CO2 Gas Flow Research Articles

Development of CO2 adsorption materials from recycling spent tire char via orthogonal design: Optimal solution and thermodynamic evaluation

This work uses chemical-physical activation to upgrade spent tire char for capturing CO2, and CO2 gas flow rate is the dominant factor of activation process based on the orthogonal experimental design. The final spent tire activated carbon with a specific surface area of 762.17 m2/g and a microporous pore volume of 0.23 cm3/g was obtained. The CO2 adsorption behavior can be described by the Langmuir and Freundlich models. The optimum spent tire-based activated carbon has the capacity to capture CO2 up to 1.42 mmol/g. It was also confirmed by Gibbs free energy change studies that the optimum spent tire-based activated carbon at less than 58.77 °C allows the CO2 adsorption reaction to proceed spontaneously. The excellent regenerability of the produced activated carbon material was demonstrated by the isosteric heat of adsorption. The process of CO2 adsorption was also confirmed as physical adsorption by various thermodynamic means. The spent tires recycling as CO2 adsorbent is a promising path which realizes the dual benefits of waste recycling and CO2 reduction.

Optimization Study of CO2 Gas Absorption with NaOH Absorbent Continuous System in Raschig Ring Packing Column Using Box–Behnken Design

Increasing CO2 gas emissions results in climate change by increasing air temperature and worsening environmental problems. It is necessary to control CO2 gas in the air to overcome this. This research aims to optimize the absorption of CO2 gas in the air with 0.1 M NaOH absorbent in the column of the Raschig ring stuffing material using the response surface methodology (RSM). This research was conducted using a continuous system of three independent variables by varying the contact time (10–80 min), the flow rate of NaOH absorbent (2–5 L/min), and the flow rate of CO2 gas (1–5 L/min). The response variables in this study were the absorption rate (L/min) and mass transfer coefficient, while the air flow rate was constant at 20 L/min. Air and CO2 gas mix before absorption occurs and flow into the Raschig ring packing column so that contact occurs with the NaOH absorbent. Mass transfer of CO2 gas occurs into the NaOH absorbent, resulting in absorption. The results showed that the effect of contact time (min), the flow rate of NaOH absorbent (L/min), and CO2 gas flow rate individually and the interaction on CO2 absorption rate and mass transfer coefficient were very significant at a p-value of 0.05. Chemical absorption of CO2 also occurred due to the reaction between CO2 and OH- to form CO32− and HCO3−, so the pH decreased, and the reaction was a function of pH. Optimization using Design Expert 13 RSM Box–Behnken Design (BBD) yielded optimal conditions at an absorption time of 80 min, NaOH absorbent flow rate of 5 L/min, CO2 gas flow rate of 5 L/min, absorption rate of CO2 gas of 3.97 L/min, and CO2 gas mass transfer coefficient of 1.443 mol/min m2 atm, with the desirability of 0.999 (≈100%).

Pulsed thulium laser blood vessel haemostasis as an alternative to bipolar forceps during neurosurgical tumour resection

Due to wavelength-specific water absorption, infrared lasers like the thulium laser emitting at 1940 nm wavelength proved to be suitable for coagulation in neurosurgery. Commonly bipolar forceps used for intraoperative haemostasis can cause mechanical and thermal tissue damage, whilst thulium laser can provide a tissue-gentle haemostasis through non-contact coagulation. The aim of this work is a less-damaging blood vessel coagulation by pulsed thulium laser radiation in comparison to standard bipolar forceps haemostasis. Ex vivo porcine blood vessels in brain tissue (0.34 ± 0.20 mm diameter) were irradiated in non-contact with a thulium laser in pulsed mode (1940 nm wavelength, 15 W power, 100–500 ms pulse duration), with a CO2 gas flow provided simultaneously at the distal fibre tip (5 L/min). In comparison, a bipolar forceps was used at various power levels (20–60 W). Tissue coagulation and ablation were evaluated by white light images and vessel occlusion was visualised by optical coherence tomography (OCT) B-scans at a wavelength of 1060 nm. Coagulation efficiency was calculated by means of the quotient of the difference between the coagulation and ablation radius to the coagulation radius. Pulsed laser application achieved blood vessel occlusion rate of 92% at low pulse duration of 200 ms with no occurrence of ablation (coagulation efficiency 100%). Bipolar forceps showed an occlusion rate of 100%, however resulted in tissue ablation. Tissue ablation depth with laser application is limited to 40 μm and by a factor of 10 less traumatising than with bipolar forceps. Pulsed thulium laser radiation achieved blood vessel haemostasis up to 0.3 mm in diameter without tissue ablation and has proven to be a tissue-gentle method compared to bipolar forceps.

Reaction of Carbon Dioxide Gas Absorption with Suspension of Calcium Hydroxide in Slurry Reactor

Chemical phenomena involving three phases (solid, liquid, and gas) are often found in the industry. Carbonate (CaCO3) is widely used in industries as a powder-making material in the cosmetic industry, a pigment in the paint industry, and filler in the paper and rubber industry. This research aim to study the ordering process carbonate deposits (CaCO3) from the absorption process of CO2 gas with Ca(OH)2 suspension. The absorption reaction of CO2 gas with Ca(OH)2 suspension was carried out in a stirred slurry tank reactor. Initially, the reactor containing water was heated to a certain temperature, then Ca(OH)2 was added to the reactor. Furthermore, CO2 gas with a certain flow rate and temperature (according to the reactor temperature) is flown with the help of a gas distributor. Samples were taken every 1 min until the concentration of Ca(OH)2 could not be detected (completely reacted). The variables in this study were: stirrer rotation speed (5.66711.067 rps), CO2 gas flow rate (34.0127–60.5503 c/s), and temperature (30–50°C). The mass transfer coefficient and the reaction rate coefficient were determined by minimizing Sum of Squares of Errors (SSE). This experimental process follows a dynamic regime. A dimensionless number relationship for the gas-liquid mass transfer for the value range is Re1 = 18928.76-38217.20, Sh = 0.07928 Reg0.4383 Rel0.4399 Sc0.6415 with an error of 5.19%. The dimensionless number relationship for solid-liquid mass transfer is Sh = 0.0001179 Reg0.4674 Rel0.5403 Sc1.444 with an error of 7.31%. The relationship between the reaction rate constant and the temperature in the 30-50 °C range can be approximated by the Arrhenius equation, namely kr = 1771000 e-2321.4/T cm3/mgmol/s with an error of 3.63%. Doi: 10.28991/ESJ-2023-07-02-02 Full Text: PDF

Study on CO2 based thermal plasma torch and its effective utilization for material processing in atmospheric pressure

Reuse of greenhouse gases is one of the promising approaches towards controlling global warming to some extent. As a part of that, an attempt has been made to utilize CO2 gas as one of the primary gases to form a thermal plasma jet for material processing. For that purpose, a unique direct current (DC) non-transferred arc thermal plasma torch was designed and its current-voltage characteristics and electro-thermal efficiency with different discharge currents and gas compositions were studied. The torch is made of rod type cathode and a nozzle type anode, which can produce a stable thermal plasma jet under different gas compositions. CH4 was used as a secondary mixing gas in an Ar-CO2 gas composition to produce a carbon-rich thermal plasma with high electro-thermal efficiency. The maximum electro-thermal efficiency of 73 % were reached while the torch operated at 100 A current with 6 slpm of CH4 flow along with 15 and 20 slpm of Ar and CO2 gas flow, respectively. Torch efficiency decreased to 12 % with increase in discharge current from 100 A to 200 A. Optical emission spectrum of the plasma jet was recorded at the exit of the torch nozzle to understand the emission characteristics of the plasma and estimate temperature and electron density. Temperature of the plasma increased from 13,400 to 17,800 K with respect to the discharge current. Thermodynamical studies were carried out for the given experimental conditions to understand the thermal decomposition of CO2-CH4 gas mixture and select the suitable condition for the material processing. Under the selective conditions, plasma torch was utilized for the spheroidization of tungsten metal powder and carburization of the AISI 316 L stainless-steel coupons in atmospheric pressure without using any shielding gases. Results showed that around 85 % of the metal powders were spheroidized perfectly at 15 kW input power. Plasma carburization results showed that the microhardness of the steel surface reached 605 HV with a short processing time of 3 min which was 4 times higher than the untreated steel surface. This work provides useful insight for the utilization of CO2 as primary plasma forming gas to generate thermal plasma for material processing.

Flow measurement challenges for carbon capture, utilisation and storage

Carbon Capture, Utilisation and Storage (CCUS) is a key element in the United Kingdom Government strategy for reducing carbon dioxide (CO2) emissions. The UK aims to capture and store 10 million tonnes of CO2 each year by 2030.At each stage in the CCUS infrastructure, accurate measurement of the CO2 flow rate is required, over a range of temperatures, pressures, flow rates and fluid phases, where the flow measurement must be validated through a credible traceability chain. The traceability chain provides the underpinning confidence required to verify meter performance, financial and fiscal transactions, and environmental compliance. The UK equivalent of the EU Emissions Trading System (EU ETS) specifies a maximum uncertainty value for CO2 flow measurement. Accordingly, the provision of accurate and traceable flow measurement of CO2 is a prerequisite for an operational CCUS scheme.However, there are currently no CO2 flow measurement facilities, nationally or internationally, providing traceable flow calibrations of gas phase, liquid/dense phase and supercritical phase CO2 that replicate real-world CCUS conditions. This lack of traceable CO2 gas and liquid flow measurement facilities and associated flow measurement standards is a significant barrier to the successful implementation of CCUS projects worldwide.This paper presents an overview of the traceability chain required for CO2 flow measurement in the UK and globally. Current challenges are described along with potential solutions and opportunities for the flow measurement community.

Protein-based biochars as potential renewable fillers in styrene-butadiene rubber composites

In this study, chicken feather meal (CFM) and canola protein (CP) were converted into biochar and their suitability as reinforcing fillers in styrene-butadiene rubber (SBR) composites was evaluated. The protein-based feedstocks were pyrolyzed at 700 °C for 1 h, at a heating rate of 50 °C/min under different pyrolysis atmospheric conditions (N2, CO2, and steam). The flow rate of N2 and CO2 was 700 ml/min, while that of steam was 31 ml/min. Also, biochar was produced under N2 and CO2 gas flow and subsequently activated using steam. The physicochemical properties of the resulting CFM and CP biochars were characterized based on elemental and proximate analyses, surface area, Fourier-transform infrared spectroscopy (FTIR), and thermal field emission scanning electron microscopy. Results showed that activated CP, pyrolyzed under nitrogen and subsequently steam cooled (CP N2 + SC), had enhanced physicochemical properties such as lower ash content, higher fixed carbon content, and reduced polar surface functional groups compared to the other studied biochars in this study. Results also showed that CFM and CP pyrolyzed under nitrogen and subsequently steam cooled displayed higher final moduli and better filler dispersion in rubber than the other biochar samples produced in this study. Given that results showed favorable physicochemical properties and higher final moduli for CP N2 + SC, this sample was further tested using dynamic mechanical analysis (DMA) and results showed slight differences with carbon black regarding the temperature dependence of the shear storage modulus (G′) and the loss tangent (tan δ). These differences were attributed to increased filler-filler interactions, reduced filler-rubber interactions, and a lower dispersion in rubber than carbon black. The observed differences were not large enough to explain the inability of the biochar to adequately reinforce the rubber. However, the biochar filled rubber sample had a comparable viscoelastic behavior to carbon black over the studied temperature range.

Engineering the NiNC Catalyst Microenvironment Enabling CO2 Electroreduction with Nearly 100% CO Selectivity in Acid.

CO2 electrolysis in acid has emerged as a promising route to achieve high CO2 utilization due to the inhibition of undesired carbonate formation that generally occurs in alkaline or neutral conditions. However, the efficiency and stability of this system need to be further improved through tailoring of the electrocatalyst and its working environment. Here, a working microenvironment of structurally engineered NiNC catalyst for acidic CO2 electrolysis is probed and optimized by adding hydrophobic poly(tetrafluoroethylene) (PTFE) nanoparticles in the catalytic layer of gas-diffusion electrodes. The PTFE-modified electrode delivers nearly 100% CO Faradaic efficiency at an industry-relevant current density of 250mA cm-2 , and a high single-pass CO2 utilization of 75.7% at a current density of 200mA cm-2 under 20 sccm CO2 gas flow rate. Moreover, compared to a conventional electrode without added PTFE, the PTFE-modified electrode exhibits a substantially enhanced water-flooding-resistant ability. Mechanistic investigations reveal that a moderate PTFE modification can optimize the local CO2 /H2 O ratio in the catalytic layer, favoring the reduction of the diffusion layer thickness and the formation of a highly active and stable solid-liquid-gas interfacial microenvironment.

Upscaling studies for efficiently electric-driven CO2 reduction to CO in ionic liquid-based electrolytes

Electric-driven CO2 reduction to high value-added chemicals is a potential way to solve the carbon emissions. However, the current studies on CO2 electroreduction (CO2ER) are mainly focused on design and preparation of novel electrocatalysts and electrolytes. The large-scale of CO2ER is puzzled in the serious hydrogen evolution reaction (HER) in aqueous electrolytes and inferior reaction stability in an enlarged CO2 electrolyzer. Ionic liquids (ILs) as electrolytes have opened great opportunities for CO2ER due to their unique advantages. Herein, a large-scale CO2ER device containing an upscaling modified H-type flow cell using IL-based electrolytes (UHFC-IL) with the largest electrode active area of 495 cm2 was established for CO2ER studies. The influences of key operating parameters, such as compositions of IL-based electrolytes, electrolytes velocity, CO2 gas flow rate and cell voltage on CO2ER performance were systematically investigated. A high CO2ER performance under the optimum operating conditions achieves 83.9% Faraday Efficiency (FE) for CO with a reaction current of 6.32 A, suppressing HER to only 2% FE. After 10 hr continuous operation, the CO selectivity in IL-based electrolytes is 51.3% higher than that in 0.1 M KHCO3 aqueous electrolytes, which maintains excellent stability with a high CO generation rate of 1.7 L hr-1. In addition, the mechanism of CO2ER to CO boosted by IL-based electrolytes in UHFC-IL was proposed. This study provides experimental parameters and guidance for future research on the amplification process of CO2ER.

A Review on CO2 Absorption using Chemical Solvents at Low and High CO2 Partial Pressure Conditions in a Packed Column

CO2 removal is important for industrial flue gas treatment, biogas enhancement, and natural gas (NG) processing applications. Chemical absorption using an amine-based solvent is a proven technology for CO2 removal from various gases. In recent years, various promising amine solvents have been investigated, either as single or blended solutions, to enhance the CO2 absorption process at low and high CO2 partial pressure conditions. Low CO2 partial pressures (1 – 47 kPa) have been utilized in numerous research works focusing on flue gas treatment and biogas enhancement applications. On the other hand, high CO2 partial pressures were instead applied in NG processing ranging between 750 and 1600 kPa. To provide more insight into the current trends, existing research on CO2 absorption in amine-based solvents is presented in this review focusing on absorption performance in a packed column at low and high CO2 partial pressures. Reports on the effect of different parameters, namely CO2 partial pressure, gas, and liquid flow rates, amine concentrations, and liquid temperature, on the removal of CO2 in the packed column are included. Based on the review, the future direction is further highlighted in this area.

CO2 Absorption from Biogas Using Piperazine-Promoted 2-Amino-2-methyl-1-propanol: Process Performance in a Packed Column

In this work, CO2 absorption from simulated biogas is investigated using different blends of a PZ + AMP solution in an absorption system at CO2 partial pressures ranging between 20 and 110 kPa. The collected data were presented as CO2 removal profiles along the packed column and were evaluated in terms of CO2 removal efficiency (%) and average overall volumetric mass transfer coefficient in the gas phase (KGav¯). An increased PZ concentration in the AMP solution was found to significantly increase the CO2 removal efficiency and KGav¯ values. It was observed that, when conducted at different CO2 partial pressures, gas and liquid flow rates, and chemical concentrations, the Lamine/GCO2 ratio strongly influenced the process behaviour in the packed column. Additionally, the optimal inlet liquid temperature was observed to be 35 ± 2 °C in this study.

Visualization and Measurement of Swirling Flow of Dry Ice Particles in Cyclone Separator-Sublimator

The dry ice sublimation process of carbon dioxide (CO2) is a unique, environmentally friendly technology that can achieve a temperature of −56 °C or lower, which is a triple point of CO2 in CO2 refrigeration systems. In this study, a cyclone separator-evaporator was proposed to separate dry ice particles in an evaporator. As an initial step before introducing the cyclone separator-evaporator into an actual refrigeration system, a prototype cyclone separator-evaporator was constructed to visualize dry ice particles in a separation chamber. A high-speed camera was used to visualize the non-uniform flow of dry ice particles that repeatedly coalescence and collision in a swirl section. Consequently, the dry ice particle size and the circumferential and axial velocities of dry ice were measured. The results show that the equivalent diameter of the most abundant dry ice particles in the cyclone separation chamber is 2.0 mm. As the inner diameter of the separation section decreases, dry ice particles coalesce and grow from an equivalent diameter of 4 mm to a maximum of 40 mm. In addition, the comparison of the experimental and simulation results shows that the drag force due to CO2 gas flow is dominant in the circumferential velocity of dry ice particles.

Valuable Biodiesel Catalyst from Solvay Wastewater

Biodiesel is considered a renewable, green fuel as it is derived from renewable living resources like animal fats or vegetable oils. This research is utilized to investigate the possibility of using Solvay wastewater as a source of biodiesel catalyst, which is CaO. CaCl2 from Solvay wastewater reacts with CO2 to produce CaCO3. CaCO3 is then heated to produce pure CaO. Waste cooking oil, wastewater, and CO2, which are considered dangerous materials to the environment, are used to produce valuable products. This research has environmental and economic benefit benefits of using waste materials as a replacement for raw materials. The selected experimental parameters for the CaCO3 production step are stirring rate (500–1300) rpm, CO2 gas flow rate (900–2000) mL/min, amount of ammonia (15–35) mL, and glycerol volume (0–25) mL. The selected experimental parameters for the biodiesel production step are reaction time (2–6) h, methanol to oil ratio (9–15), catalyst loading (1–5) %, and reaction temperature (50–70) °C. The impact of reaction parameters on reaction responses was assessed using the response surface methodology technique. A formula that represents the reaction response as a function of all the independent factors has been created. The optimization of the process is done in two steps: the first one is for the CaCO3 process while the second one is biodiesel production optimization. The first optimization was done to get the CaCO3 with minimum particle size and yield. The second optimization was done to get the maximum amount of biodiesel using minimum energy and low reaction conditions. Process optimization resulted in another economic benefit for this research. The resulted biodiesel yield equals 95.8% biodiesel yield at 2 h reaction time, 15:1 molar ratio of methanol to oil, 56 °C reaction temperature, and 1% catalyst loading.

Conversion of CO2 in stabilized low-current arc discharge at atmospheric pressure

One of the direct ways to achieve CO2 conversion is through the use of a non-isothermal plasma environment. In this work, we present an experimental study of the dissociation of CO2 in a magnetically-stabilized arc discharge in a cross-flow configuration, where the CO2 gas flow is perpendicular to both the arc and the external magnetic field. The system works at atmospheric pressure. The study examines the effect of the gas flow and discharge current on the quantities of most interest, namely, the CO2 conversion percentage and the energy efficiency of the process. The experimental results show that the conversion tends to increase with the current, while it drops as the gas flow rate is increased. The efficiency seems to decrease with the conversion percentage, as it increases with the flow rate.

A method for monitoring acoustic emissions in geological media under coupled 3-D stress and fluid flow

Fracturing is a critical process affecting rock deformation and geofluid flow in underground engineering. However, previous studies coupled 3-D geomechanics and geofluids rarely considered the process of rock fracture in real time due to the lack of experimental apparatus. In this work, we present an auxiliary device for an existing true triaxial geological apparatus, with which we implanted AE modules into loading platens with grooved fluid channels, to better collect fracture-related acoustic emission signals and their locations. We minimize the end-friction effect in terms of the performance of the auxiliary device, loading method, and program of experiments. Our case study used a cubic sandstone specimen to investigate stress-strain behaviors, the evolution of intrinsic permeability, and the spatiotemporal characteristics of acoustic emissions (AE) under true triaxial stress coupled with CO2 gas flow (1 MPa at the inlet and atmosphere at the outlet). We found an obvious correlation between AE characteristics and the evolution of permeability. The AE signals could be applied to identify the fracture mode that triggered the essential change in rock permeability from a decrease to an increase. Furthermore, the AE source locations suggest the polymodal faulting mode of specimen failure, which is consistent with previous studies and our computed tomography (CT) scanning images. The case study also demonstrated the effectiveness and reliability of the device developed, which can play an important role in studies of oil and gas exploration and geological sequestration of CO2.

CO2 capture and ions removal through reaction with potassium hydroxide in desalination reject brine: Statistical optimization

Previous studies have investigated the overall performance of the modified Solvay process based on a new alkaline compound, namely, KOH. Preliminary results have confirmed its high reactivity and effectiveness in capturing CO2 and managing reject brine. In this study, parametric sensitivity analysis has been carried out to optimize the operating conditions and thereby maximize CO2 capture and ions removal from high-salinity brines. Response surface methodology (RSM) analysis using the central composite design (CCD) approach was implemented to statistically determine the impact of important operating conditions, including KOH concentration (30–110 g/l), CO2 gas flow rate (400–1600 ml/min), gauge pressure (1–3 barg), and temperature (10–50 °C) on key response process output variables, such as CO2 uptake and ions reduction. The importance of these parameters and their interactions were confirmed by employing analysis of variance (ANOVA) approach at a confidence level of 95% (p < 0.05). These analyses demonstrated that under the optimized conditions of a temperature of 10 °C, gauge pressure of 2.1 barg, CO2 gas flow rate of 848.5 ml/min, KOH concentration of 110 g/l, and an inert mixing particle volume fraction of 15%, a maximum CO2 uptake value of 0.58 g/g KOH, maximum sodium (Na+) removal of 44.1%, chloride (Cl−) removal of 40.1%, calcium (Ca2+) removal of 100%, and magnesium (Mg2+) removal of 99.8% were achieved. The characterization of the collected solid products at optimum conditions revealed the production of valuable and useful products, particularly sodium and potassium bicarbonates, in addition to KCl.

Study on atomization mechanism in spray coating of organic paint mixed with high-pressure carbon dioxide as a diluting solvent

The atomization phenomenon in spray coating of organic paint mixed with high-pressure carbon dioxide as a diluting solvent was investigated. Industrial organic paint for automotive body coating was used without any diluting organic solvent. Under high-pressure conditions, CO2 was continuously mixed with the organic paint to reduce its viscosity to spray. The atomization phenomenon was investigated regarding the effects of high-pressure spraying and CO2 vaporization from droplets. The experimental conditions were varied such as the temperature, pressure, GtP (gas to paint ratio: CO2 gas flow rate [g/min]/paint flow rate [g/min]). The average droplet sizes under the CO2 spray at the 150 mm from nozzle (actual spray distance for automotive manufacturing) were measured by using a laser droplet size analyzer. The average droplet size was strongly affected by the fluid conditions (temperature and GtP), and the sizes were varied from 12 to 113 µm under conditions of 20–60 °C and 8–16 MPa. The minimum size of average droplet was 12 µm at 60 °C, 14 MPa, and 0.5 of GtP. The moderate heating (40–60 °C), high pressure (12–16 MPa) and two-phase (CO2-saturated paint and high pressure CO2) fluid spraying under high GtP condition in the nozzle are important factors to produce small and homogeneous droplet.

High selective synthesis of CaCO3 superstructures via ultra-homoporous interfacial crystallizer

Precise regulation of biomimetic mineralization for highly ordered superstructures is one of the perpetual concerns in biomaterial synthesis and crystal engineering. Herein, we propose a ultra-homoporous interfacial crystallizer (UHIC) as a novel interfacial microdevice, which has realized high selective synthesis of CaCO3 superstructures during Gas–Liquid reactive crystallization process. This UHIC with ultra-uniform mass transfer porous channel and interfacial superhydrophilicity render the droplet ultra-homo nucleation site and coordinatively regulate the interfacial nucleation energy. The highly precise microchannel in UHIC can control the CO2 gas flow rate and sufficient interfacial Gas–Liquid diffusion of the CaCO3 pre-nucleation cluster (PNC). By coordinating the PNC diffusion, self-organization and nucleus growth, the proportion of synthesized CaCO3 crystals with spherical and polyhedral structures both increased to higher than 96.77 %, and the crystal size distribution was very uniform (minimum C.V. =11.7%). Fundamental theory of CaCO3 synthesis with UHIC as a desire interfacial reactive were then outlined, which can shed light on the high-selective synthesis of the microscale biomaterials.

Simulation of CO2 Gas Adsorption Process Flow at Cyclone Gas Outlet in Palm Oil Mills Using Computation Fluid Dynamic Simulation

Cyclone separator is equipment used to control emissions from gas flow in industrial processes. The principle of removing particulates from the gas flow in this tool is to use the centrifugal force. The centrifugal force generated from the rotating flow will make dust particles wasted into the cyclone wall where the dust will then fall into the hopper. Adsorption is a series of processes for the accumulation of a substance (adsorbate) on the surface of another substance (adsorbent). Adsorption can occur because of the energy on the surface and the attraction force on the surface. This study aims to obtain a good CO2 adsorption efficiency from modifying the cyclone separator using an adsorption column, analyzing the CO2 gas adsorption process produced from the biomass system at the utility unit boiler station at the Palm Oil Mill (PMO) using a modified cyclone. This simulation was carried out using the Autodesk Inventor Professional 2017 (Student Version) application for the descripction of the tool as a preprocessor and Ansys 2019 R3 (Student Version) applications as a processor and post processor. The variations that were applied included the adsorption column bed height of 3100 mm and 4650 mm, respectively, CO2 gas flow rates of 10, 12.5, 15, 17.5, 20, 22.5 dan 25 m/s and mass loading 0,001 kg/s. The results obtained in the most optimal modification of the cyclone separator are at a bed height of 3100 mm with the highest adsorption percentage 93.437%, the highest flow 91.974% with a pressure drop of 1000 Pa.

Characteristics and Safety of CO2 for the Fire Prevention Technology with Gob-Side Entry Retaining in Goaf.

The mining technology of gob-side entry retaining without a coal pillar is gradually becoming a mature and increasingly important mining technology. As it maintains the roadway near goaf, the air leakage should be greater than a U-type ventilation system in goaf, so it is prone to cause coal spontaneous combustion problems. CO2 is an inert gas, and it is usually used to prevent spontaneous combustion and extinguish coal fire. However, there is a lack of research on characteristics and safety of CO2 for the mining technology of gob-side entry retaining without the coal pillar. In this paper, the indexes of influencing factors were proposed on gas, pipelines, and mining technical parameters. Using a three-dimensional physical model of coal stope, the gas migration law of CO2, the relationship between gas injection rate and the oxidation zone area, and the safety of the CO2 inerting technology were analyzed. The results indicate that the O2 concentration is diluted between the working face and the injection port, especially in the air intake side. Furthermore, the CO2 injection rate is an important parameter to the fire prevention and extinguishing technology. When the gas injection rate ranges from 240 to 720 m3/h, the oxidation zone area varies from 7380 to 14 760 m2, and the gas injection rate grows exponentially with the area of the oxidation zone. Moreover, the redundant CO2 gas flows to the retaining roadway, and it reduces the O2 concentration, resulting in asphyxia accidents of miners. The research results are helpful to balance the relationship between inert gas injection and production safety and provide guidance for the practical application of the inert gas fire prevention technology.