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英文翻譯原文 Characteristics of coal mine ventilation air flows CSIRO Exploration and Mining, P.O. Box 883, Kenmore, Qld 4069, Australia Abstract Coal mine methane (CMM) is not only a greenhouse gas but also a wasted energy resource if not utilised. Underground coal mining is by far the most important source of fugitive methane emissions, and 70% of all coal mining related methane is emitted to the atmosphere through mine ventilation air. Therefore, research and development on mine methane mitigation and utilisation now focuses on methane emitted from underground coal mines, in particular ventilation air methane (VAM) capture and utilisation. To date, most work has focused on the oxidation of very low concentration methane. These processes may be classified based on their combustion kinetic mechanisms into thermal oxidation and catalytic oxidation. VAM mitigation/utilisation technologies are generally divided into two basic categories: ancillary uses and principal uses. However, it is possible that the characteristics of ventilation air flows, for example the variations in methane concentration and the presence of certain compounds, which have not been reported so far, could make some potential VAM mitigation and utilisation technologies unfeasible if they cannot cope with the characteristics of mine site ventilation air flows. Therefore, it is important to understand the characteristics of mine ventilation air flows. Moreover, dust, hydrogen sulphide,sulphur dioxide, and other possible compounds emitted through mine ventilation air into the atmosphere are also pollutants. Therefore,this paper presents mine-site experimental results on the characteristics of mine ventilation air flows, including methane concentration and its variations, dust loadings, particle size, mineral matter of the dust, and other compounds in the ventilation air flows. The paper also discusses possible correlations between ventilation air characteristics and underground mining activities. 2006 Elseier Ltd. All rights reserved. Keywords: Coal mine methane; Greenhouse gas; Waste energy; Dust emission; Hydrogen sulphide; Sulphur dioxide; Characteristic parameters 1. Introduction Coal mine methane (CMM) is not only a greenhouse gas but also a wasted energy resource if not utilised. In 2000, it was estimated that the world total of methane emitted from mine ventilation air was over 237 Mt CO2-e, and that ventilation air methane (VAM) derived power projects could theoretically create 3GWe of net usable capacity (US EPA, 2003). Underground mining is by far the most important source of fugitive methane emissions, and _70% of all coal mining related methane is emitted through underground mine ventilation air, rather than as more highly concentrated drainage gas in advance of or immediately after mining (Moore et al., 1998; Sloss, 2005). Therefore, research and development on mine methane mitigation and utilisation now focuses on methane emitted from underground coal mines, especially VAM capture and utilisation, because (1) it represents most of the methane emission from coal mines; and (2) it is most difficult to capture and use as the air volume is large and the methane resource is dilute and variable in concentration and flow rate. To date, most work has focused on the oxidation of very low concentration methane. These processes may be classified based on their combustion kinetic mechanisms into thermal oxidation and catalytic oxidation. VAM mitigation/utilisation technologies are generally divided into two basic categories: ancillary uses and principal uses。No matter what technologies have been/are being developed for the ancillary and principal uses of VAM, an important issue related to the implementation of these technologies at mine sites has been ignored, namely the characteristics of the mine ventilation air flows. The characteristics, including dust loading, particle size, mineral matters of the dust, variations in methane concentration and flow rate, and other compounds (H2S and SO2), could make a potentia VAM mitigation and utilisation technology unfeasible if it cannot cope with the characteristics of mine site ventilation air flows. Therefore, it is important to understand the characteristics of mine ventilation air flows. Moreover, dust, H2S, SO2, and other possible compounds emitted through mine ventilation air into the atmosphere are also pollutants To gather this information and measure the levels of these emissions, an isokinetic particle sampling system was specifically designed and constructed, which met coal mine intrinsic safety requirements and suited the mine ventilation air shafts. Field sampling trials at four mines were carried out, and dust and gas samples were analysed using a variety of techniques. This paper presents the mine-site experimental results on characteristics of mine ventilation air flows, including methane concentration and its variations, dust loadings, particle size/distribution, mineral matter of the dust, and other compounds in the ventilation air flows. The paper also discusses possible correlations between ventilation air characteristics and underground mining activities. 2. Experiments 2.1. Isokinetic sampling system and sampling procedure To develop an isokinetic dust sampling system suited to mine ventilation air shafts, it is necessary to understand mine ventilation air shafts and major isokinetic sampling principles before designing and fabricating the isokinetic sampling train, in particular one which can meet coal mine intrinsic safety requirements. Since there remained many unknowns at the outset, the design had to be readily adaptable to the various flow speeds, port sizes and dust loadings at each site. The data collection was done in collaboration with four mines located in eastern Australia, designated mines A, B, C and D. At each mine the vertical ventilation air shaft (upcast shaft) was topped with a 901 elbow which redirected the ventilation air flow horizontally. The flow was split into two or three branches, each with its own fan and evasee. Following preliminary mine site visits it was concluded that the most suitable sampling locations were near the upcast shaft collars because in each case the shafts were fitted with several sampling ports at a convenient height, and the ports provided access to the entire ventilation air flow before it was branched. A sampling train with an in-stack collector is superior to out-stack collection as the latter is susceptible to dust deposition inside the sampling tube. The nozzle and probe of an out-stack collector need to be thoroughly washed with a solution to remove any particulate matter stuck to the tube and nozzle according to AS 4323.2-1995 (Standards Australia, 1995a), and the washed particles should be counted in the calculation of dust loading for each sample as discussed later. However, since the sampling ports on the ventilation air shafts of most of the mines were smaller than the particulate filter holder, out-stack collection was required. The relative humidity of the ventilation air in most of these mines was about 70–100%, however probe heating to prevent moisture deposition was not necessary because the ventilation air temperature was less than the ambient air temperature. Therefore, the sampling train selected for the mine site trials corresponded to Type D in AS 4323.2-1995 (Standards Australia, 1995a). It was a general-purpose configuration, which provided maximum flexibility for sampling at different mines and was capable of out-stack sampling (Refer Fig. 1). The dust isokinetic sampling procedure was based on AS 4323.1-1995 (Standards Australia, 1995b) and US EPA Method 5. Before the sampling can begin, a velocity profile for the shaft needs to be determined. This is achieved by using a type S Pitot tube (US EPA Method 5) at designated points in the shaft which are referenced by marks on the probe. Once this data is collected a suitable nozzle that gives the desired sampling rate can be selected based on the velocity profile. The reference marks on the Pitot probe also need to be transferred to the sampling probe to ensure that samples are collected at the same points. The system was checked for leaks to confirm that all seals were working after the sampling train was assembled and before every sampling run. At this point, the temperature and humidity inside the shaft and of the atmosphere were measured and the sample run was ready to begin. With the correct nozzle attached and a clean filter in the filter holder the probe was inserted into the shaft with the nozzle pointing into the flow. The probe was then secured at its first sampling point and the main pump was turned on and the main valve opened. A timer was started to keep track of when the probe needed to be moved to the next sampling point. Once all systems were running the rotary meter was adjusted to the desired flow rate to achieve isokinetic flow. The sampling train was now running and collected data over the specified time period, normally 1 h. At each time interval the probe was moved to the next point, checked and secured. At the end of the specified time the pump was turned off and the main valve closed. First the filter needed to be carefully removed and placed into its assigned Petri dish. Then the probe was removed from the shaft for cleaning. The probe was then washed with a dilute solution of a cleaning agent to remove any particulate matter stuck to the tube and nozzle. This solution was stored in a labelled container for filtration at the laboratory. Once the probe was thoroughly washed it was dried by passing dry nitrogen through it. Once these steps were completed the system was ready for the next sampling run. It should be pointed out that the dust loading was determined from dusts both deposited on the filter paper and washed from inside the tube and nozzle. It was not possible to select sampling plane positions which met the ideal sampling criteria specified in Australian Standard 4323.1-1995 (Standards Australia, 1995b). Hence, the non-ideal sampling plane position, as defined in the Standard, was attempted. However, this still required three sampling traverses and six access holes to performt isokinetic sampling process. Unfortunately, the number of available access holes at mine sites was often fewer because some were either occupied for permanent monitoring equipment, located too close to the surrounding structures, or the plugs rusted in place. As a result, the isokinetic sampling process was not usually fully compliant with the Standard at the mine sites. Therefore, best practise for the mine site sampling was that dust samples were taken from 10 sampling points of an accessible radius. 2.2. Analytic techniques Besides the above-described isokinetic sampling train used for the determination of dust loadings, some analytic techniques used for the analysis of dust and gas samples are summarised here. Optical microscopy and scanning electronic microscopy (SEM) were used to determine maximum particle size for each sample. SEM with energy dispersive spectrum (SEM-EDS) was used to analyse 24 typical dust samples (six per mine) so an understanding of the dust samples could be achieved in terms of the mineral matter (coal particles, stone particles, etc.). Micro Gas Chromatography was used to analyse the gas bag samples as necessary. A multi-gas monitor (iTX), based on the principle of catalytic diffusion and electrochemistry, was attached to the isokinetic sampling train and used to measure CH4, CO, H2S and SO2 concentrations. Its measuring ranges for CH4, CO, H2S and SO2 were 0–5%, 0–999 ppm, 0–999 ppm and 0.2–99.9 ppm, respectively. The gas monitor was calibrated before each run by using a calibration gas of 2.5% CH4, 100 ppm CO, 25 ppm H2S, and 5 ppm SO2 3. Conclusions This paper presented mine-site experimental results on characteristics of mine ventilation air flows, including methane concentration and its variations, dust loadings, particle size, mineral matter of the dust, and other compounds in the ventilation air flows. The major characteristic parameters are summarised in Table 1, and interesting findings are given below. Mine A: This mine was the most humid of the four mines. The ventilation air was saturated (100% relative humidity). Results showed little correlation between mine production and the dust loading. This could be due to the many water droplets observed circulating in the upcast shaft acting as a spray scrubbing system for the ventilation air. The maximum measured dust particle size in the ventilation air outlet was 5 mm. SEM-EDS results showed that the dust samples consisted mostly of coal particles and stone particles. H2S and SO2 concentrations were less than 1 ppm. Some CO spikes were captured during sampling which could have been from vehicular activity during the shift change. It is interesting to note that this mine was the first in the world to commercially use VAM as an ancillary fuel source. However, it is not used anymore because the amount of particulate matter in the air required constant replacement of the air filters, resulting in high costs. Mine B: This mine had measured relative humidities of 85–100%. Dust samples collected during mine production were visibly darker than those collected during nonproduction. Analysis showed that the dark dust samples contained more coal particles than the grey/white dust samples collected during non-production. Therefore, the mine production rate affected the dust composition in this mine. Also the data indicated that the higher the mine production rate, the higher the dust loading in this mine. H2S and SO2 concentrations were less than 1 ppm. No CO spikes were observed, in contrast with mine A. The data collected by the mine methane monitoring system were consistent with our measurements. Mine C: This mine is not a gassy mine, and the relative humidity was low at 74.5–83.5%. The mine produced coal every day during the sampling period. There was a small correlation between coal production and dust loading. It is interesting to note that, based on the SEM-EDS results, some sulphur was retained in the coal particles. This may imply a technical issue that when such mine ventilation air is directly fed into a catalytic oxidation system without filtration, the sulphur could poison the catalysts. H2S and SO2 concentrations were less than 1 ppm. No CO spikes were captured during sampling. The methane concentration of ventilation air was very low for this mine compared with the other three mines. The average methane concentration in the ventilation air was only 0.09%, hence any existing and developing VAM mitigation/utilisation technologies would not be suitable for this mine. Mine D: The relative humidity of the ventilation air at this mine was 73–99.8%. There was little correlation between the dust emissions and mine production rate, potentially because of stone dusting during non-production periods. This is supported by SEM-EDS examination results which showed that the dust collected when there was no mine production contained few coal particles. H2S and SO2 concentrations were less than 1 ppm. CO spikes as high as 28 ppm were captured during shift changes, and may have been caused by diesel equipment being started. The methane concentration of the ventilation air was relatively high, 1.01% on average. This means that the methane in ventilation air from this mine is relatively easy to mitigate and utilise. It is very interesting to note that, compared with the other three mines, the effect of mine production on the methane concentration of the ventilation air was significant. For example, when there was no production on 5 and 6 March 2005, the average methane concentration halved to 0.5%. General remarks: In general, mines A, B and D are gassy mines. All have drainage gas systems (at least postdrainage gas practise, i.e. degasification after coal mining, at the mine sites). Mine C is not a gassy mine with an average methane concentration of 0.09% in the ventilation air. In conclusion, for all the mines investigated in this paper the dust samples consisted of coal particles and stone particles. When there was no mine production, the dust samples contained few coal particles. When the dust samples were collected during mine production, they contained many coal particles. Moreover, the data presented in this paper provide basic information for selection, assessment, and development of ventilation air cleaning technology and VAM mitigation and utilisation technology. Variations in methane concentration and ventilation air flow rate need to be considered carefully when choosing appropriate technology. 中文翻譯 礦井通風空氣的流動特點 澳大利亞聯(lián)邦科學與工業(yè)研究組織的勘探和開采 摘要 煤礦瓦斯（ CMM ）的不僅是一種溫室氣體，而且如果沒有充份利用的話，也是一種被浪費掉的能源。地下采煤是迄今為止最重要的甲烷排放的來源。煤炭開采過程中，70%的甲烷通過礦井通風系統(tǒng)被排放到空氣中。因此，目前關于礦井瓦斯減少和利用的研究和開發(fā)，重點是地下煤礦中的瓦斯排放，特別是對礦井通風中的甲烷（ VAM）的收集和運用。到目前為止，大多數工作的重點是對低濃度的甲烷進行氧化。依據燃燒的動力學機制，這些過程被劃分為熱氧化和催化氧化。有關礦井通風中甲烷的消減和使用的工藝，一般被分為兩個基本類別：主要用途和輔助用途。通風過程中空氣流動的特點，極有可能成為影響這些過程的主要方面。例如，不同濃度的甲烷或目前未知且存在的某些化合物，如果它們和礦址處空氣流動特點不一致，將有可能使一些理論上的礦井瓦斯削減和利用技術變得不可行。因此，徹底弄清楚礦井通風系統(tǒng)中空氣的流動特點，顯得格外重要。此外，灰塵，硫化氫，二氧化硫，以及其他可能的化合物，也會通過礦井通風被傳播進大氣，產生污染。因此，本文介紹了煤礦現場實驗結果的特點，包括甲烷濃度及其變化，粉塵荷載，顆粒大小，礦物的問題，灰塵，及其他化合物在通風的空氣流動。該文件還討論了空氣流動的特點和地下采礦活動之間的相關性。 2006年Elseier有限公司保留所有權利。 關鍵詞：煤礦甲烷;溫室氣體;浪費能源;粉塵的排放量;硫化氫;二氧化硫;特性參數 1 .引言 煤礦甲烷（ CMM ），如果沒有被充分利用的話，不僅是一種溫室氣體，而且是一種被浪費掉能源。在2000年，據估計，全世界通過礦井通風系統(tǒng)排入大氣中的甲烷總量超過2億3千7百萬噸。另外，與通風空氣中排放的甲烷相比，動力企業(yè)理論上能創(chuàng)造3倍體積的甲烷排放量（美國環(huán)保局， 2003年） 。地下開采是迄今為止最重要的甲烷排放途徑。全球煤炭開采過程中，70%的甲烷是通過地下礦井通風系統(tǒng)被排放入大氣，而不是被作為更高度的排放氣體被利用。（穆爾等人， 1998年; sloss ， 2005年） 。因此，關于礦井瓦斯減少和利用的研究和發(fā)展，目前的重點就是地下煤礦的瓦斯排放，特別是對礦井瓦斯的捕捉和利用。因為（ 1 ）它代表了從地下采煤過程中排放的瓦斯量（ 2 ）由于風量大，而且甲烷濃度的隨時變化 ，收集和利用工作變得極為困難。到目前為止，大多數工作的重點是對非常低濃度的甲烷進行氧化。依據燃燒的動力學機制，這些過程被劃分為熱氧化和催化氧化。有關礦井通風中甲烷的消減和使用的工藝，一般被分為兩個基本類別：主要用途和輔助用途。關于礦井瓦斯，無論什么樣的技術，什么樣的用途，正在或者已經被開發(fā)，一個重要的問題已被忽略，那就是礦井通風系統(tǒng)的空氣流動的特點。它包括粉塵載荷，顆粒大小，礦塵特征，甲烷的濃度變化和流速，以及其他化合物（硫化氫和二氧化硫），這些如果不能很好的與礦井通風網絡的流量相配合，作為還處于萌芽狀態(tài)的礦井瓦斯削減和利用技術，將會變得不可實行。因此，徹底弄清楚礦井通風系統(tǒng)中空氣的流動特點，顯得格外重要。此外，灰塵，硫化氫，二氧化硫，以及其他可能的化合物，也會通過礦井通風被傳播進大氣，產生污染。為了收集這方面的資料和衡量各種級別的排放量，專門設計和建造一個等速粒子采樣系統(tǒng)，該系統(tǒng)符合煤礦本質安全的要求和礦井通風系統(tǒng)。實地取樣試驗在四個礦井進行，采用多種技術，對采樣粉塵和氣體進行分析。關于礦井通風系統(tǒng)的空氣流動的特點，進行了實驗。本文介紹了煤礦現場實驗的結果，包括甲烷濃度及其變化，粉塵荷載，顆粒尺寸及分布，灰塵，及其他化合物在通風的空氣流動。該文件還討論了礦井通風的的特點和地下采礦活動之間的可能相關性。 2.實驗 2.1 .等速取樣系統(tǒng)和取樣程序 如果設計和制造一等速粉塵采樣系統(tǒng)與礦井通風系統(tǒng)的風井相適應，就有必要了解礦井通風系統(tǒng)的風井和主要等速采樣原則，特別是這種系統(tǒng)需要能滿足煤礦本質安全的要求。由于仍然存在著許多未知因素，在一開始，設計要易于適應每個場所各種流量的速度，口徑尺寸和塵埃載荷。數據收集工作，在設在澳大利亞東的四個礦井進行，分別編號為A， B ， C和D。在每一個礦井，垂直通風井（提升井）都與水平管道相連接。這些管道能夠使流通空氣在水平方向上分為兩到三個分支。每個分支都有它自己的風扇和風筒 。根據煤礦初步實地考察，得出的結論是最合適的抽樣地點是靠近通風井的井頸處。因為在每一種情況，井筒在適宜的高度分別裝有數個采樣管口?？諝庠诜植嬷?，均有可能進入每個管道。 采樣器在抽樣車內部比在外部更加優(yōu)越，因為后者容易受到在取樣管內沉積的灰塵影響。外裝采樣器的噴嘴與探針，必須徹底清洗，以消除任何黏附在管道和管口的物質。（澳洲標準協(xié)會， 1995年） ，被清洗掉的粒子也應該作為每個樣品的粉塵負荷，在最后的計算中被考慮在內。 不過，由于在多數礦井中，采樣端口通常都遠遠小于空氣過濾器的端口。因此，多數情況下，采用外裝的空氣采樣器。在實驗的多數礦井中，雖然相對空氣濕度多為70-100 ％ ，但完全沒有必要對探針加熱，以防止水分沉積。因為通常情況下，通風空氣的溫度遠遠低于周圍空氣的溫度。因此，在各礦井選定的抽樣車應符合D型號的要求。澳大利亞第4323.2標準（澳洲標準協(xié)會， 1995年） 首先介紹一種多用途的裝置，它有足夠的彈性，能在不同的礦井，最大限度的滿足采樣要求。粉塵等速采樣器，就是基于這種裝置而設計出來的。 采樣之前，井筒的速度剖面圖需要提前制定出來。這就需要用S型皮托管（美國環(huán)保局的方法5 ）在井筒的指定地點進行測量，而這些點需要被做上標記，以方便以后的探針測量。 一旦在管口收集到的數據，恰能滿足根據流速剖面圖所預期的采樣率。在皮托管上的某位置的標記，也必須在探針所連接的管子上作同位置標記，以確保探針的樣本在同一位置收集。 在采樣列車組裝之后，每一個采樣運行。該系統(tǒng)開始檢查皮托管是否漏水，以確認所有的封條都合格，在檢查漏水的系統(tǒng)工作同時，井筒內大氣的溫度和濕度也在同時被測量，采樣工作即將開始。 在選定的管口，試驗者套上合適的皮管并連接一個干凈的過濾器。探針被深入井筒內流動的空氣。 在第一個采樣點，由于主要通風機和主閥門全部被打開，所以，采樣的數據是精確可靠的。當采樣結束時，專職測時間的人通知將探頭轉移到下一個采樣點。 一旦所有系統(tǒng)運行起來，各種工作的閥門均被調節(jié)，以到理想的等速流動。 抽樣車運行和收集數據均在指定的時間內完成，通常為1 小時。在每一個時間段結束時，探頭被準確無誤地轉移到了下一個點。在規(guī)定的事件結束時，風井和主閥門同時被關閉。過濾器小心地被拆除掉，采樣的空氣被納入其指定的器皿中。 然后探頭從井筒內移走并清洗。用裝有特種清潔劑的稀溶液清洗探針，以消除任何附著在皮托管里和噴嘴處的顆粒物。在實驗室清洗下來的溶液被過濾，并存放在一個帶有標簽的容器內。探針徹底清洗結束后，放入干燥的氮氣中自然風干。一旦這些步驟完成，該系統(tǒng)也就已經做好了準備，進行下一次的采樣。 應該指出的是，粉塵載荷量是由沉積在濾紙上的粉塵和從皮托管內和噴嘴處洗滌的粉塵兩部分決定的。 在澳大利亞，選擇平坦的空地，以盡可能的滿足理想的試驗標準是完全沒有可能的。因此，現實中，通常用非理想的采樣條件代替理想的規(guī)定標準。 不過，在等速采樣過程中，仍需要三個采樣斷面和6個觀察孔來確保采樣的順利進行。不幸的是，在多數試驗礦井中，觀察孔的位置多數裝有檢測設備或者已經生銹的電源。 因此，通常情況下，在礦井上的等速采樣過程是不完全符合標準的。因此，最好的解決方法是從粉塵樣品選取由10個