External descending type waste heat recovery system for heating furnace

Abstract

The utility model discloses an external descending type waste heat recovery system for a heating furnace, which comprises a steel structure, a high-temperature coal economizer, a medium-temperature coal economizer and a low-temperature coal economizer, and the steel structure is fixed on an open space beside the heating furnace; the high-temperature coal economizer, the medium-temperature coal economizer and the low-temperature coal economizer are sequentially arranged from top to bottom, and all the coal economizers are supported on the steel structure through supporting feet. The upper end of the high-temperature economizer is provided with a high-temperature economizer inlet flue, every two adjacent economizers are connected through a connecting flue, and the lower end of the low-temperature economizer is provided with a low-temperature economizer outlet flue. The high-temperature coal economizer inlet flue, the high-temperature coal economizer shell, the medium-temperature coal economizer shell, the low-temperature coal economizer shell, the low-temperature coal economizer outlet flue and all the connecting flues jointly form a vertical flue. The external descending type waste heat recovery system for the heating furnace is flexible in arrangement and reasonable in heat exchange process, and can effectively avoid the fault condition that water is difficult to feed into a steam drum of a waste heat boiler due to boiling of a coal economizer.

Description

Technical Field

[0001] The utility model relates to an external downward type waste heat recovery system for a heating furnace. Background Art

[0002] Existing heating furnaces for oil refining and chemical industry are generally equipment for heating continuous materials to a certain temperature. In order to improve the utilization efficiency of heating furnace fuel, a waste heat boiler is generally arranged at the top outlet of the heating furnace. The waste heat boiler is generally arranged with superheater, evaporator and economizer from bottom to top from the outlet of the heating furnace. The top of the economizer is directly connected to the chimney. This top-mounted waste heat boiler is simple in layout and saves space. However, there are serious defects in this waste heat boiler, which are mainly manifested as follows: the economizer is top-mounted, and the high-temperature flue gas flows from bottom to top. In order to effectively recover the waste heat of the flue gas, the cold water in the economizer needs to flow from top to bottom to form countercurrent heat exchange. After the cold water absorbs heat and heats up, the density decreases and there is a tendency to move upward. When the water in the economizer tube absorbs heat and reaches saturation, there is inevitably steam-water stratification in the economizer tube, and the steam-water resistance in the economizer surges, which eventually makes it difficult to fill the steam drum with water. Utility Model Content

[0003] The purpose of the utility model is to overcome the defects of the prior art and provide an external downward waste heat recovery system for a heating furnace, which has the advantages of flexible layout, reasonable flue gas flow, smooth water circulation, and easy installation, overhaul and maintenance of equipment. Since it has a larger layout space after being externally placed, the heating surface can be sufficiently arranged, which can effectively improve the thermal efficiency of the heating furnace and reduce the energy consumption of the device.

[0004] The technical solution to achieve the above purpose is: an external downward waste heat recovery system for a heating furnace, comprising a steel structure, a high-temperature economizer, a medium-temperature economizer and a low-temperature economizer, wherein:

[0005] The steel structure is fixed on the open space beside the heating furnace;

[0006] The high-temperature economizer, the medium-temperature economizer and the low-temperature economizer are arranged in sequence from top to bottom, and each economizer is supported on the steel structure by supporting legs;

[0007] The upper end of the high-temperature economizer is provided with a high-temperature economizer inlet flue, the lower end of the high-temperature economizer and the upper end of the medium-temperature economizer, as well as the lower end of the medium-temperature economizer and the upper end of the low-temperature economizer are respectively connected via connecting flues, the lower end of the low-temperature economizer is provided with a low-temperature economizer outlet flue, the high-temperature economizer inlet flue, the shell of the high-temperature economizer, the shell of the medium-temperature economizer, the shell of the low-temperature economizer, the low-temperature economizer outlet flue and the connecting flues together form a vertical flue;

[0008] The water inlet of the low-temperature economizer is externally connected to the boiler feed water main, and the water outlet of the low-temperature economizer and the water inlet of the medium-temperature economizer, as well as the water outlet of the medium-temperature economizer and the water inlet of the high-temperature economizer are respectively connected by connecting pipes; the water outlet of the high-temperature economizer is connected to the waste heat boiler drum of the heating furnace.

[0009] The above-mentioned external downward waste heat recovery system for a heating furnace, wherein the high-temperature economizer inlet flue and the low-temperature economizer outlet flue are connected to the hot flue gas channel and the cold flue gas channel of the heating furnace through pipelines in a one-to-one correspondence.

[0010] In the above-mentioned external downward waste heat recovery system for a heating furnace, an induced draft fan is arranged between the low-temperature economizer outlet flue and the cold flue gas channel of the heating furnace.

[0011] The above-mentioned external downward waste heat recovery system for a heating furnace, wherein the hot flue gas of the heating furnace flows from top to bottom along the vertical flue, and the deoxygenated water in the boiler feed water main flows from bottom to top, and the two sides perform countercurrent heat exchange.

[0012] The above-mentioned external downward waste heat recovery system for a heating furnace, wherein each economizer adopts a modular structure, and is composed of a shell and an upper header, a lower header and a plurality of tube bundles arranged therein;

[0013] The multiple groups of tube bundles are used to absorb the flue gas waste heat in the vertical flue and transfer heat to the boiler feed water in the tube bundles;

[0014] The upper header is used as a water outlet to collect boiler feed water from the multiple tube bundles and lead them out uniformly;

[0015] The lower header acts as a water inlet, and is used to distribute water from the boiler feed water main to the multiple tube bundles;

[0016] The shell is used to seal the flue gas and provide a space for heat exchange between the flue gas and boiler feed water.

[0017] The utility model is an external downward waste heat recovery system for a heating furnace, which has the advantages of flexible layout, reasonable flue gas flow, smooth water circulation, and easy installation, inspection and maintenance of equipment. Since it has a larger layout space after being externally placed, the heating surface can be sufficiently arranged, which can effectively improve the thermal efficiency of the heating furnace and reduce the energy consumption of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a front view of an external downward waste heat recovery system for a heating furnace according to the utility model;

[0019] Figure 2 It is a side view of the external downward waste heat recovery system for a heating furnace of the utility model;

[0020] Figure 3 It is a top view of the external downward waste heat recovery system for a heating furnace of the utility model;

[0021] Figure 4 It is a schematic diagram of the connection between the external downward waste heat recovery system and the heating furnace of the utility model;

[0022] Figure 5 This is a schematic diagram of the structure of a single economizer. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the technical solution of the utility model, the specific implementation method thereof is described in detail below in conjunction with the accompanying drawings:

[0024] See also Figures 1 to 5 The best embodiment of the utility model is an external downward waste heat recovery system for a heating furnace, comprising a steel structure 4, a high-temperature economizer 1, a medium-temperature economizer 2 and a low-temperature economizer 3.

[0025] The steel structure 4 is fixed on the open space beside the heating furnace 100; the high-temperature economizer 1, the medium-temperature economizer 2 and the low-temperature economizer 3 are arranged in sequence from top to bottom, and each economizer is supported on the steel structure 4 by a support leg;

[0026] The upper end of the high-temperature economizer 1 has a high-temperature economizer inlet flue, the lower end of the high-temperature economizer 1 and the upper end of the medium-temperature economizer 2, as well as the lower end of the medium-temperature economizer 2 and the upper end of the low-temperature economizer 3 are connected by connecting flues respectively, and the lower end of the low-temperature economizer 1 has a low-temperature economizer outlet flue, the high-temperature economizer inlet flue, the high-temperature economizer shell, the medium-temperature economizer shell, the low-temperature economizer shell, the low-temperature economizer outlet flue and the connecting flues together form a vertical flue 5.

[0027] The water inlet of the low-temperature economizer 3 is externally connected to the boiler feed water main, and the water outlet of the low-temperature economizer 3 and the water inlet of the medium-temperature economizer 2, as well as the water outlet of the medium-temperature economizer 2 and the water inlet of the high-temperature economizer 1 are connected via connecting pipes respectively; the water outlet of the high-temperature economizer 1 is connected to the waste heat boiler drum of the heating furnace.

[0028] The high-temperature economizer inlet flue and the low-temperature economizer outlet flue are connected to the hot flue gas channel 101 and the cold flue gas channel 102 of the heating furnace 100 through pipes one by one. An induced draft fan 6 is arranged between the low-temperature economizer outlet flue and the cold flue gas channel 102 of the heating furnace 100.

[0029] The hot flue gas of the heating furnace 100 flows from top to bottom along the vertical flue 5, while the deoxygenated water in the boiler feed water main flows from bottom to top, and the two sides exchange heat in countercurrent. The high-temperature flue gas flows from top to bottom to release the flue gas waste heat, and the low-temperature deoxygenated water flows from bottom to top to absorb the flue gas waste heat and then feed water to the waste heat boiler drum.

[0030] Please see again Figure 5 Each economizer adopts a modular structure, and is composed of a shell 24 and an upper header 22, a lower header 23 and a plurality of tube bundles 21 arranged therein; the plurality of tube bundles 21 are used to absorb the waste heat of the flue gas in the vertical flue 5 and transfer heat to the boiler feed water in the tube bundles; the upper header 22 is used as a water outlet to collect the boiler feed water of the plurality of tube bundles and lead them out uniformly; the lower header 23 is used as a water inlet to distribute water from the boiler feed water main to the plurality of tube bundles; the shell 24 is used to seal the flue gas and provide space for heat exchange between the flue gas and the boiler feed water.

[0031] The utility model is an external downward waste heat recovery system for a heating furnace, and the heat exchange tube bundles of each economizer are arranged in a corresponding shell; low-temperature deoxygenated water enters from the lower water inlet of the low-temperature economizer 3, and enters the lower water inlet of the medium-temperature economizer 2 after exiting from the upper water outlet of the low-temperature economizer 3. The upper water outlet of the medium-temperature economizer 2 is connected to the water inlet of the high-temperature economizer 3, and the hot water at the outlet of the high-temperature economizer 3 goes directly to the waste heat boiler drum of the heating furnace. Each economizer is not arranged at the top of the heating furnace, but is arranged on the ground in a way that the flue gas is led down. The high-temperature flue gas flows from top to bottom, and the cold water in the corresponding economizer flows from bottom to top to form a countercurrent heat exchange. After the cold water absorbs heat and heats up, it rises accordingly, effectively avoiding the defects of steam-water stratification, the sudden increase of steam-water resistance in the economizer, and the difficulty of water supply to the steam drum.

[0032] In summary, the external downward waste heat recovery system for the heating furnace of the utility model has the advantages of flexible layout, reasonable flue gas flow, smooth water circulation, and easy installation, inspection and maintenance of equipment. Since it has a larger layout space after being externally placed, the heating surface can be sufficiently arranged, which can effectively improve the thermal efficiency of the heating furnace and reduce the energy consumption of the device.

[0033] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. An external downward waste heat recovery system for a heating furnace, characterized in that: It includes steel structure, high temperature economizer, medium temperature economizer and low temperature economizer, among which: The steel structure is fixed on the open space beside the heating furnace; The high-temperature economizer, the medium-temperature economizer and the low-temperature economizer are arranged in sequence from top to bottom, and each economizer is supported on the steel structure by supporting legs; The upper end of the high-temperature economizer is provided with a high-temperature economizer inlet flue, the lower end of the high-temperature economizer and the upper end of the medium-temperature economizer, as well as the lower end of the medium-temperature economizer and the upper end of the low-temperature economizer are respectively connected via connecting flues, the lower end of the low-temperature economizer is provided with a low-temperature economizer outlet flue, the high-temperature economizer inlet flue, the shell of the high-temperature economizer, the shell of the medium-temperature economizer, the shell of the low-temperature economizer, the low-temperature economizer outlet flue and the connecting flues together form a vertical flue; The water inlet of the low-temperature economizer is externally connected to the boiler feed water main, and the water outlet of the low-temperature economizer and the water inlet of the medium-temperature economizer, as well as the water outlet of the medium-temperature economizer and the water inlet of the high-temperature economizer are respectively connected by connecting pipes; the water outlet of the high-temperature economizer is connected to the waste heat boiler drum of the heating furnace.

2. The external downward waste heat recovery system for a heating furnace according to claim 1, characterized in that: The high-temperature economizer inlet flue and the low-temperature economizer outlet flue are connected to the hot flue gas channel and the cold flue gas channel of the heating furnace through pipelines in a one-to-one correspondence.

3. The external downward waste heat recovery system for a heating furnace according to claim 2, characterized in that: An induced draft fan is arranged between the low-temperature economizer outlet flue and the cold flue gas channel of the heating furnace.

4. The external downward waste heat recovery system for a heating furnace according to claim 1, characterized in that: The hot flue gas from the heating furnace flows from top to bottom along the vertical flue, while the deoxygenated water in the boiler feed water main flows from bottom to top, and the two sides exchange heat in countercurrent.

5. The external downward waste heat recovery system for a heating furnace according to claim 1, characterized in that: Each economizer adopts a modular structure, consisting of a shell and an upper header, a lower header and multiple tube bundles arranged therein; The multiple groups of tube bundles are used to absorb the flue gas waste heat in the vertical flue and transfer heat to the boiler feed water in the tube bundles; The upper header is used as a water outlet to collect boiler feed water from the multiple tube bundles and lead them out uniformly; The lower header acts as a water inlet, and is used to distribute water from the boiler feed water main to the multiple tube bundles; The shell is used to seal the flue gas and provide a space for heat exchange between the flue gas and boiler feed water.

Images