Combustion modification tests on a subscale cement kiln for NOx reduction by W. A Carter

Cover of: Combustion modification tests on a subscale cement kiln for NOx reduction | W. A Carter

Published by U.S. Environmental Protection Agency, Industrial Environmental Research Laboratory in Research Triangle Park, NC .

Written in English

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Subjects:

  • Cement kilns -- Environmental aspects -- United States

Edition Notes

Book details

StatementW.A. Carter and R.C. Benson
ContributionsBenson, R. C, Industrial Environmental Research Laboratory (Research Triangle Park, N.C.)
The Physical Object
Pagination5 p. :
ID Numbers
Open LibraryOL14892156M

Download Combustion modification tests on a subscale cement kiln for NOx reduction

Tests in a combustion tunnel simulating kiln conditions showed dilution of the primary air stream with an inert gas, altered fuel injection velocity, and combustion air preheat to be most effective in lowering the NO emission level.

This report summarizes results of tests of a subscale rotary cement kiln firing natural gas and pulverized coal.

Get this from a library. Combustion modification tests on a subscale cement kiln for NOx reduction. [W A Carter; R C Benson; Industrial Environmental Research Laboratory (Research Triangle Park, N.C.)]. Gross NOx emissions are typically in the range of to 1, ppm being closely related to kiln combustion conditions.

In the cement industry normally, 95% of NOx formed is nitric oxide (NO). It is important to note that the baseline NOX levels observed for the subscale kiln « ppm, dry at 3% 02) were far lower than any observed by KVB on full-scale kilns.

The most likely explanation is that ambient air was used in all of the subscale tests. In an actual kiln, air preheater temperatures of K (°F) are not uncommon.

The report gives results of field tests of a subscale rotary cement kiln to evaluate the effect of various combustion modifications on gaseous emissions, using a research kiln donated by a cement. UNCONTROLLED NOX EMISSIONS FROM CEMENT KILNS In cement manufacturing, conditions favorable for formation of NOX are reached routinely because of high process temperatures.

Essentially all NOX emissions associated with cement manufacturing are generated in cement kilns. In cement kilns, NOX emissions are formed during fuel combustion by two. A subscale cement kiln simulator was designed, fabricated and operated to determine the effect of burner operating variables on near-flame NOX production.

The effects of combustion air preheat, carrier air dilution and fuel injection velocity were the primary variables assessed for both natural gas and coal. Based on the results of this program, further work has been initiated to investigate, in more detail, the use of combustion modifications on process heaters and cement kilns.

CONCLUSIONS The data presented show that combustion modification is an effective means to control N0 X emissions for many stationary combustion sources.

• SO2 reduction – Approx. % SO2 is converted in high-dust SCR to sulfates – Limitation on SO2 in flue gas only for low-dust applications. • NOX reduction by ≥ 90% • Reduction. The degree of NOx emission is mainly determined by ♦ Flame temperature ♦ Oxygen content ♦ Residence time of exhaust gas in the kiln ♦ Fuel-N ♦ Primary measures against NOx ♦ Secondary measures against NOx The NOx control technologies available for cement kilns include: ♦ Combustion Operational Modifications (COM) ♦ Low NOx.

Cement kilns have been identified as a stationary source that emit more than 25 tons of nitrogen oxides (NO x) per year. This alternative control technique (ACT) document provides technical information for use by State and local agencies to develop and implement regulatory programs to control NO x emissions from cement kilns.

Reduced flame temperatures and reducing conditions in the burning zone of a cement kiln may not be compatible with the production of cement clinker Coupling a low-NOx step burner with flue gas recirculation has been shown to reduce NOX emissions further in a cement kiln The additional NOX reduction attributable to FOR was estimated to be.

NOx REDUCTION El -akisting PH/PC dry-process cement kilns. Installing low-NO. burners (LNB) in the kiln distinct combustion zones are created using LNBs. Flame turbulence as well as air and fuel mixing are suppressed during the first stage of combustion. A fuel-rich, oxygen-lean, high-temperature.

Several techniques can be used to reduce NO x emissions in the cement industry. Primary measures consist in Combustion modification tests on a subscale cement kiln for NOx reduction book of the kiln and calciner combustion and should be comprehensively studied and implemented before the implementation of secondary measures, which consist mainly of treatment of the exhaust gases (SNCR and SCR) and necessarily present higher operational costs.

The experiments guided by the modeling have led to significant reduction in NOx emission; NOx was reduced from a level of lb/ Btu ( ppm @ 3% 02) in a single stage flame to lb/ Btu (80 ppm @ 3% 02) in staged combustion when the fuel equivalence ratio in the fuel rich stage was maintained in the range of = to (50 to 70% fuel rich), very close to that predicted from the.

1 Introduction. Nitrogen oxides constitute one of the main air pollutants and the NO x emission regulations for the cement industry are becoming more and more stringent.

Precalciners are used in the cement industry as the main equipment for NO x reduction. In the precalciner the fuel NO x accounts for 80 % of the total NO x from coal combustion, which is the main objective in the target for NO.

The Reduced Emission Oxygen (REO) kiln A complete review of the changes induced by converting a conventional cement kiln to oxygen combustion is necessary to ensure the feasibility of the design.

The work presented here summarizes a report written by the author for the Cement Sustainability Initiative of the World Business Council on. In this thesis, the impact of staged combustion on the operation of a precalciner cement kiln, is considered.

Mathematical modelling and full-scale experiments at the Norcem cement works in Brevik. Cement Kiln Report (FINAL – 7/14/) INTRODUCTION This study was conducted to explore potential NOx emissions reduction strategies for cement kilns in Ellis County.

This project included assessing existing NOx control technologies as well as new technologies that have not been previously considered by TCEQ. Combustion modifications, as a practical matter, provide little opportunity for beneficial reduction of either NOx or SOx emissions originating in fuels or raw material (lime mud) fed to the kiln.

Reducing flame temperature in gas-fired kilns or altering distribution of combustion air in oil-fired kilns can reduce NOx. That reduction, however.

MPR Associates, Inc. - 4 - Revision 0 NOX Reduction Overview The table lists the NOX reduction achieved by each technology as a percentage of NOX reduction prior to the implementation of the combustion control.

The capital costs, both per ton of NOX emissions removed and per kW of production, are also listed in Table 3. This report addresses nitrogen oxides (NOx) controls for new cement kilns and focuses specifically on staged combustion in the calciner (SCC), selective noncatalytic reduction (SNCR), and selective catalytic reduction (SCR) as processes for the control of NO x.

Controlling NOx Emissions from Cement Kilns Rules in Ti Texas Administrative Code, Chapterfor controlling emissions of nitrogen oxides from cement kilns. These rules are part of the State Implementation Plan strategy to meet the National Ambient Air Quality Standards for ozone.

It can be expected that NOx from precalciner combustion can be reduced to around - ppm. Calciners can be designed to reduce NOx generated in the burning zone, or to keep NOx generated in the calciner low, or both.

Since further NOx reduction to lower levels require methods such as NH 3 injection, temperature control is very important. cement kiln and other onsite combustion equipment. The cement kiln is the most significant of these combustion units and typically is fueled with coal. Other fossil fuels are generally too expensive to be used for kiln fuel; however carbon-based waste materials (e.g., solvents, oils.

A subscale cement kiln simulator was designed, fabricated, and operated to determine the effect of burner operating variables on near-flame NOx production. The effects of combustion air preheat, carrier air dilution, and fuel injection velocity were the primary.

Reducing NOx from existing cement kiln lines Abstract: In cement kiln lines, significant amounts of NOx emissions can be formed both in the rotary kiln and in the precalciner. To reduce NOx formation, low NOx techniques can be applied to the burner and to the combustion systems used in the rotary kilns and precalciners, respectively.

Thermal NOx is formed from air nitrogen at temperatures higher than °C, and its rate of formation is affected by temperature and oxygen levels.

Kilns with high heat load and high oxygen levels at the front end mainly produce thermal NOx in considerable quantities. Tests were carried out with different oxygen contents at the kiln inlet. Primary NOx reduction Primary measures for NOx reduction set a focus on avoiding the formation of nitrogen oxides by intelligent combustion control.

Based on this philosophy no additional chemicals are needed. Optimized burner design and operationas well as staged combustion in the calciner lead to a lower formation rate of NOx. Basic idea. Interim measures (principally modification of water sprays to reduce the gas temperature into the ESPs, together with modification of combustion conditions) reduced the concentrations to 37 to 1, ng/dscm (reductions of approximately 4-fold for 4 units, and fold for the fifth), and then-current regulations required a reduction to less.

Cement Rotary Kiln Coal Combustion Energy & Fuels, Vol. 20, No. 6, precalciner is about %. After it enters into the rotary kiln, the feed is heated by the gas with high temperature and the wall of kiln, and the decomposition reaction proceeds.

In this zone, there. The article reviews the development of the cement industry in China from its beginnings, inonward through the construction of the first wet-process kilns inup to the founding of the. This partial substitution of one or more additives for cement clinker results in a reduction in CO 2 emission and energy 2 saving in cement manufacture and provides heavier-duty cements that can.

A summary of test results for each modification is also given in that section. Cement Kiln Combustion Modification Concepts Rotary kilns present a difficult task for combustion modification because they have only a single burner, and the product quality is very depen- dent upon temperature.

Cement Kilns The cement industry isbased on the conversion of a mixture oflimestone (CaC03) and clay, into clinker material consisting of compounds of calcium oxide (CaO), by the addition oflarge quantities of heat in a coal- or gas-fired rotary kiln.

NOx formation results. Most cement and lime plants that are fan-limited implement oxygen enrichment to increase production. The added oxygen enables the combustion of additional fuel, allowing operators to increase feed rates.

Enhanced kiln stability and quick recoveries from “pushes” also translate into increased production. We have helped customers routinely. cement kilns. Oxy-fuel seems to be applicable only at new kilns, because a retrofit at ex-isting kilns would be too costly.

- Post-combustion capture does not require fundamental changes in the clinker burning process. Therefore this technology would be available not only for new kilns, but also for retrofits at existing cement kilns. Kiln system without pre-calciner Low pre-calcination rate of hot meal (app.

40%) Fuel used for sintering and calcination in the kiln Possible to use fuels with “delayed heat release” in the kiln burner to shift energy to the calcination zone. Kiln burner Inlet Chamber (max. 15% of energy) Calcining zone Transition and Sintering zone.

Between and tonnes/day of CO 2 at a pipeline pressure of bar(a) can be captured from a t/d oxy-fuel cement kiln.

Cost of CO 2 compression and purification ranges from about € 24/tonne to about € 27/tonne CPU is able to maintain CO 2 recovery of. Increasing the efficiency of combustion in the precalciner was the object of numerous simulations and modeling: Iliuta et al. [] investigated the influence of operating conditions on the level of calcination and made a sensitivity analysis of their model with respect to combustion/calcination parameters.

Ranade et al. [], Hu et al. [] and Lu et al. [] based on their parametric sensitivities on. Part Three: Results and Conclusions of Measuring Water in Ethylene and Propylene Production with a HD TDLAS Analyzer: Part One: The Importance of Measuring Water in Ethylene a.

re Sox and Nox generation and solution? As mentioned, Thermal NOx generation dominates at high temperature in the main kiln flame. Combustion in calciners can be designed to produce a lower concentration of NOx, particularly by having Fuel NOx generation as the dominant mechanism and/or by having a less-oxidising combustion regime than can be tolerated in the kiln .Typical SO 3 levels in cement kiln applications range from ppm.

The reduction of SO 3 levels improves Hg removal efficiencies. SO 3 concentrations as low as 3 or 4 ppm can dramatically reduce Hg adsorption. Trona is a rock (ore) mined principally in the Unites .

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