scholarly journals In situ measurements of O<sub>2</sub> and CO eq.  in cement kilns

2017 ◽  
Vol 6 (2) ◽  
pp. 327-330 ◽  
Author(s):  
Olga Driesner ◽  
Fred Gumprecht ◽  
Ulrich Guth
Keyword(s):  
Flue Gas ◽  
Oxygen Sensor ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Raw Material ◽  
Delayed Response ◽  
Plant Operator ◽  
In Situ Sensors ◽  
Cement Kilns

Abstract. The simultaneous in situ measurement of O2 and CO eq.  in cement kilns is a great challenge due to the high process temperatures and high dust load. The standard method for measurement for flue gas in cement kilns is extractive. Extractive measurements have a higher response time due to the flue gas conditioning including the length of heated extraction lines for electrochemical or optical analysis. This delayed response is not optimal for fast process control.A probe was developed for this purpose in which the in situ solid electrolyte oxygen sensor and an in situ CO eq.  mixed potential sensor are implemented. Due to the high temperatures, the probe is cooled by a water–coolant mixture. In order to prevent deposits of raw material forming and sintering on the probe, it rotates 90° in programmable intervals. In addition, an automated probe plunger pneumatically removes plugging at the probe flue gas entrance, also in programmable intervals. These self-cleaning functions allow the probe to continually stay in the process for combustion optimisation (low excess O2 and CO) and enable the plant operator to measure additional process-related gas components (NO, SO2, HCl etc.) and optimise the SNCR (selective non-catalytic reduction) for NOx reduction. Combustion air supply can be adapted very quickly due to the in situ sensors, which has been demonstrated by a CEMTEC® probe over years (Märker Cement Harburg, 2017).

scholarly journals In Situ DRIFTS Studies of NH3-SCR Mechanism over V2O5-CeO2/TiO2-ZrO2 Catalysts for Selective Catalytic Reduction of NOx

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1307 ◽  
Author(s):  
Yaping Zhang ◽  
Xiupeng Yue ◽  
Tianjiao Huang ◽  
Kai Shen ◽  
Bin Lu
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Oxygen Storage ◽  
In Situ Drifts ◽  
Nh3 Scr ◽  
Nh3 Adsorption ◽  
Reduction Of Nox ◽  
Zro2 Catalyst

TiO2-ZrO2 (Ti-Zr) carrier was prepared by a co-precipitation method and 1 wt. % V2O5 and 0.2 CeO2 (the Mole ratio of Ce to Ti-Zr) was impregnated to obtain the V2O5-CeO2/TiO2-ZrO2 catalyst for the selective catalytic reduction of NOx by NH3. The transient activity tests and the in situ DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) analyses were employed to explore the NH3-SCR (selective catalytic reduction) mechanism systematically, and by designing various conditions of single or mixing feeding gas and pre-treatment ways, a possible pathway of NOx reduction was proposed. It was found that NH3 exhibited a competitive advantage over NO in its adsorption on the catalyst surface, and could form an active intermediate substance of -NH2. More acid sites and intermediate reaction species (-NH2), at lower temperatures, significantly promoted the SCR activity of the V2O5-0.2CeO2/TiO2-ZrO2 catalyst. The presence of O2 could promote the conversion of NO to NO2, while NO2 was easier to reduce. The co-existence of NH3 and O2 resulted in the NH3 adsorption strength being lower, as compared to tests without O2, since O2 could occupy a part of the active site. Due to CeO2’s excellent oxygen storage-release capacity, NH3 adsorption was weakened, in comparison to the 1 wt. % V2O5-0.2CeO2/TiO2-ZrO2 catalyst. If NOx were to be pre-adsorbed in the catalyst, the formation of nitrate and nitro species would be difficult to desorb, which would greatly hinder the SCR reaction. All the findings concluded that NH3-SCR worked mainly through the Eley-Rideal (E-R) mechanism.

Effect of Cement Raw Material and Oxygen Concentration on SNCR Reaction

2018 ◽  
Vol 913 ◽  
pp. 969-975
Author(s):  
Ya Li Wang ◽  
Li Nan ◽  
Si Yu Peng ◽  
Yun Ning Zhang ◽  
Mei Na Chen ◽  
...  
Keyword(s):  
Oxygen Concentration ◽  
Flue Gas ◽  
Catalytic Reduction ◽  
Raw Materials ◽  
Raw Material ◽  
Cement Kiln ◽  
Gas Composition ◽  
High Concentration ◽  
Denitration Rate ◽  
Cement Raw Material

As the selective non-catalytic reduction denitration(SNCR denitration) was used in cement decomposition furnaces under the high concentration cement raw materials and complex flue gas composition , the denitration efficiency is poor and the reducing agent is largely consumed.In order to meet the more stricter requirements of environmental protection, there is an urgent need to improve the denitration efficiency of SNCR and reduce the escape of reducing agentsin order to prevent the unnecessary waste caused by excessive use of reducing agents and secondary atmospheric pollution.Therefore, studying the effect of cement raw materials and O2 concentration on SNCR process is very important. In this paper, the initial concentration of NO and the ammonium to nitrogen ration (CNH3/CNO) was 800ppm and 1.5, respectively. The effects of cement raw material and oxygen concentration on the reaction process of NH3+NO+O2 in the temperature range of 750°C -1100°C were investigated by means of denitration rate, in Situ DRIFTS analysis.The results demonstrate when O2 concentration was 5% and denitration temperature was 950°C, the deNOx rate reached a maximum of 89.64%, which due to O2 promoted NH3 and NO to react with O2 to produce N2 and H2O. However,under the effect of cement raw material, O2 can promote NH3 which was adsorbed on the surface of cement raw material to react with O2 and produce NO and H2O, and the reaction of oxidation of NH3 is dominant, therefore, the denitration reaction is inhibited. .When O2 concentration was 5% and temperature was 850°C, the deNOx rate reached a minimum value of -109.09%. the high concentration cement raw material and flue gas composition reduce the denitration efficiency of cement kiln.

Implementation of SCR Systems for Three Boilers at the TVA Paradise Fossil Site

2002 ◽  
Author(s):  
Donald Schreyer ◽  
Arnold Manaker ◽  
Scot Pritchard
Keyword(s):  
Flue Gas ◽  
Bituminous Coal ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Ammonia Slip ◽  
Catalyst Life ◽  
Fossil Site ◽  
Full Power ◽  
Nox Control ◽  
And Storage

In 1998, TVA undertook the implementation of Selective Catalytic Reduction systems at the Paradise Generating Station. The station has three fossil-fired cyclone boilers totaling 2515 Mw of power generation which have been online since the early 1960s for Paradise Units 1 and 2, and since 1970 for Unit 3. Design efforts started late 1998 with Paradise Unit 2, a 704 Mw cyclone-fired unit that went into operation for the May 2000 ozone season. This was followed by Paradise Unit 1, an identical 704 Mw unit that went into operation for the May 2001 ozone season. Paradise Unit 3, an 1107 Mw unit, is currently in manufacture and erection for placement into service for the 2003 ozone season. The Paradise Units 1 & 2 SCR modules are among the largest single modules in service for treating the entire flue gas path. The system design considered the operation of the boiler without overfire air NOx control, where the emission of NOx would be 688.5 g/GJ (1.6 lb/MMBtu) and with overfire air NOx emission of 370 g/GJ (0.86 lb/MMBtu). Paradise Units 1 & 2 are fitted with scrubbers and burn a high sulfur fuel. Paradise 3, not currently fitted with a scrubber, fires a blend of PRB and Utah bituminous coal. The SCR is configured with two modules. The SCR project guarantees are 90% NOx reduction, 2-ppm ammonia slip and a catalyst life of 20,000 hours. Each of the cyclone units retained their tubular air heaters. Each unit required the erection of either temporary or new ductwork from the air heater to the downstream equipment to allow the demolition of equipment that had been part of the gas path but is no longer in service. The old equipment had to be removed to permit the building of the SCRs. Each SCR unit is equipped with a full flow bypass and man-safe dampers. These man-safe dampers permitted the construction and maintenance of the SCR while the boiler was in operation. Paradise Unit 2’s SCR was fitted with steam soot blowers. Sonic horns were tested on a section of Unit 2 and based on the results, Paradise Unit 1 was fitted only with sonic horns for catalyst cleaning. The anhydrous ammonia unloading and storage facility is more than a mile from the ammonia vaporizers that are located at grade adjacent to their respective SCR unit. The monthly ammonia consumption under full power conditions for Paradise Units 1 & 2 and 90% NOx reduction is 1,703.3 m3 (450,000 gallons) per month with the overfire air system in service. This paper addresses the issues and decisions related to integration of the SCR systems and the experiences of manufacturing and erecting each of the SCR units.

Enhanced Selective Non-Catalytic Reduction (SNCR) for Refinery Applications: Pilot-Scale Test Data With a Hydrogen Promoter

2011 ◽  
Author(s):  
Larry Swanson ◽  
Wei Zhou ◽  
David Moyeda ◽  
Christopher Samuelson
Keyword(s):  
Flue Gas ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Pilot Scale ◽  
Gas Temperature ◽  
Wide Range ◽  
Lower Temperature Range ◽  
Scale Test ◽  
Lower Temperature ◽  
Pilot Scale Test

Selective non-catalytic reduction technology (SNCR) is an effective and economical method of reducing NOX emissions for a wide range of industrial combustion systems. It is widely known that the traditional SNCR temperature window is centered around 1,200 to 1,255 K [1]. However, for some applications, the flue gas temperatures in boilers, oxidizers, and heaters range from 950 to 1150 K. At these lower temperatures, injection of an amine reagent into flue gas no longer actively reduces NOX, but instead passes through the system and exits as ammonia slip. Earlier studies have shown that at lower temperatures, hydrogen and other promoters can be added to the system to shift the SNCR window to a lower temperature range, enhancing or promoting SNCR NOX reduction performance [2–5]. This extended abstract describes pilot-scale test results for an enhanced SNCR process (ESNCR) that uses hydrogen as the SNCR promoter. The impacts of flue gas temperature, hydrogen concentration, CO concentration, and SO2 concentration on ESNCR NOX reduction performance are presented.

RSCR® System to Reduce NOx Emissions From Boilers

2009 ◽  
Author(s):  
Richard F. Abrams ◽  
Robert Faia
Keyword(s):  
Selective Catalytic Reduction ◽  
Flue Gas ◽  
Heat Recovery ◽  
High Efficiency ◽  
Catalytic Reduction ◽  
Low Cost ◽  
Nox Reduction ◽  
Waste To Energy ◽  
Nox Emissions ◽  
Reaction Products

Babcock Power Environmental (BPE), a Babcock Power Inc. company, has developed a new, innovative, high-efficiency NOx reduction technology designed to greatly reduce the NOx emissions from waste to energy (WTE) boilers at relatively low cost. This “tail-end” system uses Selective Catalytic Reduction (SCR) to achieve the high reduction performance. Conventional SCR catalyst cannot be used in the traditional “high-dust” location, downstream of the economizer because constituents in the ash would poison the catalyst quickly, rendering it useless. Thus, the Regenerative Selective Catalytic Reduction (RSCR®) system is designed to operate at the end of the plant before the flue gas is discharged to the stack. The process utilizes a reactant (usually aqueous ammonia) to be added to the flue gas stream upstream of the RSCR to reduce NOx to harmless reaction products, N2 and H2O. The RSCR combines the efficient heat recovery, temperature control, reactant mixing, and catalyst into a single unit and provides the maximum NOx reduction and heat recovery practical. The paper will describe the overall predicted performance of a typical WTE boiler plant using this new technology. The paper will also provide actual operating data on the RSCR, which has been retrofitted to four biomass-fired units.

scholarly journals REDUCTION OF NOX CONCENTRATIONS IN BOILER FLUE GAS BY INJECTING SELECTIVE REAGENTS

2005 ◽  
Vol 13 (2) ◽  
pp. 91-96 ◽  
Author(s):  
Kestutis Buinevičius ◽  
Egidijus Puida
Keyword(s):  
Flue Gas ◽  
Catalytic Reduction ◽  
Nox Reduction ◽  
Boiler Furnace ◽  
Gas Cleaning ◽  
Operation Conditions ◽  
Cleaning Equipment ◽  
Primary Means ◽  
Reduction Of Nox ◽  
Nox Control

Present EU regulations promote search for efficient means of reducing environmental pollution caused by fuel‐burning equipment. Primary means of NOx reduction are of a limited efficiency. The aim of this study is investigation and development of Selective Non‐Catalytic Reduction (SNCR) for NOx Control. This method can be applied in the existing boilers that have no external flue gas cleaning equipment, and that is the main advantage of the method. Experimental investigation of the influence of various reagent solutions on NOx concentration was carried out in a stand simulating a boiler furnace. Reagents and their operation conditions were selected, desirable efficiency of SNCR method was determined. The experimental results indicated positive application perspectives of this method. Reduction of NOx concentration by 40 % was reached. It was determined that improperly selected SNCR technology can even increase NOx concentration.

NOx Reduction by In Situ Catalytic Reduction in the Combustion Process of Coke

2012 ◽  
Vol 610-613 ◽  
pp. 2104-2108
Author(s):  
Yan Guang Chen ◽  
Hong Jing Han ◽  
Jia Lu ◽  
Jin Lian Li ◽  
Ying Chen ◽  
...  
Keyword(s):  
Catalytic Reduction ◽  
Nox Reduction ◽  
Combustion Process ◽  
Combustion Efficiency ◽  
Nox Emission ◽  
Impregnation Method ◽  
Supporting Effect ◽  
Catalytic Effects ◽  
Co Emission

A new method, NOx reduction by in-situ catalytic effects of additives loaded in coke, was proposed. A series of coke samples with different loading amounts of CaCl2, Ce(SO4)2 and La2(SO4)3 were prepared by using the impregnation method, the rules of NOx and CO emissions in the combustion were investigated. The results show that CaCl2, Ce(SO4)2 and La2(SO4)3 play in-situ catalytic effects on the NOx reduction reactions. When the loading of CaCl2 is 4.0%, the amount of NOx emission is reduced by 13.9%. When the loading of Ce(SO4)2is 4.0%, the amount of NOx emission decreases by 17.2%. When the loading of La2(SO4)3 is 4.0%, the amount of NOx emission decreases by 8.7%. Ce(SO4)2 possesses the combustion-supporting effect. As 4.0% Ce(SO4)2 in coke, the CO emission is reduced by 26%, which improves the combustion efficiency of coke.

In-situ stabilization of silver nanoparticles in polymer hydrogels for enhanced catalytic reduction of macro and micro pollutants

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Luqman Ali Shah ◽  
Rida Javed ◽  
Mohammad Siddiq ◽  
Iram BiBi ◽  
Ishrat Jamil ◽  
...  
Keyword(s):  
Catalytic Reduction ◽  
Thermo Gravimetric Analysis ◽  
Activation Parameters ◽  
Reduction Reaction ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
In Situ Stabilization ◽  
Hybrid Hydrogels ◽  
Kinetics Of

AbstractThe in-situ stabilization of Ag nanoparticles is carried out by the use of reducing agent and synthesized three different types of hydrogen (anionic, cationic, and neutral) template. The morphology, constitution and thermal stability of the synthesized pure and Ag-entrapped hybrid hydrogels were efficiently confirmed using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and thermo gravimetric analysis (TGA). The prepared hybrid hydrogels were used in the decolorization of methylene blue (MB) and azo dyes congo red (CR), methyl Orange (MO), and reduction of 4-nitrophenol (4-NP) and nitrobenzene (NB) by an electron donor NaBH4. The kinetics of the reduction reaction was also assessed to determine the activation parameters. The hybrid hydrogen catalysts were recovered by filtration and used continuously up to six times with 98% conversion of pollutants without substantial loss in catalytic activity. It was observed that these types of hydrogel systems can be used for the conversion of pollutants from waste water into useful products.

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