内分级内返料喷浆造粒干燥机螺旋返料量研究

阐明了内分级内返料喷浆造粒干燥机中返料螺旋的返料机理，并对螺旋返料量的理论计算公式进行了修正。通过实验确定操作参数、结构参数对有效返料系数的影响。该研究对于内分级内返料喷浆造粒干燥机的设计有一定的指导作用     

AZF工艺返料质量对造粒的影响

返料是参与喷浆造粒工艺生产NPK复合肥造粒环节不可缺少的一部分。分析和讨论返料粒度分布、返料湿度和温度对造粒液固质量比、成粒率及造粒稳定性的影响。     

磷复肥喷浆造粒“三内”技术研究与开发(三)

介绍磷复肥喷浆造粒“三内技术”中的内返料技术、建立内返料计算式 ,探讨了返料数量对造粒的影响 ,为内返料装置的设计提供了理论依据     

喷浆造粒干燥窑的返料

喷浆造粒干燥窑的返料陈应斌（安徽铜陵磷铵厂）在磷铵生产过程中，要得到合格的成品粒子，可采用喷雾造粒、滚筒造粒、圆盘造粒、挤压造粒、管式反应造粒（实际上也是一种喷雾造粒）等几种方法。影响成品粒子的因素很多。其中返料是一个重要因素。下面就铜陵磷铵厂的喷浆...     

全内返料喷浆造粒干燥机研究进展

全内返料喷浆造粒干燥机是集喷浆、造粒、返料、分级、破碎于一体的高效设备,具有结构紧凑、单机生产能力大、单位能耗低、适应性强、工艺成熟等优点,在磷复肥等领域获得广泛应用。本文介绍了全内返料喷浆造粒干燥机研究进展及成果。     

内返料喷浆造粒干燥技术概述

内返料喷浆造粒干燥机集造粒、干燥、分级与破碎为一体 ,并广泛应用于化肥生产中。主要介绍了内返料喷浆造粒技术及其在国内外的发展过程     

内返料内分级喷浆造粒干燥机的返料分级机理研究Ⅵ．悬浮式螺旋进料口的有效返料系数的理论分析

本文研究内返料内分级喷浆造粒干燥机中悬浮式螺旋进料口的有效返料系数。推导出有效返料系数的计算式，讨论了螺旋进料口的悬浮高度、转筒半径和装载系数对有效返料系数的影响。     

轮碾挤压造粒生产中的常见故障及排除方法

近年来，不少复混肥厂采用轮碾挤压造粒工艺生产复混肥（见图１），取得了较好的经济效益和社会效益。轮碾挤压造粒与圆盘造粒相比具有以下优点：（１）生产无返料或返料很少，成粒率达９５％以上。（２）可选择价格低廉（以单位养分计）的碳铵、氯化铵、过磷酸钙等作原料...     

磷酸铵类肥料技术讲座第五讲喷浆造粒转筒干燥制粒状磷铵

这一讲主要介绍喷浆造粒转筒干燥制磷铵过程的成粒机理、分析造粒干燥过程的操作条件,以及揭示内返料和无外返料喷浆造粒干燥机的特点。此外还介绍了喷浆流化造粒干燥及喷霉干燥制粉状磷铵流程。     

内返料内分级喷浆造粒干燥机的返料分级机理研究 Ⅵ.悬浮式螺旋进…

本文研究内返料内分级喷浆造粒干燥机中悬浮式螺旋进料口的有效返料系数。推导出有效返料系数的计算式，讨论了螺旋进料口和悬浮高度、转筒半径和装载系数对有效返流系数的影响。     

The Role of Recycle in Countercurrent Recycle Distillation Cascades. I. Constant Reflux,Ideal, and Squared-Off Cascades

Abstract

In most textbooks concerned with countercurrent multistage separations, minimum reflux ratio for continuous distillation is usually defined only in terms of a graphical construction on a McCabe—Thiele diagram: it is the recycle ratio (liquid flow rate) associated with the operating line that touches the equilibrium curve at the feed point. However, it is easily shown that minimum recycle ratio depends on local α and composition, as well as product compositions, and thus, it is a stage-composition phenomenon. As a result, for a specified separation, each ideal stage in a continuous distillation cascade has a specific minimum recycle ratio associated with it. For constant α, the minimum recycle ratio increases as the stage compositions depart more from product (distillate or bottoms) compositions. As a result, the textbooks only consider the maximum minimum recycle ratio. This paper presents the results of some theoretical calculations which illustrate how minimum recycle ratio varies with stage α, stage and product compositions, and presents an example of distillation cascade behavior when minimum recycle ratio is approached at a composition other than the feed point. An example is also presented which shows how the separation is effected when the reflux ratio is reduced below the design value in a distillation column containing a fixed number of ideal stages. A brief comparison is also made between constant reflux, ideal, and squared-off cascades in terms of number of stages, total interstage flow, and relative energy requirements for the different designs to illustrate and emphasize the consequences of the stagewise behavior of minimum recycle ratio.     

有效微生物接种和渗滤液循环回流对垃圾降解的影响

Biodegradation of waste in landfill is a slow process requiring decades for completion. Accelerated degradation of municipal refuse in modulated landfill environments may alleviate or eliminate pollution to the land, water and air. In this work, nineteen effective microorganisms (EMs) were isolated from old landfill refuse by enrichment culturing techniques and used for the inoculum of municipal refuse. The preliminary experiments demonstrate that a combination of EMs inoculation in landfill with leachate recycle resulted in increased rates of decomposition and faster process stability. The concentrations of COD, VFA and SO4^2- in digester with EMs inoculation and leachate recycle decreased more rapidly than others. Gas production from digester with EMs inoculation and leachate recycle commenced around 32 days, which is a week shorter than with leachate recycle only. And peak cumulative gas production was obtained much earlier in digester with EMs inoculation and leachate recycle (150 days) compared to 180 days with leachate recycle only. Moreover, in the first two months, the rate of settlement in digester with EMs inoculation and leachate recycle was more rapid than others.     

Supercritical fluid recycle for surge control of CO2 centrifugal compressors

This paper presents computer-based design and analysis of control systems for centrifugal compressors when the operating fluid is supercritical CO₂.It reports a non-linear dynamic model including a main forward compression line and two different configurations for the recycle antisurge line. Disturbance scenarios are proposed for testing the configurations and performance indicators are suggested to evaluate control performance and power consumption of the compression system.The paper demonstrates that compared to the hot recycle, the process configuration including a cold gas recycle has better overall stability, but higher power consumption and lower values for the control performance indicators. Based on the previous considerations, the paper gives suggestions regarding the choice of the recycle configuration. Moreover it compares subcritical and supercritical compression during surge prevention and highlights the importance of the selection of the gas recycle configuration when full recycle is needed.     

On the effects of firing semi-anthracite and bituminous coal under oxy-fuel firing conditions

Traditional wisdom has lead to the design of a boiler being dictated by its fuel. Typically, lignite requires a large boiler to accommodate the moisture content and ash behaviour and anthracite needs a design with a long residence time to allow for complete combustion. Thus the result is that different boiler designs are required for different fuel types. This work demonstrates that it is possible to fire under oxy-fuel firing conditions different fuels in potentially a single combustion environment. In the present work a short series of scoping tests firing Russian semi-anthracite under air and oxy-fuel firing conditions on the RWEnpower Combustion Test Facility (CTF) have been performed and result compared to firing a South African bituminous coal. An IFRF swirl burner was used. The purpose behind this work was to determine whether oxy-fuel firing offered the potential for firing a wider range of coal qualities on a swirl stabilised burner than is conventional showing that stable combustion can be achieved with semi-anthracite as with bituminous coal. In this short communication, it is shown that this is possible. Flame photographs of the Russian semi-anthracite coal fired on air and under oxy-fuel firing conditions at recycle ratios of 75%, 72% and 68% were taken. The air firing condition produced a non-luminous flame in the near burner region. For oxy-fuel firing at 75% recycle ratio, the flame is also non-luminous and more so that the air firing case. When the recycle ratio is reduced from 75% to 68% the flame becomes increasingly luminous and at 68% an intense flame was observed well anchored into the burner quarl. Radiative heat flux measurements were taken with the Russian semi-anthracite coal at 68% recycle ratio and compared to the South African bituminous coal at 68% recycle ratio and on air. In general the peak in radiative heat flux for the Russian semi-anthracite at 68% recycle ratio compared to the South African bituminous coal on air is slightly higher reflecting the effect of oxygen enrichment and the higher calorific value of the semi-anthracite. It can also be observed that the location of the peak in radiative heat flux with Russian semi-anthracite coal at 68% recycle is displaced downstream. In the near burner region, the radiation intensity is lower for the Russian semi-anthracite at 68% recycle ratio compare to South African bituminous coal at 68% recycle ratio and on air reflecting the lower (but not insignificant) intensity of combustion in this region for the Russian semi-anthracite coal.     

Analysis of recycle system with selective recycling—II: Time-smoothed approximants

The residence time density of a recycle system is generally an oscillating function of time because of the lag between the cycles. In recycle system wiA general expression for a time-smoothed residence time density of recycle system with selective recycling, composed of pure time delays, is derived st     

Radiation and convective heat transfer, and burnout in oxy-coal combustion

Measurements of radiative and convective heat transfer, and carbon-in-ash have been taken on the RWEn 0.5 MWth combustion test facility (CTF) firing two different coals under oxy-fuel firing conditions. A 0.5 MWth scaled version of an IFRF Aerodynamically Air Staged Burner (AASB) was used under oxy-fuel firing conditions using simulated dry recycled flue gas. The two coals fired were a Russian Coal and a South African Coal.Recycle ratios were varied within the range of 65-75% dependent on coal. Furnace exit O₂ values were maintained at 3% and 6% for the majority of tests. Air firing tests were also performed to generate baseline data.The work described in the main text gives a comprehensive insight into the effect of oxy-fuel combustion on both radiative and convective heat transfer, and carbon-in-ash compared to air under dry simulated recycle conditions.Results have shown peak radiative heat flux values are inversely related to the recycle ratio for the two coals studied. Conversely, the convective heat flux values increase with increasing recycle ratio. It was also observed that the axial position of the peak in radiative heat flux moves downstream away from the burner as recycle ratio is increased.It has been shown that a “working range” of recycle ratios exist where both the radiative and convective heat fluxes are comparable with air.Carbon-in-ash (CIA) was measured for selected conditions. For air firing of Russian Coal, the CIA for follows and expected trend with CIA decreasing with increasing furnace exit O₂. The CIA data for the two recycle ratios of 72% and 68% for the same coal show that the CIA values are lower than for air firing for corresponding furnace exit O₂ levels and vary little with the value of furnace exit O₂.CIA measurements were taken for the South African Coal for a range of recycle ratios at 3% and 6% furnace exit O₂ levels. Results indicate that the CIA values are lower for higher furnace exit O₂ as would be expected. There appears to be a marginal general decrease in CIA as recycle ratio increases but it is suggested that at these generally low levels of CIA (i.e. < 0.7%) it is difficult to be conclusive.     

Effect of cholineacetyltransferase activity and choline recycle ratio on diffusion-reaction modeling,bifurcation and chaotic behavior of acetylcholine neurocycle and their relation to Alzheimer's and Parkinson's diseases

This paper is an extension of the previous two papers (Mustafa et al., 2009a, Mustafa et al., 2009b) on the modeling, simulation and analysis of bifurcation, dynamics, and chaotic characteristics of the acetylcholine (ACh) neurocycle. The effects of cholineacetyltransferase (ChAT) activity and choline recycle ratio as bifurcation parameters, on the system performance are studied through modifying the two-compartment model. It is found that as ChAT activity increases, ACh concentration in the model compartments increases continuously. The effect of choline recycle ratio shows that choline uptake represents the key role for providing choline as a substrate for ACh synthesis. It is found that the choline recycle ratio has a great influence on all state variables in both compartments. A detailed bifurcation and sensitive analyses over a wide range of ChAT activity and choline recycle ratio parameters are carried out in order to highlight the characteristics of ACh cholinergic system like non-linear dynamics and different solutions such as multiplicity of: stationery states as well as periodic and chaotic states. The relations between the results and the functions of ACh cholinergic neurons are investigated. A comparison between the results and other experimental and physiological measurements is performed. It is found that there is a good relation between cholinergic diseases such as Alzheimer's and Parkinson's diseases, and level of ACh in brains from one side and current results extracted from the disturbances in ChAT activity and choline recycle from the other side. It is found that choline recycled is the most critical factor in ACh processes in comparison with any of the following parameters: ChAT activity, as well as feed acetate and ACh concentrations.     

Residence-time distributions at high recycle ratios: Limiting forms obtained by increasing the recycle and by reducing the throughput

The residence-time density function for a recycle system tends to a limit as greater recycle ratios are considered for a fixed flow rate through the sy to a limit as smaller flow rates through the system are considered for a fixed recycle flow.If there is no part of the system through which the rate of transport is bounded when the recycle rate is increased for a constant net flow, the limiti of the system volume to the volumetric rate of flow through the system. When the rate of transport is bounded in some zone of the system, the limiting has an anomalous mean if transport ceases in a region of the system.Comparable rules can be advanced for the limiting distribution of normalized residence times when the net flow through the system is reduced at a const rates within the zones of the system and the net rate of transport through the system as the limit is taken. The presence of dead volume at this limitExamples are given of the several types of limit for systems where the rate of transport is limited by a flow-rate restriction in part of the system, a     

Transient behavior of recycle reactor with consecutive reaction

Experimental and theoretical transient behavior of a recycle system were studied for a plug flow reactor with a mixing tank and a recycle line. The consecutive reaction chosen for experimental study was the hydrolysis of diethyl succinate through monoethyl succinate to succinic acid on a strong acid ion exchange resin at 50°C. Both realistic and simplified models were developed to simulate the transient behavior of the recycle system. The simplified model was more useful than the realistic model because analytical solutions could be obtained. The approach time to the steady state is presented for the recycle reactor.     

ANALYSIS OF DIALYSIS IN CROSS-FLOW PARALLEL-PLATE MEMBRANE MODULES WITH FEED-STREAM RECYCLE FOR IMPROVED PERFORMANCE

The effect of external recycle on the performance of dialysis in cross-flow rectangular membrane modules with feed-stream recycle was investigated theoretically. The analysis of mass transfer in parallel-plate devices with and without recycle is analogous to heat transfer in parallel-plate heat exchangers. In contrast to a device without recycle, improvement in mass transfer is achievable if cross-flow parallel-plate dialysis is operated in a device of the same size with recycle, which provides increased fluid velocity, resulting in reduction of the mass-transfer resistance.