Industrial Combined Heat And Power Research Articles

Principal parameters of thermoelectric generator module design for effective industrial waste heat recovery

In the sustainable energy agenda, thermoelectric generators (TEG) can be a central technology for low-cost combined heat and power (CHP) systems. TEG module (TEM) is the combination of TEG cells, heat pipes, heat sinks and copper blocks that produce electrical power and thermal energy for low temperature heating simultaneously. Two TEG cells were used in each TEM for CHP in a bakery factory with a reference waste heat temperature of 250°C. Different designs of TEM affect the heat transfer mechanics through the components. However, actual testing of each design requires high cost and time consuming. Identifying the principal parameters affecting the desired output is indeed important before investing in actual design fabrication. One-dimensional model is developed in this manuscript to evaluate the fundamental interactions between each component. Parametric variation for nine main parameters characterized the steady-state response of each parameter under four novel heat sink configurations. The parameter sweeps approach benefits in designing a novel TEM for optimum system output. An improved TEM with 6 TEG cells was designed and it increased the heat recovery ratio from an initial 14% to 38%. The Reynolds number of streams are the major operating parameter as it influences the heat sink effectiveness. Large heat exchanger frontal area and copper block housing surface area are also significant parameters. Identification of these principle parameters would assist in effective designs of TEM systems for industrial CHP.

Decarbonization potential of regional combined heat and power development

Industrial decarbonization is a significant challenge to national net zero goals. Combined heat and power (CHP) technologies provide a means by which industrial facilities can achieve greater energy efficiency and decrease carbon emissions through cogenerating electric power and process heat. Regions possessing sufficient population density and manufacturing capacity have significant technical potential for industrial CHP development and can experience economic and environmental benefits. However, CHP implementation costs and the complexity of projects represent significant barriers to deployment with successful implementation often relying on government incentives to achieve economic feasibility. In this research, a framework is developed to evaluate the economic feasibility and environmental viability of various CHP technical potential under the various market penetration scenarios. A case study for a region in the United Sates is presented to highlight the efficacy of the framework. Projected CHP generating capacity of the region is calculated using commercial and industrial specific capacity factors. Comprehensive CHP engineering and cost data are integrated with regional economic transaction data. Then, comparative CHP application analysis is performed to determine which configuration could have the greatest regional economic and environmental impacts. Results indicated that investment in industrial topping cycle CHP to achieve the maximum technical potential generating capacity would have the greatest regional impacts resulting in $20 billion of economic outputs, creating 89,000 jobs, and avoiding approximately 3.2 million metric tons of carbon dioxide emissions. Results from this and similar research may be used by policymakers and administrators to assess potential investments in industrial decarbonization technologies and pathways.

Industrial CHP with Steam Systems: A Review of Recent Case Studies, Trends and Relevance to Malaysian Industry

Malaysia’s energy intensity (GWh/GDP) shows an increasing trend since the 1990s, leading to the government’s efforts to promote energy efficiency via policies such as the National Energy Efficiency Action Plan (NEEAP), which includes the Energy Performance Contracting (EPC) initiative. This paper reviews recent publications in industrial Combined Heat and Power (CHP) with a focus on international case studies relevant to Malaysian industries that use industrial steam and highlights trends within the research area. It also provides the basis for more case studies to be performed in the Malaysian industry to improve energy efficiency while also supporting further academic research in the area. Additionally, the paper documents the importance of data collection and analysis as well as demand forecasting, not only for a better understanding of industrial energy systems but also to increase profitability since system loads may vary throughout a typical year. A multi-criteria and comprehensive approach is recommended in future case studies to ensure energy efficiency, economic returns and environmental impact are considered to ensure long-term sustainability. A summary of barriers to CHP implementation in the industry is also included to provide a broad understanding of industrial CHP.

Flexible Hybrid Process for Combined Production of Heat, Power and Renewable Feedstock for Refineries

A flexible combined heat, power and fuel production concept, FlexCHX, is being developed for managing the seasonal mismatch between solar energy supply and the demand for heat and power characteristic of northern and central Europe. The process produces an intermediate energy carrier (Fischer-Tropsch (FT) hydrocarbon product), which can be refined to transportation fuels using existing refineries. The FlexCHX process can be integrated into various combined heat and power (CHP) production systems, both industrial CHPs and communal district heating units. In the summer season, renewable fuels are produced from biomass and hydrogen; the hydrogen is produced from water via electrolysis that is driven by low-cost excess electricity from the grid. In the dark winter season, the plant is operated only with biomass in order to maximise the production of the much-needed heat, electricity and FT hydrocarbons. Most of the invested plant components are in full use throughout the year with only the electrolysis unit being operated seasonally. The catalytic reformer plays a key role in this process by converting tars and light hydrocarbon gases into synthesis gas (syngas) and by bringing the main gas constituents towards equilibrium. Developmental precious metal catalysts were used, and an optimal reformer concept was established and tested at pilot scale. Reforming results obtained at pilot gasification tests with commercial nickel catalysts and with the developed precious metal catalysts are presented.

Εnergy-exergy analysis of ultra-supercritical biomass-fuelled steam power plants for industrial CHP, district heating and cooling

The use of biomass in combined heat and power (CHP) plants with district heating and cooling is necessary for achieving decarbonization targets. While in traditional biomass plants steam temperature is below 520 °C, new developments can lead to ultra-supercritical (USC) designs with steam temperatures of 600 °C. The present study investigates the performance of such plants for covering the heat demands of the aluminum and pulp and paper industrial processes, while also producing district heating and cooling. Plant performance is assessed through sensitivity analyses covering a wide range of heat demand scenarios. In the electricity-only scenarios, the electric and exergetic electric efficiencies of the aluminum/pulp and paper plants are 43.45/44.22% and 38.93/39.62%, respectively. In the CHP scenario, when the heat demand is maximized, the electric, exergetic electric, CHP and exergetic CHP efficiencies of the aluminum/pulp and paper plants are 21.81%/34.32%, 19.54%/31.70%, 92.50%/86.76% and 39.43%/39.01%, respectively. With the integration of cooling, the electric and CCHP efficiencies of the aluminum plant are 21.60% and 89.23%, respectively. Most of the exergy is destroyed during the combustion and steam generation processes, corresponding to 67–70% and 13–16% of the total exergy destruction, respectively.

New construction methodology-geothermal cogeneration plant efficiency improvements for environmental and economic sustainability using waste heat recovery system

Power station is used in geothermal cogeneration or Combined Heat and Power (CHP) plant to generate electric power and heat from a single process simultaneously. Industrial CHP gains attention due to its sustainability and its nature of carbon footprint reduction. In this regard, CHP is more effective than generating steam or burning fuel on-site, and electricity is imported from the grid. CHP is a combined system which finds applications in several techniques and thermal and fuel systems, and these functionalities can be integrated into prevail-ing building structures. In CHP, the modifications are carried out with respect to the energy and user requirements. In heat recovery mecha-nism of CHP plant, several critical parameters are required. The present research work focuses on heat recovery analysis in geothermal co-generation (CHP) plant, in which the methods to lessen the generated secondary (waste) heat is emphasized by enhancing energy efficiency. Further it also includes passive and active strategies. The recent trends of direct electric conversion devices are more useful, and therefore can be introduced in industrial waste heat recovery applications, which are usually applied in CHP or geothermal cogeneration plants includ-ing paper mills and chemical processing and refinery systems, hotels, hospitals, industries and commercial structures, where constant heat and power requirements exist.

Investigation of Different Operation Strategies to Provide Balance Energy With an Industrial Combined Heat and Power Plant Using Dynamic Simulation

Intermittency of renewable electricity generation poses a challenge to thermal power plants. While power plants in the public sector see a decrease in operating hours, the utilization of industrial power plants is mostly unaffected because process steam has to be provided. This study investigates to what extent the load of a combined heat and power (CHP) plant can be reduced while maintaining a reliable process steam supply. A dynamic process model of an industrial combined CHP plant is developed and validated with operational data. The model contains a gas turbine (GT), a single pressure heat recovery system generator (HRSG) with supplementary firing and an extraction condensing steam turbine. Technical limitations of the gas turbine, the supplementary firing, and the steam turbine constrain the load range of the plant. In consideration of these constraints, different operation strategies are performed at variable loads using dynamic simulation. A simulation study shows feasible load changes in 5 min for provision of secondary control reserve (SCR). The load change capability of the combined cycle plant under consideration is mainly restricted by the water–steam cycle. It is shown that both the low pressure control valve (LPCV) of the extraction steam turbine and the high pressure bypass control valve are suitable to ensure the process steam supply during the load change. The controllability of the steam turbine load and the process stability are sufficient as long as the supplementary is not reaching the limits of the operating range.

The job generation impacts of expanding industrial cogeneration

Sustainable economic development requires the efficient production and use of energy. Combined heat and power (CHP) offers a promising technological approach to achieving both goals. While a recent U.S. executive order set a national goal of 40GW of new industrial CHP by 2020, the deployment of CHP is challenged by financial, regulatory, and workforce barriers. Discrepancies between private and public interests can be minimized by policies promoting energy-based economic development. In this context, a great deal of rhetoric has addressed the ambiguous goal of growing “green jobs.” Our research provides a systematic evaluation of the job impacts of an investment tax credit that would subsidize industrial CHP deployment. We introduce a hybrid analysis approach combining simulations using the National Energy Modeling System with Input–output modeling. NEMS simulates general-equilibrium effects including supply- and demand-side resources. We identify first-order employment impacts by creating “bill of goods” expenditures for the installation and operation of industrial CHP systems. Second-order impacts are then estimated based on the redirection of energy-bill savings accruing to consumers; these include jobs across the economy created by the lower electricity prices that would result from increased reliance on energy-efficient CHP systems. On a jobs-per-GWh basis, we find that the second-order impacts are approximately twice as large as the first-order impacts.

An energy and carbon life cycle assessment of industrial CHP (combined heat and power) in the context of a low carbon UK

The UK has targets to reduce carbon emissions by 80% by 2050 compared to a 1990 baseline. The Transition Pathways research consortium has generated a set of three low carbon UK electrical futures, together with the corresponding technology mixes. All require a significant amount of technological change, including a significant increase in the contribution of CHP (combined heat and power). This study investigates the appropriateness of industrial CHP as a low carbon electricity generation technology for the UK via an environmental LCA (life cycle assessment) case study of an existing industrial CHP plant in UK. The study shows that harnessing the resource of industrial heat via straight forward CHP conversion can generate electricity with lower associated energy and carbon impacts than the current and the 1990 National Grids. However it is apparent that if the grid successfully reduces in carbon intensity, the technology will come at a comparative carbon cost.

Optimisation and selection of a steam turbine for a large scale industrial CHP (combined heat and power) system under Australia's carbon price

This paper describes an investigation in the optimisation of a steam turbine CHP (combined heat and power) system under three economic cases resulting from the introduction of a carbon price in Australia: no carbon price (case one); carbon price and not liable (case two); and a carbon price and liable (case three). A case study was considered for validation purposes. Steam turbine partial load equations and required pricing data under the various cases were derived. For this coal boiler steam turbine CHP system, the most economical situation was case two, and the least economical situation was case three. These results indicate the introduction of the carbon price has made the installation of these types of systems more attractive in terms of economic benefits as long as the system is not liable. All scenarios proved uneconomical with a natural gas boiler. The high price of fuel compared to the low cost of purchasing electricity resulted in recovered heat following the demand. This shortfall in electricity generation required the system to purchase the majority of its electricity demand from the grid in all three cases. Due to the low price of selling electricity, no excess electricity was produced in any investigation.

Optimal scheduling of industrial combined heat and power plants under time-sensitive electricity prices

Combined heat and power (CHP) plants are widely used in industrial applications. In the aftermath of the recession, many of the associated production processes are under-utilized, which challenges the competitiveness of chemical companies. However, under-utilization can be a chance for tighter interaction with the power grid, which is in transition to the so-called smart grid, if the CHP plant can dynamically react to time-sensitive electricity prices.In this paper, we describe a generalized mode model on a component basis that addresses the operational optimization of industrial CHP plants. The mode formulation tracks the state of each plant component in a detailed manner and can account for different operating modes, e.g. fuel-switching for boilers and supplementary firing for gas turbines, and transitional behavior. Transitional behavior such as warm and cold start-ups, shutdowns and pre-computed start-up trajectories is modeled with modes as well. The feasible region of operation for each component is described based on input–output relationships that are thermodynamically sound, such as the Willans line for steam turbines. Furthermore, we emphasize the use of mathematically efficient logic constraints that allow solving the large-scale models fast. We provide an industrial case study and study the impact of different scenarios for under-utilization.

A trading strategy for industrial CHPs on multiple power markets

SUMMARY In this paper, we propose an optimal bidding strategy for industrial combined heat and power (CHP) installations selling their power on multiple markets. This corresponds to the typical situation where power is traded on a day-ahead market (DAM) and a continuous intraday market (CIM). Each market has its own trading rules. The considered installations consist of a CHP, a conventional heating installation and a heat buffer. Each device has its own constraints, such as maximum and minimum deliverable heat and electrical power, and minimum and maximum buffer capacity. The objective is to determine the bidding strategy that will maximise the expected profit, while the future time evolution of both heat demand and market prices are unknown. To tackle this problem, we assume that the probability density functions (PDFs) of these variables are known or can be extracted from historical data. Then, by applying a tailored stochastic programming algorithm, the optimal bidding strategy can be constructed based on these PDFs and includes the different market rules and constraints on the installation. For a DAM, the bidding functions must be estimated in advance, which is a typical open-loop problem. On the other hand, the bidding functions for a CIM may be estimated almost in real time. This new scheme is exemplified for the Belgian market. Combining both markets can increase the expected profits significantly because risks due to uncertainties in heat demand are better controlled. Copyright © 2013 John Wiley & Sons, Ltd.

Sliding Back Pressure Control in Industrial CHP Plants

Operational characteristics and efficiency of the generation of electricity in combined heat and power (CHP) plants are discussed. CHP power plants produce both electric and heat power and the amount of the electric power can be adjusted by sliding the backpressure level in steam headers. The minimum back pressure level giving the maximum electric power output is detected by monitoring the positions of the load control valves in the steam consuming processes. Dynamic sliding of the backpressure level is carried out by a cascade control structure. The control structure is demonstrated in a simulator environment.

Exergetic comparison of efficiency indicators for combined heat and power (CHP)

Legislative regulations in favor of combined heat and power (CHP) production have been implemented in many countries. Although these regulations put different emphasis on power production vs. process heat production, they are based on energy quantities and not on exergy. In order to analyze and compare the exergetic consequences of the various legislations, a relative avoided irreversibility (RAI) is defined. This can be regarded as the exergy loss that is avoided when reference plants with separate production are replaced by an actual CHP plant. Some series of industrial and district heating CHP plants, under varying operational conditions, are used as test cases. It is seen that some, but not all, CHP cases are exergetically beneficial to separate generation. Comparison with the RAI allows a quantitative assessment of the various performance indicators. It is seen that exergetic improvements were only captured to a limited degree by the various energy-based efficiency indicators. Some legislatively defined indicators even appear to discourage thermodynamic improvements.

Process industry energy retrofits: the importance of emission baselines for greenhouse gas reductions

Fuel combustion for heat and/or electric power production is often the largest contributor of greenhouse gas (GHG) emissions from an industrial process plant. Economically feasible options to reduce these emissions include fuel switching and retrofitting the plant's energy system. Process integration methods and tools can be used to evaluate potential retrofit measures. For assessing the GHG emissions reduction potential for the measures considered, it is also necessary to define appropriate GHG emission baselines. This paper presents a systematic GHG emission calculation method for retrofit situations including improved heat exchange, integration of combined heat and power (CHP) units, and combinations of both. The proposed method is applied to five different industrial processes in order to compare the impact of process specific parameters and energy market specific parameters. For potential GHG emission reductions the results from the applied study reveal that electricity grid emissions are significantly more important than differences between individual processes. Based on the results of the study, it is suggested that for sustainable investment decision considerations a conservative emission baseline is most appropriate. Even so, new industrial CHP in the Northern European energy market could play a significant role in the common effort to decrease GHG emissions.

Parametric study of HRSG in case of repowered industrial CHP plant

The case study here presented deals with modernization of an industrial combined heat and power (CHP) plant located in a medium capacity steelworks industrial site. It is proposed to couple the existing power plant with a new gas turbine unit fired with Corex export gas. This fuel is a cold, low Btu by-product of the Corex process for pig iron production. The idea is to select the right distribution of heating surfaces in the heat recovery steam generator (HRSG) connected to a previously selected gas turbine and to the existing bottoming cycle in order to maximize the efficiency and economical profits of the whole plant. The study was performed using several simulation tools: a complete simulation of the system by means of engineering equation solver and a dedicated Fortran language code capable of performing all energy balances. For the correct design of the HRSG, a pinch analysis was applied. The whole set of simulation tools allowed comparing different solutions, of which the most promising ones are presented and discussed.

The adoption of cogeneration in the Japanese manufacturing sector: technological, economic and institutional determinants

Combined heat and power (CHP) has been identified by the Second and Third Assessment Report of the Intergovernmental Panel on Climate Change as a powerful carbon abating technology. In this paper, we review trends and overall changes in power generation technologies insofar as these affect industrial CHP in Japan; we also propose an empirical model for the analysis of CHP adoption based on time series cross-sectional (panel) data. This is followed by a discussion on current energy policy targets towards CHP and the changes in steam capacity (process heat) that have occurred during the period 1985-1998. Site information on 1500 CHP sites was gathered and combined with industrial statistics for a 14 year span during which Japanese power markets underwent deregulation. Based on the panel regression, we found that an increase in the probabilities of installing new CHP will be linked with a unit increase in purchased power, industrial production and consumption of self-generated power, while a unit increase in non-CHP boiler steam capacity will decrease the probability of adding CHP for the 7 industries. The fixed effects model showed that CHP faces increasing returns to scale over the period 1985-1998. Empirical work on CHP on cross sectional studies carried elsewhere confirms some of our findings. Additionally, it is found that adoptions of CHP are linked to the small to medium size industrial plants since the latter account for the mass of steam capacity retired.

The development of industrial CHP in the Netherlands

The development of industrial combined heat and power (CHP) in the Netherlands in the period 1968–1988 is studied in order to explore the factors that influenced this development, and particularly the effect of government measures designed to stimulate CHP. Between 1968 and 1988 1200 MW of CHP capacity was installed, mainly on the basis of gas turbines. Up to 1978 there was hardly any government policy directed towards the stimulation of industrial CHP. From 1978 onwards a number of stimulating measures have been introduced. From an analysis of the effects of government incentives on payback times we can conclude that some of the measures, among them the investment grants, had a considerable effect on the profitability of CHP investment.

Barriers and attitudes of the electric utilities to industrial CHP in the European community

In the European Community (EC) there is a growing recognition of combined heat and power (CHP) as a way of saving primary energy and of limiting emissions of noxious substances. In several member states, government authorities set new rules to support the access of CHP to the electricity market. The future of CHP in the EC looks certainly brighter than its past. Nevertheless, the realization of CHP projects is still troubled by a variety of barriers. We identified the barriers in the industrial CHP market and evaluated the attitudes of the electric utilities towards industrial CHP in the different EC member states. This article gives an overview of the main results. The analysis concludes that in several EC member states two important obstacles hinder the growth of industrial CHP: first, the gap between the fuel costs for central power generation and for CHP; second, the negative attitude of the electric utility(ies).