Calculation method for heat transfer coefficient of a cyclone dust collector with a heat exchange device

Abstract

The present invention discloses a calculation method for the heat transfer coefficient of a cyclone dust collector with a heat exchange device, comprising the following steps: Step 001, determining the relevant parameters affecting the heat transfer coefficient; including the flue gas flow rate, the inlet flue gas pressure, the inlet flue gas temperature, and the temperature difference between the inlet and outlet water; Step 002, using the relevant parameters, assuming the heat transfer coefficient calculation formula based on regression analysis as: K = M + BV + CP + D(T1 + 273.15) 4 + EΔt w ; Step 003, using the heat transfer amount calculation formula, inversely calculating the actual heat transfer coefficient K1 according to the actual heat transfer amount; Step 004, repeating the steps in Step 003), for multiple groups of actual heat transfer coefficients K1 obtained by calculation, through the regression analysis calculation method, the specific values of M, B, C, D, and E in the heat transfer coefficient calculation formula described in Step 002 can be calculated, and the final heat transfer coefficient calculation formula can be obtained. The present invention can accurately guide the heat transfer design calculation of a cyclone dust collector with a heat exchange device, greatly improving the relevant efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of heat transfer research of heat exchange devices, and specifically relates to a calculation method for the heat transfer coefficient of a cyclone dust collector with a heat exchange device. Background Art

[0002] The dust in the cyclone dust collector is driven by the air flow and separated. Therefore, the flow field condition in the cyclone dust collector has a crucial impact on the separation efficiency. Due to the complexity of its own flow field, there is currently no perfect theory to summarize the laws of the flow field, and only a certain simplified model can be adopted for theoretical analysis, which also affects the design of high-efficiency cyclone dust collectors to a certain extent.

[0003] The cyclone dust collector with a heat exchange device can handle a large amount of dusty flue gas, and at the same time can reduce the outlet temperature of the cyclone dust collector. On the one hand, it can save energy and reduce consumption, and on the other hand, it can provide low-temperature technical conditions for subsequent flue gas treatment such as bag dust removal.

[0004] At present, under variable operating conditions (such as the simultaneous change of the flow rate and temperature of converter gas), there is no practical and accurate calculation formula for calculating the heat transfer coefficient of a cyclone dust collector with a heat exchange device, making it impossible to quickly and accurately calculate the heat transfer parameters related to the cyclone dust collector with a heat exchange device based on the heat transfer coefficient.

[0005] In the prior art, mainly through numerical simulation and relevant design experience, the relevant heat transfer parameters of the designed cyclone dust collector with a heat exchange device are deduced; however, during the design, there are errors between the deduced heat transfer parameters and the heat transfer parameters obtained after physical experiments, and sometimes the errors are very large, exceeding the acceptable range, which makes the designed cyclone dust collector with a heat exchange device inefficient or even ineffective, affecting the heat exchange performance and dust removal efficiency of the designed cyclone dust collector with a heat exchange device. Summary of the Invention

[0006] The purpose of the present invention is to provide a calculation method for the heat transfer coefficient of a cyclone dust collector with a heat exchange device to solve the technical problem of difficult calculation of the heat transfer coefficient of a cyclone dust collector with a heat exchange device in the prior art.

[0007] To solve the above technical problem, the present invention specifically provides the following technical solution: A calculation method for the heat transfer coefficient of a cyclone dust collector with a heat exchange device, comprising the following steps:

[0008] Step 001, determining the relevant parameters affecting the heat transfer coefficient;

[0009] Including flue gas flow rate, flue gas inlet pressure, flue gas inlet temperature, and the temperature difference between the inlet and outlet water.

[0010] Step 002: Using the parameters described in Step 001, assume the heat transfer coefficient calculation formula based on regression analysis as:

[0011] K = M + BV + CP + D(T 1 + 273.15) 4 + EΔt w ;

[0012] In the formula:

[0013] K—Heat transfer coefficient, kw / m 2 ·°C;

[0014] V—Flue gas flow rate, Nm 3 / h;

[0015] P—Flue gas inlet pressure, Pa;

[0016] (T 1 + 273.15) 4 —Regression parameter;

[0017] T 1 —Flue gas inlet temperature, °C;

[0018] Δt w —Outlet - inlet water temperature difference, Δt w = t 2 - t 1 t 2 —Outlet water temperature, t 1 —Inlet water temperature, °C;

[0019] M, B, C, D, and E are constants respectively;

[0020] Step 003: Using the heat transfer amount calculation formula, inversely calculate the actual heat transfer coefficient K based on the actual heat transfer amount 1 ;

[0021] Among them, the actual heat transfer amount is calculated from the flue gas composition and the inlet and outlet temperatures;

[0022] Among them, the heat transfer amount calculation formula is:

[0023] Q = 3600K 1 AΔT;

[0024] In the formula:

[0025] Q—Heat transfer amount, kJ;

[0026] K 1 —Heat transfer coefficient, kw / m 2 ·°C;

[0027] A—Heat transfer calculation area, m 2 ;

[0028] ΔT—the average temperature difference, °C;

[0029] Step 004: Repeat the steps described in step 003) to calculate multiple groups of actual heat transfer coefficients K obtained. 1 Through the regression analysis calculation method, the specific values of M, B, C, D, and E in the heat transfer coefficient calculation formula described in step 002 can be calculated, and the final heat transfer coefficient calculation formula can be obtained.

[0030] Furthermore, in step 003, the actual heat transfer amount is the total heat of the flue gas inlet minus the total heat of the flue gas outlet, minus the heat dissipation amount.

[0031] Among them, according to the measured flue gas inlet temperature and the composition of the flue gas, look up the corresponding enthalpy value in the enthalpy-temperature table to calculate the total heat of the flue gas inlet.

[0032] According to the measured flue gas outlet temperature and the composition of the flue gas, look up the corresponding enthalpy value in the enthalpy-temperature table to calculate the total heat of the flue gas outlet.

[0033] The heat dissipation amount includes the convective heat transfer amount and the radiative heat transfer amount.

[0034] Furthermore, the convective heat transfer amount is calculated using Newton's cooling formula, and the formula is:

[0035] Φ 1 = hA 1 Δt;

[0036] In the formula,

[0037] h—the surface heat transfer coefficient, w / m 2 ·K;

[0038] A 1 —the outer surface heat transfer area, m 2 ;

[0039] Δt—the average temperature difference, Δt = T 3 -T 4 , K;

[0040] T 3 —the outer surface temperature of the cyclone dust collector, K;

[0041] T 4 —the air temperature, K;

[0042] The radiative heat transfer amount adopts the Stefan-Boltzmann formula:

[0043] Φ 2 = εA 1 σ(T 3 4 -T 44 );

[0044] Wherein,

[0045] ε—the emissivity of the outer surface, and ε is assumed to be 0.9;

[0046] A 1 —the heat transfer area of the outer surface, m 2 ;

[0047] σ—the black body radiation constant, which is 5.67E-08, w / (m 2 ·K 4 );

[0048] T 3 —the temperature of the outer surface of the cyclone dust collector, K;

[0049] T 4 —the air temperature, K.

[0050] Furthermore, during the process of calculating multiple groups of actual heat transfer coefficients K 1 , the same heat dissipation is adopted.

[0051] Furthermore, in step 003, the calculation formula for the heat transfer calculation area A is:

[0052] A = S F + S T + S TX + 2 / 3(S Z + S ZX );

[0053] Wherein,

[0054] A—the heat transfer calculation area, m 2 ;

[0055] S F —the inner surface area (excluding the opening) of the head (1), m 2 ;

[0056] S T —the inner surface area of the cylinder body (3), m 2 ;

[0057] S TX —the outer surface area of the heat exchange tubes of the cylinder heat exchange device (4), m 2 ;

[0058] S Z —the inner surface area of the conical cylinder (5), m 2 ;

[0059] S ZX —the outer surface area of the heat exchange tubes of the conical cylinder heat exchange device (6), m 2 .

[0060] Further, in the step 003, the calculation formula for the average temperature difference ΔT is:

[0061]

[0062] In the formula:

[0063] ΔT—the average temperature difference, °C;

[0064] Δt 1 —the maximum temperature difference, Δt 1 = T 2 - t 1 , °C;

[0065] Δt 2 —the minimum temperature difference, Δt 2 = T 1 - t 2 , °C;

[0066] t 1 —the inlet water temperature, °C;

[0067] t 2 —the outlet water temperature, °C;

[0068] T 1 —the flue gas inlet temperature, °C;

[0069] T 2 —the flue gas outlet temperature, °C.

[0070] Further, in the step 004, after the converter working condition is stable, determine the flue gas inlet and outlet temperatures at multiple sampling time points, and calculate the actual heat transfer coefficient K at multiple sampling time points according to the method described in the step 003 1 ;

[0071] Then perform regression analysis and calculation on multiple groups of actual heat transfer coefficients K 1 to obtain the calculation formula for the heat transfer coefficient as:

[0072] K = -0.08536 + 3.86122×10 -6 V - 4.30659×10 -5 P

[0073] + 0.00387×10 -11 (T 1 + 273.15) 4 - 6.64177×10 -4 Δt w ;

[0074] In the formula:

[0075] K — Heat transfer coefficient, kw / m 2 ·℃;

[0076] V — Flue gas flow rate, Nm 3 / h;

[0077] P — Flue gas inlet pressure, Pa;

[0078] T 1 — Flue gas inlet temperature, ℃;

[0079] Δt w — Temperature difference between outlet and inlet water, Δt w = t 2 - t 1 t 2 — Outlet water temperature, t 1 — Inlet water temperature, ℃.

[0080] Furthermore, the calculation formula of the heat transfer coefficient is verified as follows:

[0081] Step 501) Assume the flue gas outlet temperature;

[0082] Step 502) Obtain the heat transfer coefficient K according to the heat transfer coefficient calculation formula, and then obtain the heat transfer amount through the heat transfer amount calculation formula;

[0083] Step 503) According to the flue gas inlet temperature and the composition of the flue gas, look up the corresponding enthalpy value in the enthalpy-temperature table and calculate the total heat of the flue gas inlet;

[0084] Step 504) Subtract the heat transfer amount and the heat dissipation amount from the total heat of the flue gas inlet to obtain the assumed total heat of the flue gas outlet;

[0085] Step 505) Use the interpolation method through the enthalpy-temperature table to calculate the calculated flue gas outlet temperature from the assumed total heat of the flue gas outlet obtained in Step 504;

[0086] Step 506) Compare the flue gas outlet temperature with the calculated flue gas outlet temperature;

[0087] If the error is less than 0.5%, it is qualified;

[0088] Otherwise, re-assume the flue gas outlet temperature and continue the iterative calculation until it converges and is qualified, so as to obtain the calculated flue gas outlet temperature.

[0089] Step 507) Compare the calculated flue gas outlet temperature with the actual flue gas outlet temperature to obtain the calculation error.

[0090] The present invention has the following beneficial effects compared with the prior art:

[0091] The method provided by the present invention for calculating the heat transfer coefficient of a cyclone dust collector with a heat exchange device uses relevant parameters affecting the heat transfer coefficient and is derived based on regression analysis to obtain a formula for calculating the heat transfer coefficient, with the error within an acceptable range.

[0092] By calculating the heat transfer coefficient of a cyclone dust collector with a heat exchange device, it can be used to guide the design of a cyclone dust collector with a heat exchange device, such that the error between the relevant heat transfer parameters of the cyclone dust collector with a heat exchange device designed based on the calculated heat transfer coefficient and the preset relevant heat transfer parameters during design is within an acceptable range. This not only reduces the calculation amount for designing a cyclone dust collector with a heat exchange device but also ensures the accuracy of the calculation results during the design process, making the designed cyclone dust collector with a heat exchange device effective. BRIEF DESCRIPTION OF THE DRAWINGS

[0093] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings described below are merely exemplary, and those of ordinary skill in the art can also obtain other implementation drawings based on the provided drawings without creative efforts.

[0094] Figure 1 Structural diagram of the cyclone dust collector for calculating the heat transfer coefficient in the present invention;

[0095] Figure 2 Comparison diagram of the outlet temperature and the calculated temperature of the cyclone dust collector for single-hearth continuous stable operation of the converter in this embodiment;

[0096] Figure 3 Comparison diagram of the highest outlet temperature and the calculated temperature of a single furnace of the converter for multiple continuous hearths in this embodiment;

[0097] Figure 4 Error diagram of the highest calculated temperature at the outlet of a single furnace of the converter for multiple continuous hearths in this embodiment.

[0098] The reference numerals in the drawings are respectively represented as follows:

[0099] In the figure, 1 - head, 2 - head heat exchange device, 3 - cylinder body, 4 - cylinder body heat exchange device, 5 - conical cylinder, 6 - conical cylinder heat exchange device, 7 - ash hopper, 8 - ash hopper heat exchange device, 9 - separation cylinder, 10 - air inlet, 11 - exhaust port, 12 - ash discharge port. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0100] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0101] The present invention provides a specific implementation method for calculating the heat transfer coefficient of a cyclone dust collector with a heat exchange device, including the following steps:

[0102] Step 001: Determine the relevant parameters affecting the heat transfer coefficient;

[0103] Combined with the operating conditions of the cyclone dust collector with a bag heat exchange device in the actual converter working conditions, the relevant parameters affecting the heat transfer coefficient include flue gas flow rate, flue gas inlet pressure, flue gas inlet temperature, and the temperature difference between the outlet and inlet water.

[0104] Step 002: Take the flue gas flow rate, flue gas inlet pressure, flue gas inlet temperature, and the temperature difference between the outlet and inlet water as the parameters for regression analysis. The flue gas inlet temperature is deduced as (T 1 +273.15) 4 As the regression term for regression analysis calculation, based on the regression analysis, assume the heat transfer coefficient calculation formula is:

[0105] K = M + BV + CP + D(T 1 +273.15) 4 + EΔt w ;

[0106] In the formula,

[0107] K - heat transfer coefficient, kw / m 2 ·℃;

[0108] V - flue gas flow rate, Nm 3 / h;

[0109] P - flue gas inlet pressure, Pa;

[0110] T 1 —flue gas inlet temperature, ℃;

[0111] Δt w —temperature difference between the outlet and inlet water, Δt w = t 2 - t 1 ,t 2 —outlet water temperature, t 1 —inlet water temperature, ℃;

[0112] M, B, C, D, and E are constants respectively.

[0113] Among them, (T1 +273.15) 4 As an important parameter in the regression analysis calculation; (T 1 +273.15) is used to convert Celsius temperature to thermodynamic temperature; Considering the important influence of radiation heat transfer on the heat transfer coefficient, by referring to the Stefan-Boltzmann formula for calculating the radiant heat flux of an object, Φ 1 =εAσT 4 ; The regression term of the parameter related to the flue gas inlet temperature in this formula is assumed to be (T 1 +273.15) 4 .

[0114] Step 003, use the heat transfer amount calculation formula to inversely deduce the actual heat transfer coefficient K according to the actual heat transfer amount 1 ;

[0115] Among them, the heat transfer amount calculation formula is:

[0116] Q=3600K 1 AΔT;

[0117] In the formula,

[0118] Q—the heat transfer amount, kJ;

[0119] K 1 —the heat transfer coefficient, kw / m 2 ·℃;

[0120] A—the heat transfer calculation area, m 2 ;

[0121] ΔT—the average temperature difference, ℃.

[0122] The following gives a specific embodiment for calculating the actual heat transfer amount.

[0123] The actual heat transfer amount is the total heat of the flue gas inlet minus the total heat of the flue gas outlet, and then minus the heat dissipation; The heat dissipation includes convective heat transfer and radiative heat transfer.

[0124] Among them, according to the measured flue gas inlet temperature and the composition of the flue gas, look up the corresponding enthalpy value in the enthalpy-temperature table to calculate the total heat of the flue gas inlet.

[0125] Similarly, according to the measured flue gas outlet temperature and the composition of the flue gas, look up the corresponding enthalpy value in the enthalpy-temperature table to calculate the total heat of the flue gas outlet;

[0126] Among them, the composition of the flue gas in this embodiment is shown in Table 1:

[0127] Table 1 Flue Gas Composition Table

[0128] <![CDATA[N 2 > 2.76 ％ <![CDATA[O 2 > 0.46 ％ CO 80.47 ％ <![CDATA[CO 2 > 16.31 ％ Ash content 95 <![CDATA[g / m 3 >

[0129] In the process of obtaining data related to regression analysis, during the stable operation stage of the converter, the change in flue gas composition can be ignored.

[0130] Among them, the enthalpy-temperature table used for calculating heat is shown in Table 2:

[0131] Table 2 Enthalpy-temperature table

[0132]

[0133] Furthermore, an embodiment of the calculation of the heat dissipation is given as follows:

[0134] In this embodiment, considering the convenience of calculation and the fact that the actual heat dissipation does not change much, therefore, during the process of obtaining multiple groups of actual heat transfer coefficients K 1 , a unified heat dissipation is adopted; assume the temperature value of the outer surface of the cyclone dust collector and the temperature value of the air, and use the heat dissipation at this temperature value for all subsequent calculations of the actual heat transfer amount K 1 .

[0135] Specifically, assume that the temperature of the outer surface of the cyclone dust collector is 50 °C and the air temperature is 0 °C to calculate the heat dissipation.

[0136] Among them, the assumption that the temperature of the outer surface of the cyclone dust collector is 50 °C is based on the normal national standard and the heat preservation requirement that the outer surface does not exceed 50 °; usually, the atmospheric or air temperature is 10 - 30 °C, and 0 ° generally refers to winter or cold regions. Assuming it is 0 °C, consider the larger heat dissipation under normal circumstances.

[0137] The calculated result of this heat dissipation will be slightly larger than the actual heat dissipation, but the error has little impact on the final result and is within an acceptable range.

[0138] First, use Newton's cooling formula to calculate the convective heat transfer amount. The formula is:

[0139] Φ 1 = hA 1 Δt;

[0140] In the formula,

[0141] h - surface heat transfer coefficient, w / m 2 ·K;

[0142] A 1 - outer surface heat transfer area, m 2 ;

[0143] Δt - average temperature difference, Δt = T 3 - T 4 , K;

[0144] T 3 - temperature of the outer surface of the cyclone dust collector, K;

[0145] T 4 — air temperature, K;

[0146] The radiant heat transfer amount is calculated using the Stefan - Boltzmann formula.

[0147] Among them, the Stefan - Boltzmann formula for calculating the radiant heat flux of an object is:

[0148] Φ 1 = εAσT 4 ;

[0149] Specifically in this embodiment, based on the Stefan - Boltzmann formula, the corrected Stefan - Boltzmann law formula for calculating the radiant heat transfer amount is obtained:

[0150] Φ 2 = εA 1 σ(T 3 4 - T 4 4 );

[0151] In the formula,

[0152] ε— outer surface emissivity, ε is assumed to be 0.9;

[0153] A 1 — outer surface heat transfer area, m 2 ;

[0154] σ— blackbody radiation constant, which is 5.67E - 08, w / (m 2 ·K 4 );

[0155] T 3 — outer surface temperature of the cyclone dust collector, K;

[0156] T 4 — air temperature, K.

[0157] Among them, the heat dissipation amount is the sum of the convective heat transfer amount and the radiant heat transfer amount.

[0158] The following is illustrated with specific embodiments, and the relevant data is shown in Table 3:

[0159] Table 3 Calculation data table of heat dissipation amount

[0160]

[0161] According to the internal air flow temperature corresponding to different positions of the cyclone dust collector, it is divided into three zones: Zone I, Zone II, and Zone III. As Figure 1 shown, Zone I is the high - temperature zone, including the head 1 and the cylinder 3; Zone II is the medium - temperature zone, including the conical cylinder 5; Zone III is the low - temperature zone, the ash hopper 7 and the following part.

[0162] For different surface heat transfer coefficients h, it is respectively assumed that in Zone I it is 3.12 W / (m 2 ·K), in Zone II it is 2.64 W / (m 2 ·K), and in Zone III it is 1.86 W / (m 2 ·K).

[0163] The emissivity ε of the outer surface is all assumed to be 0.9, and the Stefan - Boltzmann constant σ is 5.67E - 08 W / (m 2 ·K 4 ).

[0164] The outer surface area (the outer surface of the insulation layer) A is respectively 98.83 m 2 , 70.34 m 2 , 23.17 m 2 .

[0165] As shown in the above table, the heat dissipation is obtained as 79172 W.

[0166] Since they are all conventional calculations, the calculation process is omitted.

[0167] Next, an explanation is given for (A - the heat transfer calculation area) in the heat transfer calculation formula.

[0168] As Figure 1 shown, since the gas flow in the cyclone dust collector is rotational flow, the scouring velocity of the wall surface at different axial positions is also different, resulting in inconsistent heat transfer coefficients. The air inlet 10 is tangentially connected to the separation cylinder 9 inside the cylinder body 3. The heat transfer coefficient of the wall surface of the cylinder body 3 around the air inlet 10 is the highest, and the heat transfer coefficient of the wall surface of the ash hopper 7 connected to the conical cylinder 5 is the smallest.

[0169] To simplify the steps, within the allowable error range, the heat transfer calculation area A in this embodiment preferably selects the inner surface area of the head 1, the inner surface area of the cylinder body 3, and the outer surface area of the heat exchange tubes of the cylinder heat exchange device 4; adopts 2 / 3 of the inner surface area of the conical cylinder 5 and 2 / 3 of the outer surface area of the heat exchange tubes of the conical cylinder heat exchange device 6; abandons the outer surface area of the heat exchange tubes of the head heat exchange device 2, the inner surface area of the ash hopper 7, the outer surface area of the heat exchange tubes of the ash hopper heat exchange device 8, the inner surface area of the exhaust port 11, and the inner surface area of the ash discharge port 12.

[0170] Therefore, the calculation formula for obtaining the heat transfer calculation area A is:[[]]

[0171] A = S F + S T + S TX + 2 / 3(S Z + S ZX );

[0172] In the formula,

[0173] A—the heat transfer calculation area, m 2 ;

[0174] S F —the inner surface area of the first head (excluding the opening), m 2 ;

[0175] S T —the inner surface area of the third cylinder, m 2 ;

[0176] S TX —the outer surface area of the heat exchange tubes of the heat exchange device in the third cylinder, m 2 ;

[0177] S Z —the inner surface area of the conical cylinder 5, m 2 ;

[0178] S ZX —the outer surface area of the heat exchange tubes of the heat exchange device in the conical cylinder 6, m 2 。

[0179] The following is an explanation of (ΔT—the average temperature difference) in the heat transfer amount calculation formula.

[0180] In this embodiment, the existing average temperature difference ΔT calculation formula is:

[0181]

[0182] In the formula,

[0183] ΔT—the average temperature difference, °C;

[0184] Δt 1 —the maximum temperature difference, Δt 1 = T 2 - t 1 , °C;

[0185] Δt 2 —the minimum temperature difference, Δt 2 = T 1 - t 2 , °C;

[0186] t 1 —the inlet water temperature, °C;

[0187] t 2 —the outlet water temperature, °C;

[0188] T 1 —the flue gas inlet temperature, °C;

[0189] T 2 —the flue gas outlet temperature, °C.

[0190] Step 004: Combine the multiple groups of actual heat transfer coefficients K obtained in Step 003 1 , and through the regression analysis calculation method, the specific numerical values of M, B, C, D, and E in the heat transfer coefficient calculation formula described in Step 002 can be calculated, and the final heat transfer coefficient calculation formula can be obtained.

[0191] In this embodiment, after the converter working condition is stable, determine the flue gas inlet and outlet temperatures at multiple sampling time points, and calculate the actual heat transfer coefficients K at multiple sampling time points according to the method in Step 003) 1 .

[0192] Specifically, determine the sampling time points in the 72-hour continuous working converter working condition. From the stable working conditions of each heat, compare and determine the highest inlet temperature data, and at the same time select two point parameters around or above and below the highest temperature as the sampling time points.

[0193] The three-point parameters are based on the principle of being relatively close without abrupt changes. The time interval between the two test data is 1 minute, the calculated data is adopted as the 3-minute average parameter, and the average parameter of the sum of the test parameters at the three points is taken as the source of the calculated data. This method can eliminate or reduce the test error caused by data lag recording.

[0194] Select and determine the calculation data of 76 heats from all the test parameters, and calculate 76 groups of actual heat transfer coefficients K according to the calculation data of the above 76 heats 1 , according to the obtained 76 groups of actual heat transfer coefficients K 1 , using the regression analysis calculation method, determine the assumed heat transfer coefficient calculation formula, K = M + BV + CP + D(T 1 +273.15) 4 +EΔt w , and finally obtain the quantitative relationship between the variables M, B, C, D, and E that are interdependent, and the quantitative numerical values of M, B, C, D, and E.

[0195] The following discloses the calculation data of 4 heats, as shown in Table 4 - Table 5.

[0196] The regression calculation of the heat transfer coefficient formula is to use the highest inlet temperature of each heat and three time measurement points with little change in the temperature difference before and after, that is, the data averaged over three minutes.

[0197] A heat refers to the sequence of smelting one furnace of steel. In each heat, the total time is about 35 minutes, and the oxygen blowing time is about 8 minutes; the calculation time period is mainly the oxygen blowing time period, and the highest temperature also occurs within this time period.

[0198] The stable condition refers to the period between the start and end of the oxygen-blowing stage of a furnace heat, excluding the starting and ending points, because the flue gas composition changes significantly at these two endpoints.

[0199] Sampling was continuously recorded for 72 hours. Using the single-point parameters in the oxygen-blowing section (data obtained by sampling once per minute during the oxygen-blowing period of each furnace heat), the heat transfer coefficient was calculated through the heat transfer coefficient calculation formula. At the same time, the outlet temperature was calculated, and by comparing the calculated outlet temperature with the actual outlet temperature, the accuracy of the heat transfer coefficient could be verified.

[0200] Table 4 Data table of the inlet and outlet flue gas temperatures, inlet and outlet water temperatures, and flue gas outlet air volume of the dust collector

[0201]

[0202] Table 5 Actual heat transfer coefficient K 1 Data table used in the calculation

[0203] Heat treatment batch 1 2 3 4 Average flue gas volume 66391 66387 62249 62775 Average inlet temperature 541 570 538 560 Average outlet temperature 276 283 327 301 Average temperature difference between outlet and inlet 12.3 10.6 12.8 10.9 Average inlet water temperature 111.1 114.7 118.7 120.8 Average outlet water temperature 123.4 125.3 131.4 131.7 Maximum temperature difference 429.9 455.3 419.3 439.2 Minimum temperature difference 152.6 157.7 195.6 169.3 Average temperature difference 267.7 280.7 293.4 283.1 Heat transfer area 242.4 242.4 242.4 242.4 Heat dissipation loss 285019 285019 285019 285019 Inlet air heat 27015494 28582923 25177853 26516160 Exhaust heat 13286167 13631575 14822421 13731717 Heat transfer amount 13444308 14666329 10070413 12499424 <![CDATA[Heat transfer coefficient K 1 > 0.0576 0.0599 0.0393 0.0506

[0204] In this embodiment, the flue gas outlet of 1 converter enters 2 dust collectors.

[0205] Total flue gas volume (Table 6) = 1 / 2 average flue gas volume (Table 5).

[0206] Through the test results of 72 hours, that is, 3 consecutive days, regression analysis calculation of the heat transfer coefficient was carried out through the highest temperature point (average value of 3 points) to obtain the quantitative values of M, B, C, D, and E.

[0207] Thus, the heat transfer coefficient calculation formula is obtained as:

[0208] K = -0.08536 + 3.86122×10 -6 V - 4.30659×10 -5 P

[0209] + 0.00387×10 -11 (T 1 + 273.15) 4 - 6.64177×10 -4 Δt w ;

[0210] In the formula,

[0211] K—the heat transfer coefficient, kw / m 2 ·℃;

[0212] V—the flue gas flow rate, Nm 3 / h;

[0213] P—the flue gas inlet pressure, Pa;

[0214] T 1 — Flue gas inlet temperature, °C;

[0215] Δt w — Temperature difference between outlet and inlet water, Δt w = t 2 - t 1 where t 2 — Outlet water temperature, t 1 — Inlet water temperature, °C.

[0216] Furthermore, this embodiment also provides a method for verifying the calculated heat transfer coefficient calculation formula. By using the iterative calculation method, it includes the following steps:

[0217] Step 501) Assume the flue gas outlet temperature;

[0218] Step 502) Obtain the heat transfer coefficient K according to the heat transfer coefficient calculation formula, and then obtain the heat transfer amount through the heat transfer amount calculation formula;

[0219] Step 503) According to the flue gas inlet temperature and the composition of the flue gas, look up the corresponding enthalpy value in the enthalpy-temperature table and calculate the total heat of the flue gas inlet;

[0220] Step 504) Subtract the heat transfer amount and the heat dissipation amount from the total heat of the flue gas inlet to obtain the assumed total heat of the flue gas outlet;

[0221] Step 505) Use the interpolation method through the enthalpy-temperature table to calculate the calculated flue gas outlet temperature from the assumed total heat of the flue gas outlet obtained in Step 504;

[0222] Step 506) Compare the assumed flue gas outlet temperature with the calculated flue gas outlet temperature;

[0223] If the error is less than 0.5%, it is considered qualified;

[0224] Otherwise, re-assume the flue gas outlet temperature and continue the iterative calculation until convergence is qualified, so as to obtain the calculated flue gas outlet temperature.

[0225] Step 507) Compare the calculated flue gas outlet temperature with the actual flue gas outlet temperature to obtain the calculation error.

[0226] The assumption is the initial step of the iterative calculation, which is to assign a value. Then, based on this assumed value, the result is deduced. The result is compared with the assumed value. If it is within the error range, it indicates that the assumption is correct, proving that the error of the result calculated by this formula is within the allowable range and can be applied in practice. The relevant calculation data is shown in Table 6.

[0227] Table 6 Relevant data table for calculating the heat transfer coefficient K and the outlet temperature

[0228] Heat treatment batch 1 2 3 4 <![CDATA[(T 1 + 273.15) 4 > 4.39357E+11 5.05382E+11 4.32917E+11 4.81829E+11 Total flue gas volume 33196 33194 31125 31388 Flue gas inlet pressure 8.1 9.55 8.39 2.61 Heat transfer coefficient K 0.0513 0.0549 0.0427 0.0471 Assumed outlet temperature 294 298 315 312 Maximum temperature difference 429.9 455.3 419.3 439.2 Minimum temperature difference 170.6 172.7 183.6 180.3 Average temperature difference △T 280.6 291.5 285.4 290.8 Heat transfer amount 12561461 13965163 10634497 11952271 Flue gas outlet heat 14169014 14332741 14258337 14278870 Calculated flue gas enthalpy 427 432 458 455 Calculated outlet temperature 294 297.3 314.4 312.4 Error of assumed outlet temperature 0％ 0.24％ 0.19％ -0.13％ Judgment Qualified Qualified Qualified Qualified Error of calculated outlet temperature 6.5％ 5.3％ -3.7％ 3.7％

[0229] Among them, assume that the outlet temperature error is the error value between the assumed outlet temperature and the calculated outlet temperature; the calculated outlet temperature error is the error value between the calculated outlet temperature and the actual outlet temperature.

[0230] Since the error between the assumed outlet temperature and the calculated outlet temperature is very small, the assumed outlet temperature corresponding to the convergence calculation result can also be directly used as the calculated outlet temperature result.

[0231] To better verify the accuracy of the heat transfer coefficient, a single furnace is selected from the continuous working converter conditions for 72 hours for verification calculation, as shown in Table 7 and Figure 2 as follows:

[0232] Table 7 Data Table for Outlet Temperature Calculation

[0233] Time min 1 2 3 4 5 6 7 8 Flue gas inlet pressure Pa 6.08 6.94 7.81 7.81 9.55 16.49 15.63 5.21 Inlet water temperature ℃ 111.11 111.11 111.11 111.11 111.11 111.11 111.11 112.15 Outlet water temperature ℃ 123.78 123.78 123.78 123.78 123.78 123.78 123.78 123.78 Temperature difference between outlet and inlet water ℃ 12.67 12.67 12.67 12.67 12.67 12.67 12.67 11.63 Actual inlet temperature ℃ 546.53 536.11 527.78 521.18 517.01 510.42 510.07 493.75 Actual outlet temperature ℃ 278.47 293.4 302.08 311.11 320.14 326.04 329.86 345.83 Calculated heat transfer area m2 242.4 242.4 242.4 242.4 242.4 242.4 242.4 242.4 Calculated heat transfer coefficient <![CDATA[kw / m 2 ·℃]]> 0.0566 0.0513 0.0393 0.0383 0.0373 0.0339 0.0298 0.0204 Calculated outlet temperature ℃ 283 285 315.7 313.7 314.4 320.9 334 356.9 Error of outlet temperature ％ 1.6 -2.9 4.3 0.8 -1.8 -1.6 1.2 3.1

[0234] For the test conditions of 8 consecutive time intervals during the normal operation of a furnace, the time interval is 1 minute. The outlet temperature is calculated based on the heat transfer coefficient calculated by the heat transfer coefficient calculation method of the present invention. The accuracy of the calculation result is high, and the maximum error is less than ±5%, which is 4.3%.

[0235] Figure 3 It shows that the highest temperature at the flue gas outlet of a single furnace of a continuously operating converter, compared with the calculation result based on the heat transfer coefficient calculation method of the present invention, has a high degree of accuracy.

[0236] Figure 4 It shows that the proportion of the calculation error range of ±5% is 72.3%, the proportion of the calculation error range of ±10% is 88.1%, and the maximum error of all furnace calculations is 16.4%.

[0237] The above data can show that the heat transfer coefficient calculation formula obtained by using the calculation method of this embodiment can accurately predict the outlet temperature of the cyclone dust collector with a heat exchange device under continuous and stable operating conditions within the allowable error range, so as to guide the design of the cyclone dust collector with a heat exchange device.

[0238] The heat transfer coefficient calculated based on the heat transfer coefficient calculation method of the cyclone dust collector with a heat exchange device provided in this application can be used to calculate the flue gas outlet temperature, heat transfer amount, and water-side flow rate, and can guide the structural design of the cyclone dust collector and the layout of the heat transfer area of the heat exchange device.

[0239] Exemplary embodiments are not intended to limit the present application, and the scope of protection of the present application is defined by the claims. Those skilled in the art can make various modifications or equivalent replacements within the essence and scope of protection of the present application, and such modifications or equivalent replacements should also be regarded as falling within the scope of protection of the present application.

Claims

1. A method for calculating the heat transfer coefficient of a cyclone dust collector with a heat exchange device, characterized in that: The following steps are involved: Step 001, determining relevant parameters affecting the heat transfer coefficient; Including flue gas flow, flue gas inlet pressure, flue gas inlet temperature and inlet and outlet water temperature difference; Step 002, using the parameters described in step 001, based on regression analysis, the heat transfer coefficient calculation formula is assumed to be: K=M+BV+CP+D(T1+273.15) 4 +EΔt w ; In the formula, K—heat transfer coefficient, kw / m 2 ℃; V—smoke flow, Nm 3 / h; P—flue gas inlet pressure, Pa; (T1+273.15) 4 — regression parameters; T1—flue gas inlet temperature, °C; Δt w —Inlet and outlet water temperature difference, Δt w =t2-t1, t2—outlet water temperature, t1—inlet water temperature, ℃; M, B, C, D, and E are constants; Step 003, using the heat transfer calculation formula, the actual heat transfer coefficient K1 is deduced from the actual heat transfer value; Among them, the actual heat transfer is calculated by the smoke composition and inlet and outlet temperatures; The heat transfer calculation formula is: Q = 3600K1AΔT; In the formula, Q—heat transfer, kJ; K1—heat transfer coefficient, kw / m 2 ℃; A—heat transfer calculation area, m 2 ; ΔT—average temperature and pressure, °C; Step 004, repeat the steps described in step 003, calculate the multiple groups of actual heat transfer coefficients K1, and calculate the specific values ​​of M, B, C, D, and E in the heat transfer coefficient calculation formula described in step 002 through regression analysis calculation method, and derive the final heat transfer coefficient calculation formula.

2. The method for calculating the heat transfer coefficient of a cyclone dust collector with a heat exchange device according to claim 1, characterized in that: In step 003, the actual heat transfer is the total heat of the flue gas inlet minus the total heat of the flue gas outlet minus the heat dissipation; According to the measured flue gas inlet temperature and the flue gas composition, the corresponding enthalpy value in the enthalpy-temperature table is consulted to calculate the total heat of the flue gas inlet; According to the measured flue gas outlet temperature and flue gas composition, the corresponding enthalpy value in the enthalpy-temperature table is consulted to calculate the total heat of the flue gas outlet; Heat dissipation includes convection heat transfer and radiation heat transfer.

3. The method for calculating the heat transfer coefficient of a cyclone dust collector with a heat exchange device according to claim 2, characterized in that: The convective heat transfer is calculated using Newton's cooling formula, which is: Φ1=hA1Δt; In the formula, h—Surface heat transfer coefficient, w / m 2 K; A1—External surface heat transfer area, m 2 ; Δt—average temperature difference, Δt=T3-T4, K; T3—Cyclone dust collector external surface temperature, K; T4—air temperature, K; The radiation heat transfer adopts the Stefan-Boltzmann formula: Φ2=εA1σ(T3 4 -T4 4 ); In the formula, ε—external surface emissivity, ε is assumed to be 0.9; A1—External surface heat transfer area, m 2 ; σ—blackbody radiation constant, 5.67E-08, w / (m 2 ·K 4 ); T3—Cyclone dust collector external surface temperature, K; T4—Air temperature, K.

4. The method for calculating the heat transfer coefficient of a cyclone dust collector with a heat exchange device according to claim 3, characterized in that: In the process of calculating multiple groups of actual heat transfer coefficients K1, the same heat dissipation is used.

5. The method for calculating the heat transfer coefficient of a cyclone dust collector with a heat exchange device according to claim 1 or 4, characterized in that: In step 003, the calculation formula for the heat transfer calculation area A is: A=S F +S T +S TX +2 / 3(S Z +S ZX ); In the formula, A—heat transfer calculation area, m 2 ; S F —Inner surface area of ​​the head (1), excluding openings, m 2 ; S T —Inner surface area of ​​cylinder (3), m 2 ; S TX —Surface area of ​​heat exchange tubes of cylinder heat exchange device (4), m 2 ; S Z —Inner surface area of ​​cone (5), m 2 ; S ZX —Surface area of ​​heat exchange tubes of conical tube heat exchange device (6), m 2 .

6. The method for calculating the heat transfer coefficient of a cyclone dust collector with a heat exchange device according to claim 5, characterized in that: In step 003, the average temperature and pressure ΔT is calculated by the formula: In the formula, ΔT—average temperature and pressure, °C; Δt1—maximum temperature difference, Δt1=T2-t1, °C; Δt2—minimum temperature difference, Δt2=T1-t2, °C; t1—water inlet temperature, °C; t2—outlet water temperature, °C; T1—flue gas inlet temperature, °C; T2—Flue gas outlet temperature, °C.

7. The method for calculating the heat transfer coefficient of a cyclone dust collector with a heat exchange device according to claim 6, characterized in that: In step 004, after the converter operating conditions are stabilized, the flue gas inlet and outlet temperatures at multiple sampling time points are determined, and the actual heat transfer coefficient K1 at multiple sampling time points is calculated according to the method of step 003; Then, regression analysis and calculation are performed on multiple groups of actual heat transfer coefficients K1, and the heat transfer coefficient calculation formula is obtained as follows: K=-0.08536+3.86122×10 -6 V-4.30659×10 -5 P +0.00387×10 -11 (T1+273.15) 4 -6.64177×10 -4 Δt w ; In the formula, K—heat transfer coefficient, kw / m 2 ℃; V—smoke flow, Nm 3 / h; P—flue gas inlet pressure, Pa; T1—flue gas inlet temperature, °C; Δt w —Inlet and outlet water temperature difference, Δt w =t2-t1, t2—outlet water temperature, t1—inlet water temperature, ℃.

8. The method for calculating the heat transfer coefficient of a cyclone dust collector with a heat exchange device according to claim 7, characterized in that: The heat transfer coefficient calculation formula is verified as follows: Step 501) Assume the flue gas outlet temperature; Step 502) obtaining the heat transfer coefficient K according to the heat transfer coefficient calculation formula, and then obtaining the heat transfer amount by the heat transfer calculation formula; Step 503) According to the smoke inlet temperature and the smoke composition, the corresponding enthalpy value in the enthalpy-temperature table is consulted to calculate the total heat of the smoke inlet; Step 504) The total heat of the flue gas inlet minus the heat transfer and heat dissipation to obtain the total heat of the flue gas outlet; Step 505) The total heat of the assumed flue gas outlet obtained in step 504) is calculated by using an enthalpy-temperature table and an insertion method to obtain the calculated flue gas outlet temperature; Step 506) comparing the assumed flue gas outlet temperature with the calculated flue gas outlet temperature; If the error is less than 0.5%, it is qualified. Otherwise, the flue gas outlet temperature is re-assumed and the iterative calculation is continued until convergence is qualified, thereby obtaining the calculated flue gas outlet temperature. Step 507) Compare the calculated flue gas outlet temperature with the actual flue gas outlet temperature to obtain a calculation error.

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