Pressure pulse interaction management in a multiple pump system

Abstract

Methods which include operating a plurality of pumps fluidly coupled to a common fluid line, and modulating a pumping speed of at least one of the pumps to reduce an amplitude of a pressure fluctuation in the common fluid line, where the modulating comprises maintaining an average aggregate pumping rate of the plurality of pumps.

1 . A method comprising:
 operating a plurality of pumps fluidly coupled to a common fluid line;   modulating a pumping speed of at least one of the pumps to reduce an amplitude of a pressure fluctuation in the common fluid line, wherein the modulating comprises maintaining an average aggregate pumping rate of the plurality of pumps.   
     
     
         2 . The method of  claim 1 , wherein the modulating comprises a modulation behavior selected from the modulation behaviors consisting of:
 inducing a random pump rate fluctuation into at least one of the pumps;   inducing a scheduled pump rate fluctuation into at least one of the pumps;   inducing a random pump rate fluctuation into each of the pumps;   inducing a scheduled pump rate fluctuation comprising a pump offset schedule into each of the pumps, and further ensuring that each of the pumps operates at a distinct position in the pump offset schedule; and   inducing a pseudo-random pump rate fluctuation into at least one of the pumps.   
     
     
         3 . The method of  claim 1 , wherein the modulating is based on a random seed value for at least one of the pumps, the random seed value comprising at least one of a pump startup time and a time of a last command for the pump. 
     
     
         4 . The method of  claim 1 , wherein the maintaining an average aggregate pumping rate of the plurality of pumps comprises modulating the at least one pump such that a specified pumped volume occurs within a specified time period. 
     
     
         5 . The method of  claim 1 , wherein reducing the amplitude of the pressure fluctuation in the common fluid line comprises an amplitude reduction operation selected from the amplitude reduction operations consisting of:
 minimizing a maximum amplitude of pressure fluctuation for a range of frequencies of interest;   minimizing an aggregate area under pressure fluctuation pulses for a range of frequencies of interest;   ensuring that a maximum amplitude of pressure fluctuation for a range of frequencies of interest is below a specified energy threshold;   ensuring that an aggregate area under pressure fluctuation pulses for a range of frequencies of interest is below a specified energy threshold;   determining a beat frequency response between at least two of the pumps, and ensuring that:
 a maximum amplitude of the beat frequency response is below a threshold and/or minimized; or 
 an aggregate area of the beat frequency response is below a threshold and/or minimized. 
   
     
     
         6 . The method of  claim 1 , further comprising commanding at least two of the pumps to pump at a substantially similar nominal pump rate. 
     
     
         7 . The method of  claim 1 , further comprising operating at least one pump in all transmission gears and acquiring initial pressure pulsation data to determine resonance frequencies of the at least one pump. 
     
     
         8 . The method of  claim 7  wherein an operator utilizes the resonance frequencies determined in pump operation to avoid pump speeds which generate the resonant frequencies. 
     
     
         9 . The method of  claim 8  wherein the pump operation controlled by software. 
     
     
         10 . A method comprising:
 determining a first modulation definition comprising a plurality of modulation instructions, each modulation instruction corresponding to one of a plurality of pumps fluidly coupled to a common fluid line;   operating the pumps in response to the first modulation definition;   determining a pressure fluctuation profile and a first fitness function for the first modulation definition in response to the pressure fluctuation profile;   adjusting the first modulation definition to generate a second modulation definition;   operating the pumps in response to the second modulation definition;   determining the pressure fluctuation profile and a second fitness function for the second modulation definition in response to the pressure fluctuation profile; and   comparing the first fitness function and the second fitness function, and selecting one of the first modulation definition and the second modulation definition in response to the comparing.   
     
     
         11 . The method of  claim 10 , wherein the determining a first modulation definition comprises at least one operation selected from the operations consisting of:
 determining a stored modulation definition;   selecting a default modulation definition;   determining a modulation definition in response to a pump specific parameter selected from at least one of a pump identifier, a pump start time, and a pump last command time;   utilizing a modulation definition from a previous selection of the first modulation definition and second modulation definition;   accepting a user input modulation definition;   determining the modulation definition in response to user inputs; and   scaling a preliminary modulation definition in response to a designed pumping rate.   
     
     
         12 . The method of  claim 10 , wherein the adjusting comprises performing at least one adjusting operation selected from the adjusting operations consisting of:
 changing at least one of the modulation instructions, wherein the changing is random, pseudo-random, and/or scheduled;   testing at least one of the modulation instructions over a specified operating space; and   swapping at least a portion of one of the modulation instructions with another of the modulation instructions.   
     
     
         13 . The method of  claim 10 , further comprising determining a sensitivity of the fitness functions to at least one of the pumps. 
     
     
         14 . The method of  claim 13 , further comprising preferentially modifying the modulation instructions corresponding to a pump having a high sensitivity to the fitness functions. 
     
     
         15 . The method of  claim 10 , wherein determining the first fitness function comprises determining at least one of:
 a maximum amplitude of a pressure fluctuation for a range of frequencies of interest;   an aggregate area under pressure fluctuation pulses for a range of frequencies of interest;   a maximum amplitude of a beat frequency response between at least two of the pumps; and   an aggregate area of a beat frequency response between at least two of the pumps.   
     
     
         16 . A method comprising:
 operating a plurality of pumps fluidly coupled to a common fluid line;   interpreting a pumping rate of each of the plurality of pumps; and   adjusting the pumping rate of the plurality of pumps such that:
 a total pumping rate is maintained; and 
 no two adjacent pumps are pumping at the same rate. 
   
     
     
         17 . The method of  claim 16 , wherein the pumping rate comprises the rate of pressure pulse application from the pump to the common fluid line. 
     
     
         18 . The method of  claim 16 , wherein the adjusting the pumping rate of the plurality of pumps such that no two adjacent pumps are pumping at the same rate comprises adjusting the pumping rates according to at least one of:
 ensuring that the pumps differ in volumetric rate by at least 0.1 bpm;   ensuring that the pumps differ in plunger strokes per minute by at least 2%.   
     
     
         19 . The method of  claim 16 , wherein adjacent pumps comprise any two pumps having a shortest relative fluid path through the common fluid line. 
     
     
         20 . The method of  claim 16 , further comprising operating at least one pump in all transmission gears and acquiring initial pressure pulsation data to determine resonance frequencies of the at least one pump.