300MW机组发电厂78号低加疏水泵热经济对比

本文格式为Word版，下载可任意编辑——300MW机组发电厂78号低加疏水泵热经济对比摘要

本论文主要针对300MW机组发电厂的原则性热力系统，对回热加热系统中7号、8号加热器分别设置疏水泵，通过计算分析两种回热系统的热经济性。通过设计了解、学习电厂热力系统规划、设计的一般途径和方案论证、优选的原则；学会全面性热力系统计算和发电厂主要热经济指标计算的内容、方法。本次我们要解决的问题主要是对疏水泵的选型以及加在不同位置的热经济性和技术要求的对比，选出何时的优化原则。这次设计能使我全面的了解热力发电厂的系统图，熟悉疏水泵在电厂中的应用以及电厂的优化的经济性，了解发电厂的热经济性指标，使发电厂高效、安全的运行。

h，kj/kg2′3540537t3.6633950′2″1.68p435t333330.82p337431320.327p230529260.13567143t27630.074p26630.026p282780.00542349C16.7p0537t5.93p385t131403.66p321t23035

热力过程线

4

各计算点的汽水参数单项目名称汽水位参数H4H5H60.135143276360.127106.388446.0453H70.07491.326636H80.026X=0.96C0.0054X=0.91回抽汽压热力Pj抽抽汽温汽度tj抽汽焓hj抽汽压损△pj加热器压力MPa5.933.661.680.820.327℃384.8321.1435336.8230kJ/31403035333331322926㎏%66660.774169.024714.99160.306134.196564.324025272349634.194143.22MPa5.573.441.645241.553207.080.06960.02489.79563.991376.0763267.8543加热器℃270.内饱和618水温tsj加热器内饱和水焓被加热器加的上端热差θt水加热器的下端差θtw加热器出口水温twj加热器出口水焓hwj加热器进口水温twj＋1加热器进口水焓hwi＋1疏加热器水疏水温度kJ/11871044864.㎏.887.632662℃000℃1.6700000.220.220.22℃270.618241.553207.08169.024714.991134.196564.324106.388103.38886.79560.991kJ/11871044864.㎏.887.632662℃241.553207.08174.91433.04363.46255.3589.79563.99134.194kJ/1044864.㎏.632662740.791446.045376.076267.854149.50℃243.223207.08864.662174.91752.575

103.608434.4590.015364.21134.414加热器kJ/1052疏水焓㎏.82376.94268.81114.161.2．2锅炉连续排污利用系数的计算

连续排污利用系统的汽水参数列于下表项目锅炉排污水扩容蒸汽扩容器排污水锅炉的蒸发量

Db?D0?D1?D0?0.01Db?1.0101D0，即?b=1.0101

汽水参数P（MPa）20.40.900.90T（℃）367.44175175H（kJ/㎏）1849.92773742.6汽水损失

D1?0.1Db?0.0101D0即?s=0.0101

锅炉排污量

Db1?0.01Db?0.0101D0即?b1=0.0101

锅炉给水量

Dfw?Db?Db1??0.0101?1.0101?D0?1.0202D0,即?fw=1.0202小汽轮机的用汽量

Dtd=34.988kJ/㎏Db=1025kJ/㎏D0=1014.75kJ/㎏Dtd=34.988/1014.75Do=0.03448即?t=0.03448扩容器产生的扩容蒸汽份额?f扩容器的物质平衡式?b1??f??b1

'扩容器的热平衡式?b1hb?f??fh''f??b'1h'fkJ/㎏1'两式联立求解的?f?hb'1?f?h'fh''f?h'f?b1

=0.0101×(1849.9×0.98-742.6)÷(2773-742.6)=0.00532

'未扩容的排污水份额?b1??b1??f=0.00478

化学补充水份额?ma

?ma??1??b'1=0.0101+0.00478=0.01488

6

1.3、各级加热器的计算1.3.1、H1的计算

热平衡式ɑ1（h1-hs1)?r=ɑfw(hw1-hw2)

α(h-h)ɑ1=fww1w2

?h1-hs1?ηr?fw1hw?1h1hw2=

1.0202??1187.887?1044.632?0.99??3140?1052.82?hs1=0.070731.3.2、H2的计算

热平衡式

{?sg1（hsg1-hs2）+?2（h2-hs2）+?1（hs1-hs2）}?r=?fw(hw2-hw3)

?2??2??fw(hw2-hw3)-??h-h?h-h?????sg1?sg1s2??s1s2?1?r?r?h2-hs2?

?2h2?sg1hsg11.0202??1044.632?864.662????0.004429??3394.45?887.70??0.07073??1052.82?887.70????0.99?3035?887.70??0.99=0.07576hw2hw3?1hs1???????h12sg1s21.3.3、H3的计算{ɑsg2（hsg2-hs3）+ɑ3（h3-hs3）+（ɑ1+ɑ2+ɑsg1）（hs2-hs3）}?r=ɑfw（hw3-hw4）

?3??3??fw?hw3-hw4?-??sg2?hsg2-hs3???1??2??sg1?hs2-hs3???r????h3-hs3??r?3333?752.57??0.99?

1.0202??864.662?714.991????0.004053??3535.66?752.57???0.07576?0.07073?0.004429??887.70?752.57????0.99?3=0.03720

1.3.4、H4的计算

物质平衡式

hw3?3h3?h?sg2hsg2hw4????12??sg1?hs2????????123sg1??sg2?hs3?c4=?fw-?1-?2-?3-?4-?f

=1.0202-0.07073-0.07576-0.03720-0.0232-?4

?c4+?4=0.83119

热平衡式

ɑ4h4ηc+（ɑ1+ɑ2+ɑ3+ɑsg1+ɑsg2）hs3+ɑc4hw5+ɑfhf+ɑsg3hsg3ηc=?fwhDH

7

?4×3132×0.985+0.985×0.013233×3028.44+?c4×564.324+0.00532×

2773+（0.07073+0.07576+0.03720+0.004299+0.004053）×752.57=1.0202×714.991

联立两式的?4=0.02441?c4=0.80678

?sg3hsg3?fhf?4h4????12??3??sg1??sg2?hs?c4hw51.3.5、H5的计算

?5（h5-hs5)?r=?c4(hw5-hw6)?5（2926-434.45）×0.99=0.80678×（564.324-446.045）?5=0.03869

?fw?5h5hw5?5hs5hw61.3.6、H6的计算

{?6（h6-hs6）+?5（hs5-hs6）}?r=

（?c4-?5-?6-?7）(hw6-hw7)+（?5-?6-?7）(hw6-hws7)

2267.5494?6-94.65?7=57.59495①

?6h6

1.3.7、H7的计算

hw6?5hs5hw7??5??6?hs6??5??6??7?hs7{?7（h7-hs7）+（?5+?6）（hs6-hs7）}?r=（?c4-?5-?6-?7）(hw7-hw8)2478.3581?7+215.1587?6=78.8964957②有①、②两式的?6=0.02663?7=0.02952

hw7?7h7??c4??5??6??7?hw8??5??6??7?hs7??5??6?hs61.3.8、H8的计算

?8（h8-hs8)?r=（?c4-?5-?6-?7）(hw8-hsg)

8

（2527-142.48）×0.99×?8=0.71194×（255.35-hsg）③

hw8?8h8??c4??5??6??7?hw8?8hs8?hs1.3.9、轴封加热器的计算

?sg4（hsg4-hs）=（?c4-?5-?6-?7）（hsg-hc+1.7）

hsg=149.5

解得③式的

hsg?sg4hsg4??c4??5??6??7?hc?8=0.03192

1.3．10、凝汽份额的计算

?sg4hssg4

α

=1-α1-α2-α3-α4-α5-α6-α7-α8-αt-α

=0.60751

c

sg1-

α

sg2-

α

sg3-

α

1.4、汽轮机汽耗量及各段抽汽量计算1.4.1、抽汽做功不足系数计算

根据已知参数，可以查水蒸汽表得到hrh=3035kJ/kg，hrh=3540kJ/kg，所以qrh=3540-3035=505kJ/kg

h0-hc+qrh=（3395-2349+505）kJ/kg=1551kJ/kgY1=

in

outh1?hc?qrh=(3140-2349+505)/1551=0.8356

h0?hc?qrhh2?hc?qrh=(3035-2349+505)/1551=0.7679

h0?hc?qrhh3?hc=(3333-2349)/1551=0.6344

h0?hc?qrhY2=

Y3=

h4?hcY4=Yt==(3132-2349)/1551=0.5048

h0?hc?qrhY5=

h5?hc=(2926-2349)/1551=0.3720

h0?hc?qrhh6?hc=(2763-2349)/1551=0.2669

h0?hc?qrhY6=

9

Y7=

h7?hc=(2663-2349)/1551=0.2025

h0?hc?qrhh8?hc=(2527-2349)/1551=0.1148

h0?hc?qrhhsg1?hc?qrhh0?hc?qrhhsg2?hch0?hc?qrhhsg3?hch0?hc?qrhhsg4?hch0?hc?qrh=(3394.45-2349+505)/1551=0.9996

Y8=

Ysg1=

Ysg2==(3535.66-2349)/1551=0.7651

Ysg3==(3028.44-2349)/1551=0.4381

Ysg4==(2716-2349)/1551=0.2366

各抽汽份额αj及其做功不足系数Yj的乘积αjYj见表2

1.4.2、汽轮机的汽耗量及各段抽汽量的计算

机组无回热纯凝汽工况时的汽耗量Dc0为

Dc0=3600Pe/(h0-hc+qrh)?mg=3600×3×100000/(1551×0.983)=708367.194kg/h机组有回热时的汽耗量D0为

D0=Dc0/(1-??j)==708367.194/0.78458=902861.65kg/h表2αj、Yj和Dj

αjYjY1=0.8356Y2=0.7679Y3=0.6344Y4=0.5048Y5=0.3720Y6=0.2669Y7=0.2025Y8=0.1148Ysg1=0.9996Ysg2=0.7651Ysg3=0.4381Ysg4=0.2366Yt=0.5048αjYj0.059100.058180.023600.012320.014390.007110.005980.003660.004430.003100.005800.000340.01741Dj=αjD0/（kg/h）D1=63859.40D2=68400.80D3=33586.45D4=22038.85D5=34931.72D6=24043.21D7=26652.48D8=28819.34Dsg1=3998.77Dsg2=3659.30Dsg3=11947.57Dsg4=1291.09Dt=31130.67α1=0.07073α2=0.07576α3=0.03720α4=0.02441α5=0.03869α6=0.02663α7=0.02952α8=0.03192ααααsg1=sg2=sg3=sg4=0.0044290.0040530.0132330.001430αt=0.0344810

??j=0.39794??Y=0.21542jj?Dj=354359.65αc=1-??j=0.60206

项目全厂汽水损失锅炉排污扩容蒸汽浓缩排污水化学补充水小汽轮机用汽锅炉蒸发量再热蒸汽量锅炉给水量1-??jYj=0.78458份额αxα1=0.0101αb1=DC=αcD0=548497.48流量Dx=α（kg/h）D1=9118.90Db1=9118.90Df=4803.22D'b1=4315.68Dma=13434.58Dt=31130.67Db=911980.55Drh=770601.45Dfw=921099.46x0D/0.0101αf=0.00532α'b1=0.00478αma=0.01488αt=0.03448αb=1.0101ααrh=fw=1-α1-α2=0.853511.02021.5、汽轮机的功率校核P1=

D（1h0?h1)?m?g3600D（2h0?h2)?m?g3600=4446.48kW

P2==6723.80kW

P3=

D（3h0?h3?qrh)?m?g3600D（4h0?h4?qrh)?m?g3600D（5h0?h5?qrh)?m?g3600D（6h0?h6?qrh)?m?g3600D（7h0?h7?qrh)?m?g3600D（8h0?h8?qrh)?m?g3600=5199.94kW

P4==4675.85kW

P5==9290.30kW

P6==7464.56kW

P7==9002.40kW

P8==10804.52kW

11

Pt=

D（th0?h4?qrh)?m?g3600D（ch0?hc?qrh)?m?g3600=6528.31kW

Pc==232293.71kW

汽轮机的总功率Pe=（Pc+Pt+计算误差

Δ=

?P）=296429.87kW

jj=1?Pe?Pe，Pe?100%=1.19%

计算的电功率接近给定的电功率，说明计算结果确凿。

1.6、热经济指标计算

1.6.1、汽轮机组热耗量(含小汽轮机)

Q0?D0(h0?hfw)?Drhqrh?Df(h''f?hfw)?Dma(hfw?hw)

=902861.65×(3395-1187.887)+770601.45×505+4803.22×(2773-1187.887)-13434.58×(1187.887-143.22)=2375450401kJ/h

1.6.2、汽轮机组热耗率

q0=Q0/Pe=2375450401/300000=7918.17kJ/(kw·h)

1.6.3锅炉热负荷

Qb?Db(hb?hfw)?Drhqrh?Dbl(hbl?hfw)

×(3395-1187.887)+770601.45×505+9118.90×(1849.9-1187.887)

=2408034690kJ/h

1.6.4、各种效率

管道效率

ηp=Q0/Qb=2375450401/2408034690=98.6%

机组热效率

ηe=3600/q0=3600/7918.17=45.47%

全厂热效率

ηcp=ηbηpηe=0.91?0.986?0.4547=40.8%全厂热耗率

qcp=3600/ηcp=3600/0.408=8823.53kJ/(kw·h)

发电标准煤耗率

bcp=0.123/ηcp=0.1243/0.406=0.30147kg/(kw·h)

12

2、疏水泵设置在8号低压加热器

在前面计算的基础上，直接从5号低压加热器计算以后的步骤。

2.1、各级加热器的计算2.1.1、H5的计算

?5（h5-hs5)?r=?c4(hw5-hw6)

?5（2926-434.45）×0.99=0.80678×（564.324-446.045）?5h5?5=0.038692.1.2、H6的计算

hw5?5hs5hw6{?6（h6-hs6）+?5（hs5-hs6）}?r=?c4(hw6-hw7)（2763-376.94）×0.99?6=0.80678×(433.04-363.46)-0.03869×(434.45-376.94)

?6=0.02282

?6h6hw7hw6?5hs52.1.3、H7的计算

??5??6?hs6{?7（h7-hs7）+（?5+?6）（hs6-hs7）}?r=

（?c4-?5-?6-?7-?8）(hw7-hw8)+（?5+?6+?7+a8）（hw7-hs8）

2257.3781?7-112.87a8=87.5114147④

?7h7hw7??c4??5??6??7??8?hw8??5??6??7??8?hs8??5??6?hs6??5??6??7?hs72.1.4、H8的计算

{?8（h8-hs8)+（?5+?6+?7）（hs7-hs8）}ηr=（?c4-?5-?6-?7）(hw8-hsg)

2616.025?8?380.416?7?182.613??hsg(0.745??7??8)

⑤

13

hw8?8h8??c4??5??6??7??8?hsg??5??6??7?hs7??c4??5??6??7??8?hsg2.1.5、轴封加热器的计算?sg4（hsg4-hs）=（ɑc4-?5-?6-?7-?8）（hsg-hc+1.7）-hsg（0.74527-?7-?8）

=-111.2620541-144.92?7-144.92?8⑥由④⑤⑥解得?7=0.03968

hsg?sg4hsg4??c4??5??6??7??8?hc?8=0.01829

2.1.6、凝气份额的计算

?sg4hsα

=1-α1-α2-α3-α4-α5-α6-α7-α8-αt-α

=0.61479

c

sg1-

α

sg2-

α

sg3-

α

sg4

2.2、汽轮机汽耗量及各段抽汽量计算2.2.1、抽汽做功不足系数计算

根据已知参数，可以查水蒸汽表得到hrh=3035kJ/kg，hrh=3540kJ/kg，所以qrh=3540-3035=505kJ/kg

h0-hc+qrh=（3395-2349+505）kJ/kg=1551kJ/kgY1=

in

outh1?hc?qrh=(3140-2349+505)/1551=0.8356

h0?hc?qrhh2?hc?qrh=(3035-2349+505)/1551=0.7679

h0?hc?qrhh3?hc=(3333-2349)/1551=0.6344

h0?hc?qrhY2=

Y3=

h4?hcY4=Yt==(3132-2349)/1551=0.5048

h0?hc?qrhY5=

h5?hc=(2926-2349)/1551=0.3720

h0?hc?qrhh6?hc=(2763-2349)/1551=0.2669

h0?hc?qrhY6=

14

Y7=

h7?hc=(2663-2349)/1551=0.2025

h0?hc?qrhh8?hc=(2527-2349)/1551=0.1148

h0?hc?qrhhsg1?hc?qrhh0?hc?qrhhsg2?hch0?hc?qrhhsg3?hch0?hc?qrhhsg4?hch0?hc?qrh=(3394.45-2349+505)/1551=0.9996

Y8=

Ysg1=

Ysg2==(3535.66-2349)/1551=0.7651

Ysg3==(3028.44-2349)/1551=0.4381

Ysg4==(2716-2349)/1551=0.2366

各抽汽份额αj及其做功不足系数Yj的乘积αjYj见表2

2.2.2、汽轮机的汽耗量及各段抽汽量的计算

机组无回热纯凝汽工况时的汽耗量Dc0为

Dc0=3600Pe/(h0-hc+qrh)?mg=3600×3×100000/(1551×0.983)=708367.194kg/h机组有回热时的汽耗量D0为

D0=Dc0/(1-??j)==708367.194/0.7851=902263.65kg/h表2αj、Yj和Dj

αjYjY1=0.8356Y2=0.7679Y3=0.6344Y4=0.5048Y5=0.3720Y6=0.2669Y7=0.2025Y8=0.1148Ysg1=0.9996Ysg2=0.7651Ysg3=0.4381Ysg4=0.2366Yt=0.5048αjYj0.059100.058180.023600.012320.014390.006090.008040.002100.004430.003100.005800.000340.01741Dj=αjD0/（kg/h）D1=63817.11D2=68355.49D3=33564.21D4=22024.26D5=34908.58D6=20589.66D7=35801.82D8=16502.40Dsg1=3996.13Dsg2=3656.87Dsg3=11939.65Dsg4=1290.24Dt=31110.05α1=0.07073α2=0.07576α3=0.03720α4=0.02441α5=0.03869α6=0.02282α7=0.03968α8=0.01829ααααsg1=sg2=sg3=sg4=0.0044290.0040530.0132330.001430αt=0.0344815

??j=0.38521??Y=0.2149jj?Dj=347556.47αc=1-0.38521=0.61479

项目全厂汽水损失锅炉排污扩容蒸汽浓缩排污水化学补充水小汽轮机用汽锅炉蒸发量再热蒸汽量锅炉给水量1-??Y=0.7851jjDC=αcD0=554702.67份额αxα1=0.0101αb1=流量Dx=αxD0/（kg/h）D1=9112.86Db1=9112.86Df=4800.04D'b1=4312.82Dma=13425.68Dt=31110.05Db=911376.51Dfw=920489.380.0101αf=0.00532α'b1=0.00478αma=0.01488αt=0.03448αb=1.0101ααrh=fw=1-α1-α2=0.85351Drh=770091.051.02022.3、汽轮机的功率校核P1=

D（1h0?h1)?m?g3600D（2h0?h2)?m?g3600=4443.53kW

P2==6719.34kW

P3=

D（3h0?h3?qrh)?m?g3600D（4h0?h4?qrh)?m?g3600D（5h0?h5?qrh)?m?g3600D（6h0?h6?qrh)?m?g3600D（7h0?h7?qrh)?m?g3600D（8h0?h8?qrh)?m?g3600=5196.49kW

P4==4672.76kW

P5==9284.15kW

P6==6392.35kW

P7==12092.77kW

P8==6186.84kW

16

Pt=

D（th0?h4?qrh)?m?g3600D（ch0?hc?qrh)?m?g3600=6523.98kW

Pc==234921.67kW

汽轮机的总功率Pe=（Pc+Pt+计算误差

Δ=

?P）=296433.88kW

jj=1?Pe?Pe，Pe?100%=1.19%

计算的电功率接近给定的电功率，说明计算结果确凿。

2.4、热经济指标计算

2.4.1、汽轮机组热耗量(含小汽轮机)

Q0?D0(h0?hfw)?Drhqrh?Df(h''f?hfw)?Dma(hfw?hw)

=902263.65×(3395-1187.887)+770091.05×505+4800.04×(2773-1187.887)-13425.68×(1187.887-143.22)=2373877053kJ/h

2.4.2、汽轮机组热耗率

q0=Q0/Pe=2373877053/300000=7912.92kJ/(kw·h)

2.4.3、锅炉热负荷

Qb?Db(hb?hfw)?Drhqrh?Dbl(hbl?hfw)

=911376051×(3395-1187.887)+770091.05×505+9112.86×(1849.9-1187.887)=2406439755kJ/h

2.4.4各种效率

管道效率

ηp=Q0/Qb=2373877053/2406439755=98.65%

机组热效率

ηe=3600/q0=3600/7912.92=45.5%

全厂热效率

ηcp=ηbηpηe=0.91?0.986?0.4547=40.9%

全厂热耗率

qcp=3600/ηcp=3600/0.409=8801.96kJ/(kw·h)

发电标准煤耗率

bcp=0.123/ηcp=0.1243/0.409=0.3007kg/(kw·h)

17

3、经济性比较

热电厂的疏水逐级自流的连接系统，该系统没有疏水泵，系统简单，运行可靠，不耗厂用电，运行维护便利，但由于疏水最终流入凝汽器，直接导致冷源损失增加，又由于存在排挤低压抽汽现象，额外增加了冷源损失。因此，这种疏水方式经济性最差。采用疏水泵的连接系统，因其减少了相邻高一级的抽汽量(用疏水泵将本级疏水送入加热器出口凝结水管路中，提高了