SU1458596A1 - Method of detecting early stages of exogenous fires - Google Patents

Description

one

The invention relates to an automatic fire alarm and can be used in the coal industry to recognize exogenous fires at an early stage of their development,

The purpose of the invention is to increase the reliability of recognition of the source of exogenous fire for each generation.

The method for detecting early stages of exogenous fires includes the following operations: measure the speed of the air jet (v); the lateral dimensions of the excavation and determine the area of its cross section (s),

then, in the time interval of exogenous fire development, for example, 1–6 minutes with a one-minute tag, calculate an array of threshold values of CoHCO content () to recognize the source of exogenous fire in workings equipped with conveyor belts, using formula (1), and (2) - in the remaining workings:

SP

00

sd

with

65

Xa)

(

0.756

...

(ABOUT

1458596 i

K;, (P 0, .--. L / t); (2)

/

where (C), Kj.g (r) is the threshold content of carbon monoxide in the VNW treatment atmosphere at the ignition of rubber products and the ignition of wooden lining elements, respectively, 10 rel.

51; 0.756; 0.24; 0.91 - empirical coefficients, having size-% mol%.

. ° ™ - ad- -6.9 skg. with

ti:

kg

oh-y

ra te

from on to in and in

10 pax

Kg Ying

 rel. units, respectively;

ot is an empirical dimensionless coefficient, depending on the mass burnup rate of the material W, kg / s, and equal to

i.ge-io for W 0.001 kgf / s;

1.0 10 for W 0.001 kg / s;

  fuel loading of mine workings with wood and rubber products, kg / m;

20 x10 rel. units / min (0.1 ppm / min) - in the others, the actual content of carbon monoxide in the atmosphere of the controlled mine workings is measured and the adequacy of the measured values of the CO content of the threshold values is checked using statistical criteria establish, then the hypothesis of

LgCt);

4 (t)

the occurrence of a source of exogenous fire burnout time per unit of grain is accepted; otherwise,. surface production, mines, reject, ie, registered

Carbon monoxide measurements In this case, controlled atmosphere production is the product of a normal process, such as blasting.

1 {p and m. The process of recognition of fire is modeled in development with the following mining and technical characteristics, derevo, respectively;

the length of the combustion zone in the mine at time t, counted from the moment of the occurrence of the fire, m, wood, rubber, respectively;

Vc

t is the time of exogenous development: the angle of incidence is 5 degrees; cross section - arched; length 750 m; the lining is arched metal with a wooden pull ;, the size of the combustible load of lining (go) kg / m; length

45 perimeter of the tightened surface of the excavation (Pj) 9.3 m; burnout time of woodwork elements (65) 50 min; ventilation circuit - from top to bottom, installed in the belt

50 conveyor type КРУ-350 with rubber cable. with a tape of the RTLO-1500 type, 1.2 m wide. The size of the combustible load of the conveyor belt (gd) is 24 kg / m, and the burn-out time of the tape (Tdd) is 20 min.

At the time of increasing content

fire, min;

air jet speed in development, m / s; 8 - cross section-mountain

development m

The scope of dependencies (I) and (2) is limited to the early (initial) stage of exogenous fire development. The early (initial) stage of the development of a fire is characterized by a time interval, counting from the moment of occurrence of the fire, S pred. lakh which value of the flame front propagation velocity satisfies the condition. Q. v (T), 0.7 v, p, where is the limiting rate of fire spreading by generation, M / MINS

55

carbon monoxide at a rate of not less than 0.2 ppm / min (10 rel, v / u / min) counts the time of development of a possible source of exogenous fire in

6

Duration of free time.

develop fire t until the beginning of a comparative analysis, counting from

carbon monoxide build-up at a rate of at least 0.2-K) relative rpm / min in openings with belt conveyors and at least 0.1-10 rel, feed units / min in the rest, for a reliable process

Recognition using statistical criteria takes at least 5-6 minutes.

After analyzing the determination of Kgp by the formulas (1) or (2) in the same time interval of exogenous fire, starting from the moment of increasing the carbon monoxide content with a speed of at least O5 21 O rel. Ob, u, / / min (O, 2 ppm / min) in the workings with belt conveyors and at least O, 1

x10 rel. units / min (0.1 ppm / min) - in the others, the actual content of carbon monoxide in the atmosphere of controlled mine workings is measured and the adequacy of the measured values of the CO content in the array of threshold values is checked with the help of statistical criteria. then the hypothesis about

carbon monoxide at a rate of not less than 0.2 ppm / min (10 rel, v / u / min) counts the time of development of a possible source of exogenous fire in

the experimental coefficient “t 10 at W (r) 0.00 kg / s;

3IA58596

development and measurement of CO () 8l in the atmosphere of generation through each. (About a minute. The results of measurements are listed in Table I.g

In the place of production, where the air was taken for analysis and the content of CO, the velocity of the air jet Vg and the dimensions of the mine workings, which determine the cross section, are measured.

the purpose of obtaining reliable data on c. ..- ..

air volume flow. So, for 5uf-S - Bd () 3

Vf 2.0 m / s and S 9.3 m is the maximum burning speed of the conveyor belt.

L

(uo-io

at W (r) 0.001 kg / s;

(four)

threshold values of CO in the atmosphere of generation

XLO

bot7g

h

(five)

 1 JD 1 VUCnn / l 1 posgi; p11 G1,. 4, 65 m / min, and wood elements15 The results of the calculations were recorded in

 „„, 1 „/ deliver.....table 1. For example, calculated by the formulas

latch ifcjM / MHH -., .. h h Initially, it was assumed (1) - (b) for the moment in time i about the occurrence of the fire on

belt conveyor. K () - 0.102-6 - 0.017-36 + 1.453

Then, at intervals of 1 min, the A53;

each has six meanings:

the length of the combustion zone bd (G) on a belt conveyor by the known formulas:

B, (G-6) - A, (6) (, A53.16of- - 1,453-160 - 0.360 m;

L, () 4, (r) -16 (f -K (C). | 60b W (r.6) - zo 1o ° 7.2 ppm / s, -

ci 1,0.

51.1, о.1оЧ7о | 5- ° Зб ° Г.

K (T)

m

0.102T-0, OI7 J + 5.453;

(I)

3; (2)

to „(- b)

Mass tape burnout speed

wee)

(3)

the experimental coefficient “t 10 at W (r) 0.00 kg / s;

  8l (O

with. ..- ..

L

(uo-io

at W (r) 0.001 kg / s;

(four)

threshold values of CO in the atmosphere of generation

5uf-S - bd () 3

bot7g

h

(five)

. W (r.6) - ёо 1о ° ° 7

ci 1,0.

51.1, о.1оЧ7

thirty

to „(- b)

2-9.3

0.000658 vol., 58-10 rel. Ed.

Table I

Threshold values of CO in the atmosphere of production during development

K (g + JF S t

lower boundary of the area of adequacy. co - oet measured values of CO (H) threshold

 Kj. (R) known in mathematical where Kgp (T) ppa. H .о () гллн ®

statistics formula: CO content in the atmosphere of production in

calculated the value of Kjo (r). and

I / - /, -, S grv. “J

co) gro, l FOR a moment in time "

 6 at N 6 and made the calculated table.2.

I

time instant of fire development, forming the upper and lower limits of the region of adequacy, respectively, by threshold values

F - Fisher criterion (taken by; g

the tables given in reference books K, (0.82 + 1.08 + 2.14 + + according to mathematical statistics), Do1; in the case under consideration, the tabular (critical) value Fy

RTT is the residual standard deviation of the expected CO boundary values relative to threshold values, determined from the formulas ig lamgs known from mathematical statistics,

+ 4.78 + 6.58) -18.7 3.12m

ten

rel, obed ..

T. blitz Calculated table

T

J GK, (C) Kc

osg

N-rl- t ..

one ,

(7) 20

de N number of analyzed points

measurement, DIT, (ex: - analysis of the recognition of the fire on

belt conveyor N 6); Kjp is an average of 25 threshold values, determined by the odds;

TO

With

i-l

(eight)

one""

(

The results of calculations by formulas (b) (8) are tabulated in aa.Z. For example,

T b -T

. 25,172

K. (),; - 6.58 fs, 19 2.24 11.7. 10 relative units

 cn

K “(; 6) 6.58 - G5; 19 2.24 1.5

 6

10 relative units

This table 3 The table of the granular values of the content of CO in developed fires on a conveyor belt

the value of kjo (r). and

gry. "j

FOR THE TIME OF TIME

 6 and made the calculated

I

K, (0.82 + 1.08 + 2.14 +

+ 4.78 + 6.58) -18.7 3.12m

, 82 + 1.08 + 2.14

ten

rel, obed ..

T. blitz 2 Calculation table

T

J GK, (C) Kc

25,172

four

2j24 10 rel.

 6

10 relative units

Continuation of table 3

45

1.1 1.4

About 1.5

After six minutes from the moment of the beginning of the growth of the CO content, with a rate equal to or greater than 0.2 - 55 relative units / min, they were checked from -. measured data (see tab. 3) on the condition;

Ксо (г-) гро. „I со (с)) Jp.«, (9)

9145

Since the test invented met the requirements of the conditions (9), it was concluded that the occurrence of the fire on the conveyor belt.

If even one of the six measurements did not meet the requirements of conditions (9), an assumption would be made about the occurrence of a fire on the wooden lining elements, and the initial assumption about the ignition of the conveyor belt would be rejected. For this case, six values were calculated with an interval of 1 min:

the length of the combustion zone Lp () on wood support elements according to the well-known formula :. ... -

(j ;.), .3- (J (5-br / -b (105/1 - 105), m

(ten)

20

Upper and lower boundaries of the area

relations are calculated by the formulas

the threshold values of the content (s) (gg) are only the values of N - 0 and

in the atmosphere of work, 07. The process of calculating the new La () 25 den in the calculation table. 5 and 6.

 i-eOtB Table

() Calculated table

The results of the calculations were summarized in table 4. For example, the calculations were performed using formulas (10) and (11) for a time point of 1 min:

Lfl () 14: 3 l.M (5-H) -n (105) - - 105) 0.009 m;

. -n -4fr-:

 0.0000152% by volume of CO 0.152

ten

relative units

Table Threshold values of CO in the atmosphere of the mine during the development of fire on the wooden elements of the lining

1 ft HHH-6

. to 1.633. 10 relative units

gp10

  j ----. 20.287 1.5. 10 relative units

ten

Continuation of table.4 I

(ten)

20

Upper and lower boundaries of the area

Table

The table of boundary values of the content of CO in the development of fire on wooden elements lining

In this case, all 10 measurements of the content corresponded to condition (9), therefore, it was concluded that a source of fire had arisen on lining elements. If condition less than nine out of ten measurements were satisfied with condition (9), then the reason for the growth of CO in the atmosphere of production in this case would be technological interference, for example, blasting, filling the transport chain with loose coal, etc.

Claims (1)

1. A method for detecting early stages of exogenous fires, including monitoring the microconcentration content of carbon monoxide in a mine atmosphere, measuring air velocity, temperature and smoke production, recording the current time of change of monitored parameters, conducting a comparative analysis of the actual carbon monoxide content and speed its variation with respect to the corresponding values, characterized in that. in order to increase the reliability of recognition of the source of exogenous fire for each production, before comparative analysis, the transverse dimensions of production and the time of development of the exogenous fire are determined, and then the expected values of carbon monoxide content are determined by the formulas: G P K,. ,,, ..., Cft ..; V 8 upon ignition of wooden lining elements TO   4Ct 0.91 soy) -605 V, empirical coefficients having the dimension of m vol.%  cdc m 3 13 vol.% AT 1 ° ™ D So145859 Sh kg with responsibly; i is an empirical dimensionless coefficient depending on the mass burn-up rate of the material; g - fuel loading of mine workings, kg / m;  - time of burnout of the material per unit surface of the mine, min; t - time of exogenous development fire, min; (t) is the length of the combustion zone in the mine at the time t, counted from the moment of the occurrence of the fire, m; .20 v is the speed of the air jet in the formulation, m / s; 15 Sh 20 15 14 . S is the cross-section of generation, m the indices a and l relate sor. responsible for loading Wood and rubber products (tapes), then statistically compare the arrays of expected calculations; the actual values of the carbon monoxide content and determine the presence of a source of exogenous fire in the generation when they coincide. 2, the method according to claim 1, characterized in that the time for the development of an exogenous fire is counted from. the beginning of the increase in carbon monoxide at a rate of at least Yu 212l25l spruce ABOUT, min -, and in mining with belt conveyors - at least 0, relative rpm / min.