Carrier 16JT Series Start Up & Operation Manual

Carrier 16JT Series Start Up & Operation Manual Manual pdf 6 page image

Flow Circuits — Figures 5 and 6 illustrate the basic flowcircuits of the 16JT absorption chiller.The liquid to be chilled is passed through the evaporatortube bundle and is cooled by the evaporation of refrigerantwater sprayed over the outer surface of the tubes by the re-circulating refrigerant pump. The refrigerant vapors are drawninto the absorber section and are absorbed by the lithiumbromide-water solution sprayed over the absorber tubes. Theheat picked up from the chilled liquid is transferred from theabsorbed vapor to cooling water flowing through the ab-sorber tubes.The solution in the absorber becomes diluted as it absorbswater, and loses its ability to continue the absorption. It isthen transferred by the solution pump to the generator sec-tions to be reconcentrated. Approximately half of the weak(diluted) solution goes to the high-stage generator where itis heated directly by high-pressure steam to boil out its ab-sorbed water. This vapor passes to the low-stage generatortubes. In the low-stage generator, the rest of the weak so-lution is heated by the high-temperature vapor from the high-stage generator, to boil out its absorbed water.This water vapor from the low-stage generator solutionpasses into the condenser section and condenses on tubescontaining cooling water. This is the same cooling water whichhad just flowed through the absorber tubes. The condensedhigh-temperature water from the low-stage generator tubesalso passes over the condenser tubes where it iscooled to the condenser temperature. The combined con-densed refrigerant liquid from the two generators now flowsback to the evaporator to begin a new refrigerant cycle.The strong (reconcentrated) solution flows from the twogenerators back to the absorber spray headers to begin a newsolution cycle. On the way, it passes through solution heatexchangers where heat is transferred from the hot, strong so-lution to the cooler, weak solution being pumped to the gen-erators. Solution to and from the high-stage generatorpasses through both a high-temperature heat exchanger anda low-temperature heat exchanger. Solution to and from thelow-stage generator passes through only the low-temperatureheat exchanger, mixed with the high-stage generator solu-tion. This heat transfer improves solution cycle efficiency bypreheating the relatively cool, weak solution before it entersthe generators, and precooling the hotter, strong solution be-fore it enters the absorber. The efficiency is further improvedby transferring heat to the cooler, weak solution from the hotsteam condensate in the condensate drain heat exchanger andtrap.The weak solution flowing to the generators passes througha flow control valve which is positioned by a float in thehigh-stage generator overflow box. The purpose of the valveis to automatically maintain optimum solution flow to thetwo generators at all operating conditions for maximumefficiency.LEGENDEA — Refrigerant Pump Overload CutoutEA1 — Refrigerant Pump Overload CutoutEA2 — Solution Pump Overload CutoutEA3 — Solution Spray Pump Motor Overload CutoutEA4 — Vacuum Pump Motor OverloadFA1 — Chilled Water Low-Flow CutoutI/P — Current/Pneumatic TransducerLC — Refrigerant Cutout Level Switches(High, Mid, Low)PA1 — High-Pressure Switch (High-StageTemperature Generator)P1 — Compound Gage (High-TemperatureGenerator)PWS1 — Absorber Pressure SwitchSA — Pneumatic Supply AirTA1 — Chilled-Water Low-Temperature CutoutTA3 — Refrigerant Pump Motor Coil High-Temperature CutoutTA4 — Solution Pump Motor Coil High-Temperature CutoutTA5 — Solution High-Temperature CutoutTC2 — Cooling Water Temperature CutoutTIC — Chilled Water Outlet Temperature ControlTI 1-4 — Weak Solution ThermometersTI 5-8 — Strong Solution ThermometersTI 9-10 — Refrigerant ThermometersTSW1 — Automatic Start-Stop ThermostatTSW2 — Cycle-Guard™ ThermostatControl WiringPiping ConnectionsValveNOTES:1. Spray pump and second solution pump are lo-cated on large sizes only.2. Vacuum pump is optional.3. Electric capacity control is shown.(Pneumatic is optional.)*The LCD valve is physically located with the float in the high stage generator overflow box, notwhere it is schematically shown in the illustration.Fig. 5 — Typical Flow Circuits, with Data Points, Shown for 16JT080-150,080L-150L Arrangements6