Single-duct tubular boiler for use in connection with a refuse incinerator and an air preheater

Claim 2

A ducting arrangement for a tubular boiler for generating steam or hot water by heat recovery from flue gas issuing from an incinerator for low-grade refuse of variable calorific value, comprising a horizontal flue-gas duct, said boiler including vertical boiler tubes arranged in a plurality of one row banks transversal and orthogonal to the axis of said horizontal duct, with a gap in each of the tube banks, defined by wider spacing between two adjacent boiler tubes, said gaps being in alignment and thus defining a longitudinal through channel, said channel being provided with an all-side gastight enclosure, to serve as parallel duct for diverting at least a part of the stream of flue gas, to bypass the heating surface of the boiler.

Claim 3

A ducting arrangement for a tubular boiler as claimed in claim 1, and further including movable damper means at the outlet of said parallEl duct, and means externally of said horizontal duct for actuating said damper means for controlling the volume of flue gas flowing through said parallel duct.

Claim 4

In a system including means defining an incinerator for low-grade refuse of variable calorific value, said means including a combustion chamber, an undergrate combustion supporting air chamber means, a flue-gas duct including a horizontal portion, an air preheating means arranged within said flue-gas duct downstream of said horizontal portion for preheating air and including an outlet for delivering said preheated air to said undergrate combustion supporting air chamber means, a boiler including boiler tube bank means disposed within said horizontal portion of said flue-gas duct, said boiler tube bank means being vertically disposed and so arranged as to include at least two rows of longitudinally spaced tubes spaced transversely of the longitudinal axis of said horizontal portion of said flue-gas duct and means operably associated with said at least two rows of tubes defining a gastight passage extending longitudinally of said horizontal portion of said flue-gas duct to constitute a bypass duct having an inlet and an outlet in parallel flow relation with said flue-gas duct.

Claim 5

In a system including means defining an incinerator for low-grade refuse of variable calorific value, said means including a combustion chamber, an undergrate combustion supporting air chamber means, a flue-gas duct including a horizontal portion, an air preheating means arranged within said flue-gas duct downstream of said horizontal portion for preheating air and including an outlet for delivering said preheated air to said undergrate combustion supporting air chamber means, a boiler including boiler tube bank means disposed within said horizontal portion of said flue-gas duct, said boiler tube bank means being vertically disposed and so arranged as to include at least two rows of longitudinally spaced tubes spaced transversely of the longitudinal axis of said horizontal portion of said flue-gas duct and means operably associated with said at least two rows of tubes defining a gastight passage extending longitudinally of said horizontal portion of said flue-gas duct to constitute a bypass duct having an inlet and an outlet in parallel flow relation with said flue-gas duct.

Claim 6

A system as claimed in claim 3 and movable damper means operably associated with the outlet of said bypass duct for controlling the volume of flue gas flowing through said bypass duct.

Claim 7

A system as claimed in claim 4 and means for varying the position of said damper means in dependence upon temperature conditions existing in one of either combustion chamber, said outlet of said air preheating means, said flue-gas duct downstream of said air preheating means, or said flue-gas duct at a location between said bypass duct and said air preheating means.

Claim 8

In the operation of a system including an incinerator having a combustion chamber for burning low-grade refuse of variable calorific value, a flue-gas duct communicating with said incinerator and including a horizontal portion, a boiler including tubes arranged within said flue-gas duct to extract heat from flue gas flowing through said duct, an air preheater arranged within said flue-gas duct downstream of said tubes for also extracting heat from such flue gas and for delivering preheated combustion supporting air to said incinerator, a method of controlling such operation including constraining at least a portion of such flue gas to flow through such horizontal portion of said flue-gas duct in a to bypass at least the majority of such tubes and in a parallel flow relationship with the main flue gas flow stream and controlling the volume of such bypassed portion of flue gas by variably positioning dampers controlling such bypassed flow.

Claim 9

In the operation of a system including an incinerator having a combustion chamber for burning low-grade refuse of variable calorific value, a flue-gas duct communicating with said incinerator and including a horizontal portion, a boiler including tubes arranged within said flue-gas duct to extract heat from flue gas flowing through said duct, an air preheater arranged within said flue-gas duct downstream of said tubes for also extracting heat from such flue gas and for delivering preheated combustion supporting air to said incinerator, a method of controlling such operation including constraining at least a portion of such flue gas to flow through such horizontal portion of said flue-gas duct in a to bypass at least the majority of such tubes and in a parallel flow relationship with the main flue gas flow stream and controlling the volume of such bypassed portion of flue gas by variably positioning dampers controlling such bypassed flow.

Claim 10

In the operation of a system as claimed in claim 6 and positioning such dampers in accordance with the temperature of the preheated combustion supporting air.

Claim 11

In the operation of a system as claimed in claim 6 and positioning such dampers in accordance with temperature conditions within the combustion chamber.

Claim 12

In the operation of a system as claimed in claim 6 and positioning such dampers in accordance with the temperature of the flue gas at its entry into the air preheater.

Claim 13

In the operation of a system as claimed in claim 6 and positioning such dampers in accordance with the temperature of the flue gas downstream of the air preheater.

Claim 14

A ducting arrangement for a tubular boiler for generating steam or hot water by heat recovery from flue gas issuing from an incinerator for low-grade refuse of variable calorific value, comprising a substantially horizontal flue-gas duct, said boiler including vertical boiler tubes arranged in a plurality of one row banks substantially transversal and substantially orthogonal to the axis of said horizontal duct, with a gap in each of the tube banks, defined by wider spacing between two adjacent boiler tubes, said gaps being in substantial alignment and thus defining a longitudinal thRough-channel, said channel being provided with an all-side gastight enclosure, to serve as parallel duct for diverting at least a part of the stream of flue gas, to bypass the heating surface of the boiler, movable damper means at the outlet of said parallel duct, and means for actuating said damper means for controlling the volume of flue gas flowing through said parallel duct.

Claim 15

A ducting arrangement for a tubular boiler for generating steam or hot water by heat recovery from flue gas issuing from an incinerator for low-grade refuse of variable calorific value, comprising a substantially horizontal flue-gas duct, said boiler including vertical boiler tubes arranged in a plurality of one row banks substantially transversal and substantially orthogonal to the axis of said horizontal duct, with a gap in each of the tube banks, defined by wider spacing between two adjacent boiler tubes, said gaps being in substantial alignment and thus defining a longitudinal thRough-channel, said channel being provided with an all-side gastight enclosure, to serve as parallel duct for diverting at least a part of the stream of flue gas, to bypass the heating surface of the boiler, movable damper means at the outlet of said parallel duct, and means for actuating said damper means for controlling the volume of flue gas flowing through said parallel duct.