JP2019203679A - Once-through tubular boiler - Google Patents

Abstract

To solve the problem of having to pursue economical efficiency while securing safety in site assembly of a radiation heat transfer surface breakdown voltage part, prolongation of a construction term, proper dispatch of a welding technician, and securing of welding quality in a conventional boiler whose radiation heat transfer surface dimensions exceed transport limit dimensions.SOLUTION: In a boiler, a gas passage of the boiler is formed by combining and connecting a plurality of once-through tubular boilers which have the number of folds of a plate-like heat transfer surface of a once-through boiler is zero to two, the once-through boilers each comprising a lower pipe header of a boiler, an upward flow heat transfer pipe, an upper pipe header, a steam separator and a communication pipe.SELECTED DRAWING: Figure 5

Description

  The present invention relates to the configuration and combination of radiant heat transfer surfaces of a once-through boiler installed in a waste incinerator.

The boiler's radiant heat transfer surface requires a certain volume depending on the amount of gas. In particular, the boiler in which the combustion exhaust gas temperature is about 1000 ° C, in which this boiler is represented by a waste incinerator, has an increased combustion air excess rate compared to the case where the combustion exhaust gas temperature of the fossil fuel combustion boiler is about 2000 ° C. The exhaust gas flow rate tends to increase.
When manufacturing and constructing a boiler in such a situation, it is often difficult to complete the boiler production at the factory and transport the boiler within the transport limit of the road. The boiler will be a locally assembled boiler. Local assembly boilers require welding assembly of pressure-resistant parts on site. In this case, boiler construction has many considerations such as securing skilled welding technicians, ensuring welding quality, and ensuring the construction period, and there was a technical background that measures to reduce these were desired.

  Boilers whose radiant heat transfer surface dimensions exceed the transport limit are economical, while ensuring safety in on-site assembly of the radiant heat transfer surface pressure-resistant part, lengthening the construction period, dispatching welding technicians as appropriate, and ensuring welding quality. He had the problem of having to pursue sex.

  The present invention relates to a once-through plate having a number of bent heat transfer surfaces of zero or two, which is a plate of a once-through boiler comprising a lower header of a boiler, an upflow heat transfer tube, an upper header, a steam separator and a connecting tube. The above-described problems are solved by combining and connecting a plurality of boilers to form a boiler gas passage.

  When the pressure-resistant part welding of a boiler is performed in the field work, selection of the weather and the welding posture is often limited, and it may be difficult to ensure the reliability of the welding. However, according to the present invention, since the boiler pressure-resistant part is welded in the factory, the working environment is good, and the welding posture can be welded in a downward posture by inverting the article. Effective in improving safety.

  The boiler according to the present invention can be assembled and assembled into a large boiler by combining individual boilers whose pressure-resistant parts have been completed at the factory. Therefore, damage to a part of the pressure-resistant parts does not lead to accidents such as saturated water leakage of the entire boiler. As a result, it is possible to prevent accidents to a minimum, and it is effective in improving safety as a countermeasure for risk dispersion.

  Conventional boilers installed in waste combustion furnaces with large radiant heat transfer surface dimensions are often natural circulation boilers having a steam separator drum, but this boiler increases the amount of water held by the steam separator drum, Since the saturated water circulation flow rate from the steam-water separation drum will be several to several tens of times the amount of steam evaporation, the ratio of the amount of saturated water to the amount of steam in the boiler heat transfer pipe will increase, and the amount of retained water will also increase. . The boiler according to the present invention is effective in providing a boiler that is safer against breakage of the pressure-resistant portion because the amount of water held by the entire boiler is reduced by limiting the boiler type to the once-through type.

  The ratio of the amount of recirculation of saturated water to the amount of evaporation of the natural circulation boiler is several to several tens of times. On the other hand, the ratio of the recirculation amount of saturated water to the steam amount of the once-through boiler is about 1: 1. For this reason, the steam-water separator of the once-through boiler has a smaller size than the steam-water separation drum of the natural circulation boiler, and the steam-water separator of the once-through boiler becomes smaller. The steam-water separator of the boiler in the present invention can achieve economic efficiency while ensuring separation performance.

  Since the boiler according to the present invention is divided into a plurality of boilers within the transport limit, it has an economic effect that leads to a reduction in transport costs.

  The boiler according to the present invention does not have to depend on a skilled and highly skilled welder such as pressure-resistant part welding because the assembly in the field is a combination of non-pressure-resistant parts. There is an effect that quality control becomes easy.

  The individual boilers in the factory that constitute the present invention have the same shape, those with no plate folding number, those with one plate folding number, those with two plate folding numbers, and standardized these. However, by producing in a factory, it becomes possible to cope with various boiler shapes depending on how these are assembled and assembled, and a boiler having an economic effect can be obtained.

Water circulation system diagram of conventional natural circulation boiler Radiation heat transfer part outline drawing of conventional natural circulation boiler Field connection diagram of a conventional natural circulation boiler Water circulation system diagram of once-through plate boiler of the present invention Radiation heat transfer part outline drawing of once-through type plate boiler of the present invention Field connection diagram of once-through plate boiler of the present invention

  A mode for carrying out the present invention will be described with reference to the drawings.

The conventional natural circulation boiler is as follows.
FIG. 1 shows a system diagram of a conventional natural circulation boiler. FIG. 2 shows an external view of a radiant heat transfer section of a conventional natural circulation boiler. FIG. 3 shows an on-site joint of a conventional natural circulation boiler.

  In FIG. 1, a boiler feed water communication pipe 101 enters a steam-water separation drum 107, flows into a lower header 103 of the boiler through a precipitation pipe 102, receives heat from exhaust gas in a rising heat transfer pipe 104, and has a light specific gravity mixed fluid. And flows into the upper header 105, and the air-water mixture is introduced into the air-water separation drum 107 through the connecting pipe 106. In the steam / water separation drum 107, steam and saturated water are separated, the steam is sent to the outside of the boiler through the connecting pipe 108, and the saturated water is mixed in the feed water and the steam / water separating drum which is introduced through the connecting pipe 101. Then, it is recirculated through the downcomer 102 again. The recirculation flow rate of the boiler is called a natural circulation boiler because it is naturally determined by the specific gravity difference between the internal fluids of the rising heat transfer tube 104 and the downcomer tube 102.

  FIG. 2 is a bird's-eye view of the system shown in FIG. In FIG. 2, an inlet exhaust gas 121 that gives heat to the rising heat transfer tube 104 is introduced from below, and becomes an outlet exhaust gas 122 that leaves the rising heat transfer tube 104. There are many ascending heat transfer tubes similar to the ascending heat transfer tube 104, and the ascending heat transfer tubes are welded together via a number of fin plates typically represented by the fin plate 111. This fin plate forms a plate-like gas-tight radiant heat transfer surface, and the exhaust gas passes through a rectangular gas passage and goes upward from below. Here, when the longitudinal dimension 134 and the vertical height dimension 131 of the boiler are within the land transport limit dimension and the width dimension 132 is equal to or greater than the land transport limit dimension, the boiler is manufactured in the factory and transported on-site as a whole. Becomes difficult. In this case, the boiler has to take a method of dividing the heat transfer area by the transport limit size 133 and joining the divided parts by welding on site. This division must be performed in the same manner on the heat transfer surface facing the dimension 133 within the transport limit. As a result, a conventional natural circulation boiler, which has a large radiant heat transfer area, has a construction condition in which on-site pressure welded joints cannot be avoided.

  FIG. 3 is a split coupling portion in which the portion A in FIG. 2 is enlarged. In FIG. 3, the ascending heat transfer tube 104 is coupled to the upper header 105, and the fin plates 111 and 112 are coupled to the ascending heat transfer tube 104. Similarly, the riser heat transfer tube 110 is coupled to the upper header 109, and the fin plates 113 and 114 are coupled to the riser heat transfer tube 110. Here, for the convenience of transportation, the header and the fin plate are divided at the welding line 161 and welded and joined at the site. In FIG. 2, there are a total of eight welds corresponding to the portion A in the lower header 103 and the upper header 105 and the upper and lower headers facing each other. In this on-site joining, the header 105 and the header 109 are joined by pressure-resistant welds, and quality control, construction by skilled qualification technicians, and when the thickness of the header is thick, advanced construction management such as partial annealing after welding is performed. I need it. In addition, it is necessary to secure a construction period for that purpose.

  FIG. 4 shows a boiler system diagram according to the present invention. Here, the water supply is supplied to the lower headers 203 and 303 through the connecting pipes 401, 201, 402, and 301. The rising heat transfer pipes 204 and 304 receive heat from the exhaust gas and become an air-water mixed fluid having a low specific gravity. The air / water mixture flows into the upper headers 205 and 305 and is introduced into the steam / water separators 207 and 307 through the connecting pipes 206 and 306. In the steam separators 207 and 307, the steam and saturated water are separated, the steam is sent to the outside of the boiler through the connecting pipes 208, 308, 405, and 408, and the saturated water is introduced through the downcomer pipes 202 and 302. It is mixed with the feed water and recirculated through the connecting pipes 201 and 301 again. This boiler is classified as a once-through boiler because the amount recirculated from the steam separator through the downcomer pipes 202 and 302 is approximately the same as the feed water flow rate or the boiler evaporation flow rate. In the present invention, the type of boiler is limited to the once-through type, because the amount of saturated water held in the ascending heat transfer tubes 204 and 304 and the steam separators 207 and 307 is limited because the once-through boiler has a small amount of recirculated water of saturated water. This is because it contributes to the safety that is the object of the present invention.

  In the system diagram of the present invention in FIG. 4, it is divided into two parts, the reference number 200 series and the reference number 300 series. However, the present invention is not necessarily limited to a plurality. Satisfied. This means that if the rising heat transfer tube 204 is broken and the rising heat transfer tube 304 is healthy, the damage to the rising heat transfer tube 204 is minimized without spreading to the entire boiler system. It will contribute to a certain safety.

  FIG. 5 of the present invention is a bird's-eye view of the system shown in FIG. In FIG. 5, the inlet exhaust gas 221 to the boiler is introduced from below and becomes the outlet exhaust gas 222, which leaves the boiler. In FIG. 5, the exhaust gas is escaping from below to above, but it is not necessarily limited that the exhaust gas flow from below to above. In some cases, the flow of the exhaust gas may flow from above to below. The heat transfer surface that receives the heat of the exhaust gas has many heat transfer tubes similar to the rising heat transfer tube 204, and the heat transfer tubes are connected by welding via a number of fin plates typically represented by the fin plates 211. These heat transfer tubes and a large number of fin plates form a plate-like gas-tight radiant heat transfer surface, and the exhaust gas passes through a rectangular gas passage and flows upward from below. Here, when the boiler radiant heat transfer surface dimension exceeds the transport limit, the longitudinal dimension 136 and the vertical height dimension 131 are within the land transport limit width, and the lateral width dimension 135 is equal to or greater than the land transport limit width. In this case, the boiler is divided into two boilers having a reference number 200 and a reference number 300 by the non-pressure-resistant part welding lines 262 and 263. In this way, the longitudinal dimension 136, the longitudinal height dimension 131, and the lateral width dimensions 137, 138 can be set within the land transport limit dimensions. In this boiler, the pressure-resistant parts are all combined in the factory, and transportation is also performed by land transport. Because it falls within the critical dimensions, it achieves two objectives: increased safety and increased economy.

  FIG. 6 is a split coupling portion in which the portion B in FIG. 5 is enlarged. In FIG. 6, a rising heat transfer tube 204 is coupled to the upper header 205, and fin plates 211 and 212 are coupled to the rising heat transfer tube 204. Similarly, the riser heat transfer tube 304 is coupled to the upper header 305, and the fin plates 312 and 311 are coupled to the riser heat transfer tube 304. Here, for convenience of transportation, the fin plate is divided by the non-pressure-bonding weld line 262 and welded on site. The upper header 205 and the upper header 305 are originally divided and independent in the factory, and the internal fluid does not circulate, and these headers are not directly joined by welding. The boilers in the 200 series and the 300 series are joined on site by welding of the non-pressure-resistant welding joint line 262, which is a connection between the non-pressure-resistant portion of the fin plate 212 and the fin plate 312. This welding of the portion B in FIG. 5 means that there are no 8 on-site pressure part weldings corresponding to the part A in FIG. 2 in the case of the prior art, resulting in non-pressure part welding between the fin plates. . Since this connection is easy to weld, it leads to quality reduction prevention by on-site construction, resulting in improved safety and economic effects.

  Looking at the boiler in the series 200 in FIG. 5 of the present invention, a large number of upward flow heat transfer tubes similar to the upward heat transfer tubes 204 are joined to a large number of fin plates similar to the fin plates 271. Are connected to the lower and upper headers. These parts form a plate-like radiation heat transfer surface. This radiant heat transfer surface is composed of an ascending heat transfer tube. In the boiler of the number 200 series in FIG. 5, the plate-shaped heat transfer surface is bent by two vertical fold lines 251 and 252. Bending does not necessarily mean that only one fin plate is bent, but the bent portion may be joined by welding or may be bent in an arc shape. To do. Although two fold lines are shown in FIG. 5 for the boilers in the order of number 200, depending on the configuration of the radiant heat transfer surface, there may be no fold lines, and one or two fold lines may be used. In FIG. 5, a gas passage is formed by combining a No. 200 boiler and a No. 300 series boiler, and a radiation heat transfer surface for receiving the inlet exhaust gas 221 and discharging the outlet exhaust gas 222 is formed. When the boilers of the number 200 series and the number 300 series are made in the same shape, they can be easily transported, easily constructed, and standardized, and meet the object of the present invention to provide a safe and economical boiler. In FIG. 5, the broken line of the radiation heat transfer surface is a vertical axis, but the object of the present invention can be achieved even if the broken line is a horizontal axis depending on the configuration of the heat transfer surface.

101. Connecting pipe 102. Downcomer 103. Lower header 104. Ascending heat transfer tube 105. Upper header 106. Connecting pipe 107. Air-water separation drum 108. Connecting pipe 109. Upper header 110. Ascending heat transfer tube 111. Fin plate 112. Fin plate 113. Fin plate 114. Fin plate 121. Inlet exhaust gas 122. Outlet exhaust gas 131. Vertical height dimension 132. Width dimensions 133. Dimensions within the transport limit 134. Longitudinal dimension 135. Width dimension 136. Longitudinal dimension 137. Width dimension 138. Width dimensions 161. Joining weld line 201. Connecting pipe 202. Downcomer 203. Lower header 204. Ascending heat transfer tube 205. Upper header 206. Connecting pipe 207. Steam separator 208. Connecting pipe 211. Fin plate 212. Fin plate 251. Bending line 252. Bending line 262. Non-pressure-resistant part welding line 263. Non-pressure-resistant part welding line 271. Fin plate 301. Connecting pipe 302. Downcomer 303. Lower header 304. Ascending heat transfer tube 305. Upper header 306. Connecting pipe 307. Steam separator 308. Connecting pipe 311. Fin plate 312. Fin plate 401. Connecting pipe 402. Connecting pipe 405. Connecting pipe 406. Connecting pipe

Claims (1)

  A plurality of once-through plate-like boilers having a bend number of the heat transfer surface, which is a plate-like shape of a once-through boiler consisting of a lower header, an upflow heat transfer tube, an upper header, a steam separator and a connecting tube of the boiler, up to zero or two A boiler that forms a gas passage for a boiler by combining and connecting them.

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