Document v1Za1rrvrEkk8NnagmN2xGpMY

Abatement. A blower must be used lo del necessary penetration. One large utility running several power plants equipped 29 underfeed stoker-fired steam generators with vari ous forma of overfire air jets. Its prac tice placed steam-actuated jets on oil older boilers where (1) a limited oper ating life is foreseen (2) lota of steam imposes no makeup hardships. In one setup, Fig. 7, four jets per boifer produced a definite improvement in smoke emission from 12 operating units. Six additional jets per boiler are going in to provide for overload conditions. Another boiler-type at this same plant has five jets per boiler. These boilerunits have high settings and smoke dif ficulties have never been excessive. The jets were sdded lo take care of peaks over and above the expected normal. At still another plant 12 underfeed units operate with only two pairs of jets, set to give a diagonal throw, Fig. 8. To put in additional jets along the front wall meant a very expensive in stallation. Results have exceeded expec tations and no more jets are planned. One plant experienced makeup diffi culties from a use of steam-actuated jets. They went to a blower-jet form of introducing overfire air. Fifteen V-in, jets went into the from wall and twenty (678) SMOKE OBSERVATION REPORT One organization, a strong believer In the value ol overfire jets, has instituted _Obtrvotion Point, a regular procedure of taking smoke observations. Eaeh observation covers a fall hour with readings every 15 sec onds, o total of 240 leading***p*er obser STACK OIII0III STACK Ol1I0IY1 vation. Fig. 10 shows a form it worked up for recording observations from four stacks at one time. Table 1 gives an interesting set of collected figures on several plants under observation. At Station 1 eight identical boilers operate with separate stacks. One boiler. No. 4, pul in blower jets for results shown. Stacks under observation la Station 2 serve ten boilers. But moat smoke of fenses here occur during banking pe riods and it is felt that methods other than jets must be applied to improve Average Dtnsi'yV-- unoke emission. The North stack ot Station 8 handles VtOlATlONS VIOLATIONS the output of 12 boilers equipped with *1 Otniify X.------'j tensity %------ 0Z Density X_____ Density X__ diagonal jets. Usual smoke emission, be fore jet installations, ron between 40 I Actual }ot performance eon be determined only by sotting up rogutar procedure for raking smoke observation*. Above form enables observation of four stacks and 60ft density. Twelve boilers with four jets per boiler discharge through two stacks, A Table I--Figures on Several Plants Under Observation and B, on Station 4. Six additional jets are going in each boiler to cut down on Stacks 1,9, 3,5,6,7,9... 1 and 9.................... Nodi........................ A, B........................ Observa tions 139 11 57 39 68 34 Smoke density, % 94.6 5.3 94.9 13.9 90.0 9.7 Rinslema nn, % No. 9 No. 3 31.4 3.0 94.9 3.7 17.4 6.7 11.3' 0.0 1.3 0.0 3.3 0.6 Jt None Blowet None Steam Steam Steam smoke emission. The last lilted aeries of data at Sta tion 4 on stack C record the results of five diagonal jets per boiler added to three boilers whose output was fairly free of smoke before the jet installa tions. No marked Improvement shows. This seems to indicate that jet-installstions apply particularly where a heavy Table II--Readings Collected from 48-Kour Test Blower jets were tuned on ant oil alternately every half,hour.... With *. .!** ~Salrf <tonjtr> %____ 7.0 -.ftonilrmnn No. 9, %. 0.0 ..(Rblltmaim No. 3, %. 0.0 Without |,t, JS.7 51.9 19.2 With Without lti ltt Stm, lb P4t hr............ 91.400 96.900 Outlet-sas temp, F------ 799 799 Boiler outlet, CO*. %- 11.9 19.6 smoking condition prevails. Table II lists the readings collected `from' a"48-hr test' where' blowcr jets were turned on and off alternately.every half hour. Observations were taken for o total of eight hour*. Blower-jet operation, judging from results recorded by this 4B-hr teak-cause a definite drop in CO# in the exit flue gas, possibly because additional excess air introduced over the fire (1) reduces l'et* u* blower rated at 6000 }m wiih a static pressure of 14-in wg. *^1 operating conditions require f,on7 1250 cfm at 10 in. to get a pcae*:ydoa length 0f 8 ft plus. f': | ,er lna of the nozzles slanda 5 ft Vi. x*bove the top line of tuyeres at I.1* furnace front. Noales dm at a 'd! si! 3 lt ^ *n' bove the bottom line ;j! e lu7res at the furnaco reor. Cen: y* 6 ft 11 In. from side water- *ot ****"' spacing la 12 in.-, !t>,Ccr'lCr' and outboard oozzles 1 ^ *n- from side waterwalla. `allw.i * ^ow about relative In- " cto of blower jet against a )st? Only comparison available placet steam jets at present-day prices, including engineering and overheod items, to run between 180 and $110 per jet. Blower-jet assemblies available range from $194 for sat of 4%-in. noales to $925 for 16 of 2lfe in. Now for tome field experience on reresulta. The municipal job deacribed above la felt by the plant operators to give a 2 to 4% improvement in boiler efficiency, considerably redueed soot de posit in the rear passes, a higher fur nace temperature and a resulting lower flue-gas temperature. Jets operate con tinuously and no disturbing effect has been produced on the combustion con trol. percent of unburned combustibles (2) increases nitrogen and oxygen readings. Operating the Jets. Smoke Indicators ore a must for helping the fireman do* cide whether jet action is needed. Most indicators suffer from a tendency of the lens to become dirty and give false read ings. A dustproof box, covering both sending and receiving instruments, fil ters air drawn in around the instru ments and keeps the lens dean. For further practical information on. applications, we refer you to the Technical Report No. VII, written by W ,S Major, of Bituminous Coal Research, Inc, and R B Engdaht, of Battalia Memorial Institute. ?*$ 1948 1679) 73