总66.780量 08 1206.4985 100 38.38 693.7281 100 28.40008 512.7744 100
由于立式虹吸式再沸器结构简单,造价低廉,又因为水和甲醇黏度小,所以我选择立式虹吸式再沸器。
我们将计算再沸器所需的数据罗列如下;
操作压力 121.569kp , 蒸发量 0.142kg/s , 该压力下水的饱和温度为105℃,临界压力为Pc=22.05/Mpa,加热蒸汽158.85℃,传热管选用φ25.4?2.5钢管,管长Ls=2.5m,由塔底到再沸器接管的当量长度为20m,汽化潜热2150kJ/kg. 饱和液态水105度下的黏度268upa.s , 105度气态水的黏度12.2 upa.s ,液态热容为4.222?103kJ/(kg*K), 气态热容为1.8818 kJ/(kg*K)
流程安排:因为溶液中含有一定Nacl,具有腐蚀性,所以选择溶液走管程,蒸汽走壳程。
6.1初估再沸器尺寸:
传入的热量:Q=0.142?2150=305.3Kw 传入温差: 158.85-105=53.85℃ 假定总的传热系数:K=2320W/(m2*K)
传热面积: A=305.3?103 /53.85?2320=2.44 m2
需要传热管数目: 筒体直径的计算
管中心距t=1.25d?1.25?0.025?31.25mm
02.443.1415?0.0254?2.5=12.25=13
圆整至规格尺寸t=32mm
最外列管中心距筒体b?2d0?2?25mm?50mm
'中心线上布管数nc=1.113=3.96,圆整nc=4
筒体直径的计算DN=t(nc-1)+2b=32?3+2?50=196mm 考虑到热损失等情况,圆整到300mm。
通过作CAD图得实际管程数量
24
得实际管程数量为28 6.1.2决定循环量
a 首先假定再沸器出口管的气体分率: X?=0.12
总的循环量为W=0.142/0.12=1.18kg/s,按照40%的汽化率时,x=0.048,
1?x0.9?g)(Xtt=(x?l1Xtt-2)0.5(
ulug)0.1=(1?0.0480.048)0.9
(
9541060)0.5(
26812.2)0.1 =19.02
Rg=1-(
?21/Xtt?1)0.5=1-0.65=0.35
Ptp=Pg Rg + PL(1- Rg)=0.954?0.35+1060?0.65=0.3339+689=689.3339kg/m3
1?x0.9?g)(Xtt’=(x?l)0.5(
ulug)0.1=(1?0.120.9954)(0.12106013.72)0.5(
26812.2)0.1 =7.77
RgE=1-(
1Xtt-2?21/Xtt?1)0.5=1-()0.5=0.482
Ptp=Pg RgE + PL(1- RgE)=0.954?0.482+1060?0.518=398kg/m3
b 求显热段的长度: Gi=
1.18?4=129.00kg(m2.s)
2?0.0204?280.0204?129.00kg268?10?6diGiRei=
ul=
=0.98?104
由《化工工艺设计手册》上,图15-15查得JH=0.004,由下式计算显热段的对流传热系数hi, hi=JHCPLGi(
3CPLul?L)-2/3
?6(
uuw)-1/3
=0.004?4.22?103?225.75?
(
4.222?10?268?10?L)-2/3 ?1=2723.85
25
hl=(tw=
1hi+0.000086)-1=2723.0837
=
8500?158.85?2723.0837?1058500?2723.0837hoto?h1t1ho?hl=145.8℃
tw – ti =145.8 -105=40.8℃
?t?L??diNThi(tw?t)Cplwi=
??0.0204?16?2723.0837?40.84.222?10?1.183?22.9℃/m
(?t?p)s?105?90(1.2?0.7)?1.02?29.4℃/(kg.cm)
-2
?p?L?Pl=955.3?10?4kg/(cm2.m-1)
由式(15-90)得显热段长度为: LBC=
??t/?PS?t/?l?p/?l?(?t/?p)s?LS?29.422.90.096?29.4?2.5?0.274
c.检验循环推动力: 按下式计算
[LCD(?l-?tp)-PtPELDE]g??PT
[LCD(?l-?tp)-PtPELDE]g=[(2.5-0.274)?(1260-689.33)-398?0.153]?9.8=11852.3Pa 6.2计算再沸器管系总压力降?Pt. a.按下式计算入口管内的摩擦压降?P1 Gi=
wi?di2=
1.183.14?(0.151)/42?65.93kg/(m*s)
2diGiRei=
ul=
0.151?65.93kg268?100.04Re0.16?6=3.7 ?104
=0.0074
因为Rei>2100, f==
0.04(3.7?10)40.1626
?P1=
4fiGiL'2Pldi2?2?0.0074?65.93?201060?0.1512?8Pa
b.按下式计算显热段的摩擦压力降?P2
wiNT?di2Gi==
1.1813?3.14?(0.0204)/42?277.85
diGiRei=
ul0.04Re0.16=
0.0204?277.85268?10?6=1.4 ?104
fi ==0.0087
2?P2=
4fiGiLBC2Pldi?2?0.0087?277.85?0.811060?0.02042?50.3Pa
c.按下式计算?P3 m=
wiNT?di2=
1.1813?3.14?(0.0204)/42?277.85
Relo=
dimul=
0.0204?277.85268?10?6=1.98 ?104
Rego=
dimug=
0.0204?277.8512.2?10?6=46.46?104
0.314Rego0.25fl=
(0.314Relo0.25=0.026 fg==0.014
dpdz)lo=
0.026?277.8522?0.0204?1060?46.4 (dpdz)go=
0.014?277.8522?0.0204?0.954?27767.7
27
(dp由Y
2=
27767.7dz=?598.4 Y=24.5 46.4?dp????dz?lo)go按《化工工艺设计手册》上的表15-26,B=520/24.5/277.850.5=21.2/277.850.5当=1.27 n=0.2,按表15-25,当x=0.12时查得式15-98的积分值为0.072。
?lo=1+(Y-1)(0.072B+
?P3=?lo(222
X2E3?n)=1+597.4?(0.072?1.27+
0.121.82.8)=60.4
dpdz)loLCD=60.4?46.4?2.226=6238.5Pa
d.按《化工工艺设计手册》上式(15-61)~(15-68)计算出口管的摩擦?P4 m=
wi?di2=
1.183.14?(0.2488)/42?24.3kg/(m?s)
2Relo=
dimul=
0.2488?24.3286?10?6=2.1?104
Rego=
dimug=
0.2488?24.312.2?10?6=5?105
0.186Rego0.2fl=
(0.186Relo0.2=0.025 fg==0.013
dpdz)lo=
dp0.025?24.322?0.2488?1060?0.028 (dpdz)go=
0.013?24.322?0.2488?0.954?1244
由Y2=dz()go?dp????dz?lo520=
12440.028?44425 Y=210.1
B=
210.1?(24.3)20.5?0.5
2?n2?n?lo=1+(Y-1)[BX
0.875
2
2(1-X)
2 +X2-n ]= 1+44424?[0.5?0.120。875?0.88
+0.121.75]=4198
28