Frac water heater and fuel oil heating system

Abstract

An accessory heat exchanger unit for heating the fuel oil used by the frac oil heater system of the invention prior to combustion. The accessory heat exchanger unit receives and distributes the fuel oil through a plurality of heat exchanger tubes prior to directing the oil to the combustion chamber. The unit also includes an inlet for receiving heated treatment fluid from the frac water heater system of the present invention. The heated treatment fluid passes over the plurality of heat exchanger tubes of the accessory heat exchanger unit prior to being directed to the outlet of the accessory heat exchanger unit. By heating the fuel oil prior to combustion, the accessory heat exchanger unit greatly improves the viscosity and flow rate of the fuel oil, thereby allowing cheaper, less cold-tolerant grades of fuel oil to be used in extreme cold climates with no degradation in the operation of the frac water heater system of the present invention.

I claim: 
     
         1 . An accessory fuel oil heating system for a frac-water heating system, comprising:
 a heat exchanger unit having a manifold for receiving and distributing fuel oil through a plurality of heat exchanger tubes prior to directing said fuel oil to the burners of the frac-water heating system for combustion, said heat exchanger unit having an inlet for receiving heated treatment fluid from the frac-water heating system and directing the heated treatment fluid over the plurality of heat exchanger tubes prior to directing the heated treatment fluid to an outlet of said heat exchanger unit.   
     
     
         2 . The accessory fuel oil heating system of  claim 1 , wherein the heat exchanger unit comprises a heat exchanger manifold assembly coaxially aligned with an outer housing unit. 
     
     
         3 . The accessory fuel oil heating system of  claim 2 , further comprising at least support bracket configured around the plurality of heat exchanger tubes, wherein the support bracket maintain the spacing and alignment of the heat exchanger tubes and prevent the heat exchanger tubes from contacting the outer housing unit. 
     
     
         4 . The accessory fuel oil heating system of  claim 2 , wherein the outer housing unit includes an inlet having a diameter almost twice as large as the diameter of the outlet. 
     
     
         5 . The accessory fuel oil heating system of  claim 1 , wherein the manifold includes a passageway which extends through the manifold for receiving the heated treatment fluid. 
     
     
         6 . The accessory fuel oil heating system of  claim 1 , wherein said manifold comprises an inlet chamber fluidly connected to an outlet chamber by the plurality of heat exchanger tubes. 
     
     
         7 . The accessory fuel oil heating system of  claim 6 , wherein the inlet chamber is fluidly connected to a fuel tank via a fuel pump and pressurized fuel line. 
     
     
         8 . The accessory fuel oil heating system of  claim 7 , wherein the pressurized fuel line includes an isolation valve and a by-pass valve for bypassing heat exchanger unit when not needed. 
     
     
         9 . The accessory fuel oil heating system of  claim 1 , further comprising a pressure relief valve configured downstream of the heat exchanger unit to allow excess heated fuel oil to be directed back into the fuel tank. 
     
     
         10 . The accessory fuel oil heating system of  claim 1 , wherein the plurality of heat exchanger tubes are U-shaped and each has a different length. 
     
     
         11 . The accessory fuel oil heating system of  claim 1 , wherein the inlet of said heat exchanger unit is fluidly connected to an outlet conduit of the frac-water heating system. 
     
     
         12 . The accessory fuel oil heating system of  claim 1 , wherein the outlet of said heat exchanger unit is fluidly connected to an outlet manifold of the frac-water heating system. 
     
     
         13 . The method for heating fuel oil prior to combustion in a frac-water heating system, comprising in combination:
 directing fuel oil to a manifold of a heat exchanger unit, wherein said manifold receives and distributes said fuel oil through a plurality of heat exchanger tubes prior to directing said fuel oil to the burners of the frac-water heating system for combustion,   supplying an inlet in the heat exchanger unit with heated treatment fluid from the frac-water heating system;   directing the heated treatment fluid over the plurality of heat exchanger tubes prior to directing the heated treatment fluid to an outlet of said heat exchanger unit.   
     
     
         14 . The method for heating fuel oil of  claim 13 , wherein the step of supplying the inlet of the heat exchanger with heated treatment fluid comprises fluidly connecting the inlet of the heat exchanger unit to an outlet conduit of the frac-water heating system. 
     
     
         15 . The method for heating fuel oil of  claim 13 , wherein the heated treatment fluid passes over the plurality of heat exchanger tubes in a single pass. 
     
     
         16 . The method for heating fuel oil of  claim 13 , wherein said manifold distributes the fuel oil through the plurality of heat exchanger tubes by receiving fuel oil in an inlet chamber that is fluidly connected to an outlet chamber by the plurality of heat exchanger tubes. 
     
     
         17 . The method for heating fuel oil of  claim 16 , wherein the step of directing fuel oil to the manifold of the heat exchanger unit comprises fluidly connecting the inlet chamber to a fuel tank via a fuel pump and pressurized fuel line. 
     
     
         18 . The method for heating fuel oil of  claim 17 , further comprising allowing excess heated fuel oil to be directed back into the fuel tank by configuring a pressure relief valve downstream of the heat exchanger unit. 
     
     
         19 . The method for heating fuel oil of  claim 13 , further comprising fluidly connecting the outlet of the heat exchanger unit to an outlet manifold of the frac-water heating system to direct heated treatment fluid to a wellbore application. 
     
     
         20 . The method for heating fuel oil of  claim 13 , wherein said treatment fluid is heated from 40° F. to 210° F. in ambient atmospheric temperatures below 25° F. while pumping treatment fluid through said heat exchanger unit at a volumetric flow rate ranging from 200-250 gpm.