Abstract:
A dynamic recirculation system for heating and storing emulsified fuel oil includes: a recirculative heater provided on a feed pipe for feeding emulsified fuel oil into a daily storage tank, and a feedback pipe connected to an outlet pipe of the tank for directing a returning oil streamflow to be heated and warmed by the recirculatvie heater at a predetermined optimum temperature for recirculating and storing the warm emulsified fuel oil for preventing overheating of the emulsified fuel oil and preventing separation of water from emulsified fuel oil, thereby maintaining a stable homogeneous emulsified fuel oil for a better combustion in a furnace or boiler.

Description:
BACKGROUND OF THE INVENTION 
     A conventional fuel oil such as heavy oil may be processed to become an emulsified fuel oil by adding water and emulsifying agent therein for saving fuel and reducing hazardous combustion exhaust gases. 
     As shown in FIG. 3, the emulsified fuel oil as stored in the storage tank T should be warmed by a heater such as a heating coil or a suction heater H provided in the tank T in order to maintain a proper viscosity and fluidity for the fuel oil which can thus be pumped to a burner Br of a furnace or boiler for combustion use. However, the emulsified fuel oil, contacting the heating coil or pipe of the heater H with high skin temperature on the pipe surface, may be overheated to cause separation S of water from the emulsified oil which was previously emulsified and well mixed, thereby deteriorating the emulsified fuel oil or even causing burning difficulty. 
     The present inventor has found the drawbacks of the conventional emulsified fuel oil storage system, and invented the present dynamic recirculation system for heating and storing emulsified fuel oil. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a dynamic recirculation system for heating and storing emulsified fuel oil including: a recirculative heater provided on a feed pipe for feeding emulsified fuel oil into a daily storage tank, and a feedback pipe connected to an outlet pipe of the tank for directing a returning oil streamflow to be heated and warmed by the recirculatvie heater at a predetermined optimum temperature for recirculating and storing the warm emulsified fuel oil for preventing overheating of the emulsified fuel oil and preventing separation of water from emulsified fuel oil, thereby maintaining a stable homogeneous emulsified fuel oil for a better combustion in a furnace or boiler. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a flow sheet showing the system of the present invention. 
     FIG. 2 shows the recirculative heater provided with a temperature controller in accordance with the present invention. 
     FIG. 3 shows a conventional fuel oil storage system. 
    
    
     DETAILED DESCRIPTION 
     As shown in FIG. 1, a heating and storage system for emulsified fuel oil of the present invention comprises: a delivery pipe  1  for delivering emulsified fuel oil (including water-in-oil type, oil-in-water type or multiple-phase microemulsified type) from a plant where the emulsified fuel oil (not shown) is made, an oil tank truck  2  having emulsified fuel oil loaded therein (having, for instance, transported from the plant of fuel oil), a daily storage tank  3  for storing the emulsified fuel oil O as fed by a charging pump  4  connectable with the delivery pipe  1  and the tank truck  2 , a recirculative heater  5  provided between the charging pump  4  and the storage tank  3  for dynamically recirculatively heating or warming emulsified fuel oil O as fed or returned into the tank  3  as illustrated, an outlet heater  6  provided at or in a lower portion of the storage tank  3  for heating outlet oil as input into the heater  6  through an outlet port  32  and having an outlet pipe  33  as output from the heater  6 , a burner-side pump  7  and a burner-side heater  8  are connected in between the outlet pipe  33  and a burner  9  of a combustion equipment (not shown) such as a furnace, a boiler, a combustion engine, etc. 
     The daily storage tank  3  is so designated because the storage tank should have a capacity for storing the emulsified fuel oil of 24-hour consumption as required by the combustion equipment or device (not shown). The delivery pipe is provided with a valve  11  thereon; while the tank truck  2  having an unloading hose  40 , formed with a valve  401  thereon, both pipe  11  and hose  40  being connected to a suction pipe  41  formed on a suction side of the charging pump  4  for feeding emulsified fuel oil O into the storage tank  3  as pumped by the charging pump  4 . 
     The charging pump  4  has a feed pipe  42  formed at a discharge side (end) of the pump  4  for pumping the emulsified fuel oil into the storage tank  3  through an inlet port  31  formed on an upper portion of the tank  3 . 
     The outlet pipe  33  includes a three-way (or tee) valve or joint  331  for connecting a feedback pipe  34  recirculatively connected to the suction pipe  41  of the charging pump  4  and for connecting an output pipe  71  connected to a suction side (end) of a burner-side pump  7  having a valve  711  formed on the output pipe  71 . 
     The feedback pipe  34  as branched from the outlet pipe  33  includes a first valve  341  adjacent to the valve or joint  331  and a second valve  35  near the suction pipe  41  for on-off control of a recirculative streamflow of oil which is returned to be dynamically recirculatively heated or warmed by the recirculative heater  5  and then be re-fed into the tank  3 . 
     The burner-side pump  7  will pump the warm emulsified fuel oil through a pipe  72  to be further heated by a burner-side heater  8  up to 120° C. (for example) by a heating medium  81  which may be a steam or electric coil, with the oil fed into the burner  9  to be atomized for combustion in the combustion equipment or device. 
     The outlet heater  6  may be a suction heater or other types of heaters, including a heating device  61  having an inlet  62  for entering a heating medium (such as steam) and an outlet  63  for discharging the heating medium (such as condensate). The heating device  61  may also be an electric heating device, not limited in the present invention. 
     The recirculative heater  5  includes a heating coil  51  submerged in a heating drum  50  for directing steam or other heating medium into the coil  51  through an inlet  52  for heating the emulsified fuel oil flowing through the heating drum  50  as pumped by the pump  4  and the pipe  42 . For instance, an emulsified fuel oil containing heavy oil with water may be heated to 40˜50° C. for maintaining a proper fluidity of the oil for a smooth delivery of the warm fuel oil for its final combustion use. The condensate of the heating medium may be discharged from an outlet  53  of the heater  5 . The heated oil from the heating drum  50  is then fed into the tank  3  through the feed pipe end  421  and inlet port  31  of the tank  3 . 
     The recirculative heater  5  is provided with a temperature controller T.C. especially as shown in FIG. 3 for maintaining a constant optimum temperature for warming the emulsified fuel oil, without overheating the oil and without dissociating the emulsified oil into oil and water. 
     For auxiliarily heating the fuel oil O as output from the tank  3 , the outlet heater  6  is thus provided for continuously heating the fuel oil which is finally fed into the burner  9  for combustion in a furnace, a boiler, a combustion engine, etc, 
     The heating coil  51  of the recirculative heater  5  may also be an electric heating coil  51  for heating the emulsified fuel oil. 
     Since the fuel oil is dynamically recirculatively heated by the heater  5  to shorten the contacting time between the oil and the heating device, and an optimum heating temperature has been properly controlled, the emulsified oil will not be dissociated or “broken” into oil and water due to local overheating. Meanwhile, the warm oil will maintain a proper viscosity and fluidity for a smooth delivery into the burner. 
     A preferred example of the present invention is described hereinafter. 
     EXAMPLE 
     In the recirculative heater  5 , the steam pressure of the heating coil  51  is set at 3.5 kilogram per square centimeter (gauge), and the steam temperature set at 147° C. The flow velocity of the emulsified oil through the heater  5  is gradually increased and the skin temperature on the metal surface of the heating coil  51  is gradually decreased. 
     When the temperature of the inlet oil (entering the heater  5 ) is controlled at 45° C. and while the temperature of the outlet oil is controlled at 55° C., the relationship between the oil flow velocity and the skin temperature on the metal surface of the heating coil is obtained as follows: 
     
       
         
               
               
               
             
           
               
                   
                   
               
               
                   
                 Velocity of fuel oil 
                 Skin temperature of heating coil 
               
               
                   
                   
               
             
             
               
                   
                 0.1 m/sec 
                 137.3° C. 
               
               
                   
                 0.5 m/sec 
                 133.7° C. 
               
               
                   
                 1.0 m/sec 
                 131.2° C. 
               
               
                   
                 2.0 m/sec 
                 128.3° C. 
               
               
                   
                 5.0 m/sec 
                 119.2° C. 
               
               
                   
                   
               
             
          
         
       
     
     From the data as above-mentioned, the skin temperature will be gradually decreased with respect to an increase of the oil velocity. Even though the skin temperature is reached at 100˜120° C., the emulsified fuel oil will not be “broken” (dissociated into oil and water) if the oil flow velocity through the heater  5  is properly controlled within 5˜10 meters/second, and the contacting time between the oil and the metallic heating coil is less than 40 seconds in accordance with the present invention. 
     The present invention discloses a “dynamic” recirculative heating method for dynamically warming the emulsified fuel oil at a shortened contacting time to prevent overheating and dissociation of the oil and to obtain a better viscosity and fluidity of the oil beneficial for the pumping delivery from the tank to a burner of a furnace or the like. The “dynamic” process of the present invention is superior to a “static” heating system as found in a conventional storage system for emulsified fuel oil. 
     The recirculative heater  5  of the present invention may be a heat-exchanger to allow a heating medium (steam) through the heating coil  51  to heat the recirculated oil through the heating drum  50 , through which the coil  51  is passed. Other models of heat exchangers including double-pipe may be provided in this invention for recirculative heating purpose. 
     The present invention may be modified by those skilled in the art without departing from the spirit and scope as claimed in the present invention.