Nitration plant sulphuric acid concentration section heat recovery device

Abstract

The utility model discloses a nitration device sulfuric acid concentration section heat energy recovery unit belongs to chemical industry energy -conserving and environment -friendly technical field, including reactor, heat energy recovery heating mechanism and filter adjusting mechanism, the high temperature mixed steam of reactor discharge, first enter the filter adjusting mechanism of reactor exhaust port connection and carry out purification to remove corrosive nitric acid, the steam after purification enters the steam passage of heat energy recovery heating mechanism again, and the inside of heat energy recovery heating mechanism is provided with spiral guide plate, and the spiral guide plate is separated and forms steam passage and raw material passage, and the sulfuric acid of waiting processing flows in raw material passage, and is preheated with the steam in steam passage through the high -efficient heat exchange of spiral guide plate, and the sulfuric acid after preheating is transported back to reactor. The utility model effectively solved the equipment corrosion problem, prolonged the device life, improved heat energy recovery efficiency significantly, reduced the production energy consumption.

Description

Technical Field

[0001] This utility model relates to the field of chemical energy conservation and environmental protection technology, and in particular to a heat recovery device for the sulfuric acid concentration section of a nitration unit. Background Technology

[0002] In chemical production, nitration is a crucial unit operation, and the resulting waste acid typically requires treatment. Sulfuric acid, a commonly used catalyst and dehydrating agent, decreases in concentration in waste acid. To facilitate recycling and reduce costs, it must be concentrated. The concentration process of sulfuric acid usually consumes a significant amount of heat energy to evaporate the water, while also generating large quantities of high-temperature mixed steam.

[0003] To save energy, existing technologies typically employ heat recovery, utilizing the high-temperature mixed steam generated during the concentration process to preheat the cold sulfuric acid feedstock before it enters the reactor via a heat exchanger. Theoretically, this method can significantly reduce the heating load on the main reactor, achieving energy conservation and emission reduction.

[0004] However, in practical applications, especially in the context of nitration processes, this simple heat recovery scheme has serious technical flaws. Since the waste acid to be concentrated originates from the nitration unit, the high-temperature mixed steam generated during heating is not pure water vapor, but inevitably carries a large amount of highly corrosive volatile nitric acid. When this high-temperature mixed steam containing nitric acid directly enters a conventional heat exchanger, it causes rapid and severe corrosion to the core metal components such as internal pipes and plates. This not only significantly shortens the equipment's lifespan and increases maintenance and replacement costs, but also poses a safety hazard due to corrosion perforation, leading to highly unstable system operation. Furthermore, some conventional heat exchangers have relatively simple structural designs and limited heat exchange areas, resulting in low heat exchange efficiency and insufficient energy recovery. A considerable portion of the heat energy remains unused and is emitted, failing to achieve optimal energy-saving performance.

[0005] Therefore, this utility model proposes a heat recovery device for the sulfuric acid concentration section of a nitration apparatus to address the shortcomings of existing technologies. Utility Model Content

[0006] In view of the problems existing in the heat recovery device of the sulfuric acid concentration section of the nitration unit, such as serious damage to the equipment due to the entrainment of corrosive nitric acid by high-temperature mixed steam and insufficient energy recovery due to low heat exchange efficiency, this utility model aims to provide a heat recovery device of the sulfuric acid concentration section of the nitration unit with an improved structure that can effectively solve the above problems.

[0007] This utility model provides a heat recovery device for the sulfuric acid concentration section of a nitration apparatus, comprising: a reactor, a heat recovery heating mechanism, and a filtration and adjustment mechanism.

[0008] The heat recovery heating mechanism is equipped with a spiral guide plate inside, which is divided into a steam channel for accommodating the high-temperature mixed steam and a raw material channel for accommodating the sulfuric acid to be processed.

[0009] Furthermore, the reactor has a storage port, a conveying port, and an exhaust port; the conveying pipe of the heat recovery heating mechanism is in fluid communication with the conveying port of the reactor; the outlet of the filtration and adjustment mechanism is in fluid communication with the exhaust port of the heat recovery heating mechanism, and the inlet of the filtration and adjustment mechanism is in fluid communication with the exhaust port of the reactor, so as to filter the high-temperature mixed steam discharged from the reactor and then send it into the heat recovery heating mechanism to preheat the sulfuric acid raw material entering from its inlet.

[0010] Preferably, the heat recovery heating mechanism further includes a housing, the spiral guide plate is fixed inside the housing by a plurality of fixing columns, and a heat insulation layer for filling inert gas is formed between the housing and the spiral guide plate.

[0011] Preferably, the gas inlet is located on the side wall of the outer casing, and the middle part of the spiral guide plate is provided with a gas outlet pipe communicating with the steam channel.

[0012] Preferably, the diameter of the air outlet pipe is smaller than the diameter of the air inlet, and the diameter of the material conveying pipe is smaller than the diameter of the material inlet.

[0013] Preferably, the filtration and adjustment mechanism includes a storage tank, an exhaust pipe that fluidly connects the exhaust port of the reactor to the storage tank, and an air supply pipe that fluidly connects the storage tank to the air supply port of the heat recovery heating mechanism.

[0014] Preferably, a gate valve is installed on the exhaust pipe, and a regulating valve is installed on the gas supply pipe.

[0015] Preferably, the storage tank is provided with at least two perforated partitions inside.

[0016] Preferably, the porous partitions form a receiving space for filling the nitric acid adsorption filter material.

[0017] This utility model has the following beneficial effects: 1. This utility model solves the problem in the prior art that the heat exchange equipment is severely corroded, has a short service life and unstable operation due to direct contact with steam, by using a filter adjustment mechanism set between the reactor and the heat recovery heating mechanism, and by using the internal porous baffle and adsorption filter material to remove corrosive nitric acid in the high-temperature mixed steam in advance. This achieves the technical effect of effectively protecting the core equipment, significantly extending the service life of the device and ensuring the long-term safe and stable operation of the system.

[0018] 2. This utility model, by adopting a heat energy recovery heating mechanism with a built-in spiral guide plate, utilizes the independent spiral steam channel and raw material channel separated by it to greatly increase the heat exchange area and extend the fluid residence time, solving the problems of low heat recovery efficiency, insufficient waste heat utilization, and serious energy waste in the prior art. It achieves the technical effect of efficient waste heat recovery, significantly reducing the heating energy consumption of subsequent reactors, and saving production costs. Attached Figure Description

[0019] Figure 1 This is a perspective view of the heat recovery device for the sulfuric acid concentration section of the nitration apparatus proposed in this utility model; Figure 2 This is a schematic diagram of the heat recovery heating mechanism of the sulfuric acid concentration section heat recovery device in the nitration apparatus proposed in this utility model; Figure 3 This is a partial structural cross-sectional view of the heat recovery heating mechanism of the sulfuric acid concentration section heat recovery device in the nitration apparatus proposed in this utility model. Figure 4 This is a schematic diagram of the filtration and adjustment mechanism of the heat recovery device in the sulfuric acid concentration section of the nitration apparatus proposed in this utility model. Figure 5 This is a partial structural cross-sectional view of the filtration and adjustment mechanism of the heat recovery device in the sulfuric acid concentration section of the nitration apparatus proposed in this utility model.

[0020] Legend: 1. Reactor; 2. Heat recovery heating mechanism; 201. Shell; 202. Fixed column; 203. Spiral guide plate; 204. Feed pipe; 205. Gas outlet pipe; 206. Feed inlet; 207. Gas outlet; 208. Steam passage; 209. Raw material passage; 3. Filtration and adjustment mechanism; 301. Exhaust pipe; 302. Gate valve; 303. Storage tank; 304. Regulating valve; 305. Gas outlet pipe; 306. Porous baffle; 4. Storage port; 5. Feed inlet; 6. Exhaust port. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions in the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model.

[0022] Example: Please refer to Figure 1The overall framework of the sulfuric acid concentration section heat recovery unit of the nitration plant includes a reactor 1, a heat recovery heating mechanism 2 for heat exchange, and a filtration and regulation mechanism 3 for steam purification. The reactor 1 integrates a storage port 4 for discharging finished product materials, a conveying port 5 for receiving materials to be reacted, and an exhaust port 6 for discharging high-temperature mixed steam. The filtration and regulation mechanism 3 acts as a connecting bridge, with its inlet fixedly connected to the exhaust port 6 of the reactor 1 via an exhaust pipe 301, for receiving and processing the high-temperature mixed steam discharged from the reactor 1. The outlet of the filtration and regulation mechanism 3 is fixedly connected to the gas inlet 207 of the heat recovery heating mechanism 2 via a gas conveying pipe 305, thereby conveying the purified steam to the heat recovery heating mechanism 2. The inlet 206 of the heat recovery heating mechanism 2 is used to receive the sulfuric acid raw material to be heated. After the raw material is preheated inside the heat recovery heating mechanism 2, it is conveyed through a conveying pipe 204 and fixedly connected to the conveying port 5 of the reactor 1. Thus, the steam purification and recovery path and the sulfuric acid raw material preheating supply path constitute a complete working cycle that cooperates with each other.

[0023] Please refer to Figure 2 and Figure 3 The heat recovery heating mechanism 2 includes a cylindrical outer shell 201 and a spiral guide plate 203 housed and fixed inside the outer shell 201. The spiral guide plate 203 is securely connected to the inner wall of the outer shell 201 by multiple circumferentially and axially distributed fixing posts 202. An annular gap is formed between the inner wall of the outer shell 201 and the outer wall of the spiral guide plate 203. This gap constitutes a heat insulation layer for filling with inert gas to prevent heat loss to the external environment. As a key heat exchange element, the spiral guide plate 203 is integrally formed inside to separate independent and non-interfering spiral steam channels 208 and spiral raw material channels. The outer casing 201 has a gas inlet 207 on its side wall, which is connected to the beginning of the steam channel 208. A gas outlet 205 is installed at the center of the spiral guide plate 203, which is connected to the end of the steam channel 208. The spiral guide plate 203 also has an inlet 206 connected to the beginning of the raw material channel 209 and a feed pipe 204 connected to the end of the raw material channel 209. This double spiral channel structure ensures that the high-temperature steam and sulfuric acid raw material can have a full and efficient indirect heat exchange through the wall of the spiral guide plate 203 in their respective independent flow channels.

[0024] As a preferred embodiment, in order to extend the residence time of steam and raw materials in the heat recovery heating mechanism 2, thereby achieving more complete heat exchange, please refer to... Figure 2 and Figure 3The dimensions of each pipe in the heat recovery heating mechanism 2 are specially designed. Specifically, the flow cross-sectional diameter of the air outlet pipe 205 is set to be smaller than the flow cross-sectional diameter of the air inlet 207, and the flow cross-sectional diameter of the material conveying pipe 204 is set to be smaller than the flow cross-sectional diameter of the inlet 206.

[0025] As another preferred embodiment, in order to purify the steam entering the heat recovery heating mechanism 2, please refer to... Figure 4 and Figure 5 The filter adjustment mechanism 3 has a specific internal structure; the filter adjustment mechanism 3 includes a hollow storage tank 303, and at least two porous partitions 306 are fixedly arranged at intervals along the height direction inside the storage tank 303; the porous partitions 306 are plate-shaped structures filled with micropores, and a receiving space for filling nitric acid adsorption filter material is formed between two adjacent porous partitions 306, and the filter material can be activated carbon or molecular sieve.

[0026] As another preferred embodiment, in order to achieve precise control over the on / off state and flow rate of the steam flow path, please refer to... Figure 4 A gate valve 302 is installed on the exhaust pipe 301 connecting the reactor 1 and the storage tank 303 to control whether the steam flow path is open; a regulating valve 304 is installed on the gas supply pipe 305 connecting the storage tank 303 and the heat recovery heating mechanism 2 to precisely regulate the flow rate of the filtered steam entering the heat recovery heating mechanism 2.

[0027] Working principle: The heat energy generated in the sulfuric acid concentration section of the nitration unit is mainly released as high-temperature mixed steam. The spiral guide plate 203 is fixed to the outer shell 201 by multiple fixed columns 202. The spiral guide plate 203 internally separates a steam channel 208 and a raw material channel 209. The high-temperature mixed steam discharged from reactor 1 enters the steam channel 208 through the gas inlet 207 on the side of the outer shell 201, and is then discharged to the outside through the central outlet pipe 205. The sulfuric acid to be processed enters the raw material channel 209 from the feed inlet 206, and is then transported to reactor 1 through the feed pipe 204 and feed inlet 5 for reaction. The processed sulfuric acid is then discharged through the storage port 4. During the transportation process, the high-temperature mixed steam... The heat energy of the mixed steam is transferred to the unprocessed sulfuric acid through the spiral guide plate 203, thereby preheating the sulfuric acid. At the same time, the diameter of the gas outlet 205 is smaller than the diameter of the gas inlet 207, and the diameter of the feed pipe 204 is smaller than the diameter of the feed inlet 206, thereby increasing the residence time of the high-temperature mixed steam and sulfuric acid in the spiral guide plate 203, and fully preheating the sulfuric acid. The gap between the outer shell 201 and the spiral guide plate 203 is filled with inert gas to form a heat insulation layer, preventing the high-temperature mixed steam from escaping to the outside. The heat energy recovery heating mechanism 2 can recover and utilize the heat energy of the high-temperature mixed steam, greatly reducing the heating load of the subsequent reactor 1, reducing the heat energy demand of the reactor 1 during operation, and saving energy consumption. During processing, the gate valve 302 is opened, and the high-temperature mixed steam discharged from the reactor 1 flows through the exhaust port 6 and the exhaust pipe 301 to the storage tank 303. The high-temperature mixed steam contains a large amount of steam and volatile nitric acid. Inside the storage tank 303, there are two fixed porous baffles 306. The space between the porous baffles 306 is filled with filter material that can adsorb nitric acid, thereby absorbing the mixed nitric acid and preventing nitric acid from corroding the pipes and the spiral guide plate 203. The filtered steam is transported to the spiral guide plate 203 through the gas supply pipe 305 to preheat the sulfuric acid. The regulating valve 304 on the gas supply pipe 305 can control the flow rate of the steam in the pipe, thereby controlling the preheating temperature of the unprocessed sulfuric acid. It can also prevent the gas pressure in the spiral guide plate 203 from being too high and causing a safety accident. The filter regulating mechanism 3 can not only protect the equipment pipeline from corrosion by nitric acid, but also regulate the pressure in the spiral guide plate 203 and regulate the preheating temperature of the sulfuric acid, increasing the practicality of the heat recovery device.

Claims

1. A heat recovery device for the sulfuric acid concentration section of a nitration unit, comprising a reactor (1) having a storage port (4), a conveying port (5) and an exhaust port (6), and a heat recovery heating mechanism (2); Its features are, The device also includes a filter adjustment mechanism (3); The heat recovery heating mechanism (2) includes a feed inlet (206), a feed pipe (204) and a gas outlet (207), and the feed pipe (204) is in fluid communication with the feed outlet (5) of the reactor (1); The outlet of the filter regulating mechanism (3) is in fluid communication with the gas inlet (207) of the heat recovery heating mechanism (2), and the inlet of the filter regulating mechanism (3) is in fluid communication with the exhaust port (6) of the reactor (1). The heat recovery heating mechanism (2) is provided with a spiral guide plate (203) inside. The spiral guide plate (203) is divided into a steam channel (208) that connects to the gas outlet (207) and a raw material channel (209) that connects to the feed inlet (206) and the feed pipe (204).

2. The heat recovery device for the sulfuric acid concentration section of the nitration unit according to claim 1, characterized in that, The heat recovery heating mechanism (2) also includes a shell (201), and the spiral guide plate (203) is fixed inside the shell (201) by a plurality of fixed columns (202). A heat insulation layer for filling inert gas is formed between the shell (201) and the spiral guide plate (203).

3. The heat recovery device for the sulfuric acid concentration section of the nitration unit according to claim 2, characterized in that, The gas inlet (207) is located on the side wall of the outer shell (201), and the middle part of the spiral guide plate (203) is provided with an outlet pipe (205) that communicates with the steam channel (208).

4. The heat recovery device for the sulfuric acid concentration section of the nitration unit according to claim 1, characterized in that, The heat recovery heating mechanism (2) further includes an exhaust pipe (205), the diameter of which is smaller than the diameter of the air inlet (207), and the diameter of the feed pipe (204) is smaller than the diameter of the feed inlet (206).

5. The heat recovery device for the sulfuric acid concentration section of the nitration unit according to claim 1, characterized in that, The filtration and adjustment mechanism (3) includes a storage tank (303), an exhaust pipe (301) that fluidly connects the exhaust port (6) of the reactor (1) to the storage tank (303), and an air supply pipe (305) that fluidly connects the storage tank (303) to the air supply port (207) of the heat recovery heating mechanism (2).

6. The heat recovery device for the sulfuric acid concentration section of the nitration unit according to claim 5, characterized in that, A gate valve (302) is installed on the exhaust pipe (301), and a regulating valve (304) is installed on the gas supply pipe (305).

7. The heat recovery device for the sulfuric acid concentration section of the nitration unit according to claim 5, characterized in that, The storage tank (303) is fixedly provided with at least two porous baffles (306).

8. The heat recovery device for the sulfuric acid concentration section of the nitration unit according to claim 7, characterized in that, The porous partitions (306) form a containment space for filling nitric acid adsorption filter media.

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