Heat Recovery Boiler Research Articles

Evaluation and analysis of exergoeconomic performance for the calcination process of green petroleum coke in vertical shaft kiln

The main objective of this paper is to establish a mathematical framework to analyze the complex thermal economic performance of the calcination process. To find the factors affecting exergy efficiency loss, different exergy destruction is investigated in detail. Furthermore, the exergy flow cost model for exergy cost saving has also been developed. The results show that the vertical shaft furnace is a self-sufficiency equipment without additional fuel required, but the overall exergy destruction accounts for 54.11% of the total exergy input. In addition, the energy efficiency of the waste heat recovery boiler and thermal deaerator are 83.52% and 96.40%, whereas the exergy efficiency of the two equipment are 65.98% and 94.27%. Furthermore, the import exergy flow cost of vertical shaft furnace, waste heat recovery boiler and thermal deaerator are 366.5197 RMB per MJ, 0.1426 RMB per MJ, and 0.0020 RMB per MJ, respectively. Based on the result, several suggestions were proposed to improve the exergoeconomic performance. Assessing the performance of suggested improvements, the total exergy destruction of vertical shaft furnace is reduced to 134.34 GJ per hours and the exergy efficiency of waste heat recovery boiler is raised up to 66.02%. Moreover, the import exergy flow cost of the three different equipment is reduced to 0.0329 RMB per MJ, 0.1304 RMB per MJ, and 0.0002 RMB per MJ, respectively.

Визначення причин, попередження і усунення нестійких режимів газотурбокомпресорів суднових дизелів

Annotation – With commissioning of the “Socofl Star” ship’s series, negative occurrences relative to surging of the Main Engine (ME) «Hanshin Diesel» 6LF46 turbochargers (TC) VTR 401-2. To elimination of a surging, it was necessary reduce loading of ME to the safe level. This action caused the ship’s speed to fall from 11 – 10 to 4 knots which resulted in worsening of the ship’s maneuverability characteristics and lead to the failure to provide the ship’s service speed stipulated in the contractual arrangements. Existence of this problem instigated the shipowner to charge us as experts with the mission of carrying out appropriate investigations and working out recommendations as to how to prevent and eliminate surging of TC. This task was solved on the m/v “Socofl Star”. Based on results the ME shop test and trial test of the vessel and also the saved-up data of work of ME in various conditions of swimming, the analysis of the causes of a surge of the TC was made. It is established that small values of safety factor of stability of the compressor of TC on a surging – KCT which are not allowing to ensure effective functioning of TC on the main modes of loading of ME are its reason. For increase in area of steady work of TC it is necessary to reduce the hydraulic resistance of components of the Air-Gas Path (AGP) of the ME which can be realized by changes in a design of units of air supply and gas exchange or reduction of productivity and extent of increase in pressure of air in the compressor of TC. Under operating conditions vessels an optimal solution an objective is removal of a part of blowing-off air after compressor of the TC. The air can be discharged into the flue gas header after the waste heat recovery boiler or directly into the atmosphere. This allowed the shipowner not to make constructive changes to the components of the AGP of ME and TC. The description of the operated unloading device controlled remotely on removal of air which ensures effective functioning of TC and ME that is confirmed by results of natural tests and the subsequent operating experience of vessels of the “Socofl Star” series is provided.

Thermodynamic analysis of a combined gas-steam cycle without and with afterburner

Currently in power plants what is sought are higher thermal efficiencies, which is why combined cycle plants have been chosen, since they make better use of fuel, producing greater net power, all this It has led to innovative modifications to combined cycle power plants, improving their performance. In this article the thermodynamic analysis of a combined cycle (Gas-Steam) without and with Afterburner is carried out, in said analysis adequate thermodynamic indices have been used and the calculations have been carried out taking into account the state of the art for gas turbines and the typical values for steam cycle quantities. The purpose of this study is to analyze the combined plants where the exhaust gas at the outlet of the gas turbine is used in a waste heat recovery boiler to produce steam that is expanded in a turbine and discharged in a condenser. Since the air-fuel ratio in the combustion chamber of a gas turbine is higher than the stoichiometric, fuel can be added in the boiler (Afterburner) to increase steam production or to improve the quality of the steam produced.

Enhancement of pool boiling performance using MWCNT based nanofluids: A sustainable method for the wastewater and incinerator heat recovery

Recovery of the wastewater heat and incinerator heat is an important stage of the design and optimization of the industrial thermal management system. Recovery and reuse of wastewater heat are also important for energy sustainability. Heat recovery boilers are mostly used in the industry for heat recovery. The performance of the heat recovery boilers is mainly depending on the Critical heat flux value of the cooling fluid. Various studies have suggested that the nanofluids are a better working fluid than conventional cooling fluids like water and ethylene glycol. Thus, in this study, we used MWCNT based nanofluids as a cooling fluid and compared its performance with the water. Because water is the conventional cooling fluid used in wastewater heat recovery. We have reported the bubble dynamics data, including the departure diameter, departure frequency, bubble growth time and bubble wait time. These results revealed that the incorporation of the MWCNT based nanofluids leads to the surface modification of the heater surface and the enhancement of critical heat flux.It was observed that by using a 0.005 vol% of MW-CNT in water, critical heat flux can be enhanced to 2.14 W/m2. This recorded critical heat flux enhancement is 62.12% more than the critical heat flux required for the water. At 0.005 vol% of MWCNT concentration, the heat-transfer coefficient is enhanced by 30%. The enhancement in the CHF is due to the enhanced surface wettability of the heating surface by a nanofluid. Furthermore, there is the deposition of the nanoparticles on the surface of the heater which causes CHF to enhance. This deposition also useful for critical heat flux enhancement.

Analysing the efficiency of thermopressor application in the charge air cooling system of combustion engine

As the analysis of the research results has shown, the use of a thermopressor makes it possible to increase the fuel and energy efficiency of a ship power plant in a wide range of the operation parameters. It can be achieved by cooling the charge air before the engine inlet receiver and by reducing the compression work of the turbocharger. A scheme with the thermopressor application in the cooling system of a low-speed main engine and in the system for utilizing the exhaust gases heat in a heat recovery boiler of one and two pressures was proposed. The use of thermopressors led to a decrease in the compressor power consumption, and therefore in the turbine required power. Therefore, it was appropriate to pass (bypass) the excess amount of gas past the turbine. Accordingly, the thermal potential of exhaust gases was increased. As a result, the temperature of gases at the inlet to the heat recovery boiler was increased by 10-15 °C, and gases heat was increased by 10-15% respectively. The obtained additional steam is advisable to use for driving the utilization turbine generator, thereby reducing the load on the ship's power plant, with a corresponding decrease in fuel consumption of diesel generators by 2-4%.

Waste Heat Utilization for the Energy Requirements of a Post Combustion CO <sub>2</sub> Capture Retrofit Study of a Cement Manufacturing Facility

This paper presents a preliminary investigation of utilizing waste heat available from a cement manufacturing facility for carbon dioxide (CO2) capture and compression processes. The cement manufacturing facility considered in this study emits 600,000 - 750,000 tonnes of CO2 annually while producing 800,000 – 1,000,000 tonnes of clinker. Determining an alternative energy source for amine regeneration will be a major deliverable and a challenging component of this study. Previously utilized methods from the power industry do not apply in this situation since cement plants do not normally produce steam. Cement manufacturing is an energy intensive process resulting in multiple high temperature exhaust gas streams. In this study, preliminary thermodynamic investigations of the utilization of thermal energy have been performed in two gas streams including kiln flue gas and clinker cooler air exhaust. The scenarios investigated in this study include (1) direct recovery of heat using heat recovery boilers and (2) employing of duct firing to increase the temperature of the flue gas prior to heat recovery. The recovered energy can be used for the amine regeneration process. The use of duct burning subsequently produced excess heat which exceeded the energy need for amine regeneration. However, this option can be utilized to produce medium pressure steam which can then be paired with the installation of a back pressure turbine to produce electricity. The results obtained in this study focused solely on the thermodynamic feasibility and efficiency. To justify whether the proposed strategies are practical or not, several factors including CAPEX and OPEX, requirements for modifications to the existing plant, impacts on the existing cement kiln process, and complexity and reliability of the proposed heat recovery system need to be further considered.

Prospects for the use of steam-piston engines to increase the economic attractiveness of environmentally friendly processes for the processing of copper-molybdenum concentrates of promising deposits in Kazakhstan

The use of old metallurgical processes is accompanied by releasing process gas into the atmosphere because its subsequent processing is not possible. New technological processes using oxygen flash smelter make it possible to obtain a sufficient concentration of sulfur oxide in process gases for sulfuric acid commercial production. A necessary element of the new type of power plants is heat recovery boilers that generate steam that can be used to generate electricity, which will increase the economic efficiency of oxygen flash smelter plants. The article shows that it is practically impossible to use steam turbines to generate electricity from this steam, and the use of steam-piston engines is proposed.

The Main Directions for Improving the Efficiency of the Power Equipment of a CHPP

The article discusses matters concerned with rational use and improvement of the thermal efficiency of operating combined heat and power plants (CHPPs) that form a power and heat generation system under real operating conditions. Factors influencing the CHPP performance indicators, including design solutions, the extent of equipment wear in the course of operation, which is connected with deviations of operating modes from their design parameters, etc. are analyzed. It is shown that decreasing the electricity production by T and PT turbines operating in the condensing cycle, increasing the supply of heat from the uncontrolled extractions of high-efficient condensing turbines, and modernization of the equipment and thermal cycle circuits are an important reserve for improving the thermal efficiency of the operating CHPPs. The specific generation of electricity by CHPPs operating in the cogeneration mode is compared for CHPPs equipped with T-250/300-23.5, T-185-12.8, T-100/110-12.8, and T-175/210-12.8 cogeneration turbines and for various solutions on applying gas turbine units (GTUs) at gas-fired CHPPs, including those containing hot-water boilers heated by exhaust gases, including the version of the fully variable combined cycle plant (CCP) for a capacity of 20–25 MW developed at the All-Russia Thermal Engineering Institute. Modern thermal cycle circuits and calculation methods used in designing the modernized flow paths of CHPP steam turbines are presented. The necessity of applying a systems approach in elaborating the requirements for modernizing particular CHPPs by optimizing the structure of generating capacities is pointed out. Recommendations on improving R and TR turbines (with cogeneration back pressure) and uncontrolled steam extractions from large-capacity condensing turbines are formulated with due regard to the systems approach. The article points out the advantages of electricity generation in the CCP condensing cycle, the effectiveness of domestically produced power-generating GTUs with the electrical capacity equal to 16 or 25 MW equipped with heat-recovery hot water boilers or CCPs equipped with these turbines (provided that gas fuel is available for newly constructed capacities), and also limited scales in which the commissioning of cogeneration CCPs is advisable in areas containing large heat loads.

Optimization of Thermal Conditions of Heat Recovery Boilers with Regenerative Heating in the High-Temperature Section of Isoamylene Dehydrogenation

Improving the efficiency of use of energy resources at large-capacity energy-consuming enterprises in the petrochemical industry in conditions of high internal and external competition is the priority for the development of the fuel and energy industry. This is confirmed by various legislative acts, including the energy strategy of the Russian Federation for the period up to 2035. This research focuses on a high-temperature section of dehydrogenation of isoamylenes into isoprene, the production of which relates (isoprene production relates to large petrochemical enterprises that consume a huge amount of energy resources) to large-capacity energy-consuming industries. To increase the thermodynamic efficiency of the research object, regenerative feedwater heating for heat recovery boilers is proposed due to deeper cooling of fuel and contact gas (the term "contact gas" is used in the technological regulations of an isoprene production company), which are secondary thermal energy resources in this technology. In accordance with the industry’s technology regulations, a block diagram of the initial and improved high-temperature section with the indication of material flows (The term "material flow" refers to the type of substances that are used in the high-temperature dehydrogenation stage of isoamylenes) was developed. The balance equations of the section under consideration are provided, and the thermal efficiency and exergy efficiency for systems utilizing fuel and contact gas are determined. The estimated economic effect was determined in physical terms; it was found to be 2008.58 toe/h. An exergy flow diagram is also provided to show how the system utilizes contact gas.

A comprehensive design, optimization and development methodology of a wasted heat recovery boiler using serrated fins and extensive surface in a bulky CCPP

This paper describes the requirements and the difficulty encountered in preparing the data for the consumption calculations of a waste heat recovery boiler (WHRB). The study is performed based on continuous monitoring of the operating data by considering the extensive thermal surfaces and a large number of small-serrated fins. The recovery boiler efficiency improved using optimization of temperature profile by better surface arrangement. Then, the suggested designed waste heat recovery boiler is accessible and conducted in a real combined cycle power plant (CCPP). The CCPP optimization is performed based on the new WHRB with and without optimal saturation temperature, and the recovery boiler optimal temperature is obtained based on the objective function. The founded values of the CCPP at different temperatures are verified and compared to the regular operation. The important findings include four categories. First, the gas temperature of the recovery boiler will decrease slightly while the efficiency will increase by increasing the load changes. Second, the dependency of the decision parameters of the CCPP to the ambient temperature is effectively high, and any changes in the efficiency depending on the ambient temperature. Third, the exergy efficiency increment without affecting the total exergy can be performed by using the low-pressure saturation temperature as a decision-making parameter. Forth, 17.9% improvement in the entire cycle efficiency and a 2.14% increase in WHRB exergy are observed after incrementing the cost by 14.48%.

CCP maneuverability increasing algorithm realized on DCS with the metal allowable thermo-stressed state provision

Power generating companies’ main task today is to obtain the highest possible profit. To accomplish this task, it is necessary to have maneuverable equipment that able to reach the maximum power value in minimal time and maintain metal acceptable working conditions. Metal high thermo-stressed state can lead to premature ageing and emergency situations that require investment in overhaul or replacement of units. The authors describe the method of increasing maneuverability of combined-cycle power plant. The main considered input parameter is thermo-stressed state of ‘critical’ elements of waste heat recovery boiler and steam turbine. Based on calculated thermo-stressed values, the algorithm informs the operator of the most optimal steam turbine loading speed. The algorithm does not require any outside software and is performed in the distributed control system installed at the power plant. Also, the authors present the power plant start-up trends with thermo-stressed state calculated values to show the stress reserve, which should be reduced, thus making the start-up faster and increasing the economic performance of the power unit.

Economic Efficiency Assessment of Using Wood Waste in Cogeneration Plants with Multi-Stage Gasification

The aim of this work is to assess the effectiveness of biomass gasification power plants in Russia (Irkutsk region) and compare them with other types of electricity and heat cogeneration systems. Biomass, which is waste from logging and wood processing, is considered as fuel for gasification plants. As a criterion, the cost of energy is used. Analytical relations are obtained for the cost of electric energy at a given cost of thermal energy and vice versa, thermal energy at a given cost of electric energy. These relationships are applied to assess the economic efficiency and compare small-power plants (up to 200–500 kW) such as mini-combined heat and power (CHP) on fuel chips and fuel pellets, coal-fired CHP and gas and liquid fuel power plants (gas-piston and diesel power plants). The latter are equipped with heat recovery boilers and supply consumers with heat and the electric power simultaneously. The calculation results show that the cost of electricity when using wood fuel is significantly less than the cost of electricity from a diesel power plant due to the use of cheaper fuel. In this regard, for autonomous energy systems of small power, especially near logging points, energy supply from biomass gasification power plants is a preferable solution than the use of diesel power plants. Wood fired energy cogeneration systems (mini-CHP) can also successfully compete with coal and gas power plants if they have cheap wood fuel at their location. With the introduction of carbon dioxide emissions charges, the use of not only wood chips, but also pellets becomes competitive in comparison with coal and gas.

Economic assessment of the use of double-acting resuperheating of water vapor at the PGU-420 Cherepovets state district power station

To increase the efficiency of a three-circuit combined-cycle plant, it is proposed to perform double resuperheating of water vapor in the high pressure loop (intermediate superheater ISH-1) and in the cooler part of the heat recovery boiler (intermediate superheater ISH-2). It was found by calculation that the implementation of the double reheated steam at high pressure and the tail of the WHRB increases the electrical efficiency of PGU-420 by 0.92 % compared to the option of a single resuperheat (from 60.45 to 61.37 %). The capacity of PGU-420 increases by 3.7 % (from 422.94 to 438.61 MWt). The specific reference fuel consumption is reduced by 1.5 % (from 203.47 to 200.42 g/(kWfh)). The steam dryness factor increases by 6.03 % (from 93.2 to 99.23 %). The steam turbine efficiency increases by 1.15 % (from 36.26 to 37.41 %), and steam turbine power increases by 11.61 % (from 134.94 to 150.61 MWt). The economic effect of the implementation of the second water vapor resuperheating in monetary terms is 48.0 million rubles per year when the cost of fuel equivalent is 3700 rubles/t. f e. and at the operating time of 7500 h/year.

물 분사 폐열회수 보일러의 설계 사양을 구하는 열역학적 해석법

본 논문은 시스템 내부만을 순환하는 작동 유체를 갖는 물 분사 폐열회수 보일러에 대한 체인 블록(chain block) 열역학 해석법과 그 활용법을 소개한 것이다. 작동 조건 및 필요한 설계 정보에 따라 시스템을 여러 부분(block)으로 나눈다. 각 블록은 독립적인 질량/에너지 보존식을 가지며, 선행 블록의 출구 조건이 다음 블록의 입구 조건이 되도록 연결한 체인 블록 해석법을 이용하면 각 부품의 설계 사양, 운전 상태 및 시스템 성능이 쉽게 얻어진다. 물 분사 폐열회수 보일러의 성능은 95%까지도 얻을 수 있으며, 또 화염 온도는 기본 보일러에 비해 약 100~150°C 정도 감소하여 NOSUBx/SUB 저감에 유리하다.

Analysis of a biogas-fed SOFC CHP system based on multi-scale hierarchical modeling

Biogas is an abundant renewable energy source which can be produced by anaerobic treatment of biological waste such as sewage sludge, agro-industrial waste, and industrial animal waste. The utilization of biogas instead of fossil fuels in a solid oxide fuel cell (SOFC)-based system is a promising choice to achieve a fossil-free and sustainable energy future. A biogas-fed decentralized SOFC combined heat and power (CHP) system model is proposed and analyzed. The system consists of a pre-reformer, an SOFC stack, an afterburner and a heat-recovery boiler. The system model integrates a multi-scale hierarchical three-dimensional SOFC stack model with zero-dimensional balance of power component models, which enables simultaneous investigations of both the overall system performance and the stack-internal distributed properties down to the electrode scale. The effects of steam/carbon ratio, biogas composition and operation voltage of the SOFC stack on the electrical and CHP efficiencies of the system, as well as the temperature gradient within the SOFC stack were studied. The proposed system model is demonstrated as an insightful and powerful tool for designing hybrid SOFC combined heat and power systems.

Heat recovery boilers with water spray: Part Ⅱ: Parametric analysis and optimization of design specifications

The authors recently proposed a heat recovery boiler with water spray (HR-B/WS), where water was sprayed onto the inlet airstream and/or reaction zone. We also introduced a chain-block structure analysis method to determine thermal efficiency and provide information regarding capacity design specifications for each system component (see Part Ⅰ of the paper). Although we showed that HR-B/WSs produced excellent thermal efficiency and NOX emission, principal parameter effects on system performances and optimized operating conditions were not sufficiently well determined to allow effective system control and design. Therefore, the present study performed parametric analyses for each parameter’s performance to derive design specifications for the HR-B/WS system components. This information is essential to design laboratory and pilot scale research systems to confirm industrial boiler (under development) performances.

ЗАЩИТА ОТ КОРРОЗИИ ТЕХНОЛОГИЧЕСКОГО ОБОРУДОВАНИЯ НЕФТЕПЕРЕРАБАТЫВАЮЩЕГО ПРЕДПРИЯТИЯ

A method for slowing down the corrosion of heat exchangers in the T-104 and T102 heat recovery boiler blocks is considered. PK-1 Aminate was selected as the most suitable inhibitor for process heat exchangers of the waste heat recovery boiler unit

Design of organic Rankine cycle power systems for maritime applications accounting for engine backpressure effects

The installation of an organic Rankine cycle unit on the exhaust line of a marine engine imposes an increase in the backpressure on the engine, resulting in a decrease of the engine performance and a variation of the available waste heat. In this paper, a method is presented for the optimal design of organic Rankine cycle power systems for waste heat recovery in marine applications. The method is based on the use of performance maps for the engine and numerical models for the organic Rankine cycle unit and the waste heat recovery boiler, thereby enabling consideration of the effect of the increased backpressure on the performance of both the main engine and the organic Rankine cycle unit. The method is evaluated on a hypothetical containership fuelled by liquefied natural gas. The results of the study indicate that the overall system fuel consumption can be reduced by 0.52 g/kWh to 1.45 g/kWh by allowing higher backpressure levels on the engine. In addition, the results of the study indicate that for a fixed power output of the organic Rankine cycle unit, a reduction of the space requirement for the waste heat recovery boiler by up to 35% can be attained when increasing the maximum allowed engine backpressure from 3 kPa to 6 kPa.

기존 가정용 보일러 및 신형 물분사 폐열회수 보일러에 대한 수소 연료의 평가

기존 가정용 보일러 및 신형 물분사 폐열회수 보일러에 대한 수소 연료의 평가

Heat recovery boilers with water spray. Part I: Thermodynamic analysis validation and boiler practicality

This study develops a thermodynamic analysis method to determine thermal efficiency and provide information regarding capacity design specification for each system component. A chain-block structure analysis method is introduced for heat recovery boilers with water-spray (HR-B/WS), where water is sprayed onto the inlet air stream and/or reaction zone. We subsequently validated the proposed analysis method and investigated the boiler system practically. HR-B/WSs are expected to achieve up to 95% efficiency with reduced NOX emission. Additional water spray onto the combustion chamber may be a useful mechanism to reduce NOX emission while retaining high efficiency when insufficient water is supplied to the heat exchanger.