Please select the most similar patent number from A, B, C and D. Which number is?
A pipe air pressure regulating device, relating to the technical field of transportation, the pipe air pressure regulating device comprising a pipe (4) and at least one air pressure regulating assembly disposed at an outter side of the pipe (4). The pipe (4) is provided with an inner cavity used for transportation of a transport tool (5). Each air pressure regulating assembly comprises a breather pipe (1), air inlets and air outlets of the breather pipes (1) communicate with the inner cavity of the pipe (4), and the breather pipes are used for adjusting the air pressure difference between the front and rear of the transport tool. The present device reduces the air pressure difference between a front portion and a rear portion of the transport tool in the process of the transport tool traveling in the pipe and reduces the travel resistance of the transport tool. At the same time, the symmetrical stress caused to the pipe wall by the pressure difference between the front portion and the back portion of the transport tool is reduced, thus having the effect of the pipe being protected. The present device may continuously extrude the residual air in the pipe by means of the traveling of the transport tool, so that the travel resistance of the transport tool is as low as possible.
A: Disclosed is a portable power generation system. The entire power generation system has two transportation tools. A gas turbine, a power generator, an air inlet chamber, an exhaust collector, and an auxiliary system are provided on a first transportation tool. An air inlet assembly and an exhaust pipeline are provided as an integrated component on a second transportation tool. The second transportation tool further comprises at least four lifting devices used to separate the air inlet assembly and the exhaust pipeline from the second transportation tool and raise the same upward, such that a power generation transportation tool can move to a position directly below the air inlet assembly and the exhaust pipeline, and the lifting devices are then used to lower the air inlet assembly and the exhaust pipeline so as to connect the same with the air inlet chamber and the exhaust collector, respectively. The invention utilizes the weight of the air inlet assembly and the exhaust pipeline to achieve a seal at the joints.
B: A protection apparatus for protecting a pipe bevel during transportation, storage and loading of pipes, comprising a protection hood and a fast opening connection member, the protection hood enveloping an end bevel of a pipe requiring protection, and the fast opening connection member being connected to the pipe in a sealed manner. The protection hood comprises a cover plate (1) and a connecting end on the protection hood, and the fast opening connection member comprises a connecting end fixed on an outer wall of the pipe, a washer (4) and a sealing component. The connecting end on the protection hood comprises an upper snap disc (2), the connecting end fixed on an outer wall of the pipe comprises a lower snap disc (5), and the sealing component comprises a snap hoop (3). Nitrogen charged inside the pipe can be held therein for drying and the pressure of the nitrogen charge is regulated by a pressure gauge inside a connecting pipe. The apparatus protects the bevel of a pipe to be welded during transportation, storage and loading without colliding and causing wear, and also prevents foreign substances entering the pipe and contaminating the pipe; is convenient to detach, reducing installation labour; and can be repeatedly detached and can be reused for pipes of the same diameter, saving on materials.
C: An ejecting device, comprising a cabin (30) provided on a transportation tool, and a push-out part electrically connected to an ejection triggering circuit of the transportation tool. The push-out part comprises a push rod (31). The cabin (30) is a hollow cavity with one end opened. The push rod (31) is located within the cabin, and is used for performing ejection motion along a direction towards the opening of the cabin (30) after receiving a triggering signal of the ejection triggering circuit of the transportation tool, so as to eject an article to be dropped out of the transportation tool. The ejecting device can eject a to-be-dropped article in a transportation tool, so as to make the dropped article fall within a target drop area.
D: A high-speed transportation device using a low-pressure tube comprises a travel tube (1), a travel guide rail (7), a conveyance structure (2), a control system, a braking system, and a drive system. The travel tube is an extending tube structure formed by a tube wall. The tube wall is provided with a one-way air flow window (3) capable of controlling an air flow direction. The drive system comprises a tube-filling travel driving structure (4) capable of traveling through the tube, a tube traveling and filling structure (26), and a tube-filling travel pressure-reducing structure. The conveyance structure (2) is a carriage structure. The tube-filling travel driving structure (4), the tube traveling and filling structure (26) and the conveyance structure (2) are flexibly and extendably connected.
Answer: D