Feedback control optimization of counter-flow simultaneous heat and mass exchange

Patent metadata

Field	Value
Publication number	US-10239765-B2
Application number	US-201715401948-A
Country	US
Kind code	B2
Filing date	Jan 9, 2017
Priority date	Dec 18, 2013
Publication date	Mar 26, 2019
Grant date	Mar 26, 2019

Abstract

A counter-flow simultaneous heat and mass exchange device is operated by directing flows of two fluids into a heat and mass exchange device at initial mass flow rates where ideal changes in total enthalpy rates of the two fluids are unequal. At least one of the following state variables in the fluids is measured: temperature, pressure and concentration, which together define the thermodynamic state of the two fluid streams at the points of entry to and exit from the device. The flow rates of the fluids at the points of entry and/or exit to/from the device are measured; and the mass flow rate of at least one of the two fluids is changed such that the ideal change in total enthalpy rates of the two fluids through the device are brought closer to being equal.

First claim

What is claimed is:

1. A method of operating a counter-flow simultaneous heat and mass exchange device, the method comprising:
directing flows of two fluids into a heat and mass exchange device at initial mass flow rates where ideal changes in total enthalpy rates of the two fluids are unequal;
measuring at least one of the following state variables in the fluids: temperature, pressure and concentration, which together define the thermodynamic states of the two fluid streams at the points of entry to and exit from the device;
measuring the flow rates of the fluids at at least one of the following: (a) the points of entry to the heat and mass exchange device and (b) the points of exit from the heat and mass exchange device; and
changing the mass flow rate of at least one of the two fluids such that the ideal change in total enthalpy rates of the two fluids through the device are brought closer to being equal.

2. The method of claim 1 , wherein the heat and mass exchange device is a condenser that condenses a vapor from a humidified carrier gas.

3. The method of claim 2 , wherein the vapor is water.

4. The method of claim 1 , wherein the heat and mass exchange device is a humidifier that vaporizes a volatile component from a feed liquid.

5. The method of claim 4 , wherein the vapor is water.

6. The method of claim 5 , wherein the feed liquid is selected from at least one of flow-back water and produced water from oil or gas extraction.

7. The method of claim 1 , further comprising calculating a heat capacity ratio based on the measured state variable and the measured flow rates and changing the flow rate of at least one of the fluids as a function of the calculated heat capacity ratio.

8. The method of claim 7 , further comprising iteratively calculating the heat capacity ratio and changing the flow rate if the heat capacity ratio is not within a specified margin of error of 1.

9. A method of operating a network of at least two counter-flow simultaneous heat and mass exchange devices fluidically coupled with each other, the method comprising:
flowing at least two fluid streams in counter-flow through the heat and mass exchange devices at initial mass flow rates where ideal changes in total enthalpy rates of the two fluids are unequal;
measuring at least one of the following state variables in the fluid streams: temperature, pressure and concentration, which together define the thermodynamic states of all of the fluid streams at at least one of the following: (a) the points of entry to the heat and mass exchange devices and (b) the points of exit from the heat and mass exchange devices;
measuring the flow rates of the fluids at at least one of the following: (a) the points of entry to the heat and mass exchange devices and (b) the points of exit from the heat and mass exchange devices; and
changing the mass flow rate of at least one of the fluids such that the ideal change in total enthalpy rates of the two fluids through at least one of the at least two heat and mass exchange devices are brought closer to being equal.

10. The method of claim 9 , wherein the heat and mass exchange devices comprise a humidifier and a condenser, the method further comprising:
vaporizing a volatile component from a feed liquid in the humidifier;
transporting the vaporized volatile component with a carrier gas to the condenser; and
condensing the vaporized volatile component from the carrier gas in the condenser.

11. The method of claim 10 , wherein the volatile component is water.

12. The method of claim 11 , further comprising:
extracting at least one of the fluids (a) at an intermediate stage of the humidifier and injecting the extracted fluid into an intermediate stage of the condenser or (b) at an intermediate stage of the condenser and injecting the extracted fluid into an intermediate stage of the humidifier;
measuring at least one property selected from temperature, pressure and concentration of the extracted fluid as the extracted fluid is passed between the humidifier and condenser;
measuring the flow rate of the extracted fluid as the extracted fluid is passed between the humidifier and condenser.

13. The method of claim 12 , wherein at least one of the humidifier and the condenser comprises a plurality of humidification or condensing stages through which the fluids pass, and wherein the intermediate stage in at least one of the humidifier and condenser is positioned between humidification or condensing stages.

14. The method of claim 13 , wherein the humidification or condensing stages comprise bubble columns through which at least one of the fluids is bubbled.

15. The method of claim 11 , further comprising calculating a heat capacity ratio based on the measured state variable and the measured flow rates and changing the flow rate of at least one of the carrier gas and the feed liquid as a function of the calculated heat capacity ratio.

16. The method of claim 15 , further comprising iteratively calculating the heat capacity ratio and changing the flow rate of at least one of the feed liquid and the carrier gas if the heat capacity ratio is not within a specified margin of error of 1.

17. A method for operating a network of at least one counter-flow simultaneous heat and mass exchange device and at least one heat exchange device fluidically coupled with each other, the method comprising:
flowing at least two fluid streams in counter-flow through the heat and mass exchange device and through the heat exchange device, each fluid stream entering at a respective point of entry and exiting at a respective point of exit of each, at initial mass flow rates where ideal changes in total enthalpy rates of the fluids are unequal, wherein the fluid streams comprise:
(a) a feed fluid stream fed through the heat exchange device, wherein the feed fluid stream or at least a partial product of the feed fluid stream is fed from the heat exchange device to and through the heat and mass exchange device, and
(b) a counter-flow fluid stream fed through the heat and mass exchange device, wherein the counter-flow fluid stream or at least a partial product of the counter-flow fluid stream is fed to and through the heat exchanger in counter-flow to the feed fluid flowing through the first side of heat exchange device and to the feed fluid or the partial product of the feed fluid flowing through the heat and mass exchange device;
measuring at least one of the following state variables: temperature, pressure and concentration, which together define the thermodynamic states of all of the different fluid streams at the points of entry to and exit from the heat and mass exchange device and the heat exchange device;
measuring the flow rates of the fluid streams at the points of entry to and/or exit from the heat and mass exchange device and the heat exchange device; and
changing the mass flow rate of at least one of the fluid streams such that the ideal change in total enthalpy rates of the two fluid streams through the heat and mass exchange device and the heat exchange device are brought closer to being equal.

18. The method of claim 17 , wherein the heat and mass exchange device is a humidifier or condenser.

19. The method of claim 18 , wherein at least one of the fluid streams comprises water that is (a) vaporized from the feed fluid stream in the humidifier or (b) condensed from the partial product of the feed fluid stream in the condenser.

Assignees

• Gradiant Corp

Inventors

• Govindan Prakash Narayan
• St John Maximus G
• Chehayeb Karim M
• Lam Steven

Classifications

• F28F2250/104

  with parallel flow · CPC title

• F28C1/02

  with counter-current only · CPC title

• F28B1/02

  using water or other liquid as the cooling medium · CPC title

• C02F1/043

  Details · CPC title

• C02F1/008 Primary

  Control or steering systems not provided for elsewhere in subclass C02F · CPC title