High-nitration-degree energetic nitrocellulose acid-displacement washing system

Abstract

The present application relates to a kind of high-nitration degree energetic nitrocellulose acid displacement washing system, belong to chemical cellulose production field.The displacement acid-low tank (2), displacement acid-two low tank (3), displacement dilute acid low tank (4), displacement concentrated acid low tank (5) are connected with acid displacement machine (1) by acid-one pump (6), acid-two pump (7), dilute acid pump (8) and concentrated acid pump (9), displacement acid-low tank (2), displacement acid-two low tank (3), displacement dilute acid low tank (4) are equipped with densimeter (10), acid-two pump (7), dilute acid pump (8) and concentrated acid pump (9) branch pipe are equipped with branch pipe regulating valve (11), branch pipe regulating valve (11) is electrically connected with densimeter (10).The present application is adjusted by densimeter electric control loop, and the density gradient of each section displacement acid is adjusted gradually, and the dilution heat in displacement washing process is reduced.The problem that energetic nitrocellulose decomposition denitration can occur in displacement washing process is solved.

Description

Technical Field

[0001] This invention relates to a high-nitrification-degree energetic nitrocellulose acid displacement washing system, belonging to the field of chemical cellulose production. Background Technology

[0002] The acidic nitrocellulose mixture after cellulose esterification reaction enters a horizontal piston pusher centrifuge for acid separation and displacement washing. The centrifuge is divided into a high-concentration waste acid separation section and a displacement acid washing section. A multi-stage countercurrent continuous displacement washing process is adopted to recover the residual acid of the nitrocellulose. However, high-nitrification energetic nitrocellulose has poor thermal stability. The mixed acid used for high-nitrification energetic nitrocellulose has a high sulfuric acid content. During the displacement washing process, the nitrocellulose will decompose and denitrate, which seriously affects the product quality, especially in high-temperature and high-humidity seasons. In addition, the decomposition produces a large amount of nitrogen oxides, which poses serious safety and environmental risks. Summary of the Invention

[0003] The technical problem to be solved by this invention is that the high sulfuric acid content in the mixed acid used for high nitrification energetic nitrocellulose causes the nitrocellulose to decompose and denitrate due to the dilution heat during the displacement washing process.

[0004] The technical solution adopted by this invention to solve its technical problem is: a high-nitrification-degree energetic nitrocellulose acid displacement washing system, comprising an acid displacement machine, a low-level displacement acid tank (first), a low-level displacement acid tank (second), a low-level displacement dilute acid tank, and a low-level displacement concentrated acid tank. The inlets of the first, second, third, and fourth low-level displacement acid tanks are respectively connected to the outlet of the acid displacement machine. The low-level displacement acid tanks are further connected to the outlet of the acid displacement machine. The discharge port at the lower end of the concentrated acid low-level tank is connected to the inlet of the acid displacement machine via acid pump 1, acid pump 2, dilute acid pump and concentrated acid pump respectively. Density meters are installed on the acid pump 1, acid pump 2 and dilute acid low-level tank. The discharge ends of acid pump 2, dilute acid pump and concentrated acid pump are connected to the acid pump 1, acid pump 2 and dilute acid low-level tank respectively via branch pipes. A branch pipe regulating valve and a flow meter are installed on the branch pipe respectively. The branch pipe regulating valve is electrically connected to the density meter.

[0005] In the above system, the main outlet pipes of acid pump 1, acid pump 2, dilute acid pump and concentrated acid pump are respectively equipped with main pipe regulating valves, and the low-level tanks for acid 1, acid 2, dilute acid and concentrated acid are equipped with level gauges, and the main pipe regulating valves are electrically connected to the level gauges.

[0006] The acid removal machine in the above system is equipped with a perforated cylindrical nozzle, one end of which is sealed by a plug, and five nozzles are spaced apart along the shaft on the side wall of the nozzle.

[0007] Furthermore, the plug in the above system is fixed to the nozzle by a thread, and an anti-detachment pin is provided at the connection.

[0008] Furthermore, in the above system, the plug is fixed to the nozzle by a thread, and two weld points are symmetrically spot-welded at the connection.

[0009] Furthermore, the diameter of the nozzle in the above system is 4 to 6 mm.

[0010] In the above system, the acid pump 1, acid pump 2, dilute acid pump and concentrated acid pump are driven by frequency converters, and pressure gauges are installed at the outlets. The pressure gauges are electrically connected to the frequency converters, so that the acid washing pressure is kept constant at 0.2 MPa.

[0011] The system also includes an inclined screen, the inlet of which is connected to the outlet of the acid displacement machine, and the outlet is connected to the first low-level tank of displacement acid, the second low-level tank of displacement acid, the low-level tank of displacement dilute acid, the low-level tank of displacement concentrated acid, and the low-level tank of concentrated acid, respectively.

[0012] In the above system, the acid displacement machine for displacing concentrated acid and the outlet section of the concentrated acid section are equipped with wall-mounted thermometers.

[0013] The system also includes a three-way ball valve, which is installed on the outlet pipes of the concentrated acid section and the concentrated-to-concentrated acid section of the acid displacement machine. The third port of the three-way ball valve in the concentrated acid section is connected to the concentrated-to-concentrated acid section, and the connection point is located on the outlet pipe of the three-way ball valve in the concentrated-to-concentrated acid section.

[0014] The beneficial effects of this invention are: This system improves the acid displacement washing process, enhances the level of automation control in the washing process, improves the quality of high-nitrification-degree nitrocellulose products, and reduces the safety and environmental risks of the washing process. By adding online density detection to each section of the washing collection tank, and implementing segmented, step-by-step automatic reflux, all concentrated acid is circulated to the concentrated acid collection tank, and the concentrated acid is recovered for waste acid treatment. Partial replenishment of waste acid is used to adjust the density gradient of each section of the displacement washing process. Heat exchange equipment is added for automatic temperature control, strictly controlling the displacement washing temperature to not exceed 30℃, ensuring that the quality of high-nitrification-degree energetic nitrocellulose meets customer requirements. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the connection structure of the present invention.

[0016] Figure 2 This is a schematic diagram of the nozzle structure of the present invention.

[0017] Figure 3 This is a schematic diagram of the left-side structure of the present invention.

[0018] The diagram is labeled as follows: 1 is the acid displacement machine, 111 is the nozzle, 112 is the plug, 113 is the nozzle, 114 is the weld point, 2 is the low-level tank for acid displacement one, 3 is the low-level tank for acid displacement two, 4 is the low-level tank for dilute acid displacement, 5 is the low-level tank for concentrated acid displacement, 6 is the acid one pump, 7 is the acid two pump, 8 is the dilute acid pump, 9 is the concentrated acid pump, 10 is the density meter, 11 is the branch pipe regulating valve, 13 is the level gauge, 14 is the main pipe regulating valve, 15 is the frequency converter, 16 is the pressure gauge, 17 is the inclined screen, and 18 is the three-way ball valve. Detailed Implementation

[0019] The invention will be further described below with reference to the accompanying drawings.

[0020] like Figures 1 to 3As shown, the present invention discloses a high-nitrification-degree energetic nitrocellulose acid displacement washing system, comprising an acid displacement machine 1, a low-level displacement acid tank 2, a low-level displacement acid tank 3, a low-level displacement dilute acid tank 4, and a low-level displacement concentrated acid tank 5. The inlets of the low-level displacement acid tanks 2, 3, 4, and 5 are respectively connected to the outlet of the acid displacement machine 1. The lower outlets of the low-level displacement acid tanks 2, 3, 4, and 5 are... Acid pump 6, acid pump 7, dilute acid pump 8, and concentrated acid pump 9 are respectively connected to the inlet of the acid displacement machine 1. Density meters 10 are installed on the acid displacement tank 2, acid displacement tank 3, and dilute acid displacement tank 4. The outlets of acid pump 7, dilute acid pump 8, and concentrated acid pump 9 are connected to the acid displacement tank 2, acid displacement tank 3, and dilute acid displacement tank 4 respectively via branch pipes. Branch pipes are equipped with branch pipe regulating valves 11 and flow meters, and the branch pipe regulating valves 11 are electrically connected to the density meters 10. Those skilled in the art will understand that, in order to solve the decomposition and denitrification problem of high nitrification degree (≥215.2 ml / g) nitrocellulose during the displacement washing process, ensure the production of high nitrification degree B cotton, reduce denitrification during the acid displacement washing process, and thus guarantee product quality, this system needs to optimize the acid displacement washing process and precisely control the washing process to ensure that the product quality meets the requirements of the HZY industry. In practice, online density detection is added to each section of the washing and collection tanks. Specifically, densitometers 10 are installed on the low-level tanks 2 (displacement acid one), 3 (displacement acid two), and 4 (displacement dilute acid). The discharge ends of the acid pump 7, dilute acid pump 8, and concentrated acid pump 9 are connected to the low-level tanks 2, 3, and 4 respectively via branch pipes. Each branch pipe is equipped with a branch pipe regulating valve 11 and a flow meter. The branch pipe regulating valve 11 is electrically connected to the densitometer 10, realizing segmented and step-by-step automatic reflux. All concentrated acid is circulated to the concentrated acid collection tank, and the concentrated acid is recovered to the waste acid treatment. Partial replenishment with waste acid is used to adjust the density gradient of each section of the displacement washing process, reduce the dilution heat during the displacement washing process, and strictly control the displacement washing temperature to not exceed 30℃, ensuring that the quality of the high-nitrification energetic nitrocellulose meets customer requirements. Ball valves and regulating valves are added to the waste acid aerial collection pipeline. During normal production, a small amount of waste acid is added to the low-level tank 5 (displacement concentrated acid). Overflow pipelines were added to the low-level concentrated acid tank 5 to the waste acid tank. When the acid mixing machine's mother liquor collection is insufficient, the acid can be transferred to the waste acid tank for replenishment.

[0021] Preferably, in the above system, main pipe regulating valves 14 are respectively installed on the outlet main pipes of acid pump 6, acid pump 7, dilute acid pump 8, and concentrated acid pump 9; level gauges 13 are installed on the low-level tanks 2, 3, 4, and 5 of acid replacement; and the main pipe regulating valves 14 are electrically connected to the level gauges 13. Those skilled in the art will understand that this system adds regulating valves to the acid displacement pump 1 at each stage of the displacement acid inlet and level gauges 13 to the low-level tanks of the displacement acid, automatically interlocking and adjusting the flow rate according to the liquid level. Specifically, main pipe regulating valves 14 are respectively installed on the outlet main pipes of pump 6, acid pump 7, dilute acid pump 8, and concentrated acid pump 9; level gauges 13 are installed on the low-level tanks 2, 3, 4, and 5 of the displacement acid; and the main pipe regulating valves 14 are electrically connected to the level gauges 13.

[0022] Preferably, the acid removal machine 1 in the above system is equipped with a perforated cylindrical nozzle 111, one end of which is sealed by a plug 112, and five nozzles 113 are spaced apart along the axis on the side wall of the nozzle 111. Those skilled in the art will understand that this system preferably redesigns the washing nozzle 111, relying on a constant pressure acid supply automatic control system to avoid cross-contamination of the replacement acid within the acid removal machine 1 and reduce cross-contamination dilution heat; in practice, the fan-shaped nozzle 111 used for replacement washing in the acid removal machine 1 is replaced with a perforated cylindrical nozzle 111, and the nozzle 111 is installed in the acid removal machine 1 at the 4 o'clock position to avoid the reciprocating airflow of the acid removal machine 1 affecting the spray path of the washing acid. Preferably, the nozzle 111 has a perforated cylindrical nozzle structure, one end of which is sealed by a plug 112, and five nozzles 113 are spaced apart along the axis on the side wall of the nozzle 111.

[0023] Preferably, in the above system, the plug 112 is connected and fixed to the nozzle 111 by threads, and an anti-detachment pin is provided at the connection. Those skilled in the art will understand that the nozzle 111 preferably adopts a five-hole design, with a disassembly bolt (i.e., the plug 112) at the tail end for easy cleaning after clogging. Simultaneously, considering the vibration of the acid removal machine 1, an anti-detachment pin is provided at the threaded connection to ensure a secure connection.

[0024] Preferably, in the above system, the plug 112 is connected and fixed to the nozzle 111 by threads, and two weld points 114 are symmetrically spot-welded at the connection. Those skilled in the art will understand that, similarly considering the vibration of the acid removal machine 1, electric welding can also be preferred to achieve a firm connection between the plug 112 and the nozzle 111, and two weld points 114 can be symmetrically spot-welded at the connection.

[0025] Preferably, the diameter of the nozzle 113 in the above system is 4-6 mm. Those skilled in the art will understand that, considering the internal parameters of the reverse-drive acid generator 1, such as a flow velocity of 5 m / s and a maximum flow rate of 2000 L / h, based on the derivation of fluid dynamics VS = 0.785 μd², the diameter of a single nozzle 113 is 4-6 mm, with 4.6 mm being the preferred actual diameter.

[0026] Preferably, in the above system, the acid pump 6, acid pump 7, dilute acid pump 8, and concentrated acid pump 9 are driven by a frequency converter 15, and a pressure gauge 16 is installed at the outlet, and the pressure gauge 16 is electrically connected to the frequency converter 15, so that the acid washing pressure is kept constant at 0.2 MPa. Those skilled in the art will understand that this system preferably uses acid pump 6, acid pump 7, dilute acid pump 8, and concentrated acid pump 9 driven by a frequency converter 15, and a pressure gauge 16 is installed at the outlet, and the pressure gauge 16 is electrically connected to the frequency converter 15. This arrangement ensures that the replacement acid pump, through the interlocking of the frequency converter 15 and the pressure gauge 16, maintains a constant replacement acid washing pressure of 0.2 MPa, ensuring that the water column sprayed from the orifice nozzle 111 does not deviate and has sufficient penetration power into the cotton layer.

[0027] Preferably, the above system further includes an inclined screen 17, the inlet of which is connected to the outlet of the acid displacement machine 1, and the outlet of which is connected to the first low-level displacement acid tank 2, the second low-level displacement acid tank 3, the dilute acid low-level displacement tank 4, the concentrated acid low-level displacement tank 5, and the concentrated acid tank, respectively. Those skilled in the art will understand that, preferably, the acid displacement machine 1 is connected to the first low-level displacement acid tank 2, the second low-level displacement acid tank 3, the dilute acid low-level displacement tank 4, the concentrated acid low-level displacement tank 5, and the concentrated acid tank via the inclined screen 17.

[0028] Preferably, the acid displacement machine 1 in the above system is equipped with wall-mounted thermometers at the outlet section of the concentrated acid displacement section and the concentrated acid displacement section. Those skilled in the art will understand that this system preferably incorporates wall-mounted thermometers in the concentrated acid displacement section of the acid displacement machine 1 to monitor the dilution heat during the displacement washing process in real time. When the dilution heat temperature ≥ 35℃, the system must be immediately stopped for cleaning and sieving. Production can only resume after the specific gravity and temperature of the displacement acid meet the requirements.

[0029] Preferably, the above system also includes a three-way ball valve 18, which is respectively installed on the outlet pipes of the concentrated acid section and the concentrated-to-concentrated acid section of the acid displacement machine 1. The third interface end of the three-way ball valve 18 in the concentrated acid section is connected to the concentrated-to-concentrated acid section, and the connection point is located on the outlet pipe of the three-way ball valve 18 in the concentrated-to-concentrated acid section; the third interface end of the three-way ball valve 18 in the concentrated-to-concentrated acid section is connected to the concentrated acid section, and the connection point is located on the outlet pipe of the three-way ball valve 18 in the concentrated acid section. Those skilled in the art will understand that the system preferably adds a three-way ball valve 18 at the outlet of the concentrated-to-concentrated acid to ensure that all the concentrated acid is carried into the concentrated acid low-level tank during normal production. Adding a three-way ball valve 18 at the outlet of the concentrated acid to ensure that all or part of the concentrated acid is carried into the concentrated-to-concentrated acid tank during normal production ensures the stability of the specific gravity of the replaced concentrated acid.

Claims

1. A high-nitration-degree energetic nitrocellulose acid-displacement replacement washing system, comprising an acid-displacement machine (1), a replacement acid I low tank (2), a replacement acid II low tank (3), a replacement dilute acid low tank (4), and a replacement concentrated acid low tank (5), and the feed inlets of the replacement acid I low tank (2), the replacement acid II low tank (3), the replacement dilute acid low tank (4), and the replacement concentrated acid low tank (5) are connected with the discharge outlet of the acid-displacement machine (1), characterized in that: The lower outlets of the displacement acid one low-level tank (2), displacement acid two low-level tank (3), displacement dilute acid low-level tank (4), and displacement concentrated acid low-level tank (5) are respectively connected to the inlet of the acid displacement machine (1) via acid pump one (6), acid pump two (7), dilute acid pump (8), and concentrated acid pump (9). A density meter (10) is installed on the displacement acid one low-level tank (2), displacement acid two low-level tank (3), and displacement dilute acid low-level tank (4). The outlets of acid pump two (7), dilute acid pump (8), and concentrated acid pump (9) are respectively connected to the inlet of the acid displacement machine (1) via branch pipes. 3) The dilute acid low-level tank (4) is connected, and a branch pipe regulating valve (11) and a flow meter are respectively installed on the branch pipe. The branch pipe regulating valve (11) is electrically connected to the density meter (10). The main outlet pipes of the acid pump (6), acid pump (7), dilute acid pump (8) and concentrated acid pump (9) are respectively equipped with main pipe regulating valves (14). The dilute acid low-level tank (2), dilute acid low-level tank (3), dilute acid low-level tank (4) and concentrated acid low-level tank (5) are equipped with level gauges (13), and the main pipe regulating valve (14) is electrically connected to the level gauge (13). ​ 2. The high nitrification degree energetic nitrocellulose acid displacement washing system according to claim 1, characterized in that: Each replacement washing section inside the acid removal machine (1) is equipped with a perforated cylindrical nozzle (111), and one end of the nozzle (111) is sealed by a plug (112). Five nozzles (113) are spaced along the shaft on the side wall of the nozzle (111).

3. The acid displacement washing system for high nitrification degree energetic nitrocellulose according to claim 2, characterized in that: The plug (112) is connected and fixed to the nozzle (111) by threads, and an anti-detachment pin is provided at the connection.

4. The acid displacement washing system for high nitrification degree energetic nitrocellulose according to claim 2, characterized in that: The plug (112) is connected and fixed to the nozzle (111) by threads, and two weld points (114) are symmetrically spot-welded at the connection.

5. The acid displacement washing system for high nitrification degree energetic nitrocellulose according to claim 2, characterized in that: The diameter of the nozzle (113) is 4-6 mm.

6. The acid displacement washing system for high nitrification energetic nitrocellulose according to claim 1, characterized in that: The acid pump 1 (6), acid pump 2 (7), dilute acid pump (8) and concentrated acid pump (9) are driven by frequency converter (15), and pressure gauge (16) is installed at the outlet. The pressure gauge (16) is electrically connected to the frequency converter (15) so that the acid washing pressure is constant at 0.2 MPa.

7. The acid displacement washing system for high nitrification degree energetic nitrocellulose according to claim 1, characterized in that: It also includes an inclined screen (17), the inlet of which is connected to the outlet of the acid displacement machine (1), and the outlet is connected to the first low-level tank of replacement acid (2), the second low-level tank of replacement acid (3), the low-level tank of replacement dilute acid (4), the low-level tank of replacement concentrated acid (5) and the concentrated acid tank, respectively.

8. The acid displacement washing system for high nitrification degree energetic nitrocellulose according to claim 1, characterized in that: The acid removal machine (1) is equipped with a wall-mounted thermometer at the outlet section of the concentrated acid section and the outlet section of the concentrated acid section.

9. The acid displacement washing system for high nitrification degree energetic nitrocellulose according to claim 1, characterized in that: It also includes a three-way ball valve (18), which is respectively installed on the concentrated acid section and the concentrated acid section outlet pipeline of the acid removal machine (1), and the third interface end of the three-way ball valve (18) of the concentrated acid section is connected to the concentrated acid section, and the connection point is located on the outlet pipeline of the three-way ball valve (18) of the concentrated acid section; and the third interface end of the three-way ball valve (18) of the concentrated acid section is connected to the concentrated acid section, and the connection point is located on the outlet pipeline of the three-way ball valve (18) of the concentrated acid section.

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