Burnup economic operation method for water granulated slag vertical mill system

Abstract

The invention relates to a water slag vertical mill system burn-up economic operation method which specifically comprises the following steps: step 1, under the conditions of hot blast stove temperature automatic control and vertical mill stable production, adjusting the cold air adding amount of a hot blast stove to obtain a curve of the cold air adding amount and burn-up fluctuation, and step 2, under the conditions of hot blast stove temperature automatic control and vertical mill stable production, adjusting the cold air adding amount of the hot blast stove to obtain a curve of the burn-up fluctuation. And step 3, according to the field production process test, the bivariate factor change of the cold air adding amount of the hot blast stove and the bivariate factor change of the mixing backflow flue gas amount entering the mill are synthesized, and the relation curve of the bivariate factors and the burnup fluctuation is obtained. According to the scheme, the effect of reducing the burnup of the hot blast stove is achieved on the premise that no equipment or system transformation is carried out.

Description

Technical Field

[0001] The invention relates to a method, in particular to a method for fuel-economic operation of a slag vertical mill system, belonging to the technical field of fuel-economic operation of a blast furnace slag vertical mill system. Background Art

[0002] The slag micro-powder production line of steel enterprises generally adopts the vertical mill grinding production process. The hot blast furnace burns the hot air (hot flue gas) generated by blast furnace gas and other fuels, and mixes cold air as the heating medium to complete the material drying and powder transportation. The hot air of the mill passes through the vertical mill of the mineral powder and is discharged through the main dust collector. The temperature of the discharged waste flue gas is about 100°C. In the existing production process, the hot air entering the mill is provided by the hot blast furnace. In order to adjust the wind temperature before entering the mill and save energy, part of the circulating reflow flue gas (waste flue gas) is added before entering the mill for waste heat utilization. However, in most of the current production processes, the utilization of the circulating reflow flue gas (waste flue gas) and the operation control of the cold air addition mainly rely on on-site experience and judgment, and lack of overall consideration for the system air supply volume and heat balance, which not only limits the stability of on-site production operation, but also cannot guarantee the low-consumption production requirements of the vertical mill system. Therefore, a new solution is urgently needed to solve this technical problem. Summary of the invention

[0003] The present invention is aimed at the technical problems existing in the prior art and provides a method for fuel-economic operation of a slag vertical mill system. The technical scheme provides a method for fuel-economic operation range of a slag vertical mill system. The method finds the optimal fuel consumption economic operation range and production control parameters of the hot blast furnace by changing and adjusting the mixing of cold air and return flue gas in the hot blast furnace, combining the comprehensive consideration of air volume balance and heat balance required for stable production of the mineral powder vertical mill, as well as the control of the mixing ratio of cold air volume and return flue gas. The effect of reducing the fuel consumption of the hot blast furnace is achieved without any equipment or system modification.

[0004] In order to achieve the above-mentioned purpose, the technical scheme of the present invention is as follows: a method for fuel-efficient operation of a slag vertical mill system, a method for fuel-optimal economic operation of a slag micro-powder vertical mill production system of the present invention, under the condition of automatic temperature control of the hot blast furnace and stable production of the vertical mill, the amount of cold air exchanged by the hot blast furnace (the opening of the air door) and the amount of return flue gas mixed with the mill (the opening of the return flue gas valve), as well as the change of the pressure difference distribution of the system are adjusted respectively, and the curve of the change of gas consumption of the hot blast furnace and the fluctuation of fuel consumption is obtained,

[0005] The invention discloses a method for optimizing fuel consumption and economic operation of a slag micro powder vertical mill production system. According to on-site production process tests, when the opening of the hot blast furnace and the cold air door is ≥80% (150,000 m 3 / h), the inlet and outlet temperatures of the mill are low, the mill cannot operate stably, and the system heat cannot be balanced.

[0006] The present invention provides a method for the optimal fuel consumption economic operation of a slag micro powder vertical mill production system. According to the on-site production process test, when the valve opening of the mixing and reflowing flue gas entering the mill is ≤30%, the gas consumption of the hot blast furnace increases significantly. If the valve opening of the mixing and reflowing flue gas entering the mill is ≥85%, the balance of the system wind pressure and air volume cannot be achieved, and the negative pressure of the hot blast furnace is greatly reduced, resulting in the heat of the hot air not being transferred to the mill, and stable production operation cannot be carried out. For details, see the attached Figure 2 .

[0007] The invention discloses a method for economically operating a slag micro-powder vertical mill production system with optimal fuel consumption. According to on-site production process tests, the heat balance and air volume balance calculation of the system are realized, the optimal control parameters of the mixing return flue gas volume and the hot blast furnace cold air volume are controlled, and the optimal fuel consumption level of the hot blast furnace is determined.

[0008] The air volume and heat balance control of the slag fine powder vertical mill production system according to the above embodiment of the present invention has the following additional technical features:

[0009] Technical feature 1: In the embodiment of the present invention, the heat balance equation of the slag micro powder vertical mill system is:

[0010] Q 1 +Q 2 +Q 3 =Q 1 '+Q 2 '+Q 3 '

[0011] The meaning of each heat code in the formula is shown in the following table:

[0012]

[0013] Technical feature 2: In the embodiment of the present invention, the air volume balance equation of the vertical mill system in the slag micropowder production process is:

[0014] G 11 +G 12 +G 13 +G 14 =G 1 '

[0015] The meaning of each air volume code in the formula is shown in the following table:

[0016]

[0017] Note: The main fan outlet air volume = the flue gas return volume into the mill + the flue gas volume discharged from the chimney. The normal operating condition is 200,000 to 260,000 m2 / h.

[0018] Technical feature three: In the embodiment of the present invention, the empirical formula for data regression between the cold air volume of the hot blast furnace in the vertical mill system, the mixed reflux flue gas volume and the fuel consumption in the slag micropowder production process is:

[0019] r 燃耗 =0.0008*K 1 2 +0.0017*K 2 2 -0.04*K 1 -0.02*K 2 +8.95*ε

[0020] The meaning of each code in the formula is shown in the following table:

[0021] Code project Parameter Annotations <![CDATA[r 燃耗 ]]> Hot blast furnace fuel consumption <![CDATA[K 1 ]]> Backflow flue gas mixing opening Opening degree of return flue gas regulating valve: 30~80(%) <![CDATA[K 2 ]]> Hot air furnace to cold air opening Cooling air door opening 25~75(%) ε Correction factor Related to the calorific value of gas

[0022] Compared with the prior art, the present invention has the following advantages: the technical solution proposes a method for optimal economic operation of the fuel consumption of a slag micro-powder vertical mill system, based on the comprehensive consideration of the air volume balance and heat balance required for stable production; the control range of the hot blast furnace to cold air volume and the mixing ratio of the reflux flue gas is proposed, so that the fuel consumption of the vertical mill system is in the economic operation range. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a trend diagram of the change in cooling air volume and hot blast furnace fuel consumption of a vertical mill system according to an embodiment of the present invention,

[0024] Figure 2 The figure is a trend diagram between the change of the mixing and reflowing flue gas volume of the vertical mill system and the fuel consumption of the hot blast furnace according to an embodiment of the present invention.

[0025] Figure 3 The trend diagram of the vertical mill system fuel consumption and the opening of the cold air damper and the opening of the mixed return flue gas regulating valve according to the embodiment of the present invention is shown in FIG. Figure 4 This is the vertical mill production process flow chart. DETAILED DESCRIPTION

[0026] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0027] Example 1: See Figure 1-Figure 3 A method for fuel-efficient operation of a slag vertical mill system, the method comprising the following steps:

[0028] Step 1: Under the condition of automatic temperature control of the hot blast furnace and stable production of the vertical mill, adjust the size of the cold air volume of the hot blast furnace (damper opening) to obtain the curve of cold air volume and fuel consumption fluctuation. Figure 1 This is a trend diagram between the change of the cooling air volume of the vertical mill system and the fuel consumption of the hot blast furnace according to an embodiment of the present invention. According to the production process test: under the condition of a certain opening of the return flue gas regulating valve, the fuel consumption of the hot blast furnace and the opening of the cooling air volume damper (cooling air volume) show a nonlinear relationship. As the opening of the cooling air damper increases, the fuel consumption gradually increases. When the opening is 45% to 60%, the fuel consumption change trend is relatively gentle. When the opening of the cooling air damper is ≥85% (150,000 m 3 / h), the inlet temperature is too low and the mill vibrates, which cannot meet the inlet temperature for normal production; the system heat cannot be balanced. When the cold air damper opening is ≤30%, the fuel consumption will gradually increase.

[0029] Step 2: Under the condition of automatic control of hot blast furnace temperature and stable production of vertical mill, adjust the amount of mixed reflux flue gas entering the mill (opening of reflux flue gas valve) to obtain the curve of mixed reflux flue gas amount and fuel consumption fluctuation. Figure 2 This is a trend diagram between the change in the amount of mixed reflow flue gas and the fuel consumption of the hot blast furnace of the vertical mill system according to an embodiment of the present invention. According to the production process test: under a certain opening of the cold air, the fuel consumption of the hot blast furnace and the opening of the mixed reflow flue gas regulating valve show a nonlinear relationship. As the opening of the reflow flue gas increases, the fuel consumption gradually decreases (making full use of the heat of the reflow flue gas). Among them, the fuel consumption change trend is relatively gentle when the opening is 55% to 75%. When the opening of the reflow flue gas is ≥80%, the balance of the system wind pressure and air volume cannot be achieved, and the negative pressure of the hot blast furnace is greatly reduced (≤-100pa), resulting in the heat of the hot air not being transferred to the mill, and stable production operation cannot be carried out.

[0030] Step 3: According to the on-site production process test, the changes in the dual variable factors of the hot air furnace and the cold air volume and the flue gas volume mixed with the mill are comprehensively considered to obtain the relationship curve between the dual variable factors and the fuel consumption fluctuation. Figure 3 The figure is a trend diagram of the vertical mill system fuel consumption and the change of the cold air damper opening and the mixed return flue gas regulating valve opening according to the embodiment of the present invention, as well as the fuel consumption economic operation range and the optimal fuel consumption. Under the condition of ensuring the stable production operation of the system, the economic operation range of the hot blast furnace fuel consumption is: the mixed return flue gas regulating valve opening is 50% to 70%, and the cold air damper opening is 32% to 42%; the optimal fuel consumption is 11.05kgce / t, and the optimal fuel consumption is 62% for the return flue gas opening and 36% for the cold air damper opening.

[0031] Among them, in step 3, the empirical formula for data regression between the two-variable factors (hot blast furnace to cold air volume, mixed reflux flue gas volume) and fuel consumption is:

[0032] r 燃耗 =0.0008*K 1 2 +0.0017*K 22 -0.04*K 1 -0.02*K 2 +8.95*ε

[0033] Where: r 燃耗 Represents the hot blast furnace fuel consumption, K 1 Represents the opening degree of the backflow flue gas mixing, K 2 represents the opening degree of the hot air furnace to cold air, and ε represents the correction coefficient.

[0034] When the opening of the return flue gas door is 62% and the opening of the cold air damper is 36%, the fuel consumption of the hot blast furnace is optimal, and the optimal fuel consumption is 11.05kgce / t.

[0035] Optimal fuel consumption: vertical mill system negative pressure distribution parameters: hot air furnace outlet negative pressure -280pa, mill inlet negative pressure -1200pa, flue gas mill outlet negative pressure -2800pa, main exhaust fan inlet negative pressure -4300pa; system air volume is 228280m 3 / h, and the heat balance is calculated to be 42.22GJ / h.

[0036] Example 2: In one embodiment of the present invention, the feed rate of the slag water in the vertical mill system is 91t / h, the feed size is less than 20mm, the feed moisture content is ≤7.5%, and the production of S95 slag powder is 85t / h (adding about 4 / 1000 grinding aids), and the specific surface area of ​​the produced slag is ≥410m 2 / g, the maximum moisture content of the mineral powder is less than 0.5%, the hot blast furnace uses blast furnace gas, and the low calorific value of the gas is 780kcal / m 3 The vertical mill production process is as follows: Figure 4 .

[0037] When the optimal fuel consumption of the present invention is used, the typical negative pressure parameters of the system at the optimal fuel consumption and the negative pressure distribution range of the system under normal production conditions are as follows:

[0038]

[0039]

[0040] When the optimal fuel consumption of the present invention is used, the heat balance calculation results are as follows:

[0041]

[0042] When the optimal fuel consumption of the present invention is used, the air volume balance calculation results are as follows:

[0043]

[0044] According to the results of heat balance calculation in this embodiment, the optimal fuel consumption of the system is 11.05kgce / t. According to the energy consumption limit per unit product of slag powder (DB31 / 581-2019), the energy consumption limit per unit product of existing slag powder production enterprises is 15kgce / t, and the preferred fuel consumption result is better than the standard.

[0045] It should be noted that the above embodiments are not intended to limit the protection scope of the present invention, and equivalent changes or substitutions made on the basis of the above technical solutions all fall within the protection scope of the claims of the present invention.

Claims

1. A method for fuel-efficient operation of a slag vertical mill system, characterized in that: The method comprises the following steps: Step 1: Under the condition of automatic temperature control of hot blast furnace and stable production of vertical mill, adjust the cold air volume of hot blast furnace to obtain the curve of cold air volume and fuel consumption fluctuation. Step 2: Under the condition of automatic temperature control of the hot blast furnace and stable production of the vertical mill, adjust the amount of mixed and refluxed flue gas entering the mill to obtain the curve of mixed and refluxed flue gas amount and fuel consumption fluctuation. Step 3: According to the on-site production process test, the changes in the dual variable factors of the hot air furnace and the cold air volume and the flue gas volume mixed with the mill are comprehensively considered to obtain the relationship curve between the dual variable factors and the fuel consumption fluctuation.

2. The method for fuel-efficient operation of a slag vertical mill system according to claim 1, characterized in that: In step 3, the empirical formula for data regression between the two-variable factors (hot blast furnace cold air volume, mixed reflux flue gas volume) and fuel consumption is: r 燃耗 =0.0008*K1 2 +0.0017*K2 2 -0.04*K1-0.02*K2+8.95*e Where: r 燃耗 represents the fuel consumption of the hot blast furnace, K1 represents the opening degree of the return flue gas, K2 represents the opening degree of the hot blast furnace to cold air, and ε represents the correction coefficient.

3. The method for fuel-efficient operation of a slag vertical mill system according to claim 2, characterized in that: When the opening of the return flue gas door is 62% and the opening of the cold air damper is 36%, the fuel consumption of the hot blast furnace is optimal, and the optimal fuel consumption is 11.05kgce / t.

4. The method for fuel-efficient operation of a slag vertical mill system according to claim 3, characterized in that: Optimal fuel consumption: vertical mill system negative pressure distribution parameters: hot air furnace outlet negative pressure -280pa, mill inlet negative pressure -1200pa, flue gas mill outlet negative pressure -2800pa, main exhaust fan inlet negative pressure -4300pa; system air volume is 228280m 3 / h, and the heat balance is calculated to be 42.22GJ / h.

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