Method and system for simulating the separation of residual sludge inorganic sand in a hydrocyclone

Abstract

This invention provides a method and system for simulating the separation of residual sludge and inorganic sand in a hydrocyclone, comprising: Step 1: obtaining centrifugation simulation parameters; Step 2: collecting representative residual sludge, recording the total volume, loading the residual sludge into centrifuge tubes and transferring them into a centrifuge; Step 3: starting the centrifuge, and after centrifugation is complete, removing the centrifuge tubes, extracting the concentrated material at the bottom of the centrifuge tubes (representing the representative sample of the hydrocyclone underflow material), and removing the remaining material from the centrifuge tubes (representing the representative sample of the hydrocyclone overflow material); Step 4: analyzing the samples to obtain simulation results of the actual effect of the hydrocyclone in separating residual sludge and inorganic sand. This invention, through experimental and simulation verification combined with material characteristics and the features of the hydrocyclone, proposes centrifugation simulation parameters and their determination method. The calculation process is simple, the method is scientific and reasonable, and it can accurately verify the actual separation effect of the hydrocyclone.

Description

Technical Field

[0001] This invention relates to the field of environmental protection technology, and more specifically, to a method and system for simulating the separation of residual sludge and inorganic sand using a hydrocyclone. Background Technology

[0002] A hydrocyclone is a separation and classification device based on the principle of centrifugal sedimentation. The device consists of a cylinder, a cone, an inlet, an overflow outlet, and a bottom outlet. The residual sludge to be separated enters the hydrocyclone tangentially from its periphery under pressure. Due to differences in density and particle size, different particles experience varying degrees of centrifugal force, centripetal buoyancy, and fluid drag. Most of the coarse inorganic sand particles and some sludge flocs are discharged through the bottom outlet, while most of the fine inorganic sand particles and sludge flocs are discharged through the overflow pipe, thus achieving separation and classification. Because the separation effect of a hydrocyclone is closely related to its inner diameter, verifying the actual separation effect of residual sludge and inorganic sand usually requires building a pilot-scale hydrocyclone. Small-scale verification experiments cannot be conducted in the laboratory, making the verification research process for the actual separation effect quite complex and time-consuming.

[0003] Centrifugation is a commonly used method for separation, purification, and concentration in the water treatment industry's laboratory analysis. It utilizes the powerful centrifugal force generated by the high-speed rotation of an object to cause suspended particles in the rotating body to settle, thus separating and concentrating solid substances from a mixture. Centrifugation is typically achieved using a centrifuge, and its process is similar to that of a hydrocyclone. Under suitable centrifugal speed and time conditions, the concentrated material at the bottom of the centrifuge tube is the underflow of the hydrocyclone, and the remaining material at the top of the centrifuge tube is the overflow. By analyzing the relevant indicators of the concentrated material at the bottom of the centrifuge tube and the remaining material at the top, the separation effect of the corresponding hydrocyclone on residual sludge and inorganic sand can be verified. Therefore, using a centrifuge + centrifuge tube method to simulate the separation of hydrocyclones is feasible.

[0004] The key to the aforementioned small-scale simulation experiment using a centrifuge and centrifuge tubes lies in determining the centrifugation simulation parameters. For a hydrocyclone of a specific size to be validated, appropriate centrifugal speed, centrifugal force, and centrifugation time need to be selected during centrifuge simulation. The centrifugal speed and centrifugal force are related to the size of the hydrocyclone, the feed pressure, and the tangential velocity of the material within the hydrocyclone. The centrifugation time is equivalent to the residence time of the material within the hydrocyclone. Furthermore, the sampling volume of the concentrated material at the bottom of the centrifuge tube needs to be determined. This volume is equivalent to the underflow volumetric flow rate at the bottom of the hydrocyclone during separation and is related to the hydrocyclone split ratio, i.e., the ratio of the underflow volume to the total volume. This value needs to be determined by considering the target hydrocyclone size, feed pressure, and historical empirical parameters.

[0005] Patent document CN104462816A describes a method for accurately determining the separation particle size of a hydrocyclone, comprising the following steps: 1. Determining the structural parameters of the target hydrocyclone, the operating parameters of the target working condition, and the physical property parameters of the material to be separated; 2. Establishing a flow field domain calculation model based on the above parameters and discretizing it, while determining the boundary conditions and initial conditions for the calculation; 3. Performing simulation calculations using commercial computational fluid dynamics software and commercial discrete element method software; 4. Obtaining the particle size distribution curves of the material to be separated in the overflow and sediment products through the simulation calculation results, thereby determining the separation particle size d50 of the hydrocyclone under the target working condition. However, this patent cannot solve the existing technical problems. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method and system for simulating the separation of residual sludge and inorganic sand using a hydrocyclone.

[0007] The method for simulating the separation of residual sludge and inorganic sand using a hydrocyclone according to the present invention includes:

[0008] Step 1: Obtain centrifugation simulation parameters;

[0009] Step 2: Collect representative residual sludge and record the total volume V. T The remaining sludge is loaded into centrifuge tubes and transferred into a centrifuge. The centrifuge speed and centrifugation time are set according to the centrifugation simulation parameters.

[0010] Step 3: Start the centrifuge. After centrifugation is complete, remove the centrifuge tube. First, remove the concentrated material from the bottom of the centrifuge tube, taking a sample volume of V. con This is a representative sample of the underflow material of the hydrocyclone. Then, the remaining material in the centrifuge tube is taken out by tilting, which is a representative sample of the overflow material of the hydrocyclone.

[0011] Step 4: Analyze representative samples of the underflow material and overflow material of the hydrocyclone according to the experimental requirements to obtain the simulation results of the actual effect of the hydrocyclone in separating residual sludge and inorganic sand.

[0012] Preferably, the centrifuge simulation parameters include basic hydrocyclone parameters, generalized hydrocyclone parameters, and centrifuge simulation parameters. The determination process is as follows: determine the basic hydrocyclone parameters; determine the generalized hydrocyclone parameters based on the basic hydrocyclone parameters; and calculate the centrifuge simulation parameters based on the generalized hydrocyclone parameters.

[0013] Preferably, the basic parameters of the hydrocyclone include: feed flow rate Q, hydrocyclone inner diameter D, hydrocyclone overflow outlet outer diameter D0, hydrocyclone overflow outlet inner diameter d0, hydrocyclone underflow outlet inner diameter d, hydrocyclone overflow pipe insertion depth h0, hydrocyclone bottom cone angle α, and hydrocyclone column section height H. C Height H of the hydrocyclone cone section Z The height h from the bottom outlet of the hydrocyclone to the apex of the cone section z Hydrocyclone target separation particle size d 50 The theoretical split ratio P of the hydrocyclone and the average tangential velocity of the fluid inside the hydrocyclone.

[0014] The feed flow rate Q, the inner diameter D of the hydrocyclone, the outer diameter D0 of the hydrocyclone overflow outlet, the inner diameter d0 of the hydrocyclone overflow outlet, the inner diameter d of the hydrocyclone bottom outlet, the insertion depth h0 of the hydrocyclone overflow pipe, the bottom cone angle α of the hydrocyclone, and the column height H of the hydrocyclone are specified. C Height H of the hydrocyclone cone section Z The height h from the bottom outlet of the hydrocyclone to the apex of the cone section z Hydrocyclone target separation particle size d 50 The theoretical split ratio P of the hydrocyclone is determined based on the actual parameters of the hydrocyclone being simulated.

[0015] The average tangential velocity of the fluid inside the hydrocyclone The determination process is as follows:

[0016] Establish a spherical coordinate system with the apex of the hydrocyclone cone as the origin. In a cylindrical coordinate system (r, θ, z) and a rectangular coordinate system (x, y, z), for any point in the coordinate system, s is the distance from that point to the origin. Let θ be the angle between the position vector of the point and the z-axis, θ be the angle between the projection of the position vector of the point on the xy plane and the x-axis, r be the distance from the point to the z-axis, x be the perpendicular distance from the point to the yz plane, y be the perpendicular distance from the point to the xz plane, and z be the perpendicular distance from the point to the xy plane.

[0017] Based on the calculation formulas (1) to (3) and the structural characteristics of the hydrocyclone, the r of the characteristic point f in the cylindrical coordinate system is obtained. f z f spherical coordinates

[0018]

[0019] z f =H Z +H C +hz -h0…………(2)

[0020]

[0021] The characteristic parameter σ is obtained according to the calculation formula (4);

[0022]

[0023] Based on formulas (5) to (7), the z-coordinates of the characteristic point c located at the cylindrical-cone interface of the hydrocyclone in cylindrical coordinates are calculated. c spherical coordinate system r in cylindrical coordinates c ; where feature point c is in spherical coordinates Based on the dimensionless flow function of the hydrocyclone, the expression is obtained by graphical method and is given by formula (6).

[0024] z c =H Z +h z …………(5)

[0025]

[0026]

[0027] Based on the characteristic parameter σ and the r of the characteristic point c in cylindrical coordinates c Based on the basic parameters of the hydrocyclone, an expression for the tangential velocity of the fluid in the hydrocyclone is established, which is formula (8).

[0028] The hydrocyclone is transformed into a generalized model, and the calculation point k(r) is selected in the hydrocyclone. k , z k The average tangential velocity of the fluid inside the hydrocyclone is calculated according to formula (9). The number of calculation points n ≥ 500;

[0029]

[0030]

[0031] Preferably, the generalized parameters of the hydrocyclone include: Reynolds number R. e Froude number F r Centrifugal inertial force I g The process for determining the hydraulic residence time t is as follows:

[0032] The Reynolds number R e It is calculated according to formula (10);

[0033]

[0034] Where ρ is the liquid density and μ is the liquid dynamic viscosity;

[0035] The Froude number F r It is calculated according to formula (11);

[0036]

[0037] Where g is the acceleration due to gravity;

[0038] The centrifugal inertial force I g It is calculated according to formula (12);

[0039]

[0040] The hydraulic residence time t is calculated according to formula (13);

[0041]

[0042] Preferably, the centrifuge simulation parameters include: centrifugation speed (RPM), centrifugal force (G), centrifugation time (T), and the volume of concentrated material sampled from the bottom of the centrifuge tube (V). con The determination process is as follows:

[0043] The process for determining the centrifugal speed RPM is as follows:

[0044] The centrifugal linear velocity V is calculated according to formula (14);

[0045]

[0046] Where, r ct The centrifugal radius of the centrifuge;

[0047] The centrifugal speed RPM is calculated according to formula (15);

[0048]

[0049] Wherein, CEILING is a rounding function that rounds up the multiple, and the result is a multiple of 100;

[0050] The centrifugal force G is calculated according to formula (16);

[0051]

[0052] The centrifugation time T is calculated according to formula (17);

[0053] T = [t]…………(17)

[0054] V, the volume of concentrated material sampled from the bottom of the centrifuge tubecon It is calculated according to formula (18);

[0055] V con =V T P…………(18)

[0056] Among them, V T This represents the total volume of the liquid feed.

[0057] The system for simulating the separation of residual sludge and inorganic sand using a hydrocyclone according to the present invention comprises:

[0058] Module M1: Acquire centrifugation simulation parameters;

[0059] Module M2: Collect representative residual sludge and record the total volume V. T The remaining sludge is loaded into centrifuge tubes and transferred into a centrifuge. The centrifuge speed and centrifugation time are set according to the centrifugation simulation parameters.

[0060] Module M3: Start the centrifuge. After centrifugation is complete, remove the centrifuge tubes. First, remove the concentrated material from the bottom of the centrifuge tubes. The sample volume is V. con This is a representative sample of the underflow material of the hydrocyclone. Then, the remaining material in the centrifuge tube is taken out by tilting, which is a representative sample of the overflow material of the hydrocyclone.

[0061] Module M4: Based on the experimental requirements, analyze representative samples of the underflow material and the overflow material of the hydrocyclone to obtain simulation results of the actual effect of the hydrocyclone in separating residual sludge and inorganic sand.

[0062] Preferably, the centrifuge simulation parameters include basic hydrocyclone parameters, generalized hydrocyclone parameters, and centrifuge simulation parameters. The determination process is as follows: determine the basic hydrocyclone parameters; determine the generalized hydrocyclone parameters based on the basic hydrocyclone parameters; and calculate the centrifuge simulation parameters based on the generalized hydrocyclone parameters.

[0063] Preferably, the basic parameters of the hydrocyclone include: feed flow rate Q, hydrocyclone inner diameter D, hydrocyclone overflow outlet outer diameter D0, hydrocyclone overflow outlet inner diameter d0, hydrocyclone underflow outlet inner diameter d, hydrocyclone overflow pipe insertion depth h0, hydrocyclone bottom cone angle α, and hydrocyclone column section height H. C Height H of the hydrocyclone cone section Z The height h from the bottom outlet of the hydrocyclone to the apex of the cone section z Hydrocyclone target separation particle size d 50 The theoretical split ratio P of the hydrocyclone and the average tangential velocity of the fluid inside the hydrocyclone.

[0064] The feed flow rate Q, the inner diameter D of the hydrocyclone, the outer diameter D0 of the hydrocyclone overflow outlet, the inner diameter d0 of the hydrocyclone overflow outlet, the inner diameter d of the hydrocyclone bottom outlet, the insertion depth h0 of the hydrocyclone overflow pipe, the bottom cone angle α of the hydrocyclone, and the column height H of the hydrocyclone are specified. C Height H of the hydrocyclone cone section Z The height h from the bottom outlet of the hydrocyclone to the apex of the cone section z Hydrocyclone target separation particle size d 50 The theoretical split ratio P of the hydrocyclone is determined based on the actual parameters of the hydrocyclone being simulated.

[0065] The average tangential velocity of the fluid inside the hydrocyclone The determination process is as follows:

[0066] Establish a spherical coordinate system with the apex of the hydrocyclone cone as the origin. In a cylindrical coordinate system (r, θ, z) and a rectangular coordinate system (x, y, z), for any point in the coordinate system, s is the distance from that point to the origin. Let θ be the angle between the position vector of the point and the z-axis, θ be the angle between the projection of the position vector of the point on the xy plane and the x-axis, r be the distance from the point to the z-axis, x be the perpendicular distance from the point to the yz plane, y be the perpendicular distance from the point to the xz plane, and z be the perpendicular distance from the point to the xy plane.

[0067] Based on the calculation formulas (1) to (3) and the structural characteristics of the hydrocyclone, the r of the characteristic point f in the cylindrical coordinate system is obtained. f z f spherical coordinates

[0068]

[0069] z f =H Z +H C +h z -h0…………(2)

[0070]

[0071] The characteristic parameter σ is obtained according to the calculation formula (4);

[0072]

[0073] Based on formulas (5) to (7), the z-coordinates of the characteristic point c located at the cylindrical-cone interface of the hydrocyclone in cylindrical coordinates are calculated. c spherical coordinate system r in cylindrical coordinates c; where feature point c is in spherical coordinates Based on the dimensionless flow function of the hydrocyclone, the expression is obtained by graphical method and is given by formula (6).

[0074] z c =H Z +h z …………(5)

[0075]

[0076]

[0077] Based on the characteristic parameter σ and the r of the characteristic point c in cylindrical coordinates c Based on the basic parameters of the hydrocyclone, an expression for the tangential velocity of the fluid in the hydrocyclone is established, which is formula (8).

[0078] The hydrocyclone is transformed into a generalized model, and the calculation point k(r) is selected in the hydrocyclone. k , z k The average tangential velocity of the fluid inside the hydrocyclone is calculated according to formula (9). The number of calculation points n ≥ 500;

[0079]

[0080]

[0081] Preferably, the generalized parameters of the hydrocyclone include: Reynolds number R. e Froude number F r Centrifugal inertial force I g The process for determining the hydraulic residence time t is as follows:

[0082] The Reynolds number R e It is calculated according to formula (10);

[0083]

[0084] Where ρ is the liquid density and μ is the liquid dynamic viscosity;

[0085] The Froude number F r It is calculated according to formula (11);

[0086]

[0087] Where g is the acceleration due to gravity;

[0088] The centrifugal inertial force I g It is calculated according to formula (12);

[0089]

[0090] The hydraulic residence time t is calculated according to formula (13);

[0091]

[0092] Preferably, the centrifuge simulation parameters include: centrifugation speed (RPM), centrifugal force (G), centrifugation time (T), and the volume of concentrated material sampled from the bottom of the centrifuge tube (V). con The determination process is as follows:

[0093] The process for determining the centrifugal speed RPM is as follows:

[0094] The centrifugal linear velocity V is calculated according to formula (14);

[0095]

[0096] Where, r ct The centrifugal radius of the centrifuge;

[0097] The centrifugal speed RPM is calculated according to formula (15);

[0098]

[0099] Wherein, CEILING is a rounding function that rounds up the multiple, and the result is a multiple of 100;

[0100] The centrifugal force G is calculated according to formula (16);

[0101]

[0102] The centrifugation time T is calculated according to formula (17);

[0103] T = [t]…………(17)

[0104] V, the volume of concentrated material sampled from the bottom of the centrifuge tube con It is calculated according to formula (18);

[0105] V con =V T P…………(18)

[0106] Among them, V T This represents the total volume of the liquid feed.

[0107] Compared with the prior art, the present invention has the following beneficial effects:

[0108] (1) This invention provides a method for simulating hydrocyclone separation. Based on the method for determining centrifugal simulation parameters, combined with conventional centrifuges and centrifuge tubes, the separation effect of hydrocyclones can be verified under laboratory conditions without the need to establish a pilot-scale hydrocyclone test device. The verification process is simple, convenient and accurate.

[0109] (2) This invention proposes centrifugal simulation parameters and their determination method through experiments and simulations, combined with material characteristics and the features of hydrocyclones. The calculation process is simple, the method is scientific and reasonable, and it can accurately verify the actual separation effect of hydrocyclones. Attached Figure Description

[0110] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0111] Figure 1 This is a schematic diagram of the coordinate system;

[0112] Figure 2 This is a schematic diagram of the generalized model;

[0113] Figure 3 This is a flowchart of the method for separating residual sludge and inorganic sand using a simulated hydrocyclone according to the present invention;

[0114] Figure 4 The diagram is based on the graphical method. Detailed Implementation

[0115] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0116] Example 1

[0117] Taking a wastewater treatment plant in Guiyang City as an example, the plant's residual sludge production is 2400 m³. 3 / d (moisture content 99%), the inorganic content of the residual sludge is 60%, and the median particle size of the inorganic sand is d 50The particle size is 35 μm. A standard D75 hydrocyclone was planned to be used for separating inorganic sand from the residual sludge, with an expected increase of 3%–5% in the organic matter content of the residual sludge. Considering the large volume of residual sludge and the complexity and time-consuming nature of pilot-scale verification experiments, a method for simulating the separation of inorganic sand from residual sludge using a hydrocyclone, as proposed in this invention, was adopted. Based on the method for determining centrifugal simulation parameters, and combined with conventional centrifuges and centrifuge tubes, a laboratory-scale verification experiment was conducted to evaluate the actual effectiveness of the D75 standard hydrocyclone in separating and removing inorganic sand from the plant's residual sludge.

[0118] like Figure 1 This invention provides a method for simulating hydrocyclone separation, which consists of two parts: (1) a method for determining centrifugal simulation parameters; and (2) a test method for verifying the actual effect of separating residual sludge and inorganic sand in a laboratory-scale hydrocyclone by using conventional centrifuges and centrifuge tubes based on the determined centrifugal simulation parameters and by analyzing the relevant indicators of the concentrated material at the bottom of the centrifuge tube and the remaining material at the top of the centrifuge tube.

[0119] The centrifuge simulation parameters include basic parameters of the hydrocyclone, generalized parameters of the hydrocyclone, and simulation parameters of the centrifuge.

[0120] The method for determining centrifuge simulation parameters includes the following steps: 1) determining the basic parameters of the hydrocyclone; 2) determining the generalized parameters of the hydrocyclone based on the basic parameters of the hydrocyclone; 3) calculating the centrifuge simulation parameters based on the generalized parameters of the hydrocyclone.

[0121] The basic parameters of the hydrocyclone include: feed flow rate Q, hydrocyclone inner diameter D, hydrocyclone overflow outlet outer diameter D0, hydrocyclone overflow outlet inner diameter d0, hydrocyclone underflow outlet inner diameter d, hydrocyclone overflow pipe insertion depth h0, hydrocyclone bottom cone angle α, and hydrocyclone column height H. C Height H of the hydrocyclone cone section Z The height h from the bottom outlet of the hydrocyclone to the apex of the cone section z Hydrocyclone target separation particle size d 50 The theoretical split ratio P of the hydrocyclone and the average tangential velocity of the fluid inside the hydrocyclone. The method for determining it is as follows:

[0122] The feed flow rate Q, the inner diameter D of the hydrocyclone, the outer diameter D0 of the hydrocyclone overflow outlet, the inner diameter d0 of the hydrocyclone overflow outlet, the inner diameter d of the hydrocyclone bottom outlet, the insertion depth h0 of the hydrocyclone overflow pipe, the bottom cone angle α of the hydrocyclone, and the column height H of the hydrocyclone are specified. C Height H of the hydrocyclone cone section Z The height h from the bottom outlet of the hydrocyclone to the apex of the cone section zHydrocyclone target separation particle size d 50 The theoretical split ratio P of the hydrocyclone is determined based on the actual parameters of the hydrocyclone being simulated.

[0123] In this embodiment, the specific values ​​of the above parameters are shown in the table below.

[0124]

[0125] The average tangential velocity of the fluid inside the hydrocyclone The method for determining it is as follows:

[0126] ①For example Figure 1 A spherical coordinate system is established with the apex of the hydrocyclone cone as the origin. The cylindrical coordinate system (r, θ, z) and the rectangular coordinate system (x, y, z) are shown in Figure (1). For any point in the coordinate system, s is the distance from that point to the origin. Let θ be the angle between the position vector of the point and the z-axis, θ be the angle between the projection of the position vector of the point onto the xy plane and the x-axis, r be the distance from the point to the z-axis, x be the perpendicular distance from the point to the yz plane, y be the perpendicular distance from the point to the xz plane, and z be the perpendicular distance from the point to the xy plane.

[0127] ②Based on the calculation formulas (1) to (3) and the structural characteristics of the hydrocyclone, the r of the characteristic point f in the cylindrical coordinate system is obtained. f z f spherical coordinates

[0128]

[0129] z f =H z +H C +h z -h0 Equation (2)

[0130]

[0131] ③The characteristic parameter σ is obtained according to the calculation formula (4).

[0132]

[0133] In this embodiment, the specific calculated values ​​of the relevant parameters of feature point f and feature parameter σ are shown in the table below.

[0134]

[0135] ④ Based on formulas (5) to (7), the z-axis of the characteristic point c located at the cylindrical-cone interface of the hydrocyclone in cylindrical coordinates is calculated. c spherical coordinate system r in cylindrical coordinates c Among them, feature point c in spherical coordinates... The dimensionless flow function of the hydrocyclone (Formula (6)) is calculated using the graphical method.

[0136] z c =H Z +h z Equation (5)

[0137]

[0138]

[0139] In this embodiment, the specific calculation method for the parameters related to feature point c is as follows:

[0140] a. First, calculate the z-axis of feature point c in cylindrical coordinates. c =302.58mm.

[0141] b. List the dimensionless flow function of the hydrocyclone according to formula (6);

[0142]

[0143] c. Plot the dimensionless stream function as described above and obtain the result using a graphical method. The corresponding feature point c in spherical coordinates like Figure 4 .

[0144] d. Calculate the r of feature point c in cylindrical coordinates according to formula (7). c =25.50mm.

[0145] ⑤ Based on the characteristic parameter σ and the r of the characteristic point c in cylindrical coordinates c Based on the basic parameters of the hydrocyclone (feed flow rate Q, hydrocyclone inner diameter D, hydrocyclone bottom cone angle α), establish the expression for the tangential velocity of the fluid in the hydrocyclone, Equation (8).

[0146] ⑥ Convert the hydrocyclone into Figure 2 The generalized model is shown. The calculation point k(r) is selected in the hydrocyclone. k , z k ).

[0147] The average tangential velocity of the fluid inside the hydrocyclone is calculated according to equation (9). The number of calculation points n ≥ 500.

[0148]

[0149]

[0150] The generalized parameters of the hydrocyclone include the Reynolds number R. e Froude number F r Centrifugal inertial force I g The hydraulic residence time t is determined as follows:

[0151] 1) The Reynolds number R e It is calculated according to formula (10).

[0152]

[0153] Where ρ is the liquid density and μ is the liquid dynamic viscosity.

[0154] 2) The Froude number F r It is calculated according to formula (11).

[0155]

[0156] Where g is the acceleration due to gravity.

[0157] 3) The centrifugal inertial force I g It is calculated according to formula (12).

[0158]

[0159] 4) The hydraulic residence time t is calculated according to formula (13).

[0160]

[0161] In this embodiment, the generalized parameters of the hydrocyclone calculated according to the above method are shown in the table below.

[0162] Parameter name Parameter calculation value <![CDATA[Reynolds number R e > 166.22 <![CDATA[Froude number F r > 124.30 <![CDATA[Centrifugal inertial force I g (×g)]]> 62.15 Hydraulic residence time t(s) 1.82

[0163] The centrifuge simulation parameters include centrifugation speed (RPM), centrifugal force (G), centrifugation time (T), and the volume of concentrated material sampled from the bottom of the centrifuge tube (V). con The method for determining it is as follows:

[0164] 1) The centrifugal speed (RPM) is determined according to the following method:

[0165] ①The centrifugal linear velocity V is calculated according to formula (14).

[0166]

[0167] Where, r ct This is the centrifugal radius of the centrifuge.

[0168] ②The centrifugal speed RPM is calculated according to formula (15).

[0169]

[0170] Here, CEILING is a rounding function that rounds up the multiple of 10, and the result is a multiple of 10.

[0171] 2) The centrifugal force G is calculated according to formula (16).

[0172]

[0173] 3) The centrifugation time T is calculated according to formula (17).

[0174] T = [t] = 2s Equation (17)

[0175] 4) The sampling volume V of the concentrated material at the bottom of the centrifuge tube con It is calculated according to formula (18).

[0176] V con =V T P = 50 × 10% = 5 mL (Equation 18)

[0177] Among them, V T This represents the total volume of the liquid feed.

[0178] In this embodiment, the centrifuge simulation parameters calculated according to the above method are shown in the table below.

[0179]

[0180] The method for separating residual sludge and inorganic sand using a simulated hydrocyclone, provided by this invention, includes the following steps:

[0181] (1) Determine the centrifuge simulation parameters according to the method for determining centrifugation simulation parameters, including centrifugation speed RPM, centrifugation force G, centrifugation time T, and the volume of concentrated material sampled from the bottom of the centrifuge tube V. con The specific results are shown in the table below.

[0182]

[0183] (2) Collect representative residual sludge and record the total volume V. T The volume is 50 mL. The remaining sludge is then transferred to a centrifuge tube and placed into the centrifuge. The centrifuge speed and time are set to 800 r / min and 2 s respectively, according to the centrifuge simulation parameters.

[0184] (3) Start the centrifuge and remove the centrifuge tube after centrifugation is complete. First, remove the concentrated material from the bottom of the centrifuge tube, and take a sample volume V.con The volume is 5 mL, which is a representative sample of the underflow material from the hydrocyclone. Then, the remaining material in the centrifuge tube is removed by tilting, which is a representative sample of the overflow material from the hydrocyclone, with a volume of 45 mL.

[0185] (4) Analyze representative samples of the underflow material (concentrated material at the bottom of the centrifuge tube) and representative samples of the overflow material (residual material in the centrifuge tube) of the hydrocyclone according to the experimental requirements. The test indicators include organic matter content VS%, inorganic matter content TS%, sludge concentration MLSS, sludge organic matter concentration MLVSS, and sludge inorganic matter concentration MLISS to obtain the simulation results of the actual effect of the hydrocyclone in separating residual sludge and inorganic sand. The specific results are shown in the table below.

[0186]

[0187]

[0188] Analysis of the above parameters shows that using a D75 standard hydrocyclone for inorganic sand separation of the wastewater treatment plant's excess sludge is expected to increase the organic matter content of the excess sludge by 3.26%, reduce the organic matter concentration of the effluent (overflow sludge) to 8.3193 g / L, and enrich the inorganic matter in the underflow sludge, increasing the underflow sludge concentration to 11.7013 g / L and the inorganic matter content to 54.32%. This size hydrocyclone can meet the expected target of increasing the organic matter content of the excess sludge by 3% to 5%, and further scale-up experiments can be conducted.

[0189] Example 2

[0190] The present invention also provides a system for simulating the separation of residual sludge and inorganic sand in a hydrocyclone. The system for simulating the separation of residual sludge and inorganic sand in a hydrocyclone can be implemented by executing the process steps of the method for simulating the separation of residual sludge and inorganic sand in a hydrocyclone. That is, those skilled in the art can understand the method for simulating the separation of residual sludge and inorganic sand in a hydrocyclone as a preferred embodiment of the system for simulating the separation of residual sludge and inorganic sand in a hydrocyclone.

[0191] The system for simulating the separation of residual sludge and inorganic sand in a hydrocyclone according to the present invention includes: module M1: acquiring centrifugation simulation parameters; module M2: collecting representative residual sludge and recording the total volume V. T The remaining sludge is loaded into centrifuge tubes and transferred into the centrifuge. The centrifuge speed and centrifugation time are set according to the centrifugation simulation parameters. Module M3: Start the centrifuge. After centrifugation is complete, remove the centrifuge tubes. First, remove the concentrated material from the bottom of the centrifuge tubes, with a sample volume of V. conThe first sample is a representative sample of the underflow material from the hydrocyclone. The remaining material in the centrifuge tube is then removed by tilting, which is the representative sample of the overflow material from the hydrocyclone. Module M4: Analyze the representative samples of the underflow material and the overflow material from the hydrocyclone according to the experimental requirements to obtain the simulation results of the actual effect of the hydrocyclone in separating the residual sludge and inorganic sand.

[0192] The centrifugation simulation parameters include basic hydrocyclone parameters, generalized hydrocyclone parameters, and centrifuge simulation parameters. The determination process is as follows: determine the basic hydrocyclone parameters; determine the generalized hydrocyclone parameters based on the basic hydrocyclone parameters; and calculate the centrifuge simulation parameters based on the generalized hydrocyclone parameters.

[0193] The basic parameters of the hydrocyclone include: feed flow rate Q, hydrocyclone inner diameter D, hydrocyclone overflow outlet outer diameter D0, hydrocyclone overflow outlet inner diameter d0, hydrocyclone underflow outlet inner diameter d, hydrocyclone overflow pipe insertion depth h0, hydrocyclone bottom cone angle α, and hydrocyclone column height H. C Height H of the hydrocyclone cone section Z The height h from the bottom outlet of the hydrocyclone to the apex of the cone section z Hydrocyclone target separation particle size d 50 The theoretical split ratio P of the hydrocyclone and the average tangential velocity of the fluid inside the hydrocyclone.

[0194] The feed flow rate Q, the inner diameter D of the hydrocyclone, the outer diameter D0 of the hydrocyclone overflow outlet, the inner diameter d0 of the hydrocyclone overflow outlet, the inner diameter d of the hydrocyclone bottom outlet, the insertion depth h0 of the hydrocyclone overflow pipe, the bottom cone angle α of the hydrocyclone, and the column height H of the hydrocyclone are specified. C Height H of the hydrocyclone cone section Z The height h from the bottom outlet of the hydrocyclone to the apex of the cone section z Hydrocyclone target separation particle size d 50 The theoretical split ratio P of the hydrocyclone is determined based on the actual parameters of the hydrocyclone being simulated.

[0195] The average tangential velocity of the fluid inside the hydrocyclone The determination process is as follows:

[0196] Establish a spherical coordinate system with the apex of the hydrocyclone cone as the origin. In a cylindrical coordinate system (r, θ, z) and a rectangular coordinate system (x, y, z), for any point in the coordinate system, s is the distance from that point to the origin. Let θ be the angle between the position vector of the point and the z-axis, θ be the angle between the projection of the position vector of the point on the xy plane and the x-axis, r be the distance from the point to the z-axis, x be the perpendicular distance from the point to the yz plane, y be the perpendicular distance from the point to the xz plane, and z be the perpendicular distance from the point to the xy plane.

[0197] Based on the calculation formulas (1) to (3) and the structural characteristics of the hydrocyclone, the r of the characteristic point f in the cylindrical coordinate system is obtained. f z f spherical coordinates

[0198]

[0199] z f =H Z +H C +h z -h0…………(2)

[0200]

[0201] The characteristic parameter σ is obtained according to the calculation formula (4);

[0202]

[0203] Based on formulas (5) to (7), the z-coordinates of the characteristic point c located at the cylindrical-cone interface of the hydrocyclone in cylindrical coordinates are calculated. c spherical coordinate system r in cylindrical coordinates c ; where feature point c is in spherical coordinates Based on the dimensionless flow function of the hydrocyclone, the expression is obtained by graphical method and is given by formula (6).

[0204] z c =H z +h z …………(5)

[0205]

[0206]

[0207] Based on the characteristic parameter σ and the r of the characteristic point c in cylindrical coordinates c Based on the basic parameters of the hydrocyclone, an expression for the tangential velocity of the fluid in the hydrocyclone is established, which is formula (8).

[0208] The hydrocyclone is transformed into a generalized model, and the calculation point k(r) is selected in the hydrocyclone. k , z kThe average tangential velocity of the fluid inside the hydrocyclone is calculated according to formula (9). The number of calculation points n ≥ 500;

[0209]

[0210]

[0211] The generalized parameters of the hydrocyclone include: Reynolds number R. e Froude number F r Centrifugal inertial force I g The process for determining the hydraulic residence time t is as follows:

[0212] The Reynolds number R e It is calculated according to formula (10);

[0213]

[0214] Where ρ is the liquid density and μ is the liquid dynamic viscosity;

[0215] The Froude number F r It is calculated according to formula (11);

[0216]

[0217] Where g is the acceleration due to gravity;

[0218] The centrifugal inertial force I g It is calculated according to formula (12);

[0219]

[0220] The hydraulic residence time t is calculated according to formula (13);

[0221]

[0222] The centrifuge simulation parameters include: centrifugal speed (RPM), centrifugal force (G), centrifugation time (T), and the volume of concentrated material sampled from the bottom of the centrifuge tube (V). con The determination process is as follows:

[0223] The process for determining the centrifugal speed RPM is as follows:

[0224] The centrifugal linear velocity V is calculated according to formula (14);

[0225]

[0226] Where, r ct The centrifugal radius of the centrifuge;

[0227] The centrifugal speed RPM is calculated according to formula (15);

[0228]

[0229] Wherein, CEILING is a rounding function that rounds up the multiple, and the result is a multiple of 100;

[0230] The centrifugal force G is calculated according to formula (16);

[0231]

[0232] The centrifugation time T is calculated according to formula (17);

[0233] T = [t]…………(17)

[0234] V, the volume of concentrated material sampled from the bottom of the centrifuge tube con It is calculated according to formula (18);

[0235] V con =V T P…………(18)

[0236] Among them, V T This represents the total volume of the liquid feed.

[0237] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0238] Those skilled in the art will understand that, in addition to implementing the system, apparatus, and their modules provided by this invention in purely computer-readable program code, the same program can be implemented in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system, apparatus, and their modules provided by this invention can be considered a hardware component, and the modules included therein for implementing various programs can also be considered structures within the hardware component; alternatively, modules for implementing various functions can be considered both software programs implementing the method and structures within the hardware component.

[0239] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for simulating the separation of residual sludge and inorganic sand using a hydrocyclone, characterized in that, include: Step 1: Obtain centrifugation simulation parameters; Step 2: Collect representative residual sludge and record the total volume. V T The remaining sludge is loaded into centrifuge tubes and transferred into a centrifuge. The centrifuge speed and centrifugation time are set according to the centrifugation simulation parameters. Step 3: Start the centrifuge. After centrifugation is complete, remove the centrifuge tube. First, remove the concentrated material from the bottom of the centrifuge tube, taking a sample volume of V. con This is a representative sample of the underflow material from the hydrocyclone. Then, the remaining material in the centrifuge tube is removed by tilting, which is a representative sample of the overflow material from the hydrocyclone. Step 4: Analyze representative samples of the underflow material and overflow material of the hydrocyclone according to the experimental requirements to obtain the simulation results of the actual effect of the hydrocyclone in separating residual sludge and inorganic sand. The centrifugation simulation parameters include basic parameters of the hydrocyclone, generalized parameters of the hydrocyclone, and centrifuge simulation parameters. The determination process is as follows: determine the basic parameters of the hydrocyclone. Based on the basic parameters of the hydrocyclone, determine the generalized parameters of the hydrocyclone; Calculate the centrifuge simulation parameters based on the generalized parameters of the hydrocyclone; The basic parameters of the hydrocyclone include: feed flow rate Q, hydrocyclone inner diameter D, hydrocyclone overflow outlet outer diameter D0, hydrocyclone overflow outlet inner diameter d0, hydrocyclone underflow outlet inner diameter d, hydrocyclone overflow pipe insertion depth h0, and hydrocyclone bottom cone angle. α、 Hydrocyclone column height H C Height H of the hydrocyclone cone section Z The height h from the bottom outlet of the hydrocyclone to the apex of the cone section z Hydrocyclone target separation particle size d 50 The theoretical split ratio P of the hydrocyclone and the average tangential velocity of the fluid inside the hydrocyclone. ; The feed flow rate Q, the inner diameter D of the hydrocyclone, the outer diameter D0 of the hydrocyclone overflow port, the inner diameter d0 of the hydrocyclone overflow port, the inner diameter d of the hydrocyclone bottom outlet, the insertion depth h0 of the hydrocyclone overflow pipe, and the angle of the bottom cone of the hydrocyclone are specified. α、 Hydrocyclone column height H C Height H of the hydrocyclone cone section Z The height h from the bottom outlet of the hydrocyclone to the apex of the cone section z Hydrocyclone target separation particle size d 50 The theoretical split ratio P of the hydrocyclone is determined based on the actual parameters of the hydrocyclone being simulated. The average tangential velocity of the fluid inside the hydrocyclone The process of determining it is as follows: Establish a spherical coordinate system with the apex of the hydrocyclone cone as the origin. s, φ, θ ), cylindrical coordinate system ( r, θ, z ) and rectangular coordinate system ( x, y, z For any point in the coordinate system, s The distance from this point to the origin. φ Let the position vector of this point be... z The included angle of the axis, θ For the position vector of this point in x - y Projection on a plane and x The included angle of the axis, r For this point to z Distance between axes x For this point to y - z Vertical distance between planes y For this point to x - z Vertical distance between planes z For this point to x - y Perpendicular distance between planes; Based on the calculation formulas (1) to (3) and the structural characteristics of the hydrocyclone, the characteristic points are obtained. f In cylindrical coordinates r f , z f spherical coordinates φ f ; …………（1） …………（2） …………（3） The characteristic parameters are obtained according to the calculation formula (4). σ ; …………（4） Based on formulas (5) to (7), the characteristic points located at the interface between the column and cone of the hydrocyclone are calculated. c In cylindrical coordinates z c spherical coordinate system φ c cylindrical coordinate system r c Among them, feature points c In spherical coordinates φ c Based on the dimensionless flow function of the hydrocyclone, the expression is obtained by graphical method and is given by formula (6). …………（5） …………（6） …………（7） Based on feature parameters σ Feature points c In cylindrical coordinates r c Based on the basic parameters of the hydrocyclone, an expression for the tangential velocity of the fluid in the hydrocyclone is established, which is formula (8). The hydrocyclone is transformed into a generalized model, and calculation points are selected within the hydrocyclone. k ( r k ，z k The average tangential velocity of the fluid inside the hydrocyclone is calculated according to formula (9). The number of calculation points n ≥ 500; …………（8） …………（9）。 2. The method for separating residual sludge and inorganic sand using a simulated hydrocyclone according to claim 1, characterized in that, The generalized parameters of the hydrocyclone include: Reynolds number R. e Froude number F r Centrifugal inertial force I g The process for determining the hydraulic residence time t is as follows: The Reynolds number R e It is calculated according to formula (10); …………（10） in, ρ For the density of the liquid, μ The dynamic viscosity of the liquid; The Froude number F r It is calculated according to formula (11); …………（11） in, g It is the acceleration due to gravity; The centrifugal inertial force I g It is calculated according to formula (12); …………（12） The hydraulic residence time t is calculated according to formula (13); …………（13）。 3. The method for separating residual sludge and inorganic sand using a simulated hydrocyclone according to claim 2, characterized in that, The centrifuge simulation parameters include: centrifugal speed (RPM), centrifugal force (G), centrifugation time (T), and the volume of concentrated material sampled from the bottom of the centrifuge tube (V). con The determination process is as follows: The process for determining the centrifugal speed RPM is as follows: The centrifugal linear velocity V is calculated according to formula (14); …………（14） in, r ct The centrifugal radius of the centrifuge; The centrifugal speed RPM is calculated according to formula (15); …………（15） in, CEILING This is a function for rounding up multiples of 100, and the result is rounded to the nearest multiple of 100. The centrifugal force G is calculated according to formula (16); …………（16） The centrifugation time T is calculated according to formula (17); …………（17） V, the volume of concentrated material sampled from the bottom of the centrifuge tube con It is calculated according to formula (18); …………（18） in, V T This represents the total volume of the liquid feed.

4. A system for simulating the separation of inorganic sand from residual sludge using a hydrocyclone, characterized in that, include: Module M1: Acquire centrifugation simulation parameters; Module M2: Collects representative residual sludge and records the total volume. V T The remaining sludge is loaded into centrifuge tubes and transferred into a centrifuge. The centrifuge speed and centrifugation time are set according to the centrifugation simulation parameters. Module M3: Start the centrifuge. After centrifugation is complete, remove the centrifuge tubes. First, remove the concentrated material from the bottom of the centrifuge tubes. The sample volume is V. con This is a representative sample of the underflow material from the hydrocyclone. Then, the remaining material in the centrifuge tube is removed by tilting, which is a representative sample of the overflow material from the hydrocyclone. Module M4: Based on the experimental requirements, analyze representative samples of the underflow material and the overflow material of the hydrocyclone to obtain simulation results of the actual effect of the hydrocyclone in separating residual sludge and inorganic sand. The centrifugation simulation parameters include basic parameters of the hydrocyclone, generalized parameters of the hydrocyclone, and centrifuge simulation parameters. The determination process is as follows: determine the basic parameters of the hydrocyclone. Based on the basic parameters of the hydrocyclone, determine the generalized parameters of the hydrocyclone; Calculate the centrifuge simulation parameters based on the generalized parameters of the hydrocyclone; The basic parameters of the hydrocyclone include: feed flow rate Q, hydrocyclone inner diameter D, hydrocyclone overflow outlet outer diameter D0, hydrocyclone overflow outlet inner diameter d0, hydrocyclone underflow outlet inner diameter d, hydrocyclone overflow pipe insertion depth h0, and hydrocyclone bottom cone angle. α、 Hydrocyclone column height H C Height H of the hydrocyclone cone section Z The height h from the bottom outlet of the hydrocyclone to the apex of the cone section z Hydrocyclone target separation particle size d 50 The theoretical split ratio P of the hydrocyclone and the average tangential velocity of the fluid inside the hydrocyclone. ; The feed flow rate Q, the inner diameter D of the hydrocyclone, the outer diameter D0 of the hydrocyclone overflow port, the inner diameter d0 of the hydrocyclone overflow port, the inner diameter d of the hydrocyclone bottom outlet, the insertion depth h0 of the hydrocyclone overflow pipe, and the angle of the bottom cone of the hydrocyclone are specified. α、 Hydrocyclone column height H C Height H of the hydrocyclone cone section Z The height h from the bottom outlet of the hydrocyclone to the apex of the cone section z Hydrocyclone target separation particle size d 50 The theoretical split ratio P of the hydrocyclone is determined based on the actual parameters of the hydrocyclone being simulated. The average tangential velocity of the fluid inside the hydrocyclone The process of determining it is as follows: Establish a spherical coordinate system with the apex of the hydrocyclone cone as the origin. s, φ, θ ), cylindrical coordinate system ( r, θ, z ) and rectangular coordinate system ( x, y, z For any point in the coordinate system, s The distance from this point to the origin. φ Let the position vector of this point be... z The included angle of the axis, θ For the position vector of this point in x - y Projection on a plane and x The included angle of the axis, r For this point to z Distance between axes x For this point to y - z Vertical distance between planes y For this point to x - z Vertical distance between planes z For this point to x - y Perpendicular distance between planes; Based on the calculation formulas (1) to (3) and the structural characteristics of the hydrocyclone, the characteristic points are obtained. f In cylindrical coordinates r f , z f spherical coordinates φ f ; …………（1） …………（2） …………（3） The characteristic parameters are obtained according to the calculation formula (4). σ ; …………（4） Based on formulas (5) to (7), the characteristic points located at the interface between the column and cone of the hydrocyclone are calculated. c In cylindrical coordinates z c spherical coordinate system φ c cylindrical coordinate system r c Among them, feature points c In spherical coordinates φ c Based on the dimensionless flow function of the hydrocyclone, the expression is obtained by graphical method and is given by formula (6). …………（5） …………（6） …………（7） Based on feature parameters σ Feature points c In cylindrical coordinates r c Based on the basic parameters of the hydrocyclone, an expression for the tangential velocity of the fluid in the hydrocyclone is established, which is formula (8). The hydrocyclone is transformed into a generalized model, and calculation points are selected within the hydrocyclone. k ( r k ，z k The average tangential velocity of the fluid inside the hydrocyclone is calculated according to formula (9). The number of calculation points n ≥ 500; …………（8） …………（9）。 5. The system for simulating hydrocyclone separation of residual sludge and inorganic sand according to claim 4, characterized in that, The generalized parameters of the hydrocyclone include: Reynolds number R. e Froude number F r Centrifugal inertial force I g The process for determining the hydraulic residence time t is as follows: The Reynolds number R e It is calculated according to formula (10); …………（10） in, ρ For the density of the liquid, μ The dynamic viscosity of the liquid; The Froude number F r It is calculated according to formula (11); …………（11） in, g It is the acceleration due to gravity; The centrifugal inertial force I g It is calculated according to formula (12); …………（12） The hydraulic residence time t is calculated according to formula (13); …………（13）。 6. The system for simulating hydrocyclone separation of residual sludge and inorganic sand according to claim 5, characterized in that, The centrifuge simulation parameters include: centrifugal speed (RPM), centrifugal force (G), centrifugation time (T), and the volume of concentrated material sampled from the bottom of the centrifuge tube (V). con The determination process is as follows: The process for determining the centrifugal speed RPM is as follows: The centrifugal linear velocity V is calculated according to formula (14); …………（14） in, r ct The centrifugal radius of the centrifuge; The centrifugal speed RPM is calculated according to formula (15); …………（15） in, CEILING This is a function for rounding up multiples of 100, and the result is rounded to the nearest multiple of 100. The centrifugal force G is calculated according to formula (16); …………（16） The centrifugation time T is calculated according to formula (17); …………（17） V, the volume of concentrated material sampled from the bottom of the centrifuge tube con It is calculated according to formula (18); …………（18） in, V T This represents the total volume of the liquid feed.

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