What is a chimney lining? Chimney lining: scope of work

In order to ensure the smooth functioning of systems, it is necessary to carry outpipeline lining and coating of pipes with anti-corrosion materials. This will make it possible to repair and restore industrial equipment in as soon as possible and will avoid wear and tear in the future.

Every year, leaks, regardless of their cause, result in unimaginably high repair costs. One of the problems is also the danger to person and environmentchemical leaks. To limit damage, quick and safe means are always needed. Restoration and repair technologies must be available around the clock and should be as safe as possible.

Transporting liquids through pipelines requires highly efficient wear protection And corrosion. The ingress of particles and foreign substances, regardless of their size, threatens equipment with chips, cracks and premature wear. In this case, leaks and local damage occur quickly and unhindered.

Pipeline lining, anti-corrosion pipe coating

Anti-corrosion coating of pipes, anti-corrosion coating of pipelines, internal anti-corrosion coating of pipes

It includes not only external treatment with polymer materials, but will also allow internal anti-corrosion coating of pipes.

For pipeline lining And anti-corrosion pipe coatingour company suggests using elastomerMetaline 700 series. Given elastomeric coatingforms a dense barrier to moisture penetration and thereby reliably protects the surface from corrosion. Elastomers Metaline 700 series can be used to restore anti-corrosion coatings and are easily subject to local repairs.

Send your good work in the knowledge base is simple. Use the form below

Students, graduate students, young scientists who use the knowledge base in their studies and work will be very grateful to you.

Posted on http://www.allbest.ru/

WITHpossession

Lining design solutions

Lining materials

Bibliography

TOlining design solutions

Lining chimneys performs two functions: protecting the barrel from the thermal and aggressive effects of flue gases and condensate. To exclude the possibility of condensate formed on the surface of the overlying lining link getting into the gap between the barrel and the underlying link, it is covered with a canopy made of acid-resistant products called “tear-resistant.”

Quite often, the lining is applied using shotcrete, ensuring gas tightness.

In the base part of the pipes, with significant openings for supply gas ducts, the lining thickness is taken to be 1.5 bricks or 380 mm. Considering that currently several types of linings made of piece ceramic products are used in chimneys built in different periods, it is advisable to illustrate their designs.

Until about 1960 chimneys were operated at a flue gas velocity at the exit not exceeding 14-16 m/s, and at a vacuum along the entire height of the smoke channel. The temperature of the flue gases was in the range of 180-250 C, which excluded the conditions for the formation of condensation. The lining design met these conditions.

In the early 60s, there was a significant decrease in the temperature of flue gases to 70-180 C and the use of high-sulfur fuel, which resulted in the formation of sulfuric acid condensate in the pipes. In this regard, the need arose to protect the load-bearing reinforced concrete pipe shaft from sulfuric acid corrosion and a lining design appeared using acid-resistant products and a layer of vapor and moisture insulation, usually made from bitumen mastic, although sometimes other coatings from sheet materials or coal tar epoxy resins. It should be noted that bitumen mastic required the installation of a pressure layer in the lining.

In the presence of high gas velocities (25-40 m/s), excess static pressure arises in the smoke channel of the pipe. In this regard, a backwater of aggressive flue gases is created, which penetrate through the lining of piece ceramic products to the inner surface of the reinforced concrete shaft, which has more low temperature compared to flue gas temperature. As a result, they are cooled below the dew point and sulfuric acid condensate falls on the inner surface of the pipe shaft, which leads to accelerated corrosion of the load-bearing structures.

A problem arises - either strengthen the anti-corrosion protection of the barrel, or look for new design linings.

Taking into account the acute shortage of reliable anti-corrosion coatings and their high cost, work began to improve the lining. Thus, a backpressure design in a forced-ventilated gap was developed. In chimneys with a lining of this design, an additional volume of air is supplied to the gap between the barrel and the lining by a fan and a pressure is created in the gap that exceeds the pressure of the flue gases, as a result of which the filtration of gases to the supporting pipe shaft must be prevented. To increase the crack resistance of the lining, air. Supplied into the gap, it must be heated to reduce the temperature difference on the working and outer surfaces to a minimum.

There is also a lining design with a naturally ventilated gap. The difference in design lies in the gradual reduction in the width of the gap along the height of the pipe, which should ensure that a certain back pressure is maintained in it.

In all of the above options, a lining made of pieced ceramic products requires large amounts of physical labor, time, machinery, and equipment for its construction, as well as careful implementation of measures for the safe performance of work. In addition, each of the options has its own vulnerabilities associated with the disadvantages inherent in all brick structures.

Therefore, the appearance of a monolithic lining in the early 80s, the design of which can significantly reduce labor costs, the duration of work and their cost, is quite justified.

Reinforced concrete pipes with monolithic lining began to be built in 1970. By that time, due to environmental conditions and the lack of effective ways Purification of flue gases from sulfur and nitrogen oxides at many facilities required the construction of gas exhaust pipes with a height of 250, 320, 370 and 420 m.

The search for more industrial methods of pipe lining led to the development of two-layer monolithic pipes. The outer shell was made of heavy concrete, the inner monolithic layer of lightweight polymer concrete.

In this case, a higher level of reinforcement of the outer shell was provided to increase the crack resistance of the shaft, since when the inner layer of lightweight concrete is heated, the temperature stresses must be absorbed by the reinforced concrete shaft.

A monolithic lining made of lightweight polymer-cement concrete serves to protect the load-bearing reinforced concrete shaft of chimneys. Designed for the removal of slightly aggressive gases produced by burning low-sulfur coals. To prevent excess pressure from appearing in pipes with this lining, their upper part has a cylindrical shape.

Accelerated technology for constructing pipes is ensured by the fact that concreting the shaft and lining is carried out using one set of formwork, and the separation of layers of different concretes is achieved by installing a separating diaphragm made of metal wire mesh with 4x4 mm cells.

Thirty years of experience in operating two-layer reinforced concrete chimneys has shown their high reliability. Over twenty years of operation, for example, Volzhskaya CHPP - 2, which operated for a significant part on fuel oil, the polymer-cement lining of a chimney 270 m high had a decrease in strength on the side in contact with flue gases to a depth of 2-5 mm.

The lining of prefabricated chimneys to protect the shaft from condensation is usually carried out by gunning with a layer thickness of 25-30 mm with a composition of quartz or fireclay sand and Portland cement.

To protect the barrel from high temperatures, a lining is made from KVI-650 products. Modern products made from ceramovermiculite KVI-650 (TU 21-RF-129-88), intended for lining thermal units with operating temperature up to 1100 o C. The use of KVI-650 in furnace lining allows saving significant energy and material resources. This material is easy to process (sawn, drilled, etc.), is not afraid of water, durable, and resistant to rapid temperature changes.

It should be noted that today there is no data on the long-term service of linings of old reinforced concrete chimneys.

The main disadvantages when using linings of any design are the impossibility of eliminating damage that occurs for various reasons without stopping the pipe for a long period of time, the technological complexity of repair work, as well as great difficulties in monitoring its condition during operation.

Lining materials

chimney lining gunite

In the case of removal of low-aggressive flue gases through a pipe, clay bricks are used for lining - patterned and ordinary plastic pressing. In this case, cement-clay mortars are used for laying the lining. When flue gases are highly aggressive, acid-resistant normal and radial bricks are used for lining. In terms of physical, chemical and mechanical parameters, this brick must meet the requirements given in table. 1.

Table 1 Physico-chemical and mechanical properties of acid-resistant bricks.

Brick laying is carried out on andesite putty, in which the binder is sodium-based liquid glass.

The composition of the acid-resistant solution includes, in addition to liquid glass and hardening initiators (sodium silicofluoride), finely ground filler and acid-resistant filler (sand). The binder in the acid-resistant solution is a silicic acid gel, released as a result of the interaction of liquid glass with a hardening indicator.

When burning high-sulfur fuel, it is recommended to use an acid-resistant solution of composition III and the use of an acid-resistant solution of composition I is allowed. In conditions of alternate combustion of high-sulfur and gas fuels or combustion of low-sulfur fuel with high humidity of exhaust gases, the use of acid-resistant composition II is recommended.

To prevent the penetration of gases and protect the inner surface of the reinforced concrete pipe shaft, it is necessary to completely fill the joints of the lining masonry with jointing them or grout the inner surface and oxidize with a 20% sulfuric acid solution 3-4 times. To seal the gaps at the junction of the lining links, asbestos cord is used. Acid-resistant tiles are used to protect ceilings and floors in the lower parts of chimneys exposed to acids. In the latest new designs of flue pipes as building materials applied artificial materials flint concrete and polymer concrete, and to protect gas ducts - silicate-polymer concrete.

Silica concrete is obtained by autoclave processing of a mixture of high-silica silicate block, finely ground quartz sand, acid-resistant fine and coarse aggregate. The difference between siliceous concrete and conventional concrete is the use of a new binding material called siliceous cement. Siliceous cement consists of ground quartz glass, which contains SiO 2 in amorphous form, an alkaline solvent and finely ground particles of crystalline quartz. Quartz glass is obtained by melting quartz sand in special furnaces such as glass furnaces. The filler for flint concrete is, as in conventional concrete, quartz sand and gravel.

The study of the phase composition and structure showed that silica concrete is characterized by a complex conglomerate porous structure. The pores are mostly closed in nature with a size ranging from 0.01 to 1.5 mm. The total porosity is 11 - 13%. The structural features of silica concrete and the phase composition of the cementing substance predetermine its physical, physical-mechanical, construction, and thermal properties. physical properties and durability.

In table Table 2 shows the properties of silicon concrete on Ovruch quartzite with a silicate block consumption of 320 kg/m 3.

Table 2 Basic properties of silica concrete

Slabs are formed from flint concrete, which are then subjected to thermal and wet treatment in autoclaves at a pressure of 0.13 MPa and a temperature of 190 C for about a day. These plates are used for the installation of gas exhaust shafts.

Silicate-polymer and cement-polymer concrete are used in the construction of pipes according to the “pipe-in-pipe” design principle, such as a pressure lining, and in the construction of gas ducts in the form of a concrete mixture.

Bibliography

1. Duzhikh F.P., Oslovskikh V.P., Ladygichev M.G. Industrial chimneys and ventilation pipes: Reference publication / Edited by F.P. Duzhikh. - M.: Teplotekhnik, 2004 - 464 p.

2. Chimneys / a.m. Elshin, M.N. Izhorin, V.S. Zholudov, E.G. Ovcharenko; Edited by S.V. Satyanova. - M.: Stroyizdat, 2001. - 296 p.; ill.

Posted on Allbest.ru

...

Documentation

Purpose

Steel pipe lined with a modified thermo-expandable polymer sleeve of the TFR series- This is a multi-layer two or three-layer pipe structure consisting of steel and internal polymer pipes. The steel pipe carries the load, and the polymer pipe protects the steel pipe from internal corrosion. The steel pipe is protected from external corrosion by a polymer or anti-corrosion paint coating.

Lined pipes are manufactured on the basis of technical specifications TU 1394-015-75454983-2014.

Steel pipes lined with a modified polymer sleeve are used for the construction of oil field and process pipelines transporting water-cut oil, wastewater containing hydrogen sulfide, as well as other liquid and gaseous media to which the composite polymer material is chemically resistant - a thermally expandable, complexly modified composite polymer based on polyolefins.

by operating temperature (-60 °C – +135 °C),
chemical resistance, low gas permeability (up to 10 times),
increased wear resistance (up to 30 times),
mechanical strength (up to 3 times).

These parameters significantly increase the service life of TFR compared to steel pipes and provide the main competitive advantages of lined pipes of the TFR series in relation to metal-plastic (MPT), polymer-reinforced (PAT and TTA) and polyethylene (polypropylene) lined steel pipes.

Due to the low roughness of the inner surface of lined TFMR pipes, which does not decrease over time, throughput they are 10-15% higher than that of a metal pipe, all other things being equal, which makes it possible to use TFMR of a smaller diameter.

Nomenclature of lined pipes of the TFMR series

Conditional pass: 50; 70; 80; 100; 125; 150; 200; 250; 300; 400; 500 mm.

Pipes with a diameter from 57 to 530 mm, having manufacturer certificates, are used as a steel shell:

Steel water and gas pipelines that meet the technical requirements of GOST 3262;
Seamless hot-deformed steel, meeting the technical requirements of GOST 8731. rough assortment according to GOST 8732;
Seamless cold-deformed steel that meets the technical requirements of GOST 8733. Pipe range in accordance with GOST 8734;
Straight-seam electric-welded steel, meeting the technical requirements of GOST 10705, pipe assortment GOST 10704.

It is allowed to use pipes of the same range that meet the requirements of other technical specifications, or pipe standards with external insulation, agreed with the Customer.

Wall thickness:

steel 3 – 20 mm,
lined 2.0 – 5.0 mm.

Maximum deviations: by thickness steel pipe: in accordance with GOST 8732-78, lining polymer layer ± 15%.

As a lining layer, a polymer thermo-expandable complex modified hose of the TPP series is used according to TU 2248-001-75454983-2013, made from a polyolefin composite with subsequent gamma quantum modification.

Measured pipe length: from 6 to 12 m. By agreement with the customer, it is possible to manufacture pipes with various lengths and configurations up to 12.0 m.

Connection type: flanged, coupling, welded for operating pressure up to 25 MPa (according to OZEU LLC technology).

The maximum operating pressure of lined pipes Pwork.max (MPa) is regulated by the parameters of the steel pipe.

Temperature of the transported medium: from – 60 to + 135 °C.

Transported medium:

water: technical, drinking, distilled, mineralized, sea;
oil and oilfield wastewater;
pickling solutions, galvanic departments and chemical cleaning enterprises;
liquid and gaseous ammonia;
acids: 30% sulfuric, 25% nitric, hydrochloric, hydrofluorosilicic, hydrofluoric;
gas and gas-liquid mixtures, including natural gas and associated petroleum gas.

The continuity and thickness of the lining layer is guaranteed by production technology and checked by non-destructive testing devices. If necessary, pipes are tested for impact strength at temperatures down to -60 °C.
The pipes withstand test hydraulic pressure in accordance with GOST 3845-75.

Pipes must withstand the flattening test in accordance with GOST 8695-75.

– 0,04 0,035 0,3

Page 1

Lined pipes (consisting of a metal pipe and a plastic shell adjacent to its inner surface) have the high mechanical strength of steel and at the same time the corrosion resistance of plastics.

Lined pipes, belonging to subgroup b, are made by deforming a metal pipe until its inner surface hugs the plastic one. As a result, the gap disappears and the plastic lining is pressed against the inner surface of the steel pipe.

Lined pipes are made by joint cold drawing (or cold rolling) of a polyvinyl chloride pipe and a metal sheath.

The lined pipes were heated at 80 - 85 C for 5 hours, after which they were cooled to room temperature with cold water.

Lined pipes are not damaged by accidental impacts and are less sensitive to sudden changes in temperature and pressure.

A lined pipe is a two-layer system consisting of a rigid outer shell (metallic or non-metallic) and a plastic pipe adjacent to it from the inside (lining layer) - The main purpose of lined pipes is to work in conditions high blood pressure and temperatures that threaten unprotected plastic pipes with loss of dimensional stability and strength. Sometimes lined pipes are used at normal and even low temperatures, but when high pressures when the use of unprotected plastic pipes is not economically feasible due to the need for significant wall thicknesses.

Lined pipes are manufactured as follows. A plastic pipe (polyethylene, vinyl plastic) is prestressed by reducing the diameter. Then it is introduced inside a metal pipe and heated. In this case, the stressed plastic pipe, trying to restore its original size, fits tightly to the metal one. The described method for producing lined pipes is quite simple and technologically advanced.

Lined pipes should be stored in closed heated rooms on racks or in stacks away from fire and heating devices.

The lined pipe consists of a steel pipe with flanges at the ends and a vinyl plastic pipe firmly adjacent to its inner surface with a vinyl plastic layer flanged onto the flanges.

Lined pipes should be stored away from heating devices.

Lined pipes are supplied ready for installation with the lining layer flanged onto the connection element with loose or welded flanges.

The lined pipe is heated to a temperature of 150 C and then subjected to vacuum to ensure good adhesion of the hose to metal pipe. The quality of the lined pipes is quite good.