Taking offspring in a problem of ship emission reduction by exhaust gas recirculation control for large diesel engines, an underlying generic estimation challenge is formulated as a problem of joint state and parameter estimation for a class of multiple-input single-output Hammerstein systems with first-order dynamics, sensor delay, and a bounded time-varying parameter in the nonlinear part. This brief suggests a novel scheme for this estimation problem that guarantees exponential convergence to an interval that depends on the sensitivity of the system. The system is allowed to be nonlinear, parameterized, and time dependent, which are characteristics of the industrial problem we study. The approach requires the input nonlinearity to be a sector nonlinearity in the time-varying parameter. Salient features of the approach include simplicity of design and implementation. The efficacy of the adaptive observer is shown on simulated cases, on tests with a large diesel engine on test bed, and on tests with a container vessel.
The offshore de-oiling process is a vital part of current oil recovery, as it separates the profitable oil from water and ensures that the discharged water contains as little of the polluting oil as possible. With the passage of time, there is an increase in the water fraction in reservoirs that adds to the strain put on these facilities, and thus larger quantities of oil are being discharged into the oceans, which has in many studies been linked to negative effects on marine life. In many cases, such installations are controlled using non-cooperative single objective controllers which are inefficient in handling fluctuating inflows or complicated operating conditions. This work introduces a model-based robust H ∞ control solution that handles the entire de-oiling system and improves the system’s robustness towards fluctuating flow thereby improving the oil recovery and reducing the environmental impacts of the discharge. The robust H ∞ control solution was compared to a benchmark Proportional-Integral-Derivative (PID) control solution and evaluated through simulation and experiments performed on a pilot plant. This study found that the robust H ∞ control solution greatly improved the performance of the de-oiling process.
The idea for this project originated within the Arctic Council’s Protection of the Arctic Marine Environment (PAME) Working Group, where a concern was raised about the disposal of tailings from onshore mining operations onto the seafloor. This led to a broader reflection on the impacts of mining operations on the marine environment. Many Arctic governments support the development of a mineral extraction industry, provided it operates in an environmentally responsible manner and considers socio-economic impacts to local communities. However, the environmental impact of existing and future mining operations is often debated. This report summarizes the results of the multi-year Existing Waste Management Practices and Pollution Control for Marine and Coastal Mining project, developed under the auspices of the Protection of the Arctic Marine Environment (PAME) Working Group.
The goal of this paper is to introduce and design a cost-effective Oil-in-Water (OiW) measuring instrument, which will be investigated for its value in increasing the efficiency of a deoiling hydrocyclone. The technique investigated is based on Electrical Resistivity Tomography (ERT), whose basic principle is to measure the resistivity of substances from multiple electrodes and from these measurements create a 2-D image of the oil and gas component in the water. This technique requires the measured components to have different electrical resistances, such as seawater which has a lower electrical resistance than hydrocarbon oil and gas. This work involves construction of a pilot plant, for testing the feasibility of ERT for OiW measurements, and further exploring if this measured signal can be applied as a reliable feedback signal in optimization of the hydrocyclone's efficiency. Different algorithms for creating 2-D images and the feasibility of estimating OiW concentrations are studied and evaluated. From both steady state and continuous laminate flow perspectives, with respect to the objective which is to use this measurement for feedback control purposes.
The European Green Deal (EGD) adopted in December 2019 seeks to facilitate the transition of the EU towards a climate-neutral continent and a modern, resource-efficient, and competitive economy by 2050. In addition to a set of objectives, it is also a policy program that will affect the policy landscape, by driving the development of new directives and regulation, and the amendment of existing ones. In order to facilitate a transition of EU society to better protect the marine environment, decision making and implementation processes within marine governance will need to be improved to develop and implement measures through which EGD marine protection objectives will be achieved.
The Horizon Europe PERMAGOV project aims to improve the implementation and performance of EU marine policies to reach the goals set in the EGD. The PERMAGOV project focuses on four issue areas, so-called regime complexes: Maritime Transport, Marine Energy, Marine Life and Marine Plastics. Within each regime complex, 2 to 3 case studies are used to explore and analyse how governance arrangements are emerging and changing and improving their performance through the EGD. These case studies span three European Seas, the Baltic Sea, the Mediterranean Sea and the North East Atlantic.
There has been a continued increase in the load on the current offshore oil and gas de-oiling systems that generally consist of three-phase gravity separators and de-oiling hydrocyclones. Current feedback control of the de-oiling systems is not done based on de-oiling efficiency, mainly due to lack of real-time monitoring of oil-in-water concentration, and instead relies on an indirect method using pressure drop ratio control. This study utilizes a direct method where a real-time fluorescence-based instrument was used to measure the transient efficiency of a hydrocyclone combined with an upstream gravity separator. Two control strategies, a conventional PID control structure and an H ∞ robust control structure, both using conventional feedback signals were implemented, and their efficiency was tested during severely fluctuating flow rates. The results show that the direct method can measure the system's efficiency in real time. It was found that the efficiency of the system can be misleading, as fluctuations in the feed flow affect the inlet concentration more than the outlet oil concentration, which can lead to a discharge of large oil quantities into the ocean.
This article is a feasibility study on using fluorescence-based oil-in-water (OiW) monitors for on-line dynamic efficiency measurement of a deoiling hydrocyclone. Dynamic measurements are crucial in the design and validation of dynamic models of the hydrocyclones, and to our knowledge, no dynamic OiW analysis of hydrocyclones has been carried out. Previous studies have extensively studied the steady state efficiency perspective of hydrocyclones, and have related them to different key parameters, such as the pressure drop ratio (PDR), inlet flow rate, and the flow spill. Through our study, we were able to measure the dynamics of the hydrocyclone's efficiency (ϵ) response to step changes in the inlet flow rate with high accuracy. This is a breakthrough in the modelling, control, and monitoring of hydrocyclones.
An increasing water to oil ration in the North Sea oil and gas production motivates for an optimization of the current deoiling facilities. Current facilities are operated on matured methodologies, which in most cases fulfill the government regulations. However, it has also observed that these solutions could be further improved. In order to more precisely monitor the deoiling operations, this study investigated the real-time monitoring of the deoiling efficiency of the hydrocyclone facilities which are commonly used in offshore oil and gas production. Fluorescence based monitors were applied to measure hydrocyclone inlet's and underflow's Oil-in-Water (OiW) concentrations in real-time. Image-based microscopy was used to analyze the oil droplet size distribution at inlet and underflow to investigate the droplets' influence on hydrocyclone's efficiency. Performance experiments were carried out to identify how pressure difference ratio (PDR) and the droplet's sizes affect the deoiling efficiency. The performance of the deoiling hydrocyclone was significantly influenced by the inlet flow rate, while less or marginally dependent on the PDR. The droplet size distribution experiment proved that large droplets have a high probability to be separated by the hydrocyclone. The findings suggest that the coupled separator tank and hydrocyclone system can be further improved upon by deploying coordinated control as the two systems are strongly interdependent.
Large volumes of produced water are being discharged globally as byproducts of oil production. Commercial production chemicals are conventionally needed to avoid problems such as bacterial growth, pipe corrosion, and oil/water separation issues. These chemicals will partition between oil and water phases and may affect both treatment processes and the environmental impact when water is discharged to the ocean after treatment. Capillary zone electrophoresis is used to measure partitioning coefficients of oilfield chemicals when these are dissolved in the water phase and in contact with either octanol or crude oil. The technique is fast and, due to simplicity, could have merits as on-site assessment of the partition coefficient for direct assessment of the fate of chemicals. The method was first qualified by estimating partitioning coefficients of aliphatic carboxylic acids and chemicals with a molecular structure similar to those of some production chemicals. Subsequently, the coefficients were determined for two different commercial corrosion inhibitors and a biocide that are used in the oilfield as production chemicals. The results showed that the chemicals predominantly preferred to remain in the water phase after contact with either octanol or crude oil. The partitioning coefficients log(p) spanned between −0.36 and −1.68 in the case of water/octanol contact and between 2.68 and −1.41 in the case of water/crude oil contact. One of the corrosion inhibitors exhibited a significant difference in the partitioning depending on whether the organic phase was octanol or crude oil. The chemical had a preference for the water phase in the case of the former but a preference for the crude oil phase in the case of the latter. The result demonstrates that it makes it challenging to evaluate the use of partitioning coefficients for oilfield applications.