(完整版)年产30万吨合成氨合成工段工艺设计毕业论文 下载本文

Ar =392.196÷11614.691×100%=3.378% H2 =7200.879÷11614.691×100%=61.998% N2 =2380.478÷11614.691×100%=20.495% 出器总物料==11614.691+575.367=12190.058 m3 3.3.14 冷交换器物料计算

V14

V

3

V17

V2

图3.4冷交换器物料简图

进口物料:冷交换器进口总物料等于氨冷器出口总物料,其中气体入口VⅡ=11614.691m3 =575.367m3

由气液平衡计算得,以1kmol进口物料为计算基准:即 F=1

(3-8)

L?xNH3?V?yNH3?F?mNH3 (3-9)

将=0.025, =0.98425

?x V??x(3-10)

NH3NH3?mNH?yNH33?m?1.026? ?0.959251NH3(3-10)式中可由物料平衡和氨平衡计算=

(3-11)

(3-12) (3-13) 式中V′Ⅱ —冷交换器入口总物料 V′17—冷交换器热气出口总物料 —冷交换器入口总氨物料 将V8=10212.836m3

V13=135.479m3 L15=843.687m3 代入上式解得V17′=9233.67m3 V′Ⅱ=2956.387+9233.67=12190.057 m3 =865.748 m3

=865.748÷12190.057=0.0710 代入(3-10)得:

V=1.026-(0.1056÷0.95925)=0.95197 L=1-V=0.04803

=0.04083÷0.95197=0.05045 由可求出冷交换器冷凝液体量: ==0.05045

冷凝液体量:L16=0.0909V3=0.05045×11607.77=585.612 m3

出器物料:冷交换器(冷气)出口气体物料等于进口总物料减去冷激液体量 V3=11894.358-585.612=11605.746m3 其中:NH3 =11605.746×2.5%=290.145m3 CH4 =11605.746×11.643%=1351.257m3

Ar =11605.746×3.357%=389.605m3 H2 =11605.746×61.874%=7180.939m3

N2 =11605.746×20.625%=2393.685m3

计算误差=×100%=(11605.746-11607.770)÷11607.770×100%=-0.0231% 误差在设计允许的范围内,满足要求。 校核氨分离器液氨百分数 氨分离器液氨百分数:

G分%?L15?x15?100%?

L15?L16?x16843.687×095618÷(843.687×0.95618+0.98425×585.612) ×100%=58.325% 冷交换器分离液氨百分数:

G冷%=1-G分%=1-58.325%=41.675%

计算误差==(57.554%-58.325%)÷58.325%=-1.322% 3.3.15 液氨贮槽物料计算

进槽物料:氨分离器入槽液体 L15=843.687 m3 其中:NH3 =843.687×0.95618=806.717m3 CH4 =843.687×0.01731=14.604m3

Ar =843.687×0.00157=1.325m3 H2 =843.687×0.01973=16.646m3 N2 =843.687×0.00521=4.396m3

冷交换器入槽液体 L16=585.612 m3

其中:NH3 =585.612×0.98425=576.389m3 CH4 =585.612×0.00427=2.501m3

Ar =585.612×0.00068=0.398m3 H2 =585.612×0.00825=4.831m3 N2 =585.612×0.00255=1.493m3

入槽混合物料 L21=L15+L16=843.687+585.612=1429.299 m3 各组分物料含量:

其中:NH3 = 806.717+576.389=1383.106m3 CH4 = 14.604+2.501=17.105m3

Ar = 1.325+0.398=1.723m3 H2 =16.646+4.831=21.477m3 N2 = 4.396+1.439=5.835m3

百分含量:

其中:NH3 =1383.106÷1429.299×100%=96.768% CH4 =17.105÷1429.299×100%=1.197% Ar = 1.723÷1429.299×100%=0.121% H2 = 21.477÷1429.299×100%=1.503% N2 =5.835÷1429.299×100%=0.408% 出槽物料:液氨贮槽出口弛放气 V20=108.320 m3

其中:NH3 = 64.624m3 CH4 = 15.649m3 Ar = 1.656m3

H2 = 20.768m3 N2 = 5.695m3

出口液氨总物料 L19=L21-L20=1429.299-108.320=1320.797m3 其中:NH3 =1383.106-64.624=1318.482m3

CH4 =17.105-15.649=1.456m3 Ar =1.732-1.656=0.076m3

H2 =21.477-20.768=0.709m3 N2 =5.835-5.695=0.140m3

各组分百分含量:

其中:NH3 = 1318.482÷1320.797×100%=99.826%

CH4 =1.456÷1320.797×100%=0.110% Ar = 0.076÷1320.797×100%=0.006% H2 = 0.709÷1320.797×100%=0.0534% N2 =0.140÷1320.797×100%=0.011%

液氨产量核算: =1318.482÷22.4×17=1000.06kg 核算结果符合要求。

3.4热量衡算

3.4.1 冷交换器热量计算

Q2

Q3

Q14

Q17 Q16

图3.5冷交换器热量计算示意图

(1) 热气进口温度,冷交换器热气进口温度等于水冷器气体出口温度,由题意知T14=35℃。

(2) 冷气进口温度,为保证合成塔入口氨含量在2.5%,出氨冷器的气体的氨含量必须等于小于2.5%,设过饱和度为10%,则,该冷凝温度下的平衡氨含量为:

=0.025÷1.1×100%=2.27%