A magnesium nitrate heater

Abstract

The present invention relates to a magnesium nitrate heater, which comprises a heater body, a heater head, heating tubes, a tube fixing tube sheet, a sight glass, a ceramic composite drainage tube, an erosion prevention baffle and a manhole. The ceramic composite drainage tube is arranged in the middle of the heater body. The longitudinal section of the ceramic composite drainage tube is of a U-shaped structure. The upper end of the ceramic composite drainage tube is connected to the blanking pipe of the concentration tower through a split flange. The outer wall of the ceramic composite drainage tube is welded to the reserved hole of the heater body by welding rods; Multiple layers of erosion prevention baffles are welded on the heating tubes to reduce the leakage of the heating tubes caused by erosion and high-temperature corrosion. The method of the present invention is reasonable and feasible, ingeniously designed, the equipment operates safely and stably for a long period, the number of equipment replacements is reduced, the maintenance cost and the energy consumption caused by parking are reduced, the service life of the equipment is extended, and it has good market prospects and development space for the existing technology.

Description

Technical Field

[0001] The present invention relates to the field of industrial production equipment for concentrated nitric acid by the magnesium nitrate method, and particularly to a magnesium nitrate heater. Background Art

[0002] The magnesium nitrate heater is one of the key equipment in the industrial production of concentrated nitric acid by the magnesium nitrate method. Its main function is to provide heat for the rectification of concentrated nitric acid and heat the magnesium nitrate solution to achieve the purpose of denitrification. After the magnesium solution absorbs the moisture in the dilute nitric acid, its concentration decreases, but it carries a small amount of nitric acid. Under high-temperature conditions, the corrosiveness of nitric acid and nitric acid vapor increases sharply. Coupled with the scouring effect of gravity, the feeding drain pipe and the heating tubes at the lower part of the magnesium nitrate heater are corroded more seriously, resulting in frequent shutdowns of the device and limited stable production cycle of the device.

[0003] How to design a method that is reasonable, feasible, ingenious, enables the equipment to operate safely, stably and for a long period, reduces the number of equipment replacements, reduces the maintenance cost and energy consumption caused by shutdowns, and extends the service life of the equipment is a problem that needs to be solved currently. Summary of the Invention

[0004] In order to solve the technical problems in the normal production process of existing concentrated nitric acid, such as the frequent corrosion and shutdown of the feeding drain pipe and the heating tubes of the heater due to the large flow rate, strong corrosiveness, serious scouring effect, etc. of the magnesium nitrate solution, resulting in high consumption, increased cost, increased maintenance cost and heavy operation, the present invention provides a magnesium nitrate heater to achieve the purpose of reasonable and feasible method, ingenious design, safe, stable and long-term operation of the equipment, reducing the number of equipment replacements, reducing the maintenance cost and energy consumption caused by shutdowns, and extending the service life of the equipment.

[0005] The technical solution adopted by the present invention to solve the above technical problems is: a magnesium nitrate heater, including a heater body, a heater head, heating tubes, tube fixing tube sheets, sight glasses, ceramic composite drain pipes, anti-scouring baffles and manholes. The ceramic composite drain pipe is arranged in the middle of the heater body. The longitudinal section of the ceramic composite drain pipe is a double-layer straight cylinder structure of outer 304L - inner ceramic. The upper end of the ceramic composite drain pipe is connected to the concentrated tower feeding pipe through a split flange, and the outer wall of the ceramic composite drain pipe is welded to the reserved hole of the heater body by welding rods; multiple anti-scouring baffles are welded on the heating tubes, and the welding points are located on the tube fixing tube sheets directly below the ceramic composite drain pipe to reduce the leakage of the heating tubes caused by scouring and high-temperature corrosion.

[0006] The above is the basic implementation manner of the present invention, and further improvements, perfection and limitations can be made on this basis: for example, the inner lining of the ceramic composite drain pipe adopts ceramic material, the outer wall of the ceramic composite drain pipe adopts stainless steel material, and the inner lining part is connected and fixed to the outer wall part through gaskets.

[0007] The above is the basic implementation mode of the present invention, and further improvements, refinements and limitations can be made on this basis: for example, the outer wall of the ceramic composite drainage pipe is made of 304L stainless steel.

[0008] The above is the basic implementation mode of the present invention, and further improvements, refinements and limitations can be made on this basis: for example, the inner wall of the ceramic composite drainage pipe is lined with a 4-mm ceramic layer in the form of a lining to prevent erosion and NOx corrosion.

[0009] The above is the basic implementation mode of the present invention, and further improvements, refinements and limitations can be made on this basis: for example, the ceramic composite drainage pipe adopts a split flange type, connected to the concentrated tower discharge pipe at the upper part and to the ceramic composite drainage pipe at the lower part to facilitate disassembly, inspection and maintenance.

[0010] The above is the basic implementation mode of the present invention, and further improvements, refinements and limitations can be made on this basis: for example, the lower end of the outer wall of the ceramic composite drainage pipe is welded to the heater body after argon arc welding backing.

[0011] The above is the basic implementation mode of the present invention, and further improvements, refinements and limitations can be made on this basis: for example, a manhole for maintenance is provided at the upper part of the heater body.

[0012] Compared with the prior art, the beneficial effects of the present invention are:

[0013] 1) The present invention includes a heater body, a heater head, heating tubes, tube fixed tube sheets, sight glasses, ceramic composite drainage pipes, erosion prevention baffles and manholes. The ceramic part inside the ceramic composite drainage pipe can reduce the thinning of the pipe wall caused by erosion and high-temperature corrosion, extend the replacement cycle of the corrosion of the discharge pipe, reduce the number of shutdowns, and thus reduce the energy consumption during shutdowns;

[0014] 2) Multiple layers of erosion prevention baffle plates are welded on the heating tube bundle, welded on the two fixed tube sheets on the left and right of the tube bundle directly below the discharge pipe, effectively protecting the tube bundle. The baffle plates can reduce the leakage of the heating tubes caused by erosion and high-temperature corrosion, and thus reduce the problem of low energy utilization efficiency caused by tube plugging;

[0015] 3) The composite ceramic drainage pipe adopts a stainless steel-lined ceramic composite pipe, enhancing the corrosion resistance and erosion resistance, extending the service life, and improving the stable operation cycle of the process device;

[0016] 4) The composite ceramic drainage pipe adopts a sleeve installation form, which not only protects the equipment body, but also facilitates replacement, inspection and maintenance, saving a large amount of labor, material and time costs;

[0017] 5) After the equipment is upgraded and modified, the service life of the drainage and feeding pipe of the magnesium nitrate heater is extended from 90 days to more than 360 days, reducing the maintenance cost and energy consumption caused by parking.

[0018] 6) The magnesium nitrate heater is corrosion and erosion resistant, effectively extending the service life of the feeding and drainage pipe part and the heating tube bundle part of the heater. At the same time, it reduces the shutdown of the device caused by severe corrosion and erosion, thereby reducing material consumption, maintenance costs, and the safety and environmental protection pressure caused by the shutdown and maintenance of the device, with excellent effects. Brief Description of the Drawings

[0019] Figure 1 is a partial sectional view structure diagram of the present invention;

[0020] Figure 2 is a longitudinal sectional view schematic diagram of the ceramic composite drainage pipe;

[0021] Figure 3 is an installation schematic diagram of the ceramic composite drainage pipe;

[0022] Figure 4 is a schematic diagram of the original drainage pipe lacking a ceramic lining.

[0023] In the figure: 1. Heater head, 2. Heating tube bundle, 3. Tube sheet for fixing the tube bundle, 4. Sight glass, 5. Ceramic composite drainage pipe, 6. Anti-erosion baffle, 7. Manhole, 8. Support base, 9. Loose flange, 10. Gasket. Detailed Description of the Invention

[0024] The following further describes in detail the specific embodiments of the present invention with reference to the accompanying drawings.

[0025] As Figure 1 and Figure 2 shown, Figure 1 is a partial sectional view structure diagram of the present invention, Figure 2 is a longitudinal sectional view schematic diagram of the ceramic composite drainage pipe. A magnesium nitrate heater includes a heater body, a heater head 1, a heating tube bundle 2, a tube sheet for fixing the tube bundle 3, a sight glass 4, a ceramic composite drainage pipe 5, an anti-erosion baffle 6, and a manhole 7. The number of the anti-erosion baffles 6 is three to six layers, and the material of the anti-erosion baffle 6 is made of stainless steel; the ceramic composite drainage pipe 5 is arranged in the middle of the heater body. The longitudinal section of the ceramic composite drainage pipe 5 is a double-layer straight cylinder structure of outer 304L - inner ceramic. The upper end of the ceramic composite drainage pipe 5 is connected to the concentrated tower feeding pipe through a split flange, and the outer wall of the ceramic composite drainage pipe 5 is welded to the reserved hole of the heater body by welding rods; multiple layers of anti-erosion baffles 6 are welded on the heating tube bundle 2, and the welding points are located on the tube sheet for fixing the tube bundle 3 directly below the ceramic composite drainage pipe 5 to reduce the leakage of the heating tube bundle 2 caused by erosion and high-temperature corrosion.

[0026] AsFigure 2 As shown Figure 2 is a schematic longitudinal section of a ceramic composite drainage pipe; the outer wall of the ceramic composite drainage pipe 5 is made of stainless steel and is welded to the heater body after argon arc welding backing, and the inner lining of the ceramic composite drainage pipe 5 is made of ceramic material.

[0027] Figure 3 is a schematic installation diagram of a ceramic composite drainage pipe; the upper end of the ceramic composite drainage pipe 5 is connected to the concentrated tower discharge pipe through split flanges, and the outer wall of the ceramic composite drainage pipe 5 is welded to the reserved hole on the heater body through welding rods.

[0028] A manhole 7 for maintenance is provided in the upper part of the heater body.

[0029] Figure 4 is a schematic diagram of the original drainage pipe lacking a ceramic lining. The original drainage pipe only uses stainless steel and lacks an inner lining. After long-term use, the inner wall is prone to corrosion and damage.

[0030] In actual operation, it includes connecting the upper part of the ceramic composite drainage pipe 5 to the concentrated tower discharge pipe with split flanges. The outer wall material is 304L, with a thickness of 8 mm, the inner wall material is ceramic, with a thickness of 4 mm, the length is 540 mm, the slope of the lower discharge port is 45°. The outer wall in the middle of the ceramic composite drainage pipe is welded with argon arc welding backing, and the upper part is welded to the corresponding reserved hole on the magnesium nitrate heater with stainless steel A002 welding rods. The internal ceramic part can reduce the thinning of the pipe wall caused by erosion and high-temperature corrosion, extend the replacement cycle of the corroded discharge pipe, reduce the number of shutdowns, and thus reduce the energy consumption during shutdowns. Multiple anti-erosion baffle plates are welded on the heating tube bundle, and are welded to the two fixed tube plates on the left and right of the tube bundle directly below the discharge pipe, effectively protecting the tube bundle. The baffle plates can reduce the leakage of the heating tubes caused by erosion and high-temperature corrosion, and thus reduce the reduction of energy utilization efficiency caused by tube leakage plugging.

[0031] The ceramic composite drainage pipe 5 is inserted into the magnesium nitrate heater to a depth of 350 mm, and the distance between the lower inclined port and the top layer of the baffle plate should be ≥90 mm to meet the discharge of dilute magnesium nitrate. The discharged magnesium nitrate solution is sprayed on the anti-erosion baffle 6 to reduce the erosion of the heating tubes by the high-temperature magnesium solution.

[0032] The present invention can not only be applied in the production of concentrated nitric acid by the magnesium nitrate method to reduce the corrosion and erosion of the discharge pipe and heating tubes by the high-temperature magnesium nitrate-containing solution, but also be equally applicable to production processes with strong corrosion and severe erosion.

[0033] The method of the present invention is reasonable and feasible, with ingenious design. The equipment can operate safely, stably and for a long period, reducing the number of equipment replacements, lowering the maintenance cost and the energy consumption caused by parking, prolonging the service life of the equipment, and solving the technical problems existing in the normal production process of concentrated nitric acid, such as the frequent corrosion and parking of the feeding and drainage pipes and the heater tubes due to the large flow rate, strong corrosiveness and serious scouring effect of the magnesium nitrate solution, resulting in high consumption, increased cost, increased maintenance cost and heavy operation. For the existing technology, it has good market prospects and development space.

[0034] The preferred specific embodiments and examples of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the above embodiments and examples, and various changes can be made without departing from the concept of the present invention within the scope of knowledge possessed by those skilled in the art.

Claims

1. A magnesium nitrate heater, characterized in that: It includes a heater body, a heater head (1), heating tubes (2), a tube-sheet for fixing tubes (3), a sight glass (4), a ceramic composite drainage tube (5), an erosion-proof baffle (6) and a manhole (7). The ceramic composite drainage tube (5) is arranged in the middle of the heater body. The longitudinal section of the ceramic composite drainage tube (5) is a double-layer straight cylinder structure inside and outside. The upper end of the ceramic composite drainage tube (5) is connected to the discharge pipe of the concentration tower through a split flange. The outer wall of the ceramic composite drainage tube (5) is welded to the reserved hole of the heater body by welding rods; Multiple layers of erosion-proof baffles (6) are welded on the heating tubes (2), and the welding points are located on the tube-sheet for fixing tubes (3) directly below the ceramic composite drainage tube (5) to reduce the leakage of the heating tubes (2) caused by erosion and high-temperature corrosion; The inner lining of the ceramic composite drainage tube (5) is made of ceramic material, the outer wall of the ceramic composite drainage tube (5) is made of stainless steel material, and the inner lining part is connected and fixed to the outer wall part through gaskets; The outer wall of the ceramic composite drainage tube (5) is made of 304L stainless steel material.

2. The magnesium nitrate heater according to claim 1, characterized in that: The inner wall of the ceramic composite drainage tube (5) is lined with a 4-mm ceramic layer to prevent erosion and NOx corrosion.

3. A magnesium nitrate heater according to claim 1, characterized in that: The lower end of the outer wall of the ceramic composite drainage tube (5) is welded to the heater body after argon arc welding at the bottom.

4. A magnesium nitrate heater according to claim 1, characterized in that: The number of the erosion-proof baffles (6) is three to six layers, and the material of the erosion-proof baffles (6) is stainless steel material.

5. A magnesium nitrate heater according to claim 1, characterized in that: A manhole (7) for maintenance is arranged at the upper part of the heater body.

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