Working point and flow adjustment
一. pipe characteristic curve
When centrifugal pump installed on specific pipeline system, the pump shall provide flow and pressure head, in accordance with the request of pipeline. Piping required pressure head and flow relation curves is pipeline characteristic curve, formula as He=A+BQe2
二. working point
When the pump mounting in certain pipeline system, pump characteristic curve and piping system and the curve intersection namely is pump operating point. Working point shown flow and pressure head is pump provides flow and pressure head, and the pipeline required flow and pressure head. Centrifugal pump only works in working point, pipe flow can be stable. Pump working point is advisable in the highest efficiency area.
三. flwo adjustment
For a pump is concerned, characteristic curve will not change, but pipeline characteristic curve is variable. When pump working point provided flow can not meet new conditions required flow, namely should try to change the position of the pump working point, namely, need to adjust flow.
flow adjustment method is:
(1) In centrifugal pump outlet pipeline installed one regulative valve, change valve opening, namely change pipeline characteristic curve B value in He=A+BQe2, valve opens, working point far away from the vertical axis, valve closes, working point close to vertical axis.
This adjustment method advantage is, simple, vivid operation. Its defect is, valve closes, in pipeline resistance increases, the energy loss increases, thus making pump cannot work in the highest efficiency area, it is not economical. Using change valve opening methods to adjust flow multi-purpose in flow adjusting range is not too much, and often need to adjust occasion.
(2) Change pump rotating speedm namely change pump characteristic curve
(3) External diameter of pump impeller also changes characteristic curve. Adopt two methods mentioned above can change pump curve. Using these methods to adjust flow within the certain scope and can ensure the pump working in efficiency zone, energy utilization is economical, but not convenient, flow adjusting range is also not large, so not widely application.
