PERFORMANCE
To help you evaluate jet compressors in terms of your particular requirement the following performance criteria should be considered.
Jet compressors can be divided into two categories based upon the type of performance.
The first category is termed “noncritical” in performance. If the absolute pressure at the compressor discharge is less than 1.8 times the absolute pressure at the suction (for instance, suction pressure 15 psia – discharge pressure 27 psia), the performance is noncritical.
When performance is noncritical, a constant pressure can be maintained at the suction of a compressor, at varying capacities, by controlling motive flow.
The second category is termed “critical” in performance. If the compression ratio (ratio of absolute discharge pressure to absolute suction pressure) is over 1.8 to 1 (for instance, 20 psia is 36 psia), the performance is critical.
When performance is critical, control cannot be exerted by means of the motive fluid. In order to control the suction pressure of such a unit at varying process loads, it is necessary to maintain a constant load on the compressor by addition of a secondary suction fluid, or to vary the suction pressure at the compressor by introducing an artificial pressure drop in the suction line.
Most jet compressors are operated at low compression ratios and are noncritical in performance. Should there be any question about control or performance, please check with S&K Engineers.
SIZING CHARTS
To find out whether or not a jet compressor will provide desired performance and the size required to meet requirements, refer to the charts on pages 3 through 6 for thermocompresors and to the charts on pages 7 and 8 for other gases.
TABLE 1. THERMAL DATA FOR GASES
(for use in ordinary calculations)
The symbols below are common to this and similar type problems. Check gas tables for thermodynamic properties.
Chart A – Sizing Chart for Thermocompressors
(Types 420, 425, 426, 427, 439)
Chart B – Capacity Ratios of Steam Jet Thermocompressors
100 psig Operating Live Steam
Chart C – Capacity Ratios of Steam Jet Thermocompressors
125 psig Operating Live Steam
Chart D – Capacity Ratios of Steam Jet Thermocompressors
150 psig Operating Live Steam
Chart E – Capacity Ratios of Steam Jet Thermocompressors
200 psig Operating Live Steam
Chart F – Capacity Ratios of Steam Jet Thermocompressors
200 psig Operating Live Steam
Chart G – Capacity Ratios of Steam Jet Thermocompressors
300 psig Operating Live Steam
Chart H – Capacity Ratios of Steam Jet Thermocompressors
300 psig Operating Live Steam
Chart I – Capacity Ratios of Steam Jet Thermocompressors
400 psig Operating Live Steam
Chart J – Capacity Ratios of Steam Jet Thermocompressors
400 psig Operating Live Steam
Chart K – Capacity Ratios of Steam Jet Thermocompressors
400 psig Operating Live Steam
Chart L – Capacity Ratios of Steam Jet Thermocompressors
600 psig and 600°F.
Chart M – Capacity Ratios of Steam Jet Compressors
600 psig and 600°F.
Chart N – Capacity Ratios of Steam Jet Thermocompressors
600 psig and 600°F.
Chart O – Capacity Ratios of Steam Jet Thermocompressors
600 psig and 600°F.
Chart P – Capacity Ratios of Steam Jet Thermocompressors
600 psig and 600°F.
Chart Q – Propane-Air Back Pressure Curves
Chart R – Propane-Air Capacity Curves For 2”
Type 420 Gas Jet Compressors
Chart S – Butane-Air Back Pressure Curves
Chart T – Butane-Air Capacity Curves For 2”
Type 420 Gas Jet Compressors
Chart U – Natural Gas-Air Back Pressure Curves
Chart V – Natural Gas-Air Capacity Curves For 2”
Type 420 Gas Jet Compressors
Chart W – Air-Air Back Pressure Curves For Type 420 Air Jet Compressors
Chart X – Air-Air Capacity Curves For 2” Type 420 Air Jet Compressors
