Long-term tests of gas burners mounted on hobs and cookers powered by a mixture of natural gas and hydrogen

In accordance with the document of the Ministry of Industry and Trade – Hydrogen Strategy of the Czech Republic, it can be expected that in the coming years, pressure will be exerted to inject hydrogen into the gas infrastructure, which is currently used mainly for natural gas. Injection of hydrogen into natural gas can have an effect not only on the transport and distribution system, but also on the storage of this mixture in underground reservoirs in CR. This article aims to describe the issue of storing a mixture of hydrogen and natural gas in underground reservoirs. In particular, the effect on the storage capacity and on the overall integrity of the reservoir, problems with the embrittlement of the metal parts of the probes, the effect on the rubber seal. The paper therefore describes not only the effects on the storage of a mixture of hydrogen and natural gas, but also on the devices that are located on surface technologies. The results of studies from foreign literature demonstrate that the addition of 10-15% by volume of hydrogen to natural gas will have a minimal effect on the operation of the underground reservoir. The storage of a mixture of hydrogen and natural gas in the Czech Republic is currently a much-discussed topic, also regarding the experience with the storage of town gas (which contained a high proportion of hydrogen) in the Lobodice aquifer type underground gas storage.

Previously published studies have addressed modifications to the engines when operating with biogas, i.e. a low heating value (LHV) fuel. This study focuses on mapping out the possible biogas share in a fuel mixture of biogas and natural gas in micro combined heat and power (CHP) installations without any engine modifications. This contributes to a reduction in CO2 emissions from existing CHP installations and makes it possible to avoid a costly upgrade of biogas to the natural gas quality as well as engine modifications. Moreover, this approach allows the use of natural gas as a “fallback” solution in the case of eventual variations of the biogas composition and or shortage of biogas, providing improved availability. In this study, the performance of a commercial 100kW micro gas turbine (MGT) is experimentally evaluated when fed by varying mixtures of natural gas and biogas. The MGT is equipped with additional instrumentation, and a gas mixing station is used to supply the demanded fuel mixtures from zero biogas to maximum possible level by diluting natural gas with CO2. A typical biogas composition with 0.6 CH4 and 0.4 CO2 (in mole fraction) was used as reference, and corresponding biogas content in the supplied mixtures was computed. The performance changes due to increased biogas share were studied and compared with the purely natural gas fired engine. This paper presents the test rig setup used for the experimental activities and reports results, demonstrating the impact of burning a mixture of biogas and natural gas on the performance of the MGT. Comparing with when only natural gas was fired in the engine, the electrical efficiency was almost unchanged and no significant changes in operating parameters were observed. It was also shown that burning a mixture of natural gas and biogas contributes to a significant reduction in CO2 emissions from the plant.

Using mixtures of hydrogen and natural gas as primary energy sources in current power generation systems with gas turbines is one of the worldwide trends for global decarbonization goals. However, despite the problems of adaptation of the existing assets for the use of hydrogen, little has been studied about its effects on gas turbine generation systems that operate in tropical climatic conditions where temperatures are higher than 30 °C, and relative humidity reaches values higher than 80%.The gas turbine generator plant with steam injection and cooled air inlet studied consisted of a General Electric LM5000 gas turbogenerator composed of a low-pressure compressor, high-pressure compressor, combustion chambers, turbine, and generator. The steam injection system comprises a heat recovery steam generator and two MUP pumps. The air-cooling system comprises two electric coolers, a cooling tower, two pumps, a cooling coil, two evaporators in series, and two condensers in parallel. The air-cooling system allows for reaching the minimum temperature of 8.8 °C. Plant with Stig cycle in ISO conditions (15°C and 60% RH) produces 52 MW with a thermal efficiency of 43%. The atmospheric conditions in the geographical location of the power plant are, on average, 32°C and 80% relative humidity at sea level. Therefore, the plant with the Stig cycle under local operating conditions produces a power of 44.4 MW with a thermal energy efficiency of 41.6 %. A simulation was conducted in a Stig cycle generation system with a gas turbine, steam injection in the combustion chamber, and cooling air at 8.8°C at the compressor inlet. The system is set to produce 44.4 MW for fuel mix ranges between 0–50% hydrogen. The study results showed that for every 5% by volume of hydrogen added to the H2-natural gas mixture, 5.6% kJ/m3 of energy is lost. Thermal efficiency decreases an average of 2.67% for every 10% increase in hydrogen, which forces an increase in the volume of the fuel mixture to generate the same power. For a percentage of 20% by volume of H2 in the fuel mixture, there are increases in global exergy destruction, avoidable exergy destruction, and unavoidable exergy destruction of 21.5%, 16%, and 31%, respectively. In comparison, the exergetic efficiency decreases by 13.7%. The component most affected by the use of the fuel mixture is the combustion chamber, in which exergy destruction increases by 17.8 MW compared to using 100% natural gas. In addition, the combustion chamber suffers an increase in exergy destruction of 29,2% for every 10% increase in the percentage of hydrogen injection in the fuel mixture. For every 10% increase in H2 volume, there is an average increase in the NOx concentration of 0.4% and a 5% decrease in the CO2 concentration.

Experimental evaluation and ANN modeling of a recuperative micro gas turbine burning mixtures of natural gas and biogas

Currently, the issue of creating decarbonized energy systems in various spheres of life is acute. Therefore, for gas turbine power systems including hybrid power plants with fuel cells, it is relevant to transfer the existing engines to pure hydrogen or mixtures of hydrogen with natural gas. However, significant problems arise associated with the possibility of the appearance of flashback zones and acoustic instability of combustion, an increase in the temperature of the walls of the flame tubes, and an increase in the emission of nitrogen oxides, in some cases. This work is devoted to improving the efficiency of gas turbine power systems by combusting pure hydrogen and mixtures of natural gas with hydrogen. The organization of working processes in the premixed combustion chamber and the combustion chamber with a sequential injection of ecological and energy steam for the “Aquarius” type power plant is considered. The conducted studies of the basic aerodynamic and energy parameters of a gas turbine combustor working on hydrogen-containing gases are based on solving the equations of conservation and transfer in a multicomponent reacting system. A four-stage chemical scheme for the burning of a mixture of natural gas and hydrogen was used, which allows for the rational parameters of environmentally friendly fuel burning devices to be calculated. The premixed combustion chamber can only be recommended for operations on mixtures of natural gas with hydrogen, with a hydrogen content not exceeding 20% (by volume). An increase in the content of hydrogen leads to the appearance of flashback zones and fuel combustion inside the channels of the swirlers. For the combustion chamber of the combined-cycle power plant “Vodoley”, when operating on pure hydrogen, the formation of flame flashback zones does not occur.

Dynamic Quality Tracking of Natural Gas and Hydrogen Mixture in a Portion of Natural Gas Grid

This article is devoted to the investigation of the characteristics of a low-emission gas turbine combustion chamber, which can be used in Floating Production, Storage and Offloading (FPSO) vessels and operates on a mixture of natural gas and hydrogen. A new approach is proposed for modelling the processes of burning out a mixture of natural gas with hydrogen under preliminary mixing conditions in gaseous fuel with an oxidizer in the channels of radial-axial swirlers of flame tubes. The proposed kinetic hydrocarbon combustion scheme is used in three-dimensional calculations for a cannular combustion chamber of a 25 MW gas turbine engine for two combustion models: the Finite-Rate/Eddy-Dissipation and the Eddy Dissipation Concept. It was found that, for the investigated combustion chamber, the range of stable operations, without the formation of a flashback zone in the channels of radial-axial swirlers, is determined by the hydrogen content in the mixture, which is less than 25-30% (by volume). For the operating modes of the chamber without the formation of a flashback zone inside the swirler channels, the emissions of nitrogen oxide NO and carbon monoxide CO do not exceed the values corresponding to modern environmental requirements for emissions of toxic components by gas turbine engines.

The results of theoretical study of operation of continuous furnaces heated by natural gas, renewable hydrogen, and their mixture are presented. The furnaces have the same design, but significantly different energy efficiencies due to different heat losses and capability of recuperative fume gas heat utilization system. The measures to reduce heat losses and to increase air temperature for fuel combustion can reduce specific fuel consumption for metal heating and carbon dioxide emissions by 25.8% for natural gas furnaces. For furnaces operating on mixture of natural gas and hydrogen, a greater reduction in carbon dioxide emissions is achieved in furnaces with worse energy efficiency, but with greater fuel consumption for metal heating. The paper shows the possibility of converting a furnace with better energy efficiency indicators to be heated by mixture of natural gas (75%) and hydrogen (25%). The measure reduces the natural gas consumption and carbon dioxide emissions to 9.2% due to the use of hydrogen with specific consumption 13.81 m3 per ton of metal. To ensure the same costs for metal heating when transferring continuous furnaces from natural gas to hydrogen, or their mixture, the ratio of prices for natural gas and hydrogen should not exceed 0.301-0.312.

Comparison of the solid oxide fuel cell system for micro CHP using natural gas with a system using a mixture of natural gas and hydrogen

Energetic and exergoeconomic evaluation of a stig cycle and cooled inlet air gas turbine powered by mixtures of natural gas and H2 in tropical climates

Engine characteristics of emissions and performance using mixtures of natural gas and hydrogen

This article focuses on the characteristics of a low-emission gas turbine combustion chamber that operates on a mixture of natural gas and hydrogen.In the current energy sector, reducing emissions of toxic substances like nitrogen oxides (NO) and carbon monoxide (CO) is a top priority.The article's key finding is that using hydrogen in fuel mixtures is a promising direction to ensure high efficiency of gas turbine plants while reducing the negative impact on the environment.The article proposes a new approach to modelling the combustion of a mixture of natural gas and hydrogen under conditions of preliminary mixing of gaseous fuel with an oxidant in the channels of radial-axial swirlers of flame tubes.To implement this approach, a detailed kinetic scheme of hydrocarbon combustion was used, which includes multi-stage chemical reactions typical of mixtures with a high hydrogen content.A three-dimensional numerical simulation of the operation of a tubular-ring combustion chamber of a 32 MW gas turbine engine was carried out using the Finite-Rate/Eddy-Dissipation combustion model.The results are clear: to ensure stable operation of the combustion chamber without the formation of flame slippage zones in the channels of radial-axis swirlers, the critical parameter is the hydrogen content in the mixture, which should not exceed 20-24% (by volume).The study definitively shows that under these conditions, the level of NO and CO emissions does not exceed the values that meet modern environmental standards.The proposed approach ensures combustion stability under different engine operating conditions.The use of hydrogen in the fuel mixture improves the environmental and energy efficiency of gas turbine engines.However, there are particularities of its use that must be taken into account.Key words: gas turbine; low-emission combustion chamber; environmental parameters; emissions of toxic components.. , . , (NO) (CO), . . - . , ,

With the growing place taken by hydrogen, a question still remains about its delivery and transport from the production site to the end user by employing the existing extensive natural gas pipelines. Indeed, the key challenge is the significant H 2 permeation through polymer infrastructures (PolyEthylene (PE) pipes, components such as connecting parts). This high flow rate of H 2 through PE has to be taken into account for safety and economic requirements. A 3-year project was launched, the aim of which was to develop and assess material solutions to cope with present problems for hydrogen gas distribution and to sustain higher pressure compared to classical high density polyethylene pipe. This project investigated pure hydrogen gas and mixtures with natural gas (20% of CH 4 and 80% of H 2) in pipelines with the aim to select engineering polymers which are more innovative than polyethylene and show outstanding properties, in terms of perme-ation, basic mechanical tests but also more specific characterizations such as long term ageing and behaviour. The adequate benches, equipments and scientific approach for materials testing had been developed and validated. In this context, the paper will focus on the evaluation of the barrier properties of 3 polymers (PE, PA11 and PAHM). Experiments were performed for pure H 2 and CH 4 and also in the presence of mixtures of hydrogen and natural gas in order to study the possible mixing effects of gases. It will report some round-robin tests that have been carried out. Secondly, by comparing data obtained on film, polymer membrane and on pipe section, the influence of the polymer processing will be studied. Innovative multilayers systems will be proposed and compared on the basis of the results obtained on monolayer systems. Finally, the evolution of the transport properties of the studied polymers with an ageing under representative service conditions will be discussed.

*† The paper describes the results of the electron -beam ini tiation of the combustion in the mixtures of hydrogen, natural gas and kerosene vapors with air, graphite microparticles suspe nsion in oxygen. The means of controlling these reactions with the aid of the electron beam are shown. The graphite combustion ini tiation occurred at the moment of the beam start, for the homogeneous mixtures the ignition delay reached several hundreds microse conds. Combu stion initiation in the stream of oxygen – natural gas mixture at M=5 was obtained.

An assessment of the effectiveness of the analytical methods to fracture propagation control using accurate mathematical modelling