United States Patent'".Office
This invention relates to apparatus for heating, subsurface geological deposits in. situ in their natural condition in the ground for the purpose of recovering valuable substances in liquid and/or gaseous state. Examples for sub-surfaces deposits in consideration are. shale strata, tar sand layers and sulphur deposits.
It is known in prior art to perform the heating by means of vertical holes or channels bored down from,the surface on the earth into or otherwise produced in the deposit to be heated. Said holes or channels are entered toy tubular heating members emitting their heat to. the: surrounding part of the deposit. The heat may be generated in several ways, for example by electricity in the manner disclosed in the French Patent No. 1,013,679. It is also possible to circulate a heat yielding medium such as superheated steam, for example, through the heating, member. A further possibility is to create a combustion in the heating member. This last, alternative is particularly advantageous in the exploitation by heating of fuelcarrying deposits, since considerable quantities of combustible gases generated by the heating process can be used directly as fuel in the continuing heating process. Said gases which otherwise are difficult to employ, in particular if they are of a composition making their condensation difficult, can thus directly come to economic application instead of being burnt in a power plant producing electric energy which roundabout way would cause considerable losses of energy.
When placing a conventional gas burner in the tubular heating member to be heated by combustion, the distribution of heat along the wall surrounding, or outer casing of the member will become very unequal, the portion adjacent the flame generated in the combustion becoming much more heated than other wall portions. In the heating of deposits or strata in their natural condition it is a desideratum that the whole part of the heating member located in the deposit or stratum to be treated is heated to at least approximately. the same temperature. In order to accomplish such equal distribution of heat generation of a plurality of flames on different levels has been proposed in the above cited French patent. It has proved difficult, however, to attain for each: flame the. most appropriate proportion between the quantities supplied of gaseous fuel and combustion-sustaining medium such as air or oxygen.
In order to overcome said inconvenience, one primary object of the invention is to provide a heating apparatus of the type specified with means for supply of fuel and combustion-sustaining medium to each flame in suitable proportions for ensuring a combustion by which the wall of the heating member is heated uniformly over a predetermined length.
A further object of the. invention is. to provide an ap
paratus of the type specified with means adapted to produce thorough intermixture of gas and combustion-sustaining medium supplied to each of the flames in order to ensure complete combustion.
Further objects and advantages of the invention will be apparent from the following description considered in connection with the accompanying drawings which form part of this specification and of which:
Fig. 1 is a side view of an apparatus embodying the invention, part of the outer wall or casing being cut away.
Fig. 2 is a cross-sectional view of the apparatus shown in Fig. 1 but presented in an enlarged scale.
Fig. 3 is a sectional view following line III—III of Fig. 2.
Referring to the drawings and in particular Fig. 1, the apparatus has a plurality of annular burner members generally denoted by 10 and located in the interspace between an outer wall or casing 11 encasing said burner members and an inner wall or tube 12 disposed substantially concentrically with the outer wall or casing .11. The spacing of the burner members 10 from one another is dependent on the distribution of heat desired along the outer casing 11.
It may be mentioned that the casing 11 and the tube 12 are presented in Fig. 1 in different scales with respect to their vertical and horizontal dimensions. In the vertical dimension, said members may in reality often have a length of about 20 metres, for example, whereas in the horizontal dimension the outer diameter of the casing wilr as a rule be less than 10 centimetres.
The tubular outer casing 11 is sealed on both ends, but adjacent the upper end which is intended to remain above the surface of the earth, said casing is provided with a connecting tube 13. From the same end of the casing 11 the upper end of the inner tube 12 projects upwardly. This projection is provided with two connecting tubes denoted by 14 and 15, respectively, and opening into the tube 12 at diametrically opposite points.
As will be seen from Fig. 3, the tube 12 is subdivided by a longitudinal partition 16 into two channels 17 and 18, respectively, of which the one channel communicates with one and' the other channel with the other connecting tube 14 or 15, respectively.
The burner member 1© is a hollow annular body carrying a plurality of nozzles. The annular body is in sealing connection attached to the inner tube 12, tout has no larger radial dimension than to leave a free annular space between its outer periphery and the outer casing. 11. The member 10 is composed of three parts, viz. an upper part 19, a lower part 20 and an intermediate part 21.. The. nozzles; are disposed in groups each , of which comprises two nozzles located the one within the other. Fig. 3 presents four groups of said type disposed on one annular burner member, but it is to be understood that more or less than four groups of nozzles may be applied onto one burner member. Of the two nozzles belonging to each group, the one designated by 22 has a. larger diameter than:the other designated by 23, as will be apparent,, from Fig. 2. Both nozzles have approximately the same . longitudinal dimension and are placed substantially concentrically the one within the other, but the nozzles 23 having the lesser diameter are disposed so as to extend from a lower level than the nozzle 22 having the larger .diameter. The narrower nozzle 23 will thus terminate' inside the surrounding wider nozzle 22 at a lower level than that of the edge of the opening of said nozzle 22. The narrower nozzle 23 is rigidly secured to and entirely penetrates through the intermediate part 21., Due to the cup-like shape of the lower part 20. an annular.passage 24:. is formed, the narrower nozzles 23 communicating with said passage which also communicates with, the channel 18 toy holes 25" disposed in the wall of the inner tube 12.