Hydrodynamics to limit boiler fouling

Abstract

Methods and systems relate to generating steam from water that may be recycled in thermal oil recovery processes and is heated in tubes having non-obtrusive features to limit fouling formation. The tubes may include jets to generate enhanced flow mixing along an inner wall of the tubes in order to increase heat transfer and disrupt bubble nucleation. Employing the tubes with the inner wall having an average surface roughness of less than one micron may further facilitate disruption of the bubble nucleation.

1 . A method of generating steam for oil production, comprising:
 passing a first quantity of water through a tube of a boiler;   heating the water in the tube by heat transfer across the tube to a temperature for boiling nucleation; and   injecting a second quantity of the water jetted at multiple locations through a wall of the tube to induce enhanced flow mixing inside the tube along where the heating of the water occurs.   
     
     
         2 . The method according to  claim 1 , wherein the second quantity of the water is jetted aligned with flow through a length of the tube. 
     
     
         3 . The method according to  claim 1 , wherein the multiple locations are spaced along a length of the tube. 
     
     
         4 . The method according to  claim 1 , wherein the multiple locations are spaced along a length of the tube and are circumferentially dispersed around the tube. 
     
     
         5 . The method according to  claim 1 , wherein the second quantity of the water is jetted tangential to flow through a length of the tube. 
     
     
         6 . The method according to  claim 1 , wherein the second quantity of the water is injected into the tube without restricting an internal diameter of the tube. 
     
     
         7 . The method according to  claim 1 , further comprising polishing an inside of the tube to have an average surface roughness between 0.2 to 0.1 microns. 
     
     
         8 . The method according to  claim 1 , further comprising one of acid treating and coating an inside of the tube to provide an internal average surface roughness less than 1.0 micron. 
     
     
         9 . The method according to  claim 1 , further comprising fluctuating pressure of the second quantity of the water injected through the wall to contribute to the flow mixing. 
     
     
         10 . The method according to  claim 1 , further comprising adding at least one of a fouling inhibitor chemical agent and a polishing material to the second quantity of the water injected through the wall of the tube. 
     
     
         11 . The method according to  claim 1 , further comprising injecting steam produced from the water that is heated into an injection well and recovering condensate that is recycled to resupply the water to the tube. 
     
     
         12 . The method according to  claim 1 , wherein the heating occurs in an economizer section of a steam generator to increase temperature of the water that then passes to a radiant section of the steam generator to produce the steam. 
     
     
         13 . A steam generating system for oil production, comprising:
 an economizer section having a tube through which water is passed from a first pump and heated by heat exchange across the tube with flue gases;   multiple jets disposed along the tube to direct water into the tube from a second pump operated at a higher pressure than the first pump to create enhanced flow mixing inside the tube; and   a radiant section coupled to receive the water heated in the economizer section and further increase temperature of the water to produce steam.   
     
     
         14 . The system according to  claim 13 , wherein the jets are spaced along a length of the tube and are circumferentially dispersed around the tube. 
     
     
         15 . The system according to  claim 13 , wherein the jets are disposed to introduce the water from the second pump tangential to flow through a length of the tube. 
     
     
         16 . The system according to  claim 13 , wherein the tube has an internal average surface roughness less than 1.0 micron. 
     
     
         17 . The system according to  claim 13 , further comprising an injection well coupled with an output of the radiant section for conveying the steam into a formation to facilitate the oil production. 
     
     
         18 . A method of generating steam for oil production, comprising:
 increasing temperature of water flowing through a tube in a first section of a steam generator by heat transfer from flue gases across the tube, wherein at least one fouling mitigation feature is utilized during the increasing of the temperature and is selected from the tube having an internal average surface roughness less than 1.0 micron and injecting additional water at multiple locations into the water flowing through the tube to create enhanced flow mixing; and   vaporizing at least some of the water that is preheated in the first section of the steam generator to produce the steam in a second section of the steam generator by radiant heat transfer from combustion of a fuel into the flue gases.   
     
     
         19 . The method according to  claim 18 , further comprising injecting the steam into an injection well and recovering condensate that is recycled to resupply the water to the steam generator. 
     
     
         20 . The method according to  claim 18 , further comprising injecting the steam into a horizontal injection well and resupplying the water to the steam generator from condensate recovered in a horizontal production well disposed below the injection well.