Hydrogen Chloride Emission Research Articles

Emissions of SO2, NOx, CO2, and HCl from Co-firing of coals with raw and torrefied biomass fuels

This work examined acid gas emissions of sulfur dioxide, nitrogen oxide, carbon dioxide, and hydrogen chloride from co-firing biomass (corn straw and rice husk) with either a high-sulfur bituminous coal or a low-sulfur sub-bituminous coal. Pulverized neat coals, neat biomass, either raw or torrefied, and 50–50wt% blends thereof were introduced to a laboratory-scale electrically-heated drop-tube furnace (DTF), operated at a gas temperature of 1350K, and experienced high heating rates. Emissions from the combustion of the fuels in air were measured at the furnace effluent. Coal particles were in the range of 75–90µm and biomass particles in the range of 90–150 µm. Results revealed that blending of both coals with raw and torrefied biomass drastically reduced the coal’s SO2 and NOx emission yields to values that were below those predicted by linear interpolation of the corresponding emission yields of the two neat fuels. The SO2 emission yields from torrefied biomass were lower than those of their raw biomass precursors due to their lower sulfur contents. Similarly to the emission yields, the SO2 emission factors (based on the energy content of each sample) from the blends of coal with torrefied biomass were also lower than the blends of coal with raw biomass. NOx emission yields from neat torrefied biomass were mildly higher than those from raw biomass, as the latter had higher nitrogen content per unit mass. There was no discernible trend in NOx emissions from the blends based on their nitrogen contents. HCl emission from torrefied corn straw was lower than that from its raw precursor, as the former had a lower chlorine content. The HCl emission yields from the blends of corn straw with coal were much higher than those from neat coal combustion. Finally, the HCl emission yield from blends of the high-sulfur coal with corn straw were higher than those from the blends of the same biomass with the low-sulfur coal.

Poly(vinyl chloride) and its fire properties

SummaryThis work provides an up‐to‐date review of the fire properties of poly(vinyl chloride) (PVC) materials, both rigid (unplasticized) and flexible (plasticized). The fire properties addressed include ignitability, ease of extinction (oxygen index), flame spread (small scale and intermediate scale), heat release, smoke obscuration, smoke toxicity, hydrogen chloride emission and decay, and performance in real‐scale fires.This comprehensive review includes a wide selection of references and tables illustrating the properties of PVC materials in comparison with those of other polymeric materials, including, in many instances, wood materials. The work puts these fire properties in perspective, showing that the heat release rate (the key fire property) of rigid PVC (and that of properly flame‐retarded flexible PVC) are among the lower values found for combustible materials. This work also shows that the smoke toxicity and smoke obscuration resulting from burning PVC materials in real‐scale fires is in the same range as those of other materials.

Hydrogen chloride emissions from combustion of raw and torrefied biomass

Elevated emissions of hydrogen chloride (HCl) from combustion of biomass in utility boilers is a major issue as it can cause corrosion and, in combination with the high alkali content often encountered in these fuels, it can also deposit molten alkali chloride salts on the boiler’s water tubes. Such deposition can impede heat transfer and cause further corrosion. This work torrefied and then burned herbaceous biomass (corn straw) as well as crop-derived biomass (olive residue and corn-based Distillers Dried Grains with Solubles, DDGS), all pulverized in the size range of 75–150µm. It monitored the HCl emissions from torrefaction of biomass and, subsequently, the comparative HCl emissions from combustion of both raw and torrefied biomass. Results showed that during torrefaction most of the chlorine of biomass was released in the gas phase, predominately as HCl. Consequentially, combustion of torrefied biomass, which contained less chlorine than raw biomass, generated significantly lower HCl emissions than raw biomass, particularly so for biomass of low alkali content. This observation complements previous findings in this laboratory that torrefied biomass also generated lower SO2 emissions than raw biomass, albeit by a smaller factor. Both of these findings enhance the appeal of torrefied biomass as a substitute fuel in utility boilers.

Morphological characteristics of polyvinyl chloride (PVC) dechlorination during pyrolysis process: Influence of PVC content and heating rate

In this research morphological techniques were used to characterize dechlorination process of PVC when it is in the mixed waste plastics and the two important factors influencing this process, namely, the proportion of PVC in the mixed plastics and heating rate adopted in the pyrolysis process were investigated. During the pyrolysis process for the mixed plastics containing PVC, the morphologic characteristics describing PVC dechlorination behaviors were obtained with help of a high-speed infrared camera and image processing tools. At the same time emission of hydrogen chloride (HCl) was detected to find out the start and termination of HCl release. The PVC contents in the mixed plastics varied from 0% to 12% in mass and the heating rate for PVC was changed from 10 to 60°C/min. The morphologic parameters including “bubble ratio” (BR) and “pixel area” (PA) were found to have obvious features matching with PVC dechlorination process therefore can be used to characterize dechlorination of PVC alone and in the mixed plastics. It has been also found that shape of HCl emission curve is independent of PVC proportions in the mixed plastics, but shifts to right side with elevated heating rate; and all of which can be quantitatively reflected in morphologic parameters vs. temperature curves.

Use of MRF residue as alternative fuel in cement production

Single-stream recycling has helped divert millions of metric tons of waste from landfills in the U.S., where recycling rates for municipal solid waste are currently over 30%. However, material recovery facilities (MRFs) that sort the municipal recycled streams do not recover 100% of the incoming material. Consequently, they landfill between 5% and 15% of total processed material as residue. This residue is primarily composed of high-energy-content non-recycled plastics and fiber. One possible end-of-life solution for these energy-dense materials is to process the residue into Solid Recovered Fuel (SRF) that can be used as an alternative energy resource capable of replacing or supplementing fuel resources such as coal, natural gas, petroleum coke, or biomass in many industrial and power production processes. This report addresses the energetic and environmental benefits and trade-offs of converting non-recycled post-consumer plastics and fiber derived from MRF residue streams into SRF for use in a cement kiln.An experimental test burn of 118Mg of SRF in the precalciner portion of the cement kiln was conducted. The SRF was a blend of 60% MRF residue and 40% post-industrial waste products producing an estimated 60% plastic and 40% fibrous material mixture. The SRF was fed into the kiln at 0.9Mg/h for 24h and then 1.8Mg/h for the following 48h. The emissions data recorded in the experimental test burn were used to perform the life-cycle analysis portion of this study.The analysis included the following steps: transportation, landfill, processing and fuel combustion at the cement kiln. The energy use and emissions at each step is tracked for the two cases: (1) The Reference Case, where MRF residue is disposed of in a landfill and the cement kiln uses coal as its fuel source, and (2) The SRF Case, in which MRF residue is processed into SRF and used to offset some portion of coal use at the cement kiln.The experimental test burn and accompanying analysis indicate that using MRF residue to produce SRF for use in cement kilns is likely an advantageous alternative to disposal of the residue in landfills. The use of SRF can offset fossil fuel use, reduce CO2 emissions, and divert energy-dense materials away from landfills. For this test-case, the use of SRF offset between 7700 and 8700Mg of coal use, reduced CO2 emissions by at least 1.4%, and diverted over 7950Mg of energy-dense materials away from landfills. In addition, emissions were reduced by at least 19% for SO2, while NOX emissions increased by between 16% and 24%. Changes in emissions of particulate matter, mercury, hydrogen chloride, and total-hydrocarbons were all less than plus or minus 2.2%, however these emissions were not measured at the cement kiln. Co-location of MRFs, SRF production facilities, and landfills can increase the benefits of SRF use even further by reducing transportation requirements.

Ash behaviour and emission formation in a small-scale reciprocating-grate combustion reactor operated with wood chips, reed canary grass and barley straw

The emissions and ash behaviour during combustion of wood chips, or co-combustion of two solid agricultural fuels (reed canary grass and barley straw) with wood chips, were studied. In addition, the sensitivity of the results towards different air-staging conditions was investigated using pure wood chips. The experiments were carried out in a 40-kW combustion reactor equipped with a reciprocating-grate burner. The addition of the reed canary grass to the wood chips increased only slightly the emission of fine particles (PM1), nitrogen oxides (NOX) and sulphur dioxide (SO2); while carbon monoxide (CO), hydrogen chloride (HCl), organic carbon (OC), elemental carbon (EC) and the geometric diameter (GMD) of the particles either decreased or remained unchanged. However, the number of particles emitted increased 2-fold in the reed canary grass combustion compared to the pure wood chips. In contrast, the addition of straw to wood chips substantially increased the emissions of PM1, CO, EC, SO2 and HCl. The straw-originating particles were mostly crystalline KCl, and their number emission was clearly reduced, but their size was larger compared to the case with pure wood chips. The distribution of the combustion air had only a very minor influence on the release of the major ash species, whereas the effect was significant for the release of specific trace metals and the products of incomplete combustion. Finally, the partitioning of ash-forming elements with various fuels was evaluated based on chemical analyses of the fuel, bottom ash and fine fly ash fractions.

Simulation of Rocket Exhaust Clouds at the Centro de Lançamento de Alcântara Using the WRF-CMAQ Modeling System

In this work we report numerical simulations of the contaminant dispersion and photochemical reactions of rocket exhaust clouds at the Centro de Lancamento de Alcântara (CLA) using the CMAQ modeling system. The simulations of carbon monoxide (CO), hydrogen chloride (HCl) and alumina (solid Al2O3) pollutants emission represent an effort in the construction of a computational tool in order to simulate normal and/or accidental events during rocket launches, making possible to predict the contaminant concentrations in accordance with emergency plans and pre and post-launchings for environmental management. The carbon monoxide and the alumina concentrations showed the formation of the ground and contrail cloud. The results also showed that hydrogen chloride concentrations would be harmful to human health, demonstrating the importance of assessing the impact of rocket launches in the environment and human health.

A comparative assessment of waste incinerators in the UK

The uptake in Europe of Energy from Waste (EfW) incinerator plants has increased rapidly in recent years. In the UK, 25 municipal waste incinerators with energy recovery are now in operation; however, their waste supply chains and business practices vary significantly. With over a hundred more plant developments being considered it is important to establish best business practices for ensuring efficient environmental and operational performance. By reviewing the 25 plants we identify four suitable case study plants to compare technologies (moving grate, fluidised bed and rotary kiln), plant economics and operations. Using data collected from annual reports and through interviews and site visits we provide recommendations for improving the supply chain for waste incinerators and highlight the current issues and challenges faced by the industry. We find that plants using moving grate have a high availability of 87–92%. However, compared to the fluidised bed and rotary kiln, quantities of bottom ash and emissions of hydrogen chloride and carbon monoxide are high. The uptake of integrated recycling practices, combined heat and power, and post incineration non-ferrous metal collections needs to be increased among EfW incinerators in the UK. We conclude that one of the major difficulties encountered by waste facilities is the appropriate selection of technology, capacity, site, waste suppliers and heat consumers. This study will be of particular value to EfW plant developers, government authorities and researchers working within the sector of waste management.

Heat-emission analysis of small combustion equipments for biomass

The article addresses the urgent questions regarding the use of biomass as a fuel for combustion equipment of the heat output up to 25 kW. The article is based on the determined elemental analyses of six samples of fuel taken both from the wood mass and herbaceous biomass. These samples underwent the stoichiometric analysis of fuels. After the stoichiometric analysis the heat-emission characteristics were determined on two combustion equipments. The results of carried out elemental and stoichiometric analyses indicate higher values of nitrogen, sulphur and chlorine concentration in herbaceous biomass from agriculture compared to the analyzed wood mass. The selection of combustion equipment is particularly influenced by increased contents of sulphur and chlorine (corrosive behaviour). The net calorific value of the analyzed samples taken from the wood mass is higher than of samples taken from the herbaceous biomass. The net calorific value of fuels from herbaceous biomass is reduced due to a higher content of ashes in the fuel. The results of thermal-emission analyses show higher values of nitrogen oxides, sulphur and chlorine concentrations in the herbaceous biomass compared to the analyzed wood mass. The emission concentrations of carbon monoxide for wood fuels and herbaceous biomass also depend on the type of combustion equipment and setting of combustion air volume. The increased emissions of hydrogen chloride generated by various combustion equipments are primarily caused by the volume of combustion air and the amount of chlorine in the fuel itself. The higher the volume of combustion air brought into the combustion chamber is, the higher the emissions of hydrogen chloride are. Based on the analyses we can also draw a conclusion that the spaces of combustion equipment during combustion should be most burdened with the herbaceous biomass.

Application Study of AlCl<sub>3</sub>/Al Catalyst in Fridel-Crafts Acylation Reaction

The traditional AlCl3 catalyst was substituted by a new-type solid acidic catalyst AlCl3/Al for the synthetic reaction of Fridel-Craft acylation from benzene and benzoyl chloride to diphenyl ketone. It has been showed that the yield of diphenyl ketone rising from 55% to 66%, hydrogen chloride emissions decreasing by 70.8%, and the new one being an environmental friendly catalyst.

Life cycle assessment of a pulverized coal power plant with post-combustion capture, transport and storage of CO 2

In this study the methodology of life cycle assessment has been used to assess the environmental impacts of three pulverized coal fired electricity supply chains with and without carbon capture and storage (CCS) on a cradle to grave basis. The chain with CCS comprises post-combustion CO 2 capture with monoethanolamine, compression, transport by pipeline and storage in a geological reservoir. The two reference chains represent sub-critical and state-of-the-art ultra supercritical pulverized coal fired electricity generation. For the three chains we have constructed a detailed greenhouse gas (GHG) balance, and disclosed environmental trade-offs and co-benefits due to CO 2 capture, transport and storage. Results show that, due to CCS, the GHG emissions per kWh are reduced substantially to 243 g/kWh. This is a reduction of 78 and 71% compared to the sub-critical and state-of-the-art power plant, respectively. The removal of CO 2 is partially offset by increased GHG emissions in up- and downstream processes, to a small extent (0.7 g/kWh) caused by the CCS infrastructure. An environmental co-benefit is expected following from the deeper reduction of hydrogen fluoride and hydrogen chloride emissions. Most notable environmental trade-offs are the increase in human toxicity, ozone layer depletion and fresh water ecotoxicity potential for which the CCS chain is outperformed by both other chains. The state-of-the-art power plant without CCS also shows a better score for the eutrophication, acidification and photochemical oxidation potential despite the deeper reduction of SO x and NO x in the CCS power plant. These reductions are offset by increased emissions in the life cycle due to the energy penalty and a factor five increase in NH 3 emissions.

The effects of calcium hydroxide on hydrogen chloride emission characteristics during a simulated densified refuse-derived fuel combustion process

This study investigated the effects of different calcium hydroxide (Ca(OH) 2) addition methods on the potential for hydrogen chloride (HCl) formation in a simulated densified refuse-derived fuel (RDF-5) with single metal combustion system. These experiments were conducted at 850 °C with the Ca(OH) 2 spiked in the RDF-5 production or injection in the flue gas treatment system. The results indicated that the potential for HCl formation was decreased significantly by Ca(OH) 2 spiked in the RDF-5 production or injection in the flue gas treatment system. However, the Ca(OH) 2 injection method in the flue gas for HCl emission reduction was better than other method. According to the relationship between the HCl emission and amount of Ca(OH) 2 injected or spiked, it is interesting to find that when the Ca(OH) 2 injected or spiked ranged from 0% to 5%, the potential for HCl formation in the single metal combustion system decreases significantly with increasing Ca(OH) 2 injected or spiked ratio. A corresponding increase in the amount of CaCl 2 partitioned to the fly ash was observed. However, with the ratio of Ca(OH) 2 higher than 5%, the amount of HCl formation showed that no further significant variation occurred with increasing Ca(OH) 2 spiked ratio.

The airborne lava–seawater interaction plume at Kīlauea Volcano, Hawaiʻi

Lava flows into the sea at Kīlauea Volcano, Hawaiʻi, and generates an airborne gas and aerosol plume. Water (H 2O), hydrogen chloride (HCl), carbon dioxide (CO 2), nitrogen dioxide (NO 2) and sulphur dioxide (SO 2) gases were quantified in the plume in 2004–2005, using Open Path Fourier Transform infra-red Spectroscopy. The molar abundances of these species and thermodynamic modelling are used to discuss their generation. The range in molar HCl / H 2O confirms that HCl is generated when seawater is boiled dry and magnesium salts are hydrolysed (as proposed by [T.M. Gerlach, J.L. Krumhansl, R.O. Fournier, J. Kjargaard, Acid rain from the heating and evaporation of seawater by molten lava: a new volcanic hazard, EOS (Trans. Am. Geophys. Un.) 70 (1989) 1421–1422]), in contrast to models of Na-metasomatism. Airborne droplets of boiled seawater brine form nucleii for subsequent H 2O and HCl condensation, which acidifies the droplets and liberates CO 2 gas from bicarbonate and carbonate. NO 2 is derived from the thermal decomposition of nitrates in coastal seawater, which takes place as the lava heats droplets of boiled seawater brine to 350–400 °C. SO 2 is derived from the degassing of subaerial lava flows on the coastal plain. The calculated mass flux of HCl from a moderate-sized ocean entry significantly increases the total HCl emission at Kīlauea (including magmatic sources) and is comparable to industrial HCl emitters in the United States. For larger lava ocean entries, the flux of HCl will cause intense local environmental hazards, such as high localised HCl concentrations and acid rain.

Important Environment Challenges for the U.S. Paper Industry

Although, in recent years, other issues have tended to overshadow environmental concerns in the United States, pulp and paper companies continue to be faced with a large and still-increasing number of environmental regulations. Compliance with recently finalized water and air pollution regulations (the Cluster Rule) has already cost the industry several billion dollars. As a result of these rules, essentially all paper-grade kraft mills in the U.S. have converted to ECF bleaching. Compliance with regulations on dilute emissions of hazardous air pollutants (e. g. methanol) and expected rules on boiler emissions of particulates, mercury, and hydrogen chloride will also be costly and require complex compliance monitoring and record keeping systems.These regulatory compliance issues come at a time when the industry is having to respond to intensified pressure from stakeholders in the areas of forestry practices, recycling, and climate change. The AF & PA Sustainable Forestry Initiative and Standard continue to evolve and gain broad acceptance. The U. S. industry's goal of recovering 50% of used paper for recycling has proved challenging but it is a goal to which the industry remains committed. To address concerns about climate change, some companies have joined voluntary programs to reduce emissions and the forest products industry is considering an invitation from the U. S. government to enter into a voluntary, sector-wide climate change agreement.

00/02954 Global emissions of hydrogen chloride and chloromethane from coal combustion, incineration and industrial activities: reactive chlorine emissions inventory

00/02954 Global emissions of hydrogen chloride and chloromethane from coal combustion, incineration and industrial activities: reactive chlorine emissions inventory

Global emissions of hydrogen chloride and chloromethane from coal combustion, incineration and industrial activities: Reactive Chlorine Emissions Inventory

Much if not all of the chlorine present in fossil fuels is released into the atmosphere as hydrogen chloride (HCl) and chloromethane (CH3Cl, methyl chloride). The chlorine content of oil‐based fuels is so low that these sources can be neglected, but coal combustion provides significant releases. On the basis of national statistics for the quantity and quality of coal burned during 1990 in power and heat generation, industrial conversion and residential and commercial heating, coupled with information on the chlorine contents of coals, a global inventory of national HCl emissions from this source has been constructed. This was combined with an estimate of the national emissions of HCl from waste combustion (both large‐scale incineration and trash burning) which was based on an estimate of the global quantity released from this source expressed per head of population. Account was taken of reduced emissions where flue gases were processed, for example to remove sulphur dioxide. The HCl emitted in 1990, comprising 4.6 ± 4.3 Tg Cl from fossil fuel and 2 ± 1.9 Tg Cl from waste burning, was spatially distributed using available information on point sources such as power generation utilities and population density by default. Also associated with these combustion sources are chloromethane emissions, calculated to be 0.075 ± 0.07 Tg as Cl (equivalent) from fossil fuels and 0.032 ± 0.023 Tg Cl (equivalent) from waste combustion. These were distributed spatially exactly as the HCl emissions, and a further 0.007 Tg Cl in chloromethane from industrial process activity was distributed by point sources.

The influence of heavy metals on the formation of organics and HCl during incinerating of PVC-containing waste

The heavy metal, organic pollutants and HCl emissions from incineration pose a grave threat to human health. However, submicro metal particles and organics in gas phase are removed with difficulty by conventional air pollution control apparatus, and could be released into the atmosphere along with the flue gas. This research studied the formation of organics and HCl (hydrogen chloride) during incineration when the feedstock contained different amounts of PVC and heavy metals. The experiments were performed in a bubbling fluidized bed incinerator with two cyclones and scrubbers. Experimental results indicated that the greatest amount of organic compounds produced were aromatic compounds. The amount of organic compounds and HCl increased when the feedstock contained PVC (polyvinyl chloride), and decreased when the feedstock contained heavy metals.

Effect of Operating Conditions on HCl Emissions from Municipal Solid Waste Combustion in a Laboratory-Scale Fluidized Bed Incinerator

The effect of operating conditions on hydrogen chloride emissions were determined for municipal solid waste combustion in a laboratory-scale fluidized bed incinerator. Experiments were performed according to a statistical experimental design, to examine the effect of bed temperature, limestone feeding rate, excess air, and fuel moisture. The amount of HCl emitted was found to be significantly decreased by limestone addition and slightly increased by bed temperature and waste moisture growth. Capture efficiencies as high as 55–70% without limestone, and 95% with a calcium to chlorine and sulphur ratio of 5.0 was obtained, despite the fact that CaCl2 is not thermochemically stable in the fluidized bed. A comparison with results from a corresponding chemical equilibrium analysis suggested that the high capture efficiency could be either (1) reactions with calcium containing aerosols and particles downstream of the hot reactor; or (2) high-temperature reactions involving complex liquid (or solid) solutions of more stable products. Key words: HCl emissions; municipal solid waste; incineration; fluidized bed; statistical design

Degradation of poly(vinyl chloride) in the presence of 9‐(2,3‐epoxypropane)carbazole studied by means of TGA/FTIR

AbstractBlends containing poly(vinyl chloride) and 9‐(2,3‐epoxypropane)carbazole in different weight ratios were subjected to investigations using thermogravimetric analysis coupled with Fourier transform infrared spectroscopy. The effect of additive on the polymer degradation process was studied. It was found that 9‐(2,3‐epoxypropane)carbazole causes an increase in the onset temperature of hydrogen chloride emission by about 20–25°C. Finally, the mechanisms of stabilization were proposed. © 1995 John Wiley & Sons, Inc.

Operating Parameters to Minimize Emissions During Rotary Kiln Emergency Safety Vent Openings

Certain designs of hazardous waste incinerator systems include emergency safety vents (ESVs). ESVs (also called dump stacks, vent stacks, emergency by-pass stacks, thermal relief valves, and pressure relief valves) are regarded as true emergency devices. Their purpose is to vent combustion gases directly from the combustion chambers to the atmosphere in the event of a failure of other system components. This is done for operator safety as well as to protect the incinerator and other downstream equipment from damage. ESVs are typically required for rotary kiln and hearth incinerators which process a portion of their waste load as bulk solids or contained liquids introduced continuously or in batch charges. Research has been performed at the U.S. EPA on a 73 kW (250,000 Btu/hr) rotary kiln incinerator simulator examining optimum settings of kiln operating parameters so as to minimize emissions during an ESV opening event. Experimental results are interpreted in the light of previous research results on transient "puffs." Mechanisms governing both the release of volatile matter during an ESV event and the subsequent pyrolysis and oxidation in the residual sorbent bed are identified. From a practical point of view, results indicate that alteration of operator-controllable kiln parameters during the onset of certain ESV opening events can have a significant effect on emissions of both organics and hydrogen chloride (HCl). A low air flow rate results in lower emissions of both organics and HCl. This hypothetical low air flow rate could possibly be equal to the flow rate induced by the natural draft coupled with air in-leakage. Rotational speed (RPM) appears to have slightly different effects on organics and HCl. Whereas emissions of HCl are minimized at a very low or non-existent RPM, emissions of organics exhibit a minimum at a low (but non-zero) RPM, with increasing emissions at both zero and high RPM. The use of a small afterburner to simulate an in-stack flare during an ESV event dramatically reduced organic emissions.