Steam Generator

Abstract

A boiler includes a vessel having vertically-extensive walls defining multiple vertically-extensive channels. The vessel includes a liquid supply connection communicating with liquid inlets adjacent a lower end of each of the channels and a vapor discharge communicating with liquid outlets adjacent the upper end of each of the channels. The boiler also includes a set of electrodes positioned within the channels, with some of the electrodes in each channel being located at different elevations. An electrical power supply of the boiler has at least two poles and is operable to supply different electrical potentials to the different poles. A circuit is operable to selectively connect the electrodes to and selectively disconnect electrodes from the poles in multiple different connection schemes, each of which involves electrical current flowing between the connected electrodes along a current path through liquid in at least one of the channels.

1 . A boiler comprising:
 (a) a structure including vertically-extensive walls defining a plurality of vertically-extensive channels each having a lower end and an upper end, each channel having an inlet adjacent the lower end thereof and an outlet adjacent the upper end thereof, the structure including a liquid supply connection communicating with the liquid inlets of the channels and a vapor discharge communicating with the outlets of the channels;   (b) a set of electrodes disposed within each of the channels between the liquid inlet of the channel and the vapor outlet of the channel, the set of electrodes in each channel including electrodes disposed at different elevations;   (c) an electrical power supply having at least two poles, the power supply being operable to supply different electrical potentials to different ones of the poles;   (d) a circuit operable to selectively connect the electrodes to the poles and to selectively disconnect electrodes from the poles in a plurality of different connection schemes, each such connection scheme including at least two connected electrodes connected to different poles so that electrical current flows between the connected electrodes along a current path through liquid in at least one of the channels.   
     
     
         2 . A boiler as claimed in  claim 1  wherein the circuit is operative to selectively connect isolated electrodes which are not connected to the poles of the power supply and which are disposed in different channels to one another, and wherein, in at least one of the connection schemes, the current path extends through liquid in a plurality of channels and through the isolated electrodes. 
     
     
         3 . A boiler as claimed in  claim 1  wherein the structure defines an upper space communicating with the outlets of the channels and extending above the outlets of the channels and the vapor discharge communicates with the outlets of the channels via the upper space. 
     
     
         4 . A boiler as claimed in  claim 3  further comprising a liquid level control system operative to maintain a liquid level in the upper space above the outlets of the channels. 
     
     
         5 . A boiler as claimed in  claim 3  further comprising a set of baffles disposed in the upper space, the baffles being arranged to define a tortuous path for vapor rising within the upper space, and the baffles being arranged to allow entrained liquid which drops out of the vapor to drain downwardly. 
     
     
         6 . A boiler as claimed in  claim 1  wherein the set of electrodes disposed in each channel include a plurality of pairs of electrodes, the electrodes of each pair confronting one another. 
     
     
         7 . A boiler as claimed in  claim 1  further comprising a control system operative to repeatedly select a connection scheme from the plurality of connection schemes and command the circuit to connect the electrodes in the selected connection scheme, the control system being operative to detect the presence of vapor in current paths associated with various connection schemes and to substantially prevent prolonged operation with those connection schemes having vapor present. 
     
     
         8 . A boiler as claimed in  claim 7  wherein the control system is operative to select a connection scheme, connect the electrodes in the selected connection scheme, monitor the actual current passing between the poles of the power supply, compare the actual current to an expected current for the selected connection scheme, and select a new connection scheme if the actual current is less than the expected current by more than a current tolerance. 
     
     
         9 . A boiler as claimed in  claim 1  wherein the structure includes a vessel and a plurality of dielectric walls disposed within the vessel and defining the channels. 
     
     
         10 . A boiler as claimed in  claim 9  wherein the dielectric walls are plates extending substantially parallel to one another. 
     
     
         11 . A device for heating a conductive liquid comprising:
 (a) a structure defining a plurality of channels extending side-by-side and dielectric walls between each of the plurality of channels, the structure including means for directing the liquid through the channels;   (b) a set of electrodes within each channel, the set of electrodes within each channel including electrodes disposed at a plurality of locations along the length of the channel;   (c) an electrical power supply having at least two poles, the power supply being operable to supply different electrical potentials to different ones of the poles;   (d) a circuit operable to selectively connect the electrodes to the poles and to selectively disconnect electrodes from the poles in a plurality of different connection schemes, each such connection scheme including at least two connected electrodes connected to different poles so that electrical current flows between the connected electrodes along a current path through liquid in at least one of the channels, the circuit also being operable to select isolated electrodes of two different sets which are not connected to a pole of the power supply and connect the selected isolated electrodes to one another so that in at least one connection scheme, the current path extends between the connected electrodes through the isolated electrodes.   
     
     
         12 . A boiler comprising:
 (a) a vessel having a liquid inlet and a vapor outlet;   (b) a plurality of electrodes disposed within the vessel, the electrodes being disposed in an array extending vertically and extending in at least one horizontal direction so that some of the electrodes are disposed at a higher level than others of the electrodes and some of the electrodes are horizontally offset from others of the electrodes;   (c) an electrical power supply having at least two poles, the power supply being operable to supply different electrical potentials to different ones of the poles;   (d) a circuit operable to selectively connect the electrodes to the poles and to selectively disconnect electrodes from the poles in a plurality of different connection schemes, each such connection scheme including at least two connected electrodes connected to different poles so that electrical current flows between the connected electrodes along a current path through liquid in the vessel; and   (e) a control system operative to repeatedly select a connection scheme from the plurality of connection schemes and command the circuit to connect the electrodes in the selected connection scheme, the control system being operative to detect the presence of vapor in current paths associated with various connection schemes and to substantially prevent prolonged operation with those connection schemes having vapor present.   
     
     
         13 . A method of operating a heater comprising the steps of:
 (a) contacting a plurality of electrodes with an electrically conductive liquid;   (b) selectively connecting electrodes of the plurality of electrodes to establish a conduction path between poles of a power supply through the liquid;   (c) applying a voltage between the poles to heat the liquid and measuring an actual current flowing through the conduction path;   (d) comparing the actual current to an expected current for the conductive path; and   (e) repeating steps (b) through (e) with a different selection of electrodes to establish a different conduction path when the comparison performed in step (d) indicates that the actual current is less than the expected current by more than a current tolerance.   
     
     
         14 . A method as claimed in  claim 13  wherein step (b) includes setting a desired heating rate in response to measurements of one or more parameters indicating a result achieved by heating the liquid and selecting the electrodes and the current path based on the desired heating rate. 
     
     
         15 . A method as claimed in  claim 13  wherein the liquid boils during steps (a)-(e).