Rare earth energy saving auxiliary for cement kilns and method for compounding same

Abstract

Provided is a rare earth energy saving auxiliary for cement kilns that reduces overall heat consumption and reduces nitrogen and sulfur emissions, and a method for compounding the same. [Solution] One aspect of the present invention relates to an energy-saving rare earth auxiliary for cement kilns, which is characterized by containing, calculated by mass fraction, 4 to 22% rare earth composite oxide, 31 to 49% urea, and 30 to 49% gypsum.

Description

[Technical field]

[0001] The present invention relates to the technical field of cement kiln energy saving and emission reduction, and in particular to a rare earth energy saving auxiliary for cement kiln and its compounding method. [Background technology]

[0002] On the premise of ensuring cement quality, facing the challenges of high consumption of raw materials and large amount of harmful gas emissions in the cement clinker production process, the development of more advanced multi-faceted energy-saving technologies is an urgent need for the sustainable development of the cement industry.

[0003] At present, in the cement clinker manufacturing process, the combustion property is poor, the clinker strength is low, the energy consumption is high, and the NOx and SOx emission indicators are strictly controlled. The commonly adopted method is to improve the hardware technology of the preheater system, such as adding SNCR, SCR, staged combustion, low NOx burner, and sulfur suppression devices using heat raw materials. In addition, the composition ratio of the existing raw materials in the plant is adjusted to improve the clinker burning condition and reduce emissions.

[0004] However, the problems are as follows: 1. When adding external equipment, a large amount of consumable materials is still required, and the cost remains high. 2. When adjusting the mixture based on the existing materials in the factory, it is difficult to eliminate the impact of harmful substances on the firing situation due to the difference limit of the mineralization conditions of the original mine.

[0005] Considering the characteristics of cement kilns, which require large production volumes and long-term continuous operation, if the quality of the clinker produced fluctuates due to the above-mentioned reasons and its strength does not meet the standards, it could cause huge economic and credibility losses to the company. Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above problems, the present invention aims to provide a rare earth energy-saving auxiliary for cement kilns that reduces overall heat consumption and reduces nitrogen and sulfur emissions, and a method for blending the same. [Means for solving the problem]

[0007] The rare earth energy saving auxiliary for cement kilns contains, calculated by mass fraction, 4-22% rare earth composite oxide, 31-49% urea, and 30-49% gypsum.

[0008] Furthermore, the rare earth composite oxide consisted of La2O3 and Y2O3, of which the mass content of La2O3 was 98-99%.

[0009] The compounding method of rare earth energy saving auxiliary for cement kiln is carried out by the following steps: (S1) Conduct a thermal engineering diagnostic investigation of the original firing process flow and material mixing ratio. Select a time period when the process is stable, and carry out thermal engineering measurements of the preheater, high temperature blower, rotary kiln, cracking furnace and cooler, and obtain the actual heat consumption Q1 of the existing clinker according to the measured values.

[0010] (S2) Based on the thermal engineering diagnosis survey, the amount of rare earth energy-saving auxiliary agent W required to be added is calculated backwards from the current analysis results, with the ideal clinker index heat consumption Q0 as the target. W%=(Q1-Q0) / Q2×1.5+0.05, Wherein, Q0 is the ideal heat consumption of clinker, Q1 is the actual heat consumption of conventional clinker, and Q2 is the average reduction index of rare earth energy-saving additives.

[0011] (S3) The tricalcium silicate C3S (alite) content, dicalcium silicate C2S (belite) content and thermal energy consumption in clinker with added rare earth energy-saving additives are measured in real time, the measurement data is plotted on a curve, and a data model is constructed.

[0012] (S4) Within the W data range obtained in S2, different additive amount data are selected and brought into the model in S3 to compare and analyze the overall heat consumption at each additive amount point.

[0013] (S5) The rare earth energy-saving additives selected by S4 are respectively added in different amounts to the conventional raw materials to obtain mixed raw materials, which are then fired at a high temperature of 1450°C to obtain clinker, and the strength of the clinker is then tested.

[0014] (S6) The basic selection condition is that the heat consumption is reduced to or below the ideal heat consumption of clinker, and the strength improvement value is the preferred condition, and the amount of rare earth energy-saving auxiliary to be added is determined.

[0015] In addition, the average decline index of rare earth energy saving auxiliary Q2=(5%~10%)Q1.

[0016] Furthermore, the rare earth energy saving auxiliary in S5 is ground to a particle size of 0.5 mm or less and then mixed with the raw material.

[0017] Compared with the conventional technology, the advantages of the present invention are as follows: (1) The eutectic temperature can be lowered, the firing speed can be increased, and the heat consumption can be reduced by 3 to 7%. (2) Improve cement burning conditions and increase clinker strength. (3) Solid sulfuric acid denitrification reduces harmful gas emissions, saves energy, reduces emissions and lowers production costs, and further achieves the goal of sustainable development of the cement industry. (4) In the case of no change or only minor changes to existing hardware, a soft process improvement of the rare earth energy-saving additive formulation model will be implemented through a production system diagnosis, thereby maximizing the potential for process improvement and saving the expansion costs for technical improvements of large hardware. [Brief description of the drawings]

[0018] [Figure 1] FIG. 2 is a data model diagram provided by Example 1 according to the embodiment. [Diagram 2]FIG. 11 is a data model diagram provided by Example 2 according to the embodiment. BEST MODE FOR CARRYING OUT THEINVENTION

[0019] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention can be embodied in many different forms, and the specific examples described in the following embodiments and examples can be appropriately modified and adjusted, and the present invention is not limited thereto.

[0020] The present invention provides a rare earth energy-saving auxiliary for cement kilns, which is composed of the following mass fractions: 4-22% rare earth composite oxide, 31-49% urea, and 30-49% gypsum. The rare earth composite oxide is composed of La2O3 and Y2O3, in which the La2O3 content is 98-99%.

[0021] The rare earth compounds in the rare earth energy saving additive enhance the oxidation and catalytic material reaction speed, improve the temperature rise reaction, and generate a low-temperature liquid phase early to form an intermediate transition phase, which decomposes and generates C3S at a relatively low temperature, thereby lowering the formation temperature of alite. Urea starts high-temperature thermal decomposition at 150℃ or more to generate ammonia gas, which reacts with nitrogen oxides in the exhaust gas to form nitrogen and discharge it, and on the other hand reacts with sulfides in the exhaust gas to form ammonia sulfite, which then reacts with calcium and aluminum raw materials in the material to form calcium aluminum sulfate, which enters the kiln, thereby achieving the purpose of denitrification and solid sulfurization. Gypsum itself is a basic calcareous material that generates a neutralization solid sulfurization reaction with acidic volatiles in the flue gas, and at the same time has a mineralization effect on lowering the eutectic point after entering the kiln, promoting chemical coordination in the liquid phase, and improving the firing speed.

[0022] Example 1 The rare earth energy saving auxiliary for cement kilns is composed of the following mass fractions: 15% rare earth composite oxide, 40% urea, and 45% gypsum. The rare earth composite oxide is composed of La2O3 and Y2O3, of which the La2O3 content is 98%.

[0023] The method of the present invention was implemented in a cement company A factory, and the specific steps are as follows: (S1) An actual thermal engineering process was measured at the cement kiln firing site, and the air volume, air pressure, and temperature data of the preheater, high-temperature blower, rotary kiln, cracking furnace, and cooler were measured, and it was found that 0.126 kg of coal and 1 m 3 It was found that the heat consumption of clinker is the amount of coal consumed to produce a unit mass of clinker. That is, in this embodiment, the amount of coal is 0.126 kg / kg clinker, and the calorific value of 1 kg of coal is 6200 kcal. The actual heat consumption Q1 of conventional clinker is converted to 780 kcal / kg-cli.

[0024] (S2) The heat consumption rate Q0 of the ideal clinker is set to 750 kcal / kg-cli, and the average reduction index Q2 of the rare earth energy-saving auxiliary is set to 39~78 kcal / kg-cli. The data is substituted into the formula W%=(Q1-Q0) / Q2×1.5+0.05, and the calculated range of W is 0.6~1.2.

[0025] (S3) The alite content, belite content and heat energy consumption in clinker with rare earth energy-saving additives were measured, and the measured data was plotted on a curve to form a data image model, as shown in Figure 1. According to the model, the changes in the alite and belite content can be divided into three stages (three regions in the figure). In the first stage (rare earth energy-saving additive content 0.5-0.9%), the alite content gradually decreased and then gradually recovered, and the belite content gradually increased and then gradually decreased. In the second stage (rare earth energy-saving additive content 0.9-1.2%), the alite content increased obviously and then slightly decreased, and the belite content decreased obviously and then slightly increased. In the third stage (rare earth energy-saving additive content 1.2-1.4%), the alite content gradually decreased and the belite content increased obviously.

[0026] (S4) According to the range of the additive amount W obtained in S2, select some additive amount data points and bring them into the data image model to analyze the overall heat consumption at a specific additive amount.

[0027] Specifically, five data of 0.6%, 0.7%, 0.8%, 1.0%, and 1.2% are selected for model comparison analysis. When the amount of addition is 0.6%, the alite content is 61%, the belite content is 26%, and the total heat consumption is 780 kcal / kg-cli, which is the same as the heat consumption of conventional clinker.

[0028] When the amount added is 0.7%, the alite content is 60%, the belite content is 27%, and the total heat consumption is 760kcal / kg-cli, which is 2.6% lower than the conventional heat consumption of 780kcal / kg-cli.

[0029] When the amount added is 0.8%, the alite content is 60.1%, the belite content is 27.1%, and the total heat consumption is 740kcal / kg-cli, which is 5.1% lower than the conventional heat consumption of 780kcal / kg-cli.

[0030] When the amount added is 1.0%, the alite content is 63.8%, the belite content is 26%, and the total heat consumption is 725kcal / kg-cli, which is 7.1% lower than the conventional heat consumption of 780kcal / kg-cli.

[0031] When the amount added is 1.2%, the alite content is 65.5%, the belite content is 25%, and the total heat consumption is 710kcal / kg-cli, which is 9% lower than the conventional heat consumption of 780kcal / kg-cli.

[0032] Comparing the above five sets of data, when the addition amount is 0.6% and 0.7%, the heat consumption is not reduced to the ideal value of clinker heat consumption, which is not consistent with the purpose of reducing heat consumption of the present invention. 0.8%, 1.0% and 1.2% are selectable data ranges.

[0033] (S5) Clinkers with different amounts of rare earth energy saving additives in S4 were selected and strength tests were carried out. The results are shown in Table 1 below. [Table 1]

[0034] From the data in Table 1, when the amount of rare earth energy saving additive added was 0.8%, the clinker strength improved by 1.5 MPa.

[0035] (S6) The basic selection condition is that the heat consumption is lower than that of the ideal clinker, and the amount of rare earth energy-saving additive is determined to be 0.8% based on the condition that the strength improvement value is favorable. The nitrogen oxide content and desulfurization effect are measured for the clinker with the determined amount added.

[0036] Under the condition that the amount of rare earth energy saving additive is 0.8%, the heat consumption can be reduced by 5% from the current 780kcal / kg, and stable operation of 740kcal / kg can be achieved. The strength of the clinker is improved by 1.5Mpa, and the nitrogen oxide content is reduced from the previous 120mg / m 3 to 70 mg / m 3 The desulfurization effect was reduced by about 30%.

[0037] Example 2 The rare earth energy saving auxiliary for cement kilns is composed of the following mass fractions: 15% rare earth composite oxide, 40% urea, and 45% gypsum. The rare earth composite oxide is composed of La2O3 and Y2O3, of which the La2O3 content is 98%.

[0038] The method of the present invention was implemented in a cement company B factory, and the specific steps are as follows: (S1) An actual thermal engineering process was measured at the cement kiln firing site. Through measurement of the air volume, air pressure, and temperature data of the preheater, high-temperature blower, rotary kiln, cracking furnace, and cooler, it was found that 0.129 kg of coal and 1 m 3It was found that the heat consumption of clinker is the amount of coal consumed to produce a unit mass of clinker. That is, in this embodiment, the amount of coal is 0.129 kg / kg clinker, and the calorific value of 1 kg of coal is 6200 kcal. The actual heat consumption Q1 of conventional clinker is converted to 800 kcal / kg-cli.

[0039] (S2) The ideal clinker heat consumption rate Q0 is set at 750 kcal / kg-cli, and the average reduction index of rare earth energy-saving additive Q2 is set at 40~80 kcal / kg-cli. The data is substituted into the formula W%=(Q1-Q0) / Q2×1.5+0.05, and the calculated range of W is 1.0~1.9.

[0040] (S3) The alite content, belite content and heat energy consumption in the clinker to which rare earth energy-saving additives were added were measured in real time, and the measurement data was plotted as a curve in the data diagram model shown in Figure 2.

[0041] (S4) According to the range of the additive amount W obtained in S2, some additive amount data points are selected and brought into the data image model to analyze the heat consumption of a specific additive amount.

[0042] Specifically, five data points of 1.0%, 1.1%, 1.2%, 1.3%, and 1.4% were selected to perform a model comparison analysis. When the amount added was 1.0%, the alite content was 63%, the belite content was 28.8%, and the total heat consumption was 750 kcal / kg-cli, which was 6.25% lower than the conventional heat consumption of 800 kcal / kg-cli.

[0043] When the amount added is 1.1%, the alite content is 65%, the belite content is 27.5%, and the total heat consumption is 740kcal / kg-cli, which is 7.5% lower than the conventional heat consumption of 800kcal / kg-cli.

[0044] When the amount added is 1.2%, the alite content is 67.5%, the belite content is 26%, and the total heat consumption is 730kcal / kg-cli, which is 8.75% lower than the conventional heat consumption of 800kcal / kg-cli.

[0045] When the amount added is 1.3%, the alite content is 67%, the belite content is 26.5%, and the total heat consumption is 725kcal / kg-cli, which is 9.4% lower than the conventional heat consumption of 800kcal / kg-cli.

[0046] When the amount added is 1.4%, the alite content is 66%, the belite content is 27.5%, and the total heat consumption is 715kcal / kg-cli, which is 10.6% lower than the conventional heat consumption of 800kcal / kg-cli.

[0047] When the amount of addition is 1.0%, the heat consumption of the clinker falls to the ideal value, and the heat consumption of the remaining four sets of data are all lower than the heat consumption of the ideal clinker, and all five sets of data meet the basic selection conditions.

[0048] (S5) Clinkers with different amounts of rare earth energy saving additives in S4 were selected and strength tests were carried out. The results are shown in Table 2 below. [Table 2]

[0049] From the data in Table 2, when the amount of rare earth energy saving additive added was 1.0%, the clinker strength was improved by 2 MPa.

[0050] (S6) The basic selection condition is that the heat consumption is reduced to below that of the ideal clinker, and the amount of rare earth energy saving additive is determined to be 1.0% based on the condition that the strength improvement value is favorable. The nitrogen oxide content and desulfurization effect are measured for the clinker for which the amount is determined.

[0051] At an additive rate of 1%, the clinker heat consumption was reduced from 800 kcal / kg to 750 kcal / kg. The clinker strength was improved from 54 MPa to 56 MPa. The nitrogen oxide emission was 130 mg / m 3 to 50 mg / m 3 and sulfur trioxide is reduced to within 30 mg / m 3 It stabilizes within a few minutes and the effect is obvious. [Industrial Applicability]

[0052] INDUSTRIAL APPLICABILITY The present invention has industrial applicability as a rare earth energy-saving auxiliary for cement kilns, which reduces overall heat consumption and reduces nitrogen and sulfur emissions, and as a compounding method thereof.

Claims

1. The rare earth energy saving auxiliary for cement kilns is characterized by containing, calculated by mass fraction, 4 to 22% rare earth composite oxide, 31 to 49% urea, and 30 to 49% gypsum.

2. The rare earth energy saving auxiliary according to claim 1, wherein the rare earth composite oxide is La ２ O ３ and Y ２ O ３ Of these, La ２ O ３ A mass content of 98-99% is required.

3. The rare earth energy saving auxiliary for cement kilns according to claim 1 or 2 is characterized in that it is blended in the following steps: (S1) Conduct a thermal engineering diagnostic investigation of the original firing process flow and material mixing ratio. Select a time when the process is stable and measure the heat of the preheater, high temperature blower, rotary kiln, cracking furnace and cooler. Based on the measured values, calculate the actual heat consumption Q of the existing clinker. １ to obtain. (S2) Based on the thermal engineering diagnosis survey, the ideal clinker index heat consumption Q ０ With this as the goal, the amount W of rare earth energy saving auxiliary required for addition is calculated backwards based on the current analysis results. W%=(Q １ -Q ０ ) / Q ２ ×1.5+0.05, Among them, Q ０ is the heat loss of the ideal clinker, and Q １ is the actual heat loss of conventional clinker, and Q ２ is the average reduction index of rare earth energy saving auxiliary. (S3) C in cement clinker under different rare earth energy saving additive amounts ３ S content, C ２ The change in the S content and the thermal energy consumption is measured, and the measured data is plotted into a curve to construct a diagram data model. (S4) Within the W data range obtained in S2, select different dosing data and input them into the graph data model in S3 to compare and analyze the overall heat consumption at each dosing point. (S5) The rare earth energy saving additives selected in S4 are respectively added to the conventional raw materials to obtain mixed raw materials, which are then fired at a high temperature of 1450°C to form clinker, and the strength of the clinker is then tested. (S6) Based on the results of S4 and S5, the basic selection condition is that the heat consumption is reduced to or below the ideal clinker heat consumption, and the strength improvement value is the preferred condition, and the amount of rare earth energy-saving auxiliary to be added is determined.

4. The method for blending the rare earth energy saving auxiliary for cement kilns according to claim 1 is characterized in that the average reduction index Q of the rare earth energy saving auxiliary is ２ =(5%~10%)Q １ It is characterized in that:

5. The method for blending a rare earth energy-saving auxiliary for a cement kiln according to claim 1 is characterized in that in S5, the rare earth energy-saving auxiliary is ground to a particle size of 0.5 mm or less and then mixed with the raw material.

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