Gas chromatography column temperature control device and method

Abstract

The present invention belongs to the field of chromatography technology, and specifically relates to a gas chromatography column temperature control device and method, the temperature control device includes a box and a first heater, the first heater is fixed in the box, the box includes an upper wall, a vertical wall and a lower wall, and further includes: an annular component is fixed on the box, and a closed space surrounding the vertical wall is formed on the outside of the box, and the closed space has an inlet and an outlet; a gas supply unit provides constant temperature gas, and the outlet is connected to the inlet and the inside of the box respectively, and the box has a gas outlet; a valve is used to control whether the constant temperature gas enters the box. The present invention has the advantages of fast heating and low power consumption, and is used in gas chromatographs.

Description

Technical Field

[0001] The invention relates to the technical field of chromatography, and in particular to a gas chromatography column temperature control device and method. Background Art

[0002] There are two main applications of programmed temperature chromatography:

[0003] 1. Used to shorten the separation time of multi-component complex mixtures. Chromatographic column constant temperature technology can achieve separation, but it requires a longer chromatographic column and a separation cycle of more than 30 minutes.

[0004] 2. Used for separation of mixtures with a wide boiling point range. A typical application is the gas chromatography simulated distillation range analysis of oil products, which cannot be achieved using constant temperature chromatographic column technology.

[0005] The analysis cycle of programmed temperature chromatography includes not only the heating and separation time, but also the cooling time. Therefore, it requires fast heating and cooling, uniform temperature and good repeatability.

[0006] In order to achieve rapid heating and cooling, the following solutions are adopted in the prior art:

[0007] 1. The column box is heated by a hot air bath with heating wire and fan agitation, and cooled by fan-forced convection.

[0008] 2. The column box is heated by a hot air bath with a hot air duct and cooled by compressed air.

[0009] The above two hot air bath heating methods have the following disadvantages: the air is first heated, and then the hot air transfers the heat to the chromatographic column and the inner wall and insulation layer of the metal column box with large heat capacity by convection. The required power is high, the heating is slow, and the overall cooling of the column box limits the cooling rate.

[0010] 3. On-column heating: the heating wire is directly wound around the chromatographic column to directly heat the chromatographic column, and the fan or compressed air is used to cool it down. The disadvantages of this solution are: the process is complicated and the price is expensive. Summary of the invention

[0011] In order to solve the deficiencies in the above-mentioned prior art solutions, the present invention provides a chromatographic column temperature control device.

[0012] The objective of the present invention is achieved through the following technical solutions:

[0013] A gas chromatography column temperature control device comprises a box and a first heater, wherein the first heater is fixed in the box, and the box comprises an upper wall, a vertical wall and a lower wall; the temperature control device further comprises:

[0014] An annular component, the annular component is fixed on the box body, forming a closed space surrounding the vertical wall on the outside of the box body, and the closed space has an inlet and an outlet;

[0015] A gas supply unit, the gas supply unit provides constant temperature gas, the outlet of which is respectively connected to the inlet and the inside of the box, and the box has a gas outlet;

[0016] A valve, the valve is used to control whether the constant temperature gas enters the box;

[0017] The temperature of the isothermal gas is T air satisfy:

[0018] , , d e =(d1 2 -d2 2 ) / d2;

[0019] R=0.023(k / d e )(d e uρ / μ) 0.8 P r 0.4 , Q = πd e 2 u / 4;

[0020] ε1 is the surface emissivity of the chromatographic column surrounding the first heater, ε2 is the surface emissivity of the inner wall of the box wall, σ is the Boltzmann constant, T1 is the temperature of the chromatographic column, T2 is the temperature of the box wall, H is the internal height of the box, α is the convection heat transfer coefficient between the constant temperature gas and the wall, A1 is the inner surface area of ​​the chromatographic column, A2 is the surface area of ​​the inner wall of the wall, k, u, ρ, μ and P r are respectively the thermal conductivity, flow rate, density, viscosity and Prandtl number of the gas, d2 and d1 are respectively the inner diameter and outer diameter of the closed space, and Q is the flow rate of the constant temperature gas entering the closed space.

[0021] The purpose of the present invention is also to provide a temperature control method based on the gas chromatography column temperature control device of the present application, and the purpose of the invention is achieved through the following technical solutions.

[0022] The temperature control method of the gas chromatography column temperature control device of the present invention is specifically as follows:

[0023] When the temperature of the chromatographic column is increased, the first heater is heated according to the set power, the chromatographic column is heated by the heat radiation emitted by the first heater, and the vertical wall is heated by the heat radiation emitted by the chromatographic column;

[0024] At the same time, the valve is closed, and the constant temperature gas enters the closed space, taking away the heat of the vertical wall, and the temperature of the vertical wall decreases;

[0025] When the temperature of the chromatographic column is lowered, the first heater is turned off, the valve is opened, and the constant temperature gas enters the closed space and the inside of the box respectively and is discharged, and the temperature of the chromatographic column and the wall is lowered.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The column heats up and cools down quickly;

[0028] The first heater directly heats the chromatographic column by thermal radiation. Compared with air bath heating, it has low heating power consumption and fast heating of the chromatographic column, and has the advantages of low power consumption, high temperature and high heating rate.

[0029] The closed space is not filled with thermal insulation cotton, but a constant temperature gas is introduced to dissipate the radiant heat absorbed by the inner wall of the vertical wall in real time by forced convection heat dissipation. At the same time, when the chromatographic column is cooled, the constant temperature gas (refrigeration gas relative to the inner wall temperature) enters the interior of the box, and only the chromatographic column needs to be cooled, and the cooling is fast.

[0030] 2. Strong tolerance to the environment;

[0031] Constant temperature gas enters the closed space and acts as a heat preservation layer, ensuring the stability of the external ambient temperature of the box and having strong tolerance to ambient temperature;

[0032] 3. Low power consumption;

[0033] The relationship between the flow rate of the constant temperature gas entering the closed space and the column temperature, wall temperature and other parameters has been established, which is helpful for the precise temperature control of the column;

[0034] An accurate relationship between the heating power of the first heater and parameters such as the temperature and surface area of ​​the chromatographic column is established. According to the temperature of the chromatographic column and the relationship, the set heating power of the first heater is accurately calculated, and the energy consumption is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The disclosure of the present invention will become easier to understand with reference to the accompanying drawings. It is easy for those skilled in the art to understand that these drawings are only used to illustrate the technical solution of the present invention and are not intended to limit the scope of protection of the present invention. In the drawings:

[0036] Figure 1 It is a structural schematic diagram of the gas chromatography column temperature control device of the present invention;

[0037] Figure 2 It is a schematic cross-sectional view of the gas chromatography column temperature control device of the present invention.

[0038] In the accompanying drawings, 11-box, 12-annular component, 13-enclosed space, 21-chromatographic column, 31-first heater, 41-pressure regulating valve, 42-second heater, 43-temperature sensor, 44-control module, 51-valve. DETAILED DESCRIPTION

[0039] Figure 1-Figure 2 The following description describes optional specific embodiments of the present invention to teach those skilled in the art how to implement and reproduce the present invention. In order to teach the technical solution of the present invention, some conventional aspects have been simplified or omitted. Those skilled in the art will understand that variations or replacements derived from these specific embodiments will be within the scope of the present invention. Those skilled in the art will understand that the following features can be combined in various ways to form multiple variations of the present invention. Thus, the present invention is not limited to the following optional specific embodiments, but is only limited by the claims and their equivalents.

[0040] Example 1.

[0041] A gas chromatography column control device of this embodiment, such as Figure 1 As shown, including:

[0042] The first heater 31 is fixed in the box body 11, and the box body 11 includes an upper wall, a vertical wall and a lower wall.

[0043] The annular component 12 is fixed on the box body 11 , and a closed space 13 surrounding the vertical wall is formed on the outer side of the box body 11 , and the closed space 13 has an inlet and an outlet.

[0044] The gas supply unit provides constant temperature gas, and the outlet is connected to the inlet and the inside of the box 11 respectively. The box 11 has a gas outlet.

[0045] The valve 51 is used to control whether the constant temperature gas enters the box 11 or not.

[0046] The temperature of the isothermal gas is T air satisfy:

[0047] ; , d e =(d1 2 -d2 2 ) / d2;

[0048] R=0.023(k / d e )(d e uρ / μ) 0.8 P r 0.4 , Q = πd e 2 u / 4.

[0049] ε1 is the surface emissivity of the chromatographic column 21 surrounding the first heater 31, ε2 is the surface emissivity of the inner wall of the vertical wall of the box 11, σ is the Boltzmann constant, T1 is the temperature of the chromatographic column, T2 is the temperature of the vertical wall of the box 11, H is the internal height of the box 11, α is the convection heat transfer coefficient between the constant temperature gas and the vertical wall, A1 is the inner surface area of ​​the chromatographic column 21, A2 is the surface area of ​​the inner wall of the vertical wall, k, u, ρ, μ and P r are respectively the thermal conductivity, flow rate, density, viscosity and Prandtl number of the gas, d2 and d1 are respectively the inner diameter and outer diameter of the closed space 13, and Q is the flow rate of the constant temperature gas entering the closed space 13.

[0050] In order to obtain an accurate setting power to reduce power consumption, further, the setting power P of the first heater 31 satisfies:

[0051] ηP=ε1σT1 4 A0+ε1σT1 4 A1-ε2σT2 4 A1+c·m·B;

[0052] η is the efficiency of converting the electrical power of the first heater 31 into thermal power, A0 is the surface area of ​​the first heater 31, c and m are the specific heat capacity and mass of the chromatographic column 21 respectively, and B is the heating rate of the chromatographic column 21.

[0053] In order to improve the heating efficiency, further, as Figure 2 As shown, the spiral chromatographic column 21 is cylindrical, the pitch is 0, A1 is the inner surface area of ​​the cylinder; the first heater 31 is a light-emitting lamp; A0 is the light-emitting surface area of ​​the lamp, and the interior of the box 11 is cylindrical.

[0054] In order to provide constant temperature gas, further, the gas providing unit includes:

[0055] The first pipeline is connected to the interior of the box 11, the second pipeline is connected to the inlet, and the valve 51 is arranged on the first pipeline;

[0056] The third pipe is connected to the first pipe and the second pipe, and the second heater 42 is disposed on the third pipe.

[0057] In order to accurately control the temperature of the gas, the gas supply unit further includes:

[0058] The temperature sensor 43 is used to obtain the temperature of the gas in the second pipeline and transmit it to the control module 44. The control module 44 adjusts the parameters of the second heater 42 according to the received temperature value and the set temperature.

[0059] The temperature control method of the gas chromatography column temperature control device according to this embodiment is specifically as follows:

[0060] When the temperature of the chromatographic column 21 is increased, the first heater 31 is heated according to the set power, the chromatographic column 21 is heated by the heat radiation emitted by the first heater 31, and the vertical wall is heated by the heat radiation emitted by the chromatographic column 21;

[0061] At the same time, the valve 51 is closed, and the constant temperature gas enters the closed space 13, taking away the heat of the vertical wall, and the temperature of the vertical wall decreases;

[0062] When the temperature of the chromatographic column 21 is reduced, the first heater 31 is turned off, the valve 51 is opened, and the constant temperature gas enters the closed space 13 and the inside of the box 11 respectively, and is discharged, and the temperature of the chromatographic column 21 and the temperature of the wall are reduced.

[0063] Example 2.

[0064] An application example of the chromatographic column temperature control device and method in Example 1 of the present invention.

[0065] In this application example, Figure 1 As shown, the interior of the box 11 is cylindrical, and the vertical wall is made of mirror stainless steel. The spiral chromatographic column 21 is cylindrical, with a pitch of 0, and the inner surface area of ​​the cylinder is A1. The first heater 31 uses a cylindrical halogen lamp, and the light-emitting surface area of ​​the lamp tube is A0.

[0066] The circular annular component 12 is fixed on the outer wall of the box body 11 to form an annular closed space 13. The closed space 13 has an inlet and an outlet.

[0067] like Figure 2 As shown, the first heater 31 is arranged along the central axis of the box body 11 , and its length is the same as the height inside the box body 11 .

[0068] In the gas (air) supply unit, the first pipeline is connected to the interior of the housing 11, and the solenoid valve is arranged on the first pipeline. When the temperature of the chromatographic column 21 rises, the solenoid valve is closed, and the constant temperature gas does not enter the housing 11; when the temperature of the chromatographic column 21 drops, the solenoid valve is opened, and the constant temperature gas enters the housing 11 and is discharged. The second pipeline is connected to the inlet, and when the temperature of the chromatographic column 21 rises and drops, the constant temperature gas enters the closed space 13 through the second pipeline. The third pipeline connects the first pipeline and the second pipeline, and the pressure regulating valve 41 and the second heater 42 (using an electric heater) are arranged on the third pipeline. The temperature sensor 43 is used to obtain the gas temperature in the second pipeline and transmit it to the control module 44, and the control module 44 adjusts the parameters of the second heater 42 according to the received temperature value and the set temperature.

[0069] The chromatographic column 21 is a stainless steel micro-filled column with a length of L = 10m, an outer diameter of d = 0.16cm, and an inner diameter of 0.1cm. The bending diameter of the chromatographic column 21 is D = 8cm, and the height of the box 11 is H = d·L / (3.14·D) = 6.4cm. The specific heat capacity of the chromatographic column 21 is c = 0.5J / (g·K), and the density is ρ = 7.93g / cm 3 , volume V = 12.25 cm 3 , m=ρV=97.1g, required heating rate B=30℃ / min.

[0070] η=0.9, T 1max =350℃, B=30℃ / min, ε1=0.4, T1=623.15 K, the luminous length of the lamp tube is consistent with the height of the box 11, both are 6.4cm, the diameter of the lamp tube is 1cm, so the luminous surface area of ​​the lamp tube A0=0.002m 2 , A1=0.025m 2 . Mirror stainless steel ε2=0.4, T2=100+273.15=373.15K.

[0071] According to ηP=ε1σT1 4 A0+ε1σT1 4 A1-ε2σT2 4 A1+c·m·B=129W. Calculated based on a duty cycle of no more than 70%, the electric power ≥P / 0.7=185W.

[0072] Therefore, it is necessary to select a lamp tube with a length of about 6.4cm and a power of about 200W~300W.

[0073] If the air temperature T air =50℃, T1=350℃, T2=100℃. Thermal conductivity k=2.826·10 -2 W / (m·℃), Prandtl constant Pr=0.698, air density ρ=1.093kg / m 3 , air viscosity μ = 1.96·10 -5 Pa·s. The internal height of the box 11 is H = 6.4 cm, the inner diameter of the closed space 13 is d2 = 30 cm, and when d1 = 32 cm, A2 = 0.06 m 2 .

[0074] According to ε1σT1 4 -ε2σT2 4 =αA2(T2-T air ) / A1, we get αA2=1.42 W / (℃), then the forced convection heat transfer coefficient α=23.6W / (m 2 ·℃).

[0075] use , d e =(d1 2 -d2 2 ) / d2; R=0.023(k / d e )(d e uρ / μ) 0.8 P r 0.4 , Q = πd e 2 u / 4, the flow rate u=4.86m / s is obtained, and the air flow rate at 50°C entering the closed space 13 is Q=π·d e 2 ·u / 4=391L / min.

[0076] According to the above design, the temperature of the stainless steel chromatographic column 21 with a length of 10 m can be programmed at most, with a heating rate of 30°C / min, a maximum temperature of 350°C, and a temperature drop from 350°C to 60°C within 5 minutes.

[0077] Example 3.

[0078] According to the application example of the chromatographic column temperature control device and method in Example 1 of the present invention, the difference from Example 2 is that:

[0079] The chromatographic column 21 is preferably a micro-filled column made of SS316, with an outer diameter of d = 0.16 cm and an inner diameter of 0.1 cm. The chromatographic column 21 is bent in a spiral shape, and the pitch is 0, that is, the chromatographic column 21 is cylindrical, and the cylinder diameter D = 4.4 cm, then the height of the box 11 is H = 11.6 cm. The specific heat capacity of the chromatographic column 21 is c = 0.5 J / (g*K), and the density ρ = 7.93 g / cm 3 , volume V = 12.25 cm 3 , m=ρV=97.1g, required heating rate B=30℃ / min.

[0080] η=0.9, ε1=0.4, T1=623.15 K, the luminous length of the lamp tube is the same as that of the column box, both are 11.6 cm, the diameter of the lamp tube is 1 cm, and the luminous surface area of ​​the lamp tube is A0=0.0036 m 2 , A1=0.025m 2 .

[0081] For mirror stainless steel, ε2=0.4. The wall temperature of stainless steel should be greater than the constant temperature gas temperature, calculated according to T2=100+273.15=373.15K.

[0082] According to ηP=ε1σT1 4 A0+ε1σT1 4 A1-ε2σT2 4A1+c·m·B, we get P=135W. Calculated based on the duty cycle not exceeding 70%, the electric power ≥ P / 0.7=193.4W.

[0083] Therefore, it is necessary to select a lamp tube with a length of about 11.6cm and a power of about 300W.

[0084] If T air Controlled to 50℃, T1=350℃, T2=100℃. The internal height of the box 11 is H=11.6cm, the inner diameter d2=20cm of the closed space 13, and the outer diameter d1=22.2cm, A2=0.073m 2 . Thermal conductivity k = 2.826·10 -2 W / (m·℃), Prandtl constant Pr=0.698. Air density ρ=1.093kg / m3, air viscosity μ=1.96·10 -5 Pa·s.

[0085] According to ε1σT1 4 -ε2σT2 4 =αA2(T2-T air ) / A1, we get αA2=1.42 W / (℃), then the forced convection heat transfer coefficient α=19.5W / (m 2 *℃).

[0086] use , d e =(d1 2 -d2 2 ) / d2; R=0.023(k / d e )(d e uρ / μ) 0.8 P r 0.4 , Q = πd e 2 u / 4, the flow rate u=3.35m / s is obtained, and the air flow rate at 50°C entering the closed space 13 is Q=π·d e 2 ·u / 4=339.5L / min.

[0087] According to the above design, the temperature of the stainless steel chromatographic column 21 with a length of 10 m can be programmed at most, with a heating rate of 30°C / min and a maximum temperature of 350°C; the temperature can be reduced from 350°C to 60°C within 5 minutes.

Claims

1. A gas chromatography column temperature control device, comprising a box and a first heater, wherein the first heater is fixed in the box, and the box comprises an upper wall, a vertical wall and a lower wall; characterized in that: The temperature control device also includes: An annular component, the annular component is fixed on the box body, forming a closed space surrounding the vertical wall on the outside of the box body, and the closed space has an inlet and an outlet; A gas supply unit, the gas supply unit provides constant temperature gas, the outlet of which is respectively connected to the inlet and the inside of the box, and the box has a gas outlet; A valve, the valve is used to control whether the constant temperature gas enters the box; The temperature of the isothermal gas is T air satisfy: , ,d e =(d1 2 -d2 2 ) / d2; R=0.023(k / d e )(d e uρ / μ) 0.8 P r 0.4 ,Q=πd e 2 u / 4; ε1 is the surface emissivity of the chromatographic column surrounding the first heater, ε2 is the surface emissivity of the inner wall of the box wall, σ is the Boltzmann constant, T1 is the temperature of the chromatographic column, T2 is the temperature of the box wall, H is the internal height of the box, α is the convection heat transfer coefficient between the constant temperature gas and the wall, A1 is the inner surface area of ​​the chromatographic column, A2 is the surface area of ​​the inner wall of the wall, k, u, ρ, μ and P r are respectively the thermal conductivity, flow rate, density, viscosity and Prandtl number of the gas, d2 and d1 are respectively the inner diameter and outer diameter of the closed space, and Q is the flow rate of the constant temperature gas entering the closed space.

2. The gas chromatography column temperature control device according to claim 1, characterized in that: The set power P of the first heater satisfies: ηP=ε1σT1 4 A0+ε1σT1 4 A1-ε2σT2 4 A1+c·m·B; η is the efficiency of the first heater in converting electrical power into thermal power, A0 is the surface area of ​​the first heater, c and m are the specific heat capacity and mass of the chromatographic column, respectively, and B is the heating rate of the chromatographic column.

3. The gas chromatography column temperature control device according to claim 1 or 2, characterized in that: The spiral chromatographic column is cylindrical, with a pitch of 0, A1 is the inner surface area of ​​the cylinder; the first heater is a light-emitting lamp tube; A0 is the light-emitting surface area of ​​the lamp tube, and the interior of the box is cylindrical.

4. The gas chromatography column temperature control device according to claim 3, characterized in that: The first heater is arranged along the central axis of the box body, and has a length that is the same as the height inside the box body.

5. The gas chromatography column temperature control device according to claim 1 or 2, characterized in that: The vertical wall is made of mirrored stainless steel, and the first heater is made of a cylindrical halogen lamp.

6. The gas chromatography column temperature control device according to claim 1, characterized in that: The gas supply unit comprises: a first pipe and a second pipe, the first pipe being connected to the interior of the box, the second pipe being connected to the inlet, and the valve being arranged on the first pipe; and a third pipe and a second heater, wherein the third pipe is connected to the first pipe and the second pipe, and the second heater is disposed on the third pipe.

7. The gas chromatography column temperature control device according to claim 6, characterized in that: The gas supply unit also includes: A temperature sensor and a control module, wherein the temperature sensor is used to obtain the gas temperature in the second pipeline and transmit the temperature to the control module, and the control module adjusts the parameters of the second heater according to the received temperature value and the set temperature.

8. A temperature control method for a gas chromatography column temperature control device according to any one of claims 1 to 7, specifically: When the temperature of the chromatographic column is increased, the first heater is heated according to the set power, the chromatographic column is heated by the heat radiation emitted by the first heater, and the vertical wall is heated by the heat radiation emitted by the chromatographic column; At the same time, the valve is closed, and the constant temperature gas enters the closed space, taking away the heat of the vertical wall, and the temperature of the vertical wall decreases; When the temperature of the chromatographic column is lowered, the first heater is turned off, the valve is opened, and the constant temperature gas enters the closed space and the inside of the box respectively and is discharged, and the temperature of the chromatographic column and the wall is lowered.

9. The temperature control method according to claim 8, characterized in that: The compressed air is heated and then used as a constant temperature gas.

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