Support Leg and A Mobile Offshore Work Platform

Abstract

The present invention discloses a support leg and a mobile offshore work platform having that leg. The disclosed support leg for a mobile offshore work platform comprises a support arm extending in a vertical direction, further comprising a support platform that has a cross section larger than that of the support arm, and that the lower end of said support arm is fixed to the upper surface of the support platform. When wind turbine installations or other offshore works are carried in sea areas of soft foundation ground, the support platform is supported on a soft foundation ground by a larger cross-sectional area, providing a greater support force and improving the stability of the mobile offshore work platform, and the mobile offshore work platform can be used to complete wind turbine installations and other predetermined works in sea areas of soft foundation ground.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]The application claims the benefit of Chinese Patent Application Nos. 200910237987.8, filed Nov. 27, 2009 and 201010112156.0, filed Feb. 10, 2010 under 35 U.S.C §§119(a)-(d), which are hereby incorporated by reference in their entirety.TECHNICAL FIELD[0002]This invention relates to an offshore work platform technology, and particularly, to a support leg for a mobile offshore work platform and a mobile offshore work platform having the support leg.BACKGROUND ART[0003]Offshore wind power generation technology concerns transformation of wind energy into electrical energy by means of one or more wind turbines installed in a wind farm located in an appropriate sea area. A wind turbine generally comprises a tower, a wind rotor and a nacelle, wherein the nacelle is provided with a generator, a gearbox and a main shaft. The bottom of the tower is installed to the wind turbine foundation of the wind farm, and the wind rotor and the nacelle are ins...

AI Technical Summary

Benefits of technology

[0012]Based on the provision of the support leg provides mentioned above, there is further provided a mobile offshore work platform having the above mentioned support leg, so as to improve the operation stability of the mobile offshore work platform.

[0015]Compared with the prior art, the support leg for mobile offshore work platforms which is provided by the present invention, in addition to the support arm extending in a vertical direction, further comprises the support platform fixed to the lower end of the support arm, and the cross section area of the support platform is larger than that of the support arm; and as such, when wind turbine installations or other offshore works are carried out in predetermined sea areas of soft foundation ground, the support platform with relatively large cross section area thus is supported on a soft foundation ground by a larger area, so that a greater support force can be provided for the platform body, the stability of the mobile offshore work platform is improved, and the mobile offshore work platform can be used to complete wind turbine installations and other predetermined works in sea areas of soft foundation ground. At same time, since the support platform is located at the lower end of the support arm, the support arm may be made to have a smaller cross section area, the support leg thus remains to have a relatively light total weight.

[0016]In a further preferred technical solution of the support leg of the present invention, said support platform comprises a cavity having an opening located on the lower surface of the support platform. As such, when the support leg needs to be sunk to the sea floor and supported on the soft foundation ground, the cavity may be depressurized by using a filling and expelling pump, so that a negative pressure region will be created in the cavity, the air and water in the cavity are expelled out, the support platform of the support leg can be smoothly sunk into sea water, the particles of the soft foundation ground are flowed into the cavity, the support platform is deposited into the soft foundation ground, and the support leg can provide a support force for the platform body. When the support leg needs to be raised, the filling and expelling pump can be used to increase the pressure in the cavity, to fill water or air into the cavity, to create a positive region inside the cavity, to detach the support platform from the soft foundation ground under action of the pressure of the water or air, and to pull out the support leg from the soft foundation ground smoothly, so as to facilitate the farm-transfer of the mobile offshore work platform.

[0017]In another further preferred technical solution of the support leg of the present invention, said support platform further has a filling and expelling passage having an external port located on the outer surface of the support platform and an internal port located on the wall surface of the cavity. In this technical solution, the filling and expelling pump can be connected with the cavity through the filling and expelling passage to facilitate the pressure increment and reduction of the cavity.

[0018]In an alternative technical solution of the support leg of the present invention, the external port of said filling and expelling passage is located on the outer surface of the support arm, and as such, a suitable filling and expelling pump may be provided on the platform body, by which the pressure increment and reduction of the cavity are realized to create a negative or positive region inside the cavity. At same time, the internal port is located on the upper wall surface of the cavity, and as such, when the support leg is sunk downward, the air and water inside the cavity can be expelled out more clearly; and when the support leg is raised upward, air and / or water can be filled into the cavity from its upper portion to make the support leg rise upward more smoothly.

[0020]Based on the above mentioned support leg as provided, the provided mobile offshore work platform having the above mentioned support leg also has corresponding technical effects.

Problems solved by technology

Generally speaking, each part of the wind turbine is heavy.

Because at present there is no large crane ship specifically designed to install a wind turbine, therefore, during the hoisting and mounting of a whole wind turbine, different hoisting and mounting processes need to be planned according to different wind turbines and different conditions of the predetermined sea area configurations, which makes the installation process very complicated.

Further, the cost for using or renting a large crane ship is quite high, which thus results in the expense increment of the installation of a wind turbine.

Furthermore, the large crane ship has the characteristic of a deeper draft, so that the large crane ship can not be used to perform the hoisting and mounting work in tidal flats and shallow sea areas, and the application of this manner is limited by the installation areas.

Although this solution can compensate for the defects existing in the former solution, there are also some problems in it.

In addition, when the support leg 200 is pulled out of the soft foundation ground 300, the friction force F2 will act on the support leg 200 in a reverse direction to make it difficult to pull the support leg 200 out of the soft foundation ground 300, thereby causing difficulty of the transfer of the mobile offshore work platform among farms.

In theory, although F2 can be increased by increasing the lengths of the support legs 200 to increase the contact areas of the support legs 200 with the soft foundation ground 300, or the support force F1 can be increased by causing the bottoms of the support legs 200 to extend directly to a harder foundation ground, this actually can not be implemented, due to the reason that not only the contour size of the mobile offshore work platform is increased to increase the costs of manufacture and use but also the greater friction force F2 would make it difficult to pull the support leg 200 out of the soft foundation ground 300 to cause the failure of the transfer of the mobile offshore work platform between farms.

The previously mentioned problems existing in mobile offshore work platforms exist not only in the installation process of a wind turbine, but also in other offshore work processes (including the work processes in beach areas of land-water interfaced areas of continental rivers, continental lakes, marsh lands or the like).

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