CN106838863B - Method for generating electricity by adopting low-calorific-value gas - Google Patents

Method for generating electricity by adopting low-calorific-value gas Download PDF

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CN106838863B
CN106838863B CN201611068564.4A CN201611068564A CN106838863B CN 106838863 B CN106838863 B CN 106838863B CN 201611068564 A CN201611068564 A CN 201611068564A CN 106838863 B CN106838863 B CN 106838863B
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gas
low
combustion
swirl
steam
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CN106838863A (en
Inventor
李社锋
艾庆文
陶玲
王文坦
郭华军
覃慧
徐秀英
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China City Environment Protection Engineering Ltd
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China City Environment Protection Engineering Ltd
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Priority to CN201611068564.4A priority Critical patent/CN106838863B/en
Publication of CN106838863A publication Critical patent/CN106838863A/en
Priority to RU2018145127A priority patent/RU2713554C1/en
Priority to PCT/CN2017/113102 priority patent/WO2018099346A1/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D15/00—Adaptations of machines or engines for special use; Combinations of engines with devices driven thereby
    • F01D15/10—Adaptations for driving, or combinations with, electric generators
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K11/00—Plants characterised by the engines being structurally combined with boilers or condensers
    • F01K11/02—Plants characterised by the engines being structurally combined with boilers or condensers the engines being turbines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B31/00—Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements of dispositions of combustion apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B31/00—Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements of dispositions of combustion apparatus
    • F22B31/08—Installation of heat-exchange apparatus or of means in boilers for heating air supplied for combustion
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22G—SUPERHEATING OF STEAM
    • F22G5/00—Controlling superheat temperature
    • F22G5/12—Controlling superheat temperature by attemperating the superheated steam, e.g. by injected water sprays
    • F22G5/123—Water injection apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22G—SUPERHEATING OF STEAM
    • F22G7/00—Steam superheaters characterised by location, arrangement, or disposition
    • F22G7/12—Steam superheaters characterised by location, arrangement, or disposition in flues
    • 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

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Combustion Of Fluid Fuel (AREA)

Abstract

The invention relates to a method for generating electricity by using low-heating-value gas, which comprises the following steps: (1) feeding low-calorific-value gas into a boiler for combustion, and exchanging heat between flue gas generated by combustion and a heat exchange surface in the boiler; generating high-temperature and ultrahigh-pressure superheated steam in the superheater, and sending the superheated steam to a high-pressure cylinder of the steam turbine for power generation; (2) steam coming out of the high-pressure cylinder enters a reheater, and reheated steam enters the low-pressure cylinder to generate power; (3) steam from the low-pressure cylinder enters the economizer after being condensed, and water from the economizer enters the steam pocket; (4) in the steam drum, water enters a water-cooled wall of the boiler, is heated into steam or a steam-water mixture and then returns to the steam drum; saturated steam enters the superheater. The low-heat value gas is sent into a low-heat value gas boiler to be combusted, high-temperature and ultrahigh-pressure superheated steam with the pressure of 13.7MPa and the temperature of 540 ℃ is generated in the superheater, and the efficiency of low-heat value gas power generation can be effectively improved by combining a mode of once reheating the steam.

Description

Method for generating electricity by adopting low-calorific-value gas
Technical Field
The invention belongs to the technical field of energy conservation and environmental protection, and particularly relates to a method for generating electricity by using low-calorific-value gas.
Background
China is a world-wide steel production country, and steel enterprises generate a large amount of byproduct gas in the smelting process, such as blast furnace gas, converter gas and coke oven gas, wherein the blast furnace gas has the characteristics of maximum yield, lowest heat value, toxicity, harm, flammability, explosiveness and the like. In recent years, the shortage of energy in China is prominent day by day, the environmental protection requirement is increased day by day, and blast furnace gas power generation is gradually applied to iron and steel enterprises, for example, a patent with the application number of 201320444475.0 discloses a full-combustion blast furnace gas boiler flue gas waste heat recycling system, and a patent with the application number of 201320446384.0 discloses a full-combustion blast furnace gas boiler flue gas waste heat deep recycling system, but the blast furnace gas power generation system only emphasizes on improving the recycling of flue gas side waste heat, and does not consider how to improve the thermal efficiency on the steam side; the patent with application number 201510239804.1 discloses a power generation method and system by burning metallurgical gas from a self-contained power plant, but it only provides a concept and method for generating power by gas of iron and steel enterprises, and has no related power generation system. Although blast furnace gas power generation is gradually applied to iron and steel enterprises, the problems of unstable boiler combustion, unreasonable arrangement of heating surfaces, low heat efficiency and the like still exist at present.
Disclosure of Invention
The embodiment of the invention relates to a method for generating power by using low-heating-value gas, which can at least solve part of defects in the prior art.
The embodiment of the invention relates to a method for generating power by using low-heating-value gas, which comprises the following steps:
step one, LHV is adjusted to 3100kJ/Nm3The low-heat value coal gas is sent into a low-heat value coal gas boiler for combustion, and the flue gas generated by combustion exchanges heat with the heat exchange surface in the low-heat value coal gas boiler; wherein, 13.7MPa of high-temperature ultrahigh-pressure superheated steam at 540 ℃ is generated in the superheater, and the superheated steam is sent to a high-pressure cylinder of a steam turbine for power generation;
secondly, steam coming out of a high-pressure cylinder of the steam turbine enters a reheater to be reheated, and reheated steam coming out of the reheater enters a low-pressure cylinder to be generated;
step three, condensing steam from the low-pressure cylinder into condensed water, then feeding the condensed water into an economizer, and feeding water from the economizer into a steam drum;
step four, in the steam drum, water obtained through steam-water separation enters a water-cooled wall of the low-heating value gas boiler, and is heated into steam or a steam-water mixture in the water-cooled wall and then returns to the steam drum; saturated steam obtained by steam-water separation enters a superheater, is heated to be superheated steam with high temperature and ultrahigh pressure of 13.7MPa and 540 ℃, and is sent to a high-pressure cylinder of a steam turbine to generate power;
and step five, circularly performing the step two to the step four.
As one embodiment, in the first step, low-calorific-value gas is fed into the low-calorific-value gas boiler through a burner structure for combustion;
the combustor structure comprises a first combustor layer, the first combustor layer comprises at least one first combustor arranged on the front wall of the combustor or comprises a plurality of first combustors arranged on the front wall and the rear wall of the combustor in an opposite-impact manner, each first combustor comprises an ignition gas pipe, a first gas pipe and a first combustion assisting gas pipe which are sequentially sleeved from inside to outside, and the first gas pipes are connected with low-calorific-value gas supply pipes;
the first gas pipe and the outlet end of the first combustion-supporting gas pipe are provided with swirl blade groups, each swirl blade of each swirl blade group is annularly arranged in the corresponding inner cavity of the gas pipe, and each swirl blade is arranged along the radial direction of the corresponding gas pipe.
Further, the burner structure further comprises a second burner layer, the second burner layer being located above the first burner layer; the second burner layer comprises at least one second burner arranged on the front wall of the combustion chamber or comprises a plurality of second burners oppositely arranged on the front wall and the rear wall of the combustion chamber; each second combustor all includes from inside to outside in proper order the second gas pipe, second help gas pipe, third gas pipe and the third that cup joint and help the gas pipe, and each tracheal exit end all is provided with whirl blade group, and each whirl blade ring of each whirl blade group arranges in the trachea inner chamber that corresponds, and each whirl blade all arranges along the tracheal radial of correspondence.
In one embodiment, an air preheater is arranged at the end of the flue of the low heating value gas boiler, and air preheated by the air preheater is used as combustion-supporting gas and sent to the first burner layer and/or the second burner layer for utilization.
As one embodiment, during the starting process of the generator set, the main steam pressure is controlled through a high-pressure bypass mechanism;
the high-pressure bypass mechanism comprises at least one high-pressure bypass which is arranged in parallel, each high-pressure bypass is provided with a high-bypass pressure valve, the temperature-reducing water inlet end of each high-bypass pressure valve is connected with a high-pressure water spraying pipeline, and each high-pressure water spraying pipeline is provided with a high-bypass water spraying adjusting valve and a high-bypass water spraying isolating valve;
the control method of each high-pressure bypass comprises the following steps: and calculating the required desuperheating water quantity according to the corresponding opening degree of the high-side pressure valve, the corresponding enthalpy values of the steam before and after the high-side pressure valve and the enthalpy value of the desuperheating water, and calculating the corresponding opening degree of the high-side water spraying adjusting valve according to the corresponding pressure before and after the high-side water spraying adjusting valve and the corresponding equal percentage characteristic curve of the high-side water spraying adjusting valve.
As one embodiment, a low-pressure bypass is connected to the outlet steam pipeline of the reheater, and the steam outlet end of the low-pressure bypass is connected to the outlet condensation pipeline of the low-pressure cylinder;
the low-pressure bypass is provided with a low bypass pressure valve, the entry end of the desuperheating water of the low bypass pressure valve is connected with a low-pressure water spraying pipeline, and the low-pressure water spraying pipeline is provided with a low bypass water spraying adjusting valve and a low bypass water spraying isolating valve.
As one embodiment, the method for controlling the low pressure bypass includes:
when the low side pressure valve is opened, the low side water spraying isolation valve is interlocked and opened;
and when the low side pressure valve is fully closed, the low side water spraying isolation valve is closed after a delay of 15 s.
As one embodiment, the method for controlling the low pressure bypass includes: and calculating the required desuperheating water quantity according to the opening degree of the low side pressure valve, the enthalpy values of steam before and after the low side pressure valve and the enthalpy value of desuperheating water, and calculating the opening degree of the low side water spraying adjusting valve according to the pressures before and after the low side water spraying adjusting valve and the equal percentage characteristic curve of the low side water spraying adjusting valve.
The embodiment of the invention at least has the following beneficial effects: the low-heat value gas is sent into a low-heat value gas boiler to be combusted, high-temperature and ultrahigh-pressure superheated steam with the pressure of 13.7MPa and the temperature of 540 ℃ is generated in the superheater, and the efficiency of low-heat value gas power generation can be effectively improved by combining a mode of once reheating the steam.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a burner provided in a first embodiment of the present invention;
FIG. 2 is a schematic view of the structure of the burner of FIG. 1 in the direction A;
FIG. 3 is a schematic structural view of a burner provided in a second embodiment of the present invention;
FIG. 4 is a schematic view of the structure of the burner of FIG. 3 in the direction A;
FIG. 5 is a schematic structural diagram of a low heating value gas power generation system provided by an embodiment of the invention;
fig. 6 is a schematic structural diagram of a high-pressure bypass and a low-pressure bypass according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example one
As shown in fig. 1-2, an embodiment of the present invention relates to a combustor, which includes an ignition air pipe 1111, a first fuel gas pipe 1112, and a first combustion-supporting air pipe 1113 that are sequentially sleeved from inside to outside, outlet ends of the first fuel gas pipe 1112 and the first combustion-supporting air pipe 1113 are respectively provided with a swirl blade set, each swirl blade of each swirl blade set is annularly arranged in an inner cavity of a corresponding air pipe, and each swirl blade is arranged along a radial direction of the corresponding air pipe. The ignition gas pipe 1111, the first gas pipe 1112 and the first combustion-supporting gas pipe 1113 are preferably coaxially sleeved; further included is an igniter 1116, the igniter 1116 being disposed in the first gas pipe 1112, and preferably being disposed near the ignition gas pipe 1111, and further preferably being disposed in parallel with the ignition gas pipe 1111, passing through swirl vanes disposed in the first gas pipe 1112 and being near the burner ports of the present burner; the igniter 1116 is preferably an automatic high-energy electronic igniter 1116, and the ignition operation is stable and reliable. The ignition gas pipe 1111 is connected with an ignition gas supply pipe, and the ignition gas can be coke oven gas, converter gas, natural gas, liquefied petroleum gas or fuel oil and the like; the first gas pipe 1112 is connected to a first gas supply pipe, and in this embodiment, the burner is preferably used for injection combustion of low-calorific-value gas, and the first gas supply pipe is preferably used for supplying low-calorific-value gas, and more preferably, the low-calorific-value gas is blast furnace gas; the first combustion-supporting gas pipe 1113 is connected to a combustion-supporting gas supply pipe, and the combustion-supporting gas generally adopts air.
By arranging the rotational flow blade group, on one hand, the strong mixing of the fuel gas and the combustion-supporting gas is facilitated, the continuous combustion of the fuel gas is ensured, and the combustion stability of the fuel gas is improved; on the other hand, a high-temperature flue gas backflow area can be formed in the combustion area, ignition and combustion of fuel gas are facilitated, and stability and combustion completeness of fuel gas combustion are improved. When the burner is used for burning low-heat value gas, the burning effect and efficiency of the low-heat value gas can be effectively improved.
As shown in fig. 1 and 2, the arrangement of each swirl vane group may adopt the following structure: the swirl blade group in the first gas pipe 1112 comprises a plurality of first gas swirl blades 1114, one end of each first gas swirl blade 1114 is fixed on the ignition gas pipe 1111, and the other end is fixed on the first gas pipe 1112; the swirl vane set in the first combustion-supporting gas pipe 1113 includes a plurality of first combustion-supporting gas swirl vanes 1115, and one end of each first combustion-supporting gas swirl vane 1115 is fixed on the first gas pipe 1112, and the other end is fixed on the first combustion-supporting gas pipe 1113. As shown in fig. 2, preferably, the number of first gas swirl vanes 1114 is less than the number of first combustion gas swirl vanes 1115; further, the length of the first gas swirling vanes 1114 is greater than that of the first combustion gas swirling vanes 1115 along the radial direction of the first gas pipe 1112, so as to ensure that the required tangential velocity and mixing effect of the two gas swirling flows are obtained.
In the present embodiment, it is preferable that each swirl blade group is provided with the following preferable configuration: a first annular hub is arranged at the outlet end of the first gas pipe 1112 and is positioned between the first gas pipe 1112 and the ignition gas pipe 1111; the swirl blade group in the first gas pipe 1112 includes a plurality of first swirl blades and a plurality of second swirl blades, each of the first swirl blades is fixed between the first annular hub and the ignition gas pipe 1111, and each of the second swirl blades is fixed between the first annular hub and the first gas pipe 1112. Wherein, preferably, the number of the first swirl vanes is less than the number of the second swirl vanes; further, in a radial direction of the first fuel gas pipe 1112, the length of the first swirl blades is greater than that of the second swirl blades, so that the flow rates of the two first fuel gas swirls are substantially equalized. The rotating direction of the first rotating flow blade and the rotating direction of the second rotating flow blade can be the same or different; the inclination angle of the first rotational flow blade and the inclination angle of the second rotational flow blade can be the same or different; the swirling direction of each first swirling flow blade is ensured to form a negative pressure area in the center of the ejected swirling flow so as to facilitate high-temperature flue gas backflow, and the high-temperature flue gas is used for heating first fuel gas and combustion-supporting gas so as to improve the combustion efficiency; the rotating direction of each first rotational flow blade is preferably opposite to that of the second rotational flow blade, or the rotating directions are the same but the inclination angles are different, so that the two first gas rotational flows can be intersected and collided, turbulence is conveniently formed through collision of the two first gas rotational flows, and the mixing effect of the first gas and the combustion-supporting gas is improved.
In order to further optimize the structure of the burner, a second annular hub is arranged at the outlet end of the first combustion-supporting gas pipe 1113, and the second annular hub is positioned between the first combustion-supporting gas pipe 1113 and the first gas pipe 1112; the swirl blade group in the first combustion-supporting gas pipe 1113 includes a plurality of third swirl blades, and each third swirl blade is fixed between the second annular hub and the first combustion gas pipe 1112. Swirl blades are not arranged between the second annular hub and the first combustion-supporting gas pipe 1113, namely, two air flows are formed at the outlet of the first combustion-supporting gas pipe 1113, wherein the outer jet flow is direct-current jet flow, and the inner jet flow is swirl flow, and the structure can prolong the overall jet flow air flow sprayed by the burner to a certain extent, but can weaken the rotation strength of the air flow and reduce a smoke backflow area; therefore, in this embodiment, it is further preferable that swirl vanes are provided between the second annular hub and the first combustion-supporting gas pipe 1113, that is, the swirl vane group in the first combustion-supporting gas pipe 1113 further includes a plurality of fourth swirl vanes, and each of the fourth swirl vanes is fixed between the second annular hub and the first combustion-supporting gas pipe 1113. Similarly, the rotating direction of the third rotating flow blade and the rotating direction of the fourth rotating flow blade can be the same or different; the inclination angle of the third swirl vane and the inclination angle of the fourth swirl vane can be the same or different; preferably, the third swirl vane is set to have a direction opposite to that of the fourth swirl vane, wherein the third swirl vane is preferably set to have a direction opposite to that of the second swirl vane in the first gas pipe 1112 and to have a swirl hedging, so that the mixing effect of the first gas and the combustion-supporting gas can be improved to a certain extent, and the fourth swirl vane group ensures that the overall jet flow ejected from the burner has a certain tangential velocity.
In order to obtain the required flame characteristics (such as direction, shape, rigidity, spreadability and the like), ensure the completeness of gas combustion, the stability of combustion and the like, the mixing effect of the first fuel gas and the combustion-supporting gas, the control of a flue gas backflow area and the proper tangential speed of each strand of rotational flow are considered, and the adjustment can be carried out according to the specific conditions in the following modes:
(1) adjusting the number ratio and the length ratio of the first swirl blade group and the second swirl blade group;
(2) adjusting the inclination angle of the first swirl vane and the second swirl vane;
(3) adjusting the number ratio and the length ratio of the third swirl vane group and the fourth swirl vane group;
(4) adjusting the inclination angle of the third swirl vane and the fourth swirl vane;
(5) adjusting the inclination angle of the second swirl vane and the third swirl vane;
(6) adjusting the number ratio and the length ratio of the second swirl blade group and the third swirl blade group;
under more conditions, the method is realized by combining more than two adjusting modes, so that the characteristics of strong flame rigidity, stable combustion, no flameout, no backfire, no flame drift and the like are achieved, and the characteristics of the gas with low calorific value are preferably that the gas and the air serving as combustion-supporting gas are uniformly mixed, and the gas can be completely combusted. In the embodiment, the volume ratio of the blast furnace gas to the combustion air can be adjusted within the range of 1: 5-1: 10.
According to the adjusting mode, the required parameters of each swirl vane group can be obtained through corresponding calculation according to the characteristics of on-site low-heat-value coal gas before the combustor is installed, and the corresponding combustor is selected for installation. More preferably, the method comprises the following steps: in the combustion process, the inclination angle of each swirl vane can be adjusted in real time to obtain the required combustion condition; two ends of each rotational flow blade can be rotatably arranged on the corresponding mounting parts respectively, and according to the characteristics of the working environment of the combustor, high-temperature resistant lubricating grease or high-temperature resistant lubricating oil can be adopted for lubrication between the rotating shafts at two ends of each rotational flow blade and the corresponding bearings; each rotational flow blade of each rotational flow blade group is preferably adjusted by synchronous rotation through a synchronous transmission mechanism, the synchronous transmission mechanism can be a common synchronous transmission structure such as a gear meshing transmission mode, and the specific structure is not described herein again.
In addition, a monitoring mechanism can be further arranged for monitoring the working condition of the combustor in real time so as to ensure the safe and stable operation of the combustor. The monitoring mechanism mainly comprises a flame monitor, a pressure monitor and a temperature monitor, and a flame observation hole 1117 and a hole 1118 for the flame monitor can be arranged at one end of the burner, which is far away from the spray head.
Example two
As shown in fig. 3-4, the embodiment of the present invention relates to a burner, which includes a second gas pipe 1121, a second combustion-supporting gas pipe 1122, a third gas pipe 1123, and a third combustion-supporting gas pipe 1124 which are sequentially sleeved from inside to outside, an outlet end of each gas pipe is provided with a swirl vane set, each swirl vane of each swirl vane set is annularly arranged in an inner cavity of the corresponding gas pipe, and each swirl vane is arranged along a radial direction of the corresponding gas pipe.
By arranging the rotational flow blade group, on one hand, the strong mixing of the fuel gas and the combustion-supporting gas is facilitated, the continuous combustion of the fuel gas is ensured, and the combustion stability of the fuel gas is improved; on the other hand, a high-temperature flue gas backflow area can be formed in the combustion area, ignition and combustion of fuel gas are facilitated, and stability and combustion completeness of fuel gas combustion are improved.
The second gas pipe 1121, the second combustion-supporting gas pipe 1122, the third gas pipe 1123, and the third combustion-supporting gas pipe 1124 are preferably coaxially coupled. The second gas pipe 1121 is connected to a second gas supply pipe, the third gas pipe 1123 is connected to a third gas supply pipe, and the second combustion-supporting gas pipe 1122 and the third combustion-supporting gas pipe 1124 are both connected to a combustion-supporting gas supply pipe, and the combustion-supporting gas generally uses air. By adopting the structure of double gas pipes, the two gas pipes adopt the same gas mode, namely the second gas supply pipe and the third gas supply pipe are connected with the same gas source, so that the effect of mixing gas and combustion-supporting gas can be effectively improved, and the combustion efficiency is improved; the two gas pipes adopt different gas modes, namely the second gas supply pipe and the third gas supply pipe are connected with different gas sources, so that different proportions of different gases can be realized, combustion optimization is carried out, and the combustion efficiency is improved; meanwhile, when the quality of one gas fluctuates or is in a supply interruption state, the sustainability of combustion is guaranteed due to the existence of the other gas, the combustion stability is improved, and the combustion safety is guaranteed. In this embodiment, the second gas supply pipe preferably supplies high calorific value gas such as converter gas; the third gas supply pipe is preferably used for supplying low-heating value gas, and further preferably, the low-heating value gas is blast furnace gas; the high calorific value gas and the low calorific value gas are mixed and combusted, so that on one hand, the fuel ratio can be adjusted according to the rich allowance of converter gas and blast furnace gas of the steel plant; on the other hand, the combustion effect and efficiency can be improved by adjusting the proportion of the converter gas and the blast furnace gas, so that the combustion effect of the low-calorific-value gas is effectively improved, and the improvement of the quality of the flue gas is facilitated. Furthermore, the system for generating power by adopting the low-calorific-value gas can realize the stable combustion of the pure-combustion blast furnace gas to generate power.
As shown in fig. 3 and 4, the arrangement of each swirl blade group may adopt the following structure: the swirl vane group in the second gas pipe 1121 includes a plurality of second gas swirl vanes 1126, one end of each second gas swirl vane 1126 is fixed to a support hub 1125 provided in the second gas pipe 1121, and the other end is fixed to the second gas pipe 1121; the swirl vane group in the second combustion-supporting air pipe 1122 includes a plurality of second combustion-supporting air swirl vanes 1127, one end of each second combustion-supporting air swirl vane 1127 is fixed on the second combustion-supporting air pipe 1121, and the other end is fixed on the second combustion-supporting air pipe 1122; the swirl blade group in the third gas pipe 1123 comprises a plurality of third gas swirl blades 1128, one end of each third gas swirl blade 1128 is fixed on the second combustion-supporting gas pipe 1122, and the other end is fixed on the third gas pipe 1123; the swirl vane group in the third combustion-supporting air pipe 1124 includes a plurality of third combustion-supporting air swirl vanes 1129, and one end of each third combustion-supporting air swirl vane 1129 is fixed to the third gas pipe 1123, and the other end is fixed to the third combustion-supporting air pipe 1124.
As shown in fig. 4, preferably, the number of second gas swirl vanes 1126 is less than the number of second combustion gas swirl vanes 1127; further, the length of the second gas swirl blade 1126 is greater than that of the second combustion gas swirl blade 1127 along the radial direction of the second gas pipe 1121, so as to ensure that the required tangential velocity and mixing effect of the two gas swirls are obtained. The number of the third gas swirl vanes 1128 is less than the number of the third combustion gas swirl vanes 1129; further, the length of the third gas swirl vanes 1128 is greater than the length of the third combustion gas swirl vanes 1129 in the radial direction of the third gas pipe 1123, so as to ensure that the required tangential velocity and mixing effect of the two gas swirls are obtained.
In the present embodiment, it is preferable that each swirl blade group is provided with the following preferable configuration: a supporting hub 1125 and a third annular hub are arranged at the outlet end of the second fuel gas pipe 1121, and the supporting hub 1125, the third annular hub and the second fuel gas pipe 1121 are sequentially sleeved from inside to outside; the swirl blade group in the second fuel gas pipe 1121 includes a plurality of fifth swirl blades and a plurality of sixth swirl blades, each of the fifth swirl blades is fixed between the third annular hub and the support hub 1125, and each of the sixth swirl blades is fixed between the third annular hub and the second fuel gas pipe 1121. Wherein, preferably, the number of the fifth swirl blades is less than the number of the sixth swirl blades; further, in a radial direction of the second gas pipe 1121, the length of the fifth swirl blade is greater than that of the sixth swirl blade, so that the flow rates of the two second gas swirls are substantially equalized. The rotating direction of the fifth rotating flow blade and the rotating direction of the sixth rotating flow blade can be the same or different; the inclination angle of the fifth swirl vane may be the same as or different from that of the sixth swirl vane; the rotating direction of each fifth rotational flow blade is ensured to form a negative pressure area in the center of the rotational flow ejected by the fifth rotational flow blade, so that high-temperature flue gas can flow back, and the high-temperature flue gas is used for heating second fuel gas and combustion-supporting gas, so that the combustion efficiency is improved; the rotating direction of each fifth rotational flow blade is preferably opposite to that of the sixth rotational flow blade, or the rotating directions are the same but the inclination angles are different, so that the two first gas rotational flows can be intersected and collided, turbulence is conveniently formed through collision of the two second gas rotational flows, and the mixing effect of the second gas and the combustion-supporting gas is improved.
In one embodiment, a fourth annular hub is disposed at an outlet end of the second oxidant gas pipe 1122, and the fourth annular hub is located between the second oxidant gas pipe 1122 and the second fuel gas pipe 1121; the swirl blade set in the second combustion-supporting air tube 1122 includes a plurality of seventh swirl blades and a plurality of eighth swirl blades, each of the seventh swirl blades is fixed between the fourth annular hub and the second combustion-supporting air tube 1121, and each of the eighth swirl blades is fixed between the fourth annular hub and the second combustion-supporting air tube 1122. The rotating direction of the seventh rotating flow blade and the rotating direction of the eighth rotating flow blade can be the same or different; the inclination angle of the seventh swirl vane and the inclination angle of the eighth swirl vane can be the same or different; preferably, the seventh swirl blades are arranged in a direction opposite to the eighth swirl blades, wherein the seventh swirl blades are preferably arranged in a direction opposite to the sixth swirl blades in the second gas pipe 1121 and in swirl hedging, so that the mixing effect of the second gas and the combustion-supporting gas can be improved to some extent, and the eighth swirl blades are preferably arranged in a direction opposite to the swirl blades in the third gas pipe 1123 and in swirl hedging, so that the mixing effect of the third gas and the combustion-supporting gas can be improved to some extent.
As an example, a fifth annular hub is arranged at the outlet end of the third combustion-supporting gas pipe 1124, and the fifth annular hub is positioned between the third combustion-supporting gas pipe 1124 and the third gas pipe 1123; the swirl blade group in the third combustion-supporting gas pipe 1124 includes a plurality of ninth swirl blades, and each of the ninth swirl blades is fixed between the fifth annular hub and the third gas pipe 1123. Swirl blades can not be arranged between the fifth annular hub and the third combustion-supporting air pipe 1124, namely, two air flows are formed at the outlet of the third combustion-supporting air pipe 1124, wherein the outer jet flow is direct-current jet flow, and the inner jet flow is swirl flow, and the structure can prolong the air flow of the whole jet flow sprayed by the burner to a certain extent, but can weaken the rotation strength of the air flow and reduce a smoke backflow area; therefore, in this embodiment, it is further preferable that swirl vanes are provided between the fifth annular hub and the third combustion-supporting air pipe 1124, that is, the swirl vane group in the third combustion-supporting air pipe 1124 further includes a plurality of tenth swirl vanes, and each tenth swirl vane is fixed between the fifth annular hub and the third combustion-supporting air pipe 1124. Similarly, the direction of rotation of the ninth swirl blade and the direction of rotation of the tenth swirl blade may be the same or different; the inclination angle of the ninth swirl vane may be the same as or different from that of the tenth swirl vane.
In order to obtain the required flame characteristics (such as direction, shape, rigidity, spreadability and the like), ensure the completeness of gas combustion, the stability of combustion and the like, the mixing effect of each fuel gas and combustion-supporting gas, the control of a flue gas backflow area and the proper tangential speed of each strand of rotational flow are considered, and the adjustment can be carried out in the following modes according to specific conditions:
(1) adjusting the number ratio and the length ratio of the fifth swirl blade group and the sixth swirl blade group;
(2) adjusting the inclination angle of the fifth swirl vane and the sixth swirl vane;
(3) adjusting the number ratio and the length ratio of the seventh swirl vane group to the eighth swirl vane group;
(4) adjusting the inclination angle of the seventh swirl vane and the eighth swirl vane;
(5) adjusting the inclination angle of the sixth swirl vane and the seventh swirl vane;
(6) adjusting the number and the blade length of the swirl blade group in the third gas pipe 1123;
(7) adjusting the number ratio and the length ratio of the swirl blade group and the eighth swirl blade group in the third gas pipe 1123;
(8) adjusting the number ratio and the length ratio of the ninth swirl blade group and the tenth swirl blade group;
under more conditions, the method is realized by combining more than two adjusting modes, so that the characteristics of strong flame rigidity, stable combustion, no flameout, no backfire, no flame drift and the like are achieved, aiming at the gas characteristics of low-calorific-value gas, the high-calorific-value gas and air serving as combustion-supporting gas are ensured to be uniformly mixed, and the gas can be completely combusted. In the embodiment, the volume ratio of the blast furnace gas, the converter gas and the combustion air can be adjusted within the range of 1:1: 7-1: 3: 12.
The adjusting mode can obtain the required parameters of each swirl vane group through corresponding calculation according to the characteristics of on-site low-heat value coal gas and converter coal gas before the installation of the combustor, and the corresponding combustor is selected for installation. More preferably, the method comprises the following steps: in the combustion process, the inclination angle of each swirl vane can be adjusted in real time to obtain the required combustion condition; two ends of each rotational flow blade can be rotatably arranged on the corresponding mounting parts respectively, and according to the characteristics of the working environment of the combustor, high-temperature resistant lubricating grease or high-temperature resistant lubricating oil can be adopted for lubrication between the rotating shafts at two ends of each rotational flow blade and the corresponding bearings; each rotational flow blade of each rotational flow blade group is preferably adjusted by synchronous rotation through a synchronous transmission mechanism, the synchronous transmission mechanism can be a common synchronous transmission structure such as a gear meshing transmission mode, and the specific structure is not described herein again.
In addition, a monitoring mechanism can be further arranged for monitoring the working condition of the combustor in real time so as to ensure the safe and stable operation of the combustor. The monitoring mechanism mainly comprises a flame monitor, a pressure monitor and a temperature monitor, and a flame observation hole and a hole for the flame monitor can be arranged at one end of the burner, which is far away from the spray head.
EXAMPLE III
The embodiment of the invention relates to a burner structure 11, which is used for being arranged on a combustion chamber of a boiler 1 and comprises a first burner layer, wherein the first burner layer comprises at least one first burner arranged on the front wall of the combustion chamber or a plurality of first burners oppositely arranged on the front wall and the rear wall of the combustion chamber, and each first burner comprises an ignition gas pipe 1111, a first gas pipe 1112 and a first combustion-supporting gas pipe 1113 which are sequentially sleeved from inside to outside.
Further comprising a second burner layer, the second burner layer positioned above the first burner layer; the second burner layer comprises at least one second burner arranged on the front wall of the combustion chamber or comprises a plurality of second burners oppositely arranged on the front wall and the rear wall of the combustion chamber; each of the second burners includes a second gas pipe 1121, a second combustion-supporting gas pipe 1122, a third gas pipe 1123, and a third combustion-supporting gas pipe 1124 which are sequentially sleeved from inside to outside.
Preferably, the burners provided in the first embodiment are used as the first burners, and the burners provided in the second embodiment are used as the second burners; the specific structure of each first burner and each second burner will not be described herein.
Example four
Referring to fig. 5, the embodiment of the invention relates to a low-calorific-value gas boiler 1, which comprises a boiler body, wherein the boiler body comprises a combustion chamber, a horizontal flue and a vertical flue, a superheater 13 is arranged in the horizontal flue, and a reheater 14 and an economizer 15 are sequentially arranged in the vertical flue from top to bottom. The outlet end of the superheater 13 can be communicated with a steam inlet of an external steam utilization mechanism, the inlet end of the reheater 14 is communicated with a steam outlet end of the steam utilization mechanism, the outlet end of the reheater 14 is communicated with a steam inlet of the steam utilization mechanism, and the inlet end of the economizer 15 can be connected with a condensing mechanism connected to an exhaust steam outlet end of the steam utilization mechanism. Further, the inner wall of the combustion chamber is at least partially a water-cooled wall 17; preferably, the inner walls of the combustion chamber are all water cooled walls 17. Further, the low heating value gas boiler 1 is also provided with a steam drum 12, a steam-water separation device is arranged in the steam drum 12, the steam drum 12 is provided with a water outlet, a water inlet, a steam-water mixture inlet and a gas outlet, the inlet end of each water-cooled wall 17 is communicated with the water outlet, the outlet end of each water-cooled wall 17 is communicated with the steam-water mixture inlet, the water inlet is communicated with the outlet end of the economizer 15, and the gas outlet is communicated with the inlet end of the superheater 13.
The steam utilization mechanism is generally a power generation mechanism, and includes a steam turbine 2 and a generator 3.
The steam-water medium involved in the low-calorific-value gas boiler 1 has the following trend:
low-heat value gas is combusted in the low-heat value gas boiler 1, and flue gas generated by combustion exchanges heat with a heat exchange surface in the low-heat value gas boiler 1; wherein, the superheated steam is generated in the superheater 13 and is sent to the steam utilization mechanism for utilization;
the steam from the steam utilization mechanism enters the reheater 14 to be reheated, and the reheated steam from the reheater 14 enters the steam utilization mechanism to be utilized;
after dead steam from the steam utilization mechanism is condensed into condensed water by the condensing mechanism, the condensed water enters the economizer 15, and water from the economizer 15 enters the steam drum 12;
in the steam drum 12, water obtained through steam-water separation enters a water-cooled wall 17 of the low-heat value gas boiler 1, is heated into steam or a steam-water mixture in the water-cooled wall 17, and then returns to the steam drum 12; saturated steam obtained through steam-water separation enters the superheater 13, is heated into superheated steam, and is sent to a steam utilization mechanism for utilization.
Further preferably, an air preheater 16 is arranged in the vertical flue, and the air preheater 16 is located below the economizer 15; the air preheated by the air preheater 16 can be utilized as an oxidant gas in the burner of the low heating value gas boiler 1.
EXAMPLE five
Referring to fig. 5, the embodiment of the present invention relates to a low calorific value gas boiler 1, the basic structure of which is the same as that of the low calorific value gas boiler 1 of the fourth embodiment, and a burner structure 11 is disposed on a combustion chamber thereof, and the burner structure 11 preferably adopts the burner structure 11 provided in the third embodiment.
Through the burner structure 11, stable combustion of low-heat value gas can be ensured, and the boiler 1 is suitable for an LHV (low heat value) of 3100kJ/Nm by combining the arrangement mode of the heating surface of the boiler 1 and the single reheating of the steam medium3The power generation of the blast furnace gas can reach the high-temperature and ultrahigh-pressure parameters of 13.7MPa/540 ℃/540 ℃, and the power generation efficiency reaches over 36 percent.
EXAMPLE six
Referring to fig. 5, an embodiment of the present invention relates to a low-calorific-value gas power generation system, including a boiler 1 and a steam turbine 2, where the boiler 1 is preferably the low-calorific-value gas boiler 1 provided in the fourth embodiment or the fifth embodiment, and the specific structure of the boiler 1 is not described herein again; the steam utilizing mechanism according to the fourth embodiment employs a power generating mechanism. The steam turbine 2 includes a high pressure cylinder 21 and a low pressure cylinder 22, a steam inlet of the high pressure cylinder 21 is communicated with an outlet end of the superheater 13 through a first steam line, a steam outlet of the high pressure cylinder 21 is communicated with an inlet end of the reheater 14 through a second steam line, and a steam inlet of the low pressure cylinder 22 is communicated with an outlet end of the reheater 14 through a third steam line.
Further, as shown in fig. 5, a steam outlet of the low pressure cylinder 22 is connected to a condensation pipeline, the condensation pipeline is provided with a condenser 61 and a condensate pump 62, and an outlet end of the condensation pipeline is communicated with an inlet end of the economizer 15. The condenser 61, the condensate pump 62, the low-pressure heater 63 and the high-pressure heater 66 are sequentially arranged along the flow direction of the condensate water. A deaerator 64 may further be provided on the condensation line, the deaerator 64 preferably being arranged between the low-pressure heater 63 and the high-pressure heater 66; a feed water pump 65 may further be provided on the condenser line, which feed water pump 65 is preferably arranged between the deaerator 64 and the high-pressure heater 66. In the above structure, the condenser 61 may be a horizontal or vertical structure, preferably a condenser 61 using a double-flow, single-casing, which may be elastically supported; the low-pressure heater 63 may be one-stage, two-stage or more than two-stage; the high pressure heater 66 may be one-stage, two-stage, or more than two-stage; the deaerator 64 described above should be able to meet system slip pressure operating conditions.
The structure of the system is further optimized, as shown in fig. 5 and fig. 6, the low heating value gas power generation system also comprises a high-pressure bypass mechanism and a low-pressure bypass mechanism; the steam inlet end of the high-pressure bypass mechanism is connected to the first steam pipeline, and the steam outlet end of the high-pressure bypass mechanism is connected to the second steam pipeline; the steam inlet end of the low-pressure bypass mechanism is connected to the third steam pipeline in a bypassing mode, the steam outlet end of the low-pressure bypass mechanism is connected to the condensing pipeline in a bypassing mode, and a bypassing point is located between the condenser 61 and the steam outlet of the low-pressure cylinder 22. As shown in fig. 6, the high-pressure bypass mechanism includes at least one high-pressure bypass 4 arranged in parallel, each high-pressure bypass 4 is provided with a high-bypass pressure valve 41, a desuperheating water inlet end of each high-bypass pressure valve 41 is connected to a high-pressure water spraying pipeline, and each high-pressure water spraying pipeline is provided with a high-bypass water spraying regulating valve 42 and a high-bypass water spraying isolation valve 43; in this embodiment, it is preferable to include 4 high-pressure bypasses 4, wherein the maximum flow rate of each high-pressure bypass valve 41 is 25% of the main steam flow rate of the boiler 1 under the condition of full-open power (VWO) of the regulating valve of the steam turbine 2. The low-pressure bypass mechanism comprises at least one low-pressure bypass 5 which is arranged in parallel, each low-pressure bypass 5 is provided with a low bypass pressure valve 51, the temperature-reducing water inlet end of each low bypass pressure valve 51 is connected with a low-pressure water spraying pipeline, and each low-pressure water spraying pipeline is provided with a low bypass water spraying adjusting valve 52 and a low bypass water spraying isolation valve 53; in this embodiment, only one low pressure bypass 5 may be used, and the number of low pressure bypasses 5 may be increased as appropriate.
The high-pressure bypass mechanism and the low-pressure bypass mechanism have the following functions: (1) the cold, hot and warm starting performance of the unit is improved. The start-up time is shortened, a steam runner is formed, and the limitation of the start-up on the fuel amount of the boiler 1 is reduced. The thermal stress of the unit is reduced, particularly the thermal state starting is realized, the service life of the unit is prolonged, and the working medium is recycled. (2) Cooling and protecting the reheater 14. (3) The boiler 1 is protected against overpressure. And (4) load shedding of the boiler 1 can be realized when the turbine 2 is stopped. (5) The boiler can be stopped without stopping the boiler, and the lowest stable combustion load of the boiler 1 can be maintained. Specifically, the method comprises the following steps:
the main function of the high-pressure bypass mechanism is to control the main steam pressure by adjusting the opening of the high-bypass pressure valve 41 in the starting process of the unit so as to meet the requirements of each stage of the starting of the unit on the main steam pressure. The high pressure bypass mechanism has three control modes: the unit is ignited, heated and boosted by the boiler 1 until the unit is operated to full load with load, and the high-pressure bypass mechanism is subjected to three control stages of a valve position mode, a constant pressure mode and a sliding pressure mode.
The control method of each of the high-pressure bypasses 4 includes:
(1) the required amount of desuperheating water is calculated according to the corresponding opening degree of the high side pressure valve 41, the corresponding enthalpy values of the steam before and after the high side pressure valve 41 and the enthalpy value of the desuperheating water, and then the corresponding opening degree of the high side water spraying regulating valve 42 is calculated according to the corresponding pressure before and after the high side water spraying regulating valve 42 and the corresponding equal percentage characteristic curve of the high side water spraying regulating valve 42.
(2) The set value of the temperature regulation target value of the high-side bypass to the steam is adjustable, the upper limit is calculated and set according to a thermodynamic system, and the lower limit is the superheat degree of the steam +30 ℃ behind the high-side pressure valve 41.
(3) The high-pressure bypass temperature-reducing water stop valve is also linked with the high-pressure bypass pressure valve 41. This requires precise steam temperature control in all operating modes, requiring the controller to be well matched to the various operating conditions of the high pressure bypass 4 (low load, quick open at high load, etc.), and precise temperature control in all operating conditions, which is critical for protecting valves and pipes that are subjected to high pressures.
(4) The high-pressure side pressure valve 41 has the safety protection function of the superheater 13, can be quickly opened, and has 2 quick opening valve modes: rapidly opening the high bypass pressure valve 41 through DCS control logic, wherein the opening time is less than or equal to 10 s; the loop opening valve is safely and quickly opened through the console operating button and the local pressure switch, namely when the operating button is pressed down or the pressure switch acts, the loop is safely and quickly opened to open the high bypass pressure valve 41, and the opening time is less than or equal to 2 s.
(5) The high-pressure bypass mechanism has a quick-opening function, when the deviation of the main steam pressure and a set value is greater than a set deviation value, the steam turbine trips, and an operator sends a quick-opening instruction.
The control method of each of the low pressure bypasses 5 includes:
(1) when the corresponding low side pressure valve 51 is opened (the opening degree is more than 3 percent), the corresponding low side water spraying isolation valve 53 is opened in an interlocking way; and when the corresponding low side pressure valve 51 is fully closed (the opening degree is less than 2.5 percent), closing the low side water spraying isolation valve 53 for 15 seconds. The low side spray isolation valve 53 may also be switched on and off according to an operator's command.
(2) When the low side pressure valve is automatically switched on and the low side pressure valve 51 is quickly opened or closed, the low side water spray regulating valve 52 is automatically switched to automatic control.
(3) The required amount of desuperheating water is calculated according to the corresponding opening degree of the low side pressure valve 51, the corresponding enthalpy values of the steam before and after the low pressure bypass 5 and the enthalpy value of the desuperheating water, and then the corresponding opening degree of the low side water spraying adjusting valve 52 is calculated according to the corresponding pressure before and after the low side water spraying adjusting valve 52 and the corresponding equal percentage characteristic curve of the low side water spraying adjusting valve 52.
(4) The low-voltage bypass mechanism has a quick opening and closing function. When the high-pressure bypass 4 is opened quickly, the linkage low-pressure bypass 5 is opened quickly. When at least one of the following conditions occurs, the low-pressure bypass 5 quick-closing mechanism acts: the condenser 61 has low vacuum, the condenser 61 has high temperature, the condenser 61 has high water level and the temperature-reduced water pressure is low.
EXAMPLE seven
The embodiment of the invention relates to a method for generating power by using low-heating-value gas, which comprises the following steps:
step one, LHV is adjusted to 3100kJ/Nm3The low-heat value gas is sent into a low-heat value gas boiler 1 to be combusted, and the flue gas generated by combustion exchanges heat with a heat exchange surface in the low-heat value gas boiler 1; wherein, 13.7MPa of high-temperature and ultrahigh-pressure superheated steam at 540 ℃ is generated in the superheater 13, and the superheated steam is sent to a high-pressure cylinder 21 of the steam turbine 2 for power generation;
step two, the steam from the high pressure cylinder 21 of the steam turbine 2 enters the reheater 14 to be reheated, and the reheated steam from the reheater 14 enters the low pressure cylinder 22 to be generated;
step three, after the steam from the low-pressure cylinder 22 is condensed into condensed water, the condensed water enters the economizer 15, and the water from the economizer 15 enters the steam drum 12;
step four, in the steam drum 12, water obtained through steam-water separation enters a water-cooled wall 17 of the low-heat value gas boiler 1, is heated into steam or a steam-water mixture in the water-cooled wall 17, and then returns to the steam drum 12; saturated steam obtained by steam-water separation enters the superheater 13, is heated to high-temperature and ultrahigh-pressure superheated steam of 13.7MPa and 540 ℃, and is sent to a high-pressure cylinder 21 of the steam turbine 2 to generate power;
and step five, circularly performing the step two to the step four.
Wherein, the low heating value gas boiler 1 provided in the fourth embodiment or the fifth embodiment is adopted as the low heating value gas boiler 1.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (6)

1. The method for generating power by using low-heating-value gas is characterized by comprising the following steps of:
step one, LHV is adjusted to 3100kJ/Nm3The low-heat value coal gas is sent into a low-heat value coal gas boiler for combustion, and the flue gas generated by combustion exchanges heat with the heat exchange surface in the low-heat value coal gas boiler; wherein, 13.7MPa of high-temperature ultrahigh-pressure superheated steam at 540 ℃ is generated in the superheater, and the superheated steam is sent to a high-pressure cylinder of a steam turbine for power generation;
secondly, steam coming out of a high-pressure cylinder of the steam turbine enters a reheater to be reheated, and reheated steam coming out of the reheater enters a low-pressure cylinder to be generated;
step three, condensing steam from the low-pressure cylinder into condensed water, then feeding the condensed water into an economizer, and feeding water from the economizer into a steam drum;
step four, in the steam drum, water obtained through steam-water separation enters a water-cooled wall of the low-heating value gas boiler, and is heated into steam or a steam-water mixture in the water-cooled wall and then returns to the steam drum; saturated steam obtained by steam-water separation enters a superheater, is heated to be superheated steam with high temperature and ultrahigh pressure of 13.7MPa and 540 ℃, and is sent to a high-pressure cylinder of a steam turbine to generate power;
step five, circularly performing the step two to the step four;
in the first step, low-calorific-value gas is fed into the low-calorific-value gas boiler through a burner structure to be combusted;
the combustor structure is arranged on a combustion chamber of a boiler and comprises a first combustor layer and a second combustor layer, wherein the first combustor layer comprises at least one first combustor arranged on a front wall of the combustion chamber or a plurality of first combustors arranged on the front wall and a rear wall of the combustion chamber in an opposite impact manner, each first combustor comprises an ignition gas pipe, a first gas pipe and a first combustion assisting gas pipe which are sequentially sleeved from inside to outside, and the first gas pipe is connected with a low-calorific-value gas supply pipe; the outlet ends of the first gas pipe and the first combustion-supporting gas pipe are provided with rotational flow blade groups;
a first annular hub is arranged at the outlet end of the first gas pipe and is positioned between the first gas pipe and the ignition gas pipe; the swirl blade group in the first gas pipe comprises a plurality of first swirl blades and a plurality of second swirl blades, each first swirl blade is fixed between the first annular hub and the ignition gas pipe, and each second swirl blade is fixed between the first annular hub and the first gas pipe; wherein the number of the first swirl vanes is less than the number of the second swirl vanes; the length of the first rotational flow blade is greater than that of the second rotational flow blade along the radial direction of the first fuel gas pipe, so that the flow of the two first fuel gas rotational flows is balanced; the rotating direction of each first rotational flow blade ensures that a negative pressure area can be formed in the center of the rotational flow ejected by the first rotational flow blade, so that high-temperature flue gas can flow back, and the first fuel gas and the combustion-supporting gas are heated by the high-temperature flue gas; the rotating direction of each first rotational flow blade is opposite to that of each second rotational flow blade, or the rotating directions are the same but the inclination angles are different, so that the two first gas rotational flows can be intersected and collided;
a second annular hub is arranged at the outlet end of the first combustion-supporting gas pipe and is positioned between the first combustion-supporting gas pipe and the first gas pipe; the rotational flow blade group in the first combustion-supporting gas pipe comprises a plurality of third rotational flow blades and a plurality of fourth rotational flow blades, each third rotational flow blade is fixed between the second annular hub and the first gas pipe, each fourth rotational flow blade is fixed between the second annular hub and the first combustion-supporting gas pipe, the rotational direction of each third rotational flow blade is opposite to that of each fourth rotational flow blade, the rotational direction of each third rotational flow blade is opposite to that of each second rotational flow blade in the first gas pipe, rotational flows are oppositely flushed, and the fourth rotational flow blade group ensures that integral jet flow sprayed by the combustor has a certain tangential speed;
the second burner layer is located above the first burner layer; the second burner layer comprises at least one second burner arranged on the front wall of the combustion chamber or comprises a plurality of second burners oppositely arranged on the front wall and the rear wall of the combustion chamber;
each second combustor comprises a second gas pipe, a second combustion-supporting gas pipe, a third gas pipe and a third combustion-supporting gas pipe which are sequentially sleeved from inside to outside, the outlet end of each gas pipe is provided with a rotational flow blade group, each rotational flow blade of each rotational flow blade group is annularly arranged in the inner cavity of the corresponding gas pipe, each rotational flow blade is arranged along the radial direction of the corresponding gas pipe, the second gas pipe supplies converter gas, and the third gas pipe supplies blast furnace gas; moreover, the volume ratio of the blast furnace gas, the converter gas and the combustion air is adjusted within the range of 1:1: 7-1: 3: 12;
a support hub and a third annular hub are arranged at the outlet end of the second fuel gas pipe, and the support hub, the third annular hub and the second fuel gas pipe are sequentially sleeved from inside to outside; the swirl blade group in the second gas pipe comprises a plurality of fifth swirl blades and a plurality of sixth swirl blades, each fifth swirl blade is fixed between the third annular hub and the support hub, and each sixth swirl blade is fixed between the third annular hub and the second gas pipe; wherein the number of the fifth swirl vanes is less than the number of the sixth swirl vanes; the length of the fifth swirl blade is greater than that of the sixth swirl blade along the radial direction of the second fuel gas pipe, so that the flow rates of the two second fuel gas swirls are balanced; the rotating direction of each fifth rotational flow blade ensures that a negative pressure area can be formed in the center of the rotational flow ejected by the fifth rotational flow blade, so that high-temperature flue gas can flow back, and the second fuel gas and the combustion-supporting gas are heated by the high-temperature flue gas; the rotating direction of each fifth rotational flow blade is opposite to that of the sixth rotational flow blade, or the rotating directions are the same but the inclination angles are different, so that the two first gas rotational flows can be intersected and collided;
a fourth annular hub is arranged at the outlet end of the second combustion-supporting air pipe and is positioned between the second combustion-supporting air pipe and the second fuel air pipe; the swirl blade group in the second combustion-supporting air pipe comprises a plurality of seventh swirl blades and a plurality of eighth swirl blades, each seventh swirl blade is fixed between the fourth annular hub and the second combustion-supporting air pipe, and each eighth swirl blade is fixed between the fourth annular hub and the second combustion-supporting air pipe; the rotating direction of the seventh rotational flow blade is opposite to that of the eighth rotational flow blade, wherein the rotating direction of the seventh rotational flow blade is opposite to that of the sixth rotational flow blade in the second gas pipe and the rotational flows oppositely rush, so that the mixing effect of the second gas and the combustion-supporting gas is improved, and the rotating direction of the eighth rotational flow blade is opposite to that of the rotational flow blade group in the third gas pipe and the rotational flows oppositely rush, so that the mixing effect of the third gas and the combustion-supporting gas is improved;
a fifth annular hub is arranged at the outlet end of the third combustion-supporting gas pipe and is positioned between the third combustion-supporting gas pipe and the third gas pipe; the swirl blade group in the third combustion-supporting gas pipe comprises a plurality of ninth swirl blades, and each ninth swirl blade is fixed between the fifth annular hub and the third gas pipe;
through adopting the swirl vane regulation mode more than two kinds with improve flame rigidity and burning stable, do not take off the fire, do not temper, flame do not float, wherein, swirl vane regulation mode includes: adjusting the number ratio and the length ratio of the fifth swirl blade group and the sixth swirl blade group; adjusting the inclination angle of the fifth swirl vane and the sixth swirl vane; adjusting the number ratio and the length ratio of the seventh swirl vane group to the eighth swirl vane group; adjusting the inclination angle of the seventh swirl vane and the eighth swirl vane; adjusting the inclination angle of the sixth swirl vane and the seventh swirl vane; adjusting the number and the length of the swirl vane groups in the third gas pipe; and adjusting the number ratio and the length ratio of the swirl blade group in the third gas pipe to the eighth swirl blade group.
2. The method of generating electricity using a low heating value gas as claimed in claim 1, wherein: and an air preheater is arranged at the tail end of a flue of the low-heat-value gas boiler, and air preheated by the air preheater is used as combustion-supporting gas and sent to the first combustor layer and/or the second combustor layer for utilization.
3. The method of generating electricity using a low heating value gas as claimed in claim 1, wherein: in the starting process of the generator set, the main steam pressure is controlled through the high-pressure bypass mechanism;
the high-pressure bypass mechanism comprises at least one high-pressure bypass which is arranged in parallel, each high-pressure bypass is provided with a high-bypass pressure valve, the temperature-reducing water inlet end of each high-bypass pressure valve is connected with a high-pressure water spraying pipeline, and each high-pressure water spraying pipeline is provided with a high-bypass water spraying adjusting valve and a high-bypass water spraying isolating valve;
the control method of each high-pressure bypass comprises the following steps: and calculating the required desuperheating water quantity according to the corresponding opening degree of the high-side pressure valve, the corresponding enthalpy values of the steam before and after the high-side pressure valve and the enthalpy value of the desuperheating water, and calculating the corresponding opening degree of the high-side water spraying adjusting valve according to the corresponding pressure before and after the high-side water spraying adjusting valve and the corresponding equal percentage characteristic curve of the high-side water spraying adjusting valve.
4. A method of generating electricity using a low heating value gas as claimed in claim 3, wherein: a low-pressure bypass is connected to the outlet steam pipeline of the reheater, and the steam outlet end of the low-pressure bypass is connected to the outlet condensation pipeline of the low-pressure cylinder;
the low-pressure bypass is provided with a low bypass pressure valve, the entry end of the desuperheating water of the low bypass pressure valve is connected with a low-pressure water spraying pipeline, and the low-pressure water spraying pipeline is provided with a low bypass water spraying adjusting valve and a low bypass water spraying isolating valve.
5. The method for generating power using a low heating value gas according to claim 4, wherein the method for controlling the low pressure bypass comprises:
when the low side pressure valve is opened, the low side water spraying isolation valve is interlocked and opened;
and when the low side pressure valve is fully closed, the low side water spraying isolation valve is closed after a delay of 15 s.
6. The method for generating power using a low heating value gas according to claim 4, wherein the method for controlling the low pressure bypass comprises: and calculating the required desuperheating water quantity according to the opening degree of the low side pressure valve, the enthalpy values of steam before and after the low side pressure valve and the enthalpy value of desuperheating water, and calculating the opening degree of the low side water spraying adjusting valve according to the pressures before and after the low side water spraying adjusting valve and the equal percentage characteristic curve of the low side water spraying adjusting valve.
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