Furnace lining: essence and purpose, how it is carried out for various furnaces. Lining or why furnaces do not crumble from high temperatures

LLC "TPP" offers its customers the design and lining of steam and power boilers, as well as services for the comprehensive repair of tanks for various purposes.

The lining of the boilers includes the development of a tank design that involves the use of the most modern thermal insulation materials, including high-temperature ceramic insulation, supply of refractory materials in accordance with the project, restoration of the boiler lining.

To carry out the lining of the boiler means to increase the service life by 2 times, to reduce fuel consumption by at least 15% and, accordingly, the size of operating costs, a significant reduction in the total mass due to the use of lining materials and containers.

The company "Teplopromproekt" offers services for bricking hot water, steam, power boilers. We carry out tank lining work in Moscow using modern materials We provide comprehensive maintenance and repair services protective coatings oven units.

Types of jobs

Boiler lining is a process of finishing surfaces and creating a coating that protects equipment from exposure to a negative environment, high temperatures, mechanical damage. This work allows you to increase the fire resistance of materials, extend the service life of equipment. The material for the lining of the container must have high fire and heat resistance characteristics.

Boiler lining - creation of a system of fences with refractory and heat-insulating characteristics and protecting against external environment furnace and gas ducts. Thanks to this system, normal movement is ensured flue gases, heat losses are minimized. When lining the container, various materials are used. Depending on this, its three types are distinguished:

• Heavy. In this case, it performs brickwork based on a foundation. Suitable if the furnace or boiler has a low power. The disadvantage of this type is the large weight of the structure.
• Lightweight container lining. Formed using multiple materials stacked in layers. Used for masonry refractory brick, steel cladding and heat-insulating plates fixed on the boiler frame.
• Light. It is carried out using modern refractories.

All protection work heating equipment must be carried out by specialists. Unprofessional tampering will cause serious damage, increase the chance of burnouts, bricks falling out, etc. Your container could be severely damaged.

Services "Teplopromproekt"

Brickwork and lining of boilers and any containers in Moscow is one of the services provided by Teplopromproekt. We employ specialists with the necessary experience in the development and implementation of such projects. In our work we use modern refractories, ceramic fiber thermal insulation own production. Our company provides a full range of services. You can place an order by calling +7 495 933-25-76 (Moscow).

The construction of a brick oven for a house or a bath is a matter that requires certain knowledge in the features of masonry different parts designs. The process begins with studying the ordering sequence, and ends with the installation of the chimney. special attention requires laying out the furnace furnace and its direct protection. To begin with, let's figure out what it is - a lining, and whether it is possible to build it yourself.

When fuel is burned, the inner walls of the furnace are exposed to high temperatures. If you do not make additional protection, ceramic or kiln brick collapse in the first year of operation. The lining of the furnace was invented just in order to extend the service life of the entire structure and increase heat transfer. Another row is laid out inside the fuel chamber; fireclay bricks or refractory panels are used as the material. Chamotte lining withstands temperatures up to 1300˚С, is not subject to destruction from alkali, lime or other chemical elements. In addition, the protective material retains heat well, thereby increasing the efficiency of the stove.

Lining methods and their features

Having learned what a lining is, it is necessary to figure out in what ways it is possible to create a protective layer of the furnace. Internal lining works are divided into three types:

• Overhead. The refractory lining is laid out with fireclay bricks directly during the construction of the fuel chamber itself. Industrial furnaces with increased load are equipped with refractory panels.
• Printed. A solution of clay is applied to the inside of the masonry or treated with mastic from a heat-resistant material. Joints are carefully smeared to reduce heat loss.
• shotcrete. From a professional apparatus under high pressure, concrete mortar. This method is used for lining chimney pipes and large industrial furnaces.

External lining work is the finishing of the boiler with a protective mixture, which retains heat and, in the event of an accident, will not allow steam to enter the room.

Lining materials

Lining materials for strengthening the furnace structure are divided into quality classes:

• A class - the composition of the materials includes silica, which can withstand temperatures up to 1730˚С and has increased strength. The price of the goods is high, so it will not be profitable to use premium material for a bath or at home.
• Class B - materials consist of clay with a small proportion of impurities, ideal for protecting sauna stoves (fireclay bricks). Being on average price segment, the material shows high protective properties. Maximum temperature use - 1670˚С.
• In the class - low-quality materials, consisting of several components. Temperature limit - 1590˚С.

In the lining of metal and brick ovens have their own characteristics. Starting lining work with a metal furnace, it should be remembered that the metal expands when heated. Consequently, the protective masonry is made at a short distance from the inner walls of the furnace, and glass wool is placed in the resulting void - so the expanding metal will not damage the brick, and the wool will increase heat transfer.

The layout of the inner lining in a brick kiln is also erected at a distance from the base of the furnace. It's all about clay - when exposed to high temperatures, it expands and damages the brick if the laying is done closely.

Do-it-yourself furnace lining

From fireclay bricks:

• When working with a brick or metal stove, a small indentation should be made from the inner furnace walls to prevent premature destruction of the protective masonry.
• All seams are carefully smeared with mortar, and construction wool is placed between the lining and the furnace wall.
• Bricks are laid in a spooned part to ensure the correct thickness of the lining. If the protective row is thicker, the efficiency will decrease, since the walls of the furnace will not be able to warm up sufficiently.

From kaolin plates:

• The number of plates required for laying is calculated. The thickness of one sheet is 7 mm, therefore, before the calculation, the expansion of metal or clay during operation is taken into account.
• The plates are fixed with metal bolts, holes for fasteners are made in advance.
• It is necessary to cover the fuel chamber with plates strictly from the bottom up: the bottom, side walls, ceiling.

Coating the outside of the oven:

• Knead the solution from a dry fireclay mixture and dilute with water to a state of ductility, similar in consistency to glue.
• As soon as the boiler is completely covered with a fire-resistant mortar, the furnace should be fired so that the applied layer is fired.

A set of tools for work:

• Bulgarian for accurate cutting of bricks.
• Ruler-level.
• Container for mixing solution.
• Master OK.

Over time, even a high-quality furnace lining begins to break down. To reduce the amount repair work, the integrity of the protective layer inside the furnace or the outer lining of the boiler should be checked once a year. The resulting cracks are smeared with a solution of clay and fired. It is within the power of every person to independently perform lining work, even without the skills of a stove-maker, but it will not be superfluous to consult a specialist. If you are still not confident in your abilities, seek professional help.

The lining is obligatory for each furnace: home, bath or industrial. The protective layer will keep the furnace from premature wear, increase heat transfer and reduce the risk of emergencies. And having at hand the right tools and materials, lining is easy to do on your own.

Against the background of fuel combustion in the furnace, the temperature in it rises sharply. It usually reaches hundreds of degrees. Lining is the protection of the outer side of the furnace walls from overheating. Without it, strong heat provokes a change in the structure and basic properties of the refractory materials of the furnace, which leads to negative consequences.

Furnace lining is understood as a special brick shell, which must completely cover the entire inner surface of the furnace. Such protection against excessive heating performs a number of functions, extends the life of the furnace structure.

The lining is not an independent part, it is included in the whole kiln system. This explains active interaction specified layer and exterior trim, and with the inner part, where the combustion processes take place.

Initially, work in this direction begins with preliminary calculations, choice suitable material taking into account all the features to ensure the thermal protection of the furnace. Then the efficiency will be greatest.

With proper lining of furnaces, it is ensured additional protection its main components from the negative effects of factors of a mechanical and chemical nature.

How is the thermal protection of the furnace ensured

For lining furnace structures and ensuring the protection of their internal surfaces, you can:

• Use for processing inside the furnace a material characterized by a minimum degree of thermal conductivity.
• Allow excess heat to escape with smoke by installing protective screens to direct heat radiation.

In the case of installing specialized screens, we are talking about thermal protection. Thanks to this procedure, a certain part of the furnace is protected from thermal radiation, which is output to the outside.

If a inner part the furnace will be treated with special compounds, the heat generated will not go beyond the structure.

For the lining of furnaces, only materials with thermal insulation properties, most often it is:

• brick;
• refractory concrete;
• mortar.

Lining with fireclay bricks

On the modern market building materials, in the conditions of their wide variety, fireclay bricks are especially in demand. In the course of its production, it is supposed to use a special powder based on baked clay.

The final stage of production is firing. It is performed at very high temperatures.

This variety, unlike simple bricks, has excellent thermal insulation performance. Therefore, the lining of the furnace, that is, laying it out inner surface, is performed by this material. This work has a number of features.

Against the background of high temperature, a gradual displacement of the layer located outside by fireclay bricks occurs. This is accompanied by the appearance of cracks in outer surface furnace, which over time may cause its resolution. Such consequences are dangerous - it is fraught with the penetration of harmful carbon monoxide inside the premises. Therefore, it is important to carry out the lining of the combustion chamber in strict accordance with the basic rules.

Rules for laying fireclay bricks

This version of the lining as a thermal protection of the furnace, experts call the most effective. Its cost is small. The basic rules for arranging such protection are as follows:

• To fill the joints, it is permissible to take only specialized solutions based on clay, designed to work with the specified type of brick.
• When working with a metal firebox, it is important to create a gap between it and the masonry. This will be the key to maintaining the integrity of the elements of the furnace during its operation.
• Individual bricks are located strictly "edge to edge" along the perimeter of the inner surface of the furnace. You don't need to move them.
• When lining the furnace of a brick oven, the masonry is joined without additional dressings with the main seam vertically.

In any case, fireclay bricks should not be placed close to the walls of the furnace.

To connect bricks located with outer side, clay is used. In order to prevent accidental destruction of the finished seam due to its overheating during the operation of the furnace, ready solution first evaluated for plasticity. To do this, it is enough to connect a couple of bricks with it, and then burn them.

Only the mortar that has retained its properties even at high temperatures can be used in masonry.

Features of the choice of fireclay bricks

For lining, samples that are marked ShA or ShB are suitable. Here, the first letter represents the heat resistance of the brick, while the second represents a certain level of fire resistance.

In order for the created furnace protection to work, it is necessary to carefully select materials for it. Will need to evaluate external state bricks (the surface will be rough, but not smooth), try to split them. A high-quality sample will not crumble, but will be divided into large elements.

Several types of bricks cannot be used in one masonry - they are characterized by different thermal expansion.

Brick furnace lining

Difficulties arise when lining not only metal, but also brick furnaces. Both types have their characteristic properties that need to be taken into account.

As part of the lining of brick kilns, it is strictly unacceptable to lay the protective layer close to or in close proximity to the outer walls of the kiln and their individual elements.

Against the background of an increase in internal temperature, so-called thermal cracking is often observed. In this case, excessively heated internal elements begin to displace those that are located outside from their normal position. If a external walls cannot cope with the load, against the background of expansion from the inside, they diverge to the sides with cracking and destruction. This is fraught with the penetration of carbon monoxide into inner space premises, which is extremely dangerous.

In some cases, with illiterate masonry, the seam can completely collapse. This happens when clay with a minimum degree of adhesion was used for laying the outer layer. Therefore, at the stage of laying the furnace, the prepared solution is first tested at high temperatures.

Peculiarity metal furnaces that the thermal expansion rates of metals are not the same. Therefore, a small space is necessarily left between the furnace and the lining layer. This will prevent the destruction of the protective layer when the size of the metal part changes.

In the specified space, special materials with non-combustible properties, such as asbestos or basalt wool, are usually placed. The use of asbestos is permissible only for structures located in non-residential premises. But there shouldn't be any air.

To make a metal furnace the safest, the boiler lining is often carried out from two sides at once. Through this step, the best warm-up is achieved. But this point of view is partly correct. This is explained:

• High heat capacity of brick;
• Low thermal conductivity of bricks.

This combination of properties is a guarantee that the heat will not go beyond the furnace, and will subsequently be removed with the outgoing smoke. But with double-sided lining of the furnace wall

begin to burn out due to lack of air needed to remove heat energy.

Therefore, a double-sided furnace lining made of metal is a measure for thermal insulation, and not thermal protection. But the cooled air masses must be able to enter the furnace.

Furnace lining is a necessary component of its long and safe operation. But it must be carried out in strict accordance with the basic rules and with the use of high-quality and suitable materials.

The construction of furnaces requires high-quality and refractory materials that can withstand high temperatures, chemical and thermal effects. If necessary, a lining is arranged inside the furnace - an additional shell that performs the following tasks:

• increases the service life of the furnace;
• reduces heat loss;
• protects the casing from high temperatures and chemical reactions.

Note that the main purpose of the lining is precisely thermal protection, and not thermal insulation. Otherwise, the heat will linger inside the furnace and leave with smoke, significantly reducing the efficiency of the furnace.

Depending on the tasks, choose a way how to equip the lining:

• install protective screens reflecting thermal radiation;
• lay out additional walls inside the furnace;
• treat the internal surfaces with special materials.

Lining in various furnaces

In a metal oven

When working with metal furnace the difference in thermal expansion of materials should be taken into account. Therefore, a gap must be left between the lining and the furnace wall, which is filled with non-combustible material. Usually this basalt wool, but if the furnace is operated in non-residential premises, then you can use asbestos. Brick laying on both sides to improve the heating of the furnace is the wrong decision. The low thermal conductivity and high heat capacity of the brick will improve thermal insulation and limit the flow of cooled air into the furnace, causing burnout of the surfaces.

In a brick oven

Laying the lining close to the bricks that form the outer walls is unacceptable. Reason - thermal expansion inner layer, and, as a result, cracking of the outer. Cracks can also be caused by overheating of the outer walls due to errors in the choice of materials and arrangement of the lining, which leads to the leakage of carbon monoxide into the room. Importance has a quality of seams, which depends on the clay used. To check, you can connect 2-3 bricks and expose to high temperatures. If the results are unsatisfactory, it is necessary to change the composition and repeat the tests.

Helpful Hint: To speed up the test, you can make several versions of the mixture at once and fire at the same time. Don't forget to chart samples!

in a steam boiler

There are three types of lining in furnace steam boilers:

• Heavy. They make 2-3 layers of fireclay bricks for boilers with weak shielding. The temperature in the furnace can sometimes exceed 1200 ° C, which increases the risk of fire, and such protection will reduce it to a safe 60-80 ° C.
• Lightweight is a single-layer brick lining. At the same time, each of its belts must rest on the frame of the boiler or an intermediate beam. To reduce the outside temperature and increase the efficiency of the boiler room, the surface of the heating installation is covered with non-combustible material and metal sheets.
• Pipe lining is the simplest of linings. For the arrangement, a viscous non-combustible mass is prepared, which must be applied to the pipes in 2-4 layers. The design will better resist thermal expansion if a reinforcing mesh is used.

Domestic lining

Usually, in domestic conditions, lining is the laying of fireclay bricks inside the firebox. Therefore, some prefer to do it on their own, without resorting to expensive specialist services. And immediately the first questions begin to arise for the beginner. Let's try to predict them in the following tips:

• For fireplaces and classic stoves, one layer of lining from standard brick 250x150x65.
• As a rule, laying is carried out vertically, otherwise a significant part of the internal usable volume is lost.

A distinctive feature of fireclay products from classic ones is the minimum thermal expansion. Therefore, a large gap between them should not be left. To connect the masonry elements, a clay solution is used and a metal spike is installed. lining on cement-sand mortar do not do. At the point of contact with metal product, for example, with a grate, it is necessary to make gaps. Frequent resizing metal objects from heat can eventually squeeze them out of the masonry, deform or destroy.

The most popular lining solution is prepared on fireclay clay with brick dust.

However, if the stove is designed only for firewood, you can use a classic mixture of clay with a small addition of sand.

The materials used for lining furnaces and boilers are divided into three classes:

"BUT"— consists of artificial or natural materials based on silica;

"AT"- represented by classic materials based on clay;

"WITH"- from various refractory solutions and other materials.

Protection of the inner surface of the furnace can be performed:

• fireclay brickwork;
• applying a non-flammable mixture;
• install protective screens.

The latter method is well suited for installing metal sauna stove. In other cases, it is ineffective due to large heat losses. For masonry, it is recommended to take fireclay bricks that meet the requirements of GOST 390-96. Classic is not recommended. It breaks down quickly and needs to be replaced. Previously, before the advent of fireclay materials, they used products of the M-300 brand, which even today have comparative reliability and durability, attract by price, but are inferior in efficiency.

For stucco ovens

Stucco stoves, which are built using the adobe method, gradually begin to displace the classic stone or metal heating structure in the baths. The lining for them can be made of fireclay bricks, however, experts advise using one of the special mixtures:

• mullite;
• fireclay;
• corundum.

The work becomes quite simple, even for a beginner: it is enough to dilute the selected composition warm water in place and apply the solution to the surface to be protected. The monolith obtained after drying does not crack.

About repair

During operation, it is imperative to carry out a periodic thorough inspection of all surfaces (for example, before the heating season). Timely detection and repair of damaged areas will help to avoid many unpleasant situations - from inefficient operation (or complete shutdown) to carbon monoxide poisoning.

Minor damage and shallow cracks can be patched with a mixture of aluminous cement and fireclay powder. Only after a week, the repaired places can be dried with an open flame, otherwise they can quickly collapse again. Familiarity with the features of the lining for various domestic ovens, fireplaces and heating boilers can create a dangerous illusion. Indeed, some simple things you can do yourself. Moreover, the rates for the work of a good kiln master decent. But do not forget that the retribution for mistakes can be disproportionately greater.

• competent choice of lining and its engineering calculation is a guarantee of trouble-free operation with high efficiency the entire heating structure;
• a reasonable choice of materials will ensure the reliability and durability of the work done;
• correct start.

Video

The idea of ​​installing an environmentally friendly fireplace instead of a hearth that requires firewood and constant cleaning appealed to many owners of private houses and cottages, followed by owners of housing in high-rise buildings. They preferred electrical devices, and for those who wanted to have a "live" fire, advanced technologies were useful, which were embodied in biofuel fireplaces. An excellent example of a state-of-the-art instrument,…

The production of bricks today is carried out on modern equipment using innovative technologies from various raw materials. Despite this, traditional clay and sand remain the main components, which are widely used in the production of solid and hollow bricks. But they are not suitable for the manufacture of a furnace, because in the process of prolonged exposure to an open flame they quickly collapse. Therefore, for these purposes it is necessary ...

Creation of original and practical project, which could make it possible to optimally combine the quality and comfort of using such a heating element as a potbelly stove. It should be useful not only for summer residents or garage owners. But also to everyone who has ever encountered a heating problem during a power outage central option heating. This problem is especially relevant for residents of private and country houses ....

According to the laws of physics, the heated liquid rushes up, which was the basis for the operation of the furnace heat exchanger. The heat exchanger has several pipes, one of them goes up hot water. According to another, cold is served, which replaces the hot, after which this process is repeated. As a result of the circulation in the system, the water is heated. Several factors influence the heating time of water: power ...

At its core coaxial chimney is two pipes that are located one inside the other. These pipes have one common axis. By inner tube moving gas mixture. As for the outer pipe, it represents the path for air currents from the street, which move in a heated state. The device also has a condensate collector and a device that cleans gases. Gas…

Quite often, surfaces need reliable protection from thermal, mechanical, chemical or physical damage that occurs during operation. For example, damage to equipment used in the mining and metallurgical industry is regularly encountered. It is also required to enhance the refractory properties in blast furnaces for smelting. In both the first and second cases, an additional finish is made with a special material.

Such protection is needed not only in serious production, it will not be superfluous to have it in a simple home fireplace or stove. And despite the simplicity of the task, many make a huge number of mistakes by choosing the wrong materials or the method of their installation. It is best to talk about this in a separate article on the construction topic, and we will tend to discuss the metalworking and related production.

So, if we talk about blast furnace production, then it is necessary not only to protect the casing from exposure to excessively high temperatures, liquid metal and slag, which can cause fatal damage, but also to minimize heat losses. At the same time, it is also important reliable protection from all kinds of aggressive reagents.

Thanks to the lining, the furnace becomes completely sealed, and it creates the necessary gas density. Also, its service life is significantly extended, because various indicators of resistance (mechanical, chemical, etc.) increase. This result can be achieved with special layered-porous materials.

2 Lining mixtures for finishing

Today there are many different materials for lining, in principle, their properties are completely dependent on the purpose, but, nevertheless, they must necessarily have excellent wear resistance, good impact resistance, maintainability, abrasion resistance, wide temperature range, water repellency and resistance to aggressive environments. So, for example, a special dry spinel-forming mass has found its application for the lining of an induction furnace.

Its advantage is a very low coefficient of volumetric expansion even when heated to fairly high temperatures. Due to this property, cracks almost never appear in it, even with a strong thermal difference. So it is possible to carry out more than a hundred melts in such a furnace without serious damage and loss of material. One of the representatives newest generation lining masses is vibrocompacted quartzite, the basis of which is expanded clay. It has also found its wide application for the processing of induction electric furnaces.

Usually, only the highest quality expanded clay is taken for this purpose, and it is sorted according to the size of the granules. In this way, it is possible to achieve an improvement in the installation properties due to a good laying density. It is often used for furnaces specialized in iron foundry operations. If it's about induction furnaces, in which smelting is carried out and (stainless, carbon and high-alloy), then in this case the lining material will be a mass based on sintered alumina.

This decision is justified by its advantages: excellent resistance to aggressive chemical environments, the ability to withstand very high temperatures (up to 1815 ° C). The lining treatment of ladles, kiln chambers, covers, exhaust channels is often carried out refractory concrete, which is ideal for cast products. Its advantages include excellent wear resistance (moreover, this parameter does not depend on temperatures), impact resistance and excellent surface texture.

In addition, there are also mullite mixtures, as well as mats that can withstand exposure to very high temperatures. You can also find fireclay materials, which are produced in the form of bricks or a special mixture.

Both options are different high cost which makes them very popular. For the repair of furnaces, special adhesives, putties and mastics are used, which have a pasty consistency. Their features include the possibility of application even during operation of the furnace. Still quite common in this area and special roll materials such as kaolin paper (about 5 mm thick), cardboard (about 7 mm) and cotton wool. The latter is quite easy to tear, and therefore it is used in the form of pieces and lumps of the required size.

3 Other liners and selection criteria

Let's start with metal protection. For this purpose, chromium, manganese steels, as well as different types cast iron. But in order to create protection for non-standard-shaped parts, they make a rubber lining in which vulcanized rubber is used. This material is melted and poured into the desired shape, in addition, it differs quite long term services, which is not so unimportant!

In the food, mining and other industries, they are mainly used polymer types linings. The list of their advantages can be continued for a very long time, the main ones are: resistance to chemical attack, aggressive environments, high temperatures. In addition, they are distinguished by excellent wear resistance, impact strength and water repellency. Another type that is worthy of attention is protection with the help of basalt materials.

It is mainly used for various bunkers, tanks and chutes subject to negative impact alkalis with acids. Also, the use of such a lining will be very effective as an anti-corrosion coating. In addition, the treated surface will not be at all afraid of wear from interaction with abrasive particles.

In an industry that is subject to severe operating conditions such as exposure to excessively high temperatures, severe abrasion, elevated level humidity, it is important to use ultra-high molecular weight polyethylene, which is characterized by a low tendency to abrasion, excellent resistance to aggressive environments, hydrophobicity and a rather long service life. When choosing the parameters of the protective layer for furnaces, one should be guided by the following indicators: body thickness and outer cladding, as well as the temperature that will be inside the furnace.

Besides, almost all materials are subject to thermal expansion, so a small gap is also required (no more than 10 mm). What about the lining layer, as it can be either double or single, it all depends again on the above factors. Fireclay elements are attached to each other by means of metal pins, thus reinforcing the structure is also carried out, which acts as a guarantee of additional strength.

Please note that in no case can different types of bricks be used at the same time, as they differ in different thermal conductivity and degree of linear expansion. So gradually cracks appear, and you have to redo everything anew.