Combustion Promoter Research Articles

Synthesis and Effects of Two Novel Rare-Earth Energetic Complexes on Thermal Decomposition of Cyclotetramethylene Tetranitramine (HMX).

In order to explore the effect of the energetic complex on the thermal decomposition HMX, two new rare-earth energetic complexes [La(tza)(NO3)2(H2O)4]n (1) and [Ce(tza)(NO3)2(H2O)4]n (2) (Htza = tetrazole-1-acetic acid) were prepared by a solvent evaporation method. The obtained products were structurally characterized by Fourier-transform infrared spectroscopy (FTIR), elemental analysis, powder X-ray diffraction (PXRD), single crystal X-ray diffraction (XRD), and thermogravimetric analysis coupled with differential scanning calorimetry (TG-DSC). In addition, the compatibility of complex 1 with cyclotetramethylene tetranitramine (HMX) was studied by DSC and FTIR, respectively. Structural analysis suggested that complex 1 exhibits an orthorhombic, P 21 21 21 space group, and the La (III) ion was 10-fold coordinated in a distorted double-capped antiprism configuration. Complex 2 featured a one-dimensional, right-handed helical infinite chain. The effect of complexes 1 and 2 on the thermal decomposition of HMX was investigated by DSC, which revealed that complex 1 showed a slightly better effect than 2 on the thermal decomposition of HMX and released more heat. Furthermore, complex 1 had good compatibility with HMX, indicating that it may act as a combustion promoter for nitrate ester plasticized polyether (NEPE) solid propellant.

Effect of the additives on combustion characteristics and desulfurization performance of cow dung briquette

Transformation of agricultural wastes into biomass energy is a strategy towards the development of alternative energy sources. In this study, the effect of the additives on combustion performance of cow dung briquette was investigated. Cow dung briquette (CDB) was prepared using the cold-press briquetting technology by mixing of coal and cow dung as raw materials, composite of potassium nitrate, manganese dioxide and citric acid as combustion promoter, mixture of calmogastrin and molybdenum as smoking suppressor, sodium humate and red clay as binder and acidified calcium oxide as desulphurizer. The comprehensive combustion characteristic index (SN), the stable burning characteristic index (DW) and the burnout index (Cb) of CDB were calculated by thermogravimetric analysis. The desulphurizing property of CDB was examined. When the mass ratio of cow dung to coal is 1:3-4, the mass content of binder, combustion promoter, smoke suppressor and desulphurizer are 17.0%, 6.0%, 4.5% and 6.5%, respectively, the calorific value of CDB is 19.1 MJ/kg, ash content is 29.5%, volatile matter is 13.0% and desulphurization rate can be reached to 70.02%.

Thermostable and insensitivity furazan energetic complexes: Syntheses, structures and modified combustion performance for ammonium perchlorate

It is an important issue to balance energy and sensitivity in the construction of high energy materials. Herein, two furozacycline energetic complexes ([Zn(HTZF)(H2O)3]·H2O (1) and [Co(HTZF)(H2O)3]·2H2O (2) (HTZF = 3-hydroxyl-4-(tetrazol-5-yl)furazan)) were hydrothermally synthesized. Single crystal X-ray diffraction shows that in 1, energetic ligand adopting bidentate chelating coordination mode coordinates to Zn2+. The coordinated units Zn(HTZF)2(H2O)2 and Zn(H2O)4 are alternatively linked to an infinite chain through nitrogen atom in furazan group, and with the aid of hydrogen bonding interaction, forming 3D supramolecule structure. Different in 2, ligand coordinates to Co2+ in bidentate chelating coordination and bridging coordination modes. π⋯π interaction further supports 3D framework stabilization. The thermal decomposition temperature of 1 and 2 are up to 293.0 °C and 295.8 °C, respectively. The heat of detonation (Q), detonation velocity (D), and detonation pressure (P), were evaluated to be, for 1: 1.123 kcal·g−1, 7.971 km·s−1 and 30.8 GPa; for 2: 2.165 kcal·g−1, 8.846 km·s−1 and 35.3 GPa. 1 and 2 are insensitive to impact and friction. As combustion promoter, both of complexes can effectively accelerate the thermal decomposition of ammonium perchlorate (AP).

Experimental investigation and evaluation of using ammonia and gasoline fuel blends for power generators

This paper aims to make use of ammonia as a possible fuel source for power generators and an experimental study is conducted using a gasoline generator with ammonia based gasoline fuel blends. The main aim of using ammonia is to decrease the greenhouse emissions compared to deleterious emissions occurring after the combustion of fossil fuels. In the experimental works the exhaust temperatures, power output and CO2 emissions are measured between 369.9 °C to 480.1 °C, 3689.2 W to 3572.8 W and 2.535 g/s to 2.4916 g/s, respectively with the increase in ammonia percentage of the fuel blends. The measured variables from the experimental studies are later on used for assessing the performance of the generator by finding the energy and exergy efficiencies of the ammonia based gasoline blends under different fuel ratios. The overall energy and exergy efficiencies of the generator decrease from 35.7% to 28.74% and from 44.85% to 36.4%, respectively with the increase of ammonia percentage of the fuel blends. The reductions in the efficiencies are, as expected, take place with the lower energy density and lower heating values of ammonia in compared to gasoline, but the reduction in CO2 emissions make it worth of using ammonia as a combustion promoter.

Performance assesment of hydrogen and ammonia combustion with various fuels for power generators

This paper proposes the use of hydrogen and ammonia as possible fuels for power generators and to do so the combustion is modelled by using different types of fuels which are; hydrogen, gasoline, diesel, ethanol, methanol, propane, butane and natural gas to see the effects of these fuel sources on combustion. The main aim of using a clean fuel is to decrease the greenhouse emissions, and by looking at the results, the reduction in CO2 emissions shows that blending hydrogen and ammonia will result in a reduction for the deleterious emissions occurring after combustion. The reason behind using a dual fueled system is to make use of the secondary fuel source as a combustion promoter to help increase the low flame temperatures of ammonia that causes it not to ignite when used solely. In the modelling of combustion the maximum power output is set to 3.65 kW as this is the maximum power output for the power generator used in the experimental studies. In the studies the increase of clean fuel percentage in the fuel blend cause a reduction in the performance measures as expected with the lower energy density and lower heating values that ammonia offers but the reduction in CO2 and NOx emissions makes it a fuel source worth using with a combustion promoter.

Zinc peroxide combustion promoter in preparation of CuO layers for conductometric CO2 sensing

The detection of CO2 has applications for both industrial and domestic use due to its high exposure effects on the human health. Conductivity sensors on the other hand, present a cost-effective approach that can be successfully utilized for the detection of CO2. However, the integration of metal oxide based nanoparticles layers for conducometric sensing is complicated and requires improvement in the layer quality to achieve effective and stable gas sensing properties. Addressing this challenge, we present in this work, p-type semiconducting CuO nanoparticles as a CO2 gas sensitive material and introduce a combination of organic binder and peroxide such as ZnO2 for improved gas sensitive layer quality. The addition of ZnO2 to CuO nanoparticles enables the layers annealing at 300°C which makes the preparation method compatible to silicon based gas sensing devices. For the characterization of layers, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis and Fourier transform infrared measurements are employed. The CO2 gas sensing measurements show a reversible change in resistance suggesting hybrid nanoparticles layers as an efficient gas sensitive material. The measurements performed at different humidity levels for CuO-ZnO2 (10:1) layer indicate different sensing mechanism for dry conditions in comparison to the measurements performed under humid atmosphere. The Lewis acid-base reaction between oxide oxygen and CO2 has been proposed as sensing mechanism for the measurements in dry air, whereas the formation of surface barriers between nano-grains due to the reaction with CO2 has been suggested for the CO2 response under humid conditions.

Superior Thermostability, Good Detonation Properties, Insensitivity, and the Effect on the Thermal Decomposition of Ammonium Perchlorate for a New Solvent-Free 3D Energetic PbII -MOF.

A new solvent-free energetic MOF, [Pb(HBTI)]n (1) (H3 BTI=4,5-bis(1H-tetrazole)-1H-imidazole), has been synthesized under hydrothermal and acidic conditions. It was characterized by elemental analysis, IR, thermogravimetric, differential scanning calorimetry (DSC) and SEM. Single crystal X-ray diffraction analysis revealed that 1 features a rigid 3D framework architecture free of solvent molecules. Thermal analysis demonstrated that the thermostability of 1 was up to 325 °C. Non-isothermal kinetic and apparent thermodynamic parameters of exothermic decomposition process of 1 were determined by Kissinger's and Ozawa's methods. Through oxygen-bomb combustion calorimetry, the standard molar enthalpy of formation of 1 was determined. The calculated detonation properties (heat of detonation, detonation velocity and detonation pressure) and sensitivity tests of 1 were carried out. In addition, 1 was explored as combustion promoter to accelerate the thermal decompositions of ammonium perchlorate (AP) by differential scanning calorimetry. Experimental results indicated that 1 possesses potential application prospects in the field of explosives and propellants.

Combustion Promoters for Hydrocarbon Fuels

We present a review of combustion promoters, including the major classes of organic compounds that can be used in internal combustion engines. We also consider compounds developed that have high promoter action. We give a comparative evaluation of the considered promoters based on analysis of the mechanism of action for the promoters.

Hydrogen generation system for ammonia–hydrogen fuelled internal combustion engines

Ammonia is a well known hydrogen carrier which can be effectively utilized as a fuel in internal combustion engines (ICEs) when a small percentage of other fuels are added as combustion promoters. Among them, hydrogen is certainly the most valuable since it is carbon free and has opposed and complementary characteristics to those of ammonia.In this work, a Hydrogen Generation System (HGS) capable of supplying up to 1.4 Nm3 h−1 of H2 from ammonia was successfully developed and coupled to an ICE fuelled with ammonia. The main component of the HGS is a cracking reactor housing a ruthenium based catalyst. This system is capable of working both in a stand-alone mode (as required in vehicular applications for the cold start) and in combination with a spark ignited (SI) ICE (i.e. using the combusted gases exhausted by the engine). Beside the cracking reactor, an integrated system was designed and realized in order to allow system cold start and increase overall efficiency during steady state operations.The engine experimental activity confirmed the reactor performance, which was previously verified on a dedicated test bench. Although a lower hydrogen flow rate could be used to achieve satisfactory engine operation, a greater value was used during engine experimentation with benefits for fuel economy and engine cyclic variability. On the other hand, this choice led to higher NOx emissions.

Synthesis and characterization of La0.6Sr0.4Fe0.8Cu0.2O3−δ oxide as cathode for Intermediate Temperature Solid Oxide Fuel Cells

Nanocrystalline La0.6Sr0.4Fe0.8Cu0.2O3−δ (LSFCu) material was synthetized by combustion method using EDTA as fuel/chelating agent and NH4NO3 as combustion promoter. Structural characterization using thermodiffraction data allowed to determine a reversible phase transition at 425°C from a low temperature R-3c phase to a high temperature Pm-3m phase and to calculate the thermal expansion coefficient (TEC) of both phases. Important characteristics for cathode application as electronic conductivity and chemical compatibility with Ce0.9Gd0.1O2−δ (CGO) electrolyte were evaluated. LSFCu presented a p-type conductor behavior with maximum conductivity of 135Scm−1 at 275°C and showed a good stability with CGO electrolyte at high temperatures. This work confirmed that as prepared LSFCu has excellent microstructural characteristics and an electrical conductivity between 100 and 60Scm−1 in the 500–700°C range which is sufficiently high to work as intermediate temperature Solid Oxide Fuel Cells (IT-SOFCs) cathode. However a change in the thermal expansion coefficient consistent with a small oxygen loss process may affect the electrode-electrolyte interface during fabrication and operation of a SOFC.

Potential and Challenges for a Water-Gas-Shift Catalyst as a Combustion Promoter on a D-EGR® Engine

Potential and Challenges for a Water-Gas-Shift Catalyst as a Combustion Promoter on a D-EGR^® Engine

Effect of CO Combustion Promoters on Combustion Air Partition in FCC under Nearly Complete Combustion

With CO combustion promoters, the role of combustion air flow rate for concerns of economics and control is important. The combustion air is conceptually divided to three parts: the air consumed by coke burning, the air consumed by CO combustion and the air unreacted. A mathematical model of a fluid catalytic cracking (FCC) unit, which includes a quantitative correlation of CO heterogeneous combustion and the amount of CO combustion promoters, is introduced to investigate the effects of promoters on the three parts of combustion air. The results show that the air consumed by coke burning is almost linear to combustion air flow rate, while the air consumed by CO combustion promoters tends to saturate as combustion air flow rate increases, indicating that higher air flow rate can only be used as a manipulated variable to control the oxygen content for an economic concern.

A new continuous-flow process for catalytic conversion of glycerol to oxygenated fuel additive: Catalyst screening

A new continuous-flow reactor was designed for the conversion of glycerol to solketal, an oxygenated fuel additive, through ketalization with acetone. Six heterogeneous catalysts were investigated with respect to their catalytic activity and stability in a flow reactor. The acidity of the catalysts positively influences the catalyst’s activity. Among all the solid acid catalysts tested, the maximum solketal yield from experiments at 40°C, 600 psi and WHSV of 4h−1 attained 73% and 88% at the acetone/glycerol molar ratio of 2.0 and 6.0, respectively, with Amberlyst Wet. Based on the solketal yield and glycerol conversion results, the activity of all catalysts tested follows the following order of sequence: Amberlyst Wet≈Zeolite≈Amberlyst Dry>Zirconium Sulfate>Montmorillonite>Polymax. An increase in acetone/glycerol molar ratio or a decrease in WHSV enhanced the glycerol conversion as expected. This process offers an attractive route for converting glycerol, the main by-product of biodiesel, to solketal – a value-added green product with potential industrial applications as a valuable fuel additive or combustion promoter for gasoline engines.

Low temperature sintering of binder-containing TiO2/metal peroxide pastes for dye-sensitized solar cells

The first report of low temperature thermal sintering of binder-containing TiO2 pastes giving η = 7.5% using metal peroxide combustion promoters.

The Selection of Fluid Catalytic Cracking Catalysts and Additives: The Significance of Attrition Studies

Fluid catalytic cracking (FCC) is an important secondary conversion process in refinery that converts heavier gas oils and residues to valuable petroleum products. In the present and future crude oil availability scenario demand for FCC process that increases the refinery margins is growing. Continuous attempts are being made to improve FCC margin through process optimization, selection and use of improved catalysts and additives as well as hardware modifications. Refiners often face challenging task of judiciously selecting and switching to improved catalysts and additives for maximizing profits without violating hardware constraints. It is very difficult to select catalyst or additives based on vendor's claims and testing the catalyst directly in the plant is also risky business. It is important to match the plant performance closely to understand unit constraints and exploit the new catalyst capabilities to full extent. Detailed study with respect to catalyst deactivation, microactivity studies, complete characterization, and prediction of performance on the commercial scale, as well as economic evaluation, are key steps in catalyst or additive selection. Catalyst attrition is key issue now days due to heavy losses observed in the plant and frequent shut downs of the CO boiler units. In riser and regenerator reactor of FCC process, catalyst undergoes attrition due to various reasons such as inherent characteristics of catalyst/additive or due to process environment. Poor attrition of either catalyst/additive result into catalyst loss, fouling, and plugging of down stream units. In this communication the attrition behavior of different catalysts and additives and combined effect of base fluid catalytic cracking catalyst along with different additives in various proportions have been evaluated using an ASTM method in laboratory. Attrition behavior of different FCC additives such as CO combustion promoter, Octane and LPG booster and gasoline sulfur reduction additives were measured in isolation as well as by mixing with base catalyst in different proportion. Certain when studied alone exhibited higher attrition when compared with others. It is observed that even though absolute attrition strength of certain additives such as gasoline sulfur is poor, when used along with base catalyst in desired proportion the loss due to attrition was minimized. This study in combination with VGO cracking activity results helps to select suitable catalyst/additive for enhancing FCC process profits.

Economic and Control Performance of a Fluid Catalytic Cracking Unit: Interactions between Combustion Air and CO Promoters

The presence of CO combustion promoters significantly affects the heterogeneous CO combustion in the regenerator of a fluid catalytic cracking (FCC) unit. Neglecting the quantitative correlation between the heterogeneous CO combustion and the amount of added CO combustion promoters in the previous models makes it impossible to predict the steady-state and the dynamic behaviors of the system with respect to the CO combustion promoters. Therefore, an augmented dynamic model of an FCC unit with high-efficiency regenerator incorporating the quantitative correlation between heterogeneous CO combustion and the CO combustion promoters is developed, and the corresponding closed-loop dynamic responses are obtained. Since CO combustion in the regenerator is affected by both the combustion air flow rate and the CO combustion promoters, a sensitivity analysis of some important variables related to the combustion air flow rate and the amount of added CO combustion promoters is carried out and the overall operating map of the system is developed by selecting the conversion of the riser, the integrated absolute errors of the controllers, and the temperature rise between the dense bed and the outlet of the freeboard to represent the concerns of economics, control, and safety.

Impacts of a Nanosized Ceria Additive on Diesel Engine Emissions of Particulate and Gaseous Pollutants

Fuel additives incorporating nanosized ceria have been increasingly used in diesel engines as combustion promoters. However, few studies have assessed the impact of these nanotechnology-based additives on pollutant emissions. Here, we systematically compare emission rates of particulate and gaseous pollutants from a single-cylinder, four-cycle diesel engine using fuel mixes containing nanoceria of varying concentrations. The test fuels were made by adding different amounts of a commercial fuel additive Envirox into an ultralow-sulfur diesel fuel at 0 (base fuel), 0.1-, 1-, and 10-fold the manufacturer-recommended concentration of 0.5 mL Envirox per liter of fuel. The addition of Envirox resulted in ceria-concentration-dependent emission reductions of CO2, CO, total particulate mass, formaldehyde, acetaldehyde, acrolein, and several polycyclic aromatic hydrocarbons. These reductions at the manufacturer-recommended doping concentration, however, were accompanied by a substantial increase of certain other air pollutants, specifically the number of ultrafine particles (+32%), NO(x) (+9.3%), and the particle-phase benzo[a]pyrene toxic equivalence quotient (+35%). Increasing fuel ceria concentrations also led to decreases in the size of emitted particles. Given health concerns related to ultrafine particles and NO(x), our findings call for additional studies to further evaluate health risks associated with the use of nanoceria additives in various engines under various operating conditions.

Evaluation of the possibility of using combustion promoters in hydrocarbon fuels for perspective jet engines

The article presents the analysis of published data and results of experimental studies performed by the authors regarding the effect of combustion promoters peroxides and hydro-peroxides on the turbulent burning rate of fuel TS-1. It was determined that the specific pulse thrust of the model pulse-detonating engine may be increased by 2.5 - 3.0 times. The same goes for the degree and burning rate of the fuel-air mixture. The authors explain the mechanism of action of promoters for increasing the activity of the fuel-air mixture in the process of combustion.

From a Literature Review to an Alternative Treatment System for Landfill Gas and Leachate

This paper provides an alternative treatment system for landfill gas and leachate control in order to reduce the energy consumption and disposal cost, using the recycled landfill gas as the combustion promoter for incineration of the leachate. This study starts by providing a literature review to summarize and analyze different approaches being applied to landfill leachate treatment. Subsequently, a conceptual prototype is proposed, which can be built using existing technology by means of technical possibility analysis, whilst economic benefits could be returned through preliminary comparison. With the proposed introduction of a “waste treatment park”, this alternative treatment system could provide a template for leachate and landfill gas control. This study may provide an insight for landfill operators and engineers to promote the transformation from the conceptual framework to the real achievement. Finally, the limitations of the conceptual model and analysis are discussed, laying a foundation for further work.

Analysis of the behaviour of a 4-stroke Si engine fuelled with ammonia and hydrogen

The use of hydrogen as fuel represents a possible solution to reduce greenhouse gas emission from vehicles. Although proper engine running with hydrogen has been widely demonstrated, hydrogen storage onboard of the vehicle is a major problem.A promising solution is storing hydrogen in the form of ammonia that is liquid at roughly 9 bar at environmental temperature and therefore involves relatively small volumes and requires light and low-cost tanks.Ammonia can be burned directly in IC engines, however a combustion promoter is necessary to support combustion. As a matter of fact, the best (and carbon-free) promoter is hydrogen, which has very high combustion velocity and wide flammability range, whereas ammonia combustion is characterised by low flame speed and temperature, narrow flammability range and high ignition energy.The experimental activity shown in this paper is focused on analysing the behaviour of a 4-stroke twin-cylinder SI engine of 505 cm3 fuelled ammonia-plus-hydrogen. This engine was expressly chosen and modified to be placed in a range extended vehicle where hydrogen is obtained from ammonia by means of on-board catalytic reforming. The experimental results confirm that it is necessary to add hydrogen to air-ammonia mixture to improve ignition and to increase combustion velocity, with ratios that depend mainly on load and less on engine speed. Owing to intake air dilution and to lower flame speed of the ammonia-hydrogen-air mixture, a general decrement in engine performances has been detected in respect to the original gasoline version.