Pumps high duty

High-duty pumps are equipped with steam cylinders in which the steam is used expansively. As the load is constant throughout the stroke and the steam piston force diminishes during the period of expansion, some compensating device is necessary to equalize the forces. This may be a fly wheel, an auxiliary... 

The low-duty triple-expansion pump has taken the place of the high-duty compound pump and only triple-expansion high-duty pumps are now built. They give the same duty as crank and flywheel triple-expansion pumps, have greater flexibility, require lighter foundations and the valve motion is simple. Adjustment for speed is made by hand throttle valve which is satisfactory because the load is constant. 

Use of wound-rotor induction motors has been largely in continuous-duty constant-speed supplications where particularly high starting torques and low starting currents are required simultaneously, such as in reciprocating pumps and compressors. These motors are also used where only alternating current is available to drive machines that require speed adjustment, such as types of fans and conveyors. 

A further Class 6 is suggested for pumps intended for batch or intermittent duty. (If high availability is essential, the machine should be placed in Class 4.)... 

The main factor that has been responsible for the slow adoption of absorption heat pumps for heating and air conditioning duties has been their high capital cost compared with that of vapor compression equivalents. This is due largely to the cycle complexity, as shown in Figure 14, which displays the four principal cycle elements, all of which involve vapor-liquid systems ... 

If the pump is 50% efficient, actual power = (227/0.5) = 454 W A PTFE lined centrifugal pump and lead or high silicon iron pipe would be suitable for this duty. 

Improvements in overall thermal efficiency have been coupled with the introduction of extensive air preheat to decrease the fired fuel requirements. Additional decreases in fired fuel requirements can be obtained by materially improving the radiant box efficiency through changes in radiant box geometry. Usually a balance was struck between the fired fuel requirement to meet the thermal reactor duty, and the overall need for additional heat for generation of high pressure steam required for the process as a reactant or for driving pumps, compressors, or... 

High-pressure specification canned-motor centrifugal pumps can provide the solution for the hardest pumping duties. The pump illustrated in Figures 8 and 8.1 has to pump a corrosive suspension in a continuous flow at a starting temperature of 250°C and an inlet pressure of... 

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