ppj=0.5×(ppu+p'pu)=0.5×(21.47+1.1592)=11.31MPa
给水泵内介质平均比焓hpj: 取hpj =h'pu=617.3
根据ppj =11.31和hpj =617.3查得: p4 p4 给水泵内介质平均比容υpu =0.00108 m/㎏ 给水泵介质焓升ττ
pu
pu 除氧器 3
= hpu - h′pu=
3vpu?ppu?p?pu??10?pu p′ Hpu 0.00108??21.47?1.1592??103 ==26.41kJ/kg ρ0.83pu hpu 给水泵 h′pu 给水泵出口比焓hpu: ppu p′pu
hpu= h'pu+Δhpu=617.3+26.4=643.7kJ/㎏ 2-15给水泵焓升示意图
高压加热器H3的抽汽系数α3: 高压加热器H3的疏水系数α
d,3
:
α
d,3
=α
d,2
+α3 =0.143+0.0856=0.2286
3.6除氧器抽汽系数计算
除氧器出水流量α
c,4
α
c,4
=αfw+αsp =0.989+0.03257=1.02157
抽汽系数α4:
α4=[αc,4(hw,4-hw,5)/ηh-αd,3(hd,3-hw,5)-αsg,4(hsg,4-hw,5) -αsg,5(hsg,5-hw,5)-αsg,6(hsg,6-hhw,5)-αsg,7(hsg,7-hw,5) -αnf(hnf-hw,5)]/(h4-hw,5)
=[1.02157×(745.9-595.3)/1.0-0.2286×(759.9-595.3) -0.001429×(3024.3-595.3)-0.0015911×(3024.3-595.3) -0.0013694×(3474-595.3)-0.032354×(3169-595.3) -0.03235×(697-595.3)]/(3169-595.3)=0.00714
除氧器的物质平衡和热平衡见图2-16。由于除氧器为汇集式加热器,进水流量α
c,5
为未知。
c,5
但利用简捷算法可避开求取α。
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3.7低压加热器组抽汽系数计算 αsg?4 α αc,5 αg?5 1.由低压加热器H5热平衡计算α5 αnf αd3 低压加热器H5的出水系数αc,5: 2 1 由图2-16, αpu α c,4α
c,5
=-α
d,3
-α4-α
sg,L1
-α
nf
=1.02157-0.2286-0.00714-0.001429 图2-16除氧器的物质平衡和热平衡 -0.0015911-0.0013694-0.032354-0.03235 1-除氧器;2-ge给水泵;α=0.7167 α低压加热器H5的抽汽系数α α5=
g?5-sg?4
轴封漏汽系数;αnf-暖风器凝结系数 -除氧器出水系数
α
5
c,4
?c,5?hw,5?hw,6?/?hh5?hd5?0.7167??594.9?507.2?/1.0=0.02553
2978.5?528.5低压加热器H5的疏水系数αd,5 αd,5=α5=0.02553
2.由低压加热器H6热平衡计算α低压加热器H6的抽汽系数 α6=
h6?hd,66
?c,5?hw,6?hw,7?/?h??d,5?hd,5?hd,6?
0.716??507.2?414.3?/1.0?0.2553??528.5?397.2? ==0.02577
2851.0?397.2低压加热器H6疏水系数
αd,6=αd,5+α6=0.02553+0.02577=0.0513 3.由低压加热器H7热平衡计算α7 低压加热器H7的抽汽系数α7
α7=
?c,5?hw,7?hw,8?/?h??d,5?hd,6?hd,7?h7?hd,7
=0.716??414.3?237.9?/1.0?0.0513??397.24?257.8?=0.04599 2851.0?257.8低压加热器H7的疏水系数αd,7:
αd,7=αd,6+α7=0.0513-0.04599=0.09729 4.由低压加热器H8热平衡计算α8
由于低加H8的进水焓hsg、疏水焓hd,8为未知,故先计算轴封加热器SG。由SG的热平衡,得轴封加热器出水焓hw,sg:
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hw,sg??h?=h′c+sgsg?hd,sg??h?c,5 =137.3?表2-6.
0.0087455??3217.7?415??1.0=171.49kJ/kg 0.7167由pw,sg=2.758Mpa, hw,sg=139.7℃,查得轴封加热器出水温度tw,sg=32.78℃. 低压加热器H8疏水温度td,8:
td,8=tw,sg+δt1=32.78+5.5=38.28℃
由p's=0.0197Mpa, td,8=38.28℃查得低压加热器H8疏水焓hd,8=160.27kJ/kg. 低压加热器H8的抽汽系数α8:
α8=
?c,5?hw,8?hw,sg?/?h??d,7?hd,7?hd,8?h8?hd,8
0.7167??237.9?139.7?/1.0?0.09729??257.8?160.27?==0.2653
2455.8?160.27低压加热器H8的疏水系数αα
d,8
d,8
:
=α
d,7
+α
8
=0.09729+0.02653=0.1238 3.8凝汽系数αc计算 1.小汽机抽汽系数α
αxj=h?h4c,xj?c,4??puxj
:
?1.02157?26.4?0.03613
3169.0?2422.6c
2.由凝汽器的质量平衡计算ααc=α
c,5
-α
d,8
-Σα
sg
-αxj-αma
=0.7167-0.1238-0.008445-0.03613-0.0039263-0.03244=0.51658 3.由气轮机汽侧平衡校验α
c
H4抽汽口抽汽系数和α'4:
α'4=α4+αxj+αnf+α
=0.08643
各加热器抽汽系数和Σαj: Σαj=α1+α2+α3+α4+α5+α6+α7+α
0.0659
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8
pl
=0.00714+0.03613+0.03235+0.01081
=0.07089+0.07216+0.0856+0.08643+0.02553+0.02577+0.04599+0.02653=
轴封漏汽系数和ΣαΣα
⒂
sg,k
sg,k
: +Σα
sg,⑥
=Σα
sg,④
+Σα
sg,⑤
+Σα
sg,⑦
+Σα
sg,⑧
+Σα
sg,⑨
+Σα
sg,⑩
+Σα
sg,
=0.001429+0.001032+0.0015911+0.001264
+0.000673+0.0007626+0.0013694+0.0006244
=0.0087455 凝汽系数αc:
αc=1-Σαj-Σαsg=1-0.0659-0.0087455=0.51658 该值由凝汽器质量平衡计算得到的αc相等,凝汽系数计算正确。
3.9气轮机内功计算
1.凝汽流做工ωc ωc=(αc–α
sg,S
+α
sg,T
)( h0–hc+qrh) –αJqrh-α
sg,A
(h0 –h2)
=0.51658+(3397.2-2315.6+511.8)-(3397.2-3027.2)× 0. 01622=815.68kJ/kg
式中qrh—再热器吸热,qrh= hrh–h2=3538.9-3027.1=511.8 kJ/kg 2.抽汽流做功Σωa,j 1㎏H1抽汽做功ωa,1:
ωa,1= h0 –h1=3397.2-3144.2=253 kJ/kg 1㎏H2抽汽做功ωa,2:
ωa,2= h0 –h2=3397.2-3027.1=370.1 kJ/kg
1㎏H3抽汽做功ωa,3:
ωa,3= h0 –h3+ qrh=3397.2-3352.2+511.8
=566.8 kJ/kg
1㎏H4抽汽做功ωa,4:
ωa,4= h0 –h4+ qrh =3397.2-3169+511.8
=556.8 kJ/kg
1㎏H5抽汽做功ωa,5:
ωa,5= h0 –h5+ qrh =3397.2-2978.5+511.8
=930.5 kJ/kg
1㎏H6抽汽做功ωa,6:
ωa,6= h0 –h6+ qrh =3397.2-2851+511.8
=1058 kJ/kg
1㎏H7抽汽做功ωa,7:
ωa,7= h0 –h7+ qrh =3397.2-2716+511.8
=1193 kJ/kg
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1㎏H8抽汽做功ωa,8:
ωa,8= h0 –h8+ qrh =3397.2-2455.8+511.8
=1453.2 kJ/kg
表2-9 做功量和抽汽量计算结果 1㎏抽汽做功(kJ/kg) 各级抽汽量(kJ/h) 144170 146753 174086 14520 51920 52409 93530 53454 H1 253 H2 370.1 H3 556.8 H4 740 H5 930.5 H6 1058 H7 1193 H8 1453.2 抽汽流总内功Σωa,j:
Σωa,j=α1ωa,1+α2ωa,2+α3ωa,3+α'4ωa,4+α5ωa,5+α6ωa,6+α7ωa,7+α8ωa,8
=0.07089×253+0.07216
×370.1+0.0856×556.8+0.08643 ×740+0.02553×930.5+02577
×1.58+0.04599×1193+0.02653×1453.2 =273.4 kJ/kg
3.附加功量Σωsg,k
附加功量Σωsg,k是指各小汽流量作功之和:
Σωsg,k=α12(h0 –h12+ qrh)+( α8 + α9+, α10 ) (h0 –h8)
=0.03235(3397.2-3169+511.8)+(0.000673+0.0007626+ 0. 0013694)(3397.2-3169)=24.58 kJ/kg 4.气轮机内功ωi
ωi=ωc+Σωa,j+Σωsg,k=815.68+273.4+24.58
=1113.66 kJ/kg
4热经济指标计算
4.1气轮机的内效率、热经济指标、汽水流量计算
气轮机比热耗q0:
q0= h0 –hfw+αrhqrh=3397.2-1204.4+0.8505×511.8 =1757.5 kJ/kg 气轮机绝对内效率ηi:
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