Thermally autogenous subsurface chemical reactor and method

A subsurface, thermally autogenous reactor for effecting a wet oxidation of aqueous wastes, comprising:

• downgoing means for defining a downgoing flow passage having a top end, a plurality of spaced, elongated, cylindrical downgoing heat exchange tubes below said top end, a plurality of spaced, elongated, cylindrical downgoing reaction tubes below said downgoing heat exchange tubes, and a bottom end, said downgoing heat exchange tubes extending to a depth sufficient to form a hydrostatic column of said aqueous wastes having a pressure and temperature sufficient to allow said wet oxidation, said downgoing means having a selected first cross sectional area,
• a pump for pumping said fluid into said top end of said downgoing flow passage,
• an air injection system connected to said downgoing means between said downgoing heat exchange and reaction sections for injecting compressed air which contains oxygen into said aqueous wastes and to cause said wet oxidation at a pressure that increases the mass of said oxygen to produce increased heat during said wet oxidation and,
• upgoing means for defining an upgoing flow passage in heat exchange relation to said downgoing means, and having a top end, an upgoing tube below said top end and around said downgoing heat exchange and reaction tubes, and a closed bottom end in flow communication with said bottom end of said downgoing means such that said aqueous wastes and air flowing down said downgoing and out said top end of said upgoing means, said upgoing means having a selected second cross sectional area, that is selected to be significantly greater than said first cross sectional area to slow the velocity of said two phase fluid in said upgoing heat exchange section relative to the velocity of said aqueous wastes in said downgoing heat exchange section to provide a substantially maximum amount of heat transfer from said two phase fluid in said upgoing heat exchange section to said aqueous wastes in said downgoing heat exchange section, and
• a reversible flow heat exchanger inside said upgoing tube, in spaced relation to said downgoing heat exchange tubes and said downgoing reaction tubes, said heat exchanger extending from said top end to near said bottom end of said upgoing means, for initiating said wet oxidation, controlling the temperature of said wet oxidation, and recovering excess heat from said wet oxidation,
• whereby to sustain said wet oxidation without addition of heat from another source.

A method of effecting a subsurface, thermally autogenous wet oxidation of aqueous wastes, comprising the steps of:

• providing a downgoing flow passage, having a downgoing heat exchange section and a downgoing reaction section below said downgoing heat exchange section, said downgoing heat exchange section extending to a depth sufficient to form a hydrostatic column of said aqueous wastes having a pressure and temperature sufficient to allow said wet oxidation, said downngoing heat exchange section having a selected first cross sectional area, and
• providing an air injection system connected to said downgoing means between said downgoing heat exchange and reaction sections,
• injecting compressed air which contains oxygen into said aqueous wastes in said downgoing passage with said air injection system to cause said wet oxidation at a pressure that increases the mass of said oxygen to produce increased heat during said wet oxidation,
• providing an upgoing flow passage in heat exchange relation to said downgoing flow passage, and having an upgoing heat exchange section and an upgoing reaction section below said upgoing heat exchange section, said upgoing flow passage being in flow communication with said downgoing flow passage such that said aqueous wastes flowing down said downgoing flow passage flows back up said upgoing flow passage as a two phase fluid, said upgoing heat exchange section having a selected second cross sectional area that is selected to be significantly greater than said first cross sectional area to slow the velocity of said two phase fluid in said upgoing heat exchange section relative to the velocity of said aqueous wastes in said downgoing heat exchange section to provide a substantially maximum amount of heat transfer from said two phase fluid in said upgoing heat exchange section to said aqueous wastes in said downgoing heat exchange section,
• flowing said aqueous wastes down said downgoing flow passage and up said upgoing flow passage,
• transferring heat from said two phase fluid in said upgoing heat exchange section to said aqueous wastes in said downgoing heat exchange section sufficient to sustain said step of wet oxidation,
• whereby said wet oxidation is thermally autogenous.