Effective mode of voltage in the electrical network when powering ships of the technical fleet and floating objects from the shore

The article discusses negative consequences of a decrease in the quality of electrical energy when feeding ship receivers of electricity from coastal sources, a method is proposed to ensure an effective voltage regime in the electrical network when feeding ships of technical fleet and floating objects from the coast. Definition of the equilibrium voltage mode at the “shore-to-ship” power supply scheme is given, the equivalent circuit of supply line (feeder) for the river fleet is developed, significant regulatory effects of the “shore-to-ship” power transmission elements are determined. Experimental studies of static characteristics of floating crane of R-99 project have been carried out. According to the results of the experiment, regulating effects on the voltage of the complex load of 0.4 kV of floating crane were determined. A calculation program for personal electronic computers has been compiled, which provides an assessment of the impact of voltage deviations in electrical networks when regulating the load. The law of voltage regulation in the “shore-to-ship” power transmission is proposed. An experimental verification of effectiveness of proposed regulation law was carried out while ensuring the equilibrium mode.

Analysis of heavy floating cranes and features of their operation

The main characteristics of offshore heavy floating cranes, which are independent navigation without tugs and the performance of cargo operations in open waters with wind and waves, are considered. The safety of navigation in these conditions can be ensured with high seaworthiness and maneuverability by giving the appropriate shape of the bow end of the hull, the minimum windage of the structure, as well as the optimal design of the topside (crane). The requirements for the design and construction of universal heavy sea floating cranes, built after 1966, are analyzed, the operating conditions, depending on the purpose, and the architectural and structural type of floating cranes with a lifting capacity of 100–900 tons are considered. When calculating the strength of the topside, the possibility of the floating crane operating with the maximum load was taken into account when the sea is rough up to three points and the wind is up to five points, taking into account the dynamic and inertial loads arising from rolling in waves, when picking up and breaking the load. In the event of an emergency breakage of the load, the structure of the topside and the boom system must exclude or minimize vibrations caused by the breakage of the load. The results of the calculation of the forces at the breakage of the load must be verified by full-scale tests of floating head cranes, for which the corresponding methods have been developed. The possibility of using the developed structure of the hull and the topside (crane) in the design and construction of modern floating cranes in the production conditions of shipyards is shown.

ANALISIS RESPON GERAK FLOATING CRANE BARGE UNTUK DECOMMISSIONING STRUKTUR LEPAS PANTAI

Penerapan floating crane barge memiliki potensi besar untuk operasi pengangkatan struktur dalam mendukung decommissioning anjungan lepas pantai pasca operasi. Respon gerak floating crane barge dalam perairan bergelombang selama operasi pengangkatan struktur di laut menjadi faktor penting dalam menunjang operasional yang aman. Pada penelitian ini, respon gerak dinamis floating crane barge terhadap gelombang dilakukan dengan simulasi eksperimen di laboratorium maneuvering ocean basin. Model uji barge yang dilengkapi dengan struktur crane boom sederhana dibuat dengan perbandingan skala 1:28. Respon gerak model uji dievaluasi dengan kondisi gelombang reguler dan gelombang irreguler. Karakteristik gerak amplitudo dijasikan dalam grafik RAO yang mana hasilnya menunjukkan kesesuaian antara gelombang reguler dan irreguler. Respon gerak terhadap gelombang acak mengalami peningkatan secara signifikan terjadi dari kondisi gelombang Hs = 0.50 m, Tp = 4.00 s ke kondisi gelombang Hs = 1.00 m, Tp = 5.50 s untuk heave sebesar 2.8 kali, untuk roll sebesar 2.5 kali dan untuk pitch sebesar 1.5 kali.

Safety Assessment for Upper Part of Floating Crane Considering Minimum Luffing Angle

Floating cranes are used for the construction and installation work of harbors, various heavy industries, and offshore structures. In the case of floating cranes that need to move around the work site, their navigation can be constrained due to marine bridges. In some cases, the clearance under the bridge between the water surface and the bottom of the marine bridge may be too low, and floating cranes cannot pass under the marine bridge. In this study, the height of the marine bridges and the boom height of the floating cranes considering the minimum luffing angle were investigated. Through minimizing the boom luffing angle of the floating crane by the height of back tower, a floating crane with improved mobility through marine bridges was developed. A structural analysis model was produced to check whether the developed crane design satisfies the design criteria obeying the KR, DNVGL, and ABS rules, including luffing condition as a special consideration. As a result of the structural analyses, structural safety was validated for the service, stowage, and luffing conditions in terms of combined stresses, displacements, and buckling.

Experimental Study on Development of Mooring Simulator for Multi Floating Cranes

In this study, the coupled motion of a mooring system and multifloating cranes were analyzed. For the motion analysis, the combined equations of motions of the mooring line and multifloating cranes were introduced. The multibody equations for floating cranes were derived from the equations of motion. The finite element method (FEM) was used to derive equations to solve the stretchable catenary problem of the mooring line. To verify the function of mooring simulator, calculation results were compared with commercial mooring software. To validate the analysis results, we conducted an experimental test for offshore operation using two floating crane models scaled to 1:40. Two floating crane models and a pile model were established for operation of uprighting flare towers. During the model test, the motion of the floating cranes and tensions of the mooring lines were measured. Through the model test, the accuracy of the mooring analysis program developed in this study was verified. Therefore, if this mooring analysis program is used, it will be possible to perform a mooring analysis simulation at the same time as a maritime work simulation.

ANÁLISE DE VIABILIDADE FINANCEIRA: ESTUDO DE CASO DE UM PROJETO DE FLOATING CRANE PARA O PORTO ORGANIZADO DE VILA DO CONDE-PA

A crescente demanda pelo escoamento da produção agrícola do centro-oeste brasileiro pelo “Arco Norte” tem trazido importantes desafios logísticos e, consequentemente, busca por soluções mais eficientes e de melhor capacidade de resposta. O presente estudo visa avaliar a viabilidade financeira de uma das soluções buscadas para a operação portuária de transbordo de cargas, que é uma embarcação do tipo Floating Crane, e ao mesmo tempo avaliar a eficácia da interação da análise determinística com a simulação de risco na análise de viabilidade. A análise determinística foi realizada através dos métodos tradicionais de avaliação de investimentos e para a análise de risco foi utilizado o método de Monte Carlo. O custo de capital considerado no estudo foi de 10% ao ano. A análise determinística retornou como resultados o payback no 9º ano, valor presente líquido (VPL) de R$ 35,67 milhões e taxa interna de retorno (TIR) de 18,07% ao ano. O resultado das simulações indicou um payback médio de 11 anos, VPL de R$ 27,15 milhões e TIR de 16% ao ano. A partir das distribuições de probabilidade acumuladas pode-se inferir que o investimento em tela possui baixo risco e possui viabilidade financeira. Destaca-se a boa interação entre análise determinística e de risco, proporcionando informação de melhor qualidade para a tomada de decisão.