Central Heating Plants Research Articles

Accelerated carbonation of wood combustion ash for CO2 removal from gaseous streams and storage in solid form.

In this work, ash generated by the combustion of wood in a central heating plant was used to remove and permanently store by accelerated carbonation CO2 contained in a gas mixture simulating biogas. The process was studied as an alternative treatment to the ones currently available on the market for biogas upgrading. The process was investigated at laboratory scale by setting up a facility for directly contacting the wood ash and the synthetic biogas in a fixed bed reactor. The process was able to completely remove CO2 during its initial phase. After about 30h, CO2 started to appear again in the outlet stream and its concentration rapidly increased. The specific CO2 uptake achieved in solid carbonate form was of about 200g/kg of dry wood ash. This value is an order of magnitude higher than the ones found for waste incineration bottom ash carrying out similar experiments. The difference was ascribed to the physicochemical properties of the ash, characterized by a fine particle size (d50< 0.2mm) and high content of reactive phases with CO2 (e.g., Ca hydroxides). The leaching behavior of the wood ash was examined before and after the accelerated carbonation process showing that the release of several elements was lower after the treatment; Ba leaching in particular decreased by over two orders of magnitude. However, the release of the critical elements for the management of this type of residues (especially Cr and sulfates) appeared not to be significantly affected, while V leaching increased.

Use of an Ash-Slag Dump Mixture in the Production of Autoclaved Aerated Concrete

The article presents the results of investigating the composition, properties, and possibility of using the ash-slag mixture from the combined central heating and power plant No. 9 of the JSC Irkutskenergo as a siliceous component for the production of autoclaved aerated concrete. The composition of density grade D500 aerated concrete is selected. The developed composition and technology of producing aerated concrete were introduced at one of the enterprises in the city of Angarsk.

Model-free control of thermostatically controlled loads connected to a district heating network

Optimal control of thermostatically controlled loads connected to a district heating network is considered a sequential decision-making problem under uncertainty. The practicality of a direct model-based approach is compromised by two challenges, namely scalability due to the large dimensionality of the problem and the system identification required to identify an accurate model. To help in mitigating these problems, this paper leverages on recent developments in reinforcement learning in combination with a market-based multi-agent system to obtain a scalable solution that obtains a significant performance improvement in a practical learning time. In a first step, all relevant (and practically available) state information is collected from which a limited set of features is extracted, resulting in a low-dimensional representation of the system state. In a second step, a control action for the entire cluster is extracted from a policy determined offline. In a third and final step, this control action is dispatched over the different thermostatically controlled loads using a market-based multi-agent system. This process is repeated following a receding horizon approach. The control approach is applied to a scenario comprising 100 thermostatically controlled loads connected to a radial district heating network supplied by a central combined heat and power plant. Both for an energy arbitrage and a peak shaving objective, the control approach requires 60 days to obtain a performance within 65% of a theoretical lower bound on the cost.

Intelligent heat networks: First results of an energy-information-cost-model

Abstract Integrating additional renewable heat sources into district heating networks can have several beneficial effects, but it also requires more sophisticated control strategies than supply by only one central plant. In this article, we study the integration of prosumers (i.e. buildings which have both the capacity to produce and the need to consume energy, here heat) into heat distribution grids. This study is performed with a simplified model, based on energy and information flows. The prosumers can act autonomously, based on a price communicated by the central heat plant. This price is determined based on the benefit for the network by additional heat feed-in and is regularly updated. This leads to an interlocking of a physical/technical and an economic feedback loop. The control parameters are optimized by using a stochastic optimization algorithm, based on simulation runs for one typical week in winter, spring and summer. We compare the results with standard setups (heat network with only consumers, central heat generation and additional heat-producing building disconnected from the grid) and obtain an improvement concerning fuel consumption in most and concerning emissions in many situations. While economic benefits are achieved in most scenarios, it is a non-trivial task to construct a market model that distributes these benefits in a fair way between the central heat plant and the prosumers.

FUNCTION REGULATION OF CUSTOMER’S PLANT THAT BURN TRADITIONAL TYPES OF FUEL

This article deals with the issue of function regulation of customer’s plants that burn traditional types of fuel. Its aim was to develop certain measures for reducing customer’s plants influence on the Belarusian power supply system as their activity has unfavorable economic consequences. The following methods were used in the present research: the system analysis, the method of analogies and expenses calculation. The article presents the comparative characteristics of the power production during the typical working day of the heating period in the years 2013 and 2014 in terms of condensation power plants, central heating and power plants and customer’s plants. The potential damage caused by the customer’s plants to the power supply system has been calculated, the restrictions for the customer’s plants activity existing in the Republic of Belarus nowadays has been analyzed. The author has developed a number of measures within the framework of regulation policy of the activity of customer’s plants that burn traditional types of fuel: the fee for the spinning reserve necessary for the power supply system in case of the customer’s plants breakdown; the fee for the supervisory control; the fee for the service of transfer and distribution. The introduction of the proposed measures is supposed to bring the following advantages: high-quality growth of energy efficiency of the power industry; prime cost reduction of power energy in the power supply system as a whole; stimulation of market elements implementation in the power industry; the ability to react fairly fast to the alterations of economic conditions.

Everyday Radioactive Goods? Economic Development at Semipalatinsk, Kazakhstan

I first heard of “radioactive coal” in the summer of 2012, when I was living in the small village of Koyan, one of many settlements in Eastern Kazakhstan that hosted the Soviet-era Semipalatinsk Nuclear Test Site. A scandal over the sale of radioactive coal had erupted in the fall of 2011 when local media began reporting on a train from Kazakhstan carrying more than eight thousand tons of it (in 130 wagons) to a heating plant in Bishkek, Kyrgyzstan. Upon discovering that radioactivity in the shipment was eight times higher than normal, Kyrgyz authorities had it removed from the Bishkek's central heating plant. Rather than discarding it, they put it to use elsewhere, including in the heating stoves of more than one orphanage, a kindergarten, and several rural schools. When media covered this development, public outcry forced Kyrgyz politicians to demand that the coal be returned to Kazakhstan; allegations of corruption and arrests of Kyrgyz officials ensued. Political wrangling over responsibility and refunds meant that negotiations between Kazakh and Kyrgyz authorities took more than a year to complete. Finally, Kazakhstan allowed the coal to be returned.

A Comparative Cost Assessment of Energy Production from Central Heating Plant or Combined Heat and Power Plant

Abstract The levelized cost of electricity (LCOE) is a common approach in evaluating the economic competitiveness of a power generation technology. The same approach can be applied for evaluating the levelized cost of heat (LCOH) production. There are a number of approaches in calculating the LCOE and or LCOH from a combined heat and power (CHP) plant. In this study, we explore three alternative methods in calculating the LCOE and LCOH of a CHP and compare the results with that those of a heating only plant. The results can be used as indicators for identifying a suitable pricing mechanisms for the heating market.

Development of the Circulating Fluidized Bed Combustion Technology: Studies of CFB Technology at VTI and the Justification for its Use in Russia1

The current state of and progress in circulating fluidized bed (CFB) technology are reviewed. The CFB technology has been used industrially in the boilers of generating units with powers up to 600 MW. CFB boilers are most widely used in China. The steam parameters and unit powers of systems with CFB boilers are increasing. CFB technology has the advantage of being able to burn a wide range of fuels, including biomass and process wastes, and this is a further stimulus for the introduction of CFB boilers. Based on studies of the hydrodynamics and heat exchange in model CFB boilers and generalizations of published data on advances in the design of CFB boilers, recommendations for the basic dimensions and performance of ash collectors and recovery systems in CFB boilers have been developed at the JSC “VTI” to ensure reliable determination of the major characteristics of boiler designs. Design methods and programs have been formulated. Recent designs for advanced coal-fired central heating and power plants at VTI confirm the suitability of CFB boilers for widespread use. The first CFB boiler in Russia is being installed and tested at the 330 MW unit No. 9 of the Novocherkassk GRES State Regional Electric Power Plant. Experience with the installation and startup of this unit will create the conditions for widespread introduction of CFB technology in Russia.

Foamer Influence on the Foam Concrete Properties Obtained in the High-Speed Foam Generator

Recently, there has been an increasing interest to the production of the non-autoclaved aerated concrete. It has a number of advantages in comparison with other materials: low power consumption of manufacturing, high fire resistance, environmental safety, bio persistence, as well as excellent insulation properties. However, its production involves a number of problems: insufficient ultimate strength, high shrinkage, high susceptibility to the parameters of technology, and the quality of raw materials. It is a well known fact that the formation of the foam concrete structure and its main running abilities are affected not only by the mortar part, but also by the chemical nature of the foaming additive, its basic physical and chemical characteristics, as well as by the parameters of foam, produced on its basis.The paper contains an assessment of availability of the technical foam production for manufacturing of the heat-insulated constructional foam at a high-speed cavitation plant involving use of fly ash from the Central heating and power plant. We used the protein and synthetic foaming agents for the work. The authors investigated the influence of process-dependent parameters of a laboratory plant on the technical foam density and foam stability coefficient in the cement paste. The physical and mechanical properties of the non-autoclaved aerated concrete produced with investigated foams are defined. The non-autoclaved aerated concrete samples with physical and mechanical properties allowing its use in production are produced.

Distribution of Indirect Costs on the Basis of the Matrix Approach (as Exemplified by CHP Plant of Cogenerated Type)

Background: One of the most effective management tools is a calculation of the total cost of products, works and services, which, as part of the fuel and energy complex, is complicated by the presence of multi-stage production processes, and is currently carried out at most business entities in a simplified manner with the exception of some cause-and-effect relationships. Methods: In the present study different results of calculations of the total cost of products and semi-finished products using both existing and the proposed approaches to the problem are simulated. The analysis of the problem relating to the distribution of indirect expenses at Central Heating and Power Plant (CHPP) of cogeneration type is given; the advantages and disadvantages of the most common current traditional approach to the allocation of costs are revealed; the mathematical model of indirect costs distribution is proposed based on back-directed technological ties. Findings: The traditional approach to cost allocation and full cost formation is unable to determine the above index in case of material counter-flows, which is a characteristic feature of complex technological networks in organizations and for the interaction within groups of companies (holding companies). This disadvantage is excluded in the proposed by the authors approach based on the use of mathematical apparatus of matrix algebra, which is more consistent with modern information technologies used in the practice of organizations (the concept of ‘Spreadsheet’), and which, ultimately, will enable to introduce painlessly the proposed method of full cost evaluation in practice. Improvements: The proposed model and methods of its use allow improving the indirect cost allocation mechanism in the process of calculating the total product cost of CHPP.

Приоритеты модернизации энергетической инфраструктуры в сельской местности Республики Коми

The article presents the problems of development and modernization of energy infrastructure priorities in rural areas of the Komi Republic. For the most part of rural population the achieved level of energy supply is the necessary minimum for the needs, and it has the low parameters of the energy and economy efficiency. The main directions of the rural energy supply modernization should be: the gas supply system development, the electric grid capacity growth and the construction of the modern small energy technologies (small central heating and power plants, modular boiler plants, efficient solid fuel boilers).

VACUUM-CAVITATION DEAERATOR OF SAMARA STATE DISTRICT POWER STATION

The paper presents the results of the experimental research of vacuum-cavitation deaerator of streaming water used in Samara state district power station. A study of the experimental model of this deaerator and its pilot industrial installation allowed the introduction of vacuum-cavitation deaeration in the central heating plant of Samara state district power station.

Hydrothermally modified fly ash for heavy metals and dyes removal in advanced wastewater treatment

Fly ash resulted from coal burning is a waste that can be used in wastewater treatment for removal of dyes and heavy metals by adsorption.Class “F” fly ash (FA), collected from the Central Heat and Power (CHP) Plant Brasov (Romania), with oxides composition SiO2/Al2O3 over 2.4 was used for obtaining a new substrate with good adsorption capacity for dyes and heavy metals from wastewater. A new material was obtained from modified fly ash with NaOH and hexadecyltrimethylammonium bromide (HTAB) a cationic surfactant. Contact time, optimum amount of substrate and the pH corresponding to 50mL solution of pollutants were the parameters optimized for obtaining the maximum efficiency in the adsorption process. The optimized adsorption parameters were further used in thermodynamic and kinetic studies of the adsorption processes.The adsorption kinetic mechanisms, and the substrate capacities are further discussed correlated with the surface structure (XRD), composition (EDS, FTIR), and morphology (SEM, AFM).The results indicate that the novel nano-substrate composite with fly ash modified can be used as an efficient and low cost adsorbent for simultaneous removal of dyes and heavy metals, the resulted water respects the discharge regulations.

The microspheric catalysts of sodium sulphite low-temperature oxidation by oxygen in water solutions

The composition and structure of the microspheric alumosilicates of Central Heating and Power Plants (CHРP) ashes is studied with the help of modern physical-chemical methods (XRD, scanning electronic microscopy, BET, elemental and chemical analysis). The microspheres activity in the reaction of Na 2 SO 3 oxidation by oxygen is studied by kinetic and potentiometric methods. By means of EPR and Moessbauer spectroscopy it is established that iron enter into the composition of cenospheres in two states Fe 3+ and Fe 2+ , thus, in the field of the iron content 3-4 wt. % the iron (3+) is in the form of single ions in an aluminosilicate matrix.

Fly ash adsorbents for multi-cation wastewater treatment

Class “F” fly ash (FA), collected from the Central Heat and Power (CHP) Plant Brasov (Romania), with oxides composition SiO2/Al2O3 over 2.4 proved good adsorbent properties, and was further used for obtaining a new substrate with good adsorption capacity for heavy metals from multi-cation wastewater treatment. Firstly, the new adsorbent was characterized by AFM, XRD, DSC, FTIR and the surface energy was evaluated by contact angle measurements. The experimental data suggested that the new type of substrate is predominant crystalline with highly polar surface.The substrate was used for removing the Pb2+, Cd2+ and Zn2+ cations from mixed solutions. The results show high efficiency and selective adsorption the Pb2+ and Zn2+ cations.The optimized adsorption parameters were further used in thermodynamic and kinetic studies of the adsorption processes. The Langmuir and Freundlich models were used to describe the processes. The pseudo-second order kinetics could well model all the processes, indicating a surface concentration of the adsorption sites with the same order of magnitude as the cation concentrations.

Neutronic Design and Analysis of a Small Nuclear Reactor to Supply District Heating and Electrical Energy to Canadian Forces Bases Located in the Arctic or the Northern Remote Communities

The present work describes the preliminary design of a 25-MW(thermal) nuclear reactor capable of providing safe and reliable heating and electricity to any Canadian Forces Bases, especially in the Arctic, as well as in comparable civilian applications. The aim of the project is to provide a nuclear reactor system with sufficient inherent safety characteristics as it is intended to run in automatic mode and be monitored by operators with limited experience and training. For the neutronics calculations, the design work of the reactor’s core is carried out using the probabilistic simulation code MCNP 5 along with the Winfrith Improved Multigroup Scheme–Atomic Energy of Canada Limited (WIMS-AECL) deterministic code, Version 3.1, thus permitting a code-to-code comparison of the numerical results. Several design constraints related to coolant temperature and pressure, reactivity control, fuel enrichment, and time between refueling have been considered. The final reactor concept, named the Super Near Boiling 25 reactor (SNB25), provides heat energy dedicated to building and domestic water heating and supplies electricity through an organic Rankine cycle energy conversion plant. SNB25 employs TRISO fuel particles, contained in zirconium-sheathed fuel rods, and is light water cooled and moderated. Complete reactivity control is achieved through simple and reliable mechanical means consisting of 133 control rods and six adjustable radial reflector plates. The optimized reactor core configuration, along with its intrinsic control system, allows for the power plant to operate safely for more than a decade between refuelings from a typical central heating plant or the basement of a multilevel office building. The work also included a preliminary investigation of the nonnuclear part of the energy supply system including heat exchangers and the turbine-driven, electricity-generating system.

Element budgets of forest biomass combustion and ash fertilisation – A Danish case-study

Harvest of forest biomass for energy production may lead to a significant export of nutrients from the forest. Ash spreading and recycling of nutrients from wood chip combustion to the forest has come into focus as a means for counteracting the nutrient export. This study was carried out to examine the retention of various elements in the different ash fractions and utilise the nutrient recovery to evaluate the fertiliser quality of the examined ash. The mass and element flux of wood chips, bottom ash, cyclone fly ash and condensation sludge at Ebeltoft central heating plant was studied over a four day period in spring 2005. On average, 19 ton wood chips (dry weight) were combusted each day. The combustion of the wood chips produced 0.70% ash and sludge (dry weight). The ash and sludge dry matter was distributed as 81% fly ash, 16% bottom and residual grate ash and 3% sludge solid phase. Substantial amounts of nutrients were retained in the fly ash (P, Ca, Mg, Mn and Cu have a recovery higher than 60% and K, S and Fe have a recovery higher than 30%). The recovery of elements in the bottom ash was smaller. The added recovery of the usable fractions of ashes (both fly ash and bottom ash) exceeded 75% for the nutrients P, Ca, Mn and Mg. Both these ash fractions should be considered for fertilisation.

Technologic, economic and exergoeconomic evaluation of proposed industrial heat and power plant revamp alternatives in an industrial company in Slovakia

Both European and Slovak legislation seek to promote efficient energetic media production with the support of old facilities, revamping being one of the embedded means. Based on our cooperation with Slovak industry, we analyzed several gas turbine based revamp alternatives of an industrial central heat and power plant of a paper mill in Slovakia from the technical, economic and exergoeconomic point of view, the latter being not yet applied in Slovakia to such a complex problem. The proposed alternatives exhibit a 45–55% marginal electric efficiency. However, at the given electric energy and natural gas prices and due to high fix production costs, individual project economics cannot ensure an attractive payback period unless providing ancillary services extensively. Overall and marginal results of the steam exergoeconomic costing procedure indicate that the proposed revamp alternatives are not able to provide cheaper electric energy than the existing configuration but they can produce cheaper low pressure steam for industry. The presented analysis provides a scheme and methodology for Slovak industry to properly cost the energetic media production.

Quantifying the effects of climate change and risk level on peak load design in buildings

Good building design aims to balance providing a comfortable internal environment for as much of the time as possible within a variety of constraints. An important factor is the expected weather, but in a changing climate this poses additional challenges to engineers and architects. This paper examines the effects of increased external temperature on the size of the central air conditioning and heating plant for an example building. It is found that for each 1°C rise in external temperatures, the peak cooling load increases approximately by 10%, the chiller power by 14% and fan power for distribution by 30-50%. These are relatively large increases in power needed to counteract rising external temperature and the paper considers the choice of risk level for sizing building plant. From HadRM3 data, the future frequency distribution of higher external temperatures is examined to evaluate the effects on plant size of designing to a fixed percentile of risk. Projected changes in absolute humidity are also discussed. Practical applications: Climate change is an important topic for building services engineers, resulting in the UK in the new, performance-based Building Regulations Part L. New, future weather data will also become available with different climate change scenarios. This paper examines the implications of both climate change and the risk level on the peak load for natural ventilation or air conditioning and heating that is used in the design of systems.

Linear approximant-based metaheuristic proportional-integral-derivative controller for a neutral time delay central heating system

For a test-case central heating plant, modelled as a non-linear neutral time delay system, a metaheuristic proportional-integral-derivative (PID) control scheme is proposed to control the temperature of the room using as a sole actuatable input the energy supplied to the boiler. The control scheme is based on a neutral time delay description of the linearized approximation of the process. The linearization is tested using a Euclidian norm type of error, with emphasis on the performance variable of the system, to show that it is an accurate approximation of the original process for a wide range of variables of the plant. The performance of the closed-loop system is examined via simulation experiments.