Waste Gas Flow Rate Research Articles

Recovery and utilisation of waste heat for sponge iron process through combined preheating and power generation

This paper deals with an option accounted for total waste gas heat recovered through combined preheating as well as power generation of feed material, kiln air, as well as slinger coal when it reaches 250 °C from 994 °C. The heat recovery is obtained through GCC Profile is plotted using HINT software. The power produced is 2.757 MW with an optimal condition having a temperature of 280 °C saturated, 600 °C superheated, as well as superheated pressure of 350 bar. The heat required around the superheater, boiler and preheater is 5066.9 kW, 12,669.93 kW and 6873.6 kW. The air requirement for this option is 52.588 t/h after iteration. Also, the iterative waste gas flow rate is 22.31 kg/s. Three new heat exchangers are required to achieve possible heat recovery by designing HEN through Pinch Analysis. The water requirement around EC is 14.88 t/h and 7.8 t/h as in the case of actual and modified HEN. The calculated pressure drops of different ducts having lengths 25 m and pressure 0.034 atm, 80 and 105 m are obtained pressure as 0.034, 0.12 and 0.16 atm. 3 FD fans are required for maintenance of required pressures in the duct. The TAC is INR 8068.8/y; payback period is 2.62 y.

Assessment of multi-air emissions: Case of particulate matter (dust), SO2, NOx and CO2 from iron and steel industry of China

Industrial activities are generally energy and air emissions intensive, requiring bulky inputs of raw materials and fossil fuels and emitting huge waste gases including particulate matter (PM, or dust), sulphur dioxide (SO2), nitrogen oxides (NOx), carbon dioxide (CO2), and other substances, which are severely damaging the environment. Many studies have been carried out on the quantification of the concentrations of these air emissions. Although there are studies published on the co-effect of multi-air emissions, a more fair and comprehensive method for assessing the environmental impact of multi-air emissions is still lacking, which can simultaneously consider the flow rate of waste gases, the availability of emitting sources and the concentrations of all emission substances. In this work, a Total Environmental Impact Score (TEIS) approach is proposed to assess the environmental impact of the main industrial processes of an integrated iron and steel site located in the northeast of China. Besides the concentration of each air emission substance, this TEIS approach also combines the flow rate of waste gases and the availability of emitting sources. It is shown that the processes in descending order by the values of TEIS are sintering, ironmaking, steelmaking, thermal power, steel rolling, and coking, with the values of 17.57, 16.68, 10.86, 10.43, 9.60 and 9.27, respectively. In addition, a sensitivity analysis was conducted, indicating that the TEIS order is almost the same with the variation of 10% in the permissible CO2 concentration limit and the weight of each air emission substance. The effects of emitting source availability and waste gas flow rate on the TEIS cannot be neglected in the environmental impact assessment.

Effects of arc rotation speed on BTX decomposition by atmospheric pressure plasma

This study was conducted to investigate the decomposition of volatile organic compounds in air by the rotating arc plasma system. The rotating arc plasma decomposed benzene, toluene, and m-xylene (BTX) gases diluted in air. The effects of the gas flow rate and arc rotation speed on conversion rate and energy efficiency were evaluated by high speed images and Fourier transform infrared spectroscopy. Perfect conversions of toluene and m-xylene into environmentally benign species were achieved at the lowest waste gas flow rate of 20L/min, while the conversion rate of benzene was 79% under the same operating conditions due to the highest chemical bond strength of benzene among BTX. Although the conversion rate decreased with increasing the gas flow rate, the energy efficiency had an optimal gas flow rate, which influenced arc rotation speed. In addition, the oxidation rates of BTX were examined based on analysis of carbon oxides generated under different operating conditions.

Decomposition of Nitrogen Trifluoride Using Low Power Arc Plasma

The low power arc plasma is characterized by extremely high enthalpy and temperature and it is easy to generate and control, and thus thermal decomposition process based on the plasma torch is receiving a great attention for decomposing non-degradable greenhouse gases. In order to elevate the economic feasibility, the effects of input power, waste gas flow rate and additive gases on the destruction and removal efficiency (DRE) of NF3 are examined. Specific energy density (SED) deceases as the flow rate increases, and accordingly, the DRE is reduced. The DRE is basically determined by the specific energy density. The highest DRE of NF3 was 97% for the waste gas flow rate of 100 L/min at a low input power level of 2 kW with the help of hydrogen additional gas. The inlet and outlet concentration of NF3 was analyzed using Fourier transform infrared spectroscopy (FT-IR) for DRE of NF3 evaluation. As a result, large amount of NF3 can be efficiently decomposed by low power arc plasma systems.

아크 플라즈마를 이용한 과불화합물 처리공정에서 반응가스에 의한 효과

화학적으로 안정한 과불화합물을 처리하기 위해서는 많은 양의 에너지를 필요로 한다. 이러한 단점을 극복하기 위해서 저전력 아크 플라즈마 시스템을 개발하였다. 분해대상은 <TEX>$CF_4$</TEX>, <TEX>$SF_6$</TEX>, <TEX>$NF_3$</TEX>가 플라즈마 토치로 직접 주입되었으며, 아크 플라즈마 토치의 열효율을 측정하여 실출력을 계산하였다. 실출력과 폐기체 유량 변화 그리고 추가적인 반응가스에 의한 분해효율을 확인하였다. 또한 열역학적 평형조성 분석을 수행하여 실험 결과와 비교하였다. 토치의 열효율은 60~66%의 결과를 보였으며 폐가스 유량이 증가함에 따라 분해효율이 감소하였고 입력전력이 늘어남에 따라 분해효율이 상승되었다. 추가적인 반응 가스가 없이 <TEX>$CF_4$</TEX>, <TEX>$SF_6$</TEX>, <TEX>$NF_3$</TEX>의 분해효율은 입력전력이 3 kW, 폐가스 유량이 70 L/min인 조건에서 각각 4, 15, 90%를 보였다. 반응가스로 산소와 수소를 이용하여 분해효율을 급격하게 증가시킬 수 있었으며, 실험 결과 산소보다 수소를 사용하였을 경우가 분해효율 상승효과와 부산물 제어에 효과적인 것을 알 수 있었다. 수소의 경우, 발생되는 부산물은 불화수소산이었으며 이는 일반적인 습식 스크러버를 이용하여 처리가 용이한 물질이다. 수소를 이용한 화학반응에서 입력전력이 3 kW, 폐가스유량이 100 L/min인 조건에서 <TEX>$CF_4$</TEX>가 25%, <TEX>$SF_6$</TEX>가 39%, <TEX>$NF_3$</TEX>가 99%의 분해효율을 각각 나타냈다. The treatment of chemically stable perflourocompounds (PFCs) requires a large amount of energy. An energy efficient arc plasma system has been developed to overcome such disadvantage. <TEX>$CF_4$</TEX>, <TEX>$SF_6$</TEX> and <TEX>$NF_3$</TEX> were injected into the plasma torch directly, and net plasma power was estimated from the measurement of thermal efficiency of the system. Effects of net plasma power, waste gas flow rate and additive gases on the destruction and removal efficiency (DRE) of PFCs were examined. The calculation of thermodynamic equilibrium composition was also conducted to compare with experimental results. The average thermal efficiency was ranged from 60 to 66% with increasing waste gas flow rate, while DRE of PFCs was decreased with increasing gas flow rate. On the other hand, DRE of each PFCs was increased with the increasing input power. Maximum DREs of <TEX>$CF_4$</TEX>, <TEX>$SF_6$</TEX> and <TEX>$NF_3$</TEX> were 4%, 15% and 90%, respectively, without reaction gas at the fixed input power and waste gas flow rate of 3 kW and 70 L/min. A rapid increase of DRE was found using hydrogen or oxygen additional gases. Hydrogen was more effective than oxygen to decompose PFCs and to control by-products. The major by-product in the arc plasma process with hydrogen was hydrofluoric acid that is easy to be removed by a wet scrubber. DREs of <TEX>$CF_4$</TEX>, <TEX>$SF_6$</TEX> and <TEX>$NF_3$</TEX> were 25%, 39% and 99%, respectively, using hydrogen additional gas at the waste gas flow rate of 100 L/min and the input power of 3 kW.

UJI KINERJA BIODIESEL DARI MINYAK BIJI KARET

&lt;div class="WordSection1"&gt;&lt;p&gt;&lt;strong&gt;Abstract: &lt;/strong&gt;&lt;em&gt;The increasing of national biodiesel-demand is not balanced with national production. Two of the reasons are using edible oil as feedstock and high production cost.&lt;/em&gt; &lt;em&gt;Seventy percents of production cost comes from raw materials.&lt;/em&gt; &lt;em&gt;Exploration of new crops and unexploited oil crops is needed to develop. We could use low-valued feed stocks such as unrefined vegetable oil, waste frying oil, or side product from vegetable oil hydrolysis, the fatty acids. Rubber seed is a potential feedstock for biodiesel in Indonesia, because it is one of the greatest producers in the world. Besides, rubber seed has high proportion of oil and has not been used optimally yet. By using a proper pre-treatment, we could produce high quality biodiesel. The aim of this third-year research is to produce biodiesel in the optimum condition, and analysed it with Engine Test Bed. The optimum conditions are: acid pre-treatment (using H&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt; on 2.5% v/v as catalyst on the ratio of methanol to oil is 6:1, 60 &lt;sup&gt;o&lt;/sup&gt;C), and the second step, alkaline (KOH) catalysed trans-esterification (which was processed in 1 hour, 2% catalyst, 50&lt;sup&gt;o&lt;/sup&gt;C, on the ratio of methanol to oil is 6:1). Biodiesel was refined by settling, washing and adsorption. Based on previous research, we concluded that biodiesel from rubber seed oil with acid pre-treatment has lower carbon residue and higher flash point as the advantages. So, it was analyzed in an Engine Test Bed on this research. Biodiesel resulted better performance for B10 than petroleum diesel-fuel in lower rotation (&amp;lt; 2000 rpm), lower fuel-consumption and lower waste-gas flow rate. &lt;/em&gt;&lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Keywords: &lt;/em&gt;&lt;/strong&gt;&lt;em&gt;acid pre-treatment, biodiesel, Engine Test Bed, fatty acids, rubber seed oil&lt;/em&gt;&lt;/p&gt;&lt;/div&gt;&lt;strong&gt;&lt;br clear="all" /&gt;&lt;/strong&gt;

Characterization of the start-up behavior and steady-state performance of biotrickling filter removing low concentration toluene waste gas

A biotrickling filter packed with the regular ceramic spheres was designed and fabricated to purify the low toluene-concentration waste gas. Particular attention was made to the study of the start-up behavior of the biotrickling filter. Moreover, the steady performances were investigated to establish the experimental correlation between the operation factors and removal efficiency. It was found that the start-up process of the biotrickling filter exhibited three stages including the biofilm formation, biofilm development, and biofilm stabilization. The OD600 nm of the circulated liquid, gas pressure drop, elimination capacity, and temperature rise maintained at a rather low level in the biofilm formation stage, then increased rapidly in the biofilm development stage, and finally reached a stable value in the biofilm stabilization stage. It was also found that the removal efficiency of the biotrickling filter in the stable period decreased with increase in the waste gas flow rate, circulated liquid flow rate, and diameter of the ceramic sphere. More interestingly, it was revealed the operation modes have a significant influence on the removal efficiency of the biotrickling filter, and the microorganism show a high activity under the operating temperature ranging from 30°C to 40°C. The experimental correlations for describing the effect of operation factors on the removal efficiency of the biotrickling filters under both the co-current and counter-current operation modes were obtained. The correlation results are in good agreement with the experimental data.

A comparative study of air and nitrogen thermal plasmas for PFCs decomposition

Air and nitrogen thermal plasmas were generated from a plasma torch with hollow electrodes to abate CF4 which is a serious non-degradable greenhouse gas exhausted from the semiconductor manufacturing process. Numerical analysis and experimental demonstration have been carried out to compare effects of plasma forming gas on the decomposition process at the same electric input power of 60kW and waste gas flow rate of 200L/min. Higher temperature and longer residence time were expected in nitrogen thermal plasma than air thermal plasma, because relatively low flow rate of nitrogen plasma gas is required at fixed input power compared with air plasma gas. Although small quantity of NF3 was produced in nitrogen thermal plasma process with hydrogen reactant gas, high destruction and removal efficiency of 99.6% was achievable along with suppression of unwanted NOx generation.

Ladle Heating Procedure and Its Influence on the MgO–C-Oxidation

The efficiency of ladle heating can be substantially improved by preheating the combustion air using waste gas, oxygen enriching of the air, or changing the air ratio. These actions lead to an increase of the combustion temperature and a decrease of the waste gas volume rate. Hence the knowledge of the flow conditions in the ladle is of decisive importance for further reduction of the waste gas flow rate. The commercial CFD-code (Computational Fluid Dynamic) Fluent 6.3 was used to model the flow conditions in the ladle. The commercial thermodynamic software FactSage 5.3 was used to model the chemical processes such as combustion temperature, chemical composition of the waste gas, and in special the NO x production during natural gas combustion. For the calculation of the temperature distribution in the ladle lining, the flow model was coupled with a FDM (Finite Difference Method)-based thermal ladle model. The change of the combustion temperature and waste gas composition affects significantly the surface of the MgO–C-refractory lining. The oxidation of MgO–C containing 12 wt% carbon was investigated at various temperatures (1500 to 1600°C) in air atmosphere with and without air flow.

Application of Calcined Layered Double Hydroxides as Catalysts for Abatement of N2O Emissions

The results of catalytic decomposition of N2O over mixed oxide catalysts obtained by calcination of layered double hydroxides (LDHs) are summarized. Mixed oxides were prepared by thermal treatment (500 °C) of coprecipitated LDH precursors with general chemical composition of MII1-xMIIIx(OH)2(CO3)x/2·yH2O, where MII was Ni, Co, Cu and/or Mg, MIII was Mn, Fe and/or Al, and the MII/MIII molar ratio was adjusted to 2. The influence of chemical composition of the MII-MIII mixed oxide catalysts on their activity and stability in N2O decomposition was examined. The highest N2O conversion was reached over Ni-Al (4:2) and Co-Mn-Al (4:1:1) catalysts. Their suitability for practical application was proved in simulated process stream in the presence of O2, NO, NO2 and H2O. It was found that N2O conversion decreased with increasing amount of oxygen in the feed. The presence of NO in the feed caused a slight decrease in N2O conversion. A strong decrease in the reaction rate was observed over the Ni-Al catalyst in the presence of NO2 while no N2O conversion decrease was observed over the Co-Mn-Al catalyst. Water vapor inhibited the N2O decomposition over all tested catalysts. The obtained kinetic data for N2O decomposition in a simulated process stream over the Co-Mn-Al catalyst were used for a preliminary reactor design. The packed bed volume necessary for N2O emission abatement in a HNO3 production plant was calculated as 35 m3 for waste gas flow rate of 30 000 m3 h-1.

Dynamic model for on-line observation of the current process state during RH degassing

Based on the principles of thermodynamics and reaction kinetics, a dynamic model for the vacuum circulation (RH) process was developed. It comprises decarburisation, oxygen removal, dehydrogenation, denitrogenation and the course of steel temperature. The process model was validated by comparison of simulation results with measured process data from the RH/1 plant of Voest Alpine Stahl Linz (VASL). At this plant, it is used for on-line observation of the contents of carbon, oxygen, hydrogen and nitrogen as well as the steel temperature. Based on cyclically measured values of vessel pressure, lift gas flow rate as well as waste gas flow rate and composition, the current heat status is calculated reliably. The accuracy of the carbon balance with measured waste gas values was improved remarkably by a model-based correction calculation. The on-line process observation system provides the operator with valuable information on the progress of vacuum treatment.

Self-Scrubbing of Waste Gas Containing Dioctyl Phthalate

ABSTRACT This paper proposes using liquid dioctyl phthalate (DOP) as a scrubbing agent to reduce emissions and recycle waste DOP back to the process. Gas chroma-tography (G C) was employed to determine the DOP content in the waste gas. The effects of waste gas and scrubbing agent temperatures and the waste gas flow rate o n the removal of DOP from the waste gas were investigated. Rather good DOP removal efficiency was obtained. The relationship between the height of transfer unit (Ht) of the packed scrubbing tower and operating conditions, derived on the basis of particulate transport and impaction theories, can be used to design the packed scrubbing tower.