CN106838852B - Membrane type steam generator - Google Patents
Membrane type steam generator Download PDFInfo
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- CN106838852B CN106838852B CN201710141957.1A CN201710141957A CN106838852B CN 106838852 B CN106838852 B CN 106838852B CN 201710141957 A CN201710141957 A CN 201710141957A CN 106838852 B CN106838852 B CN 106838852B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B1/00—Methods of steam generation characterised by form of heating method
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B37/00—Component parts or details of steam boilers
- F22B37/02—Component parts or details of steam boilers applicable to more than one kind or type of steam boiler
- F22B37/48—Devices for removing water, salt, or sludge from boilers; Arrangements of cleaning apparatus in boilers; Combinations thereof with boilers
- F22B37/54—De-sludging or blow-down devices
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
- F22D5/00—Controlling water feed or water level; Automatic water feeding or water-level regulators
- F22D5/26—Automatic feed-control systems
- F22D5/28—Automatic feed-control systems responsive to amount of steam withdrawn; responsive to steam pressure
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P80/00—Climate change mitigation technologies for sector-wide applications
- Y02P80/10—Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier
- Y02P80/15—On-site combined power, heat or cool generation or distribution, e.g. combined heat and power [CHP] supply
Abstract
The invention relates to a membrane type steam generator, which consists of a water supply pipeline, a membrane type evaporation pipe and a steam outlet and water return pipeline, wherein the water supply pipeline comprises a water supply main pipe and a water supply branch pipe, and water supply flows from the inlet end of the water supply main pipe to the tail end of the water supply branch pipe; the steam outlet water return pipeline comprises a steam outlet water return main pipe and a steam outlet water return branch pipe; one end of the membrane evaporation tube is connected with the water supply main pipe and/or the water supply branch pipe, and the other end of the membrane evaporation tube is connected with the steam outlet water return main pipe and/or the steam outlet water return branch pipe; the steam in the steam-outlet backwater branch pipe ascends to be output from the high-position steam outlet end and is converged into the steam-outlet backwater main pipe, and the backwater descends to be converged into the steam-outlet backwater main pipe from the low-position backwater end; and finally, the return water is output from a return water outlet and collected into a water supply circulation tank, and the water is supplemented to realize circulation water supply. The advantages of both the drum type boiler and the once-through type boiler are taken into consideration, the defects of the drum type boiler and the once-through type boiler are avoided, and the method has popularization value.
Description
Technical Field
The invention belongs to the technical field of steam generating equipment, and particularly relates to a membrane type steam generator.
Background
Energy has an important position in national economic life, and all walks of life can not leave the energy. Industrial steam (hereinafter referred to as steam) is a main energy carrier (heat energy, potential energy and kinetic energy); the steam production equipment is mainly an industrial boiler, and the industrial boiler converts various fuels such as coal, gas, fuel oil or biomass and the like from chemical energy into heat energy and potential energy (kinetic energy) to provide heat energy for production equipment, facilities, living facilities and the like; in the power plant, potential energy heat energy is provided for the steam turbine by the boiler and is converted into kinetic energy of the generator set to generate power. Therefore, it plays an important role in industrial production as an industrial boiler for producing steam.
The existing industrial boilers are mainly classified into drum type boilers, natural (or forced) circulation type boilers, and once-through type (three types of horizontal type, vertical type, and horizontal and vertical mixed type) boilers in a manner that feed water is heated to vaporize, as shown in five cases in fig. 1 to 3 and fig. 4 to 6. Both the drum type boiler and the natural (or forced) circulation type boiler are provided with a drum for water-vapor separation, so that the boiler is called a steam drum type boiler; because the steam pocket type boiler has large diameter and large length, the wall thickness of the cylinder body needs to be increased to realize safe and reliable operation under high temperature and high pressure, and the manufacturing cost of equipment is high; when the boiler operates, the system must keep a certain water quantity; take a drum boiler producing 10t/h steam as an example, the upper part and the lower part of the boilerThe total volume of the steam drum and the heated tube nest is 12m 3 When the steam supply system is normally operated, the liquid level in the upper steam drum is maintained at 40-80%, the liquid holdup of the system is about 10-11 t of water, the cooling furnace is started to normally supply steam after stopping every time, and the 10-11 t of water is heated to a saturation point above the required steam pressure after 1-2 hours of consumption, so that the steam can be normally supplied; the furnace shutdown needs 18 to 24 hours for cooling and pressure reduction. The natural (or forced) circulation boiler has complex structure, and needs to be provided with a plurality of discharge points for periodic pollution discharge in order to avoid the concentration and enrichment of salts brought in boiler feed water in the header. When the steam supply load of the steam drum type boiler changes, the whole water supply needs to be adjusted, and the load is lifted and lowered slowly. The once-through boiler has no steam pocket, the liquid holdup of the system is only 1/2-1/4 of that of a steam pocket type boiler, and the feed water can reach the boiling point under the steam supply pressure only by absorbing less heat; igniting the cold furnace for about 40-45 minutes to supply steam with rated temperature and pressure; about 25 minutes is required to shut down the furnace. The once-through boiler has no circulation function, feed water passes through the system from the inlet to the steam outlet in one step, and the heating, vaporization and overheating processes are completed in the heated tubes, so that the heating can be realized only by requiring the heating tubes to have enough length; a special system is needed to be arranged so that enough feed water passes through the heated tube when the boiler is started, and the saturated heated tube cannot be burnt out due to overheating; under the condition that the heating flow of the heated tube of the once-through boiler is fixed, if the proportion of fuel and water supply is not adjusted, the once-through boiler can not ensure to supply qualified steam; therefore, the once-through boiler has high requirements on an automatic adjusting and controlling system; because the once-through boiler can not discharge sewage, the salt in the feed water can form scale on the inner wall of the heated pipe, and the economic and safe operation of the boiler is influenced, the feed water requirement of the once-through boiler is high, and the water treatment investment and the operation cost are high; because the heating pipe of the once-through boiler passes through once, the working medium (industrial soft water) completely flows through all heating surfaces by the pressure of the feed water pump, and has larger mass flow; therefore, the outlet pressure of the feed pump is high, and the consumed power is high.
In summary, the existing industrial boiler has the following disadvantages:
1. the steam drum type boiler has heavy steam drum and large consumption of special metal; the steam drum is heavy and inconvenient to manufacture, install and transport;
2. the drum type boiler system has huge liquid holdup and long start-stop time;
3. the steam drum type boiler has slow load reaction in lifting and large energy waste in starting and stopping;
4. the drum boiler has a complex structure, the system circulation has dead corners, and a plurality of discharge points are required to be arranged for discharging pollution;
5. the energy waste of the steam drum type boiler is large when the boiler is started and stopped;
6. the flow of the heating pipe of the once-through boiler is long;
7. the once-through boiler needs to be provided with a special system for solving the problem of heating pipes and burning pipes during driving;
8. the once-through boiler has higher requirements on an automatic regulation and control system;
9. the once-through boiler has high investment and operation cost for water treatment;
10. the feed pump of the once-through boiler has large power consumption.
Disclosure of Invention
The invention aims to overcome the defects of heavy equipment, high manufacturing cost, long start-stop time, large start-stop energy waste, slow load reaction, complex structure, long flow of heated pipes, high requirements on an automatic regulation and control system, high water treatment investment and operation cost, large power consumption of a feed pump and the like of the conventional industrial boiler, and provides a membrane type steam generator which has the advantages of a steam pocket type boiler and a direct-current boiler and has the main operation characteristics of light weight, low consumption of special metals, short start-stop time, quick load reaction, simple structure, small start-stop energy waste, small heated pipe flow, general requirements on the automatic regulation and control system, general water supply requirements and cost, general power consumption of the feed pump and the like.
The technical scheme adopted by the invention for solving the problems is as follows: a membrane type steam generator mainly comprises a water supply pipeline, a membrane type evaporation pipe and a steam outlet and water return pipeline, wherein the water supply pipeline comprises a water supply main pipe and a water supply branch pipe, and water flows from the inlet end of the water supply main pipe to the tail end of the water supply branch pipe in one direction without dead angles; the steam outlet and water return pipeline comprises a steam outlet and water return main pipe and a steam outlet and water return branch pipe; one end of the membrane type evaporation tube is connected with a water supply header pipe and/or a water supply branch pipe, the other end of the membrane type evaporation tube is communicated with a steam outlet water return header pipe and/or a steam outlet water return branch pipe, water supply is distributed to the membrane type evaporation tube through the water supply header pipe or the water supply branch pipe, the water supply flows along the inner wall of the membrane type evaporation tube in a liquid film manner, the membrane type evaporation tube is heated, the liquid film is heated and directly vaporized into saturated steam, the steam flows along with the liquid film and enters the steam outlet water return header pipe or the steam outlet water return branch pipe, and the unvaporized water supply is used as return water; the steam or the mixture of the steam and partial backwater in the steam-outlet backwater branch pipe goes upward and is output from the high-position steam-outlet end and is converged into the steam-outlet backwater main pipe, and the mixture of the backwater or the backwater and partial steam goes downward and is converged into the steam-outlet backwater main pipe from the low-position backwater end; the steam-outlet backwater main pipe is provided with a high-level steam outlet and a low-level backwater outlet, the steam in the steam-outlet backwater main pipe further ascends to be separated from backwater and is finally output by the steam outlet, the backwater further descends to be separated from the steam, and the backwater is finally output by the backwater outlet and is collected into the water supply circulation tank, and the circulating water supply is realized after the backwater is supplemented.
The water supply circulation tank is externally connected with a water supply pipeline, return water and supply water (industrial soft water) are mixed in the water supply circulation tank, and the mixture is conveyed to a water supply main pipe by a water supply pump at constant flow and pressure, and the circulation is carried out.
Preferably, the return water pipeline is provided with a sewage outlet, sewage can be discharged according to the specific condition of the quality of return water, in the evaporation process, the content of impurities in the feed water can be gradually increased, the impurities are not easy to form salt frost in the pipe wall because the liquid film is continuously updated and continuously flows, but the salinity or the content of the impurities of the return water is higher than that of the feed water, so that the return water is necessary to be regularly purified and discharged according to the specific actual operation condition.
Preferably, the pressure difference between the water supply pressure and the saturated steam output by the steam outlet return water main pipe is constant, the control range of the pressure difference is 0.1-0.4 MPa, and the water supply mass flow is controlled to be 2-5 times of the rated evaporation capacity; the pressure difference between the feed water and the saturated steam is preferably controlled between 0.2 and 0.3MPa. Therefore, the power consumption of the feed pump is stable and small, and the total power consumption is only about 10 to 25 percent more than that of the steam drum type boiler due to the power consumption of the water replenishing pump, and the power consumption of the feed pump of the once-through boiler with the same evaporation scale is about 5 to 8 times of that of the steam drum type boiler.
According to different pressures of the membrane type evaporation tubes at various points in the system and different heat energy distribution densities of the tubes, the membrane type evaporation tubes in different forms and different specifications are arranged; since the flow and pressure supplied by the feed pump are constant, the liquid film distribution in the membrane evaporator tube at each point of the evaporator is also stable. Because the membrane evaporator supplies excessive water, a liquid film on the inner wall of the heated tube is stable, no cracking or cutoff occurs, the heat transfer deterioration phenomenon does not exist, and the safe operation of the system cannot be influenced by any change of load, so that the evaporator system does not need a precise and strict control system like a once-through boiler system.
The membrane type steam generator only consists of a water supply pipeline, a membrane type evaporation pipeline and a steam outlet and water return pipeline, a heavy steam drum is not arranged, and a light framework can be adopted in an evaporator system for supplying heat to a pulverized coal burner and a gas and oil burner to lightweight the whole steam generator system; because the thick-wall steam drum and water stored in the steam drum are not arranged, the heating and cooling of each part of the steam generator are more uniform in the starting and stopping processes; under the condition of cold-state driving, after the fuel is normally combusted to supply heat, the evaporator can normally supply steam with qualified temperature and pressure only in 2-5 minutes; because the feed water in the evaporator system is heated cyclically, the evaporator tubes do not need to be provided with long heating tubes, which is the case with once-through boilers, which require a sufficiently long heating and vaporizing process. The water supply in the membrane type evaporation pipe is distributed in a membrane state with the thickness of 0.1-0.3 mm, so the liquid holdup in the whole evaporator is very small; taking a membrane steam generator with 10t/h evaporation capacity as an example, the liquid holdup in the whole evaporator is about 0.2-0.3 m 3 The liquid holdup in the evaporating pipe is about 0.03-0.06 m 3 And the total liquid holdup of the 10t/h drum type boiler is 10.2-11.2 m 3 The liquid holdup of the tube array is about 5.7m3, the comprehensive liquid holdup of the membrane evaporator is only 1/100-1/200 of that of a steam drum boiler, and the heat energy loss is little in the process of starting and stopping the system. Because the heating target water quantity of the membrane type evaporation tube is very little, the vaporization capacity is large, the balance between the heat energy supply and the soft water vaporization in the evaporator is rapid, and the strain response of the evaporator to the external load change is rapid; will generatorThe output steam pressure and the fuel feeding combustion control are interlocked, the fuel supply can be controlled in real time according to the output pressure change, the linear control between the fuel and the load can be realized, and the stable steam supply can be realized under the conditions of large and frequent external load change.
Furthermore, the water supply of the film type evaporation generator is from the water supply main pipe to the steam return main pipe, the process is one-way, no dead angle exists, and the whole water flow smoothly circulates; the concentrated return water can be discharged on a return water pipeline at the rear end of the steam outlet return water main pipe without additionally arranging a plurality of discharge spots; due to the blowdown function, the feed water of the membrane evaporator can meet the feed water standard of the drum boiler, and high-requirement investment and operating cost of water treatment facilities are not required. The membrane type steam generator system only needs to be driven by water circulation and heat energy supply, is relatively simple, and does not need to be additionally provided with a driving treatment system. The requirement on auxiliary equipment is low.
The film type evaporation tube consists of a film section for distributing water at the top, a middle film type evaporation section and a lower vapor-liquid separation section.
The top water supply distribution film distribution section comprises a film distributor, the film distributor controls the water supply feeding direction and the feeding amount to directly form a film along the wall, or the combination film distributor redistributes the uniform film to ensure that the liquid film flows down along the wall contact heating surface in a uniform water film shape under the action of the initial flow velocity and the gravity.
In the middle film evaporation section, the heated tube provides heat energy in radiation and convection conduction modes at an external heat source, the liquid film continuously and alternately flows, so that the whole liquid film is uniformly heated, the feed water is evaporated and vaporized by a liquid phase after absorbing the heat energy, and the vaporized vapor phase steam is directly diffused to the central space of the heated tube without overcoming the resistance of the liquid phase water film.
The lower vapor-liquid separation section consists of a vapor phase outlet and a liquid phase outlet, the vapor phase outlet is arranged at the upper part of the liquid phase outlet, and the openings of the vapor phase outlet and the liquid phase outlet are in different directions; the water vapor is directed in a different direction than the unvaporized water to form a vapor stream and a liquid stream path. The steam-liquid mixing interaction is avoided, so that the rapid separation and circulation of steam and water in a limited space are facilitated. In the case of sufficient space for effective separation of the vapor and liquid phases, this lower separation stage can be omitted, with the vapor and water being delivered directly from the evaporator tubes.
The film distributor of the application mainly has several forms: plate hole type film distributor, wall hole type film distributor, plate ring type film distributor and spiral film distributor.
The plate hole type film distributor is characterized in that 2-20 water inlets are distributed downwards on a top end sealing plate along the tangential direction of a heated tube, the water inlets are round, square or rectangular, the sectional area of the water inlets is equivalent to that of a round hole with the diameter of 0.5-5 mm, and the number and the specification of the water inlets are set according to the evaporation task of the heated tube.
The wall hole type film distributor is arranged below the top end sealing plate, and 2-20 water inlet holes are distributed downwards on the heated tube along the tangential direction of the heated tube; the water inlet hole can be round, square or rectangular, and the cross section area and the shape of the water inlet hole are equal
The circular holes are equivalent, and the number and the specification of the water inlet holes are set according to the evaporation task of the heated tube.
The plate-ring type film distributor is characterized in that a ring-shaped water inlet is arranged on a top end sealing plate towards the pipe wall direction of a heated pipe, and a lower end outlet ring gap is set to be 0.02-0.5 mm according to the evaporation load of the heated pipe.
The spiral film distributor is provided with one on the top end sealing plate according to the evaporation load of the heated tube
The lower end of the round hole is provided with a spiral sprayer with corresponding specification, and the top water inlet is sprayed to the inner wall surface of the heated tube in an umbrella-shaped sector.
For the common operation state, the film distributing effect of the water sprayed to the wall surface by the film distributing devices achieves the application purpose; the lower end of the film distributor is additionally provided with a film homogenizing ring, so that liquid drops which possibly splash to the outside of the wall surface due to high speed are guided to the wall surface, and the feed water flows downwards along the wall in an annular liquid film.
Furthermore, the specification of the membrane type steam generating pipe is DN 20-DN 200 special steel pipe for the boiler, and the length-diameter ratio l/d is between 50 and 200; the length proportion of the top water distribution membrane distribution section and the lower gas-liquid separation section is 1-2% of the whole length, the membrane distributor is filled with water in and above the whole length, the membrane distributor is covered by liquid membranes on the inner wall of a following pipe, the thickness of the liquid membranes is 0.05-1 mm, and the average thickness of the liquid membranes is 0.1-0.2 mm under the common condition.
The film type evaporation tube has the advantages that the evaporation area is large, the heat transfer coefficient is large, the heat transfer efficiency is stable (the heat transfer deterioration phenomenon cannot occur), the wall temperature of a heated tube is relatively constant and low (see patent: one film type evaporation tube), for producing steam with the same specification and yield, the requirement on the heat supply temperature of a combustor in a film type evaporator system is lower than that of the existing boiler, the overall heat transfer efficiency of the existing boiler is not high due to the heat transfer deterioration phenomenon, the evaporation area is small, and the defects of the heat transfer efficiency and the evaporation area can only be compensated by improving the temperature; the temperature of a hearth of the existing boiler is normally controlled to be 900-1100 ℃, sometimes reaches 1200-1300 ℃, and the combustion temperature of visible flame is very high; the temperature of a combustion cavity of the membrane evaporator is only 500-800 ℃, the flame temperature is much lower, and the low-temperature combustion can effectively inhibit NO in fuel gas X Generation of (2); and the low-temperature combustion reduces the volatilization of fuel ash, thereby reducing the slag accumulated on the surface of the heated tube and avoiding the heat transfer deterioration between the fuel gas and the heated tube.
The film type evaporating pipes adopted by the application have independence and can be freely combined according to needs, so that the evaporator can adapt to different types of heat supply conditions, can supply heat by using a layer combustion type coal or biomass chain furnace, and can also be used for supplying heat by using pulverized coal, gas and fuel oil burners.
In summary, the membrane evaporator of the present invention is compared with a drum boiler and a once-through steam generator to produce steam of the same specification and scale or to convert the steam into steam of the same specification and scale, as follows:
the membrane type steam generator has the advantages of both a steam drum type boiler and a straight-flow type boiler, avoids the defects of the steam drum type boiler and the straight-flow type boiler, and has popularization value.
Drawings
FIG. 1 is a drum type boiler steam generating structure;
FIG. 1: heating pipe 1, combustion chamber 2
FIG. 2 is a natural (forced) circulation boiler;
FIG. 2:1 drum, 2 descending heated tubes, 3 headers and 4 ascending heated tubes
FIG. 3 is a horizontal surrounding coil once-through boiler;
FIG. 3:1 combustion chamber, 2 horizontal heated tube
FIG. 4 is a looped once-through boiler;
FIG. 5 is another configuration of a once-through boiler with a looped tube;
FIGS. 4 to 5:1 horizontal heated tube, 2 vertical heated tube, 3 header
FIG. 6 is a vertical tube panel once-through boiler;
FIG. 6:1 vertical heated tube, 2, header
FIG. 7 is a typical plot of saturated water boiling on a horizontal heating surface;
FIG. 8 is a schematic view of a first type of heat transfer deterioration;
FIG. 9 is a schematic diagram of a second type of heat transfer deterioration;
FIG. 10 is a schematic diagram of the structure of the film evaporation of the present application;
FIG. 11 is a sectional view of a steam generating tube (single outlet type) in the embodiment of the present application;
FIG. 12 is a side view of a steam generating channel (single outlet type) according to an embodiment of the present application;
FIG. 13 is a sectional view of a steam generating channel (double vent type) in an embodiment of the present application;
FIG. 14 is a side view of a steam generating channel (double-outlet type) according to an embodiment of the present application;
FIG. 15 is a vertical cross-sectional view of a plate hole type film distributor (without a film homogenizing ring) in the embodiment of the application;
FIG. 16 is a transverse cross-sectional view of a plate hole type membrane distributor (without a membrane homogenizing ring) in the embodiment of the application;
FIG. 17 is a vertical cross-sectional view of a plate hole type film distributor (with a film homogenizing ring) in the embodiment of the application;
FIG. 18 is a transverse cross-sectional view of a plate hole type film distributor (with a film homogenizing ring) in the embodiment of the application;
FIGS. 15 to 18:1 pipe wall, 2 distribution plates, 3 water inlet holes and 4 uniform membrane rings
FIG. 19 is a vertical cross-sectional view of a wall-hole film applicator (without a film homogenizing ring) in an embodiment of the present application;
FIG. 20 is a transverse cross-sectional view of a wall-hole film applicator (without a film homogenizing ring) in an embodiment of the present application;
FIG. 21 is a vertical cross-sectional view of a wall-hole film applicator (with a film homogenizing ring) in an embodiment of the present application;
FIG. 22 is a transverse cross-sectional view of a wall-hole film applicator (with film homogenizing ring) in an embodiment of the present application;
FIGS. 19-22:1 pipe wall, 2 closing plates, 3 water inlet holes and 4 membrane-equalizing rings
FIG. 23 is a vertical cross-sectional view of a plate-ring type film distributor (without a film homogenizing ring) in an embodiment of the present application;
FIG. 24 is a transverse cross-sectional view of a plate-ring type film distributor (without a film homogenizing ring) in an embodiment of the present application;
FIG. 25 is a vertical cross-sectional view of a plate-ring type film distributor (with a film homogenizing ring) in an embodiment of the present application;
FIG. 26 is a cross-sectional view of a plate-ring type film distributor (with a film homogenizing ring) in an embodiment of the present application;
FIGS. 23-26:1 pipe wall, 2 distribution plates, 3 water inlet rings and 4 uniform membrane rings
FIG. 27 is a vertical cross-sectional view of a spiral film distributor (without a film homogenizing ring) in an embodiment of the present application;
FIG. 28 is a transverse cross-sectional view of a spiral film distributor (without a film homogenizing ring) in an embodiment of the present application;
FIG. 29 is a vertical cross-sectional view of a spiral film distributor (with a film homogenizing ring) in an embodiment of the present application;
FIG. 30 is a cross-sectional view of a spiral film distributor (with a film homogenizing ring) in an embodiment of the present application;
FIGS. 27 to 30:1 pipe wall, 2 distribution plates, 3 water inlet holes, 4 uniform film rings, 5 spray headers, 6 rib plates and 7 balance holes
FIG. 31 is a side view of a film evaporator (stratified type) in an embodiment of the present application;
FIG. 32 is a perspective view of a membrane evaporator (of the stratified type) in an embodiment of the present application;
FIGS. 31-32: the system comprises a water supply main pipe 1, water supply branch pipes 2, membrane type evaporation pipes 3, a steam outlet return branch pipe 4, a steam outlet return main pipe 5, a circulation tank 6 and a water supply pump 7.
FIG. 33 is a perspective view of a membrane evaporator (pulverized coal fired heating) according to an embodiment of the present application;
FIG. 34 is a perspective view of a membrane evaporator (gas and oil fired) in accordance with an embodiment of the present application.
Detailed Description
The invention is described in further detail below with reference to the accompanying examples.
As shown in fig. 31, the membrane steam generator in this embodiment mainly comprises a water supply pipe, a membrane evaporation pipe 3, and a steam outlet and return pipe, wherein the water supply pipe comprises a water supply main pipe 1 and a water supply branch pipe 2, and the water supply flows from an inlet end of the water supply main pipe 1 to a tail end of the water supply branch pipe 2, and keeps flowing in one direction without dead angle. The steam outlet and water return pipeline comprises a steam outlet and water return main pipe 5 and a steam outlet and water return branch pipe 4. One end of the membrane type evaporation tube 3 is connected with the water supply header pipe 1 and/or the water supply branch pipe 2, the other end of the membrane type evaporation tube is communicated with the steam outlet backwater header pipe 5 and the steam outlet backwater branch pipe 4, the water supply is distributed to the membrane type evaporation tube 3 through the water supply header pipe 1 and the water supply branch pipe 2, the water supply flows along the wall of the inner wall of the membrane type evaporation tube 3 in the form of a liquid film, the membrane type evaporation tube 3 is heated, the liquid film is heated and directly vaporized into saturated steam, the steam flows along with the liquid film and enters the steam outlet backwater header pipe or the steam outlet backwater branch pipe, and the unvaporized water supply serves as backwater; the steam or the mixture of the steam and partial backwater in the steam-outlet backwater branch pipe ascends to be output from the high-position steam outlet end and is converged into the steam-outlet backwater main pipe, and the mixture of the backwater or the mixture of the backwater and partial steam descends to be converged into the steam-outlet backwater main pipe from the low-position backwater end; the steam-water outlet main pipe is provided with a high-level steam outlet and a low-level water return outlet, steam in the steam-water outlet main pipe further goes upward and is separated from return water, the steam is finally output through the steam outlet, the return water further goes downward and is separated from the steam, the return water is finally output through the water return outlet and is collected into the water supply circulating tank 6, the water supply circulating tank 6 is externally connected with a water supplementing pipeline, the return water and supplementing water (industrial soft water) are mixed in the water supply circulating tank 6, and the water and the supplementing water are conveyed to the water supply main pipe through the water supply pump 7 at constant flow and pressure, so that the cycle is carried out.
And a sewage discharge port is arranged on the return water pipeline, so that sewage discharge can be implemented according to the specific condition of the quality of the return water.
The pressure difference between the water supply pressure and the saturated steam output by the steam outlet return water main pipe is constant, the control range of the pressure difference is 0.1-0.4 MPa, and the water supply mass flow is controlled to be 2-5 times of the rated evaporation capacity; the pressure difference between the feed water and the saturated steam is preferably controlled to be 0.2-0.3 MPa. Therefore, the power consumption of the feed pump is stable and small, and the total power consumption is only about 10 to 25 percent more than that of the steam drum type boiler due to the power consumption of the water replenishing pump, and the power consumption of the feed pump of the once-through boiler with the same evaporation scale is about 5 to 8 times of that of the steam drum type boiler.
As shown in fig. 11 to 14, the membrane steam generator in this embodiment is composed of a top water distribution membrane section I, a middle membrane evaporation section II, and a lower vapor-liquid separation section III.
The top water supply and distribution membrane distribution section I comprises a membrane distributor 1, the membrane distributor 1 controls the water supply feeding direction and the feeding amount to directly form a membrane along the wall, and the liquid membrane flows down along the wall contact heating surface in a uniform water membrane shape under the action of the initial flow velocity and the gravity.
In the middle film evaporation section II, the heated tube provides heat energy from a heat source outside the tube in a radiation and convection conduction mode, the liquid film on the inner wall of the tube continuously and alternately flows to ensure that the whole liquid film is uniformly heated, the feed water is evaporated and vaporized by a liquid phase after absorbing the heat energy, the vaporized steam is directly diffused to the central space of the heated tube, the resistance of the liquid phase water film does not need to be overcome, and the steam runs along with the liquid film in a pipeline.
The lower vapor-liquid separation section III is composed of a vapor-phase outlet a and a liquid-phase outlet b, and more than one, two or more than two vapor-phase outlets and liquid-phase outlets may be provided. The vapor phase outlet a is arranged at the upper part of the liquid phase outlet b, and the opening directions are different; the water vapor is directed in a different direction than the unvaporized water to form a vapor stream and a liquid stream path.
It should be noted that in the case of sufficient space for efficient separation of the vapor and liquid phases, this lower separation stage can be omitted, with the water vapor and return water being directly output from the evaporation tubes.
The film distributor arranged at the film distribution section for distributing water at the top mainly has several forms: plate hole type film distributor, wall hole type film distributor, plate ring type film distributor and spiral film distributor.
As shown in fig. 15 to 18, the plate-hole type membrane distributor is formed by distributing 2 to 20 water inlets downwards along the tangential direction of the heated tube on a top end sealing plate, wherein the water inlets are round, square or rectangular or other shapes, the sectional area is equivalent to a round hole with the diameter of 0.5 to 5mm, and the number and the specification of the water inlets are set according to the evaporation task of the heated tube. In this embodiment, the specification of the film type evaporating pipe of the plate-hole type film distributor
Bore of water inlet hole
The number of water inlet holes n =7, and the total length of the evaporation tube l =15m.
As shown in fig. 19 to 22, the wall-hole type film distributor is that 2 to 20 water inlet holes are distributed downwards on the heated tube along the tangential direction of the heated tube under the top end sealing plate; the water inlet holes can be round, square or rectangular or other shapes, the sectional area is equivalent to a round hole with phi of 0.5-5 mm, and the number and the specification of the water inlet holes are set according to the evaporation task of the heated tube. Film type evaporating pipe of wall hole type film distributor, specification of evaporating pipe
Bore of water inlet hole
The number of water inlet holes n =3, and the total length of the evaporation tube l =3m.
As shown in fig. 23 to 26, in the plate-ring type film distributor, a ring-shaped water inlet is arranged on the top sealing plate in the direction of the tube wall of the heated tube, and the lower outlet ring gap is set to be 0.02 to 0.5mm according to the evaporation load of the heated tube. In this embodiment, the plate-ring type film distributor film type evaporating pipe has the specification
The width of the circular seam is 0.04mm, and the diameter of the circular seam
Total length of evaporation tube l =16m.
As shown in fig. 27 to 30, the spiral film distributor is configured such that a circular hole water inlet with a diameter of 0.5 to 10mm is set on a top end sealing plate according to the evaporation load of the heated tube, a spiral sprayer with a corresponding specification is arranged at the lower end of the circular hole, and top inlet water is sprayed onto the inner wall surface of the heated tube in an umbrella-shaped sector. In the embodiment, the specifications of the spiral film distributor film type evaporation tube and the evaporation tube
Bore of water inlet hole
The total length l =2.8m of the evaporating pipe, and the evaporating pipe is provided with pipe threads at the head and the tail.
The lower end of the film distributor 1 is additionally provided with a film homogenizing ring (film homogenizing device) which guides liquid drops which possibly splash to the outside of the wall surface due to high speed to the wall surface, so that the feed water flows downwards along the wall by an annular liquid film.
In the membrane steam generating tube, as shown in FIG. 10, the water supply is evaporated and transferred in a very thin water film flowing state, and the heat transfer coefficient is maximized to 30000-40000W/m 2· DEG C. The liquid phase vaporization surface area in the evaporation tube array exerts to the maximum value, which is 50 to 500 times of the transverse sectional area. Compared with the vaporization forms of water in the heated tubes of the steam pocket type and the straight-flow type boiler, the vaporization capacity of the heated tubes with the same area is about 250 to 2500 times of that of the heated tubes under the condition of the same vapor-liquid phase temperature difference; the feed water in the film-type steam generating pipe is directly vaporized to the vapor phase in the pipe in a liquid film state, and the phenomena of temperature difference rising, heat transfer rate reduction and first type heat transfer deterioration shown in the attached figure 7 and the attached figure 8 can not occur between the feed water and the pipe wall because the feed water is not vaporized in a boiling state. Moreover, the heat transfer coefficient of the film evaporation is not influenced by the change of vapor phase pressure, and the evaporation temperature of liquid in the pipe is only 0.5-2 ℃ higher than the temperature of saturated steam in contact with the liquid; in the membrane type evaporation tube, industrial soft water is continuously sprayed and supplied from the topThe membrane flow is far larger than the evaporation capacity in the tube, so the phenomena of liquid membrane breakage and cutoff cannot occur in the membrane type evaporation tube; the inner wall of the heated tube is protected by the liquid film, so that high and stable heat transfer rate vaporization is always maintained, and heat transfer deterioration phenomenon can not occur.
In the production of examples
1. The film evaporator for producing steam of 10t/h and steam pressure of 1.25MPa supplies heat for a layer combustion type chain furnace, and the structure is shown in attached figures 31 and 32; the flow rate of the water supply pump is 20t/h, the pressure difference between an inlet and an outlet is 0.2MPa, and the specification of a water supply header pipe
Specification of water supply branch pipe
Specification of steam outlet and water return main pipe
Specification of steam outlet backwater branch pipe
Pipe diameter
140 film-type evaporation tubes with the diameter of l =2.8m
l =2.5m film type evaporating tubes 759, total heat exchange area 330m 2 。
2. A film evaporator with the steam production of 20t/h and the steam pressure of 1.25MPa and a pulverized coal burner for supplying heat, and the structure of the film evaporator is shown in the attached figure 33; the flow rate of the water supply pump is 40t/h, the pressure difference between an inlet and an outlet is 0.3MPa, and the specification of a water supply header pipe
Specification of water supply branch pipe
Specification of steam outlet and water return main pipe
Specification of steam outlet backwater branch pipe
Pipe diameter
l =15m film type evaporation tubes 200 tubes in diameter
1155 film type evaporation tubes with the length of l =3m and the total heat exchange area of 1140m 2 。
3. A membrane evaporator with the steam production rate of 5t/h and the steam pressure of 1.25MPa and a fuel gas burner for supplying heat, and the structure of the membrane evaporator is shown in figure 34; the flow rate of the water supply pump is 10t/h, the pressure difference between an inlet and an outlet is 0.2MPa, and the specification of a water supply header pipe
Specification of water supply branch pipe
Specification of steam outlet and water return main pipe
Specification of steam outlet backwater branch pipe
Pipe diameter
150 film-type evaporation tubes with l =2.1m and tube diameter
420 film type evaporating tubes with l =1.8m and total heat exchange area of 155m 2 。
A film evaporator for producing steam of 10t/h and steam pressure of 1.25MPa, a gas burner for supplying heat, a water supply pump with flow of 10t/h, pressure difference of inlet and outlet of 0.2MPa and a water supply main pipe with specification
Specification of water supply branch pipe
Specification of steam outlet and water return main pipe
Specification of steam outlet backwater branch pipe
Pipe diameter
150 film type evaporating tubes with l =2.1m and tube diameters
420 film type evaporating tubes with l =1.8m and total heat exchange area of 155m 2 。
The membrane type steam generator only explains the principle, process and characteristics of a steam generating part in the system, does not influence the complete expression of the originality of the invention and compares the characteristics with corresponding functional parts in the existing boiler; other parts of the generator system, such as the whole structure, the fuel system, the combustion form, the air supply system, the tail gas treatment and the like, are the same as the corresponding known structures and systems in the existing boilers, and are not described again.
The evaporator structure shown in this patent is only illustrative for explaining the principle, process and characteristics thereof, and the actual production and manufacture are not limited to the above.
Claims (9)
1. A membrane steam generator, characterized by: mainly comprises a water supply pipeline, a membrane type evaporation pipe and a steam outlet water return pipeline,
the water supply pipeline comprises a water supply main pipe and water supply branch pipes, and water supply flows from the inlet end of the water supply main pipe to the tail ends of the water supply branch pipes; the steam outlet and water return pipeline comprises a steam outlet and water return main pipe and a steam outlet and water return branch pipe; one end of the membrane type evaporation tube is connected with a water supply header pipe and/or a water supply branch pipe, the other end of the membrane type evaporation tube is communicated with a steam outlet return water header pipe and/or a steam outlet return water branch pipe, water supply is distributed to the membrane type evaporation tube through the water supply header pipe or the water supply branch pipe, the water supply flows along the wall of the membrane type evaporation tube in a liquid film manner on the inner wall of the membrane type evaporation tube, the membrane type evaporation tube is heated, the liquid film is heated and directly vaporized into saturated steam, the steam flows into the steam outlet return header pipe or the steam outlet return water branch pipe along with the liquid film, and the unvaporized water supply is used as return water;
the steam or the mixture of the steam and partial backwater in the steam-outlet backwater branch pipe ascends to be output from the high-position steam outlet end and is converged into the steam-outlet backwater main pipe, and the mixture of the backwater or the mixture of the backwater and partial steam descends to be converged into the steam-outlet backwater main pipe from the low-position backwater end; the steam-outlet backwater main pipe is provided with a high-level steam outlet and a low-level backwater outlet, the steam in the steam-outlet backwater main pipe further ascends to be separated from backwater and is finally output by the steam outlet, the backwater further descends to be separated from the steam, and the backwater is finally output by the backwater outlet and is collected into a water supply circulating tank, and the circulating water supply is realized after the backwater is supplemented;
the membrane type evaporation tube consists of a top water distribution membrane section, a middle membrane type evaporation section and a lower vapor-liquid separation section,
the top water supply distribution film distribution section comprises a film distributor, the film distributor controls the water supply feeding direction and the feeding amount to directly form a film along the wall, or the combination film distributor redistributes the uniform film to ensure that the liquid film flows down along the wall contact heating surface in a uniform water film shape under the action of the initial flow velocity and the gravity;
in the middle membrane type evaporation section, the heated tube provides heat energy in a radiation and convection conduction mode at an external heat source, the liquid membrane continuously and alternately flows to ensure that the whole liquid membrane is uniformly heated, the feed water is evaporated and vaporized by a liquid phase after absorbing the heat energy, and the vaporized vapor phase steam is directly diffused to the central space of the heated tube;
the lower vapor-liquid separation section consists of a vapor phase outlet and a liquid phase outlet, the vapor phase outlet is arranged at the upper part of the liquid phase outlet, and the openings of the vapor phase outlet and the liquid phase outlet are in different directions; the water vapor is directed in a different direction than the unvaporized water to form a vapor stream and a liquid stream path.
2. The membrane steam generator of claim 1, wherein: the film distributor mainly has several forms: plate hole type film distributor, wall hole type film distributor, plate ring type film distributor and spiral film distributor; the plate hole type film distributor is characterized in that 2-20 water inlet holes are distributed downwards on a top end sealing plate along the tangential direction of a heated tube, the water inlet holes are round, square or rectangular, the sectional area of the water inlet holes is equivalent to a round hole with the diameter of 0.5-5 mm, and the number and the specification of the water inlet holes are set according to the evaporation task of the heated tube;
the wall hole type film distributor is characterized in that 2-20 water inlet holes are distributed downwards on the heated tube along the tangential direction of the heated tube below the top end sealing plate; the water inlet hole can be round, square or rectangular, and the cross section area and the shape of the water inlet hole are equal
The number and the specification of the water inlet holes are set according to the evaporation task of the heated tube;
the plate-ring type film distributor is characterized in that a ring-type water inlet is arranged on a top end sealing plate towards the pipe wall direction of a heated pipe, and a lower end outlet ring gap is set to be 0.02-0.5 mm according to the evaporation load of the heated pipe;
the spiral film distributor is provided with one on the top end sealing plate according to the evaporation load of the heated tube
The lower end of the round hole is provided with a spiral sprayer with corresponding specification, and the top water inlet is sprayed to the inner wall surface of the heated tube in an umbrella-shaped sector.
3. Membrane steam generator according to claim 1, characterized in that: the thickness of the water film on the inner wall of the film evaporation pipe is 0.1-0.3 mm.
4. Membrane steam generator according to claim 1, characterized in that: the membrane type evaporation tube is a special boiler steel tube with the specification of DN 20-DN 200, and the length-diameter ratio l/d is between 50 and 200; the length proportion of the top water distribution membrane section and the lower vapor-liquid separation section is 1-2% of the whole length.
5. The membrane steam generator of claim 1, wherein: the membrane evaporation tube and the system combination can be in a welded or threaded connection structure.
6. The membrane steam generator of claim 1, wherein: and the water supply circulation tank is externally connected with a water supply pipeline, return water and supply water are mixed in the water supply circulation tank and are conveyed to a water supply main pipe by a water supply pump, and the circulation is carried out.
7. The membrane steam generator according to claim 1 or 6, characterized in that: and a sewage discharge port is arranged on the return water pipeline, so that sewage discharge can be implemented according to the specific condition of the quality of the return water.
8. The membrane steam generator of claim 1, wherein: the pressure difference between the water supply and the saturated steam output by the steam-outlet return water main pipe is constant, the control range of the pressure difference is 0.1-0.4 MPa, and the water supply mass flow is controlled to be 2-5 times of the rated evaporation capacity.
9. The membrane steam generator of claim 8, wherein: the pressure difference between the feed water and the saturated steam is controlled between 0.2 and 0.3MPa.
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1815439A (en) * | 1926-01-04 | 1931-07-21 | La Mont Corp | Steam generator or the like |
| US5624531A (en) * | 1993-04-01 | 1997-04-29 | Tampella Power Oy | Evaporator operating on falling film principle |
| CN102171513A (en) * | 2008-09-09 | 2011-08-31 | 西门子公司 | Waste heat steam generator |
| CN103791479A (en) * | 2014-01-18 | 2014-05-14 | 西安交通大学 | Novel full tube panel type efficient oil and gas fired boiler |
| CN204756853U (en) * | 2015-05-11 | 2015-11-11 | 河北中然制药设备有限公司 | Pure steam generator |
| CN206656331U (en) * | 2017-03-10 | 2017-11-21 | 高峰 | A kind of membrane type steam generator |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU2016270569B2 (en) * | 2015-06-05 | 2021-10-28 | Advanced Technology Management Group LLC | Passive heat and mass transfer system |
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2017
- 2017-03-10 CN CN201710141957.1A patent/CN106838852B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1815439A (en) * | 1926-01-04 | 1931-07-21 | La Mont Corp | Steam generator or the like |
| US5624531A (en) * | 1993-04-01 | 1997-04-29 | Tampella Power Oy | Evaporator operating on falling film principle |
| CN102171513A (en) * | 2008-09-09 | 2011-08-31 | 西门子公司 | Waste heat steam generator |
| CN103791479A (en) * | 2014-01-18 | 2014-05-14 | 西安交通大学 | Novel full tube panel type efficient oil and gas fired boiler |
| CN204756853U (en) * | 2015-05-11 | 2015-11-11 | 河北中然制药设备有限公司 | Pure steam generator |
| CN206656331U (en) * | 2017-03-10 | 2017-11-21 | 高峰 | A kind of membrane type steam generator |
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