Two-way real-time coal blending method based on momentum mixing and coal drop pipe optimization

Abstract

The invention belongs to the technical field of coal blending, and discloses a two-way real-time coal blending method based on momentum mixing and coal drop pipe optimization. The method comprises the following steps: S1, monitoring coal flow information of a first coal feeder and a second coal feeder in real time, and respectively calculating target momentum values P of the first coal feeder and the second coal feeder at a mixing point; s2, spectral analysis is conducted on the first coal feeder and the second coal feeder, a fluctuation feature library is established, real-time detection and active compensation are conducted on discharging fluctuation, and the compensation amount delta P is output; and S3, constructing a bidirectional regulation and control model based on a multivariable cooperative control architecture, and respectively inputting target momentum values P and compensation amounts of the two paths of coal flows as control targets. According to the invention, the inherent mechanical fluctuation of the coal feeder and the change of the material level of the coal bunker can be actively inhibited, the high precision of the final coal blending proportion and the mixing uniformity is ensured, meanwhile, efficient turbulent mixing can be realized by utilizing the kinetic energy of the coal flow, and active mixing equipment such as an external mechanical stirrer or a roller mixer is omitted.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coal blending, and particularly relates to a dual-path real-time coal blending method based on momentum mixing and coal chute optimization. BACKGROUND

[0002] Coal blending is an important technical means for optimizing the use of coal, and its core operation is to mix coal of different qualities and characteristics according to specific proportioning requirements. Different qualities of coal differ in key indicators such as calorific value, ash content, sulfur content, and volatile matter. Through scientific and reasonable proportioning, the mixed coal can achieve a balanced state in various performance indicators. The final mixed coal obtained through proportioning can accurately meet the combustion requirements of a specific boiler, ensuring stable and efficient operation of the boiler. From an economic perspective, coal blending technology can make full use of various coal resources and reduce fuel costs. In terms of environmental protection, it can reduce the emission of pollutants during combustion by reasonable allocation, achieving the dual goals of economy and environmental protection.

[0003] Existing coal blending methods mainly include yard blending and real-time (online) blending. Among them, yard blending ("end blending") uses a stacker-reclaimer to mix a large amount of coal in the coal yard, which has the disadvantages of long mixing period, large land occupation, and coal separation phenomenon, and cannot quickly respond to changes in boiler load. Real-time coal blending ("road blending") adjusts the feeding amount of different coal types through multiple coal feeders during coal conveying, and mixes in the conveying belt or a dedicated mixing machine. However, most current real-time coal blending methods only use the coal pipe as a flow guide channel, and optimize the coordinated mixing of multiple coal flows, which has mixing dead angles. At the same time, active mixing devices such as mechanical stirrers and drum mixers are usually needed during mixing, which increases energy consumption and equipment maintenance costs. SUMMARY

[0004] Therefore, the present application provides a dual-path real-time coal blending method based on momentum mixing and coal chute optimization to solve the problems in the prior art.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0006] A dual-path real-time coal blending method based on momentum mixing and coal chute optimization, the method comprising:

[0007] S1: Real-time monitoring of coal flow information of the first coal feeder and the second coal feeder, and calculating target momentum values P of the first coal feeder and the second coal feeder at the mixing point, respectively;

[0008] S2: Frequency spectrum analysis of the first coal feeder and the second coal feeder, respectively, establishment of a fluctuation feature library, real-time detection and active compensation of discharge fluctuation, output of a compensation amount ΔP, and the calculation formula of the compensation amount ΔP being as follows:

[0009]

[0010] wherein k is a gain coefficient, A is the current amplitude, ω is the angular frequency, is the phase difference;

[0011] S3: Based on the multi-variable cooperative control architecture, a two-way regulation and control model is constructed, the target momentum value P and the compensation amount of the two-way coal flow are input respectively as the control target, and the speed of the first coal feeder and the second coal feeder and the speed of the downstream belt conveyor are dynamically adjusted, so that the actual momentum value of the two-way coal flow matches the target momentum value P when entering the mixed coal falling pipe;

[0012] S4: The falling pipe adopts a double-channel asymmetric incidence design, and a flow guide unit, a mixing unit and a uniform unit are sequentially arranged at the inlet section, the middle and the bottom of the falling pipe, so that the mixed coal flow flows out of the falling pipe in a uniform state;

[0013] S5: The online coal quality analyzer at the outlet of the falling pipe feeds back the measured final coal quality data to the MPC controller.

[0014] Further, the specific steps of S1 are as follows:

[0015] S1.1: Install the volume flow sensor, the flow rate sensor and the gamma-ray density meter on the outlet pipe of the first coal feeder and the second coal feeder, above the conveying belt downstream of the coal feeder and at the inlet of the falling pipe respectively, for monitoring the volume flow of the coal flow of the first coal feeder and the second coal feeder, the instantaneous speed of the coal flow and the equivalent density of the coal flow respectively;

[0016] S1.2: Calculate the target momentum value P of the two-way coal flow when entering the mixing point, and the calculation formula is as follows:

[0017]

[0018] wherein, is the equivalent density of the coal flow, Q is the volume flow of the coal flow, is the instantaneous speed of the coal flow.

[0019] Further, S2 can perform fast Fourier transform analysis on the collected instantaneous flow signal, convert it from time domain to frequency domain, and in the frequency domain graph, identify several prominent spectral peaks, the frequency corresponding to the spectral peak is the main fluctuation frequency, which is used to establish the fluctuation feature library.

[0020] Further, when real-time detection, the phase difference between the current flow signal and the reference waveform is calculated when the detected phase difference tends to the historical resonance phase, the compensation program is started.

[0021] Furthermore, the flow guiding unit is welded inside the coal chute and consists of short-stroke spiral blades arranged in an alternating pattern, with the spiral direction matching the feed and discharge direction.

[0022] Furthermore, the mixing unit is installed in the lower part of the coal chute, which is a tapered section, and is composed of multiple sets of wave-shaped impact mixing plates. The tapered section can accelerate the coal flow by reducing the cross-sectional area, and the wave-shaped impact mixing plates are used to achieve deep mixing of the coal flow.

[0023] Furthermore, the uniform unit is designed with a gradually expanding flow stabilization mode. By expanding the flow cross section, the coal flow is slowed down. The internal damping grid can break down and dissipate large-scale vortices into fine streamlines, so that the uniformly mixed coal flow spreads out in a uniform column state.

[0024] Furthermore, the bidirectional control model is used to receive the target momentum value P from S1 and the dynamic compensation signal provided by S2, and to perform multi-dimensional parameter fusion processing on it.

[0025] Furthermore, the bidirectional control model includes a two-layer control structure consisting of an upper coordination layer and a lower execution layer;

[0026] The upper coordination layer establishes a momentum ratio rule base based on fuzzy reasoning mechanism, decomposing the total momentum demand into the baseline instructions of the dual-path coal feeder;

[0027] The lower execution layer uses an adaptive sliding mode variable structure control algorithm to analyze belt speed feedback and coal flow density fluctuation parameters in real time.

[0028] The present invention has the following advantages: Through feedforward compensation for coal feeder fluctuations in step S2 and multivariable decoupling control in step S3, the system can actively suppress disturbances such as inherent mechanical fluctuations of the coal feeder and changes in coal bunker level. This ensures that the actual momentum and flow rate of the two coal streams can be highly stable and accurately track their target setpoints, thereby guaranteeing high precision in the final coal blending ratio and mixing uniformity, and reducing the fluctuation range of the coal quality entering the furnace.

[0029] This invention also provides ideal inlet conditions for the structurally optimized coal chute in step S4 through precise momentum matching control in step S3. The guiding unit, mixing unit, and homogenizing unit inside the coal chute utilize the kinetic energy of the coal flow itself to achieve efficient turbulent mixing, eliminating the need for external mechanical agitators or drum mixers and other active mixing equipment, thereby eliminating the energy consumption of these devices and reducing the mechanical maintenance work they would require.

[0030] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0031] To more intuitively illustrate the prior art and the present invention, exemplary drawings are provided below. It should be understood that the specific shapes and structures shown in the drawings should not generally be regarded as limiting conditions for implementing the present invention; for example, those skilled in the art, based on the technical concept disclosed in the present invention and the exemplary drawings, are capable of making conventional adjustments or further optimizations to the addition / reduction / classification, specific shapes, positional relationships, connection methods, size ratios, etc. of certain units (components).

[0032] Figure 1 The flowchart illustrates a dual-path real-time coal blending method based on momentum mixing and coal drop pipe optimization, as provided in one embodiment of the present invention. Detailed Implementation

[0033] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. It should be understood that these embodiments are merely for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Technical engineers in the field can make some non-essential improvements and adjustments to the present invention based on the above-described content. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Please see Figure 1 A dual-path real-time coal blending method based on momentum mixing and coal chute optimization includes the following steps:

[0035] S1: Real-time monitoring of coal flow information from the first coal feeder (first path) and the second coal feeder (second path), and calculation of the target momentum value P of the two first coal feeders at the mixing point, providing clear target parameters for subsequent coordinated control of the coal feeders, ensuring that the two coal flows can be mixed according to predetermined requirements. The coal flow information includes volumetric flow rate, coal type, and flow velocity.

[0036] The specific steps of S1 are as follows:

[0037] S1.1: Volumetric flow rate sensors, velocity sensors, and gamma-ray densitometers are installed on the outlet pipes of the first and second coal feeders, above the conveyor belt downstream of the coal feeders, and at the inlet of the coal drop pipe, respectively, to monitor the volumetric flow rate, instantaneous velocity, and equivalent density of the coal flow from the first and second coal feeders. The acquisition of this real-time data provides a reliable basis for subsequent calculations.

[0038] S1.2: Calculate the target momentum value P for each of the two coal flows as they approach the mixing point, to facilitate timely response to changes in the coal flow. The calculation formula is as follows:

[0039]

[0040] in, Let be the equivalent density of the coal flow, and Q be the volumetric flow rate of the coal flow. This represents the instantaneous velocity of the coal flow.

[0041] S2: Perform spectrum analysis on the first and second coal feeders respectively, establish a fluctuation feature library, and perform real-time detection and active compensation for discharge fluctuations, outputting a compensation amount ΔP to solve the periodic discharge fluctuations caused by the mechanical motion of the coal feeders themselves and changes in the coal bunker level, thus preventing them from violating the ideal momentum conditions set in S1. The fluctuation feature library includes the main fluctuation frequency, fluctuation amplitude, and their correlation with the coal feeder speed and coal bunker level.

[0042] First, the acquired instantaneous flow signal is analyzed using Fast Fourier Transform (FFT) to transform it from the time domain to the frequency domain. In the frequency domain plot, several prominent spectral peaks are identified. The frequencies corresponding to these peaks are the main fluctuation frequencies, which are used to establish a fluctuation feature library.

[0043] Low-frequency fluctuations (such as 0.1-2 Hz) are usually directly related to the meshing cycle of the scraper chain, the rotation of the large gear, or the periodic arching and collapse of coal in the coal bunker (which is strongly correlated with the material level).

[0044] Mid-to-high frequency fluctuations (such as 2-20 Hz) correspond to the meshing frequency of gears in the gearbox, the passing frequency of bearings, or the vibration of smaller components.

[0045] During real-time detection, the phase difference between the current flow signal and the reference waveform is calculated. When a phase difference is detected When the phase approaches the historical resonance phase (i.e., a precursor to entering the unstable region), the compensation program is initiated; based on the law of conservation of mass and the principle of conservation of energy, the compensation amount ΔP is calculated, and ΔP is converted into the feeder torque command and belt speed correction value to achieve active feedforward control.

[0046] For example: The system detects that the flow rate begins to decrease because the chain pitch reaches a specific phase (the compensation amount ΔP just becomes negative). The compensation algorithm is based on the feature library and knows that "the flow rate will decrease by X% at this time, lasting for Y milliseconds". So it immediately instructs the coal feeder speed to increase by a corresponding compensation amount ΔP.

[0047] The formula for calculating the compensation amount ΔP is as follows:

[0048]

[0049] Where k is the gain coefficient, A is the current amplitude, and ω is the angular frequency.

[0050] Phase difference The calculation formula is as follows:

[0051]

[0052] Where Δt is the time difference between the two waveforms, and T is the period.

[0053] S3: Based on the multivariable collaborative control architecture, a two-way regulation model is constructed. The target momentum value P and compensation amount of the two coal flows are input as control targets, and the speed of the first and second coal feeders and the speed of the downstream belt conveyor are dynamically adjusted so that the actual momentum value of the two coal flows matches the target momentum value P when they enter the mixed coal drop pipe.

[0054] The bidirectional control model is used to receive the target momentum value P from S1 and the dynamic compensation signal provided by S2, and to perform multi-dimensional parameter fusion processing on it.

[0055] During the fusion process, data synchronization and spatiotemporal registration are first performed. Momentum setpoints, feedforward compensation signals, and real-time process feedback signals with different transmission delays and update frequencies are timestamped within a unified control cycle. Subsequently, weighted fusion is performed based on signal confidence and dynamic characteristics. The high-frequency compensation signal of S2 is directly injected into the coal feeder control loop to cope with rapid disturbances, while the target momentum value of S1 is input into the model predictive controller along with the deviation of the process feedback for rolling optimization calculation, thereby generating a collaborative control command that can respond quickly to instantaneous fluctuations and ensure long-term stable tracking.

[0056] When constructing the bidirectional control model, a two-layer control structure is first established, consisting of an upper coordination layer and a lower execution layer. The upper layer decomposes the total momentum demand into the baseline commands of the dual coal feeders through a fuzzy inference rule base, while the lower layer adopts an adaptive sliding mode variable structure control algorithm. Subsequently, a virtual coupling term is introduced into the control loop to achieve decoupling of the two degrees of freedom between flow and velocity, and a model predictive controller containing equipment constraints is constructed. The optimal combination of coal feeder speed and belt conveyor speed is dynamically solved through a rolling optimization algorithm. Finally, a cross-feedback compensation mechanism is implanted. When the parameters of a single channel fluctuate, the control quantity of the other channel is adjusted synchronously to form a bidirectional collaborative control capability. When a disturbance is detected in a certain channel, the cross-feedback compensation mechanism is immediately activated.

[0057] The upper coordination layer establishes a momentum ratio rule base based on fuzzy reasoning mechanism, decomposing the total momentum requirement into the baseline command of the dual coal feeders; the lower execution layer uses an adaptive sliding mode variable structure control algorithm to analyze process parameters such as belt speed feedback and coal flow density fluctuation in real time, and dynamically corrects the inverter output frequency so that the actual momentum of the two coal flows always converges to near the target value.

[0058] Meanwhile, the bidirectional control model employs a decoupling control strategy to eliminate mutual interference between devices. When a deviation in flow or speed is detected on a certain line, the controller will prioritize adjusting the operating parameters of the corresponding device while also taking into account the linkage compensation on the other side, avoiding a chain reaction caused by a single adjustment.

[0059] For example, if the fluidity of coal flow A decreases due to changes in humidity, the frequency of the coal feeder on that line will be automatically increased and the belt speed will be appropriately reduced to maintain its momentum stability. At the same time, line B will make corresponding fine adjustments to balance the overall ratio and ensure that the coal flow of both lines is always in the best state.

[0060] S4: The coal chutes adopt a dual-channel asymmetric injection design, and guide units, mixing units and homogenizing units are set in sequence at the inlet section, middle and bottom of the coal chutes, so that the mixed coal flows out of the coal chutes in a uniform state, providing good conditions for subsequent combustion. The overall coal blending effect is improved through structural optimization and momentum mixing.

[0061] The guide unit is welded inside the coal chute and consists of staggered short-range spiral blades, the spiral direction of which matches the feed and discharge directions. When the two coal streams collide and rebound, the guide plate forces the material to undergo a compound motion along the spiral path: the outer ring spirals downward into the central area, while the inner ring folds upward back to the periphery. This bidirectional circulation pattern causes the coal streams to form a pair of counter-rotating spiral vortices (similar to the double helix structure of DNA).

[0062] The flow guiding unit increases the actual mixing stroke to 3 to 5 times the length of the straight pipe, extending the contact time. At the same time, the spiral centrifugal field forces particles of different densities to separate and recombine, breaking inertial stratification; and the spiral propulsion prevents material accumulation and blockage.

[0063] The mixing unit is installed in the lower, tapering section of the coal chute and consists of multiple sets of wave-shaped impact mixing plates. The tapering section accelerates the coal flow by reducing its cross-sectional area. According to Bernoulli's principle, increased velocity means further enhancement of kinetic energy, and the not-yet-completely homogeneous coal flow clumps have higher inertia. Subsequently, on the wave-shaped impact mixing plates, the coal flow is forcibly dispersed, and coal particles along different paths collide, achieving deep mixing of the coal flow.

[0064] The uniform unit features a gradually expanding, steady-flow design. By increasing the flow cross-section, the coal flow is slowed down, and some of its kinetic energy is converted into pressure energy. An internal damping grid breaks down and dissipates large-scale vortices into fine streamlines, effectively suppressing backflow and jetting. This allows the uniformly mixed coal flow to spread out in a stable and uniform column, ensuring both effective mixing and facilitating subsequent transportation and combustion.

[0065] S5: The online coal quality analyzer at the coal chute outlet feeds back the measured final coal quality data to the MPC controller. This feedback signal is used not only for conventional closed-loop control but also for parameter self-calibration of the predictive model.

[0066] For example, when it is detected that the mixing uniformity is good but the calorific value continues to deviate from the set value, the system determines that the density ρ in S1 is slowly drifting and automatically makes fine adjustments, so that the system has the self-learning ability to adapt to changes in coal type and equipment aging.

[0067] In the aforementioned dual-path real-time coal blending method based on momentum mixing and coal chute optimization, the system can actively suppress disturbances such as inherent mechanical fluctuations of the coal feeder and changes in coal bunker level through feedforward compensation for feeder fluctuations in step S2 and multivariable decoupling control in step S3. This ensures that the actual momentum and flow rate of the two coal streams can track their target setpoints with high stability and accuracy, thereby guaranteeing high precision in the final coal blending ratio and mixing uniformity, and reducing the fluctuation range of the coal quality entering the furnace.

[0068] Simultaneously, through precise momentum matching control in step S3, ideal inlet conditions are provided for the structurally optimized coal chute in step S4. The guiding unit, mixing unit, and homogenizing unit inside the coal chute utilize the kinetic energy of the coal flow itself to achieve efficient turbulent mixing, completely eliminating the need for external mechanical agitators or drum mixers and other active mixing equipment. This eliminates the energy consumption of such equipment and reduces the mechanical maintenance work associated with them.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A two-path real-time coal blending method based on momentum mixing and coal chute optimization, characterized in that, The method comprises: S1: real-time monitoring of coal flow information of the first coal feeder and the second coal feeder, and calculating target momentum values P of the first coal feeder and the second coal feeder at the mixing point respectively; S2: performing spectrum analysis on the first coal feeder and the second coal feeder respectively, establishing a fluctuation characteristic library, and performing real-time detection and active compensation on the discharge fluctuation, and outputting a compensation amount ΔP, the calculation formula of the compensation amount ΔP being as follows: where k is a gain coefficient, A is the current amplitude, ω is the angular frequency, is the phase difference; S3: constructing a bidirectional regulation and control model based on a multivariate collaborative control framework, inputting the target momentum values P of the two coal flows and the compensation amount as control targets, and dynamically adjusting the rotating speeds of the first coal feeder and the second coal feeder and the speed of the downstream belt conveyor, so that the actual momentum values of the two coal flows match the target momentum values P when entering the mixed coal falling pipe; S4: the falling pipe adopts a double-flow non-symmetrical incidence design, and a flow guide unit, a mixing unit and a uniform unit are sequentially arranged at the inlet section, the middle section and the bottom section of the falling pipe, so that the mixed coal flow flows out of the falling pipe in a uniform state; S5: an online coal quality analyzer at the outlet of the falling pipe feeds back the measured final coal quality data to the MPC controller.

2. The dual path real time coal blending method based on momentum mixing and coal drop pipe optimization according to claim 1, characterized in that, The specific steps of S1 are as follows: S1.1: installing a volume flow sensor, a flow rate sensor and a gamma-ray densimeter on the outlet pipeline of the first coal feeder and the second coal feeder, above the conveying belt downstream of the coal feeders and at the inlet of the falling pipe respectively, for monitoring the volume flow of the coal flow of the first coal feeder and the second coal feeder, the instantaneous speed of the coal flow and the equivalent density of the coal flow respectively; S1.2: calculating the target momentum values P of the two coal flows when entering the mixing point, the calculation formula being as follows: wherein, is the equivalent density of the coal flow, Q is the volumetric flow rate of the coal flow, is the instantaneous velocity of the coal flow.

3. A dual path real time coal blending method based on momentum mixing and coal drop pipe optimization according to claim 1, characterized in that, S2 can perform fast Fourier transform analysis on the collected instantaneous flow signal, convert it from the time domain to the frequency domain, and identify several prominent spectral peaks in the frequency domain graph, the frequency corresponding to the spectral peak being the main fluctuation frequency, which is used to establish the fluctuation characteristic library.

4. The dual path real time coal blending method based on momentum mixing and coal drop pipe optimization according to claim 1, characterized in that, The real-time detection calculates a phase difference between the current flow signal and the reference waveform When the phase difference is detected The compensation procedure is initiated when the historical resonance phase is approached.

5. A dual path real time coal blending method based on momentum mixing and coal drop pipe optimization as claimed in claim 1 wherein, The flow guide unit is welded inside the falling pipe and is a short-range helical blade arranged in a staggered manner, the helical direction of which matches the inlet and outlet directions.

6. A dual path real time coal blending method based on momentum mixing and coal drop pipe optimization as claimed in claim 1 wherein, The mixing unit is installed in the tapered pipe section at the lower part of the falling pipe and is composed of multiple groups of wave-shaped impact mixing plates, the tapered pipe section can accelerate the coal flow by reducing the cross-sectional area, and the wave-shaped impact mixing plates are used to realize deep mixing of the coal flow.

7. The dual path real time coal blending method based on momentum mixing and coal drop pipe optimization according to claim 1, characterized in that, The uniform unit is arranged in a gradually expanding steady flow manner, the coal flow is slowed down by expanding the flow passage cross section, and a damping grid is arranged inside to break and dissipate large-scale vortices into fine flow lines, so that the mixed uniform coal flow spreads out in the form of a uniform material column.

8. A dual path real time coal blending method based on momentum mixing and coal drop pipe optimization as claimed in claim 1 wherein, The bidirectional regulation and control model is used to receive the target momentum values P from S1 and the dynamic compensation signal provided by S2, and perform multidimensional parameter fusion processing thereon.

9. A dual path real time coal blending method based on momentum mixing and coal drop pipe optimization as claimed in claim 1 wherein, The bidirectional regulation and control model comprises a double-layer control structure of an upper coordination layer and a lower execution layer; The upper coordination layer establishes a momentum ratio rule library based on a fuzzy reasoning mechanism, and decomposes the total momentum demand into reference instructions of the double-path coal feeders; The lower execution layer uses a self-adaptive sliding mode variable structure control algorithm to analyze the belt speed feedback and the coal flow density fluctuation parameters in real time.

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