Lining structure in alkylation spent acid regeneration unit

Abstract

The present invention provides a lining structure in an alkylation waste acid regeneration device, comprising a first acid-resistant working lining, a high-temperature thermal insulation spray layer, a first medium-temperature thermal insulation spray layer, a first low-temperature thermal insulation spray layer, a first acid-resistant coating layer, an anti-scalding grille, a first external thermal insulation rock wool layer, a second acid-resistant working lining, a second medium-temperature thermal insulation spray layer, a second low-temperature thermal insulation spray layer, a second acid-resistant coating layer, a second external thermal insulation rock wool layer, a third acid-resistant working lining, a third medium-temperature thermal insulation spray layer, a third low-temperature thermal insulation spray layer, and a third acid-resistant coating layer. The present invention ensures that when the furnace operating temperature is not less than 1050°C and the furnace medium contains a high concentration of SO2, the shell steel plate control temperature is lower than 350°C, and when the shell steel plate control temperature is lower than 250°C, dew point corrosion can also be prevented. At the same time, the setting of the anti-scalding grille can also ensure that the external thermal insulation metal protection temperature is not more than 75°C to meet the anti-scalding requirements.

Description

Technical Field

[0001] The invention relates to the field of chemical equipment, in particular to a lining structure in an alkylation waste acid regeneration device. Background Art

[0002] Alkylation reaction is widely used in many chemical production processes as an important synthesis method. Sulfuric acid alkylation is a process in which isobutane and butene in the C4 component separated by gas distillation of catalytic cracking liquid hydrocarbons are used as raw materials, and 89% to 98% sulfuric acid is used as a catalyst to react in liquid phase at low temperature to produce high-octane gasoline component - alkylate oil. The alkylation waste sulfuric acid regeneration process is to pass the waste acid with a concentration of about 89% to 90% through the waste acid cracking furnace, incinerate, crack, oxidize, and absorb to convert it into 98% to 99.2% sulfuric acid, which can be returned to the device for recycling as an alkylation catalyst.

[0003] The 15,000 tons / year waste acid regeneration unit of the 160,000 tons / year alkylation project of PetroChina Ningxia Petrochemical Branch adopts the technology of Austrian PandP Company. The incinerator is a vertical positive U-shaped structure, divided into a cylindrical combustion chamber and a rectangular heat exchange chamber, and the bottom flue of the two chambers is connected. The burner is located at the top of the vertical cylindrical combustion chamber. The hot flue gas goes from the combustion chamber to the heat exchange chamber through the bottom flue, passes through two sets of molten salt heat exchangers, and then exits the incinerator through the upper part of the heat exchange. The characteristic of PandP's technology is that a molten salt heat exchanger is set in the incinerator. The molten salt has the advantages of wide liquid temperature range, low viscosity, good fluidity, low vapor pressure, low pressure bearing capacity of the pipeline, high relative density, high specific heat, strong heat storage capacity, and low cost. However, all pipelines are heated to keep the salt in a molten state. Therefore, in addition to the high requirements for operation, the operating temperature of the incinerator furnace cannot be lower than 1050℃, and the design temperature of the furnace lining reaches 1500℃. To ensure the long-term normal operation of the equipment, the metal operating temperature of the shell should be kept below 350°C, and when the metal operating temperature of the shell is below 250°C, dew point corrosion should be prevented, and the metal protection temperature of the outer insulation layer should be kept below 75°C. And because the incineration medium contains a high concentration of SO2, the requirements for the equipment lining are particularly strict.

[0004] The total thickness of the inner lining of the incinerator of the waste acid regeneration unit of Ningxia Petrochemical and similar incinerators currently in use in China is 350mm. The lining structure of the high-temperature flue gas section from the combustion chamber to the lower part of the heat exchanger in the heat exchange chamber is generally: from the fire surface to the outside, 120mm thick acid-resistant heavy castable + 150mm thick lightweight castable + 35mm thick ceramic fiberboard + 45mm thick nanoboard, and the external insulation is wrapped with 60mm thick rock wool + 1mm thick aluminum skin. During the commissioning stage, the metal temperature of the shell exceeded the standard at some local temperature measurement points, and some reached more than 400 degrees Celsius. Long-term use has a great impact on the shell strength. It can also be determined that there is heat leakage at the over-temperature point, and the lining in the over-temperature area must have a failure problem. Because the anchors are evenly arranged, the influence of the anchors on the temperature of the bridge wall can be eliminated. There should be a penetrating crack in the internal lining.

[0005] After analysis, it is found that for micro-positive pressure furnaces, this lining structure has problems such as too thin heavy layer, too many backing layers, and insufficient backing strength. Generally, a micro-positive pressure furnace with sufficient lining strength can withstand a certain pressure to ensure that the lining diameter does not change. Only when the material expands and contracts normally, the expansion joints reserved during lining construction can meet the requirements and will not cause large cracks. However, if the lining strength is not sufficient, when the furnace expands due to heat, the lining diameter will increase due to the positive pressure in the furnace, and the backing materials are all soft materials, and the strength is not enough to resist the expansion of the inner layer of castables. In this case, the internal cracks of the castable lining will inevitably become abnormally larger, and it is easy to form permeable cracks. When the furnace is shut down and cooled, the furnace body shrinks, and the expansion of the lining material cannot be enough to compensate for the cracks, thus forming permanent and irreparable cracks. Running again will inevitably cause heat leakage. In addition, the backing materials used are 35mm ceramic fiber board and 45mm nano board, both of which are assembled from boards of certain specifications and sizes. Since the boards are thick and are not made into curved boards according to the specifications of the cylindrical furnace, not only is the construction difficult, but the gap between the boards cannot be guaranteed, which may also be one of the causes of heat leakage. Summary of the invention

[0006] Based on this, it is necessary to provide a lining structure in an alkylation waste acid regeneration device that can prevent dew point corrosion while ensuring that the incineration temperature of the incinerator used for the waste acid regeneration device is not less than 1050°C and the medium in the furnace contains a high concentration of SO2, in order to address the deficiency of the background technology that the metal temperature of the shell at the local temperature measuring point reaches more than 400 degrees Celsius, causing heat leakage.

[0007] A lining structure in an alkylation waste acid regeneration device comprises a first acid-resistant working lining, a high-temperature thermal insulation spray layer, a first medium-temperature thermal insulation spray layer, a first low-temperature thermal insulation spray layer, a first acid-resistant paint layer, an anti-scalding grille, a first external thermal insulation rock wool layer, a second acid-resistant working lining, a second medium-temperature thermal insulation spray layer, a second low-temperature thermal insulation spray layer, a second acid-resistant paint layer, a second external thermal insulation rock wool layer, a third acid-resistant working lining, a third medium-temperature thermal insulation spray layer, a third low-temperature thermal insulation spray layer, and a third acid-resistant paint layer.

[0008] The burner high temperature zone is within 4 meters below the corresponding burner in the combustion chamber, the U-shaped zone between 500 mm below the heat exchanger and the burner high temperature zone is the high temperature zone, the bottom of the incinerator is the furnace bottom zone, and the inner wall of the shell steel plate in the burner high temperature zone is provided with a first acid-resistant working lining, a high temperature thermal insulation spray layer, a first medium temperature thermal insulation spray layer, a first low temperature thermal insulation spray layer, and a first acid-resistant paint layer from the inside to the outside, and the outer wall of the shell steel plate in the burner high temperature zone is provided with a first external thermal insulation rock wool layer, and the inner wall of the shell steel plate in the high temperature zone is provided with a second acid-resistant working lining, a second medium temperature thermal insulation spray layer, a second low temperature thermal insulation spray layer, and a second acid-resistant paint layer from the inside to the outside, and the outer wall of the shell steel plate in the high temperature zone is provided with a second external thermal insulation rock wool layer, and the inner wall of the furnace bottom steel plate in the furnace bottom zone is provided with a third acid-resistant working lining, a third medium temperature thermal insulation spray layer, a third low temperature thermal insulation spray layer, and a third acid-resistant paint layer from top to bottom.

[0009] In one of the embodiments, the present invention further comprises an anti-scalding grille, which is arranged between the shell steel plate of the high temperature zone of the burner and the first outer thermal insulation rock wool layer.

[0010] In one embodiment, the thickness of the first acid-resistant working lining is 150 mm, the thickness of the high-temperature thermal insulation spray layer is 50 mm, the thickness of the first medium-temperature thermal insulation spray layer is 70 mm, the thickness of the first low-temperature thermal insulation spray layer is 147 mm, the thickness of the first acid-resistant coating layer is 3 mm, the thickness of the shell steel plate in the high-temperature zone of the burner is 16 mm, the thickness of the anti-scalding grille is greater than or equal to 200 mm, and the thickness of the first outer thermal insulation rock wool layer is 20 mm. The thickness of the second acid-resistant working lining is 150 mm, the thickness of the second medium-temperature thermal insulation spray layer is 120 mm, the thickness of the second low-temperature thermal insulation spray layer is 147 mm, the thickness of the second acid-resistant coating layer is 3 mm, the thickness of the shell steel plate in the high-temperature zone is 16 mm, and the thickness of the second outer thermal insulation rock wool layer is 20 mm.

[0011] The thickness of the third acid-resistant working lining is 150mm, the thickness of the third medium-temperature insulation spray layer is 120mm, the thickness of the third low-temperature insulation spray layer is 147mm, the thickness of the third acid-resistant coating layer is 3mm, and the thickness of the bottom steel plate in the furnace bottom area is 20mm.

[0012] In one embodiment, the first acid-resistant working lining, the second acid-resistant working lining, and the third acid-resistant working lining are all made of ZTEK85 material.

[0013] In one of the embodiments, the high-temperature thermal insulation spray layer is made of INSLC2690LI material.

[0014] In one embodiment, the first medium-temperature thermal insulation spray layer, the second medium-temperature thermal insulation spray layer, and the third medium-temperature thermal insulation spray layer are all made of INSLC2470 material.

[0015] In one embodiment, the first low-temperature thermal insulation spray layer, the second low-temperature thermal insulation spray layer, and the third low-temperature thermal insulation spray layer are all made of INSLC2025 material.

[0016] In one embodiment, the first acid-resistant coating layer, the second acid-resistant coating layer, and the third acid-resistant coating layer are all made of CWBSIL material.

[0017] In one embodiment, the first outer thermal insulation rock wool layer and the second outer thermal insulation rock wool layer are both made of rock wool material.

[0018] Advantages and beneficial effects of the present invention:

[0019] The present invention ensures that the shell steel plate temperature is controlled below 350°C when the furnace operating temperature is not less than 1050°C and the medium in the furnace contains high concentration of SO2. When the shell steel plate temperature is controlled below 250°C, dew point corrosion can be prevented. At the same time, the provision of the anti-scalding grille can also ensure that the external insulation metal protection temperature is not greater than 75°C to meet the anti-scalding requirements.

[0020] 1. The present invention takes into account that the lining must have sufficient strength to prevent the occurrence of through cracks during expansion and contraction and cause heat leakage, and selects thermal insulation spray coatings (i.e., high-temperature thermal insulation spray coatings, medium-temperature thermal insulation spray coatings and low-temperature thermal insulation spray coatings in the present invention) with high strength, no elastic compression, high temperature resistance, and not affected by the shape of the furnace and suitable for various occasions as the thermal insulation lining.

[0021] 2. The present invention takes into account that the medium contains a large amount of acidic gas, and selects a refractory castable that does not contain calcium aluminate cement for the lining of the fire surface. In addition, the operating temperature of the furnace is high, not less than 1050°C, and temperature fluctuations may occur during operation, so it is necessary to use a refractory castable with excellent thermal shock resistance. Finally, the present invention selects the first acid-resistant working lining, the second acid-resistant working lining, and the third acid-resistant working lining made of ZTEK 85 material as the refractory layer of the fire surface. To ensure sufficient strength, the thickness of each lining is 150 mm.

[0022] 3. The present invention takes into account the large temperature difference between the inside and outside of the furnace. The normal working condition is from 1050℃ to 350℃, and it is necessary to use a lightweight castable with good thermal insulation performance. However, the better the thermal insulation effect of the castable, the lower the temperature resistance. After comprehensive analysis and calculation, medium-quality castables with different temperature resistance are required as transition layers. According to the temperature distribution of the furnace and the structure of the furnace body, the present invention divides three areas, namely the burner high temperature area, the high temperature area, and the furnace bottom area, and optimizes and adjusts the lining structure respectively.

[0023] 4. Check the low-limit low-temperature working conditions, that is, the operating temperature is 1050°C, the ambient temperature is -27.7°C, and there is no wind. The calculated value of the shell steel plate wall temperature is 250°C lower than the process requirement. Dew point corrosion may occur. The operating temperature can be slightly increased. Considering the difficulty in control, the present invention provides an acid-resistant coating layer to prevent the occurrence of dew point corrosion.

[0024] 5. While ensuring that the metal wall temperature of the shell does not exceed the lining structure required by the process temperature, the calculated value of the external thermal insulation protection metal layer exceeds the anti-scalding temperature under high temperature conditions. In order to solve this problem, the present invention provides an anti-scalding grille of not less than 200 mm to form an air interlayer. Due to the large thermal resistance of air, it can effectively isolate and cool down the shell steel plate to ensure that the metal wall temperature does not exceed the temperature while achieving the effect of isolation and cooling, so that the external thermal insulation meets the anti-scalding requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of the incinerator in the alkylation waste acid regeneration device of the present invention.

[0026] Figure 2 It is a schematic diagram of the lining structure of the high temperature zone of the burner of the present invention.

[0027] Figure 3 It is a schematic diagram of the lining structure in the high temperature zone of the present invention.

[0028] Figure 4 It is a schematic diagram of the lining structure of the furnace bottom area of ​​the present invention. DETAILED DESCRIPTION

[0029] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0030] It should be noted that when an element is referred to as being “disposed on” another element, it may be directly on the other element or there may be a central element.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0032] Example 1

[0033] See also Figures 1 to 4 A lining structure in an alkylation waste acid regeneration device includes a first acid-resistant working lining 11, a high-temperature thermal insulation spray layer 12, a first medium-temperature thermal insulation spray layer 13, a first low-temperature thermal insulation spray layer 14, a first acid-resistant paint layer 15, an anti-scalding grille 17, a first external thermal insulation rock wool layer 18, a second acid-resistant working lining 21, a second medium-temperature thermal insulation spray layer 22, a second low-temperature thermal insulation spray layer 23, a second acid-resistant paint layer 24, a second external thermal insulation rock wool layer 26, a third acid-resistant working lining 31, a third medium-temperature thermal insulation spray layer 32, a third low-temperature thermal insulation spray layer 33, and a third acid-resistant paint layer 34.

[0034] like Figure 1 , the area within 4 meters below the corresponding burner in the combustion chamber 4 is the burner high temperature zone 1. The U-shaped area between 500 mm below the heat exchanger 6 and the burner high temperature zone 1 is the high temperature zone 2. The bottom of the incinerator 7 is the furnace bottom zone 3. It should be noted that: Figure 1 The area within A is the burner high temperature zone 1, the area within B is the high temperature zone 2, and the area within C is the furnace bottom zone 3. L represents 500 mm.

[0035] like Figure 2 The inner wall of the shell steel plate 5 of the high temperature zone 1 of the burner is provided with a first acid-resistant working lining 11, a high temperature thermal insulation spray layer 12, a first medium temperature thermal insulation spray layer 13, a first low temperature thermal insulation spray layer 14, and a first acid-resistant coating layer 15 in sequence from the inside to the outside. The outer wall of the shell steel plate 5 of the high temperature zone 1 of the burner is provided with a first external thermal insulation rock wool layer 18. Among them, the anti-scalding grille 17 is arranged between the shell steel plate 5 of the high temperature zone 1 of the burner and the first external thermal insulation rock wool layer 18.

[0036] like Figure 3 The inner wall of the shell steel plate 5 of the high temperature zone 2 is provided with a second acid-resistant working lining 21, a second medium temperature thermal insulation spray layer 22, a second low temperature thermal insulation spray layer 23, and a second acid-resistant coating layer 24 in sequence from the inside to the outside. The outer wall of the shell steel plate 5 of the high temperature zone 2 is provided with a second outer thermal insulation rock wool layer 26.

[0037] like Figure 4 A third acid-resistant working lining 31, a third medium-temperature thermal insulation spray layer 32, a third low-temperature thermal insulation spray layer 33, and a third acid-resistant coating layer 34 are sequentially arranged on the inner side wall of the furnace bottom steel plate 8 of the furnace bottom area 3 from top to bottom.

[0038] Specifically, the thickness of the first acid-resistant working lining 11 is 150 mm, the thickness of the high-temperature thermal insulation spray layer 12 is 50 mm, the thickness of the first medium-temperature thermal insulation spray layer 13 is 70 mm, the thickness of the first low-temperature thermal insulation spray layer 14 is 147 mm, the thickness of the first acid-resistant coating layer 15 is 3 mm, the thickness of the shell steel plate 5 of the high-temperature zone 1 of the burner is 16 mm, the thickness of the anti-scalding grille 17 is greater than or equal to 200 mm, and the thickness of the first external thermal insulation rock wool layer 18 is 20 mm.

[0039] Specifically, the thickness of the second acid-resistant working lining 21 is 150 mm, the thickness of the second medium-temperature insulation spray layer 22 is 120 mm, the thickness of the second low-temperature insulation spray layer 23 is 147 mm, the thickness of the second acid-resistant coating layer 24 is 3 mm, the thickness of the shell steel plate 5 of the high temperature zone 2 is 16 mm, and the thickness of the second outer insulation rock wool layer 26 is 20 mm.

[0040] Specifically, the thickness of the third acid-resistant working lining 31 is 150 mm, the thickness of the third medium-temperature insulation spray layer 32 is 120 mm, the thickness of the third low-temperature insulation spray layer 33 is 147 mm, the thickness of the third acid-resistant coating layer 34 is 3 mm, and the thickness of the furnace bottom steel plate 8 of the furnace bottom area 3 is 20 mm.

[0041] The first acid-resistant working lining 11 , the second acid-resistant working lining 21 , and the third acid-resistant working lining 31 are all made of ZTEK85 material.

[0042] Wherein, the high-temperature thermal insulation spray layer 12 is made of INSLC2690LI material.

[0043] The first medium-temperature thermal insulation spray layer 13, the second medium-temperature thermal insulation spray layer 22, and the third medium-temperature thermal insulation spray layer 32 are all made of INSLC2470 material.

[0044] The first low-temperature thermal insulation spray layer 14, the second low-temperature thermal insulation spray layer 23, and the third low-temperature thermal insulation spray layer 33 are all made of INSLC2025 material.

[0045] The first acid-resistant coating layer 15 , the second acid-resistant coating layer 24 , and the third acid-resistant coating layer 34 are all made of CWBSIL material.

[0046] The first outer thermal insulation rock wool layer 18 and the second outer thermal insulation rock wool layer 26 are both made of rock wool. According to the relevant lining standards and the anchoring scheme of the lining supplier, anchors are set on the inner wall of the shell, and then the lining is sprayed and built layer by layer according to the above scheme.

[0047] Table 1 is a table of lining structure materials of the present invention.

[0048] Table 1 Lining structural materials of the present invention are as follows, and relevant material data are provided by United Minerals (Tianjin) Co., Ltd.:

[0049]

[0050] The acid-resistant working lining in Table 1 includes a first acid-resistant working lining 11, a second acid-resistant working lining 21, and a third acid-resistant working lining 31; the medium-temperature thermal insulation spray layer in Table 1 includes a first medium-temperature thermal insulation spray layer 13, a second medium-temperature thermal insulation spray layer 22, and a third medium-temperature thermal insulation spray layer 32; the low-temperature thermal insulation spray layer in Table 1 includes a first low-temperature thermal insulation spray layer 14, a second low-temperature thermal insulation spray layer 23, and a third low-temperature thermal insulation spray layer 33; the acid-resistant coating layer in Table 1 includes a first acid-resistant coating layer 15, a second acid-resistant coating layer 24, and a third acid-resistant coating layer 34.

[0051] 1. Working condition analysis:

[0052] 1) Design conditions:

[0053] a) Operating temperature: The maximum operating temperature is 1250℃, the minimum operating temperature is 1050℃; the combustion chamber partial interlocking temperature is 1400℃.

[0054] b) Design requirements: The design temperature of the furnace lining is 1500℃; the shell control temperature is lower than 350℃, and the shell temperature is <350℃ when the design working condition is 1400℃; external insulation is used to control the wall temperature, and the temperature after external insulation is ≤75℃.

[0055] c) Ambient temperature: annual average temperature 8.7℃; extreme maximum temperature 36.5℃; extreme minimum temperature -27.7℃; the monthly average of the lowest daily minimum temperature in the past 10 years is -14.6℃.

[0056] d) Medium components (mol%): N2: 52.2%, O2: 2.9%, CO2: 7.5%, H2O: 26.8%, SO2: 10.6%.

[0057] 2) After incineration, the medium contains SO2, with a content of 10.6%. Therefore, the selected refractory materials should not contain or contain as little alkaline oxides as possible. For example, CaO, which is often contained in refractory materials, will react chemically with SO2, causing the refractory materials to gradually peel off.

[0058] 3) The shell wall temperature control is mainly based on the maximum value control, which is related to the safe use of the equipment. We take the maximum operating temperature of 1400℃ and the extreme ambient temperature of 37℃ and no wind as the extreme high temperature working conditions. As long as the wall temperature calculation value can be less than 350℃, other working conditions will not exceed the temperature.

[0059] 2. Calculation Location

[0060] The main high-temperature area of ​​the incinerator of the waste acid regeneration device is the part from the combustion chamber to 500mm below the heat exchanger. According to the furnace structure and the specific high-temperature influence, the calculation part is divided into the following three parts:

[0061] 1. The area 4 meters below the burner in the combustion chamber is the burner high temperature area;

[0062] 2. The U-shaped area between 500mm below the heat exchanger and the high temperature area of ​​the burner is the high temperature area (i.e. the high temperature area 500mm below the heat exchanger, excluding the high temperature area of ​​the burner);

[0063] 3. Furnace bottom area.

[0064] 3. Calculation Method

[0065] According to HG / T 20525-1992 "Design Regulations for Heat Transfer Calculation of Tubular Furnaces in Chemical Industry", the heat transfer calculation formula is:

[0066] t i -t i+1 =(δ i ·Q) / λ i (Formula 2)

[0067] Q——heat loss from furnace wall, kW / m 2

[0068] ε——coefficient, value is 0.9

[0069] T s ——Furnace wall surface temperature, K

[0070] T a ——Atmospheric temperature, KK ε ——Coefficient, furnace top takes 2.1, furnace bottom takes 1.1, vertical wall takes 1.5t i ——Inner wall temperature of the ith lining, °C

[0071] t i+1 ——The inner wall temperature of the i+1th layer lining, i.e. the outer wall temperature of the ith layer lining, ℃

[0072] δ i ——Thickness of the lining layer i, m

[0073] λ i ——Thermal conductivity of the i-th lining, kW / (mK)

[0074] 4. Material selection

[0075] Considering the problem of background lining materials, it is decided to use thermal insulation spray coatings with high strength, no elastic compression, high temperature resistance, and suitable for various occasions regardless of the shape of the furnace as the thermal insulation lining. Among them, the heavy material facing the fire surface is not only acid-resistant, but also refractory castables with excellent thermal shock resistance should be used to adapt to the high temperature and temperature fluctuations in the furnace. The lightweight castable of the backing needs to use lightweight insulation materials with good thermal insulation properties, considering the large temperature difference between the inside and outside during operation (need to be reduced from 1050℃ to below 350℃, and in extreme cases, it needs to be reduced from 1400℃ to below 350℃). However, the better the insulation effect, the lower the temperature resistance. Through thermal analysis calculation, the interface temperature is obtained, and medium-quality insulation with different temperature resistance is also required for transition to ensure that the temperature of the insulation lining is lower than 350℃. In order to prevent dew point erosion when the equipment is operated or started or stopped at a low temperature, a 3mm thick acid-resistant coating layer will be applied to the inside of the equipment shell. External insulation is used to control the wall temperature. Considering the economy and durability, rock wool can be used.

[0076] Table 2 is the working condition calculation table of the high temperature zone of the burner.

[0077] Table 2 Burner high temperature zone working condition calculation table

[0078]

[0079]

[0080] It should be noted that the shell steel plate wall temperature control is mainly based on the maximum value control, and the extreme high temperature involves the safe use of the equipment. That is, we use the maximum operating temperature of 1400℃ and the extreme ambient temperature of 37℃ and the extreme high temperature condition of no wind as the benchmark to meet the shell metal wall temperature not exceeding 350℃, and other conditions will not exceed the temperature.

[0081] It can be seen from Table 2 that, taking the maximum operating temperature of 1400°C, the extreme ambient temperature of 37°C and the extreme high temperature working condition without wind as the benchmark, the high temperature zone of the burner meets the requirement that the metal wall temperature of the shell steel plate is lower than 350°C.

[0082] It can also be seen from Table 2 that under extreme high temperature conditions and operating high temperature conditions, the temperature of the outer insulation metal protective layer is slightly higher than the anti-scalding temperature requirement (operating temperature 1400℃, ambient temperature 37℃, the temperature of the outer insulation metal insulation layer is 87℃>75℃, which cannot meet the anti-scalding requirements; and operating temperature 1250℃, ambient temperature 37℃, the temperature of the outer insulation metal insulation layer is 83℃>75℃, which cannot meet the anti-scalding requirements). It can be considered to increase the thickness of the outer insulation layer, but after calculation, after increasing the thickness of the outer insulation, the temperature of the outer insulation protective layer meets the requirements, but the shell metal temperature is much higher than the process requirement of 350℃, so the solution of increasing the thickness of the outer insulation is not feasible. In the experiment of Table 2, no anti-scalding grid is set. The present invention sets a layer of anti-scalding grid between the shell steel plate in the high temperature zone of the burner and the first outer insulation rock wool layer, which can form an air layer of not less than 200 mm with the rock wool. Due to the large air thermal resistance, it can play an effective partition cooling effect, which will not affect the shell metal temperature, and can also form a certain temperature drop to meet the anti-scalding requirements.

[0083] It can also be seen from Table 2 that under extreme low temperature conditions (operating temperature 1050°C, ambient temperature -27.7°C), the metal wall temperature of the shell is lower than the minimum value of 250°C required by the process. However, the design of the acid-resistant coating layer of the present invention can prevent dew point corrosion and ensure the safe use of the equipment.

[0084] Table 3 is the working condition calculation table for the high temperature area.

[0085] Table 3 Working condition calculation table of high temperature area

[0086]

[0087] It should be noted that the shell wall temperature control is mainly based on the maximum value control, and the extreme high temperature involves the safe use of the equipment. That is, we use the maximum operating temperature of 1400℃ and the extreme ambient temperature of 37℃ and the extreme high temperature condition of no wind as the benchmark to meet the shell metal wall temperature below 350℃, and other conditions will not exceed the temperature.

[0088] It can be seen from Table 3 that, taking the maximum operating temperature of 1400°C, the extreme ambient temperature of 37°C and the extreme high temperature condition of no wind as the benchmark, the high temperature zone meets the requirement that the metal wall temperature of the shell steel plate is lower than 350°C.

[0089] It can also be seen from Table 3 that when checking the extreme low temperature working condition (operating temperature 1050°C, ambient temperature -27.7°C), the metal wall temperature of the shell steel plate is lower than the minimum value of 250°C required by the process. However, the design of the acid-resistant coating layer of the present invention can prevent dew point corrosion and ensure the safe use of the equipment. The probability of the extreme minimum temperature is very small. The operating temperature is 1050°C, the ambient temperature is -14.6°C, and there is no wind as the operating low temperature working condition for verification. The metal wall temperature of the shell steel plate is 252°C>250°C, which meets the process requirements.

[0090] Table 4 is the working condition calculation table of the furnace bottom area.

[0091] Table 4 Furnace bottom area working condition calculation table

[0092]

[0093] It should be noted that the furnace bottom is in direct contact with the cement foundation surface and needs to be calculated separately;

[0094] It can be seen from Table 4 that: taking the operating temperature of 1250℃, the ambient temperature of 25℃, and no wind as the benchmark working condition, the low temperature working condition is calculated, that is, the operating temperature of 1050℃, the ambient temperature of -14.6℃, and no wind. All of them meet the requirements that the metal wall temperature of the shell steel plate is lower than 350℃ and higher than 250℃, which meets the process requirements.

[0095] It should be noted that: when the operating temperature is 1050℃, no wind is used as the reference condition, and the low temperature operating condition is calculated, that is, the operating temperature is 1050℃, and the ambient temperature shell steel plate metal wall temperature is 252℃>250℃, which meets the process requirements.

[0096] Advantages and beneficial effects of the present invention

[0097] 1. The lining structure of the present invention can control the metal temperature of the shell steel plate to be lower than 350°C while ensuring the furnace operating temperature and the medium in the furnace containing high concentration of SO2.

[0098] 2. The present invention selects thermal insulation spray coatings (i.e., the high-temperature thermal insulation spray coating layer, the medium-temperature thermal insulation spray coating layer and the low-temperature thermal insulation spray coating layer in the present invention) which have high strength, no elastic compression, high temperature resistance, are not affected by the shape of the furnace and are suitable for various occasions as the thermal insulation lining.

[0099] 3. The present invention selects the first acid-resistant working lining 11, the second acid-resistant working lining 21 and the third acid-resistant working lining 31 made of ZTEK 85 material as the fire-facing refractory layer, which is a refractory castable material that does not contain calcium aluminate cement and has excellent thermal shock resistance. The thickness is 150 mm, which can ensure sufficient strength.

[0100] 4. The present invention takes into account the large temperature difference between the inside and outside of the furnace. The normal working condition is from 1050℃ to 350℃. It is necessary to use a lightweight castable with good thermal insulation performance. However, the better the castable is, the lower the temperature resistance is. After comprehensive analysis and calculation, medium-quality castables with different temperature resistance are required as transition layers. According to the temperature distribution of the furnace and the structure of the furnace body, the present invention divides three areas, namely the burner high temperature area 1, the high temperature area 2, and the furnace bottom area 3, and optimizes and adjusts the lining structure respectively.

[0101] 5. Considering that under extremely low temperature conditions, the shell steel plate wall temperature is checked to be less than 250°C, and dew point corrosion may occur, the present invention provides a first acid-resistant coating layer 15, a second acid-resistant coating layer 24 and a third acid-resistant coating layer 34 to prevent the occurrence of dew point corrosion.

[0102] 6. Considering that the outer insulation metal layer exceeds the anti-scalding temperature under extremely high temperature conditions, the present invention is provided with an anti-scalding grille 17 of not less than (i.e. greater than or equal to) 200 mm to form an air interlayer. While ensuring the metal wall temperature of the shell steel plate, it achieves the effect of partitioning and cooling, so that the temperature behind the outer insulation (anti-scalding grille and outer insulation rock wool layer) is no more than 75°C to meet the anti-scalding requirements.

[0103] The above-mentioned embodiment only expresses one implementation mode of the present invention, and its description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. A lining structure in an alkylation spent acid regeneration device, characterized in that: It includes a first acid-resistant working lining, a high-temperature thermal insulation spray coating, a first medium-temperature thermal insulation spray coating, a first low-temperature thermal insulation spray coating, a first acid-resistant paint layer, a first external thermal insulation rock wool layer, a second acid-resistant working lining, a second medium-temperature thermal insulation spray coating, a second low-temperature thermal insulation spray coating, a second acid-resistant paint layer, a second external thermal insulation rock wool layer, a third acid-resistant working lining, a third medium-temperature thermal insulation spray coating, a third low-temperature thermal insulation spray coating, and a third acid-resistant paint layer; The burner high temperature zone is within 4 meters below the corresponding burner in the combustion chamber, the U-shaped zone between 500 mm below the heat exchanger and the burner high temperature zone is the high temperature zone, the bottom of the incinerator is the furnace bottom zone, and the inner wall of the shell steel plate in the burner high temperature zone is provided with a first acid-resistant working lining, a high temperature thermal insulation spray layer, a first medium temperature thermal insulation spray layer, a first low temperature thermal insulation spray layer, and a first acid-resistant paint layer from the inside to the outside, and the outer wall of the shell steel plate in the burner high temperature zone is provided with a first external thermal insulation rock wool layer, and the inner wall of the shell steel plate in the high temperature zone is provided with a second acid-resistant working lining, a second medium temperature thermal insulation spray layer, a second low temperature thermal insulation spray layer, and a second acid-resistant paint layer from the inside to the outside, and the outer wall of the shell steel plate in the high temperature zone is provided with a second external thermal insulation rock wool layer, and the inner wall of the furnace bottom steel plate in the furnace bottom zone is provided with a third acid-resistant working lining, a third medium temperature thermal insulation spray layer, a third low temperature thermal insulation spray layer, and a third acid-resistant paint layer from top to bottom.

2. The lining structure in the alkylation spent acid regeneration device according to claim 1, characterized in that: The lining structure in the alkylation spent acid regeneration device also includes an anti-scalding grille, which is arranged between the shell steel plate in the high-temperature zone of the burner and the first outer thermal insulation rock wool layer.

3. The lining structure in the alkylation spent acid regeneration device according to claim 2, characterized in that: The thickness of the first acid-resistant working lining is 150 mm, the thickness of the high-temperature thermal insulation spray layer is 50 mm, the thickness of the first medium-temperature thermal insulation spray layer is 70 mm, the thickness of the first low-temperature thermal insulation spray layer is 147 mm, the thickness of the first acid-resistant coating layer is 3 mm, the thickness of the shell steel plate in the high-temperature zone of the burner is 16 mm, the thickness of the anti-scalding grille is greater than or equal to 200 mm, and the thickness of the first external thermal insulation rock wool layer is 20 mm; The thickness of the second acid-resistant working lining is 150 mm, the thickness of the second medium-temperature thermal insulation spray layer is 120 mm, the thickness of the second low-temperature thermal insulation spray layer is 147 mm, the thickness of the second acid-resistant coating layer is 3 mm, the thickness of the shell steel plate in the high-temperature zone is 16 mm, and the thickness of the second external thermal insulation rock wool layer is 20 mm; The thickness of the third acid-resistant working lining is 150mm, the thickness of the third medium-temperature insulation spray layer is 120mm, the thickness of the third low-temperature insulation spray layer is 147mm, the thickness of the third acid-resistant coating layer is 3mm, and the thickness of the bottom steel plate in the furnace bottom area is 20mm.

4. The lining structure in the alkylation spent acid regeneration device according to claim 3, characterized in that: The first outer thermal insulation rock wool layer and the second outer thermal insulation rock wool layer are both made of rock wool material.

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