US1573427A - Utilization of waste heat of furnace gases - Google Patents

Description

Feb. 16 1926.

H. H. sTouT UTILIZATION OF WASTE HEAT 0F FURNACE GASES Filedv sept. 17, 1920 l l f Patented Feb. 16, 1926.

HARRY HOWARD STOUT, OF DOUGLAS, ABIZONI'A.

UTILIZATION OF WASTE lHEAT OF FURNACE GASES.

Application led September 17, 1920. Serial No. 410,998.

To all whom t may concern:

Be it known that I, HARRY HOWARD STOUT, a citizen of the United States, residing at Douglas, in the county of Cochise 5 and State of Arizona, have invented a new and useful Improvement in Utilization of Waste Heat of Furnace Gases, of which they following is a specification.

This invention relates to waste heat boilers for generation of steam by utilization of the waste heat in gases passing from metallurgical furnacesp cement kilns, or other furnaces producin hot gases containing more or less dust, ume, or suspended material. A serious diiiiculty in the operation of such waste heat boilers arises from the deposition of such suspended material on the boiler tubes, particularly where the temperature of the gases is so high that such material deposits in fused or partly fused condition, forming a hard adherent deposit.

These deposits clog the passages between the boiler tubes and interfere with the assage of the gases and also interfere wlth the transmission of heat from thegases to the boiler tubes, and it is necessary to remove the deposits from time to time, this requiring opening of the fire doors, or even shutting down the boilers temporarily while the boiler tubes are being cleaned, with resultling diminution in steam production.

The main object of this invention is to prevent or reduce the accumulation of such adherent deposits on the boiler tubes. A further object of the invention is to provide a Waste heat boiler construction in which the boiler tubes are'out of the direct path of the hot dusty gases so that such gases do not encounter obstructing surfaces tending to receive the fused or semi-fused deposits. Another object of the invention is to provide for absorbing heat from the hot gases by means which do not obstruct the flow of gases and for radiating the heat so absorbed to steam boiler tubes which are out of the direct path of the gases.

The accompanying drawings illustrate apparatus suitable for carrying out my invention, and referring thereto:

Fig. 1 is a diagrammatic plan view, partly in section, of a furnace and waste heat boiler installation embodying the invention;

Fig. 2 is a vertical section on line 2--2 in Fig. 1;

Fig. 3 is a transverse section .on line 3-3 in Fig. 2.

My invention is a plicable in connection with various kinds ok furnaces, for exam le, reverberatory, or other `metallurgical rnaces, cement kilns, or other furnaces or kilns whose eluent gases contain dust or fume constituent at such high temperature as to tend to collect on obstructing surfaces in a more or less fused condition. In Fig. 1 ofthe drawing I have, by way of example,

illustrated the application of the invention to a reverberatory furnace, indicated atl. An outlet flue 2 is connected to such furnace to receive the hot gases therefrom, the walls (including the top 3 and floor 4, as well as the side walls 5 of the tlu'e) being of suitable refractory construction, such as firebrick, so as to be adapted to be heated t0 high temperature by contact with the hot furnace gases.

Located alongside of the flue 2 are a series or plurality of steam boiler units 6, each mounted, for example, in a bay, recess or boiler chamber 7, beside the flue, so as to be out of the direct path of the gases pass- .ing inthe flue but exposed to radiation of heat from the opposite side wall as Well as from adjacent roof and floor portions of the flue, the water tubes 8 of said boilers being, therefore, heated largely by radiation. It will be understood that while the main gas stream passes in a general longitudinal direction through iue 2 Without passing in direct contact with the water tubes 8 in recesses 7, there are of course some local convection currents or eddy currents in said recesses and around said tubes. Some heat is therefore imparted to the water tubes by convection, in addition to' the heat derived by radiation from the hot walls of the flue facing the Water tubes. Said Water tubes preferably extend more or less in the direction of the gas iiow so as to minimize any obstructing elect they may present, but can be vertical, as shown at the right hand side of Fig. 3. Successive boilers, or boiler units, are preferably arranged alternately on opposite sides of the flue as shown in Fig. 1 so as to permit the exposed radiating portions of the side walls to be distributed with maximum uniformity throughout the length of the flue and on both sides thereof and therefore enable such veo radiating side walls t-o more uniformly and effectively take up the heat from the gases passing in the Hue.

In case any material collects on the boiler tubes it may be removed from time to time, the boiler chamber being shut oHl from Hue 2 at such time by means of a partition or curtain Wall 10, which is normally supported by suitable means 11 and is brought into position between the Hue and the boiler chamber, when required, the boiler tubes being then cleaned in the usual manner.

The gases may pass from Hue 2 through conduits 12 to additional heat utilizing means comprising steam boilers 13, mounted in boiler chambersor settings 14 in the usual .manner of Waste heat boilers, the gases Hnally passing by Hues 15 to suitable stack means.

The operation of the invention is as follows:

The hot gases coming from furnace 1 pass through the Hue 2 and give up a part of their heat to the Hue Walls, which are thereby heated to a high temperature and caused to radiate heat to the boiler tubes opposite or adjacent thereto. The boiler tubes also receive some-heat directly from the gases,

but as the gas 'stream does not impingedi-- rectly on the boiler tubes there is little tendency for deposition of suspended material on the tubes. The Hue presents suHicient heat absorbing and radiating surfaces, including top 3, Hoor 4, and the unrecessed portions of the side Walls 5, to reduce the temperature of the gases inpassing through the Hue to or below the fusing pointof any constituent liable to be deposited on the boiler tubes, and as the gases pass from the Hue they are therefore at such temperature that any suspended material theyimay contain is in solid conditions or sufficiently cooled to prevent the formation of a fused or semi-fused deposit. The eHiuent gases from the Hue 2 may therefore be passed `l'hrough the Water'tube, or other boilers 13, Without liability of forming an adherent deposit thereon, and any solid material that may collect on the tubes of such boilers may be readily removed.

In the application of the invention to gases from reverberatory furnaces used in copper smelters, the gases, as they leave the furnace, have a temperature of about 2300o F., at which temperature the suspended ma- ILerial in the gases tends to form a more or less molten deposit, and in passing through the Hue the gases should be reduced in temperature to about 1-100o F., at Which temperature the suspended material is solid.

My invention is applicable with advantage to other kinds of furnaces, for example, to cement kilns using Waste heat boilers and producing eHiuent gases containing fusible constituents; for example, alkali-metal compounds which tend to fuse onto the boiler tubes. This is especially the case Where an agent,vsuch as sodium chloride, is used to increase the volatilization of potassium compound from the raw mix in the kiln, and has heretofore been considered as preventing the use of such an agent where Waste heat utilization is required. By operation of the process above described, the gases from the kiln may irstbe reduced in temperature in a preliminary radiation boiler plant, for example, of the construction described, and the gases then passed through an ordinary Waste heat boiler installation to further utilize the heat thereof.

While I have shown the boiler units as arranged at the sides of the Hue through which the hot gases pass, and in alternate arrangement, it Will be understood that they may be arranged in any position adjacent to the gas stream but out of the direct path of the gas, and may be of any desired number and closeness of arrangement, according to the requirement of any particular case.

By reason of the suspended matter contained in the gasses passing through the Hue and adjacent to or alongside the boiler tubes considerable radiation may take place from such suspended matter directly to the boiler tubes, and in some cases, this may be an important factor in the operation of the boilers.

As shown in Figs. 1 and 2, means, such as a lWater pipe 20, may be provided at the bridge Wall below the outlet of the furnace 1, so that the molten slag will not break through into the boiler setting.

What I claim is: l

1. In combination with a furnace, a Hue adapted to receive hot gasses therefrom, and having a heat-absorbing and heat-radiating side Wall, and having a lateral recess opposite said Wall and in open communication with the Hue passage, steam boiler means in said recess, out of the direct path of such gases through the Hue, and adapted to receive heat by radiation from said side Wall, and partition means movably mounted adjacent to the flue and adapted to be moved into position between said recess and said Hue, to temporarily shut off said boiler means from the Hue.

2. Means for utilizing heat of furnace gases comprising a Hue for passage of the gases and having heat absorbing and heatradiating Walls, and a plurality of steam boiler units arranged along the Hue in open communication therewith and out of the direct path of the gases through the Hue, and in alternate arrangement on opposite sides of the Hue, so that the boiler units alternate with radiating Wall portions and a radiating Wall portion is opposite each boiler unit.

3. Means for utilizing heat of furnace gases comprising a Hue adapted for passage i of the gases and having heat-absorbing and heat-radiating walls,

and a plurality of 5 rect 'path of the each boiler unit jacent Wall portions of th heat by radiation from opg gases passing inthe Hue, being adapted to receive osite and adue, and partition means ada ted to be brought into position between the Hue and the respective boiler units to shut off any boiler unit from the Hue independently of the othenunits.

In testimony whereof I have hereunto subscribed my name this 31st day of August, 1920.

HARRY HOWARD STOUT.

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