Acetylene Yield Research Articles

Non-Thermal Plasma Pyrolysis of Fuel Oil in the Liquid Phase

A pulsed plasma pyrolysis reactor with an efficient control system was designed for fuel oil processing. Non-thermal plasma pyrolysis was carried out in the liquid phase at low temperatures (not higher than 100 °C) in a 300 cm3 reactor without additional reagents or catalysts. The main process parameters and characteristics of non-thermal plasma fuel oil products were investigated within the DC source voltage range of 300–700 V. An increase in the energy of pulsed discharges led to an increase in the productivity of the plasma pyrolysis process and the yield of hydrogen but reduced the yield of acetylene and ethylene. The resulting gas consisted predominantly of hydrogen (46.5–50.0 mol%), acetylene (28.8–34.3 mol%), ethylene (7.6–8.6 mol%), methane (4.2–6.2 mol%), and C3–C5 hydrocarbons. The solid-phase products were in the form of disordered graphite and multilayer nanotubes.

Study on High Temperature Pyrolysis Light Cycle Oil to Acetylene and Carbon Black

The reaction performance of producing acetylene by light cycle oil (LCO) high temperature pyrolysis was investigated with a self-made electromagnetic induction heating device. The results showed that the reaction temperature and residence time were the main factors restricting the production of acetylene during LCO high temperature cracking. When the reaction temperature was 1800 °C and the residence time was 8.24 ms, the yield of acetylene reached 7.90%. At the same time, the comparative study of different raw materials shows that Yangzhou heavy cycle oil (YZHCO) with a higher content of chain alkanes, cycloalkanes, and tetrahydro-naphthalene aromatics was beneficial to the formation of acetylene, and the highest yield of acetylene reached to 12.7%. The preliminary characterization of byproduct carbon black showed it had a good structure and could be used for lithium electron conductive agent.

Development of a microkinetic model for non-oxidative coupling of methane over a Cu catalyst in a non-thermal plasma reactor

A surface microkinetic plasma model for non-oxidative coupling of methane into H2 and higher hydrocarbons was developed over a Cu catalytic film. Twenty key plasma species including electron, ions, radicals, and neutrals were considered in respective chemical reactions leading to the formation of C2 hydrocarbons onto the catalyst surface. The kinetic model was coupled with a global plasma model to describe the performance of a non-thermal plasma reactor. In the reactor model, the reactant gas flows between the two coaxial cylindrical metal electrodes with a length of 50 mm and a diameter of 2 mm (inner) and 6 mm (outer electrode) coated with a Cu film. The effect of discharge power, initial CH4 concentration, and inlet flow rate on methane conversion was investigated. The surface model shows that the CH4 conversion of 47% is obtained at a discharge power of 70 W with a selectivity of C2H2 (49%). Increase in power increased the conversion of methane while increase in pressure and/or inlet gas flow rate decreased it. Also, the results of the plasma-catalyst model were compared with those of plasma alone (without catalyst). It showed that presence of the catalyst inside the plasma increases the selectivity and yield of acetylene, while it deceases the selectivity and yield of hydrogen. Also, the density of radical CH3 in the plasma phase increased in the presence of catalyst, while CH2 and CH densities decreased with that.

Impact of post-flame processes on the hydrogen yield in partial oxidation of methane in the matrix reformer

Non-catalytic partial oxidation of methane in matrix reformers offers the possibility of producing hydrogen directly at sites of its consumption, in particular from local bioresources and non-traditional fossil hydrocarbons. The kinetics simulation of the process shows that it proceeds in two stages. In the flame zone, in the presence of oxygen, along with CO, H2, CO2 and H2O, methane pyrolysis products are formed. Then, in the post-flame zone, in the absence of oxygen, at 1400–1600 K the slow pyrolysis and steam conversion of the products occur. Kinetic analysis shows that the pyrolysis of methane into acetylene and the subsequent steam reforming of the latter proceeds much faster than the direct interaction of methane with H2O, which leads to decreasing methane and acetylene concertation and increasing H2 and CO concentration. It is necessary to optimize conditions in the prost-flame zone to increase hydrogen yield and decrease acetylene yield.

Моделювання процесу синтезу ацетилену в ChemCAD та особливості зв’язку зі SCADA за допомогою технології OPC

The article examines the features of constructing mathematical models in modern universal modeling programs and their further use using OPC technology in control systems for processes of chemical technology based on SCADA systems. The objective is to study the features of information exchange using OPC technology between the universal ChemCAD simulator and the modern SCADA system TRACE-MODE 6 using the example of a mathematical model of a kinetic reactor for the synthesis of acetylene. To achieve this goal, a mathematical model of a kinetic reactor for the synthesis of acetylene based on a model of a continuous stirring reactor has been developed in the ChemCAD simulation software environment. The reactor was tuned and the parameters of material flows were experimentally selected. A study of the process of synthesis of acetylene was carried out according to a mathematical model, a graphical dependence of the yield of acetylene on temperature was obtained and its analysis was carried out, according to the results of which the temperature providing the maximum yield of acetylene was established. With the help of OPC technology, information exchange between the model and the control system of the acetylene synthesis process is carried out, which is based on the modern SCADA system TRACE-MODE 6. A graphical dependence is obtained describing the transient process of the system through the acetylene output channel when using a PID controller and perturbing with a change in the task. The analysis of the transient process revealed the absence of transport lag, which is explained by the calculated nature of the control object and is impossible for a real technological process. To solve the problem, an experiment was carried out, according to the results of which a method for emulating transport lag using the functionality of the information channels of the SCADA system was proposed. The graph of the transient process of the system through the acetylene outlet channel was obtained, which confirms the effectiveness of the proposed method of emulation of transport delay when using external calculation models in SCADA systems. Keywords: mathematical modeling, universal modeling programs, OPC, control systems, SCADA-based control, TRACE-MODE, ChemCAD.

Investigation of natural gas/hydrogen mixtures for exergy storage in a piston engine

The conversion of mechanical to chemical energy offers an option for long-term and versatile energy storage. It was already proven that piston engines can be used as flexible reactors for energy conversion. Here, a novel method for energy conversion in piston engines is investigated, the pyrolysis of natural gas/hydrogen mixtures for energy storage. The supplied energy is stored by chemical conversion into hydrogen and higher energy hydrocarbons. The storage efficiency and the product composition are addressed here. To reach sufficiently high temperatures after compression, a dilution with 85–99% argon is used. The main products are hydrogen, acetylene, ethylene and benzene but also soot precursors are formed. The piston engine is simulated as a time-dependent four-stroke single-zone model with detailed chemical kinetics. The intake pressure is kept constant at 2 bar, while intake temperature, intake argon mole fraction and the hydrogen/natural gas ratio is varied. The hydrogen addition allows a reduction of the intake temperature and argon dilution but also reduces the storage power and efficiency. Yields of acetylene or ethylene are increased and the formation of soot precursors is suppressed. A storage power of 1.59 kW is reached with an efficiency of 52%.

Influence of hydrogen addition on methane coupling in a moderate pressure microwave plasma

In this paper, the effect of hydrogen addition on methane coupling in a microwave moderate pressure (55 mbar and 110 mbar) plasma reactor has been studied. The use of optical emission spectroscopy allowed the determination of the rotational temperature of heavy particles and showed it to be in the range of 3000–4000 K. Due to the high temperature in the discharge the dominant product was acetylene and it was concluded that the methane coupling process is mainly through thermal decomposition with a key role of H radicals. It was revealed that the addition of hydrogen can increase both methane conversion and acetylene and ethylene yield and selectivity. With the CH4:H2 ratio of 1:1, the methane conversion increased from 31.0% to 42.1% (55 mbar) and from 34.0% to 48.6% (110 mbar), when compared to pure methane plasma. Respectively, the yield of acetylene increased from 14.4% to 25.3% (55 mbar) and from 20.1% to 34.0% (110 mbar). Moreover, the addition of hydrogen decreased the output of the problematic soot-like product. These results indicate that hydrogen addition can be a simple yet effective method of increasing selectivity to desirable products in plasma reforming of CH4.

The impact of fuel ratio and refueling mode on pre-combustion cracking properties of RP-3 kerosene

To achieve kerosene-air rotating detonation without adding hydrogen and oxygen supplement, the pre-combustion cracking of RP-3 kerosene to produce active gas is explored. Effects of fuel ratio (3.2–14.6) and refueling mode on the cracking products distribution are investigated. The effective cracking rate of RP-3 kerosene strongly depends on the fuel ratio, with which kerosene conversion decreases rapidly, and the highest effective cracking rate reaches 92%. In cracking gas, about 26.4% is combustible components, including hydrogen, acetylene, methane, ethylene, carbon monoxide. Among them, carbon monoxide is the highest yield species in the cracking products, reaching 4940 mg/s at the fuel ratio of 3.2. And the highest yields of hydrogen and acetylene are 294 mg/s and 1364 mg/s, respectively. The yield and mole fraction of component decreased obviously with the increase of fuel ratio. In view of the reason that the center temperature of the downstream section is higher, the yield and percentage of component are higher than that when secondary kerosene is injected at the upstream section. Refueling mode has a significant effect on the product distribution, and the mode of refueling with circumferential six nozzles is superior to that of circumferential three nozzles, with which higher component percentage and product mass flow can be obtained. By contrast, the proportion of ethylene in cracking products can be greatly increased by axial refueling mode. Choosing the axial refueling mode at downstream section can obtain higher cracking rate and lower C/H ratio, while choosing the refueling mode with circumferential six nozzles, the content of high active components is more.

Effect of Hydrogen, Carbon Monoxide, Synthesis Gas, and Steam Additives on the Characteristics of Matrix Conversion of Rich Methane–Oxygen Mixtures

An experimental study and detailed kinetic modeling of characteristics of the matrix conversion of a methane–oxygen mixture with the addition of hydrogen, carbon monoxide, synthesis gas, and steam have been carried out. It has been shown that the most significant effect on the product composition is provided by the admixture of steam, which reduces the yield of acetylene and at the same time increases the H2/CO ratio. The kinetic simulation results appear to agree well with the experimental data obtained.

МОДЕЛЮВАННЯ ХІМІКО-ТЕХНОЛОГІЧНИХ ПРОЦЕСІВ У SCADA ЗА ДОПОМОГОЮ ТЕХНОЛОГІЇ OPEN PLATFORM COMMUNICATIONS

The subject of study in the article are methods for integrating mathematical models of chemical-technological processes implemented in universal modeling programs into modern SCADA systems for developing and improving methods for controlling these processes. The goal is to develop a control system for the synthesis of acetylene in a kinetic reactor, based on a computer model created in universal modeling programs and integrated into SCADA using open platform communications (OPC) technology. Tasks: to create a mathematical model of the process of synthesis of acetylene based on the selected universal modeling program; to develop a way to integrate the resulting model into modern SCADA using OPC technology; to develop in SCADA a control system for the process of synthesis of acetylene according to a mathematical model as part of a functional human-machine interface and control subsystem algorithms; get transient graphs and prove the efficiency of the control system. Conduct a process study using a mathematical model. The methods used are computer simulation of technological processes; OPC technology; SCADA based management. The following results are obtained. A control system for the acetylene synthesis process based on SCADA Trace-Mode and a mathematical model implemented in the ChemCAD package has been developed, while the model - control system information exchange is implemented based on OPC technology. Checked and proved the efficiency of the resulting control system. A mathematical study of the process was carried out, an experimental dependence of the yield of the final product, acetylene, on the temperature, and consumption of raw materials at the inlet of the reactor was established. Conclusions. The novelty of the results is as follows. A new method is proposed for integrating mathematical models implemented in the ChemCAD modeling package into modern SCADA, based on OPC technology. A study of the process of acetylene synthesis by a mathematical model was carried out, experimental dependences of the acetylene yield on temperature and ethylene consumption at the inlet of the synthesis reactor were obtained. An analysis of the obtained experimental dependences showed the need to use cascade control algorithms to increase the efficiency of controlling the process of acetylene synthesis in a kinetic reactor.

Pyrolysis of Natural Gas: Effects of Process Variables and Reactor Materials on the Product Gas Composition

AbstractHigh‐temperature pyrolysis of natural gas is the basis of the standard method for the manufacture of acetylene. The study of methane pyrolysis was designed to find optimum process conditions that would produce high yields of acetylene with minimal carbon formation. High temperatures and short residence times enhanced the selectivity for acetylene, while hydrogen dilution was found to suppress the generation of carbonous products. Carbon formation on reactor surfaces over time may be mainly responsible for the misalignment of predicted and measured product gas compositions, as the mechanisms reported do not consider the surface chemistry. In essence, the pyrolysis system favors the highest possible temperature and shortest possible residence time, suggesting that the selection of reactor materials is the key for pyrolysis process optimization. The operating temperature is likely dictated by the physical properties of the reactor materials rather than the selection of optimal pyrolysis conditions.

Matrix conversion of natural gas to syngas: The main parameters of the process and possible applications

This study demonstrates the possibility and good practical prospects of a principally new type of noncatalytic matrix conversion of natural gas and associated petroleum gas to syngas. Matrix reformers can operate on various types of oxidizers, such as air, enriched air, and oxygen, thereby producing syngas with the desired nitrogen content, including nitrogen-free syngas for petrochemical applications. The optimal value of oxygen excess coefficient, α = 0.34 − 0.36, provides a high conversion of reagents and a high yield of syngas in such a simple noncatalytic process. Addition of steam stabilizes the matrix temperature and decreases the yield of acetylene, thereby making the process more stable.

Compact solid oxide fuel cells and catalytic reformers based on microtubular membranes

AC heated oxygen-permeable microtubular membranes with the composition Ba0.5Sr0.5Co0.78W0.02Fe0.2O3-δ were used to provide catalytic reforming of methane into C2- hydrocarbons. The methane conversion degree about 60% and acetylene yield about 27% at 1200 °C was achieved. Microtubular solid oxide fuel cells based on gadolinium-doped ceria with perovskite-like cathode material composed of Ba0.5Sr0.5Co0.75Mo0.05Fe0.2O3-δ were prepared. The MT-SOFC demonstrates maximum power densities of 50, 100, 200 mW/cm2 at 550, 600, 650 °C, respectively with humidified H2 as fuel and ambient air as oxidant.

Experimental study of partially decoupled oxidation of ethane for producing ethylene and acetylene

Abstract With increasing amount of unconventional natural gas, the production of ethane, propane and other low alkanes continues to increase. In our previous works, a partially decoupled process (PDP) was proposed for conversion of ethane based on numerical simulations, which showed higher acetylene and ethylene selectivities than the original partial oxidation process. In the current work, the PDP of ethane for producing acetylene and ethylene was studied experimentally to verify the PDP concept. In the PDP of ethane, coke-oven gas or other cheap gas combusts with stoichiometric oxygen as heat carrier, and ethane is mixed with the heat carrier and undergoes pyrolysis at high temperatures. The jet-in-cross-flow (JICF) reactor was designed and manufactured to realize the PDP. A positioning device of 0.1 mm accuracy and a mass spectrometer were used to measure the spatial profiles of the species concentrations. The maximum combined yield (52.7%) of acetylene and ethylene was obtained even at the condition of heat loss, confirming that the PDP of ethane was advantageous over the partial oxidation process and at least comparable to the steam cracking process.

Numerical analysis of methane pyrolysis in thermal plasma for selective synthesis of acetylene

Thermal plasma pyrolysis can realize direct synthesis of acetylene and carbon black from methane, while the yields of products vary according to the reaction conditions. In the present work, a pre-proposed detailed kinetic mechanism is applied to investigate the efficiency and product distribution of methane pyrolysis in thermal plasma. The kinetic mechanism is validated with experiments, which proves the reliability of the mechanism under the conditions of thermal plasma. From simulation results, higher temperature and residence time in millisecond are beneficial for higher acetylene yield, while long residence time is beneficial for the production of carbon black. To be specific, when the temperature is higher than 2100K, conversion of methane is above 99wt% and the yield of acetylene is above 80wt%, which is referred to as the selective synthesis of acetylene from methane. When temperature increases, the proper residence time for the maximum acetylene yield would decrease to within one millisecond.

Removal of trichloroethylene by biochar supported nanoscale zero-valent iron in aqueous solution

Abstract Nanoscale zero-valent iron (NZVI) has been widely used for the degradation of trichloroethylene (TCE) in contaminated water, however, it is suffering from being easy to aggregate and having low adsorption capacity for TCE. In order to overcome the shortcomings of NZVI, modified NZVI particles with biochar (NZVI/BC) were applied in this study for removal and degradation of TCE, given the high stability and adsorption capacity of BC. The effects of pyrolysis temperature of BC, mass ratio of NZVI/BC and solution pH on the removal and degradation efficiency of TCE were studied. The different pyrolysis temperatures of BC resulted in the differences on the surface areas, aromaticity and noncarbonized fractions, which determined the sorption capacity of TCE. Compared with pure NZVI, the NZVI/BC at different mass ratios could increase the removal efficiency of TCE to 99%, which was attributed to the higher adsorption capacity of BC for TCE. Besides, the yield of final products (ethane, ethylene and acetylene) differed at different mass ratios of NZVI/BC. Generally, the main product was ethylene in all reactions and the yield of acetylene and ethane were relatively low. Solution pH had little effect on the total removal of TCE but significantly influenced the yield of final products. The yield of ethylene decreased with the increasing pH. The results indicate that solution pH could not affect the sorption of TCE but influenced the degradation rate of TCE by NZVI/BC.

Enhancement of the acetylene and ethylene yields from ethane by partially decoupling the oxidation and pyrolysis reactions

The ethane contained in wet shale gas is usually used to produce ethylene through the steam cracking process. In parallel, the partial oxidation (POX) of methane is the most important method to produce acetylene. In this paper, the feasibility of the POX process of ethane was first explored. The reaction pathway analysis showed that the exothermal oxidation and endothermic pyrolysis reactions were highly coupled, which limited the yield of C2 species (C2H2+C2H4). To overcome this problem, a new process named partially decoupling process (PDP) was proposed to physically separate the heat supply and pyrolysis reactions in a jet-in-cross-flow (JICF) reactor. The computational fluid dynamics (CFD) coupled with a detailed reaction mechanism, the modified GRI 3.0, was applied to simulate the complex interaction between turbulent mixing and reactions. The results showed that a high combined yield of ethylene and acetylene (69%) could be obtained. The operating and reactor structural parameters were further optimized based on the CFD simulations. The maximum yield of C2 products was found less sensitive to the mixing in the ethane PDP than in the methane PDP, making it easier to scale up the reactor for the ethane PDP.

Role of hydrogen enrichment on acetylene emission during benzene oxidation

A zero-dimensional model (perfectly-stirred reactor) in conjunction with CHEMKIN II and a scheme resulting from the merging of validated kinetic schemes for the oxidation of benzene were used to investigate the effect of hydrogen addition on the formation-depletion of C2H2, which is known as a soot precursor. The current modeling study treats the dependence of acetylene amounts on hydrogen percentage in the fuel mixture, and defines the key reaction mechanisms responsible for the observed reduction in C2H2 and consequently in polycyclic aromatic hydrocarbons and soot amounts induced by the hydrogen additive. The main objective of this work was to obtain fundamental understanding of the mechanisms, through which the hydrogen affects the acetylene yields. It was found that, at high temperatures hydrogen/benzene fuel mixtures displayed lower acetylene concentrations compared to the pure benzene fuel, whereas opposite trends were observed at low reaction temperatures.

Detailed kinetic modeling of chemical quenching processes of acetylene-rich gas at high temperature

Quenching of acetylene-rich gas at high temperature is an essential step in most acetylene production processes. Different from traditional physical quenching methods (e.g., water spray), chemical quenching has the advantage of reusing the gas heat content and producing co-products while preventing acetylene from decomposing. In this work, a detailed kinetic mechanism was proposed to theoretically describe and reveal the chemical quenching process. Reactions of small hydrocarbons, PAHs growth and soot formation were taken into consideration to build the model, which was validated by reported data. Afterwards, an ideal PFR model was used to investigate the effects of different operating conditions, including temperature after quenching, quenching time, and quenching media. Furthermore, the proposed model was used to optimize the chemical quenching operation for a pilot-plant acetylene production process based on thermal plasma technique. The results showed that chemical quenching could effectively realize both energy re-utilization and ethylene co-production, while maintaining a satisfactory yield of acetylene.

Detailed Chemistry Modeling of Partial Combustion of Natural Gas for Coproducing Acetylene and Syngas

ABSTRACTPartial combustion of natural gas is of great popularity in coproducing acetylene and syngas. Instead of macrokinetics, detailed chemistry modeling is performed to describe fuel-rich methane and ethane flames by using two typical combustion mechanisms: GRI-Mech 3.0 and Curran mechanism. A large uncertainty is found in the rate coefficient of C2H2 + OH → CH2CO + H in GRI-Mech 3.0. A more chemically sound rate coefficient expression is proposed and GRI-Mech 3.0 and Curran mechanism are optimized for predicting acetylene profiles in the laminar premixed flames. Major species profiles in the flames are also calculated and compared with experimental data in the literature. The industrial partial combustion process is reasonably predicted by using the new rate coefficient within the framework of GRI-Mech 3.0. The optimum equivalence ratio is determined for attaining the maximum acetylene yield.