ASSESSMENT OF SOME ORGANIC POLLUTANTS FROM COMBUSTION PROCESSES. PRELIMINARY RESULTS OF LABORATORY AND FIELD TESTS.

Abstract

Italian Law on emission limitation and control requires 54 organic compounds to be determined in the flue gases of industrial combustion plants. These compounds show very different chemical and physical characteristics
(e.g. volatility, stability, reactivity with water …). Some of these compounds (i.e. PAH, PCDD/PCDF, VOC) are commonly monitored in emissions of Large Combustion Plants, but for the majority of them a validated standard
method doesn’t exist, neither at Italian nor at international level.

A preliminary laboratory investigation has therefore been performed, which allowed to focus on the most promising methods for some of the above mentioned compounds. During this phase, US-EPA, OSHA and NIOSH methods, together with the technical literature, have been reviewed and some tests have been performed on a small scale test rig.

The selected methods have then been field tested on a low-sulfur heavy fuel oil fired power plant, equipped with ESP and SCR, and on a coal-fired power plant, equipped with ESP, FGD and SCR (the results of this last test are only partially accounted for in this paper, because lab analyses are still in progress).

Experimental tests performed allowed to select and verify –at least in a preliminary way- a series of procedures suitable for the sampling in combustion flue gases of about 30 organic pollutants.

1 INTRODUCTION

Italian Law on emission limitation and control (Environment Ministry Decree N.51 of July 12, 1990) requires 54 organic compounds -defined as “carcinogenic, mutagenic or highly toxic”- to be determined in the flue gases of industrial combustion plants. These compounds show very different chemical and physical characteristics (e.g. volatility, stability, reactivity with water …). Some of these compounds (i.e. PAH, PCDD/PCDF, VOC as Total Organic Carbon) are commonly monitored in power plants and others Large Combustion Plants (LCP) emissions, but for the majority of them a standard method -validated for combustion flue gases- doesn’t exist, neither at Italian nor at international level [Bertolaccini 1991, Johnson 1988, Wagoner 1991].

ENEL Produzione planned and financed a comprehensive R&D program, developed and carried out by CESI during 1999 and 2000, aimed to the development and testing of sampling and analysis methods for some of the
above mentioned compounds. The following compounds have been excluded:

• Polycyclyc Aromatic Hydrocarbons (PAH), Dioxins and Furans (PCDD and PCDF), Polychlorobiphenyls (PCB) because Italian (i.e. UNICHIM Method N.825) and/or international (i.e. ISO/DIS 11338 and EN1948) methods were already available or in the development stage;
• 1-methyl-3-nitro-1-nitrosoguanidine and methyl-ONN-azosymethylacetate because of their very high reactivity, that will make sampling impossible or very difficult,
• propylenimine because of its commercial unavailability.

The first step of the program has been a grouping of the remaining 36 compounds (see Table 1) according to their chemical and physical characteristics and to the preliminary definition of the potentially suitable methods. The results are summarized in Table 2. During this phase, US-EPA, OSHA and NIOSH methods, together with the technical literature, have been reviewed.

Following steps have been:

• laboratory development and tuning of the analytical instrumental techniques,
• laboratory test of the recovery rates from liquid or solid sampling supports,
• test of sampling methods, by means of a small scale test rig
• ,field test of the selected sampling methods, on a low-sulfur heavy fuel oil fired power plant, equipped with ESP and SCR, and a coal fired Power Plant equipped with SCR, ESP, FGD.