阅读说明：本技术 一种煤样瓦斯解吸量测定装置及测定方法 (Coal sample gas desorption amount measuring device and measuring method ) 是由 鲁忠良 原保全 王洪丽 郭新红 权佩胜 陈建龙 陆军 景瑞 郭良 曹秀龙 杜江涛 于 2019-11-06 设计创作，主要内容包括：本发明公开了一种煤样瓦斯解吸量测定装置及测定方法,测定装置包括连通的反应机构和测定机构,测定机构包括依次连通的第一引压管、流量测量管和第二引压管,流量测量管内设有瓦斯流量传感模块,第二引压管出气端设有用于向外排气的排气口,测定时,先进行设备安装与验证,再进行煤样反应,然后打开阀门进行煤样测试,获取瓦斯解吸量,最后关闭阀门；本发明能够在快捷高效地进行瓦斯解吸量测定的同时,替代传统的排水法进行测定,有效提高解吸量测定结果的准确性,同时,性能可靠,稳定性强。(The invention discloses a coal sample gas desorption amount measuring device and a measuring method, wherein the measuring device comprises a reaction mechanism and a measuring mechanism which are communicated, the measuring mechanism comprises a first pressure leading pipe, a flow measuring pipe and a second pressure leading pipe which are sequentially communicated, a gas flow sensing module is arranged in the flow measuring pipe, an air outlet end of the second pressure leading pipe is provided with an air outlet for exhausting air outwards, during measurement, equipment is firstly installed and verified, then coal sample reaction is carried out, then a valve is opened for coal sample test, the gas desorption amount is obtained, and finally the valve is closed; the invention can quickly and efficiently measure the gas desorption amount, and meanwhile, the traditional drainage method is replaced for measurement, so that the accuracy of the desorption amount measurement result is effectively improved, and meanwhile, the invention has reliable performance and strong stability.)

1. The utility model provides a coal sample gas desorption volume measuring device which characterized in that: comprises a reaction mechanism and a determination mechanism;

the reaction mechanism comprises a coal sample tank, a guide pipe and a valve arranged on the guide pipe, the upper end part of the coal sample tank is communicated with the air inlet end of the guide pipe, and the air outlet end of the guide pipe is communicated with the measuring mechanism; the coal sample tank comprises a tank cover and a tank body which are arranged up and down, the lower end of the tank cover is hermetically connected with the upper end of the tank body, and the upper end of the tank cover is provided with an exhaust hole for communicating a guide pipe;

the measuring mechanism comprises a first pressure leading pipe, a flow measuring pipe, a second pressure leading pipe and a central processing module, the first pressure leading pipe, the flow measuring pipe and the second pressure leading pipe are sequentially communicated, the air inlet end of the first pressure leading pipe is communicated with the air outlet end of the guide pipe, a gas flow sensing module for measuring the gas flow is arranged in the flow measuring pipe, and the air outlet end of the second pressure leading pipe is provided with an air outlet for exhausting outwards; the detection signal input end of the central processing module is connected with the output end of the gas flow sensing module.

2. The coal-sample gas desorption amount measurement device according to claim 1, characterized in that: the flow sensing module comprises a throttling piece, a high-pressure sensing element and a low-pressure sensing element, wherein the high-pressure sensing element, the throttling piece and the low-pressure sensing element are sequentially distributed along the flow direction of gas in the flow measuring pipe; the output end of the high-voltage sensing element and the output end of the low-voltage sensing element are respectively connected with the detection signal input end of the central processing module.

3. The coal-sample gas desorption amount measurement device according to claim 2, characterized in that: the flow measurement pipe is in a single-blade hyperboloid structure with thick ends and thin middle parts, the throttling element is arranged at the position with the thinnest inner diameter of the flow measurement pipe, the pipe walls of the flow measurement pipes on two sides of the throttling element are respectively provided with a high-pressure tapping and a low-pressure tapping, the high-pressure sensing element is arranged in the high-pressure tapping, and the low-pressure sensing element is arranged in the low-pressure tapping.

4. The coal-sample gas desorption amount measurement device according to claim 1, characterized in that: the cover adopts the toper structure, cover osculum and pipe integrated into one piece, cover macrostoma sealing connection can body.

5. The coal-sample gas desorption amount measurement device according to claim 1, characterized in that: the guide pipe and the first pressure pipe are connected through a connecting nut, a horn-shaped vent groove is arranged in the connecting nut, a large opening of the horn-shaped vent groove is connected with the guide pipe, and a small opening of the horn-shaped vent groove is connected with the first pressure pipe.

6. The coal-sample gas desorption amount measurement device according to claim 5, characterized in that: and sealing rubber gaskets are arranged between the tank body and the tank cover and between the horn-shaped vent groove and the guide pipe.

7. The coal-sample gas desorption amount measurement device according to claim 1, characterized in that: the outer fixing clip that is used for fixed external equipment that is equipped with of can body, the can body bottom is equipped with articulated nut.

8. The coal-sample gas desorption amount measurement device according to claim 1, characterized in that: the measuring mechanism further comprises a display dial, and the input end of the display dial is connected with the signal output end of the central processing module.

9. A determination method based on the coal sample gas desorption amount determination apparatus of claim 2 is characterized in that: the method comprises the following steps:

A. equipment installation and verification: closing the valve, connecting the guide pipe with the first guide pipe, verifying the air tightness of the coal sample tank and each interface, and entering the next step if the air tightness is confirmed to be good;

B. coal sample reaction: collecting a coal sample and filling the coal sample into a coal sample tank, tightly covering the tank cover, and starting the reaction of the coal sample;

C. opening a valve to test a coal sample, and obtaining the gas desorption amount: the specific process is as follows:

c 1: the valve is blocked, and gas generated in the coal sample tank flows into the flow measuring pipe after passing through the guide pipe and the first pressure guiding pipe;

c 2: the high-pressure sensing element and the low-pressure sensing element detect the pressure difference change at two ends of the throttling element and transmit the pressure difference change to the central processing module, and meanwhile, desorbed gas is exhausted to the outside through the exhaust port;

c 3: the central processing module calculates the desorption amount and the gas loss amount of the gas in the coal sample tank according to the pressure difference change;

D. and closing the valve and finishing the test.

10. The method for measuring a desorption amount of coal-sample gas according to claim 9, characterized in that: the specific calculation process of the gas loss in the step c3 is as follows:

calculating the gas desorption volume in the standard state according to the gas desorption flow in the test time, wherein the calculation formula is as follows:

in the formula (1), V_t0Expressed in cm converted to the gas volume in the standard state³；V_tThe total amount of gas desorbed in cm within 2h measured underground³，P₁Representing downhole air pressure in kPa, t_wThe temperature in the sampling tank is expressed in unit;

by usingThe gas loss is calculated by the method, and the formula is as follows:

in the formula (2), a and b represent undetermined constants when

Technical Field

The invention relates to the technical field of coal sample desorption, in particular to a device and a method for measuring the gas desorption amount of a coal sample.

Background

In the original coal body, once the dynamic equilibrium state of the free gas and the adsorbed gas is destroyed, the occurrence state of partial gas can be converted in a single direction within a certain time until a new dynamic equilibrium state is reached. When the coal sample is in the original coal body, the gas pressure of the coal sample is equal to the gas pressure of the original coal body, and the free gas and the adsorbed gas in the coal sample are in a dynamic balance state; after the coal sample is stripped by the excavation operation, the coal is exposed to the atmosphere, the pressure of the surrounding environment becomes the atmospheric pressure of the measuring place, the pressure is reduced, the dynamic balance state of free gas and adsorbed gas in the coal sample is destroyed, the original gas adsorbed in the coal starts to be desorbed until the gas pressure in the coal sample is equal to the atmospheric pressure of the measuring place, and the new dynamic balance is achieved.

At present, the content of each layer of original gas in the underground is usually determined directly, and the specific flow of the direct method is as follows:

selecting a proper test site on site, taking out the coal sample from the deep part of the coal bed through drilling, putting the coal sample into a coal sample tank in time, sealing the coal sample tank well, and testing the gas desorption X within 2 hours on site_jThen according to the desorption rule of coal sample gasSelecting a proper empirical formula to calculate the gas loss X before the coal sample is filled into the coal sample tank_sFinally, the coal sample tank is taken back to the laboratory for residual gas content X_cAnd (4) measuring, wherein the sum of the three is the coal bed gas content.

However, during the field test in the underground, the existing coal sample tank for testing the desorption amount of the gas has the following problems:

1) poor sealing performance: the gas leakage is easy to occur at the threaded occlusion part of the tank opening of the coal sample tank, so that the test result is inaccurate;

2) the puncture needle head is easily blocked by the sealing rubber pad in the using process, so that desorbed gas cannot be normally collected, and the accurate judgment of workers on the occurrence condition of the coal bed gas on site is influenced;

3) the method for testing the coal sample desorption amount underground by adopting a direct method needs to be carried out by using a drainage method, namely, a tester acquires a plurality of groups of coal samples underground, fills the testing device with water, and utilizes gas pressure to drain water to measure the volume of gas.

Disclosure of Invention

The invention aims to provide a coal sample gas desorption amount measuring device and a measuring method, which can quickly and efficiently measure the gas desorption amount, replace the traditional drainage method for measurement, effectively improve the accuracy of a desorption amount measuring result, and have reliable performance and strong stability.

The technical scheme adopted by the invention is as follows:

a coal sample gas desorption amount measuring device comprises a reaction mechanism and a measuring mechanism;

the reaction mechanism comprises a coal sample tank, a guide pipe and a valve arranged on the guide pipe, the upper end part of the coal sample tank is communicated with the air inlet end of the guide pipe, and the air outlet end of the guide pipe is communicated with the measuring mechanism; the coal sample tank comprises a tank cover and a tank body which are arranged up and down, the lower end of the tank cover is hermetically connected with the upper end of the tank body, and the upper end of the tank cover is provided with an exhaust hole for communicating a guide pipe;

the measuring mechanism comprises a first pressure leading pipe, a flow measuring pipe, a second pressure leading pipe and a central processing module, the first pressure leading pipe, the flow measuring pipe and the second pressure leading pipe are sequentially communicated, the air inlet end of the first pressure leading pipe is communicated with the air outlet end of the guide pipe, a gas flow sensing module for measuring the gas flow is arranged in the flow measuring pipe, and the air outlet end of the second pressure leading pipe is provided with an air outlet for exhausting outwards; the detection signal input end of the central processing module is connected with the output end of the gas flow sensing module.

Furthermore, the flow sensing module comprises a throttling piece, a high-pressure sensing element and a low-pressure sensing element, wherein the high-pressure sensing element, the throttling piece and the low-pressure sensing element are sequentially distributed along the flow direction of gas in the flow measuring pipe; the output end of the high-voltage sensing element and the output end of the low-voltage sensing element are respectively connected with the detection signal input end of the central processing module.

Furthermore, the flow measuring tube is in a single-blade hyperboloid structure with thick ends and thin middle parts, the throttling element is arranged at the position with the thinnest inner diameter of the flow measuring tube, the tube walls of the flow measuring tubes on two sides of the throttling element are respectively provided with a high-pressure tapping opening and a low-pressure tapping opening, the high-pressure sensing element is arranged in the high-pressure tapping opening, and the low-pressure sensing element is arranged in the low-pressure tapping opening.

Furthermore, the tank cover adopts a conical structure, a small opening of the tank cover and the guide pipe are integrally formed, and a large opening of the tank cover is connected with the tank body in a sealing mode.

Further, pipe and first pressure pipe are connected through coupling nut between, are equipped with tubaeform air channel in the coupling nut, and tubaeform air channel main aspects connect the pipe, and tubaeform air channel osculum is connected first pressure pipe.

Furthermore, sealing rubber gaskets are arranged between the tank body and the tank cover and between the horn-shaped vent groove and the guide pipe.

Furthermore, a fixing clamp for fixing external equipment is arranged outside the tank body, and a hinged nut is arranged at the bottom of the tank body.

Furthermore, the measuring mechanism also comprises a display dial, and the input end of the display dial is connected with the signal output end of the central processing module.

The invention also discloses a determination method based on the coal sample gas desorption amount determination device, which comprises the following steps:

A. equipment installation and verification: closing the valve, connecting the guide pipe with the first guide pipe, verifying the air tightness of the coal sample tank and each interface, and entering the next step if the air tightness is confirmed to be good;

B. coal sample reaction: collecting a coal sample and filling the coal sample into a coal sample tank, tightly covering the tank cover, and starting the reaction of the coal sample;

C. opening a valve to test a coal sample, and obtaining the gas desorption amount: the specific process is as follows:

c 1: the valve is blocked, and gas generated in the coal sample tank flows into the flow measuring pipe after passing through the guide pipe and the first pressure guiding pipe;

c 2: the high-pressure sensing element and the low-pressure sensing element detect the pressure difference change at two ends of the throttling element and transmit the pressure difference change to the central processing module, and meanwhile, desorbed gas is exhausted to the outside through the exhaust port;

c 3: the central processing module calculates the desorption amount and the gas loss amount of the gas in the coal sample tank according to the pressure difference change;

D. and closing the valve and finishing the test.

Further, the specific calculation process of the gas loss amount in the step c3 is as follows:

calculating the gas desorption volume in the standard state according to the gas desorption flow in the test time, wherein the calculation formula is as follows:

in the formula (1), V_t0Expressed in cm converted to the gas volume in the standard state³；V_tThe total amount of gas desorbed in cm within 2h measured underground³，P₁Representing downhole air pressure in kPa, t_wThe temperature in the sampling tank is expressed in unit;

by usingThe gas loss is calculated by the method, and the formula is as follows:

in the formula (2), a and b represent undetermined constants whenWhen, V_t0The value of a is the amount of gas lost as required.

The invention has the following beneficial effects:

(1) the coal sample tank and the flow measuring pipe are communicated with each other, so that the reaction and measurement of the gas desorption amount are integrated and intelligentized, the coal sample tank and the flow measuring pipe are directly communicated with the outside during desorption, the desorbed gas is directly discharged to the outside through the exhaust port, the gravity required to be overcome in the drainage link of the traditional drainage valve method is saved, meanwhile, the integrated structure saves a plurality of steps of the drainage valve and eliminates the influence of a plurality of factors of the underground operation environment, and the accuracy of the measurement result is greatly improved;

(2) the flow sensing module is arranged to comprise the throttling piece, the high-pressure sensing element and the low-pressure sensing element, and the desorption amount of the gas at different moments is measured by utilizing the pressure difference between the front and the back of the throttling piece, so that the structure is simple and firm, the performance is stable and reliable, and the service life is long;

(3) the flow measuring tube is arranged to be a single-blade hyperboloid structure with thick ends and thin middle parts, the throttling element is arranged at the position with the thinnest pipe diameter in the flow measuring tube, and the principle that the flow velocity is increased at the contraction position of the pipeline, the static pressure is reduced, and then the pressure difference is generated in the front and at the back of the throttling element, and the larger the gas flow is, the larger the generated pressure difference is, is utilized to further improve the pressure difference, and further improve the accuracy of the measuring result;

(4) the tank cover is arranged to be of a conical structure, and the tank cover and the guide pipe are integrally formed, so that gas is prevented from accumulating and generating eddy at the lower end of the guide pipe, the smoothness of gas flowing in the measuring process is ensured, and the accuracy of the measuring result is indirectly ensured;

(5) the trumpet-shaped vent groove is arranged, so that gas dissipation can be effectively prevented, and the accuracy of a measurement result is further improved;

(6) the measurement method integrally carries out the reaction and measurement by adopting the coal sample tank and the flow sensing module, realizes the integrated operation of the reaction and the measurement, greatly saves manpower, simplifies the measurement flow, and further effectively improves the measurement efficiency.

Drawings

FIG. 1 is a schematic view of the structure of an assay device according to the present invention;

FIG. 2 is a schematic view of the construction of the can body of FIG. 1;

FIG. 3 is a schematic view of the trumpet-shaped vent slot of FIG. 1;

fig. 4 is a schematic structural diagram of the flow sensing module of fig. 1.

Description of reference numerals:

1. a can body; 2. a can lid; 3. sealing the rubber gasket; 4. fixing the card; 5. a hinged nut; 6. a conduit; 7. a valve; 8. a connecting nut; 9. a horn-shaped vent channel; 10. a sealing gasket; 11. a first pressure leading pipe; 12. a second pressure leading pipe; 13. a flow measurement tube; 14. a high voltage sensing element; 15. a low voltage sensing element; 16. a display dial; 17. a central processing module; 18. an exhaust port; 19. a throttle member.

Detailed Description

The invention discloses a device for measuring the desorption amount of coal sample gas, which comprises a reaction mechanism and a measuring mechanism;

the reaction mechanism comprises a coal sample tank, a guide pipe 6 and a valve 7 arranged on the guide pipe 6, the upper end part of the coal sample tank is communicated with the air inlet end of the guide pipe 6, and the air outlet end of the guide pipe 6 is communicated with the measuring mechanism; the coal sample tank comprises a tank cover 2 and a tank body 1 which are arranged up and down, the lower end of the tank cover 2 is hermetically connected with the upper end of the tank body 1, and the upper end of the tank cover 2 is provided with an exhaust hole for communicating a guide pipe 6;

the measuring mechanism comprises a first pressure leading pipe 11, a flow measuring pipe 13, a second pressure leading pipe 12 and a central processing module 17, the first pressure leading pipe 11, the flow measuring pipe 13 and the second pressure leading pipe 12 are sequentially communicated, the air inlet end of the first pressure leading pipe 11 is communicated with the air outlet end of the conduit 6, a gas flow sensing module for measuring the gas flow is arranged in the flow measuring pipe 13, and the air outlet end of the second pressure leading pipe 12 is provided with an air outlet 18 for exhausting air outwards; the detection signal input end of the central processing module 17 is connected with the output end of the gas flow sensing module.

For a better understanding of the present invention, the technical solutions of the present invention are further described below with reference to the accompanying drawings.

As shown in FIG. 1, the present invention includes a reaction means and a measurement means provided on the left side of the reaction means.

As shown in fig. 1 and 2, the reaction mechanism includes a coal sample tank, a conduit 6, and a valve 7 disposed on the conduit 6, wherein an upper end of the coal sample tank is communicated with an air inlet end of the conduit 6, and an air outlet end of the conduit 6 is communicated with the measuring mechanism.

The gas guide mouth of traditional coal sample jar is sealed by sealed cushion 3 and is died, has guaranteed that its gas tightness is good, but the easy rubber pad of in-process puncture spicule of using is died, leads to the test to go on smoothly, consequently 7 control conduits 6 are adopted to this design, convenient easy operation.

Coal sample jar is including cover 2 and the can body 1 that set up from top to bottom, and cover 2 adopts the toper structure and with 6 integrated into one piece of pipe, and cover 2 osculum that is located the upper end is the exhaust hole that communicates with pipe 6 on cover 2 promptly, and 2 macrostoma of cover that are located the lower extreme inner wall is equipped with the internal thread, and the outer circumference of 1 upper end of can body is equipped with the external screw thread that matches with 2 internal threads of cover, realizes sealing connection through threaded connection between 2 macrostoma of cover and the can body 1.

The guide pipe 6 and the coal sample tank cover 2 are cast into a whole, so that gas is prevented from accumulating at the lower end of the guide pipe 6, the guide pipe can be directly communicated with the outside during desorption, and the gravity required for overcoming water in a drainage link is omitted.

In order to further improve sealing performance, be equipped with sealed cushion 3 on 1 external screw thread of can body, further guarantee the leakproofness between can body 1 and the cover 2, external sealed cushion 3 adopts the rubber material, and the leakproofness is strong, and the material easily acquires moreover, durable, low cost.

In order to facilitate installation, a hinged nut 5 for hinging external equipment is arranged at the bottom of the tank body 1, a fixing clamp 4 for fixing the external equipment is arranged on the tank body 1, and the measuring device can be flexibly hung in the process of underground gas desorption, so that reading is facilitated.

Survey mechanism includes that first pressure tube 11, flow survey buret 13, second pressure tube 12, central processing module 17 and display dial plate 16 are drawn to the pressure, and first pressure tube 11, flow survey buret 13 and second are drawn and are pressed pipe 12 and communicate in proper order, and first pressure tube 11 inlet end is passed through coupling nut 8 and is linked up 6 end of giving vent to anger of pipe.

Coupling nut 8 embeds has to be equipped with loudspeaker form air channel 9 in coupling nut 8, as 3 shows, 9 osculums of loudspeaker form air channel connect first to draw and press pipe 11 and with first to draw and press pipe 11 integrated into one piece, pipe 6 is given vent to anger and is held and be equipped with the external screw thread, 9 macrostoma of loudspeaker form air channel are equipped with the internal thread that matches 6 external screw threads of pipe, loudspeaker form air channel 9 passes through threaded connection pipe 6 and realizes sealing connection between the two, for further improving sealed effect, be equipped with seal ring 10 between preferred pipe 6 and the loudspeaker form air channel 9.

The flow measuring tube 13 is internally provided with a gas flow sensing module for measuring gas flow, the flow sensing module comprises a throttling piece 19, a high-pressure sensing element 14 and a low-pressure sensing element 15, and the high-pressure sensing element 14, the throttling piece 19 and the low-pressure sensing element 15 are sequentially distributed along the flow direction of gas in the flow measuring tube 13.

As shown in fig. 4, the flow measuring tube 13 is shaped as a single-blade hyperboloid structure with thick ends and thin middle, the throttle 19 is disposed at the position where the inner diameter of the flow measuring tube 13 is the thinnest, the tube walls of the flow measuring tube 13 at the two sides of the throttle 19 are respectively provided with a high pressure tapping and a low pressure tapping, the high pressure sensing element 14 is disposed in the high pressure tapping, and the low pressure sensing element 15 is disposed in the low pressure tapping.

The inlet end of the second pressure leading pipe 12 is communicated with the outlet of the flow measuring pipe 13, the outlet end of the second pressure leading pipe 12 is provided with an exhaust port 18 for exhausting outwards, and desorbed gas is directly exhausted to the outside from the exhaust port 18, so that water gravity required to be overcome in the traditional drainage link is omitted.

The output end of the high-pressure sensing element 14 and the output end of the low-pressure sensing element 15 are respectively connected with the detection signal input end of the central processing module 17, the output end of the central processing module 17 is connected with the signal input end of the display dial 16, the central processing module 17 calculates the pressure difference between the front and the back of the throttling element 19 according to the pressure values respectively measured by the output end of the high-pressure sensing element 14 and the low-pressure sensing element 15, then calculates the gas desorption amount and displays the gas desorption amount by the display dial 16, and the central processing module 17. It should be noted that the high voltage sensor element 14, the low voltage sensor element 15, the central processing module 17 and the display dial 16 are all intrinsic safety type designs to ensure the safety of the present invention in explosive environment.

The invention also discloses a determination method based on the coal sample gas desorption amount determination device, which comprises the following steps:

A. equipment installation and verification: and closing the valve 7, connecting the guide pipe 6 with the first guide pipe 6, selecting a safe position to fix the coal sample tank after the preparation work is completed, verifying the air tightness of the coal sample tank and each interface, and entering the next step if the air tightness is confirmed to be good.

B. Coal sample reaction: the coal sample is collected and put into a coal sample tank, the tank cover 2 is tightly covered, and the coal sample starts to react.

After the coal sample starts to react and the valve 7 is opened, the desorbed gas in the coal sample tank directly enters the first pressure guiding pipe 11, the flow measuring pipe 13 and the second pressure guiding pipe 12 along the guide pipe 6 in sequence.

C. And opening the valve 7 to test the coal sample and obtain the gas desorption amount.

The specific process is as follows:

c 1: the valve 7 is opened, and gas generated in the coal sample tank flows into the flow measuring pipe 13 through the guide pipe 6 and the first pressure leading pipe 11;

c 2: the high pressure sensing element 14 and the low pressure sensing element 15 detect the change of the pressure difference between the two ends of the throttling element 19 and transmit the change to the central processing module 17, and simultaneously, the desorbed gas is exhausted to the outside through the exhaust port 18;

c 3: the central processing module 17 calculates the desorption amount and the gas loss amount of the gas in the coal sample tank according to the pressure difference change.

Because the gas that the coal sample desorption in the coal sample jar flows into flow measurement buret 13, utilize high pressure sensing element 14 and low pressure sensing element 15 can detect the change of gas at flow measurement buret 13 internal pressure differential, and then form the signal of telecommunication and input singlechip, the gas desorption volume at different moments can be shown promptly to the display dial plate 16 that links to each other with the singlechip, and the staff can directly read the gas desorption volume of coal sample in the coal sample jar at different moments, gas desorption total amount and gas loss volume under the standard condition in the test time through display dial plate 16. The reaction time of the coal sample is about 2h, specifically, the reaction of the coal sample is started until the flow counts obtained by the high-pressure sensing element 14 and the low-pressure sensing element 15 are zero.

The specific calculation process of the gas loss is as follows:

calculating the gas desorption volume in the standard state according to the gas desorption flow in the test time, wherein the calculation formula is as follows:

in the formula (1), V_t0Expressed in cm converted to the gas volume in the standard state³；V_tThe total amount of gas desorbed in cm within 2h measured underground³，P₁Representing downhole air pressure in kPa, t_wThe temperature in the sampling tank is expressed in unit;

by using

The gas loss is calculated by the method, and the formula is as follows:

in the formula (2), a and b represent undetermined constants when

When, V_t0The value of a is the amount of gas lost as required. Before calculating the value of a, firstly

As the abscissa, by V_t0For the ordinate drawing, the CPU 17 will generally judge the display from the drawingAnd (4) automatically calculating the gas loss amount according to the coordinate values of the points according to the measuring points in the relationship of the relationship by a least square method.

D. The valve 7 is closed and the test is finished. After the test, screw up valve 7, take off coupling nut 8 and gas flowmeter, after the gas tightness of examining the coal sample jar again, send coal sample and flowmeter to the laboratory and handle and assay.

The method is simple to operate and convenient to carry, has important significance for improving the underground direct method for measuring the coal bed gas desorption amount, and has popularization value.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art that various changes, modifications and substitutions can be made therein without departing from the spirit and scope of the embodiments of the present invention.