Pump delivery flow rate control apparatus

• US 5,213,477 A
• Filed: 04/11/1991
• Issued: 05/25/1993
• Est. Priority Date: 04/13/1990
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Ohbayashi, Takahiko, Watanabe, Michio
• Primary Examiner(s): Bertsch, Richard A.
• Assistant Examiner(s): Scheuermann, David W.
• Application Number:
  US07/684,171
• Time in Patent Office: 775 Days
• Field of Search: 417/2, 417/3, 417/4, 417/5, 417/6, 417/7, 417/20, 417/32
• US Class Current: 417/20
• CPC Class Codes: F04B 49/065 and making use of computers
• CPC Class Codes: F04D 15/0066 by changing the speed, e.g. of the driving engine
• CPC Class Codes: F04D 15/0088 Testing machines
• CPC Class Codes: F04D 29/688 especially adapted for liquid pumps

Abstract

A control apparatus for controlling a delivery flow rate of a pump pressure-feeding process liquid within a process pipe system is described. The control apparatus has detecting means for detecting available N.P.S.H. of a pump on the basis of a pressure and a temperature of the process liquid within the suction portion of the pump, and calculating means for calculating an allowable maximum flow rate of the pump so as to hold the relationship: available N.P.S.H. required N.P.S.H. The control apparatus also has outputting means for outputting a control signal to control the delivery flow rate of the pump on the basis of the smaller value, the allowable maximum flow rate or a required flow rate of the pump.

Claims

1. A control apparatus for controlling a delivery flow rate of a pump pressure-feeding processing liquid within a process pipe system comprising:

detecting means for detecting available N.P.S.H. of a pump on the basis of a pressure and a temperature of the process liquid within a suction portion of the pump;

calculating means for calculating an allowable maximum flow rate of the pump so as to maintain the relationship

space="preserve" listing-type="equation">available N.P.S.H.>

required N.P.S.H.; and

outputting means for outputting a control signal to control delivery flow rate of the pump on the basis of the smaller of the allowable maximum flow rate and a required flow rate of the pump;

wherein

the detecting means for detecting the available N.P.S.H. of the pump comprises a high-pressure chamber that transmits the pressure of a process liquid, a low pressure chamber that is held at a saturation vapor pressure corresponding to the temperature of the process liquid, and a sensor diaphragm which partitions the high-pressure chamber and the low-pressure chamber, the high-pressure chamber and the low-pressure chamber being separated from the process liquid by respective sealing diaphragms.

2. A control apparatus for controlling a delivery flow rate of a pump pressure-feeding processing liquid within a process pipe system comprising:

detecting means for detecting available N.P.S.H. of a pump on the basis of a pressure and a temperature of the process liquid within a suction portion of the pump;

calculating means for calculating an allowable maximum flow rate of the pump so as to maintain the relationship

space="preserve" listing-type="equation">available N.P.S.H.>

required N.P.S.H.; and

outputting means for outputting a control signal to control delivery flow rate of the pump on the basis of the smaller of the allowable maximum flow rate and a required flow rate of the pump;

wherein

the detecting means for detecting the available N.P.S.H. of the pump comprises a temperature/saturation pressure conversion portion that determines a saturation vapor pressure of the process liquid from the temperature of the process liquid, and a subtractor portion that calculates a differential pressure between the pressure of the process liquid and the saturation vapor pressure of the process liquid.

3. A control apparatus for controlling a delivery flow rate of a pump pressure-feeding process liquid within a process pipe system comprising:

detecting means for detecting available N.P.S.H. of a pump on the basis of a pressure and a temperature of the process liquid within the suction portion of the pump;

liquid inserting means for inserting a low-temperature process liquid into the process liquid on the suction side of the pump; and

outputting means for comparing the available N.P.S.H. determined by the detecting means and required N.P.S.H. of the pump and for outputting a control signal to the liquid inserting means in order to control an inserting amount of the liquid inserting means so as to hold the relationship

space="preserve" listing-type="equation">available N.P.S.H.>

required N.P.S.H.

4. A control apparatus for controlling a delivery flow rate of a pump pressure-feeding process liquid within a process pipe system comprising:

detecting means for detecting available N.P.S.H. of a pump on the basis of a pressure and a temperature of the process liquid within the suction portion of the pump;

liquid supply means for supplying a cooling liquid to a tank which temporarily stores the process liquid on the suction side of the pump and into which process vapor flows; and

outputting means for comparing the available N.P.S.H. determined by the detecting means and required N.P.S.H. of the pump and for outputting a control signal to the liquid supply means in order to control a supplying amount of the liquid supply means so as to hold the relationship

space="preserve" listing-type="equation">available N.P.S.H.>

required N.P.S.H.

5. A control apparatus for controlling a delivery flow rate of a pump pressure-feeding process liquid within a process pipe system comprising:

detecting means for detecting available N.P.S.H. of a pump on the basis of a pressure and a temperature of the process liquid within the suction portion of the pump;

calculating means for calculating an allowable maximum flow rate of the pump so as to hold the relationship

space="preserve" listing-type="equation">available N.P.S.H.>

required N.P.S.H.;

detecting means for detecting an abnormal sound of a pump by an acoustic detector portion disposed in the vicinity of a pump and a predetermined limit flow rate signal; and

outputting means for outputting a control signal to control the delivery flow rate of the pump on the basis of the smallest value, the allowable maximum flow rate, a required flow rate of the pump, or the predetermined flow rate.

6. A control apparatus for controlling a delivery flow rate of a pump pressure-feeding process liquid within a process pipe system having a speed control pump comprising:

detecting means for detecting required N.P.S.H. of a pump on the basis of a pressure and a temperature of the process liquid within the suction portion of the pump;

calculating means for calculating an allowable maximum flow rate of the pump so as to hold the relationship

space="preserve" listing-type="equation">available N.P.S.H.>

required N.P.S.H.; and

flow rate judging means for outputting a flow rate restriction signal to a delivery valve of the pump when it is judged that it is not possible to perform emergency speed control according to the allowable maximum flow rate.

7. A control apparatus for controlling a delivery flow rate of a pump pressure-feeding process liquid within a process pipe system comprising:

detecting means for detecting available N.P.S.H. of a pump on the basis of a pressure and a temperature of the process liquid within the suction portion of the pump;

vapor supply means for supplying high pressure process vapor to press the process liquid on the suction side of the pump; and

outputting means for comparing the available N.P.S.H. from the detecting means and required N.P.S.H. of the pump and for outputting a control signal to the vapor supply means in order to control a supplying amount of the vapor supply means so as to hold the relationship

space="preserve" listing-type="equation">available N.P.S.H.>

required N.P.S.H.

8. The control apparatus of claim 7, wherein a tank for holding the process liquid is provided on the upstream side of the pump, the vapor supply means being connected to the tank.