Industrial case studies in the petrochemical and gas industry in Qatar for the utilization of industrial waste heat for the production of fresh water by membrane desalination

Membrane distillation differs from other membrane technologies in that the driving force for desalination is the difference in vapor pressure of water across the membrane, rather than total pressure. The membranes for MD are hydrophobic, which allows water vapor (but not liquid water) to pass. The vapor pressure gradient is created by heating the source water thereby elevating its vapor pressure. The major energy requirement is for low-grade thermal energy. Moreover, the Qatari economy is based on its massive hydrocarbon industry. In such industries water is routinely used in a number of applications in the form of process or cooling water. In a number of cases the water used can be seawater but with certain restrictions due to corrosion, fouling and water composition, large volumes of fresh water are required around the chemical plants. It is well known that many processes produce large amounts of excess heat i.e., heat beyond what can be efficiently used in the process. Industrial waste heat recovery methods attempt to extract some of the energy as work that otherwise would be wasted. Typical methods of recovering heat in industrial applications include direct heat recovery to the process itself, economizers, regenerators, and waste heat boilers. An investigation into the potential of using industrial low-grade waste heat in desalination using membrane distillation has been carried out. Three well-known chemical processes were considered: LNG, ethylene and VCM. Using an approach based on pinch technology for heat integration, process streams in the three processes were screened to eliminate unsuitable sources of low-grade heat. Consequently, the LNG and ethylene processes were eliminated because of their unsuitable cooling curves that tended to highlight extreme temperatures. The VCM process on the other hand showed a promising outlook, in particular in the direct chlorination section where a major vapor stream is condensed through the temperature range 118 to 460C. This is precisely the ideal range for low -grade heat recovery. Exploiting literature data and modeling concepts, a flowsheet for a potential MD plant was designed with relevant terminal temperatures.

Modeling approach and simulation study to assess the utilization potential of industrial waste heat in district heating systems

To operate industrial processes like the generation of hot water and steam or the melting and heat treatment of materials, thermal energy is usually required. In all these processes, a waste of thermal energy occurs, which is referred to as industrial waste heat. In order to reduce the primary energy consumption and environmental impacts due to CO2 emissions, the wasted energy should be recovered efficiently. Different technologies to reuse industrial waste heat for other applications exist. Companies interested in applying these technologies are confronted with risks and uncertainties, such as the lack of knowledge in this field of technology and risks involved with investments in these technologies. Due to these risks and uncertainties, the potential of existing technologies for industrial waste heat recovery is not realized sufficiently. The aim of this article is to discuss a Product-Service System (PSS) that is adequate for a flexible, sustainable and profitable waste heat recovery. This solution is based on the storage, transportation and utilization of industrial waste heat via mobile phase change material devices. Based on the introduction, existing and established concepts for waste heat recovery as well as the theoretical fundamentals of the Product-Service System approach and latent heat accumulators are described. Afterwards, the PSS concept for waste heat utilization is presented. In particular, appropriate business models are introduced for this solution.

The efficient utilization of waste heat from industrial processes can provide a significant source of energy savings for production plants, as well as be a driver of sustainable operations and the abatement of emissions. Industrial waste heat usually is contained in liquid or gaseous outlet streams. Although the possible ways to utilize waste heat are discussed in a wide variety of papers, these either provide only a general overview of utilization options and opportunities or focus on a narrow range of industrial processes. The aim of the present paper is to discuss the practical aspects of waste heat utilization in the European Union so that the reader can gain perspective on (i) the thermal classification of waste heat, (ii) liquid and gaseous waste streams and their typical temperatures for industrial use cases, (iii) the technical, economic, physical, and environmental aspects barring full utilization of the available waste heat, (iv) waste heat sources in various industries, and (v) standardized equipment and technologies applicable to industrial waste heat utilization, including their advantages, disadvantages, and weak points.

Key issues and solutions in a district heating system using low-grade industrial waste heat

External use of industrial waste heat - An analysis of existing implementations in Austria

Efficient and economical utilization of industrial waste heat would result in reduced energy use and thereby contribute to reduction of greenhouse gas emissions to the atmosphere. Two-phase thermosyphon technology has demonstrated the potential capability for waste heat recovery, but it has not been yet utilized in large-scale industrial applications. As a part of an industrial project, various types of thermosyphon heat pipes have been designed and tested for extraction of waste heat and process control in aluminum industry. This article presents the heat and mass transfer model, developed to provide a fast and accurate simulation tool for industrial application of thermosyphon heat pipe technology for waste heat utilization. The mathematical model considers the energy, momentum, and mass transfer equations, in their one-dimensional form, to predict output parameters of the thermosyphon and enable parametric and sensitivity analysis. The mathematical model structure is set up in a way that the least numerical cost and time is spent while the model accuracy is kept at acceptable level for the defined application. To provide experimental data for validation of the simulation model, the proposed thermosyphon was tested experimentally using a test set-up instrumented for this purpose. The simulation results are found to be in good agreement with the experimental data. The developed model and code are viable to be used as a simple and fast tool for modeling, design, and optimization of the thermosyphon as an element in a heat recovery module.

Phase change heat storage technology can provide effective solutions for temporal and spatial mismatch in the utilization of industrial waste heat and achieve efficient heat transportation. However, in view of the diverse characteristics of industrial waste heat, it is urgent to conduct research on the utilization of waste heat at different temperatures. Building upon existing theories, this paper innovatively establishes a numerical model for multi-melting-point phase change heat storage materials (PCMs), taking into account both temperature of the heating surface and melting points of the heat storage materials. The melting process of the selected materials was simulated and the results were discussed. The coupled thermal performance of different heating surfaces and melting point temperatures was quantitatively clarified based on the analysis of the results of numerical models, The research results show that different heating surfaces have remarkable influence on the melting efficiency. At the melting point of 50?C, under the heating surface at 75?C, the complete melting time is only 3360 seconds, which is 31% of the complete melting time when using a heating surface at 60?C. Furthermore, when the heating surface temperature reaches a certain level, the influence brought by melting point gradually diminishes. Evolution diagrams of the temperature field visually demonstrates the positive correlation between the intensity of natural convection and the heat transfer temperature difference. Finally, it was found that latent heat mainly determines the heat storage capacity of PCM and choose materials with appropriate melting points can improve the heat storage rate. By conducting research on the new type of heat storage device with multiple heating surfaces and multiple melting points, this study provides guidance for optimizing the heat utilization efficiency in practical engineering applications.

Evaluation of membrane-based desalting processes for RO brine treatment

As the goal of carbon peak and carbon neutrality becomes a global consensus, the circular economy is gradually evolving from an environmental concept to a core lever for national strategy and industrial transformation. To achieve green and low-carbon development, China is accelerating the construction of a circular economy system, particularly in the fields of resource recycling and utilization. Industrial waste heat, a strategically critical supplementary energy resource, performs a pivotal role in advancing the circular economy. Based on an energy technology coupling model, this study assesses the waste heat utilization potential in China and quantitatively measures its impact on energy conservation and carbon reduction. The results show that: (1) The potential of industrial waste heat in China is characterized by an inverted U-shaped trajectory. Over the near-to-medium term, the steel and power industries remain the primary contributors to waste heat utilization potential. (2) Low-grade waste heat represents the majority of utilization potential in China’s industrial sector, mainly from power generation, fuel processing, and steel manufacturing. The model results indicate that the proportion of low temperature waste heat will increase from approximately 66% in 2025 to 83% in 2060. (3) Waste heat utilization significantly influences the energy transition pathway. The findings of this study demonstrate that energy-intensive industries have the potential to reduce primary energy consumption by more than 13%. Moreover, making full use of waste heat could accelerate China’s carbon peaking target to 2028, and reduce peak carbon emissions by an estimated 5.1%.

Evaluation of the theoretical, technical and economic potential of industrial waste heat recovery in the Basque Country

Industrial waste heat may be one of the answers to future energy demands. Depending on the temperature, industrial waste heat may be used to produce electricity or meet cooling or heating demands at different temperature levels. However, in order to estimate the influence the waste heat may have in future energy systems, the magnitude of the industrial waste heat in the different countries need to be estimated. For Germany, so far, only top-down analyses of the waste heat potential exist, using key figures derived from other studies in other countries. In this paper, the first bottom-up approach for estimating the industrial waste heat potential in Germany is presented. For this approach, an algorithm to evaluate and test the mandatory emission report data from German production companies was developed. In a second step, round about 81,000 data sets have been evaluated to calculate a conservative and lower boundary value for the industrial waste heat. As this conservative, lower boundary based on the collected data from the German industry, the waste heat volume was evaluated as 127 PJ/a or 13 % of the industrial fuel consumption. Results were used to derive key figures with which the missing share of the data was approximated.

The process industry utilizes thermal energy on a massive scale and rejects a significant proportion into the environment as a low grade heat. The definition of low grade heat is fuzzy and is somewhat related to the temperature of the stream carrying such thermal energy. Estimates of low grade heat emissions are hard to compile accurately on a global scale but these are likely to be of the order of thousands of trillions of BTUs. In some cases, up to 50% of thermal energy consumed is eventually rejected as low grade heat. This waste is not only uneconomical but also environmentally damaging since it carries a carbon footprint. Modern process plants reduced a great deal of thermal energy losses through heat integration and energy recovery. However, due to process temperature requirements, a vast amount of thermal energy denoted as low grade heat is still rejected. The objectives of this work include evaluating the possibility of utilizing the low grade heat outside the process generating, in a useful manner that has both economic and environmental benefits. In the Middle East where the oil and gas industry rejects vast amounts of low grade heat, recovery and utilization for desalination is becoming a serious option. This work proposes utilization of low grade heat in membrane distillation for desalination and establishes a balance between capital and operating costs as well as carbon footprint reduction. The work is based on a couple of case studies involving well established processes, namely the vinyl chloride monomer and gas-to-liquids processes. The recovery of low grade heat will be coupled with seawater cooling thus providing a warm source of salty water feed to the membrane distillation system. The work indicated that quality potable water may be produced for the petrochemical plants and neighboring living quarters at a reasonable cost. This approach may reduce the demand for fresh water from desalination plants in major industrial complexes making these self-sufficient in fresh water. Benefits are both economic and environmental.

In this study, a novel industrial application of membrane distillation (MD) is presented for waste water treatment in the nano-electronics industries. Previously reported performance of a semi-commercial Air Gap Membrane Distillation (AGMD) module is employed to evaluate the system performance in the terms of thermal energy analysis. To comply with thermal power demand in the MD systems, different integration possibilities between the MD unit and waste heat sources namely heat recovery chiller, Volatile Organic Compounds (VOCs) abatement combustion exhaust, and process cooling water exhaust are identified. Along with the technical assessment, this feasibility study has also involved the economic evaluation of the industrial waste heat integrated MD systems including unit water treatment cost. Results show the techno-economic viability of the proposed MD system integrated with industrial waste heat sources.

Membrane distillation (MD) is an emerging membrane separation technique which provides a competition for the conventional separation process such as reverse osmosis (RO) and thermal distillation. The MD process was first developed in the 1960s, but only recently garnered the interest from academics and industry due to the advancement of membrane fabrication technique. The MD is a thermal-driven process which has an ability to be integrated with renewable energy and/or waste heat. The driving force of the MD process is vapor pressure difference where the feed vapor is transported through the non-wetted hydrophobic porous membrane to the permeate regime where permeate will be collected via condensation. As such, the MD possesses a theoretical rejection rate of nearly 100%. This review addressed the recent progress of the MD process in terms of membrane fabrication, integration with renewable energy and/or other membrane separation process as well as applications of MD in various industries. This paper may serve as an update of the recent progress of MD which in some way, is able to help the researchers explore the new investigation field in MD for it to be commercially more viable.