700 MW燃煤机组SCR运行适应性改造分析

目前大型燃煤电厂普遍采用选择性催化还原法脱硝工艺,其应用过程中存在由于机组调峰导致投运率不高的普遍问题。从脱硝反应过程和催化剂特性两方面出发,分析造成上述问题的原因,并根据省煤器结构及其换热特性,提出了两种不同的改进方案。通过对比择优,选择增设省煤器烟气旁路的改进措施,并提出相应的控制策略、安全性评估及其注意事项,可为同类型机组提供借鉴。     

Credible Enforcement Policies Under Illegal Fishing: Does Individual Transferable Quotas Induce to Reduce the Gap Between Approved and Proposed Allowable Catches?

In general, approved Total Allowable Catches (TACs) are higher than proposed TACs by the scientific assessment and reported landings approved are higher than approved TAC. We build a simple enforcement agency’s behavior model that generates—as a rational behavior—those two facts. The model has two ingredients. First, there exists illegal fishing generated by an imperfect enforcement technology; second, the enforcement agency cannot commit on announced penalties. We show that lack of commitment increases the potential benefits for national enforcement agency of deviating from proposal (scientific optimal) quotas. Although the enforcement agency wants to announce a low quota target to induce a low level of illegal harvest, it will find optimal to revise the quota announced in order to reduce penalties and improve fishermen welfare. Therefore, agencies find it optimal to approve higher quotas than that proposed by the scientific advice. Our main result is to show that when full compliance is not possible, and national agencies cannot commit, the introduction of Individual Transferable Quotas increases the potential benefits for agencies of deviating from the optimal proposed TAC by the scientific advised.     

Assessment of the emission of PCDD/Fs and dioxin-like PCBs from an industrial area over a nearby town using a selective wind direction sampling device

The development of new sampling devices or strategies to assess the concentration of persistent organic pollutants (POPs) in the environment has increased in the last two decades. In this study, a selective sampling device was used to evaluate the impact of potential local sources of polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/Fs) and dioxin-like polychlorinated biphenyl (dl-PCBs) emissions on the ambient air levels of such compounds in a town near an important industrial estate. Average concentrations of target compounds of up to 2.5 times for PCDD/Fs and 2 times for dl-PCBs were found to come from the industrial state confirming this area as the main responsible for the majority of such compounds reaching the town.This finding was supported by a PCDD/F and dl-PCB sample profile analysis and a principal component analysis (PCA), which established a direct link between the dioxin-like compounds found in the samples collected in the town and their source.     

Fish Traders as Key Actors in Fisheries: Gender and Adaptive Management

This paper fills an important gap towards adaptive management of small-scale fisheries by analyzing the gender dimension of fish trade in Zanzibar, Tanzania. We hypothesize that gender-based differences are present in the fish value chain and to test the hypothesis interviews were performed to analyze: (i) markets, customers, and mobility, (ii) material and economic resources, (iii) traded fish species, (iv) contacts and organizations, and (v) perceptions and experiences. Additionally, management documents were analyzed to examine the degree to which gender is considered. Results show that women traders had less access to social and economic resources, profitable markets, and high-value fish, which resulted in lower income. These gender inequalities are linked, among others, to women’s reproductive roles such as childcare and household responsibilities. Formal fisheries management was found to be gender insensitive, showing how a crucial feedback element of adaptive management is missing in Zanzibar’s management system, i.e., knowledge about key actors, their needs and challenges.     

The Regional Advisory Councils: What is Their Potential to Incorporate Stakeholder Knowledge into Fisheries Governance?

The protection of the Baltic Sea ecosystem is exacerbated by the social, environmental and economic complexities of governing European fisheries. Increased stakeholder participation and knowledge integration are suggested to improve the EU’s Common Fisheries Policy (CFP), suffering from legitimacy, credibility and compliance problems. As a result, the CFP was revised in 2002 to involve fisheries representatives, NGOs and other stakeholders through so called Regional Advisory Councils (RACs) in the policy process. We address the RAC’s task to incorporate stakeholder knowledge into the EU’s fisheries governance system in empirical and theoretical perspectives. Drawing on a four-stage governance concept we subsequently suggest that a basic problem is a mismatch between participation purpose (knowledge inclusion) and the governance stage at which RACs are formally positioned (evaluation of management proposals). We conclude that, if the aim is to broaden the knowledge base of fisheries management, stakeholders need to be included earlier in the governance process.     

Selective removal of diclofenac from contaminated water using molecularly imprinted polymer microspheres

A molecularly imprinted polymer (MIP) was synthesized by precipitation polymerization using diclofenac (DFC) as a template. Binding characteristics of the MIP were evaluated using equilibrium binding experiments. Compared to the non-imprinted polymer (NIP), the MIP showed an outstanding affinity towards DFC in an aqueous solution with a binding site capacity (Q_max) of 324.8 mg/g and a dissociation constant (K_d) of 3.99 mg/L. The feasibility of removing DFC from natural water by the MIP was demonstrated by using river water spiked with DFC. Effects of pH and humic acid on the selectivity and adsorption capacity of MIP were evaluated in detail. MIP had better selectivity and higher adsorption efficiency for DFC as compared to that of powdered activated carbon (PAC). In addition, MIP reusability was demonstrated for at least 12 repeated cycles without significant loss in performance, which is a definite advantage over single-use activated carbon.     

Assessing Fisheries – Using an Ethical Matrix in a Participatory Process

The Norwegian National Committee for Research Ethics inScience and Technology (NENT), collaborating with The NorwegianFisherman's Association and The Research Council of Norway,started in 1999 a project aiming at an ethical assessment of Norwegian fisheries for the year 2020. The project was to preparethe ground for ethical debate in and of the fishery sector inview of pending important decisions on long term strategies. Thispaper has its focus on the method used for achieving these aims,rather than the substantive results concerning the fisheries. Amethod was developed for this purpose, called the ethicalscenario process. This included the construction of scenarios forthe future of Norwegian fisheries, using an ethical matrix for evaluating strategies, and organizing a ``value workshop' whereparticipants from different stakeholder groups came together todo ethical evaluations. The positive achievements and theshortcomings of this method are discussed in this paper. The useof an ethical matrix was meant to combine a participatory approachwith insights from theoretical ethics. The project revealedinherent tensions between these two objectives. Possible ways ofdealing with this tension are indicated, but in general a goodgrasp of the socio-political context might be the best guardianagainst the possible pitfalls involved in such an approach.     

Unraveling SO2-tolerant mechanism over Fe2（SO4）3/TiO2 catalysts for NOx reduction

Developing low-temperature SO₂-tolerant catalysts for the selective catalytic reduction of NO_x is still a challenging task. The sulfation of active metal oxides and deposition of ammonium bisulfate deactivate catalysts, due to the difficult decomposition of the as-formed sulfate species at low temperatures（<300 °C）. In recent years, metal sulfate catalysts have attracted increasing attention owing to their good catalytic activity and strong SO₂ tolerance at hi...     

Mechanistic insights into the selective photocatalytic degradation of dyes over TiO2/ZSM-11

● TiO₂/ZSM-11 was prepared by a facile solid state dispersion method. ● Mechanism for photocatalytic degradation of dyes was investigated. ● Both experimental and MD simulations were conducted. ● Chemisorption instead of electrostatic interaction played a critical role. Photocatalytic degradation is a promising way to eliminate dye contaminants. In this work, a series of TiO₂/ZSM-11 (TZ) nanocomposites were prepared using a facile solid state dispersion method. Methyl orange (MO), methylene blue (MB), and rhodamine B (RhB) were intentionally chosen as target substrates in the photocatalytic degradation reactions. Compared to pristine TiO₂, negative effect was observed on MO degradation while promoted kinetics were collected on MB and RhB over TZ composites. Moreover, a much higher photocatalytic rate was interestingly achieved on RhB than MB, which indicated that a new factor has to be included other than the widely accepted electrostatic interaction mechanism to fully understand the selective photodegradation reactions. Systematic characterizations showed that TiO₂ and ZSM-11 physically mixed and maintained both the whole framework and local structure without chemical interaction. The different trends observed in surface area and the photo-absorption ability of TZ composites with reaction performance further excluded both as the promotion mechanism. Instead, adsorption energies predicted by molecular dynamics simulations suggested that differences in the adsorption strength played a critical role. This work provided a deep mechanistic understanding of the selective photocatalytic degradation of dyes reactions, which helps to rationally design highly efficient photocatalysts.     

NiB2O4 (B = Mn or Co) catalysts for NH3-SCR of NOx at low-temperature in microwave field

● Microwave-assisted catalytic NH₃-SCR reaction over spinel oxides is carried out. ● SCR reaction temperature is tremendously lowered in microwave field. ● NO conversion of NiMn₂O₄ is highly up to 90.6% at 70°C under microwave heating. Microwave-assisted selective catalytic reduction of nitrogen oxides (NO_x) was investigated over Ni-based metal oxides. The NiMn₂O₄ and NiCo₂O₄ catalysts were synthesized by the co-precipitation method and their activities were evaluated as potential candidate catalysts for low-temperature NH₃-SCR in a microwave field. The physicochemical properties and structures of the catalysts were characterized by X-ray diffraction (XRD), Scanning electron microscope (SEM), N₂-physisorption, NO adsorption-desorption in the microwave field, H₂-temperature programmed reduction (H₂-TPR) and NH₃-temperature programmed desorption (NH₃-TPD). The results verified that microwave radiation reduced the reaction temperature required for NH₃-SCR compared to conventional heating, which needed less energy. For the NiMn₂O₄ catalyst, the catalytic efficiency exceeded 90% at 70 °C and reached 96.8% at 110 °C in the microwave field. Meanwhile, the NiMn₂O₄ also exhibited excellent low-temperature NH₃-SCR reaction performance under conventional heating conditions, which is due to the high BET specific surface area, more suitable redox property, good NO adsorption-desorption in the microwave field and rich acidic sites.