THE FURNACE TO BURN FUEL INTO MELTED SLAG.

The invention relates generally to heat-and-power engineering, particularly, to the device for solid fuel firing, processing of the thermal and the thermal condensing power plants thermal condensing power plant ash wastes (AW) in melted slag, bubbled by oxygenated gas, and getting refuse-to-gas energy.

The vortex slag tap furnace chamber, containing a vertical cylindrical body with a slag-notch for melt outlet, a central gas discharge insertion for upper gas removal and a pivotal cruciform gas distributing insertion for limiting loss with gas and for gas temperature rise at the chamber output, is known (a.c. SU N' 1603136 class F 23 5/32 published in 1990) . The shortcoming of this embodiment is the high fuel-dust make, the complexity of the furnace construction, poor specific productivity, moreover, the high temperature of firing process results in the heightened nitric oxide content in exhaust gases.

The furnace for solid fuel firing in melt, containing a body, a tuyere ring with nozzles, a crown, a hearth, loading devices and attachments for liquid and gas combustion products outlet, is the closest to the suggested embodiment by its technical essence (RU Patent N?2031310 cl . F 23 C 11/00, F23 J 1/08 publ. 1995).

The shortcoming of the present furnace for solid fuel firing in melt is the absence of padded and embedded water-cooled caissons in the hearth construction, which mounting significantly increases the time of the overhaul life and provides the furnace trouble-free and stable operation.

The other shortcoming of the furnace is the equipment of hearth by a hard metal frame, which length and width exact calculation is practically impossible, in consideration of the refractory masonry growth during the period of the furnace run-up and its constant firing (all mass of the furnace masonry keeps on

growing pending 30-35 days since firing and till the growth termination) .

The third shortcoming of the furnace is that the power boiler- furnace conjunction isn't equipped by the gas seal device along the whole boiler girth, eliminating both the leak-in from atmosphere and the exhaust gases discharge through underpressure decrease inside the boiler.

The object of the invention is the availability enhancement of the furnace for solid fuel firing in melt by the development of the hearth and the hearth enclosure construction, mounting of the gas seal device along the furnace girth at the power boiler- furnace conjunction and the selection of the furnace optimal length.

The result is achieved in the furnace for solid fuel firing in melt, containing a body, an air tuyere ring with nozzles, a crown, a hearth, loading devices and attachments for liquid and gas combustion products outlet, by the padded caissons adjustment on the hearth surface in the zone of the intensive movement of the melted slag of under-tuyere area and by the embedded caissons mounting into the hearth masonry at the depth of 10-12 gages of air tuyeres with the interval equal to 1-3 items thickness of embedded caisson.

The hearth metal enclosure is assembled from separate non- connected sections, compressed by special devices both along the hearth length and width. The tightening studs are equipped by springs, holding extension force of masonry during its heating at the period of primary firing and constant furnace work until the growth termination. The enormous efforts, arising at the masonry growth, are eliminated by nuts untwisting at the tightening studs .

The mounting of the gas seal device along the power-generating boiler girth at the power boiler - furnace conjunction allows to

eliminate both the leak-in from atmosphere and the exhaust gases discharge through underpressure decrease inside the boiler.

The selection of the furnace optimal length makes it possible to decrease loss with low-grade heat and thereby to increase the power boiler heat rate.

The energotechnological aggregate is schematically represented on fig.l, the sectional view A-A of fig.l is represented on fig.2, unit I of fig.l- on fig.3, unit II on fig.2- on fig.4, the sectional view B-B of fig.l - on fig.5.

The energotechnological aggregate consists of the furnace for solid fuel firing in melt and the power boiler.

The furnace consists of the rectangular shaft 1, composed from the copper water-cooled caissons, the loading devices 2, the divider 3, dividing the furnace into two zones: the pre-firing camera 4 - the zone of solid fuel loading and preparation for intensive firing in the zone 1 of solid fuel complete firing, the arch of 26 lateral air tuyeres 5 with nozzles, the butt air tuyeres 6 of the pre-firing camera 4, the hearth 7, the divider 8 with the square pipe skids 9, the slag tap window 10 for nonstop slag tap, the lift tube 11, the spur devices 12 for periodic metal melt outlet, the hearth enclosure 13, the radiation shaft 14 of the boiler, the barrels-separators 15 and the boiler convective shaft 16.

The cross-section of the furnace 1 is represented on fig.2, the sectional view A-A of fig.l, where is shown that the furnace body with caissons has a variable cross-section, but the furnace hearth 7 is equipped by the padded 17 and embedded 18 caissons.

The furnace gas seal device, consisting of the refractory units 21, arranged along the radiation shaft 14 girth at the power boiler - furnace conjunction, the shell ring 19 of the boiler and the sandy bath, 20, is represented on fig. 3 - unit I on fig.l.

The hearth 7 construction with the mounted padded 17 and embedded 18 caissons is represented on fig.4 - unit II on fig.2.

The furnace hearth enclosure 13 consists of the separate metal sections. The hearth enclosure compressing devices, consisting of the linear 23 and the cross 24 studs with the strings 25 (fig.2 the sectional view A-A of fig.l) and the nuts, are represented on fig.5 sectional view B-B of fig.l.

The decrease of low-grade heat loss with water, cooling the caissons and the selection of the furnace optimal length are estimated according to the formula, deduced empirically:

a

U — X

1 - φ where

- the furnace relative specific productivity, t/m ² a day; β _s i - the furnace specific productivity, t/m ² a day omax _

PsI - the maximal furnace specific productivity, t/m per a day

B - the furnace length, m

S ^r - the desired furnace length, m b - the furnace width, m

<J cais ~ heat loss with water, cooling the caissons, kilowatt

(J si ~ heat loss with slag, kilowatt

The energotechnological aggregate operate as follows.

The solid fuel and ash wastes enter the furnace pre-firing camera 4 with the crown 26 and the butt air tuyeres 6 through the loading devices 2 and get the silicate slag melt, intensively bubbled by oxygenated gas. The said components are instantly assimilated by the melt, start heating, decrepitate to small pieces because of moisture and coal-volatile gases explosive evaporation and burn off in the melt. The ash wastes and coal are simultaneously warmed up to the melting temperature and turn into the fluid state under the influence of the melt bath high temperature. The fuel complete combustion and slag formation of the preset structure take place in the furnace shaft 1, and exhaust gases get the radiation 14 and the convective 16 furnace boiler shafts, where a steam with power conditions is generated.

The location of padded 17 and embedded 18 caissons in the furnace hearth (fig.2 and fig.4 - unit II on fig.2) at the depth h of 10-12 gages of air tuyeres 5 and the embedded 18 caissons mounting with the interval δ equal to 1-3 items thickness of the embedded caisson, provide the hearth masonry long-term work from its firing in the zone of the intensive movement of the under- tuyere area melted slag, since the masonry is protected by the skull stratum, instantly processing in the thermal dynamic equilibrium Qreceipt~Qconsumption (the heat receipt in this zone is equal to the heat consumption) .

All mass of shaft, equipped by caissons, rests upon padded caissons 17, trimming the load along the whole hearth surface, but the refractory masonry, growing both in length and width during the heating up period, smoothly slides on the undersurface of padded caissons 17, without crippling of masonry but cooling it. The location of padded and embedded caissons at the depth less than 10 gages of air tuyeres 5 can result in the lining

deterioration, situated lower than the last embedded caisson, which would sharply reduce the furnace lifetime.

The arrangement of padded and embedded caissons at the depth more than 12 gages of air tuyeres is undesirable, since the last embedded caissons would work in the metal melt zone, which is abnormally dangerous, considering explosion at ingress of water into the metal melt. The additional heat pick-up in the metal melt zone is undesirable too, because of the melt fluidity decrease.

The mounting of the embedded caissons 18 with the interval less than its one thickness would result in the lining overcooling and additional consumption of expensive copper for making supplementary embedded caissons.

The mounting of the embedded caissons with the interval more than three items of their thickness would result in the lining deterioration, because of the cooling decrease, and service life decrease of the furnace and the hearth.

The structure of the furnace gas seal device (fig.3 -unit I on fig.l) is created so, that the shell ring 19 of the boiler is protected from the fire side by refractory blocks 21, situated at the boiler girth. The shell ring sinking to the depth, corresponding Hhyd _r allows to eliminate both the leak-in from atmosphere and the exhaust gases discharge from the boiler. The hydraulic resistance Hftydr of the sandy bath 20 must always be

20-100 mm of water higher, than available pressure inside the boiler, that is:

Hhydr ^ ^* ^ ^" comb. gas/ ^■ where

Hhydr ~ hydraulic resistance of the sandy bath stratum to the depth of boiler shell ring sinking, mm of water/

P "com _b . gas ^~ exhaust gases underpressure in the boiler at normal mode, minus 10-20 mm of water;

P comb. gas ~ abrupt underpressure decrease in the boiler, turning into the pressure, plus 10-100 mm of water.

The enclosure 13 of the hearth 7 (fig.5 sectional view B-B of fig.l) is composed from the separate metal sections both from the butt and the linear hearth sides .

The non-connected sections allow to unload the hearth enclosure during the masonry growth period from the furnace runup and till the growth termination. Every section is compressed by the linear 23 and the crosscut 24 studs, equipped by springs and nuts. The springs are arranged directly on the surface of every section.

The equipment of the hearth enclosure 13 by compressing devices enables to realize the refractory masonry firing correctly and in line with "the firing schedule", which completely eliminate the conditions for high probability of the masonry breaking (decrepitation of bricks and even the masonry- bursting expansion) because of untimely eliminating of enormous efforts, arising at the masonry growth. Elimination of these efforts takes place by control of the springs 25 state and timely nuts untwisting at the linear 23 and the crosscut 24 studs. The sizes of the masonry growth widthway and lengthway are estimated by reference flags, established by every stud.

The decrease of low-grade heat loss with water, cooling the caissons, promotes the increase of the boiler thermal power, and the selection of the boiler optimal length is estimated according to the empirical formula:

Thus, an application of the supposed furnace for solid fuel firing in melt allows to enhance the hearth lifetime between overhauls by the arrangement of padded and embedded caissons in the furnace hearth at the depth of 10-12 gages of air tuyeres, counting from the padded caisson upper surface and with the interval between the embedded caissons equal to their 1-3 items thickness, but mounting of the gas seal device at the hearth- boiler conjunction, equipped by refractory blocks from the fire side and by the sandy bath from the cool side, allows to obtain tightness of the hearth-boiler conjunction by immersion of the boiler shell ring into the sandy bath. This provides that hydraulic resistance is always 20-100 mm of water higher, than possible gas pressure inside the boiler, which eliminates both the leak-in from atmosphere and the exhaust gases discharge from the boiler.

The mounting of the hearth enclosure from separate metal sections along its girth, compressed by the linear and the crosscut studs, equipped by springs and nuts, allows to eliminate great efforts, arising at heating of the refractory masonry in the period of its active growth, by unloading springs by untwisting of nuts at studs.

All abovementioned gives an opportunity for correct implementation of the refractory masonry without its damage.

The decrease of low-grade heat loss with water, cooling the caissons and the furnace optimal length are calculated according to the following empirical formula:

V iccaaiiss „ b a q _sl a + b a'= x

qsi a + b