例: 已知某炼油厂燃料油的干燥无灰基 (旧标准称可燃基) 成分为: Cdaf = 87. 52% ,
H
daf =10. 74% , Odaf = 0. 51% , Ndaf = 0. 51% , Sdaf = 0. 72% ; 给出的工业分析成分是 Ad =
0. 21% , Mar =2. 0% , 试确定在空气消耗系数为 1. 10 时, 该燃料油的各燃烧系数。
解:
(1) 根据燃料中的成分在任何一种表达形式中所占的绝对含量是相等的原理 (见2-33
题), 进行燃料油收到基成分的换算:
首先求出灰分的收到基成分, 即:
A
ar = [(100 - Mar) /100]Ad = [(100 - 2. 0) /100] × 0. 21% = 0. 98 × 0. 21% = 0. 206%
再根据 A
ar和 Mar的值求出其他元素的收到基成分:
第八章 铝合金熔铸设备 ·317·C
ar = [(100 - Aar - Mar) /100]Cdaf = [(100 - 0. 206 - 2. 0) /100] × 87. 52%
= 0. 978 × 87. 52% = 85. 6%
同理可求得:
H
ar = 0. 978 × 10. 74% = 10. 5% ;Oar = 0. 978 × 0. 51% = 0. 5%
N
ar = 0. 978 × 0. 51% = 0. 5% ;Sar = 0. 978 × 0. 72% = 0. 70%
(2) 按 2-35 题的公式计算燃料油的低位发热量:
Q1 = 339Car + 1030Har - 109(Oar - Sar) - 25Mar
= 339 × 85. 6 + 1030 × 10. 5 - 109 × (0. 5 - 0. 7) - 25 × 2
= 29018. 4 + 10815 + 21. 8 - 50 = 39805(kJ/ kg)
(3) 按 8-26 题的公式计算实际空气需要量:
按组分计算:
V′
0 = nV0 = n[8. 89Car + 26. 7Har + 3. 33(Sar - Oar)]
= 1. 1 × [8. 89 × 85. 6% + 26. 7 × 10. 5% + 3. 33 × (0. 70% - 0. 50% )]
= 1. 1 × 10. 42 = 11. 46(m3 / kg)
按发热量计算:
V′
0 = nV0 = n[0. 21 × 10 -3
Q + 2. 0]
= 1. 1 × [0. 21 × 10 -3 × 39805 + 2] = 1. 1 × 10. 36 = 11. 40(m3 / kg)
(4) 按 8-26 题的公式计算实际燃烧产物量:
按组分计算:
V′
1 = V1 + (n - 1)V0 = [1. 87Car + 11. 2Har + 0. 8Nar +
0. 7S
ar + 1. 24Mar + 0. 79V0] + (1. 1 - 1) × 10. 42
= [1. 87 × 85. 6% + 11. 2 × 10. 5% + 0. 8 × 0. 5% +
0. 7 × 0. 7% + 1. 24 × 2% + 0. 79 × 10. 42% ] + 1. 04
=11. 04 + 1. 04 = 12. 08(m3 / kg)
按发热量计算:
V′
1 = V1 + (n - 1)V0 = 0. 265 × 10 -3
Q + (n - 1)V0
= 0. 265 × 10 -3 × 39805 + (1. 1 - 1) × 10. 36
= 10. 55 + 1. 04 = 11. 59(m3 / kg)
(5) 按 8-26 题的公式计算实际燃烧产物密度:
ρ1 = [(1 - Aar) + 1. 293V′0] / V′1 = [(1 - 0. 00206) + 1. 293 × 11. 46] /12. 08
= 1. 31(kg/ m3)