US2291730A - Radiation superheater - Google Patents

Description

Aug. 4, w42.

J.' KRUG ETAM RADIATION sUPERHEATER lFiled March 13, 1940 S s TulJllm el@ Patented Aug. 4;, 1942 EJNHTED STA'ES P'E'ENT @ENCE RADIATION SUPERHEATER Julius Krug, Berlin-Wiimersdorf,

and Hans New York, N. Y.

Appiication March 13, 1940, Serial No. 323,690 In Germany May 25, 1939 2 Claims.

The invention refers to a superheater which is installed in the combustion chamber of boilers, especially radiation boilers which are fired with fine distributed fuel. According to the invention the bare superheater tubes are distributed along two parallel walls which also run parallel to the direction of the fuel discharge. At low rating, when one or more burners are shut off, a more even superheating of the steam will be accomplished regardless of how the re gases cover the combustion chamber. It is desirable hereby to split up the superheating surface in two or more sections and arrange them parallel to the steam flow. Each one of these sections should be made up of several groups of tubes whichshould be arranged one behind the other in the steam ow. This way the steam velocities, the cooling of the tubes and the superheating in the radiation superheater can be increased.

According to the invention the groups of superheater tubes are connected to one lower and two upper headers. The tubes coming up from the lower header run alternately into the upper inlet and outlet headers. Every tube heading into the upper outlet header is therefore a continuation of a tube coming from the inlet header, resulting also in increased velocity in the tubes and increased cooling of them. At the same time it is possible for the tubes that carry steam of higher temperatures to expand independently of the other ones and each group of superheater tubes can be drained through the lower header. The connecting tubes between the inlet and outlet headers of the groups of tubes laying on top one another will preferably be located underneath the boiler roof so as to use them for heating surfaces. To get an even superheat and even wear on the superheater parts in the different sections, each group of tubes of each superheater section will be distributed to the walls of the combustion chamber opposite one another.

It is recommended to arrange the groups of tubes of one superheater section opposite the different groups of tubes of the other superheater, so that for instance in each case the groups of inlet tubes will be located opposite the groups of outlet tubes. This arrangement also serves the purpose of getting even superheat in the various superheater sections, giving consideration to the possible arrangement of burners in the front wall of the combustion chamber or stokers, as for instance with a traveling grate stoker the heat of the flame near the back wall will be considerably higher than near the front wall. With the suggested arrangement an uneven heat reflection in the combustion chamber and along its walls will be equally distributed to the various superheater sections.

One embodiment of the invention is shown in the accompanying drawing in which Figure 1 is a vertical section through a boiler unit embodying the invention;

Figure 2 diagrammatically shows the header arrangement for the radiant superheater;

Figure 3 is a section through the radiant superheater on line 3 3 of Fig. 2.

Figure 4 shows a plan view of the arrangement of the sections of the two radiant superheaters.

The furnace I is provided with pulverized coal burners 2 which direct the coal across the furnace. The furnace is provided with steaming tubes 3 on the front and rear walls as well as on the oor and roof, which are connected for supply at the bottom to a common drum 4 and deliver to the intermediate drum 5. Lower drum l is fed by downcomers t from the steam and water drum 1. The steam and water mixture deliveredto drum 5 is substantially separated into steam and water and the water is returned through downcomers 8 to th'e lower drum 4, while the steam passes through risers 9 to upper drum Ii) and thence through tubes il to the steam drum l. The two side walls of the furnace are lined with tubes I3 of a radiant superheater which are connected at their' bottom to header I ll and at the top to headers I5 and I3 and I9. Steam leaves drum 'I through tubes I5 which are uniformly distributed longitudinally of the drum and passes through tubes Il which uniformly distributes it to the upper header I S. The steam then passes down through part of the tubes I3 to lower header I4 and through the remaining tubes i3 up to header I9 from which tubes 20 lead it to a convection superheater, not shown. Above the furnace there are located tubes coils 23 of an economizer which are arranged for radiant heat absorption and l deliver the heated water as well as any generated steam into the upper drum lil. From header Il) water flows via tubes I2 to the drum I while the separated steam flows through tubes I I. The tube coils 23 of the economizer are assembled in the form of fiat walls which are substantially spaced apart from one another and are supported by bifurcated tubes 35. The latter'are connected to header 35 which is supplied by downcorners 3% from drum 'I and deliver to the upper drum I0. The bifurcated tubes in this way serve.as additional heating surface of the boiler. After passing through the roof of the boiler they are bent 'at right angles and are supported on their vertical portions by carriers 31 which in turn are hung from the boiler structural work.

'Ihe products of combustion from the furnace after leaving the furnace flow over the economizer 23 to which they give up mostly radiant heat and thence may pass over a convection economizer, a convection superheater, a second convection economizer and thence through an air heater before entering the breeching.

The radiant superheater consists, according to Figs. 2 and 3, of inlet header I8 to which steam is led by tubes I1 from which header the radiant tubes lSa lead down to header 14a from which' last header the steam rises through ltubes |31) to header Ia. Tubes l3a and Mb alternate continuously so that one tube l3b`represents the continuation of an adjacent tube l3a. From header ia tubes di! convey the steam to header l5b thence through tubes I3c to header |41)y and thence through tubes I3d to header I8. Steam leaves h'eader l 9 by means of tubes 20.

In the form shown there are two individual superheaters which are connected in parallel with regard to the steam flow. Further, each of the superheater half-sections consists of two serially connected tube groups |3a and |311 or I'3c'and i3d. In the form shown in Fig, 4, the arrangement is such that each superheater h'alf-section is located on opposite side walls, i. e., the primary section A of one superheater is located on one side wall alongside the secondary section B of the other superheater and opposite the primary section A' of the other superheater which in turn is adjacent the secondary section B of the first superheater. In this arrangement the front superheater section A or A respectively of the one side Wall is connected with the rear superheater group section B or B', respectively, on the opposite side Wall, by connecting tubes 40 which cross one another.

What We claim is:

1. In a furnace provided with means for introducing fuel into the latter through one or more Walls thereof; a pair of superheaters each having tubular heat absorbing elements mounted on opposite walls of the furnace, each superheater comprising a primary section disposed on one furnace wall contiguous to the secondary section of the other superheater and facing the primary section of the other superheater; tubes extending subs'tant'ially diagonally across the furnace for connecting the primary section of each superheater in series with its secondary section.

2. In a furnace; a radiant superheater section comprising a plurality of parallelly disposed tubes extending vertically of a Wall of the furnace; a header extending along said Wall and having the lower ends of all said Vtubes connected thereto; a pair of headers extending along said wall with the upper ends of alternate tubes connected to one header of said pair and said ends of the remaining 'tubes connected to the other header of said pair; a second similarly arranged superheating section mounted on the opposite Wall of the furnace diagonally opposite said rst superheater section; connections for supplying steam to one upper header of the first Vsuperheater section and taking it from the other upper header of "said second superheater section; and tubes interconnecting the other upper headers of said superheater sections so that steam flows in series through said sections.

JULIUS KRUG. HANS COERPER.

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