RU2442856C1 - Liquid industrial waste storage unit - Google Patents

Abstract

FIELD: hydraulic engineering. ^ SUBSTANCE: the invention relates to hydraulic engineering and can be used while creating sludge reservoirs, tailing ponds and ash-dumps for waste capable of solidifying and creating cracks. The storage unit has a storage tank dug in ground, a launder and a collector for solidifying waste. The collector is made of steel pipes and fitted with the protective layer on the outside, consisting of cellular plastic with sealed pores which covers the pipes and protects them from damage caused by cracks in solidified waste. The following condition is fulfilled: dacc=bl(compkcomp-hhkhh), that is, bl=dacc/compkcomp-hhkhh, where dacc - is the acceptable amount of vertical movement for two solid blocks in relation to each other at the place where the steel pipe is cracked. bl - the thickness of protective layer above the steel pipe; comp - the relative amount of volume compression of the protective layer material, which corresponds to the maximum acceptable for the pipe durability pressure pcomp, created by waste; hh - is the relative amount of volume compression of the protective layer material, which corresponds to the calculated natural pressure prhh , created by water and waste and applied to the protective layer during the collector operation; kcomp - is the quotient which considers deformation in the cross-section of the pipe caused by compression pressure pcomp and its uneven distribution; khh - is the quotient which considers deformation in the cross-section of the pipe caused by calculated natural pressure prhh and its uneven distribution. ^ EFFECT: prevented steel pipe damage caused by cracks in solidified waste. ^ 10 cl, 6 dwg, 2 ex

Description

The invention relates to hydraulic engineering and can be used to create sludge collectors, tailings and ash dumps for storing waste that can harden and form deformation cracks.

Known drive liquid waste industrial enterprises, including an earth tank, spillway and waste collector, made of precast or monolithic reinforced concrete, covered with waterproofing [1]. The disadvantage of this drive is its high cost due to the complexity of the collector made of reinforced concrete and its bell-shaped butt joints.

Gosgortekhnadzor of Russia in the collectors laid in the alluvial massifs of drives, banned the use of pipes with bell-shaped joints [2]. However, the socketless butt joint is difficult to perform and not reliable enough during operation.

Known drive liquid waste of industrial enterprises, including an earth tank, spillway and sewer hardened by solidifying waste, which is made of steel pipes [3, p. 55-56, p. 6.1-6.7].

Self-hardening waste, for example, ash and slag, have cementing properties - group I according to the classification of UralVTI. These include ash and slag materials of oil shale, coal of the Kansk-Achinsk basin and peat. These ash and slag are distinguished by a high content of total and free calcium - up to 60 and 30%, respectively [3, Appendix 1] and hardened to a specific adhesive force of c = 0.5 MPa or more [3, Appendix 9]. Self-hardening is also possessed, for example, by nepheline sludges from alumina production [4] and others. Such solidified waste forms a bearing vault above the collector, which limits the pressure of water and waste on the pipe. However, with further storage of waste, especially with uneven deformations of the base and / or shocks, the massif can break with the opening of cracks. In this case, both horizontal and vertical displacement of the formed solid blocks relative to each other occurs, which, when a crack crosses the collector, can damage it.

It is precisely this, according to the authors, that the sewage well collector No. 1 was damaged on map No. 2 of the Achinsky alumina sludge storage facility in October 2008 as a result of the formation of a crack and its opening on the waste surface to 4-5 mm, which led to gushing of water on the slope and decommissioning the well. Previously, a similar long flowing of water from a crack at this sludge storage facility was observed on map No. 1.

A well-known liquid storage device for industrial enterprises, including an earthen tank, a spillway and a collector washed by hardening waste, is made of steel pipes and provided with a protective coating on the outside made of a polymer roll material (plastic film with grease at the base). In this case, the condition expressed by the mathematical formula is fulfilled, in which the relationship between the strength and deformation properties of the steel pipe, the value of the shear stress between the solidified waste and the steel pipe and the allowable crack opening [5] are linked.

Such a protective coating effectively prevents damage to steel pipes during the opening of a deformation crack in solidified waste when only two solid state blocks are formed horizontally relative to each other. When crack opening occurs with simultaneous vertical displacement of solid-state blocks relative to each other, this protective coating does not protect the steel pipe from damage from transverse (shear) forces, which reduces the reliability of the drive.

The problem to which the invention is directed, is to increase the reliability of the drive. The technical result achieved in this case is that damage to steel pipes during the formation of deformation cracks in the solidified waste is prevented by reducing the impact to safe, i.e. the maximum allowable value of additional compressive pressure on steel pipes from above, arising from the formation of cracks in solidified waste.

This problem is solved, and the technical result is achieved by the fact that in the liquid waste storage device of industrial enterprises, including an earth tank, a spillway and a collector washed by solidifying waste, which is made of steel pipes and provided with a protective coating from the outside, according to the invention, the protective coating is made in the form of a cellular layer hermetically sealed pores. This protective layer covers steel pipes and prevents their damage when a strain crack is formed in the solidified waste, while the condition

d _d = b _cl (ε _cr k _cr- ε _b k _b ),

those.

b _sl = d _d / ε _cr k _cr- ε _b k _b ,

where d _d - the allowable amount of vertical displacement relative to each other of two solid blocks at the intersection of the cracked steel pipe;

b _SL - the thickness of the protective layer above the steel pipe;

ε _sr - the relative volumetric compression of the material of the protective layer corresponding to the maximum pressure p _sr from the strength condition of the steel pipe, which is created by waste and water;

ε _b is the relative volumetric compression of the material of the protective layer corresponding to the compressive design household pressure p _rb created by waste and water on the protective layer during the period of operation of the collector;

k _sz - coefficient taking into account the deformation in the cross section of the steel pipe from the action of compressive pressure p _sz and the unevenness of its distribution;

k _b - coefficient taking into account the deformation in the cross section of the steel pipe from the effects of compressive design household pressure p _rb and the unevenness of its distribution.

Additionally:

- the protective layer is made of polystyrene foam;

- the condition is satisfied:

p _cr = 2σ _p δ / D _n ,

where σ _p - the allowable increment of compressive stress in the wall of the steel pipe in its cross section from the vertical displacement relative to each other of solid blocks,

δ is the wall thickness of the steel pipe,

D _n - the outer diameter of the steel pipe;

- the condition is satisfied

P _rb = γh _p ,

where γ is the specific gravity of water;

h _p - the estimated height of the excess water level above the steel pipe during the operation of the collector;

- the protective layer is made of cellular plastic with compressive strength at 10% deformation of not more than 0.45 MPa;

- the protective layer is made of cellular plastic with compressive strength at 10% deformation of at least 0.1 MPa;

- the condition is satisfied

d _d = b _cl (1,1ε _{compression channel} -ε _b);

- the condition is satisfied

d _d = b _cl (ε _cr- ε _b );

- the condition is satisfied

d _d ≤ (0,6-0,9) b _sl.

It is the coating of steel pipes with a layer of easily deformable cellular plastic, the thickness of which with a margin exceeds the value of the vertical displacement of solid-state blocks relative to each other, as will be shown below, protects steel pipes from damage both during horizontal displacement of blocks accompanied by crack opening and vertical displacement of blocks.

The invention is illustrated by drawings, which depict the following:

- figure 1 - waste accumulator at the final stage of filling the working section, plan;

- figure 2 is a section aa in figure 1, the collector is located at the base of the solidified waste, example 1;

- figure 3 is a section bB in figure 2;

- figure 4 - node I in figure 2;

- figure 5 is a section aa in figure 1, the collector is located inside the solidified waste, example 2;

- figure 6 is a curve of the volumetric deformation of the gas from compressive pressure and the quality curves of the volumetric deformation of cellular plastics (ε _sr ,%) from the compressive pressure p _sr .

Example 1. The working section 1 of the drive is formed by a building envelope 2 made of soil material, and is equipped with two spillway wells 3, collectors 4 of which discharge water and are washed away by solidifying waste 5. Section 1 is also equipped with slurry pipelines of main 6 and distribution 7 and conduit 8 of the return system the enterprise (not shown) of water clarified in the settling pond 9. The backup section 10 is adjacent to the working section 1.

The collector 4 is located above the polymer antifiltration element 11, which prevents the penetration of waste water into the base 12. The lower part of the collector 4 is enclosed in the soil of the protective layer 13 of the antifiltration element 11, and the upper part is enclosed in waste 5. The collector 4 is made of steel pipes (hereinafter: pipes) 14 and is provided externally with a protective layer 15 (FIG. 2 and FIG. 3). This protective layer 15 is made of cellular plastic with hermetically sealed pores, covers the pipes 13 at least from above and prevents their damage when a deformation crack 15 (hereinafter: crack) is formed in the solidified waste 5. In doing so, the condition justified below is fulfilled

those.

where d _d - the allowable amount of vertical displacement relative to each other of two solid blocks at the intersection of the cracked pipe;

b _SL - the thickness of the protective layer above the pipe;

ε _sr - the relative volumetric compression of the material of the protective layer corresponding to the maximum allowable pressure p _sr from the pipe strength condition created by waste and water;

ε _b is the relative volumetric compression of the material of the protective layer corresponding to the compressive design household pressure p _rb created by waste and water on the protective layer during the period of operation of the collector;

k _sz - coefficient taking into account the deformation (ductility) in the cross section of the pipe from the action of compressive pressure p _sz and the unevenness of its distribution (in the upper part of the pipe);

k _b - coefficient taking into account the deformation in the cross section of the pipe from the effects of compressive design household pressure p _rb and the unevenness of its distribution.

The protective layer 15 can be made primarily of polystyrene foam foam 35 or 45 grade (segments C-1, C-2 and C-3), the compressive strength at 10% deformation of which, respectively, is not less than 0.25 MPa and 0.45 MPa [6] or heat-insulating polystyrene shell according to TU 5768-001-81781752-2007, the compressive strength at 10% deformation of which is not less than 0.08 MPa.

The protective layer 15 can be made of rigid (according to the terminology of GOST 20869-75 *) foam, which is a foamed cellular plastic with hermetically closed pores and having a given design compressive strength, but not less than 0.1 MPa at 10% linear deformation.

The protective layer 15 can be made of polyurethane foam, foamed phenol formaldehyde or other foamed cellular plastic, widely used for thermal insulation of the outer surface of pipes according to GOST 16381-77.

Pipes 14, it is advisable to provide an anticorrosive coating, for example, a polyethylene coating of factory application 17 (figure 4).

Foamed cellular plastics, in fact, are composite materials and usually 96% or more of their volume consist of gas trapped in the pores. Therefore, upon compression of the protective layer 15, as the thickness decreases, the compression resistance on the gas side increases sharply. In this case, the maximum permissible compressive pressure p _cr , which is transferred from above from the waste 5 and water through the protective layer 15 to the pipe 14 (Fig. 3), can be determined from the pipe strength condition by the approximate formula

where σ _p - the allowable increment of compressive stress in the pipe wall in its cross section from the vertical displacement relative to each other of solid blocks;

δ is the pipe wall thickness;

D _n - the outer diameter of the pipe.

The estimated household pressure p _rb created on the protective layer 15 during the period of operation of the collector can be determined by the formula

where γ is the specific gravity of water;

h _p - the estimated height of the water level above the pipe during the period of operation of the collector.

Household pressure p _b on the pipe 14 at the initial stage of creating waste storage 5 is determined by the pressure of loose waste 5 and water and is determined by known mathematical formulas. In the future, after the solidification of waste 5 adjacent to the pipe 14, it can be considered that only a constantly increasing water pressure will act on the pipe, which compresses the protective layer 15 to a value of b _b (Fig. 2 and Fig. 4). This water pressure most often determines the estimated household pressure p _rb , which is calculated by the formula (3).

The calculated household pressure p _{rb is} usually many times lower than the permissible compressive pressure p _cr , at which the protective layer 15 is compressed to a value of b _cr . The pressure p _rb does not exceed 0.45 MPa, which causes the compression of the protective layer by no more than 10% and does not create high stresses and significant deformations in the pipe 14. Therefore, at the preliminary design stage in formula 1a, the coefficient k _b can be taken equal to unit, and the coefficient k _sr according to the applicant may be taken equal to 1.1 or unit. In this case, formula 1a will have the form, respectively,

or

The permissible value of the vertical displacement d _d according to the applicant is in the range of (0.5-0.9) b _sl i.e. the condition is satisfied

Relative values of the volumetric compression of the material of the protective layer and ε ε _{compression channel used} depend on the compression pressure, _{compression channel,} respectively p and p and _b which are determined based on the actual volumetric strain curve depending material of the protective layer 15 (ε,%) by compressing the layer of pressure p. Such a curve is established by experimental-mechanical testing of a sample of the material of the protective layer 15.

_SJ factors k and k are _used in relation to specific operating conditions of the pipe 14 is also useful to define by means of a testing machine equipped with a special measuring instruments.

In the drawings, other elements of the drive are indicated, namely:

18 - gap;

19 - pipe wall;

20 - water level in the pipe;

21 - the cavity of the pipe;

22 - the underlying layer of soil (antifiltration element).

The main features of the drive when filling the above-described working section 1 with waste 5 are as follows.

1. After a set of sufficient strength by waste 5, the pressure on the protective layer 15 determines, first of all, the constantly increasing hydrostatic pressure of water p _b . This pressure p _b compresses the protective layer 15 to a household thickness b _b (FIG. 2 and FIG. 4). As a result, between the solidified waste 5 and the protective layer 15, therefore, and the collector 4, a gap 18 is formed, which is filled with water.

2. After the formation of a crack 16 crossing the pipe 14, from the side of block No. 1, the vertical pressure p _cp acts on the pipe 14 from above, which includes household pressure p _b and which compresses the protective layer 15 above the pipe 14 to a value of b _cp . It is due to this that damage to the pipe 14 is prevented under the condition that the vertical displacement of blocks No. 1 and No. 2 relative to each other d (Fig. 2 and Fig. 4) does not exceed the permissible, i.e. safe value d _d , which is determined by mathematical formula 1a. Simultaneously, the disclosure of crack 16, by an amount a (4) the presence of a water-filled gap 18, as well as high deformation properties of the material of the protective layer 15 reduces the tensile strength pipe 14 to a negligible value. In addition, it is advisable to adapt the slot 18 with safety in mind to remove filtering water from the waste 5 - it is constructively solved in the project.

3. The effective work of the collector can be determined only after conducting a study (theoretical, by analogs) for the possible formation of a crack in the solidified waste crossing the collector and predicting the possible value of the vertical displacement d of two formed solid state blocks relative to each other.

The following is an example of calculating the vertical displacement d _d allowed under specific conditions.

Let the steel pipe 14 has an outer diameter of D _n = 120 cm, the wall thickness δ = 1.2 cm and the top is covered with a protective layer of rigid foam with a thickness of b _sl = 20 cm. Additionally, the estimated height h _{p the} excess of the water level in the settling pond 9 above the pipe 14 during the period of operation of the collector is equal to 45 m (extremely high), and the allowable increment of compressive stress in the wall 19 of the pipe 14 is defined as σ _p = 150 MPa.

Using the formula (2), we determine the allowable compressive pressure p _cr on the pipe from above

p _cr = 2σ _p δ / D _n = 2 × 150 × 1.2 / 120 = 3 MPa.

By the formula (3), we determine the compressing household pressure p _b on the pipe from above

p _rb = γh _p = 1000 kg / m ³ × 45 m = 45000 kg / m ² = 0.45 MPa.

When performing the protective layer 15 of expanded polystyrene "foamplex" grade 45 (segments 1-3 in figure 3 and figure 4), we determine the relative values of the volumetric compression of the protective layer ε _squ = 0.6 and ε _b = 0 from the curve in figure 6 ,one. Then, using approximate formula 4, we determine the allowable value of the vertical displacement of two solid blocks relative to each other

d _d = b _cl (1,1ε _{compression channel} -ε _b) = 20 × (1,1 × 0,6-0,1) = 11,2 cm.

When performing the protective layer 15 of expanded polystyrene grade 35 and under the same conditions, we have ε _sr = 0.82; ε _b = 0.19 and d _d = 14.24 cm.

When performing the protective layer of the "shell" we have

ε _cr = 0.93; ε _b = 0.46 and d _d = 11.26 cm.

The dependency curves for the possible materials of the protective layer 15 in Fig.6 are built on three points, namely:

- the first point "0" is the origin;

- the second point corresponds to 10% compression of the material according to the technical specifications;

- the third point is applied at a pressure p = 3 MPa (30 kg / cm ² ) approximately by analogy with the gas curve.

Despite the approximation of the dependency curves shown in Fig.6, the estimated calculations allow us to conclude that the cellular plastics are highly effective for the protective layer 15 of steel pipes 14 of the collectors 4 in the solidifying waste storage.

Example 2 (figure 5). The collector 4 differs from the previously described collector 4 in example 1 in that it is completely located inside the solidified waste 5. Therefore, the pipe 14 of the collector 4 is provided with a protective coating 15, which is made along the entire perimeter of the cross section of the pipe 14.

A feature of the work of such a collector 4 when crossing it with a crack 16 is as follows.

1. Under the influence of a constantly increasing hydrostatic pressure of water p _{b, a} gap 18 between the solidified waste 5 and the protective layer 15 is formed practically along the entire perimeter of the cross-section of the collector 4, therefore, the pipe 14. This pipe 14 together with the protective coating 15 floats in water - depending on the level of water 20 filling the cavity 21 of the pipe 14.

2. After the rapid formation of a crack 16 under the pipe 14, a vacuum may form within the descending block No. 1, the size of which is limited by the expansion of the gas trapped in the pores of the protective layer 15 and the elasticity of the plastic of this layer 15. In this case, the thickness of the protective layer 15 increases to b _times . This restriction of the vacuum reduces the vertical load on the pipe 14, the value of which could be at the time of formation of the crack 16 during deep discharge, if the protective layer 15 were not present on the pipe 14 below.

Information sources

1. Waterworks. Designer Handbook / Ed. V.P. Nedrigi. M .: Stroyizdat, 1983.P. 509-515.

2. Gosgortekhnadzor of Russia. Safety rules for hydraulic structures of liquid industrial waste storage. Moscow, Russian newspaper, No. 103, dated 08.06.2002.

3. Recommendations for the design of ash and slag heaps of thermal power plants: P 26-85 / VNIIG, L., 1986.

4. OAO Achinsk Alumina Refinery. Sludge storage passport. Map No. 2 (table 1.1).

5. RF patent No. 2398067, cl. E02B 7/06, 2010. Liquid storage of industrial waste. Yagin V.P., Vaikum V.A., Rudnov V.M.

6. Segments and half-cylinders heat-insulated from Penoplex extruded polystyrene foam for pipelines with a diameter of 57-1420 mm. TU 5767-001-01297858-02 / Ministry of Energy of the Russian Federation. - M .: OA "VNIIST", 2002.

Claims (9)

1. The accumulator of liquid waste of industrial enterprises, characterized in that it has an earth tank, a spillway and a collector washed by solidifying waste, which is made of steel pipes and equipped with a protective layer made of cellular plastic with hermetically sealed pores covering the steel pipes and preventing their damage during the formation of a deformation crack in solidified waste, while the condition
d _d = b _cl (ε _cr k _cr- ε _b k _b ),
those.
b _sl = d _d / ε _cr k _cr- ε _b k _b ,
where d _d - the allowable amount of vertical displacement relative to each other of two solid blocks at the intersection of the cracked steel pipe;
b _SL - the thickness of the protective layer above the steel pipe;
ε _sr is the relative volumetric compression of the material of the protective layer corresponding to the maximum compressive pressure p _sz generated by waste from the strength condition of the steel pipe;
ε _b is the relative volumetric compression of the material of the protective layer corresponding to the compressive design household pressure p _rb created by water and waste on the protective layer during the period of operation of the collector;
k _sz - coefficient taking into account the deformation in the cross section of the steel pipe from the action of compressive pressure p _sz and the unevenness of its distribution;
k _b - coefficient taking into account the deformation in the cross section of the steel pipe from exposure to compressive design household pressure p _rb and the unevenness of its distribution. 2. The drive according to claim 1, characterized in that the protective layer is made of expanded polystyrene. 3. The drive according to claim 1, characterized in that the condition
p _cr = 2σ _p δ / D _n ,
where σ _p - the allowable increment of compressive stress in the wall of the steel pipe in its cross section from the vertical displacement relative to each other of solid blocks;
δ is the wall thickness of the steel pipe;
D _n - the outer diameter of the steel pipe. 4. The drive according to claim 1, characterized in that the condition
p _rb = γh _p ,
where γ is the specific gravity of water;
h _p is the estimated height of the water level above the steel pipe during the period of operation of the collector. 5. The drive according to claim 1, characterized in that the protective layer is made of cellular plastic with compressive strength at 10% deformation of not more than 0.45 MPa. 6. The drive according to claim 1, characterized in that the protective layer is made of cellular plastic with compressive strength at 10% deformation of at least 0.1 MPa. 7. The drive according to claim 1, characterized in that the condition
d _d = b _cl (1,1ε _{compression channel} -ε _b). 8. The drive according to claim 1, characterized in that the condition d _d ≤ (0.5-0.9) b _cl . 9. The drive according to claim 7, characterized in that the condition
d _d = b _cl (ε _cr- ε _b ).

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