加工利用与安全环保 天 然 气 工 业 2005年5月
我国L N G 工厂的生产流程介绍3
曹文胜 鲁雪生 顾安忠 石玉美 汪荣顺
(上海交通大学制冷与低温工程研究所)
曹文胜等. 我国L N G 工厂的生产流程介绍. 天然气工业,2005;25(5) :100～102
摘 要 介绍了我国的L N G 示范装置、调峰型工厂和基本负荷型工厂的状况, 模和工艺流程。这些流程包括:级联式、混合制冷剂、, 。最后指出了我国L N G 工厂的发展方向:根据国情, , 、比功耗、运行要求进行全面的对比分析; 、, 综合考虑各种液化流程的技术特点, —, 冷箱结构紧凑, 换热效率高, 火用损小, , 小型LN G 装置, 以适应我国已经面临大规模开发利用天 主题词 工艺 流程 生产 规模 级联 混合 制冷剂 膨胀机 对比
L N G 工厂按功能分为基本负荷型和调峰型2种。LN G 工厂液化流程按制冷方式分为3种模式:①级联式液化流程; ②混合制冷剂液化流程, 包括闭式、开式、丙烷预冷、CII ; ③带膨胀机液化流程, 包括天然气膨胀、氮气膨胀、氮—甲烷膨胀等。
一、级联式液化流程(Cascade Cycle )
1. 工程
2001年, 中原石油勘探局建造了国内首座生产性质的LN G 工厂, 日处理量为15×104m 3, 采用丙烷和乙烯为制冷剂的级联式循环, 见图1。
①净化:原料气先后进入原料分液罐1(除液) 、过滤器2(脱粒) 、脱CO 2塔3(M EA 法) 、分子筛干燥器4(脱水) 。②液化:净化后的天然气, 首先利用丙烷制冷循环经换热器5和6冷却, 节流降温进入分离器8气液分离; 液相返流回收冷量回收, 气相利
用乙烯制冷循环经换热器9和10冷却, 节流降温进入分离器12气液分离; 气相返流回收冷量回收, 液相经换热器13冷却及节流后进入分离器15气液分离, 气相返流回收冷量回收, 液相流入L N G 储罐16储存
。
2. 特点 该流程充分利用了原料气的高压力, 采用了三级J -T 节流降温, 并注重回收闪蒸气的冷量, 这些措施使得本来就以能耗低著称的级联式液化流程在能耗上更具优势。但是应该看到, 它的每一级制冷循环都是独立的, 都要配备压缩机和水冷却器, 这会使管道和控制系统复杂化,L N G 的单位投资成本较大。此外, 由于附属设备多, 要有专门生产和储存多种制冷剂的设备, 维护不便。考虑到级联式液化流
图1 中原天然气液化流程示意图
1. 分液罐;2. 过滤器;3. 脱CO 2塔;4. 干燥器; 5. 中压丙烷换热器;6. 低压丙烷换热器;7、11、14. 节流阀;8. 高压天然气分离器;9. 乙烯换热器; 10. 中压LN G 换热器; 12. 中压天然气分离器; 13. 低压
LN G 换热器;15. 低压天然气分离器;16. LN G 储槽
3本成果为福建省自然科学基金计划资助项目(项目编号:E0440002) 。
作者简介:曹文胜,1973年生; 上海交通大学制冷及低温工程博士研究生, 集美大学教师。地址:(200030) 上海交通大学制冷与低温工程研究所。电话:(021) 62932602,[1**********]。E 2mail :[email protected]. cn
・100・
程技术成熟, 操作稳定, 对于国内首家生产性质的L N G 工厂, 采用此种流程应是不错的选择。
104m 3的调峰型L N G 工厂, 采用混合制冷剂液化流程(CII ) , 见图2。
二、混合制冷剂液化流程(MRC )
1. 工程Ⅰ
1999年, 上海建造了国内首座日处理量为10×
①液化:预处理后的天然气进入冷箱上部冷却,
经重烃分离器气液分离, 液相回收, 气相进入冷箱下部冷凝和过冷, 最后节流至L N G 储槽。②制冷循环:混合制冷剂是N 2和C 1～C 5的烃类混合物。
冷
图2 上海L N G 调峰站CII 液化流程示意图(由于篇幅所限, 图中数字节点所代表的意义解释从略)
箱出口的低压混合制冷剂蒸气先后经低压吸入筒分
离、压缩机低压级压缩、冷却器冷却进入中压吸入筒分离, 再经压缩机中压级压缩、冷却器部分冷凝后进入分馏塔。混合制冷剂分馏后分成两部分, 分馏塔底部的重组分液体主要含有丙烷、丁烷和戊烷, 进入冷箱预冷后节流降温, 返回冷箱上部蒸发制冷; 分馏塔上部的轻组分气体主要成分是氮、甲烷和乙烷, 进入冷箱冷却并部分冷凝, 经高压吸入筒气液分离, 液相作为分馏塔的回流液, 气相经压缩机高压级压缩、冷却器冷却后进入冷箱预冷, 再进入轻混合制冷剂闪蒸塔气液分离, 得到的气液两相分别进入冷箱预冷后节流降温, 返回冷箱下部的不同部位提供冷量。 2. 工程Ⅱ 2002年, 新疆广汇实业兴建了国内第一座大规模基本负荷型L N G 工厂, 日处理天然气150×104m 3, 采用高效混合制冷剂液化流程, 见图3。
图3 新疆鄯善L N G 工厂液化流程示意图
离, 气液相分别进入预冷段。液相经预冷段过冷、节流阀节流降温, 与后续流程的返流气混合后为预冷段提供冷量; 气相经预冷段冷却、分离器气液分离, 气液相分别流入液化段。液相经过冷和节流降压降温后, 与返流气混合为液化段提供冷量; 气相经液化段冷却、过冷段过冷、节流降压降温后返回该段, 为过冷段提供冷量。
・101・
①液化:预处理后的天然气进入冷箱, 经预冷段
分离重烃、液化段冷凝, 过冷段过冷, 最后节流至L N G 储槽。②制冷循环:从冷箱返流的混合制冷剂蒸气经三级压缩机压缩、风冷器冷却、
分离器气液分
3. 特点胀降温, 进入换热器2, 冷却需液化的天然气。另一
MRC 是目前最具活力和生命力的制冷工艺, 它部分经过换热器2冷却, 节流降温后进入L N G 储罐的最大特点是混合工质在换热器内的热交换过程是储存。储罐中自蒸发的气体冷量回收后进入管网。个变温过程, 能与同样是混合组分的天然气相匹配。 2. 工程Ⅱ因此可使冷热流体间的换热温差保持较低的水平, 20世纪90年代中期, 长庆石油勘探局建立了1其实它等价于级联式液化流程在无穷级数时的极限, 但又避免了级联式系统复杂的缺点。目前全球各大L N G 设备公司为争夺市场展开了激烈的竞争, 如美国空气制品公司开发的A PCI 和A P -X 流程, 法国燃气公司开发的CII 流程, 它们均代表了天然气液化技术的发展趋势。
MRC 中最具代表性的是丙烷预冷混合制冷剂液化流程(C 3/MRC ) , 其目的是通过丙烷制冷循环预冷进入主流程的天然气, 剂流量大为降低。C 3/MRC 简单、投资省, CII 流程, 、分馏设备与整体式冷箱的巧妙组织, 使得流程进一步精简, 同时又兼具了C 3/MRC 流程的技术优势。但其核心部件———高效板翅式换热器冷箱, 可采用H TFS. MU SE 进行设计。新疆L N G 工厂没有采用丙烷预冷, 其能耗较高。
座示范性L N G 工程, 日处理量为3×104m 3, 采用气波制冷机和透平膨胀联合进行低温制冷, 进气压力4. 1M Pa , 见图5
。
5 陕北气田L N G 示范工程液化过程工艺流程图
1. 氨蒸发器;2. 第二预冷器;3. 第三预冷器;4. 深冷换热器;5. 分离器;6. 气波制冷机;7. 透平膨胀机;9、11、13水冷却器;10. 第一预冷器;8、12、14循环压缩机;15. LN G 储罐
三、带膨胀机液化流程(Expander Cycle )
1. 工程Ⅰ
20世纪90年代初, 中国科学院低温中心等单位先后为四川石化企业和吉林石化企业建成了2座L N G 示范装置:前者生产能力为0. 3m 3/h , 采用天然气膨胀制冷循环, 进气压力4M Pa , 见图4; 后者生产能力为0. 5m 3/h , 采用氮气膨胀闭式制冷循环
。
高压原料气经氨蒸发器1、预冷器2冷却, 一部分气体进入气波制冷机6和透平膨胀机7膨胀降温, 与返流气混合为预冷器3、预冷器2、预冷器10提供冷量; 另一部分气体经预冷器3、换热器4冷却并节流后进入分离器5气液分离, 气相返流冷量回收, 液相进入LN G 储罐15。 3. 特点 膨胀机具有较高的等熵效率及膨胀功可回收的优点, 因此越来越受到液化能力较小的调峰型LN G 工厂的青睐。但由于靠压差通过膨胀机来制冷, 所以压缩机需要消耗较多的功来增压气体。以上两个工程都是采用天然气膨胀液化流程, 省去了专门生产、运输、储存制冷剂的费用, 但不能获得像氮气膨胀液化流程那样低的温度、循环气量大、液化率低, 膨胀机的工作性能受原料气压力和组成变化的影响较大, 对系统的安全性要求较高。 采用氮气膨胀液化流程虽然可以避免以上缺点, 但由于冷热流体间的换热温差大, 为缩小温差促使换热面积增加, 导致换热器金属投入量增大。若是采用氮—甲烷膨胀液化流程, 可缩小冷端的换热温差, 节省动力消耗。
图4 四川石化天然气膨胀液化流程示意图
四、结束语
目前天然气液化流程追求高效率、低能耗与低
投资, 以此降低产品生产费用, 增强(下转第121页)
高压气体经换热器1预冷, 进入气液分离器分离掉重烃。分离器产生的气体一部分进入膨胀机膨・102・
第25卷第5期 天 然 气 工 业
表7 液化气质量及燃料气故障停机频率统计对比表改造措施实施前①
机组燃气质量
液化气
故障占机组总
不合格率
故障百分率
计的是6月至9月内的数据。
加工利用与安全环保
改造措施实施后②
机组燃气质量
液化气
故障占机组总
不合格率
故障百分率
四、经济效益及社会效益
1. 经济效益
截止到2002年12月31日已完成液化气33428t , 比2001年液化气产量28414t 增产5014t , 创造了可观的经济效益。表10为效益核算表。
表10 经济效益核算结果表
创效
指标数量液化气
5014t / 注:①统计的是40万装置工艺改造投产后20天内的数据; ②统
3. 90万装置入口放空阀开启时间及放空气量对比 将90万装置机组处理的部分气举气输至40万装置进行处理, 减少了伴生气放空。表8为90万装置入口放空阀开启时间及放空气量对比表。
表8 90统计时间
2001年6～11电
425810kW ・h 元/h 31万元
节约合同费用设备维护费年总收益
13. 5万元964. 05万元
放空阀(～70h/～244/d )
8～15 注:90万装置检修时间除外。
2. 社会效益
(1) 利用40万装置闲置流程实现90万装置入口自动补压, 不仅保证了40万装置透平膨胀机的运行效率, 而且减少了气体放空量, 降低了环境污染, 消除了操作隐患。
(2) 轻烃厂仅在夏季开工, 不仅保证轻烃外输质量, 提高轻烃外销安全性, 而且节约了人力, 具有可观的社会效益。
(3) 轻烃跨储运站, 降低了生产成本。
4. 液化气产量对比 通过以上几项液化气保质增产措施的实施, 2002年轮南天然气站液化气产量得到期很大提高, 表9为2001年与2002年液化气产量对比表。
表9 液化气产量对比表
液化气产量(t )
2001年2002年增产百分比(%)
5月2483279212. 44
6月2545292614. 97
9月10月[***********]. 810. 97
11月277429004. 54
12月2375360051. 58
(来稿日期 2004212201 编辑 居维清)
注:检修改造停产月份不计算在内。
(上接第102页) 市场竞争力, 这需要对工艺流程进
工技术经济,2004; (1)
3 王保庆. 天然气液化技术及其应用. 天然气工业,2004;24
(7)
4 Brautigam M. L N G baseload plant in remote north 2West
of China. L N G journal , November/December ,2003:19—20
5 朱刚. 天然气迁移性质与调峰型液化流程的优化研究. 上
行合理的分析和评价。级联式液化流程虽然能耗最
低, 但是投资大, 流程复杂, 管理极为不便。混合制冷剂液化流程以丙烷预冷最具竞争力, 但是流程设备还是显得复杂, 适应于大型基本负荷型L N G 工厂。带膨胀机液化流程紧凑、规模较小, 但是能耗高, 适应于调峰型L N G 工厂。
参 考 文 献
1 顾安忠, 鲁雪生, 汪荣顺, 石玉美, 林文胜. 液化天然气技
海交通大学博士学位论文,2000
6 徐烈, 徐永生等. 我国液化天然气(L N G ) 的陆地储存与运
输. 天然气工业,2002;22(3) :89～91
术. 北京:机械工业出版社,2004
2 顾安忠, 石玉美, 汪荣顺. 中国液化天然气的发展. 石油化
(修改回稿日期 2005203211 编辑 居维清)
・121・
N A TU R A L GA S I N DUS T R Y/May , 2005
f racturing for condensate reservoirs. Taking some produc 2tion well of Q K Garfield in Dongpu sag as example , the pro 2ductivity changing law is found for condensate liquid and nat 2ural gas after f racturing. In the end , integrating the variation of components and f racture length , the reasons causing pro 2ductivity change are analyzed comprehensively.
Beijing (102249) , China Tel :(010) 89733152 E 2mail :yangsl @bjpeu.edu. cn
INTR OD UCTION ON L NG RESOURCE AN D L NG TRADE 1)
SUB JECT HEADING S :Condensate gas well , Hydraulic
f racturing , Production , Performance , Component , Mathe 2matical simulation
Zhu Juhui is studying for doctoral degree. Add :Xindu District , Chengdu , Sichuan (610500) , China Tel :(028)
83030425 E 2mail :zhujuhui @etang. com
STRESS SENSITIVIT Y OF R OCK AN D ITS INF L U 2ENCE ON PR OD UCTIVIT Y FOR V OIRS WITH ABN 1 Yang (2versity ) , Xiao Xiaoqiang (Tal 2imu Oilfield Branch , PCL ) . N A T U R. GA S I N D. v. 25, no. 5, pp. 94—95, 5/25/2005. (ISSN 1000-0976; In Chinese)
ABSTRACT :The permeability of rock samples is meas 2
ured under different overburden pressure for Kela 22gas res 2ervoirs with abnormal high pressure. According to the meas 2ured results , the power f unction expression of stress sensi 2tivity of permeability is derived. The changing law of the rock permeability is summed up as the gas reservoir pressure or the effective overburden pressure changes. Considering the influence of permeability changing on the productivity of the gas reservoir , a new productivity equation is developed. The study shows the stress sensitivity of rock samples for Kela 22gas reservoirs is bigger than that for Daqing oilfield , which is the no 2compacted characteristic of rocks of gas res 2ervoirs with abnormal high pressure. The stress sensitivity of rock samples makes the productivity decreasing. Under the conditions of Kela 22gas reservoirs , considering the stress sensitivity , AOF is about 70%of that when the per 2meability is constant. The study provides reference to deeply understand the productivity of gas reservoirs with abnormal high pressure , predict the production performance and the recovery factor of gas reservoirs with abnormal high pres 2sure. (Financed by the Subject N o. 2001BA 605A 02202203of the N ational K ey T echnical Problems to Solve in the “T enth 52years Plan ”)
Yuan Hailing (Planning Depart ment of
Zhongyuan Oilfield Com. , Sinopec ) , Zhao Baocai (Survey &Design Instit ute of Zhongyuan Oil Ex 2ploration Bureau Com. , Sinopec ) and Wang Wen 2tao (Oil Recovery Engineering Instit ute of Zhongyuan Oilfield Com. , ) . N A T U R. GA I N D. v. 255—99, 5/25/2005. (; price rises continuously in the
as by long 2distance pipeline crossing oceans is restricted by many factors , which promote L N G trade increasing rapidly. As L N G receiving station in Guang 2dong province and L N G project in Fujian province are f ul 2filled , the domestic L N G receiving stations will appear more and more. So , analyzing the construction and progress of L N G production 2line projects and the L N G trade worldwide will be helpf ul for the domestic L N G receiving stations to choose the proper source and trade mode. According to the L N G sources f rom neighbor places , the principle of high safety , reasonable price , and short transportation distance of L N G delivering is proposed for domestic L N G stations to se 2lect L N G source. The L N G pricing principle is analyzed worldwide. Especially , the calculating formula of S curve used in Australia L N G projects is introduced. Also , both the modes of FOB and DES usually used in the international trade of L N G are introduced. The advantages and disadvan 2tages of the 2modes are compared.
SUB JECT HEADING S :Liquefied natural gas (L N G ) ,
Receiving station , Production line , Resource , Trade , Mode , FOB , DES
Yu an H ailing (f emale ) was born in 1969. Add :Puy 2ang , Henan (457001) , China Tel :(0393) 4826625 Cell :
[1**********] E 2mail :yuanhl @sina.com
WORK F LOW OF L NG PLANTS IN CHINA 1)
SUB JECT HEADING S :Permeability , Rock , Stress ,
Experiment , High 2pressure reservoir , Productivity
Cao Wensheng , L u Xuesheng , Gu Anzhong , Shi Yumei and Wang Y ongshun (Ref rigeration and Cryogenics Instit ute of Shanghai Jiatong U niversi 2ty ) . N A T U R. GA S I N D. v. 25, no. 5, pp. 100—102, 5/25/2005. (ISSN 1000-0976; In Chinese)
ABSTRACT :The modeling plant , the peak 2cutting
plant and the basic loading plant of L N G in China are intro 2
Yang Shenglai (associate p rof essor , post 2Doctor ) has
published more than 30papers. Add :Changping District ,
13
N A TU RA L GA S I N DUS T R Y/May , 2005
duced including their production scales and process flows. The flows cover the cascade ref rigeration , the mixed 2ref rig 2erate ref rigeration , and the refrigeration with expander. The operating features , advantages and disadvantages of the flows are compared. At the end , the development direction of L N G plants is pointed out in China. According to the real situation of China , the concrete design conditions and pe 2ripheral conditions , the investing cost , the specific power consumption and the running requirements of the different flows are analyzed thoroughly. Following the development trend of the current gas liquefaction flows to seek simplifica 2tion and high efficiency , the technical features of the differ 2ent flows should be considered comprehensively to develop new gas liquefaction flows suitable to the real situation in China. The flow should be simple , the equipment less , the structure of the ref rigeration case tight , the heat 2efficiency high , the enthalpy loss less , driving machine L N G plants should be developed largely to new situation facing in China to produce and utilize natural gas with a large scale.
study progress of L N G cryogenic energy utilization covering the new power cycling and C 2+hydrocarbon separating by L N G cryogenic energy. At last , the idea of integrative opti 2mization is proposed to combine L N G cryogenic energy utili 2zation with L N G utilization i. e. L N G receiving station is built coupling with the industrial zone of L N G cryogenic en 2ergy utilization to use L N G cryogenic energy level by level and improve the using efficiency of L N G cryogenic energy.
SUB JECT HEADING S :L N G , Cryogenic energy utiliza 2
tion , Analysis and evaluation , Integrative optimization
Li Jing (f emale ) , born in 1980, is studying for doctoral
degree. Add :South China Technology University , Guang 2zhou , Guangdong (510640) , :(020) 87113614 Fax. (020) @sohu.com
STATUS OF FUE L SYSTEM USE D B Y L NG 2D RIVEN VEHIC L ES IN USA 1)
SUB JECT HEADING S :China , G as liquefaction , Tech 2
nology , Flow sheet , production , Scale , Cascade , Mixture , Ref rigerate , Expander , Comparison
Wei Wei , Wang Y ongshun and Shi Yumei (Ref rigeration and Cryogenics Instit ute of Shang 2hai Jiatong University ) . N A T U R. GA S I N D. v. 25, no. 5, pp. 106—108, 5/25/2005. (ISSN 1000-0976; In Chinese)
ABSTRACT :As L N G is imported largely in China ,
L N G vehicles will be developed gradually and have bright f u 2ture. It is introduced the working principle of f uel system used by L N G 2driven vehicles in USA , the product specifica 2tions and types of L N G fuel tanks , the codes and standards to design , manufacture and apply the f uel system used by L N G 2driven vehicles , and the technical patents holt in the
C ao Wensheng (teacher ) , born in 1973, is studying for
doctoral degree. Add :Ref rigeration and Cryogenics Insti 2tute of Shanghai Jiatong University , Shanghai (200030) , China Tel :(021) 62932602 Cell :[1**********] E 2mail :wscao @sjtu.edu. cn
CURRENT STATUS AN D DEVE LOPING PR OS 2
PECT OF L NG CR YOGENIC ENERG Y UTI L IZA 2TION 1)
field. Also , after the fuel system used by L N G 2driven vehi 2cles is analyzed comprehensively , it is pointed out the tech 2nology of fuel system used by L N G 2driven vehicles has to be improved and developed further more.
Li Jing , Li Zhihong and Hua Ben (Sout h Chi 2
na Technology University ) . N A T U R. GA S I N D. v. 25, no. 5, pp. 103—105, 5/25/2005. (ISSN 1000-0976; In Chinese)
ABSTRACT :As L N G is imported largely in China , uti 2
lizing the large low 2temperature energy carried by L N G has become very important economically. The current status of L N G cryogenic energy utilization is introduced at home and abroad. It is analyzed and evaluated the main ways to utilize L N G cryogenic energy including the power generation , air separation , CO 2liquefaction etc. by L N G cryogenic energy. The above 2mentioned ways consider recovering the L N G cry 2ogenic energy only , but not utilizing L N G cryogenic energy comprehensively , and lead a lot of enthalpy loss. And most ways of L N G cryogenic energy utilization are separate , but not combined with L N G utilization. Here is introduced the
SUB JECT HEADING S :United States , Liquefied natural gas (L N G ) , Automobile , Fuel , System , Theory , Standard ,
Patent
Wei Wei (f emale ) , born in 1973, is studying for doc 2
toral degree. Add :No. 1954, Huashang Rd. , Shanghai (200030) , China Tel :(021) 62932602 E 2mail :wei [email protected]. cn
F LOW SHEET OF G AS L IQUEFACTION WITH SMALL SCAL E 1)
Cao Wensheng , L u Xuesheng , Shi Yumei , Wang Y ongshun (Ref rigeration and Cryogenics In 2stit ute of Shanghai Jiatong University ) . N A T U R. GA S I N D. v. 25, no. 5, pp. 109—111, 5/25/
14
加工利用与安全环保 天 然 气 工 业 2005年5月
我国L N G 工厂的生产流程介绍3
曹文胜 鲁雪生 顾安忠 石玉美 汪荣顺
(上海交通大学制冷与低温工程研究所)
曹文胜等. 我国L N G 工厂的生产流程介绍. 天然气工业,2005;25(5) :100～102
摘 要 介绍了我国的L N G 示范装置、调峰型工厂和基本负荷型工厂的状况, 模和工艺流程。这些流程包括:级联式、混合制冷剂、, 。最后指出了我国L N G 工厂的发展方向:根据国情, , 、比功耗、运行要求进行全面的对比分析; 、, 综合考虑各种液化流程的技术特点, —, 冷箱结构紧凑, 换热效率高, 火用损小, , 小型LN G 装置, 以适应我国已经面临大规模开发利用天 主题词 工艺 流程 生产 规模 级联 混合 制冷剂 膨胀机 对比
L N G 工厂按功能分为基本负荷型和调峰型2种。LN G 工厂液化流程按制冷方式分为3种模式:①级联式液化流程; ②混合制冷剂液化流程, 包括闭式、开式、丙烷预冷、CII ; ③带膨胀机液化流程, 包括天然气膨胀、氮气膨胀、氮—甲烷膨胀等。
一、级联式液化流程(Cascade Cycle )
1. 工程
2001年, 中原石油勘探局建造了国内首座生产性质的LN G 工厂, 日处理量为15×104m 3, 采用丙烷和乙烯为制冷剂的级联式循环, 见图1。
①净化:原料气先后进入原料分液罐1(除液) 、过滤器2(脱粒) 、脱CO 2塔3(M EA 法) 、分子筛干燥器4(脱水) 。②液化:净化后的天然气, 首先利用丙烷制冷循环经换热器5和6冷却, 节流降温进入分离器8气液分离; 液相返流回收冷量回收, 气相利
用乙烯制冷循环经换热器9和10冷却, 节流降温进入分离器12气液分离; 气相返流回收冷量回收, 液相经换热器13冷却及节流后进入分离器15气液分离, 气相返流回收冷量回收, 液相流入L N G 储罐16储存
。
2. 特点 该流程充分利用了原料气的高压力, 采用了三级J -T 节流降温, 并注重回收闪蒸气的冷量, 这些措施使得本来就以能耗低著称的级联式液化流程在能耗上更具优势。但是应该看到, 它的每一级制冷循环都是独立的, 都要配备压缩机和水冷却器, 这会使管道和控制系统复杂化,L N G 的单位投资成本较大。此外, 由于附属设备多, 要有专门生产和储存多种制冷剂的设备, 维护不便。考虑到级联式液化流
图1 中原天然气液化流程示意图
1. 分液罐;2. 过滤器;3. 脱CO 2塔;4. 干燥器; 5. 中压丙烷换热器;6. 低压丙烷换热器;7、11、14. 节流阀;8. 高压天然气分离器;9. 乙烯换热器; 10. 中压LN G 换热器; 12. 中压天然气分离器; 13. 低压
LN G 换热器;15. 低压天然气分离器;16. LN G 储槽
3本成果为福建省自然科学基金计划资助项目(项目编号:E0440002) 。
作者简介:曹文胜,1973年生; 上海交通大学制冷及低温工程博士研究生, 集美大学教师。地址:(200030) 上海交通大学制冷与低温工程研究所。电话:(021) 62932602,[1**********]。E 2mail :[email protected]. cn
・100・
程技术成熟, 操作稳定, 对于国内首家生产性质的L N G 工厂, 采用此种流程应是不错的选择。
104m 3的调峰型L N G 工厂, 采用混合制冷剂液化流程(CII ) , 见图2。
二、混合制冷剂液化流程(MRC )
1. 工程Ⅰ
1999年, 上海建造了国内首座日处理量为10×
①液化:预处理后的天然气进入冷箱上部冷却,
经重烃分离器气液分离, 液相回收, 气相进入冷箱下部冷凝和过冷, 最后节流至L N G 储槽。②制冷循环:混合制冷剂是N 2和C 1～C 5的烃类混合物。
冷
图2 上海L N G 调峰站CII 液化流程示意图(由于篇幅所限, 图中数字节点所代表的意义解释从略)
箱出口的低压混合制冷剂蒸气先后经低压吸入筒分
离、压缩机低压级压缩、冷却器冷却进入中压吸入筒分离, 再经压缩机中压级压缩、冷却器部分冷凝后进入分馏塔。混合制冷剂分馏后分成两部分, 分馏塔底部的重组分液体主要含有丙烷、丁烷和戊烷, 进入冷箱预冷后节流降温, 返回冷箱上部蒸发制冷; 分馏塔上部的轻组分气体主要成分是氮、甲烷和乙烷, 进入冷箱冷却并部分冷凝, 经高压吸入筒气液分离, 液相作为分馏塔的回流液, 气相经压缩机高压级压缩、冷却器冷却后进入冷箱预冷, 再进入轻混合制冷剂闪蒸塔气液分离, 得到的气液两相分别进入冷箱预冷后节流降温, 返回冷箱下部的不同部位提供冷量。 2. 工程Ⅱ 2002年, 新疆广汇实业兴建了国内第一座大规模基本负荷型L N G 工厂, 日处理天然气150×104m 3, 采用高效混合制冷剂液化流程, 见图3。
图3 新疆鄯善L N G 工厂液化流程示意图
离, 气液相分别进入预冷段。液相经预冷段过冷、节流阀节流降温, 与后续流程的返流气混合后为预冷段提供冷量; 气相经预冷段冷却、分离器气液分离, 气液相分别流入液化段。液相经过冷和节流降压降温后, 与返流气混合为液化段提供冷量; 气相经液化段冷却、过冷段过冷、节流降压降温后返回该段, 为过冷段提供冷量。
・101・
①液化:预处理后的天然气进入冷箱, 经预冷段
分离重烃、液化段冷凝, 过冷段过冷, 最后节流至L N G 储槽。②制冷循环:从冷箱返流的混合制冷剂蒸气经三级压缩机压缩、风冷器冷却、
分离器气液分
3. 特点胀降温, 进入换热器2, 冷却需液化的天然气。另一
MRC 是目前最具活力和生命力的制冷工艺, 它部分经过换热器2冷却, 节流降温后进入L N G 储罐的最大特点是混合工质在换热器内的热交换过程是储存。储罐中自蒸发的气体冷量回收后进入管网。个变温过程, 能与同样是混合组分的天然气相匹配。 2. 工程Ⅱ因此可使冷热流体间的换热温差保持较低的水平, 20世纪90年代中期, 长庆石油勘探局建立了1其实它等价于级联式液化流程在无穷级数时的极限, 但又避免了级联式系统复杂的缺点。目前全球各大L N G 设备公司为争夺市场展开了激烈的竞争, 如美国空气制品公司开发的A PCI 和A P -X 流程, 法国燃气公司开发的CII 流程, 它们均代表了天然气液化技术的发展趋势。
MRC 中最具代表性的是丙烷预冷混合制冷剂液化流程(C 3/MRC ) , 其目的是通过丙烷制冷循环预冷进入主流程的天然气, 剂流量大为降低。C 3/MRC 简单、投资省, CII 流程, 、分馏设备与整体式冷箱的巧妙组织, 使得流程进一步精简, 同时又兼具了C 3/MRC 流程的技术优势。但其核心部件———高效板翅式换热器冷箱, 可采用H TFS. MU SE 进行设计。新疆L N G 工厂没有采用丙烷预冷, 其能耗较高。
座示范性L N G 工程, 日处理量为3×104m 3, 采用气波制冷机和透平膨胀联合进行低温制冷, 进气压力4. 1M Pa , 见图5
。
5 陕北气田L N G 示范工程液化过程工艺流程图
1. 氨蒸发器;2. 第二预冷器;3. 第三预冷器;4. 深冷换热器;5. 分离器;6. 气波制冷机;7. 透平膨胀机;9、11、13水冷却器;10. 第一预冷器;8、12、14循环压缩机;15. LN G 储罐
三、带膨胀机液化流程(Expander Cycle )
1. 工程Ⅰ
20世纪90年代初, 中国科学院低温中心等单位先后为四川石化企业和吉林石化企业建成了2座L N G 示范装置:前者生产能力为0. 3m 3/h , 采用天然气膨胀制冷循环, 进气压力4M Pa , 见图4; 后者生产能力为0. 5m 3/h , 采用氮气膨胀闭式制冷循环
。
高压原料气经氨蒸发器1、预冷器2冷却, 一部分气体进入气波制冷机6和透平膨胀机7膨胀降温, 与返流气混合为预冷器3、预冷器2、预冷器10提供冷量; 另一部分气体经预冷器3、换热器4冷却并节流后进入分离器5气液分离, 气相返流冷量回收, 液相进入LN G 储罐15。 3. 特点 膨胀机具有较高的等熵效率及膨胀功可回收的优点, 因此越来越受到液化能力较小的调峰型LN G 工厂的青睐。但由于靠压差通过膨胀机来制冷, 所以压缩机需要消耗较多的功来增压气体。以上两个工程都是采用天然气膨胀液化流程, 省去了专门生产、运输、储存制冷剂的费用, 但不能获得像氮气膨胀液化流程那样低的温度、循环气量大、液化率低, 膨胀机的工作性能受原料气压力和组成变化的影响较大, 对系统的安全性要求较高。 采用氮气膨胀液化流程虽然可以避免以上缺点, 但由于冷热流体间的换热温差大, 为缩小温差促使换热面积增加, 导致换热器金属投入量增大。若是采用氮—甲烷膨胀液化流程, 可缩小冷端的换热温差, 节省动力消耗。
图4 四川石化天然气膨胀液化流程示意图
四、结束语
目前天然气液化流程追求高效率、低能耗与低
投资, 以此降低产品生产费用, 增强(下转第121页)
高压气体经换热器1预冷, 进入气液分离器分离掉重烃。分离器产生的气体一部分进入膨胀机膨・102・
第25卷第5期 天 然 气 工 业
表7 液化气质量及燃料气故障停机频率统计对比表改造措施实施前①
机组燃气质量
液化气
故障占机组总
不合格率
故障百分率
计的是6月至9月内的数据。
加工利用与安全环保
改造措施实施后②
机组燃气质量
液化气
故障占机组总
不合格率
故障百分率
四、经济效益及社会效益
1. 经济效益
截止到2002年12月31日已完成液化气33428t , 比2001年液化气产量28414t 增产5014t , 创造了可观的经济效益。表10为效益核算表。
表10 经济效益核算结果表
创效
指标数量液化气
5014t / 注:①统计的是40万装置工艺改造投产后20天内的数据; ②统
3. 90万装置入口放空阀开启时间及放空气量对比 将90万装置机组处理的部分气举气输至40万装置进行处理, 减少了伴生气放空。表8为90万装置入口放空阀开启时间及放空气量对比表。
表8 90统计时间
2001年6～11电
425810kW ・h 元/h 31万元
节约合同费用设备维护费年总收益
13. 5万元964. 05万元
放空阀(～70h/～244/d )
8～15 注:90万装置检修时间除外。
2. 社会效益
(1) 利用40万装置闲置流程实现90万装置入口自动补压, 不仅保证了40万装置透平膨胀机的运行效率, 而且减少了气体放空量, 降低了环境污染, 消除了操作隐患。
(2) 轻烃厂仅在夏季开工, 不仅保证轻烃外输质量, 提高轻烃外销安全性, 而且节约了人力, 具有可观的社会效益。
(3) 轻烃跨储运站, 降低了生产成本。
4. 液化气产量对比 通过以上几项液化气保质增产措施的实施, 2002年轮南天然气站液化气产量得到期很大提高, 表9为2001年与2002年液化气产量对比表。
表9 液化气产量对比表
液化气产量(t )
2001年2002年增产百分比(%)
5月2483279212. 44
6月2545292614. 97
9月10月[***********]. 810. 97
11月277429004. 54
12月2375360051. 58
(来稿日期 2004212201 编辑 居维清)
注:检修改造停产月份不计算在内。
(上接第102页) 市场竞争力, 这需要对工艺流程进
工技术经济,2004; (1)
3 王保庆. 天然气液化技术及其应用. 天然气工业,2004;24
(7)
4 Brautigam M. L N G baseload plant in remote north 2West
of China. L N G journal , November/December ,2003:19—20
5 朱刚. 天然气迁移性质与调峰型液化流程的优化研究. 上
行合理的分析和评价。级联式液化流程虽然能耗最
低, 但是投资大, 流程复杂, 管理极为不便。混合制冷剂液化流程以丙烷预冷最具竞争力, 但是流程设备还是显得复杂, 适应于大型基本负荷型L N G 工厂。带膨胀机液化流程紧凑、规模较小, 但是能耗高, 适应于调峰型L N G 工厂。
参 考 文 献
1 顾安忠, 鲁雪生, 汪荣顺, 石玉美, 林文胜. 液化天然气技
海交通大学博士学位论文,2000
6 徐烈, 徐永生等. 我国液化天然气(L N G ) 的陆地储存与运
输. 天然气工业,2002;22(3) :89～91
术. 北京:机械工业出版社,2004
2 顾安忠, 石玉美, 汪荣顺. 中国液化天然气的发展. 石油化
(修改回稿日期 2005203211 编辑 居维清)
・121・
N A TU R A L GA S I N DUS T R Y/May , 2005
f racturing for condensate reservoirs. Taking some produc 2tion well of Q K Garfield in Dongpu sag as example , the pro 2ductivity changing law is found for condensate liquid and nat 2ural gas after f racturing. In the end , integrating the variation of components and f racture length , the reasons causing pro 2ductivity change are analyzed comprehensively.
Beijing (102249) , China Tel :(010) 89733152 E 2mail :yangsl @bjpeu.edu. cn
INTR OD UCTION ON L NG RESOURCE AN D L NG TRADE 1)
SUB JECT HEADING S :Condensate gas well , Hydraulic
f racturing , Production , Performance , Component , Mathe 2matical simulation
Zhu Juhui is studying for doctoral degree. Add :Xindu District , Chengdu , Sichuan (610500) , China Tel :(028)
83030425 E 2mail :zhujuhui @etang. com
STRESS SENSITIVIT Y OF R OCK AN D ITS INF L U 2ENCE ON PR OD UCTIVIT Y FOR V OIRS WITH ABN 1 Yang (2versity ) , Xiao Xiaoqiang (Tal 2imu Oilfield Branch , PCL ) . N A T U R. GA S I N D. v. 25, no. 5, pp. 94—95, 5/25/2005. (ISSN 1000-0976; In Chinese)
ABSTRACT :The permeability of rock samples is meas 2
ured under different overburden pressure for Kela 22gas res 2ervoirs with abnormal high pressure. According to the meas 2ured results , the power f unction expression of stress sensi 2tivity of permeability is derived. The changing law of the rock permeability is summed up as the gas reservoir pressure or the effective overburden pressure changes. Considering the influence of permeability changing on the productivity of the gas reservoir , a new productivity equation is developed. The study shows the stress sensitivity of rock samples for Kela 22gas reservoirs is bigger than that for Daqing oilfield , which is the no 2compacted characteristic of rocks of gas res 2ervoirs with abnormal high pressure. The stress sensitivity of rock samples makes the productivity decreasing. Under the conditions of Kela 22gas reservoirs , considering the stress sensitivity , AOF is about 70%of that when the per 2meability is constant. The study provides reference to deeply understand the productivity of gas reservoirs with abnormal high pressure , predict the production performance and the recovery factor of gas reservoirs with abnormal high pres 2sure. (Financed by the Subject N o. 2001BA 605A 02202203of the N ational K ey T echnical Problems to Solve in the “T enth 52years Plan ”)
Yuan Hailing (Planning Depart ment of
Zhongyuan Oilfield Com. , Sinopec ) , Zhao Baocai (Survey &Design Instit ute of Zhongyuan Oil Ex 2ploration Bureau Com. , Sinopec ) and Wang Wen 2tao (Oil Recovery Engineering Instit ute of Zhongyuan Oilfield Com. , ) . N A T U R. GA I N D. v. 255—99, 5/25/2005. (; price rises continuously in the
as by long 2distance pipeline crossing oceans is restricted by many factors , which promote L N G trade increasing rapidly. As L N G receiving station in Guang 2dong province and L N G project in Fujian province are f ul 2filled , the domestic L N G receiving stations will appear more and more. So , analyzing the construction and progress of L N G production 2line projects and the L N G trade worldwide will be helpf ul for the domestic L N G receiving stations to choose the proper source and trade mode. According to the L N G sources f rom neighbor places , the principle of high safety , reasonable price , and short transportation distance of L N G delivering is proposed for domestic L N G stations to se 2lect L N G source. The L N G pricing principle is analyzed worldwide. Especially , the calculating formula of S curve used in Australia L N G projects is introduced. Also , both the modes of FOB and DES usually used in the international trade of L N G are introduced. The advantages and disadvan 2tages of the 2modes are compared.
SUB JECT HEADING S :Liquefied natural gas (L N G ) ,
Receiving station , Production line , Resource , Trade , Mode , FOB , DES
Yu an H ailing (f emale ) was born in 1969. Add :Puy 2ang , Henan (457001) , China Tel :(0393) 4826625 Cell :
[1**********] E 2mail :yuanhl @sina.com
WORK F LOW OF L NG PLANTS IN CHINA 1)
SUB JECT HEADING S :Permeability , Rock , Stress ,
Experiment , High 2pressure reservoir , Productivity
Cao Wensheng , L u Xuesheng , Gu Anzhong , Shi Yumei and Wang Y ongshun (Ref rigeration and Cryogenics Instit ute of Shanghai Jiatong U niversi 2ty ) . N A T U R. GA S I N D. v. 25, no. 5, pp. 100—102, 5/25/2005. (ISSN 1000-0976; In Chinese)
ABSTRACT :The modeling plant , the peak 2cutting
plant and the basic loading plant of L N G in China are intro 2
Yang Shenglai (associate p rof essor , post 2Doctor ) has
published more than 30papers. Add :Changping District ,
13
N A TU RA L GA S I N DUS T R Y/May , 2005
duced including their production scales and process flows. The flows cover the cascade ref rigeration , the mixed 2ref rig 2erate ref rigeration , and the refrigeration with expander. The operating features , advantages and disadvantages of the flows are compared. At the end , the development direction of L N G plants is pointed out in China. According to the real situation of China , the concrete design conditions and pe 2ripheral conditions , the investing cost , the specific power consumption and the running requirements of the different flows are analyzed thoroughly. Following the development trend of the current gas liquefaction flows to seek simplifica 2tion and high efficiency , the technical features of the differ 2ent flows should be considered comprehensively to develop new gas liquefaction flows suitable to the real situation in China. The flow should be simple , the equipment less , the structure of the ref rigeration case tight , the heat 2efficiency high , the enthalpy loss less , driving machine L N G plants should be developed largely to new situation facing in China to produce and utilize natural gas with a large scale.
study progress of L N G cryogenic energy utilization covering the new power cycling and C 2+hydrocarbon separating by L N G cryogenic energy. At last , the idea of integrative opti 2mization is proposed to combine L N G cryogenic energy utili 2zation with L N G utilization i. e. L N G receiving station is built coupling with the industrial zone of L N G cryogenic en 2ergy utilization to use L N G cryogenic energy level by level and improve the using efficiency of L N G cryogenic energy.
SUB JECT HEADING S :L N G , Cryogenic energy utiliza 2
tion , Analysis and evaluation , Integrative optimization
Li Jing (f emale ) , born in 1980, is studying for doctoral
degree. Add :South China Technology University , Guang 2zhou , Guangdong (510640) , :(020) 87113614 Fax. (020) @sohu.com
STATUS OF FUE L SYSTEM USE D B Y L NG 2D RIVEN VEHIC L ES IN USA 1)
SUB JECT HEADING S :China , G as liquefaction , Tech 2
nology , Flow sheet , production , Scale , Cascade , Mixture , Ref rigerate , Expander , Comparison
Wei Wei , Wang Y ongshun and Shi Yumei (Ref rigeration and Cryogenics Instit ute of Shang 2hai Jiatong University ) . N A T U R. GA S I N D. v. 25, no. 5, pp. 106—108, 5/25/2005. (ISSN 1000-0976; In Chinese)
ABSTRACT :As L N G is imported largely in China ,
L N G vehicles will be developed gradually and have bright f u 2ture. It is introduced the working principle of f uel system used by L N G 2driven vehicles in USA , the product specifica 2tions and types of L N G fuel tanks , the codes and standards to design , manufacture and apply the f uel system used by L N G 2driven vehicles , and the technical patents holt in the
C ao Wensheng (teacher ) , born in 1973, is studying for
doctoral degree. Add :Ref rigeration and Cryogenics Insti 2tute of Shanghai Jiatong University , Shanghai (200030) , China Tel :(021) 62932602 Cell :[1**********] E 2mail :wscao @sjtu.edu. cn
CURRENT STATUS AN D DEVE LOPING PR OS 2
PECT OF L NG CR YOGENIC ENERG Y UTI L IZA 2TION 1)
field. Also , after the fuel system used by L N G 2driven vehi 2cles is analyzed comprehensively , it is pointed out the tech 2nology of fuel system used by L N G 2driven vehicles has to be improved and developed further more.
Li Jing , Li Zhihong and Hua Ben (Sout h Chi 2
na Technology University ) . N A T U R. GA S I N D. v. 25, no. 5, pp. 103—105, 5/25/2005. (ISSN 1000-0976; In Chinese)
ABSTRACT :As L N G is imported largely in China , uti 2
lizing the large low 2temperature energy carried by L N G has become very important economically. The current status of L N G cryogenic energy utilization is introduced at home and abroad. It is analyzed and evaluated the main ways to utilize L N G cryogenic energy including the power generation , air separation , CO 2liquefaction etc. by L N G cryogenic energy. The above 2mentioned ways consider recovering the L N G cry 2ogenic energy only , but not utilizing L N G cryogenic energy comprehensively , and lead a lot of enthalpy loss. And most ways of L N G cryogenic energy utilization are separate , but not combined with L N G utilization. Here is introduced the
SUB JECT HEADING S :United States , Liquefied natural gas (L N G ) , Automobile , Fuel , System , Theory , Standard ,
Patent
Wei Wei (f emale ) , born in 1973, is studying for doc 2
toral degree. Add :No. 1954, Huashang Rd. , Shanghai (200030) , China Tel :(021) 62932602 E 2mail :wei [email protected]. cn
F LOW SHEET OF G AS L IQUEFACTION WITH SMALL SCAL E 1)
Cao Wensheng , L u Xuesheng , Shi Yumei , Wang Y ongshun (Ref rigeration and Cryogenics In 2stit ute of Shanghai Jiatong University ) . N A T U R. GA S I N D. v. 25, no. 5, pp. 109—111, 5/25/
14