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(Solution concentration at the high pressure generator outlet)
1) Read the high pressure generator pressure.
2) Read the intermediate concentrated solution temperature at the high pressure generator
outlet.
3) Then, draw a horizontal line of the pressure value obtained above 1) and search for a point
of intersection with the perpendicular stood from the solution temperature obtained above
2). It is the point indicating the solution concentration.
If the solution concentration is more than 64.5%, the following measures must be taken.
1) Throttle the fuel control valve until the solution concentration at the high and low pressure
generator outlets drops less than 64.5%.
2) At ordinary load operation check the level of refrigerant reservoir of the evaporator. Unless
it over-flows, refrigerant must be charged.
7.2 De-crystallization
Lithium bromide solution in the chiller-heater may be crystallized when the concentration of solution
becomes excessively high. Although the crystallization gives no physical damages to the chiller-
heater itself, it may cause a disturbance of the solution circulation resulting in cooling capacity drop.
Crystallization can be detected by the following phenomena:
(1) The solution level is out of sight from the absorber sight glass.
(2) The automatic de-crystallization device works and the temperature of the over-flow pipe rises
because the solution flows in the over-flow pipe.
(3) Cavitation in the solution pump takes place and noise generates.
When such a phenomenon is detected, de-crystallize by taking the following countermeasures :
1) Reduce the cooling water flow rate or stop the cooling water pump.
2) Open the refrigerant by-pass valve and damp the refrigerant to the absorber. When the
refrigerant level is out of sight from the evaporator sight glass, close the by-pass valve.
3) Carry out service level is out of sight from the evaporator sight glass, close the by-pass valve.
4) Reduce the combustion flow rate to 30~40% by the manual fuel control valve.
When the solution level returns to the normal level, de-crystallization is considered to be
completed. Then, the chiller-heater will return to the normal operation. If crystallization spreads
over the solution pump and the service operation can not be carried out, heat the solution pump
suction pipe and the low temperature heat exchanger with a torch lamp or gas burner to de-
crystallize the solution. When the solution pump can operate, above countermeasure item 1) to 4)
must be made. Contact our service agent for these countermeasures.
7.3 Recording of Operation Data.
For the purpose of prevention from serious damage in the chiller-heater and of earlier detection of
the signs of abnormal phenomena, keep recording the temperatures and pressures during
operation at a given period of time on a daily basis.
It is desirable to collect operation data in such a stable condition as the chiller-heater is
running as per the design conditions as much as possible.
As causes of the gradual drop of refrigerating capacity the scale accumulation in the tubes,
the gradual generation of non-condensable gas in the vessel, malfunction of control system,
etc. are considered.
Performance analysis must be conducted with data collected in the condition without any
leakage. Abnormal data on not only temperature but also solution concentration, evaporative
pressure and fuel flow rate are not useful for analysis at all.
8.
Prolonged Shut-down
When shutting down the chiller-heater in winter or for a long period for some reason proceed the
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