Simplified selection method for blast furnace gas boiler induced draft fan

Abstract

The application discloses a simplified selection method for a blast furnace gas boiler induced draft fan, and comprises the following steps: calculating the amount of flue gas generated by the combustion of each cubic meter of blast furnace gas according to the dry basis heat value of the blast furnace gas; calculating the total standard flue gas amount according to the blast furnace gas flow and the calculated flue gas amount; calculating the total resistance of the flue gas system before the induced draft fan inlet and the total resistance of the flue gas system after the induced draft fan according to the total standard flue gas amount, the flue gas temperature, the local atmospheric pressure, the flue gas pressure and the equipment resistance; calculating the induced draft fan inlet negative pressure according to the calculated total resistance of the flue gas system before the induced draft fan inlet and the hearth negative pressure; calculating the actual total flue gas amount according to the flue gas temperature at the induced draft fan inlet, the local atmospheric pressure and the induced draft fan inlet negative pressure; calculating the selection air volume of the induced draft fan according to the actual total flue gas amount V 总 and calculating the selection pressure head according to the total resistance of the flue gas system before the induced draft fan inlet, the total resistance of the flue gas system after the induced draft fan, the self-generated draft of the chimney, the hearth negative pressure and the number of the induced draft fans.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel enterprises coal gas power generation, and particularly relates to a simplified selection method of a blast furnace gas boiler induced draft fan. BACKGROUND

[0002] A large amount of by-product coal gas is produced in the smelting process of a steel enterprise, including blast furnace gas, converter gas, coke oven gas and the like. In addition to being supplied to each smelting process of the steel plant for self-use, a certain amount of the by-product coal gas is in surplus, especially the blast furnace gas. For the surplus coal gas, the steel plant generally recycles and utilizes it through a coal gas boiler. As an important auxiliary machine of the coal gas boiler, the selection of the induced draft fan is crucial to the economic and safe operation of the unit. However, at present, the selection of the induced draft fan has the following characteristics: first, it is relatively extensive and not reasonable. The air volume of the induced draft fan is closely related to the excess air coefficient. At present, a certain set value (such as 1.15) is usually taken in engineering, but in fact, the excess air coefficient of different calorific values of the coal gas is different (even if the oxygen content is the same), which is a major difference between metallurgical coal gas and conventional fuels such as coal, natural gas and biomass. Second, the range of the calorific value of the coal gas can be provided in many projects, but the accurate composition of the coal gas cannot be provided, especially in the early stage of the project, which undoubtedly brings difficulties to the selection of the blast furnace gas boiler induced draft fan. Third, the automation level, operation personnel level and unit maintenance and maintenance capacity of different steel plants are different, resulting in large differences in the air volume and pressure head of the induced draft fan of the same unit in the same region, with the same fuel and the same parameters. SUMMARY

[0003] In view of the above defects, the present application aims to construct a simplified selection method of a blast furnace gas boiler induced draft fan under limited conditions.

[0004] To achieve the above-mentioned purpose, the simplified selection method of the blast furnace gas boiler induced draft fan of the steel enterprise comprises the following steps:

[0005] The flue gas volume generated by the combustion of each cubic meter of blast furnace gas is calculated according to the dry basis calorific value of the blast furnace gas;

[0006] The total flue gas volume at the standard state is calculated according to the blast furnace gas flow rate and the calculated flue gas volume;

[0007] The total resistance of the flue gas system before the induced draft fan inlet and the total resistance of the flue gas system after the induced draft fan are calculated according to the total flue gas volume at the standard state, the flue gas temperature, the local atmospheric pressure, the flue gas pressure and the equipment resistance;

[0008] The negative pressure at the induced draft fan inlet is calculated according to the calculated total resistance of the flue gas system before the induced draft fan inlet and the hearth negative pressure;

[0009] According to the flue gas temperature at the inlet of the induced draft fan, local atmospheric pressure and negative pressure at the inlet of the induced draft fan, the actual total flue gas volume is calculated.

[0010] According to the actual total flue gas volume V 总 , the selected air volume of the induced draft fan is calculated, and the selected pressure head is calculated according to the total resistance of the flue gas system before the inlet of the induced draft fan, the total resistance of the flue gas system after the induced draft fan, the self-generated draft of the chimney, the furnace negative pressure and the number of induced draft fans.

[0011] Further, the steps are specifically as follows:

[0012] Step 1: According to the calorific value Q of the blast furnace gas d , the flue gas volume V generated by the combustion of each cubic meter of blast furnace gas is calculated. y,0

[0013] V y,0 = aQ d + b

[0014] Wherein, V y,0 is the flue gas volume generated by the combustion of each cubic meter of blast furnace gas, unit Nm 3 / Nm 3 ; Q d is the dry basis calorific value of blast furnace gas kJ / Nm 3 ; a, b are calculation coefficients.

[0015] Step 2: According to the blast furnace gas flow B into the furnace, the standard state total flue gas volume V y,1 is calculated.

[0016] V y,1 = BV y,0

[0017] Wherein, V y,1 is the standard state total flue gas volume, unit Nm 3 / h; B is the dry basis standard state flow of blast furnace gas into the furnace, unit Nm 3 / h; V y,0 is the flue gas volume generated by the combustion of each cubic meter of blast furnace gas, unit Nm 3 / Nm 3 .

[0018] Step 3: According to the standard state total flue gas volume, flue gas temperature, local atmospheric pressure, flue gas pressure and equipment resistance, the total resistance P1 of the flue gas system before the inlet of the induced draft fan and the total resistance P2 of the flue gas system after the induced draft fan are calculated.

[0019] Step 4: According to the total resistance P1 of the flue gas system before the inlet of the induced draft fan and the furnace negative pressure p lt , the negative pressure p y at the inlet of the induced draft fan is calculated.

[0020] p y = p​lt P1

[0021] wherein p y is the negative pressure at the inlet of the induced draft fan, in Pa; p lt is the negative pressure in the furnace, in Pa; and P1 is the total resistance of the flue gas system before the induced draft fan, in Pa.

[0022] Step 5: calculate the actual total flue gas volume V y according to the flue gas temperature t y at the inlet of the induced draft fan, the local atmospheric pressure p0, and the negative pressure p 总 at the inlet of the induced draft fan.

[0023]

[0024] wherein V 总 is the actual total flue gas volume, in m 3 / h; t y is the flue gas temperature at the inlet of the induced draft fan, in ℃; p0 is the local atmospheric pressure, in Pa; p y is the negative pressure at the inlet of the induced draft fan, in Pa; and V y,1 is the standard total flue gas volume, in Nm 3 / h.

[0025] Step 6: determine the selected air volume and the selected pressure head of the induced draft fan, as follows:

[0026] 1) selected air volume V 选型 = 1.1 x k x V 总 / N

[0027] wherein V 选型 is the selected air volume of the induced draft fan, in m 3 / h; k is the flow coefficient considering the air leakage at the flue gas side of the air preheater and the air leakage of the boiler flue gas system after one year of operation of the unit; V 总 is the actual total air volume, in m 3 / h; and N is the number of induced draft fans.

[0028] 2) selected pressure head P 选型 = 1.2 x (P1 + P2 - P3 - p lt )

[0029] wherein P 选型 is the selected pressure head of the induced draft fan, in Pa; P1 is the total resistance of the flue gas system before the induced draft fan, in Pa; P2 is the total resistance of the flue gas system after the induced draft fan, in Pa; P3 is the self-generated draft of the chimney, in Pa; and p lt is the negative pressure in the furnace, in Pa.

[0030] Further, in step 1, a = 1.6 x 10 -4 ~ 1.7 x 10-4 b=1.2~1.3.

[0031] Further, the blast furnace gas heat value Q d The blast furnace gas flow B corresponds to the data under the boiler BMCR condition.

[0032] Further, the furnace negative pressure p lt The value is -20~-50Pa.

[0033] Further, if the accurate data of the equipment factory is lacking, the flow coefficient k of the step 6 is 1.05, which considers the air preheater flue gas side air leakage and the boiler flue gas system air leakage after the unit operation for one year.

[0034] To achieve the above purpose, the storage medium of the present application has a computer program stored thereon, which realizes the simplified selection method of the blast furnace gas boiler induced draft fan of the steel enterprise when the computer program is executed by the processor.

[0035] The present application constructs a set of general rapid selection method of blast furnace gas boiler induced draft fan under limited conditions, which can complete the relevant selection calculation only by the gas heat value, is very convenient, and eliminates the tedious process of traditional detailed calculation which needs a large amount of basic data. Moreover, the method provided by the present application has good universality, which can be used in steel plants with high operation and maintenance level or high automation level, and is also suitable for steel plants with low operation and maintenance level; can be used for rough selection in the early stage of the project, and can also be used for empirical checking of detailed selection in the preliminary design stage, and has strong practical significance. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The flowchart of the present application. DETAILED DESCRIPTION

[0037] In the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore cannot be understood as a limitation on the present application.

[0038] The terms "first", "second", "third", etc. are used only for descriptive purposes and do not connote or imply relative importance or a specific number of the technical features indicated. Thus, features defined with "first", "second", etc. can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified and limited, the term "a plurality of" means two or more.

[0039] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0040] The steel enterprise blast furnace gas boiler induced draft fan simplification method, the method comprises the following steps:

[0041] According to the dry basis heat value of the blast furnace gas, the flue gas quantity generated by the combustion of each cubic meter of blast furnace gas is calculated;

[0042] According to the blast furnace gas flow and the calculated flue gas quantity, the standard total flue gas quantity is calculated;

[0043] According to the standard total flue gas quantity, the flue gas temperature, the local atmospheric pressure, the flue gas pressure and the equipment resistance, the total resistance of the flue gas system before the induced draft fan inlet and the total resistance of the flue gas system after the induced draft fan are calculated;

[0044] According to the calculated total resistance of the flue gas system before the induced draft fan inlet and the hearth negative pressure, the induced draft fan inlet negative pressure is calculated;

[0045] According to the flue gas temperature at the induced draft fan inlet, the local atmospheric pressure, the induced draft fan inlet negative pressure, the actual total flue gas quantity is calculated;

[0046] According to the actual total flue gas quantity V 总 The selection air volume of the induced draft fan is calculated, and the selection pressure head is calculated according to the total resistance of the flue gas system before the induced draft fan inlet, the total resistance of the flue gas system after the induced draft fan, the chimney self-ventilation force, the hearth negative pressure and the number of induced draft fans.

[0047] The above method can complete the relevant selection calculation only with the gas heat value, which is very convenient, and eliminates the tedious process of traditional detailed calculation which needs a large amount of basic data. Moreover, the method provided by the present application has good universality, which can be used in steel plants with high operation and maintenance level or high automation level, and also suitable for steel plants with low operation and maintenance level; it can be used for rough selection in the early stage of the project, and also can be used for empirical checking of detailed selection in the preliminary design stage.

[0048] The specific steps of an exemplary embodiment of the present application are as follows:

[0049] Step 1: According to the calorific value Q of the blast furnace gas d Calculate the flue gas volume V generated by the combustion of each cubic meter of blast furnace gas y,0 :

[0050] V y,0 = aQ d + b

[0051] Wherein, V y,0 is the flue gas volume generated by the combustion of each cubic meter of blast furnace gas, unit Nm 3 / Nm 3 ; Q d is the dry basis calorific value of blast furnace gas kJ / Nm 3 ; a, b are calculation coefficients; for steel plants with high operation and maintenance level or high degree of automation, and which have invested in boiler combustion automatic control, the calculation coefficient a = 1.625 x 10 -4 , b = 1.23. For steel plants with low operation and maintenance level, extensive management, and which have not invested in boiler combustion automatic control, the calculation coefficient a = 1.669 x 10 -4 , b = 1.26.

[0052] Step 2: According to the blast furnace gas flow B into the furnace, calculate the standard state total flue gas volume V y,1 :

[0053] V y,1 = BV y,0

[0054] Wherein, V y,1 is the standard state total flue gas volume, unit Nm 3 / h; B is the dry basis standard state flow of blast furnace gas into the furnace, unit Nm 3 / h; V y,0 is the flue gas volume generated by the combustion of each cubic meter of blast furnace gas, unit Nm 3 / Nm 3 ;

[0055] The above blast furnace gas calorific value Q d , blast furnace gas flow B into the furnace correspond to the data under the boiler BMCR condition.

[0056] Step 3: According to the standard state total flue gas volume, flue gas temperature, local atmospheric pressure, flue gas pressure and equipment resistance, calculate the total resistance P1 of the flue gas system before the induced draft fan inlet and the total resistance P2 of the flue gas system after the induced draft fan;

[0057] Step 4: According to the total resistance P1 of the flue gas system before the induced draft fan inlet and the furnace negative pressure p lt , calculate the induced draft fan inlet negative pressure p y :

[0058] p y = p lt -P1

[0059] wherein, p y is the negative pressure at the inlet of the induced draft fan, in Pa; p lt is the negative pressure in the furnace, in Pa; and P1 is the total resistance of the flue gas system before the induced draft fan, in Pa.

[0060] Step 5: Calculate the actual total flue gas volume V y according to the flue gas temperature t y at the inlet of the induced draft fan, the local atmospheric pressure p0, and the negative pressure p 总 at the inlet of the induced draft fan:

[0061]

[0062] wherein, V 总 is the actual total flue gas volume, in m 3 / h; t y is the flue gas temperature at the inlet of the induced draft fan, in ℃; p0 is the local atmospheric pressure, in Pa; p y is the negative pressure at the inlet of the induced draft fan, in Pa; and V y,1 is the total flue gas volume at standard state, in Nm 3 / h.

[0063] Step 6: Determine the selected air volume and the selected pressure head of the induced draft fan, as follows:

[0064] 1) Selected air volume V 选型 = 1.1 x k x V 总 / N

[0065] wherein, V 选型 is the selected air volume of the induced draft fan, in m 3 / h; k is the flow coefficient considering the air leakage at the flue gas side of the air preheater and the air leakage of the boiler flue gas system after one year of operation of the unit; if accurate data of the equipment factory are not available, k is taken as 1.05; V 总 is the actual total air volume, in m 3 / h; and N is the number of induced draft fans.

[0066] 2) Selected pressure head P 选型 = 1.2 x (P1 + P2 - P3 - p lt )

[0067] wherein, P 选型 is the selected pressure head of the induced draft fan, in Pa; P1 is the total resistance of the flue gas system before the induced draft fan, in Pa; P2 is the total resistance of the flue gas system after the induced draft fan, in Pa; P3 is the self-generated draft of the chimney, in Pa; and p lt is the negative pressure in the furnace, in Pa.lt The value can be -30 Pa.

[0068] In some example embodiments, a non-transitory computer readable storage medium, such as a memory including instructions executable by a processor to perform the method described above is also provided. The non-transitory computer readable storage medium can be a Read Only Memory (ROM), a Random Access Memory (RAM), a magnetic tape and an optical storage device, etc.

[0069] Those skilled in the art can understand that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application. Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described system, device and unit can refer to the corresponding processes in the foregoing method embodiments, which will not be repeated here.

[0070] In the embodiments disclosed herein, it should be understood that the disclosed methods, products (including but not limited to devices, equipment, etc.) can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division, and actual implementation can have another division manner. For example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interface, device or unit, and can be electrical, mechanical or other forms. The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e. can be located in one place, or can be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purposes of the embodiments. In addition, the functional units in each embodiment of the present application can be integrated in one processing unit, or each unit can be physically present separately, or two or more units can be integrated in one unit.

[0071] It should be understood that the flow diagrams and block diagrams in the drawings are presented to illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present application. In this regard, each block in the flow diagrams and block diagrams can represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical functions ("instructions"). It should also be noted that in some alternative implementations, the functions noted in the blocks can occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently or the blocks can sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and / or flow diagrams, and combinations thereof, can be implemented by a dedicated hardware-based system that performs the specified functions or acts, or combinations of hardware and software. The present application is not limited to the above-described and illustrated flow and structure, and various modifications and changes can be made without departing from its scope. The scope of the present application is limited only by the claims that follow.

Claims

1. A simplified selection method for induced draft fans in blast furnace gas boilers, characterized in that, The method includes the following steps: The amount of flue gas produced per cubic meter of blast furnace gas combustion is calculated based on the dry basis calorific value of blast furnace gas. Calculate the standard total flue gas volume based on the blast furnace gas flow rate and the calculated flue gas volume; Calculate the total resistance of the flue gas system before the induced draft fan inlet and the total resistance of the flue gas system after the induced draft fan based on the standard total flue gas volume, flue gas temperature, local atmospheric pressure, flue gas pressure, and equipment resistance. The negative pressure at the inlet of the induced draft fan is calculated based on the total resistance of the flue gas system before the inlet of the induced draft fan and the negative pressure in the furnace. The actual total flue gas volume is calculated based on the flue gas temperature at the induced draft fan inlet, the local atmospheric pressure, and the negative pressure at the induced draft fan inlet. Based on the actual total flue gas volume V 总 Calculate the required air volume for the induced draft fan, and calculate the required pressure head based on the total resistance of the flue gas system before and after the induced draft fan inlet, the self-generated ventilation force of the chimney, the negative pressure in the furnace, and the number of induced draft fans. The specific steps of the method are as follows: Step 1: Based on the calorific value Q of the blast furnace gas d Calculate the amount of flue gas V produced per cubic meter of blast furnace gas combustion. y,0 : V y,0 =aQ d +b Among them, V y,0 The amount of flue gas produced per cubic meter of blast furnace gas combustion, expressed in Nm³. 3 / Nm 3 Q d The dry basis calorific value of blast furnace gas is kJ / Nm³. 3 a and b are calculation coefficients, where a = 1.6 × 10⁻⁶ -4 ~1.7×10 -4 b = 1.2 to 1.3; Step 2: Calculate the standard total flue gas volume V based on the blast furnace gas flow rate B. y,1 : V y,1 =BV y,0 Among them, V y,1 Total flue gas volume under standard conditions, unit: Nm³ 3 / h; B is the dry standard flow rate of blast furnace gas entering the furnace, in Nm³. 3 / h;V y,0 The amount of flue gas produced per cubic meter of blast furnace gas combustion, expressed in Nm³. 3 / Nm 3 ; Step 3: Calculate the total resistance P1 of the flue gas system before the induced draft fan inlet and the total resistance P2 of the flue gas system after the induced draft fan based on the standard total flue gas volume, flue gas temperature, local atmospheric pressure, flue gas pressure and equipment resistance. Step 4: Based on the total resistance P1 of the flue gas system before the induced draft fan inlet and the furnace negative pressure p lt Calculate the negative pressure p at the inlet of the induced draft fan y : p y =p lt -P1 Where, p y This refers to the negative pressure at the inlet of the induced draft fan, measured in Pa; p lt P1 represents the negative pressure in the furnace, in Pa; P2 represents the total resistance of the flue gas system before the induced draft fan, in Pa. Step 5: Based on the flue gas temperature t at the inlet of the induced draft fan y Local atmospheric pressure p0, induced draft fan inlet negative pressure p y Calculate the actual total flue gas volume V 总 : Among them, V 总 This represents the actual total flue gas volume, in cubic meters (m³). 3 / h;t y p is the inlet flue gas temperature of the induced draft fan, in °C; p0 is the local atmospheric pressure, in Pa; p y The negative pressure at the inlet of the induced draft fan is expressed in Pa; V y,1 Total flue gas volume under standard conditions, unit: Nm³ 3 / h; Step 6: Determine the required air volume and pressure head for the induced draft fan, as follows: 1) Selecting the air volume V 选型 =1.1×k×V 总 / N Among them, V 选型 For selecting the air volume of the induced draft fan, the unit is m³. 3 / h; k is the flow coefficient considering air leakage on the air preheater flue gas side and air leakage in the boiler flue gas system after one year of unit operation; V 总 This represents the actual total air volume, in meters (m³). 3 / h; N is the number of induced draft fans; 2) Selecting the pressure head P 选型 =1.2×(P1+P2-P3-p) lt ) Among them, P 选型 P1 is the pressure head for selecting the induced draft fan, in Pa; P2 is the total resistance of the flue gas system before the induced draft fan, in Pa; P3 is the total resistance of the flue gas system after the induced draft fan, in Pa; p is the self-generated ventilation force of the chimney, in Pa. lt This represents the negative pressure in the furnace, expressed in Pa.

2. The simplified selection method for induced draft fans in blast furnace gas boilers as described in claim 1, characterized in that, The calorific value Q of the blast furnace gas d The data for the blast furnace gas flow rate B corresponds to the boiler BMCR operating condition.

3. The simplified selection method for induced draft fans in blast furnace gas boilers as described in claim 1, characterized in that, The furnace negative pressure p lt The value ranges from -20 to -50 Pa.

4. The simplified selection method for induced draft fans in blast furnace gas boilers as described in claim 1, characterized in that, In step 6, the flow coefficient k for considering air leakage on the air preheater flue gas side and air leakage in the boiler flue gas system after one year of unit operation is taken as 1.05.

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