Abstract Booklet 2006 - Swanson School of Engineering - University ...

52-5
Pilot-Scale Demonstration of Upgrading Waste Sulfuric Acid From Acid
Washing Process for Crude Benzol Production in a Coke Plant
Shitang Tong, Cui Zhengwei, Wuhan University of Science and Technology, P.R.
CHINA
Zhanghua Zhen, Hua Qi, Jinan Iron and Steel Corperation, CHINA
Charles Q. Jia, University of Toronto, CANADA
To process crude benzol from coke oven gas, the acid washing process is widely used
in coke manufacturers in China. Although the hydrogenation process was known to be
a superior process due to its better quality control of the final benzene products and the
avoidance of the generation of waste sulfuric acid containing coal tar, many coke
manufacturers still hesitate to adapt the technology due to its high cost. Containing
acidic tar, the waste sulfuric acid generated from the acid washing process is a pinkish
black liquid that has an odious smell and a rather high COD value. With nearly 50 wt%
of sulfuric acid, it contains sulfonic surfactant, saturated and unsaturated hydrocarbons.
Despite its troublesome nature and potential impacts on the environment, nothing was
practically done to deal with this waste stream. Recently, we have developed an
environment-friendly process for upgrading the waste sulfuric acid. A 30 L installation
was built and successfully demonstrated in Jinan Iron and Steel Co., China, where 3.5
million tons of coke are produced each year. The process consists of two major
operation units: polymerization and extraction. In the first unit, a specific catalyst is
used for inducing the polymerization of unsaturated organic species and the
precipitation of a coke-like solid material. In the second unit, the filtrate from the first
unit is extracted with an organic solvent obtained from coal tar distillation to clear off
most of the remaining organic compounds in the sulfuric acid. To reduce the amount of
the solvent used in the primary extraction step, a secondary extraction with another
solvent obtained from the crude benzol processing may be used. Upon the treatment
using the two-stage process, the COD value was reduced from 200 g/l to 20g/l, a
removal of over 80 %. Color index was reduced by up to 96%. The yield of the cokelike
solid sludge was 15-25 % of the mass of the waste acid. The purified acid was then
used to produce ammonia sulfate crystals of a satisfactory quality, without
encountering any engineering problem. The coke-like material was used as a precursor
for activated carbon production.
SESSION 53
COAL UTILIZATION BY-PRODUCTS – 3
53-1
Investigation of the Relationship between Particulate Bound Mercury and
Properties of Fly Ash in a Full-scale 100 MWe Pulverized
Coal Combustion Boiler
Wei-Ping Pan, Chin-Min Cheng, Yan Cao, Western Kentucky University, USA
Sen Li, Purdue University, USA
The properties of fly ash in coal-fired boilers influence the emission of mercury
pollutant from power plants into the environment. In this study, fly ash samples were
collected from mechanical hopper (MHP) and electrostatic precipitator hopper (ESP)
of a full-scale 100-MWe, pulverized coal combustion boiler. The mercury content,
specific surface area (SSA), unburned carbon, and elemental composition of the fly ash
samples were analyzed to evaluate the correlation between the concentration of
particulate bound mercury and the properties of fly ash in coal combustion boilers. For
a given coal, it was found that the mercury content in the fly ash collected from ESP
was greater than in the fly ash samples collected from MHP. This phenomenon may be
due to higher sulfur, unburned carbon, and manganese contents, as well as SSA, of
ESP fly ash than of MHP fly ash. Comparison of the fly ash samples generated from
seven different coals by using the statistical Pearson Correlations indicates that the
mercury adsorbed on both MHP and ESP fly ashes has a highly positive correlation
with the unburned carbon and manganese contents of those fly ashes, respectively.
Moreover, no significant correlations were found between particulate bound mercury
and other elemental compositions of fly ash. The high SSA and unburned carbon
contents are beneficial for fly ash to catch gaseous mercury by physical adsorption,
while sulfur will aggregate with gaseous mercury. Manganese in fly ash is believed
participating in oxidizing volatile elemental mercury (Hg 0 ) to mercury (Hg 2+ ). The
oxidized mercury in flue gas can form a complex with the fly ash and then get removed
before the flue gas get out from the stack of the boiler.
53-2
Distinguishing Free Crystalline Quartz in Coal Fly Ash using
Electron Microscopy Techniques
Gerald Huffman, Nick Cprek, Naresh Shah, Frank Huggins, University of Kentucky,
USA
Determination of the amounts and classification of the types of silica contained in coal
fly ash is a subject of interest because of the adverse health effects caused by
inhalation of crystalline quartz. Workers with prolonged exposure to this carcinogen
can develop respiratory diseases over time. Here we examine crystalline quartz in coal
fly ash by computer controlled scanning electron microscopy (CCSEM).
Both the size and shape of the quartz particles are related to their toxicity. In the
present study, energy-dispersive x-ray (EDX) spectra identify quartz particles as those
that contain > 90% Si. CCSEM size distributions are then used to classify respirable
quartz particles as those having a mean particle diameter of < 4μm. Shape is also very
important since crystalline quartz particles will generally be more angular and
elongated than glassy SiO 2 particles. Such angular and/or elongated particles will more
readily penetrate cell walls to cause biological damage. In order to classify particle
shape quantitatively by CCSEM, we define another parameter called circularity.
Glassy ash particles are very often in the form of spheres, near-spheres, or at least
smooth equant particles. The parameter circularity is therefore defined as the ratio of
the radius determined from the particle perimeter to that obtained from the particle area
subtended by the electron beam. A perfect sphere would have a circularity of 1.
CCSEM data for these parameters for ~2,000 3,000 fly ash particles are then combined
into plots that display volume percentages of Si-rich particles as a function of size and
circularity. Regions of interest can be highlighted based on parameter definitions. On
the basis of a CCSEM examination of NIST K-411 Glass Microspheres standard
reference material, we conclude that SiO 2 glass particles have a circularity < 2. The
SiO 2 particles that are then classified as respirable quartz are those with mean
diameters < 4 µm and circularity >2. Based on our investigation of four power plant
ashes using this method, the percentage of the total SiO 2 particles that would be
classified as respirable quartz is relatively small and constitutes a very small fraction of
the total ash.
53-3
A Study on the Ash from Coal Gangue Fired Power
Plant-Characteristics and Application
Jianglong Yu, Hui Song, Shenyang Institute of Aeronauctical Engineering
Liping Chang, Wei Xie, Kechang Xie, Taiyuan University of Technology, P.R.
CHINA
Coal will continue to dominate China s energy supply in the future. The mining of coal
creates large amount of gangue which not only occupies a large area of land but also
generate environmental problems. On the other hand, coal gangue is a low calorific
fuel which should be utilized properly. A few small power plants are current running
or under construction in China. However, due to its high ash content, coal gangue
generates a large amount of ash when it is combusted in power plants. The ash from
power stations not only contributes to emissions of fine particulates in the air but also
results in the contamination of soil. The utilization of coal gangue ash is therefore
important to reduce China s environmental pollution. In this paper, current status of the
research and development of gangue ash utilization in China is reviewed. The gangue
ash has found its application in a wide range of areas, such as road construction,
chemicals, agriculture fertilizers, etc. Some ash samples were collected by the authors
from a coal gangue fired power plant in Fuxin, northeast China. Characteristics of the
ash were analyzed by using XRD, SEM, Laser sizer and other techniques. Because of
its physical structure (e.g., large surface area and porosity) and its composition (i.e.,
containing mainly SiO 2 , Al 2 O 3 and CaO) the gangue ash has a potential in the
application of iron-based sorbents for high temperature removal of hydrogen sulfide
from coal gas. A desulphurization sorbent was prepared by using the mixture of iron
oxide and the gangue ash collected from the power plant. The structure and property of
the surbent were examined using XRD, SEM and other techniques.
53-4
Flotoreagent on Base of the Products of the By-Product Coke Plant
Viktor Saranchuk, The Litvinenko L.M. Institute of Physical-Organic Chemistry and
Coal Chemistry, UKRAINE
Igor Arovin, Pilot-line Production, UKRAINE
Flotation method is used for enrichment of ordinary coal having small part less 0,5
mm. In connection with deficit of flotoreagent has got up the question about creation
flotoreagent on the base own non-deficit products and waste-products by-product coke
production. Such work was done in laboratory condition on flotomachine 240-FL-À.
As complex flotoreagent were trieded usual and formilin straw oil, polymers of
benzene department, formilin polymers, non-phenol butter, stillage bottoms and their
mixture. The best results are received when use formilin straw oil, on base which is
created flotoreagent UR-410. Efficiency of the work flotoreagent was explored on
charge of Avdeevka by-product coke plant.
53-5
Geology and Mineralogy of Coal and Combustible Shale World Deposits as a
Resources Forecast Basement of Energy-Chemical and Mineral Raw Materials in
View of Valuable and Potentiality Toxic Rare Elements it Contains
Mikhail Povarennykh, Russian Academy of Sciences, RUSSIA
Mikhail Shpirt, Institute of Fossil Fuels, Ministry of Natural Resources, RUSSIA
Inevitable in the nearest future exhausting of oil and gas deposits in view of the
modern constantly increasing industrial consumption forces us to pay maximum
attention to significantly more huge world resources of hard fossil fuels (HFF) (coals
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