What does a chimney mean?

Yā NC not ng is one of the oldest and most important anti-pollution equipment.

Chimneys were invented long ago.

When primitive people discovered fire, they also found a truth that where there is fire, there must be smoke.

The earliest chimneys were indoor ventilation holes.

When "fire" was brought into the room to cook and keep warm, smoke also came in.

This forced people to try to open some air holes in the roof and walls to drive away the smoke in the house.

As a standard human practice, this method has been preserved for hundreds of thousands of years.

It took mankind a long time to improve this big chimney.

In the past, academic circles generally believed that Egypt and Mesopotamia, the birthplace of human chimney civilization, had warm climates, so family heating did not become an urgent problem.

Finally, a French expedition announced that they had discovered a 4,000-year-old palace equipped with many chimneys while excavating the huge ruined city of Mali in the upper reaches of the Euphrates River.

So that the above viewpoint can be changed.

Indeed, when the Romans invented a novel hot gas heating system, they greatly improved their chimneys.

However, the popular view still holds that the concept of "chimney" was introduced into western Europe from the east by Syrians, Egyptians and Jewish businessmen more than 200 years ago.

At present, the highest single-tube reinforced concrete chimney in China is 2 10 meter.

The tallest multi-tube reinforced concrete chimney is a 2 12-meter-high four-tube chimney in Qinling Power Plant.

At present, there are dozens of chimneys over 300 meters high in the world. For example, the single-tube reinforced concrete chimney of Mitchell Power Station is as high as 368 meters.

Classification generally includes brick chimneys, reinforced concrete chimneys and steel chimneys.

Its materials are generally divided into several types: brick masonry, iron, asbestos and pottery, which are generally used in small places, such as homes and offices.

Industrial chimneys are mostly cylindrical, with fine top and thick bottom, and are generally used in large industrial workshops, such as large boilers, smelters and power plants. The stoves in rural areas of China and the chimneys in northern heatable adobe sleeping platform are mostly square bricks.

Steel chimney, concrete chimney, cement chimney, square chimney, chimney wall made of steel.

Reinforced concrete chimney Reinforced concrete chimney wall material is reinforced concrete chimney.

A brick chimney with brick walls.

Self-supporting steel chimney The self-supporting steel chimney cylinder and foundation together form a steel chimney with stable structure, without any additional stress support.

Guyedsteelchimney, a cable-type steel chimney, and cable * * * together form a steel chimney with stable system.

Frame steel chimney Frame steel chimney tube and tower together form a stable steel chimney system.

Single-tube chimney Single-tube chimney lining is a common chimney supported on the wall in sections.

A chimney with a smoke exhaust pipe is arranged in the pipe wall of the pipe-in-pipe.

Multi-pipe chimney Multi-flue chimney A chimney consisting of two or more smoke pipes and a wall or tower.

The superposition effect of action principle effect is the result of the combined action of hot pressing caused by indoor and outdoor temperature difference and outdoor wind pressure. Usually, the former is dominant, and the hot pressing value is directly proportional to the air density difference and the height difference of air inlet and outlet caused by indoor and outdoor temperature difference.

This shows that the higher the indoor temperature is than the outdoor temperature, the higher the building is, and the more obvious the stack effect is. At the same time, it also shows that the stack effect of civil buildings generally only occurs in winter.

As far as buildings are concerned, in theory, half the height of buildings is taken as neutral surface, and it is considered that rooms below neutral surface are infiltrated with air from the outside, while rooms above neutral surface are infiltrated with air from the inside.

Negative Effects Under the action of stack effect, organized natural ventilation and smoke exhaust can be realized indoors, but its negative effects are also various: First, sandstorms blow into the room through various holes and gaps in the lower floor, consuming heat and polluting the room; Secondly, the elevator door can't be closed normally in the process of wind leading from the bottom hall door to the top floor through the elevator shaft; Thirdly, in case of fire, with the rapid increase of indoor air temperature, the volume increases rapidly, especially in stack effect. At this time, all kinds of vertical shafts become vertical channels to draw fire smoke, which is the main way for the fire to spread vertically, thus fueling the fire and expanding the disaster.

Some data show that the vertical diffusion velocity of flue gas in vertical tube well is 3-4m/s, that is to say, it only takes about 30s for a high-rise building with a height of 100m to escape directly from the bottom to the top.

If the burning conditions are met, the whole building may form a sea of fire in an instant.

In order to effectively reduce the negative impact of stack effect, the following measures can be taken.

Take measures 1. In winter, air mainly flows into the room from the ground floor through various external doors. The most direct method is to set all doors leading to the outside of the building as two doors, revolving doors, door buckets or air curtains inside the outer doors as far as possible, which is especially necessary for hall doors. For the external doors of secondary passages and underground parking lots, doors should be installed in winter, and at least thick curtains should be hung.

In winter, the ventilation hole at the top of the elevator shaft should be properly adjusted or closed.

2. For heating buildings, try not to make the lower indoor temperature higher than the upper indoor temperature.

3. When a fire breaks out, stack effect will not only be produced through various shafts in any season, but also stack effect may be produced through air-conditioning pipes passing through the floor in a small range and even some humble pores.

In this regard, the Code for Fire Protection Design of High-rise Civil Buildings (GB50045- 1995) clearly stipulates the following.

(2) "For high-rise buildings whose building height does not exceed 100m, cable wells and pipeline wells should be separated every 2-3 floors by incombustible materials equivalent to the fire resistance limit of this floor; High-rise buildings with a building height exceeding 100m should be separated on each floor by incombustible materials equivalent to the fire resistance limit of that floor. "

Due to construction defects and various pores formed at the roots of bridges and pipelines, they must be packed and compacted with incombustible materials.

Chimney is a kind of exhaust tool, which is used to remove gas or smoke produced by fire.

It is a towering structure that emits smoke into the sky.

It can improve the combustion conditions and reduce the pollution of flue gas to the environment.

Summary of chimney design of high-rise buildings Hu Yu believes that since the reform and opening up of Central South Architectural Design Institute, high-rise buildings have mushroomed all over the country. According to China's national conditions, most high-rise buildings still consider using oil-fired or coal-fired boilers or lithium bromide units as heat sources. The chimney installation in their computer room, especially in coal-fired boiler room, is often a headache for designers. If independent chimneys are built, it is impossible to set them independently because they are all in downtown areas. And the cost is expensive. If there are mistakes in design or construction, it will cause irreparable economic losses. For example, the brick chimney attached to the wall of a 28-story residential building in a unit in Wuhan was cracked due to certain problems in design and construction, and the smoke penetrated into all rooms, so the chimney could not be maintained and used, and the steel chimney was rebuilt.

Causing economic losses of hundreds of thousands of yuan.

In the design practice, we learn from others' experience and lessons, make bold innovations, adopt new technologies according to the site conditions, and strictly require the construction unit to construct according to the drawings, thus solving some problems in the chimney design of high-rise buildings. Many projects have passed the completion acceptance of relevant departments, running for several years without problems, and some projects have won the second prize of provincial excellent design (Hubei Construction Bank Office Building and International Finance and Trade Building), which has achieved good economic and environmental benefits.

The office building of Hubei Branch of China Construction Bank (also known as Hubei International Finance Building) is one of the first high-rise buildings in Wuhan. The main building of this building has 26 floors and is nearly 100 meters high. Because of the energy policy at that time, only coal could be used as fuel. However, because the building is located at the intersection of Zhongnan in the downtown area of Wuhan, the environmental protection requirements are particularly high, and the coal-fired boiler is not suitable for the roof, so it can only be arranged on the first floor of the podium. According to the boiler smoke emission standard, the chimney of the boiler room in this project can be designed as 30M (with a total capacity of 5t/h). However, because the height of the building is close to 100M, and there are Zhongnan Commercial Building (about 50M high), the planned Material and Trade Building and Shangzhong Plaza (all built later) around it, the above emission standard also stipulates that "when there are buildings within a radius of 200M around the chimney, the height of the chimney should generally be.

Some people hope that we can design according to 30M, so that the construction unit can save a lot of investment and our design is much more convenient. If we make a fuss about "general" and "should", it is not impossible to ask the environmental protection department to lower the requirements. However, from the perspective of environmental protection, from the long-term perspective of urban development, and from the impact of boiler room flue gas on this building-because the boiler room is located in the northwest of this building, the boiler operation time is mostly in winter, and the harm of flue gas to the building is self-evident-it is beneficial to build the boiler chimney higher, so we decided to build the boiler.

However, the real design is very difficult. First of all, this building is one of the first landmark buildings in Wuhan and the office building of Hubei Construction Bank. Urban planning needs luxurious and spectacular exterior decoration. Therefore, for various reasons, the chimney position 3 meters above the roof is not considered in the scheme design. If brick chimneys or steel chimneys are considered in the construction drawing, it will not only destroy the image of the building, but also be structurally unsolvable.

Secondly, if an independent brick chimney is built, the cost will be as high as one million yuan, and it will vary from place to place, which will not be harmonious with the whole building and will destroy the scenery. What should I do if I can't even reach 30M by sticking it on the podium? After many consultations with civil engineers, we finally squeezed out a triangular position with an area of about 2.5M2 near the elevator shaft of the main building and decided to set the chimney here.

The installation of chimneys in inner tubes is still a new problem in China and even in Asia. First of all, the flue gas has a great influence on the thermal stress of the inner cylinder. Secondly, the boiler room is not on the main floor, but in the podium, with a horizontal distance of tens of meters from the inner cylinder. The flue must pass through several rooms on the standard floor, which will affect these rooms.

Especially in winter, boilers usually run more, and the temperature difference between inside and outside the chimney is larger. To avoid its influence, the chimney is treated as follows: 1. According to the construction method of ordinary chimney, the gas barrier is expanded to 100MM, and the gas barrier of ordinary brick chimney is 50MM, which is set to protect the outer wall of the chimney, and the object we want to protect is the whole inner tube of the building, even the whole building. Therefore, we will

2. Masonry the inner wall of refractory bricks with the same height as the chimney, and use red bricks when the flue gas humidity is lower than 500℃. Obviously, the humidity of the outer wall of the chimney is not equal to the room temperature, and the compactness and thermal insulation of refractory bricks are much better than ordinary red bricks, which can effectively prevent the influence of flue gas humidity on the inner cylinder.

3. The joint between chimney and flue is provided with expansion joints, and the flue (steel) is strictly insulated.

4. The outer wall of the chimney (that is, the inner cylinder wall) is poured with refractory concrete, which further eliminates the influence of flue gas.

By taking the above measures, the influence of the temperature difference between inside and outside the chimney on the inner cylinder of the main building is completely avoided. If you don't explain, no one knows that the chimney of this building is located near the inner tube aisle of the main building.

Several years' operation proves that this method not only solves the problem of installing chimneys in high-rise buildings, but also saves a lot of investment for construction units (compared with independent chimneys, it saves about 700,000 yuan, and compared with wall-attached chimneys, it saves about 1/3, reaching about 300,000 yuan).

) has produced huge economic benefits, more importantly, because the chimney is very high, it has eliminated the pollution of flue gas to the surrounding area and produced more obvious environmental benefits.

Meida Jianhua Hotel built by Hubei Post and Telecommunications Administration is a large building with 28 floors and a height of 100 meters. The boiler room is set in a four-story podium, and the main flue of three oil-fired boilers is just in the corner of the building's outer wall. We also cut a triangle with an area of about 2M2 on the corner. Because it is on the outer wall, the influence of thermal stress is smaller than that of the inner pipe, so the air insulation layer is only 70 mm. Other methods are the same as those of Hubei International Finance Building, but after the boiler is put into operation, it is found that the room near the chimney is on the high side. After analysis and investigation, it was found that when the construction unit laid refractory bricks on the inner wall of the chimney, it did not follow the chimney masonry technology at all, and even the scaffolding holes on the inner wall were not blocked. There are 250 × 200mm big holes and several 20mm wide gaps up to tens of meters. After plugging the leak and taking some other measures, the humidity of the room was reduced to meet the requirements of normal use.

The equipment for attaching the stainless steel chimney to the wall is located in Jinbo Town, Zhengzhou, Henan Province. The boiler room is located on the first floor of the podium, and the boiler room is connected with the 33rd floor commercial and residential building. The original design office building has 46 floors, and the chimney is connected with the office building. However, due to some reasons, only a few floors of the office building have been built, and the commercial and residential buildings have been completed. After research, the wall of the commercial and residential building is attached with a stainless steel chimney, and the following measures have been taken.

1. In order to avoid the high cost of chimney replacement caused by corrosion of ordinary steel, stainless steel was adopted after calculation.

2. In order to reduce the cost, the installation method of short flange with less stainless steel is adopted, that is, the distance between two flanges is only 2 meters, and the chimney is supported on the flange, thus reducing the wall thickness of the lower chimney. According to the calculation, if the weight of the chimney falls on the foundation, the wall thickness of the lower chimney will exceed 10 mm. If the above method is adopted, the wall thickness of the upper and lower chimneys will be 4-5 mm.

The support and fixation are made of ordinary steel that does not contact with flue gas.

3. Take thermal compensation measures for the chimney to prevent the damage caused by thermal expansion between the chimney fixing brackets.

The boiler room has been running for several years, and everything is normal.

Several problems in the construction of four-wall brick chimney.

1, please have a professional team for furnace or chimney construction.

2. The inner wall must be smooth and dense to reduce heat conduction.

3. The width of air insulation layer must be ensured, and two layers of insulation layer are not allowed to be uneven.

4. Building firebricks on the interior wall is absolutely not allowed to build scaffolding on the interior wall, but only on the exterior wall, because the scaffolding holes are not tightly blocked.

5. The supervision company must supervise at all times, otherwise the future trouble will be endless. For example, after the operation of Ramada Wuhan Hotel, it is very difficult to check because it can't stop the boiler, and it is even more difficult to plug the loopholes, and the effect is not good.

High-rise building is a new thing developed in China in recent years. With the further development of the four modernizations, high-rise buildings have sprung up. Because they are generally built in densely populated cities, China has few heating centers for the time being due to historical reasons, so boilers are essential. How to solve the problem of smoke exhaust in high-rise buildings (that is, chimney design) is a very difficult topic. If we don't do it well, it will harm people now and in the future, but as long as we study it carefully.

Construction sequence: the space of grid and outer frame area is leveled and tamped → C30 concrete is poured on the grid foundation, with the thickness of 150mm → the frame pad is erected → the chimney cylinder is laid → the firebrick is laid → the expanded perlite insulation layer is filled → the frame is turned over → the safety net is erected at the elevation of 2. 1m → the inner frame is erected → the cylinder is laid.

Construction preparation ①

Firstly, the center, axis position and elevation size of the chimney are determined.

Center pouring concrete to fix a steel bar, draw a cross line, determine the center position, and cover it with an iron drum made of steel plate.

②

Five ruler boards.

Planing the wood board with length 1 0m, width 150mm and thickness 25mm, using Mo Dou to pop up the center line first, and then making a slope of 2.5%.

③

Wire hammer.

The steel plate is welded into a cone shape, and concrete is poured into it to make a wire hammer, which weighs 3 kg -5 kg. Hang the wire hammer in the center of the wheel plate with 16# lead wire, and determine its center by centering with the central pile.

④

Wheel plate

Plant a wood board with a length of 4 0m, a width of 100mm and a thickness of 50mm, put a wood board with a length of 2.2m, a width of 150mm and a thickness of 30mm on the top with the center as the axis, carve it into a grid according to the inclination of the chimney of 2.5%, and rotate the wheel plate to measure the circumference of the outer ring of the chimney.

⑤

The top beam of the tic-tac-toe frame is welded by two metal frame rods, and two pulleys are fixed in the middle. The center of the tic-tac-toe frame is 1 and the edge of the tic-tac-toe frame is 1.

⑥

Brick hanging cage, welded with d8mm steel bar, limited to 30 bricks at a time.

⑦

Mortar barrels should be hung below 0.05m3 at a time.

⑧

Cross bars with different diameters are cut into 1.0m- 1.5m with steel pipes with diameters of 50mm and 60mm respectively, and a group of cross bars are formed by drilling holes on them, inserting them and fixing them with steel bolts.

Its characteristic is that it can be telescopic and easy to use.

Masonry engineering should build three layers of brick joints, with annular vertical joints staggered 1/2 bricks and radial joints staggered 1/4 bricks; The dosage of 1/2 brick shall not exceed 30%, and bricks below 1/4 brick shall not be used, and masonry shall be carried out after inspection.

When laying bricks, check with level and ruler. After 300mm of bricklaying, that is, after five layers of bricklaying, 300mm of refractory bricks are laid, and expanded perlite is filled in the middle. It is advisable to build 1.2m high every day.

The installation of vertical reinforcement, annular temperature reinforcement and ladder shall meet the design requirements.

After each step of laying bricks or stones, check the center and the surrounding area with a messenger hammer with a pulley plate, and check with a theodolite.

Below 10.0m, temperature joints of 1 0m shall be set at intervals of 5 0m high along the circumference of the cylinder, and masonry shall be staggered up and down, and temperature joints shall also be set at variable cross sections.

Scaffolding engineering ①

First, the periphery of the chimney is leveled and tamped, C30 concrete with a thickness of 150mm is poured on the basis of the grid, and then wooden boards are laid. The height of the tic-tac-toe frame and hexagonal metal frame is 20m, and the tic-tac-toe frame is next to the chimney ladder, with the height of 23m at first.

②

The tic-tac-toe frame of 1 chimney stands in the north of the chimney, and the hoist is located in the east of the tic-tac-toe frame; The tic-tac-toe frame of No.2 chimney is erected on the northwest side of the chimney, and the hoist is located on the west side of the tic-tac-toe frame. See figure 1 (page 33) for details.

③

The shelf shall be at least 200mm away from the periphery of the chimney, and the shelf board shall be made of wood with a thickness of 50mm, and there shall be no probe board. It is recommended to use butt plates and hang vertical safety nets.

Every 10 Milla, the tic-tac-toe frame is provided with a cable wind rope, and two safety nets with a width of 6m are hung at the outer side of 3m and10m. ..

④

Hang a 6 0m wide 1 safety net at the elevation of 2 1 0m. The inner ring of this safety net is fixed on the brick chimney with d6mm steel bars. The method is to use the characteristics of thin on the brick chimney and thick on the bottom, and tie it in the high place and naturally tie it down in the low place.

The outer ring is supported by the frame rod, and it will automatically spread out when it is cut from the ladder mouth when it is removed.

In this way, the metal frame below 20.0 m can be dismantled in advance to facilitate turnover.

⑤

For internal scaffolding with a height of more than 20 meters, two variable-diameter crossbars should be used for erection, and the frame eyes and crossbars should be plugged with wooden wedges.

Below the elevation of 30.0 m, you can kidnap the pole on the crossbar, lay the wooden frame board and make it into an arc.

Because the diameter of the cylinder becomes smaller at an altitude of more than 30 meters, the frame plate can be directly placed on two cross bars with different diameters, and the frame plate can be fixed with 20 # lead wire. 12.

When the frame is laid and turned over, these two reducing rails are left behind. When removing the frame, from top to bottom, remove it while removing it, and repair the frame eye.

The height of the tic-tac-toe frame should be at least 2 levels higher than the chimney at a time.

For formwork works, there are 1 ring beams at the elevation of 26.7m and 39.5m, the steel bars shall be bound first, and the formwork support can be 450mm× 100mm or 600mm× 100mm steel formwork.

First, fix the internal model, support it with wooden keel and frame rod, and tie it with 12# lead wire.

The external mould is placed on the head of D160mm steel bar which is embedded in the cylinder in advance and exposed at intervals of 500mm, and it is bound with 12# lead wire and fixed externally with steel wire rope and chain block.

After watering, dismantle the inner and outer molds, and then lay bricks.

The vertical reinforcement of the reinforcement engineering pipe body is d 10mm, the spacing is 500mm, and the overlapping length of reinforcement is 40d (excluding hook). In order to facilitate aerial work, the length of reinforcement should be 3.0m-4.0m ..

Ring temperature reinforcement is d8mm, spacing is 250mm, reinforcement within 500mm at variable cross section is d8mm, spacing is 125mm, and reinforcement lap length is 40d (excluding hook). Ladder installation should be consistent from top to bottom, and the top should be aligned and fixed before welding.

Demolition project chimney demolition project: manual demolition, using manual equipment.

Such as sledgehammer, crowbar jack and other things are all dismantled manually, and are generally used in an environment without a garden around the environment.

What should be considered is that we must seriously consider the safe construction environment, safe income and expenditure methods and the throwing of broken materials; Machine disassembly: air hammer, hammer, hanging hammer, hydraulic arm and other machines can be used; Attention should be paid to the safety of the longitudinal machine, the space of the longitudinal machine, the ability to set up equipment deployment and the cover of the longitudinal hand; Demolition of chimney by blasting: including pre-weakening the building, and then pulling down the cable by blasting.

The qualification of operators, safe storage, initiation cover, ignition rhythm and the use of explosion-proof milling should be considered when using.

When pulling down the cable, we should consider the professional requirements of the staff, the choice of materials and enough working space; Group demolition: Group demolition, also known as chimney placement, is a technique of directional demolition of chimneys in the upper hand environment in the garden.

Project quality objectives and quality assurance measures 1

The material quality must meet the design and specification requirements, and there must be a certificate of approval and a test report.

2

Mortar and concrete have a notice of test ratio in advance, which should be accurately measured during construction, and test blocks should be set up according to regulations to test the strength of mortar and concrete.

three

When laying, the bottom should be laid first, and the seam should be left according to the specification requirements. Mortar plumpness should reach more than 95%. Always lean on the board, hang it with a hammer, level it, and measure the circle with a roundness instrument (track gauge).

four

Seriously implement the system of self-inspection, mutual inspection and full-time inspection, check while doing, make original records, and carry out construction in strict accordance with the requirements of specifications and operating procedures.

five

Carefully calculate the chimney diameter at each height to facilitate random inspection at any time, strictly control the elevation and axis, and make written and oral quality disclosure.

Case Location Chimney Company —— Jiangsu Zhongjie Gaokong Jian 'an Anticorrosion Engineering Co., Ltd.