A coal-saving and combustion-aiding agent for boilers with desulfurization and coking properties and its preparation method.

Abstract

This invention relates to the field of boiler fuel additive preparation, and discloses a coal-saving and combustion-aiding agent for boilers that fixes sulfur and removes coke, and its preparation method. The method includes: mixing a sulfur-fixing agent component containing calcium oxide, a framework stabilizer, and a sacrificial pore-forming agent to prepare a porous framework particle preform; mixing a flux component containing alkali metal salts and a combustion-aiding catalyst component to prepare a synergistic fluid powder; mixing the preform and powder and heating them, causing the sacrificial pore-forming agent to first decompose and gasify to form interconnected channels, followed by the melting of the synergistic fluid and its penetration and filling along the channels to form integrated sintered particles that are then cooled. The heterogeneous structure particles obtained by this method ensure the inevitable penetration of the synergistic fluid into the framework. In application, the synergistic fluid first melts out to remove coke, then exposes the sulfur-fixing framework for sulfur fixation, avoiding physical shielding interference and achieving multifunctional, stable, and synergistic effects.

Description

Technical Field

[0001] This invention relates to a coal-saving and combustion-aiding agent for boilers that removes sulfur and coke, and its preparation method, belonging to the field of boiler fuel additive preparation technology. Background Technology

[0002] Currently, to meet increasingly stringent environmental regulations and cope with fluctuating coal costs, the use of composite fuel additives with functions of sulfur fixation, coking removal, and combustion enhancement has become standard practice in the industry. The field has long pursued an additive product that can efficiently synergize the above three functions. Achieving this goal requires the synergistic effect of different components at high temperatures. However, there is an inherent constraint based on physicochemical principles. The efficient sulfur fixation function, such as the use of calcium oxide, is essentially a heterogeneous reaction between a solid material with a high specific surface area and gaseous pollutants in flue gas. The efficient coking removal function, such as the use of alkali metal salt fluxing agents, must rely on them melting into a liquid phase at high temperatures to capture and melt the solid coal ash through wetting, encapsulation, and reaction.

[0003] Existing preparation methods, whether involving simple mechanical blending of component powders or energy-intensive co-melting processes, produce additive particles that are essentially homogeneous at the microscopic level. This preparation approach, represented by mechanical blending, is particularly prevalent in existing technologies. For example, Chinese invention patent CN103254961A discloses a solid combustion aid for chain-grate coal-fired boilers. Its technical solution requires pulverizing the raw materials of the combustion aid (potassium permanganate), catalyst (sodium carbonate, potassium carbonate, calcium oxide, etc.), desulfurizing agent (calcium carbonate, magnesium oxide), and anti-scorching agent (potassium nitrate) to a fineness of 325 mesh or higher, followed by uniform mixing. This preparation method... The method yields typical homogeneous mixed particles. Under high-temperature boiler conditions, fluxes with lower melting points, such as carbonates, and anti-coking agents, such as potassium nitrate, will inevitably melt first, forming a liquid phase. This liquid phase encapsulates the high-temperature resistant solid sulfur-fixing agents (such as magnesium oxide and calcium carbonate). This homogeneous structure causes operational conflicts between the two functions with drastically different working principles in the high-temperature environment of the boiler. When the flux melts into a liquid phase to perform its coking function, this liquid phase will inevitably encapsulate the solid sulfur-fixing agent inside the particles due to capillary action and fluidity. This physical shielding effect will significantly reduce the specific surface area of ​​the sulfur-fixing agent, leading to a decrease in its gas-solid reaction activity.

[0004] Therefore, the technical problem to be solved by this invention is how to improve the existing preparation method, break the constraint between decoking and sulfur fixation functions caused by physical masking in homogeneous additives, and prepare an additive with functional partitions or heterogeneous structures at the microscopic level that can make the two major functions of sulfur fixation and decoking not interfere with each other under high temperature conditions. Summary of the Invention

[0005] This invention provides a coal-saving and combustion-aiding agent for boilers that removes sulfur and coke, and its preparation method. Its main purpose is to solve the problem that the existing preparation methods produce homogeneous particles in which the decoke removal process physically masks the sulfur fixation process, leading to mutual interference between the two processes.

[0006] To achieve the above objectives, the present invention provides a coal-saving and combustion-aiding agent for boilers that removes sulfur and coke, and a method for preparing the same. The preparation method includes the following steps:

[0007] Step a: The sulfur-fixing agent component containing calcium oxide is mixed with the skeleton stabilizer, and a sacrificial pore-forming agent is further mixed in. The porous skeleton particle preform containing the sacrificial pore-forming agent is prepared by dry pressing or rolling granulation.

[0008] Step b involves mixing a flux component containing an alkali metal salt with a combustion catalyst component to prepare a synergistic fluid powder. The synergistic fluid powder has a synergistic fluid melting point, and the porous framework particle preform has a framework softening temperature range. The synergistic fluid melting point is lower than the lower limit of the framework softening temperature range.

[0009] Step c: The porous framework particle preform is mixed with the synergistic fluid powder and heated in a heating device. The heating process includes: firstly heating to a first temperature range, which is higher than the thermal decomposition temperature of the sacrificial porogen and lower than the melting point of the synergistic fluid, so that the sacrificial porogen decomposes and vaporizes, forming a through-pore network in the porous framework particle preform; then continuing to heat to a second temperature range, which is higher than the melting point of the synergistic fluid, so that the molten synergistic fluid penetrates along the through-pore network and fills the pores of the porous framework particle preform, forming integrated sintered particles.

[0010] Step d: Cool the integrated sintered particles to obtain the combustion aid.

[0011] Preferably, the skeleton stabilizer in step a includes magnesium oxide or kaolin; and the sacrificial pore-forming agent in step a includes ammonium bicarbonate or corn starch; the combustion-supporting catalyst component in step b is a thermally decomposable catalyst precursor salt; step b further includes mixing the thermally decomposable catalyst precursor salt with a flux component; and when heated in the second temperature range of step c, the thermally decomposable catalyst precursor salt is thermally decomposed, generating a combustion-supporting catalyst in situ and dispersing it in the molten co-fluid; the decomposition products of the thermally decomposable catalyst precursor salt also include additional flux components and gas, and the gas forms microbubbles inside the co-fluid when the co-fluid cools and solidifies.

[0012] Preferably, the precursor salt of the thermally decomposable catalyst is potassium permanganate, which thermally decomposes in the second temperature range. The combustion-supporting catalyst generated in situ is manganese dioxide with a particle size in the range of 1 nm to 100 nm, and the additional fluxing component in its decomposition products is potassium manganate.

[0013] Preferably, the flux component in step b includes sodium carbonate and potassium carbonate, which are mixed in proportion to their lowest eutectic point.

[0014] Preferably, the combustion-supporting catalyst component in step b includes manganese dioxide or ferric oxide.

[0015] Preferably, the first temperature range in step c is 300°C. Up to 500 The second temperature range is 650. Up to 750 .

[0016] Preferably, step c further includes: when mixing the porous skeleton particle preform with the co-fluid powder, a high-temperature inert physical isolation medium is further incorporated, the physical isolation medium remaining in a solid phase in a second temperature range and acting as an isolation layer between the porous skeleton particle preforms in the heating device.

[0017] Preferably, the high-temperature inert physical isolation medium is graphite powder.

[0018] Preferably, step c further includes: installing an optical monitoring sensor in the heating device, and using the optical monitoring sensor to monitor the average brightness of the mixture of porous framework particle preform and synergistic fluid powder in real time. The heating process is terminated by an adaptive endpoint signal, which is generated according to the following rule: real-time calculation of average brightness. Over time slope of change ,in When the slope changes When the absolute value is less than a termination threshold in the range of 0.01 to 0.5, the permeation process is determined to be complete, and an adaptive endpoint signal is generated to trigger cooling in step d.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. By first constructing porous framework particles with initial porosity, and then using the pore network of the framework to accommodate and fill molten co-fluid, a heterogeneous structure particle with functional partitions was obtained. Under the high-temperature conditions of the boiler, the co-fluid with a lower melting point inside the particle melts first and overflows from the pores to treat the liquid or solid phase of coal ash; while the high-temperature resistant sulfur-fixing framework body maintains its inherent high specific surface area afterward, allowing it to be exposed and react with sulfur oxides in the gas phase. This microscopic action sequence of overflow followed by exposure, determined by the structure, avoids the physical masking and activity inhibition problems of the fluxing and decoking function on the solid phase sulfur-fixing function, ensuring that multiple functions of different phase feedback can coexist without conflict under their respective suitable conditions.

[0021] 2. In the step of preparing porous framework particles, a sacrificial porogen can be pre-mixed in. Based on the physical property that the decomposition temperature of the porogen is lower than the melting point of the synergistic fluid, the porogen will preferentially decompose and vaporize during the subsequent infiltration sintering heating process, creating interconnected micro-channels inside the framework. The subsequently melted synergistic fluid will then smoothly infiltrate into the particle interior along these newly formed pore networks. This sequential synergy in the process steps transforms the probability of complete fluid infiltration into a certainty guaranteed by the process, ensuring the homogeneity and integrity of the final particle function. It also eliminates the negative correlation between the mechanical pressing strength of the particle blank and the required infiltration porosity.

[0022] 3. In the preparation of the synergistic fluid powder, the conventional combustion-supporting catalyst component can be replaced with a thermally decomposable catalyst precursor salt. In the subsequent heating treatment, the in-situ thermal decomposition of the precursor salt and the melting of the synergistic fluid matrix occur synergistically in sequence. This allows the nascent, highly active nanoscale catalyst particles to be captured and uniformly dispersed by the molten fluid matrix at the moment of generation, thus avoiding the problems of catalyst particle agglomeration and sedimentation and loss of active sites caused by conventional physical mixing. In the infiltration sintering step, a high-temperature inert physical isolation medium, such as graphite powder, can be further incorporated into the mixture. In continuous production equipment such as rotary kilns, this medium powder acts as a solid isolation layer when the particles tumble, physically blocking the thermal adhesion and bridging between particles caused by the melting of the synergistic fluid. This solves the process blockage and product agglomeration bottleneck in large-scale production. At the same time, as a component with combustion-supporting function, the introduction of graphite powder as an isolation medium in the process also plays a synergistic role in enhancing the combustion-supporting function of the final product. Attached Figure Description

[0023] Figure 1 This is a process flow diagram for preparing the heterogeneous combustion improver of the present invention;

[0024] Figure 2This is a diagram of the adaptive control curve of the penetration endpoint based on the slope S of the brightness change in this invention.

[0025] Figure 3 This is a schematic diagram illustrating the mechanism of the heterogeneous structure particles' initial overflow followed by exposure in this invention. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the scope of protection of the present invention.

[0027] This invention provides a method for preparing a coal-saving and combustion-aiding agent for boilers that removes sulfur and coke. The aim is to solve the technical problem of physical masking of the solid-phase sulfur-fixing component by the liquid-phase coke-removing component in existing homogeneous additives by constructing a heterogeneous microstructure with functional partitions. The preparation method mainly includes the steps of constructing a porous framework granular preform, preparing a synergistic fluid powder, performing a multi-stage infiltration sintering heating treatment, and a cooling step. In step a of preparing the porous framework granular preform, a sulfur-fixing agent component containing calcium oxide is mixed with a framework stabilizer. The sulfur-fixing agent component, such as industrial-grade calcium oxide powder, is responsible for... The framework is the main component for high-temperature sulfur fixation. To ensure that the framework does not collapse or soften during subsequent high-temperature sintering and boiler operation, a framework stabilizer such as magnesium oxide or kaolin is introduced. This stabilizer has a melting point much higher than that of the sulfur fixation agent components and the subsequent synergistic fluids. Given that physical compression granulation alone may lead to the formation of numerous closed pores or heterogeneous channels within the particles, thus hindering the complete penetration of the subsequent liquid phase, a sacrificial pore-forming agent is further incorporated into the mixing of the above components in this step. This sacrificial pore-forming agent is preferably ammonium bicarbonate or corn starch, and its selection is based primarily on its thermal decomposition temperature. The melting point is lower than that of the synergistic fluid powder. Subsequently, the mixed powder containing the above three components is prepared into a porous framework particle preform with certain mechanical strength and internally embedded sacrificial porogen by conventional industrial methods such as dry pressing or rolling granulation. In the stage of preparing the porous framework particle preform in step a, the sulfur-fixing agent component, the framework stabilizer, and the sacrificial porogen are all powders with specific particle size distributions. For example, the D50 particle size of the sulfur-fixing agent component and the framework stabilizer is controlled in the range of 50 micrometers to 100 micrometers, while the D50 particle size of the sacrificial porogen is controlled in the range of 150 micrometers to 250 micrometers. This facilitates the uniform construction of the subsequent pore network. For dry compression granulation, the selection of the compression molding pressure can be determined through the following engineering debugging procedure: Prepare multiple sets of green body samples with different molding pressures, for example, covering the range of 50MPa to 200MPa. Heat the samples to the first temperature range to allow the sacrificial pore-forming agent to completely decompose and escape. Then measure and compare the porosity and compressive strength of each set of samples. Finally, select a molding pressure parameter that allows the green body to maintain sufficient mechanical strength while achieving the maximum or preset value of porosity, such as 30% or more, as the process setting value for subsequent mass production.

[0028] In step b, which prepares the synergistic fluid powder, the powder is designed to perform decoking and combustion-supporting functions. It is prepared by mechanically mixing a flux component containing an alkali metal salt with a combustion-supporting catalyst component. The flux component includes, for example, sodium carbonate and potassium carbonate. To obtain the lowest melting temperature and enhance fluidity, these two are preferably mixed in a ratio according to their lowest eutectic points. The combustion-supporting catalyst component may include transition metal oxides such as manganese dioxide or ferric oxide. A key technical constraint in this step is that the prepared synergistic fluid powder must have a synergistic fluid melting point, which is clearly lower than the lower limit of the softening temperature range of the porous framework particle preform. This temperature difference is a prerequisite for achieving subsequent selective melting and infiltration processes. In a preferred embodiment, to avoid the problem of conventional catalyst powder easily agglomerating and settling in molten salt and becoming deactivated, the combustion-supporting catalyst component in step b is replaced with a thermally decomposable catalyst. The precursor salt for the catalyst, such as potassium permanganate, will undergo in-situ thermal decomposition at high temperature during heating in subsequent step c, generating a highly active manganese dioxide catalyst with a particle size ranging from 1 nm to 100 nm. Simultaneously, additional flux components, namely potassium manganate and gas, are generated. The gas can form microbubbles within the co-fluid during cooling and solidification, further increasing the reaction contact area. In step b, during the preparation of the co-fluid powder, to obtain a homogeneous mixture for stable melting in the second temperature range, the flux component containing the alkali metal salt and the combustion catalyst component can be mechanically mixed, for example, using a V-type mixer or a three-dimensional motion mixer, for a mixing time of, for example, 30 minutes to 2 hours. The uniformity of the mixture and the effectiveness of its eutectic melting point can be verified by differential scanning calorimetry (DSC), i.e., taking a sample of the mixed powder and heating it at a set heating rate, such as 10... The heat flow curve is tested at a rate of / min. A uniformly mixed synergistic fluid powder should exhibit a single and sharp endothermic peak. The peak temperature of this peak corresponds to the melting point of the synergistic fluid. If multiple peaks or diffuse peaks appear, it indicates that the mixing is uneven or the component ratio deviates from the lowest eutectic point, and the mixing process or raw material ratio needs to be adjusted.

[0029] In step c, which involves heat treatment, the porous skeleton particle preform obtained in step a is first mixed with the synergistic fluid powder obtained in step b. Given that in large-scale continuous production, such as when using a rotary kiln, particles are prone to agglomeration in a high-temperature molten state, leading to process blockage and product agglomeration, this step preferably incorporates a high-temperature inert physical isolation medium, such as graphite powder. The graphite powder remains in a solid phase at subsequent heating temperatures and does not wet the molten salt, acting as an isolation layer during particle tumbling to effectively prevent thermal adhesion between particles. The mixed material is then fed into a heating device for a sequential synergistic heat treatment, which includes two stages: first, heating to a first temperature range, for example, 300°C. Up to 500 This temperature range is set above the thermal decomposition temperature of the sacrificial porogen and below the melting point of the cooperating fluid. During this stage, the sacrificial porogen inside the framework preform decomposes and vaporizes, its escape path forming a continuous pore network within the porous framework particle preform. Meanwhile, the cooperating fluid powder remains solid and does not hinder pore formation. Subsequently, heating continues to a second temperature range, for example, 650°C. Up to 750 This temperature range is above the melting point of the synergistic fluid, causing the synergistic fluid powder to melt and form a low-viscosity liquid phase. Driven by capillary force, this liquid phase permeates along the interconnected pore network and fills the pores of the porous framework particle blank. Simultaneously, the high-temperature liquid phase wets the contact points of the framework particles, playing a role in liquid-phase assisted sintering, ultimately forming integrated sintered particles. To accurately control the endpoint of this permeation sintering process and avoid incomplete permeation due to insufficient heating time or energy waste and side reactions due to excessive heating time, it is preferable to install an optical monitoring sensor in the heating equipment to monitor the average brightness of the mixture in real time. When the dark-colored co-fluid melts and is drawn into the light-colored porous framework, the overall average brightness of the material increases. It will change, through real-time calculation of average brightness. Over time slope of change ,in When the permeation process is complete, the brightness of the material tends to stabilize, and the slope of change... When the absolute value is less than a preset termination threshold, such as a value in the range of 0.01 to 0.5, the system determines that the permeation process is complete and generates an adaptive endpoint signal to trigger the next step. In step d, after receiving the adaptive endpoint signal, heating is stopped and the integrated sintered particles are cooled, for example by air cooling or water cooling, to obtain the finished product of the coal-saving combustion aid for boiler desulfurization and coking. The combustion aid obtained by the preparation method of the present invention contains integrated sintered particles with a heterogeneous microstructure, specifically: a porous skeleton composed of a desulfurizing agent component containing calcium oxide and a skeleton stabilizer, and a co-fluid solidified material that is solid at room temperature and fills the interconnected pore network of the skeleton. The co-fluid solidified material contains an alkali metal salt fluxing agent component and a combustion catalyst component. This structure ensures that in boiler applications, the co-fluid with a lower melting point melts out first to perform the coking and combustion functions, and then the exposed high-temperature desulfurizing skeleton body performs the desulfurization function.

[0030] Example 1: In a typical small-to-medium-sized chain grate boiler application scenario, the fuel used is low-quality market coal with high ash and high sulfur content, with an ash content greater than 25% and a sulfur content greater than 2%. This operating condition places dual and contradictory technical requirements on boiler additives: on the one hand, the high ash content requires the fluxing agent component, which carries the decoking function, to have high activity and high loading capacity, fully wetting and capturing a large amount of coal ash in liquid phase to prevent severe coking in the furnace; on the other hand, the high sulfur content requires the desulfurizing agent component, which carries the desulfurization function, to maintain a large specific surface area, efficiently capturing high concentrations of sulfur oxides in flue gas in solid phase to meet environmental monitoring requirements. If homogeneous particles prepared by mechanical blending or co-melting methods in the existing technology are used... The inherent physicochemical constraints of granular additives are amplified under the aforementioned operating conditions. High ash load forces the flux to form a large amount of low-melting-point liquid phase at high temperatures. While performing the decoking function, this liquid phase will inevitably flow and encapsulate the unreacted solid calcium oxide desulfurizing agent in the granules. This physical masking effect caused by the decoking process leads to a significant reduction in the specific surface area of ​​the desulfurizing agent, resulting in the failure of its desulfurization activity. Ultimately, this leads to a failure state in boiler operation where both coking and SOx emissions exceed the standard. The combustion aid prepared by the method of this invention, namely the integrated sintered granules with a porous skeleton-cooperative fluid-filled heterogeneous microstructure, undergoes a reconfiguration of its internal action sequence when applied to the same high-ash and high-sulfur operating conditions.

[0031] When the integrated sintered particles enter the high-temperature zone of the boiler, such as 650... Up to 750 When the temperature reaches a certain range, the synergistic fluid solidified material with a lower melting point, filling the pores of the porous framework, melts first. Driven by capillary forces and the micro-bubbling action of internal gas (which can be generated when using a potassium permanganate precursor), this liquid phase, which carries the functions of fluxing, decoking, and combustion catalysis, preferentially overflows from the pore network, actively dewetting, capturing, and modifying a large amount of coal ash in the furnace. This overflow process of the synergistic fluid physically clears the pore network that was originally filled by it, thus exposing the porous framework, composed of high-temperature resistant calcium oxide and magnesium oxide with a high specific surface area, to the high-temperature flue gas environment. Since the softening temperature of this framework is much higher than the current operating temperature, it always maintains a highly active solid phase state. High concentrations of sulfur oxides in the flue gas diffuse into the interior of the framework, where they react with exposed calcium oxide in a highly efficient and unimpeded gas-solid phase sulfur fixation reaction. Thus, the heterogeneous structure constructed by this preparation method results in a microscopic action sequence of first overflowing and then exposing the product during application, decoupling the decoking function of the liquid phase from the sulfur fixation function of the solid phase in both space and time. The overflow of the decoking liquid phase does not obscure the sulfur fixation framework; instead, it becomes a prerequisite for its exposure. This avoids the performance conflict between decoking and sulfur fixation functions in homogeneous additives when dealing with high-ash and high-sulfur coal types, allowing both functions to operate in parallel under their respective suitable phases. Even under conditions of drastic fluctuations in fuel quality, the synergistic effects of combustion support, decoking, and sulfur fixation can still be maintained.

[0032] Example 2: To objectively verify the synergistic effect of the heterogeneous microstructure of the combustion improver prepared by the method of the present invention on sulfur fixation and decoking functions under high-temperature conditions, the following simulated combustion test was designed; the test used a high-temperature tubular furnace as the reaction equipment, which has a programmable temperature control system with a temperature control accuracy of ±2 It is equipped with a gas mass flow controller and an exhaust gas analyzer to simulate the flue gas environment and monitor the outlet in real time. Concentration; The reference fuel used in the experiment was a high-ash, high-sulfur coal with industrial analysis data of 28.5% ash and 2.3% sulfur; Four experimental groups were set up: control group 1 (using only reference coal); control group 2 (reference coal + existing homogenizing additive); control group 3 (reference coal + additive prepared by the method of the present invention without the addition of sacrificial pore-forming agent); experimental group (reference coal + additive prepared by the complete method of the present invention); wherein, the homogenizing additive of control group 2 was prepared by mechanically mixing calcium oxide, sodium carbonate, potassium carbonate, and potassium permanganate in a ball mill for 1 hour with the same type and mass ratio of raw materials as the experimental group; the additive of control group 3 was prepared in the same steps as the experimental group except that corn starch was not added in step a; the additive of the experimental group was prepared according to the specific implementation method, wherein corn starch was used as a sacrificial pore-forming agent in step a, potassium permanganate was used as a precursor salt for thermal decomposition catalyst in step b, and the second temperature range of step c was set to 700. During the experiment, the additive and reference coal were uniformly mixed at a mass ratio of 5%. A 5.0g sample of the mixture was placed in a quartz boat and then placed in the constant-temperature zone of a tubular furnace. The furnace was then heated to 900°C. and introduce a solution containing 1500ppm Simulated flue gas was used, with the remainder being air, and the total gas flow rate was 1.0 L / min; the reaction was continued for 30 minutes, and the outlet gas was recorded using a tail gas analyzer. The concentration was determined, and the average sulfur fixation efficiency was calculated. After the reaction was completed, the sample was cooled and taken out. The ash fusion temperature, i.e. the softening temperature ST, was determined by visual observation combined with an ash fusion tester according to GB / T219-2008 standard. The test results are summarized in Table 1.

[0033] Table 1: Effects of different additives on sulfur fixation efficiency and ash melting characteristics

[0034]

[0035] Referring to the experimental data in Table 1, the reference coal in control group 1 exhibited a low ash melting point and no sulfur-fixing ability in its original state; control group 2 showed that although the addition of flux increased the ash melting temperature using the traditional homogeneous blending method, its sulfur-fixing efficiency was only 35.2%, because the molten liquid flux physically masked the solid calcium oxide, confirming the functional conflict in Example 1; data from control group 3 showed that if a sacrificial pore-forming agent was lacking in the preparation process, the resulting particles had incomplete penetration, resulting in unsatisfactory sulfur-fixing efficiency and ash melting improvement effects, highlighting the necessity of actively constructing a network of interconnected pores in step a; data from the experimental group showed that the heterogeneous structure particles obtained using the complete preparation method of this invention achieved an average sulfur-fixing efficiency of 88.7%, while the ash melting temperature was also increased to 1310℃. Both key performance indicators have been improved. The experimental data confirms that the heterostructure constructed by the preparation method of this invention is the key to achieving the synergistic effect of efficient sulfur fixation and efficient coking removal. This structure effectively avoids the problem of physical masking failure of homogeneous additives under high temperature conditions.

[0036] Example 3: To further verify the process stability and feasibility of the preparation method of the present invention in continuous industrial production, especially to evaluate the role of the high-temperature inert physical isolation medium in step c, the following comparative example was designed; Comparative Example 1 and Experimental Group 1 of the present invention were set up, and both groups of experiments simulated industrial continuous production conditions; The heating equipment used was an electrically heated rotary kiln with an inner diameter of 0.5 meters, a length of 5 meters, a rotation speed of 3 rpm, and an inclination angle of 2°; The raw material formulation and preparation steps used in both groups of experiments strictly followed the method adopted in Experimental Group 2 of Example 2, that is, both used porous skeleton granular preforms containing corn starch and synergistic fluid powders containing potassium permanganate; The only process difference was in the mixing stage of step c: Experimental Group 1 of the present invention, according to the description of the specific implementation method, added 2% of graphite powder as a high-temperature inert physical isolation medium to the mixture of preforms and powders; while Comparative Example 1 did not add this graphite powder.

[0037] The two groups of materials were continuously fed into the rotary kiln at a feed rate of 20 kg / h. The kiln heating program was consistent with that in Example 2, i.e., first at 300... Up to 500 Heating is performed in the first temperature range, followed by 650°C. Up to 750 The second temperature range was used for infiltration sintering; continuous sampling was performed at the discharge port, and the cooled finished product was sieved to calculate the target particle size, which was set to a particle yield of 2mm to 5mm; after 2 hours of experimental operation, it was observed that the rotary kiln discharge port of Comparative Example 1 began to show poor flow and large agglomerates were discharged. Its final cooling and sieving results showed that the particle yield of the target particle size of 2mm to 5mm was only 41.5%, and the rest were hard lumps larger than 10mm or fragments smaller than 2mm; In the experimental group 1 of this invention, the material flow was smooth and the discharge was uniform throughout the entire operation cycle, and no obvious agglomeration was observed. Its cooling and sieving results showed that the particle yield of the target particle size of 2mm to 5mm reached 92.8%.

[0038] Example 4: This example combines Figures 1 to 3 This document describes a coal-saving and combustion-aiding agent for boilers that uses desulfurization and coking, and its preparation method. Figure 1As shown, the method begins with multiple components, including ammonium bicarbonate or corn starch as a sacrificial porogen, magnesium oxide or kaolin as a framework stabilizer, calcium oxide as a sulfur-fixing component, potassium permanganate as a precursor salt for a thermally decomposable catalyst, and sodium carbonate and potassium carbonate as fluxing components. In step a, the sulfur-fixing component, framework stabilizer, and sacrificial porogen are mixed and granulated by dry pressing or rolling to prepare a porous framework particle preform. In step b, the fluxing component and catalyst component are mixed to prepare a synergistic fluid powder. Subsequently, the preform and powder are mixed, and a high-temperature inert physical isolation medium, such as graphite powder, can be selectively incorporated as a key process medium to form a mixture. This mixture is then heated in the first temperature range of step c-1, for example, 300°C. Up to 500 The purpose of this process is to decompose and vaporize the sacrificial pore-forming agent, forming a continuous pore network in the green body; then, it proceeds to the second temperature range of step c-2 for heating, for example, 650°C. Up to 750 The process aims to melt and permeate the pores of the synergistic fluid, and to decompose the catalyst precursor salt in situ to generate nanocatalysts. During the heating process, key process control can be implemented through optical monitoring sensors to calculate the slope of the average brightness change in real time. ,when When the value is less than the termination threshold, an adaptive endpoint signal is generated, triggering the cooling process in step d, such as air cooling or water cooling, to finally obtain integrated sintered particles of boiler combustion aid with heterogeneous microstructure.

[0039] like Figure 2 As shown, the horizontal axis represents time in minutes, and the vertical axis represents the slope S of the brightness change; the solid line in the figure represents the slope of the brightness change. This value changes over time during the permeation sintering process. It rises from the initial stage, reaches a peak of 2.0 at the 4th minute, and then begins to decline, indicating a slowdown in the permeation rate. The dashed line in the figure represents the preset termination threshold, which has a value of 0.1. When the S value, represented by the solid line, drops below this termination threshold at the 12th minute, cooling is triggered. Figure 3 As shown, before use at room temperature on the left, the particles have a heterogeneous structure. This structure consists of a porous framework composed of calcium oxide desulfurizing agent and a framework stabilizer. Inside, a network of interconnected pores formed by the decomposition and vaporization of the pore-forming agent fills a synergistic fluid solidified product that is solid at room temperature. This solidified product contains an alkali metal flux and a combustion catalyst. When it enters a boiler at high temperatures, such as 650°C... Up to 750 When in use, as shown in the high-temperature working state on the right, the lower melting point co-fluid melts first and overflows from the particles, forming a molten co-fluid that performs decoking and combustion-supporting functions on the outside of the particles. This overflow process turns the previously filled pores into empty pores, thereby exposing the high-temperature resistant porous skeleton, which maintains a high specific surface area to perform the sulfur fixation reaction.

[0040] Example 5: In step c of the preparation method of the present invention, the setting of the first temperature range and the second temperature range, as well as the calibration of the termination threshold of the adaptive endpoint signal, are key to ensuring the sequential synergy between the preferential decomposition of the sacrificial porogen and the subsequent complete penetration of the co-fluid. This example provides a standardized engineering calibration procedure for determining the above-mentioned key process parameters. In a specific calibration scenario, the raw materials used are the same as in Example 2, that is, the sacrificial porogen in step a is corn starch, and the co-fluid powder in step b is a mixture of sodium carbonate and potassium carbonate in the lowest eutectic point ratio, with potassium permanganate added as a precursor salt for the thermally decomposable catalyst. The first step in the calibration process is to determine the two core thermodynamic transition temperatures. First, take 10 mg of corn starch sample and place it in a thermogravimetric analyzer (TGA) under a nitrogen atmosphere at 10°C. Heating to 600 at a rate of / min The TGA curve shows that the main thermal decomposition and weight loss phase of this corn starch occurs at approximately 280°C. Start, and at 460 When weightlessness is essentially complete, it indicates that the upper limit of the temperature at which it completely vaporizes and escapes is 460°C. Secondly, 10 mg of the co-fluid powder sample was placed in a differential scanning calorimeter (DSC) and scanned under the same atmosphere and heating rate. The DSC curve was at approximately 675°C. A sharp endothermic peak appears, corresponding to the melting point of the alkali metal salt eutectic system, i.e., the melting point of the co-fluid. The second step in the calibration process is to set the process window based on the aforementioned transition temperature. To ensure that the sacrificial porogen completely decomposes and escapes before the co-fluid melts, the upper limit of the first temperature range must be higher than the decomposition completion temperature of the porogen, 460°C. At the same time, its upper limit must be lower than the melting point of the co-fluid, which is 675°C. To prevent premature formation of molten fluid and blockage of the channels, the first temperature range is set to 480°C. Up to 500 This provides a feasible process window; subsequently, to ensure the synergistic fluid has sufficient fluidity to fully penetrate the skeleton, the lower limit of the second temperature range must be higher than the melting point of the synergistic fluid, 675°C. And it provides a certain degree of superheat, therefore, the second temperature range is set to 700. Up to 720 .

[0041] The third step in the calibration process is to determine the termination threshold of the adaptive endpoint signal, and then apply the calibrated temperature program, i.e., the first temperature range of 500°C. Second temperature range 700 It is applied in rotary kiln heating equipment, and the optical monitoring sensor is activated to continuously record the average brightness of the mixture. Over time slope of change By sampling and observing at different time points, it was determined that the infiltration process was visually completed at approximately 15 minutes. At this point, monitoring... The signal curve showed that after penetration was complete, the The value is not absolutely zero, but fluctuates within a small range, representing the background noise of the equipment operation. The absolute peak value of this noise signal is recorded as 0.04. To avoid the system failing to trigger cooling due to background noise, while ensuring that the permeation process has been truly completed, the termination threshold must be set higher than this noise peak value of 0.04, but much lower than the value observed during the permeation process. Value, that The absolute value of the value during the permeation phase is usually greater than 1.0; therefore, it is reasonable to set the termination threshold to 0.1 in this calibration procedure. This value can effectively filter out noise interference and sensitively capture the true endpoint of the permeation process.

[0042] Example 6: This example compares the actual effects of using a thermally decomposable catalyst precursor salt in the method of the present invention with the direct use of a conventional combustion-supporting catalyst on combustion performance; Experimental group A and experimental group B were set up. The combustion-supporting agents in both groups were prepared using the complete preparation method of the experimental group in Example 2, that is, both included the sacrificial pore-forming agent (corn starch) in step a and the permeation sintering process in step c, to ensure that both have heterogeneous microstructures; the only difference is in the preparation of the synergistic fluid powder in step b: Experimental group A (precursor scheme) according to the specific implementation method, added potassium permanganate ( Potassium permanganate was used as a precursor salt for thermal decomposition catalysts; experimental group B (conventional scheme) did not add potassium permanganate, but instead added manganese dioxide, which is theoretically capable of being decomposed from potassium permanganate in experimental group A. Equimolar amounts of commercially available nano-manganese dioxide powder with an average particle size of 50 nm were used. The experiment was conducted using a thermogravimetric analyzer (TGA). The reference coal powder from Example 2 was mixed with the two groups of combustion aids at a mass ratio of 10:1. 15 mg of the mixed sample was placed in a TGA crucible and, under an air atmosphere, heated to 20 °C. Heating from room temperature to 1000 at a rate of / min Record the weight loss curve of the sample and calculate the burnout temperature of the coal sample, i.e., the temperature at which the weight loss rate recovers to near zero. The lower this temperature, the better the combustion-promoting catalytic effect. The experimental results show that the burnout temperature of the reference coal without any added combustion-promoting agent is 735°C. The burnout temperature of test group B (with added nano-MnO2 powder) was 692°C. The burnout temperature of test group A (using KMnO4 precursor) was 658°C. The data shows that although both methods have a combustion-supporting effect, the burnout temperature of test group A, which uses potassium permanganate precursor salt, is lower than that of test group B, which directly adds nano-manganese dioxide powder. This confirms that, as in the specific implementation method, potassium permanganate undergoes in-situ thermal decomposition in the second temperature range, allowing nascent, highly active nano-manganese dioxide to be instantly generated and uniformly dispersed in the molten synergistic fluid. This method avoids the problems of catalyst particle agglomeration and sedimentation and loss of active sites in high-temperature molten salt caused by conventional physical mixing.

[0043] Example 7: This example is used to objectively confirm the heterogeneous structure formed by the preparation method of the present invention through microstructure characterization, and to verify the decisive role of the sacrificial porogen in synergistic fluid permeation; integrated sintered particle products after cooling were taken from the control group 3 (without sacrificial porogen) and the experimental group (with corn starch) prepared in Example 2; the two types of particles were cold-mounted with epoxy resin, and after curing, the samples were cut to expose their internal cross-sections, and the cross-sections were polished sequentially using coarse sandpaper to fine sandpaper, and finally polished with diamond polishing paste with a particle size of 0.5µm. Fine polishing was performed; the two polished cross-sectional samples were sputter-coated with gold and placed under a scanning electron microscope (SEM) in backscattered electron (BSE) mode to observe their cross-sectional morphology. The accompanying energy-dispersive X-ray spectroscopy (EDX) was used to scan the elemental distribution of the cross-sections, focusing on the distribution of framework elements (calcium, Ca) and co-fluid elements (potassium, manganese, Mn). SEM observations showed that the particle cross-section of control group 3 (without pore-forming agent) exhibited a dense core and a loose shell. In the core region, the framework particles were densely packed with low porosity. The cross-section of the experimental group (with added pore-forming agent) showed a uniform porous network skeleton structure, with high uniformity of pore distribution across the entire cross-section. The elemental distribution spectrum obtained by energy dispersive X-ray spectroscopy further confirmed the above differences: In the cross-sectional spectrum of control group 3, the calcium (Ca) element signal was distributed throughout the entire particle, while the potassium (K) and manganese (Mn) signals showed a highly uneven distribution, mainly enriched in the outer shell of the particle, and the signal in the core region was extremely weak. This objectively indicates that after the synergistic fluid powder melted, due to the lack of through channels, it only penetrated on the surface of the particle and failed to enter the interior. In the cross-sectional spectra of the experimental group, the calcium (Ca) element signal clearly outlines a continuous porous framework, while the potassium (K) and manganese (Mn) signals are uniformly filled in the pore network of the framework, presenting a distribution image complementary to the calcium (Ca) signal. This microscopic characterization result provides direct physical evidence that the preparation method of the present invention, especially the introduction of the sacrificial porogen, successfully constructs a through-pore network in step c and achieves complete penetration and filling of the porous framework by the synergistic fluid, ultimately obtaining a heterogeneous microstructure with clearly spatially partitioned functional components.

[0044] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a coal-saving combustion-supporting agent for a boiler for desulfurization and decoking, characterized by, The method comprises the following steps: Step a, mixing a sorbent component comprising calcium oxide with a skeleton stabilizer, and further mixing a sacrificial porogen, to prepare porous skeleton granule blanks comprising the sacrificial porogen by dry pressing or roller compaction; Step b, mixing a fluxing agent component comprising an alkali metal salt with a combustion-supporting catalyst component, to prepare a synergic fluid powder, the synergic fluid powder having a synergic fluid melting point, the porous skeleton granule blanks having a skeleton softening temperature interval, the synergic fluid melting point being lower than the lower limit of the skeleton softening temperature interval; Step c, mixing the porous skeleton granule blanks with the synergic fluid powder, and performing a heating treatment in a heating device, the heating treatment comprising: firstly heating to a first temperature interval, the first temperature interval being higher than the thermal decomposition temperature of the sacrificial porogen and lower than the synergic fluid melting point, so that the sacrificial porogen is thermally decomposed and gasified to escape, forming a through-pore network in the porous skeleton granule blanks; and then continuing to heat to a second temperature interval, the second temperature interval being higher than the synergic fluid melting point, so that the molten synergic fluid penetrates and fills into the pores of the porous skeleton granule blanks along the through-pore network, forming integrated sintered granules; Step d, cooling the integrated sintered granules to obtain the combustion-supporting agent; In step a, the skeleton stabilizer comprises magnesium oxide or kaolin; and in step a, the sacrificial porogen comprises ammonium bicarbonate or corn starch, the combustion-supporting catalyst component in step b is a thermal decomposition type catalyst precursor salt; step b further comprises mixing the thermal decomposition type catalyst precursor salt with the fluxing agent component; and when heated in the second temperature interval in step c, the thermal decomposition type catalyst precursor salt is thermally decomposed to in-situ generate the combustion-supporting catalyst and disperse in the molten synergic fluid, the decomposition products of the thermal decomposition type catalyst precursor salt further comprise additional fluxing agent components and gas, which forms micro-bubbles inside the synergic fluid when the synergic fluid is cooled and solidified; The thermal decomposition type catalyst precursor salt is potassium permanganate, the in-situ generated combustion-supporting catalyst is manganese dioxide with a particle size in the range of 1 nm to 100 nm, and the additional fluxing agent component in the decomposition products is potassium manganate.

2. The preparation method of a boiler desulfurization and coke removal coal-saving combustion aid according to claim 1, characterized in that, The fluxing agent component in step b comprises sodium carbonate and potassium carbonate, which are mixed in the lowest eutectic point ratio.

3. The method for preparing the coal-saving combustion-supporting agent for sulfur fixation and decoking of a boiler according to claim 1, characterized in that, The combustion-supporting catalyst component in step b comprises manganese dioxide or diiron trioxide.

4. The method for preparing the coal-saving combustion-supporting agent for sulfur fixation and decoking of a boiler according to claim 1, characterized in that, The first temperature interval in step c is 300 up to 500 ; The second temperature interval is 650 to 750 .

5. The method for preparing the coal-saving combustion-supporting agent for sulfur fixation and decoking of a boiler according to claim 1, characterized in that, Step c further comprises: when mixing the porous skeleton granule blanks with the synergic fluid powder, further incorporating a high-temperature-inert physical isolation medium, which remains in solid phase in the second temperature interval and acts as an isolation layer between the porous skeleton granule blanks in the heating device.

6. The method for preparing the coal-saving combustion-supporting agent for sulfur fixation and decoking of a boiler according to claim 5, characterized in that, The high-temperature-inert physical isolation medium is graphite powder.

7. The method for preparing the coal-saving combustion-supporting agent for desulfurization and decoking of a boiler according to claim 1, characterized in that, Step c further comprises installing an optical monitoring sensor in the heating device and using the optical monitoring sensor to monitor the average brightness of the mixture of porous scaffold granule green bodies and synergistic fluid powder in real time ; the end of the heating process is triggered by an adaptive end signal generated according to the rule that the average brightness is calculated in real time and the slope of the change over time is calculated , wherein ; when the absolute value of the slope of the change over time is less than a termination threshold value in the range of 0.01 to 0.5, it is determined that the infiltration process is complete and an adaptive end signal is generated to trigger the cooling of step d.

8. A coal-saving combustion-supporting agent for a boiler for desulfurization and decoking, characterized by comprising: The combustion-supporting agent is prepared by the preparation method of claim 1.

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