Single-boiler-barrel double-boiler-shell waste heat boiler structure

Abstract

The utility model belongs to heat exchange devices, and particularly relates to a single-boiler-barrel double-boiler-shell waste heat boiler structure which comprises a boiler barrel unit, a first boiler shell unit and a second boiler shell unit, and the boiler barrel unit is located on the upper portion of the first boiler shell unit and the upper portion of the second boiler shell unit. The upper portion of the first boiler shell unit and the upper portion of the second boiler shell unit are communicated with the boiler barrel unit through ascending pipes, each of the first boiler shell unit and the second boiler shell unit comprises a barrel body and a pipe plate, the pipe plate is of a flexible pipe plate structure, and the ascending pipes are made of carbon steel in a forged mode. The connecting positions of the first boiler shell unit, the second boiler shell unit and the ascending pipes are the front ends of the upper portions of the first boiler shell unit and the second boiler shell unit, and the inner diameter of at least one ascending pipe is larger than or equal to 350 mm. One boiler barrel unit can be saved, the steel consumption is reduced while the gas production rate is not affected, the number of equipment is reduced, and convenience in maintenance and stable operation of the device are facilitated.

Description

Technical Field

[0001] The invention relates to a heat exchange device in a waste heat recovery system of chemical production, in particular to a single-drum double-shell waste heat boiler structure with a fixed flue gas channel and which utilizes water evaporation to recover chemical flue gas. Background Art

[0002] Waste heat boiler is the main heat exchange equipment in the chemical waste heat recovery system. In traditional technology, a waste heat boiler is usually installed at the outlet of the sulfur incinerator, that is, a structure with two boiler shells and two boiler drums is installed at the outlet of the sulfur incinerator to ensure the steam production;

[0003] However, due to the number of boiler shells and boiler drums, the amount of steel used for the boiler shells and boiler drums is relatively large, and the increase in the number of boiler shells and boiler drums increases the equipment failure rate and the difficulty of maintenance, affecting the smooth operation of the device. Summary of the invention

[0004] The purpose of the present invention is to provide a single-drum double-shell waste heat boiler structure, which can save a drum unit, save steel consumption without affecting gas production, reduce the number of equipment, and facilitate maintenance and smooth operation of the device.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A single-drum double-shell waste heat boiler structure comprises a drum unit, a first shell unit and a second shell unit. The drum unit is located above the first shell unit and the second shell unit. The upper part of the first shell unit and the upper part of the second shell unit are both connected to the drum unit through a riser.

[0007] Furthermore, the first boiler shell unit and the second boiler shell unit both include a cylinder and a tube sheet, the tube sheet adopts a flexible tube sheet structure, the flexible tube sheet structure is subjected to ANSYS finite element analysis intelligent calculation, and the ANSYS finite element analysis intelligent calculation includes the following steps:

[0008] Analyze the influence of flexible tube sheets under different R-arcs on the thermal expansion stability of equipment and select the best R-arc structure;

[0009] If the location with higher stress value appears in the transition area of ​​tube sheet during calculation, it shall be adjusted according to the result of finite element analysis;

[0010] If high stress values ​​occur at the tube-to-tubesheet weld joints, they can be reduced by increasing the size of the weld joints;

[0011] After adding the temperature field, thermodynamic calculation and temperature field simulation methods are used to control the temperature difference to prevent excessive temperature stress. If the temperature difference is greater than the warning value, the water circulation is enhanced to accelerate the flow of water, take away heat and reduce the temperature difference.

[0012] Furthermore, the riser is forged from carbon steel.

[0013] Furthermore, the connection position of the first pot shell unit, the second pot shell unit and the riser is the front end of the upper part of the first pot shell unit and the second pot shell unit.

[0014] Furthermore, the inner diameter of at least one of the riser pipes is ≥350 mm.

[0015] Furthermore, the first boiler shell unit and the second boiler shell unit are both fire tube boilers.

[0016] The technical effects achieved by the present invention are:

[0017] The single-drum double-shell waste heat boiler structure of the present invention adopts a double-shell single-drum unit natural circulation boiler, which is arranged in the open air and connected by a pipe system. This structure is different from the traditional waste boiler and will save a drum unit. It will save steel consumption without affecting the gas production, reduce the number of equipment, and help facilitate maintenance and smooth operation of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the present invention.

[0019] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0020] 1. Boiler drum unit; 2. First boiler shell unit; 3. Second boiler shell unit; 4. Riser; 5. Downcomer. DETAILED DESCRIPTION

[0021] In order to make the purpose and advantages of the present invention more clearly understood, the present invention is specifically described below in conjunction with embodiments. It should be understood that the following text is only used to describe one or several specific embodiments of the present invention, and does not strictly limit the scope of protection of the specific claims of the present invention.

[0022] like Figure 1 As shown, a single-drum double-shell waste heat boiler structure comprises a drum unit 1, a first shell unit 2 and a second shell unit 3;

[0023] The drum unit 1 is used for steam-water separation and steam purification, forming a water circulation loop and storing boiler water. Its main functions are to receive water from the economizer, separate steam from water, supply water to the circulation loop, and deliver saturated steam to the superheater.

[0024] In addition, a certain amount of water is stored in the drum unit 1, which has a certain amount of heat and working fluid storage. When the working conditions change, the speed of steam pressure change can be slowed down. When the water supply and load are not coordinated for a short time, it plays a certain buffering role. The drum unit 1 is equipped with internal devices to perform steam-water separation, steam cleaning, pot dosing, and continuous sewage discharge to ensure steam quality;

[0025] Among them, the first boiler shell unit 2 and the second boiler shell unit 3 can both be fire tube boilers. The tube-side circulation medium is the flue gas from the smoke box of the sulfur incinerator, and the shell-side circulation medium is water. The main function is to heat water through high-temperature flue gas to form water vapor that enters the boiler drum unit 1 to form a water circulation loop and store water.

[0026] The first shell unit 2 and the second shell unit 3 both include a cylinder and a tube sheet. Since the first shell unit 2 and the second shell unit 3 have a high operating temperature, in order to effectively absorb the stress caused by the temperature difference between the shell cylinder and the heat exchange tube, the shell tube sheet adopts a flexible tube sheet structure and performs ANSYS finite element analysis and intelligent calculation to ensure the safety and reliability of the structure.

[0027] Here, the ANSYS finite element analysis intelligent calculation includes the following steps:

[0028] Analyze the impact of flexible tube sheets under different R arcs on the thermal expansion stability of equipment, select the best R arc structure, and ensure the intrinsic safety of the equipment;

[0029] When calculating, pay attention to the range of stress values ​​in various parts of the tube sheet: if the parts with higher stress values ​​appear in the transition zone of the tube sheet, adjust them according to the results of finite element analysis; if the high stress value appears in the tube-to-tube sheet weld joint, increase the size of the weld joint to reduce it;

[0030] After adding the temperature field, thermodynamic calculation and temperature field simulation methods are used to control the temperature difference to prevent excessive temperature stress. If the temperature difference is greater than the warning value, the water circulation is enhanced to accelerate the flow of water, take away heat and reduce the temperature difference.

[0031] The method for enhancing water circulation here is to increase the number of downcomers 5 and adjust the distance between heat exchange tubes to accelerate water circulation, while also assisting with water flow field analysis to ensure smooth water circulation.

[0032] Since the medium of this equipment contains Na ions, stress corrosion is prone to occur. In order to prevent stress corrosion damage, the spacing between heat exchange tubes is increased to avoid the superposition of manufacturing residual stress. After manufacturing, overall stress relief heat treatment is adopted, which can greatly reduce the stress value. At the same time, in order to reduce the occurrence of gap corrosion, the tube sheet is planned to use a smaller gap for welding and expansion. Intelligent mechanical finishing drilling is used during manufacturing to reduce the diameter of the tube hole and improve the processing accuracy of the tube hole. Reduce the gap between the tube hole and the heat exchange tube, thereby controlling the occurrence of gap corrosion.

[0033] The boiler drum unit 1 is located at the upper part of the first boiler shell unit 2 and the second boiler shell unit 3. The upper part of the first boiler shell unit 2 and the upper part of the second boiler shell unit 3 are both connected to the boiler drum unit 1 through the riser 4, which is used to circulate water vapor from the boiler shell into the boiler drum unit 1. At the same time, the riser 4 is preferably forged from carbon steel, taking into account the supporting effect on the boiler drum unit 1, thereby saving the material cost of the saddle of the boiler drum unit 1.

[0034] Moreover, the connection position of the first boiler shell unit 2, the second boiler shell unit 3 and the riser 4 is preferably the front end of the upper part of the first boiler shell unit 2 and the second boiler shell unit 3. The riser 4 should be designed to have a larger diameter and be arranged forward while meeting the conditions of structure and strength, so as to facilitate the large amount of steam generated at the front of the boiler shell to rise quickly to the drum unit 1, avoiding local high temperature due to poor heat exchange at the front of the boiler shell. At least one of the two riser pipes 4 should have an inner diameter ≥350mm so that it can be used as a manhole, head hole, and hand hole during the boiler shell manufacturing process.

[0035] The lower parts of the first boiler shell unit 2 and the second boiler shell unit 3 are connected to the boiler drum unit 1 through the downcomer 5, and the water separated by the steam-water separation device in the boiler drum unit 1 flows back to the first boiler shell unit 2 or the second boiler shell unit 3 to form a water circulation loop.

[0036] The working principle of the present invention is as follows: the drum unit 1 receives water from the economizer, performs steam-water separation and supplies water to the circulation loop, and delivers saturated steam to the superheater;

[0037] The water separated from the boiler drum unit 1 enters the interior of the first boiler shell unit 2 and the second boiler shell unit 3 through the downcomer 5, and is converted into steam by the first boiler shell unit 2 and the second boiler shell unit 3, and then is input into the interior of the boiler drum unit 1 through the riser 4.

[0038] In summary, this technical solution adopts a double-boiler shell single-drum unit 1 natural circulation boiler, which is arranged in the open air and connected by a pipe system. This structure is different from the traditional waste boiler in which one drum unit 1 is equipped with one boiler shell. It will save one drum unit 1, save steel consumption without affecting the gas production, reduce the number of equipment, and help facilitate maintenance and smooth operation of the device.

[0039] The above is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications should also be considered as the protection scope of the present invention. The structures, devices and operating methods not specifically described and explained in the present invention shall be implemented according to the conventional means in the art unless otherwise specified and limited.

Claims

1. A single-drum double-shell waste heat boiler structure, characterized in that: The invention comprises a boiler drum unit (1), a first boiler shell unit (2) and a second boiler shell unit (3); the boiler drum unit (1) is located above the first boiler shell unit (2) and the second boiler shell unit (3); the upper part of the first boiler shell unit (2) and the upper part of the second boiler shell unit (3) are both connected to the boiler drum unit (1) via a riser (4).

2. The single-drum double-shell waste heat boiler structure according to claim 1 is characterized in that: The first boiler shell unit (2) and the second boiler shell unit (3) both comprise a cylinder, a tube sheet and a heat exchange tube, and the tube sheet adopts a flexible tube sheet structure.

3. The single-drum double-shell waste heat boiler structure according to claim 1 is characterized in that: The riser (4) is made of forged carbon steel.

4. The single-drum double-shell waste heat boiler structure according to claim 1 is characterized in that: The connection position between the first pot shell unit (2), the second pot shell unit (3) and the riser (4) is the front end of the upper part of the first pot shell unit (2) and the second pot shell unit (3).

5. The single-drum double-shell waste heat boiler structure according to claim 1 is characterized in that: The inner diameter of at least one of the riser pipes (4) is ≥350 mm.

6. The single-drum double-shell waste heat boiler structure according to claim 1, characterized in that: The first boiler shell unit (2) and the second boiler shell unit (3) are both fire tube boilers.

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