US2689456A - Open cycle gas turbine and cleaning means therefor - Google Patents

Description

R. B. WHITE Sept. 21, 1954 OPEN CYCLE GAS TURBINE AND CLEANING MEANS THEREFOR 2 Sheets-Sheet 1 Filed June 22, 1951 QQ Q Iv Q W INVENTOR. 2 5. Wfi/fe 2 Sheets-Sheet 2 L 1 B W L 9 t u T R 3E 91/ W 2 QR EM M E W Q\ E w T Q M Islll nmm h 9 IIIII W UV BY M R. B. WHITE OPEN CYCLE GAS TURBINE AND CLEANING MEANS THEREFOR Filed June 22, 1951 Patented Sept. 21, 1954 assaisc O EN oYoLE GAS TURBINE AND CLEANING MEANS THEREFOR .Roy B. White, Baltimore, Ma, assignor to maminous Coal Rescarch ,.lnc., Washington, D. (3., a corporation of Delaware Application June 22, 1951, Serial No. 233,021 a This invention relates to multi-stage axial flow gas turbines incorporating means for effecting cleaning of fouled last stage blading elements.

In the operation of multi-stage axial flow gas turbines, and particularly those used in systems wherein the motive fluid is generated by the pressurized combustion of pulverized coal, it has been found that, in an open-cycle system wherein the turbine exhausts directly into the atmosphere, there is a localized fouling of the last stage rotor blades by deposits of a sooty nature. This condition is associated with the operation of turbines wherein the combustors are of the cold walled type and continuously-burning oil flames are used toinsure positive ignition of the pulverized coalair flame. Where gas turbine power plants utilizing motive gas generated from the pressurized combustion of pulverulent solid fuels are used in locomotives, variations in locomotive speed are obtained by varying the rate of feed of pulverulent solid fuel to the combustor.

It has been noted that under conditions of locomotive operationwhere there are a multiplicity of starting periods 1 and decelerating or stopping periodsdeposits of a sooty natureare deposited onlyon-the last stage rotorblades of the multistage axial flow turbine. These deposits are readily removed by hand tools, but such cleaning operation :requires the dismantlingof at least the discharge endof the turbine casing in order to permit access to 'the fouled rotor blades.

Ithasnowbeen found that the fouling on the last'r'ows of multi-stage axial flow gas turbine Claims. (01.60-49.46)

rotor blades can be removed 5 without opening the casing by providing means for directing jets of vaporous fluids against the fouled portion of the affected'blades. This is essentially effected by providing symmetrically disposed jet devices mounted in the turbine casing and directed against the last row of rotor blades. The devices used may comprise a long single nozzle extending the length of and in radial alignment with the radially disposed rotor blades. 1 The cleaning may be effected by injecting fluid through such nozzles, which, as noted, are juxtaposed to the affected blades so that the jets of fluid are projected against the fouled surfaces of the blades as they severally rotate past the fixed nozzles. The fluids used may comprise hot or cold air, steam, and water, with or without cleaning agents, as well as suitable solvents. Instead of a long single nozzle in the jet devices, a multiplicity of aligned small nozzles may be used. The cleaning fluid may be supplied from a separate source, or where air is used, may be supplied from the air system of the turbine plant, particularly in view of the fact that the greatly reduced pressure obtaining inthe discharge end of the turbine will permit the use of low powered jets.

It. is, therefore, among the features of novelty and advantage of the present invention to provide improved means for cleaning fouled last stage rotor blades of multi-stage axial flow gas turbines which are powered by motive fluid generated in pressurized combustors utilizing fuels which liberate applicable amounts of solid residues.

It is also a feature of novelty and advantage of the invention herein to provide multi-stage axial flow gas turbines incorporating means for clean ing fouled last stage rotor blades, as well as com trol means for operating the cleaning means, which means are operable from a central panel or control board.

The above and other desirable features of novelty and advantage will bemore readily appreciated by referenceto the specification and accompanying drawings, certain preferred embodiments of the invention being shown, by way of illustration only, as it is not intended to be limited to the specific form illustrated, except as such limitations are clearly imposed by the appended claims.

In the drawings, like numerals refer to similar parts throughout the several views, of which Fig. 1 is a schematic showing of apulverulent fuel burning gas turbine power plant;

Fig. 2 is a fragmentary detailof the low pressureend of a gas turbine rotor having five stages of turbine blades and showing the location of fouling deposits on the last stage blades;

Fig; 3 is a fragmentary section of the low pressure end of a multi-stage blading gas turbine with parts of the casing removed to show the mounting of the cleaning jets with respect to the last stage of blading;

Fig. 4 is a schematic view illustrating the mounting of a cleaning jet with respect to a rotor blade;

Fig. 5 is a perspective of a cleaning jet having a single nozzle slot, and

Fig. 6' is a view similar to Fig. 5,'showing a plurality of aligned jets in the cleaning nozzle.

Referring now to the drawings, there is shown a gas turbine power plant adapted for the generation and use of motive fluid prepared by the pressurized combustion of pulverized coal fed to a.

combustor as a streaming entrainment of solid fuel particles in a combustive air stream and which system includes coarse and line ash separators in the gas discharge line from the com- 3 busters, the clean gas being delivered to a use device such as a gas turbine, which discharges its exhaust to the atmosphere through a regenerator wherein compressed air supplied by a main air compressor driven by the gas turbine, is preheated and supplied to the combustor to be heated furtherpbythe burningaof the fuel, to form the turbine motive-fluid.

As shown in Fig. 1, suitable generators are coupled to the turbine output shaft. The power plant illustrated schematically ..1 lis-iof the type shown and claimed 'inPatent No. 2,533,866, issued December 12, 1950, to John I. Yellott.

Considering the specific detailsoftthe present invention and with more particular reference to Figs. 3 to 6, there is shown ai-turbinezcasmgdil mounting a rotor I I, incorporating multiple rows of blades, and having a last row of blades,=sever ally indicated by the numeral l2. Pairs of jets 13 are mountedd i8flzrl'egreesrapartemthe'srotorrcaswith the :nozz'les directed against time. :last stageorwtermina'l row of:bl adesr IE2.v The jets-4153 may be secured in the casing in anyasulitab'le'lmanmen and arerconnectedtto :a; feed. line: t4.,:monnted intheficasing'wall, which line is connected to a suitable 'fluidvsupply 1.15., comprising 'a :cieaning fluid tank and pump, EaSlfihOWlfll in :ZEig. i1. .sAs shown-more in: detailiiniFigs. 52. A, I thee-sooty deposit: t5, described above, 1 is localized .i-and? :wi'll formAm'ai-nly at; :the" trailingxefigesiof:the sconvex surfaces :of. =-the. terminal :rotor blades. f 12. The iietrof cleaning. fluid i I: issn-ing:frm ithe'nozzle .1 I33 will-sweep thesrotating; blades. 1 2, .andxemovexthe deposits, 1-6. rEBy providing :two or iamore. ttsymmetrically arranged; jets:the terminal orllast stage biaidesrarersubiected to can .accel-eratedv scouring action which serves to remove the .depositsrmore readily. 'As 'shown 5,; the jet; of "fluidimay beproduced'by-a longitudinalslot E: jet $3.. ;An alternateiiorrm.asiliustrateiiinllilighv omprises a; longitudinal array-:of aperturesror smallnozzl'es t8. S'I'he amid. introduced through line; I :.may comprise 'air, waterg 'or steam, andzthellikegfrom external sources. lniternativelyt-air mayibe'taken from the main compressor.

The cleaning of the fouled blades is bestieffeeterbwhenthe turbinefis operating atsiowsspeeds, as thewstartingrfand --"st.opping operations. Under-:=such :;low speed conditions, the. jets: are much more-reflective: in reaching ztthe nblaade: surfaces -.than;'when the rotoris turning, atiiiligh speeds,,-=and=ithe motive fluidis issningwfrom-zthe bladeipassages at "high velocity.

The jets, asgspreviously noted aretpreiierably mounted symmetnicaliy, radial juxtaposition to 2 the last; stage rotorf blades, tow eliminate =the unbalance which would result from the; presence of 1a -.silngle, g'jetvora unsymmetrica'lly disposed multiple jets.

-.It will now be appreciatedthat there hasbeen provided:. a novel apparatus 5 for cleaning 2 fouled last stage turbine blades of multi-stage axialfiow gas-turbines of pulverized coal-burning power plants, which cleaning apparatus requireslbuta of structure-and without requiring any alteration of existing turbine structures cor designs.

"What is claimed is:

"1.I'n an axial "flow. gas turbine ,powenpla'nt comprisingpulverized coal .supply. means, a .pres- 4 surized combustor, a pressurized air line and a compressed air supply therefor, means for transferring pulverized coal into the air line whereby to form a combustive fluid, means for feeding the combustive fluid to the combustor, and a multistage axial flow gas turbine in fluid communication-was the combustor, :the: improvements comprising jetmeans in the zzturbine :casin'gzefiective to direct cleaning blasts against the last stage trotor blades, and cleaning fluid supply means coupledtosaid jetmeans, whereby said last stage rotortbl ades arecleaned while the turbine is in operation.

.lyMultisstageiaxial flow gas turbine according toelaim- 1,-eharacte1ized by the fact that the fluid =supply=means comprises an air line coupled to the. compressed air: supply.

3. In a multi-stage axial flow gas turbine char acteri'zed by the fouling of the last stage rotor blades with sooty deposits, the improvements comprisin gejiet me ans juxtaposeditothe lastlst-age rotorcblades; andcmeans .forssupplying: a: cleaning .to. said; je-tzmeans, whereby the fluid pmjectedragainst the 'fouledfiblades and-theriblades areycleaned iirhiletheiturbine isrotating.

1.4. ea pelt-purging, "openacycle multiestage axial flow. gasturbinerfonuse; asuthegprimelmoyer in: generatingelectric locomotives, and particularly adapted for: use with motive: fluids which deposit foulingmaterial on thezlast-stage rotonbladesthe improvements comprising jet. cleaning. means symmetrically mountedpin the turbine; :casing:,in radial juxtaposition :to the .;said vlastestagerrotor blades, and cleaning. fluid supply means; coupled to; saidjetqcleaning means; whereby the cleaning fluid-sis projected against the rl'zLSt rstage x'mtor blades, the blades are cleaned whileithe turbi-ne rotor is; rotating.

5. Ina generating electricflocomotive luding generators powered a :multi-stage axial flow gas turbine, anda motivezfluid generatorx'for the; turbine, ithezmotive 1 fluid being; characterized by the: deposition of fouling materialon theirlast stag-e blades of the :turbine rotor, --the improvemen-ts comprising jet cleaning means: syn-imet ricelly nicunted in then-turbine easinga,-in-;.radia1 juxtaposition --to the saidibladesgand cleaning; fluid .suppl-y means coupled to said iet means, whereby cleaning flair-1 1sdischarged against. the fouled blade su-rfacesand the surf-aces-areeoleaned while the-turbinarotorisrotating. Y Y

.References Cited; in thelfilefofthis atent. UNI'EED' STATES LlFATENTS,

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