CN104122122A - Pressure stabilizing sampling device - Google Patents

Abstract

The pressure stable sampling device of the present invention comprises a sampling tube, a pressure stabilizing chamber, a control system and a gas monitoring instrument, the sampling tube is connected to the air inlet of the pressure stabilizing chamber, one path of the pressure stabilizing chamber is connected to multi-branch pipes, and each branch pipe is connected to the gas monitoring Instrument, the inlet end of the sampling tube is provided with a first flowmeter and a flow restrictor in turn, the pressure stabilization chamber is connected with a vacuum pump through a ventilation pipeline, and a second flowmeter and a proportional regulating valve are installed on the ventilation pipeline. The pressure stabilization sampling device of the present invention The injection pressure can be maintained at a constant value to ensure the repeatability of the injection. The internal pressure of the instrument can be adjusted through the pressure stabilization chamber and the control device to maintain the internal pressure of the instrument at a constant value. The aerial survey flight altitude environment must be lower than this In the case of the value, there is no need to calibrate it, so as to realize the uncertainty caused by the pressure change caused by the altitude change of the aircraft, and improve the data accuracy of the gas monitoring instrument during the aerial survey.

Description

Pressure Stabilized Sampling Device

technical field

The invention relates to a voltage-stabilizing sampling device, in particular to a voltage-stabilizing sampling device used in aerial surveys.

Background technique

In aerial surveys, analytical instruments are usually used to monitor the concentration of gas samples. In order to accurately analyze and measure the concentration of gases, it is necessary to ensure that the sampling process has good repeatability (that is, the repeatability of multiple sampling gas monitoring results). The stable pressure during sample injection is an important condition to ensure the repeatability of sample injection, but in the aerial survey, due to the change of flight altitude, the real-time change of external pressure brings difficulties to control the sample injection pressure.

The existing atmospheric environment gas monitoring instruments used on the ground can be placed in a specific environment (generally set to 0.6 atmospheric pressure on the ground), so as to ensure that the internal pressure of the instrument remains constant and solve the problem of calibration stability. However, during the aerial survey, as the height of the transport aircraft changes, the following problems still exist in the application of existing atmospheric environment gas monitoring instruments:

1. During the aerial survey, the pressure at the air inlet of the sampling pipe changes with the height of the transport aircraft. The real-time change of the external pressure brings difficulties in controlling the injection pressure, which leads to poor repeatability of the injection, which will bring errors to the sampling measurement results. Thus affecting the gas monitoring accuracy;

2. Atmospheric environment gas monitoring instruments need to perform gas monitoring in a stable air pressure environment, and when the pressure of the instrument varies, the internal standard quantity cannot be determined, which affects the accuracy of gas monitoring.

Contents of the invention

The purpose of the invention of this application is to solve the technical problems that the sampling pressure of the current atmospheric environment gas monitoring instrument is unstable when used in aerial surveys, the instrument pressure changes greatly and cannot be calibrated, and to provide a pressure stable sampling device.

In order to complete the invention purpose of the application, the application adopts the following technical solutions:

The pressure stable sampling device of the present invention comprises a sampling tube, a pressure stabilizing chamber and a gas monitoring instrument, the sampling tube is connected to the air inlet of the pressure stabilizing chamber, and the gas outlet pipe of the pressure stabilizing chamber is connected to the gas monitoring instrument, the inlet end of the sampling pipe is provided with a first flowmeter and a flow restrictor in turn, and the pressure stabilization chamber also has a port connected to a control device, and the control device includes a second flowmeter, a proportional control valve, a vacuum pump and a PC, the pressure stabilizing chamber is connected to the vacuum pump through a ventilation pipeline, the second flowmeter and the proportional regulating valve are installed on the ventilation pipeline, and the PC is connected to the first flowmeter, the The second flow meter, proportional regulating valve, flow restrictor and vacuum pump are connected.

The current restrictor of the present invention is a proportional regulating valve, and the proportional regulating valve is connected with the PC.

The gas outlet pipe of the gas monitoring instrument of the present invention is communicated with the vacuum pump, and a third flowmeter and a regulating valve are arranged between the gas monitoring instrument and the vacuum pump, and the third flowmeter and the regulating valve are connected with the PC respectively. connected.

In the present invention, a thermometer and a hygrometer are also installed between the first flowmeter and the flow restrictor, and a flowmeter, a hygrometer and a thermometer are also connected to the pressure stabilization chamber.

The second flow meter and the proportional regulating valve of the present invention can be replaced by a mass flow controller.

The PC of the present invention is also connected with an alarm.

The flow restrictor of the present invention may also be a flow restricting hole or a mass flow controller, and the mass flow controller is connected to the PC.

The pressure stable sampling device of the present invention can keep the sampling pressure at a constant value through the flow limiter to ensure the repeatability of sampling, and can adjust the internal pressure of the instrument through the pressure stabilizing chamber and the control system to maintain the internal pressure of the instrument at a constant value. Value, so as to achieve a stable calibration value, so that the accuracy of gas monitoring during aerial survey can be greatly improved.

In addition, the outlet pipe of the gas monitoring instrument is connected to the vacuum pump, which can control the discharge flow of the gas monitoring instrument and the internal air pressure of the gas monitoring instrument through the vacuum pump. To monitor the function of the internal air pressure in real time, and then send the measured results to the PC, and control the internal air pressure in real time through the PC.

Description of drawings

FIG. 1 is an overall schematic diagram of a pressure-stabilized sampling device of the present invention.

Detailed ways

As shown in Figure 1, the pressure stable sampling device of this embodiment includes a sampling tube 1, a pressure stabilizing chamber 2 and a gas monitoring instrument 3, the sampling tube 1 is connected to the inlet of the pressure stabilizing chamber 2, and the outlet of the pressure stabilizing chamber 2 The trachea is connected to the gas monitoring instrument 3 through a multi-branch pipe, and each branch pipe is connected to a certain gas monitoring instrument 3. The inlet end of the sampling pipe 1 is provided with a first flowmeter 4 and a flow restrictor 5 in turn, and the pressure stabilization chamber 2 is also There is a port connected to the control device 6, the control device 6 includes a second flow meter 7, a proportional control valve 8, a vacuum pump 9 and a PC 10, the pressure stabilization chamber 2 is connected to the vacuum pump 9 through a vent pipe, and the second flow meter is installed on the vent pipe. The flow meter 7 and the proportional regulating valve 8, the PC 10 are respectively connected with the first flow meter 4, the second flow meter 7, the proportional regulating valve 8 and the vacuum pump 9, the gas outlet pipe of the gas monitoring instrument 3 is connected to the vacuum pump 9, and the gas monitoring instrument 3 and the vacuum pump 9 are provided with a third flowmeter 11 and a regulating valve 12, and the third flowmeter 11 and regulating valve 12 are connected to the PC 10 respectively.

The flow limiter 5 in this embodiment can be a flow limiting hole or a mass flow controller, the flow limiter 5 is connected with the PC 10, a thermometer and a hygrometer are also installed between the first flowmeter 4 and the flow limiter 5, A flow meter, a hygrometer and a thermometer are also connected to the pressure stabilization chamber 2 .

The PC 10 of the present invention is also connected with an alarm. When the pressure measured by the second flowmeter 7 is obviously greater than the value of the first flowmeter 4, the PC 10 will start the alarm to alert the staff to overhaul the gas monitoring and sampling device. .

The second flow meter 7 and the proportional regulating valve 8 of this embodiment can be replaced by a mass flow controller.

The method of using the above-mentioned pressure-stabilized sampling device is as follows: during the aerial survey, the air inlet of the sampling pipe is directly facing the air flow. With the operation of the transport plane, the wind speed of the inlet increases, the flow of the air flow increases, and the pressure at the restrictor 5 continues to increase. increase, but when the wind speed increases to a certain level, the pressure at the flow restrictor 5 will stop rising and be at a constant value, so that the sample injection pressure remains unchanged, and the air flow will enter the pressure stabilization chamber after passing through the flow restrictor 5, which can be The pressure stabilizing chamber 2 reduces the impact on the gas monitoring accuracy of the gas monitoring instrument when the sample injection pressure changes, ensures the sample injection repeatability, and improves the gas monitoring accuracy. In addition, the internal pressure of the sampling device can be adjusted through the regulating device, the specific method is as follows:

Before the operation of the transport plane, set the internal air pressure of the atmospheric environment gas monitoring instrument to the calibration value, generally set to 0.6 atmospheric pressure. As the pressure increases, the pressure at the restrictor continues to increase, but when the wind speed increases to a certain level, according to the Venturi theorem, the pressure at the restrictor 5 will stop rising and remain at a constant value. At the same time, the inlet of the sampling tube The first flowmeter 4, thermometer and hygrometer at the place, the second flowmeter 7, the third flowmeter 11, the flowmeter, hygrometer and thermometer on the pressure stabilization chamber 2 transmit the measured values to the PC 10 from time to time, The PC 10 controls the pressure release of the vacuum pump 9 and the flow limiter 5 to control the pressure of the inlet according to the measured values, so that the pressure inside the sampling device and the pressure at the inlet of the sampling tube 1 are equal to the calibration value, thereby ensuring gas monitoring Accuracy.

The above-mentioned embodiments are only descriptions of preferred implementations of the present invention, and are not intended to limit the scope of the present invention. Variations and improvements should fall within the scope of protection defined by the claims of the present invention.

Claims (6)

1. a pressure stability sampling apparatus, comprise sampling pipe (1), pressure stability chamber (2) and gas monitoring instrument (3), described sampling pipe (1) is communicated in the air intake opening in described pressure stability chamber (2), it is characterized in that: the escape pipe in described pressure stability chamber (2) is communicated in described gas-monitoring instrument (3) by multi-limbed tube, the inlet end of described sampling pipe (1) is provided with first flow meter (4) and restrictor (5) successively, described pressure stability chamber (2) also has the port of connection regulation device (6), described regulation device (6) comprises the second flowmeter (7), ratio adjusting valve (8), vacuum pump (9) and PC (10), described pressure stability chamber (2) is connected with described vacuum pump (9) by breather line, described the second flowmeter (7) and described ratio adjusting valve (8) are installed on described breather line, described PC (10) respectively with described first flow meter (4), the second flowmeter (7), ratio adjusting valve (8), restrictor (5) is connected with vacuum pump (9).

2. pressure stability sampling apparatus as claimed in claim 1, it is characterized in that: the escape pipe of described gas-monitoring instrument (3) is communicated in described vacuum pump (9) by multi-limbed tube, between described gas-monitoring instrument (3) and vacuum pump (9), be provided with the 3rd flowmeter (11) and variable valve (12), described the 3rd flowmeter (11) is connected with described PC (10) respectively with variable valve (12).

3. pressure stability sampling apparatus as claimed in claim 2, it is characterized in that: between described first flow meter (4) and restrictor (5), thermometer, hygrometer are also installed, on described pressure stability chamber (2), are also connected with flowmeter, hygrometer and thermometer.

4. pressure stability sampling apparatus as claimed in claim 3, is characterized in that: described the second flowmeter (7) and ratio adjusting valve (8) available quality flow controller are replaced.

5. pressure stability sampling apparatus as claimed in claim 4, is characterized in that: described PC (10) is also connected with alarm.

6. pressure stability sampling apparatus as claimed in claim 1, is characterized in that: described restrictor (5) is metering hole or mass flow controller, and described mass flow controller is connected with described PC (10).