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合成氨装置氨合成单元危险有害因素分析及对策

摘 要： 本文结合齐鲁达州化肥分公司合成氨装置建设与开工情况,对其氨合成单元的危险有害因素进行辨识，提出了一系列针对性措施，对于确保装置的安全稳定运行具有一定的积极意义。

关键词：合成氨装置；氨合成单元 ；危险有害因素； 分析 ；对策

1.概述

中国石油化工股份有限公司齐鲁分公司达州化肥项目（以下简称“齐鲁达化项目”）是以中国石化普光气田天然气为原料，依托达州市天然气能源化工产业区的工业水.电.道路.消防及污水处理等公用工程设施，将齐鲁分公司闲置的30万吨/年合成氨和48万吨/年尿素装置搬迁至达州市天然气能源化工产业区进行同规模重建。搬迁后的化肥装置工艺流程在原工艺基础上进行了节能.环保等适应性改造，并新建与装置配套的公用及辅助工程设施。其合成氨装置系上世纪70年代由日本东洋工程公司(TEC)成套引进，采用当时国际上比较先进.成熟可靠的美国凯洛格公司技术。该装置2006年10月26日土建开工，2008年12月26日装置实现中交，2010年1月19日产出合格液氨产品，装置开车一次成功。由于该装置2002年已停产，本次迁建中存在着装置设备老化.设计不足等困扰装置稳定运行因素较多，另外合成氨装置本身具有单系列.大型化的工艺特点，氨合成单元作为该装置的核心组成部分，高温.高压.临氢，其操作条件脆弱.工艺波动损失大，因此有必要对该单元定期进行危险有害因素分析，找出制约安全稳定运行的瓶颈，预先采取针对性措施，确保装置的安全稳定运行。

2.危险有害因素分析

2.1.1合成气的压缩.氨合成来自甲烷化的工艺气（温度37.8℃，压力2.35MPa）经氨冷器冷却至7.2℃（2.530MPa），与普里森回收的低压氢气混合后送合成压缩机一段。一段出口压力约为6.38MPa，抽取少量作为脱硫加氢用，其余气体经冷却.分离与普里森回收的高压氢混合后再进入二段压缩，出二段压力为15.75MPa，冷却.分离后进入第三段压缩。三段出口压力为22.48MPa。三段出口的新鲜气和合成塔出来的循环气混合，经水冷却后分为两路：一路经第一氨冷器.第二氨冷器，使温度降至7.2℃；另一路经热交换器换热，温度降至7.2℃，这两路气体混合后，再经第三氨冷器，使温度降至－12.2℃，进入氨分离器分离液氨后，气体再经热交换器复热至23.9℃，进入合成气压缩机第三缸循环段压缩至23.54MPa后，经换热器温升至140.6℃进入合成塔进行氨合成反应。

出塔合成气中的NH3达13.6%。经锅炉水加热器和换热器换热后与103-J三段压缩机出口的新鲜气混合。如此反复循环。

为了控制循环过程惰性气体CH4和Ar浓度，需弛放一部分合成塔出口气。弛放气经氨冷器冷却，使所含氨大部分被冷凝，然后进弛放气分离器，回收液氨，排出的气体进入普里森装置回收氢气，回收的氢气送回合成气压缩机作为合成原料，尾气作为燃料送出。

合成系统设置了一台开工加热炉（102-B）供开车催化剂升温还原和停车后再开车时加热进塔气用。

从弛放气分离器分离出来的液氨，经减压进入液氨储槽，液氨送往冷冻系统。

2.1.2冷冻系统

该系统供合成氨用的冷冻量并按要求的温度和流量输送去氨库和尿素装置。

由液氨储槽来的液氨，一部分送第二闪蒸槽，一部分送冰机储槽闪蒸气氨冷却器，其余送至三级氨闪蒸槽，以保持中间储槽液位稳定。第一.第二.第三氨冷器是按热虹吸原理冷冻蒸发循环操作的，一级氨闪蒸槽出来的液氨除送一级氨冷器外，另一部分作为第一段入口氨冷器.出口氨冷器和弛放气氨冷器冷冻用。后三用户蒸发的气氨进入二级氨闪蒸槽。一级氨闪蒸槽多余的液氨送往二级氨闪蒸槽。二级氨闪蒸槽的液氨除送第二氨冷器外，其余部分作为弛放气氨器冷冻用。

为了供给合成系统冷冻量，并按合成系统的温度及流量输送成品液氨，设置了一台两缸三段离心式冰机。由112-F出来的气氨送入离心式冰机一段压缩，一段出口与111-F出来的气氨汇合后进入二段压缩，二出口先经水冷器冷却后再与110-F来的气氨汇合进入第三段压缩，三段出口的气氨经水冷后，送入液氨储槽。液氨储槽闪蒸气去闪蒸气冷却器将气体中的氨冷凝分离出来，送往110-F。液氨储槽的液氨抽出经热液氨泵加压与冷凝氨汇合，送往尿素。

2.2危险有害因素识别

2.2.1压缩

(1)压缩机入口压力2.35MPa，出口压力24MPa，为离心式压缩机。压缩机组压力高.转速高.功率高,工艺气中H2气含量高，如压缩机密封.气封损坏，高压气流外泄，极易引发着火.爆炸事故。

(2)压缩机各级分离器液位过高，气体带液进入气缸，会造成叶片及缸体损坏；液位过低，则高压工艺气窜出也可引发爆炸.火灾爆炸。

2.2.2合成（包括氢回收.制冷）

(1)合成系统压力高达24MPa，工艺气中含有H2.N2.NH3.CH4等气体，高压气体一旦发生泄漏，由于压力高，工艺气中H2浓度高，可引发重大着火.爆炸事故。

(2)生产运行中极易发生超压.超温等异常，引发催化剂损坏.设备损坏及爆炸事故。

(3)停车期间，空气有可能漏入合成塔内，如果空气漏入塔内，不仅会使合成催化剂超温.烧毁，甚至还可造成设备损坏而引发重大事故。

(4)合成系统在运行中如氨分离器液位超低，高压工艺气有可能窜入中压氨罐，造成中压氨系统超压而发生爆炸。

(5)合成驰放气经洗涤回收氨后，进入普里森装置回收氢气，由于压力高，工艺气发生泄漏，也可引发爆炸.着火事故。

(6)合成气压缩机入口气用氨冷却，合成系统工艺气也采用氨冷，单元中设有离心式氨压缩机一台，用来制冷。如果氨发生泄漏，不但会造成人员中毒，也可引发着火.爆炸事故。

(7)氨压缩机入口气氨如果发生带液，液氨进入气缸可损坏叶片.缸体.气封，如果发生氨泄漏，也可引发中毒或火灾.爆炸事故。

(8)润滑油或密封油如果外泄，透平机壳温度高达300℃以上，易引发火灾。

2.2.3氨贮存

设有低温.低压贮罐一台，容量5000M3及事故冰机系统。

(1)若液氨发生泄漏，可引发中毒或着火.爆炸事故。

(2)由于液氨贮存量大，若储罐超压而损坏或爆炸，液氨发生大量泄漏，可造成重大人员中毒或着火.爆炸事故。

2.2.4中毒窒息

(1)高压氨分离器（106-F）液体若窜入低压氨中间贮罐（107-F），会发生爆裂而引发的火灾事故外，喷出的液氨接触到人体还会 生人员中毒事故。

(2)氨冷冻系统有三台氨闪蒸罐.三台氨冷凝器和多台氨贮罐和多台氨冷凝器组成。其设备.管线.阀门发生泄漏，漏出的液氨接触到人体会发生中毒和窒息危险事故。

(3)氮吸收塔和洗涤塔发生泄漏，漏出的液氨或氨水亦会造成人员中毒事故。

(4)氨合成塔在卸催化剂过程中，塔内要充满N2气，作业人员进入塔作业，若长管面具质量不好或接头处松开，就会发生人员窒息事故。

(5)冰机（105-J）系统所压缩介质是气氨,出口压为1.7MPa，其设备的法兰.阀门.管线发生泄漏，漏出的氨接触到人体会发生中毒和窒息危险事故。

3.对策实施

3.1压缩

(1)加强应急管理，建立联动应急机制，现场配备必要的消防设备和报警装置。

(2)加强设备管理，严格大机组管理，杜绝泄漏事故发生。

(3)压缩机各级分离器液位设置报警联锁，加强工艺控制，严格巡回检查，防止液位过低或过高现象发生。

3.2合成（包括氢回收.制冷）

(1)开工前严格气密试验.运行中加强巡检，配备便携式H2.CH4.CO监测仪，定期检查固定式H2.N2.NH3.CH4报警仪运行状况，确保发生泄漏时及时发现并处置。

(2)经评估现有装置配备的联锁保护系统可以满足工艺需要，生产运行中应加强巡回检查，及时跟踪各工艺指标变化，防止发生超压.超温等异常。

(3)停车泄压期间，严格按停车方案操作，及时通入合格的保护氮气，杜绝空气漏入合成塔内。

(4)合成系统在运行中加强对氨分离器液位的管理，防止高压工艺气窜入中压氨罐。

(5)合成系统现场设置有氨泄漏报警仪，岗位操作人员配备有便携式氨监测仪，应定期效验监测报警仪，制定氨泄漏应急预案，同时要求进入现场的操作人员必须携带便携式监测仪，遇有异常及时处置或撤离。

6.严格控制氨压缩机入口气氨带液。

3.3氨贮存

(1)若液氨发生泄漏，应立即启动(1)若液氨发生泄漏，应立即启动应急管理程序及时处理异常，防止事故扩大。

(2)由于液氨贮存量大，故储罐应严防超压操作，定期检查事故冰机系统，确保正常循环。

3.4中毒窒息

精心操作，严格劳保护品的穿戴，严格执行各项规章制度。

4.结语

本次风险识别是我们在装置停车期间组织进行的，当然由于水平所限，所作分析及对策制定可能不够全面，需要在以后的工作实践中进一步完善提高。但是通过此项工作，使得各级管理人员.操作维护人员对于氨合成单元有了进一步的认识，必将对于装置的安全长周期运行发挥积极作用，我们也期待着能够得到专家同行的批评指正。

论文出自《城市建设理论研究》作者：张世兴

翻译

Ammonia plant of ammonia synthesis unit dangerous and harmful factors analysis and countermeasures Pick to: this paper qilu branch dazhou chemical fertilizer ammonia plant construction and construction conditions, the identification was carried out on the dangerous and harmful factors of ammonia synthesis unit, put forward a series of specific measures, to ensure the safe and stable operation of plant has certain positive meaning.Key words: ammonia plant;Ammonia synthesis unit;Dangerous and harmful factors;Analysis;countermeasures 1.An overview of the China petroleum and chemical co., LTD., dazhou chemical fertilizer project of qilu branch(hereinafter referred to as the “qilu project”)in puguang gas field of sinopec gas as raw materials, relying on DaZhouShi energy of natural gas chemical industry area of industrial water.Electricity.Road.Fire and sewage treatment and other utility facilities, the qilu branch spare 300000 tons/year synthetic ammonia and 480000 tons/year urea plant moved to DaZhouShi energy of natural gas chemical industry area with scale reconstruction.After the relocation of technological proce in chemical fertilizer plants on the basis of the original proce for energy saving.Adaptive transform, such as environmental protection and new public and aided engineering facilities and equipments.The ammonia plant is in the 1970 s by toyo engineering corporation(TEC)package import, by the more advanced at that time.Mature and reliable Kellogg company technology in the United States.The device on October 26, 2006 the civil construction, on December 26, 2008 device implementations, 19 January 2010 nian of qualified products, liquid ammonia device to drive a succe.Due to the unit has been shut down in 2002, the relocation of the devices exist aging.Troubled device and stable operation factors such as insufficient design is more, in addition with single series, ammonia plant itself.The proce characteristics of bigne, ammonia synthesis unit as a core component of the device, high temperature, high preure, hydrogen, its operating conditions, fragile.Lo of volatile, so it is neceary for the unit analysis of dangerous and harmful factors on a regular basis, find the safe and stable operation of the bottleneck, targeted measures in advance, to ensure the safe and stable operation of the plant.2.The dangerous and harmful factors analysis 2.1.1 the compreion of the syngas.Ammonia synthesis From the methanation proce gas(temperature 37.8 ℃, preure 2.35 MPa)the ammonia cooler cooling to 7.2 ℃(2.530 MPa), and general ellison recycling of low-preure hydrogen blend to give a synthetic compreor.Preure of 6.38 MPa, exported from a small amount for hydrogenation desulfurization, the remaining gas cools.Separation of mixed with ellison recycling's high-preure hydrogen into two stage compreion, again after a two stage preure is 15.75 MPa, cool.After separation into the third period of compreion.Three sections of outlet preure is 22.48 MPa.Three sections of the export of fresh air and synthetic DaChu to recycle gas mixing, the water cooling is divided into two after the road: a path first ammonia cooler.The second ammonia cooler, the temperature dropped to 7.2 ℃;Another path heat exchanger heat transfer, the temperature dropped to 7.2 ℃, the gas mixture, then through the third ammonia cooler, the temperature dropped to 12.2 ℃, enter the ammonia separator after the separation of liquid ammonia, then through gas heat exchanger after heat to 23.9 ℃, the third cylinder into syngas compreor cycle period of compreed to 23.54 MPa, the temperature rise of the heat exchanger and 140.6 ℃ in the ammonia synthetic tower is synthetic reaction.The tower of the syngas NH3 was 13.6%.After boiler water heater and heat exchanger heat exchanger with 103B)for driving the catalyst reduction and parking of gas heating when driving into the tower again after use.From chi put the separated liquid ammonia gas separator, the relief into the liquid ammonia tank, liquid ammonia to the refrigeration system.2.1.2 refrigeration system Department TongGong ammonia refrigeration quantity and temperature according to the requirement and flow conveying to ammonia and urea device.By the liquid ammonia tank of liquid ammonia, part sent the second flash tank, part of the flash steam ammonia cooler sent ice storage tank, the rest of the sent to the three levels of ammonia flash tank, to maintain the reservoir level stability in the middle.First.Second.The third is according to the thermal siphon principle refrigeration cycle of ammonia tanks, level of ammonia flash tank of liquid ammonia in addition to send 1 ammonia cooler, the other part as the first section of the entrance to the ammonia cooler.Export ammonia cooler and chi deflated ammonia cooler with frozen.Three users after the evaporation of ammonia gas into the secondary flash ammonia tank.Level of flash trough exce ammonia liquid ammonia to secondary ammonia flash tank.Secondary ammonia flash tank of liquid ammonia in addition to send the second ammonia cooler, as the rest of the enterprisesin deflated ammonia refrigeration with.Frozen quantity in order to supply synthetic system, and according to the temperature of the synthetic system and flow conveying liquid ammonia products, set up a two cylinder three sections of the centrifugal ice machine.By 112F out ammonia converge into two stage compreion and two export first after water cooler cooling again joins gas ammonia 110F.Liquid ammonia storage tank of liquid ammonia extraction by hot liquid ammonia pump preure and condensing ammonia rendezvous, sent to urea.2.2 dangerous and harmful factors identification 2.2.1 compreion(1)compreor inlet preure is 2.35 MPa, 24 MPa, the outlet preure of centrifugal compreor.Compreor high preure, high speed.High power, high H2 gas content in the proce of gas, such as compreor seal.Seal damage, leakage of high preure air flow, easy to cause fire.The explosion.(2)compreor separator liquid level is too high, at all levels of gas liquid into the cylinder, will cause the damage of blade and the cylinder body;Liquid level is too low, the high preure proce gas channeling out also can explode.Fire explosion.2.2.2 synthesis(refrigeration)including hydrogen recovery.(1)synthesis of system preure as high as 24 mpa, proce gas containing H2.N2 NH3.CH4 gas, such as high preure gas, once leak, because of high preure, the proce of gas H2 concentration is high, can cause a major fire.The explosion.(2)the overpreure occurred easily in the production run.Overtemperature and other abnormal, lead to catalyst damage.Equipment damage and explosion accidents.(3)during the parking, synthesis tower may leak into the air, if the air leakage into the tower, not only can make the synthesis catalyst overtemperature.Burned, even can cause equipment damage caused a serious accident.(4)synthesis system in operation such as ammonia separator liquid level low, high preure proce gas into the medium preure ammonia tank likely, medium preure ammonia system overpreure caused an explosion.(5)after washing recovery of ammonia synthesis chi is deflated, enter at ellison device recycle hydrogen, because of high preure, the proce gas leak, also can explode.Fire accidents.(6)the syngas compreor cooling into the breath with ammonia and synthesis gas system proce also USES ammonia cold, an ammonia centrifugal compreor unit, used for cooling.If ammonia leakage occurs, not only will cause poisoning, also can cause fire.The explosion.(7)ammonia compreor in the tone in the event of liquid ammonia, ammonia into the cylinder can damage the blade.Cylinder.Gas seal, in the event of ammonia leakage, also can cause poisoning or fire.The explosion.(8)or if the sealing oil leakage of lubricating oil, turbine casing temperature as high as 300 ℃ above, easy to cause fire.2.2.3 ammonia storage Have a low temperature.A low preure storage tank, the capacity of 5000 m3 ice machine systems and accidents.(1)if the liquid ammonia leakage occurs, can cause poisoning or catch fire.The explosion.(2), because of the large amount of liquid ammonia storage tank damage or explosion overpreure, liquid ammonia large leakage occurs, can cause significant personnel poisoning or catch fire.The explosion.2.2.4 poisoning choke(1)high preure ammonia separator(106F), may burst and cause of the fire accident, spewing liquid ammonia will come into contact with the human body Personnel poisoning accident.(2)the ammonia refrigeration system has three ammonia flash tank.More than three sets of ammonia condenser and ammonia storage tank, and many sets of ammonia condenser.Their equipment.Pipeline.Valve leakage, leakage of liquid ammonia poisoning and choking dangerous accident came into contact with the body.(3)nitrogen absorption tower scrubber and leakage, leakage of liquid ammonia and ammonia also can cause poisoning accident.(4)in the proce of unloading catalyst ammonia synthetic tower, the tower shall be filled with N2 gas, and people working in tower mask if long tube quality is bad or loosen, the joint staff suffocation accident occurs.(5)ice machine(105-J)system of compreed medium is ammonia gas, outlet preure is 1.7 MPa, the flange of the equipment.Valve.Pipeline leakage, leakage of ammonia poisoning and choking dangerous accident came into contact with the body.3.The countermeasures of implementing 3.1 compreion(1)to strengthen the emergency management and establish emergency linkage mechanism, the scene is equipped with the neceary fire fighting equipment and alarm devices.(2)to strengthen equipment management, large sets of strict management, to eliminate leakage accidents.(3)compreor separator liquid level set alarm interlocking, at all levels to strengthen the proce control and strictly carry out inspection, prevent the phenomenon of liquid level too low or too high.3.2 synthesis(refrigeration)including hydrogen recovery.(1)strictly air test before start working.In the operation of the strengthen inspection, equipped with portable H2, CH4, CO monitor, regularly check the stationary H2.N2 NH3.CH4 alarming device running status, ensure the timely discover and dispose of the leaking.(2)the evaluation of existing device equipped with interlocking protection system can meet the demand of proce, should strengthen the inspection tour in the operation of production, timely tracking every technical index change, prevent overpreure.Overtemperature anomaly, etc.(3)during the parking preure, parking program operation, in strict accordance with the timely acce to qualified nitrogen protection, prevent air leakage into the synthesis of the tower.Synthesis system(4)strengthen the management of ammonia separator liquid level in the operation, to prevent the high preure proce gas into the medium preure ammonia tank.(5)synthesis system with ammonia leakage alarming device, set up posts operating personnel are equipped with a portable monitor, ammonia should be verified regularly monitoring and alarming device, making ammonia leak emergency plans, also required to enter the scene of the operating personnel must carry a portable monitor, in case of abnormal timely or withdrawal.6.The strict control of ammonia compreor in ammonia liquid.3.3 ammonia storage(1)if the liquid ammonia leakage, should immediately start(1)if the liquid ammonia leakage, should immediately start emergency management procedures timely handle exceptions, prevent accident expanding.(2)because of the large amount of liquid ammonia storage, so storage tank should be protected from overpreure operation, regular check accident ice machine system, to ensure the normal circulation.3.4 poisoning choke Careful operation and strict wear labor protection products, strictly implement the rules and regulations.4.Conclusion The risk identification is our parking organization during the period of the device, due to the limitation of the level, of course, made analysis and countermeasures for may not be comprehensive enough, need to further improve in the later work practice.But through this work, make management personnel at all levels.Operation and maintenance personnel for ammonia synthesis unit had the further understanding of, will certainly to device safe and long period operation of play a positive role, we also look forward to receive peer experts comment.Papers from the studies of urban construction theory author: Zhang Shixing