欢迎来到天天文库
浏览记录
ID:18817009
大小:70.50 KB
页数:11页
时间:2018-09-24
《制浆造纸专业单词10》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、61Thischapterisconcernedprimarilywithalkalinepulpingequipment.However,th'eprinciplesdiscussedapplytoallchemicalpulpingmethods.Theobjectiveforanewpulpmilldesignorfortheexpansionofanexistingfacilityistoproducequalitypulpatthelowestcostwhilemeetingenvironmentalstandards.Qualitypulpcanbep
2、roducedusingeitherbatchorcontinuousequipment,andtheproperchoicewilldependonconsiderationofallrelevantfactors.Becauseoftheinterdependenceofcookingwithoverallmilloperations,itisnotpossibletogeneralizeaboutthepropercourseofactionforallinstallations.Whencontinuousdigestersbecameoperationa
3、linthelate1950'sandearly1960's.anumberofadvantageswereclaimed.Amongthese,theclaimsoflowerenergyconsumptionandreducedpollutionhavegenerallyprovenvalid:butclaimsofhigheryield,betterstrength,andimproveduniformityhavenotbeensubstantiatedbymillexperience.Initially,amanpowersavingswaspossib
4、lewithcontinuousdigesteroperation,butnewer,fully-automatedandcomputer-controlledbatchdigesterinstallationscannowbeoperatedbyjustoneindividualpershift.Theauxiliaryequipmentassociatedwithcontinuousdigestersismorecomplexthanthatrequiredbyconventionalbatchdigesters.Onepulpinglinewillusual
5、lydependonasinglecontinuousdigesterorseveralbatchdigesters.Ifonebatchunitistakenoutofoperationforanyreason,theproductionrateisonlycurtailed:butifacontinuousdigesterisdown,theentireproductionislost.Therefore,productionavailabilitynormallyfavorsthebatchdigester.Also,whenfrequentchangesi
6、nwoodfurnishordegreeofcookingarerequired,thebatchdigestersaremoreflexible.Generally,startupsandshutdownsareeasierforbatchdigesters.Steamconsumptionforcontinuousdigestersismuchlowerthanforbatchunitsbecauselow-pressureflashsteamfromtheliquorcanberecycledtopreheatandpreconditionchips.Ste
7、amdemandisalsomoreconstantforcontinuousdigesters,althoughfluctuationindemandfrombatchunitscanbereducedwithcomputercontrol.Thesizingofthepowerboilerisaffectedbybothaveragedemandandpeakdemand.TherelativeadvantagesofbatchandcontinuousdigestersaresummarizedinTable5-1.table5-1.Advantages:b
8、atchv
此文档下载收益归作者所有