本文選題：直接空冷凝汽器　切入點：軸流風(fēng)機群　出處：《華北電力大學(xué)》2014年博士論文　論文類型：學(xué)位論文

【摘要】：近年來,空冷技術(shù)在我國北方火力發(fā)電中得到了大力的發(fā)展。環(huán)境因素與火電直接空冷機組的耦合比較復(fù)雜,環(huán)境風(fēng)速與風(fēng)向、環(huán)境溫度以及軸流冷卻風(fēng)機的性能等因素都對火電直接空冷機組性能產(chǎn)生影響,并且受軸流風(fēng)機群運行中的群抽效應(yīng)和環(huán)境風(fēng)影響下的熱風(fēng)回流的耦合影響,軸流風(fēng)機群外圍的空冷凝汽器單元受環(huán)境風(fēng)影響大。 在四臺聯(lián)建火電直接空冷機組上進行了春、夏與秋三個季節(jié)不同工況下的機組熱力性能實驗,并在夏季主導(dǎo)風(fēng)向下,基于兩臺聯(lián)建火電直接空冷機組的軸流風(fēng)機群分區(qū)調(diào)節(jié)的基礎(chǔ)上,進行了不同工況下的機組熱力性能實驗。然后建立火電直接空冷機組性能的灰關(guān)聯(lián)度模型,定量分析火電直接空冷機組自身運行實驗變量與環(huán)境條件以及軸流風(fēng)機群各風(fēng)機的性能對火電直接空冷系統(tǒng)性能的影響,并基于上述兩個熱力性能實驗數(shù)據(jù),分別應(yīng)用神經(jīng)網(wǎng)絡(luò)(ANN)與最小二乘支持向量機(LS-SVM)等算法,建立汽輪機背壓預(yù)測模型。接著,在選定的基準工況下應(yīng)用火電直接空冷機組汽輪機背壓LS-SVM預(yù)測模型,分析出處于夏季主導(dǎo)風(fēng)向下的軸流風(fēng)機群不同分區(qū)風(fēng)機轉(zhuǎn)速降低和升高對環(huán)境風(fēng)下游與上游火電直接空冷機組抵御環(huán)境風(fēng)影響的作用規(guī)律。建立由太陽輻射引起的直接空冷系統(tǒng)附加熱負荷計算模型,對太陽輻射影響空冷凝汽器熱負荷的程度進行分析。 基于火電直接空冷機組熱力性能實驗數(shù)據(jù),應(yīng)用建立的火電直接空冷機組性能灰關(guān)聯(lián)度模型進行分析,結(jié)果顯示出,文中選定的機組自身運行與環(huán)境實驗變量對火電直接空冷機組的性能影響不同,并且處于不同位置的軸流冷卻風(fēng)機的性能對火電直接空冷機組性能的影響也不同,處于外圍的軸流冷卻風(fēng)機的性能對火電直接空冷機組性能的影響最強烈。 以北方地區(qū)某135MW火電直接空冷機組凝汽器的全年太陽輻射量為主線,假定汽輪機排汽量不變,環(huán)境溫度為月平均日溫度,揭示出由太陽輻射引起的月平均附加熱負荷在1-5月期間升高,5月時達到最大值,為371.75kW,而后逐步降低,與日照時數(shù)的變化趨勢基本一致。假定方位角為零時,凝汽器由太陽輻射引起的月平均附加熱負荷增加而導(dǎo)致汽輪機背壓升高,1-7月間汽輪機背壓變化增加,7月時達到最大值,為0.2097kPa,8-12月相應(yīng)的影響會減弱,與環(huán)境溫度的變化趨勢大致相同,并且由太陽輻射引起的直接空冷系統(tǒng)附加熱負荷平均占空冷凝汽器總熱負荷的0.134%。 基于LM-BP算法,建立火電直接空冷機組的汽輪機背壓ANN預(yù)測模型,其預(yù)測值與汽輪機背壓的真實值基本一致,模型的平均相對誤差,MRE,為9.27%；平均均方差,RMSE,為1.827kPa；絕對變異分數(shù),R2,為0.9859。為檢測模型的魯棒性與可靠性,分別將空冷凝汽器的環(huán)境輸入變量,如自然環(huán)境風(fēng)速、自然環(huán)境風(fēng)向、空冷島擋風(fēng)墻上環(huán)境風(fēng)速和空冷島擋風(fēng)墻上環(huán)境風(fēng)向等參數(shù),加入±5%的隨機波動后,輸入到模型中,其MRE分別為14.57%,12.21%,11.22%和11.16%,RMSE分別為2.773,2.130,1.844和1.895kPa,R2分別為0.9641,0.9779,0.9836和0.9824,說明模型的穩(wěn)定性很好,數(shù)據(jù)波動產(chǎn)生的相對誤差能得到有效的抑制。 針對夏季主導(dǎo)風(fēng)向下的兩臺聯(lián)建火電直接空冷機組,分別建立相應(yīng)的汽輪機背壓LS-SVM預(yù)測模型,討論軸流風(fēng)機群不同分區(qū)風(fēng)機轉(zhuǎn)速降低與升高時,軸流風(fēng)機群環(huán)境風(fēng)下游與上游火電直接空冷機組汽輪機背壓的變化規(guī)律：(1)軸流風(fēng)機群不同分區(qū)的軸流冷卻風(fēng)機轉(zhuǎn)速發(fā)生變化時,汽輪機背壓變化明顯不同；(2)改變其中一臺機組軸流冷卻風(fēng)機的轉(zhuǎn)速,也會對另一臺機組的汽輪機背壓產(chǎn)生影響；(3)單純提高軸流冷卻風(fēng)機轉(zhuǎn)速并非總能夠起到降低機組汽輪機背壓的效果,適當降低受熱風(fēng)回流影響較大分區(qū)的軸流冷卻風(fēng)機轉(zhuǎn)速,反而可以起到降低軸流風(fēng)機群環(huán)境風(fēng)下游機組汽輪機背壓的作用,并且軸流風(fēng)機群環(huán)境風(fēng)上游機組汽輪機背壓也不會升高。
[Abstract]:In recent years, air cooling technology has been developed vigorously in the north of China's thermal power plants. The coupling of direct air cooling unit of environmental factors and the power is more complex, the environment of wind speed and wind direction, the ambient temperature and the axial cooling fan performance and other factors of the direct air cooling unit of thermal power can affect the coupling effect of hot air reflux and axial flow fan cluster in the operation group pumping effect and environmental wind under the influence of the axial flow fan cluster outside condenser unit by environmental wind influence.
The spring in four the construction of thermal power direct air cooling unit, summer and autumn three seasons under different conditions of the thermal performance of the unit test, and in the summer the dominant wind direction, based on the construction of two units of power direct air cooling unit axial flow fan cluster partition adjustment on the thermodynamic performance experiments under different conditions the grey correlation model. Then establish the power performance of direct air cooling unit, quantitative analysis of the influence of thermal performance of direct air-cooled unit operation and environmental conditions as well as the experimental variable axial flow fan cluster the fan on the performance of the power of the direct air cooling system, and based on the two thermal performance experimental data were used to neural network (ANN) and least squares support vector machine (LS-SVM) algorithm, the establishment of the steam turbine back pressure prediction model. Then, using the power of direct air-cooled unit steam turbine back pressure LS-SVM in the benchmark under the selected conditions Prediction model, analysis of provenance in the summer the dominant wind direction under different axial flow fan cluster partition fan speed decreased and increased effect of wind withstand environmental impact on the environment downstream and upstream wind power direct air cooling unit. Calculation model of direct air cooling system of heating load caused by solar radiation, the solar radiation influence space the condenser heat load is analyzed.
The power of direct air-cooled unit thermal performance based on experimental data were analyzed using the established power direct air cooling unit properties of grey correlation model, results show that the performance of the selected unit operation and environment experimental variables on the thermal power of direct air cooling units and different effects in the performance flow cooling fan in different positions the axial thermal effect of direct air cooling unit performance is different, in the performance of the cooling fan shaft of the thermal effect of the periphery of the direct air cooling unit performance most strongly.
In the northern region of a 135MW power direct air cooling condenser of the annual amount of solar radiation as the main line, assuming that steam turbine exhaust quantity, ambient temperature for monthly average daily temperature, revealing the radiation caused by the sun's monthly average of the heating load increased in 1-5 during the month of May, reached the maximum value is 371.75kW, then sunshine and gradually reduce the trend change is consistent. We assume that the azimuth angle is zero, the condenser from solar radiation caused by the monthly average of the heating load increase caused by steam turbine back pressure, increase the steam pressure change in 1-7 months, in July reached the maximum value for 0.2097kPa, 8-12 month corresponding effect will be weakened. Roughly the same as the trend of environmental temperature, radiation and direct air cooling system of heating load caused by the average duty total heat load of condenser 0.134%. by the sun
Based on the LM-BP algorithm, the power of direct air cooling unit of steam turbine back pressure ANN prediction model, the prediction value and the real value of the steam turbine back pressure is basically the same, the average relative error of the model, MRE, 9.27%; average variance, RMSE, 1.827kPa; the absolute variation fraction, R2, robustness and reliability of 0.9859. detection model the environmental input variables are the condenser, such as natural environment, natural environment of wind direction, wind speed, air cooling island wind wall wind and air cooling island wind wall environment, wind direction and other parameters, random fluctuations add + 5%, input to the model, the MRE were 14.57%, 12.21%, 11.22% and 11.16% RMSE, 2.773,2.130,1.844 and 1.895kPa respectively, R2 0.9641,0.9779,0.9836 and 0.9824 respectively, indicating the stability of the model is very good, the relative error data fluctuation can be effectively suppressed.
In summer two the construction of leading power direct air cooling unit under the wind direction, establish the corresponding steam turbine back pressure LS-SVM prediction model, the discussion of axial flow fan cluster in different zones of fan speed and reduce the rise, variation of axial flow fan cluster environment downstream wind and upstream power direct air cooling unit steam turbine back pressure: (1). Axial flow fan cluster partition of different flow cooling fan speed change when the steam pressure changes were significantly different; (2) the change of one unit of axial cooling fan speed, but also the other units of the steam turbine back pressure generating effect; (3) improve speed of the machine is not always able to play to reduce the effect of back pressure steam turbine axial flow cooling fan, appropriate to reduce the influence of hot air recirculation by the partition of the axial cooling fan speed, it can reduce the axial flow fan cluster environment wind downstream unit steam turbine backpressure It does not increase the back pressure of the steam turbine in the axial-flow wind turbine group.

【學(xué)位授予單位】：華北電力大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TM611

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