Methods and systems of cooling process plant water

Abstract

The present disclosure provides methods and system for the cooling of process plant water. A system can include a first heat exchanger for exchanging heat between a first process water stream and a refrigerant; a multiphase pump, coupled to the first heat exchanger, to increase the pressure of the refrigerant; a second heat exchanger, coupled to the multiphase pump and the first heat exchanger, for exchanging heat between a second process water stream and the refrigerant; a first expansion valve, coupled to the second heat exchanger, for lowering the temperature of the refrigerant; a vapor-liquid separator, coupled to the first expansion valve and the multiphase pump, for separating the liquid and vapor phases of the refrigerant; and a second expansion valve, coupled to the vapor-liquid separator and the first heat exchanger, for lowering the temperature of the liquid phase of the refrigerant.

1 . A method for cooling process plant water, the method comprising:
 (a) exchanging heat between a first process water stream and a liquid refrigerant to lower the temperature of the process water stream, thereby generating a partially vaporized refrigerant that comprises a vapor phase and a liquid phase;   (b) increasing the pressure and/or temperature of the partially vaporized refrigerant to generate a pressurized partially vaporized refrigerant;   (c) exchanging heat between a second process water stream and the pressurized partially vaporized refrigerant to lower the temperature of the pressurized partially vaporized refrigerant and/or increase the temperature of the second process water stream;   (d) lowering the pressure and/or temperature of the pressurized partially vaporized refrigerant and separating out at least a portion of the liquid phase from the partially vaporized refrigerant to generate a liquid refrigerant; and   (e) lowering the temperature of the liquid refrigerant to generate a cooled liquid refrigerant suitable for exchanging heat with the first process water stream.   
     
     
         2 . The method of  claim 1 , wherein the lowering the pressure and/or temperature of the partially vaporized refrigerant portion of step (d) occurs in a first expansion valve. 
     
     
         3 . The method of  claim 1 , wherein the lowering the temperature of the liquid refrigerant of step (e) occurs within a second expansion valve. 
     
     
         4 . The method of  claim 1 , wherein the liquid refrigerant comprises a refrigerant having a viscosity greater than or equal to about 0.1 cP at a temperature of about 0° C. 
     
     
         5 . The method of  claim 1 , wherein the liquid refrigerant comprises a refrigerant having a boiling point temperature from about −10° C. to about −50° C. 
     
     
         6 . The method of  claim 1 , wherein the liquid refrigerant comprises a refrigerant selected from the group consisting of R134A, R404A, R407C, R125, and R410A. 
     
     
         7 . The method of  claim 1 , wherein the partially vaporized refrigerant comprises a refrigerant having a vapor phase of about 30% to about 50%. 
     
     
         8 . The method of  claim 1 , wherein the increasing the pressure and/or temperature of the partially vaporized refrigerant occurs within a multiphase pump. 
     
     
         9 . The method of  claim 1 , further comprising transferring the cooled process water to one or more process plants. 
     
     
         10 . The method of  claim 1 , wherein:
 step (a) further comprises exchanging heat between the first process water stream and the liquid refrigerant within a first heat exchanger to lower the temperature of the first process water stream, thereby generating the partially vaporized refrigerant, which comprises the vapor phase and the liquid phase, upon the exchange of heat with the first process water stream;   step (b) further comprises increasing the pressure of the partially vaporized refrigerant and transferring at least a portion of the partially vaporized refrigerant to a second heat exchanger;   step (c) further comprises exchanging heat between a second process water stream and the partially vaporized refrigerant portion within the second heat exchanger to decrease the temperature of the refrigerant;   step (d) further comprises lowering the pressure and/or temperature of the partially vaporized refrigerant portion and transferring the partially vaporized refrigerant portion to a vapor-liquid separator to separate the liquid phase from the vapor phase thereof, thereby generating the liquid refrigerant; and   step (e) further comprises lowering the temperature of the liquid refrigerant and transferring at least a portion of the refrigerant to the first heat exchanger to exchange heat with the first process water stream.   
     
     
         11 . The method of  claim 10 , wherein the increasing pressure of the partially vaporized refrigerant of step (b) occurs in a multiphase pump. 
     
     
         12 . The method of  claim 10 , further comprising: (f) transferring at least a portion of the vapor phase of the refrigerant from the separator to the multiphase pump. 
     
     
         13 . The method of  claim 10 , wherein the vapor-liquid separator comprises a flash drum. 
     
     
         14 . A method for cooling process plant water, the method comprising:
 (a) exchanging heat between a first process water stream and a liquid refrigerant within a first heat exchanger to lower the temperature of the process water stream, thereby partially vaporizing the refrigerant upon the exchange of heat with the first process water stream;   (b) transferring the first process water from the first heat exchanger to one or more process plants;   (c) transferring the partially vaporized refrigerant from the first heat exchanger to a multiphase pump to increase the pressure of the partially vaporized refrigerant;   (d) transferring the partially vaporized refrigerant from the multiphase pump to a second heat exchanger;   (e) exchanging heat between a second process water stream and the partially vaporized refrigerant within the second heat exchanger to decrease the temperature of the refrigerant;   (f) transferring the second process water stream from the second heat exchanger to become the first process water stream entering the first heat exchanger;   (g) transferring the partially vaporized refrigerant from the second heat exchanger to a first expansion valve to lower the pressure and/or temperature of the refrigerant;   (h) transferring the partially vaporized refrigerant from the first expansion valve to a vapor-liquid separator to separate the liquid phase from the vapor phase thereof, thereby generating a liquid refrigerant;   (i) transferring the liquid refrigerant from the vapor-liquid separator to a second expansion valve to lower the temperature of the liquid refrigerant; and   (j) transferring the refrigerant from the second expansion valve to the first heat exchanger to exchange heat with the first process water stream.   
     
     
         15 . A system for exchanging heat between a first process water stream and a second process water stream with a refrigerant, the system comprising:
 (a) a first heat exchanger for exchanging heat between the first process water stream and the refrigerant and thereby generate a partially vaporized refrigerant having liquid and vapor phases;   (b) a multiphase pump, coupled to the first heat exchanger, to increase the partially vaporized refrigerant pressure;   (c) a second heat exchanger, coupled to the multiphase pump and the first heat exchanger, for exchanging heat between the second process water stream and the partially vaporized refrigerant;   (d) a first expansion valve, coupled to the second heat exchanger, for lowering the lowering the pressure and/or temperature of the partially vaporized refrigerant temperature;   (e) a vapor-liquid separator, coupled to the first expansion valve and the multiphase pump, for separating the liquid and the vapor phases of the partially vaporized refrigerant; and   (f) a second expansion valve, coupled to the vapor-liquid separator and the first heat exchanger, for lowering the liquid phase temperature of the refrigerant.   
     
     
         16 . The system of  claim 15 , wherein the vapor-liquid separator comprises a flash drum. 
     
     
         17 . The method of  claim 7 , wherein the lowering the pressure and/or temperature of the partially vaporized refrigerant portion of step (d) occurs in a first expansion valve. 
     
     
         18 . The method of  claim 4 , wherein the lowering the pressure and/or temperature of the partially vaporized refrigerant portion of step (d) occurs in a first expansion valve. 
     
     
         19 . The method of  claim 5 , wherein the lowering the pressure and/or temperature of the partially vaporized refrigerant portion of step (d) occurs in a first expansion valve. 
     
     
         20 . The method of  claim 6 , wherein the lowering the pressure and/or temperature of the partially vaporized refrigerant portion of step (d) occurs in a first expansion valve.