CN114777415B - 一种低能耗双塔双过冷正流膨胀制氮工艺 - Google Patents

一种低能耗双塔双过冷正流膨胀制氮工艺 Download PDF

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CN114777415B
CN114777415B CN202210432228.2A CN202210432228A CN114777415B CN 114777415 B CN114777415 B CN 114777415B CN 202210432228 A CN202210432228 A CN 202210432228A CN 114777415 B CN114777415 B CN 114777415B
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杨正军
何森林
韦霆
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Hangzhou Turning Energy Technology Development Co ltd
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Abstract

本发明公开了一种低能耗双塔双过冷正流膨胀制氮工艺，所述工艺所需装置包括过滤器、空气压缩机、空气预冷系统、交替使用的分子筛吸附器、电加热器、主换热器、精馏塔I、主冷凝蒸发器I、过冷器I、精馏塔II、主冷凝蒸发器II、液氮泵、过冷器II、膨胀机。本发明制备的氮气纯度高(≤3ppmO2)，压力为0.5‑1.0MpaG，提取率高，装置能耗低。

Description

一种低能耗双塔双过冷正流膨胀制氮工艺
技术领域
本发明涉及空分技术领域，具体涉及一种低能耗双塔双过冷正流膨胀制氮工艺。
背景技术
随着我国经济的快速发展以及汽车保有量的不断攀升，环境污染问题日益凸显，人们对新型清洁能源的需求也越来越迫切。实现此目标的关键任务是以清洁能源发电和储能，逐步替代传统化石能源；以动力电池助力电动车发展，替代移动式化石能源。为达成目标，我国政府出台多项惠利政策，大力支持新能源行业的发展，上下游行业配套不断完善。中国动力锂电池企业在全球市场中的竞争力不断增强，市场份额快速增长。新能源汽车及锂离子电池需要品质稳定的高端电池级磷酸铁、磷酸铁锂、三元材料等，高端电池级磷酸铁、磷酸铁锂、三元材料等在加工生产过程中需要大量高纯度氮气作为保护气。随着产品升级，规模的大幅增加，低能耗高纯度氮气制取设备及工艺将会极大地节约耗能，降低生产成本，进一步提升企业产品的行业竞争优势。为此本发明提出了一种低能耗双塔双过冷正流膨胀制氮工艺。
发明内容
本发明的目的是提供一种低能耗双塔双过冷正流膨胀制氮工艺，以解决现有技术的不足。
本发明采用以下技术方案：
一种低能耗双塔双过冷正流膨胀制氮工艺，所述工艺所需装置包括过滤器、空气压缩机、空气预冷系统、交替使用的分子筛吸附器、电加热器、主换热器、精馏塔I、主冷凝蒸发器I、过冷器I、精馏塔II、主冷凝蒸发器II、液氮泵、过冷器II、膨胀机；
过滤器、空气压缩机、空气预冷系统、交替使用的分子筛吸附器、电加热器、膨胀机增压端、膨胀机增压后水冷却器设于冷箱外，主换热器、精馏塔I、主冷凝蒸发器I、过冷器I、精馏塔II、主冷凝蒸发器II、液氮泵、过冷器II、膨胀机设于冷箱内，主冷凝蒸发器I设于精馏塔I之上，主冷凝蒸发器II设于精馏塔II 之上；
过滤器、空气压缩机、空气预冷系统、交替使用的分子筛吸附器依次连接，交替使用的分子筛吸附器分别和主换热器、膨胀机增压端连接，主换热器的完全冷却出口和精馏塔I底部的空气进口连接；膨胀机增压端和膨胀机增压后水冷却器连接，膨胀机增压后水冷却器和主换热器连接，主换热器的部分冷却出口和膨胀机连接，膨胀机和精馏塔II连接；
精馏塔I底部的液空出口和过冷器I连接，过冷器I和主冷凝蒸发器I连接，过冷器I和主冷凝蒸发器I的连接管路上设有节流阀，主冷凝蒸发器I富氧空气出口和精馏塔II连接；主冷凝蒸发器I液空出口和主冷凝蒸发器II连接，主冷凝蒸发器I液空出口和主冷凝蒸发器II的连接管路上设有节流阀；
精馏塔I下部的污液氮出口和过冷器I连接，过冷器I和精馏塔II连接，过冷器I和精馏塔II的连接管路上设有节流阀；
精馏塔I顶部的压力氮气出口分别和主换热器、主冷凝蒸发器I连接，主换热器连至外部高纯度压力氮气供用户管网；主冷凝蒸发器I的液氮出口和精馏塔 I顶部连接；
精馏塔II底部的富氧液空出口和过冷器II连接，过冷器II和主冷凝蒸发器 II连接，过冷器II和主冷凝蒸发器II的连接管路上设有节流阀；主冷凝蒸发器 II的污氮气出口和过冷器II连接，过冷器II和过冷器I连接，过冷器I和主换热器连接，主换热器分别和外部放空管道、电加热器连接，电加热器和交替使用的分子筛吸附器连接；
精馏塔II顶部的氮气出口和主冷凝蒸发器II连接，主冷凝蒸发器II的液氮出口分别和精馏塔II顶部、液氮泵连接，液氮泵分别和外部液氮产品储罐、过冷器II连接，过冷器II和精馏塔I顶部连接；
所述工艺包括如下步骤：
步骤一、将原料空气经过滤器过滤掉灰尘和机械杂质后，进入空气压缩机将空气压缩到设定压力；之后经空气预冷系统预冷后进入交替使用的分子筛吸附器中纯化；
步骤二、纯化后的空气一小部分用于仪表空气，其余部分分成两股，一股空气进入主换热器冷却至饱和温度并带有一定的含湿后进入精馏塔I底部参与精馏；另一股空气经膨胀机增压端增压并经膨胀机增压后水冷却器冷却后引入主换热器部分冷却，后引入膨胀机膨胀制取装置所需冷量，膨胀后空气引入精馏塔II 中参与精馏；
步骤三、空气经精馏塔I精馏后分离为液空、污液氮和压力氮气，液空经过冷器I过冷、节流阀节流后进入主冷凝蒸发器I和压力氮气换热，液空被汽化为富氧空气，富氧空气引入精馏塔II底部参与精馏，引出部分液空经节流阀节流后引入主冷凝蒸发器II；污液氮经过冷器I过冷、节流阀节流后进入精馏塔II 参与精馏；部分压力氮气引入主冷凝蒸发器I和液空换热，压力氮气被冷凝为液氮，液氮引入精馏塔I顶部作为回流液；其余压力氮气经主换热器复热后出冷箱作为高纯度压力氮气产品；
步骤四、富氧空气、污液氮、膨胀后空气经精馏塔II精馏后分离为富氧液空和氮气，富氧液空经过冷器II过冷、节流阀节流后进入主冷凝蒸发器II和氮气换热，富氧液空被汽化为污氮气，污氮气依次经过冷器II、过冷器I和主换热器复热后出冷箱，部分作为再生气由电加热器加热后引入交替使用的分子筛吸附器，其余放空；氮气引入主冷凝蒸发器II和富氧液空换热，氮气被冷凝为液氮，部分液氮引入精馏塔II顶部作为回流液，其余液氮经液氮泵增压后部分出冷箱作为液氮产品，其余经过冷器II复热后引入精馏塔I顶部作为回流液。
进一步地，空气压缩机为透平空气压缩机。
进一步地，膨胀机为增压透平膨胀机。
进一步地，步骤一空气经空气压缩机压缩到0.6-1.0MPaG。
进一步地，步骤一空气经空气预冷系统预冷至5-15℃。
进一步地，步骤三高纯度压力氮气产品纯度为≤3ppmO2，压力为 0.5-1.0MpaG。
本发明的有益效果：
1、本发明采用双塔精馏，增加精馏塔II用于分离来自精馏塔I分离出的富氧空气、污液氮及膨胀后空气中的氮，分离出的氮气经主冷凝蒸发器II冷凝为液氮，部分液氮作为精馏塔II的回流液，部分液氮经液氮泵增压、过冷器II复热后引入精馏塔I作为回流液，从而分离出更多的氮产品。本发明制备的氮气纯度高(≤3ppmO2)，压力为0.5-1.0MpaG。
2、本发明设置了双过冷器，增加过冷器II，用于过冷精馏塔II底部的富氧液空，以回收返流污氮气及增压后过冷液氮的部分冷量转移至精馏塔II，减少富氧液空节流后汽化率，增大精馏塔II回流液氮量，提高精馏塔II氮组分的提取率，降低装置能耗。
3、本发明采用双主冷凝蒸发器，设置主冷凝蒸发器II，因主冷凝蒸发器I 中液空中含氧量较精馏塔II富氧液空含氧量低，在精馏塔II精馏压力不变及满足主冷凝蒸发器I换热的情况下，可以降低精馏塔I的压力，从而降低进入精馏塔I的空气压力，进而降低装置能耗。
4、本发明从精馏塔I中引一股污液氮经过冷器I过冷、节流阀节流后引入精馏塔II参与精馏，将冷量从精馏塔I转移至精馏塔II，降低了精馏塔I的负荷，同时改善了精馏塔II的回流量，提高了精馏塔II氮组分的提取率，使负荷分配更合理，也提高了装置整体氮的提取率，降低装置能耗。
5、本发明主冷凝蒸发器II中氮气冷凝后的部分液氮经液氮泵增压后再经过冷器II复热后引入精馏塔I作为回流液，一方面利用液氮泵增压提高进入精馏塔 I液氮的压力，降低了装置的能耗，另一方面利用过冷器II回收该液氮部分冷量，将冷量转移至精馏塔II，减少富氧液空节流后汽化率，增大精馏塔II回流液氮量，提高精馏塔II氮组分的提取率，从而进一步降低装置能耗。
6、本发明将膨胀后空气引入精馏塔II参与精馏，提高了装置整体氮组分利用率，降低装置能耗。
附图说明
图1为本发明工艺所需装置结构示意图。
具体实施方式
下面结合实施例和附图对本发明做更进一步地解释。下列实施例仅用于说明本发明，但并不用来限定本发明的实施范围。
一种低能耗双塔双过冷正流膨胀制氮工艺，所述工艺所需装置如图1所示，包括过滤器1、空气压缩机2、空气预冷系统3、交替使用的分子筛吸附器4、电加热器5、主换热器6、精馏塔I7、主冷凝蒸发器I8、过冷器I11、精馏塔II9、主冷凝蒸发器II10、液氮泵13、过冷器II12、膨胀机14；优选地，所述空气压缩机2为透平空气压缩机，所述膨胀机14为增压透平膨胀机；空气预冷系统3 为空气预冷机组或空冷塔/水冷塔；
过滤器1、空气压缩机2、空气预冷系统3、交替使用的分子筛吸附器4、电加热器5、膨胀机增压端141、膨胀机增压后水冷却器142设于冷箱外，主换热器6、精馏塔I7、主冷凝蒸发器I8、过冷器I11、精馏塔II9、主冷凝蒸发器II10、液氮泵13、过冷器II12、膨胀机14设于冷箱内，主冷凝蒸发器I8设于精馏塔I7 之上，主冷凝蒸发器II10设于精馏塔II9之上；
过滤器1、空气压缩机2、空气预冷系统3、交替使用的分子筛吸附器4依次连接，交替使用的分子筛吸附器4分别和主换热器6、膨胀机增压端141连接，主换热器6的完全冷却出口和精馏塔I7底部的空气进口连接；膨胀机增压端141 和膨胀机增压后水冷却器142连接，膨胀机增压后水冷却器142和主换热器6 连接，主换热器6的部分冷却出口和膨胀机14连接，膨胀机14和精馏塔II9连接；
精馏塔I7底部的液空出口和过冷器I11连接，过冷器I11和主冷凝蒸发器I8 连接，过冷器I11和主冷凝蒸发器I8的连接管路上设有节流阀，主冷凝蒸发器 I8富氧空气出口和精馏塔II9连接；主冷凝蒸发器I8液空出口和主冷凝蒸发器 II10连接，主冷凝蒸发器I8液空出口和主冷凝蒸发器II10的连接管路上设有节流阀；
精馏塔I7下部的污液氮出口和过冷器I11连接，过冷器I11和精馏塔II9连接，过冷器I11和精馏塔II9的连接管路上设有节流阀；
精馏塔I7顶部的压力氮气出口分别和主换热器6、主冷凝蒸发器I8连接，主换热器6连至外部高纯度压力氮气供用户管网；主冷凝蒸发器I8的液氮出口和精馏塔I7顶部连接；
精馏塔II9底部的富氧液空出口和过冷器II12连接，过冷器II12和主冷凝蒸发器II10连接，过冷器II12和主冷凝蒸发器II10的连接管路上设有节流阀；主冷凝蒸发器II10的污氮气出口和过冷器II12连接，过冷器II12和过冷器I11连接，过冷器I11和主换热器6连接，主换热器6分别和外部放空管道、电加热器 5连接，电加热器5和交替使用的分子筛吸附器4连接；
精馏塔II9顶部的氮气出口和主冷凝蒸发器II10连接，主冷凝蒸发器II10 的液氮出口分别和精馏塔II9顶部、液氮泵13连接，液氮泵13分别和外部液氮产品储罐、过冷器II12连接，过冷器II12和精馏塔I7顶部连接。
上述各部件的功能如下：
过滤器1，用于过滤原料空气中的灰尘和机械杂质；
空气压缩机2，用于将过滤后的空气压缩到设定压力；
空气预冷系统3，用于将过滤、压缩后的空气预冷；
交替使用的分子筛吸附器4，用于将过滤、压缩、预冷后的空气纯化，去除水分、CO2、C2H2等物质；
电加热器5，用于加热污氮气以再生交替使用的分子筛吸附器4；
主换热器6，用于将纯化后的部分空气冷却，将经膨胀机增压端141增压并经膨胀机增压后水冷却器142冷却后的空气部分冷却，将压力氮气、污氮气复热；
精馏塔I7，用于将空气精馏而分离为压力氮气和液空；
主冷凝蒸发器I8，用于液空和压力氮气换热，液空被汽化为富氧空气，压力氮气被液化为液氮；
过冷器I11，用于将液空、污液氮过冷，用于将污氮气复热；
精馏塔II9，用于将富氧空气、污液氮、膨胀后空气精馏而分离为富氧液空和氮气；
主冷凝蒸发器II10，用于富氧液空和氮气换热，富氧液空被汽化为污氮气，氮气被冷凝为液氮；
液氮泵13，用于将主冷凝蒸发器II10的部分液氮增压；
过冷器II12，用于将富氧液空过冷，将经液氮泵13增压后的部分液氮、污氮气复热；
膨胀机14，用于将部分冷却后的空气膨胀，制取装置所需冷量。
所述工艺包括如下步骤：
步骤一、将原料空气经过滤器1过滤掉灰尘和机械杂质后，进入空气压缩机 2将空气压缩到0.6-1.0MPaG；之后经空气预冷系统3预冷至5-15℃后进入交替使用的分子筛吸附器4中纯化，去除水分、CO2、C2H2等物质；
步骤二、纯化后的空气一小部分用于仪表空气(图1中未示意出)，其余部分分成两股，一股空气进入主换热器6冷却至饱和温度并带有一定的含湿后进入精馏塔I7底部参与精馏；另一股空气经膨胀机增压端141增压并经膨胀机增压后水冷却器142冷却后引入主换热器6部分冷却，后引入膨胀机14膨胀制取装置所需冷量，膨胀后空气引入精馏塔II9中参与精馏；
步骤三、空气经精馏塔I7精馏后分离为液空、污液氮(其中，氧组分 33％-40％O2)和压力氮气，液空经过冷器I11过冷、节流阀节流后进入主冷凝蒸发器I8和压力氮气换热，液空被汽化为富氧空气，富氧空气引入精馏塔II9底部参与精馏，引出部分液空经节流阀节流后引入主冷凝蒸发器II10；污液氮经过冷器I11过冷、节流阀节流后进入精馏塔II9参与精馏；部分压力氮气引入主冷凝蒸发器I8和液空换热，压力氮气被冷凝为液氮，液氮引入精馏塔I7顶部作为回流液；其余压力氮气经主换热器6复热后出冷箱作为高纯度压力氮气产品，高纯度压力氮气产品纯度为≤3ppmO2，压力为0.5-1.0MpaG；
步骤四、富氧空气、污液氮、膨胀后空气经精馏塔II9精馏后分离为富氧液空和氮气(≤3ppmO2)，富氧液空经过冷器II12过冷、节流阀节流后进入主冷凝蒸发器II10和氮气换热，富氧液空被汽化为污氮气，污氮气依次经过冷器II12、过冷器I11和主换热器6复热后出冷箱，部分作为再生气由电加热器5加热后引入交替使用的分子筛吸附器4，其余放空；氮气引入主冷凝蒸发器II10和富氧液空换热，氮气被冷凝为液氮，部分液氮引入精馏塔II9顶部作为回流液，其余液氮经液氮泵13增压后部分出冷箱作为液氮产品，其余经过冷器II12复热后引入精馏塔I7顶部作为回流液。

Claims (6)

1.一种低能耗双塔双过冷正流膨胀制氮工艺，其特征在于，所述工艺所需装置包括过滤器、空气压缩机、空气预冷系统、交替使用的分子筛吸附器、电加热器、主换热器、精馏塔I、主冷凝蒸发器I、过冷器I、精馏塔II、主冷凝蒸发器II、液氮泵、过冷器II、膨胀机；
过滤器、空气压缩机、空气预冷系统、交替使用的分子筛吸附器、电加热器、膨胀机增压端、膨胀机增压后水冷却器设于冷箱外，主换热器、精馏塔I、主冷凝蒸发器I、过冷器I、精馏塔II、主冷凝蒸发器II、液氮泵、过冷器II、膨胀机设于冷箱内，主冷凝蒸发器I设于精馏塔I之上，主冷凝蒸发器II设于精馏塔II之上；
过滤器、空气压缩机、空气预冷系统、交替使用的分子筛吸附器依次连接，交替使用的分子筛吸附器分别和主换热器、膨胀机增压端连接，主换热器的完全冷却出口和精馏塔I底部的空气进口连接；膨胀机增压端和膨胀机增压后水冷却器连接，膨胀机增压后水冷却器和主换热器连接，主换热器的部分冷却出口和膨胀机连接，膨胀机和精馏塔II连接；
精馏塔I底部的液空出口和过冷器I连接，过冷器I和主冷凝蒸发器I连接，过冷器I和主冷凝蒸发器I的连接管路上设有节流阀，主冷凝蒸发器I富氧空气出口和精馏塔II连接；主冷凝蒸发器I液空出口和主冷凝蒸发器II连接，主冷凝蒸发器I液空出口和主冷凝蒸发器II的连接管路上设有节流阀；
精馏塔I下部的污液氮出口和过冷器I连接，过冷器I和精馏塔II连接，过冷器I和精馏塔II的连接管路上设有节流阀；
精馏塔I顶部的压力氮气出口分别和主换热器、主冷凝蒸发器I连接，主换热器连至外部高纯度压力氮气供用户管网；主冷凝蒸发器I的液氮出口和精馏塔I顶部连接；
精馏塔II底部的富氧液空出口和过冷器II连接，过冷器II和主冷凝蒸发器II连接，过冷器II和主冷凝蒸发器II的连接管路上设有节流阀；主冷凝蒸发器II的污氮气出口和过冷器II连接，过冷器II和过冷器I连接，过冷器I和主换热器连接，主换热器分别和外部放空管道、电加热器连接，电加热器和交替使用的分子筛吸附器连接；
精馏塔II顶部的氮气出口和主冷凝蒸发器II连接，主冷凝蒸发器II的液氮出口分别和精馏塔II顶部、液氮泵连接，液氮泵分别和外部液氮产品储罐、过冷器II连接，过冷器II和精馏塔I顶部连接；
所述工艺包括如下步骤：
步骤一、将原料空气经过滤器过滤掉灰尘和机械杂质后，进入空气压缩机将空气压缩到设定压力；之后经空气预冷系统预冷后进入交替使用的分子筛吸附器中纯化；
步骤二、纯化后的空气一小部分用于仪表空气，其余部分分成两股，一股空气进入主换热器冷却至饱和温度并带有一定的含湿后进入精馏塔I底部参与精馏；另一股空气经膨胀机增压端增压并经膨胀机增压后水冷却器冷却后引入主换热器部分冷却，后引入膨胀机膨胀制取装置所需冷量，膨胀后空气引入精馏塔II中参与精馏；
步骤三、空气经精馏塔I精馏后分离为液空、污液氮和压力氮气，液空经过冷器I过冷、节流阀节流后进入主冷凝蒸发器I和压力氮气换热，液空被汽化为富氧空气，富氧空气引入精馏塔II底部参与精馏，引出部分液空经节流阀节流后引入主冷凝蒸发器II；污液氮经过冷器I过冷、节流阀节流后进入精馏塔II参与精馏；部分压力氮气引入主冷凝蒸发器I和液空换热，压力氮气被冷凝为液氮，液氮引入精馏塔I顶部作为回流液；其余压力氮气经主换热器复热后出冷箱作为高纯度压力氮气产品；
步骤四、富氧空气、污液氮、膨胀后空气经精馏塔II精馏后分离为富氧液空和氮气，富氧液空经过冷器II过冷、节流阀节流后进入主冷凝蒸发器II和氮气换热，富氧液空被汽化为污氮气，污氮气依次经过冷器II、过冷器I和主换热器复热后出冷箱，部分作为再生气由电加热器加热后引入交替使用的分子筛吸附器，其余放空；氮气引入主冷凝蒸发器II和富氧液空换热，氮气被冷凝为液氮，部分液氮引入精馏塔II顶部作为回流液，其余液氮经液氮泵增压后部分出冷箱作为液氮产品，其余经过冷器II复热后引入精馏塔I顶部作为回流液。
2.根据权利要求1所述的低能耗双塔双过冷正流膨胀制氮工艺，其特征在于，空气压缩机为透平空气压缩机。
3.根据权利要求1所述的低能耗双塔双过冷正流膨胀制氮工艺，其特征在于，膨胀机为增压透平膨胀机。
4.根据权利要求1所述的低能耗双塔双过冷正流膨胀制氮工艺，其特征在于，步骤一空气经空气压缩机压缩到0.6-1.0MPaG。
5.根据权利要求1所述的低能耗双塔双过冷正流膨胀制氮工艺，其特征在于，步骤一空气经空气预冷系统预冷至5-15℃。
6.根据权利要求1所述的低能耗双塔双过冷正流膨胀制氮工艺，其特征在于，步骤三高纯度压力氮气产品纯度为≤3ppmO2，压力为0.5-1.0MpaG。
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