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.

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.

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.

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 Performance of Mn-Fe-Ce/GO-x for Catalytic Oxidation of Hg0 and Selective Catalytic Reduction of NOx in the Same Temperature Range

Catalysts ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 399 ◽  
Author(s):  
Donghai An ◽  
Xiaoyang Zhang ◽  
Xingxing Cheng ◽  
Yong Dong
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Oxidation ◽  
Flue Gas ◽  
Photoelectron Spectroscopy ◽  
Catalytic Reduction ◽  
Good Mechanical Property ◽  
Active Components ◽  
Thermal Methods ◽  
Temperature Range ◽  
Reduction Of Nox

A series of composites of Mn-Fe-Ce/GO-x have been synthesized by a hydrothermal method. Their performance in simultaneously performing the catalytic oxidation of Hg0 and the selective catalytic reduction of nitrogen oxides (NOx) in the same temperature range were investigated. In order to investigate the physicochemical properties and surface reaction, basic tests, including Brunauer-Emmett-Teller (BET), XRD, scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) were selected. The results indicate that the active components deposited on graphene play an important role in the removal of mercury and NOx, with different valences. Especially, the catalyst of Mn-Fe-Ce/GO-20% possesses an excellent efficiency in the temperature range of 170 to 250 °C. Graphene has a huge specific surface area and good mechanical property; thus, the active components of the Mn-Fe-Ce catalyst can be highly dispersed on the surface of graphene oxide. In addition, the effects of O2, H2O, NO and SO2 on the removal efficiency of Hg0 were examined in flue gas. Furthermore, the regeneration experiments conducted by thermal methods proved to be promising methods.

Clean Power From Coal: Design and Status of East Kentucky Power Cooperative’s E. A. Gilbert Unit

2005 ◽  
Author(s):  
Peter Treff ◽  
Craig Johnson
Keyword(s):  
Low Temperature ◽  
Catalytic Reduction ◽  
Nox Emissions ◽  
Residence Times ◽  
So2 Emissions ◽  
Gas Cleaning ◽  
Cleaning Equipment ◽  
The Us ◽  
Fluid Bed ◽  
Commercial Operation

East Kentucky Power Cooperative’s (EKPC) E. A. Gilbert unit promises to be one of the cleanest coal fired units in the US. Employing Circulating Fluid Bed (CFB) technology and innovative gas cleaning equipment from ALSTOM, this 268 MW unit will fire a variety of coals. The E. A. Gilbert unit is located at EKPC’s Spurlock Station alongside a 300 MW and a 500 MW pulverized coal unit that were built more than 20 years ago. Low SO2 emissions will be achieved by sulfation of limestone sorbent in the CFB and by additional sulfation of unreacted sorbent in the Flash Dryer AbsorberTM (FDA) system located downstream of the CFB. This will permit low SO2 emissions (0.2 lb/MM BTU, >95% removal). Very low NOx emissions (0.1 lb/MM BTU) are enabled by the low combustion temperatures of the CFB and by the use of selective non-catalytic reduction (SNCR). The latter employs the addition of anhydrous ammonia and extended residence times at low temperature to further reduce NOx within the boiler. Having broken ground in June of 2002, the unit is scheduled to begin firing coal in the winter of 2004–5, with commercial operation scheduled for spring, 2005. Its’ design features and status are the focus of this paper.

Sign in / Sign up

Export Citation Format

Share Document