DN1200氨吸收塔畢業(yè)CAD設(shè)計(jì)（全套含7張圖紙+說(shuō)明書+開(kāi)題報(bào)告+翻譯）
DN1200氨吸收塔畢業(yè)CAD設(shè)計(jì)（全套含7張圖紙+說(shuō)明書+開(kāi)題報(bào)告+翻譯）,dn1200,吸收塔,畢業(yè),cad,設(shè)計(jì),全套,圖紙,說(shuō)明書,仿單,開(kāi)題,報(bào)告,講演,呈文,翻譯
畢業(yè)設(shè)計(jì)(論文)
題 目 DN1200氨吸收塔設(shè)計(jì)
學(xué)院名稱 機(jī)械工程學(xué)院
指導(dǎo)教師
職 稱
班 級(jí)
學(xué) 號(hào)
學(xué)生姓名
2011年 5 月 30 日
畢業(yè)設(shè)計(jì)(論文)任務(wù)書
學(xué) 院： 機(jī)械工程學(xué)院
題 目： DN1200氨吸收塔設(shè)計(jì)
起止時(shí)間：
學(xué) 生 姓 名：
專 業(yè) 班 級(jí)：
指 導(dǎo) 老 師：
教研室主任：
院 長(zhǎng)：
20 年 1月 6日
設(shè)計(jì)（論文）內(nèi)容及要求：
一、 已知設(shè)計(jì)參數(shù)：
用20℃的清水吸收混合氣中的氨，混合氣中含氨10%，其余為空氣。
操作壓力為1.01×105pa，操作溫度40℃，混合氣流量10000m3/h，吸收劑用量為最小用量的1.1倍,氣相體積吸收總系數(shù)為200kmol/( m3.h)氨的回收率為95%,
環(huán)境 衡陽(yáng)室外
二、設(shè)計(jì)內(nèi)容及設(shè)計(jì)工作量要求：
（1）按所給設(shè)計(jì)參數(shù)完成氨吸收塔的設(shè)計(jì)；
（2）繪制設(shè)計(jì)圖紙總計(jì)3張零號(hào)以上，其中要求手工繪圖1張壹號(hào)以上；
（3）設(shè)計(jì)說(shuō)明書字?jǐn)?shù)不少于1.5萬(wàn)字，并要求統(tǒng)一用A4紙打印；
（4）翻譯3千左右漢字量的與畢業(yè)設(shè)計(jì)有關(guān)的英文資料；
（5）撰寫相當(dāng)于3百漢字的英文摘要。
三、主要參考資料：
《化工設(shè)備設(shè)計(jì)全書（塔設(shè)備）》
《化工原理》
《化工工藝設(shè)計(jì)手冊(cè)》
GB150-1998《鋼制壓力容器》
指導(dǎo)教師： 年 月 日
生畢業(yè)設(shè)計(jì)（論文）開(kāi)題報(bào)告
設(shè)計(jì)（論文）題目
DN1200氨吸收塔設(shè)計(jì)
設(shè)計(jì)（論文）題目來(lái)源
自選
設(shè)計(jì)（論文）題目類型
工程設(shè)計(jì)
起止時(shí)間
一、 設(shè)計(jì)（論文）依據(jù)及研究意義：
氨是化工生產(chǎn)中極為重要的生產(chǎn)原料。硝酸、各種含氮的無(wú)機(jī)鹽及有機(jī)中間體、磺胺藥、聚氨酯、聚酰胺纖維和丁腈橡膠等都需直接以氨為原料；液氨常用作制冷劑；尿素的主要用途：一、肥料作用；二、其他工業(yè)用。因此，氨在現(xiàn)實(shí)中需求量是比較大的，而氨又是工業(yè)廢氣中污染環(huán)境的因素之一，因此對(duì)于氨的回收有環(huán)保和經(jīng)濟(jì)上的雙重意義，符合現(xiàn)代可持續(xù)發(fā)展的理念。
二、 設(shè)計(jì)（論文）主要研究的內(nèi)容、預(yù)期目標(biāo)（技術(shù)方案、路線）：
本次設(shè)計(jì)的是氣混合氣流量為10000 m3/h的氨吸收塔。設(shè)計(jì)包括的主要內(nèi)容：物料衡算、熱量衡算、塔設(shè)備的工藝設(shè)計(jì)（塔內(nèi)徑、塔高、封頭、填料、進(jìn)出口接管及裙座等）等。并對(duì)其進(jìn)行強(qiáng)度計(jì)算及校核，繪制圖紙等。
技術(shù)方案及路線：1.收集資料；2.物料衡算及工藝計(jì)算；3.塔結(jié)構(gòu)設(shè)計(jì)和強(qiáng)度設(shè)計(jì)及校核；4.繪制施工圖；5.設(shè)計(jì)說(shuō)明書制訂。
三、設(shè)計(jì)（論文）的研究重點(diǎn)及難點(diǎn)：
重點(diǎn)是：
物料衡算、熱量衡算和塔設(shè)備的尺寸計(jì)算和確定以及強(qiáng)度計(jì)算和校核。
難點(diǎn)是：
1、其難點(diǎn)為塔內(nèi)的物料及熱量衡算，并對(duì)其進(jìn)行比較準(zhǔn)確的計(jì)算。
2、由于本次設(shè)計(jì)的塔是滿足常壓下大能力的生產(chǎn)，其難點(diǎn)是對(duì)塔高、塔內(nèi)徑以及壁厚等進(jìn)行比較優(yōu)化的設(shè)計(jì)。
三、由于本次設(shè)計(jì)的塔為高壓塔而且考慮了各種載荷，其難點(diǎn)是對(duì)塔體以及一些塔內(nèi)件的強(qiáng)度計(jì)算及校核。
四、設(shè)計(jì)（論文）研究方法及步驟（進(jìn)度安排）：
1月6日至1月10日：了解我們所要設(shè)計(jì)的試驗(yàn)裝置，為進(jìn)行設(shè)計(jì)做準(zhǔn)備；
1月10日至2月17日：查閱資料，找設(shè)計(jì)依據(jù)，理出設(shè)計(jì)思路；
2月18日至3月28日：算數(shù)據(jù)，求得設(shè)計(jì)的各種依據(jù)；
3月29日至5月18日：設(shè)計(jì)，畫出設(shè)計(jì)圖紙；
5月19日至5月26日；整理圖紙，進(jìn)行打印。寫出設(shè)計(jì)說(shuō)明書并校核。
5月26日至5月31日：準(zhǔn)備答辯。
五、進(jìn)行設(shè)計(jì)（論文）所需條件：
1、要有充分的資料（在圖書館查閱與尿素合成相關(guān)的書籍，進(jìn)行篩選，選出有用的信息）。
2、設(shè)計(jì)所需設(shè)計(jì)方法、軟件、工具等。
六、指導(dǎo)教師意見(jiàn)：
簽名： 年 月 日
中文摘要：本次設(shè)計(jì)的是氣混合氣流量為10000的氨吸收塔。根據(jù)工藝條件選用填料塔來(lái)完成此任務(wù)。填料塔的設(shè)計(jì)包括的主要內(nèi)容：物料衡算、熱量衡算、塔設(shè)備的工藝設(shè)計(jì)（塔內(nèi)徑、塔高、封頭、填料、進(jìn)出口接管及裙座等）等。并對(duì)其進(jìn)行強(qiáng)度計(jì)算以及校核，繪制圖紙等。技術(shù)方案及路線：首先進(jìn)行物料衡算和熱量衡算，然后進(jìn)行塔設(shè)備的尺寸計(jì)算，主要包括塔的高度確定和填料層高度的計(jì)算，以及對(duì)塔附件（吊柱、液體分布器、人孔、手孔、裙座等）的計(jì)算與選擇，最后進(jìn)行強(qiáng)度計(jì)算和校核。
關(guān)鍵詞：氨吸收；填料塔；物料衡算；強(qiáng)度計(jì)算；
Abstract: This design is about of an ammonia absorption tower whose operated pressure is 1.01×105 pa, the operated temperature is 40℃ and the gas mixture flow of 10000 m3/h. Select packed tower to accomplish this task in accordance of technique. Packed tower design includes the main elements: technique calculation, tower equipment process design (inner diameter, height, head, padding, import and export and the supporting seat, etc.). Calculated and collate the strength of them, and drawing. Technical programs and routes: first material balance and heat balance, and then proceed to calculate the size of tower equipment, including the height of tower and fill to identify, as well as the calculation and choice of the tower annex (hanging column, liquid distributor, manhole, hand hole, support, etc.), the final calculated and check for strength.
Keywords: ammonia; absorption tower; packed tower; strength counting.
目錄
目錄 1
引言 1
第一章 工藝計(jì)算 2
1.1吸收劑用量及吸收溶液深度 2
1.1.1惰性氣體流量 2
1.1.2 最小氣液比 2
1.1.3最小吸收劑用量 4
1.1.4吸收液濃度 4
1.2泛液速度 4
1.2.1 塔頂混合氣體平均分子量 4
1.2.2填料的選擇 5
1.2.3泛點(diǎn)氣速 5
1.3塔徑的估算 7
1.4液體噴淋密度的驗(yàn)算 7
1.5填料層高度的計(jì)算 8
1.5.1傳質(zhì)單元數(shù)的計(jì)算 8
1.5.2傳質(zhì)單元數(shù)的計(jì)算 8
1.5.3填料層的分段 10
1.5.4填料層壓降的計(jì)算 10
第二章 塔結(jié)構(gòu)的設(shè)計(jì) 12
2.1塔內(nèi)件及附件的選擇 12
2.1.1除沫器的選擇 12
2.1.2填料支承裝置的選擇 12
2.1.3液體分布器 13
2.1.4液體再分布器 14
2.1.5 裙座結(jié)構(gòu)設(shè)計(jì) 15
2.1.6 人孔的設(shè)計(jì)與選擇 16
2.1.7塔吊柱的選擇 16
2.1.8接管的選擇 19
2.1.9 接管法蘭的選擇 19
2.1.10壓力容器法蘭的選擇 20
第三章 塔的設(shè)計(jì)及強(qiáng)度校核 21
3.1塔體和封頭的厚度計(jì)算 21
3.1.1材料的選擇 21
3.1.2筒體厚度的確定 21
3.1.3封頭壁厚計(jì)算 22
3.2塔體載荷分析 23
3.2.1質(zhì)量載荷 23
3.2.2自振周期的計(jì)算 24
3.2.3塔體的風(fēng)載荷及風(fēng)力矩 25
3.2.4地震載荷與地震彎矩的計(jì)算 27
3.3塔體的強(qiáng)度及穩(wěn)定性校核 31
3.3.1 塔體的軸向應(yīng)力 31
3.3.2 軸向應(yīng)力校核 31
3.4 裙座的強(qiáng)度及穩(wěn)定性較核 32
3.4.1裙座各危險(xiǎn)截面的校核 32
3.4.2焊縫強(qiáng)度的校核 33
3.5裙座基礎(chǔ)環(huán) 33
3.5.1 基礎(chǔ)環(huán)內(nèi)外徑確定 33
3.5.2基礎(chǔ)環(huán)的厚度設(shè)計(jì) 34
3.6地腳螺栓計(jì)算 35
3.7水壓試驗(yàn)時(shí)塔的強(qiáng)度和穩(wěn)定性驗(yàn)算 35
第四章 開(kāi)孔和開(kāi)孔補(bǔ)強(qiáng)設(shè)計(jì) 36
4.1開(kāi)孔及補(bǔ)強(qiáng)說(shuō)明 36
4.2 開(kāi)孔補(bǔ)強(qiáng)設(shè)計(jì)計(jì)算 41
4.2.1 封頭開(kāi)孔補(bǔ)強(qiáng)設(shè)計(jì)計(jì)算 41
4.2.2人孔開(kāi)孔補(bǔ)強(qiáng)設(shè)計(jì)計(jì)算 43
第五章 主要制造工藝 45
5.1 橢圓封頭部件的制造 45
5.2筒節(jié)的主要制造工藝 45
5.3總裝 46
5.4 主要件的熱處理 47
5.5主要檢驗(yàn)要求 47
參考文獻(xiàn)： 48
附錄一 外文原稿： 49
附錄二 外文翻譯： 56
謝 辭 62
第 5 頁(yè) 共 62 頁(yè)
附件2
畢業(yè)設(shè)計(jì) (論文)裝訂格式及打印規(guī)范
一、 裝訂順序
1、封面頁(yè)：首頁(yè)為封面，按照學(xué)校統(tǒng)一設(shè)計(jì)的封面樣式打??；
2、畢業(yè)設(shè)計(jì)（論文）任務(wù)書頁(yè)；
3、開(kāi)題報(bào)告；
4、中文摘要和關(guān)鍵詞頁(yè)：摘要的字?jǐn)?shù)在200至300字之間，關(guān)鍵詞在3至5個(gè)之間；
5、英文摘要和關(guān)鍵詞頁(yè)：根據(jù)中文摘要和關(guān)鍵詞翻譯；
6、目錄頁(yè)：應(yīng)有小節(jié)對(duì)應(yīng)的頁(yè)碼；
7、正文頁(yè)；
8、參考文獻(xiàn)頁(yè)；
9、謝辭
二、打印規(guī)范
1、論文以A4標(biāo)準(zhǔn)頁(yè)面排版(21*29.7cm)，1.5倍行距，字體、字號(hào)要求如下：
標(biāo)題用粗黑體：一級(jí)標(biāo)題三號(hào)，二級(jí)標(biāo)題小三號(hào)，三級(jí)標(biāo)題四號(hào)；正文用宋體小四號(hào)。
2、章節(jié)目序號(hào)(標(biāo)題序號(hào))：
(1)按照正式出版物的慣例，標(biāo)題編號(hào)順序規(guī)定如下：1、1.1、1.1.1………
(2)論文標(biāo)題一律從“1、”開(kāi)始。
3、圖表標(biāo)號(hào)：
圖1.1 圖1.2 圖2.1 圖2.2 ……
(與圖名稱一起標(biāo)在圖正下方，用5號(hào)宋體，如圖1.1，GDP按年度增長(zhǎng)率)
表1.1 表1.2 表2.1 表2.2 ……
(與表名一起標(biāo)在表正上方，如表1.1職工情況一覽表)
4、中文摘要和關(guān)鍵詞：
摘要：※※※※
關(guān)鍵詞：※※※；※※※；※※※
其中：摘要和關(guān)鍵詞這兩個(gè)詞用宋體加粗，小四號(hào)，摘要內(nèi)容和關(guān)鍵詞內(nèi)容用楷體四小號(hào)；
5、英文摘要和關(guān)鍵詞：參照中文摘要和關(guān)鍵詞；用Times New Roman體；
6、論文正文：空二行后書寫正文，正文的第一段為“引言”，但不加小標(biāo)題。
7、參考文獻(xiàn)列示格式(5號(hào)宋體)：
書籍格式：〔編號(hào)〕作者,作者.書名[M].出版地:出版社,出版時(shí)間
期刊格式：〔編號(hào)〕作者,作者.文章題目[J].期刊名,年份(期數(shù)):起頁(yè)碼~止頁(yè)碼
報(bào)紙格式：〔編號(hào)〕作者,作者.文章題目[N]. 報(bào)紙名,年月日,第幾版
注意：網(wǎng)絡(luò)文獻(xiàn)一般不作為參考文獻(xiàn)。
8、頁(yè)眉必須打印“南華大學(xué)※※※學(xué)院畢業(yè)設(shè)計(jì)（或論文）” ，居中（5號(hào)宋體）；
9、正文必須打上頁(yè)碼，頁(yè)碼格式為“第X頁(yè)，共X頁(yè)”；居中打印（5號(hào)宋體）；論文前面的中英文摘要頁(yè)、目錄頁(yè)用小寫ⅰ、ⅱ、ⅲ、ⅳ順序編頁(yè)。
10、所有論文請(qǐng)用WORD98以上版本打印。
浮閥塔設(shè)計(jì)計(jì)算結(jié)果匯總
序號(hào)
項(xiàng)目
單位
數(shù)值
1
回流比
R
3.66
2
精餾段平均溫度
℃
90.8
3
精餾段平均壓力
kPa
109.3
4
氣相流量
m3/s
1.42
5
液相流量
m3/s
0.0041
6
實(shí)際塔板數(shù)
31
7
精餾段塔板數(shù)
18
8
提餾段塔板數(shù)
12
9
精餾段有效段高度
m
10.2
10
提餾段有效段高度
m
6.6
11
人孔高度
m
0.8
12
精餾塔有效段高度
m
18
13
塔徑
m
1.6
14
板間距
m
0.6
15
溢流形式
單溢流
16
降液管形式
弓形降液管
17
堰長(zhǎng)
m
1.171
18
堰寬
m
0.25
19
堰高
m
0.0669
20
板上液層高度
m
0.06
21
堰上液層高度
m
0.0161
22
降液管底隙高度
m
0.035
23
安定區(qū)寬度
m
0.05
24
邊緣區(qū)寬度
m
0.075
25
有效傳質(zhì)面積
m2
15.801
26
開(kāi)孔區(qū)面積
m2
0.222
27
浮閥直徑
m
0.039
28
閥孔數(shù)目
120
29
孔中心距
m
0.3
30
開(kāi)孔率
0.13
31
閥孔氣速
m/s
9.91
32
穩(wěn)定系數(shù)
3.4
33
每層塔板壓降
Pa
0.8
附錄一 外文原稿：
Anhydrous Ammonia Pressure Vessels In The Pulp And Paper Industry
The purpose of this article is to ensure that pulp and paper operating companies, their engineering consultants, and inspection contractors are informed about stress corrosion cracking in anhydrous ammonia service. The information was written by a task group of the TAPPI Engineering Division Nondestructive Testing and Quality Control Subcommittee.
Bacteria in some activated sludge effluent treatment systems require supplementary food. In some cases, this food is provided by ammonia and phosphoric acid which are stored on the mill site. Ammonia is commonly stored as anhydrous liquid ammonia in carbon steel vessels at ambient temperature and 16 bar (250 psig) pressure.
These vessels can be subject to stress corrosion cracking (SCC).SCC could cause release of ammonia, which is a hazardous chemical. SCC of carbon steel vessels in anhydrous ammonia service is somewhat analogous to that experienced in continuous digesters. For example, the importances of stress relief during fabrication and of in-service inspection are common to both.
This article concerns storage in horizontal pressure vessels at ambient temperature, as this type of vessel is used in pulp and paper applications. Large refrigerated storage tanks are used for atmospheric pressure storage in the chemical industry.
History of Scc In Ammonia Storage Vessels
The history of SCC in carbon steel ammonia storage vessels was reviewed by Loginow (1) and is also briefly summarized in a NACE Technical Committee Report entitled “Integrity of Equipment in Anhydrous Ammonia Storage and Handling” (2). In the 1950s, liquefied ammonia began to be injected directly into soil for fertilization. Failure of carbon steel storage vessels by SCC began to occur. These failures were unexpected since liquefied ammonia had been used for many years in the refrigeration, chemical, and metal heat treating industries without reported problems.
Investigation confirmed SCC to be the cause of cracking. Three recommendations were made in 1962 that still form the basis of modern codes:
? Pressure vessels should be fully stress relieved.
? Extreme care should be used to eliminate oxygen from ammonia systems.
? Ammonia should contain at least 0.2% water to inhibit SCC.
Loginow reported that adoption of these recommendations practically eliminated SCC in carbon steel vessels in the agriculture industry. However, in a recent Western Canadian survey SCC was found in 100 of 117 field storage vessels inspected by wet fluorescent magnetic particle testing (WFMT) (3).
Despite the above measures SCC continued to occur in road transport tanks constructed from high strength steels, in refrigerated storage vessels and in vessels which had been weld repaired but not subsequently stress relieved. An additional recommendation to limit steel tensile or yield strength was embodied in the U.S. and British ammonia storage codes, respectively (4, 5).
? ANSI K61.1—Nominal tensile no greater than 70,000 psi (580 MPa)
? U.K. Code—Minimum specified yield strength shall not exceed 350 MPa (51,000 psi).
PRACTICAL CONSIDERATIONS
This article is concerned mainly with practical considerations important to pulp and paper mills already possessing anhydrous ammonia storage vessels or planning to fabricate such vessels. In view of the industry’s experience with SCC in continuous digesters the governing objectives should be to control fabrication and inspection to prevent, or at least minimize, in-service problems including over-reaction to relatively minor crack indications. Guidance is available in the published codes and detailed information is available from some ammonia suppliers.
Fabrication
The two main objectives in fabrication should be to provide the most crack resistant vessel possible at reasonable cost and to ensure that an adequate inspection baseline is available for interpretation of subsequent in-service inspections.
ASME Section VIII Division 1 does not require stress relief for anhydrous ammonia storage pressure vessels unless the owner specifies a lethal service designation.
The lethal service designation requires radiographic testing (RT) of all butt welded joints plus post weld heat treatment.
ANSI K-61.1-1989, “American National Standard Safety Requirements for the Storage and Handling of Anhydrous Ammonia,” adds several requirements:
? Fabrication to ASME Section VIII Division 1 Table UW 12 at a joint efficiency less than 80% is not allowed.
? Inspection and testing under UG-90(c) (2) (multiple, duplicate pressure vessel fabrication) is not allowed.
? Steel used for pressure containing parts shall have a nominal tensile strength no greater than 580MPa (70,000 psi).
? The minimum design pressure for ambient temperature storage shall be 16 bar (250 psig).
? Post weld heat treatment is mandatory and a furnace of sufficient size to accommodate the entire vessel is recommended. Welded attachments may be made to pads after post weld heat treatment.
? Horizontal vessels shall be mounted on saddles which extend over at least one third of the shell’s circumference. Thermal expansion and contraction shall be allowed for and means provided to prevent corrosion between the shell and the saddles.
The 1986 British Code “Storage of Anhydrous Ammonia under Pressure in the United Kingdom” requires:
? Steel must have specified minimum yield strength less than 350 MPa (51,000 psi).
? Weld filler must have minimal strength overmatch compared with the base plate.
? 100% magnetic particle inspection of all internal welds in order to provide a record against which all future inspections of the vessel can be assessed.
? No welding is permitted after stress relief without subsequent local stress relief.
? Concrete saddles are prohibited.
? Support must be on continuously welded steel saddles attached before stress relief.
Although the British Code does not state that magneti particle inspection should be by WFMT it is generally agreed that WFMT is the most sensitive technique and should be used for inspection of ammonia storage vessels. All inspection should be performed by qualified technicians. SNT-TC-1A Level II is a recommended minimum.
One pulp and paper company has added the following requirements for fabrication of such vessels:
? Incorporation of a “corrosion allowance” of at least 1.6 mm (1/16 in.) to permit minor defect chasing during in-service inspections and to provide a margin against pitting which may occur if water is allowed to enter an out of service vessel.
? All weld toes profiled by grinding prior to wet fluorescent magnetic particle testing (WFMT). All WFMT indications greater than 1.6 mm (1/16 in.) to be removed by grinding before post weld heat treatment.
? Shear wave ultrasonic testing (UT) of nozzle-to-shell welds permitted if RT is judged impractical.
? WFMT to be repeated after final hydrotest test of the vessel and the report retained by the owner.
? Vessel to be dried completely after hydrotest test and nitrogen padded until filled with ammonia.
Valves, piping, and fittings
Both the ANSI and U.K. codes address piping, valves, and fittings. A detailed summary is beyond the scope of this article, but some points are worth noting.
? ANSI K61.1 requires all nonrefrigerated ammonia piping to meet the requirements of ANSI/ASME B31.3 “Chemical Plant and Petroleum Refinery Piping.”
? The U.K. Code states copper and copper bearing alloys shall not be used.
ANSI/ASME B31.3 requires a minimum of 5% of piping welds be radiographically tested. Valves and other apparatus should be rated for ammonia service and should not contain copper or copper alloy components.
In one case, a nickel rupture disc corroded to failure at its periphery due to formation of an ammonia solution at a gasketed joint exposed to the weather.
In-service inspection
Vessel entry Liquid or gaseous ammonia is hazardous and in some jurisdictions release of ammonia vapor to the atmosphere is prohibited by law. Vessels must be properly purged by water and/or steam. Detailed procedures for vessel purging and entry are available from ammonia suppliers (6).
Inspection procedures The ANSI standard does not address in-service inspection but does state weld repair or alteration must conform to the current edition of the National Board Inspection Code (NBIC).
The 1992 edition of the NBIC includes nonmandatory guidelines for inspection of liquid ammonia vessels (7).
These guidelines recommend:
? Power buffing or light sandblasting as surface preparation for inspection
? All interior welds be examined by WFMT.
? Cracks should be removed by grinding without encroaching on the minimum thickness required by ASME Section VIII and the original design.
? Weld repairs, regardless of size, should be post weld heat treated wherever possible.
Light grinding does increase the sensitivity of WFMT compared to sandblasting or power buffing (8). For example the NBIC mandates grinding as surface preparation for deaerator inspection. The omission of grinding in the guidelines for ammonia vessel in-service inspection may be due to concern that rough grinding may produce residual stress sufficient to initiate SCC in anhydrous ammonia service. If welds have been properly profiled for WFMT on initial fabrication, then grinding for in-service inspection should not be needed.
The NBIC guidelines also state that other inspection methods such as acoustic emission or ultrasonics may be used and that fracture mechanics may be used to assess the integrity of vessels where complete removal of cracks is not practical.
Normally the only corrosion that occurs in anhydrous ammonia vessels is due to water ingress during out of service periods. Shallow pitting, however, has been found in the bottom of some vessels beneath oily deposits. The source of oil is presumed to be from compressors used to handle the ammonia.
In view of concerns over air contamination due to vessel entry and residual stress imparted by grinding nonintrusive inspection, techniques like acoustic emission and UT could be considered by vessel owners. The British Code does not mention nonintrusive inspection of ambient temperature pressure vessels but does state that, if acoustic emission is to be used for spherical storage vessels, a reference base should be taken during initial hydrotesting. Nonintrusive inspection is being used in other industries (9).
Vessel refilling Safety procedures should be established for refilling a vessel that has been emptied for inspection. It is also very important to purge the vessel of air to prevent the occurrence of SCC. Detailed instructions are available from ammonia suppliers (10). If a vessel is not to be returned to service immediately after inspection, then care should be taken to dry it and possibly nitrogen-pad it depending on the time it will remain out of service.
Inspection frequency Neither the ANSI document nor the NBIC deals with inspection frequency. The British Code recommends the following:
? WFMT inspection of 100% of all internal butt welds within the first three years of service
? WFMT re-inspection within 2 years if significant defects are found
? Subsequent to no significant defects being found, any subsequent inspection should include WFMT of all Tee junctions and 10% of the total length of butt welds
? In no case should the subsequent examination interval exceed 6 years.
It is apparent from the above that latitude can exist for in-service inspection techniques and frequencies. Each owner should determine inspection frequency in conjunction with the appropriate authority. Some jurisdictions require a 3-year inspection frequency.
SUMMARY
The use of carbon steel pressure vessels for storage of anhydrous ammonia in the pulp and paper industry could be a non-event or deteriorate into a cycle of inspection and repair. This article has highlighted major concerns related to SCC. There is a wealth of additional information available on all considerations related to these vessels from the ANSI and British Codes, the NACE document, ammonia suppliers, and the current technical literature. The American Institute of Chemical Engineers (AIChE) holds the annual AIChE Ammonia Safety Symposium aimed at finding ways to safely manufacture, transport, and store ammonia and related chemicals. The proceedings of these symposia are published by AIChE. It is recommended that any owner of such vessels keep aware of current expertise.
Reid is materials and corrosion section head with MacMillan Bloedel Research, 4225 Kincaid St., Burnaby, BC, Canada V5G 4P5.
Task group members: Craig Reid; R.S. Charlton, Levelton Associates Consulting Engrs.; R.C. Faloon, MQSInspections Inc.; and W. E. Boudreau, Belle Testing Inc.
Literature cited
1. Loginow,A.W. , Materials Performance 25 (12): 18(1986).
2. NACE Technical Committee report 5A192, Integrity of Equipment in Anhydrous Ammonia Storage and Handling, Houston, NACE Storage Tank, Spokane, 1992.
3. Stephens, J. D. and Vidalin, F., 1994 AIChE Ammonia Symposium Notes, American Institute of Chemical Engineers, New York, p. 9.
4. Compressed Gas Association Inc., American National Standard Safety Requirements for the Storage and Handling of Anhydrous Ammonia ANSI K61.1-1989, Arlington, VA, 1989 (CGA Pamphlet G-2.1-1989).
5. Storage of Anhydrous Ammonia Under Pressure in the United Kingdom, London, Her Majesty’s Stationery Office, 1986. (Health and Safety Booklet HS/G 30)
6. Cominco Fertilizers (U.S.) Inc., Decommissioning an Ammonia Storage Tank, Spokane, 1992.
7. The National Board of Boiler and Pressure Vessel Inspectors, National Board Inspection Code: A Manual for Boiler and Pressure Vessel Inspectors, Columbus, OH, 1992, p.197.
8. Reid, J. C. and Reid, C., TAPPI 1992 Engineering Conference Proceedings, TAPPI PRESS, Atlanta, Book I, p.163.
9. Conley, M. J., Sture, A., and Williams, D., “Ammonia Vessel Integrity Program: A Modern Approach, 1990 AIChE Ammonia Symposium Notes, New York, AIChE, 1990.
10. Cominco Fertilizers (U.S.) Inc., “Commissioning an Ammonia Storage Tank”, Spokane, 1992.
附錄二 外文翻譯：
紙漿和造紙行業(yè)中的無(wú)水氨壓力容器
本文的目的是為了確保紙漿和紙張經(jīng)營(yíng)公司，他們的工程顧問(wèn)，承建商了解在脫水氨設(shè)備中的應(yīng)力腐蝕開(kāi)裂現(xiàn)象。這篇資料是由美國(guó)紙漿與造紙工業(yè)技術(shù)協(xié)會(huì)無(wú)損檢測(cè)工程部和質(zhì)量控制小組委員會(huì)共同編寫。
細(xì)菌生存在一些活性污泥污水處理系統(tǒng)中需要充足的食物。在某些情況下，這種食品是氨和磷酸的儲(chǔ)存現(xiàn)場(chǎng)。氨通常以無(wú)水液氨的形式貯存在室溫和1.6MPa（250 磅）的壓力的碳鋼容器中。
這些容器可能會(huì)受到應(yīng)力腐蝕開(kāi)裂（SCC）。應(yīng)力腐蝕開(kāi)裂可能導(dǎo)致氨泄露，這是一種危險(xiǎn)化學(xué)品。用于無(wú)水氨設(shè)備的碳鋼容器中的SCC是有點(diǎn)類似于連續(xù)蒸煮罐的經(jīng)驗(yàn)。例如，減少壓力的引入在生產(chǎn)和在役檢查過(guò)程都是很常見(jiàn)的。本文關(guān)注在常溫下的臥式壓力容器，像這類型容器通常用于紙漿和造紙的應(yīng)用。大型冷藏儲(chǔ)罐在化工行業(yè)一般是常壓儲(chǔ)存。
SCC在氨儲(chǔ)罐的歷史
SCC在碳鋼氨儲(chǔ)存容器的歷史是由Loginow（1）審查通過(guò),也是在簡(jiǎn)要回顧了NACE技術(shù)委員會(huì)報(bào)告題為“完整的設(shè)備在無(wú)水氨的儲(chǔ)存和處理”(2)。在20世紀(jì)50年代，液氨作為肥料直接注入土壤。碳鋼貯存容器由于應(yīng)力腐蝕開(kāi)裂而導(dǎo)致的故障開(kāi)始出現(xiàn)。這些故障是意外，因?yàn)橐喊币延糜谠谥评?，化工多年，金??熱處理行業(yè)沒(méi)有報(bào)告的問(wèn)題。
調(diào)查結(jié)果證應(yīng)力腐蝕是開(kāi)裂的原因。1962年提出了三條建議構(gòu)成了現(xiàn)代條例的基礎(chǔ)：
?壓力容器應(yīng)充分消除應(yīng)力。
?要特別小心是消除氨系統(tǒng)中的氧氣。
?氨應(yīng)該包含至少0.2％的水，以抑制應(yīng)力腐蝕開(kāi)裂。
Loginow報(bào)告說(shuō)，采用這些建議能有效避免應(yīng)力腐蝕發(fā)生在農(nóng)業(yè)用碳鋼容器中。然而，最近的加拿大西部的調(diào)查顯示通過(guò)濕熒光磁粉探傷檢查（WFMT）（3）發(fā)現(xiàn)117處農(nóng)場(chǎng)的儲(chǔ)罐中有100處發(fā)生了應(yīng)力腐蝕開(kāi)裂。
盡管采用了上述措施，SCC仍然發(fā)生在由高強(qiáng)度鋼建造的公路運(yùn)輸油罐、冷藏儲(chǔ)存容器以及作了焊接修復(fù)卻沒(méi)后續(xù)的應(yīng)力消除的容器。另外一條建議被納入美國(guó)和英國(guó)的氨儲(chǔ)存條例，以限制鋼材的拉伸或屈服強(qiáng)度。
?ANSI K61.1 -名義抗拉強(qiáng)度不超過(guò)70,000磅（580兆帕）
?英國(guó)條例指定的最低屈服強(qiáng)度不超過(guò)350兆帕（51,000磅）。
實(shí)用的考慮
本文主要關(guān)注是實(shí)際問(wèn)題對(duì)于已擁有無(wú)水氨貯存容器的紙漿和造紙廠或計(jì)劃制作這類容器的重要性。以連續(xù)蒸發(fā)罐中SCC的經(jīng)驗(yàn)來(lái)看，執(zhí)行目標(biāo)應(yīng)該是控制制造和檢驗(yàn)，以避免或至少減少在運(yùn)行中的問(wèn)題，包括過(guò)度反應(yīng)相對(duì)輕微裂縫的跡象。從一些氨的供應(yīng)商提供公開(kāi)條例和規(guī)范資料可以得到相關(guān)的指導(dǎo)。
制造
制作中的兩個(gè)主要目標(biāo)應(yīng)是提為抗裂容器供合理的成本，并確保為后續(xù)在役檢驗(yàn)的解釋有適當(dāng)?shù)臋z驗(yàn)基線可用。
ASME第1部第VIII節(jié)沒(méi)有要求無(wú)水氨存儲(chǔ)壓力容器要應(yīng)力消除，除非擁有者指定了一個(gè)致命的部件名稱。
指定的致命部件需要焊接接頭的焊后熱處理加所有對(duì)接射線檢測(cè)（RT）。
美國(guó)國(guó)家標(biāo)準(zhǔn)化組織（ANSI）K – 61.1 - 1989，“美國(guó)國(guó)家標(biāo)準(zhǔn)無(wú)水氨的存儲(chǔ)和處理安全要求”增加了幾個(gè)要求：
?制造符合ASME第一部第VIII節(jié)UW12表的效率不能低于80％。
?基于UG-90(c)檢查和測(cè)試是不允許的。
?用于壓力容器部件的鋼材的標(biāo)稱抗拉強(qiáng)度應(yīng)當(dāng)不低于580MPa（70,000 psi）。
?室溫儲(chǔ)罐的最低設(shè)計(jì)壓力應(yīng)當(dāng)為16bar（250 psig）的。
?必須進(jìn)行焊后熱處理，要求足夠大的熔爐來(lái)適應(yīng)整個(gè)容器。附件的焊接點(diǎn)可能要進(jìn)行熱處理
?臥式壓力容器應(yīng)當(dāng)安裝在鞍座超過(guò)至少有一個(gè)殼體的周長(zhǎng)三分之一。應(yīng)允許熱膨脹和收縮和給出以防止殼體和鞍座之間腐蝕的方法。
1986年英國(guó)章程“英國(guó)常壓無(wú)水氨儲(chǔ)存”要求：
?鋼材的指定最低屈服強(qiáng)度必須小于350兆帕（51,000磅）。
?焊接填充物的最小強(qiáng)度必須高于于比母材強(qiáng)度。
?100％的內(nèi)部焊縫磁粉探傷，對(duì)未來(lái)所有的容器檢查提供可以評(píng)估的紀(jì)錄。
?沒(méi)有后續(xù)局部應(yīng)力消除的應(yīng)力消除后允許無(wú)焊接
?混凝土鞍座是禁止的。
?鋼制鞍座連續(xù)焊接必須在應(yīng)力釋放之前。
雖然英國(guó)規(guī)范并沒(méi)有規(guī)定磁化粒子檢查應(yīng)當(dāng)進(jìn)行濕熒光磁粉實(shí)驗(yàn)，人們普遍認(rèn)為，WFMT是最靈敏的技術(shù)，應(yīng)該用于檢驗(yàn)氨貯存容器。所有的檢查應(yīng)該由合格的技術(shù)人員來(lái)完成。SNT-TC-1A II級(jí)是建議的最低水平。
其中紙漿和造紙公司已對(duì)這些容器的制造增加了下列要求：
?設(shè)立“腐蝕裕量”至少1.6毫米(1 / 16英寸)，允許在役檢驗(yàn)中出現(xiàn)的微小缺陷，并在容器停止服役期間浸水，對(duì)可能出現(xiàn)的腐蝕保持一定的裕度，。
?濕熒光磁粉探傷（WFMT）檢驗(yàn)所有焊接接頭前要進(jìn)行磨削。在焊后熱處理前，大于1.6毫米（1 / 16英寸）所有WFMT跡象要被磨削。
?如果射線探傷不符合實(shí)際，可以使用橫波超聲波檢測(cè)（UT）。
?容器水壓試驗(yàn)后重復(fù)進(jìn)行WFMT，由業(yè)主保留的測(cè)試報(bào)告。
?容器水壓試驗(yàn)后要完全干燥，并且進(jìn)行充氮保護(hù)直至填充氨。
閥門，管道及配件
ANSI和英國(guó)壓力容器規(guī)范都對(duì)管道，閥門和配件進(jìn)行了論述。詳細(xì)摘要已經(jīng)超出了本文的范圍，但有些要點(diǎn)是值得注意的。
?ANSI K61.1要求所有的非冷卻氨管道要滿足符合ANSI / ASME B31.3的規(guī)定“化工廠和石油精煉廠管道。”
?英國(guó)壓力容器規(guī)范規(guī)定銅及銅合金軸承不得使用。
ANSI / ASME B31.3要求5％以上管道焊縫需要X線測(cè)試。閥門和其他設(shè)備應(yīng)使用標(biāo)準(zhǔn)的的氨部件，并且不能含有銅或銅合金成分。
在一個(gè)案例中，一個(gè)鍍鎳爆破片腐蝕失效原因在于襯墊上的氨溶液的形成
在役檢查
容器引進(jìn)。液態(tài)或氣態(tài)氨是危險(xiǎn)化學(xué)品的，而且某些司法管轄區(qū)的法律禁止氨蒸氣釋放到大氣中。容器必須用水或蒸汽妥善清除。從氨供應(yīng)商獲取詳細(xì)的清洗和引進(jìn)說(shuō)明（6）。
檢查程序。 ANSI標(biāo)準(zhǔn)不??涉及在役檢查，但要求焊接修復(fù)或改裝，必須符合現(xiàn)行版國(guó)家檢測(cè)局規(guī)范（NBIC）。
該NBIC 1992年版包括液氨儲(chǔ)罐非強(qiáng)制性的檢查指導(dǎo)。
這些指導(dǎo)原則建議：
?拋光或噴砂表面處理為檢查做準(zhǔn)備
?所有的內(nèi)部焊縫進(jìn)行WFMT檢測(cè)。
?裂縫應(yīng)磨削處理以符合ASME第八節(jié)規(guī)定的最小設(shè)計(jì)厚度。
?焊縫，不論尺寸，都應(yīng)進(jìn)行焊后熱處理。
輕微磨削相對(duì)噴砂處理和電學(xué)拋光可以增加WFMT靈敏性相（8）。例如，NBIC要求磨削作為除氧檢測(cè)的表面處理的準(zhǔn)備。在氨儲(chǔ)罐的在役檢查指導(dǎo)中磨削的遺漏可能是由于擔(dān)心粗磨可能產(chǎn)生的殘余應(yīng)力以致產(chǎn)生應(yīng)力腐蝕開(kāi)裂。如果在初始制造過(guò)程中焊縫因WFMT產(chǎn)生了合適的變形，那么在在役檢查中磨削就沒(méi)有必要了。
該NBIC準(zhǔn)則還規(guī)定，如可能使用聲發(fā)射或超聲波等檢查方法，斷裂力學(xué)可用于評(píng)估那里的容器完整性裂縫徹底清除是不實(shí)際的。
通常，腐蝕只發(fā)生在無(wú)水氨儲(chǔ)罐，是因?yàn)樵谕Ｖ惯\(yùn)行期間滲入水。淺點(diǎn)蝕已發(fā)現(xiàn)在有些容器底部的油性沉淀物。油源被假定為從用來(lái)處理氨的壓縮機(jī)。
針對(duì)由于容器引進(jìn)而產(chǎn)生的空氣污染問(wèn)題和磨削無(wú)損檢測(cè)產(chǎn)生殘余應(yīng)力的問(wèn)題，采用如聲發(fā)射技術(shù)和UT的技術(shù)可以由使用者考慮。英國(guó)規(guī)范并沒(méi)有提及常溫常壓容器的無(wú)損檢測(cè)，但指出了，如果聲發(fā)射檢測(cè)要用于球形儲(chǔ)存容器，應(yīng)當(dāng)在初始水壓試驗(yàn)采取相應(yīng)的參考。無(wú)損檢測(cè)應(yīng)用于其他行業(yè)。
儲(chǔ)罐填充。應(yīng)該為因檢查而清空的容器填充建立一個(gè)安全規(guī)程。這對(duì)于凈化容器空氣防止發(fā)生應(yīng)力腐蝕開(kāi)裂是非常重要的。從氨供應(yīng)商獲取詳細(xì)說(shuō)明（10）。如果容器在檢查后沒(méi)有被立刻送回返修，然后應(yīng)注意干燥，并有可能氮封它取決于停止服役的時(shí)間。
檢查頻率。無(wú)論是ANSI文件或NBIC沒(méi)有處理檢驗(yàn)頻率。英國(guó)規(guī)范建議如下：
?在首三年服役期WFMT100％檢查所有內(nèi)部的對(duì)接焊縫
?如果在兩年內(nèi)發(fā)現(xiàn)重大缺陷進(jìn)行重新檢查，
?繼無(wú)發(fā)現(xiàn)明顯缺陷后，后續(xù)的任何檢查應(yīng)對(duì)所有T型接頭和的對(duì)接焊縫總長(zhǎng)度的10％進(jìn)行WFMT檢測(cè)
?在任何情況下后續(xù)檢查的時(shí)間間隔超過(guò)6年。
從上述可以很明顯看出在役檢查技術(shù)和頻率存在一定范圍。每個(gè)使用者應(yīng)與結(jié)合相關(guān)部門確定檢查頻率。有些管轄區(qū)需要3年的檢查頻率。
總結(jié)
對(duì)紙漿和造紙工業(yè)的碳鋼無(wú)水氨儲(chǔ)存壓力容器的使用可能是一個(gè)非活動(dòng)或進(jìn)入檢查和維修的惡性循環(huán)。本文重點(diǎn)關(guān)注的是應(yīng)力腐蝕開(kāi)裂。從ANSI和英國(guó)規(guī)范，NACE文件，氨儲(chǔ)罐供應(yīng)商和現(xiàn)行的技術(shù)文獻(xiàn)可以獲取的大量有關(guān)注意事項(xiàng)的信息。在美國(guó)化學(xué)工程師學(xué)會(huì)（AIChE）舉行的年度合成氨安全研討會(huì)旨在發(fā)現(xiàn)在安全生產(chǎn)，運(yùn)輸和儲(chǔ)存氨及相關(guān)化學(xué)品的方法。這些專題討論的會(huì)議記錄AIChE公開(kāi)發(fā)表。它建議任何此類容器的所有人應(yīng)及時(shí)了解當(dāng)前的專業(yè)知識(shí)。
里德材料和麥克米蘭布勒德?tīng)栄芯浚?225金凱德街，本拿比，BC，加拿大V5G 4P5腐蝕科科長(zhǎng)。
工作組成員：克雷格里德; R.S.查爾頓Levelton協(xié)會(huì)咨詢工程部。R.C. Faloon鋼筋混凝土s公司和W. E. Boudreau檢測(cè)公司
參考文獻(xiàn)：
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[7] 全國(guó)鍋爐壓力容器督察局和國(guó)家局檢查規(guī)范：鍋爐壓力容器檢驗(yàn)手冊(cè)，哥倫布，俄亥俄州，1992，p.197。
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[9] 康利，麻將，Sture，A.和威廉姆斯，博士，“氨壓力容器完整性方案：一種現(xiàn)代方法，1990年AIChE氨研討會(huì)報(bào)告，紐約，AIChE，1990年。
[10] Cominco的肥料（美國(guó)）公司，“調(diào)試氨儲(chǔ)罐”，斯波坎，1992年。
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