CN114602222B - Intrinsically safe type energy-containing material is with filtering base - Google Patents

Abstract

The present invention relates to the technical field of energetic material processing, and in particular to an intrinsically safe filter base for energetic materials. The present invention comprises a lower cylinder and a filter disc detachably mounted at the top of the lower cylinder, wherein the filter disc and the cylinder cavity of the lower cylinder together enclose a mother liquid collection chamber for accommodating filtrate, and a discharge port is correspondingly arranged at the lower cylinder to connect to the mother liquid collection chamber; the filter disc is in the shape of a trumpet with a larger diameter at the top and a smaller diameter at the bottom, and a small port located at the axis of the filter disc constitutes a discharge port for discharging solid slurry, and the discharge port is connected to an external material collection device, and a switch valve that can open and close the discharge port is arranged on the discharge port. The present invention can effectively avoid the problem of deposition of filter cake particles, and ultimately provide a prerequisite guarantee for the safe and reliable implementation of the filtering and/or washing process of energetic materials.

Description

An intrinsically safe filter base for energetic materials

Technical Field

The invention relates to the technical field of energetic material processing, and in particular to an intrinsically safe energetic material filtering base.

Background technique

High-performance energetic materials include TNT, RDX, octogen, nitrogen-rich compounds and their derivatives, which are the prerequisite for improving the performance of advanced weapons. Unlike general explosives, their physical properties are more sensitive, contain explosive groups, can react quickly, and are extremely destructive; the slightest carelessness can lead to catastrophic consequences. The production process of high-performance energetic materials mostly uses concentrated nitric acid to directly decompose hexamethylenetetramine, and obtains the required energetic material crystal suspension through nitric acid cooking, crystallization, deacidification, recrystallization and other processes, and then obtains a crystal filter cake with a certain moisture content through washing and filtration, and then obtains the final product through drying and grading. Washing and filtration are essential processes in the production process of energetic materials and are also important processes related to the quality of the final product. There are many types of energetic material crystals, such as α crystal, β crystal, γ crystal, etc. Different crystals have very different physical properties, such as viscosity, fluidity, crystal volume, strength, explosive performance, stability performance, etc., which have a great impact on the quality of energetic materials. During the washing process of energetic materials, the mother liquor washed out has a certain viscosity, and it is easy to precipitate crystals, forming a "hanging wall" phenomenon; the filter cake crystals have different crystal forms, and the particle size distribution is wide. The coarse crystal particles are very easy to deposit, causing local solid accumulation and forming safety hazards; in addition, in the washing and filtering process, the materials include concentrated nitric acid, water or organic solvents such as acetone and ethyl acetate. The temperature is generally controlled below 100°C. The equipment needs to have high temperature and pressure conditions. In addition to hazardous chemicals such as nitric acid and organic solvents such as acetone and ethyl acetate, there are also various mixed crystal forms of energetic materials with unstable performance and explosiveness. Therefore, the filtering and washing equipment must meet the following requirements: First, the equipment must be closed, pressure-bearing, and temperature-resistant. Second, the equipment must be inherently safe; for example, the part in contact with the material must not have hidden dangers such as extrusion or collision, and there must be no hard friction and extrusion, etc.; it can be fully automatically operated to achieve unmanned production process and avoid accidental injuries. Third, the volume of the mother liquor collection chamber should be large, and the mother liquor after washing should flow smoothly, form a certain speed, and not easily stagnate. Fourth, the coarse crystal particles in the filter cake are not easy to deposit, and there is a certain amount of deposition space. Finally, the traditional filter screen structure is a flat-bottom type. Due to the low linear velocity at the center of the blade, the filter cake particles are very easy to deposit, resulting in a solid accumulation area in the center of the filter disc; the mother liquid cavity is small, and because the cavity bottom is a flat bottom structure, the mother liquid has poor fluidity and a small volume, which easily forms mother liquid stagnation or dead corners, causing crystal precipitation. The above situation is no longer in line with current needs and technological development, and needs to be solved urgently.

Summary of the invention

The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide an intrinsically safe filter base for energetic materials, which can effectively avoid the deposition problem of filter cake particles and ultimately provide a prerequisite guarantee for the safe and reliable filtering and/or washing process of energetic materials.

To achieve the above object, the present invention adopts the following technical solutions:

A filter base for intrinsically safe energetic materials, characterized in that it comprises a lower cylinder and a filter disc detachably mounted at the top cylinder mouth of the lower cylinder, the filter disc and the cylinder cavity of the lower cylinder together enclose a mother liquid collection chamber for accommodating filtrate, and a discharge port is correspondingly arranged at the lower cylinder to connect with the mother liquid collection chamber; the filter disc has an outer shape of a trumpet-shaped mouth with a larger diameter at the top and a smaller diameter at the bottom, and a small port located at the axis of the filter disc constitutes a discharge port for discharging solid slurry, the discharge port is connected to an external material collection device, and a switch valve that can open and close the discharge port is arranged on the discharge port.

Preferably, the lower cylinder is a rotating body, and its axial section is "W"-shaped; flange holes are arranged at the top cylinder mouth and the middle boss of the lower cylinder, and pull rods are correspondingly arranged at the top edge and bottom edge of the filter disc; a lifting ring is arranged at the top of the pull rod for facilitating lifting the filter disc, and the bottom end of the pull rod passes through the lower cylinder in a vertical direction through the matching flange hole and then is fixed by a nut; the switch valve is an upward-expanding discharge valve, and the valve port of the switch valve is flush with the small port of the filter disc.

Preferably, the bottom surface of the lower cylinder is spherical, and the liquid discharge port connected to the mother liquid collection chamber is located at the lowest end of the "W"-shaped lower cylinder.

Preferably, a reinforcing ring is coaxially protruding downward on the lower surface of the filter disc, and the reinforcing rings are coaxial with each other to form a concentric ring layout; the reinforcing rings are connected to each other by radial ribs, thereby forming a grid-like reinforcing structure on the bottom surface of the filter disc; there is a gap between the reinforcing structure and the bottom surface of the lower cylinder for the mother liquid to flow.

Preferably, transverse ribs and longitudinal ribs are arranged on the bottom surface of the lower cylinder, so as to form a grid-like fixed structure on the outer bottom surface of the lower cylinder.

Preferably, the outer cylindrical surface of the filter disc is a conical surface with a larger diameter at the top and a smaller diameter at the bottom, and a matching countersunk hole with a larger diameter at the top and a smaller diameter at the bottom is correspondingly arranged at the top opening of the lower cylinder body, so that a coaxial plug-in fit is formed between the two.

Preferably, the filter disc comprises a multi-layer metal sintered mesh made of stainless steel 304 or 316L or duplex stainless steel 2205 with a filtration accuracy of 20 μm; the inner ring of the metal sintered mesh is coaxially installed with an inner ring flange to form the top edge, and the outer ring of the metal sintered mesh is coaxially installed with an outer ring flange to form the bottom edge.

Preferably, the valve core of the switch valve is sprayed with plastic material; and a plastic guide sleeve is added at the connection between the valve stem and the valve body of the switch valve.

Preferably, universal casters are arranged at the lower cylinder for easy movement.

The beneficial effects of the present invention are:

1) Through the above scheme, the present invention provides a filter base structure, which can be adapted to existing filters or washing machines or filter-washing machines, etc., and can even be used as an independent accessory to match other energetic material processing equipment, thereby ensuring the safety and efficiency of energetic materials during the processing process.

In actual operation, on the one hand, the filter disc of the present invention forms a detachable structure with the lower cylinder, so that the filter disc and the lower cylinder cooperate to form a mother liquid collection chamber during operation, and the filter disc can be removed at any time during cleaning to fully expose all mother liquid contact parts, so as to achieve thorough cleaning and avoid the occurrence of safety hazards such as flow short circuit caused by crystal precipitation and accumulation. On the other hand, for the problem of solid slurry accumulation in conventional filter discs, the present invention not only ensures the convergence of solid slurry to the middle through the cone-shaped filter disc structure; at the same time, the discharge port arranged in the middle also realizes the timely removal of solid slurry, thereby avoiding explosions and other hidden dangers caused by excessive accumulation of solid slurry.

Thus, the present invention avoids safety hazards such as the risk of coarse crystal particles in the filter cake being deposited, thereby improving the safety of the equipment; the present invention can effectively avoid the problem of the deposition of filter cake particles, and ultimately provide a prerequisite guarantee for the safe and reliable filtering and/or washing process of energetic materials.

2) The "W"-shaped lower cylinder can achieve a rapid drainage effect for the mother liquor, avoid the mother liquor staying in the mother liquor collection chamber for a long time, and reduce the possibility of crystal precipitation and accumulation as much as possible. It is more noteworthy that the cooperation between the filter disc and the lower cylinder is achieved by the flange structure at the inner and outer rings. On the one hand, each flange cooperation is independent and far away from the mother liquor collection chamber and the working chamber above the filter disc. Compared with conventional threaded fasteners exposed in the working chamber or the mother liquor collection chamber, this is safer and avoids the explosion of energetic materials caused by actions such as threaded fastening. On the other hand, the switch valve also uses a specific upward-expanding discharge valve to minimize the impact on explosive solid slurry and even crystallization, and the safety of use can be significantly improved.

3) The setting of the reinforcement structure not only ensures the working strength of the filter disc itself, but also provides a gap between the reinforcement structure and the bottom surface of the lower cylinder for the flow of mother liquid, so as to ensure the rapid flow of mother liquid in the mother liquid collection chamber, thus achieving multiple goals at one stroke.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the assembly structure of the present invention;

FIG2 is a schematic cross-sectional view of the structure of the filter disc;

FIG3 is a schematic cross-sectional view of the structure of the lower cylinder;

FIG4 is a schematic diagram of the structure of a switch valve;

FIG5 is a schematic diagram of the arrangement of the reinforcement structure;

FIG6 is a schematic diagram of the arrangement of the fixed structure;

Figure 7 is a longitudinal section velocity vector diagram when the distance from the stirring paddle to the filter disc is 50 mm;

Figure 8 is a longitudinal section turbulent kinetic energy diagram when the distance from the impeller to the filter disc is 50 mm.

The actual correspondence between the reference numerals and component names of the present invention is as follows:

10-Filter disc 11-Discharge port 12-Switch valve

13-tie rod 14-lifting ring 15-nut 16-reinforcement ring 17-radial rib plate

20-lower cylinder 20a-top cylinder mouth 20b-middle crown

21-Drainage port 22-Outer ring 23-Horizontal rib plate 24-Vertical rib plate

30-upper cylinder 40-stirring assembly

41-Stirring motor 42-Stirring shaft 43-Stirring paddle

50-Spray assembly 51-Spray pipe 52-Spray ball

60-frame 70-vertical piston cylinder 80-jacket 90-coil

Detailed ways

For ease of understanding, one embodiment of the present invention is taken as an example to further describe the specific application structure and working method of the present invention as follows:

The specific implementation structure of the present invention can be shown in Figures 1-6, and its overall structure includes a barrel part, a stirring assembly 40, a spray assembly 50 and a frame 60, etc. Among them:

The cylinder part is a pressure container, and the design pressure, design temperature, equipment material, etc. are in accordance with the specific requirements of the energetic material process. The upper cylinder 30 and the spherical lower cylinder 20 constituting the cylinder part are matched through the stopper to form a closed, pressure-bearing container, which is the material working space, that is, the filtering and washing chamber. Concentrated nitric acid, water or organic solvents such as acetone, ethyl acetate, and energetic materials are stirred, mixed, washed and filtered in this material working space. The upper cylinder 30 is generally composed of a straight section of the cylinder, a jacket 80 and/or a coil 90, a head, a flange, etc. The head is generally provided with a material inlet, a washing liquid inlet, a pressure gauge port, a safety valve port, an air inlet, an exhaust port, etc., which will not be described one by one.

During operation, the outer ring body 22 at the lower cylinder 20 can be pushed by the vertical piston cylinder 70, so that the lower cylinder 20 and the filter plate 10 can move downward relative to the upper cylinder 30, thereby exposing the present invention as a whole.

The stirring assembly 40 stands on the head of the upper cylinder 30, and its output shaft is coaxially arranged with the upper cylinder 30. The stirring assembly 40 is generally composed of a stirring motor 41, a reducer, etc., so as to output a certain range of rotation speed and torque to meet the stirring and mixing needs during the washing and filtration process and the scraping needs during the slag discharge process. The stirring shaft 42 is also coaxially arranged with the upper cylinder 30, passing through the head at the upper cylinder 30, and the stirring shaft 42 synchronously receives the rotation speed and torque output by the stirring motor 41. A stirring paddle 43 is provided at the bottom end of the stirring shaft 42, and the bottom surface of the stirring paddle 43 is a certain distance from the upper surface of the truncated cone filter disc 10, generally more than 50 mm, to avoid hard friction and extrusion between the stirring paddle 43 and the filter cake.

As shown in Figure 1, a spray assembly 50 is also provided at the upper cylinder 30, specifically including a spray pipe 51 and a spray ball 52 for washing arranged at the spray pipe 51. The number and size of the spray balls 52 are rotated according to the diameter and height of the upper cylinder 30. The spray balls 52 should not be made of metal to avoid the safety hazards caused by metal friction; polytetrafluoroethylene or nozzle types can be used. During operation, the closed cavity formed by the upper surface of the filter disc 10 and the inner surface of the upper cylinder 30 is the area where the materials are stirred, mixed, washed and filtered, and is the working cavity. The effective volume and slag area of the working cavity are designed according to the process parameters such as the solid content and liquid content of the energetic material.

Furthermore, as shown in Fig. 1-2, the filter plate 10 is in the shape of a truncated cone funnel or a trumpet, with the center being the lowest point and the discharge port 11 for the solid slurry; this design avoids the potential safety hazard of easy accumulation of slurry solids due to the minimum stirring line speed in the center of the existing equipment. The filter plate 10 is integral and can be hoisted as a whole by a hoisting ring, so that all mother liquid contact parts are completely exposed and thoroughly cleaned.

The specific structure of the filter disc 10 is as follows: According to the material process requirements, a multi-layer metal sintered mesh with suitable metal material and suitable filtering accuracy is selected and made into a truncated cone shape. The large end is welded to the outer ring flange, and the small end is welded to the outer ring flange. For the convenience of lifting, the outer cylindrical surface of the outer ring flange is provided with a taper, which is a large taper at the top and a small taper at the bottom. At the same time, the upper surface of the outer ring flange is uniformly provided with lifting rings 14, generally three; the lower surface of the outer ring flange and the inner ring flange are fixed with tie rods 13 to be fixedly connected with the matching nuts 15; the top barrel mouth 20a and the middle crown 20b of the lower cylinder 20 are correspondingly arranged with flange holes, so as to correspond to the matching tie rods 13 one by one. Since the tie rod 13 and the nut 15 are completely independent, that is, they do not contact the material, so as to avoid the thread squeezing the material to cause a safety accident, thus avoiding possible safety risks. During actual assembly, the corresponding parts need to be sealed at the matching places. To ensure strength, a reinforcing ring can also be provided at the inner ring flange according to the pressure requirements.

The lower cylinder 20 cooperates with the filter disc 10 to form a mother liquid collection chamber. Under the action of pressure, the mother liquid in the material passes through the multi-layer metal sintered mesh of the filter disc 10 and is concentrated in the mother liquid collection chamber. Because the mother liquid collection chamber has a large volume and a large slope produced by the "W"-shaped design of the lower cylinder 20 itself, the mother liquid is not easy to stagnate, and the mother liquid has good fluidity, which solves the problem of crystal precipitation caused by the poor flow of the mother liquid caused by the flat-bottomed structure. When the filter disc 10 is hoisted as a whole, the mother liquid collection chamber is completely exposed, and manual intervention can be performed regularly to thoroughly clean the mother liquid collection chamber to avoid crystal precipitation and accumulation causing flow short circuits.

In order to solve the problem of supporting strength of the metal sintered mesh, as shown in Figures 5-6, a series of spoke ribs can be provided in the mother liquid collection chamber, and their number, wall thickness, etc. are related to the diameter and pressure of the lower cylinder 20. Specifically, referring to Figure 5, a reinforcing ring 16 and a radial rib 17 are arranged on the bottom surface of the filter disc 10 to form a reinforcing structure; at the same time, the reinforcing structure does not contact the inner bottom surface of the lower cylinder 20 and has a certain distance, which is the flow channel of the mother liquid. Through the above design, the reinforcing structure presents a grid shape of a certain size, which provides good support for the metal sintered mesh and prevents the metal sintered mesh from being deformed and damaged by pressure under pressure. As shown in Figure 6, the outer bottom surface of the lower cylinder 20 is arranged with a transverse rib 23 and a longitudinal rib 24, thereby forming a well-grid type fixed structure to further strengthen the lower cylinder 20.

Furthermore, to ensure smooth flow of the mother liquid, a series of mother liquid outlets, namely, discharge ports 21, are provided at the lowest position of the mother liquid collection chamber, and their number and diameter are related to the diameter of the lower cylinder 20, material properties, and the like.

During actual assembly, the switch valve 12 shown in FIG3 needs to be installed at the inner flange of the filter disc 10 and docked with the discharge port 11 for discharging solid slurry. The switch valve 12 is generally an upward-spreading discharge valve. To prevent hard friction with energetic materials, the valve core of the switch valve 12 needs to be sprayed with plastic materials, such as F40 or F30; a plastic guide sleeve, generally made of polytetrafluoroethylene, needs to be added at the connection between the valve stem and the valve body to prevent the material from being brought into the valve body by the valve stem and causing safety accidents due to extrusion.

Figures 7-8 disclose the longitudinal section velocity vector diagram and longitudinal section turbulent kinetic energy diagram when the distance from the stirring paddle 43 to the filter disc 10 is 50 mm. In actual operation, it was found that when the height of the stirring paddle 43 was increased, the flow state of the fluid in the cylinder part did not change much, and the fluid at the bottom of the paddle flowed, but the effect was not obvious; and when the distance from the stirring paddle 43 to the filter disc 10 increased, the low turbulent kinetic energy area at the center of the bottom of the paddle was significantly expanded; this shows that blindly increasing the height of the stirring paddle will have a certain adverse effect on the stirring effect of the material at the bottom of the tank; research has found that 50 mm is the best distance for specific use.

Of course, it will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the present invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

The techniques, shapes, and structural parts not described in detail in the present invention are all well-known techniques.

Claims (9)

1. An intrinsically safe energetic material filtration base, characterized in that: the device comprises a lower cylinder body (20) and a filter disc (10) detachably assembled at a cylinder opening at the top of the lower cylinder body (20), wherein the filter disc (10) and a cylinder cavity of the lower cylinder body (20) are jointly enclosed to form a mother liquor collecting cavity for containing filtrate, and liquid draining ports (21) are correspondingly arranged at the lower cylinder body (20) so as to be communicated with the mother liquor collecting cavity; the appearance of the filter disc (10) is in a horn mouth shape with a large caliber and a small caliber, a small port positioned at the axle center of the filter disc (10) forms a discharge port (11) for discharging solid slurry, the discharge port (11) is communicated with external collecting equipment, and a switch valve (12) capable of opening and closing the discharge port (11) is arranged on the discharge port (11);

the lower cylinder body (20) is a revolution body, and the axial section of the lower cylinder body is in a W shape; flange holes are uniformly distributed at the top cylinder opening (20 a) and the middle crown table (20 b) of the lower cylinder (20), and pull rods (13) are correspondingly arranged at the top edge and the bottom edge of the filter disc (10); the top end of the pull rod (13) is provided with a hanging ring (14) which is convenient for hanging the filter disc (10), and the bottom end of the pull rod (13) vertically penetrates out of the lower cylinder body (20) through a matched flange hole and is then fixed by a screw cap (15).

2. A filter base for intrinsically safe energetic materials according to claim 1, wherein: the switch valve (12) is an upward-expansion discharge valve, and a valve port of the switch valve (12) is flush with a small port of the filter disc (10).

3. A filter base for intrinsically safe energetic materials according to claim 2, wherein: the bottom surface of the lower cylinder body (20) is spherical, and a liquid outlet (21) communicated with the mother liquor collecting cavity is positioned at the lowest end of the W-shaped lower cylinder body (20).

4. A filter base for intrinsically safe energetic materials according to claim 1 or 2 or 3, wherein: reinforcing rings (16) are coaxially and downwardly arranged on the lower surface of the filter disc (10) in a protruding mode, and the reinforcing rings (16) are mutually coaxial to form a concentric annular layout; the reinforcing rings (16) are connected with each other through radial rib plates (17), so that a grid-shaped reinforcing structure is formed at the bottom of the filter disc (10); a gap for the flow of mother liquor is reserved between the reinforcing structure and the bottom surface of the lower cylinder body (20).

5. The intrinsically safe energetic material filtration bed of claim 4, wherein: the bottom surface of the lower cylinder body (20) is provided with a transverse rib plate (23) and a longitudinal rib plate (24), so that a grid-shaped fixing structure is formed on the outer bottom surface of the lower cylinder body (20).

6. A filter base for intrinsically safe energetic materials according to claim 2 or 3, characterized in that: the outer cylindrical surface of the filter disc (10) is a conical surface with a large diameter and a small diameter, and the top cylinder opening (20 a) is correspondingly provided with a matched counter bore with a large diameter and a small diameter, and the two are coaxially inserted and matched.

7. A filter base for intrinsically safe energetic materials according to claim 2 or 3, characterized in that: the filter disc (10) comprises a metal sintering net with a multilayer structure, wherein the metal sintering net is made of stainless steel 304 or 316L or duplex stainless steel 2205 and has the filtering precision of 20 mu m; the inner ring flange is coaxially arranged on the inner ring of the metal sintering net to form the top edge, and the outer ring flange is coaxially arranged on the outer ring of the metal sintering net to form the bottom edge.

8. A filter base for intrinsically safe energetic materials according to claim 1 or 2 or 3, wherein: spraying plastic material on a valve core of the switch valve (12); a plastic guide sleeve is additionally arranged at the joint of the valve rod and the valve body of the switch valve (12).

9. A filter base for intrinsically safe energetic materials according to claim 1 or 2 or 3, wherein: the lower cylinder body (20) is provided with universal casters which are convenient to move.