空气化工空分工艺流程.doc

中国石油四川石化炼化一体化工程 - 空分装置PetroChina Sichuan Refinery & Ethylene Complex Project-ASU1.0 设备选择和流程说明 Equipment selection and Process description1.1 工艺流程概述 Process description本装置以空气为原料，冷却水为辅助原料，经空气压缩、空气净化与冷却以及精馏分离等过程，将空气分离得到氧气、氮气、液氧、液氮和液氩。大致流程叙述如下(详细说明参见文件工艺流程描述DOC0000382869)：The primary raw material in the air separation process is atmospheric air, with auxiliary utilities of cooling water and lubrication oil for machinery. Nitrogen, Oxygen and Argon are separated from the air by a process of compression, liquefactioin and cryogenic distillation. The products may be recovered in both gaseous and liquid phase. Brief process is summarized below and details refer to document”Process Description” DOC0000382869:1.1.1 空气压缩Air compression空气从入口空气过滤器吸入，过滤除去悬浮固体颗粒(污物,灰尘等)后，经主空压机入口消音器，削弱从压缩机第一级叶轮产生的噪音，然后进入K111主空压机(MAC)进行压缩。Air is drawn through the Inlet Air Filter to remove suspended solid particles (dirt, dust, etc.) and then passes through the MAC Suction Silencer which attenuates the noise radiating from the first stage impeller. The air is then compressed in the K111 Main Air Compressor (MAC).空气被压缩后温度会升高。在压缩机各级之间设管式中间冷却器，采用冷却水来冷却并将压缩产生的热量带走。经主空压机压缩后的空气仍含有水份。随着空气压力上升，其存留水份的能力降低，水份会因冷却而被凝结成冷凝水。在中间冷却器的气体侧安装有冷凝水疏水器来分离和排除这些冷凝水。Compressing the air increases its temperature. This heat of compression is removed between the stages of compression by cooling water in the shell-and-tube intercoolers. The air being compressed in the main air compressor contains water vapor. As the pressure of the air increases, the airs ability to hold water decreases and water vapor condenses to form condensate. Condensate traps are installed on the gas side of the intercoolers to trap and drain the water condensed by compression and cooling.从空压机末级流出的热空气从底部进入空气冷却塔（或称DCAC）C161，在这里，空气经与冷却水（塔的下部）以及冷冻水（塔的上部）直接接触而被降温。所需要的冷冻水由冷冻水塔C171来产生并通过冷冻水泵G171A/B压入空气冷却塔。在C171塔内，冷却水与来自冷箱的部分干燥污氮直接逆流接触，干燥污氮与水的接触使部分液态水蒸发并随污氮排放,同时冷却水降温，形成低温冷冻水。The warm air from the last stage of the compressor flows to the Direct Contact Aftercooler or DCAC. The warm air is cooled by direct contact with cooling water (in the lower section) and with ciller water (top section). The chilled water for the direct contact aftercooler is produced by the C171 Chilled Water Tower and pumped by the G171A/B Chilled Water Pumps. The C171 chills cooling water using evaporative cooling by direct contact with a portion of the dry nitrogen waste from the cold box.1.1.2 空气净化与冷却Air impurity removal and cooling从空气冷却塔出来的冷空气从底部进入四个C182A/B/CD TSA吸附器之中的两个。每个吸附器中均含有吸附剂，用以除去大部分碳氢化合物、水和二氧化碳，产生洁净干燥的空气。这四个吸附器可交替吸附和升温再生循环使用；也就是说，两个吸附器在吸收空气中所含有的杂质的同时，另两个吸附器则被加热的干燥污氮再生。来自主换热器的部分干燥污氮用中压蒸汽加热后进入被杂质饱和的吸附器，带走吸附器床层上被吸附的杂质，从而使吸附器再生。这种吸附和再生的顺序操作在DCS控制下自动重复进行，可不需要操作人员干涉。位于吸附容器内的自洁式过滤器能够防止在吸附器内的微粒被带出吸附器。The cool air leaving the DCAC enters the bottom of two of the fourTSA Adsorber Vessels (C182A/B/C/D). Each vessel contains adsorbents that remove water, carbon dioxide, and some hydrocarbons to produce a clean, dry air stream. The vessels operate on an alternating temperature swing adsorption cycle; that is, two vessels are adsorbing the contained impurities while the other two vessels are being regenerated by dry nitrogen waste. A portion of the waste nitrogen from the main heat exchanger is heated by a MP steam heat exchanger to remove the adsorbed impurities from the saturated bed. This sequence is repeated automatically, is controlled by the DCS, and requires no operator intervention. Self-cleaning filters located inside the adsorbent vessels prevent dust carryover from the adsorber. 从吸附器TSA出来的部分干燥空气在主换热器E201内被冷却后进入高压塔。部分空气进入1# 空气增压机K131中被进一步压缩，在主换热器E201内与液氧换热后被冷凝，然后分两股进入高/低压塔系统。一部分空气从增压机K131级间抽出，经由压缩膨胀机K261压缩后进入主换热器E201，再经E201中间抽出后，经压缩膨胀机K261膨胀后产生液化装置所需的冷量，进入高压塔。Part of the dry air enters the cold box directly, being cooled in the E201 Main Heat Exchanger and entering the High Pressure Column. A portion of the air is compressed further in the K131 Booster Air Compressor (BAC), then is cooled against boiling LOX in E201 then is fed to HP/LP column. A sidestream is taken from an intermediate stage of BAC to the compander compressor K261, then to E201 to be partially cooled, then to compander expander K261 to make refrigeration, then feed to HP column. 1.1.3 精馏分离获取氧、氮产品O2 and N2 production by distillationC211精馏塔下塔 Hig pressure column送入下塔底部的空气流向上穿过塔板使塔板上的液体部分汽化，其结果是易挥发的氮从液体中挥发，通过交换汽化潜热使穿过塔板空气中的氧被冷凝。这样，氧在向塔底部流动的液体中富积，同时氮气纯度在向塔顶流动的气体中逐步增加，从而在下塔塔釜中得到富氧液空。The vapor portion of the air feeding the bottom of the high pressure column passes up through the column and boils the liquid on the trays. The more volatile nitrogen is boiled out of the liquid and the exchange of latent heat condenses the oxygen out of the air passing up through the trays. As a result, the liquid from the bottom of the column becomes enriched with oxygen, while the vapor passing up to the top of the column steadily increases in nitrogen concentration.下塔C211顶部的纯氮气分为两路，一部分送到精氩塔的精氩再沸器。其他的通过E201主换热器复热，气体经高压氮压机K761压缩后经过管网送给客户。The nitrogen vapor at the top of the column is withdrawn from the high pressure column C211. Some of the nitrogen is sent to the argon purifier to generate boil-up in the C461 Pure Argon Column. while others flows to the E201 Main Heat Exchanger to be superheated, then flows to K761 HP GAN Compressor to be pressurized to HP GAN, then be sent to Customer by pipeline.C211塔上部剩余的冷氮气进主再沸器/冷凝器E213与低压塔C212底的沸点液氧换热冷凝。大部分冷凝后的液氮返回至高压塔C211回流，剩余部分冷凝液氮经过冷器E201冷却后回流至低压塔C212。少量液氮至低压液氮贮罐T721贮存。The remainder of the cold vapor at the top of the column is fed to the E213 Main Reboiler/Condenser where it is condensed by the boiling action of the oxygen liquid from the bottom section of the C212 Low Pressure Column. The major portion of the condensed nitrogen returns to the high-pressure column as reflux. The rest of the liquid stream is subcooled in the E201, and is fed to the C212 Low Pressure Column as pure reflux. A small LIN stream is fed to the T721 LP LIN storage tank.粗液氧由高压塔C211底部抽出送入粗氩塔冷凝器E401，部分液氧于此与粗氩气换热气化，同时粗氩气冷凝。部分气化后的粗氧送至低压塔C212。Crude liquid oxygen is withdrawn from the sump of the high-pressure column. It is transferred to the E401 Crude Argon Condenser. The crude liquid oxygen is partially vaporized by condensing crude argon in the E401. The vapor and liquid portions of the partially vaporized crude oxygen are fed to the low pressure column.C212 精馏塔上塔Low pressure column氧气产品的净化于低压塔C212进行，其精馏工艺与高压塔相同。高压塔的富氮液回流至低压塔C212。The final purification of oxygen takes place in the C212 Low Pressure Column. The distillation process in the low-pressure column is essentially the same as in the high pressure column. Liquid nitrogen-rich reflux from the high pressure column is fed to the low pressure column.产品液氧由主再沸器/冷凝器E213底部抽出，先经过冷器E201冷却后流至LP液氧贮罐T621，再用液氧产品泵G641A/B增至所需产品压力，再经主换热器E201气化后管道送至用户。Product oxygen is withdrawn as a liquid from the low pressure column reboiler sump. It is subcooled in the E201 before flowing to the T621 LP LOX Storage Tank. Liquid oxygen from the T621 is pumped to the required product pressure in the G641A/B LOX Process Pump. The pumped LOX stream is vaporized in the E201 Main Heat Exchanger and is then sent to the customer by pipeline.低压塔顶出的污氮经主换热器E201换热升温后进低温水塔C171冷却DCAC塔来的循环水。另一股低压气氮用于TSA吸附器C182再生。Waste nitrogen is withdrawn from the top of the low pressure column. This stream is warmed in the E201 Main Heat exchanger. The waste gas is fed to the C171 Chilled Water Tower to chill the water for the DCAC. The LP GAN flow from the top of the column is used to regenerate the C182 TSA adsorbers.从上塔顶部抽出的气体为低压纯氮气。纯氮在E201主换热器中复热。经过K701A/B氮压机压缩后送至用户。 Extract from the top of the low pressure column for pure low pressure nitrogen gas. Pure Nitrogen is warmed in the E201 main heat exchanger and compressed by K701A/B to form the GAN product stream. 从下塔顶部抽出的气体为低压纯氮气。纯氮在E201主换热器中复热。经过K701A/B氮压机压缩后送至用户。 Extract from the top of the low pressure column for pure low pressure nitrogen gas. Pure Nitrogen is warmed in the E201 main heat exchanger and compressed by K701A/B to form the GAN product stream. 氩回收Recovery argon从低压塔中部抽出一股富含氩气的气流，送入氩塔C401底部，通过汽液接触，氩气在随气流在塔内上升的过程中逐渐富集，从氧中分离出来。A portion of the argon enriched stream is drawn from the Low Pressure Column and sent to the bottom of Crude Argon Column (C401). The vapor increases in argon concentration as it passes up the column. where the argon is separated from the oxygen by distillation.粗氩塔顶蒸汽在氩气冷凝器E401中部分冷凝。大部分液氩从冷凝器中回流回塔内。小部分液氩送精氩塔C461。The vapor at the top of the crude argon column is partly condensed in the E401 Crude Argon Overhead Condenser. The bulk of liquid argon is refluxed to C401. A small portion of liquid argon is fed to the Pure Argon Column (C461).氩精制Argon purification 从精氩塔顶将氩中所含有的微量氮分离除去。从粗氩塔顶冷凝器来的液氩进入精氩塔中部。液氩在向塔底流动过程中被从塔底上来的气流逐步提纯，部分液氩从塔釜采出，送液氩贮罐T471,其余液氩在精氩塔再沸器中被汽化后，作为精氩塔上升气流。 The Pure Argon Column removes the small amount of nitrogen. The liquid argon flows down through the bottom section of the column, and is enriched in argon by the vapor flowing up through the stages. A portion of the liquid argon from the sump is withdrawn as product and sent to the LAR Storage Tank T471. The remainder is vaporized in the Pure Argon Column Reboiler/Condenser to provide boil-up for the pure argon column. 用从高压塔顶来的氮气再沸器中冷凝来提供再沸汽化热，汽化蒸汽在塔内向上流动，逐级到达塔顶。在蒸汽上升过程中，不断使向下流动的液氩中的氮气化而使氮气在塔顶富集，上升气在塔顶冷凝器中被部分冷凝，冷凝液回流回塔中，不凝气主要为氮气，直接放空。冷凝器所需冷量由来自再沸器的液氮被汽化而获得。The boil-up in the reboiler is generated by condensing HP GAN from the high-pressure column. The boil-up vapor rises to the top of the column through the stages. As it rises, it is enriched in nitrogen. The vapor from the top of the column flows to the Pure Argon Column Overhead Condenser where it is partially condensed. The liquid portion is returned to the column as reflux. The vapor portion, a nitrogen-rich waste stream, is vented to atmosphere. The refrigeration for the condenser is provided by vaporizing condensed nitrogen from the reboiler. 1.2 主要设备的选定说明Description of major equipment selection鉴于美国AP公司为世界上四大空分生产厂之一，具有数十年的丰富生产经验，所用主要设备由AP公司根据原有厂使用设备为选取依据并设计，故选定的设备技术先进，可靠性强。Based on Air Products and Chemical, Inc of American is one of the four largest plants of air separation production in the world and with several years of expericence for air separation production. Major equipment in the plant is selected based on th quipment ever used in similar original plant in Air Products and Chemical, Inc of American, so selected equipment is reliable and with advanced technology.装置机械，设备包括主空气压缩机，膨胀机，直接接触后冷器，冷水塔，纯化器，空气压缩冷却器，冷箱，低压液氧罐，液氩罐，液氩泵，液氧泵以及装卸液化气体装置等等。由于装置采用业主Air Products 先进可靠的气体分离专利技术，因此装置机械，设备主要由业主进行成套采购提供，设备基本上采用引进设备，国内只分交配套部分辅助静止设备，现场制作大型储罐以及水系统部分水泵。Main mechanism and equipment as follows: Mair Air Compressor, Booster Air Compressor, Expander, Direct Contact Aftercooler, Water Chiller Tower, TSA Adsorber Vessels, BAC Aftercooler, Main Heat Exchanger Box, HP/LP Column Box, Pure Argon Box, Crossover, LP PAR Storage Tank, LP LOX Storage Tank, LOX Product Pumps, Argon Column Crude LOX Return Pump, LOX Tank Fill Pump, Argon Tank Fill Pump. Because of adopting latest and reliable air separation patent technology of Air Products and Chemicals, Inc., main mechanism and equipment will be stocked as whole set by owner from overseas import, only part of assistant vessels, local fabrication large tank and pumps of utility unit will be submitted in civil.业主提供主要关键设备有：主空压机组，空气增压机组，膨胀机，冷箱，转换器及主要的离心泵。Mechanism and equipment of owner offering are Mair Air Compressor, Booster Air Compressor, Expander, Main Heat Exchanger Box, HP/LP Colum Box, Pure Argon Box, Crossover and cryogenic pumps.1.3 设备一览表 Equipment list参见文件DOC0000383365。Refer to the document DOC0000383365.1.4 设备规格书 Equipment specification提交的数据表，设备条件图，参考设备平面图等有关设备规格选型的文件仅适用于初步设计，不能用于设备采购和详细设计。项目执行阶段根据工艺参数的不同也会对相应文件做出修改。All equipment specification related documents, such as data sheets, setting plans, referred general arrangement drawings etc, are only subject to input for preliminary design, not suitable for equipment purchasing and detailed design. Those documents might be updated per process data in the project execution stage. 详细文件参见交付文件目录DOC0000384578。Detailed specifications refer to External Process Package Deliverable List DOC0000384578.2.0 仪表选型和自动化水平Instrument selection and process control 2.1 概述 General本项目工艺过程复杂，需要有较高的自动化水平，才能保证生产正常和运行安全。所以，在本项目中采用分散型控制系统（PCS7）作为装置的控制系统。装置设置一个中央控制室（CCR），操作人员可在中控室内对生产进行监视和控制，实现全厂集中控制。Since the process design is complex, a high level of automation is required. The implementation of a distributed control system (PCS7) ensures safe and efficient operation. Operators can control the plant from a central control room, which allows the operators to take control action on the plant from an indoor environment. 2.2 装置控制系统 Plant control system本装置控制系统采用西门子（Siemens）PCS7系统，它由操作站（HMI）和控制站（CPU）组成。操作人员在操作站上对整个空分装置进行监视和操作。控制站完成过程信号的采集、连锁和自动调节的功能。本装置还配置了独立的安全连锁系统，它用来满足空分装置对紧急、安全停车系统的要求。The plant control system will be a Siemens PCS7. It consist of an operator station (HMI) and an control station (CPU). Operator will monitor and control whole plant in operator station. Operator station has the function for signal collecting and interlocking and automatic adjusting. A separate hard wired trip panel will handle all of the safety & emergency shutdown requirements for the ASU.2.3 控制逻辑图仪表系统 Control Logic Diagram控制逻辑包含两部分内容，一是安全连锁系统逻辑图，参见文件DOC0000385182；二是DCS连锁逻辑图，参见文件DOC0000385391。Control Logic Diagram for this ASU plant consists of two parts: one is Critical Safety System Logic, referring to DOC0000385182; another is DCS Logic Diagram, referring to DOC 0000385391.2.4 仪表系统 Instrument system仪表设计和安装遵循相关的国家标准和规范。The Instrumentation design and installation should comply with the requirements of all relevant National Codes and Standards.仪表设计和选择以保证安全为准则。当仪表气源或电源中断时，仪表系统还能保证空分装置处于安全状态。Instrumentation shall be designed and selected for a failsafe condition i.e. loss of instrument air and power shall not impair the safety of the process.详细请参阅仪表设计说明DOC0000383330。Details refer to document “Instrument Design Specification” DOC0000383330.