Application of bellows technology in heat exchanger
化工企业普遍使用列管式换热器。该换热器价格低, 制造简单。缺点是换热效果欠佳, 管程易堵, 冷媒消耗大。1999 年, 我厂冰机系统技术改造中, 采用了北京某公司的波纹管技术, 将其合作单位制造的波纹管换热器(F = 500m 2) 用于生产。经过一年多的生产试运行, 该技术在节约水源, 提高换热效果, 降低系统压力降等方面明显优于传统技术, 且波纹管换热器具有操作简单,占地小, 管程不易堵等优点。贵州波纹管厂家以该台换热器为例, 介绍波纹管技术, 以供参考。
翡翠棋牌Chemical companies generally use tubular heat exchanger. The heat exchanger is low in price and simple in manufacture. The disadvantage is that the heat transfer effect is not good, the tube process is easy to plug, and the consumption of the cold medium is great. In 1999, during the technical transformation of our plant's ice machine system, we adopted the bellows technology of a company in Beijing, and used the bellows heat exchanger made by our cooperation unit (F = 500m 2) to produce. After more than a year of production trial run, the technology in water conservation, improve the heat transfer effect, reduce the system pressure drop is obviously superior to the traditional technology, and the corrugated tube heat exchanger has the advantages of simple operation, small occupied area, the tube is not easy to block etc.. The Guizhou bellows manufacturers take the heat exchanger as an example to introduce the bellows technology for reference.
翡翠棋牌1 theoretical analysis
翡翠棋牌1.1 structure characteristics
BOWENGUANHUANREQIYUPUTONGHUANREQIDEQUBIEZAIYUYIBOWENGUANDAITIZHIGUAN。BOWENGUANSHIYOU<25mm ×0.8mm DEBOBIBUXIUGANG(0Cr18N i10T i) GUANTONGGUOZHUANYONGSHEBEIJIAGONGERCHENG。BOWENGUANYUZHIGUANCAIYONGDAHANJIE。
The difference between the bellows heat exchanger and the ordinary heat exchanger lies in the replacement of the straight pipe with the bellows. The bellows are made from a <25mm * 0.8mm thin-walled stainless steel (0Cr18N i10T I) tube through a special equipment. The bellows are welded with the straight pipe.
1.2 possible problems
BOWENGUANBIHOUZHIYOU0.8 mm , ZUIBOCHUWEI0.75mm。WOMENZIRANHUIDUIQIWENDINGXING, KANGFUSHIXINGJINAIJIEZHIDECHONGSHUANENGLIDENGCHANSHENGYIWEN。SHISHISHANG, ZHEIYESHIJISHURENYUANBIXUKAOLVDAODEWENTI。
The wall thickness of the bellows is only 0.8 mm, and the thinnest is 0.75mm. We will naturally question its stability, corrosion resistance and the ability to resist the erosion of the medium. In fact, this is a problem that the technicians must take into consideration.
1.3 technical analysis
(1) working conditions
GAITAIBOWENHUANREGUANDEZUOYONGSHIYONGLENGQUESHUIJIANGQIANLENGQUECHENGYEAN。GUANCHENGTONGSHUI, QIAOCHENGTONGQIAN(YEAN) , SHUIYAp SHUI= 0.3M Pa, QI(YE) ANp AN= 1.3M Pa, JINKOUSHUIWENtSHUIJIN= 9.5 ℃, CHUKOUSHUIWENtSHUICHU= 16 ℃, QI(YE) ANPINGJUNWENDUtW = 37 ℃。
翡翠棋牌The function of the corrugated heat exchanger is to cool the ammonia into liquid ammonia with cooling water. The pipe passes through the water, the shell side aeration ammonia (liquid ammonia), the water pressure P water = 0.3M Pa, the gas (liquid) ammonia, P ammonia = 1.3M Pa, the inlet water temperature T water intake = 9.5 degrees, the outlet water temperature T water out = 16 degrees, the average temperature of gas (liquid) ammonia is tW = 37 degrees.
(2) stability analysis
YOUGONGKUANGJIJIEGOUTEDIANKEZHI, BOWENGUANZHUYAOSHIXIAOPOHUAIYINGLILAIZIQIANDEYALIHEYOUYUGUANZILIANGDUANGUDINGWENCHAYINQIGUANZIREZHANGBINGZHUANHUANWEIZHOUXIANGYAYINGLI。SUOYIBOWENGUANDECEXIANGHEZHOUXIANGTONGSHISHOUJUNBUWAIYAp DEZUOYONG。ZHOUXIANGWAIYADUIGUANZISHIWENYINGXIANGBUDA。KEYIZHIJIEJIANGBOWENGUANJINSHOUCEXIANGWAIYAYUANTONGDESHIWENZUOWEIZHUYAOSHIXIAOWENTIJINXINGTAOLUNHESHEJI。GUANZIDESHIXIAOKENENGSHIDANGWAIYADADAOYIDINGZHISHI,GUANBIDEJINGXIANGNAODUSUIYASUOYINGLIDEZENGJIAERJIJUZENGDA,ZHIDAOGUANZIBEIYABIE。
According to the working condition and structural characteristics, the main failure of bellows is the pressure of gas ammonia and the thermal expansion and transformation to axial compressive stress due to the fixed temperature difference between two ends of the tube. So the lateral and axial direction of the bellows are simultaneously subjected to the effect of the uniform external pressure of P. The axial outward pressure has little effect on the instability of the tube. It is possible to discuss and design the failure of the bellows directly under the lateral pressure cylinder as the main failure problem. The failure of the tube may be that when the external pressure reaches a certain value, the radial deflection of the tube wall increases sharply with the increase of the compressive stress, until the tube is compressed.
翡翠棋牌The bellows of Guizhou bellows are made from light tube billets. It is introduced that the failure parts of the bellows are located in the straight pipe section at both ends of the bellows.
GAIBOWENGUANZHANGDUL = 4950 mm , ZHIJING(YIGUANGGUANJI) D 0= 25 mm , BIHOUn= 0.8 mm , L C WEILINJIEZHANGDU。
The length of the bellows is L = 4950 mm, the diameter is D 0= 25 mm, the thickness of the wall is n= 0.8 mm, and L C is the critical length.
翡翠棋牌YOUYUL C= 1.17D 0 (D 0/n) 1/2 = 1.17×25 (25/0.8) 1/2 = 163.5 mm ,L > L C, GUWEIZHANGYUANTONG。YIZHIBIHOU、GUANZHANGJIGUANJING, GENJUTUSUANFAYUANLI, KEYISUANCHUBOWENGUANZAI37 ℃XIADEXUYONGWAIYA〔p 〕WEI21784 M Pa(JISUANGUOCHENGLVE) , 〔p 〕> p AN, GUBOWENGUANBUHUIFASHENGWENDINGSHIXIAO。
Because L C= 1.17D 0 (D 0/n) 1/2 = 1.17 * 25 (25/0.8) 1/2 = 163.5 mm, L > L C, so it is a long cylinder. The known wall thickness, tube length and diameter, according to the principle of the algorithm can calculate the corrugated pipe at 37 DEG C under the allowable external pressure of P for 21784 M Pa (computational process slightly), P > P ammonia, the bellows stability failure does not occur.
(3) corrosion failure
DUIYUAOSHITIBUXIUGANGBOWENGUANHUANREGUANLAISHUO, Cl-YINGLIFUSHISHISHIXIAODEZHUYAOPOHUAIXINGSHI, FUSHIYIBANXIANYILIEWENCHUXIAN, HOUKUAISUXIANGQIANFAZHAN, ZHIZHISHIXIAO。Cl- YINGLIFUSHIDEWENDUFANWEIYIBANWEI70～ 250 ℃, ZHEILIDEWENDUWEI37 ℃, GUFASHENGCl- YINGLIFUSHIDEKENENGXINGJIXIAO。LINGWAI, Cl- YESHICHANSHENGFUSHIDEYIGEZHONGYAOYINSU, DUIYUBUXIUGANGCAILIAO, QIGONGZUOHUANJINGZHONGCl- NONGDUYINGXIAOYUHUODENGYU25×10- 6, JINGJIANCE, JUHUAGONGYEYONGSHUIZHONGDECl- NONGDUWEI4×10- 6, QIANHEYEANZHONGDECl- NONGDUKEYIHULVEBUJI。SUOYI, BOWENGUANZAIZHEIZHONGGONGKUANGXIASHIBIJIAOANQUANDE。
For austenitic stainless steel bellows heat exchanger tubes, Cl- stress corrosion is the main form of failure. Corrosion usually starts with cracks and then develops rapidly until failure occurs. The temperature range of Cl- stress corrosion is generally 70~250 C, and the temperature is 37 C, so the possibility of Cl- stress corrosion is very small. In addition, Cl- is also an important factor for the corrosion of stainless steel materials, the concentration of Cl-, the working environment should be less than or equal to 25 x 10-6, after testing, the concentration of Cl- in industrial water Juhua is 4 * 10-6, Cl- concentration in liquid ammonia and ammonia gas can be ignored. Therefore, the bellows are safer in this condition.
(4) scour wear
翡翠棋牌ZHIYUSHUIZHONGNISHADECHONGSHUA, ZAOCHENGBUXIUGANGGUANGUANBIJIANBO, CONGERSUODUANBOWENGUANDESHOUMING。MUQIAN, ZAIJISHUFENXISHANGHAICUNZAIHENDADEKUNNAN, DANJUWOMENDUILANGFANGGUANDAOSHUSONGJUGONGNUANSHEBEIJINXINGKAOCHA, JIEGUOBIJIAOLIXIANG。GAIJUSHUIZHIHANSHALIANGJIAODA, YIGE9m ZHIJINGDECHENDIANCAO, YUNXING5 GEYUE, JISHASHENDA1.5m。DANZI1995 NIAN11 YUEZHI1999 NIAN1 YUE, GAIJUTOUYONGDEBOWENGUANHUANREQIYUNXINGZHENGCHANG, CONGWEIJIANXIU。
翡翠棋牌As for the erosion of sediment in the water, the wall of the stainless steel tube is thinned and the life of the bellows is shortened. At present, there are still great difficulties in the technical analysis, but according to the investigation of the heating equipment in the Pipeline Transportation Bureau of the corridor room, the result is ideal. The water quality of the bureau is large, a sedimentation tank with 9m diameter, running for 5 months, and the sediment is up to 1.5m. But from November 1995 to January 1999, the bellow heat exchanger operated by the bureau had run normally and had never been overhauled.
As the application of bellows technology in the chemical industry is not much, there may be other forms of failure. Guizhou corrugated pipe manufacturers also only with tubular heat exchanger were compared.
2 practical application effect
BOWENGUANHUANREQIYOUYUBOWENJIEDECUNZAI, ZENGDALEHUANREMIANJI, YOUYUBIHOUZHIYOU018 mm , HUANREXIAOGUOJIAOHAO。ZUIWEIZHONGYAODESHIYOUYUBOWENJIEDECUNZAI, YETILIUJINGGUANNEISHIBUDUANTUANDONG, HUANREXIAOGUOHENHAO。LINGYIFANGMIAN, YOUYUYETITUANLIU, BUDUANCHONGSHUANEIBI, SHIWUGOUHENNANXINGCHENG, BOWENGUANJIHUBUHUICHUXIANGUANDUXIANXIANG。
The heat exchange area of the bellows heat exchanger is increased because of the presence of the bellows. The heat transfer effect is better because the thickness of the wall is only 018 mm. The most important thing is that because of the presence of the bellows, the liquid flow is constantly turbulent in the tube, and the heat transfer effect is very good. On the other hand, as a result of liquid turbulence, continuous erosion of the inner wall makes the dirt difficult to form, and the bellows will hardly appear in pipe plugging.
翡翠棋牌WEICHONGFENKAOCHABOWENGUANHUANREQIDESHIYONGQINGKUANG, WOMENZAI1999 NIAN11 YUEZHI2000 NIAN4 YUE, TINGDIAO4 TAILISHILIEGUANHUANREQI, QIEBOWENGUANDELENGMEI(LENGQUESHUI) JIANZHIXIAJIYONGSHUILIANGDE1/3, JIEGUOSHENGCHANJIBENWENDING。TONGGUOYINIANDEXINGNENGKAOHE, JIBENWANCHENGLEDANGCHUYUJIMUBIAO: NIANJIEYUESHUILIANG600WANt, JIEYUESHUIFEI66 WANYUAN, YOUYUQIANZONGGUANYALIXIAJIANG,JIEDIAN600 kW ·h, NIANJIEYUEDIANFEIYUE31.3 WANYUAN, PAIWUDABIAO, SHEBEIYUNXINGQINGKUANGLIANGHAO。
In order to fully examine the usage of bellows heat exchangers, we stopped 4 vertical tube heat exchangers from November 1999 to April 2000, and the cooling medium (cooling water) of bellows was reduced to 1/3 of summer water consumption, and the production was basically stable. Through a year's performance assessment, we basically completed the original target: annual water saving 6 million T, and water saving 660 thousand yuan. Because of the pressure drop of gas ammonia pipe, the electricity saving is 600 kW H. Annual electricity saving is about 313 thousand yuan, sewage discharge is up to standard, and the equipment runs well.
2000 NIANNIANCHU, JUHUAJITUANGONGSIYALIRONGQIJIANCEZHANDUIBOWENGUANJINXINGLEJIANCE: DAKAIFENGTOUSHI, WEIFAXIANLIEGUANZHONGYOUWUWUDUSAIQINGKUANG。DUIRENYICHOUQUDE6 GENGUANJINXINGNEIKUIJINGJIANCHA(SHENRUZHANGDUWEI1.6～ 1.8 m ) , JIEGUOBIAOMINGNEIBIFUSHIQINGKUANGBUMINGXIAN, WEIJIANFUSHIKENGHUOQITAYANZHONGFUSHIXIANXIANG, GUANBOFENGNEIYEWEIFAXIANWUWUJICUN。
In early 2000, Juhua Group Corporation, pressure vessel inspection station of the bellows were detected: open the head, did not find the tube in case of clogging dirt. An endoscopy (6 to 1.8 m) was carried out for any of the extracted tubes. The results showed that the corrosion of the inner wall was not obvious, no corrosive pits or other serious corrosion occurred, and no accumulation of dirt was found in the peak of the pipe wave. It was also found that there was no corrosion in the top of the tubes. The results showed that there was no corrosion in the top of the tubes. The results showed that there was no corrosion in the top of the tubes. There was no accumulation of pollutants in the pipes. It was also found that there was no corrosion in the top of the tubes. The results showed that there was no corrosion in the top of the tubes. There was no accumulation of pollutants in the pipes. The
3 problems to be paid attention to by using bellows heat exchanger
翡翠棋牌When using a bellows heat exchanger, be sure to pay attention to the following points:
(1) ZHENDUIJUTIQINGKUANGXUANQU。BUXIUGANGBOWENGUANHUANREQIDUIGONGKUANGYAOQIUJIAOYAN(TEBIESHIDUICl- DENONGDU) , LENGMEIJIEZHIDEYALIYEBUNENGTAIGAO。
(1) the selection of specific circumstances. The stainless steel bellows heat exchanger is strict with the working conditions (especially the concentration of Cl-), and the pressure of the medium is not too high.
翡翠棋牌(2) BOWENGUANHUANREQIGUANSHUDEKANGZHENXINGJIAOCHA, YUNSHUJIDIAOZHUANGSHI, BUDECHUXIANGUODUPENGZHUANG。
(2) the aseismic property of the bellows heat exchanger tube bundle is poor, and no excessive collision may occur when transportation and hoisting are transported and hoisting.
翡翠棋牌(3) BOWENGUANHUANREQIYUNXING10 GEYUEZUOYOUYINGTINGCHEYICI, BIANYUBOWENGUANSHOUSUOFUYUAN。BOWENGUANDESHOUSUOYEYOULIYUWUGOUDEBOLUO。
翡翠棋牌(3) the bellows heat exchanger should be stopped for about 10 months to facilitate the contraction of the bellows. The contraction of the bellows is also beneficial to the exfoliation of the dirt.
翡翠棋牌(4) MEIGECHANGLENGMEIQINGJIECHENGDUBUTONG, XINSHANGDEBOWENGUANHUANREQIZUIHAONENGZAIJINKOUJIAZHUANGYITAIGUOLVSHEBEI, TONGSHIYINGDINGQIDAKAIFENGTOUJIANCHA
翡翠棋牌(4) the cleanliness of the refrigerants in each plant is different. The new bellows heat exchanger should be able to install a filter in the inlet and open the head check at regular intervals.