Emissions from Pressurized Fluidized-Bed Combustion Processes Keshava S. Murthy'", James E. Howes, and Herman Nack Battelle-Columbus Laboratories, Columbus, Ohio 4320 1
Ronald C. Hoke Exxon Research & Engineering Company, Linden, N.J. 07036
Results of the comprehensive analysis of emissions from a pressurized fluidized-bed combustion unit (the Exxon Miniplant) are described as an illustration of the methodology for comprehensive analysis. The results are discussed in the context of the overall environmental assessment of the process being conducted by the U.S. Environmental Protection Agency. The comprehensive analysis of the fluidized-bed combustion emissions and process streams involved approximately 740 measurements on about 90 samples, using more than 40 different inorganic, organic, and physical analytical methods. A brief discussion on the sampling methods and analytical techniques is also included.
Environmental data acquisition is one of the seven major steps (Figure 1)in conducting a complete environmental assessment of emerging energy technologies such as fluidizedbed combustion (FBC) of coal ( I ) . The data are acquired primarily by comprehensive analysis of emissions. Precommercial-stage comprehensive analysis (CA) of emissions from FBC units provides an opportunity for detecting potential environmental problems early in the development of the process. The environmental assessment of the process based on the CA data should assist in the identification and/or development of the most cost-effective control technologies. A phased approach in three levels is the currently accepted technique for sampling and analyzing emissions. The three levels of analysis are defined as follows: Level 1 analysis includes comprehensive screening of a wide variety of organic and inorganic components. Level 1 sampling and analysis are designed to rapidly identify the potential pollutants from a source, and to measure them with a target accuracy factor of f 3 . I t also identifies all process streams that may contain four types of pollutants: gaseous, particulates, liquids/slurry, and solids. In addition, level 1 strategy includes bioassay testing of several effluent streams t o obtain a direct index or estimate of their toxicity potential. Level 2 analysis is based on level 1results. More accurate, compound-specific analytical techniques are used to pinpoint problem pollutants and effluent streams. Level 1 data, together with bioassay data, will be used to identify the analytical needs of levels 2 and 3. Level 3 analysis (not yet defined completely) would include routine continuous monitoring of those pollutants identified as specific problems in level 2. A set of 12 biological tests was used in level 1testing. These tests and the samples on which they were used are given in Table I. They are designed to test the possible toxicity of a waste stream to mammalian, marine, freshwater, plant, and soil systems. This test protocol provides a fairly good representation of the various biological constituents of the environment that might be exposed to a waste stream. The bioassays are designed to be implemented quickly and inex-
Present address, Battelle Northwest Laboratories, Richland, Wash. 99352. 0013-936X/79/0913-0197$01.OO/O
@
1979 American Chemical Society
pensively, in keeping with the screening nature of level 1 testing. Their output will permit a relative ranking of waste streams according to biological hazard, and, together with the chemical and physical data, will provide an overall hazard characterization of the waste streams. The measurement techniques and results presented in this paper are based largely on level 1 analysis. The sampling matrix for level 1 (and some level 2 analysis of substances already known as problem pollutants) is shown in Table 11. Data presented in this paper were obtained from the pressurized FBC facility a t Exxon; sampling was conducted in accordance with Table 11. This facility has a 0.32-m diameter reactor which was operated a t 890 "C, 900 kPa, 1.2 m/s superficial velocity, 40% excess air, 75 kg/h coal feed, and 11.0 kg/h dolomite sorbent feed a t a Ca/S molar ratio of 1.25 for the tests reported in this paper.
Experimental Sampling Methods. The comprehensive analysis program for the Exxon unit consisted of sampling seven of the nine streams shown in Figure 2. The nine streams are: (1) coal feed, (2) dolomite feed, (3) second stage cyclone discard, (4) bed reject material, (5) cyclone discard leachates, (6) bed reject material leachates, (7) undiluted stack gas, (8) diluted stack gas, and (9) dilution and combustion air. Sampling of the sorbent regenerator unit was not performed since this unit was not operated during the tests. Streams 5 and 6 were simulated in the laboratory since no leachate streams were actually present a t the miniplant site. Five tests were conducted at Exxon from March 28 to April 1, 1977; the Miniplant was operated continuously for about 80 h. Sampling was performed on an around-the-clock basis by two 7-man teams working 12-h shifts. During each test, lasting 5 h, the various FBC streams were sampled by the techniques given in Table 11. Grab samples of solids from the FBC process streams were taken periodically throughout each test. The individual samples were composited to obtain one sample per test. The gases (CO, CO2, 0 2 , S02, etc.) in the undiluted flue gas a t stream 7 were sampled continuously for analyses by Exxon on-line instrumentation. Integrated grab samples were also taken for C02, and 0 2 analyses by Orsat. SO2 and NO, were sampled by EPA methods 6 and 7, respectively, to provide backup data. The controlled condensation method was used to sample for SOs/H2S04, and special impinger trains were HCN, HC1, and HF. used for sampling "3, Continuous sampling of the undiluted flue gas was performed for total hydrocarbon measurements. Grab samples in glass bulbs were taken several times during each test for gas chromatographic analysis of c 1 - C ~hydrocarbons and sulfur compounds. The primary particulate sampling was performed in the flue gas stream which was reduced to near atmospheric pressure by dilution with air. The source assessment sampling system (SASS) was used to collect samples for chemical and physical analysis. In three tests, the stainless steel condenser module normally supplied with the SASS unit was replaced with a glass module of similar dimensions. The glass module modification was included in these tests since a preliminary sampling experiment indicated excessive corrosion of the stainless Volume 13, Number 2, February 1979
197
Table 1. Level 1 Bioassay Matrix sample type
water and liquids
health effects tests
microbial mutagenesis
solids gases particulates sorbent
rodent acute toxicity
+ + +
ecology effects tests
cytotoxicity
+
+ + +
algal bioassays
static bioassays
+
soil microcosm
+
+
plant stress ethylene soil microcosm
Table II. Sampling and Analyses to Be Performed in Comprehensive Analysis of FBC Units
specles, pollutants
continuous gas measurements COP
co
NO NO2
SOP 0 2
sample collection techniquesa
analysis method
*
slack partlcuiates mid flne > 3 pm 1 3 pm
system stream or material solid waste coilec-
lion gas
cw cw cw cw cw cw
NDIRC IR or UV CLC CLC NDlR PM
X X X X X X
IG IG IG M7 IG M6 IG IG IG IG IG IG IG IG IG IG IG IG GT/St St St
FGCITC FGCITC FGC/TC M7 FGCITC -I-M6 FGCITC FGC/TC FGCITC FGCIFPD FGC/FPD FGCIFPD FGCIFID FGC/FID FGCIEC FGC/TC FGCITC FGC/TC ion chromatograph titration SIE
X X X X X X X X X X X X X X X X X X X
leachate from solid waste sorbent collection feed device bed
bed reject
coal feed
X
X
X
X
X
X X X X
X
X
device discard
integrated gas measurements
co2
co
+ +
NO,
so2 0 2
N2 H20 H2S
cos CH3SH-CsH13SH Cj-cs hydrocarbons C ,-C hydrocarbons C1-Cs chlorocarbons "3
HCN cyanogen S031H2S04 HCI fluoride integrated specimens for subsequent group anal. inorganic chemicals 71 elements (Li through U) proximate (fuels) ultimate sulfur forms (fuels) radionuclides (gross
a
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X X
X X
X X
X X
X X
X X
X X
X X
X
X
X X
AAS
X
X
X
X
X
X
X
SASSfGs colorimetric SASS/Gs colorimetric SASSlGs distillation/colorimetric
X X X
X
X
X
X
X
X
SASSIGS SSMS Gs Gs Gs SASSIGs
ASTM 0 3 172-73 ASTM D3 176-74 ASTM D2492-68 LBPC
X
X
X
X
X
X X X
P)
organic chemicals organics by class organic compds POM organic-reduced sulfur compounds C7-C12 hydrocarbons organic mass integrated specimens for subsequent specific anal. volatile, toxic elements (Be, Cd, Hg, Pb, Se, Sb, Te) As CIF-
198
+
SASSIGs LCIIR (total sample and 8 fractions) SASSIGs LCILRMS (selected fractions) SASSIGs GCIMS SASSIGs GCIFPD (8 fractions combined SASS/Gs GCIFID SASSIGs microbalance (8 fractions)
SASSfGs
Environmental Science & Technology
X X
X
X
X
X
Table 11. continued
~~
species, pollutants
Na Ca Mg C032-
sample coliectlon techniquesa
5042-
Gs Gs Gs SASS/Gs SASS/Gs
S032-
SASS/Gs
S2-
SASSlGs
NO?NO3C (noncarbonate) heating valve particle morphology particle size
SASS/Gs SASS/Gs Gs Gs Gs Gs
particle mass biological assays health microbial mutagenesis cytotoxicity cytotoxicity
gas
system stream or material solid waste collecleachate from solld waste tlon bed coal sorbent collectlon devlce leed feed device bed discard reject
X X X X
X X
X X
X X
X X X X
X
X
X
X
X
X
X
X
X
X
X X
X X
X X X
X X X
X
X X X X X X
X
X
X
X
X
X
X
X
X
X
X
X
algal bottle static
X X
X X
X X
X X
X X
X X
X X
X X
X X
X X
X X
X X
SASS/Gs
static unicellular marine algae static
X
X
X
X
X
X
SASS/Gs SASS/Gs SASS/Gs
static soil microcosm stress ethylene
X X
X X
X X
X X
X X
X X
SASS/M5
SASS/Gs SASS/Gs
salmonella/ames human lung fibroblast (WI-38) SASS/Gs rabbit alveolar macrophage (RMA) SASS/Gs in vivo rodent
acute toxicity ecological freshwater algal SASS/Gs freshwater animal SASS/Gs (daphnia) freshwater animal (fish) SASS/Gs saltwater algal SASSlGs saltwater animal (grass shrimp) saltwater animal (fish) terrestrial soil terrestrial plant
analysis method
AAS A AS/titration AAS gas evolution titrationlion chromatography SO2 evolution/ colorimetric HzS evolution/ titrations colorimetric colorimetric combustion ASTM D 2015-66 LM/SEM sieve ASTM D 4 1038 weight
stack partlculates mid line > 3 Mum < 3 gm
X Xd
X
X
X
X
X
X
X X
X
X
X
X
X
X X
X X
X X
X X
X
X
a Cw, continuous withdrawal through nonreactive line with mechanical filtration; IG. integrated grab sample of gas in glass bulb: GR/St, Goksoyr-Ross coiVspecial sampling train: St, separate wet chemical train to collect gas (such as method 6):SASS, source assessment sampling system (train used for suspendedparticulates, organics, and volatile trace elements); Gs, grab multiple samples riffled to reduce to 100-9 representative sample: M5. €PA method 5; M6, €PA method 6; M7, €PA method 7. NDIR, nondispersive infrared; IR, infrared; UV, ultraviolet; CL, chemiluminescence; PM, paramagnetic: FGCITC, field chromatograph/thermaI conductivity detector; FGCIFPD. field chromatograph/flame photometric detector; FGC/FID, field chromatograph/flame ionization detector: FGC/EC, field chromatographielectron capture detector: SI€, selective-ion electrode: SSMS, spark source mass spectroscopy; ASTM, American society for testing materials standard method; LBPC. low background gas proportional controller: LC, liquid chromatography: LRMS, low-resolution mass spectrometry; GC, gas chromatography; GC/MS, gas chromatography with mass spectrography: AAS, atomic absorption spectroscopy: LM/SEM, light microscopy/scanning electron microscope. Or acceptable instrumentation already installed at FBC Unit. Coarse ( > l o Fm) and filter (
