石灰石-石膏法脫硫設(shè)備
Limestone-gypsum method
一． 概述
Summary of a.
石灰石-石膏濕法煙氣脫硫工藝是目前應(yīng)用泛的一種脫硫技術(shù)，其基本工藝流程如下：
Limestone-gypsum wet flue gas desulfurization technology is currently the most widely used a desulfurization technology, the basic process is as follows:
鍋爐煙氣經(jīng)電除塵器除塵后，通過增壓風機、GGH(可選)降溫后進入吸收塔。在吸收塔內(nèi)煙氣向上流動且被向下流動的循環(huán)漿液以逆流方式洗滌。循環(huán)漿液則通過噴漿層內(nèi)設(shè)置的噴嘴噴射到吸收塔中，以便脫除SO2、SO3、HCL和HF，與此同時在“強制氧化工藝”的處理下反應(yīng)的副產(chǎn)物被導(dǎo)入的空氣氧化為石膏（CaSO4•2H2O），并消耗作為吸收劑的石灰石。循環(huán)漿液通過漿液循環(huán)泵向上輸送到噴淋層中，通過噴嘴進行霧化，可使氣體和液體得以充分接觸。每個泵通常與其各自的噴淋層相連接，即通常采用單元制。
Boiler flue gas after the electric dust, through the booster fan, GGH (optional) after cooling into the absorption tower. In the absorption tower flue gas flows up and is downward flow of slurry by countercurrent washing cycles. Circulating slurry is set up through the shotcrete layer of nozzle to the absorption tower, so that the removal of SO2, SO3, HCL and HF, and at the same time under the processing of "forced oxidation process" reaction by-products are imported air oxidation of gypsum (CaSO4 • 2 h2o), ａnd consume as absorbent of limestone. Circulating slurry through the slurry circulating pump up to the spray layer, through the nozzle atomization, can be used to good contact with gas and liquid. Each pump is usually connected with their respective spray layer, the system usually adopt unit.
在吸收塔中，石灰石與二氧化硫反應(yīng)生成石膏，這部分石膏漿液通過石膏漿液泵排出，進入石膏脫水系統(tǒng)。脫水系統(tǒng)主要包括石膏水力旋流器（作為一級脫水設(shè)備）、漿液分配器和真空皮帶脫水機。
經(jīng)過凈化處理的煙氣流經(jīng)兩級除霧器除霧，在此處將清潔煙氣中所攜帶的漿液霧滴去除。同時按特定程序不時地用工藝水對除霧器進行沖洗。進行除霧器沖洗有兩個目的，一是防止除霧器堵塞，二是沖洗水同時作為補充水，穩(wěn)定吸收塔液位。
In the absorption tower, gypsum, limestone and so2 reacts this part of the gypsum slurry by gypsum slurry pump discharge, entering the gypsum dewatering system. Dehydration system mainly includes the gypsum hydrocyclone (as a level 1 dewatering equipment), the slurry distributor and vacuum belt dryer.
After purification treatment of flue gas flow through the two levels of demister mist, here will clean the slurry droplets carried by flue gas in the removal. At the same time, according to the specific program of demister with process water from time to time to wash. Demister irrigation has two purposes, one is to prevent the demister blocked, 2 it is to wash water as make-up water at the same time, the steady absorption tower level.
在吸收塔出口，煙氣一般被冷卻到46—55℃左右，且為水蒸氣所飽和。通過GGH將煙氣加熱到80℃以上，以提高煙氣的抬升高度和擴散能力。
In the absorption tower export, flue gas is cooled to 46-55 ℃ or so commonly, and saturated by water vapor. Through the GGH heat of flue gas to 80 ℃ above, in order to improve the lifting height and diffusion ability of flue gas.
最后，潔凈的煙氣通過煙道進入煙囪排向大氣。
Finally, clean through stack into the chimney flue gas into the atmosphere.
石膏法的主要優(yōu)點是：適用的煤種范圍廣、脫硫效率高、吸收劑利用率高、設(shè)備運轉(zhuǎn)率高、工作的可靠性高、脫硫劑—石灰石來源豐富且廉價。
Main advantage of gypsum method is: the applicable range, high desulfurization efficiency of coal, high utilization rate of absorbent, equipment operation rate, high reliability, high desulfurization agent, the limestone source is rich and cheap.
二． 工藝流程
2. Process
來自于鍋爐或窯爐的煙氣經(jīng)過除塵后在引風機作用下進入吸收塔，吸收塔為逆流噴淋空塔結(jié)構(gòu)，集吸收、氧化功能于一體，上部為吸收區(qū)，下部為氧化區(qū)，經(jīng)過除塵后的煙氣與吸收塔內(nèi)的循環(huán)漿液逆向接觸。系統(tǒng)一般裝3-5臺漿液循環(huán)泵，每臺循環(huán)泵對應(yīng)一層霧化噴淋層。當只有一臺機組運行時或負荷較小時，可以停運1-2層噴淋層，此時系統(tǒng)仍保持較高的液氣比，從而可達到所需的脫硫效果。吸收區(qū)上部裝二級除霧器，除霧器出口煙氣中的游離水份不超過75mg/Nm3。吸收SO2后的漿液進入循環(huán)氧化區(qū)，在循環(huán)氧化區(qū)中，亞硫酸鈣被鼓入的空氣氧化成石膏晶體。同時，由吸收劑制備系統(tǒng)向吸收氧化系統(tǒng)供給新鮮的石灰石漿液，用于補充被消耗掉的石灰石，使吸收漿液保持一定的pH值。反應(yīng)生成物漿液達到一定密度時排至脫硫副產(chǎn)品系統(tǒng)，經(jīng)過脫水形成石膏。
From the boiler or furnace flue gas after dust under the action of induced draft fan into the absorption tower, absorption tower for counter-current spray air tower structure, integrating absorption and oxidation function, upside is absorbing area, lower for the oxidation zone, after cleaning cycle of the gas and absorption tower in slurry reverse contact. System commonly 3-5 slurry circulating pump, each corresponding to a layer of circulation pump atomization spray layer. When only one unit operation or the load is small, can shut down the 1-2 spray layer, the system still keep high liquid gas ratio, which can achieve the required desulfurization effect. Absorption area upper secondary demister, demister, the free water in the outlet flue gas does not exceed 75 mg/Nm3. After absorbing SO2 slurry into the circulation oxidation zone, in cyclic oxidation zone, calcium sulfite oxidation by blowing air into gypsum crystals. At the same time, absorbed by the sorbent preparation system to supply fresh limestone slurry oxidation system, used to supplement the burn limestone, keep absorbing slurry pH value. Product size reaches a certain density to the by-product desulphurization system, forms through dehydration gypsum.
工藝流程圖
Process flow diagram
三． 技術(shù)特點
3. Technical characteristics
石膏法脫硫是濕法脫硫的一種。
Wet desulphurization gypsum desulphurization is one of the most commonly used.
但是石灰石/石膏法的缺點也是比較明顯的：初期投資費用太高、運行費用高、占地面積大、系統(tǒng)管理操作復(fù)雜、磨損腐蝕現(xiàn)象較為嚴重、副產(chǎn)物—石膏很難處理（由于銷路問題只能堆放）、廢水較難處理。
But the shortcoming of limestone/gypsum method is obvious: the high cost of initial investment, operating cost is high, covers an area of big, complex system management operation, wear corrosion phenomenon is relatively serious, by-product gypsum difficult to handle (as sales problems can only be stacked), wastewater more difficult.
該技術(shù)與拋棄法的區(qū)別在于向吸收塔的漿液中鼓入空氣，強制使CaSO3都氧化為CaSO4(石膏），脫硫的副產(chǎn)品為石膏。同時鼓入空氣產(chǎn)生了更為均勻的漿液，易于達到90%的脫硫率，并且易于控制結(jié)垢與堵塞。由于石灰石價格便宜，并易于運輸與保存，因而自8 0年代以來石灰石已經(jīng)成為石膏法的主要脫硫劑。當今國內(nèi)外選擇火電廠煙氣脫硫設(shè)備時，石灰石/石膏強制氧化系統(tǒng)成為優(yōu)先選擇的濕法煙氣脫硫工藝。
The technology and abandon the difference between the absorber slurry in the blowing air and force CaSO3 oxidation to CaSO4 (gypsum), a by-product of desulfurization gypsum. While blowing air produced more homogeneous slurry, easy to achieve 90% desulfurization efficiency, and easy to control fouling and plugging. Due to limestone is cheap and easy to transport and to save, so since 8 0 s limestone has become the main method of gypsum desulfurization agent. Today's choosing a coal-fired power plant flue gas desulfurization equipment at home and abroad, the limestone/gypsum forced oxidation system become wet flue gas desulfurization technology of choice.
采用石灰石或石灰作為脫硫吸收劑，石灰石經(jīng)破碎磨細成粉狀與水混合攪拌成吸收漿液，當采用石灰為吸收劑時，石灰粉經(jīng)消化處理后加水制成吸收劑漿液。在吸收塔內(nèi)，吸收漿液與煙氣觸混合，煙氣中的二氧化硫與漿液中的碳酸鈣以及鼓入的氧化空氣進行化學反應(yīng)從而被脫除，最終反應(yīng)產(chǎn)物為石膏。
Using limestone/lime as desulfurization absorbent, lime writing broken ground into powder mixed with water to form a absorption of serous, when using lime as absorbent, lime powder after digestion treatment made absorber slurry water. Within the absorption tower, absorption of touch the mixed slurry and flue gas, sulphur dioxide in flue gas with the calcium carbonate in the slurry and the oxidation of blowing air for chemical reaction to be removal, the final reaction products of gypsum.
