Viewport for high temperature combustion zones

A viewport for a combustion zone, said viewport comprising:

• an inner casing assembly, said inner casing assembly having an inner plate 28, an inner casing window opening disposed centrally relative to said inner plate, said inner plate being attached to an exterior surface of a wall of said combustion zone, said inner casing assembly further having a flange extending from said inner plate into said combustion zone, said inner plate having an exterior inner plate surface;
• a first layer of insulation formed of ceramic fibers positioned adjacent to said exterior inner plate surface, said first layer of insulation having a first layer window opening, said first layer window opening being aligned relative to said inner plate, said first layer window opening having a first layer window opening size dimension;
• a middle casing assembly, said middle casing assembly being positioned adjacent and exterior to said first layer of insulation, said middle casing assembly comprising a first middle plate having a first middle casing window opening, a plurality of traverse plates integral to and extending normally from said first middle plate proximate to said first middle casing window opening, and second middle plate having a second middle window opening, said second middle plate being integral with said plurality of traverse plates proximate to said first middle casing window opening, said second middle plate having an exterior second middle plate surface, said first middle casing window opening having a first middle casing window opening size dimension, said second middle window opening having a second middle window opening size dimension;
• a first insulated pane of glass formed of quartz disposed between said first middle plate and said first layer of insulation, said first insulated pane of glass having a first or inner insulated pane of glass size dimension, said first insulated pane of glass size dimension being larger than said first middle casing window opening size dimension and said first layer window opening size dimension;
• a second layer of insulation formed of ceramic fibers positioned adjacent to said exterior second middle plate surface, said second layer of insulation having a second layer window opening, said second layer window opening being aligned relative to said second middle window opening, said second layer window opening having a second layer window opening size dimension;
• a second insulated pane of glass formed of quartz disposed between said second middle plate and said second layer of insulation, said second insulated pane of glass having a second insulated pane of glass size dimension which is larger than said second middle window opening size dimension and said second layer window opening size dimension;
• and
• an outer casing assembly, said outer casing assembly having an outer casing window opening, said outer casing window opening being aligned relative to said second layer window opening, wherein first fasteners extend outwardly from said interior of said wall, said first fasteners engaging said inner plate, said first layer of insulation and said first middle plate, wherein tightening said first fasteners squeezes said first insulated pane of glass between said middle casing assembly and said inner plate, and further wherein second fasteners extend inwardly from said outer casing assembly, said second fasteners engaging said outer casing assembly, said second layer of insulation and said second middle plate, wherein tightening of said second fasteners squeezes said second insulated pane of glass 44 between said second layer of insulation and said second middle plate and further wherein said first fasteners may be released from said inner casing assembly, said first layer of insulation and said middle casing assembly, whereupon said outer casing assembly may be separated from said inner casing assembly.