Boiler type

There are many models and types of boilers. Could you be more specific, OP? For example, boilers can be divided into vertical and horizontal types, as well as those that generate steam or hot water; these represent different categories. There are also oil-fired boilers, reciprocating boilers, hand-fired boilers, chain boilers, and so on

Boiler model 1: Industrial boiler models in China are designated in accordance with the standards set by the Ministry of Machinery, JB 1626——81. The product model of industrial boilers consists of three parts, which are connected by hyphens. The first section is divided into three paragraphs, representing the boiler model (using Pinyin letters as codes), the combustion method (using Pinyin letters as codes), and the evaporation capacity (expressed in Arabic numerals, with the unit being t/h) ； Hot water furnace provides heat capacity, measured in MW ； The waste heat boiler is expressed in terms of the heating surface area, measured in m2). In quick-install water tube boilers, the letter K (for quick) is used in the first part of the model to replace the code indicating the number of boiler drums. KZ code for quick-install horizontal/vertical drum boilers (Quick, Horizontal) ； The code KQ (fast, strong) is used for quick-installation forced-circulation boilers. The second part indicates the working fluid parameters. For industrial steam boilers, it is divided into two sections: rated steam pressure and rated steam temperature, separated by a slash. The common units are MPa and °C respectively. When the steam temperature is at the saturation temperature, there is no slash in the second part of the model, and the second section is not present. For hot water boilers, the second section consists of three segments: rated pressure, outlet temperature, and inlet temperature, with slashes used to separate the segments from each other. Part three indicates the fuel type and design sequence, consisting of two paragraphs: the first paragraph specifies the fuel type (using Pinyin letters as codes), while the second paragraph indicates the design sequence (using Arabic numerals); the prototype design does not have a second paragraph. 　　 2. Power plant boiler model: The power plant boiler model is also composed of three parts. The first part indicates the boiler manufacturer’s code ； The second part indicates the boiler parameters ； The third part indicates the design fuel code and design sequence. One of the structures of boilers: The structure of industrial boilers. Industrial boilers can be classified into fire-tube boilers and water-tube boilers based on their basic structural design. A fire-tube boiler has the form of a metal cylinder, offering advantages such as a compact structure, good integrity, the ability to use water of lower quality, and easy operation. However, due to its shell-and-tube structure, it has poor stress conditions; the pressure it can withstand as well as its size are greatly limited, which means that only boilers with low parameters and small capacity can be manufactured using this design ； Furthermore, due to the vertical flow of flue gas against the wall surfaces, the heat transfer efficiency is poor, resulting in a low thermal efficiency as well as a high rate of metal consumption ； Furthermore, due to its small furnace size, the operation and maintenance of the built-in combustion device are inconvenient, making it difficult to burn low-quality materials. The main body of a water-tube boiler consists of a drum with a smaller diameter and tubes; it has favorable stress conditions, convenient arrangement of the heating surfaces and furnace, good heat transfer performance, high thermal efficiency, and low steel consumption. Structurally, it is suitable for boilers with large capacity and high parameters, but it requires high standards regarding water quality and operation conditions. In addition to the above two basic types of boilers, there is also a mixed-type boiler composed of water tubes and fire tubes, namely the water-fire tube boiler. This type of boiler combines the advantages of both water-tube and fire-tube boilers; especially when the water tubes form an external furnace chamber: it features a simple structure, easy operation, a larger capacity compared to fire-tube boilers, and good overall integrity. However, it is also not possible to completely avoid the disadvantages of both; for example, the requirements regarding water quality are relatively high, similar to those of water-tube boilers. Due to their small capacity and good overall structure, fire-tube boilers are always manufactured as quick-install (ready-to-use) boilers, and they are currently widely used with fuel oil and gas. Water-tube boilers are preferably designed as boilers with larger capacities, but there are also compact (pre-assembled) boilers of smaller capacity available. Water-tube and fire-tube boilers cover a wide range of capacities, but they are all designed for quick installation (either as complete units or in stacked configurations). They are widely used for burning coal, and currently constitute the majority of industrial boilers in China. 　　Section 1: Structure of Fire-Tube Boilers In fire-tube boilers, flue gas flows within the fire tubes (commonly known as burners) and smoke tubes, transferring heat to the working fluid through radiation and convection, thereby heating it to produce steam. A cylindrical pressure vessel that holds water and steam and also serves as the boiler shell is called a boiler shell. The boiler’s heating surfaces – namely the fire tubes and smoke tubes – are arranged within the boiler shell. The combustion device is located within the fire tube, and the combustion method that uses the fire tube as the furnace is known as internal combustion ； Conversely, those with the combustion device arranged outside the boiler shell are called external combustion. Fire-tube boilers can be divided into horizontal and vertical types based on their arrangement; in the horizontal type, the longitudinal center line of the boiler shell is parallel to the ground, while in the vertical type, this longitudinal center line is perpendicular to the ground. Horizontal fire-tube boilers can be further divided into single-fire-tube (chamber) boilers (also known as Cornish boilers), double-fire-tube (chamber) boilers (also known as Lancashire boilers), smoke-tube boilers (external combustion boilers), and flame-and-smoke-tube boilers (internal combustion boilers). Vertical fire-tube boilers can be divided into vertical horizontal flue-tube boilers and vertical vertical flue-tube boilers. The Cockrell boiler, which was widely used in the past, belongs to the former category. Due to the complex structure of this pure fire-tube vertical boiler, the limitations in the arrangement of its heating surfaces, and its low thermal efficiency, it is no longer manufactured in China. A vertical water-fire tube combined boiler that eliminates the smoke tubes in such boilers and replaces them with water tubes has been widely adopted in China, where it has seen significant development. There are now various types of such vertical fire-tube and water-tube combined boilers, including vertical boilers with large horizontal water tubes, vertical boilers with small horizontal water tubes, vertical boilers with straight water tubes, and vertical boilers with curved water tubes. Among the various types of boilers mentioned above, the vertical water-tube boilers are no longer produced today ； Single-fire-tube boilers and double-fire-tube boilers are widely used with fuel oil and gas. 　　 I. External combustion smoke tube boiler: An external combustion smoke tube boiler is a type of horizontal fire-tube boiler. This type of boiler has numerous smoke tubes arranged in its shell, but no fire tube. The smoke pipe is submerged in the water space of the pot shell. The boiler shell is elevated, with the combustion device located beneath it. A furnace wall is built around the grate to form an external furnace chamber. The flue gas generated after combustion flows from front to back within the furnace chamber, washing against the outer wall of the boiler shell. At the rear end of the furnace chamber, it turns upward into the flue tubes, where it flows from back to front inside those tubes until it reaches the front smoke box, from where it is discharged through the chimney above the smoke box. The flue gas flows once from front to back and then once from back to front inside the boiler, which is called two passes. But some external combustion smoke tube boilers also have a three-pass design. Smoke pipes are usually made of seamless steel tubes. The advantage of this type of boiler is that it uses an external combustion method, which makes it easy to adjust the area of the grate and the volume of the furnace; as a result, it can utilize a wide range of fuels, and the burning process is also simpler. Its disadvantages are: the boiler has poor integrity, the furnace walls need to be constructed on-site, and rapid installation is not possible ； No radiation heating surfaces are installed on the inner surface of the furnace wall; this not only prevents the furnace wall from being cooled, forcing the use of heavier furnace walls, but also reduces the heat transfer efficiency of the entire boiler due to the lack of efficient radiation heating surfaces. These drawbacks result in a large floor space required for the boiler, high installation costs, and difficulties in installation and relocation. Now, these boilers are rarely produced and have been replaced by fire-tube boilers. 　　II. Horizontal internal-combustion smoke hot pot boiler: This type of boiler is the most commonly manufactured today; it can be used to burn coal, but it is more suitable for burning fuel oil and gas. An elastic, wave-shaped fire tube is arranged eccentrically within the boiler shell of the horizontal fire-tube boiler; smoke tubes are installed on both the left and right sides of the boiler shell as well as at the upper part of the fire tube. Both the barrel and the smoke pipe are submerged in the water space of the pot shell. The combustion device and chain grate are placed inside the fire tube. The first passage of the flue gas flows forward and backward through the fire tube; the second passage takes place as the gas flows from back to front through the smoke pipes on both sides toward the front smoke box; the third passage sees the gas flow from the front smoke box, through the upper smoke pipes, from front to back into the rear part of the boiler, from where it is then expelled by the exhaust fan. This type of internal combustion boiler does not require an external furnace chamber; it features excellent integrity and sealing properties. It is designed for quick installation, resulting in low installation costs and minimal space requirement. However, the applicable range of coal types is limited. In addition, this type of boiler has some drawbacks related to the flue tubes themselves: flue tubes are generally joined by expansion fitting, and if this joining process is not carried out properly, leaks can easily occur ； The spacing between the smoke pipes is small, making it difficult to clean the scale; therefore, higher requirements are placed on the quality of water ； When the flue tubes are arranged horizontally, dust tends to accumulate on them, and the flue gas flows vertically within the tubes, resulting in low heat transfer efficiency. The extensive use of such flue tubes not only increases the amount of metal required for the boiler but also raises its ventilation resistance, especially when the flow velocity of the flue gas inside the tubes is high. Horizontal internal-combustion flame tube boilers using fuel or gas take full advantage of the advantages of these fuels, do not require exhaust fans, and thus save on investment and electricity consumption. It maximizes the advantages of internal combustion furnaces while avoiding their disadvantages. It achieves compactness in structure and layout, efficient cleaning during quick installation and operation, as well as safety, feasibility, and automation. Therefore, with the increasing exchanges between domestic and international markets, this type of boiler has become quite popular in China in recent years. 　　 III. Vertical small water-tube fire-tube boilers: These boilers are also referred to as vertical horizontal-water-tube boilers. The boiler body consists of main pressure-bearing components such as the boiler shell, furnace chamber, horizontal water tubes, and draft tube. The horizontal pipes are also arranged at an angle to facilitate water circulation. These types of vertical fire-tube boilers are internal combustion type. Due to the small volume of the furnace chamber, high degree of water cooling, difficulty in achieving complete combustion of the fuel, small heating surface area, and high flue gas temperature, these types of boilers have low thermal efficiency as well as poor smoke and dust removal capabilities. The boiler has a small capacity and low parameters. 　　 IV. Vertical straight-tube fire-tube boilers, abbreviated as vertical straight-tube boilers. This is a vertical water-tube boiler that was developed in earlier periods. The boiler shell is divided into upper and lower **parts**, with the upper and lower ends of each vertical pipe being connected to these two parts of the boiler shell, respectively. The advantage of this type of boiler over the previous vertical boiler is that the water circulation is improved ； The upper and lower tube sheets are not exposed to the high-temperature radiation from the furnace, so the tube sheets do not overheat due to scale formation, and the scale in the tubes is also easier to remove ； A larger number of heating surfaces can be arranged, resulting in a compact structure that facilitates installation and maintenance. However, it still has the following drawbacks: the thermal efficiency of the boiler remains low, and the steel consumption is high. Moreover, the ash accumulation in the tubes is difficult to remove. 　　V. Vertical bent-tube boiler: It is a type of vertical fire-tube boiler that has been developed in recent times as an improvement on traditional boilers. Water-cooling tubes are arranged inside the furnace chamber, with their ends connected to the side walls of the furnace chamber and the spherical top wall of it, respectively. These water tubes, together with the inner wall of the furnace chamber, form the boiler’s radiant heating surface. A ring of staggered ear-shaped tubes is installed on the outer wall of the boiler shell, and an insulated annular smoke box covers the outside of this tube array, forming the convective evaporation heating surface of the boiler. The grate is placed at the bottom of the furnace chamber. The high-temperature flue gas generated by the combustion of fuel on the grate flows through the bent tubes in the furnace chamber, exits through the throat at the upper part of the furnace chamber, and then divides into two streams that enter the ear-shaped convective tube bundle area. Along the outer wall of the boiler shell, these streams flow half a circle each, scrubbing against the ear tubes in the external flue box as well as the corresponding outer wall of the boiler shell. Finally, the flue gas is discharged into the atmosphere through the chimney. This type of boiler features water tubes installed both inside the furnace chamber and in the boiler shell, which increases the area of radiant and convective heating surfaces. As a result, the flue gas temperature is low, giving the boiler high efficiency. Its design also takes into account ease of ash removal, but it requires high-quality feed water. This type of boiler is a vertical boiler that is widely used in our country at present. 　　 Section 2: Structure of Water-Tube and Fire-Tube Boilers. Water-tube and fire-tube boilers generally refer to a type of horizontal external combustion smoke tube boiler that is formed by adding a water wall to the lower part of the boiler shell of a conventional horizontal external combustion smoke tube boiler. This type of boiler is compact and comes pre-assembled; it was formerly known as a \"quick-install boiler\" and was designated by the KZ model code. Now, to be consistent with the naming of water-tube boilers, some have begun to be changed to the DZ model. In China, quick-install boilers were originally developed to replace older types of boilers such as Lancashire and Cowper boilers; today they have become the most common type in China’s industrial boiler production. Combustion equipment generally uses chain grates, but reciprocating grates are also used; in some cases, vibrating grates are employed. Fixed grates are also used in small-capacity boilers. The flue gas flow path is as follows: After flowing out from the furnace chamber, the flue gas first moves upward into the first set of flue tubes, flows from back to front toward the front flue tubes, then turns into the second set of flue tubes from the front flue box, flows from front to back toward the economizer, and is finally exhausted by the exhaust fan. The advantages of this type of boiler are its compact structure, small footprint and height, easy installation and transportation, as well as high thermal efficiency. Its main drawback is that the lower part of the boiler shell is directly exposed to the high-temperature radiation from the furnace, which requires high standards for water quality. 　　Section 3: Structure of Water-Tube Boilers. The notable feature of water-tube boilers is that steam and water flow inside the tubes, while flue gas flows outside them. Compared to fire-tube boilers, it lacks a large-diameter boiler shell in its structure, and uses flexible bent water tubes in place of the more rigid straight smoke tubes; this not only saves metal but also creates the conditions for increasing capacity and improving steam parameters. By using an external combustion method, there are no constraints imposed by the boiler shell, allowing for an increased scale of combustion and a wider range of applicable fuels. From the perspective of thermodynamics, efficient heat transfer methods can be employed: appropriately increasing the radiation heating surface ； Organize the flue gas to cause lateral erosion of the heated surfaces of the pipes; if necessary, the pipes can also be arranged in a staggered pattern. At the same time, the heating surfaces of the water tubes are easy to arrange, and cleaning them of scale and ash is straightforward. It is possible to locate the steam superheater within the most suitable smoke temperature range, as well as placing economizers and air preheaters at the rear section. Of course, such boilers have high requirements regarding water quality, but this is not a problem for large-capacity, high-parameter boilers and modern water treatment technologies. In short, for large-capacity, high-parameter boilers, water-tube boilers offer significant advantages and are often the only viable option ； For small-capacity low-pressure boilers, water-tube boilers and even fire-tube boilers retain a significant advantage. Water-tube boilers can be classified into horizontal water-tube boilers and vertical water-tube boilers based on the arrangement of their tubes ； Based on the shape of the tubes, they can be further divided into straight-tube water tube boilers and curved-tube water tube boilers. In horizontal tube boilers, having the water tubes arranged horizontally or at a slight angle is detrimental to water circulation ； In straight-tube boilers, the water tubes are straight, highly rigid and lack elasticity, which is unfavorable for reducing thermal stress and manufacturing stress. However, when straight tubes are used in horizontal tube boilers, these tubes are connected to each other using integral headers or corrugated manifolds. Manholes are provided at corresponding positions on the walls opposite to the ends of the connected tubes on the headers, allowing for the cleaning of scale inside the tubes. However, due to the large size of the entire box and its shape, which is not conducive to withstanding pressure, its pressure resistance is poor ； Waveform diversity boxes and manholes are difficult to manufacture, require extensive maintenance, and consume a lot of metal; therefore, they have now been replaced by vertical curved water pipes with a small number of drums. Vertical drum water tube boilers can be classified as single-drum and double-drum based on the number of drums ； Based on the orientation of the boiler drum, they can be divided into vertical and horizontal types. 　　I. Vertical boiler with a single drum The most commonly used type of vertical boiler with a single drum is the “A”-shaped boiler. The drum is located in the upper central part of the furnace, aligned along the longitudinal center line of the boiler (grate). There are large-diameter vertical collectors on each of the left and right sides below it. The two sets of convective tube bundles are connected to the drum at the upper part, while they are connected to the respective left and right collectors at the lower part. This type of boiler body is most suitable for a two-pass flow of flue gas, and is therefore commonly used in combustion with a stoker and an inverted chain grate; however, other combustion systems can also be employed. The flue gas flows from back to front within the furnace; as it approaches the front wall, it divides into two streams that pass through the narrow flue openings on either side and enter the convective tube bank, after which it flows from front to back, washing over the tubes horizontally. The steam superheater is located in the flue of the convective tube bank in the right front half, forming part of the second pass convective heating surface. After the flue gas reaches the rear part of the boiler, it splits into two streams – one on the left and one on the right – which rise upward and converge at the top of the boiler. From there, they turn downward and flow through the cast-iron economizer and air preheater successively; after passing through the dust collector, they are drawn out by the exhaust fan and discharged into the chimney. The outstanding advantages of Type A boilers are: compact structure, symmetry, ease of quick assembly, and low metal consumption. Its disadvantage is that the arrangement of the boiler tube bank is restricted by the structure, and its manufacturing and maintenance are also rather troublesome. 　　 II. Horizontal boiler with a single drum. The structural feature of this type of single-drum boiler is that its boiler tube bank is not connected directly by an upper drum and a lower large-diameter header; instead, a modular design is used. First, several rows of tubes are installed between the upper and lower header tanks of smaller diameter to form a single assembly; then, the upper header tanks of these assemblies are connected vertically to the boiler drum along its length. The lower header tanks of each assembly are connected vertically to a collecting header tank that is located below the boiler drum and parallel to it, via connecting pipes. The collecting header tank is in turn connected to the boiler drum through several downcomers. The boiler features a chain grate and a combined long rear arch, and is fueled with low-quality bituminous coal. This type of boiler requires less metal, but occupies more space; moreover, it has high water circulation resistance in the boiler tube bank, making cleaning difficult, and thus it has high requirements for water quality. 　　 III. Double-drum vertical boilers: In these boilers, a boiler tube bank is installed between two drums arranged parallel to each other, one above the other. The longitudinal centerlines of the two drum shells are parallel to the longitudinal centerline of the boiler. Depending on the arrangement of the boiler tube bank relative to the furnace, the double-drum vertical boiler can be further divided into those with the boiler tube bank placed on the side, namely the so-called “D”-shaped boilers ； With the boiler tubes arranged at the back, that is, an “O”-shaped boiler. The combustion equipment in boilers commonly uses coal throwers, manual grates, chain grates, or vibrating grates; in recent years, fluidized bed boilers have been widely used as well. The structural feature of this boiler is that the flue gas flushes the tube bank laterally, resulting in good heat transfer; it is compact and symmetrical, making it suitable for modular or stacked installation. 　　IV. Double-drum horizontal boilers: Double-drum horizontal boilers are the most widely used in large industrial boilers. The upper and lower drum sections along with the tube bank between them are horizontally suspended behind the furnace chamber. The flue gas generated by combustion flows out through the smoke outlet at the upper rear part of the furnace, and after passing through the slag duct, enters the superheater flues in the tube bank. Then downward, from the lower part of the tube bundle, the tube bundle is flushed and circled upward in three forward-and-back bends. It then flows backward from the upper outlet window to the tail flue, passing through the economizer and air preheater in sequence before being discharged from the boiler. This type of boiler already possesses the characteristics of medium and large-sized boilers: a high degree of mechanization in its combustion equipment, an efficient and comprehensive heating surface area, and high boiler efficiency ； However, the boiler has poor integrity, with a complex framework and furnace walls. The metal consumption is high.

They can be divided into four categories based on their use: power station boilers, industrial boilers, ship boilers, and locomotive boilers. It is recommended that the original poster obtain a manual on power station boilers, as it provides a comprehensive classification

You can refer to http://bbs.hcbbs.com/thread-580047-1-1.html

Boilers can be classified according to the circulation method, combustion method, slag discharge method, operation mode, as well as fuel, steam parameters, furnace type, and ventilation method. Among these, classification based on the circulation method and steam parameters is the most common. Based on the circulation method, they can be classified into: natural circulation boilers, forced circulation boilers, and once-through boilers. Based on steam parameters, boilers can be classified as follows: low-pressure boilers (exit steam pressure, the same below, ≤2.45 MPa), medium-pressure boilers (2.94–4.90 MPa), high-pressure boilers (7.8–10.8 MPa), ultra-high-pressure boilers (11.8–14.7 MPa), subcritical-pressure boilers (15.7–19.6 MPa), supercritical-pressure boilers (>22.1 MPa), and ultra-supercritical-pressure boilers (>27 MPa). 　　

Boilers are classified by function into water-boiling boilers, hot water boilers, steam boilers, heat transfer oil boilers, hot air boilers, etc； Classified by fuel, they include electric heating boilers, oil-fired boilers, gas boilers, coal-fired boilers, biogas boilers, solar boilers, etc ； Among them, water boilers are classified into KS-D electric water boilers, KS-Y fuel oil water boilers, KS-Q gas water boilers, KS-AII coal-fired water boilers, etc ； Hot water boilers are classified into CLDZ (CWDZ) electric hot water boilers, CLHS (CWNS) fuel oil hot water boilers, gas hot water boilers, CLSG (CDZH) coal-fired hot water boilers, and others ； Steam boilers are classified into LDR (WDR) electric steam boilers, LHS (WNS) fuel oil steam boilers, gas steam boilers, as well as coal-fired steam boilers such as LSG, DZG, DZH, and DZL.