CN115062457A

CN115062457A - Dynamic monitoring and optimizing method for full-pipe-section operation parameters of dredger conveying system based on mechanism

Info

Publication number: CN115062457A
Application number: CN202210589265.4A
Authority: CN
Inventors: 王费新; 周忠玮; 尹纪富; 洪国军; 邢津; 程书凤; 鲁嘉俊; 冒小丹; 张忱; 舒敏骅; 刘功勋; 周振燕
Original assignee: CCCC National Engineering Research Center of Dredging Technology and Equipment Co Ltd
Current assignee: CCCC National Engineering Research Center of Dredging Technology and Equipment Co Ltd
Priority date: 2022-05-27
Filing date: 2022-05-27
Publication date: 2022-09-16
Anticipated expiration: 2042-05-27
Also published as: CN115062457B

Abstract

The invention relates to a mechanism-based dynamic monitoring and optimizing method for full-pipe section operation parameters of a dredger conveying system, belongs to the field of hydraulic conveying, is applied to dredging engineering, and relates to the following steps: s1, measuring main parameters of the conveying system, and obtaining full pipeline conveying parameters by a mathematical deduction method; s2, selecting a critical flow velocity calculation formula for determining a reasonable value range of a practical flow velocity interval; s3, calculating the lowest limit of the flow rate and monitoring safety; s4 practical flow rate interval calculation and safety and economy monitoring; and S5 parameter dynamic optimization and quantitative regulation. By the monitoring and optimizing method, the self-regulation mechanism of the system is kept, the characteristic of self dynamic fluctuation of dredging operation is complied with, and the safety and the economy of the conveying system are effectively improved.

Description

Dynamic monitoring and optimizing method for full-pipe-section operation parameters of dredger conveying system based on mechanism

Technical Field

The invention belongs to the field of hydraulic conveying, and is applied to dredging engineering.

Background

The dredging operation process of the dredger is complex, and the operation parameters have the characteristic of unstable and strong fluctuation which is difficult to predict, so that the real-time optimization of the operation process becomes a difficult problem in the dredging world. Due to the imperfection of the related theory, the running state and the evolution trend of the excavating and conveying system of the dredger are difficult to be accurately controlled. In the case of a conveying system, the fluctuation of concentration distribution along the line due to the uncertainty of the yield of the excavating system and the uncertainty of the yield of the excavating system, and the conveying characteristic of solid-liquid two-phase flow show obvious dynamic characteristics. Especially under the coarse grain soil matter high concentration transport operating mode such as sandy soil, when carrying with critical flow rate, there is the siltation in the bottom, density ripples phenomenon can appear to it is inhomogeneous more to make density distribution along the line through dashing the silt evolution, aggravates the stifled pipe risk of pipeline. In order to ensure the safe operation of the conveying system, the working flow rate is usually set above the critical flow rate and a large margin is left for practical operation. In addition, in the aspect of monitoring the operation performance and parameters of the conveying system, currently, the lower limit value of the working flow rate is obtained through calculation on the basis of measured point data such as flow rate, concentration, vacuum and pressure discharge measured by a shipborne instrument, and the influence of the running state of the whole pipe section of the conveying system and the evolution trend of the operation parameters is not considered. In actual ship operation, the state evaluation and adjustment operation is still performed mainly by the knowledge and experience of operators at present.

The traditional mechanism-based monitoring and controlling method for the conveying system is mainly characterized in that pipeline head loss is directly calculated based on pipeline initial point measuring point concentration or whole-pipe average concentration, then a conveying working condition point is determined by finding out an intersection point of a mud pump lift-flow characteristic curve and a pipeline head loss-flow curve, and the working condition point is taken as an optimization target of the conveying system to regulate and control operation parameters (such as literature: Wangwu, cutter suction dredger suction system matching optimization design, ship electric technology, 2017,37 (9): 59-67).

In recent years, with the rapid development of control theory and control technology, methods such as machine learning and data mining are used for predictive analysis and optimal control of the operating performance and operating parameters of a dredger, and certain results are achieved. However, when the methods are used for a dredger conveying system, only monitoring and optimization control of the operation performance of the dredge pump are mostly considered (such as documents: closed-control jump and the like, an online dynamic optimization method of a dredger slurry pipeline conveying working condition point, a mechanical engineering report, 2009,45(9):93-99,108). In practice, the economic dredge Pump control unit (EPC) developed by IHC of the Netherlands and applied to two 6500 square trailing suction Dredgers in mid-port dredging is taken as an example, and the Optimization of dredge Pump Performance is also taken as an Optimization target (see: Wang, et al, Study on Performance Analysis and Optimization development for improving System of hydralic drivers, Proceedings of the third International Ocean and Polar Engineering Conference,2020: 1351-elastic 1357). Due to neglecting the pipeline parameters, it is difficult to deal with the impact of the row spacing variation, concentration distribution and evolution thereof on the performance of the conveying system.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, and on the basis of inheriting the technical method and engineering experience of deduction of the concentration and related parameters of the whole pipeline, the method changes the thought of the traditional monitoring optimization method by applying the related theories and analytical calculation methods of the sediment motion mechanics, including the minimum resistance critical flow rate, the pipeline friction formula, the dredge pump lift formula and the like, comprehensively provides a method for dynamically monitoring the running parameters of the whole pipeline section of the dredger conveying system in real time based on the mechanism, and comprehensively obtains the upper and lower limits allowed by the working flow rate from the local and overall characteristics of the conveying system to judge the safety and the economy; and an optimized regulation and control method for respectively calculating and comparing the instantaneous dredge pump lift and the total head loss is provided by combining the running characteristics and the optimized requirements of the excavating and conveying system of the dredger in the actual engineering, and finally the quantification of the regulation and control parameters is obtained. Through the coupling of the monitoring and optimizing method, manual intervention can be carried out only when necessary, a certain self-adjusting mechanism of the system is kept, the characteristic of self dynamic fluctuation of dredging operation is complied with, and the safety and the economical efficiency of a conveying system are effectively improved.

Therefore, the technical scheme of the invention is as follows:

the dynamic monitoring and optimizing method for the operation parameters of the whole pipe section of the dredger conveying system based on the mechanism is characterized by comprising the following steps of:

s1: measuring main parameters of the conveying system, and obtaining the whole pipeline conveying parameters by a mathematical deduction method

S1-1: the following parameters of the conveying system are measured by the sensors for provision to the subsequent steps, including:

(1) engineering hydrogeological condition parameters: cutter suction dredger for digging depth H _down Tidal level H _tide And the climbing height H of the pipeline on the land _up ；

(2) Dredger ship machine performance parameters: the clear water rated lift H of the underwater pump and the cabin pump used by the ship _we Rated flow Q of clear water _we Rated speed n of underwater pump _we1 Rated rotation speed n of two pumps in the cabin _we2 Pipeline layout conditions (such as pipe length above water, immersed tube length in particular);

(3) conveying condition parameters: inside diameter D (m) of the pipe, and bulk density gamma of the slurry _m (t/m ³ ) Volume weight of transport carrier liquid gamma _w (t/m ³ ) Volume weight of solid gamma _s (t/m ³ ) Coefficient of friction μ _s Concentration C at the starting point of the pipeline, slurry flow velocity V, and mean particle diameter d of conveyed particles _s SiltParticle sinking velocity V _ss 。

S1-2: the real-time input of the mathematical deduction model measurement parameters (including the pipeline starting point concentration C and the slurry flow rate V measured by the sensors) is calculated using a known mathematical deduction model (see the literature: Zhou, et al, A dynamic the analytical model of long-distance pipeline transport based on Lagrangian method, Proceedings of the third-first International oxygen and Polar Engineering Conference, Rhodes, Greece,2021: 1276-.

The mathematical deduction model is based on the assumption that the slurry concentration does not change along with the change of the spatial position, and proposes to use a lagrangian method to deduct the concentration displacement distance and the concentration distribution in the whole pipeline, and specifically comprises the following steps: the actually measured concentration of the slurry at the suction port of the pipeline at a certain moment is c, the actually measured flow velocity v of the slurry is a function of time, and after delta t time, the slurry with the concentration of c is positioned at a position x away from the suction port:

by analogy, the measured initial point concentration in a period of time is deduced, namely the concentration on the whole pipeline in the period of time is obtainedConcentration profile。

S2: and selecting a critical flow velocity calculation formula for determining a reasonable value range of the practical flow velocity interval, and providing the reasonable value range for S3 and S4.

S2-1: in the prior art, a plurality of calculation formulas exist for the critical flow velocity, and each formula has certain applicability; according to the invention, through analysis and actual measurement data verification, the critical flow rate calculated by the existing critical flow rate calculation formula cannot be used as the lower limit flow rate value of each key monitoring point in the layout scheme of the invention. For this purpose, the lower limit flow velocity V of the key monitoring point is calculated by adopting a formula (2) reconstructed by correction _c In which the inclined pipe section is criticalA flow rate correction coefficient of k _p Through experimental verification, the nonlinear dependence of the inclination angle of the pipeline can be represented by the table 1.

V _c ＝k _p ·(14·C) ^1/3 ·g ^1/4 ·D ^1/2 ·v _ss ^1/2 ·d _s ^-1/4 (2)

TABLE 1 Critical flow Rate modification factor k for inclined tube section _p

Angle of rotation	0°	5°	10°	15°	20°	25°	30°
								k _p	1	1.05	1.1	1.2	1.25	1.3	1.35

S2-2: ideally, the system operates at the minimum critical flow rate of resistance, which is theoretically optimal for performance and energy consumption.

In actual construction, in order to prevent pipe blockage, a certain safety margin is set on the basis of critical flow velocity to serve as a practical lower limit of flow velocity; meanwhile, in order to inhibit the waste of energy consumption caused by overhigh flow velocity and overcome the defect of reducing the economical efficiency of a conveying system, the critical flow velocity is multiplied by an allowance coefficient to be used as the practical upper limit of the flow velocity.

Therefore, the invention provides a method for adopting a practical flow velocity interval as a flow velocity control threshold value, wherein the practical flow velocity interval is obtained by utilizing a critical flow velocity formula with the lowest resistance of S2-1 and engineering test data comprehensive analysis. Combining practical construction feasibility to average concentration of the conveying pipeline

Calculated critical flow rate

Multiplying by a multiple k _max And k _min Upper and lower limits V for operating flow rate control _cmax And V _cmin I.e., the practical flow rate interval shown in equation (3), to achieve relative safety and economy of the delivery system.

Practical flow velocity interval [ V ] _cmin ，V _cmax ]The calculation is based on the whole-tube average concentration, the overall macroscopic characteristics of the conveying system are reflected, the local microscopic characteristics of the conveying system are reflected different from the key monitoring points, the conveying characteristics can be better represented by adopting the idea of combining the whole-tube average concentration and the key monitoring points, and the safety and economical monitoring of the system can also be better realized.

S3: calculating the lowest limit of the flow rate and monitoring the safety

According to the characteristics of concentration distribution, the concentration of the measuring point adopted by the traditional mode is directly calculatedThe critical flow rate method, which monitors the risk of pipe blockage, has certain deviation. Therefore, the invention provides that the critical flow velocity V of a plurality of key monitoring points is taken _c1 ，V _c2 ，V _c3 … … as a total flow rate minimum lower limit V _c Method (2) of _c ＝max(V _c1 ，V _c2 ，V _c3 … …) to realize monitoring and evaluation of the risk of pipeline blockage. Namely: according to analysis and research, an arrangement scheme that a plurality of pipe parts easy to block are used as key monitoring points is determined, the lower limit flow speed parameter of the pipe is calculated according to the concentration data of each key monitoring point, and the maximum threshold value is determined according to a corresponding algorithm scheme and is used as the lower limit of the working flow speed of the operation safety of the whole pipe section.

The specific arrangement scheme and matching algorithm scheme are as follows:

s3-1: identifying key monitoring points for provision to S3-2

The key monitoring points selected in the arrangement scheme comprise:

(1) the key monitoring points A: the maximum concentration point of the whole tube.

Under the same condition, the higher the conveying concentration is, the higher the corresponding critical flow rate is, the higher the possibility of clogging is, so that it is necessary to determine the maximum concentration point of the whole pipe section as the key monitoring point (i.e. point A), however, because the conveying concentration fluctuates constantly, the concentration distribution on the pipeline is different every moment, the maximum concentration position is different at different moments, the S1 whole pipe section concentration distribution data is used for objectively determining the real position in real time, and the key monitoring point lower limit flow rate V is designed according to the real position _c And calculating the model.

(2) Key monitoring points B: the maximum value of the concentration of the immersed tube.

The whole conveying pipeline is divided into an upper water pipe, a sinking pipe and a shore pipe. The immersed tube is positioned on a near-shore seabed and has a certain inclination angle, namely a climbing section, the larger the inclination degree of the pipeline is, the higher the corresponding critical flow rate is under the same concentration condition, so that the critical flow rate is possibly higher although the maximum concentration of the immersed tube is not necessarily higher than the maximum concentration of the whole pipe section, and the clogging is possibly more easily caused; similarly, the point is not fixedAnd finally, utilizing the concentration distribution data of the S1 full pipe section to objectively determine the real position in real time and design the lower limit flow velocity V of a key monitoring point according to the real position _c And calculating the model.

(3) The key monitoring points C: is the starting point of the immersed tube.

The front section of the immersed tube is inclined downwards at a larger angle, and is called as a downcomer, so that the initial point of the immersed tube is the initial position of the climbing section of the immersed tube and the final position of the downcomer, and particle aggregation and silting are easy to occur. Although the monitoring point is a fixed position in space, in actual construction, the initial position of the immersed tube finally on the seabed cannot be accurately obtained before the immersed tube is placed, and the initial position is generally obtained in a measurement mode after the immersed tube is placed, so that the concentration of the point is difficult to measure by pre-installing a concentration meter on a pipeline, the seabed condition is complicated, and the measurement and data transmission difficulty of the concentration meter is greatly increased _c And calculating the model.

S3-2: extracting the concentration C of the key monitoring point from the known full pipeline conveying parameters of S1 according to the position information of the key monitoring point ₁ ，C ₂ ，C ₃ And a flow velocity V ₁ ，V ₂ ，V ₃ When the data is obtained, because the cross section area of the conveying pipeline is generally the same everywhere in the dredging engineering, and the flow in the pipeline is equal everywhere, the flow velocity values of different positions (including all key monitoring points) are also the same, namely the flow velocity value V measured at the starting point of the pipeline ₀ I.e. the operating flow rate V, i.e. V ═ V, to be monitored as important in the invention ₀ ＝V ₁ ＝V ₂ ＝V ₃ ；

S3-3: the transmission parameter of the point is calculated according to the pipeline inclination coefficient k _p Concentration C, pipe diameter D, particle settling velocity V _ss Particle size d _s Inputting the critical flow rate calculation formula in step S2 to calculate the real-time critical flow rate V corresponding to each monitoring point _c1 ，V _c2 ，V _c3 (corresponding to monitor point A, B, C, respectively) for provision to S3-4;

s3-4: comparing the working flow rate V in S3-2 with the critical flow rate V at each monitoring point in S3-3 _c1 ，V _c2 ，V _c3 If the working flow rate V is lower than the critical flow rate of any one of the monitoring points, identifying the safety risk that the current conveying system is likely to be blocked, and entering S3-5;

s3-5: and (4) early warning that safety risks exist, determining that the operation parameters need to be adjusted in time, and entering S5.

S4: practical flow velocity interval calculation and safety and economy monitoring

S4-1: extracting the concentration distribution data of the whole pipeline and the pipe diameter D and the particle settling velocity V required by the formula (2) from the whole pipeline conveying parameters obtained in the step S1 _ss Particle size d _s Calculating the average concentration value over the entire pipeline

These data are supplied to S4-2; extracting the measured value V of the flow velocity at the initial position of the pipeline ₀ This flow rate, referred to as the working flow rate V, is supplied to S4-4;

s4-2: the average concentration is measured

Formula V of critical flow velocity with lowest resistance _c ＝k _p ·(14·C) ^1/3 ·g ^1/4 ·D ^1/2 ·v _ss ^1/2 ·d _s ^-1/4 (2) Calculating to obtain' full-pipeline real-time critical flow velocity

"(the" full pipeline real time critical flow Rate)

"considered as a statistical average over the entire pipeline, as distinguished from the local critical flow rate at the monitoring point).

S4-3: further, according to the recommended value of the S2-2 practical flow velocity interval, specific calculation is carried outPractical flow velocity interval [ V ] _cmin ，V _cmax ]Supplied to S4-4;

s4-4: comparing the working flow rate V in S4-1 with the practical flow rate interval [ V ] in S4-3 _cmin ，V _cmax ]Judging whether the flow rate exceeds the interval;

s4-5: carrying out early warning with safety and economy and carrying out classification:

s4-5-1: if the working flow velocity V is less than the practical lower flow velocity limit V _cmin If the early warning conveying flow rate is too low and pipe blockage is caused, the operation parameters are adjusted, and S5 is entered (practical lower limit V of flow rate) _cmin Corresponding critical flow rate

Is not equal to the critical flow velocity V of the pipeline part in the step S3-3 _c1 ，V _c2 ，V _c3 And the practical lower limit V of the flow velocity cannot be determined _cmin And V _c1 ，V _c2 ，V _c3 Which is greater, for which reason the safety is monitored and the monitored operating flow rate V and the lower practical flow rate limit V are both monitored _cmin Comparison is made, i.e. the working flow rate V is less than V _c1 ，V _c2 ，V _c3 And V _cmin Any of which triggers a security pre-warning);

s4-5-2: if the working flow velocity V is higher than the practical upper limit V _cmax If the early warning is that the conveying flow rate is too high, the energy consumption of the conveying system is large and uneconomical, and the operation parameters need to be adjusted, the operation enters S5;

otherwise, the current operation parameters are unchanged, and the working condition is maintained;

s5: parameter dynamic optimization and quantitative regulation and control method

The method has the advantages that the rotational speed of the mud pump is changed, so that the pumping head of the mud pump is changed to realize the timely regulation and control of the flow speed, specifically, the traditional idea that the optimization target is determined by a method for searching a balance point of the pumping head and the head loss is broken through, and the pumping head and the total head loss of the mud pump at the current moment are calculated in real time and are used for cyclic judgment to realize the quantitative regulation and control of the rotational speed of the mud pump.

For the safety early warning conditions of the steps S3-5 and S4-5-1, the rotating speed of the mud pump needs to be increased, and for the economic early warning condition of S4-5-2, the rotating speed of the mud pump needs to be reduced, and the steps are respectively regulated and controlled:

(1) the safety early warning comprises the following steps:

s5-1-1: in order to increase the flow rate, the rotating speed of the dredge pump needs to be increased, and the preliminary planned increase value of the rotating speed of the dredge pump is set to be 1% of the total rotating speed in the technical scheme of the embodiment;

s5-2: calculating the rotation speed of the dredge pump according to plan adjustment to obtain the lift of the dredge pump, and respectively entering S5-4-1 or S5-4-2 according to the change of the lift of the dredge pump;

the above calculation process is as follows (some algorithmic literature: Zhou, et al, A dynamic diagnostic model of long-distance pipeline transport based on Lagrangian method, Proceedings of the third-first International Ocean and Polar Engineering Conference, Rhodes, Greece,2021: 1276-:

clear water rated lift H of underwater pump and cabin pump for dredger _we Rated flow Q of fresh water _we The relationship is fitted by a polynomial expression, and the following relational expressions are satisfied respectively.

Rated speed n of underwater pump _we1 245r/min, the rated speed of the pump in the two cabins is n _we2 257 r/min. Flow rate Q of slurry _w1 -dredge pump speed n _w1 The following relationship exists:

the mud pump can obtain a certain flow rate Q through the formula (4) _w1 Rotational speed n _w1 Lower corresponding rated clear water flow Q _we . Obtaining the corresponding rated clean water lift H through the relation (5) _we . Rated clean water lift H _we And instantaneous clean water lift H _w1 And satisfies the following relation:

thus, the corresponding instantaneous clear water lift H under the condition of certain slurry flow can be calculated _w1 。

According to the Stepanoff empirical formula, the head-to-fall ratio HR can be expressed as:

HR＝1-(0.8+0.6logd _m )·C _vd (7)

in the formula (d) _m The median particle diameter d is used according to the invention for the average particle diameter of the slurry particles ₅₀ Alternative, C _vd Is the slurry volume concentration.

Meanwhile, the head drop ratio HR can also be expressed as:

by integrating the formulas (4) - (8), the lift H of the mud pump under the condition of certain slurry concentration can be obtained _m 。

S5-3: parallel to S5-2, calculating the total head loss based on the whole concentration distribution at the moment, and respectively entering S5-4-1 or S5-4-2 according to the change of the total head loss;

the above calculation procedure is as follows (implemented using state-of-the-art techniques):

selecting a formula of Ferand and Jun (1994) as a basic formula, correcting the formula through measured data, and correcting the pipeline friction resistance I _m Calculating; the modified equation of auspicious is as follows:

in the formula I _m For conveying slurry friction loss (mH) ₂ O/m); alpha is a correction coefficient related to the relative viscosity coefficient of the slurry; v _ss The settling velocity of silt particles is shown;

lambda is the on-way resistance coefficient of the pipeline when clean water is conveyed; v is the conveying flow velocity (m/s); g is gravity acceleration (m/s) ² ) (ii) a D is the inner diameter (m) of the pipeline; gamma ray _m Is volume weight (t/m) of slurry ³ )；γ _w For delivering the volume weight (t/m) of the carrier liquid ³ )；γ _s Is solid volume weight (t/m) ³ )；K _m The test coefficient is determined by actually measured data, and the value is 1120; mu.s _s The coefficient of friction is generally 0.44; c _vd Is the volume concentration of solid particles in the slurry;

re is reynolds number (dimensionless number); and delta is the equivalent roughness of the tube wall.

V _c For the critical flow rate (m/s), the canonical formula (JTS 181-5-2012), which is already known in the art, was chosen, so the individual parameters are left out of the notation:

V _c ＝(90C _V ) ^1/3 ·g ^1/4 ·D ^1/2 ·ω ^1/2 ·d _m ^-1/4 (12)

due to the length L of each section of pipeline and the corresponding slurry concentration C _vd The flow velocity v is different at each moment, so the friction resistance value I of each pipeline at each moment _m All different, the corresponding head losses are different.

In the working condition used by the invention, the inner diameters of the dredger ship pipe, the water floating pipe, the underwater immersed pipe and the land shore pipe are consistent, and the length conversion coefficient of each pipe section can be obtained according to the conversion ratio and the conversion length ratio of the local resistance.

Total on-way head loss h _m Is the sum of head loss along the way of each section of pipeline:

h _m ＝∑(I _m ·L·k) (13)

in addition, the inlet head loss h _jm Outlet head loss h _jou High head loss h _H The calculation formulas are respectively as follows:

in the formula, the inlet head loss coefficient xi _in The value is 0.8, and the outlet head loss coefficient xi _out Taking the value as 1; the inlet of the pipeline is a flaring with the diameter of the cross section of 0.9m and the inlet velocity v _in Conversion is carried out through the sectional area ratio; the outlet is a necking, the diameter of the cross section is 0.45m, and the outlet velocity v _out Converted by the outlet cross-sectional area ratio. H _down ，H _tide ，H _up The cutter suction dredger digs the depth, the sea level and the climbing height of the pipeline on the land respectively. Gamma ray _m The density of the slurry mixture was calculated by concentration, and the formula is as follows.

γ _m ＝(γ _s -γ _w )·C _vd +γ _w (17)

Total head loss h of pipeline _mt As the sum of all head losses:

h _mt ＝h _jin +h _jout +h _H +h _m (18)

s5-4-1: comparing the calculated lift with the total head loss, returning to S5-1-1 if the lift is less than 105% of the total head loss, continuously increasing the rotation speed of the planned mud pump, and adding 1% of the total rotation speed on the basis of the first planned value, namely increasing the rotation speed to 2% of the total rotation speed; then, the step S5-2 is carried out for circulation;

when the lift is more than 5% of the total head loss or the rotation speed increase value of the mud pump reaches 5% of the total rotation speed, the circulation is jumped out, and the S5-5-1 is entered;

s5-5-1: and obtaining the rotating speed of the dredge pump which is actually required to be improved at the current moment.

(2) For the economic early warning:

s5-1-2: according to S4-5-2 monitoring and early warning, in order to reduce the flow rate, the rotating speed of the dredge pump needs to be reduced, and the primary planned reduction value of the rotating speed of the dredge pump is assumed to be 1% of the total rotating speed in the technical scheme of the embodiment;

s5-2: calculating the rotation speed of the dredge pump after planned adjustment to obtain the lift of the dredge pump, wherein the calculation process is the same as the safety early warning;

s5-3: calculating the total head loss based on delayed concentration distribution at the moment, wherein the calculation process is the same as the safety early warning;

s5-4-2: comparing the calculated lift with the total head loss, returning to S5-1-2 if the lift is greater than 95% of the total head loss, continuously reducing the rotation speed of the planned mud pump, and adding 1% of the total rotation speed on the basis of the first planned value, namely increasing the rotation speed to 2% of the total rotation speed; then, the step S5-2 is carried out for circulation until the lift is less than 95% of the total head loss or the rotating speed reduction value of the mud pump reaches 5% of the total rotating speed, and the circulation is skipped;

s5-5-2: and obtaining the rotating speed of the dredge pump which is actually required to be reduced at the current moment.

In order to avoid over-regulation, as a technical scheme of a preferred embodiment, the rotating speed of the dredge pump is regulated each time to be preferably not more than 5% of the rated rotating speed, because the length of a conveying pipeline is long, the change of the flow speed is not completed instantly, the flow speed is observed and maintained for a short time after regulation, if the flow speed is still too large or too small, the rotating speed is continuously regulated, and meanwhile, the rotating speed of the dredge pump cannot exceed the upper limit and the lower limit allowed by equipment.

Through the dynamic optimization and adjustment method, the allowable fluctuation range of the flow speed interval during monitoring is matched, intervention is performed only when necessary, a certain self-adjustment mechanism of the system is maintained, the self-fluctuation characteristic of the dredging engineering is complied with, and the safe, efficient and stable operation of the dredging and conveying system can be realized.

Drawings

FIG. 1 is a flow chart of a method for dynamically monitoring and optimizing the operating parameters of a full pipe section of a dredger conveying system according to the invention

The deduction result of the concentration distribution of the whole pipe section at different times in the embodiment of FIG. 2

FIG. 3 is a comparison between the lower limit flow rate and the real-time flow rate of the key monitoring point in the embodiment

FIG. 4 comparison of practical minimum flow rate to real-time flow rate for the example

FIG. 5 shows the time-dependent process of the concentration of the measured point, the maximum concentration in the pipe and the average concentration in the whole pipe section

FIG. 6 example of the time course of the concentration of the key monitoring points

FIG. 7 shows the control results of the dynamic optimization method for the operation parameters of the pipeline transportation system in the embodiment

Detailed Description

Examples

In the embodiment, a certain typical working condition of a construction site is adopted for calculation and analysis, and the concentration, flow velocity and other parameters corresponding to 5000 s-20000 s in the time period and related monitoring and optimization calculation results are given in the scheme. The present embodiment is further described below according to the technical solution of the present invention:

S1-1: measuring, by a sensor, a primary parameter of a delivery system, comprising: (1) engineering hydrogeological condition parameters: cutter suction dredger for digging depth H _down Tidal level H _tide And the climbing height H of the pipeline on the land _up (ii) a (2) Performance parameters of the ship machine: the clear water rated lift H of the underwater pump and the cabin pump used by the ship _we Rated flow Q of clear water _we Rated speed n of underwater pump _we1 Rated speed n of pumps in two cabins _we2 Pipeline layout conditions (e.g., length of pipe above water, length of immersed tube); (3) conveying condition parameters: inside diameter D (m) of the pipe, and bulk density gamma of the slurry _m (t/m ³ ) Volume weight of transport carrier liquid gamma _w (t/m ³ ) Volume weight of solid gamma _s (t/m ³ ) Coefficient of friction μ _s Concentration C at the starting point of the pipeline, slurry flow velocity V, and mean particle diameter d of conveyed particles _s Velocity of settling of silt particles V _ss 。.

S1-2: the calculation is carried out by using a mathematical deduction model (see the literature: Zhou, et al, A dynamic same model of long-distance pipeline transmission based on Lagrangian method, Proceedings of the third-first International oxygen and Polar Engineering consensus, Rhodes, Greece,2021: 1276-one 1281), and inputting necessary measurement parameters (including the pipeline starting point concentration C and the slurry flow rate V measured by the sensor).

by analogy, the measured starting point concentration in a period of time is deduced, and the concentration distribution on the whole pipeline is obtained.

S1-3: the full-pipe delivery parameters required in the present invention, i.e., the concentration and flow rate on the full pipe, were obtained and supplied to S2 and S4.

The concentration profile (obtained by mathematical extrapolation) for the conditions taken is given here, as shown in fig. 2.

S2: selecting a critical flow velocity calculation formula, and analyzing a reasonable value range of a practical flow velocity interval

S2-1: the critical flow velocity has a plurality of calculation formulas, each formula has certain applicability, and a reasonable critical flow velocity formula is selected for calculation according to the conditions of working condition soil quality and the like; in the invention, a certain project is taken as a support, and the critical flow rate obtained by calculation of the existing critical flow rate calculation formula can not be taken as the lower limit flow rate value of a key monitoring point through analysis and actual measurement data verification. Therefore, the corrected formula (2) is adopted to calculate the lower limit flow velocity V of the key monitoring point _c Wherein the critical flow rate correction coefficient k of the immersed tube climbing section _p The value is 1.05, the rest pipe sections are 1, and the calculation result is shown in figure 3. The critical flow rate value (red line) calculated by equation (2) is located substantially below the measured flow rate line (black line)Color line) to indicate that the anti-blocking pipe has certain rationality and can be used as a control parameter of the anti-blocking pipe of the conveying system.

V _c ＝k _p ·(14·C) ^1/3 ·g ^1/4 ·D ^1/2 ·v _ss ^1/2 ·d _s ^-1/4 (2)

S2-2: ideally, the system operates at the minimum critical flow rate of resistance with optimal performance and energy consumption. In actual construction, in order to prevent pipe blockage, certain safety margin is often required to be set, and the too high flow rate can cause the waste of energy consumption, and the economic efficiency of a conveying system is reduced. Therefore, the invention provides a method for adopting a practical flow velocity interval as a flow velocity control threshold value, wherein the practical flow velocity interval is obtained by utilizing a resistance minimum critical flow velocity calculation formula and engineering test data comprehensive analysis. In this embodiment, based on equation (2), the measured flow rates are compared with the product obtained by multiplying the measured flow rates by different margin coefficients, i.e., equation (3), and the result is shown in fig. 4. Obviously, in the time period of 5000 s-7500 s, the average concentration of the conveying is slightly higher, the working flow rate is basically more than 1.05 times and less than 1.25 times of the critical flow rate, and the relatively reasonable effect is achieved; in the time period of 12500 s-17500 s, the average concentration of the conveying is lower, the flow rate is obviously higher than 1.25 times of the critical flow rate, the economy is seriously reduced, and the actual required flow rate can be lower than the flow rate in the time period of 5000-7500 s due to the lower concentration; in a period of 17500 s-20000 s, the conveying concentration is obviously increased, the flow rate is greatly reduced and exceeds 1.05 times of the critical flow rate, and the system has the risk of clogging. Therefore, the control values and the measured flow rate under different margin coefficients have certain deviation, and the control values and the measured flow rate have the characteristic of reverse fluctuation, so that a certain optimization space exists. When the surplus coefficient is 1.05, the calculated control value is basically positioned below the actually measured flow rate; when the surplus coefficient is 1.25, the value of the surplus coefficient is higher than the actually measured flow rate for about half of the time period; therefore, the margin coefficient k is respectively taken in combination with practical construction feasibility _max ＝1.25、k _min 1.05 is used as the upper limit and the lower limit of the working flow rate control, and the relative safety and the economical efficiency of the conveying system are realized.

S3: theoretical calculation of minimum and minimum flow rate limit and safety monitoring

Based on the full-pipe concentration data obtained in step S1, a comparison graph of the point concentration, the pipe maximum concentration, and the full-pipe average concentration in a typical period is given, as shown in fig. 5. The concentration distribution of the whole pipe section in a typical test period is in a relatively obvious fluctuation characteristic, the concentration of a measured point, the maximum concentration in the pipe and the average concentration of the whole pipe section are greatly different in fluctuation frequency, fluctuation amplitude and the like, and obviously, the measured point concentration is used for calculating (preventing clogging) critical flow rate and practical minimum flow rate, and relatively large deviation can occur.

According to the characteristics of concentration distribution, the method for directly calculating the critical flow rate by measuring the point concentration in the traditional mode has certain deviation in monitoring the risk of pipe blockage. Therefore, the invention provides that the critical flow velocity V of a plurality of key monitoring points is taken _c1 ，V _c2 ，V _c3 … … as a total flow rate minimum lower limit V _c Method (2) of _c ＝max(V _c1 ，V _c2 ，V _c3 … …) to realize monitoring and evaluation of the risk of pipeline blockage. Namely: according to analysis and research, a plurality of parts easy to block the pipe are selected as key monitoring points, the lower limit flow speed parameter of the block-proof pipe is calculated according to the concentration data of the key monitoring points, and the maximum value of the lower limit flow speed parameter is taken as the lower limit of the working flow speed of the operation safety of the whole pipe section.

S3-1: identifying key monitoring points for provision to S3-2

The key monitoring points selected in the arrangement scheme comprise:

(1) the key monitoring points A: full tube concentration maximum point.

Under the same conditions, the higher the conveying concentration is, the higher the corresponding critical flow rate is, the higher the possibility of clogging is, so that it is necessary to determine the maximum concentration point of the whole pipeline section as the key monitoring point (namely point A), however, the concentration distribution on the pipeline is different every moment due to the fluctuation of the conveying concentration, the maximum concentration is different at different moments, and S1 is used for the whole pipelineThe section concentration distribution data is used for objectively determining the real position in real time and designing the lower limit flow velocity V of the key monitoring point according to the data _c And calculating the model.

The entire transport pipeline can be roughly divided into an upper water pipe, a sinking pipe and an onshore pipe, of which the sinking pipe is a part. Because the immersed tube is generally positioned on a near-shore seabed and has a certain inclination angle, which is called as a climbing section, according to the formula (2) described in S2-1, the larger the inclination degree of the pipeline is, the higher the corresponding critical flow rate is under the same concentration condition, so that the maximum concentration of the immersed tube is not necessarily higher than the maximum concentration on the whole pipe section, but the critical flow rate is possibly higher, and the silting can be easily caused; similarly, because the position of the position is not fixed, the position can be accurately found only on the basis of mastering the concentration distribution of the full-immersed tube section.

(3) The key monitoring points C: is the starting point of the immersed tube.

The former section of the immersed tube is inclined downwards at a larger angle, and is called as a downcomer, so that the initial point of the immersed tube is the initial position of the climbing section of the immersed tube and the final position of the downcomer, particle aggregation and clogging are easy to occur, and the immersed tube is necessary to be used as a key monitoring point. Although the monitoring point is a fixed position in space, in actual construction, the initial position of the immersed tube finally on the seabed cannot be accurately obtained before the immersed tube is placed, and the initial position is generally obtained in a measurement mode after the immersed tube is placed, so that the concentration of the point is difficult to measure by pre-installing a concentration meter on a pipeline, the seabed condition is complex, and the measurement and data transmission difficulty of the concentration meter is greatly increased.

S3-2: extracting the concentration C of the key monitoring point from the known full pipeline conveying parameters of S1 according to the position information of the identified key monitoring point ₁ ，C ₂ ，C ₃ Velocity of flow V ₁ ，V ₂ ，V ₃ Equal data, since the pipe cross-sectional area is generally the same everywhere in dredging projects, andthe flow in the pipeline is equal everywhere, so the flow velocity values at different positions (including all key monitoring points) are also the same, namely the flow velocity value V measured at the starting point of the pipeline ₀ I.e. the operating flow rate V, i.e. V ═ V, to be monitored as important in the invention ₀ ＝V ₁ ＝V ₂ ＝V ₃ ；

S3-3: the transmission parameter of the point is calculated according to the pipeline inclination coefficient k _p Concentration C, pipe diameter D, particle settling velocity V _ss Particle size d _s Substituting into the critical flow velocity calculation formula in the step S2, and calculating to obtain the real-time critical flow velocity V corresponding to each monitoring point _c1 ，V _c2 ，V _c3 (corresponding to monitor points A, B, C, respectively);

s3-4: comparing the working flow velocity V with the critical flow velocity V of each monitoring point _c1 ，V _c2 ，V _c3 If the working flow rate is lower than any critical flow rate, the situation that the current conveying system is possibly blocked is indicated;

s3-5: the early warning has safety risk, and the operation parameters need to be adjusted in time.

The invention adopts the measured data in a period of time of a certain construction project for analysis, the critical flow rate of the key monitoring point concerned in the step S2 and the comparison between the critical flow rate and the working flow rate are shown in figure 2, and the change of the concentration of the key monitoring point along with the time is shown in figure 6.

s4-2: the average concentration is measured

Equation (2) V of minimum critical flow velocity of resistance _c ＝k _p ·(14·C) ^1/3 ·g ^1/4 ·D ^1/2 ·v _ss ^1/2 ·d _s ^-1/4 Calculating to obtain' full-pipeline real-time critical flow velocity

"(the" full pipeline real time critical flow Rate)

S4-3: further, according to the recommended value of the S3-2 practical flow velocity interval, calculating a specific practical flow velocity interval [ V ] _cmin ，V _cmax ]Supplied to S4-4;

s4-4: comparing the working flow velocity V with the practical flow velocity interval [ V ] _cmin ，V _cmax ]Judging whether the flow rate exceeds the interval;

s4-5-1: if the working flow velocity V is less than the lower practical flow velocity limit V _cmin If the early warning conveying flow velocity is too low, the risk of pipe blockage exists, and the operation parameters are adjusted (practical lower limit V of the flow velocity) _cmin Corresponding critical flow rate

Is not equal to the critical flow velocity V of the pipeline part in the step S2-3 _c1 ，V _c2 ，V _c3 And the practical lower limit V of the flow velocity cannot be determined _cmin And V _c1 ，V _c2 ，V _c3 Which is greater, for this reason, the monitored working flow velocity V and the practical lower flow velocity limit V are required to be monitored for safety monitoring _cmin Comparison is made, i.e. the working flow rate V is less than V _c1 ，V _c2 ，V _c3 And V _cmin Any of which triggers a security pre-warning);

s4-5-2: if the working flow velocity V is higher than the practical upper limit V _cmax If the flow rate is too high, the energy consumption of the conveying system is high, the conveying system is not economical, and the operation parameters need to be adjusted;

otherwise, the current operation parameters are unchanged;

the method of the invention synchronously analyzes and calculates through steps S3 and S4 to jointly complete the safety and economical monitoring of the conveying system. The practical flow rate interval of interest for step S4 and its comparison to the operating flow rate is shown in fig. 4.

For the safety pre-warning of the steps S2-5 and S4-5-1, the rotational speed of the dredge pump needs to be increased, and for the economic pre-warning of S4-5-2, the rotational speed of the dredge pump needs to be decreased, which are explained in the following two cases:

(1) the safety early warning comprises the following steps:

s5-2: the mud pump lift is obtained by calculating the mud pump rotating speed regulated according to the plan, and the calculation process is as follows (partial algorithm documents: Zhou, et al, A dynamic mechanical model of long-distance segment transmission based on Lagrangian method, Proceedings of the third-first International objective and Polar Engineering Conference, Rhodes, Greece,2021: 1276-:

Rated speed n of underwater pump _we1 245r/min, the rated speed of the pump in the two cabins is n _we2 257 r/min. Flow rate Q of slurry _w1 -dredge pump speed n _w1 The following relationships exist:

the mud pump can obtain a certain flow rate Q through the formula (4) _w1 Rotational speed n _w1 Lower corresponding rated clear water flow Q _we . Obtaining the corresponding rated clean water lift H through the relation (5) _we . Rated clean water lift H _we And instantaneous clear water lift H _w1 And satisfies the following relation:

According to the Stepanoff empirical formula, the head drop ratio HR can be expressed as:

HR＝1-(0.8+0.6logd _m )·C _vd (7)

Meanwhile, the head pressure drop ratio HR can also be expressed as:

by integrating the formulas (4) to (8), the lift H of the mud pump under the condition of certain slurry concentration can be obtained _m 。

S5-3: and calculating the total head loss based on the whole-course concentration distribution at the moment, wherein the calculation process is as follows (realized by adopting the prior art in the field):

choose a lucky JungongFormula (1994) is used as a basic formula, the formula is corrected through measured data, and the pipeline friction resistance I is corrected _m Calculating; the modified equation for the auspicious sign is as follows:

V _c ＝(90C _V ) ^1/3 ·g ^1/4 ·D ^1/2 ·ω ^1/2 ·d _m ^-1/4 (12)

due to the length L of each section of pipeline and the corresponding slurry concentration C _vd The flow velocity v is different at each moment, so that each tube is at each momentRoad friction resistance value I _m All different, the corresponding head losses are different.

h _m ＝∑(I _m ·L·k) (13)

in addition, the inlet head loss h _jm Loss of outlet head h _jou High head loss h _H The calculation formulas are respectively as follows:

in the formula, the inlet head loss coefficient xi _in The value is 0.8, and the outlet head loss coefficient xi _out Taking the value as 1; the inlet of the pipeline is a flaring with the diameter of the cross section of 0.9m and the inlet velocity v _in Conversion is carried out through the sectional area ratio; the outlet is a necking, the diameter of the cross section is 0.45m, and the outlet velocity v _out Converted by the outlet cross-sectional area ratio. H _down ，H _tide ，H _up Respectively, the cutter suction dredger digs the depth, the tide level and the climbing height of the pipeline on the land. Gamma ray _m The density of the slurry mixture was converted by the concentration, and the formula is as follows.

γ _m ＝(γ _s -γ _w )·C _vd +γ _w (17)

Total head loss h of pipeline _mt As the sum of all head losses:

h _mt ＝h _jin +h _jout +h _H +h _m (18)

s5-4-1: comparing the calculated lift with the total head loss, returning to S5-1-1 if the lift is less than 105% of the total head loss, continuously increasing the rotation speed of the planned mud pump, and adding 1% of the total rotation speed on the basis of the first planned value, namely increasing the rotation speed to 2% of the total rotation speed; then, the step S5-2 is carried out for circulation until the lift is more than 5% of the total head loss or the rotation speed increase value of the dredge pump reaches 5% of the total rotation speed, and the circulation is carried out;

(2) For the economic early warning:

s5-1-2: in order to reduce the flow rate, the rotating speed of the dredge pump needs to be reduced, and the preliminary planned reduction value of the rotating speed of the dredge pump is assumed to be 1% of the total rotating speed in the technical scheme of the embodiment;

By the optimization method, trial calculation is also performed on the working conditions, and the optimization result is shown in fig. 7.

Meanwhile, the total power and the output of the mud pump before and after optimization are calculated, and the average single-side energy consumption is obtained, and the result is shown in the following table:

TABLE 1 comparison of average unilateral energy consumption

According to the analysis and calculation results, after optimization and adjustment, synchronous and in-phase change of the working flow rate and the concentration is basically realized, and all the working flow rates are higher than the lower limit flow rate of key monitoring points. The conveying flow rate and the conveying concentration are smooth to a certain degree, the variation coefficient of the flow rate is reduced to 3.98% from 5.51% in the testing period, the variation coefficient of the average concentration of the whole pipe section is reduced to 24.2% from 28.5%, and the running stability of the conveying system is improved. The unilateral energy consumption is 10.02MJ/m ³ Reduced to 7.62MJ/m ³ The energy consumption can be reduced by about 23.9%. The comparison result shows that the dynamic optimization adjustment method is matched with the allowable fluctuation range of the flow speed interval during monitoring, intervention is performed only when necessary, a certain self-adjustment mechanism of the system is kept, the self-fluctuation characteristic of the dredging engineering is complied with, and finally the safe, efficient and stable operation of the dredging conveying system can be realized.

Claims

1. The dynamic monitoring and optimizing method for the operation parameters of the whole pipe section of the dredger conveying system based on the mechanism is characterized by comprising the following steps of:

(2) Dredger ship machine performance parameters: the clear water rated lift H of the underwater pump and the cabin pump used by the ship _we Rated flow Q of clean water _we Rated speed n of underwater pump _we1 Rated speed n of pumps in two cabins _we2 The pipe layout condition;

(3) conveying condition parameters: inner diameter D of pipeline and volume weight gamma of slurry _m Volume weight of transport carrier liquid gamma _w Volume weight of solid gamma _s Coefficient of friction μ _s Concentration C at the starting point of the pipeline, slurry flow velocity V, and mean particle diameter d of conveyed particles _s Settling velocity of silt particle V _ss ；

S1-2: inputting the measurement parameters of the mathematical deduction model in real time by using a known mathematical deduction model for calculation, thereby outputting the real-time concentration distribution of the whole pipeline, and further providing two conveying parameters of the whole pipeline, namely the concentration distribution and the flow speed on the whole pipeline to S3, S4 and S5;

s2: selecting a critical flow velocity calculation formula for determining a reasonable value range of a practical flow velocity interval, and providing the reasonable value range for S3 and S4;

s2-1: constructing a new critical flow velocity formula for calculation;

constructing a new critical flow velocity formula (2) for calculating the lower limit flow velocity V of the key monitoring point _c Wherein the critical flow rate correction coefficient of the inclined pipe section is k _p The nonlinear correlation with the pipeline inclination angle is verified through experiments; s2-2: the method adopts a practical flow velocity interval as a flow velocity control threshold value, and the practical flow velocity interval is determined by using a critical flow velocity formula with the lowest resistance of S2-1 and engineering test data so as to obtain the average concentration of the conveying pipeline

Calculated critical flow rate

Multiplied by a multiple k _max And k _min Upper and lower limits V as operating flow rate control _cmax And V _cmin I.e. the practical flow rate interval shown in equation (3) to achieve transportThe relative safety and economy of the system;

practical flow velocity interval [ V ] _cmin ，V _cmax ]The calculation of (a) is based on the whole tube average concentration;

s3: calculating the lowest limit of the flow rate and monitoring the safety

Critical flow velocity V adopting multiple key monitoring points _c1 ，V _c2 ，V _c3 … … as a total flow rate minimum lower limit V _c Method (2) of _c ＝max(V _c1 ，V _c2 ，V _c3 … …) to monitor and evaluate the risk of pipeline blockage;

the specific arrangement scheme and matching algorithm scheme are as follows:

s3-1: identifying key monitoring points for provision to S3-2

The key monitoring points comprise:

(1) the key monitoring points A: maximum point of concentration of whole tube

The real position is objectively determined in real time by using the concentration distribution data of the S1 full pipe section, and the lower limit flow speed V of a key monitoring point is designed according to the real position _c Calculating a model;

(2) key monitoring points B: maximum value point of immersed tube concentration

(3) the key monitoring points C: for the starting point of immersed tube

The S1 full-pipe section concentration distribution data is used for objectively determining the real position in real time and combining the sinking pipe initial point position determined after arrangement, so as to design the lower limit flow velocity V of the key monitoring point _c Calculating a model;

s3-2: extracting the concentration C of the key monitoring point from the full pipeline conveying parameters of S1 according to the position information of the identified key monitoring point ₁ ，C ₂ ，C ₃ And a flow velocity V ₁ ，V ₂ ，V ₃ Data, the flow velocity values at different positions are the same, namely the flow velocity value V measured at the starting point of the pipeline ₀ I.e. the monitored operating flow rate V, so that V ═ V ₀ ＝V ₁ ＝V ₂ ＝V ₃ ；

S3-3: the inclination coefficient k of the pipeline of the transmission parameter of the key monitoring point _p Concentration C, pipe diameter D, particle settling velocity V _ss Particle size d _s Inputting the critical flow rate formula (2) in step S2 to calculate the real-time critical flow rate V corresponding to each monitoring point _c1 ，V _c2 ，V _c3 Respectively corresponding to the monitoring points A, B, C for providing to S3-4;

s3-5: early warning that safety risks exist, and entering S5 if the operation parameters need to be adjusted in time;

S4-1: extracting the concentration distribution data of the whole pipeline and the pipe diameter D and the particle settling velocity V required by the critical flow velocity formula (2) from the whole pipeline conveying parameters obtained in the step S1 _ss Particle size d _s Calculating the average value of the concentration of the whole pipeline

These data are supplied to S4-2; extracting the measured value V of the flow velocity at the initial position of the pipeline ₀ This flow rate, taken as the operating flow rate V, is supplied to S4-4;

s4-2: the average concentration is measured

Substituting the resistance into the critical flow velocity formula (2) V with the lowest resistance _c ＝k _p ·(14·C) ^1/3 ·g ^1/4 ·D ^1/2 ·v _ss ^1/2 ·d _s ^-1/4 Calculating to obtain' full-pipeline real-time critical flow velocity

", said" full pipeline real time critical flow rate

"is regarded as the statistical average condition of the whole pipeline, and is different from the local critical flow velocity of the monitoring point;

s4-3: further, according to the recommended value of the S2-2 practical flow velocity interval, calculating a specific practical flow velocity interval [ V ] _cmin ，V _cmax ]Supplied to S4-4;

s4-5-1: if the working flow velocity V is less than the lower practical flow velocity limit V _cmin If the early warning conveying flow rate is too low and the pipe blockage risk exists, adjusting operation parameters, and entering S5; practical lower limit of flow velocity V _cmin Corresponding critical flow rate

Is not equal to the critical flow velocity V of the pipeline part in the step S3-3 _c1 ，V _c2 ，V _c3 And the practical lower limit V of the flow velocity cannot be determined _cmin And V _c1 ，V _c2 ，V _c3 Which is greater, for which reason the safety is monitored and the monitored operating flow rate V and the lower practical flow rate limit V are both monitored _cmin Comparison is made, i.e. the working flow rate V is less than V _c1 ，V _c2 ，V _c3 And V _cmin Any one of them triggers safety pre-warning;

s4-5-2: if the working flow velocity V is higher than the practical upper limit V _cmax If the early warning is over high in conveying flow rate, the conveying system is high in energy consumption and uneconomical, and operation parameters need to be adjustedThen proceed to S5;

For the safety early warning conditions of the steps S3-5 and S4-5-1, the rotating speed of the dredge pump needs to be increased, and for the economic early warning condition of S4-5-2, the rotating speed of the dredge pump needs to be reduced, and the steps are respectively regulated and controlled:

(1) the safety early warning comprises the following steps:

s5-1-1: setting a preliminary planned increase value of the rotation speed of the dredge pump as a percentage of the total rotation speed;

s5-2: calculating the rotation speed of the dredge pump regulated according to a plan to obtain the lift of the dredge pump, and respectively entering S5-4-1 or S5-4-2 according to the change of the lift of the dredge pump;

the above calculation process is as follows:

clear water rated lift H of underwater pump and cabin pump for dredger _we Rated flow Q of fresh water _we The relation is fitted by a polynomial and respectively satisfies the following relations:

rated speed n of underwater pump _we1 245r/min, the rated rotation speed of the pump in the two cabins is n _we2 257 r/min; flow rate Q of slurry _w1 -dredge pump speed n _w1 The following relationships exist:

the mud pump can obtain a certain flow rate Q through the formula (4) _w1 Rotational speed n _w1 Lower corresponding rated clear water flow Q _we (ii) a Obtaining the corresponding rated clean water lift H through the relation (5) _we (ii) a Rated clean water lift H _we And instantaneous clear water lift H _w1 And satisfies the following relation:

thus, the corresponding instantaneous clear water lift H under the condition of certain slurry flow is calculated _w1 ；

According to the Stepanoff empirical formula, the head drop ratio HR is expressed as:

HR＝1-(0.8+0.6logd _m )·C _vd (7)

in the formula (d) _m The average particle diameter of the slurry particles is defined as the median particle diameter d ₅₀ Alternative, C _vd Is the volume concentration of the slurry;

meanwhile, the head drop ratio HR is also expressed as:

by integrating the formulas (4) - (8), the lift H of the mud pump under the condition of certain slurry concentration can be obtained _m ；

S5-3: parallel to S5-2, calculating the total head loss based on the whole concentration distribution at the moment, and entering S5-4-1 or S5-4-2 according to the change of the total head loss;

the above calculation process is as follows:

selecting a equation of Fer and auspicious as a basic equation, correcting the equation through actually measured data, and rubbing the pipeline to be blocked I _m Calculating; the modified equation of auspicious is as follows:

in the formula I _m In order to convey the slurry and rub and hinder the loss; alpha is a correction coefficient related to the relative viscosity coefficient of the slurry; v _ss The settling velocity of silt particles is shown;

lambda is the on-way resistance coefficient of the pipeline when clean water is conveyed; v is the conveying flow rate; g is the acceleration of gravity; d is the inner diameter of the pipeline; gamma ray _m Is the volume weight of the slurry; gamma ray _w Volume weight for transport of carrier liquid; gamma ray _s Is the volume weight of the solid; k is _m The test coefficient is determined by actual measurement data and the value is 1120; mu.s _s The coefficient of friction is generally 0.44; c _vd Is the volume concentration of solid particles in the slurry;

re is Reynolds number; delta is the equivalent roughness of the tube wall;

V _c critical flow rate:

V _c ＝(90C _V ) ^1/3 ·g ^1/4 ·D ^1/2 ·ω ^1/2 ·d _m ^-1/4 (12)

h _m ＝∑(I _m ·L·k) (13)

in the formula, the inlet head loss coefficient xi _in The value is 0.8, and the outlet head loss coefficient xi _out Taking the value as 1; the inlet of the pipeline is a flaring with the diameter of the cross section of 0.9m and the inlet velocity v _in Conversion is carried out through the sectional area ratio; the outlet is a necking, the diameter of the cross section is 0.45m, and the outlet velocity v _out Converting through the outlet sectional area ratio; h _down ，H _tide ，H _up Respectively digging depth, tide level and climbing height of a pipeline on the land for the cutter suction dredger; gamma ray _m The density of the slurry is converted by concentration, and the formula is as follows

γ _m ＝(γ _s -γ _w )·C _vd +γ _w (17)

Total head loss h of pipeline _mt As the sum of all head losses:

h _mt ＝h _jin +h _jout +h _H +h _m (18)

s5-4-1: comparing the calculated lift with the total head loss, returning to S5-1-1 if the lift is less than the total head loss by a certain percentage, continuously increasing the rotation speed of the planned mud pump, and adding the percentage of the total rotation speed on the basis of the first planned value; then, the step S5-2 is carried out for circulation;

when the lift is larger than the percentage of the total head loss or the rotating speed increase value of the mud pump reaches the percentage of the total rotating speed, the mud pump jumps out of circulation and enters S5-5-1;

s5-5-1: obtaining the rotating speed of the dredge pump which is actually required to be improved at the current moment;

(2) for the economic early warning:

s5-1-2: monitoring and early warning according to S4-5-2, in order to reduce the flow rate, the rotating speed of the dredge pump needs to be reduced, and the initial planned reduction value of the rotating speed of the dredge pump is set to be a percentage proportion of the total rotating speed;

s5-4-2: comparing the calculated lift with the total head loss, returning to S5-1-2 if the lift is greater than a certain percentage of the total head loss, continuously reducing the rotation speed of the planned mud pump, and adding the same percentage of the total rotation speed on the basis of the first planned value; then, the step S5-2 is carried out for circulation until the lift is smaller than the percentage of the total head loss or the rotating speed reduction value of the mud pump reaches the percentage of the total rotating speed, and the circulation is carried out;

2. The method as claimed in claim 1, wherein the critical flow rate formula (2) in S2-1, wherein the critical flow rate correction factor of the inclined tube section is k _p The nonlinear correlation with the pipeline inclination angle is verified through experiments and is represented by a table 1;

TABLE 1 Critical flow Rate modification factor k for inclined tube section _p

3. The method as set forth in claim 1, wherein the preliminarily planned increase in the rotation speed of the dredge pump is set to 1% of the total rotation speed in S5-1-1 and S5-1-2.

4. The method as claimed in claim 1, wherein, in S5-4-1, the following are specifically: comparing the calculated lift with the total head loss, returning to S5-1-1 if the lift is less than 105% of the total head loss, continuously increasing the rotation speed of the planned mud pump, and adding 1% of the total rotation speed on the basis of the first planned value, namely increasing the rotation speed to 2% of the total rotation speed; then, the step S5-2 is carried out for circulation;

and (4) jumping out of circulation and entering S5-5-1 until the lift is more than 5% of the total head loss or the rotation speed increase value of the mud pump reaches 5% of the total rotation speed.

5. The method as claimed in claim 1, wherein, in S5-4-2, specifically: comparing the calculated lift with the total head loss, returning to S5-1-2 if the lift is greater than 95% of the total head loss, continuously reducing the rotation speed of the planned mud pump, and adding 1% of the total rotation speed on the basis of the first planned value, namely increasing the rotation speed to 2% of the total rotation speed; and then, the step S5-2 is carried out for circulation until the lift is less than 95% of the total head loss or the rotational speed reduction value of the mud pump reaches 5% of the total rotational speed, and the circulation is skipped.

6. The method as claimed in claim 1, wherein in S5-5-2, the rotation speed of the dredge pump is adjusted to not exceed 5% of the rated rotation speed each time, the adjustment is observed and maintained for a short period of time, and if the flow rate is still too large or too small, the rotation speed is continuously adjusted while the rotation speed of the dredge pump does not exceed the allowable upper and lower limits of the equipment.