大罐吹扫、干燥、预冷方案.doc

靖边西蓝天然气综合利用项目10000 M3LNG储罐安装工程靖边西蓝天然气综合利用项目10000M3LNG储罐吹扫、预冷方案 编制： 安全： 审核： 审批： 张家港中集圣达因低温装备有限公司 2010年9月3日目 录1、SCOPE范围2、CRITERIA OF PURGING AND DRYING干燥和吹扫标准3、PRELIMINARY CHECKS AND SET-UP初步的检查和组织安排4、QUALITY OF NITROGEN GAS氮气质量5、NITROGEN PURGE AND DRY OUT氮气吹扫和干燥 5.1、Purge and dry out inner tank Zone A (Step 1) 内罐区域A吹扫和干燥（步骤1） 5.2、Purge and dry out zone B (step 2) 区域B吹扫和干燥（步骤2） 5.3、Purge and dry out bottom (step 3) 底部吹扫和干燥（步骤3） 5.4、Purge and dry out of nozzles and zone B (step 4) 管道与区域B吹扫与干燥（步骤4）6、PRODUCT GAS PURGE产品气体吹扫 6.1、Initial conditions初始条件 6.2、Product Gas purge Zone A (step 5) 产品气体吹扫区域A（步骤5） 6.3、Product gas Purge, Zone B (step 6) 产品气体吹扫区域B（步骤6） 6.4、Product gas purge of nozzles (Step 7) 产品气体吹扫管道（步骤7）7、COOL-DOWN冷却 7.1、Initial conditions (step 8) 初始条件（步骤8） 7.2、Cool-down process (step 9) 冷却过程（步骤9）8、Appendix A Tools and Instruments附录A-工具和仪表1 SCOPE范围This specification covers the procedure for purging, dry out and cool down of one 10000 m3 capacity, single integrity, refrigerated storage tank, storing LNG at -163C. 说明文件描述容积为一万方、结构完整、低温储罐、储存LNG温度为-163C 的储罐，内容为吹扫、干燥以及冷却程序Note: Product stated in this procedure refers to LNG AT -163C. Product gas stated in this procedure refers to warm (ambient temperature) LNG vapour. 注意：所规定的“产品”指-163C 的LNG，所规定的“产品气体”指环境温度下的LNG蒸汽。2 CRITERIA OF PURGING AND DRYING吹扫和干燥标准Criteria of Oxygen purging and drying using Nitrogen shall be as follows: 用氮气吹扫和干燥氧气的标准应是列举如下：ZONE区域O2 CONCENTRATION(VOL %)氧气浓度DEW POINT露点(AT ATMOSPHERIC PRESSURE) 在大气压力下A: INNER TANK AND DOME SPACE内罐和顶部空间 8%BELOW 20 C低于-20 CB: ANNULAR SPACE夹层 8%BELOW 20 C * NOTE低于-20 C*注释Criteria of Nitrogen purging using Product gas shall be as follows: 用产品气体吹扫和干燥氮气的标准应是列举如下：ZONE 区域N2 CONCENTRATION(VOL %)氮气浓度DEW POINT露点(AT ATMOSPHERIC PRESSURE) 在大气压力下A: INNER TANK AND DOME SPACE 内罐和顶部空间 8%BELOW 20 C低于-20 CB: ANNULAR SPACE 夹层98%Dew point露点 -60CFlow rate流量300-600 nmchnmch = normalised metre 3 per hour5 NITROGEN PURGE AND DRY OUT氮气吹扫和干燥5.1 Purge and dry out inner tank Zone A (Step 1) 内罐区域A吹扫和干燥（步骤1）a) Monitor the tank pressure during purge and dry out. 在吹扫和干燥过程中监测储罐压力b) Ensure Nitrogen bottom purge valve N4, annulus purge valve N16 and Bottom purge valves N23A & B are closed during purge of inner tank. 确保底部进气阀N4、夹层排气阀N16、底部排气阀N23A&B在吹扫内罐的过程中是关闭的。c) Open valve on purge inlet nozzle (N 15) and introduce Nitrogen gas into the inner tank. 打开N15管口上的阀门，吹扫氮气通过此管口进入内罐。d) When the inner tank pressure reaches 400mm H2O open the valve on purge vent nozzle (N17) and discharge the purge gas to atmosphere. 当内罐压力达到400mmH2O时，打开吹扫排放管口N17上的阀门，吹扫气体从此管口排放出去。e) Ensure that the Nitrogen gas is supplied at a rate between 300 to 600 Nm3/hr. Start purge at the lower rate and gradually increase after 4 hours. 确保氮气在300到600 Nm3/hr之间，在较低比率时开始吹扫，在4小时后逐渐上升。f) Monitor the O2 concentration and the dew point of the vented Nitrogen gas at N 17. When the O2 concentration and dew point of the vented Nitrogen gas at N1 7 is approaching the required levels as defined in section 2 above then proceed to the next section(step2). 监测N17排放出氮气中的氧气浓度和露点。当氧气浓度和露点接近在第2部分定义的要求时，然后进入下一步骤（步骤2）。5.2 Purge and dry out zone B (step 2) 区域B吹扫和干燥（步骤2）a) When the Oxygen concentration at N1 7 is less than 8% during purge of the inner tank and roof space as described above open the valve N16 to commence purging of zone B. 当在N17位置在内罐和顶部空间吹扫过程中如上叙述氧气浓度低于8%时，打开N16阀门开始吹扫区域BWARNING, ENSURE ALL PRECAUTIONS ARE IN PLACE TO ENSURE ALLPERSONNEL ARE PROTECTED FROM SUFFOCATION FROM NITROGEN GAS DURING THE PURGE OPERATION. 警告，确保所有预防措施到位以保证所有人员受到防护，避免在吹扫过程中因氮气导致窒息。b) Monitor the O2 concentration and the dew point of the vented Nitrogen gas at N 17. 监视N17排放出氮气中的氧气浓度和露点c) When the vented gas and dew point of the vented Nitrogen gas at N1 7 are below the required levels as defined in section 2 above reduce the supply rate of Nitrogen and then close nozzle N1 7. The supply rate of the Nitrogen should be adjusted to avoid over pressurising the outer tank. It is important to purge the annular space slowly to avoid the purge gas tunnelling through the resilient blanket alone. 当排放气体和N17位置排放氮气的露点低于在第2部分定义的要求时，降低氮气的供气量然后关闭管口N17。氮气供气量应调节以避免对外罐施加过多的压力。缓慢置换夹层是很重要的，要避免产生隧道效应（吹扫气体只单独穿过弹性毯）d) Proceed to the next section (step 3). 进入下一步骤（步骤3）5.3 Purge and dry out bottom (step 3) 底部吹扫和干燥（步骤3）e) When the Oxygen concentration at N16 is less than 10% during purge of the annular space as described above open valves N4, N23A & B to commence purging of the bottom insulation. 当吹扫夹层过程中如上所述N16位置处氧气浓度低于10%时，打开N4、N23A&B阀门开始吹扫底部绝热层。WARNING, ENSURE ALL PRECAUTIONS ARE IN PLACE TO ENSURE ALLPERSONNEL ARE PROTECTED FROM SUFFOCATION FROM NITROGEN GAS DURING THE PURGE OPERATION. 警告，确保所有预防措施到位以保证所有人员受到防护，避免在吹扫过程中因氮气导致窒息。f) Monitor the O2 concentration and the dew point of the vented Nitrogen gas at N23A & B. 监测N23A&B排放氮气中氧气浓度和露点g) When the concentration and dew point of the vented Nitrogen gas at N23A & B is below the required levels as defined in section 2 above then close nozzles N4, N23A & B and reduce the supply rate of Nitrogen. The supply rate of the Nitrogen should be adjusted to avoid over pressurising the outer tank. 当N23A&B排放氮气的浓度和露点低于如上所述第二部分中定义的要求时，关闭管口N4、N23A&B，以及降低氮气供气量。氮气供气量应被调节以避免对外罐施加过多的压力h) Proceed to the next section (step 4). 进入下一步骤（步骤4）5.4 Purge and dry out of nozzles and zone B (step 4) 管嘴与区域B吹扫与干燥（步骤4）a) During the purging of zone B purge out all nozzles and roof top piping. Open each valve on all nozzles, piping and appurtenances to purge any entrapped air. 在吹扫区域B时，吹扫所有管口和顶部管道，打开所有管口、管道、附件的阀门进行吹扫任何位置夹带的空气。b) Monitor the O2 concentration and the dew point of the vented Nitrogen gas at each point. 在每一位置监测排放氮气的氧气浓度和露点。c) When the vented gas and dew point of the vented Nitrogen gas at each purge point is below the required levels as defined in section 2 above then close the relevant valve. 当排放氮气的露点低于第2部分所定义的要求时，关闭相关阀门。d) Close all valves on all nozzles, piping and appurtenances. 关闭所有管口、管道、附件的阀门。e) Close the purge supply valve N15.关闭吹扫气体供给阀N15。f) Close the annular purge valve N16. 关闭夹层放气阀N166 PRODUCT GAS PURGE产品气体吹扫6.1 Initial conditions初始条件a) Ensure all permanent pressure and vacuum relief valves are operational. 确保所有的固定压力和真空解除阀是可使用的。b) Disconnect all temporary piping, if any, associated with Nitrogen purging and dry out. 如果有与氮气吹扫和干燥相关的临时性管道，全部拆除。c) Ensure that all instruments, such as the following are in operational condition. 确保所有仪表是可使用的，例如如下几种：i. Temperature sensors. 温度传感器ii. The tank gauging systems. 储罐度量系统iii. Pressure sensors. 压力传感器6.2 Product Gas purge Zone A (step 5) 产品气体吹扫区域A（步骤5）a) Ensure annulus purge valve N16 is closed after Nitrogen purge of inner tank. 确保在内罐氮气吹扫之后夹层放气阀N16是关闭的。b) Ensure warm (ambient temperature) Product gas is connected and available to the product supply line either via the process or via the injection point on the pipe rack. 确保环境温度下“产品气体”已经通过管线输送到储罐，并能满足吹扫需要量。c) Open the valve on the boil off gas outlet nozzle N6 to vent the Nitrogen gas in the tank, replacing it with warm (ambient temperature) Product gas. 打开管口N6的BOG阀门以排放储罐内的氮气，用环境温度下的“产品气体”置换罐内的氮气。d) Open the bottom product inlet valve N2 and introduce Product gas into the tank. 打开底部进液阀N2引导产品气体进入储罐。e) Warning: ensure that only warm product gas is allowed into the tank at this stage. On no account should cold product be introduced into the line. 确保在这阶段中进入储罐的是环境温度下的产品气体，切莫使冷的产品气体进入供给线。f) Monitor the concentration of Product gas in the boil off gas line. 监测BOG管线上“产品气体”的浓度。g) When the Product gas concentration reaches 92% open N17 to purge the dome space of Nitrogen. 当“产品气体”的浓度达到92%，打开N17以吹扫顶部空间的氮气6.3 Product gas Purge, Zone B (step 6) 产品气体吹扫区域B（步骤6）a) When the Nitrogen concentration at N1 7 is less than 8% during purge of the inner tank and roof space as described above, open the valve N16 to commence purging of zone B. 当内罐和顶部空间吹扫过程中N17位置氮气浓度低于8%，打开N16阀门开始吹扫区域Bb) Monitor the N2 concentration and the dew point of the vented Nitrogen gas at N16. 监测N16位置排放氮气的氮气浓度和露点c) When the vented gas and dew point of the vented Nitrogen at N16 is below the required levels as defined in section 2 above then close nozzle N 17 and reduce the supply rate of Product gas. The supply rate of the Product gas should be adjusted to avoid over pressurising the outer tank. It is important to purge the annular space slowly to avoid the purge gas tunnelling through the resilient blanket alone. 当排放气体以及N16位置处排放氮气的露点低于第2部分所定义的要求时，关闭管口N17和降低“产品气体”的供给量，“产品气体”的供给量应被调节以避免对外罐施加过多的压力，缓慢置换夹层是很重要的，要避免产生隧道效应。6.4 Product gas purge of nozzles (Step 7)产品气体吹扫管口（步骤7）a) After closing nozzle N1 7, purge out the nozzles and roof top piping. Open each valve on all nozzles, piping and appurtenances to purge any entrapped Nitrogen. 在关闭管口N17之后吹扫管口和顶部管道，打开所有管口、管道、附件的阀门以吹扫任何夹带氮气。b) Monitor the N2 concentration and the dew point of the vented Nitrogen gas at N16. 监测N16位置排放氮气的氮气浓度和露点。c) When the vented gas and dew point of the vented Nitrogen gas at each purge point is below the required levels as defined in section 2 above then close the relevant valve. 当各位置排放气体和排放氮气的露点低于第2部分所定义的要求时，关闭相关阀门d) Close all valves on all nozzles, pump columns, piping and appurtenances. 关闭所有管口、泵柱、管道和附件处的阀门。e) Close the Product supply valve N2. 关闭产品气体供给阀N2。f) Close the Purge valve N16. 关闭放气阀N16。g) Close the Boil off gas valve N6. 关闭BOG阀门N6。h) Re-install blanking flanges for in service arrangement of nozzles where appropriate. 相关的吹扫管口重新安装盲法兰以实现使用中对管口的要求。7 COOL-DOWN冷却7.1 Initial conditions (step 8) 初始条件（步骤8）a) The tank shall be cooled down at a controlled rate to prevent thermal stressing of the inner tank. 储罐冷却应受到控制，以预防内罐热应力收缩太大。b) The following parameters govern the operation. 以下因素控制操作要求。i. Inner tank cooling shall be controlled at 3C per hour. Maximum permissible cooling measured at any thermocouple shall not exceed 5C per hour. 内罐冷却控制在每小时3C。在任何热电偶处最大允许的冷却率不应超过每小时5Cii. The maximum differential temperatures between adjacent thermocouples shall not be greater than 20C. 临近的热电偶最大差异温度值不应大于20Ciii. The maximum differential temperatures across all thermocouples shall not be greater than 50C. 所有热电偶最大差异温度值不应大于50Civ. The tank pressure shall not exceed the operating pressure. 储罐压力不应超过工作压力。7.2 Recommended Cooldown using product. 推荐用产品冷却Assumed start temperature假设开始温度35CFlow rate for cooldown spray nozzle冷凝喷嘴流量32 l / min at 3 barFlow rate for cooldown spray nozzle冷凝喷嘴流量42 l / min at 5 barEstimated time for cooldown冷却估计时间228 hoursEstimated quantity of LNG required for cooldown 185 tonnes冷却用LNG估计需求量Liquid heel in bottom of tank罐底液体根部300 mmQuantity of LNG foliquid heel LNG液体根部数量147 m 3Estimated quantity of LNG for liquid heel 62 tonnesLNG液体根部估计数量Total quantity of LNG LNG总量( cooldown + liquid heel) （冷却用+液体根部）247 tonnes-120-160-200-40-80400050100150200250LNG Cooldown185 tonnes of LNG requiredTime in Hours32 lp m 3bar 41.9 lp m 5barTank available for the introduction of product7.3 Cool-down process (step 9) 冷却过程（步骤9）a) Open the valve on the boil off outlet nozzle N6 to allow the Product gas to be discharged. 打开N6 BOG出口使产品气体排放出来。b) Introduce LNG through the pro