Integrated Impressed Current Cathodic Protection for Wet Crude Handling Vessels

Abstract

A cathodic protection system includes a vessel for containing a fluid or a mixture of fluids, a plurality of anodes positioned inside the vessel, an encapsulant encapsulating the plurality of anodes, the encapsulant being a wax repellant material that is sufficiently porous to allow ions to pass therethrough, and an impressed current source electrically connected to each of the anodes and the vessel. The impressed current source produces a continuous high current output, and the vessel acts as a cathode when current is applied from the impressed current source. The anodes are monitored and controlled from outside of the vessel using one or more adjustable resistors, which are installed in a junction box located either inside or outside the vessel. The resistors are configured to adjust the individual anode current output based upon a predetermined cathodic protection criteria.

1 . A cathodic protection system, the cathodic protection system comprising:
 a vessel for containing a fluid or a mixture of fluids;   a plurality of anodes positioned inside the vessel;   an encapsulant encapsulating the plurality of anodes, the encapsulant being a wax repellant material that is sufficiently porous to allow ions to pass therethrough; and   an impressed current source electrically connected to each of the anodes and the vessel, wherein the impressed current source produces a continuous high current output, the vessel being a cathode when current is applied from the impressed current source.   
     
     
         2 . The system according to  claim 1 , wherein each of the anodes are monitored and controlled from outside of the vessel using one or more adjustable resistors. 
     
     
         3 . The system according to  claim 1 , wherein the one or more adjustable resistors are installed in a junction box located either inside or outside the vessel, wherein the resistors are configured to adjust the individual anode current output based upon a predetermined cathodic protection criteria. 
     
     
         4 . The system according to  claim 1 , further comprising:
 a positive terminal connecting a transformer-rectifier to the impressed current source; and   a negative terminal connecting the transformer-rectifier to the vessel.   
     
     
         5 . The system according to  claim 1 , further comprising:
 one or more nozzles fitted to the inside and/or outside of the vessel, wherein each of the nozzles is coupled to a plurality of the anodes.   
     
     
         6 . The system according to  claim 1 , further comprising at least five anodes positioned inside the vessel. 
     
     
         7 . The system according to  claim 1 , further comprising:
 a plurality of coalescers installed inside the vessel, wherein the plurality of coalescers are configured to separate oil from water.   
     
     
         8 . The system according to  claim 1 , wherein the coalescers comprise at least one material selected from the group consisting of polypropylene, polyvinyl chloride, chlorinated polyvinyl chloride, acrylic, aluminum, marine aluminum, 304/304L stainless steel, 316/316L stainless steel, carbon steel, and composite. 
     
     
         9 . The system according to  claim 1 , further comprising:
 a plurality of cables coupled to the coalescers and terminated outside the vessel, wherein the plurality of cables are used to monitor and control the corresponding coalescers from outside the vessel.   
     
     
         10 . The system according to  claim 4 , further comprising:
 a galvanic anode monitoring system configured to monitor the vessel potential when the anodes are disconnected from the vessel.   
     
     
         11 . The system according to  claim 10 , wherein the galvanic anode monitoring system is coupled to the transformer-rectifier to adjust the individual anode current output based upon a predetermined cathodic protection criteria. 
     
     
         12 . The system according to  claim 1 , wherein the anodes comprise at least one material selected from the group consisting of mixed metal oxide (“MMO”), platinized nickel (“PtNi”), platinized cobalt (“PtCo”), platinized niobium (“PtNb”), platinized titanium (“PtTi”), high temperature zinc, and high silicon cast iron. 
     
     
         13 . The system according to  claim 6 , further comprising:
 a plurality of MMO anodes and a plurality of high silicon cast iron anodes.   
     
     
         14 . The system according to  claim 1 , wherein the encapsulant is spaced apart from the vessel. 
     
     
         15 . The system according to  claim 1 , wherein the encapsulant is hydrophilic. 
     
     
         16 . The system according to  claim 1 , wherein the encapsulant is fluid permeable. 
     
     
         17 . The system according to  claim 1 , wherein the encapsulant is acid resistant. 
     
     
         18 . The system according to  claim 1 , wherein the encapsulant is resistant to H 2 S. 
     
     
         19 . The system according to  claim 1 , wherein the encapsulant is cementitious. 
     
     
         20 . The system according to  claim 1 , wherein the encapsulant comprises cement and carbon. 
     
     
         21 . The system according to  claim 1 , wherein the encapsulant comprises pores, the pores having a diameter in the range of 100 μm to 650 μm. 
     
     
         22 . The system according to  claim 1 , wherein the encapsulant comprises grains having a resin coating, the grains comprising a plurality of crystalline compounds including mullite and corundum. 
     
     
         23 . The system according to  claim 1 , wherein the vessel comprises a wet crude handling vessel, wherein the anodes are positioned inside the wet crude handling vessel. 
     
     
         24 . An anode system, the anode system comprising:
 a vessel having an interior surface;   a first phase fluid and a second phase fluid contained within the vessel;   a plurality of anodes spaced apart from each other, each of the plurality of anodes being connected to the interior surface of the vessel and at least a portion of the anodes being positioned within the second phase fluid;   an impressed current source electrically connected to each of the anodes and the vessel, wherein the impressed current source produces a continuous high current output, the vessel being a cathode when current is applied from the impressed current source; and   an encapsulant encapsulating the anodes, the encapsulant being a wax repellant material operable to transmit ions therethrough.   
     
     
         25 . The system according to  claim 24 , wherein the first phase comprises crude oil and the second phase comprises water. 
     
     
         26 . The system according to  claim 24 , wherein the encapsulant is spaced apart from the vessel. 
     
     
         27 . The system according to  claim 24 , wherein each of the anodes are monitored and controlled from outside of the vessel using one or more adjustable resistors. 
     
     
         28 . The system according to  claim 27 , wherein the one or more adjustable resistors are installed in a junction box located either inside or outside the vessel, wherein the resistors are configured to adjust the individual anode current output based upon a predetermined cathodic protection criteria. 
     
     
         29 . The system according to  claim 24 , further comprising:
 one or more nozzles fitted to the inside and/or outside of the vessel, wherein each of the nozzles is coupled to a plurality of the anodes.   
     
     
         30 . The system according to  claim 24 , wherein the anodes comprise at least one material selected from the group consisting of mixed metal oxide (“MMO”), platinized nickel (“PtNi”), platinized cobalt (“PtCo”), platinized niobium (“PtNb”), platinized titanium (“PtTi”), high temperature zinc, and high silicon cast iron. 
     
     
         31 . The system according to  claim 24 , further comprising:
 a plurality of MMO anodes and a plurality of high silicon cast iron anodes.   
     
     
         32 . The system according to  claim 24 , wherein the encapsulant comprises grains having a resin coating, the grains comprising a plurality of crystalline compounds including mullite and corundum. 
     
     
         33 . The system according to  claim 24 , wherein the vessel comprises a wet crude handling vessel, wherein the anodes are positioned inside the wet crude handling vessel. 
     
     
         34 . A method of providing corrosion protection to a vessel, the method comprising:
 positioning a plurality of anodes inside the vessel, wherein the plurality of anodes are encapsulated with a wax repellant material that is sufficiently porous to allow ions to pass therethrough; and   electrically connecting an impressed current source to each of the anodes and the vessel, wherein the impressed current source produces a continuous high current output, the vessel being a cathode when current is applied from the impressed current source.   
     
     
         35 . The method according to  claim 34 , further comprising:
 electrically connecting one or more adjustable resistors to each of the anodes for monitoring and controlling the anodes from outside of the vessel.   
     
     
         36 . The method according to  claim 35 , further comprising:
 installing the one or more adjustable resistors in a junction box located either inside or outside the vessel, wherein the resistors are configured to adjust the individual anode current output based upon a predetermined cathodic protection criteria.   
     
     
         37 . The method according to  claim 34 , further comprising:
 installing one or more nozzles inside and/or outside of the vessel; and   connecting each of the nozzles to a plurality of the anodes.   
     
     
         38 . The method according to  claim 34 , wherein the anodes comprise at least one material selected from the group consisting of mixed metal oxide (“MMO”), platinized nickel (“PtNi”), platinized cobalt (“PtCo”), platinized niobium (“PtNb”), platinized titanium (“PtTi”), high temperature zinc, and high silicon cast iron. 
     
     
         39 . The method according to  claim 34 , wherein the wax repellant material comprises grains having a resin coating, the grains comprising a plurality of crystalline compounds including mullite and corundum. 
     
     
         40 . The method according to  claim 34 , further comprising:
 applying a double layer of the wax repellant material within a radius of half a meter around the anodes.