酸氫鈉為吸附劑的干法吸附工藝已成為一個煙氣凈化手段，用于去除煙氣中所含的各種污染物。其凈化效果可與已知的其它方式相比，如采用石灰乳為吸附劑的噴霧吸附法。干法煙氣凈化不僅可用于煤電廠、垃圾或替代燃料焚燒廠，還可廣泛地用于玻璃、水泥、冶金等行業(yè)的工業(yè)爐。采用干法煙氣凈化可以經(jīng)濟地達到煙氣排放標準
The dry adsorption process with sodium hydrogen carbonate as adsorbent has become a means of flue gas purification to remove various pollutants contained in flue gas. The purification effect can be compared with other known methods, such as the spray adsorption method using lime milk as adsorbent. Dry flue gas purification can be used not only in coal power plants, waste or alternative fuel incineration plants, but also in industrial furnaces in glass, cement, metallurgy and other industries. Using dry flue gas purification can economically meet the flue gas emission standard
碳酸氫鈉用于煙氣脫硫的基本原理
Basic principle of sodium bicarbonate for flue gas desulfurization
碳酸氫鈉（小蘇打， NaHCO3）可以用作煙氣脫硫的吸附劑。它通過化學吸附去除煙氣中的酸性污染物，同時，它還可通過物理吸附去除一些無機和微量物質(zhì)。此工藝將碳酸氫鈉細粉直接噴入高溫煙氣。在高溫下碳酸氫鈉分生成碳酸鈉Na2CO3、H2O和CO2。
Sodium bicarbonate (baking soda, NaHCO3) can be used as adsorbent for flue gas desulfurization. It can remove acidic pollutants in flue gas through chemical adsorption. At the same time, it can also remove some inorganic and trace substances through physical adsorption. In this process, the fine sodium bicarbonate powder is directly sprayed into the high-temperature flue gas. Sodium bicarbonate is divided into sodium carbonate Na2CO3, H2O and CO2 at high temperature.
新產(chǎn)生的碳酸鈉Na2CO3在生成瞬間有高度的反應** ，可自發(fā)地與煙氣中的酸性污染物進行下列反應
The newly produced sodium carbonate Na2CO3 has a high degree of reaction * * at the moment of formation, and can spontaneously react with the acid pollutants in the flue gas
一般情況下，煙氣溫度在140和250 °C之間。由于碳酸氫鈉吸附劑的高度**，通常略微過量的碳酸氫鈉（化學計量因子在1.1和1.3之間）就足夠 。
In general, the flue gas temperature is between 140 and 250 ° C. Due to the high * * of sodium bicarbonate adsorbent, a slight excess of sodium bicarbonate (stoichiometric factor between 1.1 and 1.3) is usually sufficient.
原則上碳酸鈉（蘇打，Na2CO3）也可用于煙氣脫硫。碳酸鈉的反應**稍低，但工藝流程幾乎不變。本文對碳酸鈉脫硫不作進一步闡述。
In principle, sodium carbonate (soda, Na2CO3) can also be used for flue gas desulfurization. The reaction * * of sodium carbonate is slightly lower, but the process flow is almost unchanged. The desulfurization of sodium carbonate is not further described in this paper.
由于運輸和存儲的原因，碳酸氫鈉原料通常是粗顆粒（d50值約為200微米）。如要達到較高的反應性，吸附劑需要有較大的比表面積。因此在注入煙氣管道前，碳酸氫鈉研磨至一定細度。比如，要去除SO2碳酸氫鈉細度須達到d90 < 20 µm。而去除HCl只要求d90 < 35 µm。如果系統(tǒng)操作正確，可以去除95%以上的SO2；HCl的去除率甚至可達 99%。
Due to transportation and storage, the raw material of sodium bicarbonate is usually coarse particles (D50 value is about 200 microns). In order to achieve high reactivity, the adsorbent needs to have a large specific surface area. Therefore, before injecting into the flue gas pipe, the sodium bicarbonate shall be ground to a certain fineness. For example, to remove SO2, the fineness of sodium bicarbonate must reach D90 < 20 & micro; m。 For HCl removal, only D90 < 35 & micro; m。 If the system is operated correctly, more than 95% SO2 can be removed; The removal rate of HCl can even reach 99%.
為了在長期操作中保持所需的碳酸氫鈉細度，通常采用帶分級機的沖擊磨，亦稱分級磨，如ZJ-C分級式?jīng)_擊磨。研磨后，吸附劑以氣體輸送方式運輸并通過多個噴嘴直接通入煙氣管道，以保證其在管道內(nèi)均勻分散。這套設備設計簡單耐用，與其它煙氣凈化方式相比，它的投資和運營成本均較低。
In order to maintain the required fineness of sodium bicarbonate in long-term operation, impact mill with classifier, also known as grading mill, such as zj-c grading impact mill, is usually used. After grinding, the adsorbent is transported by gas transportation and directly connected to the flue gas pipeline through multiple nozzles to ensure its uniform dispersion in the pipeline. The design of this equipment is simple and durable. Compared with other flue gas purification methods, its investment and operation cost are low.
是常規(guī)負壓流程的示意圖，在此流程中碳酸氫鈉從貯罐(A)通過一臺螺旋輸送機
This is a schematic diagram of the conventional negative pressure process in which sodium bicarbonate passes through a screw conveyor from the storage tank (a)
(1)定體積地供給下游的分級磨 (2)所需的吸附劑的量可由脫硫前后的污染物濃度趨勢曲線計算，并通過變頻器對螺旋輸送機進行控制。在螺旋輸送機和分級磨之間須安裝旋轉(zhuǎn)閥，用于隔離氣流，以免氣流影響螺旋輸送機的定量進料。碳酸氫鈉在分級磨中進行研磨后，細粉由一臺物料輸送風機(3)氣體輸送至煙氣管道(B)。
(1) The amount of adsorbent required by the downstream grading mill (2) can be calculated from the pollutant concentration trend curve before and after desulfurization, and the screw conveyor is controlled by the frequency converter. A rotary valve must be installed between the screw conveyor and the grading mill to isolate the air flow so as not to affect the quantitative feeding of the screw conveyor. After the sodium bicarbonate is ground in the graded mill, the fine powder is transported to the flue gas pipe (b) by a material conveying fan (3).
此操作模式中的積垢問題經(jīng)常是討論的焦點。設備的清洗，特別是物料輸送風機的清洗過于耗時。此外，在開機和關機過程中風機葉輪上的積垢還可能剝落，導致風機的振動及其運轉(zhuǎn)狀態(tài)的振蕩。
The crud problem in this operation mode is often the focus of discussion. The cleaning of equipment, especially the cleaning of material conveying fan, is too time-consuming. In addition, the scale on the fan impeller may peel off during startup and shutdown, resulting in the vibration of the fan and the oscillation of its operating state.
因此考慮由負壓流程改為正壓流程。在新的工作模式下風機安裝在分級磨之前，將工藝空氣壓入研磨系統(tǒng)。這種工作模式的優(yōu)點是研磨后的碳酸氫鈉不通過風機運輸，完全避免了風機的積垢問題。此外，風機的耗電也有所降低，使經(jīng)營成本更低
Therefore, it is considered to change from negative pressure process to positive pressure process. In the new working mode, the fan is installed before the grading mill, and the process air is pressed into the grinding system. The advantage of this working mode is that the ground sodium bicarbonate is not transported through the fan, which completely avoids the scaling problem of the fan. In addition, the power consumption of the fan is also reduced, making the operating cost lower
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