A molten salt waste heat recovery device for melamine production

Abstract

The utility model discloses a kind of molten salt waste heat recovery devices for melamine production, belong to molten salt waste heat recovery technical field, the outer end of hot water recovery pipe is connected with control valve, branch pipe is equipped between control valve and hot water recovery pipe, the outer end of control valve is connected with hot water discharge pipe, and hot water discharge is realized in molten salt tank inside by hot water recovery pipe, hot water discharge pipe;The outer end of branch pipe is connected with first filter tank.Through multistage filtration system (including first filter tank, dismounting tank inner filter cylinder and second filter tank) to molten salt tank hot water depth filtration, remove impurity, ensure that the water quality of entering waste heat recovery heat exchanger is pure.This not only prevents heat exchanger pipeline to reduce heat exchange efficiency due to impurity blockage, but also reduces the surface of pipeline adhesion scale, prolongs the service life of heat exchanger.In addition, waste heat recovery heat exchanger utilizes annular distribution multiple pipeline to improve heat exchange efficiency, fully utilizes molten salt tank waste heat, not only improves energy utilization, reduces cost, but also helps energy saving and emission reduction.

Description

Technical Field

[0001] This utility model relates to the field of molten salt waste heat recovery technology, and in particular to a molten salt waste heat recovery device for melamine production. Background Technology

[0002] The high-temperature molten salt furnace, also known as a nitrate furnace, is the core equipment used for high-temperature heating in the chemical industry, primarily used in melamine production. This equipment is widely used in various fields, including melamine production, such as coal tar deep processing, lubricant refining, and fertilizer manufacturing. The high-temperature molten salt furnace uses a molten nitrate mixture as the heat transfer medium, mainly composed of potassium nitrate (KNO3), sodium nitrite (NaNO2), and sodium nitrate (NaNO3). The equipment has a wide operating temperature range, generally between 150℃ and 580℃, with some units reaching up to 600℃. The high-temperature molten salt furnace provides a stable heat source through electric heating or fuel combustion (such as coal, oil, or gas), with a heating capacity ranging from 300,000 to 12 million kcal / h. During operation, powdered molten salt is placed in a melting tank and melted by high-pressure steam heating pipes or electric heating pipes installed within the tank. Once the molten salt reaches a certain viscosity, it is transported by a circulating pump to a heat carrier furnace for further circulation and heating, forming a closed-loop circulating heating system. This system is not only highly thermally efficient, but also easy to maintain.

[0003] During the production of melamine, the molten salt equipment gradually melts and stores heat during the heating process. However, during the crystallization of melamine, the temperature drops from high to low, resulting in a significant waste of heat. For example, if effective waste heat recovery measures are not implemented during the temperature drop from 320°C to 160°C, this heat will be directly dissipated into the environment.

[0004] After recycling, the ammonia gas, due to its relatively low temperature, needs to be heated in an ammonia preheater. This process often requires additional heat from the molten salt furnace, thus increasing energy consumption. Furthermore, existing process designs often fail to fully recover and utilize useful components such as carbon dioxide in the exhaust gas, leading to further energy loss.

[0005] Molten salt equipment itself is corrosive, which affects the safety, strength, and service life of the equipment. This not only increases maintenance costs but may also lead to production interruptions due to equipment failure, further impacting production efficiency and energy consumption. Utility Model Content

[0006] The main objective of this invention is to provide a molten salt waste heat recovery device for melamine production, which can effectively solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0008] A waste heat recovery device for molten salt in melamine production includes a molten salt tank, a sealing cover, a locking assembly, and a hot water recovery pipe. The sealing cover is installed on the molten salt tank via the locking assembly, and the hot water recovery pipe is installed on the side wall of the molten salt tank.

[0009] The outer end of the hot water recovery pipe is connected to a control valve, and a branch pipe is provided between the control valve and the hot water recovery pipe. The outer end of the control valve is connected to a hot water discharge pipe, and the hot water inside the molten salt tank is discharged through the hot water recovery pipe and the hot water discharge pipe.

[0010] The outer end of the branch pipe is connected to a first filter tank, the outer end of the first filter tank is connected to a disassembly tank, the inner end of the disassembly tank is connected to an internal filter cylinder, and the outer end of the disassembly tank is connected to a second filter tank. The tail end of the second filter tank is connected to an outlet pipe, and the outlet pipe is connected to a waste heat recovery heat exchanger through a distribution pipe. The waste heat recovery heat exchanger has an inner cavity, which is connected to a hot water discharge pipe through a connecting pipe. Hot water filtration is achieved through the internal filter cylinder, reducing scale adhesion on the surface of the heat exchanger pipes in the inner cavity.

[0011] In a further preferred embodiment, the control valve connects the hot water recovery pipe and the hot water discharge pipe via a connecting flange. The branch pipe is integrated with the hot water recovery pipe. The branch pipe is connected to the first filter tank via a connecting flange, and the liquid outlet pipe is connected to the second filter tank via a connecting flange.

[0012] In a further preferred embodiment, the disassembly tank is placed in the middle section of the first filter tank and the second filter tank and connected by a connecting flange. The internal filter cylinder is fixed inside the disassembly tank by bolts. The internal filter cylinder is provided with multiple filter layers, namely carbon oxide filter material, high-strength alloy filter screen and particle packed bed.

[0013] In a further preferred embodiment, the liquid outlet pipe, the liquid distribution pipe, and the liquid drain pipe are connected by threaded pipes, and a valve is provided at the connection between the liquid outlet pipe and the liquid distribution pipe, and a valve is provided at the connection between the liquid drain pipe and the liquid outlet pipe. The liquid distribution pipe and the connecting pipe are connected to the waste heat recovery heat exchanger through threaded pipes, and a sealing ring is provided at each pipe connection.

[0014] In a further preferred embodiment, the connecting pipe is connected to the hot water discharge pipe via a threaded pipe, and a valve is connected to the connecting pipe. A sealing ring is provided at the connection point, and multiple heat exchanger pipes are distributed in a ring inside the waste heat recovery heat exchanger.

[0015] In a further preferred embodiment, the molten salt tank, the first filter tank, and the second filter tank are all connected to a discharge connector, and a valve is connected to the discharge connector via a connecting flange.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] A multi-stage filtration system (including a first filter tank, an internal filter cartridge in the disassembly tank, and a second filter tank) deeply filters the hot water generated in the molten salt tank, effectively removing impurities and ensuring the purity of the water entering the waste heat recovery heat exchanger. This not only prevents heat exchanger pipes from becoming clogged with impurities, thus reducing heat exchange efficiency, but also minimizes scale buildup on the pipe surfaces, extending the lifespan of the heat exchanger.

[0018] The waste heat recovery heat exchanger utilizes multiple heat exchanger pipes arranged in a ring to improve heat exchange efficiency, allowing for the full utilization of waste heat generated in the molten salt tank. This not only improves energy efficiency and reduces production costs but also contributes to achieving energy conservation and emission reduction goals.

[0019] The equipment is easy to assemble, with components securely connected via flanges and threaded pipes. Valves and sealing rings ensure sealing and controllability. During use, discharge and maintenance can be performed through the discharge connector, ensuring long-term stable operation of the device. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0021] Figure 2 This is a diagram showing the overall structure of the present invention;

[0022] Figure 3 This is a front view of the overall structure of this utility model;

[0023] Figure 4 This is a diagram illustrating the filter tank, disassembly tank, waste heat recovery heat exchanger, and piping of this utility model.

[0024] Figure 5 This is a cross-sectional view of the filter tank, disassembly tank, waste heat recovery heat exchanger, and pipeline of this utility model.

[0025] In the diagram: 1. Molten salt tank; 2. Sealing cover; 3. Locking assembly; 4. Hot water recovery pipe; 5. Branch pipe; 6. Control valve; 7. Hot water discharge pipe; 8. First filter tank; 9. Disassembly tank; 10. Second filter tank; 11. Internal filter cylinder; 12. Liquid outlet pipe; 13. Dividing pipe; 14. Drain pipe; 15. Waste heat recovery heat exchanger; 16. Inner cavity; 17. Connecting pipe. Detailed Implementation

[0026] To make the technical means, creative features, objectives and effects of this utility model easier to understand, the present utility model will be further described below in conjunction with specific embodiments.

[0027] like Figure 1 - Figure 5 As shown, a molten salt waste heat recovery device for melamine production mainly consists of a molten salt tank 1, a sealing cover 2, a locking assembly 3, and a hot water recovery pipe 4. The sealing cover 2 is fixedly installed on the top of the molten salt tank 1 via the locking assembly 3, while the hot water recovery pipe 4 is installed on the side wall of the molten salt tank 1. To better control the discharge of hot water, a control valve 6 is connected to the outer end of the hot water recovery pipe 4, and a branch pipe 5 is installed between the control valve 6 and the hot water recovery pipe 4. The outer end of the control valve 6 is connected to a hot water discharge pipe 7. Through the cooperation of these two parts, the effective discharge of hot water inside the molten salt tank 1 can be achieved.

[0028] The outer end of branch pipe 5 is connected to a first filter tank 8, and the outer end of the filter tank is connected to a disassembly tank 9. The inner end of disassembly tank 9 is connected to an internal filter cylinder 11, and the outer end of disassembly tank 9 is connected to a second filter tank 10. The tail end of the second filter tank 10 is connected to an outlet pipe 12, which is connected to the waste heat recovery heat exchanger 15 through a distributor pipe 13. The waste heat recovery heat exchanger 15 has an inner cavity 16, which is connected to the hot water discharge pipe 7 through a connecting pipe 17. Through the filtration effect of the internal filter cylinder 11, the adhesion and scaling on the surface of the heat exchanger pipes in the inner cavity 16 can be effectively reduced.

[0029] Control valve 6 is connected to hot water recovery pipe 4 and hot water discharge pipe 7 via connecting flanges. Branch pipe 5 is integrated with hot water recovery pipe 4, and branch pipe 5 is connected to the first filter tank 8 via connecting flanges. Discharge pipe 12 and second filter tank 10 are connected via connecting flanges. Disassembly tank 9 is placed between the first filter tank 8 and the second filter tank 10 and is connected via connecting flanges. Internal filter cylinder 11 is bolted to the inside of disassembly tank 9. The internal filter cylinder 11 contains multiple filter layers, including carbon oxide filter media, high-strength alloy filter screen, and a granular packed bed.

[0030] The outlet pipe 12, the distributor pipe 13, and the drain pipe 14 are connected by threaded pipes. Valves are installed at the connections between the outlet pipe 12 and the distributor pipe 13, and also at the connections between the drain pipe 14 and the outlet pipe 12. The distributor pipe 13 and the connecting pipe 17 are connected to the waste heat recovery heat exchanger 15 via threaded pipes. Sealing rings are installed at each pipe connection to ensure airtightness. The connecting pipe 17 is connected to the hot water discharge pipe 7 via threaded pipes. A valve is connected to the connecting pipe 17, and a sealing ring is installed at the connection. Multiple heat exchanger pipes are arranged in a ring inside the waste heat recovery heat exchanger 15 to improve heat exchange efficiency.

[0031] For ease of maintenance and cleaning, molten salt tank 1, first filter tank 8, and second filter tank 10 are all connected to discharge connectors, with valves connected to the discharge connectors via connecting flanges, so that discharge and maintenance operations can be performed when needed.

[0032] The sealing cap 2 is fixedly installed on the top of the molten salt tank 1 using the locking assembly 3, ensuring a tight seal between the sealing cap 2 and the molten salt tank 1 to prevent molten salt leakage. Next, a hot water recovery pipe 4 is installed on the side wall of the molten salt tank 1, ensuring a good seal at the connection between the hot water recovery pipe 4 and the molten salt tank 1. Then, a control valve 6 is connected to the outer end of the hot water recovery pipe 4, and a branch pipe 5 is installed between the control valve 6 and the hot water recovery pipe 4. The branch pipe 5 is integrally designed with the hot water recovery pipe 4 to ensure a secure connection. Next, the outer end of the branch pipe 5 is connected to the first filter tank 8 via a connecting flange. The disassembly tank 9 is then placed between the first filter tank 8 and the second filter tank 10, and connected to both via a connecting flange. An internal filter cylinder 11 is installed at the inner end of the disassembly tank 9 and secured with bolts to ensure the internal filter cylinder 11 remains stable inside the disassembly tank 9. Finally, an outlet pipe 12 is connected to the tail end of the second filter tank 10, and the outlet pipe 12 is connected to the second filter tank 10 via a connecting flange. Next, connect the outlet pipe 12, the distributor pipe 13, and the drain pipe 14 using threaded pipes, and install valves and sealing rings at the connections to ensure sealing and controllability. Finally, connect the connecting pipe 17 to the waste heat recovery heat exchanger 15 and the hot water discharge pipe 7 using threaded pipes, again installing valves and sealing rings at the connections. After assembly, check that all connections are properly sealed to ensure the device can operate normally.

[0033] During operation, the molten salt in molten salt tank 1 generates waste heat, and hot water enters the device through hot water recovery pipe 4. First, the hot water is regulated by control valve 6 and enters branch pipe 5, then undergoes preliminary filtration through first filter tank 8. Next, the hot water enters the internal filter cylinder 11 in disassembly tank 9 for further filtration. The internal filter cylinder 11 has multiple filter layers to effectively remove impurities from the water. The filtered hot water then enters second filter tank 10 through outlet pipe 12 for final filtration, ensuring water purity. Next, the hot water enters waste heat recovery heat exchanger 15 through distributor pipe 13 for heat exchange. Multiple heat exchanger pipes are arranged in a ring inside the waste heat recovery heat exchanger 15 to improve heat exchange efficiency. The hot water after heat exchange is discharged from the device through connecting pipe 17 and hot water discharge pipe 7. When maintenance and cleaning are required, discharge and maintenance operations can be performed through the discharge joints on molten salt tank 1, first filter tank 8, and second filter tank 10 to ensure long-term stable operation of the device.

[0034] All standard parts used in this utility model can be purchased from the market, and irregular parts can be customized according to the description and drawings. The specific connection methods of each part adopt conventional methods such as bolts, rivets, and welding that are mature in the prior art. The machinery, parts and equipment adopt conventional models in the prior art, and the circuit connection adopts conventional connection methods in the prior art, which will not be described in detail here.

[0035] The above are merely preferred embodiments of this utility model, but the scope of protection of this utility model is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this utility model, based on the technical solution and inventive concept of this utility model, should be included within the scope of protection of this utility model.

Claims

1. A molten salt waste heat recovery device for melamine production, comprising a molten salt tank (1), a sealing cover (2), a locking assembly (3), and a hot water recovery pipe (4), wherein the sealing cover (2) is installed on the molten salt tank (1) via the locking assembly (3), and the hot water recovery pipe (4) is installed on the side wall of the molten salt tank (1), characterized in that: The outer end of the hot water recovery pipe (4) is connected to a control valve (6), and a branch pipe (5) is provided between the control valve (6) and the hot water recovery pipe (4). The outer end of the control valve (6) is connected to a hot water discharge pipe (7). The hot water inside the molten salt tank (1) is discharged through the hot water recovery pipe (4) and the hot water discharge pipe (7). The outer end of the branch pipe (5) is connected to the first filter tank (8), the outer end of the first filter tank (8) is connected to the disassembly tank (9), the inner end of the disassembly tank (9) is connected to the internal filter cylinder (11), and the outer end of the disassembly tank (9) is connected to the second filter tank (10). The tail of the second filter tank (10) is connected to the liquid outlet pipe (12), and the liquid outlet pipe (12) is connected to the waste heat recovery heat exchanger (15) through the liquid distribution pipe (13). The waste heat recovery heat exchanger (15) has an inner cavity (16) inside. The inner cavity (16) is connected to the hot water discharge pipe (7) through the connecting pipe (17). Hot water filtration is achieved through the internal filter cylinder (11), reducing the scale adhesion on the surface of the heat exchanger pipe in the inner cavity (16).

2. The molten salt waste heat recovery device for melamine production according to claim 1, characterized in that: The control valve (6) connects the hot water recovery pipe (4) and the hot water discharge pipe (7) through a connecting flange. The branch pipe (5) is designed as an integral part of the hot water recovery pipe (4). The branch pipe (5) is connected to the first filter tank (8) through a connecting flange. The liquid outlet pipe (12) is connected to the second filter tank (10) through a connecting flange.

3. The molten salt waste heat recovery device for melamine production according to claim 2, characterized in that: The disassembly tank (9) is placed in the middle section of the first filter tank (8) and the second filter tank (10) and connected by a connecting flange. The internal filter cylinder (11) is fixed inside the disassembly tank (9) by bolts. The internal filter cylinder (11) is provided with multiple filter layers, namely zirconium oxide filter material, high-strength alloy filter screen and particle packed bed.

4. The molten salt waste heat recovery device for melamine production according to claim 3, characterized in that: The liquid outlet pipe (12), liquid distribution pipe (13) and liquid drain pipe (14) are connected by threaded pipes. A valve is provided at the connection between the liquid outlet pipe (12) and the liquid distribution pipe (13), and a valve is provided at the connection between the liquid drain pipe (14) and the liquid outlet pipe (12). The liquid distribution pipe (13) and the connecting pipe (17) are connected to the waste heat recovery heat exchanger (15) by threaded pipes. A sealing ring is provided at each pipe connection.

5. The molten salt waste heat recovery device for melamine production according to claim 4, characterized in that: The connecting pipe (17) is connected to the hot water discharge pipe (7) through a threaded pipe, and a valve is connected to the connecting pipe (17). A sealing ring is provided at the connection. Multiple heat exchanger pipes are distributed in a ring inside the waste heat recovery heat exchanger (15).

6. The molten salt waste heat recovery device for melamine production according to claim 5, characterized in that: The molten salt tank (1), the first filter tank (8), and the second filter tank (10) are all connected to a discharge connector, and a valve is connected to the discharge connector via a connecting flange.

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