JPH07119682B2 - Adsorption equilibrium measurement method and adsorption equilibrium measurement device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a so-called adsorption equilibrium measurement for measuring an adsorption amount of a solvent that a sample may contain under a predetermined temperature and a predetermined relative vapor pressure, and a measurement method thereof. And a measuring device. It is important to know the amount of adsorption as described above, for example, for tobacco manufacturers to control the water content of leaf tobacco, and for this reason the adsorption equilibrium is measured when water is used as a solvent for tobacco leaves. .

[Conventional technology]

As a conventional device of this type, a weighing means for measuring the weight of a sample is housed in an airtight container, the airtight container and solvent vapor are set to a desired temperature, and a solenoid valve is opened and closed while detecting the pressure in the container. Then, a solvent vapor having a predetermined pressure is introduced into the airtight container, and the adsorption equilibrium of the sample in the airtight container is measured.

When measuring the adsorption equilibrium, set a predetermined temperature with the sample such as tobacco leaf set in the measuring means in the airtight container and dry the sample by vacuumizing the airtight container and measuring the dry weight to a certain degree. Drying is terminated when the weight balance is reached.

When the sample is dried, a solvent vapor such as water vapor is introduced into the airtight container at a predetermined temperature, and the relative vapor pressure calculated from the pressure and temperature in the container is adjusted to a preset relative vapor pressure. When the adsorption by the sample is controlled and the equilibrium state is reached, the sample weight, the relative vapor pressure and the temperature are measured, and the adsorption isotherm is obtained based on these measured values and the dry weight during drying.

FIG. 10 is a view for explaining changes in sample weight and determination of weight balance in the conventional sample drying process, and determination of weight balance during conventional drying is performed as follows.

The time elapsed from the start of drying (point A) is measured and the change in sample weight is measured, and this measured time T _dai is within the preset weight stabilization time T _da , that is, T _dai <T _da , When the weight change Δw reaches the preset allowable weight W _da , that is, when Δw = W _da (time B), the time measurement T _dai and the weight change Δ
w is reset, and further, the time measurement is started from this time point and the weight change Δw from that time point is measured.

Then, the same determination is sequentially performed, and when both the conditions of T _dai ≧ T _da and Δw ≦ W _da are satisfied (at the time of G), the equilibrium state is determined and the drying is finished.

FIG. 9 is a diagram showing changes with time in relative vapor pressure inside the container and sample weight in the process of measuring adsorption equilibrium by conventional control. First, the relative vapor pressure P inside the container is set relative to the preset relative vapor pressure P. _{When the} solvent vapor is introduced into the container so that it becomes _s or more and the sample absorbs the solvent vapor and the relative vapor pressure P decreases to the set relative vapor pressure P _s , the solvent vapor is introduced each time and the relative vapor pressure P Is controlled.

On the other hand, although the sample weight changes with time due to adsorption, the sample weight is measured while the relative vapor pressure is controlled as described above, and the sample weight during the preset weight stabilization time T _ka is When the change becomes equal to or less than a preset allowable amount, it is determined that the adsorption has reached equilibrium, and the temperature, pressure and sample weight at that time are measured as equilibrium data.

Then, the equilibrium data is measured for a plurality of preset relative vapor pressures set in advance, and the adsorption isotherm for the sample at a predetermined temperature is calculated by calculating the relative vapor pressure and the adsorption amount at equilibrium from the measured equilibrium data. Desired. In addition,
The adsorption amount and the relative vapor pressure are obtained as follows.

If the dry weight of the sample is W _c , the temperature at the time of adsorption equilibrium measurement is T _k , the saturated vapor pressure at this temperature T _k is Q ₀ , and the pressure and sample weight measured as equilibrium data are Q and W _k , respectively, the adsorption amount M relative vapor pressure P _k is determined by _{M = (W k -W c)} / W c × 100 ......... (1) P k = Q / Q 0 × 100 ......... (2).

[Problems to be Solved by the Invention]

According to the conventional method as described above, since the equilibrium is determined at the discontinuous points such as points B, C, D, E, F and G shown in FIG. 10 in the drying process, for example, Even if the weight change Δw between the two points E ′ and F ′ having the time difference of the weight stabilization time T _da before and after the point F is within the allowable weight W _da , the weight equilibrium cannot be detected and the drying is performed. The process took extra time.

Further, in the process of measuring the adsorption equilibrium, since the weight equilibrium is determined while controlling the relative vapor pressure with respect to the set pressure, the solvent vapor is introduced while the sample weight is close to equilibrium. Even when it is determined that the sample weight satisfies the equilibrium condition and reaches equilibrium, the equilibrium between the relative vapor pressure and the adsorption amount at that time is disturbed and accurate equilibrium data cannot be obtained. There was a problem.

Therefore, when the sample weight deviates from the weight equilibrium, it takes time to reach equilibrium, and it takes a long time to measure equilibrium data.

[Means for Solving the Problems]

The present invention, in the adsorption equilibrium measuring device, when the relative vapor pressure in the airtight container is maintained within a preset allowable range for a preset period of time, after that, the introduction of the solvent vapor is stopped, and then in the airtight container. The relative equilibrium of relative vapor pressure was determined, and the adsorption equilibrium was determined by determining the weight equilibrium based on the preset equilibrium weight tolerance and the equilibrium weight stabilization time.

Further, when the sample is dried, if the change in the sample weight during a predetermined period of time is within a preset allowable amount, it is determined in advance that equilibrium is determined, such as a sampling cycle of the sample weight. The weight equilibrium was detected by carrying out at a set fixed cycle.

Further, the adsorption equilibrium measuring device according to the present invention, as shown in FIG. 1, has a pressure detecting means for detecting a pressure in the airtight container, a weight detecting means for detecting the weight of the sample, and the pressure detecting means. And a data sampling means for sampling the pressure data and the weight data detected by the weight detecting means at a preset constant cycle, and a storage means for storing the detection data obtained by the data sampling means in correspondence with the sampling order. For each of the pressure data and the weight data stored in the storage means, the old and new detection data corresponding to a preset constant time difference is read out, and the difference between the old and new detection data is compared with the preset value. Comparing means and after drying the sample,
The introduction of the solvent vapor is performed until the detection data of the pressure detection means becomes a preset value or more, and then the introduction and the stop of the solvent vapor are controlled based on the comparison result of the comparison means,
After that, the control means is provided for determining the equilibrium of the relative vapor pressure based on the comparison result of the pressure data of the comparison means and determining the weight balance based on the comparison result of the weight data of the comparison means. Is characterized by.

Further, in the adsorption equilibrium measurement apparatus according to the present invention, in addition to the function of the control means, the airtight container is evacuated, and the weight equilibrium is determined based on the comparison result of the weight data of the comparison means. It may have a function of stopping the exhaust of the airtight container when the weight balance is detected by the determination.

[Work]

According to the measuring method and the measuring apparatus of the present invention, when the relative vapor pressure equilibrium determination and the weight equilibrium determination are performed, the relative vapor pressure is in a substantially stable state, and the subsequent introduction of the solvent vapor is Not done

Therefore, since the adsorption equilibrium is measured in a state where the equilibrium between the relative vapor pressure and the adsorption amount is maintained, the equilibrium is not disturbed during the measurement, and the adsorption equilibrium is promptly measured.

Further, at the time of drying, the weight balance is immediately detected when a predetermined weight balance condition is satisfied, so that the time required for drying is minimized.

〔Example〕

FIG. 2 is a diagram showing an adsorption equilibrium measuring apparatus according to an embodiment of the present invention. In the figure, a measuring means 1 is connected to a vacuum container 10 and this vacuum container 10 for adsorbing and desorbing a solvent vapor on a sample. The vacuum container 10 is made of stainless steel, and the gas adsorption chamber 11 is made of special heat-resistant transparent glass.

An electronic calculator 14 for measuring the weight of the sample container 13 suspended in the gas adsorption chamber 11 via the suspension core 12 is accommodated in the vacuum container 10, and the signal from the electronic calculator 14 is It is input to the measurement control unit 15. The sample container 13 is for containing the sample S made of, for example, dried tobacco leaves, and is made of quartz. Further, the inner wall of the vacuum container 10 is provided with a pressure sensor 16 as a pressure detecting means for measuring the pressure inside the vacuum container 10 and the gas adsorption chamber 11, and a signal from this pressure sensor 16 is output via an amplifier 17 as described above. It is input to the measurement control unit 15.

On the other hand, on the inner wall of the gas adsorption chamber 11, a temperature sensor 18 for measuring the temperature in the gas adsorption chamber 11 is provided. The temperature sensor 18 is composed of, for example, a platinum resistance temperature detector.
The signal generated by 18 is sent to the measurement control unit 15 via the amplifier 19.
Entered in.

Due to the above, the measurement control unit 15 is configured such that the electronic calculator 14
The adsorption temperature line is automatically measured based on the signals from 16 and the temperature sensor 18.

The vacuum container 10 is surrounded by a stainless steel vacuum container storage case 20 having a constant temperature liquid inlet 20a at the bottom and a constant temperature liquid discharge port 20b at the top, and between the vacuum container 10 and the vacuum container storage case 20. It forms a flow path for the constant temperature liquid.

On the other hand, the gas adsorption chamber 11 is surrounded by an outer tube 21 having a constant temperature liquid inlet port 21a and a constant temperature liquid outlet port 21b in the lower part, and the gas adsorption chamber 11 and the outer pipe 21 are filled with a constant temperature liquid liquid. It forms a flow path.

Further, the measuring means 1 is connected to a liquid reservoir 22 containing the solvent A which is the source of the solvent vapor introduced into the vacuum container 10, and the liquid reservoir 22 contains the solvent vapor via the conduits P1 and P2. It is connected to the gas sump 23.

A solenoid valve G1 is provided between the pipeline P1 and the pipeline P2, and the solvent vapor generated in the liquid reservoir 22 is opened and closed by opening and closing the solenoid valve G1.
It is controlling the supply to 23. Gas reservoir 23 is a branch line
It is connected to the vacuum container 10 via P3 and a solenoid valve G2, and is also connected to a trap 24 via a branch pipe line P3, a solenoid valve G3, and pipe lines P4 and P5, and this trap 24 is an oil rotary pump 25.
Together with this, the vacuum exhaust system 2 is configured. A mercury manometer 26 used for calibration of the pressure sensor 16 is connected to the conduit P5 via a conduit P6.

The liquid reservoir 22, the gas reservoir 23 and the branch pipe line P3 are surrounded by outer pipes 27, 28 and 29, respectively. This outer tube 27,2
8 and 29 have constant temperature liquid inlets 27a, 28a and 29a at the bottom or bottom thereof, and constant temperature liquid outlets 27b, 28b above.
And 29b respectively, and the outer tubes 27, 28 and 29, and the liquid reservoir.
A constant temperature liquid reservoir is formed between the gas reservoir 23, the gas reservoir 23 and the branch pipe P3.

The constant temperature liquid of a predetermined temperature supplied to the constant temperature liquid flow path is a constant temperature tank.
It is made by 30 and is introduced into and discharged from each flow path by the circulation pump 31 and is circulated.

The outer tubes 21, 27, 28 and 29 are made of a special heat-resistant transparent glass to have a double tube structure, and in particular, the outer tubes 27, 28 and 29 are fixed to the pedestal 32 by the support fittings K _{1 to} K ₄ . . The pedestal 32 is made portable by the casters C1 and C2.

As shown in FIG. 3, the electronic weighing instrument 14 has a lever 14b which is swingable about a fulcrum 14a.
The above-described sample container 13 is connected to one end of 4b through the hanging core 12, and the other end faces the displacement sensor 14c. Also, one end of the lever 14b on the displacement sensor 14c side and the fulcrum
A force coil 14d in which an insulation-coated copper wire is wound in multiple layers on a bobbin is attached to an intermediate portion of 14a, and this force coil 14d is movably faced between a magnetic gap Mg formed by a magnet 14e and a yoke 14f. ing.

The displacement sensor 14c detects the displacement of the lever 14b due to the load, and inputs the displacement signal to the measurement circuit 14g provided outside the case 20 by the insulating covered electric wire L ₁ . Measurement circuit 14g controls the current flowing through the insulation coated wire L _2, L ₃ as displaced by a signal from the displacement sensor 14c becomes zero force coil 14d, reads its current value, measures the weight of the sample S Then, the measurement result is output to the measurement control unit 15.

Coating of the insulation coated wire L ₁ ~L ₃ is increased is formed by coating without pinholes tetrafluoroethylene resin is a hydrophobic fluorine resin, the measurement accuracy by eliminating the adsorption of the solvent vapor by coating . The coating thickness should be between 10μm and 1000μm, especially 100μm.
m to 300 μm is the best.

The measuring circuit 14g is configured as shown in FIG. 4, and the displacement signal from the displacement sensor 14c is supplied to the preamplifier 141 and the PID controller.
An electric current is passed through the force coil 14d placed in the magnetic field of the magnetic gap Mg through the power amplifier 143 and the power amplifier 143, and the displacement is automatically returned to zero. At this time, the current flowing through the force coil 14d is exactly proportional to the weight that is the source of the displacement, enters the AD converter 145 through the range switching unit 144, is digitized, and then is commanded by the control switch 147 by the microcomputer 146. Various calculations according to the above are performed, and the result is output from the output terminal 148 to the measurement control unit 15.

The measurement control unit 15 is composed of a microprocessor, a memory, a timer, etc., and sequentially loads the weight signal from the measuring circuit 14g, the pressure signal from the pressure sensor 16, and the temperature signal from the temperature sensor 18 at a preset sampling cycle. The above equations (1) and (2) are stored according to the signals stored in the memory or these input signals or the data stored in the memory.
According to the control logic described later, the adsorption isotherm is measured and the result is output to, for example, a printer.

FIG. 8 is a diagram showing another embodiment of the adsorption equilibrium measuring device of the present invention, in which elements corresponding to those in FIG. 2 are designated by the same reference numerals.

In this device, instead of the constant temperature liquid used in the device of FIG. 2, a liquid reservoir 22, a gas reservoir 23 and a measuring means 1 are housed in an air constant temperature bath 3 for temperature setting. is there.

The outer wall 34 of the air constant temperature bath 3 is kept warm by a heat insulating material 35, a partition plate 33 is provided inside the air constant temperature bath 3, and air in the room temperature constant temperature bath is circulated by a blower 36.

The PID controller 42 measures the air temperature in the constant temperature air chamber 3 by the temperature sensor 39 and sends a signal for controlling the temperature to a set temperature to the thyristor 41.
A current corresponding to the signal output from the PID controller 42 is supplied to 38. As a result, the temperature of the air in the air bath is kept at 30 ° C.
It can be adjusted in the range of -80 ° C.

Further, when the cooling CFC gas is circulated from the chiller unit 40 to the cooling coil 37 to cool the air in the constant temperature air chamber,
It is also possible to adjust the temperature range from 0 ° C to 30 ° C.

In place of the solenoid valves G1, G2 and G3 shown in FIG. 2, heat resistant air valves V1, V2 and V3 are attached,
The air valves V1, V2 and V3 are supplied from the nitrogen cylinder 44 with a gauge pressure of 5
It is driven by flowing nitrogen gas of kg / cm ² . In addition,
This nitrogen gas is controlled to open and close by solenoid valves G4, G5 and G6.

Further, in this apparatus, a vacuum gauge 43 is attached instead of the mercury manometer 26.

In the apparatus shown in FIG. 2, the vacuum container 10 and the vacuum container storage case 20 are used.
Made of stainless steel, glass adsorption chamber 11, liquid reservoir 22, gas reservoir 2
3.Pipe lines P1 to P6 and their outer tubes 21, 27, 28, 29 were made of special heat-resistant transparent glass.
The bottom plate of 10 is made of stainless steel, a cover made of special heat-resistant transparent glass is attached to the bottom plate, and the vacuum container 10 is configured by sealing with an O-ring, and the glass adsorption chamber 11 and the liquid reservoir 22 have special heat resistance. Made of transparent glass and all other parts made of stainless steel.

The measurement control in the apparatus of FIG. 8 is performed in the same manner as that of FIG. 2, and hereinafter, the adsorption equilibrium measuring apparatus of FIG. 2 will be described.

5a to 5h are flowcharts showing the control by the measurement control unit 15, FIG. 5a is the main sequence, FIG. 5b is drying, FIG. 5c is adsorption, FIG. 5d is degassing, and FIG. 5e. Shows the control to the set pressure, FIG. 5f shows the steam introduction, FIG. 5g shows the exhaust, and FIG. 5h shows the sequence of the equilibrium data measurement.

As shown in FIG. 5a, the control by the measurement controller 15 is roughly divided into a drying sequence for drying the sample and an adsorption sequence for adsorbing the solvent vapor. In addition, the solvent is stored in the liquid reservoir 22 and the sample is set in the sample container 13 prior to the measurement, and the vacuum exhaust system 2, the constant temperature tank 30, and the circulation pump 31 are arranged.
Is driven to set the temperature of the constant temperature liquid to a predetermined drying temperature.

Then, when a common constant, a drying constant, and a drying start key for activating a drying sequence, which will be described later, are input from an operation unit (not shown) of the measurement control unit 15, the drying sequence is started.

Further, when the drying sequence is completed, a standby state is set, and the temperature setting at the time of adsorption measurement is performed in the same manner as the above-mentioned setting of the drying temperature, and the vapor introduction constant, the exhaust constant, the control constant for the set pressure, and the constant relating to the adsorption equilibrium determination. When each constant and the adsorption start key for activating the adsorption sequence are entered, the adsorption sequence is started and the adsorption equilibrium is measured.

When the drying sequence and the adsorption sequence are started, the timer is started, and the interrupt processing is performed based on the timer content and the later-described sampling cycle set as a common constant. The pressure data, the weight data and the temperature data are sampled and sequentially stored in the memory.

Here, the above-mentioned constants that are input will be described.

(Constant) The common constant is a constant indicating the sampling period T _dat of the measurement data and the number N _dat of sampling data sampled to average the balanced data.

The drying constant is an allowable weight W _da and a weight stabilization time T _da that set the allowable range of the weight change and the allowable time range of the weight balance determination during drying.

The degassing constant is a gas pool that sets the waiting time required to exhaust the gas from the gas reservoir 23, the waiting time required to exhaust the gas in the solvent in the liquid reservoir 22, and the number of times of degassing. Exhaust time T _eg , liquid reservoir exhaust time T _e1 and number of times of desorption N _e
Is.

The vapor introduction constant is a holding time T _S1 while introducing solvent vapor from the liquid reservoir 22 to the gas reservoir 23, a holding time T _s2 while introducing solvent vapor from the gas reservoir 23 to the vacuum container 10, and a response of the pressure sensor 16. Pressure measurement holding time T that is set in consideration of gender delay time, etc.
_sp , a control procedure that changes the control procedure depending on the difference between the relative vapor pressure in the vacuum vessel 10 and the set relative vapor pressure when introducing _steam.The pressure control range P _sa that sets the reference pressure and the fine control performed by changing this control procedure. The number of steam introduction repetitions N _s that limits the number of times.

The exhaust constant is a holding time T _O2 while discharging the solvent vapor from the vacuum container 10 to the gas reservoir 23, a holding time T _o3 while discharging the solvent vapor from the gas reservoir 23, and the vacuum at the time of exhausting similarly to the vapor introduction constant. Change the control procedure according to the difference between the relative vapor pressure in the container 10 and the set relative vapor pressure.Set the reference pressure Pressure control range _Poa
And the number of exhaust cycles N _o that limits the number of fine controls performed by changing this control procedure.

The control constant for the established pressure is determined from a plurality of preset relative vapor pressures P _s (up to 15 in this example) for obtaining the adsorption isotherm, and a set relative vapor pressure of the relative vapor pressure in the vacuum vessel 10. a plurality of setting stepwise reduced tolerance to any of the permissible pressure internal stabilization time T _a to set pressure tolerance P _a (in this embodiment five in the example), is correspondingly set to the vapor plurality of setting tolerance And a permissible outside pressure correction waiting time T _w for setting a waiting time until forced evacuation when the relative vapor pressure in the vacuum container 10 becomes higher than the set relative vapor pressure.

The constants related to the adsorption equilibrium judgment are set as the equilibrium pressure allowable value P _ka that sets the allowable range of pressure change for the relative vapor pressure equilibrium judgment, the equilibrium weight allowable value W _ka that sets the allowable range of weight change, and the allowable time range. _Is the equilibrium stabilization time T _ka .

Next, the control for each sequence will be described based on FIGS. 5b to 5h.

(Drying sequence) By inputting the drying start key, the solenoid valves G2 and G3 are opened and the solenoid valve G1 is closed to close the vacuum container 10, the gas adsorption chamber 11 and the gas reservoir.
The inside of 23 is kept under a reduced pressure of 10 ^-3 mmHg and the measurement of the drying time is started.

Then, the drying time count value T _ki indicating the elapsed time becomes larger than the sum of the weight stabilization time T _da and the data sampling time (N _dat · T _da ), and T _ki ＞ (T _da + N _dat · T _dat ) is satisfied. Then, the judgment of weight balance is started.

FIG. 7 is a diagram for explaining the change of the sample weight and the judgment of the weight balance in the drying process of the example. The judgment of the weight balance is made by the present average sample weight W _ave0 and the weight stabilization time T from the present.
The average sample weight W _ave1 before _da is calculated respectively, and the difference (absolute value) between these current and past average sample weights W _ave0 and W _ave1 becomes smaller than the allowable weight W _da , and | W _ave0 −W _ave1 | Until <W _da is satisfied, calculation of each average sample weight W _ave0 and W _ave1 and determination of this condition are performed. In the calculation of the current and past average sample weights W _ave0 and W _ave1 , the past sampling data number N _dat pieces of data are read from the memory from the points of interest before and after the present and weight stabilization time T _da , respectively. The average is calculated based on the N _dat data.

As described above, when the conditions are satisfied, it is determined that the dry weight has reached equilibrium, and the average weight W _ave0 at that time is _set as the dry weight W _c, and the solenoid valves G1, G2 and G3 are closed. Finish the drying sequence.

In this way, since the equilibrium state can be detected immediately after reaching the weight equilibrium, the time required for the drying process is shortened as compared with the conventional one described with reference to FIG.

(Adsorption sequence) The adsorption sequence is performed from the set relative vapor pressures in ascending order of set value, for example, if P _s1 <P _s2 <P _s3 <..., P _s1 , P _s2 , P _s3 , ... Set the relative vapor pressure P _s in order.

And a degassing sequence for degassing the dissolved air in the solvent,
The relative vapor pressure P in the vacuum vessel is controlled within _a permissible range determined by the set relative vapor pressure P _s and the set pressure permissible value P _a , and the equilibrium between the relative vapor pressure and the weight is determined. Each process of the equilibrium data measurement sequence for measuring the equilibrium data is sequentially performed for the selected set relative vapor pressure, and the measurement of the adsorption isotherm is completed.

(Deaeration sequence) When the deaeration sequence starts, the deaeration count value N
While updating _ei , the solenoid valve is opened and closed to degas only N _e times.

At the time of degassing each time, the solenoid valves G1 and G2 are closed, the solenoid valve G3 is opened for the gas reservoir exhaust time T _eg to exhaust the gas in the gas reservoir 23, and then the solenoid valves G2 and G3 are closed and the solenoid is closed. Open the valve G1 from the liquid reservoir 22 to the gas reservoir 23 by opening the liquid reservoir degassing time T _e1.
Controlled to degas.

Then, when the processing of the upper air is completed, the solenoid valves G1 and G2 are closed and the solenoid valve G3 is opened for the gas reservoir exhaust time T _eg and the gas reservoir 2 is closed.
3 is exhausted, each solenoid valve G1, G2, G3 is closed and the degassing sequence is completed.

(Control sequence to set pressure) In the control sequence to set pressure, the set pressure allowable value P _a and the allowable pressure stable time T _a are selected, and the solvent vapor is introduced into the vacuum container 10 for each selected value. The vapor introduction sequence and the exhaust sequence for performing the exhaust when the relative vapor pressure becomes higher than a predetermined value are performed for each set pressure allowable value P _a .

FIG. 6 is a diagram showing an example of changes with time in relative vapor pressure and sample weight during the control sequence for the set pressure and during the measurement sequence of equilibrium data described later.

First, the relative vapor pressure P in the vacuum vessel 10 is set relative vapor pressure P _s.
And the set pressure allowable value P _a difference (lower limit of allowable pressure P _s −P _a ), that is, when P <(P _s −P _a ), P> P _s is set by the steam introduction sequence. The solvent vapor is introduced.

Even if the relative vapor pressure P in the vacuum container 10 is set to P> P _s by the vapor introduction sequence, when the relative vapor pressure P is lowered because the solvent vapor is adsorbed by the sample S, the time elapses. P <P _s , but even if the elapsed time after P <P _s exceeds the allowable pressure outside correction waiting time T _w , P <
If not a P _s, forced exhaust is performed such that P <P _s by the exhaust sequence. In addition, the elapsed time after P <P _s is the value outside the set pressure correction waiting time count value.
_Timed by updating T _wi .

The elapsed time from when the relative vapor pressure P in the vacuum container 10 becomes lower than the set relative vapor pressure P _s is measured by updating the allowable pressure stabilization time count value T _ai , and this elapsed time stabilizes within the allowable pressure. If the relative vapor pressure P is lower than the allowable pressure limit P _s -P _a while not exceeding the time T _a, the introduction of solvent vapor is carried out by steam introduction sequence (of FIG. 6 a
point).

In addition, the relative vapor pressure P in the vacuum vessel 10 is set relative vapor pressure P _s
Acceptable i.e. when is between pressure limit P _s -P _a, when the elapsed time when the relative vapor pressure P is a relative vapor pressure of the allowable pressure internal exceeds the allowable pressure internal stabilization time T _a and the permissible its set pressure the value P _a and the allowable pressure internal control over stabilization time T _a finished (in FIG. 6 B
Point), the following control for the set pressure allowable value P _a and the allowable pressure stable time T _a is performed in the same manner as above.

When the control for the set last set pressure tolerance P _a permissible pressure internal stabilization time T _a is completed, the control sequence to the set pressure is completed (the six view point C).

(Steam introduction sequence) steam introduction sequence, when the relative vapor pressure P within the vacuum vessel 10 as described above is lower than the set relative vapor pressure P _s, that is, the introduction of solvent vapor when P <P _s.

The difference P _s between the set relative vapor pressure P _s and the relative vapor pressure P in the vacuum container 10
When P is higher than the pressure control range P _sa , that is, (P _s −
When P)> P _sa , open solenoid valves G1 and G2 and open solenoid valve G3.
Closed and introduced solvent vapor (hereinafter, liquid reservoir 22, gas reservoir 23
In addition, the introduction performed by opening between the vacuum containers 10 is called collective introduction. ).

When the pressure difference P _s -P is lower than the pressure control range P _sa , that is, when (P _s -P) <P _sa , the solenoid valves G2 and G3 are closed and the solenoid valve G1 is closed for the gas reservoir introduction time T _s1. Open and collect 2
Introduce solvent vapor from 2 to gas reservoir 23, and further solenoid valve G1,
While G3 is closed, the solenoid valve G2 is opened for the vacuum container introduction time T _s2 to introduce solvent vapor from the gas reservoir 23 to the vacuum container 10 (hereinafter, introduced from the liquid reservoir 22 to the gas reservoir 23 and then from the gas reservoir 23 to the vacuum container). The method of introducing to 10 is called split introduction.) After that, the solenoid valves G1, G2, G3 are closed, and after the pressure measurement waiting time T _{sp has} elapsed, the set relative vapor pressure P _s and the relative vapor pressure P are compared and judged.

Further, the pressure difference P _s -P is lower than the pressure control range P _sa ,
Moreover, even if the above-mentioned split introduction is repeated N _s times, P>
When P _s is not satisfied, the solenoid valves G1 and G2 are opened and the solenoid valve G3 is closed to introduce the solvent vapor (collective introduction).

Then, when the relative vapor pressure P becomes higher than the set relative vapor pressure P _s , the vapor introduction sequence is ended.

FIG. 11 is a diagram showing an example of the relative vapor pressure and the time change when the batch introduction and the split introduction are performed, and the line l1 in the figure is shown.
Shows the case of batch introduction and l2 shows the case of divided introduction. As can be seen from this figure, the relative vapor pressure in the case of batch introduction becomes sharply higher than that in the case of split introduction, and in the case of split introduction, it rises almost in proportion to time.

Therefore, set relative vapor pressure P _s and vacuum vessel as above.
When the difference P _s -P of the relative vapor pressures P in 10 is high, it is possible to reach a predetermined vapor pressure quickly by performing batch introduction, and conversely, when the pressure difference is small, by performing split introduction, Highly precise control can be performed.

That is, the pressure control range P _sa is set as a guide for switching between the batch introduction and the split introduction.
As a result, highly accurate control can be performed in a short time.

(Exhaust Sequence) In the exhaust sequence, P <P _s even if the elapsed time after P> P _s as described above passes the allowable out-of-pressure correction waiting time T _w.
If not, it is done.

The difference P between the relative vapor pressure P in the vacuum container 10 and the set relative vapor pressure P _s
When -P _s is higher than the pressure control range _Poa , that is, (P-P
_s )> _Po a When solenoid valves G2 and G3 are opened and solenoid valve G1
Close and exhaust.

When the pressure difference P-P _s is less than the pressure control range P _oa, namely, (P-P _s) <only gas reservoir evacuation time T _o3 solenoid valve G3 closes the solenoid valve G1, G2 when the P _oa The gas reservoir 23 is opened to exhaust the gas, and the solenoid valves G1 and G3 are closed, and the solenoid valve G2 is opened for the vacuum container exhaust time _To2 to exhaust gas from the vacuum container 10 to the gas reservoir 23. After that, the solenoid valves G1, G2,
After G3 is closed and the pressure measurement waiting time T _{sp has} elapsed, the set relative vapor pressure P _s and the relative vapor pressure P are compared and judged.

Further, the pressure difference P-P _s is lower than the pressure control range P _oa,
And, if even if the exhaust emissions and the vacuum chamber 10 of the gas reservoir 23 exhaust repetition number N _o times does not satisfy P <P _s performs exhaust closes the solenoid valve G1 opens the solenoid valve G2, G3 .

Then, when the relative vapor pressure P becomes lower than the set relative vapor pressure P _s , the exhaust gas introduction sequence is ended.

Even in the case of this exhaust sequence, for the same reason as in the case of the batch introduction and the split introduction described with reference to FIG. 10, it is possible to shorten the time by selecting the exhaust method based on the set pressure control range _Poa. It enables highly accurate control.

(Equilibrium Data Measurement Sequence) When the equilibrium data measurement sequence is performed (after the line C in FIG. 6), the control sequence to the set pressure is completed by the vapor introduction sequence and the exhaust sequence, As shown in FIG. 6, the relative vapor pressure P in the vacuum container 10 is in a substantially equilibrium state.

When the control sequence to the set pressure is completed and the equilibrium data measurement sequence is entered, the elapsed time is counted by updating the elapsed time count value T _ki , and the last allowable stable pressure T within the control sequence to the set pressure is set. _a and elapsed time T
_When the sum with _ki becomes larger due to the sum of the equilibrium stabilization time T _ka and the data sampling time (N _dat · T _dat ), that is, (T _a + T _ki )> (T _ka + N _dat · T _dat ). When satisfied, the relative vapor pressure equilibrium determination begins.

Equilibrium of relative vapor pressure is judged by the current average relative vapor pressure P
_ave0 and the average relative vapor pressure P from the present to the equilibrium stabilization time T _ka
ave1 is calculated respectively, and the difference (absolute value) between these current and past average relative vapor pressures P _ave0 and P _ave1 is calculated as the equilibrium pressure allowable value P _ka.
Until it becomes smaller and | P _ave0 −P _ave1 | <P _ka is satisfied, calculation of each average relative vapor pressure P _ave0 , P _ave1 and determination of this condition are performed.

As described above, when the conditions are satisfied, it is determined that the relative vapor pressure in the vacuum container 10 has reached equilibrium, and the weight equilibrium determination is started.

Determination of the weight balance, the current average sample weight W _Ave0 equilibrium stabilization time T _ka previous average sample weight W _ave1 calculated, this average sample weight W _Ave0, difference W _ave1 (absolute value) is the equilibrium weight tolerance W _ka
Each average sample weight W _ave0 , W _ave1 is calculated and determined until it becomes smaller and | W _ave0 −W _ave1 | <W _ka is satisfied.

Then, when the conditions are satisfied, the equilibrium judgment is ended, the current average temperature t _ave is calculated, and this average temperature is calculated.
t _ave , the current average sample weight W _ave0 and the current average relative vapor pressure P _ave0 are determined as the temperature T _k , the equilibrium weight W _k and the equilibrium relative vapor pressure P _k during the adsorption equilibrium measurement, and the equilibrium data is measured. End the sequence.

The calculation of current and historical average relative vapor pressure P _Ave0, P _ave1 average sample weight W _Ave0, W _ave1, like the average sample weight W _Ave0, W _ave1 in the drying sequence, past sampling from each attention point The number of data is calculated based on each N _dat data.

Wherein as described for the adsorption sequence and successively the sequence processing is performed for a plurality of setting a relative vapor pressure that is set, the average relative vapor pressure P _k of each set relative vapor圧近near the temperature T _k at adsorption equilibrium measuring Then, the equilibrium weight W _k is obtained, and the adsorption isotherm is obtained based on the above equations (1) and (2).

[Invention and effect]

As described above, according to the present invention, in the adsorption equilibrium measurement device, the control of solvent vapor introduction is stopped when the relative vapor pressure in the airtight container is maintained within the preset allowable range for a preset period of time. After that, the relative vapor pressure was made to be in a substantially stable state when the relative vapor pressure equilibrium and the weight equilibrium were determined thereafter, so the equilibrium is disturbed by the change in the relative vapor pressure when measuring the equilibrium data. Not only can accurate data be obtained, but the measurement time can be shortened.

When drying the sample, if the change in the sample weight within a preset time period is within the preset allowable amount, the equilibrium judgment is sequentially performed for each sampling synchronization. Since the weight balance is detected immediately when the predetermined weight balance condition is satisfied, the time required for drying can be minimized and the measurement time can be shortened.

[Brief description of drawings]

FIG. 1 is a block diagram of an adsorption equilibrium measuring device of the present invention, FIG. 2 is a diagram showing an embodiment of an adsorption equilibrium measuring device of the present invention, and FIG. 3 is a diagram showing details of measuring means in the embodiment. FIG. 4 is a diagram showing a measuring circuit in the embodiment, FIGS. 5a to 5h are flow charts showing control in the embodiment, and FIG. 6 is a diagram showing an example of changes with time in relative vapor pressure and sample weight in the embodiment. FIG. 7 is a diagram for explaining changes in sample weight and determination of weight balance in the drying process of the embodiment, FIG. 8 is a view for showing another embodiment of the adsorption equilibrium measuring device according to the present invention, and FIG. 9 is conventional. Fig. 10 is a diagram showing changes in relative vapor pressure and sample weight over time under the control of Fig. 10, Fig. 10 is a diagram for explaining changes in sample weight and judgment of weight balance in the conventional drying process, and Fig. 11 shows batch introduction and divided introduction. FIG. 6 is a diagram showing an example of a time-dependent change in relative vapor pressure when . 10 ... vacuum container, 11 ... gas adsorption chamber, 14 ... electronic measuring instrument, 15 ... measurement control section, 16 ... pressure sensor, 18 ... temperature sensor.

Claims (4)

[Claims] 1. An airtight container containing a sample is evacuated to dry the sample until the weight balance of the sample is detected, and a solvent vapor is introduced into the airtight container to adsorb the solvent vapor by the sample. In the adsorption equilibrium measurement method for measuring the adsorption isotherm by detecting the equilibrium state of the process, after the sample is dried, the solvent in the airtight container until the relative vapor pressure in the airtight container becomes equal to or higher than the preset relative vapor pressure. The vapor is introduced, and the introduction of the solvent vapor is repeated until the relative vapor pressure in the airtight container is maintained within a preset allowable range for a preset period of time. Adsorption equilibrium characterized by determining the equilibrium of the relative vapor pressure in the container and determining the weight equilibrium based on the preset equilibrium weight tolerance and the equilibrium weight stabilization time to measure the adsorption isotherm. Measuring method. 2. An airtight container containing a sample is evacuated to dry the sample until the weight balance of the sample is detected, and a solvent vapor is introduced into the airtight container to adsorb the solvent vapor by the sample. In an adsorption equilibrium measuring method for detecting an adsorption isotherm by detecting an equilibrium state of a process, when the sample is dried, a change in sample weight during a preset time period is within a preset allowable amount. A method for measuring adsorption equilibrium, characterized in that the weight equilibrium is detected by making a determination that equilibrium has occurred in a preset fixed cycle. 3. An apparatus for measuring an adsorption isotherm by the adsorption equilibrium measuring method according to claim 1, wherein the pressure detecting unit detects a pressure in the airtight container, and the weight detecting unit detects a weight of the sample. A data sampling means for sampling the pressure data and the weight data detected by the pressure detecting means and the weight detecting means at a preset constant cycle; and the detection data obtained by the data sampling means corresponding to the sampling order. For each of the pressure data and the weight data stored in the storage means, the old and new detection data corresponding to a preset fixed time difference is read out, and the difference between the new and old detection data is set in advance. After the sample is dried, the detection data of the pressure detection means is set in advance. The solvent vapor is introduced until it becomes equal to or more than the specified value, and then the introduction and stop of the solvent vapor are controlled based on the comparison result of the comparison means, and then the relative vapor is calculated based on the comparison result of the pressure data of the comparison means. An adsorption equilibrium measurement device comprising: a control unit that determines the pressure equilibrium and determines the weight equilibrium based on the comparison result of the weight data of the comparison unit. 4. The air-tight container is evacuated by the control means, the weight balance is judged based on a comparison result of the weight data of the comparison means, and when the weight balance is detected by this judgment, the air-tight container is evacuated. The adsorption equilibrium measuring device according to claim 3, characterized in that