98results about "Boiler water tubes" patented technology

A system includes a heat exchanger having a plurality of tubes arranged in a tube bundle having opposite first and second sides, opposite third and fourth sides extending from the first side to the second side, and opposite fifth and sixth sides extending from the first side to the second side, wherein the fifth and sixth sides extend between the third and fourth sides. The heat exchanger further includes a plurality of external flow lanes extending across the tube bundle and between the fifth and sixth sides outside of the plurality of tubes. Each tube of the plurality of tubes comprises a plurality of tubing portions extending in opposite first and second directions between the first and second sides in a sequence, and each successive tubing portion in the sequence switches lanes between the plurality of external flow lanes relative to a preceding tubing portion.

The utility model relates to the technical field of boilers, in particular to a low-nitrogen gas steam boiler which comprises a boiler body, two groups of water pipes are arranged in the boiler body and include an ascending pipe and a descending pipe, the descending pipe is located on the periphery of the ascending pipe, a gas distributor is arranged on one side of the ascending pipe, and a burner is installed on the side, facing the ascending pipe, of the gas distributor. A preheater is arranged on the outer side of the furnace body, one side of the furnace body is connected with a flue, a smoke pipe is vertically installed in the middle of the interior of the preheater, the top end of the smoke pipe is connected with the flue, and the bottom end of the smoke pipe is connected with a chimney. According to the low-nitrogen gas-steam boiler, the boiler body and the combustor are integrally designed, so that complicated structures such as a return smoke tube and a reversal chamber in a traditional boiler are omitted, the overall size of the boiler is greatly reduced, the weight is reduced accordingly, and the boiler is convenient to install and transport.

The application relates to a boiler container, which comprises a container with a containing cavity, a plurality of openings in communication with the containing cavity, an inner wall of the container provided with a reflecting layer, and an outer wall of the container provided with a heat insulation layer; a plurality of boilers, at least one of which is arranged in the opening, and any two adjacent boilers are communicated through at least one heat transfer pipe, the heat transfer pipe is arranged in the containing cavity, and the reflecting layer is used for reflecting heat radiated outward by the heat transfer pipe to the heat transfer pipe. As known from the above, the boiler container in the embodiment can reduce the heat dissipation of the heat transfer pipe, reduce the heat energy loss of the boiler container, increase the number of the heat transfer pipes, and guarantee the energy conversion efficiency of the boiler container.

A system includes a heat exchanger having a plurality of tubes arranged in a tube bundle having opposite first and second sides, opposite third and fourth sides extending from the first side to the second side, and opposite fifth and sixth sides extending from the first side to the second side, wherein the fifth and sixth sides extend between the third and fourth sides. The heat exchanger further includes a plurality of external flow lanes extending across the tube bundle and between the fifth and sixth sides outside of the plurality of tubes. Each tube of the plurality of tubes comprises a plurality of tubing portions extending in opposite first and second directions between the first and second sides in a sequence, and each or at least one successive tubing portion in the sequence switches lanes between the plurality of external flow lanes relative to a preceding tubing portion.

To provide a method for forming a functional self-fluxing alloy coating, capable of exhibiting excellent wear resistance, corrosion resistance and lubricity and suppressing the suppression effect of the adhesion and deposition of ash (clinker) for a long period of time.SOLUTION: A method for forming a functional self-fluxing alloy coating comprises: the thermal spray coating formation step of forming a self-fluxing alloy thermal spray coating on the surface of a base material; the lubricant composition impregnation step; the drying step of drying the thermal spray coating including the impregnated lubricant composition to remove the solvent and form a thermal spray coating including the solid lubricant particles; and the self-fluxing alloy remelting step of heating the thermal spray coating including the solid lubricant particles to remelt the self-fluxing alloy.SELECTED DRAWING: Figure 1

The invention discloses a supercritical gas-fired boiler based on tower type arrangement and a thermal optimization control method, and relates to the field of supercritical gas-fired boilers, the supercritical gas-fired boiler comprises a hearth, a burner, a water cooling wall, a heating surface in the boiler, a header outside the boiler, an economizer and a tubular air preheater. The periphery of the hearth is wrapped by an ash bucket water-cooled wall, a spiral tube coil water-cooled wall and a vertical tube coil water-cooled wall, in-furnace heating surfaces are sequentially arranged in the smoke flowing direction and are suspended through in-furnace suspension tubes, and an out-furnace collecting box is suspended through out-furnace suspension tubes; the economizer is divided into an upper stage and a lower stage, is arranged by adopting sequential tube bundles and is provided with a bypass, and a denitration reactor is arranged between the upper stage and the lower stage; the suspension pipe is made of high-strength alloy steel, a working medium flows in the suspension pipe, and a heating surface and related parts are made of alloy materials with adaptive performance. The invention has the technical effects of high safety of the wall temperature of the heated surface, small deviation, small occupied area, low smoke, wind, steam and water resistance, smooth expansion system, adaption to the rapid variable load requirement, excellent environmental protection property, reliable operation and the like.

The present invention is a method for feeding a chemical to a steam system that controls the injection of a water treatment chemical to the steam system, the method being for feeding a chemical to the steam system that comprises: a pressure sensor, a temperature sensor, or a steam trap as a steam circulation detection means provided to the steam system; and a chemical feed pump for injecting the water treatment chemical to the steam system, said steam system controlling the injection of the water treatment chemical by means of the chemical feed pump in accordance with the steam circulation detection status of the steam circulation detection means.

A bottom seal for a boiler is provided that includes a first refractory layer, a second refractory layer, a plurality of anchors, and an alloy plate. The first refractory layer is made of a castable refractory material. The second refractory layer is positioned below the first refractory layer. The anchors are configured to support the first and second refractory layers. The alloy plate is configured to be positioned below and support the first and second refractory layers. The first and second refractory layers are configured to seal a bottom opening of the boiler.

The utility model discloses a waste heat boiler dense tube panel structure which comprises a plurality of tube panel sets arranged at intervals, a header assembly, an anti-vibration device and a connecting assembly, each tube panel set comprises a plurality of heat exchange tubes and a plurality of connecting tubes, the heat exchange tubes are sequentially arranged and communicated with one another, and the connecting tubes are used for being communicated with the heat exchange tubes in the same tube panel set. The anti-vibration device comprises first anti-vibration pieces arranged at the tops of the tube panel sets and at least one second anti-vibration piece arranged at the bottoms of the tube panel sets, and the connecting assembly comprises a plurality of first connecting plates arranged on the side faces of the tube panel sets in parallel and second connecting plates arranged at the bottoms of the tube panel sets. According to the utility model, the heat exchange efficiency and the heat economy can be improved, and the anti-vibration device which is convenient to disassemble is arranged, so that the efficiency of unit equipment can be prevented from being sacrificed during the maintenance operation, and the maintenance operation is convenient.

This invention discloses an energy-saving boiler vehicle steam generator, relating to the field of energy-saving boiler technology. It includes a boiler drum with end caps fixedly installed at both ends. It also includes a heat exchange tube assembly located inside the boiler drum, comprising two support rings fixedly connected to the sides of the end caps facing the boiler drum. Four support plates are arranged in a rectangular array between the two support rings, with the length direction of the support plates aligned with the axial direction of the support rings. Each support plate has a U-shaped spring fixedly connected to one end facing the support ring, with the opening direction of the U-shaped spring aligned with the axial direction of the support ring. The side of each U-shaped spring away from the support plate is fixedly connected to the outer side of the corresponding support ring. By floating the spiral heat exchange tubes, the constraint force during thermal deformation is reduced, avoiding the cracking, water leakage, and air leakage that easily occur with traditional fixed-connection heat exchange tubes, ultimately leading to heat source waste.

The utility model provides a staged burner and a steam coil thereof. The steam coil pipe comprises a water inlet pipe, a heated coil pipe and a steam ejection ring pipe which are sequentially connected, the heated coil pipe is spiral, the diameter of the inner ring contour of the steam ejection ring pipe is larger than that of the outer ring contour of the heated coil pipe, and a plurality of steam outlet holes are formed in the steam ejection ring pipe. Water enters from a water inlet pipe of the steam coil pipe to cool primary flame combusted in the fire protection barrel, local high temperature is prevented, NOx emission of a primary combustion area is reduced, meanwhile, steam generated by heating is sprayed out from a steam outlet hole of the steam spraying ring pipe, and the steam and secondary air participate in secondary combustion after being mixed in a secondary air shell. OH and H groups generated by decomposition of the water vapor can be subjected to chain reaction with CO generated by primary combustion, the reducing atmosphere is enhanced, NO in-phase reduction reaction is facilitated, meanwhile, H and OH free radicals generated by dissociation of the water vapor can inhibit oxidation of HCN to NO, and the generation amount of NO is reduced under the combined action of the H and OH free radicals and the CO free radicals.

The application discloses a kind of early warning method, device, equipment and storage medium of heated surface tube screen state, by dividing into multiple tube screen nodes, obtain the multiple inner wall temperature information corresponding to the multiple tube screen nodes and the data information of control system, and then calculate the multiple outer wall temperature information corresponding to the multiple tube screen nodes;According to the multiple outer wall temperature information and the data information of control system, calculate the multiple oxide skin generation thickness corresponding to the multiple tube screen nodes;According to the multiple oxide skin generation thickness, preset first critical thickness value and preset second critical thickness value, obtain the multiple oxide skin accumulation thickness corresponding to the multiple tube screen nodes;When any one of the multiple oxide skin accumulation thickness reaches preset accumulation thickness value, generate the early warning information corresponding to the preset accumulation thickness value.The application can monitor the state of high-temperature heated surface tube screen in real time, effectively reduce the occurrence of tube screen explosion leakage accident.

This application relates to the technical field of coal-fired boilers, and provides a method and an apparatus for improving steam oxidation resistance of a small-diameter boiler tube in a coal-fired boiler. The method includes the following steps: cutting a boiler tube panel from a ceiling of the boiler, vertically hoisting and fixing the boiler tube panel, and cutting out a section from a bottom portion of a lower bend of the boiler tube panel; cleaning an inner tube wall of each tube body in the boiler tube panel; performing oxidation resistance coating sintering on the inner tube wall of each tube body in the boiler tube panel; and performing a welding repair on each tube body in a sintered boiler tube panel. All construction processes of this method can be completed in a furnace during shutdown and maintenance, production efficiency is high, and maintenance duration can be significantly reduced. In addition, a steam oxidation resistance layer can be formed on an inner wall of the small-diameter boiler tube, so that a steam oxidation resistance capability of a small-diameter boiler tube in a service coal-fired boiler can be greatly improved.

The invention provides a waste heat recovery device used in front of and behind a square and round billet continuous casting withdrawal and straightening machine, which is characterized by comprising a pipeline system, the heating surface 1 is arranged on a before-cutting roller way between a cutting machine and a withdrawal and straightening machine and is used for absorbing heat of a continuous casting billet; the heating surface 2 is arranged on the arc-shaped section in front of the withdrawal and straightening machine and is used for absorbing the heat of the continuous casting billet; one end of the steam pocket is connected with the heating surface through the pipeline system, and the steam pocket is used for collecting hot steam generated after the heating surface absorbs heat; one end of the circulating water pump is connected with the heating surface 1 through the pipeline system, and the other end of the circulating water pump is connected with the steam pocket to provide circulating power for the whole device. The device has the beneficial effects that heat dissipated to the surrounding environment by blanks in front of and behind a withdrawal and straightening machine of a billet or round billet continuous casting machine is absorbed, the heat is partially converted into heat energy, and steam meeting industrial requirements is formed.

The application provides a water feeding system of a waste heat boiler of a gas turbine heat supply unit, comprising: a heat supply water supplement pipeline, a boiler water feeding pipeline and a unit water supplement pipeline, output ends of the heat supply water supplement pipeline are communicated with the boiler water feeding pipeline and the unit water supplement pipeline respectively; the boiler water feeding pipeline and the unit water supplement pipeline are coupled to a boiler steam-water system respectively; a heat supply water supplement pump is arranged on the heat supply water supplement pipeline, and the heat supply water supplement pump is used for providing water feeding power and water supplement power to the boiler water feeding pipeline and the unit water supplement pipeline respectively. The heat supply water supplement pump of the gas turbine heat supply unit is used for setting pipelines for feeding water to high-pressure, medium-pressure and low-pressure systems of the boiler at the outlet of the pump, and water feeding can be quickly, conveniently and energy-savingly completed by switching valves, so that initial investment and operation energy consumption are reduced, operation is more simple and flexible, the scouring and wearing of a feed water regulating valve are avoided, and the service life of the regulating valve is prolonged.

To provide a heat exchanger which is suitable for recovering heat from a flow medium in a flow layer boiler.SOLUTION: A heat exchanger (10) has: first and second heat exchanger tubes (810, 820); and first and second supply chambers (310, 320) configured to supply a flow medium to the first and second heat exchanger tubes (810, 820) respectively. The first heat exchanger tube (810) is disposed on a first side surface of a plane (P) intersecting with the first supply chamber (310), and the second heat exchanger tube (820) is disposed on a second side surface of the plane (P). The first supply chamber (310) is configured to supply the flow medium to the second supply chamber (320).SELECTED DRAWING: Figure 2

Simply and accurately align and install multiple fire-resistant tiles in their designated positions. [Solution] The process includes: a first step of using one fire-resistant tile 2 as a reference tile 2-1 and hooking it onto a reference hook 5-1 without applying fire-resistant grout; a second step of aligning and fixing one fire-resistant tile 2-2 different from the reference tile 2-1 with the reference tile; a third step of performing either a first branching step after the second step, in which the reference tile 2-1 is removed from the reference hook 5-1 and fixed in alignment with the fire-resistant tile 2-2 fixed in the second step, or a second branching step in which one fire-resistant tile 2-3 different from the fire-resistant tile 2-2 fixed in all the preceding steps of this process is hooked onto an unused hook 5-3 one position away from the hook on which the fixed fire-resistant tile 2-2 was hooked, and fixed while aligning it with the fixed fire-resistant tile 2-2; and a fourth step of repeating the third step a predetermined number of times after the third step.

This utility model relates to the field of circulating fluidized bed boiler technology and discloses a limiting device for a π-shaped bend in the heating surface of a circulating fluidized bed boiler. The device includes a limiting frame, with a π-shaped tube rotatably connected inside the limiting frame. Multiple wear-resistant tiles are fixedly connected to the outside of the π-shaped tube. A limiting block is installed on one of the bottom wear-resistant tiles, and a fixing block is installed on the outside of the other bottom wear-resistant tile. A fixing component is provided inside the fixing block, including a locking body. A sliding column is slidably connected inside the locking body, and a spring is sleeved on the outside of the sliding column. A connecting block is fixedly connected inside the sliding column. In this utility model, the arc-shaped limiting block can restrict the displacement of the π-shaped bend and the swing of the limiting device itself, avoiding friction with the pipe, preventing limiting failure and pipe thinning, and greatly reducing the occurrence of π-shaped bend leakage accidents.

The utility model discloses a multi-pressure steam superheater, which relates to the technical field of superheaters, and comprises a hearth which is of an n-shaped arrangement structure and comprises a heat insulation flue of a burner outlet, a burner arranged at the front end of the heat insulation flue, and a convection heating surface arranged at the outlet of the heat insulation flue. A high-pressure superheater II, a high-pressure superheater I, a medium-pressure superheater II, a medium-pressure superheater I, a low-pressure superheater II, a low-pressure superheater I, a low-low pressure superheater, a steering flue, a tubular air preheater and an outlet flue are sequentially arranged in the convection heating surface; a high-pressure superheater spray desuperheater is arranged in a pipeline between the high-pressure superheater I and the high-pressure superheater II, a medium-pressure superheater spray desuperheater is arranged in a pipeline between the medium-pressure superheater I and the medium-pressure superheater II, and a low-pressure superheater spray desuperheater is arranged in a pipeline between the low-pressure superheater I and the low-pressure superheater II. According to the utility model, the multi-pressure steam overheating condition under various process links of a coal chemical system can be met, the pipe is convenient to block or replace, and meanwhile, the pipe panel is not easy to deform due to overtemperature.

The invention discloses a high-flexibility thin-tube thin-wall parallel modular heating surface coal-fired boiler. Wherein a plurality of cooling walls with the same heat absorption capacity are sequentially arranged in the hearth in the smoke flowing direction; the superheater and the reheater are arranged in the flue; a first heat absorption pipeline of the boiler system is divided into a plurality of strands which are connected in parallel, and each strand is connected with a first working medium acting inlet of the circulating system after sequentially passing through a cooling wall and a superheater to absorb heat. The thickness and the inner diameter of the thin-tube thin-wall heat exchange tube can be reduced by about 40%-60%; compared with a traditional boiler, the heat storage coefficient of the heating surface is reduced, and the thermal inertia is reduced; therefore, the response speed of the boiler is improved, load regulation of the power system can be more quickly participated, and load change can be quickly tracked. The temperature of the outer wall face of the heat exchange tube can be reduced while the thin-wall heat exchange tube is designed, and the safety of a boiler system is improved.

The utility model relates to the technical field of steam generators, in particular to a biomass steam generator which is structurally characterized in that the biomass steam generator comprises a furnace pipe with the inner water capacity not larger than 30 L, a combustion chamber is installed at the lower end of the furnace pipe, a single-layer finned pipe is annularly arranged on the periphery of the furnace pipe, and an inner double-coil pipe is arranged outside the single-layer finned pipe; an inner double-coil pipe and a single-layer finned pipe form a first flue, an outer double-coil pipe is arranged outside the inner double-coil pipe, the inner double-coil pipe and the outer double-coil pipe form a second flue, a smoke outlet is formed in an outlet of the second flue, a double-layer finned pipe is arranged between the inner double-coil pipe and the outer double-coil pipe, and a steam outlet is formed in the upper portion of the single-layer finned pipe. Biomass is combusted in the furnace pipe, then enters a flue gas channel formed by the inner double-coil pipe and the single-layer finned tube energy saver, finally passes through a flue gas channel formed by the inner double-coil pipe and the outer double-coil pipe and the double-layer finned tube between the inner double-coil pipe and the outer double-coil pipe to recycle heat, and convective heat transfer is conducted again. The heat efficiency of the energy saver is improved, and the dust content of smoke is reduced.

The invention discloses a supercritical variable-pressure operation coal-fired boiler which comprises a boiler body unit, a boiler wall, a supporting ring plate arranged on the boiler wall and a plurality of burner air boxes arranged on the boiler wall. The evaporation unit comprises a top plate arranged on the furnace wall, an evaporation pipe assembly arranged on the lower end face of the top plate and a bottom plate arranged at the bottom end of the evaporation pipe assembly. The limiting unit comprises a first limiting plate arranged on the evaporation pipe assembly, a hinge arranged on the first limiting plate, a second limiting plate arranged on the hinge, a locking assembly arranged on the second limiting plate, a clamping assembly arranged on the first limiting plate and the second limiting plate, and a limiting block arranged on the first limiting plate. According to the supercritical variable-pressure operation coal-fired boiler, the evaporation pipe assembly integrally penetrates through a large heat absorption area and a small heat absorption area in the boiler wall, so that heat absorption is uniform; the inclination angle of the evaporation pipe assembly is accurately controlled through the arranged limiting unit, and angle deviation of the evaporation pipe assembly under long-time high-temperature operation is avoided.

The utility model relates to a steam generator and cooking equipment, which can generate high-temperature steam in a microgravity environment to cook food and meet the taste and taste requirements of passengers. The steam generator comprises a water supply pipe which is provided with a water supply flow channel and a plurality of capillary holes communicated with the water supply flow channel; the water absorption piece is fixedly connected to the water supply pipe so as to cover the capillary holes, and the water absorption piece is provided with a porous structure and is used for absorbing water under the capillary action; and the heating piece is arranged on the water absorption piece and is used for heating the water absorption piece to generate steam.

The application discloses a SHS gas boiler with straight fin tube special-shaped combined multi-mechanism coupled enhanced heat exchange, which comprises a full premix water-cooled burner, upper and lower boiler drums, a furnace membrane water-cooled wall, a front light tube bundle and a straight fin tube special-shaped combined tube bundle group. The full premix water-cooled burner ignites and burns after mixing air and gas on the inner surface of a water-cooled combustion head; high flue gas is cooled by the furnace membrane water-cooled wall and the front light tube bundle, and then enters a straight fin tube special-shaped combined tube bundle group formed by symmetric fork-shaped straight fin tubes and front and rear double-wing-shaped longitudinal flat fin tubes to form a multi-mechanism coupled enhanced heat exchange tube row, and the flue gas is discharged from the boiler body after being gathered. x The full premix water-cooled combustion reduces the combustion temperature to realize ultra-low NOx emission, the flame length is short, and the depth of the furnace is only one tenth of that of a traditional diffusion combustion boiler; the straight fin tube special-shaped combined tube bundle group significantly improves the heat exchange coefficient of the tube bundle group, greatly reduces the longitudinal row number of the water pipes, is only one tenth of that of a traditional SZS longitudinal row number, and significantly reduces the steel consumption of the boiler, welding workload, manufacturing cost and carbon emission.

The invention relates to a steam generator and a steam generator simulation structure. The external downcomer can be formed by directly bending and welding a standard pipe without customizing a special-shaped structure matched with the annular gap, so that the manufacturing cost is reduced. When the external downcomer breaks down, the external downcomer can be directly and independently maintained or replaced, core components such as the shell and the heat transfer pipe do not need to be disassembled, the risk that the core components are damaged in the disassembling process is reduced, and the maintenance cost is reduced. In addition, a descending channel with an annular gap is adopted, the coaxiality and the gap uniformity of the shell and the cylinder need to be strictly controlled, and multiple times of calibration and debugging need to be carried out; the external downcomer only needs to fix two end interfaces, the assembly process is simplified, and the test preparation period is shortened. Meanwhile, parameters such as the pipe diameter and the length of the external downcomer can be flexibly adjusted, the main body structure of the shell does not need to be changed, contrast tests of different circulation parameters can be conveniently carried out, the test period is shortened, data monitoring in the test process is more direct, test errors caused by a complex structure are reduced, and repeated test cost is reduced.

The embodiment of the utility model provides an instant heating type liquid and steam heating device which comprises a shell, at least one pipeline piece and at least one electric heating body, the shell can conduct heat, the pipeline piece is arranged in the shell, the two ends of the pipeline piece extend out of the two ends of the shell respectively, and the two ends of the electric heating body extend out of at least one side of the shell respectively; the electric heating body can heat under the condition of electrification; according to the embodiment of the invention, the pipeline connecting end and the power connection connecting end are staggered at the end part and the periphery of the shell, the installation space of the pipeline connecting end and the power connection connecting end is increased, the pipeline connecting end and the power connection connecting end are not easy to interfere with each other during respective installation, the installation efficiency is improved, and the power connection connecting end is far away from the pipeline connecting end. And the safety risk of power connection leakage is reduced.

The utility model provides a water cooling wall structure convenient to assemble and a boiler, the water cooling wall structure convenient to assemble comprises a plurality of water cooling wall modules, each water cooling wall module comprises a first collecting box, a second collecting box and a plurality of water cooling wall pipes, and the water cooling wall pipes are vertically arranged in parallel in the first direction; the first ends of the water cooling wall pipes are fixedly connected with the first collecting box, the second ends of the water cooling wall pipes are fixedly connected with the second collecting box, the water cooling wall pipes are connected with the first collecting box and the second collecting box in the mode that the water cooling wall pipes are directly assembled and welded in a field to form the assembled water cooling wall module to leave a factory, and a large amount of field assembling and welding work of the boiler water cooling wall is reduced. According to the convenient assembly type water cooling wall through structure, the water cooling wall pipe and the collecting box are modularly assembled and welded in advance and leave a factory, so that the tedious welding and assembling workload on site is reduced, and the assembling efficiency is improved.

We provide protective refractory materials with excellent maintenance performance. [Solution] The protective fire-resistant material has a recess on its back surface into which the tip of the mounting bracket fixed to the protected member is inserted. A groove extends from the recess toward the end face in the direction of the protective fire-resistant material, and the fixing member is inserted through the groove and engages with the mounting bracket, thereby fixing the protective fire-resistant material to the mounting bracket.

The application discloses a water circulation system for stable operation of a once-through boiler at low load, which comprises a steam-water separator, a water storage tank, a recirculation pump, a high-pressure heater, a feedwater pump, an economizer, a water-cooled wall, a superheater, a steam-water heat exchanger, a steam turbine and a reheater; the steam-water separator is connected with the water storage tank and the superheater respectively, the water storage tank is connected with the recirculation pump, the feedwater pump is connected with the high-pressure heater, the economizer is connected with the water-cooled wall, and the water-cooled wall is connected with the steam-water separator; the steam-water heat exchanger is connected with the recirculation pump, the high-pressure heater, the economizer and the steam-water separator respectively; the steam turbine is connected with the superheater; and the reheater is connected with the steam turbine and the steam-water heat exchanger respectively. The steam-water heat exchanger is used for heating the feedwater after the recirculation water is mixed with the feedwater, and the inlet temperature of the water-cooled wall is increased after the recirculation flow is increased, so that the problem of the water power multi-value of the water-cooled wall is solved, and the water power stability of the once-through boiler at low load is ensured.