Date of Award

Fall 1994

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Chemical Engineering - (Ph.D.)

Department

Chemical Engineering, Chemistry and Environmental Science

First Advisor

Robert Benedict Barat

Second Advisor

Joseph W. Bozzelli

Third Advisor

Richard Stephen Magee

Fourth Advisor

Henry Shaw

Fifth Advisor

Javad Tavakoli

Abstract

The feasibility of converting fuel-bound chlorine and nitrogen into HCl and N2 with reduced pollutant emissions of CO, NO, and unburned hydrocarbons was investigated in a two-stage turbulent flow reactor. The study consists of four segments: completion and validation of the experimental facility, experimental and modeling studies of methyl chloride (CH3Cl) combustion, similar studies on monomethyl amine (CH3NH2), and finally studies on simultaneous CH3Cl and CH3NH2 combustion.

Validation of the experimental facility was made by combustion of ethylene (C2H4) and air under both fuel-lean and fuel-rich conditions. Premixed C2H4 and air, fed into the first stage, served as the primary fuel and oxidant for all experiments. Additional air or steam was injected into the second stage as required. Perfect stirred and plug flow sequential reactor (PSR+PFR) behavior was demonstrated by good agreement between the experimental data and the modeling predictions.

An experimental and modeling study of methyl chloride combustion and the effects of steam injection on combustion emissions was performed. Reactor temperatures, O2, CO, CO2, and light hydrocarbon concentrations were measured in both fuel-lean and fuel-rich cases. Experimental data showed that CH3Cl inhibits the CO burnout and increases the yield of incomplete products of combustion (PICs). Model predictions agree well with the experimental observations. Analysis of the modeling results indicates that reaction OH + HCI <=> CI + H2O is a major OH consumption channel, which inhibits the CO burnout reaction OH + CO <=> CO2 + H. Results of experiments and modeling show that steam injection into the second stage can effectively enhance CO burnout and reduce PIC emissions.

Monomethyl amine, serving as a source of fuel-bound nitrogen, has been burned in air with fuel ethylene. Experiments showed that NO formation from the first stage dramatically decreased as the fuel equivalence ratio (φ) in this stage was increased from φ=0.86 to 1.45. While the first stage was operated fuel-rich, air was injected into the second stage to achieve overall fuel-lean combustion. Under such air staging conditions a minimum NO emission from the second stage was observed and the corresponding optimal fuel equivalence ratio (φ)m=1.28 to 1.38) in the first stage was determined to be a function of the feed CH3NH2 concentration. Data indicated that the NO emission was reduced by more than 60% with air staging combustion as compared to the fuel-lean only case at the same 4). A detailed elementary reaction mechanism has been used together with the PSR+PFR reactor simulation to model the experimental data. Rate-of-production (ROP) analyses based on the successful modeling have illuminated the key pathways to NO formation and destruction.

The simultaneous combustion of monomethyl amine and methyl chloride was studied using the two-stage reactor. Interactions of the chlorine- and nitrogen-containing species during combustion were observed from the experiments. Under staged conditions, the interactions resulted in lower NO emissions as the methyl chloride loading in the feed was increased. A proposed interaction mechanism has been satisfactorily used to predict the experimental observations.

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