Furnace wall of ethylene cracking furnace

Abstract

The utility model discloses a furnace wall of an ethylene cracking furnace, which is matched with a flat flame burner for use, and a burner brick is square outside and round inside and is matched with a heat storage layer in size. The furnace wall comprises a heat storage layer, a heat insulation layer, a heat preservation layer and a heat preservation plate layer from inside to outside; the two sides of the heat insulation layer are embedded in brick joints of the heat storage layer and the heat preservation layer respectively. Or the heat insulation layer is divided into an inner heat insulation layer and an outer heat insulation layer, the outer heat insulation layer is arranged in the heat preservation layer, the heat preservation layer is divided into an inner heat preservation layer and an outer heat preservation layer, and the inner heat insulation layer is located between the heat storage layer and the inner heat preservation layer. The thickness of the heat insulation layer is 4-10 mm. The novel paste aerogel heat insulation material is applied to the furnace wall structure, so that the heat insulation capacity of the furnace wall is improved, and the heat insulation layer is quick and convenient to construct and detect.

Description

Technical Field

[0001] The utility model is applied to the field of ethylene manufacturing and relates to an ethylene cracking furnace, in particular to a furnace wall heat insulation structure of the cracking furnace. Background Art

[0002] The ethylene cracking furnace is one of the most important equipment in the petrochemical plant. The furnace includes a radiation zone and a convection zone. The convection zone is used to preheat the raw materials, and the radiation zone is used to crack the raw materials. The temperature of the radiation zone is usually around 1000°C, and the heat exchange accounts for about 50% of the entire cracking furnace. Therefore, the thermal insulation performance of the cracking furnace wall structure is directly related to the cost of ethylene production. CN203269870U discloses a high-temperature insulating refractory brick and its lining structure for an ethylene cracking furnace. The insulating refractory brick is a polyhedron with a T-shaped or Z-shaped cross section. It is laid and arranged along the furnace wall. The sides of adjacent refractory bricks are adapted to overlap to form a zigzag joint, eliminating the through seams between the brick joint surfaces and avoiding heat dissipation losses. CN203947074U discloses a cracking furnace wall reinforced heat transfer lining structure, wherein a reinforced heat transfer refractory brick is arranged on the lining wall, wherein a corner of the reinforced heat transfer refractory brick is cut off along the length direction, and the cut corner is arc-shaped or triangular in cross section, so as to increase the heating area and the radiation area and enhance the radiation heat transfer. CN213901911U discloses an ethylene cracking furnace and a composite heat insulation layer of the inner wall of the furnace bottom, wherein the furnace bottom is fitted with a flat layer for increasing the heat preservation effect, and the gaps between the refractory bricks above the flat layer are filled with sealed refractory mud powder. Each layer of refractory bricks has an expansion joint of 1.4-1.6 mm, and the expansion joint is filled with a strip-shaped fiber blanket and an adhesive for fixing the fiber blanket. The composite heat insulation layer of the inner wall of the furnace bottom of the ethylene cracking furnace has a small heat dissipation, is easy to install, does not need to bake the furnace, and has a good heat preservation effect. The above three patents are only partially improved on the basis of the existing technology, and have not achieved a revolutionary heat preservation effect. Utility Model Content

[0003] The technical problem solved by the utility model is: the aerogel insulation material is used for the furnace wall structure, the construction is convenient, the insulation effect is good, and the heat storage layer is set to avoid the adverse effect of the burner working fluctuation on the furnace temperature.

[0004] The technical solution adopted by the utility model is that the furnace wall of the ethylene cracking furnace of the utility model is used in conjunction with a flat flame burner, and comprises a heat storage layer, a heat insulation layer, a thermal insulation layer and a thermal insulation board layer from the inside to the outside; the thickness of the thermal insulation layer is 5-10mm, and the two sides are respectively embedded in the brick seams of the heat storage layer and the thermal insulation layer.

[0005] Preferably, the thermal conductivity of the thermal insulation layer at 1000° C. is not greater than 0.035 W / (mK).

[0006] Preferably, the heat insulation layer is divided into an inner heat insulation layer and an outer heat insulation layer, the outer heat insulation layer is arranged in the heat preservation layer, and the heat preservation layer is divided into an inner heat insulation layer and an outer heat insulation layer; the inner heat insulation layer is located between the heat storage layer and the inner heat insulation layer. The thickness of the inner heat insulation layer and the outer heat insulation layer is 4-7 mm.

[0007] Preferably, the burner bricks of the flat flame burner are square outside and round inside, matching the size of the heat storage layer.

[0008] The utility model has the following beneficial effects: the utility model applies the new aerogel insulation material to the furnace wall structure, improves the insulation and heat preservation capacity of the furnace wall, and saves energy. The construction and detection of the paste aerogel insulation material are quick and convenient. The thermal storage layer is used to radiate and heat the cracking tube, thereby avoiding the influence of the working fluctuation of the burner on the temperature of the cracking furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a schematic diagram of the furnace wall structure of Example 1;

[0010] Figure 2 is a schematic diagram of the furnace wall structure of Example 2;

[0011] In the figure: 1-heat storage layer, 2-insulating layer, 3-thermal insulation layer, 4-insulating board layer, 5-outer wall, 6-burner, 7-burner brick, 8-insulating coating;

[0012] 21-inner insulation layer, 22-outer insulation layer;

[0013] 31 - inner insulation layer; 32 - outer insulation layer. DETAILED DESCRIPTION

[0014] The inside and outside mentioned below refer to the direction from the furnace cavity to the furnace body, the furnace cavity is inside, and the outside of the furnace body is outside, that is, the left side of the accompanying drawing is inside, and the right side is outside.

[0015] Example 1.

[0016] The wall structure of the cracking furnace in this embodiment is shown in the attached figure. Figure 1 As shown, from the inside out, it includes a heat storage layer 1, a heat insulation layer 2, a thermal insulation layer 3, a thermal insulation board layer 4 and an outer wall 5.

[0017] The heat storage layer 1 is built with heat storage bricks, the inner side of which is in direct contact with the high-temperature furnace gas for radiation heating, and the outer side is in close contact with the insulation layer 2. Requirements for heat storage bricks: 1) High temperature resistance and high high temperature strength, that is, high refractoriness and high softening point; 2) Good chemical stability, that is, no chemical reaction with furnace gas; 3) Good volume stability, that is, from room temperature to high temperature, it will not produce large expansion or contraction due to recrystallization or sintering; 4) It has air permeability, so that the moisture in the insulation layer can evaporate when the furnace wall is baked; 5) It has a certain heat storage capacity to ensure the stability of radiation heat transfer, and will not affect the radiation heat transfer of the heat storage layer due to the working fluctuation of the burner, that is, to ensure the hysteresis of temperature. Corundum bricks are preferably used for heat storage bricks, such as chrome corundum, aluminum corundum, etc.

[0018] The insulation layer 2 uses aerogel insulation material, which is a new product developed by a company in Handan. The base material is resistant to high temperature and uses nanopore insulation. The product is in paste form. During construction, the paste insulation material is scraped (equivalent to the operation of applying an insulation layer or cement layer on the wall surface) to the inner side of the insulation layer. After the water evaporates, it becomes an insulation layer with a thickness of 5-10mm. The circular sample plate made by drying this paste insulation material is 3.8mm thick and covered on a 2kw resistance wire heating furnace. After 24 hours, the infrared temperature measuring gun measures the temperature of the upper surface, which is only 87-96℃, and the insulation effect is excellent. According to the test of relevant testing agencies, the thermal conductivity at 1000℃ is not more than 0.035W / (m·K). Since the product cannot withstand the impact of furnace gas after drying, especially at high temperature, it is powdery and gradually thinned after being tested on the inner wall of the furnace, so it is set between the heat storage layer and the insulation layer. Considering the air heat dissipation on the upper surface of the above test sample plate, the insulation layer in the furnace wall should be thickened to ensure the insulation effect. Another advantage of the paste aerogel insulation material is that it has extrusion fluidity during construction, can fill the brick joints, ensure the bite joints of the heat storage layer and the insulation layer, and thus ensure the integrity of the furnace wall.

[0019] The insulation layer 3 is built of porous lightweight refractory bricks and is the main supporting member of the furnace wall. Lightweight clay bricks can be selected.

[0020] The insulation board layer 4 is a porous fiber material, such as an insulation asbestos board, or other insulation boards. Its main purpose is to prevent convection heat dissipation through the brick joints, while retaining a certain air permeability to facilitate the exhaust of water vapor during the drying of the furnace wall refractory bricks and the drying of the insulation layer.

[0021] The outer wall 5 is a steel plate, which is a structural member supporting the burner, temperature measuring device, pipeline and other components.

[0022] The furnace wall of this embodiment is preferably used in conjunction with a flat flame burner. The structure of the flat flame burner is shown in the patent application "A Flat Flame Burner for Cracking Furnace" (application number 2023232635794), attached Figure 1In the double-dotted line portion, the flame of the burner 6 can be spread along the inner wall of the heat storage layer, and its heat can quickly heat the heat storage layer. Figure 1 As shown, the burner brick 7 is customized, with a square outside and a round inside, matching the size of the corundum bricks in the heat storage layer. A heat-insulating coating 8 is applied to the inner end face of the burner 6 to reduce the heat dissipation caused by water cooling of the burner 6. The heat-insulating principle of the heat-insulating coating 8 is the same as that of the heat-insulating layer 2, but the material ratio is different. The performance emphasizes the bonding ability and crack prevention ability with the burner, that is, the material selection and ratio of the high-temperature adhesive and refractory fiber are different from those of the heat-insulating layer 2. The thickness of the heat-insulating coating 8 is thinner than the heat-insulating layer, generally less than 4 mm. If it is greater than 5 mm, it is easy to flake off or produce shrinkage cracks, affecting its heat-insulating performance.

[0023] When laying the bricks of this embodiment, first lay the insulation board layer 4 on the inner side of the outer wall 5, and then lay the insulation layer 3. When the position of the burner 6 is laid, the burner 6 is installed, and the inner end face of the burner is flush with the inner side of the insulation brick. After the insulation brick is laid, the paste insulation material is scraped on the inner side of the insulation brick. The paste insulation material can be embedded in the brick seam of the insulation brick and become one with the insulation brick. In order to reduce the moisture drying evaporation pressure of the insulation layer and ensure the thickness of the insulation layer, the insulation layer should be scraped twice or three times. After the current scraping, dry and evaporate the moisture. Under the condition of maintaining a certain humidity, scrape the next time to ensure that the insulation layer is bonded as a whole. The last scraping should be carried out simultaneously with the laying of the heat storage brick. The paste insulation material can be embedded in the brick seam of the heat storage brick and become one with the heat storage layer. In this way, both the inner and outer sides of the insulation layer are embedded in the brick seam, so that the heat storage layer and the insulation layer become one.

[0024] Before use, the furnace wall of this embodiment needs to be dried slowly at a low temperature for a long time, the purpose of which is to remove free water in the insulation layer, heat storage layer and thermal insulation layer to avoid the adverse effect of rapid generation of water vapor on the furnace wall.

[0025] Example 2.

[0026] The wall structure of the cracking furnace in this embodiment is shown in the attached figure. Figure 2 As shown, from the inside out, it includes a heat storage layer 1, an inner insulation layer 21, an inner thermal insulation layer 31, an outer insulation layer 22, an outer thermal insulation layer 32, an insulation board layer 4 and an outer wall 5. The main difference from Example 1 is that the insulation layer is divided into two layers, namely, an inner insulation layer 21 and an outer insulation layer 22, wherein the outer insulation layer 22 is arranged in the thermal insulation layer, and the thermal insulation layer is divided into an inner thermal insulation layer 31 and an outer thermal insulation layer 32. The thickness of the inner insulation layer 21 and the outer insulation layer 22 can be controlled at 4-7 mm, which is basically consistent with the brick joints of the wall.

[0027] Compared with Example 1, the advantages of this embodiment are: 1) It is conducive to the evaporation of free water in the insulation layer and shortens the drying time. The thickness of the insulation layer is reduced, and the evaporation of water is easier. 2) The masonry period of the furnace wall is shortened. Each layer of insulation layer only needs to be scraped once, which is suitable for simultaneous construction with refractory bricks, eliminating the drying time in between multiple scrapings in Example 1. 3) The thickness of the heat storage layer can be appropriately reduced, which helps to shorten the empty furnace heating time. The disadvantage is that the inner insulation layer 31 needs to select lightweight insulation bricks different from the outer insulation layer 32, such as lightweight clay bricks for the outer insulation layer 32, and lightweight high-alumina bricks for the inner insulation layer 31, or other refractory bricks that can withstand higher temperatures and have a small heat transfer coefficient.

[0028] The thickness of the insulation layer determines the thermal insulation effect of the furnace wall. Therefore, the thickness detection process of the insulation layer should not be sloppy. Simple special tools can be used for thickness detection. On the iron wire, make groove marks according to the thinnest required thickness of the insulation layer, or paste fluorescent strips at this position to adapt to the dim light environment of the furnace construction. After the insulation layer is scraped, immediately insert the iron wire vertically into the insulation layer. After the end of the iron wire touches the insulation brick, observe whether the mark is inserted into the insulation layer. The thickness detection is convenient and quick.

[0029] The utility model applies a new type of aerogel insulation material to the furnace wall structure, which greatly improves the insulation capacity of the furnace wall, reduces the heat dissipation of the outer wall of the cracking furnace, and lays the foundation for energy saving. The paste-like aerogel insulation material is used, and the slurry construction and thickness detection are quick and convenient. The flat flame burner is used to heat the heat storage layer, and the heat storage layer is used to radiate and heat the cracking tube, which greatly alleviates the influence of the working fluctuation of the burner on the temperature of the cracking furnace, making the cracking temperature control tend to be stable.

Claims

1. An ethylene cracking furnace wall, characterized in that: It is used in conjunction with a flat flame burner and comprises, from the inside out, a heat storage layer (1), a heat insulation layer (2), a thermal insulation layer (3) and a thermal insulation board layer (4); both sides of the heat insulation layer (2) are respectively embedded in the brick joints of the heat storage layer (1) and the thermal insulation layer (3).

2. The ethylene cracking furnace wall according to claim 1, characterized in that: The thermal conductivity of the thermal insulation layer at 1000° C. is no greater than 0.035 W / (m·K).

3. The ethylene cracking furnace wall according to claim 1, characterized in that: The thickness of the thermal insulation layer (2) is 5-10 mm.

4. The ethylene cracking furnace wall according to claim 1, characterized in that: The heat insulating layer (2) is divided into an inner heat insulating layer (21) and an outer heat insulating layer (22); the outer heat insulating layer (22) is arranged in the thermal insulation layer (3), dividing the thermal insulation layer (3) into an inner heat insulating layer (31) and an outer heat insulating layer (32); the inner heat insulating layer (21) is located between the heat storage layer (1) and the inner heat insulating layer (31).

5. The ethylene cracking furnace wall according to claim 4, characterized in that: The thickness of the inner heat insulating layer (21) and the outer heat insulating layer (22) is 4-7 mm.

6. The ethylene cracking furnace wall according to claim 1, characterized in that: The burner brick (7) of the flat flame burner is square on the outside and round on the inside, matching the size of the heat storage layer (1).

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