Establishment of an Environmental Control Technology Laboratory with a Circulating Fluidized-Bed Combustion System

This report is to present the progress made on the project ''Establishment of an Environmental Control Technology Laboratory (ECTL) with a Circulating Fluidized-Bed Combustion (CFBC) System'' during the period October 1, 2005 through December 31, 2005. Work was performed on the following activities. First, the fabrication and manufacture of the CFBC Facility is nearly completed. The erection of the CFBC facility is expected to start in the second week of February, 2006. Second, effect of flue gas components on mercury oxidation was investigated in a drop tube reactor. As a first step, experiment for mercury oxidation by chlorine was investigated. The experimental results from this study are presented in this report. Finally, the proposed work for the next quarter is described in this report

Fusion characterization of biomass ash

The ash fusion characteristics are important parameters for thermochemical utilization of biomass. In this research, a method for measuring the fusion characteristics of biomass ash by Thermo-mechanical Analyzer, TMA, is described. The typical TMA shrinking ratio curve can be divided into two stages, which are closely related to ash melting behaviors. Several characteristics temperatures based on the TMA curves are used to assess the ash fusion characteristics. A new characteristics temperature, T-m, is proposed to represent the severe melting temperature of biomass ash. The fusion characteristics of six types of biomass ash have been measured by TMA. Compared with standard ash fusibility temperatures (AFT) test, TMA is more suitable for measuring the fusion characteristics of biomass ash. The glassy molten areas of the ash samples are sticky and mainly consist of K-Ca-silicates. (C) 2016 Elsevier B.V. All rights reserved.</p

Release of phosphorus from thermal conversion of phosphorus-rich biomass chars – Evidence for carbothermic reduction of phosphates

Biomass can be used to generate heat, power, or biofuels in thermal conversion processes such as combustion, gasification and pyrolysis. However, some types of biomass contain high levels of phosphorus, which can be released to the gas phase and cause operational or environmental problems. The mechanism(s) responsible for phosphorus release has not been convincingly established. Understanding the high-temperature phosphorus chemistry is also important in order to enable efficient recovery of phosphorus in residues from thermal conversion of biomass. In this work, the release of phosphorus from wheat bran char and sunflower seed char in different gas environments (100 % N2, 1–20 % O2, and 10 % CO2) and temperatures (900–1100 \ub0C) was studied. The chars were converted in a horizontal tube reactor and characterized using ICP-OES, XRD, SEM-EDS, and 31P NMR. The release of ash-forming elements was determined using ICP-OES analysis of the char and sample residues, whereas the release of carbon was determined using CO and CO2 gas analysis. In both chars, phosphorus was present primarily together with potassium and magnesium, mainly as pyrophosphates in the wheat bran char, and largely as orthophosphates in the sunflower seed char. For wheat bran char, the release of phosphorus increased from 27 % at 900 \ub0C to 71 % at 1100 \ub0C in N2, whereas the release was at least 20 % lower in the oxidizing atmospheres (1–20 % O2, or 10 % CO2). The sunflower seed char reached a maximum release of 55 % at 1100 \ub0C in N2. For wheat bran char, the molar ratio of released carbon/phosphorus was close to 2.5, which fits well with the theoretical value for carbothermic reduction of phosphates (P2O5(s, l) + 5C(s) → P2(g) + 5CO(g)). At 1100 \ub0C, in N2, the release of phosphorus, potassium and sodium occurred mainly during the first 10 min. It was shown that KMgPO4, used as a model compound, could be reduced by carbon starting from 950 \ub0C, but that some of the phosphorus remained in the condensed phase. The work provides a better understanding of phosphorus release and presents evidence showing that carbothermic reduction reactions can be an important phosphorus release mechanism for seed- and grain-based biomass char

Catalytic Cracking of Pyrolytic Vapors of Low-Rank Coal over Limonite Ore

Low-grade natural iron ore, limonite, is proposed as an inexpensive catalyst to increase the light liquid production from coal pyrolysis. Experiments were conducted at a pyrolyzer combined with gas chromatography/mass spectrometry (Py-GC/MS). It is found that limonite favors the formation of light aromatic hydrocarbons, while the aliphatics and oxygenated compounds in tar are significantly reduced. Tests with model compounds (C-19 alkane and o-cresol) indicate that the increased light aromatics could result from the conversions of either oxygenated compounds or aliphatics promoted by limonite. Gaseous products are determined with online gas chromatography (GC). A strong correlation between COx and light aromatics is revealed in the catalytic pyrolysis process, indicating that COx could be seen as an index of light aromatic formation. There is a maximum value for the yield of liquids when the temperature is increased, which is quite different from the tests without limonite. It is postulated that pyrolytic water is decreased with the temperature because the total tar yield exhibits an increasing trend.</p

Study on the conversion of CaCl2 with H2O and CO2 for dechlorinating pyrolysis of municipal solid waste

In a pyrolysis-combustion combined process for treatment of municipal solid waste (MSW), the removal of HCl from the volatile before combustion, with a calcium-based absorbent has been broadly investigated, but the conversion of CaCl2 as the reverse reaction of the absorption of HCl has seldom been reported. In this work, the conversion of CaCl2 with H2O and CO2 (main products from pyrolysis of MSW) in the temperature range of 350 degrees C-650 degrees C is studied by fixed-bed experiments and thermodynamic analysis. The results show that the conversion of CaCl2 increases with the increase of temperature and with the increasing contents of CO2 and H2O. Comparatively, the impacts of CO2 and H2O are both stronger in lower temperatures, and the influence of H2O is more distinct than that of CO2. The existence of H2O is a prerequisite for the conversion of CaCl2, and the component of CO2 is promotive to the reaction of CaCl2

Two-step catalytic co-pyrolysis of walnut shell and LDPE for aromatic-rich oil

A novel two-step catalytic co-pyrolysis (TSCCP) process is proposed through coupling advantages of conventional two-step catalytic pyrolysis (TSCP) and one-step catalytic co-pyrolysis (OSCCP) for producing aromaticrich oil using walnut shell (WNS) and LDPE as feedstock. Co-pyrolysis of three WNS components (hemicellulose, cellulose and lignin) with LDPE are performed to validate the necessity and rationality of TSCCP. And effects of first step pyrolysis temperature (T1) and residence time (Rt1) on product distributions of TSCCP are investigated. When T1 and Rt1 are 550 degrees C and 7.5 s respectively, the oil yield is increased by 59.1% and 15.7% respectively compared with that of conventional TSCP and OSCCP. The selectivity toward aromatics is as high as 82.5%, and the selectivity of oxygenates is reduced to less than 1%. The excellent results of TSCCP are attributed to preventing secondary reactions led by higher temperature for hemicellulose and cellulose components, the enhanced conversion due to activation effect from lignin component, and the synergetic effect between WNS-derived oxygenates and LDPE-derived hydrocarbons

Study on the conversion of CaCl2 with H2O and CO2 for dechlorinating pyrolysis of municipal solid waste

In a pyrolysis-combustion combined process for treatment of municipal solid waste (MSW), the removal of HCl from the volatile before combustion, with a calcium-based absorbent has been broadly investigated, but the conversion of CaCl2 as the reverse reaction of the absorption of HCl has seldom been reported. In this work, the conversion of CaCl2 with H2O and CO2 (main products from pyrolysis of MSW) in the temperature range of 350 degrees C-650 degrees C is studied by fixed-bed experiments and thermodynamic analysis. The results show that the conversion of CaCl2 increases with the increase of temperature and with the increasing contents of CO2 and H2O. Comparatively, the impacts of CO2 and H2O are both stronger in lower temperatures, and the influence of H2O is more distinct than that of CO2. The existence of H2O is a prerequisite for the conversion of CaCl2, and the component of CO2 is promotive to the reaction of CaCl2

Process simulation of mineral carbonation of phosphogypsum with ammonia under increased CO2 pressure

The mineral carbonation of phosphogypsum offers many advantages in sequestering CO2, solving the pollution problem of phosphogypsum stacking, and manufacturing high value-added chemical products with low energy consumption and cost. Using the Aspen Plus process simulation software, this work simulates a novel process for the mineral carbonation of phosphogypsum with ammonia under increased CO2 pressure. This process is divided into five sections, namely, pre-carbonation, enhanced carbonation, flash separation, gas phase absorption, and (NH4)(2)SO4 fertilizer production. With its large-scale application, this new process allows the sensitivity analysis of many operation conditions, identifies the optimal conditions for reducing the ammonia and energy consumption of (NH4)(2)SO4 fertilizer production, and achieves a high carbonation conversion with a fast reaction rate. The optimal conditions (6 bar enhanced carbonation pressure, 1 bar flash pressure, 38 degrees C ammonia absorption solution temperature, 1.05 ammonia excess ratio, 1.024 CO2 excess ratio, and 0.94 mass ratio of water to gypsum) yield the highest carbonation conversion, ammonia utilization ratio, and enhanced carbonation temperature of 99.9%, 95.2%, and 138.5 degrees C, respectively, all of which can help achieve a fast carbonation reaction rate. (C) 2016 Elsevier Ltd. All rights reserved.</p

Pyrolysis of Huadian oil shale under catalysis of shale ash

The influence of shale ash on the pyrolysis of Huadian oil shale was investigated. It was found that under the catalysis of shale ash, aliphatics in shale oil were partially converted to aromatics, and the long-chain aliphatics were converted to shorter ones. This effect could be improved by increased content of shale ash or by augmented temperature. Beyond the Diels-Alder reaction for the formation of aromatics, a novel reaction route of cyclization of aliphatics followed by dehydrogenation to aromatics was proposed. The component of CaO in shale ash plays an important role to the general performance of shale ash. (C) 2016 Elsevier B.V. All rights reserved.</p

investigationoftheaccelerationregioninagassolidcocurrentdownflowcirculatingfluidizedbed

In this work, a mathematical model is established to describe the axial variation of the characteristic flow parameters (particle velocity, solid holdup and pressure gradient) in a downer. An empirical correlation is developed to estimate the particle velocity at the constant velocity section. Experimental investigations are made to validate the downer model. The model simulations have a good agreement with experimental data. Moreover, a formula is derived to predict the first acceleration section length and the whole acceleration section length