RU227902U1 - BOILER WITH HEAT INSULATION DEVICE - Google Patents

Abstract

The utility model relates to the field of power engineering. A boiler with smoke tubes comprises a boiler drum (11) including a combustion chamber (1), smoke tubes (5), a heat transfer surface in an exhaust gas container (3), a heat-insulating device (4) and an exhaust gas container; a roof (8) of the boiler drum; an outlet opening for exhaust flue gas (7); and a smoke stack (9). The heat-insulating device (4) includes a heat-insulating reflective plate and is installed inside the exhaust gas container opposite the heat transfer surface of the exhaust gas container (3). The utility model makes it possible to reduce heat loss from the exhaust gas, lower its temperature by improving heat transfer properties, and prevent the formation of a dew point. 5 clauses, 7 figs.

Description

The utility model relates to a boiler that includes a heat-insulating device.

State of the art and purpose of the utility model

Generally, the heat loss due to exhaust gas is 5-12%, which accounts for a relatively large proportion of the total heat loss. Therefore, reducing the heat loss due to exhaust gas is of great importance in improving the thermal efficiency of heat.

To reduce heat loss during boiler operation, the temperature of the exhaust gas released into the air through the exhaust gas container and pipe should be reduced.

However, with the method of expanding the heat transfer surface, in the event of an excessive decrease in the temperature of the exhaust gas, the moisture in this gas thickens and, in interaction with nitrogen oxide and sulfur, forms an acid, corroding the heat transfer surface and other metal parts.

Hence, the existing technology has determined the temperature of power boilers to be within 120-160 degrees, and industrial or domestic boilers of medium and small size with variable load - 180-250 degrees. At present, various technical solutions are known for preventing or reducing corrosion of the heat transfer surface under the influence of condensation of water vapor contained in the exhaust gas. The document GB2017288A, taken as the closest analogue, discloses a liquid fuel heat exchanger for heating a fluid such as water or gas, comprising a plurality of heat exchangers, pipes (flue pipes), each of which has a double-wall structure. In this technical solution, the double-wall structure is formed, at least above a part of the heat exchange pipes, forming an annular space separating the heating medium, namely, combustion gases, from the heated medium. The presence of the annular insulating space prevents the flue gas temperature from falling below the dew point and thereby reduces condensation and corrosion.

The prior art only discloses how to reduce the corrosion of chimneys caused by the condensation of water vapor contained in the exhaust gas, but does not disclose how to effectively improve the heat transfer efficiency of the boiler at the same time. The disadvantage of the prior art is that the manufacture of double-wall chimneys is difficult and requires a large amount of material.

The purpose of this utility model, as noted above, is to provide boilers with a heat-insulating device that allows the temperature of the exhaust gas in the exhaust gas container to be reduced below the limit value of the existing technology and to prevent the formation of a dew point in order to increase the thermal efficiency of heat.

Description of the utility model

To increase the thermal efficiency of heat, a greater proportion of the heat of the burning fuel should be transferred to the heat exchange medium through the heat transfer surface. One of the measures is to reduce heat loss from the exhaust gas by reducing its temperature by improving heat transfer properties. In the new version, to increase the thermal efficiency of heat, more specifically, to improve heat transfer properties, boilers with a heat-insulating device are provided, allowing the exhaust gas temperature to be reduced below the limit value of existing equipment and preventing the formation of a dew point.

The boiler of this utility model as a boiler with smoke tubes or water tubes for producing steam or hot water mainly includes a boiler drum containing a combustion chamber, a smoke tube, a heat transfer surface in a waste gas container, a heat-insulating device, a waste gas container, and also a boiler drum roof, a waste flue gas outlet and a smoke pipe.

When fuel is burned in the furnace, the resulting combustion gas flows, comes into contact with the inside of the smoke tubes, and transfers most of the heat contained in the combustion gas to the heat exchange medium by thermal radiation, convection and transmission, passes through the exhaust gas container and is discharged to the outside through the exhaust gas outlet and the chimney.

The boiler thermal insulation device is installed inside the exhaust gas container opposite the heat transfer surface, reduces the exhaust gas temperature and prevents the formation of dew point.

Heat transfer surface of exhaust gas container upper tube sheet.

According to the utility model, the heat-insulating device has a cross-sectional area equal to the area remaining from the cross-section of the exhaust gas container after subtracting 20-30% of the cross-section of the combustion chamber. The area of the container figure obtained by vertically projecting the heat-insulating device onto the heat-transfer surface of the exhaust gas container is within 10-24% of the cross-section of the combustion chamber.

According to the utility model, the heat-insulating device may also include a heat-resistant layer on one side of the heat-insulating reflective plate that is not located opposite the heat-transfer surface of the waste gas collection container. It may also include an element that regulates the gap between the heat-insulating device and the heat-transfer surface of the waste gas collection container and secures the heat-insulating device inside the waste gas container.

It can also form a unit with the boiler body cover.

The advantage of the boiler is that, in comparison with analogues of existing equipment, it reduces the temperature of the exhaust gas below the limit of existing equipment due to lower materials and consumption and prevents the formation of the dew point, which is why a long campaign increases the thermal efficiency of heat.

Description of drawings

Fig. 1 shows in a three-dimensional plan the use of a boiler with inclined smoke tubes, in the exhaust gas container of which a heat-insulating device is installed.

Fig. 2 shows an example of the principle of installing a heat-insulating device in a waste gas container of a boiler with inclined smoke tubes.

Fig. 3 shows an example of the principle of installing a heat-insulating device in the exhaust gas container of a boiler with vertical smoke tubes.

Fig. 4 shows an example of the principle of unity of the boiler drum cover and the heat-insulating device in a boiler with inclined smoke tubes.

Fig. 5 shows an example of a specific design of a thermal insulation device.

Fig. 6 shows an example of the principle of unity of the boiler drum cover and the heat-insulating device in a boiler with inclined smoke tubes.

Fig. 7 shows an example of the principle of the lateral area of the container figure obtained by vertically projecting the heat-insulating device onto the heat transfer surface of the exhaust gas container.

1: combustion chamber; 2: heat exchange medium; 3: heat transfer surface in exhaust gas container (upper tube sheet in case of fire tube boiler); 31: heat exchange medium inlet; 32: heat exchange medium outlet; 4: heat insulating device; 40: member fixing heat insulating device in exhaust gas container; 41: heat insulating reflective plate; 42: heat-resistant heat insulating layer; 43: sand; 44: handle of heat insulating device; 5: smoke tube; 6: exhaust gas container; 7: exhaust gas outlet; 71: opening for observing and removing soot and ash deposited on the heat transfer surface in exhaust gas container; 72: opening for removing soot and ash from the tube; 8: boiler drum cover; 9: chimney; 11: boiler drum; 12: area of passage of exhaust gas flowing out between the edge of the heat-insulating device and the heat transfer surface of the exhaust gas container (part of the lateral area of the container figure obtained by vertically projecting the heat-insulating device onto the heat transfer surface of the exhaust gas container);

Example of application of the utility model

To help better understand the technical options for implementing the purpose of the utility model, an example of its application is provided with a drawing and a specific description.

An example, a heat-insulating device, including boilers with inclined smoke tubes, vertical smoke tubes in the figure are isolated examples of the application of the utility model, and its application is not limited.

In the examples, the cross-section of the combustion chamber of the boilers is 0.0346 sq.m.

In one example, propane was used as fuel and water as heat exchange medium. The cross-section of the smoke stack is 9 - 8% of the cross-section of the combustion chamber.

The exhaust gas temperature in the examples means the exhaust gas temperature measured in the container where the exhaust gas outlet 7 ends and the chimney 9 begins.

Application example 1

The fire tube boilers from the application examples of the utility model in Figs. 1-3 mainly consist of a boiler drum 11 surrounding a combustion chamber 1, a heat exchange medium 2 surrounding it, a fire tube 5, an upper tube plate 3, a heat-insulating device 4, an exhaust gas container 6; a boiler drum cover 8, an exhaust gas outlet 7, and a smoke stack 9.

Here, the exhaust gas container 6 is the space before the exhaust flue gas outlet 7 surrounded by the boiler drum cover 8 and the upper tube plate 3, and the heat transfer surface of the exhaust gas container is the upper tube plate 3. Therefore, the accounting number 3 is also written for the heat transfer surface of the exhaust gas container.

The heat-insulating device 4 is installed in the exhaust gas container 6 opposite the heat transfer surface 3.

In the boiler drum 11 there is an inlet opening 31 and an outlet opening 32, the heat exchange medium 2 enters through the inlet opening 31 at the bottom of the drum and exits through the outlet opening 32 at the top of the drum.

In the outlet opening of the outgoing flue gas 7 there is an opening for observing soot and ash settling on the heat transfer surface 3 and for removing them 71, an opening for removing soot and ash from the chimney 9.

In one example of application of the utility model, the cross-section of the heat-insulating device 4 of the boiler with smoke tubes is equal to the cross-section of the heat-insulating reflective plate 41, equal to the cross-section of the exhaust gas container 6 minus 20-30% of the cross-section of the furnace. And also the heat-insulating device 4 is installed so that the area of passage of exhaust gas 12 between the edge of the named device and the heat transfer surface 3 of the exhaust gas container is within 10-24% of the cross-section of the combustion chamber. The area of passage of exhaust gas 12 between the edge of the heat-insulating device 4 and the heat transfer surface of the exhaust gas container 3, as shown in Fig. 7, is the lateral area of the container figure obtained by vertically projecting the heat-insulating device 4 onto the heat transfer surface 3. In this case, the geometric center of the cross-section of the heat-insulating device 4 coincides with the geometric center of the cross-section of the boiler.

In the example in Fig. 5, the heat-insulating device 4 regulates the interval between the heat-insulating reflecting plate 41, the heat-insulating device 4 and the heat-transfer surface in the exhaust gas container 3, and includes an element 40 that secures the heat-insulating device 4 in the exhaust gas container, i.e. on the upper tube plate or on the drum cover of the boiler 8, as well as a heat-resistant heat-insulating layer 42 on one side of the heat-insulating reflecting plate that is not face to face with the heat-transfer surface 3 of the exhaust gas container.

In the heat-insulating devices 4 of the boilers in the examples, the heat-insulating reflective plate 41 reflects onto the heat-transfer surface of the exhaust gas container a portion of the radiant energy of the exhaust gas flowing through the smoke tube 5 in the exhaust gas container, and also enhances the transfer of convective heat during the rapid flow of the exhaust gas through the narrow space between the heat-insulating reflective plate and the heat-transfer surface in the exhaust gas container.

It also extends the combustion gas path, thus extending the residence time of this gas in the boiler and preventing the formation of an ineffective heat exchange zone on the heat transfer surface, which ultimately increases the heat transfer coefficient. In the above examples, stainless steel and carbon steel can be used as materials for the heat-insulating reflective plate 41, in one example, stainless steel 1Cr18Ni9 was used.

Heat-resistant glass fiber, vermiculite, and coal ash can be used as the material of the heat-resistant thermal insulation layer 42; in one example, coal ash was used.

According to the example of application of the utility model, the heat-insulating layer 42 in the heat-insulating device 4 enhances the heat-insulating effect of the heat-insulating reflective plate 41. In this case, already common means are used as fastening elements, which are fixed on the surface of the heat-insulating device in the exhaust gas container or on the roof of the boiler drum.

In order to regulate the distance from the heat-insulating device 4 to the heat transfer surface 3 in the exhaust gas container, 4 fastening elements 40, consisting of bolts and nuts, are secured by welding to the heat transfer surface 3 in the exhaust gas container or to the roof of the boiler drum 8.

Fig. 4 and 6 show an example of the principle of unity of the boiler drum cover and the heat-insulating device in a boiler with inclined smoke tubes.

Under the same combustion conditions, a test was conducted to compare the heat transfer efficiency of boilers with inclined smoke tubes, which depends on the cross-sectional area of the heat-insulating device 4. The heat-insulating device 4 was installed 10 millimeters from the heat transfer surface 3 in the exhaust gas container.

The boilers used were inclined smoke tube boilers with a drum diameter of 210 millimeters, a height of 210 millimeters, and a heat transfer surface area of 0.325 square meters, and boilers with vertical smoke tube boilers with a drum diameter of 210 millimeters, a height of 230 millimeters, and a heat transfer surface area of 0.336 square meters. The steam generated in the miniature boilers was sprayed through an outlet 32 into a container containing 4 liters of water. The initial water temperature was 16 degrees Celsius, and the test duration was 6 minutes from the moment of steam generation, respectively.

After this, the water in the containers was moved and the final temperature of the water was measured.

The temperature of the exhaust gas in boilers with inclined and vertical smoke tubes, where a heat-insulating device was not installed in the exhaust gas container, was 230 and 260 degrees Celsius, respectively.

Table 1 provides data on the comparison of miniature boilers with inclined fire tubes, and Table 2 provides data on the comparison of miniature boilers with vertical fire tubes.

As shown in Tables 1 and 2, if the cross-sectional area of the heat-insulating device, i.e., the heat-insulating reflective plate, is excessively increased, incomplete combustion is observed, and if it is excessively reduced, there will be no great heat exchange effect from installing the heat-insulating device. As the test shows, the fuel is sufficiently burned and the heat transfer efficiency is improved in the case where the cross-section of the heat-insulating device has a size obtained by subtracting 20-30% of the cross-section of the combustion chamber from the cross-sectional size of the exhaust gas container. In order to compare the heat transfer efficiency in boilers with inclined and vertical smoke tubes, which depends on the area of the exhaust gas passage between the edge of the heat-insulating device 4 and the heat transfer surface 3 in the exhaust gas container, a test was carried out under the same combustion conditions. The boilers used were inclined smoke tube boilers with a drum diameter of 210 millimeters, a height of 210 millimeters, and a heat transfer surface area of 0.325 square meters, and boilers with vertical smoke tube boilers with a drum diameter of 210 millimeters, a height of 230 millimeters, and a heat transfer surface area of 0.336 square meters. The steam generated in the miniature boilers was sprayed through an outlet into a container containing 4 liters of water. The initial water temperature was 16 degrees Celsius, and the test duration was 6 minutes from the moment of steam generation, respectively. The diameter of the heat-insulating device, i.e. the diameter of the heat-insulating reflective plate (41), was 180 millimeters. Its cross-sectional area is equal to the difference between the cross-sectional area of the exhaust gas container and the cross-section of the combustion chamber minus 74 percent.

The test data are presented in Tables 3 and 4.

As shown in Tables 3 and 4, if the area of the exhaust gas passage between the edge of the thermal insulation device and the heat transfer surface in the exhaust gas container is excessively reduced, the heat exchange effect of installing the thermal insulation board will not be sufficient. The test proved that the fuel is sufficiently burned and the heat transfer efficiency is improved when the thermal insulation device is installed so that the area of the exhaust gas passage between the edge of the thermal insulation device and the heat transfer surface in the exhaust gas container is within 10-24% of the cross-section of the combustion chamber.

Under identical combustion conditions, the new utility model, i.e. boilers with an optimally installed heat-insulating device, compared to analogues, had improved characteristics of convective heat transfer and radiant heat transfer, as a result of which the transferred heat was increased, the temperature of the exhaust gas was reduced and the thermal efficiency of heat was increased. The technical version of the utility model can be used in heat exchange devices with thermal radiation and heat convection, and in the case of maintaining a certain type and shape of the material used for the heat-resistant heat-insulating layer, only the heat-resistant heat-insulating layer and the fixing element can be included in the heat-insulating device.

This utility model must be protected not only from cases of use, as the example shows.

Any change, amendment, equivalent replacement and update of examples are within the scope of protection of the utility model, as long as they do not go beyond the idea of the technical variant provided for the utility model.

Claims (11)

1. A boiler with fire tubes, containing: a boiler drum (11) comprising a combustion chamber (1), smoke tubes (5), a heat transfer surface in a waste gas container (3), a heat-insulating device (4) and a waste gas container (6); the roof of the boiler drum (8); flue gas outlet (7); and chimney (9); characterized in that the heat-insulating device (4) includes a heat-insulating reflective plate (41) and is installed inside the exhaust gas container (6) opposite the heat transfer surface of the exhaust gas container (3). 2. A boiler according to item 1, characterized in that the cross-section of the heat-insulating device (4) has a size obtained by subtracting 20-30% of the cross-section of the combustion chamber from the size of the cross-section of the exhaust gas container (6). 3. The boiler according to item 2, characterized in that the lateral area (12) of the exhaust gas container figure, obtained by vertically projecting the heat-insulating device (4) onto the heat transfer surface (3) of the exhaust gas container, occupies 10-24% of the cross-section of the combustion chamber. 4. The boiler according to item 3, characterized in that a heat-resistant heat-insulating layer (42) is also included in one of the sides of the heat-insulating reflective plate (41), which is not located opposite the heat transfer surface (3) of the exhaust gas container. 5. A boiler according to item 3 or 4, characterized in that it includes a fastening element (40) that regulates the gap between the heat-insulating device (4) and the heat transfer surface (3) of the exhaust gas container (6) and fixes the heat-insulating device (4) inside the exhaust gas container (6). 6. A boiler according to item 3 or 4, characterized in that the heat-insulating device (4) and the roof of the boiler drum (8) form a monoblock.