CN217845766U - Sampling device for detecting content of methanol and formaldehyde in methanol engine tail gas - Google Patents
Sampling device for detecting content of methanol and formaldehyde in methanol engine tail gas Download PDFInfo
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- CN217845766U CN217845766U CN202221809349.6U CN202221809349U CN217845766U CN 217845766 U CN217845766 U CN 217845766U CN 202221809349 U CN202221809349 U CN 202221809349U CN 217845766 U CN217845766 U CN 217845766U
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Abstract
The utility model provides a methyl alcohol, formaldehyde sampling device among methyl alcohol engine exhaust, including the sampling pipeline that is arranged in conveying gas, establish the sampling pipe that is arranged in adsorbing methyl alcohol or formaldehyde on the sampling pipeline in the engine exhaust, establish critical flow venturi that is located the sampling pipe low reaches on the sampling pipeline and be located the minipump that critical flow venturi low reaches made gaseous carry in the sampling pipeline. The sampling device of the utility model extracts gas from the dilution channel in the engine tail gas emission testing equipment directly for sampling, thereby avoiding the situation that the volume of the collected gas can not meet the requirements of regulations due to the limited volume of the gas collection bag body and avoiding the situation that the tail gas generates steam for condensation due to the temperature reduction; moreover, continuous sampling can be realized, the flow of sampled gas is more accurate, and the detection result of the content of methanol and formaldehyde in the subsequent methanol engine tail gas is more accurate.
Description
Technical Field
The utility model belongs to gaseous pollutant sampling field, concretely relates to sampling device of methyl alcohol, formaldehyde content detection in methyl alcohol engine exhaust.
Background
According to the regulation of the standard of 'method for measuring the emission of unconventional pollutants of methanol fuel automobiles' (HJ 1137-2020), two sampling modes of unconventional pollutants, namely methanol and formaldehyde, are provided in the process of measuring the emission pollutants of the tail gas of the heavy-duty methanol engine. One is to collect sample gas in a gas collection bag of a dilution emission test system after the emission test cycle is finished to measure the content of methanol and formaldehyde (A sampling scheme for short), and the other is to collect samples in a tail gas dilution channel of the dilution emission test system in the emission test cycle (B sampling scheme for short) to analyze, wherein the A sampling scheme is mostly used in the type test process at present.
The sampling scheme A is that after the circulation of the emission test is finished, sampling is carried out in a gas collecting bag of the dilution emission test system, and the volume of gas flowing through each sampling pipe is not less than 15L when the regulation requires the collection of formaldehyde; when methanol is collected, the sampling volume flowing through each sampling tube is not less than 9L. Generally, after one emission test cycle is finished, methanol and formaldehyde are respectively sampled, so that at least 24L of sample gas in the gas collection bag is required by using the sampling scheme A. After the test is finished, the emission analyzer can extract a part of gas from the gas collection bag to measure and analyze other conventional pollutants (CO, THC, NOx and the like), the volume of the gas collection bag is limited, and after the conventional pollutants are analyzed, the volume of the residual gas in the gas collection bag can not reach 24L, so that the sampling requirements of formaldehyde and methanol can not be met, and the test fails.
Meanwhile, the effectiveness of sampling is regulated by laws and regulations, two or more sampling pipes are required to be connected in series for sampling in the sampling process, and the analysis result is the sum of the adsorption capacity of each sampling pipe. In the subsequent analysis, the mass of the formaldehyde or the methanol measured in the last sampling tube at the downstream is less than 10.0 percent of the mass of all other sampling tubes at the upstream. Therefore, 3 or more sampling pipes may need to be connected in series in the actual sampling process, the resistance caused by the series connection of the sampling pipes can be overcome by the sampling pump with larger suction force, and the portable rechargeable constant-flow sampling pump used in the sampling process of the scheme A has smaller working power, so that the situation that the sampling pump stops working due to insufficient power can often occur.
In addition, the flow rate of the portable constant-flow sampling pump used in the scheme a during actual operation is also affected by changes in the ambient temperature, so that the actual gas flow rate passing through the sampling pump is different from a set value to a certain extent, the ambient temperature is not continuously monitored and measured in the sampling process, the sampling flow rate of the whole sampling process cannot be corrected, and finally, the measurement result is inaccurate.
SUMMERY OF THE UTILITY MODEL
The utility model aims at solving the technical problem existing in the prior art, the utility model aims at providing a sampling device for methanol and formaldehyde content detection in methanol engine tail gas.
In order to achieve the above purpose, the utility model adopts the following technical scheme: the utility model provides a sampling device that methyl alcohol, formaldehyde content detected in methyl alcohol engine exhaust, including the sampling pipeline that is used for the transported gas, establish the sampling pipe that is arranged in adsorbing methyl alcohol or formaldehyde in the sample gas on the sampling pipeline, establish the critical flow venturi that is located the sampling pipe low reaches on the sampling pipeline, and be located critical flow venturi low reaches and be used for making the pump that gas carried in the sampling pipeline, gas gets into in the sampling pipeline through the sampling pipeline entry, the export of sampling pipeline links to each other with the entry of pump, the export of pump communicates with each other with external atmosphere.
In the technical scheme, the sampling pipe is used for adsorbing formaldehyde or methanol in the sample gas, and then the formaldehyde or methanol is reversely desorbed by a chemical analysis means to perform quantitative analysis. The critical flow venturi is a nearly constant flow gas flow meter that measures the flow of sample gas through the sampling tube and calculates the volume of sample gas flowing through the sampling tube from the flow integrated over time.
The utility model discloses a sampling device need not to sample from the gas collection bag, but directly extracts gas from the tail gas dilution channel of emission analysis equipment and samples, compares the method of sampling from the gas collection bag in emission analysis equipment at present, and this sampling device can avoid because the gas collection bag is long-pending to lead to the fact the volume of gathering gas can not satisfy the condition that the regulation required, can avoid tail gas because the temperature descends and produce the condition that vapor condenses simultaneously; moreover, continuous sampling can be realized, the flow of sampled gas is more accurate, and the detection result of the content of methanol and formaldehyde in the subsequent methanol engine tail gas is more accurate.
The utility model discloses an in a preferred embodiment, still be equipped with on the sampling line and be located the heating device between sampling pipe and the critical flow venturi and be located the temperature pressure sensor who is used for measuring temperature and pressure of heating device low reaches, temperature pressure sensor's signal output part links to each other with the control unit.
Among the above-mentioned technical scheme, the heating device carries out the constant temperature processing to the sample gas that gets into critical flow venturi, and temperature pressure sensor is used for the temperature and the pressure of the sample gas that gets into critical flow venturi, carries out temperature and pressure correction to the transient state gas flow who gets into critical flow venturi from this, makes critical flow venturi's flow measurement more accurate, and the sample gas volume measurement through the collection pipe that obtains through integral calculation is more accurate, makes follow-up methyl alcohol, formaldehyde's content measurement more accurate from this.
The utility model discloses an in the preferred embodiment, critical flow venturi detachable connects on the sampling pipeline, and sampling device disposes the critical flow venturi of a plurality of different laryngeal aperture diameters. In the technical scheme, the critical flow venturi tubes with different throat diameters can be selected according to the size of the sampling flow.
In a preferred embodiment of the present invention, the heating device is a heat exchanger. The heat exchanger can heat or cool the sample gas entering the critical flow venturi tube according to the requirement.
In a preferred embodiment of the present invention, the collection control terminal of the control unit is connected to the enable terminal of the pump.
In a preferred embodiment of the present invention, the control unit is connected to a main control computer of the engine testing stand.
In a preferred embodiment of the present invention, the pump is a micro vacuum pump.
Among the above-mentioned technical scheme, the believe vacuum pump a little of this scheme adopts the formula power supply mode that cut straightly, can avoid current portable rechargeable sampling pump because of the not enough condition of stop work of power, can select the vacuum pump that makes the sampling gas flow rate reach the sound velocity to satisfy the actual requirement moreover.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a schematic structural diagram of a sampling device for detecting the content of methanol and formaldehyde in methanol engine exhaust according to an embodiment of the present application.
Reference numerals in the drawings of the specification include: the device comprises a sampling pipeline 1, a sampling pipe 2, a heating device 3, a temperature and pressure sensor 4, a critical flow Venturi tube 5, a control unit 6, a pump 7 and an engine test bench master control computer 8.
Detailed Description
Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary only for the purpose of explaining the present invention, and should not be construed as limiting the present invention.
In the description of the present invention, it is to be understood that the terms "longitudinal", "lateral", "vertical", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be construed as limiting the present invention.
In the description of the present invention, unless otherwise specified and limited, it is to be noted that the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, mechanically or electrically connected, or may be connected between two elements through an intermediate medium, or may be directly connected or indirectly connected, and specific meanings of the terms may be understood by those skilled in the art according to specific situations.
The utility model provides a methyl alcohol among methyl alcohol engine exhaust, formaldehyde content detection's sampling device, as shown in figure 1, this sampling device is including the sampling pipeline 1 that is used for conveying gas, establish the sampling pipe 2 that is arranged in adsorbing methyl alcohol or formaldehyde among the tail gas on sampling pipeline 1 (sampling pipe 2 is the absorption formula sampling pipe that adopts among the current chemical analysis), establish critical flow venturi 5 that is located sampling pipe 2 low reaches on sampling pipeline 1, and be located critical flow venturi 5 low reaches and be used for making gaseous pump 7 of carrying in sampling pipeline 1, pump 7 adopts micro vacuum pump, gas gets into in sampling pipeline 1 through sampling pipeline 1 entry, sampling pipeline 1's export links to each other with pump 7's entry, pump 7's export communicates with each other with external atmosphere.
In another preferred embodiment, a heating device 3 is further disposed on the sampling pipeline 1 between the sampling pipe 2 and the critical flow venturi 5, and a temperature and pressure sensor 4 is disposed downstream of the heating device 3 for measuring temperature and pressure, the temperature and pressure sensor 4 may be a pressure and temperature integrated transmitter (such as FST800-217 type pressure and temperature integrated transmitter of the francis and filister sensor limited company), or a temperature sensor and a pressure sensor are respectively disposed on the sampling pipeline 1 (the temperature sensor and the pressure sensor are disposed on the pipeline and are of conventional design of pipeline systems, and are commercially available, and the model and specification are not limited). The signal output end of the temperature and pressure sensor 4 is connected with the control unit 6, the acquisition control end of the control unit 6 is connected with the enabling end of the pump 7, and the control unit 6 is connected with the engine test bench main control computer 8.
The heating device 3 heats or cools the gas entering the critical flow venturi 5, so that the temperature of the gas in the sampling pipeline 1 can be kept within a set temperature range without great fluctuation, and the heating device 3 can be a heat exchanger or a resistance heater. The utility model discloses a sampling device, sampling pipeline 1's entry is connected with engine emission analytic system's dilution passageway, before the sampling, according to the difference of analysis target material, adopts assorted absorption type sampling pipe 2, uses two and more than two sampling pipes 2 to establish ties according to the regulation requirement simultaneously.
The start and the end of the discharge cycle are operated and finished by the engine test bench main control computer 8, when the discharge test program starts or ends, the engine test bench main control computer 8 sends a signal to the control unit 6, and the control unit 6 controls the pump 7 to start or stop after receiving the signal. When the pump 7 starts to work, negative pressure is formed inside the sampling pipeline 1, so that part of gas enters the sampling pipeline 1 from the dilution channel, the gas entering the sampling pipeline 1 firstly passes through the sampling pipe 2, formaldehyde or methanol is adsorbed inside the sampling pipe 2 (when the content of methanol and formaldehyde in the gas is analyzed subsequently, the formaldehyde or methanol is desorbed reversely through a chemical analysis means and is analyzed quantitatively), the gas passing through the sampling pipe 2 enters the heating device 3 on the next step, the heating device 3 keeps the temperature of the gas in the sampling pipeline 1 within a set temperature range, and the influence of the environmental temperature on the sampling flow is reduced.
The gas after passing through the heating device 3 flows through a critical flow venturi tube 5 (the critical flow venturi tube 5 is a small-sized venturi tube with standard flow, which is also called a critical flow venturi nozzle, and the structure and principle of the venturi tube are the prior art, and are not described in detail herein), and the critical flow venturi tube 5 functions to fix and measure the flow of the gas passing through the inside thereof. The temperature and pressure of the gas before entering the critical flow Venturi tube 5 are measured by a temperature and pressure sensor 4 arranged on the sampling pipeline 1, the temperature and pressure measurement results and flow data are stored and recorded by a control unit 6, meanwhile, the data are sent to an engine test bench main control computer 8, and finally, the gas is emptied through a pump 7.
The flow Q of the critical flow venturi tube is obtained by using the existing following calculation formula:
Q＝t*Kv*Pp*/T 0.5
in the formula: t-sampling time, s;
kv is the critical flow venturi tube calibration coefficient under the standard condition;
Pp-Venturi Inlet Absolute pressure, kPa;
t-the absolute temperature at the venturi entrance, K.
Each critical flow venturi tube 5 corresponds to a critical flow venturi tube calibration coefficient Kv (calibration coefficient for short) under a standard condition, and the calibration coefficient of the critical flow venturi tube 5 is stored in the control unit 6. The temperature and pressure sensor 4 continuously detects the temperature and pressure of the sample gas entering the critical flow venturi tube 5 according to a certain frequency, and records data in the control unit 6, and the data recording start and end time is controlled by the control unit 6; after sampling is finished, the control unit 6 calculates the volume of the gas passing through the sampling tube 2 according to the recorded data value, the frequency and the calibration coefficient of the critical flow venturi tube.
The utility model discloses a critical flow venturi 5 detachable connects on sampling pipeline 1, and this sampling device disposes the critical flow venturi 5 of a plurality of different laryngeal aperture diameters. Therefore, the critical flow Venturi tube 5 with different throat diameters can be selected according to the size of the sampling flow.
The utility model discloses a when gas temperature and pressure were constant basically in the sampling pipeline 1, the air flow through critical flow venturi 5 was a definite value, chooseed for use the critical flow venturi 5 of suitable laryngeal opening diameter, and the calibration factor Kv that corresponds has just confirmed and has got off, alright fixed this sampling device's sampling flow, measured sampling flow simultaneously.
In the description of the present specification, reference to the description of the terms "preferred embodiment," "one embodiment," "some embodiments," "an example," "a specific example" or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (7)
1. The utility model provides a sampling device that methyl alcohol, formaldehyde content detected in methyl alcohol engine exhaust, its characterized in that, including the sampling pipeline that is used for transporting gas, establish the sampling pipe that is arranged in adsorbing methyl alcohol or formaldehyde in the exhaust on the sampling pipeline, establish critical flow venturi who is arranged in the sampling pipe low reaches on the sampling pipeline, and be arranged in critical flow venturi low reaches and be used for making the pump that gas carried in the sampling pipeline, the exhaust gets into the sampling pipeline through the sampling pipeline entry, the export of sampling pipeline links to each other with the entry of pump, the export of pump communicates with each other with external atmosphere.
2. The sampling device for detecting the contents of methanol and formaldehyde in the tail gas of the methanol engine as claimed in claim 1, wherein the sampling pipeline is further provided with a heating device located between the sampling pipe and the critical flow venturi tube, and a temperature pressure sensor located downstream of the heating device for measuring temperature and pressure, and a signal output end of the temperature pressure sensor is connected with the control unit.
3. The sampling device of claim 2, wherein the critical flow venturi tube is detachably connected to the sampling line, and the sampling device is configured with a plurality of critical flow venturi tubes with different throat diameters.
4. The sampling device for detecting the content of methanol and formaldehyde in the tail gas of the methanol engine as claimed in claim 2, wherein the heating device is a heat exchanger.
5. The sampling device for detecting the content of methanol and formaldehyde in the tail gas of the methanol engine according to any one of claims 2 to 4, wherein the acquisition control end of the control unit is connected with the enabling end of the pump.
6. The sampling device for detecting the contents of methanol and formaldehyde in the tail gas of the methanol engine according to claim 5, wherein the control unit is connected with a main control computer of an engine test bench.
7. The sampling device for detecting the content of methanol and formaldehyde in the methanol engine exhaust gas as claimed in any one of claims 1 to 4, wherein the pump is a micro vacuum pump.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202221809349.6U CN217845766U (en) | 2022-07-13 | 2022-07-13 | Sampling device for detecting content of methanol and formaldehyde in methanol engine tail gas |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202221809349.6U CN217845766U (en) | 2022-07-13 | 2022-07-13 | Sampling device for detecting content of methanol and formaldehyde in methanol engine tail gas |
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| Publication Number | Publication Date |
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| CN217845766U true CN217845766U (en) | 2022-11-18 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202221809349.6U Active CN217845766U (en) | 2022-07-13 | 2022-07-13 | Sampling device for detecting content of methanol and formaldehyde in methanol engine tail gas |
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| CN (1) | CN217845766U (en) |
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- 2022-07-13 CN CN202221809349.6U patent/CN217845766U/en active Active
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