1、中 南 大 學本科生畢業論文(設計)題 目年產4萬噸合成氨全中變換工序工藝學生姓名 指導教師 學 院 湖南化工職業技術學院 專業班級 化 工 0615 完成時間 2010年10月9日 年產4萬噸合成氨全中變變換工序工藝設計任務書一、設計項目：合成氨廠變換工序工藝設計二、設計規模：4 三、設計階段：初步設計四、設計時間 2010年 10月28日 2010年 11月9 日五、設計條件：1、原料（半水煤氣）規格： 組成 v%(干) 38.0 22.0 30.0 8.3 1.5 0.2 100.0半水煤氣入系統（入飽和塔）溫度為：502、產品規格出變換工序氣體中 3.5%（干）；變換氣出系統溫度353

2、、生產方式：加壓變換 半水煤氣進系統壓力：0.8mpa；系統壓差0.05mpa 4、地區條件：湖南5、觸媒型號：中變催化劑（型號自選）6、其他條件：外加蒸汽1.0mpa飽和或過熱蒸汽（過熱溫度為300）。六、設計成果：1、設計說明書一份2、帶控制點的工藝流程圖（中變流程）3、設備平面布置圖七、設計主要參考文獻：1、梅安華主編.小合成氨廠工藝技術與設計手冊上冊、下冊，北京：化學工業出版社.19952、化工（含輕工）類畢業設計指導書.北京：中央廣播電視大學出版社，19863、周大軍主編，化工制圖.北京：化學工業出版社.20054、陳聲宗主編，化工設計.北京：化學工業出版社.20015、天津大學化工

3、原理教研室編.化工原理上冊、下冊，北京：化學工業出版社.2000目 錄1前言 12工藝條件 23工藝流程的確定 34主要設備的選擇說明 35對本設計的評述 26英文翻譯 4第一章 變換工段物料及熱量衡算 8第一節 中溫變換物料及熱量衡算 811確定轉化氣組成81.2水汽比的確定 91.3中變爐一段催化床層的物料衡算 101.4中變爐一段催化床層的熱量衡算 101.5中變爐催化劑平衡曲線 111.6最佳溫度曲線的計算 111.7操作線計算 121.8中間冷淋過程的物料和熱量計算 121.9中變爐二段催化床層的物料衡算 121.10中變爐二段催化床層的熱量衡算 131.11中變爐三段催化劑床層的物

4、料衡算 141.12中變爐三段催化床層的熱量衡算 15第二節 中變爐的物料與熱量計算 17第三節 廢熱鍋爐的熱量和物料計算 18第四節 主換熱器的物料與熱量的計算 20第五節 調溫水加熱器的物料與熱量計算 22第二章 設備的計算 231. 中溫變換爐計算 232. 飽和熱水塔計算 273主熱交換器計算 30參考文獻及致謝 34前 言氨是一種重要的化工產品，主要用于化學肥料的生產。我國合成氨工業的發展情況解放前我國只有兩家模不大的合成氨廠，解放后合成氨工業有了迅速發展。1949年全國氮肥產量僅0.6萬噸，而1982年達到1021.9萬噸，成為世界上產量最高的國家之一。近幾年來，我國引進

5、了一批年產30萬噸氮肥的大型化肥廠設備。我國自行設計和建造的上海吳涇化工廠也是年產30萬噸氮肥的大型化肥廠。這些化肥廠以天然氣、石油、煉油氣等為原料，生產中能量損耗低、產量高，技術和設備都很先進。合成氨生產經過多年的發展，現已發展成為一種成熟的化工生產工藝。合成氨的生產主要分為：原料氣的制取；原料氣的凈化與合成。粗原料氣中常含有大量的c，由于co是合成氨催化劑的毒物，所以必須進行凈化處理，通常，先經過co變換反應，使其轉化為易于清除的co2和氨合成所需要的h2。因此，co變換既是原料氣的凈化過程，又是原料氣造氣的繼續。最后，少量的co用液氨洗滌法，或是低溫變換串聯甲烷化法加以脫除。變換工段是指

6、co與水蒸氣反應生成二氧化碳和氫氣的過程。在合成氨工藝流程中起著非常重要的作用。工藝原理：一氧化碳變換反應式為：co+h2o=co2+h2+q (1-1) co+h2 = c+h2o (1-2) 其中反應（1）是主反應，反應（2）是副反應，為了控制反應向生成目的產物的方向進行，工業上采用對式反應（11）具有良好選擇性催化劑，進而抑制其它副反應的發生。一氧化碳與水蒸氣的反應是一個可逆的放熱反應，反應熱是溫度的函數。變換過程中還包括下列反應式：h2+o2=h2o+q工藝條件1.壓力：壓力對變換反應的平衡幾乎沒有影響。但是提高壓力將使析炭和生成甲烷等副反應易于進行。單就平衡而言，加壓并無好處。但從動

7、力學角度，加壓可提高反應速率。從能量消耗上看，加壓也是有利。由于干原料氣摩爾數小于干變換氣的摩爾數，所以，先壓縮原料氣后再進行變換的能耗，比常壓變換再進行壓縮的能耗底。具體操作壓力的數值，應根據中小型氨廠的特點，特別是工藝蒸汽的壓力及壓縮機投各段壓力的合理配置而定。一般小型氨廠操作壓力為0.7-1.2mpa,中型氨廠為1.21.8mpa。本設計的原料氣由小型合成氨廠天然氣蒸汽轉化而來，故壓力可取1.7mpa.2.溫度：變化反應是可逆放熱反應。從反應動力學的角度來看，溫度升高，反應速率常數增大對反應速率有利，但平衡常數隨溫度的升高而變小，即 co平衡含量增大，反應推動力變小，對反應速率不利，可見

8、溫度對兩者的影響是相反的。因而存在著最佳反應溫對一定催化劑及氣相組成，從動力學角度推導的計算式為tm= 式中tm、te分別為最佳反應溫度及平衡溫度，最佳反應溫度隨系統組成和催化劑的不同而變化。3.汽氣比：水蒸汽比例一般指h2o/co比值或水蒸汽/干原料氣.改變水蒸汽比例是工業變換反應中最主要的調節手段。增加水蒸汽用量，提高了co的平衡變換率，從而有利于降低co殘余含量，加速變換反應的進行。由于過量水蒸汽的存在，保證催化劑中活性組分fe3o4的穩定而不被還原，并使析炭及生成甲烷等副反應不易發生。但是，水蒸氣用量是變換過程中最主要消耗指標，盡量減少其用量對過程的經濟性具有重要的意義，蒸汽比例如果過

9、高，將造成催化劑床層阻力增加；co停留時間縮短，余熱回收設備附和加重等，所以，中（高）變換時適宜的水蒸氣比例一般為：h2o/co=35，經反應后，中變氣中h2o/co可達15以上，不必再添加蒸汽即可滿足低溫變換的要求。工藝流程確定:目前的變化工藝有：中溫變換，中串低，全低及中低低4種工藝。本設計選用中變工藝。以煤為原料的中小型氨廠制得的半水煤氣中含有較高的一氧化碳,需采用多段中變流程.而且由于出脫硫塔系統的半水煤氣溫度與水蒸氣含量較低,氣體在進入中變爐之前設有原料氣預熱及增濕裝置.另外,由于中變的反應量大,反應放熱多,應充分考慮反應的移熱和余熱回收半水煤氣首先進入飽和熱水塔1,在飽和塔內氣體與

10、塔頂噴淋下來的130-140的熱水逆流接觸,使半水煤氣提高增濕。出飽和塔的氣體進入氣水分離器2分離夾帶的液滴,并與蒸汽過熱器5送來的300-500的過熱蒸汽相混,使半水煤氣中的汽氣比達到工藝條件的要求,然后進入主熱交換器3和中間換熱器4,使氣體溫度升至380進入變換爐,經第一段催化床層反應后溫度升到480-500,經蒸汽過熱器,中間換熱器與蒸汽,半水煤氣換熱,降溫后進入第二段催化床層反應.反應后的高溫氣體用冷凝水冷凝降溫后,進入第三段催化劑床層反應.氣體離開變換爐的溫度為400左右,變換氣依次經過主熱交換器,第一水加熱器,熱水塔,第二熱水塔第二水加熱器回收熱量,再經變換氣冷卻器9降至常溫后送到

11、下一工序.主要設備的選擇說明:中變流程中，主要設備有中變爐、飽和熱水塔,換熱器等。中變爐選用b109型催化劑，計算得中變催化劑實際用量10.59m3。以上設備的選擇主要是依據所給定的合成氨系統的生產能力、原料氣中碳氧化物的含量以及變換氣中所要求的co濃度。對本設計評述半水煤氣變換工段工序是合成氨生產中的第一步，也是較為關鍵的一步，因為能正常生產出合格的壓縮氣，是后面的所有工序正常運轉的前提條件。因此，必須控制一定的工藝條件，使轉化氣的組成，滿足的工藝生產的要求。在本設計中，根據已知的半水煤氣組成，操作條件，采用了全中變的工藝流程路線。首先對中變進行了物料和熱量衡算，在計算的基礎上，根據計算結果

12、對主要設備選型，最終完成了本設計的宗旨。設計中一共有中變爐，主換熱器，調溫水換熱器，飽和熱水塔,中間換熱器幾個主要設備。由于半水煤氣變換工段工序是成熟工藝，參考文獻資料較多，在本設計中，主要參考了小合成氨廠工藝技術與設計手冊和合成氨工藝學這兩本書。由于時間有限，設計可能不完善，請各位老師指出。謝謝！英文翻譯 forewordammonia is an important chemical products, mainly for the production of chemical fertilizers. china's industrial ammonia development

13、of the liberation of our country, only two small ammonia plant, after the liberation of synthetic ammonia industry has developed rapidly. national production of nitrogen fertilizer in 1949 only 06,000 tons, and in 1982 reached 10,219,000 tons, the world's highest output of one of the countries.

14、in recent years, china has introduced a number of annual output of 300,000 tons of large-scale nitrogen fertilizer plant equipment. china's self-designed and built by shanghai and jiangsu jing is also a chemical plant with an annual output of 300,000 tons of large-scale nitrogen fertilizer plant

15、. these chemical fertilizer plant to natural gas, oil and gas refining, and other raw materials for the production of low-energy loss, high oammonia production after years of development, has grown into a mature chemical production process. the main ammonia production is divided into: gas in the pre

16、paration of raw materials; raw materials and synthetic gas purification. crude materials often contain a large number of gas c, is the co due to the ammonia catalyst poison, so the need for purification treatment, usually, the first after a co shift reaction to make it easier to translate into the r

17、emoval of synthetic ammonia and co2 needed to h2. therefore, co conversion of raw materials is both a gas purification process and a feed gas to the gas. finally, the co with a small amount of washing liquid ammonia, or low-temperature method to transform serial methanation removal. transform sectio

18、n refers to the co and water vapor to form carbon dioxide and hydrogen. in the process ammonia plays an important role.utput, all-the-art technology and equipment.at present, the transformation section of the main changes in the use of low-string change process, which is developed in the mid-80'

19、s. change in the so-called string of low-flow changes, such as the b107 is the fe-cr catalyst after the string into the department of co-mo temperature shift catalyst. changes in the string of low-change process, as the catalyst for broad changes to the series, operating conditions there have been l

20、arger. on the one hand into the furnace of the steam to a greater degree than has been reduced; on the other hand, transform the gas content of co also significantly reduced. since the change in the string after a wide catalyst for change, so that the operating system's increased operating flexi

21、bility, so that transform the system easy to handle, but also significantly reduced its energy consumption.principles of technology:co-shift reaction:co + h2o = co2 + h2 + q (1-1)co + h2 = c + h2o (1-2) one response (1) is the main reaction (2) is a side effect, in order to control the reaction to g

22、enerate a product aimed at the direction of the industrial use of the reactor (1-1) has a good catalyst for selective and thus inhibit other side effects from happening. the reaction of water vapor and carbon monoxide is a reversible exothermic reaction, reaction heat is a function of temperature.in

23、 the process of transformation include the following reaction:h2 + o2 = h2o + q1 conditions. pressure: pressure on the balance shift reaction is almost no effect. but the pressure to increase will generate methane and carbon analysis of side effects such as easy. one-on balance, the pressure to do s

24、o. but from the perspective of dynamics, the pressure may increase the response rate. from energy consumption, the pressure is also beneficial. as the dry feed gas moore is less than the number of dry gas conversion moore, therefore, be carried out after the feed gas compression transformation of en

25、ergy consumption, atmospheric pressure than the further transformation of energy consumption at the end of compression. pressure on the value of specific operations, according to the characteristics of small and medium-sized ammonia plant, in particular the process of steam and pressure for the comp

26、ressor section of the rational distribution of pressure. general small-scale ammonia plant operating pressure for the 0.7-1.2mpa, medium-sized ammonia plant for 1.2 1.8mpa. the design of the feed gas from small-scale ammonia plant from steam reforming of natural gas, it is desirable pressure 1.7mpa.

27、2. temperature:changes in the exothermic reaction is reversible. kinetics from the point of view, temperature, the rate constant for the reaction rate increases beneficial, but constant balance with the temperature and smaller, that is, the balance of co content increased, the driving force smaller

28、response, the response a negative rate, the temperature can be seen on both the impact to the contrary. there is therefore the best response for a certain temperature and gas composition of the catalyst, derived from the point of view of the dynamics calculation for -tm =in-tm, te-were the best reac

29、tion temperature and the temperature balance, the best response with the temperature and composition of the catalyst systems vary.    gas than steam:the proportion of water vapor h2o/co generally refers to the ratio of water or steam / dry feed gas. to change the ratio of water vapor in in

30、dustrial transformation in response to the most important means of regulation. increase the amount of water vapor, co increased the rate of transformation of the balance, which will help to reduce the residual co content to accelerate the transformation of the reaction carried out. due to the existe

31、nce of excess water vapor, the catalyst to ensure the stability of the active component fe3o4 not be restored, and analysis of carbon and methane generation, and other side effects occur easily. however, the amount of water vapor in the process of transformation is the most important indicator of co

32、nsumption, to minimize the amount of the economic process of great significance, if the ratio of steam too, will result in increased resistance to the catalyst bed; co stop time, waste heat recovery equipment add to chime in with, and so on, so in the (high) suitable for conversion when the ratio of

33、 water vapor in general: h2o/co = 3 5, by the reaction after the change in gas h2o/co up more than 15, do not have to add steam to to meet the low temperature conversion.process to determineat present, there are changes in technology: the temperature change in the low strings, all low and low techno

34、logy 4. design of the sichuan zigong honghe reference to the chemical production process, the selection process in the low strings. transformed into gas from the furnace into the waste heat boiler, waste heat boiler in the transformation of gas from 920 down to 330 , the waste heat boiler exports by

35、 adding water to make steam vapor than the gas to reach 3-5, after re-entering the change in the gas furnace will be converted in the concentration of carbon monoxide dropped to below 3%. through heat exchangers to convert the gas temperature dropped to about 180 , the furnace will be changed into t

36、he low conversion of carbon monoxide gas content down to below 0.3 percent, from re-entering the methanation section.the main equipment of choicelow-flow changes in the series, the major equipment change in the furnace, the low variable furnace, waste heat boiler, heat exchanger, and so on. change f

37、urnace selection of low-c6 catalyst, a catalyst changes the calculation is too low, the actual amount of 10.59m3. over the choice of equipment is mainly based on the given systems ammonia production capacity, feed gas carbon oxide content as well as the transformation of gas required by the co conce

38、ntration.design of the commentssection natural gas conversion process is the first step in the production of synthetic ammonia, but also a more crucial step, because the normal ability to produce qualified compressed gas, is behind all the processes a prerequisite for the normal operation. it is the

39、refore necessary to control certain conditions, so that the conversion of gas, to meet the requirements of the production process.in this design, on the basis of known natural gas, operating conditions, using a string variable in the process of changing the low road. first of all, changing, low had

40、a balance of materials and energy, on the basis of the calculation, according to the results of the major equipment selection, the final design of the purposes. a total of design in temperature waste heat boiler, the change in the furnace, the main exchangers, heat exchanger water temperature, low-f

41、urnace several major equipment change. due to natural gas conversion process is the section maturity process, more information on references, in the design of the main reference of the "small ammonia plant technology and design manual" and "ammonia technology," these two books. d

42、ue to time constraints, the design may be imperfect, teachers pointed out. thanks!第一章 變換工段物料及熱量衡算第一節 中溫變換物料衡算及熱量衡算1.1已知條件及計算結果：（1）半水煤氣的組成（干）表1 半水煤氣的組成（干）組 分co2coh2n2ch4o2合 計%8.330.038.022.01.50.2100(標)274.73993.001257.8728.249.656.623310kmol12.26544.33056.15232.5092.2170.296147.768（2）壓力進工段煤氣壓力0.8mpa

43、(表)進工段蒸汽壓力為1.0mpa（表）（3）溫度進系統半水煤氣溫度 50進中變爐一段催化劑氣體溫度 300出系統那個變換氣溫度 35精煉來循環水溫度 84出系統變換氣（干）中co含量 3.5%（4）計算基準以1t氨為計算基準年產4萬噸合成氨生產能力：日生產量：40000/300=133.337t/d=5.56t/h要求出中變爐的變換氣干組分中co小于3.5工藝計算流程圖如圖1-1-1所示1.2中溫變換爐物料及熱量計算（1）干變換氣量及變換率的計算設氧與氫在變換爐一段催化劑內完全燃燒生成水，由 +2 =2 知，實際參加co變換反應的半水煤氣量為 3310-3 =3310-6.62×3

44、=3290.14 （標）co總變換率為 x= 式中 x= =85.41%  則 =3290.14×(1+85.41%×30.18%)=4138.23 （標）co變換總量： 3290.14×30.18%×85.41%=848.05 （標）=37.86kmol變換氣中co量 3290.14×30.18%848.05=144.91 （標）=6.47kmol（2）總蒸汽比計算設低溫變換爐出口變換氣溫度為252，平衡溫距取36，t252+36288co變換反應式為 co+ 設 a b c d 則 a=30 b=8.3 d=38co反應量 co=

45、30×85.41%=25.623 （標）co100干半水煤氣由查小合成氨廠工藝技術與設計手冊表4-2-6得288時 =47.39= = =47.39解得 b=39.61 即汽氣=39.61：100上式中 為煤氣中氨的濃度需總蒸汽量（包括噴的冷凝水量）147.768×39.61%=58.531kmol=1311.09 （標）（3）中變爐一段催化劑層物料及熱量計算a入爐蒸汽比（汽氣）計算 設co在一段催化劑層轉化率60.1%且 在一段催化劑層與氨完全燃燒而生成水，則co反應量為 =30×60.1%=18.03n 100n （干半水煤氣）co總反應量 3300×

46、; =596.793n （標）=26.64koml設氣體出一段催化劑層溫度為460，平衡溫距取12，出口氣平衡溫度為460+12=472由小合成氨廠工藝技術與工藝手冊1表4-2-6查得472時 =6.20則 = 將a,c,d及 等代入式得= =6.20解得 b=37.36 即汽：氣=37.36：100入爐蒸汽量 3300 =1236.6 （標）=55.206kmol表2 入爐濕氣組成組分co2coh2n2ch4o2合計%6.04321.84027.66516.0161.0920.14527.200100(標)274.73993.001257.8728.249.656.621236.64546.

47、62kmol12.26543.33056.15232.5092.2160.29655.206202.974kg539.661241.24112.30910.2535.469.47993.7183842.09b.平衡變換率計算及出一段催化劑層氣體組成設460的co平衡變換率為 ，查表4-2-6得460時 =6.85則 = 將入爐氣有關組成代入上式得 = 得 =61.34%實際變換率為平衡變換率的 =97.98%出一段催化劑層干氣體量 3310+596.7936.62×3=3886.933 （標）出一段催化劑層干氣組成表3 催化劑層干氣組成組 分co2coh2n2ch4合 計%22.42

48、10.1947.3818.731.28100(標)871.523396.2071841.353728.20049.6503886.933kmol38.90717.68882.20332.5092.216173.524kg1711.92495.26164.41910.2535.463317.30 出一段催化劑剩余蒸汽量1236.6596.793+6.62×2=653.047 （標）=29.254kmol出一段催化劑層濕氣組成表4 催化劑層濕氣組成組 分co2coh2n2ch4合 計%19.208.7340.5616.041.0914.38100(標)871.523396.2071841

49、.353728.20049.65653.0474539.980kmol38.90717.68882.20332.5092.21629.155202.679kg1711.92495.26164.41910.2535.46524.773842.07c.熱量衡算計算co變換反應氣體溫升入熱co反應放熱 設氣體由300升至460反應取平衡溫度380時熱效應由小合成氨廠工藝技術與設計手冊查圖4-2-1得 kjkmol =（44.33017.688）×38700=1031045.4kj 燃燒熱 =0.296×427250=126466kj合計為1157511.4kj出熱氣體溫升吸熱 設

50、氣體溫升為 ，氣體在平均溫度380下查小合成氨廠工藝技術與設計手冊圖4-6-1圖4-6-8計算得平均熱容為33.521 kj(kmol·) =202.679×33.521 =6794.003 熱損失 =30095.2964kj合計30095.2964+6794.003 熱平衡1176834=30095.2964+6794.003 = =160氣體出口溫度為t=300+160=460氣體出口溫度為460,與前面假設溫度一致。d.一段催化劑平衡曲線計算根據中變爐一段入口汽中蒸汽比（汽氣）0.374，由式（4-3-3）計算各溫度下的平衡變換率列于下表。表5 各溫度下的平衡變換率t

51、,3003203403603804004200.84930.82140.79240.76270.73270.70260.6725t, 4404664805000.64280.61370.58510.5573把干氣體組成折算成濕氣組成%= =21.83%= =6.04%= =27.66%= =16.01%= =14.57%= =1.09%= =27.33即 a=21.83 b=27.22 c=6.04 d=27.66由表4-4-6查得300時 =39.758用式4-3-2計算得w=39.7581=38.758u=39.758（21.83+27.22）+（6.04+27.66）=1983.83v=

52、39.758×21.83×27.2227.22×6.0423457.64q= =546.71由表中數據作圖即得平衡曲線 （見圖12-1-1） e最適宜溫度曲線計算最適宜溫度曲線式（4-4-2）并以b109催化劑的數據進行計算，由于b109催化劑 =16046kal kmol=67156kj/kmol，變換的逆反應活化能 為： = 對于變換反應 =1，則 = + 為反應熱，取其平均溫度下的值即 由(4-2-2)式算得 =37686kjkmol =67156+37686=104842 kjkmol 最適宜溫度計算結果列于表中表6 最適宜溫度計算結果0.84930.82140.79240.76240.73270.70260.67250.64280.61370.58510.5573557.4578.0592.1612.2630.4647.5664.7681.9698.9715.9731.4284.430