CN118052025A - Method for determining length extremum of downstream inclined shaft of purification ventilation system for slag transportation process of inclined shaft - Google Patents

Abstract

The application discloses a method for determining the length extremum of a downstream inclined shaft of a purification ventilation system for the slag transportation process of the inclined shaft, wherein an air purifier is arranged in the inclined shaft, two ends of the air purifier are respectively provided with an induced air section and an injection section, the induced air section is arranged opposite to the bottom of the inclined shaft, the injection section is arranged opposite to an inlet of the inclined shaft, and upstream air flow, air flow to be purified, purified air flow and unpurified air flow realize the split flow and the confluence flow of the air flow through the induced air section and the injection section of the air purifier; the calculation formula of the length extremum of the downstream inclined shaft is as follows: Wherein: q ₀ is the back flow sewage wind volume of the tunnel face, and m ³/s; c=c/delta is the integral influence factor of smoke flow and the factor ratio number of the designed concentration, m ²/s; delta is the allowable smoke concentration of ventilation design, m ^‑1; c is the comprehensive influence coefficient of smoke flow, m/s; l ₁ is the distance upstream of the inclined shaft, m; e is the wind dividing ratio and dimensionless number; η is the smoke dust removal efficiency of the air purifier,%; Distance loss for diluting the back flow sewage wind of the tunnel face; delta ₀ is the smoke concentration of the face return sewage at the bottom of the inclined shaft, m ^‑1. The invention can rapidly and rapidly determine the extreme value of the length of the inclined shaft at the downstream of the purification ventilation system in the slag conveying process of the inclined shaft.

Description

Method for determining length extremum of downstream inclined shaft of purification ventilation system for slag transportation process of inclined shaft

Technical Field

The invention belongs to the technical field of tunnel construction ventilation, and particularly relates to a method for determining a length extremum of a downstream inclined shaft of a purification ventilation system for an inclined shaft slag conveying process.

Background

Along with the vigorous development of highway transportation industry and high-speed railway construction, the construction scale of the tunnel in the extra-long mountain is continuously enlarged; in order to ensure the construction progress and the construction efficiency, when the single-hole tunneling mileage is too long, a plurality of tunnel faces are opened up by adopting a vertical shaft or an inclined shaft for tunneling in a split mode.

The inclined shaft is a channel and a throat constructed in a long tunnel hole, and is used for carrying slag, entering and exiting equipment and personnel, transporting building materials, ventilating and draining. Plays a critical role in the economy, safety and efficiency of the whole engineering.

In the process of the inclined shaft slag conveying, the current domestic tunnel inclined shaft slag conveying modes mainly comprise rail slag conveying, rail slag loading, rail conveying and the like.

In the inclined shaft rail lifting slag conveying mode, a mining winch lifts the slag conveying of the mine car connected in series, and the opening of the mine car is subjected to unhooking and marshalling operation. For a longer steep slope inclined shaft, from the conventional construction experience, equipment investment is large, unsafe factors are large, construction links are numerous, auxiliary facilities are large, and mine car lifting capacity limits the construction progress of tunnel excavation to influence the construction period. The trackless transportation mode of the automobile slag conveying feeding has the characteristics of convenient, simple and flexible construction, high construction speed, less equipment investment and wide application range of slag conveying equipment. In addition, the problem that the rail-free automobile slag transportation is mainly carried out by diesel engines due to various types of vehicle engines, toxic gases are discharged in the high-frequency operation process, and secondary dust and dirty air discharged from a main hole caused by slag transportation are collected in an inclined shaft still lacks an effective solution. The potential risk is brought to the slag handling process due to the low visibility in the inclined shaft caused by the accumulation of pollutants.

The wet dust removal air purifier aims at solving the problems existing in the prior art, and simultaneously combines the problems of high smoke concentration, low visibility, poor air quality and the like in the conventional tunnel inclined shaft slag conveying process. Then, the smoke dust concentration in the inclined shaft is influenced by factors such as vehicle type, vehicle flow density and the like, and has an important relation with the length of a tunnel at the upstream and downstream of the inclined shaft, but a method for determining the length extremum of the inclined shaft at the downstream of a purification ventilation system for the slag transportation process of the inclined shaft is not formed.

The patent number ZL201810902148.2 discloses a downstream tunnel length extremum method for closed controllable circulation ventilation of a super-long highway tunnel; the patent number ZL201810903665.1 discloses an upstream tunnel length extremum calculating method for controllable circulation ventilation of a super-long highway tunnel; patent No. ZL201810903617.2 discloses a tunnel short-channel length extremum calculating method for a circulating ventilation system of a super-long highway tunnel. The method is mainly applied to a highway tunnel closed type controllable circulating ventilation system in operation, and a tunnel transverse hole with a circulating air duct can rapidly and rapidly complete the pre-evaluation of the installation position of an air purifier in the closed type circulating ventilation system, the length of the circulating air duct and the like. However, in the operation of transporting slag in the inclined shaft in the tunnel construction process, the concentration of smoke dust in the inclined shaft is affected by the backflow of the sewage wind on the face, and the calculation method of the invention is not mentioned, so that the invention is not suitable for the pre-evaluation of a purification ventilation system in the operation of transporting slag in the inclined shaft.

Disclosure of Invention

In order to solve the problems, the invention provides a method for determining the length extremum of a downstream inclined shaft of a purification ventilation system for a slag conveying process of the inclined shaft, so as to quickly and quickly determine the length extremum of the downstream inclined shaft.

The technical scheme adopted by the invention is as follows:

An air purifier is arranged in the inclined shaft, two ends of the air purifier are respectively provided with an induced draft section and an injection section, the induced draft section is arranged opposite to the bottom of the inclined shaft, and the injection section is arranged opposite to an inlet of the inclined shaft; the purifying and ventilating system is provided with an upstream air flow, an air flow to be purified, a purified air flow, a non-purified air flow and a downstream air flow; the upstream air flow is mixed air flow of the back flowing sewage air of the face and flowing air in the installation position of the inclined shaft bottom to the air purifier, the air flow to be purified is a part of the upstream air flow entering the air purifier, the purified air flow is the air flow purified by the air purifier, and the unpurified air flow is a part of the upstream air flow which does not enter the air purifier; the upstream air flow, the air flow to be purified, the purified air flow and the unpurified air flow are split and combined through the air inducing section and the injection section of the air purifier; the calculation formula of the length extremum of the downstream inclined shaft is as follows:

wherein: q ₀ is the back flow sewage wind volume of the tunnel face, and m ³/s; c=c/delta is the integral influence factor of smoke flow and the factor ratio number of the designed concentration, m ²/s; delta is the allowable smoke concentration of ventilation design, m ^-1; c is the comprehensive influence coefficient of smoke flow, m/s; l ₁ is the distance upstream of the inclined shaft, m; e is the wind dividing ratio and dimensionless number; η is the smoke dust removal efficiency of the air purifier,%; Distance loss for diluting the back flow sewage wind of the tunnel face; delta ₀ is the smoke concentration of the face return sewage at the bottom of the inclined shaft, m ^-1.

In one embodiment, the calculation formula of the smoke flow integrated influence coefficient C is:

Wherein: q _VI is the reference emission amount of smoke dust, m ²/(veh·km);f_a(VI) is the vehicle condition coefficient considering the smoke dust, and the dimensionless number is zero; f _d is a vehicle density coefficient and is a dimensionless number; f _h(VI) is the altitude coefficient of the smoke and dust, and is dimensionless; f _iv(VI) is a dimensionless number considering the longitudinal slope-vehicle speed coefficient of smoke; n _D is the model class number and dimensionless number of the diesel vehicle; n _m is the traffic volume, veh/h of the corresponding vehicle type; and f _m(VI) is a model coefficient of the diesel vehicle taking smoke and dust into consideration, and is a dimensionless number.

In one embodiment, the obtaining process of the downstream inclined shaft length extremum calculation formula includes the following steps:

1) Calculating the upstream smoke flow of the inclined shaft, wherein the calculation formula is as follows:

Wherein: q _VI is the upstream smoke flow of the inclined shaft, m ²/s;q_VI is the reference smoke emission, and m ²/(veh·km);f_a(VI) is the vehicle condition coefficient considering smoke, and dimensionless number; f _d is a vehicle density coefficient and is a dimensionless number; f _h(VI) is the altitude coefficient of the smoke and dust, and is dimensionless; f _iv(VI) is a dimensionless number considering the longitudinal slope-vehicle speed coefficient of smoke; n _D is the model class number and dimensionless number of the diesel vehicle; n _m is the traffic volume, veh/h of the corresponding vehicle type; f _m(VI) is the model coefficient of the diesel vehicle taking the smoke dust into consideration, and is a dimensionless number; l is the length of the inclined shaft, m;

In the formula (1), when the standard emission amount is unchanged, and the dimensionless number of the vehicle condition, the vehicle density, the gradient, the vehicle speed and the diesel vehicle type is unchanged and the influence caused by the change of the altitude can be ignored, the inclined shaft smoke flow is a function of the inclined shaft length and the comprehensive influence factor; wherein, the calculation formula of the comprehensive influence factor is:

Wherein: c is the comprehensive influence factor of smoke flow, m/s;

2) Calculating the smoke concentration of upstream wind flow, applying formulas (1) and (2), and setting the length of the upstream inclined shaft to be L ₁, mixing

The calculation formula of the upstream wind flow smoke dust concentration of the return sewage wind of the face is as follows:

Wherein: delta ₁ is the smoke concentration of the upstream wind flow, m ^-1;L₁ is the upstream inclined shaft length, m; q ₀ is the flow rate of the back-flowing sewage wind of the tunnel face, m ³/s;δ₀ is the concentration of the back-flowing sewage wind and smoke of the tunnel face, m ^-1;Q_A(VI) is the flow rate of smoke at the upstream of the inclined shaft, m ²/s;Q_1(VI) is the flow rate of smoke newly added at the upstream section of the inclined shaft, m ²/s;Q_0(VI) is the flow rate of the back-flowing sewage wind of the tunnel face, and m ²/s;

3) The wind dividing ratio is calculated, and the calculation formula is as follows:

Wherein: e is the wind dividing ratio and dimensionless number; q _B1 is the circulating air flow volume which is shunted to the air inducing section of the air purifier, and m ³/s;

according to the principle of conservation of mass, the air volume of the air flow which does not enter the air purifier is:

Q_B2＝(1-e)·Q₀ (5)

Wherein: q _B2 is the air quantity of the air flow which does not enter the air purifier, and m ³/s;

4) Calculating the concentration of smoke dust not entering the air flow of the air purifier:

the flow smoke flow calculation formula of the wind flow smoke flow which does not enter the ceiling wet type air purifier is as follows:

Q_C2(VI)＝Q_B2(VI)＝δ₁Q_B2＝δ₁Q_C2 (6)

Wherein: q _B2、Q_C2 is the air quantity of the unpurified air flow, m ³/s; q _B2＝Q_C2;Q_B2(VI)、Q_C2(VI) is the smoke flow which does not enter the air flow of the ceiling wet type air purifier, and m ²/s; because the length of the air purifier is far smaller than that of the inclined shaft, the flow of the smoke dust added at the bottom of the suspended ceiling wet type air purifier is negligible, and therefore, Q _B2(VI)＝Q_C2(VI) exists;

Substituting the formula (5) into the formula (6) to obtain:

Q_C2(VI)＝Q_B2(VI)＝δ₁(1-e)Q₀ (7)

5) Calculating the concentration of smoke dust which is converged by the purified circulating air flow and the air flow which does not enter the air purifier:

The wind flow flowing through the suspended ceiling wet type air purifier arranged in the inclined shaft is the purified circulating wind flow, and the smoke flow in the wind flow is as follows:

Q_C1(VI)＝δ₁Q_B1(1-η) (8)

substituting formula (4) into formula (8) to obtain:

Q_C1(VI)＝δ₁·Q₀·e·(1-η) (9)

according to the basic principle of physics, the concentration of the flue gas when the purified circulating air flow is combined with the air flow which does not enter the air purifier is as follows:

Substituting the formula (7) and the formula (9) into the formula (10) to obtain:

δ₂＝δ₁·(1-e·η) (11)

Wherein: delta ₂ is the smoke concentration where the two streams meet, m ^-1;

6) Calculating the accumulated smoke concentration of the downstream wind flow:

newly increased smoke flow generated by pollutant emission of vehicles running in a downstream inclined shaft is:

Q_3(VI)＝C·L₃ (12)

Wherein: q _3(VI) is the newly added smoke flow of the downstream wind flow, m ²/s;L₃ is the length of the downstream inclined shaft through which the downstream wind flow flows, and m;

The accumulated smoke flow of the downstream wind flow in the downstream of the inclined shaft is from two parts, namely the smoke flow brought by merging the purified circulating wind flow and the airflow which does not enter the air purifier, and the smoke flow of the newly added downstream wind flow; thus, the downstream wind flow accumulates the smoke concentration as:

wherein: delta ₃ is accumulated downstream wind flow smoke concentration, m ^-1;Q_E(VI) is downstream wind flow smoke flow, m ²/s;

substituting the formula (11) and the formula (12) into the formula (13) to obtain:

7) Calculating the length extremum of the downstream inclined shaft:

When the allowable smoke dust concentration of the inclined shaft ventilation design is delta and delta ₂＜δ₃ is less than or equal to delta, the ventilation design requirement is met, and the ventilation design method comprises the following steps of:

Wherein: delta is the allowable smoke concentration of ventilation design, m ^-1;

If and only if δ ₃ =δ, to meet the inclined shaft ventilation design smoke concentration requirement, then the downstream inclined shaft length has a limit value L _3c; substituting L ₃ for L _3c in equation (14), the term is shifted from equation (14):

Wherein: l _3c is the downstream slant well length, m, when δ ₃ =δ;

And (3) further finishing the formula (16) to obtain:

wherein: c=c/delta is the integral influence factor of smoke flow and the factor ratio number of the designed concentration, m ²/s; to dilute the distance loss of the back flow of the sewage wind on the face.

In one embodiment, the determining the downstream inclined shaft length extremum includes the following steps:

obtaining the values of the upstream inclined shaft length, the smoke dust removal efficiency of the air purifier, the wind dividing ratio, the return air quantity of the face, the dependent variable ratio number and the distance loss of the return air of the diluted face;

substituting the numerical values into a formula (17) for calculation to obtain the length extremum of the downstream inclined shaft.

In one embodiment, the air purifier is a suspended ceiling wet air purifier that is mounted above the interior of the inclined shaft.

Compared with the prior art, the invention has the beneficial effects that:

the invention can be used for extremum of the length of the downstream inclined shaft of the purification and ventilation system in the slag conveying process of the inclined shaft, can avoid complicated calculation of dimensional number parameters such as the length of the inclined shaft, the section scale and the like, or network calculation of the ventilation system, or complex and time-consuming calculation fluid dynamic numerical simulation, rapidly and rapidly determine the extremum of the length of the downstream inclined shaft of the purification and ventilation system in the slag conveying process of the inclined shaft, further rapidly and rapidly calculate the maximum length of the downstream inclined shaft allowed by wind consumption on the premise of a certain length of the upstream inclined shaft, and can evaluate whether to set an air purifier again or evaluate the installation position of the suspended ceiling wet dust removal air purifier on the basis.

Drawings

FIG. 1 is a schematic diagram of a method for determining an extreme value of a length of a down-stream inclined shaft of a purification ventilation system for an inclined shaft slag transportation process according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of the influence of the wind splitting ratio on the length extremum of the lower inclined shaft in the method for determining the length extremum of the lower inclined shaft in the embodiment of the invention (the flow rate of the back flow sewage wind of the face is 20m ³/s, and the factor ratio is 0.06m ²/s).

FIG. 3 is a schematic diagram of the influence of the wind splitting ratio on the length extremum of the downstream inclined shaft (the flow rate of the back-flowing sewage wind of the face is 20m ³/s, and the factor ratio is 0.07m ²/s) in the method for determining the length extremum of the downstream inclined shaft according to the embodiment of the invention.

FIG. 4 is a schematic diagram of the influence of the wind splitting ratio on the length extremum of the downstream inclined shaft (the flow rate of the back-flowing sewage wind of the face is 30m ³/s, and the factor ratio is 0.06m ²/s) in the method for determining the length extremum of the downstream inclined shaft according to the embodiment of the invention.

FIG. 5 is a schematic diagram of the influence of the wind splitting ratio on the length extremum of the lower inclined shaft in the method for determining the length extremum of the downstream inclined shaft according to the embodiment of the invention (the flow rate of the back-flowing sewage wind of the face is 30m ³/s, and the factor ratio is 0.07m ²/s).

In the figure: 0. the bottom of the inclined shaft, the upstream of the inclined shaft, the air purifier, the induced draft section of the air purifier, the downstream of the inclined shaft, the inlet of the inclined shaft, A, upstream wind flow, B ₁, to-be-purified wind flow, B ₂, unpurified wind flow, C ₁, purified wind flow, C ₂, unpurified wind flow, D, mixed wind flow, E, downstream wind flow.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

As shown in FIG. 1, in the embodiment of the invention, a suspended ceiling wet type air purifier 2 is arranged in a purification ventilation system for a slag conveying process of an inclined shaft, the air purifier is arranged above the inside of the inclined shaft, the air purifier is respectively provided with an induced air section 2-1 and an injection section 2-2 according to the two functional ends, the induced air section 2-1 of the air purifier is arranged opposite to the bottom 1 of the inclined shaft, and the injection section 2-2 is arranged opposite to an inlet 4 of the inclined shaft.

When the purification ventilation system operates, the tunnel face backflow sewage wind is introduced through the bottom 0 of the inclined shaft and mixed with the wind flow in the upstream 1 of the inclined shaft to become an upstream wind flow A. Part of the upstream air flow A flows into an equipment air inducing section 2-1, under the action of the suspended ceiling wet type air purifier 2, the air flow B ₁ to be purified passes through the air purifier 2 to remove dust and other particle pollutants, so that purification treatment is obtained, and the air flow B ₁ flows out through the suspended ceiling wet type air purifier injection section 2-2 and is converted into purified air flow C ₁. Part of the polluted air B ₂ which does not enter the suspended ceiling wet type air purifier is moved to the inclined shaft inlet from the lower part of the air purifier to form an unpurified air flow C ₂, and the unpurified air flow C ₁ is mixed with the purified air flow C ₁ to form a diluted mixed air flow D, and the mixed air flow D continuously dilutes pollutants in the downstream air flow E. When designing and constructing the purification and ventilation system, it is necessary to ensure that the concentration of the pollutant in the downstream 3 of the inclined shaft (downstream refers to the space between the air purifier and the next air purifier or the inlet of the inclined shaft, that is, if another air purifier is further provided between the air purifier and the inlet of the inclined shaft, the downstream refers to the space between the air purifier and the next air purifier, and if no other air purifier is provided between the air purifier and the inclined shaft, the downstream refers to the space between the air purifier and the inlet of the inclined shaft) is kept within a prescribed safety value, thereby ensuring that the air consumption needs.

In the embodiment of the invention, the method for determining the length extremum of the downstream inclined shaft comprises the following specific processes.

1) According to the existing engineering calculation method, a smoke flow calculation formula is obtained, and the specific operation is as follows:

Wherein: q _VI is the upstream smoke flow of the inclined shaft, m ²/s;q_VI is the reference smoke emission, and m ²/(veh·km);f_a(VI) is the vehicle condition coefficient considering smoke, and dimensionless number; f _d is a vehicle density coefficient and is a dimensionless number; f _h(VI) is the altitude coefficient of the smoke and dust, and is dimensionless; f _iv(VI) is a dimensionless number considering the longitudinal slope-vehicle speed coefficient of smoke; n _D is the model class number and dimensionless number of the diesel vehicle; n _m is the traffic volume, veh/h of the corresponding vehicle type; f _m(VI) is the model coefficient of the diesel vehicle taking the smoke dust into consideration, and is a dimensionless number; l is the length of the inclined shaft, m;

In the formula (1), when the reference emission amount is unchanged, and the dimensionless number of the vehicle condition, the vehicle density, the gradient, the vehicle speed and the diesel vehicle type is unchanged, and the influence caused by the change of the altitude can be ignored, the inclined shaft smoke flow is a function of the inclined shaft length and the comprehensive influence factor. Wherein, the calculation formula of the comprehensive influence factor is:

Wherein: c is the comprehensive influence factor of smoke flow and m/s.

2) Smoke concentration calculation of upstream wind flow:

applying formulas (1) and (2) and setting the length of the upstream inclined shaft as L ₁, and mixing the calculation formula of the concentration of the smoke of the upstream wind flow of the back flow sewage wind of the tunnel face as follows:

Wherein: delta ₁ is the smoke concentration of the upstream wind flow, m ^-1;L₁ is the upstream inclined shaft length, m; q ₀ is the flow rate of the back-flowing sewage wind of the tunnel face, m ³/s;δ₀ is the concentration of the back-flowing sewage wind and smoke of the tunnel face, m ^-1;Q_1(VI) is the flow rate of the newly added smoke at the upstream section of the inclined shaft, m ²/s;Q_0(VI) is the flow rate of the back-flowing sewage wind of the tunnel face, and m ²/s;

3) The wind dividing ratio is calculated by the following specific formula:

Wherein: e is the wind dividing ratio and dimensionless number; q _B1 is the circulating air flow volume which is shunted to the air inducing section of the air purifier, and m ³/s;

according to the principle of conservation of mass, the air volume of the air flow which does not enter the air purifier is:

Q_B2＝(1-e)·Q₀ (5)

Wherein: q _B2 is the air quantity of the air flow which does not enter the air purifier, and m ³/s.

4) Calculation of smoke concentration of wind flow not entering the air purifier:

The smoke that does not enter the air cleaner flow comes from the smoke carried by the upstream flow.

Wherein, influence not get into furred ceiling wet-type air purifier wind flow smoke and dust flow calculation formula as follows:

Q_C2(VI)＝Q_B2(VI)＝δ₁Q_B2＝δ₁Q_C2 (6)

Wherein: q _B2、Q_C2 is the air quantity of the unpurified air flow, m ³/s; q _B2＝Q_C2;Q_B2(VI)、Q_C2(VI) is the smoke flow which does not enter the air flow of the ceiling wet type air purifier, and m ²/s; because the length of the air purifier is far smaller than that of the inclined shaft, the flow of the smoke dust added at the bottom of the suspended ceiling wet type air purifier is negligible, and therefore, Q _B2(VI)＝Q_C2(VI) exists.

Substituting the formula (5) into the formula (6) to obtain:

Q_C2(VI)＝Q_B2(VI)＝δ₁(1-e)Q₀ (7)

5) And (3) calculating the concentration of smoke which is formed by merging the purified circulating air flow and the air flow which does not enter the air purifier:

The wind flow flowing through the suspended ceiling wet type air purifier arranged in the inclined shaft is the purified circulating wind flow, and the smoke flow in the wind flow is as follows:

Q_C1(VI)＝δ₁Q_B1(1-η) (8)

substituting formula (4) into formula (8) to obtain:

Q_C1(VI)＝δ₁·Q₀·e·(1-η) (9)

according to the basic principle of physics, the concentration of the flue gas when the purified circulating air flow is combined with the air flow which does not enter the air purifier is as follows:

Substituting the formula (7) and the formula (9) into the formula (10) to obtain:

δ₂＝δ₁·(1-e·η) (11)

Wherein: delta ₂ is the smoke concentration where the two streams meet, m ^-1.

6) Downstream wind flow cumulative soot concentration calculation:

newly increased smoke flow generated by pollutant emission of vehicles running in a downstream inclined shaft is:

Q_3(VI)＝C·L₃ (12)

Wherein: q _3(VI) is the newly added smoke flow of the downstream wind flow, m ²/s;L₃ is the length of the downstream inclined shaft through which the downstream wind flow flows, and m;

The accumulated smoke flow of the downstream wind flow in the downstream of the inclined shaft is from two parts, namely the smoke flow brought by merging the purified circulating wind flow and the airflow which does not enter the air purifier, and the smoke flow of the newly added downstream wind flow; thus, the downstream wind flow accumulates the smoke concentration as:

wherein: delta ₃ is accumulated downstream wind flow smoke concentration, m ^-1;Q_E(VI) is downstream wind flow smoke flow, m ²/s;

substituting the formula (11) and the formula (12) into the formula (13) to obtain:

7) Calculating the length extremum of the downstream inclined shaft:

When the allowable smoke dust concentration of the inclined shaft ventilation design is delta and delta ₂＜δ₃ is less than or equal to delta, the ventilation design requirement is met, and the ventilation design method comprises the following steps of:

Wherein: delta is the allowable smoke concentration of ventilation design, m ^-1;

If and only if δ ₃ =δ, to meet the inclined shaft ventilation design smoke concentration requirement, then the downstream inclined shaft length has a limit value L _3c; substituting L ₃ for L _3c in equation (14), the term is shifted from equation (14):

Wherein: l _3c is the downstream slant well length, m, at δ ₃ =δ.

Equation (16) shows that after the downstream inclined shaft length is equal to or greater than the extremum, the downstream wind flow smoke concentration of the downstream inclined shaft exceeds the allowable concentration and the vehicle continuing to travel in the downstream inclined shaft is unsafe.

And (3) further finishing the formula (16) to obtain:

wherein: c=c/delta is the integral influence factor of smoke flow and the factor ratio number of the designed concentration, m ²/s; to dilute the distance loss of the back flow of the sewage wind on the face.

Formula (17) shows that the length extremum of the downstream inclined shaft is inversely proportional to the upstream length and the factor ratio of the inclined shaft, and the length extremum of the downstream inclined shaft is directly proportional to the return air quantity, the air dividing ratio and the purification efficiency of the air purifier.

8) The method comprises the steps of obtaining the values of the upstream inclined shaft length, the smoke dust removal efficiency of the air purifier, the wind dividing ratio, the back flow air quantity of the tunnel face, the factor ratio number and the distance loss of the back flow air of the diluted tunnel face, and further obtaining the downstream inclined shaft length extremum by calculation, wherein the specific operation is as follows:

a) Setting the return sewage wind volume of the tunnel face to be 20m ³/s and 30m ³/s respectively;

b) In the invention, the standard of Highway tunnel ventilation design rule is referred to, and the set factor ratio is respectively 0.06m ²/s and 0.07m ²/s;

c) Setting the distance loss of the back flow sewage wind of the tunnel face to be 20m;

d) Setting the purification efficiency of the air purifier to be 0.95 and setting the wind dividing ratio range to be 0.0-1.0;

e) Setting upstream inclined wells as 50m, 100m, 150m, 200m and 250m respectively;

f) Substituting the numerical values into a formula (17) for calculation to obtain the length extremum of the downstream inclined shaft. Fig. 2 to 5 are schematic diagrams showing the influence of the wind splitting ratio on the length extremum of the inclined shaft.

By analyzing the specific embodiments, the following generalizations can be made: ① Along with the increase of the wind dividing ratio, the length of the downstream inclined shaft is increased; along with the increase of the return air quantity of the sewage on the tunnel face, the extreme value of the downstream inclined shaft increases; ② In the range of large factor ratio and small wind dividing ratio, when the length of the upstream inclined shaft is longer, the length of the downstream inclined shaft is negative, which indicates that the overlong length of the upstream inclined shaft inevitably leads to the exceeding of the smoke dust concentration in the tail end of the downstream inclined shaft, and the value of the length of the upstream inclined shaft is unsuitable.

By the method for determining the length extremum of the downstream inclined shaft, the size of the length extremum of the downstream inclined shaft (namely, the maximum length of the downstream inclined shaft allowed by the requirement of wind) can be calculated under the condition of a certain length of the upstream inclined shaft. If the downstream inclined shaft length extremum is less than the distance between the air purifier and the inclined shaft inlet, one or more air purifiers may be further positioned between the air purifier and the inclined shaft inlet. If the downstream inclined shaft length extremum is greater than or equal to the distance between the air purifier and the inclined shaft inlet, then no air purifier need be provided between the air purifier and the inclined shaft inlet, and the installation location of the suspended ceiling wet dust removal air purifier can be estimated based on the extremum size (e.g., if the extremum is much greater than the distance between the air purifier and the inclined shaft inlet, then it is contemplated that the location of the air purifier is closer to the bottom of the inclined shaft).

Claims (5)

1. An air purifier is arranged in the inclined shaft, two ends of the air purifier are respectively provided with an induced draft section and an injection section, the induced draft section is arranged opposite to the bottom of the inclined shaft, and the injection section is arranged opposite to an inlet of the inclined shaft; the purifying and ventilating system is provided with an upstream air flow, an air flow to be purified, a purified air flow, a non-purified air flow and a downstream air flow; the upstream air flow is mixed air flow of the back flowing sewage air of the face and flowing air in the installation position of the inclined shaft bottom to the air purifier, the air flow to be purified is a part of the upstream air flow entering the air purifier, the purified air flow is the air flow purified by the air purifier, and the unpurified air flow is a part of the upstream air flow which does not enter the air purifier; the upstream air flow, the air flow to be purified, the purified air flow and the unpurified air flow are split and combined through the air inducing section and the injection section of the air purifier; the method is characterized in that the calculation formula of the length extremum of the downstream inclined shaft is as follows:

wherein: q ₀ is the back flow sewage wind volume of the tunnel face, and m ³/s; c=c/delta is the integral influence factor of smoke flow and the factor ratio number of the designed concentration, m ²/s; delta is the allowable smoke concentration of ventilation design, m ^-1; c is the comprehensive influence coefficient of smoke flow, m/s; l ₁ is the distance upstream of the inclined shaft, m; e is the wind dividing ratio and dimensionless number; η is the smoke dust removal efficiency of the air purifier,%; Distance loss for diluting the back flow sewage wind of the tunnel face; delta ₀ is the smoke concentration of the face return sewage at the bottom of the inclined shaft, m ^-1.

2. The method of claim 1, wherein the smoke flow integrated influence coefficient C is calculated by:

Wherein: q _VI is the reference emission amount of smoke dust, m ²/(veh·km);f_a(VI) is the vehicle condition coefficient considering the smoke dust, and the dimensionless number is zero; f _d is a vehicle density coefficient and is a dimensionless number; f _h(VI) is the altitude coefficient of the smoke and dust, and is dimensionless; f _iv(VI) is a dimensionless number considering the longitudinal slope-vehicle speed coefficient of smoke; n _D is the model class number and dimensionless number of the diesel vehicle; n _m is the traffic volume, veh/h of the corresponding vehicle type; and f _m(VI) is a model coefficient of the diesel vehicle taking smoke and dust into consideration, and is a dimensionless number.

3. The method of claim 1, wherein the obtaining of the downstream inclined shaft length extremum calculation comprises the steps of:

1) Calculating the upstream smoke flow of the inclined shaft, wherein the calculation formula is as follows:

Wherein: q _VI is the upstream smoke flow of the inclined shaft, m ²/s;q_VI is the reference smoke emission, and m ²/(veh·km);f_a(VI) is the vehicle condition coefficient considering smoke, and dimensionless number; f _d is a vehicle density coefficient and is a dimensionless number; f _h(VI) is the altitude coefficient of the smoke and dust, and is dimensionless; f _iv(VI) is a dimensionless number considering the longitudinal slope-vehicle speed coefficient of smoke; n _D is the model class number and dimensionless number of the diesel vehicle; n _m is the traffic volume, veh/h of the corresponding vehicle type; f _m(VI) is the model coefficient of the diesel vehicle taking the smoke dust into consideration, and is a dimensionless number; l is the length of the inclined shaft, m;

In the formula (1), when the standard emission amount is unchanged, and the dimensionless number of the vehicle condition, the vehicle density, the gradient, the vehicle speed and the diesel vehicle type is unchanged and the influence caused by the change of the altitude can be ignored, the inclined shaft smoke flow is a function of the inclined shaft length and the comprehensive influence factor; wherein, the calculation formula of the comprehensive influence factor is:

Wherein: c is the comprehensive influence factor of smoke flow, m/s;

2) Calculating the smoke concentration of upstream wind flow, applying formulas (1) and (2), and setting the length of an upstream inclined shaft as L ₁, wherein the calculation formula of the smoke concentration of the upstream wind flow mixed with the back flow of the sewage wind of the tunnel face is as follows:

Wherein: delta ₁ is the smoke concentration of the upstream wind flow, m ^-1;L₁ is the upstream inclined shaft length, m; q ₀ is the flow rate of the back-flowing sewage wind of the tunnel face, m ³/s;δ₀ is the concentration of the back-flowing sewage wind and smoke of the tunnel face, m ^-1;Q_A(VI) is the flow rate of smoke at the upstream of the inclined shaft, m ²/s;Q_1(VI) is the flow rate of smoke newly added at the upstream section of the inclined shaft, m ²/s;Q_0(VI) is the flow rate of the back-flowing sewage wind of the tunnel face, and m ²/s;

3) The wind dividing ratio is calculated, and the calculation formula is as follows:

Wherein: e is the wind dividing ratio and dimensionless number; q _B1 is the circulating air flow volume which is shunted to the air inducing section of the air purifier, and m ³/s;

according to the principle of conservation of mass, the air volume of the air flow which does not enter the air purifier is:

Q_B2＝(1-e)·Q₀ (5)

Wherein: q _B2 is the air quantity of the air flow which does not enter the air purifier, and m ³/s;

4) Calculating the concentration of smoke dust not entering the air flow of the air purifier:

the flow smoke flow calculation formula of the wind flow smoke flow which does not enter the ceiling wet type air purifier is as follows:

Q_C2(VI)＝Q_B2(VI)＝δ₁Q_B2＝δ₁Q_C2 (6)

Wherein: q _B2、Q_C2 is the air quantity of the unpurified air flow, m ³/s; q _B2＝Q_C2;Q_B2(VI)、Q_C2(VI) is the smoke flow which does not enter the air flow of the ceiling wet type air purifier, and m ²/s; because the length of the air purifier is far smaller than that of the inclined shaft, the flow of the smoke dust added at the bottom of the suspended ceiling wet type air purifier is negligible, and therefore, Q _B2(VI)＝Q_C2(VI) exists;

Substituting the formula (5) into the formula (6) to obtain:

Q_C2(VI)＝Q_B2(VI)＝δ₁(1-e)Q₀ (7)

5) Calculating the concentration of smoke dust which is converged by the purified circulating air flow and the air flow which does not enter the air purifier:

The wind flow flowing through the suspended ceiling wet type air purifier arranged in the inclined shaft is the purified circulating wind flow, and the smoke flow in the wind flow is as follows:

Q_C1(VI)＝δ₁Q_B1(1-η) (8)

substituting formula (4) into formula (8) to obtain:

Q_C1(VI)＝δ₁·Q₀·e·(1-η) (9)

according to the basic principle of physics, the concentration of the flue gas when the purified circulating air flow is combined with the air flow which does not enter the air purifier is as follows:

Substituting the formula (7) and the formula (9) into the formula (10) to obtain:

δ₂＝δ₁·(1-e·η) (11)

Wherein: delta ₂ is the smoke concentration where the two streams meet, m ^-1;

6) Calculating the accumulated smoke concentration of the downstream wind flow:

newly increased smoke flow generated by pollutant emission of vehicles running in a downstream inclined shaft is:

Q_3(VI)＝C·L₃ (12)

Wherein: q _3(VI) is the newly added smoke flow of the downstream wind flow, m ²/s;L₃ is the length of the downstream inclined shaft through which the downstream wind flow flows, and m;

The accumulated smoke flow of the downstream wind flow in the downstream of the inclined shaft is from two parts, namely the smoke flow brought by merging the purified circulating wind flow and the airflow which does not enter the air purifier, and the smoke flow of the newly added downstream wind flow; thus, the downstream wind flow accumulates the smoke concentration as:

Wherein: delta ₃ is accumulated downstream wind flow smoke concentration, m ^-1;Q_E(VI) is inclined shaft upstream and downstream smoke flow, and m ²/s;

substituting the formula (11) and the formula (12) into the formula (13) to obtain:

7) Calculating the length extremum of the downstream inclined shaft:

When the allowable smoke dust concentration of the inclined shaft ventilation design is delta and delta ₂＜δ₃ is less than or equal to delta, the ventilation design requirement is met, and the ventilation design method comprises the following steps of:

Wherein: delta is the allowable smoke concentration of ventilation design, m ^-1;

If and only if δ ₃ =δ, to meet the inclined shaft ventilation design smoke concentration requirement, then the downstream inclined shaft length has a limit value L _3c; substituting L ₃ for L _3c in equation (14), the term is shifted from equation (14):

Wherein: l _3c is the downstream slant well length, m, when δ ₃ =δ;

And (3) further finishing the formula (16) to obtain:

wherein: c=c/delta is the integral influence factor of smoke flow and the factor ratio number of the designed concentration, m ²/s; to dilute the distance loss of the back flow of the sewage wind on the face.

4. The method of claim 1, wherein the determining of the downstream deviated well length extremum comprises the steps of:

obtaining the values of the upstream inclined shaft length, the smoke dust removal efficiency of the air purifier, the wind dividing ratio, the return air quantity of the face, the dependent variable ratio number and the distance loss of the return air of the diluted face;

substituting the numerical values into a formula (17) for calculation to obtain the length extremum of the downstream inclined shaft.

5. The method of claim 1, wherein the air purifier is a suspended ceiling wet air purifier that is mounted above the interior of the inclined shaft.