Single Nozzle, Spindle Operated

Unlike a control valve where energy is lost as flow is throttled, a spindle reduces the flow rate without reducing the energy available per unit flow. This permits the thermocompressor to use the maximum energy available at all ranges of flow and extends the capacity variation of a single unit. 

Spindle operated units can be provided with either manually or automatically operated spindles. Thermocompressors with manually-operated spindles are designed for applications where loads will remain steady but where changes in operating conditions may occur and when operating conditions are not sufficiently established and some flexibility in nozzle orifice size is preferred.Thermocompressors with automatically-controlled spindles are used where pressure, suction, or discharge conditions vary and it is necessary to control discharge pressure or flow. 

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Figure 18-2 Ejectors used for thermal compression, (a) Single nozzle type, (b) Spindle operated type, (c) Multiple nozzle type.

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