US2008073063A1PendingUtilityA1

Reduction of fouling in heat exchangers

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Assignee: EXXONMOBIL RES & ENG COPriority: Jun 23, 2006Filed: May 24, 2007Published: Mar 27, 2008
Est. expiryJun 23, 2026(expired)· nominal 20-yr term from priority
Inventors:Leroy ClavennaIan A. CodyAshley CooperSteve ColgroveHugh HuffmanJulio Danin LoboLimin SongH. Alan WolfGlen B. BronsGeorge A. LutzMohsen S. Yeganeh
F28D 2021/0059B01J 19/1825F28G 7/00B01J 2219/00247F28F 19/02B01J 2219/0245B01J 2219/0231B01J 19/02C10G 75/00F28F 2245/04B01J 2219/00094B01J 19/185
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Claims

Abstract

A method for reducing the formation of deposits on the inner walls of a tubular heat exchanger through which a petroleum-based liquid is flowing comprises applying one of fluid pressure pulsations to the liquid flowing through the tubes of the exchanger and vibration to the heat exchanger to effect a reduction of the viscous boundary layer adjacent the inner walls of the tubular heat exchange surfaces. Reduction of the viscous boundary layer at the tube walls not only reduces the incidence of fouling with its consequential beneficial effect on equipment life but it also has the desirable effect of promoting heat transfer from the tube wall to the liquid in the tubes. Fouling and corrosion are further reduced by the use of a coating on the inner wall surfaces of the exchanger tubes.

Claims

exact text as granted — not AI-modified
1 . A method for reducing the formation of deposits on walls of tubes in a heat exchanger through which a petroleum-based liquid is flowing, comprising: 
 applying one of fluid pressure pulsations to the liquid flowing through the tubes of the exchanger and vibration to the heat exchanger, wherein the wall contacting the liquid having an adherent fouling resistant coating having a surface energy of not more than 50 mJ/m 2 .    
   
   
       2 . A method according to  claim 1 , wherein mechanical vibration is applied to the heat exchanger.  
   
   
       3 . A method according to  claim 1 , wherein fluid pulsation pulsations area applied to the liquid flowing through the tubes.  
   
   
       4 . A method according to  claim 3 , wherein the fluid pressure pulsations are applied at a frequency in the range of 0.1 Hz to 20 kHz.  
   
   
       5 . A method according to  claim 3 , wherein the amplitude of the pulsations as measured by the incremental flow rate through the heat exchange tubes is in the range from about 10 −6  of the normal heat exchanger flow rate to about an order of the normal heat exchanger flow rate.  
   
   
       6 . A method according to  claim 5 , wherein the pulsations are applied at a frequency in the range from 0.1 to 10 kHz and the amplitude of the pulsation as measured by the incremental flow rate through the heat exchange tubes is in the range of about 10 −2  of the normal heat exchanger flow rate to about the order of the normal heat exchanger flow rate.  
   
   
       7 . A method according to  claim 5 , wherein the pulsations are applied at a frequency in the range from 10 to 20 kHz and the amplitude of the pulsation as measured by the incremental flow rate through the heat exchange tubes is in the range of about 10 −6  of the normal heat exchanger flow rate to about 0.1 of the order of the normal heat exchanger flow rate.  
   
   
       8 . A method according to  claim 1 , wherein the adherent fouling resistant coating on the wall of the tubes comprises: 
 a layer of organometallic molecules having a thickness of 1 to 10 molecular layers, wherein the layer will not undergo substantial decomposition at temperatures up to 450° C., and wherein the layer has a surface energy lower than 50 millijoule/m 2 .    
   
   
       9 . A method according to  claim 8 , wherein the layer of organometallic molecules is deposited on 80 to 100% of the inner wall surface.  
   
   
       10 . A method according to  claim 8 , wherein the metal in the organometallic compound is silicon.  
   
   
       11 . A method according to  claim 8 , wherein the organo moiety in the organometallic compound is a hydrocarbyl group from 1 to 30 carbon atoms.  
   
   
       12 . A method according to  claim 11 , wherein the hydrocarbyl group is aliphatic or aromatic and is substituted with at least one functional group.  
   
   
       13 . A method according to  claim 8 , wherein the organometallic compound is an alkoxy silane, silane, silazone or phenyl siloxane.  
   
   
       14 . A method according to  claim 13 , wherein the organometallic compound is hexamethyldisiloxane.  
   
   
       15 . A method according to  claim 8 , wherein the surface energy of the coating is between 18 and 50 mJ/m 2 .  
   
   
       16 . A method according to  claim 8 , wherein the coating has a surface with a water contact angle from 95° to 160°.  
   
   
       17 . A method according to  claim 16 , wherein the water contact angle is from 110° to 150°.  
   
   
       18 . A method according to  claim 16 , wherein the water contact angle is from 130° to 160°.  
   
   
       19 . A method according to  claim 8 , wherein mechanical vibration is applied to the heat exchanger.  
   
   
       20 . A method according to  claim 8 , wherein fluid pressure pulsations are applied to the liquid flowing through the tubes.  
   
   
       21 . A method according to  claim 20 , wherein the fluid pressure pulsations are applied at a frequency in the range of 0.1 Hz to 20 kHz.  
   
   
       22 . A method according to  claim 20 , wherein the amplitude of the pulsations as measured by the incremental flow rate through the heat exchange tubes is in the range from about 10 −6  of the normal heat exchanger flow rate to about an order of the normal heat exchanger flow rate.  
   
   
       23 . A method according to  claim 22 , wherein the pulsations are applied at a frequency in the range from 0.1 to 10 kHz and the amplitude of the pulsation as measured by the incremental flow rate through the heat exchange tubes is in the range of about 10 −2  of the normal heat exchanger flow rate to about the order of the normal heat exchanger flow rate.  
   
   
       24 . A method according to  claim 22 , wherein the pulsations are applied at a frequency in the range from 10 to 20 kHz and the amplitude of the pulsation as measured by the incremental flow rate through the heat exchange tubes is in the range of about 10 −6  of the normal heat exchanger flow rate to about 0.1 of the order of the normal heat exchanger flow rate.  
   
   
       25 . A heat exchanger for effecting heat exchange between a petroleum-based liquid and a heat exchange medium, comprising: 
 a housing having an interior;    a plurality of heat exchange tubes having a hollow interior passage for the passage of one of the petroleum-based liquid and the heat exchange medium therethrough, wherein each tube having an interior surface and an exterior surface;    an adherent fouling resistant coating on one at least one of the interior surface and the exterior surface, wherein the coating having a surface energy of not more than 50 mJ/m 2 ; and    one of fluid pressure pulsation generating device and a vibration generating device,    wherein the fluid pressure pulsation generating device applying fluid pressure pulsations to the petroleum-based liquid,    wherein the vibration generating device applying mechanical vibration to housing and the plurality of tubes.    
   
   
       26 . The heat exchanger according to  claim 25 , wherein the heat exchanger includes a fluid pressure pulsation generating device, wherein the device generating fluid pressure pulsations are generated at a frequency in the range of 0.1 Hz to 20 kHz.  
   
   
       27 . The heat exchanger according to  claim 25 , wherein the adherent fouling resistant coating comprises: 
 a layer of organometallic molecules having a thickness of 1 to 10 molecular layers, wherein the layer will not undergo substantial decomposition at temperatures up to 450° C., and wherein the layer has a surface energy lower than 50 millijoule/m 2 .    
   
   
       28 . The heat exchanger according to  claim 26 , wherein the layer of organometallic molecules is deposited on 80 to 100% of the inner wall surface.  
   
   
       29 . The heat exchanger according to  claim 26 , wherein the metal in the organometallic compound is silicon.  
   
   
       30 . The heat exchanger according to  claim 26 , wherein the organo moiety in the organometallic compound is a hydrocarbyl group from 1 to 30 carbon atoms.  
   
   
       31 . The heat exchanger according to  claim 30 , wherein the hydrocarbyl group is aliphatic or aromatic and is substituted with at least one functional group.  
   
   
       32 . The heat exchanger according to  claim 26 , wherein the organometallic compound is an alkoxy silane, silane, silazone or phenyl siloxane.  
   
   
       33 . The heat exchanger according to  claim 26 , wherein the organometallic compound is hexamethyldisiloxane.  
   
   
       34 . The heat exchanger according to  claim 25 , wherein the surface energy of the coating is between 18 and 50 mJ/m 2 .  
   
   
       35 . The heat exchanger according to  claim 25 , wherein the coating has a surface with a water contact angle from 95° to 160°.  
   
   
       36 . The heat exchanger according to  claim 35 , wherein the water contact angle is from 110° to 150°.  
   
   
       37 . The heat exchanger according to  claim 35 , wherein the water contact angle is from 130° to 160°.

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