US2592887A - Hot-water heating system - Google Patents

Description

April 15, 1952 FRENGER 2,592,887

HOT-WATER HEATING SYSTEM Filed Feb. 7, 1947 Patented Apr. 15, 195:2

Application February 7, 1947, Serial No. 727,004 In Norway October 20, 1939 Section 1, Public Law 690, August 8, 1946 Patent expires October 20, 1959 Claims.

The present invention relates to hot water boilers, and especially hot water boilers of the type having a water jacket (that is a hollow wall filled with water and surrounding the furnace proper) and an economiser portion (that is a heating surface located outside of the furnace proper and subjected to the action of the combustion gases), preferably for stoker or wood firing.

Boilers of said type are extensively used, especially in connection with stoker furnaces, due to the material advantages derived from the use of such boilers. However, corrosion of the heating surfaces of such boilers is frequently observed in hot water boilers of this type. This is due to the fact, that in operation of hot water boiler systems it is necessary to use such low temperatures, that the water vapours contained in the combustion gases are condensed upon the water cooled heating surfaces of the boiler. For obviating this drawback it has been suggested that such heating systems being provided with a so-called shunt coupling arrangement enabling the boiler to be operated at a high water temperature of say 80-90 C. This arrangement, however, does not remove the objectionable corrosion feature because of the fact that the water returning from the heating system or radiators is returned into the boiler at so low a temperature, especially in the period of transition, that parts of the boiler surfaces attain a temperature lower than the condensation temperature of water vapour at the partial pressure in question, as a rule about 40 C. This will cause corrosion of the boiler surfaces, the sulphur of the fuel, now contained in the combustion gases, forming sulphuric acid and sulphurous acid, which in short time may fret through the boiler surfaces. The parts most vu1- nerable in this respect are those parts of the boiler surfaces which are located outside of the furnace and which consequently are not directly touched or irradiated by the flames. Thus the economiser portion of the boiler, which is per sev the least accessible part, is corroded to a substantial degree.

The present invention aims at obviating the drawbacks mentioned above, and comprises to that end several features and arrangements in hot water boilers of the type in question, which features and arrangements will be explained below.

The annexed drawing illustrates by way of example embodiments of a hot Water boiler according to the invention.

Fig. 1 shows a vertical section thereof on the line A-A in Fig. 2.

Fig. 2 is a horizontal projection, the top half of which shows a section on the line 11-15 in Fig. l, and the lower half of which shows a section on the line E-E in Fig. 1. v

Fig. 3 shows a section on the line B'-'B in Fig. 1.

Fig. 4 illustrates on a larger scale a section through the upper wall of the header.

Figs. 5 and 6 show, in perspective view and in vertical section respectively, a modification ac cording to the invention.

Figures 1-3 show a stoker boiler, which I is the furnace space, which is surrounded by a jacket.

The combustion gases flow from the furnace l throrgh the gas flue 3 of the boiler into the exit flue The interior path of the circulation system of the boiler may be traced as follows: starting at 5, the circulation moves downwards in the front jacket 2, through the openings 6 at the bottom of the bciler into the lateral side jacket 1. Here a portion of the boiler water rises into the box [8, whereas another portion proceeds through openings 9 and is distributed into a set of tubes ID, from where it passes through collecting headers I l into said mixing box [8.

In order to assist this interior path of circulation, transverse partitions such as at 2 I, may be arranged in the top portion of the boiler as shown,

which partitions divide the water jacket area into two parts or zones, in such a manner that the water will flow downwards in one of the Zones at 5 in jacket 2 (at the left in Fig. 1) and upwards in the other zone consisting of the side jackets l and the back jacket (at the right in Fig. 1).

In the boiler the highest temperature will be attained. at 8, and the lowest temperature at 5. The outer circulatory path extends from tubulation [2 into the collecting chamber l3 and through holes M in the bottom of the mixing" box l8 into said mixing box to the area [5 and out through the tubulation l6, so that the colder return water is introduced at l2, the warm water leaving at l6. Through the holes I4, which are preferably inclined in forward direction towards the front side of the mixing box, the cold return water is intimately mixed in the mixing box l8 'above the holes M with the hottest Water coming 3 from 8, whereby the temperature of the water leaving the boiler at IE will be substantially equal to the temperature of the water re-entering the interior path of the circulation system of the boiler at 5.

The result of the present invention is that no surface of the boiler, normally susceptible to corrosion has a temperature lower than the temperature of the Water passing to the outer circulation system, and if the temperature of the outgoing water is at all times kept above the temperature critical to corrosion, which as a rule is about 40-45 C., no deposit of tars or similar materials will occur in the boiler, and corrosion due to too low water temperature will be eliminated.

It is not always practical to let the return water conduit or conduits open directly into the space for transient flow, and in such cases the return water pipe from which the return water passes into the space for transient flow may, according to the invention; enter into a separate collecting chamber, below the mixing chamber which collecting chamber is thus situated in a part of the furnace less subjected to corrosion and the like, so that the cold return water will first flow along a heating surface, on which a low water temperature is substantially harmless.

As will be seen a very thorough mixing of boiler water and return water is obtained, and the inclined outlet openings l4 (see Fig. 4) are effective to increase the circulation in the boiler.

Moreover the said circulations will take place, as shown, in a natural way due to the temperature differences, and due to the relative arrangement of the return water inlet.

In hot water boilers of this general design it has been suggested to provide a wall, as indicated at 2B in Fig. 1, extending from the bottom of the water jacket I, so that the heater water contained within the furnace walls is provided with added heating surface prior to the introduction of said water into the tube set. While such an arrangement is not necessary in this connection, it may be used, if desired.

In the embodiment shown in Figs. 1 to 3 inclusive, the openings M for inlet of return water are situated between that opening through which the hot water flows into the space for transitory flow, and the opening for downward flow.

The invention is, however, not restricted to the embodiment of Figs. 1, 2 and 3. Thus the inlet of return water may take place topmost, at any one of the boiler sides, and the like. Thus Fig. 5 is a perspective view, and Fig. 6 a vertical section of an embodiment, showing how the device in question may be arranged within the water jacket of a boiler.

If it is desired that the water issuing into the outer circulation circuit shall have a lower temperature than the water entering from l5, a by-pass conduit may be arranged from the chamber 43 through a valve 40, so that a portion of the return water is returned to the outer circuit.

This is diagrammatically indicated by dashdotted lines at the upper left of Fig. l.

The invention is also of great value for heaters fired with wood or peat, in order that pitch or tar deposits on the heating surfaces shall be avoided.

I claim:

1. A hot water boiler having a water jacket and an economizer portion provided with heating surfaces, said economizer portion connected to 4 said water jacket in water circulating relation, means providing a space for transitory flow and admixing of water of varied temperatures located substantially at the high point of said jacket, and having inlet means for heated water from said jacket, inlet means for heated water from said economizer portion, inlet means for return water, and outlet means for heated admixed water, said inlet means and outlet means being arranged for flow of water therebetween and within said transitory flow space means in such spaced relation that said return water, the hottest boiler water, and the heated water from said economizer portion are intimately admixed prior to flowing into said outlet.

2. A hot water boiler having a water jacket provided with heating surfaces and an economizer portion provided with heating surfaces, said economizer portion connected to said water jacket in Water circulating relation, means providing a space for transitory flow and admixing of water of varied temperatures located at the top of said jacket, and having inlet means for heated water from said jacket, inlet means for heated water from said economizer portion, re-

turn water inlet means adjacent the heating surface provided for the top of said jacket, and outlet means for heated admixed water, said inlet means and outlet means being arranged for flow of water therebetween and within said transitory flow space means in such spaced relation that said return water, the hottest boiler water, and the heated water from said economizer portion are intimately admixed prior to flowing into said outlet.

3. In a hot water heating system of the type having radiators, a boiler, said boiler including a furnace box, a water jacket surrounding said furnace box and an economizer portion connected to said water jacket for circulation of water from said water jacket through said economizer portion in heat exchange relation and back into said water jacket, outlet pipes connected to the upper area of said water jacket for flow of heated water to said radiators, intake pipes connected to the upper area of said water jacket for flow of return water from said water circulating elements, said intake pipes and said outlet pipes being in such spaced relation that the water flowing into said outlet pipes is an admixture of said return water and the hottest water contained in said boiler.

4. In a hot water heating system of the type having separate radiators for heat exchange, a boiler comprising a furnace box, a water jacket surrounding said furnace box and an economizer portion connected to said water jacket and consisting of water conduits heated by the hot flue gases escaping from said furnace box into said economizer portion, said boiler including inlet means for return water from said radiators to the top section of said water jacket, inlet means for hot Water from the side and rear sections of said water jacket and from said economizer portion to said top section and outlet means to said radiators from said top section, said inlet means and said outlet means being arranged in such spaced relation that said return water, the hottest boiler water and the heater water from said economizer portion are intimately mixed prior to flowing into said outlet.

5. In a hot water heating system according to claim 4 wherein the top section of the water jacket of the boiler is divided into two areas, the lower area comprising a collecting box and the upper area comprising a mixing box, said collecting box separated from said mixing box by an apertured platform, said return water inlet means connected to said collecting box, said inlet means for hot water from the side and rear sections of said water jacket and from said economizer portion and said outlet means connected to said mixing box, whereby said return water is in heat exchange relation with the top heating surface of said furnace box and flows upwardly through said apertured platform into said mixing box for admixing.

GUNNAR, FRENGER.

REFERENCE S CITED The following references are of record in the file of this patent:

Number Number 15 70,807

UNITED STATES PATENTS Name Date Owen et a1. May 17, 1887 Stettinius July 4, 1899 Restner June 25, 1918 Edsen June 29, 1920 Williams June 16, 1925 Hulsmeyer June 24, 1930 Ostermann Jan. 7, 1936 Swars Dec. 29, 1936 'Kolb Jan. 14, 1941 FOREIGN PATENTS Country Date Norway Aug. 5, 1946

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