化工概论：8-3 Pumping Equipment for Gases

1、8.3 Pumping Equipment for GasesDifference of L and G transferredDensityLarge volume, high speedViscosityTendency for leakageGas Compressed fluidGas A considerable increase in temperatureThe principle types of compressors for gasesAccording to the outlet pressure and the compression ratio r r = outle

2、t pressure / inlet pressure (absolute)wFans (通风机通风机)： P 1.471104Pa(g)， r 1.15wBlowers(鼓风机鼓风机)： 1.471104 2.942105Pa(g) ，r 2.942105Pa(g) ，r 48.3.1 Centrifugal fansSimilar to centrifugal pump wVolute, impellerwCross-section of the delivery pipe -circularhigh pressure -squarer middle and low pressurewIm

3、peller -straight- low pressure -forwards middle and high pressure -backwards-middle and high pressurewLow pressure: 1.2Kg/m3 ,TTHH QQ 2 . 1NN8.3.2 BlowersCentrifugal blowersturbine blowers : multi-stages, to develop high pressure P2 294103Pa(g)Rotary blowers p287-Rootes blower: positive displacement

4、 typeCompression is achieved by the rotation of two elements. Q n no relationship with discharge pressureQ=2-500m3/minP2 80103Pa(g) T85C 8.3.3 Centrifugal compressors - Turbo compressors, similar to centrifugal blower both in the principle and the constructionThe number of stage is much moreDiameter

5、 of the impeller is much largerSpeed of rotation is much higherThe cooler between each section is necessaryAdvantages:Small volume; high capacity; uniform delivery; fewer moving parts8.3.4 The Reciprocating CompressorNo clearance1-2 compression2-3 expulsion3-4 sudden reduction in pressure4-1 suction 1-2 isothermal process1-2 isentropic processWith clearance12340V2V1VP1P2P图2 -54 有 余隙压缩循环V4V3Multistage Compressormin3122212