MD-2 coal drilling cuttings gas desorption instrument

MD-2 coal drilling cuttings gas desorption instrument

MD-2 coal drilling cuttings gas desorption instrumentApplication Fields

Drilling at the underground stone gate and mining face, measuring the gas desorption indicators Δ h2 and K1 values of coal drill cuttings to determine the risk of coal and gas outburst in the working face.

MD-2 coal drilling cuttings gas desorption instrumentPrinciple construction

The principle of the coal drill cuttings gas desorption instrument is to release (desorb) gas into a closed space using the residual gas pressure (gas content) in the coal drill cuttings without artificially degassing and inflating the coal sample underground. The volume and pressure (expressed as water column pressure difference) of this space are used to characterize the amount of gas desorbed from the coal sample. The main body of MD-2 coal drill chip gas desorption instrument is made of a whole piece of organic glass processing. The instrument structure is shown in Figure 1, consisting of a water column meter 1, a desorption chamber 2, a coal sample bottle 3, a three-way stopcock 4, a two-way stopcock 5, etc. The external dimensions of the instrument are 270 × 120 × 34mm, and the weight is approximately 0.8kg

Coal drilling chip gas desorption instrumentTechnical parameters

Coal sample particle size: 1-3mm

Coal sample weight: 10g

Measurement indicators: Δ h2, K1

Differential pressure measured by water column gauge: 200mm water column

Instrument system error: ≤± 1.46%

Instrument accuracy: ± 1mm water column

Desorption of drill cuttingsIndicator determination

1. Desorption index of drill cuttings Δ h2

The desorption index of drill cuttings is the pressure difference reading of the desorption instrument water column gauge at the end of 2 minutes after the start of the measurement. This indicator does not require calculation and can be directly read from the water column of the desorption instrument

2. Desorption index K1 value

The desorption index K1 value is the cumulative gas desorption amount per gram of coal sample within 1 minute after the coal sample falls off and is exposed. Calculate according to the following formula: (1)

In the formula: Q - the cumulative gas desorption amount per gram of coal sample measured by the desorption instrument at t min after the start of coal sample desorption measurement, ml/g

Calculate the Q of MD-2 desorption instrument using the following formula:

Q=0.0821 △ h/10 (2)

0.0821- Structural constant of desorption instrument, ml/mm water column

10- Weight of coal sample, g

T - desorption measurement time, min

W1- Before the desorption measurement begins, the coal sample loses gas during the exposure time, ml/g

3- Coal sample exposure time, min

After measurement, first convert the reading of the water column meter to the desorption amount Q according to formula (2), and then use the 10 sets of data obtained from 10 minutes of desorption measurement to calculate K1 and W1 by plotting or multiplication

Coal drilling chip gas desorption instrumentDetermination of critical values for indicators

The critical values of the prominent hazard of the desorption indicators Δ h2 and K1 for drill cuttings should be determined based on the measured data of each coal seam. When there is no actual measurement data available, please refer to the data listed in the table below.

Coal drilling chip gas desorption instrumentPrecautions for measurement

1. The coal drill chip gas desorption instrument is equipped with 8 coal sample bottles, and the coal weight marked by the engraved line position on the coal sample bottles is 10g. To accurately calculate the Δ h value, after each coal sample desorption measurement, the coal sample bottle mouth can be plugged tightly with a rubber stopper or paper ball, and the coal sample weight can be weighed on the ground (the coal sample is in a natural dry state, and then the measured value can be corrected according to the following formula)

　

10

△h=—— △h′

G

In the formula: △ h ′ - pressure difference reading of the measured water column gauge of the downhole desorption instrument, mm water column

△ h - corrected desorption instrument water column gauge pressure difference reading, mm water column

G - Weigh the coal sample, g

2. The exposure time of coal samples is the time from the detachment of coal drill cuttings from the coal body to the start of desorption measurement

It can be calculated by the following formula:

In the formula: t0- coal sample exposure time, min

T1- The time required for coal drill cuttings to detach from the coal body and be discharged to the borehole opening, min

It can be estimated from the following equation:

L - Drilling depth during sampling, m

T2- the time from taking coal drill cuttings from the borehole to starting desorption measurement, min

The gas desorption instrument, gas pressure measuring instrument, geological gas desorption instrument, gas adsorption constant measuring instrument and other equipment produced by Zhengzhou Huazhi Technology Co., Ltd. have good quality, reasonable prices, and complete after-sales service. Welcome new and old customers to inquire and purchase. Consultation Hotline:

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Drilling requirements for MD-2 coal drill cuttings gas desorption instrument