JPH03244990A - Control of nitrogen concentration in material argon - Google Patents
Control of nitrogen concentration in material argonInfo
- Publication number
- JPH03244990A JPH03244990A JP4217190A JP4217190A JPH03244990A JP H03244990 A JPH03244990 A JP H03244990A JP 4217190 A JP4217190 A JP 4217190A JP 4217190 A JP4217190 A JP 4217190A JP H03244990 A JPH03244990 A JP H03244990A
- Authority
- JP
- Japan
- Prior art keywords
- nitrogen concentration
- argon
- amount
- oxygen
- value
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 title claims abstract description 203
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 title claims abstract description 170
- 229910052757 nitrogen Inorganic materials 0.000 title claims abstract description 101
- 229910052786 argon Inorganic materials 0.000 title claims abstract description 85
- 239000000463 material Substances 0.000 title abstract 10
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 64
- 239000001301 oxygen Substances 0.000 claims abstract description 64
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 64
- 238000000034 method Methods 0.000 claims abstract description 25
- 239000002994 raw material Substances 0.000 claims description 49
- 238000004817 gas chromatography Methods 0.000 description 16
- 239000007789 gas Substances 0.000 description 5
- 238000000605 extraction Methods 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 3
- 238000009835 boiling Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000004821 distillation Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000001052 transient effect Effects 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000013256 coordination polymer Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000004540 process dynamic Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
- F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
- F25J3/04763—Start-up or control of the process; Details of the apparatus used
- F25J3/04769—Operation, control and regulation of the process; Instrumentation within the process
- F25J3/04793—Rectification, e.g. columns; Reboiler-condenser
- F25J3/048—Argon recovery
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
- F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
- F25J3/04406—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using a dual pressure main column system
- F25J3/04412—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using a dual pressure main column system in a classical double column flowsheet, i.e. with thermal coupling by a main reboiler-condenser in the bottom of low pressure respectively top of high pressure column
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
- F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
- F25J3/04642—Recovering noble gases from air
- F25J3/04648—Recovering noble gases from air argon
- F25J3/04654—Producing crude argon in a crude argon column
- F25J3/04666—Producing crude argon in a crude argon column as a parallel working rectification column of the low pressure column in a dual pressure main column system
- F25J3/04672—Producing crude argon in a crude argon column as a parallel working rectification column of the low pressure column in a dual pressure main column system having a top condenser
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Separation By Low-Temperature Treatments (AREA)
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は、空気を原料として酸素、窒素を蒸留精製する
酸素精留塔上塔の中程から、アルゴンを生成する別の精
留塔、すなわち粗アルゴン塔への原料として含アルゴン
ガス（以下「原料アルゴン」という、）を抜き出す際の
原料アルゴン中の窒素濃度の制御方法に関する。Detailed Description of the Invention (Industrial Application Field) The present invention is directed to a separate rectification column that produces argon from the middle of an upper column of an oxygen rectification column that distills and purifies oxygen and nitrogen using air as a raw material. That is, the present invention relates to a method of controlling the nitrogen concentration in raw argon when extracting argon-containing gas (hereinafter referred to as "raw material argon") as a raw material to a crude argon column.
（従来の技術）
従来より既に良く知られているように、空気分離法によ
るアルゴンガスの製造には、いわゆる高圧式と低圧式と
があるが、いずれの場合にあっても、酸素精留塔の中程
から抜き出す原料アルゴンをさらに精製することにより
製造している。(Prior art) As is already well known, there are two types of argon gas production using the air separation method: the so-called high-pressure method and the low-pressure method. It is manufactured by further refining the raw material argon extracted from the middle of the process.
第１図は、空気分離プロセスの一例の概要を示す略式説
明図である。第１図において、酸素精留塔１は、上塔１
ａと下塔１ｂとからなる。上塔１ａと下塔１ｂとは、凝
縮器１ｃで結合され、両者の間で熱交換が行われる。原
料空気は図示の経路で酸素精留塔１の下塔１ｂおよび上
塔１ａに供給される。原料空気の一部は冷却器２で冷却
後に供給され、残りは昇圧後、熱交換器３ａ、３ｂで冷
却されて後に供給される。FIG. 1 is a schematic explanatory diagram showing an overview of an example of an air separation process. In FIG. 1, an oxygen rectification column 1 is an upper column 1
a and a lower tower 1b. The upper column 1a and the lower column 1b are connected by a condenser 1c, and heat exchange is performed between them. Feed air is supplied to the lower column 1b and upper column 1a of the oxygen rectification column 1 through the illustrated route. A part of the raw air is supplied after being cooled by the cooler 2, and the rest is supplied after being pressurized and cooled by the heat exchangers 3a and 3b.
酸素精留塔上塔ｌａ内では沸点の低い窒素が塔頂に、沸
点の高い酸素が塔底に濃縮される。沸点が窒素より高く
酸素より低いアルゴンは塔の中程に集まる。したがって
、窒素・酸素はそれぞれ上塔１ａの塔頂部、塔底部から
抜き出される。また、アルゴンは原料アルゴンとして塔
の中程から粗アルゴン塔４に抜き出される。In the upper column la of the oxygen rectification column, nitrogen with a low boiling point is concentrated at the top of the column, and oxygen with a high boiling point is concentrated at the bottom of the column. Argon, whose boiling point is higher than nitrogen and lower than oxygen, collects in the middle of the column. Therefore, nitrogen and oxygen are extracted from the top and bottom of the upper column 1a, respectively. Further, argon is extracted from the middle of the column to the crude argon column 4 as raw argon.
ところで、この原料アルゴン中に窒素が多量に、例えば
１１０００ｐｐ以上存在すると、粗アルゴン塔４の上部
の窒素濃度が上昇し、塔頂から取り出されるアルゴン中
に規格値以上に窒素が混入してしまう。また、これを防
くべく粗アルゴン塔４からの抜出量を減少させると粗ア
ルゴン塔内に窒素ガスが溜まり、圧力が増加して粗アル
ゴン塔の運転が不可能となる。さらに、これを防くべく
塔頂からガスを抜き出すとその排出ガス中に７０％もの
アルゴンが存在し、アルゴン収率の低下となってしまう
。By the way, if a large amount of nitrogen exists in this raw material argon, for example, 11,000 pp or more, the nitrogen concentration at the upper part of the crude argon column 4 will increase, and the argon taken out from the top of the column will contain more than the standard value of nitrogen. Moreover, if the amount of extraction from the crude argon column 4 is reduced in order to prevent this, nitrogen gas will accumulate in the crude argon column, the pressure will increase, and the operation of the crude argon column will become impossible. Furthermore, if the gas is extracted from the top of the tower to prevent this, as much as 70% argon will be present in the exhaust gas, resulting in a decrease in argon yield.
一方、原料アルゴン中のアルゴン濃度と窒素濃度との間
には正の相関関係があり、窒素濃度を規格値ぎりぎり、
例えばＩＯ００ｐｐｍ以下の範囲でできるだけ高く保持
することによりアルゴン収率の向上が可能となる。On the other hand, there is a positive correlation between the argon concentration in the raw material argon and the nitrogen concentration.
For example, it is possible to improve the argon yield by keeping the IO as high as possible within the range of 00 ppm or less.
そこで、アルゴンガスの製造に際しては、原料アルゴン
中の窒素濃度を正確に把握して、原料アルゴン中の窒素
濃度を１１０００ｐｐ以下に抑える必要があるが、従来
の原料アルゴン中の窒素濃度の制御方法は、ガスクロマ
トグラフィー分析装置により間欠的に測定される窒素濃
度をオペレータが見ながら経験的に酸素精留塔からの酸
素抜出量ｕ１を操作し制御するというものであった。し
かし、酸素抜出量ｕ１を操作量とすると、操作から窒素
濃度に影響が及ぶまでに時間がかかり、外乱または目標
値の変更に対して過度応答特性が良くなかった。Therefore, when producing argon gas, it is necessary to accurately grasp the nitrogen concentration in the raw material argon and suppress the nitrogen concentration in the raw material argon to 11,000 pp or less, but the conventional method for controlling the nitrogen concentration in the raw material argon is In this method, an operator experimentally manipulates and controls the amount of oxygen extracted from the oxygen rectification column while observing the nitrogen concentration intermittently measured by a gas chromatography analyzer. However, when the oxygen extraction amount u1 is the manipulated variable, it takes time for the operation to affect the nitrogen concentration, and the transient response characteristics to disturbances or changes in the target value are not good.
そこで、窒素濃度の応答特性を向上させるために、本出
願人は先に、特開昭６３−２６３３８１号公報乙こより
、酸素精留塔の特定段の温度または特定成分の濃度から
連続推定される窒素濃度を、ガスクロマトグラフィー分
析装置により間欠的に測定される窒素濃度を用いて補正
し、計算機により酸素抜出量ｕ１を操作することにより
、この補正された窒素濃度（連続推定値）を目標値に一
致させる制御法を提案した。Therefore, in order to improve the response characteristics of the nitrogen concentration, the present applicant first proposed a method that can be continuously estimated from the temperature of a specific stage of an oxygen rectification column or the concentration of a specific component. By correcting the nitrogen concentration using the nitrogen concentration intermittently measured by a gas chromatography analyzer and manipulating the oxygen extraction amount u1 by a computer, this corrected nitrogen concentration (continuous estimated value) is set as the target. A control method to match the value was proposed.
また、本発明者らは先に、特願昭６３−１０００７３号
により、酸素精留塔の特定段の温度または特定成分の濃
度から連続推定される窒素濃度をさらにガスクロマトグ
ラフィー分析装置により間欠的に測定される窒素濃度を
用いて補正し、この補正された窒素濃度（連続推定値）
を、計算機により酸素抜出量目あるいは原料空気量Ｕ、
あるいは酸素抜出量Ｕ、および原料空気Ｎｕｓを操作す
ることにより、目標値に一致させる制御法を提案した。In addition, the present inventors previously disclosed in Japanese Patent Application No. 100073/1983 that the nitrogen concentration, which is continuously estimated from the temperature of a specific stage of an oxygen rectification column or the concentration of a specific component, is further analyzed intermittently using a gas chromatography analyzer. This corrected nitrogen concentration (continuous estimate) is corrected using the nitrogen concentration measured in
The amount of oxygen extracted or the amount of raw air U is determined by a calculator.
Alternatively, a control method was proposed to match the target value by manipulating the oxygen extraction amount U and the raw air Nus.
（発明が解決しようとする課題）
ところで、この特願昭６３−１０００７３号により提案
した方法では、前述したように、原料アルゴン中の窒素
濃度を制御する際、原料アルゴン中の窒素濃度を連続的
に高精度で推定または測定しなければならないが、この
原料アルゴン中の窒素濃度の推定は酸素精留塔の特定段
の温度から換算した推定値をガスクロマトグラフィー分
析装置で間欠的に測定される窒素濃度で補正すること、
あるいは酸素精留塔の特定段の特定成分の濃度から換算
した推定値をガスクロマトグラフィー分析装置で間欠的
に測定される窒素濃度で補正することにより行われてい
た。(Problem to be Solved by the Invention) By the way, in the method proposed in this Japanese Patent Application No. 100073/1983, when controlling the nitrogen concentration in the raw material argon, the nitrogen concentration in the raw material argon is continuously controlled. The nitrogen concentration in the raw argon must be estimated or measured with high accuracy, but the estimated value converted from the temperature of a specific stage of the oxygen rectification column is intermittently measured using a gas chromatography analyzer. To correct for nitrogen concentration,
Alternatively, the estimated value calculated from the concentration of a specific component in a specific stage of an oxygen rectification column is corrected by the nitrogen concentration intermittently measured by a gas chromatography analyzer.
しかし、操業中に原料空気量Ｕ、の変動が発生した場合
、窒素濃度の推定精度が低下してしまうという問題があ
った。However, there is a problem in that when the feed air amount U changes during operation, the accuracy of estimating the nitrogen concentration decreases.
従来は、このような窒素濃度の推定精度の低下という問
題に対しては、ガスクロマトグラフィー分析装置で間欠
的に測定される原料アルゴン中の窒素濃度を用いて補正
することにより対処していたが、ガスクロマトグラフィ
ー分析装置は分析に１０分間程度要し、連続的に補正を
行うことは不可能であるため、この間の推定精度は、や
はり祇Ｆしていた。Previously, this problem of reduced estimation accuracy of nitrogen concentration was dealt with by correcting it using the nitrogen concentration in the raw material argon, which was measured intermittently with a gas chromatography analyzer. Since the gas chromatography analyzer requires about 10 minutes for analysis and it is impossible to perform continuous correction, the estimation accuracy during this time was still at a disadvantage.
すなわち、従来の技術では、原料アルゴン中の窒素濃度
の制御に際して、操業中に原料空気量の変動が発生した
場合、原料アルゴン中の窒素濃度の推定精度の低下を防
ぐことは不可能であったのである。In other words, with conventional technology, when controlling the nitrogen concentration in the raw material argon, it is impossible to prevent the estimation accuracy of the nitrogen concentration in the raw material argon from decreasing if fluctuations occur in the amount of raw material air during operation. It is.
ここに、本発明の目的は、上記の問題を解決すること、
すなわち原料空気量の変動が発生した場合においても、
原料アルゴン中の窒素濃度の早く正確な推定を可能とし
、前記窒素濃度を高精度で制御することが可能な、原料
アルゴン中の窒素濃度の制御方法を提供することにある
。Herein, it is an object of the present invention to solve the above problems,
In other words, even when fluctuations occur in the amount of raw air,
It is an object of the present invention to provide a method for controlling the nitrogen concentration in raw material argon, which enables quick and accurate estimation of the nitrogen concentration in raw material argon and allows the nitrogen concentration to be controlled with high precision.
（課題を解決するための手段）
本発明者らは、上記課題を解決するため、まず原料空気
量の変動が発生した場合に、原料アルゴン中の窒素濃度
の推定精度が低下する原因について、詳細に検討した。(Means for Solving the Problems) In order to solve the above problems, the present inventors first studied in detail the cause of the decrease in the estimation accuracy of the nitrogen concentration in the raw material argon when a fluctuation in the amount of raw material air occurs. We considered this.
その結果、操業中に原料空気量の変動が発生すると、酸
素精留塔上塔内の圧力が変動し、これに伴い酸素精留塔
の特定段の温度が変動するため、酸素精留塔上塔内の温
度と原料アルゴン中の窒素濃度との間の相関関係が、原
料空気量の変動の前後で変化してしまうことを知見した
。As a result, if the feed air amount fluctuates during operation, the pressure in the upper column of the oxygen rectification column will fluctuate, and the temperature of a specific stage of the oxygen rectification column will change accordingly. It was discovered that the correlation between the temperature inside the tower and the nitrogen concentration in the feedstock argon changes before and after changes in the feedstock air amount.
第２図は、先に提案した特開昭６３−２６３３８１号公
報において例示した、原料アルゴン中の窒素濃度と酸素
精留塔の４３段における温度との間の相関関係を示すグ
ラフであり、■の状態は、原料空気量。FIG. 2 is a graph showing the correlation between the nitrogen concentration in the raw argon and the temperature at the 43rd stage of the oxygen rectification column, as exemplified in the previously proposed Japanese Patent Application Laid-open No. 63-263381. The state of is the amount of raw air.
６０００ＯＮｍ”／ｈｒ 、上塔４５段の内部の圧カニ
１．３７ｋｇｆ／−の場合であり、■の状態は、原料空
気量：５Ｂ００ＯＮｍ’／ｈｒ、上塔４５段の内部の圧
カニ１．３５ｋｇｆ／ｃ−の場合である。6000ONm"/hr, the pressure crab inside the 45th stage of the upper column is 1.37kgf/-, and the condition (2) is the case where the amount of raw air is 5B00ONm'/hr, the pressure crab inside the 45th stage of the upper column is 1.35kgf/-. /c-.
第２図において、■の状態が原料空気量が変動する前の
状態を示し、■の状態が原料空気量が変動した後の状態
を示すものとすると、■の状態の場合は、この関係（原
料アルゴン中の窒素濃度と４３段の温度との相関関係を
示すものとして、予め設定されでいる）を用いて推定し
、さらにガスクロマトグラフィー分析装置による分析値
を用いて補正を行うことで、原料アルゴン中の窒素濃度
の推定精度は充分に確保することができる。In FIG. 2, if the state of ■ indicates the state before the raw air amount fluctuates, and the state of ■ indicates the state after the raw material air amount fluctuates, then in the case of the state of ■, this relationship ( By estimating the correlation between the nitrogen concentration in the raw material argon and the temperature of the 43rd stage (preset), and further correcting using the analysis value from the gas chromatography analyzer, Sufficient accuracy in estimating the nitrogen concentration in the raw material argon can be ensured.
しかし、この状態から原料空気量が変動すると、原料ア
ルゴン中の窒素濃度と４３段の温度との間の相関関係は
■の状態から■の状態に変化してしまう。したがって、
原料空気量が変動したにもかかわらず、■の相関関係を
用いた場合に推定される窒素濃度が例えばａ値のときに
は、実際の窒素濃度はｂ値である。したがって、１ａ−
ｂｌ（ｉの誤差を生してしまうことになり、原料アルゴ
ン中の窒素濃度の推定精度が低下してしまうのである。However, if the raw material air amount changes from this state, the correlation between the nitrogen concentration in the raw argon and the temperature of the 43rd stage changes from the state (■) to the state (2). therefore,
Even though the raw material air amount fluctuates, when the nitrogen concentration estimated using the correlation (2) is, for example, the a value, the actual nitrogen concentration is the b value. Therefore, 1a-
This results in an error in bl(i), which reduces the accuracy of estimating the nitrogen concentration in the raw argon.
そこで、本発明者らは、さらに検討を重ねた結果、特開
昭６３−２６３３８１号公報または特願昭６３−１００
０７３号において提案したように、原料アルゴン中の窒
素濃度を、酸素精留塔の特定段の特定の成分の濃度また
は特定段の温度から推定するのではなく、原料アルゴン
中の窒素濃度を酸素精留塔の特定段の温度と特定段の圧
力とから推定することが、原料アルゴン中の窒素濃度の
推定精度を向上させるには、有効であることを知見した
。Therefore, as a result of further study, the inventors of the present invention found that
As proposed in No. 073, instead of estimating the nitrogen concentration in the feed argon from the concentration of a specific component in a specific stage of the oxygen rectification column or the temperature of a specific stage, the nitrogen concentration in the feed argon is estimated from the oxygen purification method. It has been found that estimating from the temperature and pressure of a specific stage of the distillation column is effective in improving the accuracy of estimating the nitrogen concentration in the raw argon.
さらに検討を重ねた結果、このようにして推定した原料
アルゴン中の窒素濃度を、ガスクロマトグラフィー分析
装置を用いて実測した原料アルゴン中の窒素濃度の間欠
測定値に基づいて補正することにより、原料アルゴン中
の窒素濃度を高精度で連続的に推定できることを本発明
者らは知見して、本発明を完成した。As a result of further studies, the nitrogen concentration in the raw material argon estimated in this way was corrected based on the intermittent measurement values of the nitrogen concentration in the raw material argon actually measured using a gas chromatography analyzer. The present inventors have discovered that the nitrogen concentration in argon can be continuously estimated with high accuracy, and have completed the present invention.
ここに、本発明の要旨とするところは、空気を原料とし
て酸素および窒素を分離する酸素精留塔上塔の中程から
抜き出される原料アルゴン中の窒素濃度を制御する方法
において、原料アルゴン中の窒素濃度を酸素精留塔の特
定段の温度と特定段の圧力とを用いて連続推定した推定
値に基づいて、製品酸素の抜出量あるいは原料空気量あ
るいは製品酸素の抜出量および原料空気量を操作して、
前記窒素濃度を予め設定された値に連続自動制御するこ
とを特徴とする原料アルゴン中の窒素濃度の制御方法で
ある。Here, the gist of the present invention is to provide a method for controlling the nitrogen concentration in raw argon extracted from the middle of the upper column of an oxygen rectification column for separating oxygen and nitrogen using air as a raw material. The amount of product oxygen extracted or the amount of raw material air or the amount of product oxygen extracted and the amount of raw material By controlling the amount of air,
This method of controlling the nitrogen concentration in raw material argon is characterized by continuously and automatically controlling the nitrogen concentration to a preset value.
（作用）
次に、添付図面を参照しなら、本発明をさらに詳細に説
明する。(Operation) The present invention will now be described in further detail with reference to the accompanying drawings.
まず、本発明を実施するためのプラントの構成は、前述
した、第１図に示す従来のプラントと同しでよい。First, the configuration of a plant for implementing the present invention may be the same as the conventional plant shown in FIG. 1 described above.
また、本発明と特願昭６３−１０００７３号により提案
した方法との相違点は、原料アルゴン中の窒素濃度の推
定因子を、酸素精留塔上塔の特定段の温度および特定段
の圧力としている点である。なお、本発明においても、
特願昭６３−１０００７３号により提案した方法と同様
に、原料空気量Ｕ、を操作量としいるため、過度応答特
性が極めて良好である。Furthermore, the difference between the present invention and the method proposed in Japanese Patent Application No. 100073/1983 is that the estimation factor for the nitrogen concentration in the raw argon is determined by using the temperature and pressure at a specific stage of the upper column of the oxygen rectification column. This is the point. In addition, also in the present invention,
Similar to the method proposed in Japanese Patent Application No. 63-100073, since the amount of raw air U is used as the manipulated variable, the transient response characteristics are extremely good.
本発明においては、原料アルゴン中の窒素濃度を酸素精
留塔上塔の特定段の温度と特定段の圧力とを用いて連続
的に推定し、さらにこの推定値をガスクロマトグラフィ
ー分析装置による間欠測定値を用いて補正すること、す
なわち（１）弐および（２）式に基づいて補正すること
により、高精度で連続推定できる。In the present invention, the nitrogen concentration in the feed argon is continuously estimated using the temperature and pressure of a specific stage in the upper column of the oxygen rectification column, and this estimated value is then intermittently analyzed using a gas chromatography analyzer. By correcting using the measured values, that is, by correcting based on equations (1) and (2), continuous estimation can be performed with high accuracy.
Ｃｗｚ（ｎ） ＝ａＴ（ｎ） ＋ｂＰ（ｎ＞ ＋ｃ＋δ
（鋼）・・・（］）δ（ｍ）＝δ（ｍ−１） ＋Ｇｐ（
Δ（ｍ）−Δ（ｍ−１）） ＋Ｇｌ（Δ（ｍ）−δ（■
−１））・・・・（２）Δ（ｍ）＝ＣＮｚｇ（ｍ）
（ａＴ（ｍ）＋ｂＰ（ｍ）＋ｃ） ・・・（３）Δ（＊
−１） ＝Ｃｘｚｇ（１−１） （ａＴ（ｍ−１）
＋ｂＰ（ｍ−１） ＋ｃ）・・・（４）
ただし、
ＣＮＺ ： 原料アルゴン中の窒素濃度の連続推定値
ＣＮ２＠’ ガスクロマトグラフィー分析装置による
原料アルゴン中の窒素濃度の間欠測
定値
：酸素精留塔上塔の特定段の温度
Ｐ ：酸素精留塔上塔の特定段の圧力ａ、ｂ、ｃ ：
換算係数
δ ：ガスクロマトグラフィー分析装置による原料ア
ルゴン中の窒素濃度の間欠測
定値から算出され、ａＴ（ｎ）＋ｂＰ（ｎ）＋ｃにより
求まる換算値を真の窒素濃度に近
づけるための補正値
ＣＰ、Ｃ，：補正係数（ゲイン）
ｎ 、制御周期を単位とする時刻
ＩＩｌ二時刻ｎの時に一番最近ガスクロマトグラフィー
分析装置で測定した時刻
すなわち、本発明において酸素精留塔上塔のある特定段
の圧力の値毎に、その特定段の温度と窒素濃度との関係
を事前に求めておき、測定時の圧力および温度から、原
料アルゴン中の窒素濃度を求めるのである。Cwz(n) =aT(n) +bP(n> +c+δ
(Steel)...(]) δ(m)=δ(m-1) +Gp(
Δ(m)−Δ(m−1)) +Gl(Δ(m)−δ(■
-1))...(2)Δ(m)=CNzg(m)
(aT(m)+bP(m)+c)...(3)Δ(*
-1) =Cxzg(1-1) (aT(m-1)
+bP(m-1) +c)...(4) However, CNZ: Continuous estimated value of nitrogen concentration in raw material argon CN2@' Intermittent measurement value of nitrogen concentration in raw material argon by gas chromatography analyzer: Oxygen concentration Temperature P at a specific stage in the upper column of the distillation column: Pressure a, b, c at a specific stage in the upper column of the oxygen rectification column:
Conversion coefficient δ: correction value CP, which is calculated from intermittent measurements of the nitrogen concentration in the raw material argon by a gas chromatography analyzer, and is used to bring the converted value found by aT(n)+bP(n)+c closer to the true nitrogen concentration; C,: correction coefficient (gain) n, the time most recently measured by a gas chromatography analyzer at time IIl2 time n in the unit of control period, that is, in the present invention, a certain stage of the upper column of the oxygen rectification column For each pressure value, the relationship between the temperature and nitrogen concentration at that particular stage is determined in advance, and the nitrogen concentration in the raw argon is determined from the pressure and temperature at the time of measurement.
そして、本発明においては、このようにして得た推定値
と予め求めておいた目標値との差に応して、製品酸素の
抜出量あるいは原料空気量あるいは製品酸素の抜出量お
よび原料空気量を操作することにより、原料アルゴン中
の窒素濃度を目標値に連続自動制御する。In the present invention, the amount of product oxygen extracted or the amount of raw material air or the amount of product oxygen extracted or the amount of raw material By manipulating the amount of air, the nitrogen concentration in the raw argon is continuously and automatically controlled to the target value.
この場合に、酸素抜出量、原料空気量あるいは、酸素抜
出量および原料空気量に関しての操作は、具体的には次
のように行われる。In this case, operations regarding the amount of oxygen extracted, the amount of raw material air, or the amount of oxygen extracted and the amount of raw material air are specifically performed as follows.
すなわち、酸素抜出量、原料空気量等の入力変数から原
料アルゴン中の窒素濃度、原料空気の温度等の酸素プラ
ントの状態変数への応答特性の関係から予め求めたゲイ
ンを制？３ｉ１量の目標値に対する偏差および状態変数
の値に掛けて操作量を求めて操作量を連続的に操作する
。In other words, the gain is determined in advance from the relationship between the response characteristics of input variables such as the amount of oxygen extracted and the amount of feed air to the state variables of the oxygen plant such as the nitrogen concentration in the feed argon and the temperature of the feed air. The manipulated variable is continuously manipulated by multiplying the deviation of the 3i1 quantity from the target value and the value of the state variable to obtain the manipulated variable.
なお、本発明にかかる方法を実施する場合には、次の手
順によればよい。In addition, when implementing the method according to the present invention, the following procedure may be used.
■プロセスの動特性を自己回帰モデルにより同定する。■Identify the dynamic characteristics of the process using an autoregressive model.
■自己回帰モデルで同定されたプロセス動特性から操作
量算出のためのゲインを求める。■Determine the gain for calculating the manipulated variable from the process dynamic characteristics identified by the autoregressive model.
■制御量の偏差および状態変数の値に予め求めたゲイン
をかけることにより操作量を求めてこの操作量を連続的
に操作する。(2) A manipulated variable is obtained by multiplying the deviation of the controlled variable and the value of the state variable by a predetermined gain, and this manipulated variable is continuously manipulated.
このようにして、本発明によれば、原料空気量の変動に
より酸素精留塔上塔の特定段の圧力が変動した場合の原
料アルゴン中の窒素濃度の推定が従来より高精度になり
、例えば特開昭６３−２６３３８１号公報、特願昭６３
−１０００７３号に示した方法に比較して前記窒素濃度
を安定化して、原料アルゴン中の窒素濃度の目標値を１
１０００ｐｐという上限値に可能な限り近づけての操業
が可能となる。したがって、アルゴン収率を向上させる
ことができる。In this way, according to the present invention, the estimation of the nitrogen concentration in the feed argon when the pressure in a specific stage of the upper column of the oxygen rectification column fluctuates due to a change in the amount of feed air becomes more accurate than before, for example. Japanese Unexamined Patent Publication No. 1983-263381, Patent Application No. 1983
Compared to the method shown in No.-100073, the nitrogen concentration is stabilized, and the target value of the nitrogen concentration in the raw material argon is reduced to 1.
It becomes possible to operate as close to the upper limit of 1000 pp as possible. Therefore, the argon yield can be improved.
さらに、本発明を実施例を用いて詳述するが、これはあ
くまでも本発明の例示であり、これにより本発明が限定
されるものではない。Further, the present invention will be explained in detail using Examples, but these are merely illustrative of the present invention and the present invention is not limited thereby.
実施例１
酸素精留塔上塔の中程から抜き出される原料アルゴン中
の窒素濃度を制御する際に、本発明にかかる方法と特願
昭６３−１０００７３号により提案した方法とを用いて
、原料アルゴン中の窒素濃度の推定を行った。Example 1 When controlling the nitrogen concentration in the raw argon extracted from the middle of the upper column of the oxygen rectification column, the method according to the present invention and the method proposed in Japanese Patent Application No. 100073/1982 were used. The nitrogen concentration in the raw material argon was estimated.
すなわち、本発明例として、原料アルゴン中の窒素濃度
を酸素精留塔１の第４３段の温度と第４５段の圧力とを
用いて連続推定した。That is, as an example of the present invention, the nitrogen concentration in the raw argon was continuously estimated using the temperature at the 43rd stage and the pressure at the 45th stage of the oxygen rectification column 1.
なお、時刻ｍ、 ｍ−］におけるガスクロマトグラフィ
ー分析装置による原料アルゴン中の窒素濃度の測定値Ｃ
，□９と酸素精留塔工の第４３段の温度Ｔと第４５段の
圧力Ｐを用いて式（３）、（４）、（２）からΔ（ｍ）
、Δ（ｍ−１） 、δ（ｆｆｉ）を求め、式（１）から
δ（１１）を用いて原料アルゴン中の窒素濃度の推定値
Ｃ８□をｍ（＝ｎ）、 ｎ＋１． ｎ＋２１．、．１
ｍ＋１（＝ｎ＋１０）の各時刻（ｍ＋１を除く）
について求める。In addition, the measured value C of the nitrogen concentration in the raw material argon by the gas chromatography analyzer at time m, m-]
, □9, the temperature T of the 43rd stage of the oxygen rectification column, and the pressure P of the 45th stage, from equations (3), (4), and (2), Δ(m)
, Δ(m-1), δ(ffi), and using δ(11) from equation (1), the estimated value C8□ of the nitrogen concentration in the raw material argon is calculated as m(=n), n+1. n+21. ,． 1
Find each time (excluding m+1) of m+1 (=n+10).
ここで各定数は
ａ −−０，２０、ｂ ＝２０．０、ｃ−−６０，８Ｇ
Ｐ−０，１０ＸＧ＋＝０．２０
一方、比較例として、原料アルゴン中の窒素濃度を酸素
精留塔１の第４３段の温度を用いて連続推定した。Here each constant is a --0,20, b =20.0, c --60,8G
P-0,10XG+=0.20 On the other hand, as a comparative example, the nitrogen concentration in the raw argon was continuously estimated using the temperature of the 43rd stage of the oxygen rectification column 1.
そして、この両方の場合に、ガスクロマトグラフィー分
析装置を用いて、窒素濃度を測定した。In both cases, the nitrogen concentration was measured using a gas chromatography analyzer.
結果を第３図（ａ）および第３図（ｂ）に、窒素濃度の
実績値と推定値との関係において示す。The results are shown in FIGS. 3(a) and 3(b) in terms of the relationship between the actual value and estimated value of nitrogen concentration.
この第３図（ａ）および第３図（ｂ）から明らかなよう
に、本発明により、原料アルゴン中の窒素濃度の推定精
度が窒素濃度の対数値の標準偏差で±０．１向上した。As is clear from FIGS. 3(a) and 3(b), according to the present invention, the accuracy of estimating the nitrogen concentration in the raw argon was improved by ±0.1 in terms of the standard deviation of the logarithm of the nitrogen concentration.
実施例２
酸素精留塔上塔の中程から抜き出される原料アルゴン中
の窒素濃度を制御する際に、原料アルゴン中の窒素濃度
を、
（１）酸素精留塔の第４３段の温度と第４５段の圧力と
を用いて、前記（１）ないしく４）式を用いる方法（本
発明例）、
（２）酸素精留塔の第４５段の温度を用いる方法（比較
例）、
により推定し、この値に基づいて、製品酸素の抜出量を
操作して前記原料アルゴン中の窒素濃度を予め設定され
た値に制御して、窒素濃度の制御結果をガスクロマトグ
ラフィー分析装置により実測した。Example 2 When controlling the nitrogen concentration in the raw material argon extracted from the middle of the upper column of the oxygen rectification column, the nitrogen concentration in the raw material argon was adjusted to (1) the temperature of the 43rd stage of the oxygen rectification column and (2) a method using the temperature of the 45th stage of the oxygen rectification column (comparative example); Based on this value, the amount of product oxygen extracted is controlled to control the nitrogen concentration in the raw material argon to a preset value, and the nitrogen concentration control result is actually measured using a gas chromatography analyzer. did.
結果を第４図（ａ）および第４図（ｂ）に示す。第４図
（ａ）および第４図（ｂ）から明らかなように、本発明
により、原料アルゴン中の窒素濃度を１１０００ｐｐ以
下で、高濃度に安定することができ、窒素濃度の目標値
を従来の６００ｐｐｍから７００ｐｐＩｌとすることが
できた。The results are shown in FIGS. 4(a) and 4(b). As is clear from FIG. 4(a) and FIG. 4(b), according to the present invention, the nitrogen concentration in the raw material argon can be stabilized at a high concentration of 11,000 pp or less, and the target value of nitrogen concentration can be lowered than the conventional one. It was possible to reduce the amount from 600 ppm to 700 ppIl.
（発明の効果）
以上詳述したように、本発明により、原料空気量の変動
により酸素精留塔上塔の特定段の圧力が変動した場合に
も、原料アルゴン中の窒素濃度の推定精度を向上させる
ことが可能となった。(Effects of the Invention) As detailed above, the present invention improves the accuracy of estimating the nitrogen concentration in the argon feed even when the pressure in a specific stage of the upper column of the oxygen rectification column fluctuates due to fluctuations in the amount of feed air. It was possible to improve it.
したがって、原料アルゴン中の目標値を、上限である１
１０００ｐｐに大幅に近づけて操業することができるた
め、アルゴン収率を向上させることができる。Therefore, the target value in the raw material argon is set to the upper limit of 1
The argon yield can be improved since it can be operated much closer to 1000 pp.
かかる効果を有する本発明の意義は極めて著しい。The significance of the present invention having such effects is extremely significant.
第１図は、空気分離プロセスの一例の概要を示す略式説
明図：
第２図は、酸素精留塔上塔の圧力が異なる場合の４３段
の温度と原料アルゴン中の窒素濃度の関係を示すグラフ
第３図（ωおよび第３図〜）は、本発明の実施例におけ
る窒素濃度を示すグラフ；および
第４図（ａ）および第４図（ｂ）は、他の実施例におけ
る原料アルゴン中の窒素濃度の分析を示すグラフである
。
１：酸素精留塔 １ａ・酸素精留塔上塔１ｂ、酸素
精留塔下塔 ＩＣ：凝縮器
２：冷却器 ３ａ 、 ３ｂ ：熱交換器４ニオ
且アルゴン塔Figure 1 is a schematic explanatory diagram showing an overview of an example of an air separation process. Figure 2 shows the relationship between the temperature of the 43rd stage and the nitrogen concentration in the raw argon when the pressure in the upper column of the oxygen rectification column is different. Graph 3 (ω and 3~) is a graph showing the nitrogen concentration in an example of the present invention; and 4(a) and 4(b) are graphs showing the nitrogen concentration in the raw material argon in other examples It is a graph showing an analysis of the nitrogen concentration of. 1: Oxygen rectification column 1a, oxygen rectification column upper column 1b, oxygen rectification column lower column IC: Condenser 2: Cooler 3a, 3b: Heat exchanger 4 Nitrogen and argon column
Claims (1)
上塔の中程から抜き出される原料アルゴン中の窒素濃度
を制御する方法において、原料アルゴン中の窒素濃度を
酸素精留塔の特定段の温度と特定段の圧力とを用いて連
続推定した推定値に基づいて、製品酸素の抜出量あるい
は原料空気量あるいは製品酸素の抜出量および原料空気
量を操作して、前記窒素濃度を予め設定された値に連続
自動制御することを特徴とする原料アルゴン中の窒素濃
度の制御方法。In a method for controlling the nitrogen concentration in raw argon extracted from the middle of the upper column of an oxygen rectification column that uses air as a raw material to separate oxygen and nitrogen, the nitrogen concentration in the raw argon is controlled by controlling the nitrogen concentration in a specific stage of the oxygen rectification column. The nitrogen concentration is determined in advance by manipulating the amount of product oxygen removed or the amount of feed air, or the amount of product oxygen removed and the amount of feed air, based on the estimated value that is continuously estimated using the temperature and the pressure of a specific stage. A method for controlling nitrogen concentration in raw material argon, characterized by continuously and automatically controlling it to a set value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4217190A JPH03244990A (en) | 1990-02-22 | 1990-02-22 | Control of nitrogen concentration in material argon |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4217190A JPH03244990A (en) | 1990-02-22 | 1990-02-22 | Control of nitrogen concentration in material argon |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH03244990A true JPH03244990A (en) | 1991-10-31 |
Family
ID=12628526
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4217190A Pending JPH03244990A (en) | 1990-02-22 | 1990-02-22 | Control of nitrogen concentration in material argon |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH03244990A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0609814A1 (en) * | 1993-02-01 | 1994-08-10 | Praxair Technology, Inc. | Process for maximizing the recovery of argon from an air separation system at high argon recovery rates |
| FR2855872A1 (en) * | 2004-06-25 | 2004-12-10 | Air Liquide | Cryogenic air separation, for argon production, uses plant with second level of low-pressure column above first level and separated from it by theoretical plates |
| JP2005114349A (en) * | 2003-10-06 | 2005-04-28 | L'air Liquide Sa Pour L'etude & L'exploitation Des Procede S Georges Claude | Method and system for optimizing argon recovery in air separation unit |
| JP2021110466A (en) * | 2020-01-06 | 2021-08-02 | 日本エア・リキード合同会社 | Air separation system |
-
1990
- 1990-02-22 JP JP4217190A patent/JPH03244990A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0609814A1 (en) * | 1993-02-01 | 1994-08-10 | Praxair Technology, Inc. | Process for maximizing the recovery of argon from an air separation system at high argon recovery rates |
| JP2005114349A (en) * | 2003-10-06 | 2005-04-28 | L'air Liquide Sa Pour L'etude & L'exploitation Des Procede S Georges Claude | Method and system for optimizing argon recovery in air separation unit |
| FR2855872A1 (en) * | 2004-06-25 | 2004-12-10 | Air Liquide | Cryogenic air separation, for argon production, uses plant with second level of low-pressure column above first level and separated from it by theoretical plates |
| JP2021110466A (en) * | 2020-01-06 | 2021-08-02 | 日本エア・リキード合同会社 | Air separation system |
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