Anti-blocking pneumatic conveying device

Abstract

The utility model provides an anti-blocking pneumatic conveying device. Comprising an air supply unit, a material storage unit, a material receiving unit and a control unit, an airflow pipeline, a first branch, a second branch and a third branch are arranged between the air supply unit and the material storage unit; one end of the airflow pipeline is connected with the air supply unit, and the other end of the airflow pipeline is connected with the inlet end of the first branch, the inlet end of the second branch and the inlet end of the third branch. A conveying pipeline is arranged between the material storage unit and the material receiving unit and comprises a horizontal section, a bent section and a vertical section, and the two ends of the bent section are connected with the horizontal section and the vertical section correspondingly; the control unit is electrically connected with the gas flow meter, the first pressure sensor, the second pressure sensor and the third pressure sensor. According to the anti-blocking pneumatic conveying device, the air speed in the pipeline can be regulated and controlled in real time, and the situation that materials are blocked in the pneumatic conveying process is effectively avoided.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of anti-blocking pneumatic conveying devices. BACKGROUND

[0002] Biomass, as a renewable energy, has broad application prospects under the background of "double carbon target" and energy supply structure transformation. By achieving safe, stable, continuous and efficient pneumatic conveying of biomass powder, important reference can be provided for the design of biomass gasification devices in industry, thereby promoting the efficient use of biomass energy.

[0003] In practical applications, in order to reduce the wear of the pipeline and the particles, and considering the economy of the system, it is more desirable to conduct pneumatic conveying of biomass powder at a lower gas velocity. However, when the gas velocity is reduced to a certain critical value, the pipeline will be blocked. In industrial applications, once the pneumatic conveying device for biomass powder is blocked, it will seriously affect the downstream process flow, and even cause serious production consequences. SUMMARY

[0004] In order to overcome the defect that the prior art pneumatic conveying device is prone to blockage, the utility model provides an anti-blocking pneumatic conveying device; the anti-blocking pneumatic conveying device can real-time regulate and control the gas velocity in the pipeline, effectively avoiding the blockage of the material during pneumatic conveying.

[0005] The utility model provides a kind of anti-blocking pneumatic conveying device, it includes gas supply unit, material storage unit, material receiving unit and control unit;Gas supply unit with the material storage unit between being equipped with airflow pipeline, first branch, second branch and third branch;The one end of airflow pipeline is connected with the gas supply unit, the other end is respectively connected with the inlet end of the first branch, the inlet end of the second branch, the inlet end of the third branch;The bottom of material storage unit is equipped with discharge port;Material storage unit with the material receiving unit between being equipped with conveying pipeline, the conveying pipeline includes horizontal section, bending section and vertical section, the both ends of the bending section are connected with the horizontal section and the vertical section respectively;The outlet end of the first branch, the outlet end of the second branch are connected with the material storage unit;The outlet end of the third branch is connected with the conveying pipeline;Airflow pipeline is equipped with gas flow meter;The horizontal section, the bending section, the vertical section are equipped with first pressure sensor, second pressure sensor, third pressure sensor respectively;The control unit is electrically connected with the gas flow meter, the first pressure sensor, the second pressure sensor, the third pressure sensor respectively, for converting the pressure signal received into gas flow control signal, to regulate and control the gas flow meter.

[0006] In some embodiments, the conveying pipe comprises, in sequence, a first vertical section, a first bending section, a horizontal section, a second bending section, a second vertical section and a third bending section, in the direction of material conveying from the material storage unit to the receiving unit; the first pressure sensor is arranged on the horizontal section, the second pressure sensor is arranged on the second bending section, and the third pressure sensor is arranged on the second vertical section.

[0007] In specific embodiments, the first pressure sensor is arranged on the horizontal section close to the first bending section.

[0008] In specific embodiments, the second pressure sensor is arranged at the center of the second bending section.

[0009] In specific embodiments, the third pressure sensor is arranged on the second vertical section close to the second bending section.

[0010] In specific embodiments, the diameter of the conveying pipe is 0.01-0.2 m.

[0011] In specific embodiments, a first valve is arranged on the first vertical section.

[0012] In specific embodiments, the outlet end of the third branch is connected to the first vertical section, for controlling the flow state of the material.

[0013] In some embodiments, the outlet end of the first branch is connected to the upper or middle part of the material storage unit, for maintaining the internal pressure of the material storage unit; the outlet end of the second branch is arranged below the outlet end of the first branch and is connected to the upper part of the discharge port of the material storage unit, for loading the material for discharge.

[0014] In some embodiments, second, third and fourth valves are arranged on the first, second and third branches, respectively.

[0015] In some embodiments, the receiving unit comprises a reactor or a collector.

[0016] In some embodiments, a thermometer is arranged on the horizontal section, the bending section and the vertical section.

[0017] In some embodiments, the control unit comprises input module, calculation module, judgment module and output module set in sequence; the input module is used for importing input data into the calculation module, the input data comprising gas volume flow, pressure in the conveying pipeline and gas temperature in the conveying pipeline; the gas volume flow is measured by a gas flow meter, the pressure in the conveying pipeline is measured by a pressure sensor arranged in the conveying pipeline, and the gas temperature in the conveying pipeline is measured by a thermometer arranged in the conveying pipeline; the calculation module is used for calculating conveying gas velocity in the conveying pipeline according to the input data; the judgment module is used for judging the size relationship between the conveying gas velocity and the critical choking gas velocity; if the conveying gas velocity is greater than the critical choking gas velocity, the input data is collected again, and the calculation and judgment are sequentially performed again; if the conveying gas velocity is less than or equal to the critical choking gas velocity, an adjustment signal of the gas flow is obtained; and the output module is used for feeding back the adjustment signal to the gas flow meter and performing regulation and control.

[0018] On the basis of common knowledge in the art, the above-mentioned preferred conditions can be combined arbitrarily, i.e. to obtain each preferred example of the present application.

[0019] The reagent and raw material used in the present application are commercially available.

[0020] The positive progress effect of the present application is that:

[0021] The anti-blocking pneumatic conveying device of the present application can realize real-time measurement and control of the actual gas velocity of the pipeline, so that it is always greater than the critical choking gas velocity, thereby avoiding pipeline blockage and effectively reducing the blockage risk of the material in the pneumatic conveying process. The present application has important guiding significance for the design and safe and efficient operation of the biomass powder pneumatic conveying device in industrial applications. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 Figure 1 is a structural schematic diagram of the anti-blocking pneumatic conveying device of Example 1;

[0023] Figure 2 Figure 2 is a force decomposition diagram of a single particle in the horizontal section of the conveying pipeline using the anti-blocking pneumatic conveying device of Example 1;

[0024] Figure 3 Figure 3 is a force decomposition diagram of a single particle in the vertical section of the conveying pipeline using the anti-blocking pneumatic conveying device of Example 1;

[0025] Figure 4 Figure 4 is a force decomposition diagram of a single particle in the bending section of the conveying pipeline using the anti-blocking pneumatic conveying device of Example 1;

[0026] Figure 5 Figure 5 is a control flow schematic diagram of the anti-blocking pneumatic conveying device of Example 1;

[0027] Reference signs:

[0028] Gas supply unit 1

[0029] Air flow pipe 101

[0030] First branch 102

[0031] Second branch 103

[0032] Third branch 104

[0033] Gas flow meter 2

[0034] Material storage unit 3

[0035] First pressure sensor 4

[0036] Second pressure sensor 5

[0037] Third pressure sensor 6

[0038] Material receiving unit 7

[0039] Control unit 8

[0040] Conveying pipe 9

[0041] First vertical section 901

[0042] First bent section 902

[0043] Horizontal section 903

[0044] Second bent section 904

[0045] Second vertical section 905

[0046] Third bent section 906

[0047] First valve 10

[0048] Second valve 11

[0049] Third valve 12

[0050] Fourth valve 13 DETAILED DESCRIPTION

[0051] The utility model will be described in more detail below with reference to the preferred embodiments and drawings.

[0052] Embodiment 1

[0053] The embodiment discloses an anti-blocking pneumatic conveying device. Figure 1 The structure diagram of the anti-blocking pneumatic conveying device of the embodiment.

[0054] The anti-blocking pneumatic conveying device comprises a gas supply unit 1, a material storage unit 3, a material receiving unit 7 and a control unit 8; a gas flow pipeline 101, a first branch 102, a second branch 103 and a third branch 104 are arranged between the gas supply unit 1 and the material storage unit 3; one end of the gas flow pipeline 101 is connected with the gas supply unit 1, and the other end is connected with the inlet end of the first branch 102, the inlet end of the second branch 103 and the inlet end of the third branch 104 respectively; a discharge port is arranged at the bottom of the material storage unit 3; a conveying pipeline 9 is arranged between the material storage unit 3 and the material receiving unit 7, and the material conveying direction from the material storage unit 3 to the material receiving unit 7 comprises a first vertical section 901, a first bending section 902, a horizontal section 903, a second bending section 904, a second vertical section 905 and a third bending section 906 in sequence; the outlet end of the first branch 102 and the outlet end of the second branch 103 are connected with the material storage unit 3; the outlet end of the third branch 104 is connected with the conveying pipeline 9; a gas flow meter 2 is arranged on the gas flow pipeline 101; a first pressure sensor 4 is arranged on the horizontal section 903, a second pressure sensor 5 is arranged on the second bending section 904, and a third pressure sensor 6 is arranged on the second vertical section 905; the control unit 8 is electrically connected with the gas flow meter 2, the first pressure sensor 4, the second pressure sensor 5 and the third pressure sensor 6 respectively, and is used for converting the received pressure signals into gas flow control signals to regulate and control the gas flow meter 2.

[0055] The first pressure sensor 4 is arranged on the horizontal section 903 close to the first bending section 902; the second pressure sensor 5 is arranged at the center of the second bending section 904; the third pressure sensor 6 is arranged on the second vertical section 905 close to the second bending section 904; the pipe diameter of the conveying pipeline 9 is 0.2m; the first valve 10 is arranged on the first vertical section 901; the outlet end of the third branch 104 is connected to the first vertical section 901, and is used for controlling the flow state of the material.

[0056] The outlet end of the first branch 102 is connected to the upper part of the material storage unit 3, and is used for maintaining the internal pressure of the material storage unit 3; the outlet end of the second branch 103 is arranged below the outlet end of the first branch 102 and above the discharge port of the material storage unit 3, and is used for loading the material to discharge.

[0057] The first branch 102, the second branch 103 and the third branch 104 are respectively provided with a second valve 11, a third valve 12 and a fourth valve 13; the material receiving unit 7 is a collector; a thermometer is arranged on each horizontal section, each bending section and each vertical section.

[0058] The control unit 8 includes an input module, a calculation module, a judgment module, and an output module set sequentially. The input module is used to import input data into the calculation module. The input data includes gas volumetric flow rate, pressure in the delivery pipeline, and gas temperature in the delivery pipeline. The gas volumetric flow rate is measured by the gas flow meter 2, the pressure in the delivery pipeline 9 is measured by the pressure sensor installed in the delivery pipeline 9, and the gas temperature in the delivery pipeline 9 is measured by the thermometer installed in the delivery pipeline 9. The calculation model is used to calculate the delivery gas velocity in the delivery pipeline 9 based on the input data. The judgment model is used to determine the relationship between the delivery gas velocity and the critical blockage gas velocity. If the delivery gas velocity is greater than the critical blockage gas velocity, the input data is collected again, and the calculation and judgment are performed sequentially again. If the delivery gas velocity is less than or equal to the critical blockage gas velocity, a gas flow rate adjustment signal is obtained. The output module is used to feed back the adjustment signal to the gas flow meter for regulation.

[0059] Application Example 1

[0060] This application example discloses a method for establishing a pneumatic conveying model.

[0061] The object being transported in this application example has a particle density of 1608 kg / m³. 3 The biomass powder has an equivalent sphere diameter of 313.41 μm; the conveying gas is compressed air; the inner diameter of the conveying pipeline is 0.2 m. The density ρ of the compressed air is... g Calculations need to be performed based on the pressure and gas temperature of the pipeline; the dynamic viscosity is taken as 1.79 × 10⁻⁶. -6 Pa·s, ρ g The calculation method is as follows:

[0062]

[0063] Where P is the absolute pressure of the pipeline, Pa; M is the molar mass of the gas, g / mol; R is the ideal gas constant, with a value of 8.314 J / (mol·K); and T is the gas temperature, K.

[0064] The method for establishing the pneumatic conveying model includes the following steps:

[0065] Step S1: Obtain 18 sets of fitting data (6 sets for horizontal segments, 6 sets for vertical segments, and 6 sets for bends). Each set of fitting data includes the transition velocity U in the conveying pipeline. g,s and the transition velocity U g,s The corresponding critical clogging velocity U g,cb ;

[0066] The conveying pipeline 9 comprises in sequence a first vertical section 901, a first bending section 902, a horizontal section 903, a second bending section 904, a second vertical section 905 and a third bending section 906;

[0067] The following is the calculation method of the force that the particles can be subjected to in the conveying pipeline:

[0068] The gravity of the particles F G :

[0069]

[0070] Wherein, π is the circular constant; d V is the volume average particle size of the conveying particles, m; ρ p is the density of the conveying particles, kg / m 3 ; g is the acceleration of gravity, m / s 2 .

[0071] According to Archimedes' principle, the buoyancy F B exerted by the gas on the particles is equal to the gravity of the gas displaced by the particles:

[0072]

[0073] Wherein, π is the circular constant; d V is the volume average particle size of the conveying particles, m; ρ g is the density of the conveying gas, kg / m 3 ; g is the acceleration of gravity, m / s 2 .

[0074] The Saffman lift F L caused by the velocity gradient of the gas:

[0075]

[0076] Wherein, μ g is the dynamic viscosity of the conveying gas, Pa·s; ρ g is the density of the conveying gas, kg / m 3 ; d V is the volume average particle size of the conveying particles, m; U g is the velocity of the conveying gas, m / s; U p is the velocity of the conveying particles, m / s; is the velocity U g of the conveying gas in the direction perpendicular to the conveying direction.

[0077] The drag force F D is calculated as follows:

[0078]

[0079] wherein C D is the drag coefficient, C D is 0.44; π is the circular constant; d V is the volume average particle size of the conveyed particles, m; ρ p is the density of the conveyed particles, kg / m 3 ; U g is the velocity of the conveying gas, m / s; and U p is the velocity of the conveyed particles, m / s.

[0080] Centrifugal force F C is calculated as follows:

[0081]

[0082] wherein π is the circular constant; d V is the volume average particle size of the conveyed particles, m; ρ p is the density of the conveyed particles, kg / m 3 ; U p is the velocity of the conveyed particles, m / s; and r is the bending radius of the bend, m.

[0083] The critical choking gas velocity is closely related to the suspension and settlement of single particles in the vertical direction and the collision effect of particle groups. The motion state of single particles in the vertical direction can be characterized by the transition velocity. The following is the way to obtain the calculation formula of the transition velocity in the horizontal section, vertical section and bend:

[0084] a) Analyze the force on a single particle near the bottom of the pipeline during horizontal pneumatic conveying. Figure 2 is a force decomposition diagram of a single particle in the horizontal section of the conveying pipeline in the application embodiment. As Figure 2 shown, the particle moves horizontally along the x direction. In the y direction, the particle is mainly subjected to the action of gravity F G , buoyancy F B and lift F L . In the horizontal section, F G is the main force causing the particle to settle. F B is derived from the static pressure difference on the surface of the particle, which is vertically upward, and its size is equal to the weight of the gas with the same volume as the particle. F L is mainly derived from the radial gas velocity gradient in the pipeline; the closer to the wall, the smaller the gas flow rate, and the flow rate in the center of the pipeline is the largest. According to Bernoulli's equation, the upper pressure of the particle near the bottom of the pipeline is small, and the lower pressure is large, thereby forming the vertically upward lift.

[0085] For the equation of motion of a single particle in the horizontal section: Since the gas density is usually much smaller than the particle density, the buoyancy can be ignored. According to Newton's second law, the equation of motion of a single particle near the bottom of the pipeline in the y direction in the horizontal section can be established as:

[0086]

[0087] Where, m p is the mass of the conveying particles, kg; F G is the gravity of the conveying particles, N; F L is the Saffman lift of the conveying particles, N; is the rate of change of the conveying particle velocity U p with time t, U p is the velocity of the conveying particles, m / s.

[0088] Substituting equations (1) and (3) into equation (6) gives:

[0089]

[0090] Since the gas motion in the boundary layer near the wall surface in the pipeline can usually be considered as a linear shear flow process, the corresponding gas velocity gradient is constant. Therefore, the gas velocity gradient term in equation (7) can be expressed as:

[0091]

[0092] Where, U g is the conveying gas velocity, m / s; D is the inner diameter of the conveying pipeline, m.

[0093] It is assumed that the particles are in a suspended state in the initial state, and as the gas velocity decreases, the lift experienced by the particles decreases. Under the action of gravity, the particles will begin to settle. The minimum gas velocity required to maintain the particles in suspension is defined as the particle transition velocity. When the pipeline gas velocity is less than this velocity, the particles will settle, and otherwise the particles will be vertically lifted.

[0094] Substituting the boundary conditions U p = 0, and equation (8) into equation (7), a calculation model for the particle transition velocity in the horizontal section can be established as:

[0095]

[0096] Where, U g,s ’ is the transition velocity in the horizontal section of the conveying pipeline, m / s; π is the circular constant; d V is the volume average particle size of the conveying particles, m; ρ p is the density of the conveying particles, kg / m3 ; g is the acceleration of gravity, m / s 2 ; p g is the density of the conveying gas, kg / m 3 ; m g is the dynamic viscosity of the conveying gas, Pa-s; D is the inner diameter of the conveying pipe, m.

[0097] b) Analyzing the force conditions of a single particle near the bottom of the pipe in the pneumatic conveying process in the second vertical section. Figure 3 is a force decomposition diagram of a single particle in the vertical section of the conveying pipe in the embodiments of the present application. As shown in Figure 3 , the particle moves vertically along the y direction. In the x direction, the solid particle is mainly subjected to the action of gravity F G , buoyancy F B , lift F L and drag F D . Unlike the horizontal section, the lift F L experienced by the single particle in the vertical section is mainly derived from the axial velocity difference of the gas. The pressure difference between the upper and lower parts of the particle forms the lift F D . F p is derived from the flow around the particle formed when the gas flows through the particle, and its size mainly depends on the slip velocity between the gas and the particle, the windward area of the particle and the drag coefficient.

[0098] For the motion equation of the single particle in the second vertical section: due to the small axial pressure gradient, the buoyancy and the lift can be ignored. According to Newton's second law, the motion equation of the single particle in the x direction in the pneumatic conveying process in the vertical section can be established as follows:

[0099]

[0100] Substituting equations (1) and (4) into equation (10) can obtain:

[0101]

[0102] When the sum of the forces in the x direction of the particle is 0, the acceleration of the particle in the x direction disappears. When the axial velocity of the particle is 0, the particle reaches the critical suspension state. Substituting the boundary conditions and U p = 0 into equation (11), the particle transition velocity calculation model in the vertical section can be established as follows:

[0103]

[0104] wherein, U g,s ” is the transition velocity in the vertical section of the conveying pipe, m / s; d V is the volume average particle size of the conveyed particles, m; p pThe density of the conveyed particles, kg / m³ 3 g is the acceleration due to gravity, m / s² 2 ;ρ g The density of the transported gas is kg / m³. 3 C D It is the drag coefficient, C D The value is 0.44.

[0105] In equation (12), C D Size and particle Reynolds number Re p Closely related, Re p Calculate using the following formula: Re p =ρ g (U g -U p )d V / μ g With Re p As the velocity increases, the particle motion occurs in the laminar, transition, and turbulent regions, respectively. To simplify the calculation, the drag coefficient corresponding to the turbulent region, C, is taken. D =0.44.

[0106] c) Analyze the force situation of a single particle near the bottom of the pipeline during the pneumatic conveying process in the second bend section. Figure 4 This is a force decomposition diagram of a single particle in the bend of the conveying pipeline in this application embodiment. For example... Figure 4 As shown, the particles move upwards at an angle; where θ represents the angle between the conveying gas velocity and the horizontal plane. In the x-direction, the solid particles are mainly subjected to gravity F. G buoyancy F B Lift F L traction force F D and centrifugal force F C The function of F. C It originates from the circular motion of the particles along the bend and is an imaginary force. The suspension and settling of particles in the pipe depends on the forces acting on the particles in the vertical direction.

[0107] For the equation of motion of a single particle in the second bend: the buoyancy force on the particle can be neglected. When passing through the bend, the particle's direction of motion gradually transitions from horizontal motion (θ = 0°) to vertical motion (θ = 90°). Therefore, it is necessary to integrate all forces acting on the particle from θ = 0° to θ = 90°, and then, according to Newton's second law, establish the equation of motion of the powder particle in the vertical direction:

[0108]

[0109] Simplifying equation (13) yields:

[0110]

[0111] Substituting equations (1), (3), (4) and (5) into equation (14), we have:

[0112]

[0113] Substituting the boundary conditions and U p = 0 into equation (15), we can establish a model for calculating the transition velocity of particles in the elbow section:

[0114]

[0115] wherein, U g,s ”’ is the transition velocity of particles in the elbow section of the conveying pipeline, m / s; d V is the volume average particle size of the conveyed particles, m; p p is the density of the conveyed particles, kg / m 3 ; g is the acceleration of gravity, m / s 2 ; p g is the density of the conveying gas, kg / m 3 ; m g is the dynamic viscosity of the conveying gas, Pa·s; D is the inner diameter of the conveying pipeline, m; C D is the drag coefficient, C D = 0.44.

[0116] wherein, d V is measured by a particle size analyzer; p p is measured by a particle density meter; p g is calculated by the average pressure of the conveying pipeline and the ambient temperature.

[0117] S2, the collision effect of the particle group can be characterized by the solid mass flux. The faster the motion velocity of the particles, the higher the solid concentration, and the more intense the collision between the particles in the group and the pipe wall. The calculation formula of the solid mass flux is:

[0118] m s = U p C s (17)

[0119] The way to obtain the pneumatic conveying model formula IV is to determine the functional relationship between the critical choking gas velocity and the solid mass flux:

[0120]

[0121] Substitute the above fitting data into the pneumatic conveying model, wherein the pneumatic conveying model is as follows:

[0122]

[0123] wherein U g,cb is the critical choking velocity in the conveying pipe, m / s; U g,s is the transition velocity in the conveying pipe, m / s; m s is the mass flux of the conveyed particles, kg / (m 2 ·s); a, b are fitting coefficients.

[0124] wherein U p is the velocity of the conveyed particles, m / s; C s is the solid concentration, kg / m 3 .

[0125] According to the position of the particles in the conveying pipe (horizontal section, vertical section or bending section), six groups of pneumatic conveying experiments are carried out under different solid mass fluxes. According to equation (18), the parameter a is obtained by power function fitting. The parameter a is substituted into equation (19) to obtain the parameter b by proportional function fitting.

[0126] wherein under the conditions of a pipe inner diameter of 0.02 m, m s = 302, 451, 605 kg / (m 2 ·s) three solid mass fluxes and a pipe inner diameter of 0.05 m, m s = 557, 692, 934 kg / (m 2 ·s) three solid mass fluxes, biomass powder pneumatic conveying experiments are carried out. Specifically, the experimental test method of the critical choking velocity U g,cb is as follows: by controlling the constant conveying pressure difference so that the solid mass flux remains constant, then gradually reducing the adjusting gas (the third branch 104) until the pipe is blocked. According to the total air intake amount, pipe temperature and pressure at the time of blocking, the critical choking velocity U g,cb can be calculated.

[0127] The value of U g,s is calculated according to the calculation formula of step S1, and equation 19 is fitted, and the fitted parameters a, b are substituted into equation (19). In equation (19), U g,cb is obtained by the above conveying experiment test, and U g,s is calculated by known parameters such as dv, p g .

[0128] The critical choking velocity under different pipe inner diameters and solid mass fluxes can be calculated, and the results are shown in Table 1. Table 1 is the analysis results of the actual value and the calculated value of the critical choking velocity under different inner diameters of the conveying pipe and solid mass fluxes. The deviation is calculated as follows: (U g,cb calculated value-U g,cb actual value) / U g,cbActual value x 100%.

[0129] Table 1

[0130]

[0131] From the above table, it can be seen that the deviation between the calculated value of the critical choking gas velocity and the actual value of the critical choking gas velocity is within ±11.70% by using the embodiment to calculate the critical choking gas velocity; further, the deviation between the calculated value of the critical choking gas velocity and the actual value of the critical choking gas velocity is within ±6% in most cases, effectively meeting the calculation requirement of the critical choking gas velocity of the biomass pneumatic conveying system.

[0132] Application Example 2

[0133] The application example discloses a control method of pneumatic conveying.

[0134] Figure 5 is a control flow diagram when the application example adopts the pneumatic conveying system.

[0135] The control method of pneumatic conveying comprises the following steps:

[0136] ss1, collecting pneumatic conveying information to calculate the conveying gas velocity U of the conveying gas according to formula V g ; the pneumatic conveying information comprises the inner diameter D of the conveying pipeline, the pressure P of the conveying pipeline, the temperature T of the conveying gas, and the volume flow Q of the conveying gas;

[0137]

[0138] ss2, comparing the conveying gas velocity U of the conveying gas g with the critical choking gas velocity U g,cb ; the critical choking gas velocity U g,cb is calculated by the pneumatic conveying model established in Example 1;

[0139] When U g is greater than U g,cb , repeat step S1 to continuously monitor the conveying gas velocity of the conveying gas;

[0140] When U g is less than or equal to U g,cb , adjust the volume flow Q of the conveying gas, and repeat step S1 to keep U g greater than U g,cb .

[0141] In addition to the above control method, the target conveying gas velocity U g,tThe maximum deviation between the calculated value and the actual value of the critical choking gas velocity can also be set. According to the calculation deviation result of Embodiment 1, the predicted deviation between the calculated value and the actual value of the critical choking gas velocity is mostly within ±6%, and the maximum deviation is -11.7%. Therefore, the target conveying gas velocity U g,t The control is in the critical choking gas velocity U g,cb 111.7% of the calculated value, that is, U g,t > 1.117U g,cb . U g,t The higher the calculated value of the critical choking gas velocity is above the calculated value, the higher the corresponding energy consumption is, but the anti-blocking safety redundancy of the conveying system is greater.

Claims

1. A choke free pneumatic conveying apparatus characterized by, It comprises a gas supply unit, a material storage unit, a material receiving unit and a control unit; The gas supply unit is connected with the material storage unit through a gas flow pipeline, a first branch, a second branch and a third branch; one end of the gas flow pipeline is connected with the gas supply unit, and the other end is connected with the inlet end of the first branch, the inlet end of the second branch and the inlet end of the third branch respectively; The bottom of the material storage unit is provided with a discharge port; The material storage unit is connected with the material receiving unit through a conveying pipeline, which comprises a horizontal section, a bending section and a vertical section, and the two ends of the bending section are connected with the horizontal section and the vertical section respectively; The outlet end of the first branch and the outlet end of the second branch are connected with the material storage unit; the outlet end of the third branch is connected with the conveying pipeline; A gas flow meter is arranged on the gas flow pipeline; first, second and third pressure sensors are arranged on the horizontal section, the bending section and the vertical section respectively; the control unit is electrically connected with the gas flow meter, the first pressure sensor, the second pressure sensor and the third pressure sensor respectively, for converting the received pressure signals into gas flow control signals to regulate and control the gas flow meter.

2. A choke free pneumatic conveying apparatus as claimed in claim 1 wherein, From the material conveying direction of the material storage unit to the material receiving unit, the conveying pipeline comprises a first vertical section, a first bending section, a horizontal section, a second bending section, a second vertical section and a third bending section in sequence; The first pressure sensor is arranged on the horizontal section, the second pressure sensor is arranged on the second bending section, and the third pressure sensor is arranged on the second vertical section.

3. A choke free pneumatic conveying apparatus as claimed in claim 2, wherein, The conveying pipeline satisfies one or more of the following conditions: ① The first pressure sensor is arranged on the horizontal section close to the first bending section; ② The second pressure sensor is arranged at the center of the second bending section; ③ The third pressure sensor is arranged on the second vertical section close to the second bending section; ④ The diameter of the conveying pipeline is 0.01-0.2 m.

4. The choke-free pneumatic conveying apparatus as claimed in claim 2, wherein, A first valve is arranged on the first vertical section.

5. The choke-free pneumatic conveying apparatus as claimed in claim 2, wherein, The outlet end of the third branch is connected to the first vertical section for controlling the flow state of the material.

6. The choke free pneumatic conveying apparatus as claimed in claim 1, wherein, The outlet end of the first branch is connected to the upper part or the middle part of the material storage unit for maintaining the internal pressure of the material storage unit; The outlet end of the second branch is arranged below the outlet end of the first branch and above the discharge port of the material storage unit for loading the material for discharge.

7. The choke free pneumatic conveying apparatus as claimed in claim 1, wherein, Second, third and fourth valves are arranged on the first, second and third branches respectively.

8. The choke free pneumatic conveying apparatus as claimed in claim 1, wherein, The material receiving unit comprises a reactor or a collector.

9. The choke free pneumatic conveying apparatus as claimed in claim 1, wherein, Thermometers are arranged on the horizontal section, the bending section and the vertical section.

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