half of the
diluted solution is pumped to a high-temperature vessel (high
stage) where it is heated for reconcentration directly from
the combustion of gas or light oil. The rest of the solution is
pumped to a low-temperature vessel (low stage) where it is
heated by the hot water vapor generated in the high-temperature
vessel. The low stage acts as the condenser for the high stage,
so the heat energy first applied in the high-stage vessel is
used again in the low-stage vessel. This cuts the heat input
to almost half of that required for an absorption chiller with
a single-stage reconcentrator.
Basic Heating Cycle — The heating cycle uses a dif-
ferent vapor flow path than that used for cooling, and does
not use the absorption process. The high-temperature water
vapor produced in the direct fired high-stage vessel is passed
directly to the heating tubes where it condenses and trans-
fers its heat into the circulating hot water. The condensed
water then flows by gravity to mix with the concentrated so-
lution which had returned from the high-stage vessel. This
diluted solution then is pumped back to the high-stage ves-
sel to repeat the vapor generation for the heating function.
Machine Construction — The major sections of
the machine are contained in several vessels (Fig. 1- 4,
Table 1).
The large lower shell contains the evaporator section in
its upper part and the absorber section at the bottom. In the
evaporator, the refrigerant water vaporizes in the cooling cycle
and cools the chilled water for the air conditioning or cool-
ing process. In the heating cycle, hot water vapor flows into
the evaporator section where it condenses and heats the hot
water for the heating process. The heat transfer tube bundle
in the evaporator is used for both cooling and heating. In the
absorber, vaporized refrigerant water is absorbed by lithium
bromide solution in the cooling cycle. In the heating cycle,
condensed refrigerant water from the evaporator drains into
the absorber where it is mixed with the strong solution.
The short vessel with the burner, located next to the
evaporator/absorber assembly, is the high-stage generator. The
vessel above it is the separator. In both the cooling and heat-
ing cycles, approximately half of the diluted lithium bro-
mide solution is heated directly from the combustion of gas
or oil. The water vapor created in this process is released
from the reconcentrated solution in the separator vessel.
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