Abstract:
Provided is a damper structure for an enclosed derrick, which can constantly compensate and maintain a pressure of an inner space of an enclosed derrick structure. The damper structure for the enclosed derrick includes: one or more communication ducts installed in a side of the enclosed derrick; and one or more open/close dampers coupled to the communication ducts to open or close the communication ducts, whereby air is selectively supplied to or exhausted from the enclosed derrick.

Description:
[0001]    CROSS-REFERENCE(S) TO RELATED APPLICATION 
         [0002]    This application is a national stage application filed under 35 U.S.C. §371 of International Application No. PCT/KR2011/004556, accorded an International Filing Date of Jun. 22, 2011, which claims priority of Korean Patent Application No. 10-2010-0109026, filed on Nov. 4, 2010, in the Korean Intellectual Property Office, which is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND 
       [0003]    1. Technical Field 
         [0004]    The present disclosure relates to a damper structure, and more particularly, to a damper structure for an enclosed derrick, which can constantly compensate and maintain a pressure of an inner space of an enclosed derrick structure. 
         [0005]    2. Description of the Related Art 
         [0006]    Due to the rapid international industrialization and industrial development, the use of the earth&#39;s resources, such as oil, is gradually increasing. Accordingly, stable production and supply of oil is emerging as a very important worldwide issue. 
         [0007]    For this reason, much attention has recently been paid to development of small marginal fields or deep-sea oil fields, which have been ignored because of their low economic feasibility. Therefore, with the development of offshore drilling techniques, drill ships equipped with drilling equipment suitable for development of such oil fields have been developed. 
         [0008]    In conventional offshore drilling, rig ships or fixed type platforms have been mainly used, which can be moved only by tugboats and are anchored at a position on the sea using a mooring gear to conduct an oil drilling operation. In recent years, however, so-called drill ships have been developed and used for offshore drilling. The drill ships are provided with advanced drilling equipment and have structures similar to typical ships such that they can make a voyage using their own power. Since drill ships have to frequently move in order for development of small marginal fields, they are constructed to make a voyage using their own power, without assistance of tugboats. 
         [0009]    Meanwhile, a moonpool is formed at the center of a rig ship, a fixed type platform or a drill ship, such that a riser or a drill pipe is vertically movable through the moonpool. In addition, a derrick in which a variety of drilling equipment is integrated is installed on a deck. 
       BRIEF SUMMARY 
       [0010]    An aspect of the present invention is directed to a damper structure for an enclosed derrick, which can effectively compensate or offset a negative pressure or a positive pressure generated within an enclosed derrick and a moonpool due to influence of waves on the moonpool. 
         [0011]    Meanwhile, in order for drilling of natural resources in extremely cold regions such as arctic regions, arctic rig ships, fixed type arctic platforms, and arctic ships such as arctic drill ships have been built. Such arctic ships may be constructed to have an enclosed area in almost all zones in order to prevent freezing in extremely low temperature environments and ensure the smooth operation of equipments and crews&#39; safety. 
         [0012]    In particular, a derrick and a moonpool of an arctic ship are enclosed in order to protect internal equipment and workers. The enclosed derrick and the enclosed moonpool may be installed to communicate with each other. 
         [0013]    Meanwhile, due to influence of waves transferred through an opening of the moonpool, a negative pressure or a positive pressure may be generated in the inner space of the moonpool and the inner space of the derrick communicating with the moonpool. Therefore, there is a need for protecting equipment, workers, and working conditions inside the derrick and the moonpool from the negative pressure or the positive pressure. 
         [0014]    According to an embodiment of the present invention, a damper structure for an enclosed derrick includes: one or more communication ducts installed in a side of the enclosed derrick; and one or more open/close dampers coupled to the communication ducts to open or close the communication ducts, whereby air is selectively supplied to or exhausted from the enclosed derrick. 
         [0015]    One end of the communication duct may communicate with an outer space of the enclosed derrick, and a first mesh may be installed at the end of the communication duct. 
         [0016]    The other end of the communication duct may communicate with an inner space of the inner space of the enclosed derrick, a second mesh may be installed at the other end of the communication duct, and the open/close damper may be installed between the other end of the communication duct and the second mesh. 
         [0017]    The damper structure may further include a control unit controlling the opening/closing operation of the open/close damper. 
         [0018]    The communication duct may include: a curved duct having one end which is inclined downward and communicates with an outer space of the enclosed derrick and at which a first mesh is installed; and a penetration duct installed in a sidewall of the enclosed derrick, the penetration duct having one end which is coupled to the other end of the curved duct, and the other end at which a second mesh is installed, whereby the penetration duct communicates with an inner space of the enclosed derrick. 
         [0019]    According to another embodiment of the present invention, a damper structure includes: an enclosed derrick disposed on a drill floor of a ship; a moonpool communicably coupled to a lower portion of the enclosed derrick; and a damper unit installed in at least one side of the enclosed derrick to selectively supply air to the inside of the enclosed derrick or exhaust air to the outside of the enclosed derrick. 
         [0020]    The damper unit may include: one or more communication ducts installed in a side of the enclosed derrick to communicate an outer space of the enclosed derrick with an inner space of the enclosed derrick; and one or more open/close valves coupled to the communication ducts to open or close the communication ducts. 
         [0021]    A fingerboard may be disposed in an upper inside of the enclosed derrick, and the damper unit may be disposed under the fingerboard. 
         [0022]    According to another embodiment of the present invention, a damper structure for an enclosed derrick communicating with a moonpool includes: a damper unit selectively supplying air to the inside of the enclosed derrick or exhausting air to the outside of the enclosed derrick in order to compensate or offset a positive pressure or a negative pressure which is generated in the moonpool by influence of waves. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0023]      FIG. 1  is a schematic view illustrating an enclosed derrick structure and a damper unit installed therein according to an embodiment of the present invention. 
           [0024]      FIG. 2  is an enlarged view illustrating the connection of a moonpool and a duct. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0025]    Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. 
         [0026]      FIGS. 1 and 2  illustrate an enclosed derrick structure and a damper unit installed therein according to an embodiment of the present invention. 
         [0027]    As illustrated in  FIGS. 1 and 2 , the enclosed derrick structure according to the embodiment of the present invention includes an enclosed derrick  10  installed in a ship, and an enclosed moonpool  15  coupled to a lower portion of the enclosed derrick  10 . 
         [0028]    The enclosed derrick  10  has a first inner space  10   a,  and the enclosed moonpool  15  has a second inner space  15   a.  The first inner space  10   a  and the second inner space  15   a  are coupled to communicate with each other. The enclosed derrick  10  is disposed on a drill floor  11  of the ship, and the enclosed moonpool  15  is disposed under the drill floor  11 . 
         [0029]    An outer wall of the enclosed derrick  10  is formed in an enclosed structure, and first and second enclosed tunnels  17  and  19  are provided in a side of the enclosed derrick  10 . Openings are formed at the ends of the first and second enclosed tunnels  17  and  19 , such that equipment such as a riser can be passed therethrough. 
         [0030]    Meanwhile, an inlet/output port  15   b  is formed at a lower portion of the moonpool  15 , and seawater waves may be transferred through the inlet/output port  15   b . Due to the influence of waves, excessive negative pressure or positive pressure may be generated in the first and second inner spaces  10   a  and  15   a.    
         [0031]    Therefore, one or more damper units  30  are installed in at least one side of the enclosed derrick  10 . Since air is supplied to or discharged from the first inner space  10   a  by the damper unit  30 , it is possible to compensate or offset the excessive negative pressure or positive pressure generated in the first and second inner spaces  10   a  and  15   a.  Thus, the pressures of the first and second inner spaces  10   a  and  15   a  can be constantly maintained, thereby safely protecting internal equipments, workers, and working conditions. 
         [0032]    The damper unit  30  includes one or more communication ducts which are installed in a side of the enclosed derrick  10  and communicate the outer space of the enclosed derrick  10  with the inner space of the enclosed derrick  10 . As one example, the communication duct includes a curved duct  32  and a straight penetration duct  33 . An open/close damper  35  is installed in the curved duct  32  and the penetration duct  33  to selectively open or close the curved duct  32  and the penetration duct  33 . 
         [0033]    In particular, the damper unit  30  may be disposed under a fingerboard  16 , such that the operation of compensating and offsetting the pressures of the first and second inner spaces  10   a  and  15   a  is effectively performed. 
         [0034]    One end of the curved duct  32  is inclined downward and communicates with the outer space of the enclosed derrick  10 , and a first mesh  31  is installed at the end of the curved duct  32 . The other end of the penetration duct  33  communicates with the first inner space  10   a,  and a second mesh  34  is installed at the other end of the penetration duct  33 . An open/close damper  35  is installed between the other end of the penetration duct  33  and the second mesh  34 . The first and second meshes  31  and  34  can minimize the inflow of external particles. 
         [0035]    It is preferable that the penetration duct  33  is coupled to the other end of the curved duct  32 , and the penetration duct  33  is fixed to the sidewall of the enclosed derrick  10 . 
         [0036]    When an excessive positive pressure (more than 25 Pa) and an excessive negative pressure (less than −75 Pa) are generated in the inside of the enclosed derrick  10 , the open/close damper  35  may be opened or closed manually or automatically in order to offset the excessive positive or negative pressure of the enclosed derrick. In addition, the open/close damper  35  may be selectively closed to block an air flow in the event of a fire or other emergency. 
         [0037]    A control unit  37  is installed in one side of the enclosed derrick  10  to control the opening/closing operation of the open/close damper  35 . The control unit  37  may be installed in the first and second enclosed tunnels  17  and  19 . The control unit  37  detects an internal pressure state of the enclosed derrick  10  in real time and controls the opening/closing operation of the open/close damper  35  manually or automatically. In this manner, the control unit  37  may control the internal pressure of the enclosed derrick  10  by supplying air to the inside of the enclosed derrick  10  or exhausting air to the outside of the enclosed derrick  10 . 
         [0038]    According to the embodiments of the present invention, the negative pressure or the positive pressure generated in the enclosed derrick  10  and the moonpool  15  due to influence of waves transferred to the moonpool  15  can be effectively compensated or offset, thereby safely protecting internal equipment, workers and working conditions inside the enclosed derrick  10  and the moonpool  15 . 
         [0039]    Furthermore, the downwardly curved duct  32  and the first and second meshes  31  and  34  can minimize the inflow of external rainwater or foreign particles. 
         [0040]    While the embodiments of the present invention have been described with reference to the specific embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.