scholarly journals Reduction of Cold-Start Emissions for a Micro Combined Heat and Power Plant

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1862
Author(s):  
Tammo Zobel ◽  
Christian Schürch ◽  
Konstantinos Boulouchos ◽  
Christopher Onder

Decentralized power generation by combined heat and power plants becomes increasingly popular as a measure to advance the energy transition. In this context, a substantial advantage of small combined heat and power plants is based on the relatively low pollutant emissions. However, a large proportion of the pollutant emissions is produced during a cold-start. This fact is not reflected in governmental and institutional emission guidelines, as these strongly focus on the emission levels under steady-state conditions. This study analyzes the spark advance, the reference air/fuel ratio and an electrically heated catalyst in terms of their potential to reduce the cold-start emissions of a micro combined heat and power plant which uses a natural gas fueled reciprocating internal combustion engine as prime mover and a three-way catalytic converter as aftertreatment system. Based on these measures, control approaches were developed that account for the specific operating conditions of the class of small combined heat and power plants, e.g., full-load operation and flexible, demand-driven runtimes. The experimental data demonstrates that even solutions with marginal adaptation/integration effort can reduce cold-start emissions to a great extent.

2021 ◽  
Vol 25 (2) ◽  
pp. 207-219
Author(s):  
A. D. Mekhryakov ◽  
A. N. Kudryashov ◽  
T. V. Koval

The study aims to improve the efficiency of waste utilisation from the coal-fired power industry based on an analysis of the dry-ash output unit operating at the Novo-Irkutsk Combined Heat and Power Plant, JSC “Irkutskenergo”. The unit was tested under various operating conditions of steam generating blocks following the standard methods adopted at the enterprise. The tests showed that the station steam generating block No. 3 (with a steam load of 409.2 t/h and an electrostatic precipitator efficiency of 90.46%) provided an ash supply efficiency of 7.10 t/h. When the ash is supplied from the steam generating block No. 4, operating at a steam load of 421.8 t/h and an electrostatic precipitator efficiency of 94.72%, the ash supply efficiency amounts to 9.19 t/h. Under the simultaneous operation of the steam generating blocks No. 3 and 4 at a steam load of 397.6 and 380.7 t/h, respectively, and an electrostatic precipitator efficiency of 90.46 and 94.72%, respectively, the unit efficiency was 14.23 t/h. As a result, limitations in the unit operation were identified. Thus, the airspeed in the pneumatic ash pipeline during ash transporting was 8.0-8.5 m/s, which facilitated the operation of the dry-ash output unit in a pulsed cycle. It was, therefore, recommended to increase the airspeed by accelerating the flow rate through the jet pump or by using a smaller diameter pipe. The conducted analysis showed that the efficiency of the dry-ash output unit depends mainly on the steam capacity of steam generating blocks, as well as on the flue gas cleaning efficiency in the steam generator electrostatic precipitators. The obtained results were used to determine the technical state, efficiency and reliability of the dry-ash output unit of the Novo-Irkutsk Combined Heat and Power Plant.


2020 ◽  
Vol 12 (8) ◽  
pp. 3330
Author(s):  
Guido Marseglia ◽  
Blanca Fernandez Vasquez-Pena ◽  
Carlo Maria Medaglia ◽  
Ricardo Chacartegui

The Sustainable Development Goals 2030 Agenda of United Nations raises the need of clean and affordable energy. In the pathway for more efficient and environmentally friendly solutions, new alternative power technologies and energy sources are developed. Among these, the use of syngas fuels for electricity generation can be a viable alternative in areas with high biomass or coal availability. This paper presents the energy, environmental and economic analyses of a modern combined cycle plant with the aim to evaluate the potential for a combined power plant running with alternative fuels. The goal is to identify the optimal design in terms of operating conditions and its environmental impact. Two possible configurations are investigated in the power plant presented: with the possibility to export or not export steam. An economic analysis is proposed to assess the plant feasibility. The effect of the different components in its performance is assessed. The impact of using four different syngases as fuel is evaluated and compared with the natural gas fuelled power cycle. The results show that a better efficiency is obtained for the syngas 1 (up to 54%), in respect to the others. Concerning pollutant emissions, the syngas with a GHG impact and lower carbon dioxide (CO2) percentage is syngas 2.


Author(s):  
G. Hariharan ◽  
B. Kosanovic

The ability of modern power plant data acquisition systems to provide a continuous real-time data feed can be exploited to carry out interesting research studies. In the first part of this study, real-time data from a power plant is used to carry out a comprehensive heat balance calculation. The calculation involves application of the first law of thermodynamics to each powerhouse component. Stoichiometric combustion principles are applied to calculate emissions from fossil fuel consuming components. Exergy analysis is carried out for all components by the combined application of the first and second laws of thermodynamics. In the second part of this study, techniques from the field of System Identification and Linear Programming are brought together in finding thermoeconomically optimum plant operating conditions one step ahead in time. This is done by first using autoregressive models to make short-term predictions of plant inputs and outputs. Then, parameter estimation using recursive least squares is used to determine the relations between the predicted inputs and outputs. The estimated parameters are used in setting up a linear programming problem which is solved using the simplex method. The end result is knowledge of thermoeconomically optimum plant inputs and outputs one step ahead in time.


2011 ◽  
Vol 347-353 ◽  
pp. 631-634
Author(s):  
Qin Liang Tan ◽  
Cai Juan Zhang ◽  
Xiao Ying Hu ◽  
Li Gang Wang ◽  
Qiang Lu ◽  
...  

Biomass direct combustion power generation is the most simple but effective way in dealing with environmental issues and energy crisis. A comprehensive diagnosis with accurate evaluation of energy saving potential of a given biomass power plant is of great importance in lowing the cost of generating electricity, reducing the consumption of energy and pollutant emissions [1]. This paper throws light upon an innovative energy consumption diagnosis method-the specific consumption analysis theory, which is based on the First and Second law of thermodynamics [2,3]. Taking a given biomass power plant of National Energy Group as an example, mathematical models are made based on all the components and processes. The specific consumption analysis theory is employed to calculate the specific consumption within the biomass power plant using design parameters under design operating conditions, thus demonstrating the specific consumption distribution in the power plant, which provides theoretical basis for energy-saving and optimization in biomass power plant.


2021 ◽  
pp. 1-11
Author(s):  
Dominik Appel ◽  
Fabian P. Hagen ◽  
Uwe Wagner ◽  
Thomas Koch ◽  
Henning Bockhorn ◽  
...  

Abstract To comply with future emission regulations for internal combustion engines, system-related cold-start conditions in short-distance traffic constitute a particular challenge. Under these conditions, pollutant emissions are seriously increased due to internal engine effects and unfavorable operating conditions of the exhaust aftertreatment systems. As a secondary effect, the composition of the exhaust gases has a considerable influence on the deposition of aerosols via different deposition mechanisms and on fouling processes of exhaust gas-carrying components. Also, the performance of exhaust gas aftertreatment systems may be affected disadvantageously. In this study, the exhaust gas and deposit composition of a turbocharged three-cylinder gasoline engine is examined in-situ upstream of the catalytic converter at ambient and engine starting temperatures of -22 °C to 23 °C using a Fourier-transform infrared spectrometer and a particle spectrometer. For the cold start investigation, a modern gasoline engine with series engine periphery is used. In particular, the investigation of the behavior of deposits in the exhaust system of gasoline engines during cold start under dynamic driving conditions represents an extraordinary challenge due to an average lower soot concentration in the exhaust gas compared to diesel engines and so far, has not been examined in this form. A novel sampling method allows ex-situ analysis of formed deposits during a single driving cycle. Both, particle number concentration and the deposition rate are higher in the testing procedure of Real Driving Emissions (RDE) than in the inner-city part of the Worldwide harmonized Light vehicles Test Cycle (WLTC). In addition, reduced ambient temperatures increase the amount of deposits, which consist predominantly of soot and to a minor fraction of volatile compounds. Although the primary particle size distributions of the deposited soot particles do not change when boundary conditions change, the degree of graphitization within the particles increases with increasing exhaust gas temperature.


Author(s):  
Erik Rosado Tamariz ◽  
Norberto Pe´rez Rodri´guez ◽  
Rafael Garci´a Illescas

In order to evaluate the performance of new turbo gas power plants for putting in commercial operation, it was necessary to supervise, test and, if so the case, to approve the works of commissioning, operational and acceptance of all equipments and systems that constitute the power plant. All this was done with the aim of guaranteeing the satisfactory operation of these elements to accomplish the function for which they were developed. These activities were conducted at the request of the customer to confirm and observe that the evidence of the tests was carried out according to the specifications and international regulations. The putting into commercial operation activities were done in collaboration with the supplier and manufacturer of equipment, the client and the institution responsible for certification and approval of the plant. All this in a logical and chronological order for the sequence of commissioning tests, operation and acceptance. Commissioning tests were carried out on-site at normal operating conditions, according to the design and operation needs of each power plant of a group of 14. Once the commissioning tests were completely executed and in a satisfactory manner, operational tests of the plants were developed. This was done by considering that they must operate reliable, stable, safe and automatically, satisfying at least, one hundred hours of continuous operation at full load. After evaluating the operational capacity of the machine, it was necessary to determinate the quality of the plant by carrying out a performance test. Finally, it was verified if every unit fulfills the technical requirements established in terms of heat capacity of the machine, noise levels and emissions. As a result of this process, it is guaranteed to the customer that the turbo gas power plants, their systems and equipments, satisfy the requirements, specifications and conditions in agreement with the supplier and manufacturers referring to the putting into commercial operation of the plant.


Author(s):  
Dennis Toebben ◽  
Tobias Burgard ◽  
Sebastian Berg ◽  
Manfred Wirsum ◽  
Liu Pei ◽  
...  

Abstract Combined cycle power plants (CCPP) have many advantages compared to other fossil power plants: high efficiency, flexible operation, compact design, high potential for combined heat and power (CHP) applications and fewer emissions. However, fuel costs are relatively high compared to coal. Nevertheless, major qualities such as high operation flexibility and low emissions distinctly increase in relevance in the future, due to rising power generation from renewable energy sources. An accelerated start-up procedure of CCPPs increases the flexibility and reduces the NOx-emissions, which are relatively high in gas turbine low load operation. Such low load operation is required during a cold start of a CCPP in order to heat up the steam turbine. Thus, a warm-keeping of the thermal-limiting steam turbine results in an accelerated start-up times as well as reduced NOx-emissions and lifetime consumption. This paper presents a theoretical analysis of the potential of steam turbine warm-keeping by means of hot air for a typical CCPP, located in China. In this method, the hot air passes through the steam turbine while the power plant is shut off which enables hot start conditions at any time. In order to investigate an improved start-up procedure, a physical based simplified model of the water-steam cycle is developed on the basis of an operation data set. This model is used to simulate an improved power plant start-up, in which the steam turbine remains hot after at least 120 hours outage. The results show a start-up time reduction of approximately two-thirds in comparison to a conventional cold start. Furthermore, the potential of steam turbine warm-keeping is discussed with regards to the power output, NOx-emissions, start-up costs and lifetime consumption.


Author(s):  
Cesar Celis ◽  
Sergio Peralta ◽  
Walter Galarza

Abstract The influence of different power augmentation techniques used in gas turbines on the performance of simple cycle type power plants is assessed in this work. A computational model and tool realistically describing the performance of a typical simple cycle type power plant at design and off-design point conditions is initially developed. This tool is complemented with different models of power augmentation technologies. Finally, the whole model including both power plant and power augmentation techniques is used to analyze a case study involving a particular power plant in Peru. The results from the simulations of the specific power plant indicate that power output can be increased through all the evaluated power augmentation technologies. These results show indeed that technologies based on absorption refrigeration systems produce the largest gains in terms of power output (7.1%) and thermal efficiency (0.7%). Such results confirm the suitability of these systems for simple cycle type power plant configurations operating under hot and humid operating conditions as those accounted for here. From an economic perspective, considering the net present value as the key parameter defining the feasibility of a project in this category, power augmentation techniques based on absorption cooling systems result also the most suitable ones for the studied power plant. Power augmentation techniques environmental implications are also quantified in terms of CO2 emissions.


Author(s):  
Anastasios N. Karkanis ◽  
Pantelis N. Botsaris ◽  
Panagiotis D. Sparis

This paper presents and discusses experimental data obtained during test simulating the test cycle ECE-15 for a relatively simple method for the reduction of pollutant emissions during a cold start. During a cold start the volume of the exhaust gases is considerably smaller than the ones under full load. Therefore, only a small portion of the catalyst active surface is used to process the gases at the cold start phase. After the light-off at the initial surface the exhaust gases pass from the total catalytic surface which is already pre-heated from the first phase. The experimental results presented here indicate that there is a reduction of the pollutant emissions during the cold start of an engine. The developed system uses the 20% of the catalyst active surface during start-up and the rest of the catalyst surface after this phase, controlled by a proper automation system. At the cold start phase the system focusing the gas flow towards the center core of the monolith, so there is a quicker warm-up of the catalyst and a faster initiation of catalysis in this area. So when the remaining ceramic body of the catalytic converter is used, it is already warmed and the catalysis starts almost immediately.


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