Design, Modeling and Simulation of a Buffer and Injection Unit for Deep Sea Mining

Abstract

This thesis presents a design of a buffer and injection unit used in deep sea mining. The design process has presented a promising concept, that has been validated through modeling and simulations.

The main task for the injection unit is to provide a smooth and even flow of nodules into a mud loop, running in a traditional drilling riser system, without generating disturbances in terms of pulses in the mud flow or pressure.

The most promising concept is a swashplate design, similar to an axial piston pump. The swashplate design consists of a rotating drum with circular chambers. Each chamber has a piston that is connected to the swashplate and when the drum rotates the piston is extending and retracting, depending on the slanted plate.

Hydraulic and mechanical simulations of the swashplate design were performed and proved the concept to be feasible. The results from the simulations showed that a higher number of chambers with smaller cross section areas were beneficial in terms of generating as little pulses as possible in the mud. Additionally, a back pressure system should be implemented. Practical considerations such as the risk of clogging, the cylinder stroke, wear and added complexity must also be considered for a final design.

The outcome of this thesis is a promising design. However, there are still challenges that need to be solved and further development, including more detailed engineering is necessary towards a final design.