Thermal device, its use, and method for heating a heat transfer medium

A thermal device comprising

• at least a first wall delimiting a flow duct for gases;
• and
• a heat exchanger pipe comprising at least an inner pipe, at least a first first section of said heat exchanger pipe being placed in said flow duct for gases and extending in said flow duct for gases from said first wall to said first wall or to a second wall delimiting the flow duct for gases;
• the heat exchanger pipe comprising a second first section extending in said flow duct for gases from one wall to the same or another wall;
• and
• several other heat transfer pipes inside the walls of the flow duct for gases, for recovering heat, in which thermal device;
• said first first section of the heat exchanger pipe comprises:
• a second section of the heat exchanger pipe, extending in said flow duct for gases, wherein said second section of the heat exchanger pipe comprises:
• at least a section of the inner pipe, for transferring heat transfer medium from the first end to the second end of the inner pipe and for recovering heat by the heat transfer medium, an outer pipe which radially encloses said section of the inner pipe, and
• a medium layer placed between said outer pipe and said section of the inner pipe in the radial direction;
• and
• said heat exchanger pipe and said other heat transfer pipes constitute a continuous flow duct for the heat transfer medium, for heating the heat transfer medium, in which thermal device
• (A,i) the inner pipe of the first first section of said heat exchanger pipe is non-insulated from the flow duct for gases in one or more non-insulated areas in such a way that
• the distance from all points of the non-insulated areas of the first first section to the other heat recovery surfaces of the thermal devices is not greater than 15 cm;
• or
• (A,ii) said first first section of the heat exchanger pipe, or the inner pipe of said first first section of the heat exchanger pipe, is insulated, over its entire length, from the flow duct for gases by means of said outer pipe and/or an insulator, and
• (B,i) the second first section or its inner pipe is non-insulated from the flow duct for gases in one or more non-insulated areas in such a way that the distance from all the points in the non-insulated areas of the second first section to the other heat recovery surfaces of the device is not greater than 15 cm;
• or
• (B,ii) the second first section or the inner pipe of said second first section is, over its entire length, insulated from the flow duct for gases by means of a second outer pipe and/or an insulator, wherein
• (C,i) said flow duct for the heat transfer medium comprises the first first section of said heat exchanger pipe as the heat transfer element placed last in the flow duct of gases, in the direction of the flow of the heat transfer medium, or
• (C,ii) said flow duct for the heat transfer medium comprises the first first section of the heat exchanger pipe placed last in the flow duct for gases, in the flow direction of the heat transfer medium, and at least one heat transfer pipe placed downstream in the flow duct for gases, in the direction of flow of the heat transfer medium, and
• said first first section of the last heat exchanger pipe is arranged, in the flow direction of the gas flowing outside the outer pipe, upstream of said heat transfer pipes placed downstream in the flow duct for gases in the flow direction of the heat transfer medium, and
• (D) said inner pipe connects said first first section of the heat exchanger pipe to said second first section of the heat exchanger pipe outside said flow duct for gases,
• said second first section of the heat exchanger pipe is placed downstream of said first first section of the heat exchanger pipe in the flow direction of the medium flowing in the inner pipe, and
• said second first section of the heat exchanger pipe is placed downstream of said first first section of the heat exchanger pipe in the flow direction of the gas flowing outside the heat exchanger pipe.

A method for heating a heat transfer medium, the method comprising:

• producing gas heated by a thermal device,
• conveying said gas into a flow duct for gases,
• conveying heat transfer medium into a heat exchanger pipe comprising
• at least an inner pipe,
• at least the first first section of the heat exchanger pipe being placed in the flow duct for gases and extending in said flow duct for gases from the wall of said flow duct to the same or another wall of said flow duct, and said first first section of the heat exchanger pipe comprising a second section of the heat exchanger pipe, extending in said flow duct for gases, and
• a second first section extending in said flow duct for gases from one wall to the same or another wall,
• recovering heat by the heat transfer medium by means of said heat exchanger pipe, in which method the thermal device comprises
• several other heat transfer pipes inside the walls of the flow duct for gases, for recovering heat,
• said second section of the heat exchanger pipe comprises
• at least a section of the inner pipe for transferring heat transfer medium from the first end to the second end of the inner pipe and for recovering heat by the heat transfer medium,
• an outer pipe which radially encloses said section of the inner pipe, and
• a layer of medium left between said outer pipe and said part of the inner pipe in the radial direction,
• said heat exchanger pipe and said other heat transfer pipes constitute a continuous flow duct for the heat transfer medium, for heating the heat transfer medium, and
• the inner pipe of the first first section of said heat exchanger pipe is non-insulated from the flow duct for gases in one or more non-insulated areas in such a way that
• the distance from all points of the non-insulated areas of the first first section to the other heat recovery surfaces of the thermal devices is not greater than 15 cm;
• or
• said first first section of the heat exchanger pipe, or the inner pipe of said first first section of the heat exchanger pipe, is insulated, over its entire length, from the flow duct for gases by means of said outer pipe and/or an insulator, and
• the second first section or its inner pipe is non-insulated from the flow duct for gases in one or more non-insulated areas in such a way that
• the distance from all the points in the non-insulated areas of the second first section to the other heat recovery surfaces of the device is not greater than 15 cm;
• or
• the second first section or the inner pipe of said second first section is, over its entire length, insulated from the flow duct for gases by means of a second outer pipe and/or an insulator,
• wherein
• said flow duct for the heat transfer medium comprises the first first section of said heat exchanger pipe as the heat transfer element placed last in the flow duct of gases, in the direction of the flow of the heat transfer medium, or
• said flow duct for the heat transfer medium comprises the first first section of the heat exchanger pipe placed last in the flow duct for gases, in the flow direction of the heat transfer medium, and at least one heat transfer pipe placed downstream in the flow duct for gases, in the direction of flow of the heat transfer medium, and
• said first first section of the last heat exchanger pipe is arranged, in the flow direction of the gas flowing outside the outer pipe, upstream of said heat transfer pipes placed downstream in the flow duct for gases in the flow direction of the heat transfer medium, and
• said inner pipe connects said first first section of the heat exchanger pipe to said second first section of the heat exchanger pipe outside said flow duct for gases,
• said second first section of the heat exchanger pipe is placed downstream of said first first section of the heat exchanger pipe in the flow direction of the medium flowing in the inner pipe, and
• said second first section of the heat exchanger pipe is placed downstream of said first first section of the heat exchanger pipe in the flow direction of the gas flowing outside the heat exchanger pipe.