A device and method for accurately measuring the open adsorption of water vapor by an adsorbent

Abstract

The present invention discloses a device and method for accurately measuring the open adsorption of water vapor by an adsorbent, the device comprising: an adsorbent desorption system for desorbing the adsorbent; a condensation system connected to the adsorbent desorption system for condensing the gas desorbed by the adsorbent; a condensation water measurement system connected to the condensation system for measuring the amount of condensed water; and a moisture content measurement system connected to the condensation water measurement system for measuring the water content of uncondensed gas. The present invention can accurately measure the precise value of specific water vapor in various gases adsorbed by the adsorbent, and separately measure and calculate the amount of desorbed condensed water and the water vapor content in the uncondensed gas by a separate measurement method, with the advantages of accurate experimental results, simple operation, good stability, and a wide range of applications.

Description

Technical Field

[0001] The invention relates to the technical field of measuring adsorption amount, and in particular to a device and method for accurately measuring open adsorption of water vapor by an adsorbent. Background Art

[0002] Currently, there are three main ways to obtain water in water-scarce areas: fresh water transportation, seawater desalination, and air-to-water production.

[0003] There are two main methods of water production from air: condensation water production and adsorption water production. Adsorption water production has the following advantages: under conditions of extremely low relative humidity, condensation water production has a low dew point temperature and is difficult to produce water. Adsorption water production can utilize the adsorption characteristics of the adsorbent to complete water production.

[0004] At present, there are mainly two methods for measuring the adsorption amount of adsorbents: weighing method and condensation method.

[0005] The weighing method is a method of measuring weight change, which cannot accurately measure the water content of the adsorbate adsorbed and desorbed by the adsorbent. The reason is that the adsorbent adsorbs water vapor under open adsorption conditions, that is, in the atmospheric environment. Due to the structural characteristics of the adsorbent, its adsorption usually has a relatively wide range of adsorption characteristics, and it will adsorb a variety of gases. The wide adsorption of the adsorbent is also reported in the following documents. The nitrogen adsorption capacity of the zeolite 13X adsorbent mentioned in the authorization publication number CN102580669 "A method for preparing a zeolite adsorbent for air separation oxygen production" is 5.60ml / g, and the oxygen adsorption capacity is 2.33ml / g. Therefore, the amount of water vapor adsorbed by the adsorbent measured by the weighing method is larger than the actual adsorption capacity, and the difference is the other non-condensable gases adsorbed by the adsorbent.

[0006] The condensation method is to condense the gas desorbed by the adsorbent, and then test the amount of condensed water to obtain the water vapor adsorption amount of the adsorbent. This method has the problem that some water vapor overflows with the non-condensable gas, causing inaccurate testing. The amount of water vapor adsorbed by the adsorbent measured by the condensation method is smaller than the actual adsorption amount, and the difference is the part of the water vapor overflowing with the non-condensable gas. There is currently a lack of accurate testing methods for the open adsorption performance of adsorbents.

[0007] The patents disclosed for testing the adsorption performance of adsorbents are: Authorization publication number CN202119741 "A device for testing adsorption performance" is mainly used for closed adsorption, and cannot meet the performance testing requirements of adsorbents in solar adsorption water-making pipes in an open state. Authorization publication number CN105136922 "A dynamic detection device for adsorbent performance" does not have a system for collecting desorbed adsorbates, and can only test adsorbates with lower boiling points. Authorization publication number CN104849170 "A system and method for testing the open adsorption performance of solar adsorption water-making pipes" uses the weighing method to measure, and can only measure the reduction in adsorbent. The reduction also includes adsorbed oxygen, nitrogen, etc., so this measurement method has errors. Summary of the invention

[0008] The object of the present invention is to provide a device and method for accurately measuring the open adsorption of water vapor by an adsorbent, so as to accurately measure the condensed adsorbate and the uncondensed water vapor.

[0009] To achieve the above object, the present invention provides a device for accurately measuring the open adsorption of water vapor by an adsorbent, comprising:

[0010] an adsorbent desorption system for desorbing the adsorbent;

[0011] A condensation system connected to the adsorbent desorption system and used for condensing the gas desorbed from the adsorbent;

[0012] A condensate water measuring system connected to the condensation system for measuring the amount of condensate water;

[0013] A moisture content measurement system connected to a condensed water measurement system to measure the moisture content of uncondensed gas.

[0014] The above-mentioned device for accurately measuring the open adsorption of water vapor by the adsorbent, wherein the adsorbent desorption system comprises: a temperature control box; a stainless steel reactor arranged in the temperature control box and connected to the condensation system pipeline for placing the adsorbent; an electric heater arranged in the temperature control box; a temperature probe arranged in the temperature control box, and a PID controller respectively connected to the electric heater and the temperature probe and used to control the power of the electric heater to reach the adsorbent desorption temperature in the temperature control box.

[0015] The above-mentioned device for accurately measuring the open adsorption of water vapor by an adsorbent, wherein the adsorbent desorption system also includes an L-shaped temperature measuring sleeve arranged in a stainless steel reactor; the end of the L-shaped temperature measuring sleeve is located at the center of the reactor, and is provided with a first thermocouple for measuring the temperature at the center of the adsorbent; the corner of the L-shaped temperature measuring sleeve is located at the edge of the reactor, and is provided with a second thermocouple for measuring the temperature at the edge of the adsorbent; the first thermocouple and the second thermocouple are respectively connected to a data acquisition instrument; and the data acquisition instrument is connected to a computer for displaying collected data.

[0016] In the above-mentioned device for accurately measuring the open adsorption of water vapor by an adsorbent, the stainless steel reactor comprises a reactor body and an upper cover sealedly connected to the reactor body.

[0017] In the above-mentioned device for accurately measuring the open adsorption of water vapor by an adsorbent, the upper cover and the reactor body are sealed by a flange and a sealing ring.

[0018] The above-mentioned device for accurately measuring the open adsorption of water vapor by the adsorbent, wherein the condensation system includes: a condenser and a chiller; the cold side inlet and cold side outlet of the condenser are connected to the chiller; the hot side inlet of the condenser is connected to the adsorbent desorption system; the hot side outlet of the condenser is connected to the condensate measurement system.

[0019] In the above-mentioned device for accurately measuring the open adsorption of water vapor by an adsorbent, a temperature tester is provided between the chiller and the cold side inlet of the condenser.

[0020] The above-mentioned device for accurately measuring the open adsorption of water vapor by an adsorbent, wherein the condensed water measuring system comprises: a measuring cylinder for measuring the volume of condensed water and a sealing rubber plug for sealing the measuring cylinder; the measuring cylinder is respectively connected to the condensation system and the moisture content measuring system through pipelines.

[0021] The above-mentioned device for accurately measuring the open adsorption of water vapor by an adsorbent, wherein the moisture content measurement system includes: a gas test container for measuring the volume of uncondensed gas and a movable piston arranged in the gas test container; the movable piston divides the gas test container into a first cavity and a second cavity; the first cavity is connected to the pipeline of the condensation water measurement system, and is provided with a temperature and humidity measuring instrument for measuring the temperature and humidity in the first cavity and a pressure testing instrument for measuring the pressure in the first cavity.

[0022] The present invention also provides a method for accurately measuring the open adsorption of water vapor by an adsorbent, which is implemented based on the above-mentioned device for accurately measuring the open adsorption of water vapor by an adsorbent, and comprises the following steps:

[0023] Step 1: placing the adsorbed adsorbent in an adsorbent desorption system for temperature-raising desorption;

[0024] Step 2: The desorbed gas is condensed by the condensation system and then enters the condensate measurement system;

[0025] Step 3: Measure the amount of condensed water through the condensed water measurement system, and the uncondensed gas overflows to the moisture content measurement system;

[0026] Step 4: Measuring the moisture content of the uncondensed gas by using a moisture content measurement system;

[0027] Step 5: Add the condensed water content and the uncondensed gas water content to obtain the amount of water vapor adsorbed by the adsorbent in the open state.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The operation is simple. It only requires placing the adsorbed adsorbent into a stainless steel reactor and heating it for desorption. There are no extra steps.

[0030] (2) The experimental results are relatively accurate. The device provided by the present invention can not only measure the amount of condensed water, but also measure the amount of water contained in the uncondensed gas. Compared with the traditional weighing method and condensation method, its measurement results are more accurate.

[0031] (3) It has a wide range of applications and the desorption temperature can be adjusted according to different adsorbents. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the structure of the device for accurately measuring the open adsorption of water vapor by an adsorbent according to the present invention;

[0033] Figure 2 It is a schematic diagram of the physical model of the L-shaped temperature measuring sleeve in the present invention. DETAILED DESCRIPTION

[0034] The present invention will be further described below through specific embodiments in conjunction with the accompanying drawings. These embodiments are only used to illustrate the present invention and are not intended to limit the protection scope of the present invention.

[0035] like Figure 1 As shown, the present invention provides a device for accurately measuring the open adsorption of water vapor by an adsorbent, which comprises:

[0036] an adsorbent desorption system for desorbing the adsorbent;

[0037] A condensation system connected to the adsorbent desorption system and used for condensing the gas desorbed from the adsorbent;

[0038] A condensate water measuring system connected to the condensation system for measuring the amount of condensate water;

[0039] A moisture content measurement system connected to a condensation water measurement system to measure the moisture content of uncondensed gas (non-condensable gas and part of water vapor).

[0040] The adsorbent desorption system comprises: a temperature control box 10; a stainless steel reactor 11 disposed in the temperature control box 10 and connected to the condensation system pipeline for placing the adsorbent; an electric heater 12 disposed in the temperature control box 10; a temperature probe 13 disposed in the temperature control box 10, and a PID controller 14 respectively connected to the electric heater 12 and the temperature probe 13 and used to control the power of the electric heater 12 so that the temperature control box 10 reaches the adsorbent desorption temperature.

[0041] The adsorbent desorption system also includes an L-shaped temperature measuring sleeve 15 arranged in the stainless steel reactor 11; the end of the L-shaped temperature measuring sleeve 15 is located at the center of the reactor, and is provided with a first thermocouple for measuring the temperature at the center of the adsorbent; the corner of the L-shaped temperature measuring sleeve 15 is located at the edge of the reactor, and is provided with a second thermocouple for measuring the temperature at the edge of the adsorbent; the first thermocouple and the second thermocouple (T-type thermocouple can be selected) are respectively connected to a data acquisition instrument 16; the data acquisition instrument 16 is connected to a computer 17 for displaying collected data. Optionally, the L-shaped temperature measuring sleeve 15 is arranged in the stainless steel reactor 11 after passing through the top of the stainless steel reactor 11, and the measuring height can be adjusted and the interface with the stainless steel reactor 11 is sealed with interference silicone. Further, the stainless steel reactor 11 includes a reactor body and an upper cover sealed with the reactor body. Further, the upper cover and the reactor body are sealed by a flange 18 and a sealing ring 19 (polytetrafluoroethylene sealing ring 19 can be selected).

[0042] The condensation system includes: a condenser 20 and a chiller 21; the cold side inlet and the cold side outlet of the condenser 20 are connected to the chiller 21; the hot side inlet of the condenser 20 is connected to the adsorbent desorption system; the hot side outlet of the condenser 20 is connected to the condensate measurement system. Furthermore, a temperature tester 22 is provided between the chiller 21 and the cold side inlet of the condenser 20.

[0043] The condensation water measuring system comprises: a measuring cylinder 30 for measuring the volume of condensation water and a sealing rubber plug 31 for sealing the measuring cylinder 30; the measuring cylinder 30 is respectively connected to the condensation system and the moisture content measuring system through pipelines.

[0044] The moisture content measurement system includes: a gas test container 40 for measuring the volume of uncondensed gas and a movable piston 41 arranged in the gas test container 40; the movable piston 41 divides the gas test container 40 into a first cavity 42 and a second cavity 43; the first cavity 42 is connected to the condensation water measurement system pipeline, and is provided with a temperature and humidity measuring instrument 44 for measuring the temperature and humidity in the first cavity 42 and a pressure tester 45 for measuring the pressure in the first cavity 42.

[0045] like Figure 2 As shown, when selecting an L-type temperature measuring sleeve:

[0046] First, a physical model of a one-dimensional steady-state straight rib with equal cross-section is established to establish the equation:

[0047]

[0048] Where t H is the internal temperature of the casing, t f is the external temperature of the casing, t0 is the temperature of the casing root (corner), H is the rib height, and ch is the hyperbolic cosine function.

[0049]

[0050] Where h is the surface heat transfer coefficient, P is the heat exchange perimeter, λ is the thermal conductivity, and A is the cross-sectional area of ​​the casing.

[0051] Secondly, according to the equation, it can be concluded that choosing a long and thin sleeve made of stainless steel with a low thermal conductivity can reduce measurement errors.

[0052] The present invention also provides a method for accurately measuring the open adsorption of water vapor by an adsorbent, which is implemented based on the above-mentioned device for accurately measuring the open adsorption of water vapor by an adsorbent, and comprises the following steps:

[0053] Step 1: placing the adsorbed adsorbent in an adsorbent desorption system for temperature-raising desorption;

[0054] Step 2: The desorbed gas is condensed by the condensation system and then enters the condensate measurement system;

[0055] Step 3: Measure the amount of condensed water through the condensed water measurement system, and the uncondensed gas overflows to the moisture content measurement system;

[0056] Step 4: Measuring the moisture content of the uncondensed gas by using a moisture content measurement system;

[0057] Step 5: Add the condensed water content and the uncondensed gas water content to obtain the amount of water vapor adsorbed by the adsorbent in the open state.

[0058] When the device provided by the present invention is used, the air tightness of the entire device should be tested first. On the premise of ensuring good air tightness, the adsorbed adsorbent is placed in the stainless steel reactor 11, and then the corresponding measurement experiment is carried out. The specific process is described as follows.

[0059] Desorption experiment process:

[0060] First, adjust the temperature measuring sleeve to the best temperature measuring position. The stainless steel reactor 11 is sealed with a polytetrafluoroethylene sealing ring 19 and fixed with a flange 18.

[0061] Furthermore, the electric heater 12 is adjusted by the PID controller 14 so that the temperature in the temperature control box 10 reaches the adsorbent desorption temperature, and the adsorbent temperature change is detected by the data acquisition instrument 16 .

[0062] Condensation and condensation water measurement experimental process:

[0063] When the adsorbent desorption system is turned on, the condensation system is turned on at the same time. Assuming the ambient temperature is 20°C, the temperature and humidity tester measures results accurately within the range of 40%-60%.

[0064] First, the chiller 21 is turned on.

[0065] Secondly, by reading the temperature tester 22, the water supply temperature of the chiller 21 is manually adjusted to achieve condensation in different temperature ranges to ensure that the air humidity is within a relatively accurate measurement range. In this embodiment, according to the wet air enthalpy psychrometric chart, the use of 7°C-12°C condensation can achieve a relative humidity of 40%-60% after condensation, to ensure that the air humidity is within a relatively accurate measurement range.

[0066] Further, the cooling water temperature is adjusted to 7° C.-12° C. to condense the desorbed gas. The amount of condensed water is measured by a measuring cylinder 30 .

[0067] Uncondensed gas water content measurement process:

[0068] First, the gas pressure value in the first cavity 42 is fed back through the pressure tester 45 , and the first cavity 42 is maintained at the standard atmospheric pressure by pushing the movable piston 41 .

[0069] Secondly, the gas volume in the first cavity 42 before and after desorption is measured by using a gas testing container 40 with a volume scale thereon.

[0070] Furthermore, the temperature and humidity of the gas in the first cavity 42 before and after desorption are measured by a temperature and humidity measuring instrument 44 .

[0071] Calculation process of the amount of water vapor adsorbed by the adsorbent in open form:

[0072] The amount of condensed water is directly observed in the measuring cylinder.

[0073] Calculation of water content in uncondensed gas:

[0074] First, the data measured by the temperature and humidity measuring instrument is checked on the wet air enthalpy and humidity diagram to obtain the saturated water vapor partial pressure at that temperature.

[0075] Secondly, the water vapor partial pressure at this temperature and humidity can be calculated as:

[0076] Where P V is the water vapor partial pressure of moist air at that temperature, P a ; is the relative humidity of wet air; P S is the water vapor partial pressure of saturated moist air at this temperature, P a ;

[0077] Furthermore, the absolute humidity of water vapor is obtained from the ideal gas state equation:

[0078] In the formula, ρ s is the absolute humidity of water vapor at this temperature, kg / m 3 ;P V is the partial pressure of water vapor at this temperature, P a ; R V is the gas constant of water vapor, R V =461J / (kg*k); T is the thermodynamic temperature, K;

[0079] Furthermore, the mass of water vapor in the uncondensed gas

[0080] In the formula, is the absolute humidity of water vapor after desorption, kg / m 3 ; V2 is the volume of the container after desorption, m 3 ; is the absolute humidity of water vapor before desorption kg / m 3 ; V1 is the volume of the container before desorption, m 3 .

[0081] Finally, the amount of water vapor adsorbed by the adsorbent in the open state (the amount of adsorbate desorbed) is equal to the amount of condensed water plus the water vapor content in the uncondensed gas.

[0082] In summary, the present invention can accurately measure the precise value of specific water vapor in various gases adsorbed by the adsorbent, and measure and calculate the amount of desorbed condensed water and the water vapor content in the uncondensed gas by a separate measurement method, respectively. It has the advantages of accurate experimental results, simple operation, good stability, and a wide range of applicability.

[0083] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A device for accurately measuring the open adsorption of water vapor by an adsorbent, characterized in that: It contains: an adsorbent desorption system for desorbing the adsorbent; A condensation system connected to the adsorbent desorption system and used for condensing the gas desorbed from the adsorbent; A condensate water measuring system connected to the condensation system for measuring the amount of condensate water; A moisture content measurement system connected to the condensed water measurement system for measuring the moisture content of uncondensed gas; The adsorbent desorption system comprises: a temperature control box; a stainless steel reactor arranged in the temperature control box and connected to the condensation system pipeline for placing the adsorbent; an electric heater arranged in the temperature control box; a temperature probe arranged in the temperature control box, and a PID controller respectively connected to the electric heater and the temperature probe and used to control the power of the electric heater so that the adsorbent desorption temperature in the temperature control box is reached; The adsorbent desorption system further comprises an L-shaped temperature measuring sleeve arranged in a stainless steel reactor; the end of the L-shaped temperature measuring sleeve is located at the center of the reactor and is provided with a first thermocouple for measuring the temperature at the center of the adsorbent; the corner of the L-shaped temperature measuring sleeve is located at the edge of the reactor and is provided with a second thermocouple for measuring the temperature at the edge of the adsorbent; the first thermocouple and the second thermocouple are respectively connected to a data acquisition instrument; the data acquisition instrument is connected to a computer for displaying the collected data; The condensation system comprises: a condenser and a chiller; the cold side inlet and the cold side outlet of the condenser are connected to the chiller; the hot side inlet of the condenser is connected to the adsorbent desorption system; and the hot side outlet of the condenser is connected to the condensate measurement system.

2. The device for accurately measuring the open adsorption of water vapor by an adsorbent as claimed in claim 1, characterized in that: The stainless steel reactor comprises a reactor body and an upper cover which is sealed and connected to the reactor body.

3. The device for accurately measuring the open adsorption of water vapor by an adsorbent as claimed in claim 2, characterized in that: The upper cover and the reactor body are sealed by a flange and a sealing ring.

4. The device for accurately measuring the open adsorption of water vapor by an adsorbent as claimed in claim 1, characterized in that: A temperature tester is arranged between the chiller and the cold side inlet of the condenser.

5. The device for accurately measuring the open adsorption of water vapor by an adsorbent as claimed in claim 1, characterized in that: The condensation water measuring system comprises: a measuring cylinder for measuring the volume of condensation water and a sealing rubber plug for sealing the measuring cylinder; the measuring cylinder is respectively connected with the condensation system and the moisture content measuring system through pipelines.

6. The device for accurately measuring the open adsorption of water vapor by an adsorbent as claimed in claim 1, characterized in that: The moisture content measurement system includes: a gas test container for measuring the volume of uncondensed gas and a movable piston arranged in the gas test container; the movable piston divides the gas test container into a first cavity and a second cavity; the first cavity is connected to the condensation water measurement system pipeline, and is provided with a temperature and humidity measuring instrument for measuring the temperature and humidity in the first cavity and a pressure tester for measuring the pressure in the first cavity.

7. A method for accurately measuring the adsorption of water vapor by an adsorbent in an open form, the method being implemented based on the device for accurately measuring the adsorption of water vapor by an adsorbent in an open form as claimed in claim 1, characterized in that: It contains the following steps: Step 1: placing the adsorbed adsorbent in an adsorbent desorption system for temperature-raising desorption; Step 2: The desorbed gas is condensed by the condensation system and then enters the condensate measurement system; Step 3: Measure the amount of condensed water through the condensed water measurement system, and the uncondensed gas overflows to the moisture content measurement system; Step 4: Measuring the moisture content of the uncondensed gas by using a moisture content measurement system; Step 5: Add the condensed water content and the uncondensed gas water content to obtain the amount of water vapor adsorbed by the adsorbent in the open state.

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