Heat Plant Research Articles

INFLUENCE OF PRESSURE IN THE TURBINE CONDENSER ON HEAT SUPPLY EFFICIENCY OF NPP WITH HEAT PUMP

The use of a heat pump for heat supply makes it possible to practically stop thermal pollution of the environment during the operation of thermal and nuclear power plants in winter. If a steam turbine condenser is used as a low-potential energy source for heat pump, the amount of released thermal energy will be equal to the sum of the thermal power of the NPP condenser and the power of the heat pump compressors. From the point of view of environmental safety, heat supply by combining power plant with a heat pump is an urgent task. But it is known that the due to the lack of steam extraction for water heating, the additional electrical power of the cogeneration heat and power plant will be less than the capacity of the heat pump compressors. Thus, in terms of thermodynamic efficiency, the use of a heat pump loses to a traditional cogeneration plant. The purpose of the work is to determine the influence of the final pressure in the turbine condenser on the thermodynamic efficiency of a nuclear power plant with a heat pump. A mathematical model of the thermal scheme of the K-1000-5.8/1500 NPP turbo-plant during summer and winter operation with heating plant has been developed. With the heating plant capacity of 230 MW, the electric capacity of NPP unit decreases by 43.5 MW. A mathematical model of a heat pump has been developed, for which a steam turbinecondenser is used as a low-potential energy source. To ensure the release of 230 MW of heat, the power of the heat pump compressor must be 48.4 MW. Thus, if the heating plant is replaced with a heat pump of the same capacity, the electric power will decrease by 4.8 MW. Calculations were made regarding the influence of the final pressure in the condenser on the exergetic efficiency of the NPP with heat pump, which uses the entire capacity of the turbine condenser. The analysis of the obtained results showed that the exergetic efficiency due to the increase in electric power released in winter increases with the increase of the final pressure in the condenser. This is explained by an increase in the heat pump coefficient of performance.

AERMOD air dispersion modeling and health risks of gas and oil fueled heating plant emissions

A significant part of the population in Serbia relies on central heating systems during the winter months, with around fifty heating plants in operation across the country. Common fuels used in these plants primarily include fossil fuels such as fuel oil and natural gas. Combustion of some of these fuels leads to significant emissions of air pollutants. This study evaluates the impact on the air quality of the two heating boilers at the Valjevo city (Serbia) heating plant. Air emissions were measured separately for two heating boilers in the facility using standard reference methodology. The AERMOD air dispersion model was used to estimate the dispersion of various pollutants. A combination of topographical and meteorological data was used to set up a receptor grid exposed to air pollution within a 10 km radius around the heating plant. It was found that the resulting distribution and concentration gradient of pollutant gases and particles were less inclined towards the city centre and instead spread eastwards into the surrounding villages. The health risk from the fuel oil boiler was shown to be significantly higher than that caused by the natural gas-fuelled boiler. Nevertheless, the calculated carcinogenic and non-carcinogenic health risks were within acceptable limits. However, further research is required to adequately assess the cumulative health risk generated by other surrounding emitters.

Computer thermodynamic modeling of the producing silicon alloys from the Kentau Combined Heat and Power Plant ash

The article presents the results of studies on the production of silicon alloys from the Kentau Combined Heat and Power Plant ash by the computer thermodynamic modeling method using the HSC-6.0-Chemistry software package. The effect of temperature (from 500 °C to 2000 °C) and the amount of carbon (from 30% to 40% of the ash mass) on the equilibrium distribution degree of elements between the condensed and gas phases, the grade of resulting ferroalloys. In the system under consideration, the formation of FeSi25 ferrosilicon occurs in the temperature range of 1500-1530 °C, and FeSi45 ferrosilicon-at the temperature of 1610-1700 °C; FS50 ferrosilicon is formed in the temperature range of 1700-1900 °C in the presence of 30% of carbon. The formation of FeSi45A10 ferrosilicoaluminium is possible at 2000 °C and 30% of carbon, in this case the concentrations of the metals in the alloy are 46.51% of Si, 8.57% of Al; 42.27% of Fe. FeSi45A15 ferrosilicoaluminium is formed in the system at 40% of carbon and 2000 °C; the elements’ concentrations in the alloy are 45.62% of Si, 14.76% of Al, 37.29% of Fe. Processing of 1 tonne of the ash makes it possible to produce 459 kg of FeSi45A10 ferrosilicon

Sales of electricity from cogeneration plants on organized markets in Southeast Europe

Volatile energy prices in the past period, force countries and their market participants to find alternative and cheaper sources of electricity production, while respecting defined environmental principles. Serbia is one of the rare European countries that uses its reserves of dissolved gas in the heat and electricity production. Combined heat and power plants, although in an almost negligible amount, contribute to the diversification of Serbia's production mix. With the presence of organized markets and local power exchanges, sale of electricity from combined heat and power plants is guaranteed for all producers who do not meet the conditions for acquiring the right to feed-in tariffs. The aim of this paper is to analyze the most profitable sale on the power exchanges of the domestic market and the region, specifically the markets of Serbia, Croatia, Hungary, Romania, and Bulgaria. The calculation methodology itself implies the use of average monthly price value for the observed markets, in the period of the past three years and nine months. In addition to the aforementioned, the costs of cross-border capacities were considered. In order to have a clearer overview of the results and the possibility of applying the methodology, the amount for calculation is 1 MWh. Costs and revenues related to negative and positive balance energy deviations are excluded from the analysis. Results showed that sale of electricity is most profitable on Serbian power exchange.

Assessment of economic efficiency of combined power plants based on renewable energies

Energy plants based on renewable energy sources can be combined according to the type of energy source (hydro, solar, wind with or without hydro storage). Currently, not enough attention has been paid to assessing the economic efficiency of combined power plants incorporating a hydraulic accumulator. When designing combined power plants, it becomes necessary to choose the composition of such plants and evaluate their economic efficiency. The purpose of this study is to justify the possibility of applying the present value method to select the composition of combined heat and power plants and assess their economic efficiency. The research used the following methods: review, synthesis of existing literature on the subject, system analysis, collection of data on different types of power plants, and calculation of their economic efficiency. A computer program has been compiled with Turbo Pascal 7.0 for the calculations. The calculations have shown that a cost-effective option is a combined power plant based on a wind power plant and a hydropower plant with a hydro accumulator.

Innovative solutions in the energy sector

Combined heat and power plants (CHPPs) allow for significant savings in primary energy resources and a reduction in environmental pollution. Mostly it is carried out using steam turbines. However, in the eighties of the twentieth century, a new promising direction in the development of cogeneration appeared. These are plants operating on the organic Rankine cycle (ORC). An analysis of energy innovations abroad is required for the development and adaptation of this direction to Russian realities. Therefore, an analysis of the energy and environmental efficiency of high-moisture biofuels and biofuel mixtures with high ash content was carried out in boilers operating as part of a CHP using ORC technology and traditional steam turbine plants. Some recommendations for the innovative development of small and medium-scale power generation were proposed.

Optimization of schemes and ways to expand the adjustment range for the power supply of combined heat and power plants

The article assesses the possibility of using low-flow operating modes at steam turbine with an additional boiler and steam and combined-cycle cogeneration plants for heat supply schemes, taking into account the storage properties of heat networks and buildings. It is shown that the use of low-flow operation modes of the turbine plant during the night period allows the combined heat and power plant to participate more effectively in covering the variable part of the electric load schedule. The dependence of the share of participation of an additional boiler in covering the heat load on the prices for fuel and electricity is determined. Comparison of the performance indicators of the steam turbine CHPP in low-flow modes with the release of the thermal energy necessary to the consumer from an additional boiler with the mode of its complete shutdown and the release of thermal energy from the peak hot water boiler made it possible, taking into account the accumulating properties of heat networks and buildings, to recommend a low-flow operation mode at night. For a combined-cycle cogeneration plant it is shown that it is advisable to reduce the electric power at night, while ensuring the nominal heat supply, by unloading the gas turbines with the transfer of the steam turbine to the motor mode.

Artificial intelligence control system of heat recovery in thermal power plant

In order to improve the comprehensive utilization rate of energy in power plants, the author puts forward the research of artificial intelligence control system for heat and power plant waste heat recovery. In the heating system of waste heat recovery, intelligent time-sharing and zoning control is set according to user needs, which enables the heating system to adjust the temperature of heating water outlet in real time according to the dynamic change of outdoor climate, in the heating system of waste heat recovery, intelligent time-sharing and zoning control is set according to user needs, which enables the heating system to adjust the temperature of heating water outlet in real time according to the dynamic change of outdoor climate. The results show that the energy saving rate of time-sharing heating increases with the increase of outdoor temperature, when the outdoor temperature is 8?C, the energy saving rate is 0.35, in addition, the energy saving rate of the heating system is not only related to the outdoor temperature, but also to the length of the intermittent period, it is obvious that the longer the intermittent period is, the higher the energy saving rate is. In conclusion, the application of time division temperature control technology in the heating system greatly improves the energy saving effect of buildings, saves energy, and has extremely high economic, environ?mental and social benefits, which is worth advocating and promoting.

Ecological analysis of the impact of the ironic activity of the public joint-stock company “Kherson heat and power plant” on the component of the environment city of Kherson

Ecological analysis of the impact of the ironic activity of the public joint-stock company “Kherson heat and power plant” on the component of the environment city of Kherson

Frost Damage Index: The Antipode of Growing Degree Days.

Abiotic stresses such as heat and frost limit plant growth and productivity. Image-based field phenotyping methods allow quantifying not only plant growth but also plant senescence. Winter crops show senescence caused by cold spells, visible as declines in leaf area. We accurately quantified such declines by monitoring changes in canopy cover based on time-resolved high-resolution imagery in the field. Thirty-six winter wheat genotypes were measured in multiple years. A concept termed "frost damage index" (FDI) was developed that, in analogy to growing degree days, summarizes frost events in a cumulative way. The measured sensitivity of genotypes to the FDI correlated with visual scorings commonly used in breeding to assess winter hardiness. The FDI concept could be adapted to other factors such as drought or heat stress. While commonly not considered in plant growth modeling, integrating such degradation processes may be key to improving the prediction of plant performance for future climate scenarios.

Wood waste ash Re-Use. Mechanical performance and durability for mortars

Wood waste ashes from a thermal biomass heating plant were used as a supplementary cementitious material in partial substitution of ordinary Portland cement. The ashes undergone a chemical analysis with respect to their heavy metal content. They exhibited values below the required legislation limits and could be used for the tests. Mechanical and durability tests were carried out on mortars specimens with the addition of wood waste ashes to ordinary Portland cement (OPC) in percentages of 5, 15, and 30%. The strength properties of mortar mixtures increased with age due to pozzolanic actions. This was observed with the 5–15% WWA addition. The OPC reference blend with 5% WWA in substitution of cement exhibited the best data and a satisfactory durability. The values obtained were similar or below the required limits for the resistance as compared to the mortars prepared with the reference Portland cement.

Співставлення варіантів розташування теплових насосів для гарячого водопостачання від АЕС

Fuel consumption for heat supply makes up about a third of the total amount of fuel and energy resources consumed in the country, and this value is twice as large as the amount of fuel consumed for electricity production. This means that in order to solve the problems related to climate change, it is necessary to use nuclear power plants (NPP) more widely in the direction of heat supply. The way to reduce heating costs is to use cogeneration. As the experience of using combined heat plants shows, fuel savings due to the combined production of electric and thermal energy is 13 % of the fuel consumption for electricity production. In the future, heat supply from NPPs should expand. This saves energy resources and reduces the burden on the environment. The use of steam condensation heat in the condenser of the NPP turbine as a low-potential source for a heat pump (HP) is considered. In this case, thermal pollution from the NPP is reduced. Currently, taxes for thermal pollution from NPPs are not charged, but, considering that this is one of their disadvantages and the great attention of humanity to the preservation of the environment, such taxes may soon be introduced. The work considers two options for the location of heat pumps to provide hot water supply to the city of Varash from the Rivne NPP: 1. Location of a powerful HP directly next to the NPP and transportation of hot water to the city. 2. Transportation of circulating water, heated in the condenser, to the city to provide HPs located near consumers. The comparison of these options was carried out on the basis of reduced costs, which took into account the cost of HPs, heat losses during the transportation of hot water and the cost of electricity for pumping. When taking into account the cost of HPs, the well-known formula for the dependence of specific equipment costs depending on capacity was used. As a result of the comparison, it was determined that the first option has the advantage. In the structure of reduced costs, the main contribution is made by the cost of heat pumps.

Importance of HVAC System Selection in Reducing the Energy Consumption of Building Retrofits–Case Study: Office Building in London

The analysis of the holistic life cycle and energy has become more important due to the escalating energy demands in existing office stock. HVAC system retrofits to save energy are an outstanding way when compared to envelope improvements. The study proposes a parametric workflow to analyze and reduce energy, carbon and cost in HVAC retrofits. Based on the workflow, the energy demands of an existing office building were gathered using energy modelling software. The results then were calibrated with the building's energy data. Using the equation-based modelling workflow, HVAC plant side systems were simulated parametrically to calculate energy, carbon and cost. In total, 5184 iterations of 10 interventions were tested. It was found that heating plant type and heat recovery were the prominent savings inputs in the case study. The study presented a comprehensive approach to the HVAC system retrofit of existing buildings, which uses real energy data calibration, verifiable, and parametric methods.

Study on the cost effectiveness of a combined evaporation unit

In a thermal power plant, water treatment plants are used to perform body losses in the main steam cycle using one of the following methods of water preparation: chemical, thermal, membrane or combination of them. One of the main advantages of thermal desalination is the low impact on environmental pollution. In the light of the ever-increasing environmental demands on energy processing systems, thermal desalination is becoming an increasingly preferred method of water treatment, since it allows wastewater to be used as feed water for evaporators. In our country, multi-stage evaporation units are quite widespread. They are used as operating units in industrial heating plants and as backup for condensation plants. These units have high thermal costs and are characterized by an excess of secondary vapour of the last evaporation step, which needs to be continuously removed from the plant to avoid loss of productivity. The main objective of this work is to minimize the total and thermal costs of the production of additive water in the main steam turbine cycle of the thermal power plant and the treatment of wastewater in evaporation complexes, as well as to determine the technical economic effectiveness of applying some technical solutions for the recovery of excess steam in multi-stage evaporation units.

Determining the ecophysiological limits of a narrow niche tropical conifer tree (Podocarpus trinitensis).

Many tropical species live close to their thermal limits within a narrow niche. Here, we investigate the ecophysiological limits of the tropical tree Podocarpus trinitensis, which is endemic to Trinidad and Tobago where most populations exist as isolated stands on hilltops. Five wild stands from a range of elevations were compared in the field with measurements of leaf temperature, canopy cover, stomatal conductance (gs), chlorophyll content and several chlorophyll fluorescence parameters. A parallel greenhouse experiment was used to acclimate seedlings to 'CONTROL' and 'HEAT' treatments (with mid-day air temperatures of 34.5 and 37°C respectively), after which the above parameters were measured along with photosynthetic light and temperature response curves, leaf morphology and in vitro Fv/Fm thermostability. There was a positive association between improved physiological performance and elevation. In the high elevation sites, leaf temperatures were significantly lower while most of the physiological parameters were higher (gs, chlorophyll content, ɸ PSII, ETRmax and Isat90). In the greenhouse, HEAT and CONTROL plants were similar for most parameters, except leaf temperature (which was coupled with air temperature) and leaf mass per unit area (which was higher in HEAT plants). Temperature response curves showed an optimum temperature for photosynthesis of 30±0.5°C (TOpt) and in vitro Fv/Fm indicated a critical temperature of 47.4±0.38°C for HEAT and 48.2±0.24°C for CONTROL (T50), with no indication of heat acclimation. Podocarpus trinitensis was found to be shade tolerant. In the field, seedlings established under a close canopy (>95% canopy cover) and had a low light saturation point (LCP). In the greenhouse, where more light was available, seedlings retained a low light compensation point, light saturation point (LSP) and maximum photosynthetic rate (Amax). The results suggest that P. trinitensis is moderately heat tolerant with the higher elevation sites being more habitable, but stands are also able to survive near sea level under a closed canopy. The narrow niche, along with the 30±0.5°C optimum temperature for photosynthesis and the lack of thermal plasticity in critical temperature, suggests that P. trinitensis has little room to acclimate to temperatures higher than those currently experienced.

Physical and mechanical properties of ceramic brick using rice husk and ash of thermal power plants

The paper presents the results of the influence on shrinkage deformations of the adopted composition during the drying and firing of ceramic bricks made using rice husk and ash of the combined heat and power plant of the city of Kyzylorda of the Republic of Kazakhstan. The optimal values of the husk additives content and ash from thermal power plants in the studied compositions were determined. Ash dumps from thermal power plants (TPP) create environmental tension and pose a great threat to both the environment and human health. It was found that the hydro-removal ash from the thermal power plant mainly consists of oxides of silica (45.45…46.37 %) and alumina (16.62…17.70 %), there are oxides of calcium (1.66…2.20 %), magnesium (0.86…1.12 %), iron (2.98…3.41 %) and alkali metals (0.80…1.04 %). The composition of ceramic bricks based on loess-like loam, rice husks, and ash from thermal power plants was studied. The charge composition of the raw components of the “clay, TPP ash, and rice husk” brick: clay is 71…75 %, TPP ash is 18…22 %, and rice husk is 2…6 % of the total mass of the components of the raw mixture of ceramic bricks. The compressive strength of fired ceramic bricks was 11…12 MPa. According to the results of experimental studies, it was found that the increased concentration of rice husks in natural mixtures is characterized by a stable increase in ceramic mass drying cracks. The increase in time until the appearance of drying cracks is 100 up to 160 sec. The resulting ceramic brick in accordance with the developed composition has a low weight, good thermal properties and meets the standard requirements for ceramic bricks according to GOST 530-2012

Techno-economic-reliability assessment of a combined NGL refinery and CCHP system driven by wasted energy of flare and flue gases

Due to their improved functionality and increased efficiency, hybrid flare and flue gas recovery methods have drawn attention. Applying these methods removes flare gas in the oil wells and hot flue gas in the power plant, and a combination of flare gas recovery with hot flue gas recovery is more environmentally friendly as it increases the energy efficiency of the technologies. Integrated heating, cooling, and electricity generation plants composed of a gas turbine, a natural gas liquids refinery, and an absorption chiller were proposed as a hybrid system for flare and flue gas recovery in an oil well. The generated cooling was used in the natural gas liquids refinery and inlet air cooling of the gas turbine. Thermo-economic analysis was applied to the system with consideration of the recovery of heat from the gas turbines’ hot flue gas. The reliability of its downstream installation was examined. The sensitivity analysis showed that the proposed system is very economical even at low electricity prices, and the most sensitive equipment is the NGL’s recovery section.

Evaluation of the effectiveness of technological measures to manage the risk to public health when exposed to atmospheric emissions of multi-fuel combined heat and power plants

AIM: To assess the effectiveness of technological measures to manage the risk to public health of exposure to atmospheric emissions from multi-fuel combined heat and power plants (CHP).
 METHODS: The study involved modeling the dispersion of emissions from the thermal power plants, calculation of surface concentrations, assessment of carcinogenic and non-carcinogenic risks to public health, and estimating the relative risk of mortality, referrals and hospitalizations based on WHO guidelines on atmospheric air quality. Predictive scenarios were constructed for thermal power plants, including the initial state, modernization with the help of technological and sanitary measures, and changes in the structure of the fuel balance.
 RESULTS: The use of low-temperature vortex fuel combustion technology in combination with a modernized dust and gas cleaning system significantly (p 0.001) decreased the predicted carcinogenic risk index by an average of 80.67%, non-carcinogenic risk index by 78.84%, and relative mortality risks and referrals to medical organizations by more than 80%. The use of a gas turbine plant increased the production of electric energy by 72.23%, thermal energy by 4.89%, and significantly (p 0.001) reduced the level of carcinogenic risk by 4460%, non-carcinogenic risk by 3547%, and relative risks of mortality, visits to medical organizations and hospitalizations by 3364%.
 CONCLUSION: The use of the best available technologies to modernize multi-fuel CHP plants significantly reduces the level of risk to public health while it increases the production of electric and thermal energy and maintaining the advantage of using both solid and gaseous fuels.

FEATURES OF THE USE OF LIQUEFIED PETROLEUM GAS AS A RESERVE AND ALTERNATIVE FUEL AT COAL-BASED CHP PLANTS

The paper analyzes the main properties of liquefied petroleum gas and the peculiarities of its energy use compared to natural gas, including taking into account the specifics of the operation of pulverized coal boiler units of the CHP. The advantages of liquefied petroleum gas compared to heavy fuel oil are shown and a comparative economic assessment of their use is given. It is shown that interchangeability with natural gas is ensured by mixing the vaporized liquefied petroleum gas with air to form a homogeneous mixture — synthetic natural gas, which can be directly used in burners as a direct substitute for natural gas without changes in the composition of the equipment and in the design of the boiler burners. The calculation is presented of the permissible limits of the air fraction for liquefied petroleum gas of different composition according to the criterion of the Wobbe Index correspondence of synthetic natural gas and natural gas. Technical solutions are proposed for the use of liquefied petroleum gas as a reserve and alternative fuel at coal-fired combined heat and power plants in the event of damage of gas supply networks, which provide reliable and economical feeding of a coal-fired boiler unit with synthetic natural gas in such fundamentally different modes as coal jet “lighting” with low consumption and pressure of synthetic natural gas and ignition or emergency operation at a load of 25 % with high consumption and increased synthetic natural gas pressure, with the possibility of switching from natural gas to liquefied petroleum gas and vice versa. Bibl. 17, Fig. 3, Tab. 5.

Methane losses from different biogas plant technologies

Biogas and biomethane production can play an important role in a fossil-fuel-free energy supply, provided that process-related methane (CH4) losses are minimized. Addressing the lack of representative emission data, this study aims to provide component specific CH4 emission factors (EFs) for various biogas plant technologies, enabling more accurate emission estimates for the biogas sector and supporting the identification of low emission technologies. Four measurement teams investigated 33 biogas plants in Austria, Germany, Sweden and Switzerland including mainly agricultural and biowaste treating facilities. For the first time, a harmonized measurement procedure was used to systematically survey individual on-site emission sources and leakages. Measurements revealed a large variability in technology specific emissions, especially for biogas utilization and upgrading. Median loss from combined heat and power (CHP) plants was 1.6 % for gas engines (n = 21), and 3.0 % for pilot injection units (n = 3) of the input CH4. Biogas upgrading units showed median CH4 slips of < 0.1 % (chemical scrubbers, n = 4), 0.1 % (after exhaust gas treatment, n = 3) and 2.9 % (water scrubbers, n = 2). Not-gastight digestate storage (n = 8) was identified as a major emission source with maximum 5.6 % of the produced CH4 emitted. Individual leakages (n = 37) released between 0.0 and 2.1 % (median 0.1 %) relative to the CH4 production. All measurement and secondary data are provided in a harmonized dataset (294 datapoints). A review of IPCC default EFs indicate an underestimation of emissions from biogas utilization (reported in the energy sector) while the impact of leakages on overall plant emissions (waste sector) may be overestimated for European biogas plants.