Manifold for receiving gas streams from a plurality of parallel-working units

Abstract: Manifold (35) for receiving gas streams from a plurality of groups of gas purifiers (14, 16) arranged in parallel. The manifold (35) comprises a number of pipe parts (38a-d) with a successively increasing diameter forming a main channel in the manifold (35). A first pipe part (38a) projects into a second pipe part (38b), whereby, in the gap between the pipe parts (38a, 38b), a gap or connection channel (40b) is formed which is substantially parallel to the main channel formed by the pipe parts (38a-d). The second pipe part (38b) projects into the third pipe part (38c), thus forming a gap (40b) between the pipe parts (38b, 38c), and so on. Outlet tube parts (36a-d) from the cyclones (16a-d) are connected to the channels formed by said gaps (40b, 40c,...).

Description: The invention relates to a manifold for receiving gas streams from a plurality of parallel-working units according to the introductory part of claim 1. The manifold is primarily intended to receive purified gas from gas cleaners operating in parallel, for example cyclones in a PFBC power plant in which the combustion gases from a combustor are utilized for operation of one or more gas turbines. "PFBC" are the initial letters of the English expression "Pressurized Fluidized Bed Combustion". In a plant comprising a plurality of parallel groups of gas cleaners, it is important that the connections to a common manifold which receives the purified gas are so designed that the pressure conditions at the connections are equal. In prior art designs this is not the case, thus giving rise to different flows in the parallel-working cleaners. Therefore, it has not been possible to attain an optimum cleaning efficiency. In a PFBC power plant in which cleaners are located in an expensive pressure vessel and the gas is utilized for operation of turbines, it is particularly important for the cleaning plant to operate with optimum efficiency so that its size can be limited while maintaining a good dust separation and a small dust load in the purified propellant gases for the turbine. The invention aims at designing a manifold of the above-mentioned kind exhibiting equalized pressure conditions on its inflow connections. To achieve this aim the invention suggests a manifold according to the introductory part of Claim 1, which is characterized by the features of the characterizing part of Claim 1. Further developments of the invention are characterized by the features of the additional claims. According to the invention, a uniform load in parallel-working cleaners is obtained by a special embodiment of the connecting channel from a cleaner to the main channel of the manifold. The connection channel is parallel to the manifold main channel, and the cross-sectional area of this channel is such that the velocity of flow becomes the same as in the main channel. At the mouth of the connecting channel the area of the manifold main channel increases with the area of the connection channel. The length of the connection channel, which is parallel to the manifold main channel, is at least equal to the diameter of a tube having the same area as the channel. Suitably, the length is more than twice this diameter. The manifold may consist of a number of tubes having diameters increasing in steps. In one embodiment, a connecting tube projects into a tube which is enlarged at the connection. The connection channel is formed by the gap between this enlarged tube and the tube projecting thereinto. In another embodiment the connection channel may consist of a tube which is substantially parallel to a tube forming a part of the main channel. The area of the main channel tube increases with the area of the connecting tube at the mouth of the connecting tube. In a PFBC power plant a number of groups of series-connected cyclones are connected to the manifold. The invention will now be described in greater detail with reference to the accompanying drawings showing - by way of example - in Figure 1 schematically a PFBC power plant, Figure 2 and 3, contemplated from A-A in Figure 1, a view of the combustor, the cyclones and a manifold connecting the cyclones to gas tubes for transporting purified gases to a turbine, Figure 4 a section through the manifold taken along the line B-B in Figure 2, Figure 5 a section through the manifold taken along the line C-C in Figure 3. In the figures, 10 designates a pressure vessel. The pressure vessel 10 comprises a combustor 12 and a gas purification plant 13 comprising a plurality of parallel groups of series-connected cyclones 14 and 16 for purifying the combustion gases. Only one such group is shown in Figure 1 while four such groups are to be seen in Figures 2 and 3. The space 18 inside the pressure vessel 10 and surrounding the combustor 12 contains compressed combustion air. The pressure may amount to 2 MPa or more. Combustion air is supplied to the combustor 12 via nozzles 20 in the air-distributing bottom 22. This air fluidizes a bed 24 of particulate material and burns a fuel, usually coal. Fuel and bed material are supplied to the bed 24 via the feed pipe 26. The combustor 12 includes tubes 28 for the generation of steam for a steam turbine (not shown). The combustion gases are collected in the freeboard 30 above the bed 24 and are passed to the cyclones 14 and 16 via the pipes 32 and 34. The last cyclones 16a to 16d in the groups of parallel-connected cyclones 14, 16 are connected to a manifold 35. This manifold 35 consists of tubes 36a-d and tubes 38a-d forming the inlet channels 40b-40d and the main channel, respectively. The tube 38d of the manifold 35 is connected to a tube supplying propellant gas to the turbine 42. The turbine 42 drives a compressor 44, which supplies the space 18 with compressed combustion air, and a generator 46. As shown in Figures 2 and 3, the purification plant 13 consists of parallel groups of cyclones 14a-d and 16a-d which are connected to the combustor 12 by the pipes 32a-d and which are connected between themselves by pipes 34a-d. The cyclones 16a-d are connected to the tubes 36a-d forming the inlet channels of the manifold 35 each having the area A. The tube parts 38a-d form the main channel of the manifold 35 with the areas A, 2A, 3A and 4A. In case of equal flow through the parallel groups of cyclones, the velocity of flow V becomes equal in the whole main channel of the manifold formed by said tubes parts 38a-d. In the embodiment according to Figures 2 and 4, the main channel of the manifold 35 consists of tube parts 38a-d having circular cross-section. The first tube part 38a of the pipe 38 projects into the second tube part 38b by a distance L1, the second tube part 38b projects into the third tube part 38c by a distance L2, the third tube part 38c projects into the fourth tube part 38d by a distance L3. Between the tube parts 38a and 38b, 38b and 38c, and 38c and 38d of the manifold 35, gaps 40b, 40c and 40d, respectively, are formed, the lengths L1, L2, L3, etc., of which increase with the area of the tube parts 38b-d at the connection. The tube parts 36b, 36c and 36d are connected to theses gaps. The gaps 40b-d form channels, parallel to the main channel of the manifold 35 ahead of the terminating point of the gaps 40b-d. An undisturbed gas flow connection is obtained since the direction of flow and the velocity of flow at the mouths of the channels are the same as in the main channel of the manifold upstream of the mouth. Thus, no pressure differences, which might cause the flows through the groups of cyclones to become different, will arise. In the embodiment according to Figures 3 and 5, the connection channels and the main channel of the manifold 35 consist of rectangular tubes 36a-d and rectangular tubes 38a-d, respectively. Ahead of the connection to the main channel of the manifold 35, the tube parts 36b-d are formed parallel to the tube parts 38a-d. At the mouth of the tube parts 36b-d the area of the main channel formed by the tube parts 38a-d increases with the area of the tube parts 36b-d.

Claims: Manifold for receiving gas streams from a plurality of parallel-working units comprising connection channels (40b - 40d) which extend parallel or substantially parallel to a collecting main channel (38), preferably in a gas purifiers (14, 16) equipment of cyclone type, characterized in that said connection channels (40b - 40d) are arranged alongside the collecting main channel (38), that the outlet openings of the connection channels (40b - 40d) into the main channel (38) are arranged separated from each other and along the length of the manifold (35) and that the area of the main channel (38) increases in such a way that the gas velocity V in the connection channels (40b - 40d) and the main channel (38) is substantially equal. Manifold according to claim 1, characterized in that the length (L) of the connection channel (40) is at least equal to the diameter (d) of a tube having the same cross-section as the connection channel (40), preferably more than twice said diameter (d). Manifold according to claim 1 or 2, characterized in that the manifold (35) consists of a number of pipe parts (38a-d) with a gradually increasing area at the point where an upstream pipe part projects into a subsequent downstream pipe part by a distance (L), and that the connection channel (40) is formed of the gap between said pipe parts. Manifold according to claim 1 or 2, characterized in that the connection channel (40) consists of a pipe which is parallel to the main channel (38), and that the area of the main channel (38) increases with the area of the connection channel (40) at the mouth thereof into the main channel (38). Manifold according to any of the preceding claims, characterized in that it collects purified gas from a number of gas purifiers (14, 16), primarily cyclones for purification of gas from a combustor (12) in a PFBC power plant.

Inventors: ANDERSSON KARL-ERIK, ANDERSSON, KARL-ERIK
Applicants: ABB STAL AB
Application year: 1989
Main classification: B04C5
IPC codes: F23J15, F15D1, F23C10, B04C5, B01D45, F02C3