Synthesis and Design Strategies for the Development of Macroscopic Interplant Water Networks in Industrial Zones

Increased water scarcity problems, coupled with the immense scale of water-intensive industrial activities in the region demands for the development of optimal water reuse and recycling strategies in industrial cities. Hence, industrial water and wastewater management is a key research priority. As a result, several necessary aspects that have not been addressed previously in water integration methods have been considered in this work, by developing and implementing a framework which allows for improved applications of macroscopic water integration in complex industrial regions. The main components relevant to the planning of cost-effective water networks in a devised city plan have been captured with a focus on identifying cost-effective water allocations within an industrial city. Detailed information associated with water-using and water-consuming entities have been captured, using both flowrate and contamination information as well as site location information. Hence, a spatial representation that is capable of capturing an industrial city arrangement, has been developed to assist in water network design, an aspect which has often been overlooked in existing methods. Moreover, the presence of a number of different options during the selection process of appropriate treatment technologies, as well as the efficient placement of corresponding treatment facilities, have also been considered. In addition to the above aspects, two different pipeline merging representations that are capable of identifying cost-effective opportunities have also been captured in this work. Both approaches allow for the screening of less complex pipeline networks, by assembling together commonly existing pipe sections, in the course of determining optimal water networks. All methods were implemented and demonstrated using several industrial city layout scenarios, and each method was able to identify a number of optimal synergies

The Development of a Synthesis Approach for Optimal Design of Seawater Reverse Osmosis Desalination Networks

This work introduces a systematic seawater reverse osmosis (SWRO) membrane network synthesis approach, based on the coordinated use of process superstructure representations and global optimization. The approach makes use of superstructure formulations that are capable of extracting a globally optimal design as a performance target, by taking into consideration desired process conditions and constraints that are typically associated with reverse osmosis systems. Thermodynamic insights are employed to develop lean network representations so that any underperforming solutions can be eliminated a priori. This essentially results in considerable improvement of the overall search speed, compared to previously reported attempts. In addition, the approach enables the extraction of structurally different design alternatives. In doing so, distinct membrane network design classes were established by partitioning the search space, based on network size and connectivity. As a result, corresponding lean superstructures were then systematically generated, which capture all structural and operational variants within each design class. The overall purpose is thus to enable the extraction of multiple distinct optimal designs, through global optimization. This mainly helps provide design engineers with a better understanding of the design space and trade-offs between performance and complexity. The approach is illustrated by means of a numerical example, and the results obtained were compared to previously related work. As anticipated, the proposed approach consistently delivered the globally optimal solutions, as well as alternative efficient design candidates attributed to different design classes, with reduced CPU times. This work further capitalizes on the developed representation, by accounting for detailed water quality information, within the SWRO desalination network optimization problem. The superstructures were modified to incorporate models that capture the performance of common membrane elements, as predicted by commercially available simulator tools, e.g. ROSA (Dow) and IMSDesign (Hydranautics). These models allow tracing of individual components throughout the system. Design decisions that are supported by superstructure optimization include network size and connectivity, flow rates, pressures, and post treatment requirements. Moreover, a detailed economic assessment capturing all the significant capital and operating costs associated in SWRO processes, including intake, pre and post treatment has also been accounted for. These modifications were then illustrated using a case study involving four seawater qualities, with salinities ranging from 35 to 45 ppt. The results highlight the dependency of optimal designs on the feed water quality involved, as well as on specified permeate requirements

The investigation of treatment design parameters on carbon integration networks

Carbon Integration methods help identify the appropriate allocation of captured carbon dioxide (CO2) streams into CO2-using sinks, and are especially useful when a number of CO2 sink options are present simultaneously. The method helps identify CO2 allocation scenarios when subjected to an emission target on the CO2 overall network. Many carbon dioxide sink options are costly, and more often than not, require a high purity carbon dioxide source to satisfy the sink demand. Hence, it is imperative to effectively incorporate treatment units in such networks, to obtain high-purity CO2 streams. In fact, it has been previously reported in many studies that the most expensive step in Carbon Capture, Utilization and Sequestration (CCUS) is the treatment system. As a result, this paper focuses on reassessing the performance of carbon integration networks using a more rigorous cost model for the treatment design stage. The effect of utilizing different treatment operating conditions on the overall cost of the treatment stage of CO2 (before allocation) is first captured using a detailed cost model. Subsequently, this information is then fed into a network design problem that involves a CO2 source-sink allocation network problem, and different CO2 net capture targets within the network. For this, an enhanced treatment model that captures all necessary treatment design parameters has been utilized alongside the original model. The original carbon integration formulation has been adopted from previous work. Many of the cost items have been lumped into single parameters in the original formulation, and lack the necessary depth required to carry out the necessary investigations for this work. Hence, the treatment model introduced in this paper is more rigorous, as it accounts for important technical performance constraints on the system to be assessed. Utilizing a more detailed cost model was found to be very helpful in understanding several effects of varying parameters on the overall source-sink allocations, when subjected to different CO2 net emission reduction targets. The cost of the carbon network increases when the solvent temperatures are increased. However, there was a noticeable linear trend at lower temperatures compared to higher temperatures, where the increase became non-linear. Furthermore, it was discovered that for net capture targets of 20% and 25%, no revenue from carbon storage could be generated beyond a solvent temperature of 25 °C. Additionally, the optimal diameter of the treatment column was more responsive to changes in solvent temperature for cases with low net capture targets (below 10%), while its sensitivity decreased for higher capture targets (above 10%). Graphical Abstract: [Figure not available: see fulltext.

Pipe size sensitivity in pressure relief networks using genetic algorithms

This paper utilizes a stochastic optimization approach using genetic algorithms, for conducting rigorous pipe size sensitivity assessments onto the design of pressure relief networks. By sampling high performance candidates, only the finest options can survive. The pressure relief network system that was investigated in this work was previously reported in literature. The problem is constrained and involves minimizing a cost objective function that evaluates the overall network performance, in which the best pipe size combination should be selected for each segment within the network. The overall goal of this paper was to seek cost-effective designs for the pressure relief piping system by exploring different ranges of pipe diameters that are available for each segment in the network and comparing how the overall design of the system is affected, when the number of pipe size options to select from is varied

Design and thermo-economic evaluation of an integrated concentrated solar power-Desalination tri-generation system

In this work, a concentrated solar power (CSP) tri-generation system that is capable of the simultaneous production of steam, power and freshwater is introduced. The abundantly available direct normal irradiance can potentially allow concentrated solar power systems to become major energy contributors in the desalination market. Since CSPs can generate both thermal and electrical energy, they have been found to be excellent candidates for sustainable operation of large scale desalination systems, in the long term. This paper presents a mathematical model in the form of a Mixed-Integer Nonlinear program (MINLP), which involves a tri-generation system for combined steam and power production, primarily using solar energy to operate steam turbines. Moreover, the option of freshwater production using various desalination technology choices, such as reverse osmosis (RO) and multi-stage flashing (MSF), is also accounted for within the model. Hence, the proposed model offers a very convenient and eco-friendly tri-generation route for steam, power and water production. The proposed systematic method was tested using different feedwater salinities, as well as using different product water flowrates, and electricity prices. According to the results obtained, the water production cost (WPC) associated with a water salinity of 25 g/L resulted in a value of 1.83 USD/m3, which is significantly lower than the WPCs obtained at 35 g/L (2.09 USD/m3) and 45 g/L (2.24 USD/m3). Moreover, a large scale tri-generation system with an overall production capacity of 100,000 m3/d of freshwater resulted in a 60% reduction of the attained WPC value, when compared against a small scale system with a production capacity of 10,000 m3/d of freshwater. The option of exporting electrical energy to the grid using the proposed tri-generation system was also investigated, and a sensitivity analysis was conducted by varying the price of electrical energy. The attained breakeven energy prices were 0.74, 0.79 and 0.82 cent/kWh at 25, 35 and 45 g/L of feedwater salinity, respectively

Investigation of seasonal variations and multiple fuel options in a novel tri-generation CSP integrated hybrid energy process

This work presents a novel Mixed-Integer Non-linear Program (MINLP) that accounts for the presence of multiple fuels in tri-generation systems. The key novelty of this work pertains to the use of hybrid energy systems in tri-generation processes, which are associated with multiple energy sources. In this work, different fuel sources such as natural gas, biomass and municipal solid waste (MSW) have been considered in the model, together with concentrated solar power (CSP), as a renewable energy option. The use of the aforementioned energy sources in tri-generation systems for heat, power and water production, were assessed simultaneously by the proposed model. CSP was utilized as the sole renewable energy option, due to the ease of obtaining both heat and power from such systems. The design of optimal tri-generation systems has been studied using the proposed model, under different conditions for carbon reduction. The model has been formulated using multi-period considerations, so as to account for seasonal variations. Moreover, the effect of several different operating parameters on the land use requirements of such systems were also investigated. The results indicate that despite the high cost of CSP, it was still found to be a highly desirable choice in the presence of carbon taxation. The water production cost of a hybrid natural gas-CSP tri-generation system was estimated at 1.277 USD/m3. This value could be 16% higher in the presence of carbon taxation. Additionally, biomass and solid waste options were found to be very promising energy outlets for desalination, especially in winter and fall seasons which have the lowest DNI values. The selection of these energy streams is also highly affected by the presence of carbon taxation policy. On the other hand, the incorporation of these two energy streams along with CSP could result in a fully local energy independent system with a water production cost of 1.44 and 1.537 USD/m3, respectively

Optimal Design of Spatially Constrained Interplant Water Networks with Direct Recycling Techniques using Genetic Algorithms

In this work, an industrial city spatial representation that accounts for different plant layouts and arrangements is utilized for interplant water network synthesis. The problem has been previously tackled using deterministic optimization methods. This work employs a stochastic optimization approach, using genetic algorithms, for the design of spatially constrained interplant water networks using direct recycling techniques. The approach identifies well-performing solutions in an evolutionary manner, by generating populations of candidate solutions, then sampling regions that are associated with the highest performance probabilities. This ensures that only the fittest designs survive, when evaluating the network performance. A fitness objective that accounts for both freshwater and piping costs was utilized in the design evaluation stage. When compared to the results that have been obtained using deterministic optimization, trade-off trends between the optimum cost of the network and fresh/waste targets were manifested by means of stochastic optimization. Enhanced network performance was attained for a reduced total cost, at the expense of a certain deviation from fresh/waste targets

Optimization of multiple fuel utilization options in Tri-generation systems

This work investigates the design of optimal tri-generation systems for heat, power and water production via multiple fuel selections, thus aiming to reduce the reliance on fossil fuel consumption. Generally speaking, tri-generation systems are associated with high levels of carbon dioxide emissions to meet energy and water production requirements. Hence, a shift towards more renewable energy sources can assist in partially reducing the environmental damage associated with standard tri-generation operations. Since the switch from fossil fuels to renewable energy is very costly, hybrid energy systems were found an appealing solution that could allow a gradual reduction of carbon emissions. Hence, the novelty aspect of this work is the ability to generate cost-effective tri-generation systems that incorporate optimal hybrid energy selections and utility generation routes, subject to specific net carbon reduction targets (NCRT). As such, four different energy sources (natural gas, biomass, municipal solid waste (MSW) and Concentrated Solar Power (CSP) were investigated, together with five different routes for steam expansion and electricity production using a Mixed Integer Nonlinear Program (MINLP), including technical, economic and environmental constraints. In order to study the effect of different fuel selections, energy production operations, and water production routes on the performance of tri-generation systems, data from three different desalination plants (located in USA, Cyprus and Qatar) were used. The results obtained show that energy requirements for desalination greatly affects the order of selection of energy sources. In general, biomass was identified as the best alternative to replace natural gas at NCRT values below 40%. On the other hand, MSW incineration using grate-fired and fluidized bed boilers became more desirable for steam production when higher NCRT values were utilized. The water production costs (WPC) of a standalone CSP system integrated with each of the studied plants, having a feedwater salinity of 33.5, 41.8 and 45 g/L, were estimated at 1.739, 2.233 and 2.67 USD/m3, respectively. In addition, an average incremental increase of 5.5% in the WPC has been observed during seasons that provide the lowest solar availability values

On the identification of optimal utility corridor locations in interplant water network synthesis

Studies involving the design of interplant water networks have received significant attention over the past few years. Many methods have been developed to assist in obtaining efficient water reuse network design schemes, mainly using fundamental concepts of water integration. Our recent work has presented the importance of considering spatial constraints in the form of utility corridor availability, when identifying cost-effective interplant water network arrangements in industrial zones (Alnouri et al., [2014]: Clean Technologies and Environmental Policy 16, 1637-1659). This article extends the scope of our previous work by enabling the identification of new corridor locations, which could potentially be used alongside existing utility infrastructure. We present an optimization framework that allows unutilized areas of land within industrial zones to be sectioned off and added as optional transportation channels, together with existing utility corridor regions, in the course of attaining cost-effective interplant water network designs. The methodology entails that identification of optimal wastewater reuse schemes among various processing entities, by exploring options for enhanced utility corridors. As an illustration, several cases that utilize an assumed layout for an industrial zone have been carried out, in which a number of unutilized regions of land were identified to exist. Several opportunities that allow for potential corridor additions onto existing corridor infrastructure, through the exploitation of unutilized regions of land within the plot, were explored. A number of improvements in the water network designs obtained are highlighted for the different case scenarios that have been investigated, using the proposed approach