lesson-17-Boiler-Management-轮机英语教学.ppt

单击此处编辑母版标题样式,Jimei university,Lesson 17,Boiler Management,Jimei university,General management principles and operating procedures are well known and must always be followed to avoid boiler,mishaps(意外事故、损坏).,In particular:,Jimei university,With many small package boilers,the automatic control sequence usually ensures that the boiler fire is initially,ignitedlighted,from a diesel oil supply,Jimei university,and changed over to the usual source when,ignition,is completed.,Jimei university,When burning such diesel fuel,it,is essential for safety that only the correct(small),burner tip(锅炉燃烧器喷油嘴),should be used.,Jimei university,It should be,kept in mind,that if fire does not light,immediately shut off fuel and vent furnace.,Jimei university,Complete ignition of fuel in the furnace is essential.The burner flame,the,smoke indicator,(,烟气指示器),and the funnel should be frequently observed.,Jimei university,If,on first ignition,the flame is,uncertain,badly shaped and separated from the primary,swirler,(旋流),momentary,opening or closing of,air register(调风门),air regulator,may correct.,Jimei university,The,pH value,of the boiler feed water should be kept between 8 and 9 and the boiler,density,less than 300 ppm.,Jimei university,The boiler should be,blown down,when the oil burner is operating,the water level lowered and then restored to prove the functioning of the low water,cut-out,and the oil burner,start-up,equipment.,Jimei university,Fuel burner components and,igniter,electrodes,should be cleaned weekly and the furnace examined to ensure that there are no excess carbon deposits.,Jimei university,Tubes in the exhaust gas section of the boiler should be brushed through at about six-monthly intervals,and those in the oil burning section periodically examined and cleaned as necessary with,a wire bristle brush,.,Jimei university,Boiler fires may be,out,for long periods when a ship is,at sea,and the boiler steaming maintained by heat input from waste heat recovery plant.,Jimei university,This operation is free from,hazard(危险),but feed water and boiler water treatment must be maintained to prevent internal,deterioration,or scale formation.,Jimei university,Water level controllers must be kept operable to protect external steam-using plant from,water“carry-over”(蒸汽携水、汽水共腾),danger,.,Jimei university,If a boiler,is isolated from the steam-using system it must be kept,either,in closed dry storage with a suitable internal,desiccant(干燥剂),or,completely full of treated water,Jimei university,or,under a low steam pressure preferably maintained by a steam-heated coil.,Jimei university,Frequent comparison of,drum-mounted,and,remote-reading,water level indicators,:,Jimei university,discrepancies,between these have contributed to failures because of overheating through shortage of water,when a boiler was being oil-fired.,Jimei university,If in doubt,as to,the true boiler water level,i.e.whether a water level indicator sightglass is completely full or empty,when a unit is being oil-fired,the fire should be immediately extinguished until the true level is,resolved(恢复),.,Jimei university,In general,fires should be immediately extinguished by,remote tripping of fuel supply valves(供油远程速闭阀),;,Jimei university,forced draught,air pressure maintained if there is any risk of escaping steam entering the boiler room;,Jimei university,Regular operation of soot blowers,if these are fitted,when the boiler is on oil-fired operation.,Jimei university,The steam supply line must be thoroughly warmed and drained before the blowers are used,the,air/fuel ratio,increased throughout the action,and blowers,greased,after use.,Jimei university,Immediate investigation,of,any high,salinity(盐度),alarms in condensate system,and,elimination,of any salt water,or,oil contamination of boiler feed water system,.,Jimei university,Safety precautions(should be)taken before entering a boiler,connected to another boiler,under,steam,.,Jimei university,The main engine may be kept in operation with the boiler dry and the gases passing through the exhaust gas section.,Jimei university,If this is to be done for a prolonged period it is advisable to allow,a current of air,to flow through the boiler by removing,manhole,sighthole,and mudhole covers.,Jimei university,If refilling a hot boiler the main engine speed should be reduced to slow for half an hour,and,the feed water supplied be as hot as possible;thereafter the main engine may be brought up to power over a similar period.,Jimei university,Reading Materials,A.Raising steam(升汽),Jimei university,The boiler should be filled to normal level(1/2,gaugeglass,)when the,feed,control valve is automatically closed and the,panel indicating light,extinguished(off).,Jimei university,The forced draught fan should be started and air passed through the furnace for several minutes to,purge(清扫),it,of any exhaust gas or oil vapors.,Jimei university,The operating burner can now be lit and adjusted to provide a low firing rate with good combustion.,Jimei university,The fuel oil pressure and forced draught pressure should be matched to ensure good combustion with a full steady flame.,Jimei university,When water level nears the top of the,gauge glass,due to expansion,the initial level should be restored by,draining off,water through the,scum valve,.,Jimei university,When a drum pressure of about 210 KN/m,2,has been reached,the,drum air vent,may be closed.,Jimei university,The boiler must be brought slowly up to working pressure in order to ensure gradual expansion and,Jimei university,and,to,avoid overheating the,superheater,elements,and,damaging any,refractory(难熔的),material due to expansion stresses.,Jimei university,The time,required,will vary with boiler types and construction.,Jimei university,If necessary blow down some of the contents to sea to displace cold water from the lowest part of the boiler shell,to minimize temperature differentials and the thermal stresses.,Jimei university,The main and auxiliary steam lines should now be warmed by,crack opening,of the boiler main and auxiliary stop valves.When the lines are hot,close,the drains.,Jimei university,In addition the water level gauges should be blown through and checked for correct reading.,Jimei university,When the steam pressure is about 300 KN/m,2,below the normal operating value,the safety valves should be lifted and released using the,easing gear(放松装置、释放装置).,Jimei university,Once at operating pressure,the boiler may be put on load and the superheater circulating valves closed.,Jimei university,All other,vents,drains,and,by-passes,should then be closed.The water level in the boiler should be maintained.,Jimei university,B.Boiler shut-down and,securing(封炉),This operation may have to be done normally at the end of a voyage or in emergency.,Jimei university,For normal shut-down the suitable procedure is:,-Carry out soot blowing,if permissible.,Jimei university,-Change combustion control from automatic to manual.,-Change fuel supply to diesel oil;,shut,steam,off,fuel heaters,and,trace heating(伴热管),.,Jimei university,Close burner supply valves and main fuel shut off valve.,-Purge boiler furnaces with air for three to five minutes;stop forced draught fan.,Jimei university,-Close steam stop valves on boiler when pressure is reduced.Drain boiler when it has cooled down or fill with treated water.,Jimei university,C.Boiler water testing,Tests,required,are,hardness(硬度),alkalinity(碱度),chloride(氯化物),dissolved(溶解)solids(or conductivity传导率),hydrazine(联氨),phosphate(磷酸盐),pH and,occasionally,silica(二氧化硅).,Jimei university,The essential test for control of treatment are alkalinity,chloride or dissolved solids,phosphate and hydrazine.,Jimei university,Phenolphthalein(酚酞)Alkalinity in boiler water,Five to ten drops of phenolphthalein are added to a measured,filtered volume of sample.If alkaline,a pink color is produced.,Jimei university,Titrate(以滴定法测定),with,sulphuric acid(硫酸),of known strength with continuous,stirring,of the sample with a glass rod until the pink colour just disappears.,Jimei university,The boiler alkalinity,in parts per million,is calculated from the strength of the acid and volume of the boiler water sample.,Jimei university,1.Measure 20,50 or 100ml of filtered boiler water from a,graduated cylinder(量筒),into a,casserole(烧杯),.,Jimei university,Add 10 drops of,phenolphthalein indicator solution,.The sample will turn pink if phenolphthalein alkalinity is present.,Jimei university,2.Add,sulphuric acid solution,strength 0.02N from a 10ml automatic,burette(滴管),stirring continuously until the pink colour just disappears.Note the burette reading.,Jimei university,3.Calculate the result as follows:,Alkalinity to phenolphthalein,=1000,ml,of,sulphuric acid(0.02N),used,volume of sample in ml,(expressed in ppm in terms of CaCO,3,),Jimei university,Chlorides in boiler water,1.To the sample used for the phenolphthalein alkalinity test add a further 1.0ml of sulphuric acid solution,0.02N.,Jimei university,2.Add 10 drops of,potassium chromate(铬酸钾),indicator solution.The sample will turn yellow.,Jimei university,Add,silver nitrate(硝酸银),solution,strength 0.02N from a 10ml automatic burette,stirring continuously until the yellow just changes to a,reddish,range.Note the burette reading.,Jimei university,3.Calculate the result as follows:,Chloride=1000,ml of silver nitrate(0.02N)used,less 0.2,Volume of sample in ml,Jimei university,Hardness by,EDTA(乙二胺四乙酸),in Boiler Water,In correctly treated boiler waters,the hardness is very small.,Jimei university,The hardness is determined by titrating a 100ml sample of boiler water with a standard solution().02N)of EDTA using,Mordant Black(黑色煤染剂),as indicator which,Jimei university,which gives a red colour in the presence of an alkaline solution of,calcium(钙),and,magnesium(镁),salts.,Jimei university,The sample of boiler water must be filtered before testing.,1.Measure 100 ml of filtered boiler water from a graduated cylinder into a casserole.,Jimei university,2.Add 2ml of,ammonia(氨),buffer solution,and add 1ml Mordant Black 11 solution and stir.,Jimei university,3.If any hardness salts are present the colour will turn wine-red.,Jimei university,4.Add EDTA solution,strength 0.02N,from a 10ml automatic burette,stirring the solution until the colour of the solution in the casserole begins to change to purple.,Jimei university,Continue adding EDTA solution slowly until all traces of the red colour have disappeared.This is the end point.The colour of the solution should now be blue,or grayish.,Jimei university,5.Calculate the result as follows:,Hardness,=10ml of EDTA solution(strength 0.02N)used.,(expressed in ppm in terms of CaCO,3,),Jimei university,D.Chemicals used in water treatment aboard ship,Chemical,Formula,Uses,Disodium hydrogen phosphate,Na,2,HPO,4,In boiler treatment for precipitation,of calcium as Calcium phosphate,Trisodium phosphate,Na,3,PO,4,Sodium polyphosphate,(NaPO,3),x,Sodium hydroxide,(Caustic soda),NaOH,In boiler treatment to provide alkalinity for protection against corrosion and to precipitate,Sodium carbonate,(soda ash),NaCO,3,magnesium hardness salts in the form ofmagnesium Hydroxide.,Sodium sulphite,Na,2,SOs,For removal of traces of dissolved,oxygen from boiler feed water,Sodium sulphate,NaSO,4,In boiler treatment where protection,Sodium nitrate,NaNO,3,Against caustic craking is required,Jimei university,