低温空分制氧制氮设备

Oxygen, Nitrogen and Argon will be produced by air separation using cryogenic distillation process.
Air Compression, Cooling ＆ Purification
The atmospheric air will be compressed in a multistage centrifugal turbo air compressor （ATC） equipped with suction air filter and inter/ after coolers. The heat of compression will be rejected in the intercoolers, after coolers and further cooling upto desired temperature will be done in air water tower through waste nitrogen gas ＆ chilled water. A demister will be used to free water from the air stream. Moisture separator shall be provided.
The pre－cooled air will be passed through twin bed adsorber towers containing activated alumina and molecular sieve to remove moisture, carbon dioxide, as well as hydrocarbon impurities from air steam. After passing through the bed, the air passes through a dust filter that removes any molecular sieve fines that may be present. A small stream of air will be withdrawn downstream of the dust filter to meet the instrumentation air requirement of ASU.
One of the two vessels will be in operation while the other will be reactivated by waste Nitrogen coming form the cold box. The regeneration gas （waste Nitrogen） will be heated in electrical heater in the heating cycle of regeneration.
At the outlet of the air purification unit, the main stream of purified air will be divided into two streams. While the first stream of purified air （Medium pressure air at 5－6 kg/cm2 g） will enter the main exchanger in the cold box, the other stream of purified air will be further compressed to high pressure in a multistage centrifugal booster air compressor （BAC） and then it will enter the cold box. Both the medium MP （medium pressure）and HP air will be cooled down by heat exchange with the counter current liquid Oxygen to produce product gaseous Oxygen, product gaseous Nitrogen and waste gaseous Nitrogen steam in the main exchanger （inside the cold box）.
Air Distillation
The air distillation takes place in the Air Separation Unit cold box consisting of main heat exchanger, nitrogen heaters, bottom column, top column, main condenser, argon condenser, argon columns, expansion turbine, cryogenic pumps etc.
The MP air （at 5－6 kg/cm2 g） which will be nearly to dew point, enters the bottom column which perform the first separation.
Part of the HP air will be used to produce required refrigeration by taking it out of the main exchanger at an appropriate point and expanding it in an expansion turbine. This expanded air will be fed to the MP column （at the bottom of the bottom distillation column）. The other part of the HP air will be further compressed in the booster connected to the turbine to elevate the pressure level to vaporize liquid Oxygen in the main exchanger and then expanded through an expansion valve before it enters the MP column （i.e. at the bottom of the bottom distillation column）. Oxygen and Nitrogen will be separated from the air by Cryogenic distillation from the cold box.
In order to produce Argon, the Argon rich stream of liquid from intermediate level of the top column will be fed into the pure Argon column where it is stripped of its Nitrogen content. Pure liquid Argon product from the bottom of the column will be sent to the storage tank.
All distillation columns shall be with structured packing for high degree of efficiency with minimum energy consumption.
Layout of the Plant shall be such that control room and cold box are located near compressor building and easily approachable.

流程简述PROCESS DESCRIPTION
 利用低温精馏工艺分离空气可制取氧气、氮气和氩气。
空气压缩、冷却和净化
   原料空气经（空压机配置有吸入空气过滤器和中间/后冷却器）多级离心式透平压缩机压缩，压缩产生的热量被中间冷却器和后冷却器带走，而后在空气冷却塔中被污氮和冷冻水进一步冷却到所需的温度。采用除雾器来除去空气中的水分，此外还设置了水分离器。
预冷后的空气通过双层床吸附器，由吸附器内充填的活性铝和分子筛来清除空气中的水分、二氧化碳和碳氢化合物。空气穿过出床层后，进入滤尘器中去除空气中可能含有的分子筛粉末。在滤尘器之后抽出一小股空气，作为空分设备的仪表空气。
两台吸附器一台使用，另一台由来自冷箱的污氮进行再生。再生气体（污氮）在再生加热循环中由电加热器加热。
    空气离开净化系统治后，干净的空气被分成两股。一股（5－6 kg/cm2 g的中压空气）进入冷箱内的主换热器，另一股经多级离心空气增压机压缩至高压后送入冷箱。中压空气和高压空气经冷箱内的主换热器与返流液氧换热而被冷却，制取产品氧气，产品氮气和污氮。
空气精馏
    空气精馏在空分设备冷箱中进行。冷箱中设有主换热器，氮加热器，下塔，上塔，主冷凝器，氩冷凝器，氩塔，透平膨胀机，低温泵等。
    接近露点的中压空气（5－6 kg/cm2 g）进入下塔进行初次分离。
    一部分高压空气从主换热器的某一位置抽出，送入透平膨胀机中膨胀以获得所需的冷量。膨胀后的空气送入中压塔（下塔的底部）。另一部分高压空气在与膨胀机联轴的增压机中进一步压缩，提高了压力，在主换热器中使液氧蒸发，经膨胀阀膨胀后送入中压塔（下塔的底部）。经冷箱内的低温精馏，氧和氮从空气中分离出来。为了制取氩气，将上塔中部的氩馏分送入精氩塔中，去除其中的氮成分。把塔底部得到的纯液氩送入储罐。
    所有的精馏塔都使用规整填料，以提高效率，减少能耗。
    设备总体布置时，控制室和冷箱要靠近压缩机房，且通行方便。

    所有的精馏塔都使用规整填料，以提高效率，减少能耗。
    设备总体布置时，控制室和冷箱要靠近压缩机房，且通行方便