Inside Estrella Del Mars III: Noise Analysis and Pollution Control

In 4Q2018, the marine arm of ST Engineering and Siemens were contracted for the design and build of Estrella del Mar III, a SCC-800 2x1C SeaFloat plant-mounted power plant for  Seaboard Corporation subsidiary Transcontinental Capital Corporation (Bermuda) Ltd., an Independent Power Producer with operation in Dominican Republic.

ST Engineering will be responsible for the engineering design, procurement and construction of the technologically advanced floating power plant, the balance of plant and the installation of the floating power plant. Siemens will provide for a combined cycle power plant with a capacity of 145 megawatts (MW) and deliver its innovative hybrid SIESTART solution, combining a flexible (gas turbine) combined cycle power plant with a battery energy storage system. Upon completion of the construction, the plant will be transported to its final destination where hot commissioning of the power generation facility will be undertaken before final delivery to the customer.

Noise Analysis Study

Expected to be situated along the Ozama River in the Santo Domingo, capital city of the Dominican Republic, the noise emission impacts to the environment must be carefully analysed. Adverse pollutions in terms of noise and air will affect locals living in the immediate surroundings of the power plant.

A joint noise emission study was conducted by ST Engineering and Siemens. Leveraging on each party’s domain specific noise knowledge and analysis software to corroborate on the findings, aiming to create an efficient noise management catering to both environmental and working conditions.  

Different permutations of potential noise sources during different modes of operations were detailed with the construction design of the power plant. Major elements, such as the two Gas Turbine (GT) SGT-800 and a Steam Turbine (ST) SST-600, were considered along with auxiliary equipment such as boilers, generators and condensers, amongst other equipment.

ST Engineering was able to simulate the noise emission to account for both structural-borne and airborne noise contributers and provide noise level results for both internal and exposed cavity compartments.

In addition, specific internal compartment cavities within the administration building were also reviewed. These included the offices, control rooms, conference rooms as well as the canteen on board. Exposed cavities such as the areas outside of the administration blocks and plant sides were also taken into consideration during the analysis.

Figure 1: VAone Noise Model of Power Plant (L) & Sample Result (R)

Upon obtaining all the inputs of the structural built-up and noise sources mentioned above, a noise study model was built with the VAone software (See Fig. 1). From the preliminary results obtained, necessary Noise Control Measures (NCMs) were considered for optimisation and implementation on the required compartment. One such measure is the extensive coating of the deck with a viscoelastic layer and floating floor. These measures dampen the effects of noise, provided a reduced output that satisfies pre-determined standards.

Concurrently, Siemens conducted a similar noise study with the distinct difference on emphasising on the effects towards near-field results. They primarily analyse the noise impact to the adjacent environmental region illustrated in Figure 3, taking the effects of the surrounding terrain, buildings and infrastructure from the power-plant to the environment, to create a comparison and compliance to noise requirements.

Figure 2: Noise Impact Assessment Region

During the course of the joint study, the parties concurred that the GT and ST structure-borne noise contribution is significant to the overall noise level of the power barge. Therefore, the results from ST Engineering’s VAone inputs were translated into Siemen’s Odeon software for analysis and vice versa. This helped to paint a more accurate picture of the structure-borne noises from the power plant to the environment.

Figure 3 – Sample Noise Analysis – Conference Room

As a result of the close cooperation between ST Engineering and Siemens, the power plant was designed to ensure operations will be at a noise level that has been assessed to meet both internal and environmental noise requirements, not exceeding 65 and 70dBA respectively.

Pollution Control

Aside from noise level requirements, a subject of interest is that design elements such as energy re-generation and waste water pollution control are also incorporated in the power plant in a bid to achieve positive environmental impact. Energy re-generation was achieved by channelling the exhaust from the GT through the Once Through Steam Generator (OTSG) to generate pressurised steam to run the Steam Turbine (ST). The re-using of exhaust heat energy allows the steam-water cycle to produce cleaner energy. At the same time, it significantly improves the plant’s overall efficiency from 37% up to 56%. The pipe routing of high and low pressure steam from the OTSG to the ST was similarly designed by the team in ST Engineering.

High quality water is required to extend the power plant’s operational life cycle. Thus, a Continuous Electro-Deionization (CEDI) plant will be used to treat water inputs, producing high quality, demineralised water for steam generation. Since the CEDI is self-generating and chemical free, the decrease in chemical discharge and infiltration results in reduced waste water discharge to the environment.

In summary, this joint and comprehensive noise assessment study done by both ST Engineering and Siemens has provided insights to highlight focus areas that can be improved on to meet internal and environmental noise requirements. Through strong collaboration between the two parties that is able to leverage on each other’s engineering capability to design and construct a modern power-plant that caters to one such environmental considerations.