Pulverized coal forming system, mold and production process thereof

Abstract

The invention provides a pulverized coal forming system, a mold and a production technology thereof, and relates to the field of pulverized coal processing technologies, the pulverized coal forming system comprises: a raw material pretreatment subsystem, which is provided with a three-stage crushing device, a microwave-hot air coupling drying tower and a binder dynamic proportioning unit; the gradient compression molding subsystem comprises a three-stage hydraulic driving mechanism, a multi-temperature-zone composite mold and a vibration auxiliary demolding device; the intelligent control subsystem integrates a process parameter self-optimization module, an equipment state monitoring unit and a human-computer interaction interface; and the waste heat recovery subsystem comprises a flue gas heat exchanger, a phase change heat storage tank and a heat energy redistribution pipe network. According to the system and the process, through the synergistic effect of three-stage gradient pressing (pre-pressing, main pressing and pressure maintaining) and a multi-temperature-zone mold, the density deviation of a briquette coal core part is reduced, the heat stability is improved, and the surface breakage rate is reduced; energy consumption can be reduced, and the preheating efficiency is improved by matching with a mold made of composite materials.

Description

Technical Field

[0001] The present invention relates to the field of pulverized coal processing technology, in particular to a pulverized coal molding system, a mold and a production process thereof. Background Art

[0002] Pulverized coal briquetting technology is a key component of clean and efficient coal utilization. It processes pulverized coal into shaped coal briquettes through physical or chemical methods and is widely used in the metallurgical, chemical, and civilian fuel sectors. With stricter environmental protection policies and rising industrial energy efficiency standards, the market is placing higher demands on the mechanical strength, thermal stability, and production energy efficiency of briquette products.

[0003] The traditional pulverized coal molding process usually adopts single-stage pressing combined with hot air drying. Although it can achieve basic molding, it has significant limitations in terms of raw material adaptability, density uniformity and energy consumption control, and it is difficult to meet the industrial production needs of high-performance coal.

[0004] However, in the actual processing process, pulverized coal molding technology still has the following certain defects. First, the single-stage pressing mode leads to high porosity and uneven density distribution in the core of the briquette, which seriously affects the mechanical properties of the product; second, the pressure fluctuates greatly during the pressure holding stage, and the invalid energy consumption accounts for as much as 25%. In addition, the mold material has low thermal conductivity and poor wear resistance, resulting in long preheating time and short service life; third, the process parameters rely on manual experience to adjust, the response is delayed, and the product qualification rate is less than 85%, making it difficult to achieve intelligent production. Summary of the Invention

[0005] The present invention aims to solve the shortcomings of the background technology, provide multi-gradient pressing with multi-temperature zone molds to synergistically improve the mechanical properties of the finished product, and combine special molds with intelligent production to improve the yield and processing efficiency.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solutions: a pulverized coal molding system, comprising the following subsystems connected in sequence: a raw material pretreatment subsystem: equipped with a three-stage crushing device, a microwave-hot air coupled drying tower and a binder dynamic proportioning unit; a gradient pressing molding subsystem: comprising a three-stage hydraulic drive mechanism, a multi-temperature zone composite mold and a vibration-assisted demolding device; an intelligent control subsystem: integrating a process parameter self-optimization module, an equipment status monitoring unit and a human-computer interaction interface; a waste heat recovery subsystem: comprising a flue gas heat exchanger, a phase change heat storage tank and a heat energy redistribution pipeline network; wherein, the working pressure of the three-stage hydraulic drive mechanism covers 0.5-100MPa, the pressure switching response time is ≤0.2 seconds, and the multi-temperature zone composite mold forms a temperature gradient of 50-250°C in the axial direction, and the gradient difference is controlled within ±5°C / 10mm.

[0007] Further, the tertiary crushing device further comprises: i. a primary jaw crusher with a discharge particle size ≤50mm, equipped with a hydraulic overload protection device; ii. a medium roller crusher with an adjustable roller spacing range of 1-10mm and a surface hardness of HRC≥60; iii. a superfine vertical impact crusher with a built-in cyclone classifier for precise control of the particle size range of 0.1-3mm; the crushing process uses power feedback control, and the motor load rate is maintained at 75-85%, with a crushing efficiency ≥8t / h.

[0008] Further, the operation method of the microwave-hot air coupled drying tower comprises: step S1: the raw material is weighed by a belt scale and then enters the drying tower, and the initial moisture content detection accuracy is ±0.3%; step S2: the microwave generator array is started, and the power density is dynamically adjusted according to the formula P=0.5Win×2.3, wherein Win is the input moisture content (%); step S3: the cyclone hot air system is started synchronously, the wind speed is 2-5m / s, and the temperature is 80-150℃, which is regulated in three stages; step S4: the moisture content is monitored in real time by a dielectric constant sensor, and the discharge valve is triggered when the set value Wt=12±0.5% is reached.

[0009] Further, the tertiary hydraulic drive mechanism comprises: (I) a pre-pressing module: a servo motor driven ball screw with a stroke accuracy of ±0.01mm and a pre-pressing pressure of 5-10MPa; (II) a main pressing module: a four-column hydraulic cylinder cooperating with an accumulator, with a maximum pressure of 80MPa and an adjustable pressure increasing rate of 0.5-5MPa / s; (III) a pressure maintaining module: a piezoelectric ceramic actuator closed-loop control with a pressure fluctuation of ≤±0.3MPa and a pressure maintaining time t=K×ln(h), wherein K=8-12 and h is the height of the briquette (mm).

[0010] Further, the structure of the multi-temperature zone composite mold comprises: an upper mold zone: an array of inlaid heating rods with a power density of 15-25W / cm² and a temperature PID control accuracy of ±2℃; a middle mold zone: a micro-channel cooling system with a water flow rate of 3-5m / s and a heat exchange efficiency ≥85%; a lower mold zone: a gradient porous structure with a porosity of 15-30% and built-in thermocouple temperature measurement point spacing ≤10mm; the mold surface is sprayed with a nano composite coating with a surface roughness Ra≤0.08μm, and the friction coefficient of the nano composite coating is μ=0.12-0.18.

[0011] Further, the operation steps of the vibration-assisted demolding device are as follows: step A1: applying ultrasonic pretreatment with a frequency of 28-35 kHz and an amplitude of 10-50 μm for 30-60 seconds before demolding; step A2: starting the multi-top rod synchronous ejection system, with a displacement error of each top rod ≤0.05 mm, and the speed being controlled in three stages: 0.1-0.3 mm / s (10% of the stroke) in the first stage, 0.5-1 mm / s (60% of the stroke) in the second stage, and 2-3 mm / s (30% of the stroke) in the third stage; and step A3: immediately performing mold cleaning after demolding, with a blowing pressure of 0.3-0.5 MPa and a cleaning cycle ≤15 seconds.

[0012] Further, the operation method of the process parameter self-optimization module comprises: (a) establishing a raw material characteristic database containing 12 indexes such as ash content, volatile content, and particle size distribution; (β) using a deep reinforcement learning algorithm to train the objective function F=0.3S+0.4D+0.3E, wherein S is the compressive strength, D is the density uniformity, and E is the energy efficiency; and (Y) real-time optimization of output parameters: a combined scheme of pressure curve, temperature gradient, and holding time, with an optimization cycle ≤5 seconds.

[0013] Further, the operation logic of the waste heat recovery subsystem is as follows: dry waste gas waste heat recovery: flue gas is cooled to below 80℃ by a heat exchanger, with a heat recovery rate ≥65%; mold cooling water circulation: hot water with an outlet temperature of 55-65℃ is stored in a phase change heat storage tank, with a heat storage density ≥200 kJ / kg; and heat energy redistribution: recovered heat is preferentially used for raw material preheating, and the second priority is for plant heating, with a comprehensive utilization rate ≥82%.

[0014] A mold material comprises, by weight percentage: a matrix: WC-10Co 60-65%; a reinforcing phase: TiCN nanoparticles (20-50 nm) 15-20%; a lubricating component: h-BN 5-8%; an interface modifier: Cr3C2 3-5%; and a sintering aid: Y2O3 1-2%; wherein the preparation method comprises: high-energy ball milling mixing (400 rpm x 10 h) → cold isostatic pressing (200 MPa) → vacuum sintering (1380℃ x 2 h) → surface nitriding treatment (520℃ x 6 h).

[0015] A kind of powder coal forming process control method, based on the system of claims 1-9, the following steps are implemented: step B1: raw material is broken to D90≤3mm, moisture content is regulated to 12±0.5%;Step B2: gradient pressing is carried out, wherein the gradient pressing stage parameters are: pre-pressing: 8MPa×30s, mold temperature increasing rate 3℃ / s, main pressure: 40→80MPa ramped voltage, slope 0.8MPa / s, pressure maintaining: 80±0.5MPa×25s, mold temperature gradient maintains 150→90℃;Step B3: post-treatment after demoulding: surface is sprayed waterproof film, thickness 50-80 μm, forced air cooling to below 60℃, cooling rate 5-8℃ / min;Step B4: qualified inspection is carried out to finished product, using oscillation crushing process mode to carry out oscillation crushing, and the quality qualified rate is detected.

[0016] The present application provides a kind of powder coal forming system, mould and its production process, with the following beneficial effects:

[0017] The present application has the advantages that, by three-stage gradient pressing (pre-pressing-main pressure-pressure maintaining) and multi-temperature zone mould synergistic effect, the density deviation of briquette core is reduced, the thermal stability is improved, and the surface damage rate is reduced, secondly, microwave-hot air coupling drying technology combined with waste heat recovery system can reduce energy consumption and improve preheating efficiency with the mould made of the material. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is the schematic diagram of the modular powder coal forming system of the present application.

[0019] Figure 2 It is the gradient pressing process parameter synergistic control flow chart of the present application.

[0020] Figure 3 It is the composite mould material gradient structure micrograph of the present application.

[0021] Figure 4 It is the briquette forming technology effect comparison analysis diagram of the present application. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be described clearly and completely in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0023] The following disclosure provides many different embodiments, or examples, for implementing different structures of the present application. For the purpose of simplifying the present application, the components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeatedly refer to numbers and / or letters in different examples, and such repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those of ordinary skill in the art can realize the application of other processes and / or the use of other materials.

[0024] The embodiment of the present application provides a pulverized coal forming system, a mold and a production process thereof. The process reduces the density deviation of the briquette core through three-stage gradient pressing (pre-pressing-main pressing-holding) and the cooperation of the multi-temperature zone mold, improves the thermal stability, and reduces the surface damage rate. In addition, the microwave-hot air coupled drying technology combined with the waste heat recovery system can reduce energy consumption and improve the preheating efficiency with the mold made of the material. The pulverized coal forming system, the mold and the production process thereof are described in detail below. It should be noted that the description order of the following embodiments is not limited as the preferred order of the embodiments.

[0025] The present application will be described in detail below in combination with the drawings and specific embodiments.

[0026] Embodiment 1

[0027] Please refer to Figures 1-4 In the present embodiment, a pulverized coal forming system is provided, which includes the following sequentially connected subsystems: a raw material pretreatment subsystem provided with a three-stage crushing device, a microwave-hot air coupled drying tower and a binder dynamic proportioning unit; a gradient pressing forming subsystem including a three-stage hydraulic drive mechanism, a multi-temperature zone composite mold and a vibration assisted demolding device; an intelligent control subsystem integrating a process parameter self-optimization module, an equipment state monitoring unit and a man-machine interaction interface; a waste heat recovery subsystem including a flue gas heat exchanger, a phase change heat storage tank and a heat energy redistribution pipe network; wherein the working pressure of the three-stage hydraulic drive mechanism covers 0.5-100 MPa, the pressure switching response time is ≤0.2 seconds, the multi-temperature zone composite mold forms a temperature gradient of 50-250℃ in the axial direction, and the gradient difference is controlled within ±5℃ / 10mm.

[0028] Further, the tertiary crushing device further comprises: i. a primary jaw crusher with a discharge particle size ≤ 50 mm, equipped with a hydraulic overload protection device; ii. a medium roller crusher with an adjustable roller spacing range of 1-10 mm and a surface hardness of HRC≥60; iii. a superfine vertical impact crusher with an internal cyclone classifier for precise control of the particle size range of 0.1-3 mm; the crushing process uses power feedback control, and the motor load rate is maintained at 75-85%, with a crushing efficiency ≥8 t / h.

[0029] Further, the operation method of the microwave-hot air coupled drying tower comprises: step S1: the raw material is weighed by a belt scale and then enters the drying tower, and the initial moisture content detection accuracy is ±0.3%; step S2: the microwave generator array is started, and the power density is dynamically adjusted according to the formula P=0.5Win×2.3, wherein Win is the input moisture content (%); step S3: the cyclone hot air system is started synchronously, the wind speed is 2-5 m / s, and the temperature is 80-150℃, which is regulated in three stages; step S4: the moisture content is monitored in real time by a dielectric constant sensor, and the discharge valve is triggered when the set value Wt=12±0.5% is reached.

[0030] Further, the tertiary hydraulic drive mechanism comprises: (I) a pre-pressing module: a servo motor driven ball screw with a stroke accuracy of ±0.01 mm and a pre-pressing pressure of 5-10 MPa; (II) a main pressing module: a four-column hydraulic cylinder cooperating with an accumulator, with a maximum pressure of 80 MPa and an adjustable pressure increasing rate of 0.5-5 MPa / s; (III) a pressure maintaining module: a piezoelectric ceramic actuator closed-loop control with a pressure fluctuation of ≤±0.3 MPa and a pressure maintaining time t=K×ln(h), wherein K=8-12 and h is the height of the briquette (mm).

[0031] Further, the structure of the multi-temperature zone composite mold comprises: an upper mold zone: an array of inlaid heating rods with a power density of 15-25 W / cm² and a temperature PID control accuracy of ±2℃; a middle mold zone: a micro-channel cooling system with a water flow rate of 3-5 m / s and a heat exchange efficiency ≥85%; a lower mold zone: a gradient porous structure with a porosity of 15-30% and built-in thermocouple temperature measurement point spacing ≤10 mm; the mold surface is sprayed with a nano composite coating with a surface roughness Ra≤0.08 μm, and the friction coefficient μ of the nano composite coating is 0.12-0.18.

[0032] Further, the operation steps of the vibration-assisted demolding device are as follows: step A1: ultrasonic pretreatment is applied for 30-60 seconds before demolding, with a frequency of 28-35 kHz and an amplitude of 10-50 microns; step A2: the multi-top rod synchronous ejection system is started, the displacement error of each top rod is less than or equal to 0.05 mm, and the speed is controlled in three stages: the first stage is 0.1-0.3 mm / s (10% of the stroke), the second stage is 0.5-1 mm / s (60% of the middle stroke), and the third stage is 2-3 mm / s (30% of the end stroke); step A3: mold cleaning is performed immediately after demolding, with a blowing pressure of 0.3-0.5 MPa, and the cleaning cycle is less than or equal to 15 seconds.

[0033] Further, the operation method of the process parameter self-optimization module includes: (a) establishing a raw material characteristic database including 12 indicators such as ash content, volatile content, and particle size distribution; (b) using a deep reinforcement learning algorithm to train the objective function F=0.3S+0.4D+0.3E, where S is the compressive strength, D is the density uniformity, and E is the energy efficiency; (Y) real-time optimization of output parameters: combination scheme of pressure curve, temperature gradient, and holding time, optimization cycle ≤5 seconds.

[0034] Further, the operation logic of the waste heat recovery subsystem is as follows: dry waste gas waste heat recovery: flue gas is cooled to below 80°C by a heat exchanger, with a heat recovery rate of ≥65%; mold cooling water circulation: hot water with an outlet temperature of 55-65°C is stored in a phase change heat storage tank, with a heat storage density of ≥200 kJ / kg; heat energy redistribution: recovered heat is preferentially used for raw material preheating, and the second priority is for plant heating, with a comprehensive utilization rate of ≥82%.

[0035] and the technical solutions cooperate to form a complete process flow:

[0036] First process: raw material preparation stage

[0037] Input: raw coal (particle size 0-50 mm, moisture content 15-25%)

[0038] Core processing:

[0039] Three-stage crushing: jaw crusher (particle size ≤50 mm) → roller crusher (particle size 1-10 mm) → vertical impact crusher (particle size 0.1-3 mm, D90 ≤3 mm).

[0040] Microwave-hot air coupled drying: microwave power density 1.2-1.8 W / cm³ + hot air temperature 110-130°C, moisture content reduced to 12±0.5%, binder dynamic addition: adjust the binder ratio (5-8%) according to the coal quality characteristics (ash content, volatile content), and the mixing uniformity is ≥95%.

[0041] Output: pretreated pulverized coal (particle size 0.1-3 mm, moisture content 12%).

[0042] Second procedure: Gradient compression molding stage

[0043] Input: Pretreated pulverized coal

[0044] Core processing:

[0045] Three-stage hydraulic compression: Pre-pressing (8 MPa x 30 s, mold preheating to 80°C) → Main pressing (ramp up to 80 MPa, rate 0.8 MPa / s) → Pressure holding (80 ± 0.3 MPa x 25 s, mold temperature gradient 150 → 90°C).

[0046] Vibration compaction assistance: Superimpose 20 kHz ultrasonic vibration (amplitude 10 μm) during pressure holding stage to eliminate internal pores.

[0047] Output: Green briquette (density 1.25-1.35 g / cm³, compressive strength ≥ 15 MPa).

[0048] Third procedure: Intelligent demolding and post-processing stage

[0049] Input: Green briquette

[0050] Core processing:

[0051] Phase difference vibration demolding: Top rod applies 30-50 μm amplitude vibration, demolding force is reduced by 40% (traditional 8-10 kN → invention only 4.8-6 kN).

[0052] Surface strengthening treatment: Spray waterproof film (silane composite coating, thickness 50-80 μm), waterproof rate increased to 98%.

[0053] Waste heat recovery: Mold cooling water (60-70°C) is used for preheating raw materials, comprehensive energy saving 35%.

[0054] Output: Finished briquette (moisture content ≤ 3%, drop strength ≥ 96%).

[0055] Fourth procedure: Quality control and recycling

[0056] Online detection: Laser scanning density distribution (deviation ≤ 1.5%), AI image recognition surface defects (detection rate ≥ 99%).

[0057] Waste material return: Unqualified products are automatically crushed and reused (return rate ≤ 2%), and the amount of binder added is dynamically adjusted.

[0058] Final product: Industrial briquette meeting GB / T 34168-2017 standard (cold compression strength ≥ 12 MPa, thermal stability ≥ 85%).

[0059] Example 2:

[0060] A pulverized coal forming process control method, based on the system of claims 1-9, implements the following steps: Step B1: crushing the raw material to D90≤3mm, and adjusting the moisture content to 12±0.5%; Step B2: performing gradient pressing, wherein the gradient pressing stage parameters are: pre-pressing: 8MPa×30s, mold temperature rise rate 3℃ / s, main pressing: 40→80MPa ramped pressure rise, slope 0.8MPa / s, pressure holding: 80±0.5MPa×25s, mold temperature gradient maintained at 150→90℃; Step B3: post-mold treatment: surface spraying of waterproof film, thickness 50-80μm, forced air cooling to below 60℃, cooling rate 5-8℃ / min; Step B4: performing qualified inspection on the finished product, using an oscillation crushing process to perform oscillation crushing, and detecting the quality pass rate.

[0061] The traditional pulverized coal pressing process has the following bottlenecks: uneven density: single-stage pressing results in a coal core porosity of up to 8%, with a density deviation exceeding 5%; energy waste: pressure fluctuation during the pressure holding stage reaches ±2MPa, with invalid energy consumption accounting for 25%; quality dependent on manual adjustment: parameter adjustment lags behind, with a product pass rate of less than 85%.

[0062] Solution: design a three-stage gradient pressing process, combined with temperature-pressure coordinated control and AI dynamic optimization, to realize intelligent production throughout the entire process.

[0063] Process flow and function analysis

[0064] Step B1: raw material pretreatment

[0065] Crushing particle size control:

[0066] Operation process: raw coal is coarsely broken by a jaw crusher to ≤50mm, finely broken by a roller crusher to 1-10mm, and finally finely crushed by a vertical impact crusher to D90≤3mm;

[0067] Technical purpose: eliminate stress concentration defects caused by large particles;

[0068] Mechanism: three-stage crushing makes the specific surface area of the raw material ≥350m² / kg, improving the uniformity of binder coating.

[0069] Moisture content regulation:

[0070] Operation process: in a microwave-hot air combined drying tower, microwave is irradiated at a power density of 1.5W / cm³, and 115℃ cyclone hot air is simultaneously introduced, and the moisture content is monitored in real time to 12±0.5%;

[0071] Technical purpose: optimize the plastic deformation ability of coal powder;

[0072] Mechanism: Microwave selectively heats water molecules, forming a water gradient from the surface to the core (10.8% on the surface and 12.5% in the core), which enhances the particle migration efficiency during the pressing stage.

[0073] Step B2: Gradient pressing

[0074] Pre-pressing stage (8 MPa x 30 s):

[0075] Operation process: The servo motor drives the ball screw at a speed of 0.5 mm / s for pre-compaction, and the mold is heated from room temperature to 80°C;

[0076] Technical purpose: Preliminary exclusion of interstitial gas between raw materials;

[0077] Mechanism: Low-pressure slow compaction stabilizes the loading rate at 85-90%, avoiding the "edge densification, center porosity" phenomenon.

[0078] Main pressing stage (40→80 MPa ramped pressure):

[0079] Operation process: The four-column hydraulic cylinder is pressurized at a rate of 0.8 MPa / s, and the mold heating is started simultaneously (upper mold 150°C, middle mold 120°C, lower mold 90°C);

[0080] Technical purpose: Promote the viscoelastic flow of coal powder;

[0081] Mechanism: Temperature gradient field reduces the yield strength of coal powder, increases the pressure transmission efficiency by 40%, and reduces the density difference between the core and the surface of the briquette from 5.7% to 1.9%.

[0082] Pressure holding stage (80±0.5 MPa x 25 s):

[0083] Operation process: Piezoelectric ceramic actuators adjust the pressure in real time to compensate for temperature gradients and maintain temperature gradients with the mold cooling system;

[0084] Technical purpose: Complete the molecular bonding between coal particles;

[0085] Mechanism: Nanoscale pressure fluctuation control (≤±0.3 MPa) suppresses the rebound effect, and the density uniformity reaches 98.5%.

[0086] Step B3: Post-processing

[0087] Vibration demolding:

[0088] Operation process: Apply 28 kHz ultrasonic vibration for 45 seconds before demolding, and control the ejection speed in three stages (0.1 mm / s→0.8 mm / s→2 mm / s);

[0089] Technical purpose: Reduce demolding resistance and protect the integrity of the briquette;

[0090] Mechanism: Ultrasonic cavitation effect weakens the coal-mold interface bonding force, reduces the demolding force from traditional 10 kN to below 6 kN, and reduces the corner damage rate of briquette from 3.2% to 0.5%.

[0091] Surface spraying:

[0092] Operation process: Apply silicone-epoxy resin composite coating with 60 kV voltage using electrostatic spraying equipment, film thickness 65±5 μm;

[0093] Technical purpose: Improve the waterproofness and mechanical strength of briquette;

[0094] Mechanism: The coating forms a dense cross-linked network, 24-hour water absorption rate ≤1.2%, and the compressive strength is additionally increased by 15%.

[0095] Step B4: Quality detection and return material

[0096] Shocking and crushing detection:

[0097] Operation process: Unqualified products are crushed by 25 Hz high-frequency vibration to D90≤1 mm, and automatically returned to the pretreatment section;

[0098] Technical purpose: Realize zero waste discharge and recycling;

[0099] Mechanism: Directional crushing avoids over-crushing, and the return coal powder does not degrade the pressing performance after mixing with new material.

[0100] Through the above process, the quality breakthrough can be achieved: the compressive strength of briquette reaches 19.8 MPa (national standard ≥12 MPa), the thermal stability is 93.2% (industry average 82.5%), and energy efficiency optimization is provided, with the coal power consumption reduced from 44.1 kW·h to 29.3 kW·h per ton.

[0101] Example 3:

[0102] A mold material, comprising by weight percentage: matrix: WC-10Co 60-65%; reinforcing phase: TiCN nanoparticles (20-50 nm) 15-20%; lubricating component: h-BN 5-8%; interface modifier: Cr3C2 3-5%; sintering aid: Y2O3 1-2%; wherein the preparation method comprises: high-energy ball milling mixing (400 rpm x 10 h) → cold isostatic pressing (200 MPa) → vacuum sintering (1380℃ x 2h) → surface nitriding treatment (520℃ x 6h).

[0103] Traditional pulverized coal forming mold faces three major defects under high temperature and high pressure working conditions:

[0104] Low thermal conductivity: the thermal conductivity of conventional cemented carbide dies is less than 30 W / m·K, which leads to slow establishment of die temperature field and preheating time exceeding 15 minutes;

[0105] Insufficient wear resistance: under the working environment of 600℃, the die surface wear rate is as high as 3.8×10⁻ 6 mm³ / N·m, and the service life is only about 2000 times of pressing;

[0106] Thermal fatigue failure: the die is prone to cracks under frequent cold and hot cycles, and the thermal shock life is less than 1500 times.

[0107] 2. Solution

[0108] Develop a WC-TiCN-Cr3C2 gradient composite material, and realize the comprehensive improvement of die performance through nanoparticle reinforcement, interface modification and surface nitriding treatment technology.

[0109] 3. Preparation process and function analysis

[0110] Step one: high-energy ball milling

[0111] Process parameters: use a planetary ball mill, ball mill for 10 hours under argon protection at a speed of 400 rpm, ball-to-material ratio of 10:1, and alternate forward and reverse rotation;

[0112] Technical purpose: uniformly disperse TiCN nanoparticles (20-50 nm) in WC-Co matrix, break the agglomeration phenomenon of traditional mechanical mixing;

[0113] Mechanism: nanoparticles are embedded in WC grain boundaries, forming a "pinning effect" to inhibit grain coarsening during sintering (grain size ≤1.2 μm).

[0114] Step two: cold isostatic pressing

[0115] Process parameters: press at a pressure of 200 MPa for 30 minutes in a rubber jacket, and the green density reaches 65% of the theoretical density;

[0116] Technical purpose: prepare high-density preforms to reduce subsequent sintering deformation;

[0117] Mechanism: uniform transmission of isostatic pressing pressure eliminates the voids between powder particles and avoids sintering cracks caused by local density differences.

[0118] Step three: vacuum sintering

[0119] Process parameters: under the condition of vacuum degree ≤5×10⁻³ Pa, first heat up to 800℃ at a rate of 10℃ / min for 1 hour to remove wax, then heat up to 1380℃ at a rate of 5℃ / min for 2 hours, while applying an axial pressure of 30 MPa;

[0120] Technical purposes: form a dense gradient structure, optimize the matching of material strength and toughness;

[0121] Mechanism of action: Cr3C2 and Y2O3 synergistic effect, Cr3C2 forms (Cr, W) C complex phase at the grain boundary, improves the interface bonding strength; Y2O3 inhibits the abnormal growth of WC grains, so that the standard deviation of grain size distribution is reduced from 0.8 μm of traditional process to 0.3 μm.

[0122] Step four: surface nitriding treatment

[0123] Process parameters: in the ion nitriding furnace at 520℃ for 6 hours, nitrogen potential KN=3.5, nitriding layer thickness 80-120 μm;

[0124] Technical purposes: enhance the wear resistance and anti-adhesion of the mold surface;

[0125] Mechanism of action: ε-Fe2-3N hard phase is formed in the nitriding layer, the surface hardness is improved to 2200HV, and at the same time, h-BN lubricating phase is precipitated at high temperature, so that the friction coefficient is reduced to below 0.15.

[0126] The mold produced by the above process can improve the thermal conductivity, the material thermal conductivity reaches 65 W / m·K, which is increased by 132% compared with the traditional YG15 alloy (28 W / m·K), the mold preheating time is shortened from 15 minutes to 6 minutes, and the mold single use life reaches 6800 times of pressing, which can effectively provide the service life of the device.

[0127] In the above embodiments, the description of each embodiment has its own emphasis, and the parts not described in detail in a certain embodiment can be referred to the related description of other embodiments.

[0128] The above provides a coal forming system, a mold and a production process thereof, and the specific examples are applied to the principle and implementation of the present application. The above embodiment is only used to help understand the technical scheme and core idea of the present application; those skilled in the art should understand that the technical scheme recorded in the above embodiments can be modified, or some technical features can be replaced; and these modifications or replacements do not make the essence of the corresponding technical scheme deviate from the scope of the technical scheme of the embodiments of the present application.

Claims

1. A pulverized coal molding system, characterized in that: It includes the following subsystems connected in sequence: Raw material pretreatment subsystem: equipped with a three-stage crushing device, a microwave-hot air coupled drying tower and a binder dynamic proportioning unit; Gradient pressing subsystem: includes a three-stage hydraulic drive mechanism, a multi-temperature zone composite mold, and a vibration-assisted demoulding device; Intelligent control subsystem: integrates process parameter self-optimization module, equipment status monitoring unit and human-computer interaction interface; Waste heat recovery subsystem: including flue gas heat exchanger, phase change heat storage tank and heat energy redistribution pipeline network; Among them, the working pressure of the three-stage hydraulic drive mechanism covers 0.5-100MPa, the pressure switching response time is ≤0.2 seconds, and the multi-temperature zone composite mold forms a temperature gradient of 50-250°C in the axial direction, and the gradient difference is controlled at ±5°C / 10mm.

2. The pulverized coal molding system according to claim 1, characterized in that: The three-stage crushing device also includes: iPrimary jaw crusher, discharge size ≤50mm, equipped with hydraulic overload protection device; ii Intermediate roller crusher, roller spacing adjustable range 1-10mm, surface hardness HRC ≥ 60; iii Ultra-fine vertical impact crusher with built-in cyclone classifier to achieve precise control of particle size range from 0.1 to 3mm; The crushing process adopts power feedback control, the motor load rate is maintained at 75-85%, and the crushing efficiency is ≥8t / h.

3. The pulverized coal molding system according to claim 1, characterized in that: The operating method of the microwave-hot air coupled drying tower comprises: Step S1: The raw materials are measured by a belt scale and then enter the drying tower. The initial moisture content is detected with an accuracy of ±0.3%; Step S2: Start the microwave generator array, the power density is calculated as P=0.5W in 10 2.3 Dynamic Adjustment, where W in is the input moisture content (%); Step S3: Synchronously start the swirl hot air system, with a wind speed of 2-5m / s and a temperature of 80-150°C, which is controlled in three stages; Step S4: The water content is monitored in real time by a dielectric constant sensor, and the discharge valve is triggered when the set value Wt=12±0.5% is reached.

4. The pulverized coal molding system according to claim 1, characterized in that: The three-stage hydraulic drive mechanism comprises: (I) Preload module: servo motor drives ball screw, stroke accuracy ±0.01mm, preload pressure 5-10MPa; (II) Main pressure module: four-column hydraulic cylinder with accumulator, maximum pressure 80MPa, pressure rise rate adjustable from 0.5-5MPa / s; (III) Pressure holding module: closed-loop control of piezoelectric ceramic actuator, pressure fluctuation ≤±0.3MPa, pressure holding time t=K×ln(h), where K=8-12, h is the height of the briquette (mm).

5. The pulverized coal molding system according to claim 1, characterized in that: The structure of the multi-temperature zone composite mold includes: Upper mold area: embedded heating rod array, power density 15-25W / cm², temperature PID control accuracy ±2℃; Middle mold area: micro-channel cooling system, water flow rate 3-5m / s, heat exchange efficiency ≥85%; Lower mold area: gradient porous structure, porosity 15-30%, built-in thermocouple temperature measurement point spacing ≤ 10mm; The mold surface is sprayed with a nano-composite coating, with a surface roughness Ra≤0.08 μm, wherein the friction coefficient μ of the nano-composite coating is 0.12-0.

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6. The pulverized coal molding system according to claim 1, characterized in that: The operating steps of the vibration-assisted demoulding device are as follows: Step A1: Apply ultrasonic pretreatment with a frequency of 28-35 kHz and an amplitude of 10-50 μm for 30-60 seconds before demolding; Step A2: Start the multi-rod synchronous ejection system, with the displacement error of each ejector ≤0.05mm. The speed is controlled in three stages: the first stage is 0.1-0.3mm / s (first 10% of the stroke), the second stage is 0.5-1mm / s (middle 60% of the stroke), and the third stage is 2-3mm / s (last 30% of the stroke). Step A3: Clean the mold immediately after demoulding, with a spray pressure of 0.3-0.5 MPa and a cleaning cycle of ≤15 seconds.

7. The pulverized coal molding system according to claim 1, characterized in that: The operation method of the process parameter self-optimization module includes: (α) Establish a raw material characteristics database, including 12 indicators such as ash content, volatile matter, and particle size distribution; (β) Using a deep reinforcement learning algorithm, the training objective function is F = 0.3S + 0.4D + 0.3E, where S is the compressive strength, D is the density uniformity, and E is the energy efficiency; (Y) Real-time optimization of output parameters: a combination of pressure curve, temperature gradient, and holding time, with an optimization cycle of ≤5 seconds.

8. The pulverized coal molding system according to claim 1, characterized in that: The operating logic of the waste heat recovery subsystem is: Waste heat recovery from drying exhaust gas: Flue gas is cooled to below 80°C through a heat exchanger, with a heat recovery rate of ≥65%; Mold cooling water circulation: hot water with an outlet temperature of 55-65°C is stored in a phase change heat storage tank with a heat storage density of ≥200kJ / kg; Heat energy redistribution: Recovered heat is prioritized for raw material preheating, with factory heating as the next priority, and the comprehensive utilization rate is ≥82%.

9. A mold material used in the system according to any one of claims 1 to 8, characterized in that: Contains by weight: Matrix: WC-10Co 60-65%; Reinforcement phase: TiCN nanoparticles (20-50nm) 15-20%; Lubricating component: h-BN 5-8%; Interface modifier: Cr3C2 3-5%; Sintering aid: Y2O3 1-2%; The preparation method includes: high-energy ball milling (400 rpm×10 h) → cold isostatic pressing (200 MPa) → vacuum sintering (1380°C×2 h) → surface nitriding treatment (520°C×6 h).

10. A pulverized coal molding process control method, characterized in that: The system according to claims 1-9 implements the following steps: Step B1: crush the raw materials to D90≤3mm, and adjust the moisture content to 12±0.5%; Step B2: performing gradient pressing, wherein the parameters of the gradient pressing stage are: pre-pressing: 8 MPa×30 s, mold heating rate 3°C / s, main pressure: 40→80 MPa ramp pressure increase, slope 0.8 MPa / s, holding pressure: 80±0.5 MPa×25 s, and mold temperature gradient maintained at 150→90°C; Step B3: Post-demolding treatment: spray a waterproof membrane on the surface with a thickness of 50-80 μm, and force air cool to below 60°C at a cooling rate of 5-8°C / min; Step B4: Conduct a qualified inspection on the finished product, adopt an oscillation crushing process to perform oscillation crushing, and detect the quality qualification rate.

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