Process and catalyst structure employing intergal heat exchange with optional downstream flameholder

A reaction system for combustion of a combustible mixture of fuel and an oxygen-containing gas wherein a flowing stream of the combustible mixture, in vapor or gaseous form, is initially subject to partial combustion in the presence of a catalyst followed by complete combustion under non-catalytic conditions in a homogeneous combustion zone downstream from the catalyst comprising a housing containing:

• (a) a catalyst structure made up of a heat resistant support material composed of a plurality of common walls which form a multitude of adjacently disposed longitudinal channels for passage of the combustible mixture, wherein at least a part of the interior surface of at least a portion of the channels is coated with a catalyst for the combustible mixture and the interior surface of the remaining channels is not coated with catalyst such that the interior surface of the catalyst-coated channels are in heat exchange relationship with the interior surface of adjacent catalyst-free channels and wherein:
• (i) the catalyst-coated channels have a smaller average hydraulic diameter (D.sub.h) than the catalyst-free channels;
• (ii) the catalyst-coated channels have a higher film heat transfer coefficient (h) than the catalyst-free channels;
• and
• (iii) the catalyst-coated channels form a more tortuous flow passage for the reaction mixture than the flow passage formed by the catalyst-free channels;
• such that only a portion of the combustible mixture undergoes combustion to afford a partially-combusted, gaseous mixture flowing at elevated temperature from an outlet end of the catalyst structure;
• (b) a homogeneous combustion zone comprising an enclosed space in fluid communication with the catalyst structure and located immediately downstream from the outlet end of the catalyst structure;
• and
• (c) a means for inducing recirculation in the partially-combusted mixture flowing through the homogeneous combustion zone whereby homogeneous combustion of the partially-combusted mixture is stabilized within the region of recirculation and complete combustion of the partially-combusted mixture is promoted within the homogeneous combustion zone.

A reaction system for combustion of a combustible mixture of fuel and an oxygen-containing gas wherein a flowing stream of the combustible mixture, in vapor or gaseous form, is initially subject to partial combustion in the presence of a catalyst followed by complete combustion under non-catalytic conditions in a homogeneous combustion zone downstream from the catalyst comprising a housing containing:

• (a) a catalyst structure made up of a heat resistant support material composed of a plurality of common walls which form a multitude of adjacently disposed longitudinal channels for passage of the combustible mixture, wherein at least a part of the interior surface of at least a portion of the channels is coated with a catalyst for the combustible mixture and the interior surface of the remaining channels is not coated with catalyst such that the interior surface of the catalyst-coated channels are in heat exchange relationship with the interior surface of adjacent catalyst-free channels and wherein catalyst-coated channels form a more tortuous flow passage than the catalyst-free channels and have a film heat transfer coefficient (h) which is more than 1.5 times greater than the h for catalyst-free channels and the catalyst-coated channels represent from about 20% to about 80% of the total open frontal area in the catalyst structure, such that only a portion of the combustible mixture undergoes combustion to afford a partially-combusted, gaseous mixture flowing at elevated temperature from an outlet end of the catalyst structure;
• (b) a homogeneous combustion zone comprising an enclosed space in fluid communication with the catalyst structure and located immediately downstream from the outlet end of the catalyst structure;
• and
• (c) a means for inducing recirculation into the partially-combusted mixture flowing through the homogeneous combustion zone whereby homogeneous combustion of the partially-combusted mixture is stabilized within the region of recirculation and complete combustion of the partially-combusted mixture is promoted with the homogeneous combustion zone.

A reaction system for combustion of a combustible mixture of fuel and an oxygen-containing gas wherein a flowing stream of the combustible mixture, in vapor or gaseous form, is initially subject to partial combustion in the presence of a catalyst followed by complete combustion under non-catalytic conditions in a homogeneous combustion zone downstream from the catalyst comprising a housing containing:

• (a) a catalyst structure made up of a heat resistant support material composed of a plurality of common walls which form a multitude of adjacently disposed longitudinal channels for passage of the combustible mixture, wherein at least a part of the interior surface of at least a portion of the channels is coated with a catalyst for the combustible mixture and the interior surface of the remaining channels is not coated with catalyst such that the interior surface of the catalyst-coated channels are in heat exchange relationship with the interior surface of adjacent catalyst-fee channels and wherein catalyst-coated channels have a lower average hydraulic diameter (D.sub.h) than the catalyst-free channels and the numeric ratio of average D.sub.h for the catalyst-coated channels divided by the average D.sub.h for the catalyst-free channels is smaller than the numeric ratio of open frontal area of the catalyst-coated channels divided by the open frontal area of the catalyst-free channels, such that only a portion of the combustible mixture undergoes combustion to afford a partially-combusted, gaseous mixture flowing at elevated temperature from an outlet end of the catalyst structure;
• (b) a homogeneous combustion zone comprising an enclosed space in fluid communication with the catalyst structure and located immediately downstream from the outlet end of the catalyst structure;
• and
• (c) a means for inducing recirculation into the partially-combusted mixture flowing through the homogeneous combustion zone whereby complete combustion of the partially-combusted mixture is stabilized within the region of recirculation and complete combustion of the partially-combusted mixture is promoted with the homogeneous combustion zone.

A reaction system for combustion of a combustible mixture of fuel and an oxygen-containing gas wherein a flowing stream of the combustible mixture, in vapor or gaseous form, is initially subject to partial combustion in the presence of a catalyst followed by complete combustion under non-catalytic conditions in a homogeneous combustion zone downstream from the catalyst comprising a housing containing:

• (a) a catalyst structure made up of a heat resistant support material composed of a plurality of common walls which form a multitude of adjacently disposed longitudinal channels for passage of the combustible mixture, wherein at least a part of the interior surface of at least portion of the channels is coated with a catalyst for the combustible mixture and the interior surface of the remaining channels is not coated with catalyst such that the interior surface of the catalyst-coated channels are in heat exchange relationship with the interior surface of adjacent catalyst-free channels and wherein:
• (i) the catalyst-coated channels have a higher film heat transfer coefficient (h) than the catalyst-free channels;
• (ii) the catalyst-coated channels have a smaller average hydraulic diameter (D.sub.h) than the catalyst-free channels;
• and
• (iii) the numeric ratio of the average D.sub.h for the catalyst-coated channels divided by the average D.sub.h for the catalyst-free channels is smaller than the numeric ratio of the open frontal area of the catalyst-coated channels divided by the open frontal area of the catalyst-free channels;
• such that only a portion of the combustible mixture undergoes combustion to afford a partially-combusted, gaseous mixture flowing at elevated temperature from an outlet end of the catalyst structure;
• (b) a homogeneous combustion zone comprising an enclosed space in fluid communication with the catalyst structure and located immediately downstream from the outlet end of the catalyst structure;
• and
• (c) a means for inducing recirculation into the partially-combusted mixture flowing through the homogeneous combustion zone whereby homogeneous combustion of the partially-combusted mixture is stabilized within the region of recirculation and complete combustion of the partially-combusted mixture is promoted with the homogeneous combustion zone.

A reaction system for combustion of a combustible mixture of fuel and an oxygen-containing gas wherein a flowing stream of the combustible mixture, in vapor or gaseous form, is initially subject to partial combustion in the presence of a catalyst followed by complete combustion under non-catalytic conditions in a homogeneous combustion zone downstream from the catalyst comprising a housing containing:

• (a) a catalyst structure made up of a heat resistant support material composed of a plurality of common walls which form a multitude of adjacently disposed longitudinal channels for passage of the combustible mixture, wherein at least a part of the interior surface of at least a portion of the channels is coated with a catalyst for the combustible mixture and the interior surface of the remaining channels is not coated with catalyst such that the interior surface of the catalyst-coated channels are in heat exchange relationship with the interior surface of adjacent catalyst-free channels and wherein:
• (i) the catalyst-coated channels have a higher film heat transfer coefficient (h) than the catalyst-free channels;
• (ii) more than 50% of the total reaction mixture flow is through the catalyst-coated channels;
• and
• (iii) the catalyst-coated channels form a more tortuous flow passage for the combustible mixture than the flow passage formed by the catalyst-free channels;
• such that only a portion of the combustible mixture undergoes combustion to afford a partially-combusted, gaseous mixture flowing at elevated temperature from an outlet end of the catalyst structure;
• (b) a homogeneous combustion zone comprising an enclosed space in fluid communication with the catalyst structure and located immediately downstream from the outlet end of the catalyst structure;
• and
• (c) a means for inducing recirculation into the partially-combusted mixture flowing through the homogeneous combustion zone whereby homogeneous combustion of the partially-combusted mixture is stabilized within the region of recirculation and complete combustion of the partially-combusted mixture is promoted with the homogeneous combustion zone.

A reaction system for combustion of a combustible mixture of fuel and an oxygen-containing gas wherein a flowing stream of the combustible mixture, in vapor or gaseous form, is initially subject to partial combustion in the presence of a catalyst followed by complete combustion under non-catalytic conditions in a homogeneous combustion zone downstream from the catalyst comprising a housing containing:

• (a) a catalyst structure made up of a heat resistant support material composed of a plurality of common walls which form a multitude of adjacently disposed longitudinal channels for passage of the combustible mixture, wherein at least a part of the interior surface of at least a portion of the channels is coated with a catalyst for the combustible mixture and the interior surface of the remaining channels is not coated with catalyst such that the interior surface of the catalyst-coated channels are in heat exchange relationship with the interior surface of adjacent catalyst-free channels and wherein:
• (i) the catalyst-coated channels have a higher film heat transfer coefficient (h) than the catalyst-free channels by a factor of greater than 1.2;
• and
• (ii) more than 40%, but less than 50% of the total reaction mixture flow is through the catalyst-coated channels;
• and
• (iii) the catalyst-coated channels form a more tortuous flow passage for the combustible mixture than the flow passage formed by the catalyst-free channels;
• such that only a portion of the combustible mixture undergoes combustion to afford a partially-combusted, gaseous mixture flowing at elevated temperature from an outlet end of the catalyst structure;
• (b) a homogeneous combustion zone comprising an enclosed space in fluid communication with the catalyst structure and located immediately downstream from the outlet end of the catalyst structure;
• and
• (c) a means for inducing recirculation into the partially-combusted mixture flowing through the homogeneous combustion zone whereby homogeneous combustion of the partially-combusted mixture is stabilized within the region of recirculation and complete combustion of the partially-combusted mixture is promoted with the homogeneous combustion zone.

A reaction system for combustion of a combustible mixture of fuel and an oxygen-containing gas wherein a flowing stream of the combustible mixture, in vapor or gaseous form, is initially subject to partial combustion in the presence of a catalyst followed by complete combustion under non-catalytic conditions in a homogeneous combustion zone downstream from the catalyst comprising:

• (a) a catalyst structure made up of a heat resistant support material composed of a plurality of common walls which form a multitude of adjacently disposed longitudinal channels for passage of the combustible mixture, wherein at least a part of the interior surface of at least a portion of the channels is coated with a catalyst for the combustible mixture and the interior surface of the remainin channels is not coated with catalyst such that the interior surface of the catalyst-coated channels are in heat exchange relationship with the interior surface of adjacent catalyst-free channels and wherein:
• (i) the catalyst-coated channels have a higher film heat transfer coefficient (h) than the catalyst-free channels by a factor of greater than 1.3;
• and
• (ii) more than 30%, but less than 40% of the total reaction mixture flow is through the catalyst-coated channels;
• and
• (iii) the catalyst-coated channels form a more tortuous flow passage for the combustible mixture than the flow passage formed by the catalyst-free channels;
• such that only a portion of the combustible mixture undergoes combustion to afford a partially-combusted, gaseous mixture flowing at elevated temperature from the outlet end of the catalyst structure;
• (b) a homogeneous combustion zone comprising an enclosed space in fluid communication with the catalyst structure and located immediately downstream from the outlet end of the catalyst structure;
• and
• (c) a means for inducing recirculation into the partially-combusted mixture flowing through the homogeneous combustion zone whereby homogeneous combustion of the partially-combusted mixture is stabilized within the region of recirculation and complete combustion of the partially-combusted mixture is promoted with the homogeneous combustion zone.

A process for the combustion of a combustible mixture comprising the steps of:

• (a) mixing a fuel and an oxygen-containing gas to form a combustible mixture;
• (b) contacting the mixture with a heat resistant catalyst support composed of a plurality of common walls which form a multitude of adjacently disposed longitudinal channels for passage of the combustible mixture wherein at least a part of the interior surface of at least a portion of the channels is coated with a catalyst for the combustible mixture and the interior surface the remaining channels is not coated with catalyst such that the interior surface of the catalyst-coated channels are in heat exchange relationship with the interior surface of adjacent catalyst-free channels and wherein:
• (i) the catalyst-coated channels have a higher film heat transfer coefficient (h) than the catalyst-free channels;
• (ii) the catalyst-coated channels have a smaller average D.sub.h than the catalyst-free channels;
• and
• (iii) the catalyst-coated channels form a more tortuous flow passage for the combustible mixture than the flow passage formed by the catalyst-free channels;
• thereby combusting a portion of the combustible mixture to afford a partially-combusted, gaseous mixture;
• and
• (c) passing the partially-combusted, gaseous mixture to a homogeneous combustion zone equipped with a flameholder to erect recirculation of at least a portion of the partially-combusted mixture such that homogeneous combustion is stabilized within the region of recirculation and essentially complete combustion of the partially-combusted mixture is obtained.

A process for the combustion of a combustible mixture comprising the steps of:

• (a) mixing a fuel and an oxygen-containing gas to form a combustible mixture;
• (b) contacting the mixture with a heat resistant catalyst support composed of a plurally of common walls which form a multitude of adjacently disposed longitudinal channels for passage of the combustible mixture wherein at least a part of the interior surface of at least a portion of the channels is coated with a catalyst for the combustible mixture and interior surface of the remaining channels is not coated with catalyst such that the interior surface of the catalyst-coated channels are in heat exchange relationship with the interior surface of adjacent catalyst-free channels and wherein:
• (i) the catalyst-coated channels have a higher film heat transfer coefficient (h) than the catalyst-free channels;
• (ii) the catalyst-coated channels have a smaller average D.sub.h than the catalyst-free channels;
• and
• (iii) the numeric ratio of average D.sub.h for the catalyst-coated channels divided by the average D.sub.h for the catalyst-free channels is smaller than the numeric ratio of open frontal area of the catalyst-coated channels divided by the open frontal area of the catalyst-free channels;
• thereby combusting a portion of the combustible mixture to afford a partially-combusted, gaseous mixture;
• and
• (c) passing the partially-combusted, gaseous mixture to a homogeneous combustion zone equipped with a flameholder to effect recirculation of at least a portion of the partially-combusted mixture such that homogeneous combustion is stabilized within the region of recirculation and essentially complete combustion of the partially-combusted mixture is obtained.