CN108697978B - Method for operating a desulfurization system - Google Patents
Method for operating a desulfurization system Download PDFInfo
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- CN108697978B CN108697978B CN201780006853.8A CN201780006853A CN108697978B CN 108697978 B CN108697978 B CN 108697978B CN 201780006853 A CN201780006853 A CN 201780006853A CN 108697978 B CN108697978 B CN 108697978B
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/48—Sulfur compounds
- B01D53/50—Sulfur oxides
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Abstract
The invention provides a technique for forming a moving layer of a desulfurizing agent in a desulfurizing tower, and enabling stable operation of desulfurization efficiency when flue gas is desulfurized by contacting the flue gas with the moving layer. Gypsum (CaSO) which has used a desulfurizing agent after a desulfurizing treatment using a desulfurizing agent comprising hydrated lime, an active source supplying material for supplying silica and alumina, such as lime, gypsum, for use in a desulfurizing treatment as a novel desulfurizing agent4) A source. Then, the hardness of the desulfurizing agent is measured, and when it is evaluated that the hardness is not more than a predetermined value, the used desulfurizing agent is increased by a predetermined amount, and the slaked lime is decreased by the amount corresponding to the increase.
Description
Technical Field
The present invention relates to a desulfurization method for flue gas, and more particularly to a method for desulfurizing flue gas by forming a moving bed by descending and moving a desulfurizing agent in a desulfurization tower so that the flue gas contacts the moving bed in a cross-flow manner.
Background
Exhaust gas discharged from thermal power plants, industrial or household boilers, cement furnaces, and coke ovens, which use coal or heavy oil containing sulfur compounds and nitrogen compounds as fuel, contains many air pollutants such as sulfur oxides (SOx), nitrogen oxides (NOx), and dust, and becomes an environmental pollution source such as acid rain, photochemical smog, and PM 2.5.
As an apparatus for removing SOx in flue gas from air pollutants, for example, a moving bed dry desulfurization method is known in which a granular cleaning agent (desulfurizing agent) having desulfurization performance is moved down in a desulfurization tower to form a moving bed, and a cross flow is formed by making a flow of flue gas orthogonal to the moving bed to desulfurize the flue gas, as described in patent document 1. Patent document 1 describes that slaked lime (ca (oh))2) Coal ash and gypsum (CaSO)4) The resultant mixture was mixed with water, and then the mixture was steam-cured in a heated state, and the obtained cured product was extrusion-molded, and the molded product was dried to be used as a desulfurizing agent.
In such a desulfurization method, a used desulfurizing agent used for desulfurization in a desulfurizing tower is used as a gypsum source in producing a new desulfurizing agent (patent documents 1 and 2). One of the reasons why the used desulfurizing agent can be effectively used as a gypsum source is that SiO is eluted from coal ash in the production of the desulfurizing agent as a precursor thereof2Or Al2O3Etc., and they exist in an active state.
The moving bed dry desulfurization method has advantages such as not lowering the temperature of flue gas and not using a large amount of water, as compared with the wet flue gas desulfurization method, but also has a case where the desulfurization efficiency is unstable and it is difficult to perform a stable operation, and therefore this case is one of the main reasons why the popularization and development of this technology cannot be promoted.
Documents of the prior art
Patent document
Patent document 1: japanese laid-open patent publication No. 4-354538
Patent document 2: japanese laid-open patent publication No. 4-59044
Disclosure of Invention
Problems to be solved by the invention
The present invention was made under such circumstances, and provides a technique for forming a moving bed of a desulfurizing agent in a desulfurizing tower, and enabling operation with stable desulfurization efficiency when flue gas is desulfurized by bringing the flue gas into contact with the moving bed.
Means for solving the problems
The present inventors have found that when a desulfurizing agent comprising hydrated lime, an active source supplying material for supplying silica and alumina, and gypsum is used as a gypsum source for a new desulfurizing agent after desulfurization treatment, the composition of the desulfurizing agent used affects the instability of desulfurization efficiency.
Specifically, when the hardness of the desulfurizing agent is lowered, the desulfurizing agent is pulverized in the desulfurizing tower due to abrasion between the desulfurizing agents. Even if pulverized, the desulfurization performance does not change, and the pressure difference is reduced at a portion where the pulverized ratio is small as compared with a portion where the pulverized ratio is large, and therefore, the flue gas is concentrated at a portion where the pressure difference is low, and therefore, the flue gas flows unevenly in the desulfurization tower, causing drift. As a result, the desulfurization reaction becomes difficult to proceed at a portion where the pulverization ratio is large, and the desulfurization efficiency is lowered as a whole.
In order to maintain the desulfurization efficiency, it is conceivable that the supply amount per unit time of the desulfurizing agent, i.e., the amount of calcium as a sulfur-fixing substance is increased relative to the amount of sulfur in the flue gas, is increased for the desulfurizing tower. This is suitable from the viewpoint of maintaining desulfurization efficiency, but the used desulfurizing agent contains a large amount of unreacted lime components, and as a result, the gypsum content in the desulfurizing agent decreases, the formation of silicates and aluminates is suppressed, and the hardness of the desulfurizing agent decreases. The present inventors have determined that the desulfurization efficiency of the desulfurization tower cannot be maintained at a predetermined value when such a correspondence is repeated.
In the step of producing the desulfurizing agent, a step of curing a mixture containing at least slaked lime and the active source supplying material in a heated state in a steam atmosphere (hydrothermal treatment step) is performed. When this hydrothermal treatment step is performed, a desulfurization active material (mainly calcium silicates) is generated, and a material for expressing hardness (mainly calcium aluminates) is generated. Therefore, in order to increase the hardness of the desulfurizing agent, it is conceivable to lengthen the hydrothermal treatment time. However, since the amount of calcium in the desulfurizing agent is determined, if more calcium than necessary is consumed in order to maintain the hardness, the generation of calcium silicate, which is a desulfurization active material, is inhibited, with the result that the desulfurization performance of the desulfurizing agent is lowered.
The present inventors have obtained the following findings based on the results of these consideration studies: the hardness of the desulfurizing agent is monitored, and when the hardness is lower than a predetermined value, the amount of the used desulfurizing agent is increased to increase the amount of gypsum, and on the other hand, the amount of slaked lime as another raw material is decreased, whereby stabilization of the desulfurization efficiency can be achieved.
The present invention provides a method for operating a dry desulfurization apparatus for desulfurizing flue gas containing sulfur oxides, the method comprising the steps of:
a step of mixing a used desulfurizing agent, which is obtained by using a desulfurizing agent containing hydrated lime, an active source supply material for supplying silica and alumina, and gypsum for desulfurization treatment, with the used desulfurizing agent, hydrated lime, and an active source supply material for supplying silica and alumina to produce a desulfurizing agent;
a step of supplying the desulfurizing agent produced in the step from the upper part of the desulfurizing tower and forming a moving layer composed of the desulfurizing agent moving downward;
a step of bringing the flue gas into contact with the moving bed in a cross-flow manner;
a step of taking out the used desulfurizing agent from the lower part of the desulfurizing tower;
a first raw material ratio changing step of, when the hardness of the desulfurizing agent is measured and evaluated to be equal to or less than a predetermined value, decreasing the slaked lime by a predetermined amount and increasing the used desulfurizing agent by a predetermined amount,
the step of producing the desulfurizing agent includes a step of curing a mixture containing at least slaked lime and the active source supplying material in a heated state in a steam atmosphere.
Effects of the invention
The hardness of a desulfurizing agent is measured when the desulfurizing agent containing hydrated lime, an active source supply material for supplying silica and alumina, and gypsum is used as a gypsum source for a new desulfurizing agent after desulfurization treatment. When the hardness is evaluated to be equal to or less than the predetermined value, the used desulfurizing agent is increased by a predetermined amount, and the amount of the hydrated lime is decreased by the amount of the increase. Therefore, the hardness of the desulfurizing agent can be maintained at a predetermined value or more, and thus, the operation can be performed with stable desulfurization efficiency.
Drawings
Fig. 1 is a schematic diagram showing the overall configuration of a desulfurization system used in the method for operating a desulfurization system according to the embodiment of the present invention.
FIG. 2 is a schematic explanatory view showing a desulfurizing agent production facility included in the desulfurization system.
FIG. 3A is a flow chart illustrating a method of operating a desulfurization system in accordance with an embodiment of the present invention.
FIG. 3B is a flow chart illustrating a method of operating a desulfurization system in accordance with an embodiment of the present invention.
Detailed Description
Fig. 1 shows the overall configuration of a desulfurization system used in the method for operating a desulfurization system according to an embodiment of the present invention. The desulfurization system includes a manufacturing apparatus 1 of a desulfurizing agent and a desulfurization device 2.
As shown in FIG. 2, the desulfurization agent production facility 1 includes a storage unit 31 for storing a used desulfurization agent described later, a storage unit 32 for storing slaked lime, and a storage unit 33 for storing coal ash. Discharge valves 31a to 33a are provided at the lower ends of the reservoirs 31 to 33, respectively, and meters 31b to 33b are provided below the discharge valves 31a to 33a, respectively. Reference numeral 34 denotes a kneader 34, and the kneader 34 kneads the used desulfurizing agent, the slaked lime, and the coal ash measured by the respective meters 31b to 33 b.
The raw materials of the desulfurizing agent, hydrated lime and coal ash have been used, and SiO is dissolved from the coal ash2And AlO2Etc. in the presence of slaked lime (Ca (OH)2) And (CaSO)4) Water and compounds are formed, and the high-activity desulfurizing agent is obtained. In this example, coal ash is used as the active source supply material for supplying silica and alumina, but the active source supply material is not limited to coal ash, and may be, for example, volcanic ash, white sand ash, pyroxene, bentonite, diatomaceous earth, blast furnace slag, or the like. The kneaded material kneaded by the kneader 34 is stored in the storage section 35, and then supplied to the kneader 36 via the discharge valve 35a, and water is added to the kneader 36 to knead the water and the raw material mixed powder. The kneaded material kneaded by the kneader 36 is supplied to an extruder 37. The pellets molded by the extruder 37 are sent to the steam curing apparatus 4.
In the steam curing apparatus 4, the granular material is heated to, for example, 90 to 120 ℃ and, for example, 95 ℃, and then left in a steam atmosphere for, for example, 5 to 15 hours and, for example, about 10 hours, to perform steam curing (hydrothermal treatment). Specifically, the steam curing apparatus is configured such that a belt conveyor is disposed in a treatment chamber from which steam is ejected from a bottom surface, and granular materials are placed on the belt conveyor and moved in the treatment chamber.
When the granular material is steam cured, it is preferable to carry out the steam curing so that the granular material cannot be permeated by the steam. Specific configurations for realizing this method include an example in which a rubber belt is used as the conveyor belt, and an example in which a dense SUS-made mesh belt that is almost impermeable to water vapor is used as the conveyor belt. As another example, a case having an opening on the top surface can be given. As the case, for example, a SUS rectangular parallelepiped case or a case having a trapezoidal cross section can be used.
Further, even when a mesh body permeable to water vapor is used as a placement member for placing the granular particles, the granular particles may be highly stacked to such an extent that water vapor cannot permeate therethrough, without being arranged so that the placement member is visible from above while the granular particles are dispersed. In order to prevent condensed water droplets from falling onto the granular particles from the top surface of a partition member (enclosure member for forming a curing chamber) for partitioning the atmosphere in which steam curing of the granular particles is performed and the external atmosphere, it is preferable to form a structure in which the top surface is inclined, for example, a triangular roof structure. In order to suppress the drop of condensed water droplets, it is preferable that no beam is provided in the curing chamber as much as possible.
In the steam curing of the granular materials, in order to increase the amount of steam contacting the granular materials per unit time, it is considered that a mesh body or the like through which steam can pass is preferable as a placement portion for placing the granular materials. On the other hand, in order to increase (increase) the hardness of the granular bodies, it is necessary to have a structure in which the aluminate as a structural maintaining component is firmly structured, but when a mesh body or the like is used, excessive moisture exists in the granular bodies, and as a result, the excessive moisture inhibits the bonding between aluminate molecules, and the hardness of the granular bodies is lowered. The present inventors have obtained this finding and carried out steam curing by placing the granular material on a member such as a sheet material configured to be impermeable to steam.
Returning to fig. 2, the steam-cured granules are dried by a dryer 41, and granules having a predetermined particle size or less are removed by, for example, a vibration sieve, not shown, and granules having a particle size of, for example, 3mm to 10mm are used as a desulfurizing agent. The desulfurizing agent is sent to the storage section 21 of the desulfurization apparatus 2 by a conveying means such as a belt conveyor.
Next, the desulfurization device 2 will be described with reference to fig. 1. The desulfurization apparatus 2 includes a first desulfurization tower (reaction tower) 5 and a second desulfurization tower (reaction tower) 6 arranged at a distance from each other in the front-rear direction. The first and second desulfurizing towers 5 and 6 are each formed in a rectangular cylindrical shape flat in the front-rear direction, and have an inverted triangular prism-shaped bottom surface and an inclined surface on the bottom surface. In this example, the dimension (thickness dimension) in the front-rear direction of the second desulfurization tower 6 located on the rear side (the downstream side as viewed in the flow direction of the flue gas) is set larger than the thickness dimension of the first desulfurization tower 5 located on the front side. The relationship between the thickness dimensions of the desulfurizing towers 5 and 6 is not limited to this example, and may be the same thickness dimension, for example.
The desulfurizing agent discharged from the lower portion of the second desulfurizing tower 6 through the discharge valve 61 is conveyed to the upper portion of the first desulfurizing tower 5 by a conveying means such as a conveying belt combined with a belt conveyor, and is supplied into the first desulfurizing tower 5. In the first desulfurization tower 5, too, the same behavior as in the second desulfurization tower 6 is exhibited, and in a state of being filled with the desulfurizing agent, the desulfurizing agent descends at a descending speed corresponding to the opening/closing degree of the discharge valve 51 at the bottom by its own weight. Therefore, a mobile layer of the desulfurizing agent is formed in the first desulfurizing tower 5.
Both side surfaces (front and rear surfaces) of the first desulfurization tower 5 and the second desulfurization tower 6 are configured such that the flue gas passes therethrough, but the desulfurizing agent does not overflow or break down. Specifically, for example, in the side surfaces of the desulfurizing towers 5 and 6, a plurality of inclined plates are arranged in the vertical direction so as to extend in the horizontal direction from one end to the other end (from one end to the other end when viewed in the direction perpendicular to the paper plane) over the entire lateral width, the inclined plates are provided upward, and the gap between the inclined plates adjacent to each other in the vertical direction is a flow port for the flue gas. The structure of the side surface is not limited to the structure in which the flow port is formed in the horizontally long slit, and may be a structure in which a plurality of holes are formed in a side surface in a dispersed manner.
A flow path member (guide path member) 7 forming a flow path of the flue gas is provided around the desulfurizing towers 5 and 6 so that the flue gas flows in from one side surface (front surface) of the first desulfurizing tower 5 and flows out from the other side surface (rear surface), and then flows in from one side surface of the second desulfurizing tower 6 and flows out from the other side surface. Reference numeral 71 denotes an inlet port for the flue gas, and is connected to a flow path for the flue gas sent from a flue gas source such as a thermal power plant. Reference numeral 72 denotes an outlet port, which is connected to, for example, a flow path for feeding flue gas to a denitration device in the subsequent stage.
Therefore, the flue gas flows orthogonally to the moving layer of the desulfurizing agent formed inside each of the desulfurizing towers 5 and 6, that is, forms a cross flow. At this time, SOx in the flue gas reacts with calcium hydroxide in the desulfurizing agent to be fixed in the form of calcium sulfate. The used desulfurizing agent discharged from the first desulfurizing tower 5 is stored in the storage section 73 and then transported to the desulfurizing agent production facility 1 through the discharge valve 73 a. In the desulfurizing agent production facility 1, the used desulfurizing agent is pulverized and stored in the storage section 31.
Next, the operation of the above embodiment will be described. Although the explanation is repeated, first, in the desulfurizing agent production facility 1, the desulfurizing agent used is mixed with slaked lime and coal ash, and the mixture is steam-cured (hydrothermal treatment) to produce the desulfurizing agent. The desulfurizing agent moves in the second desulfurizing tower 6 and the first desulfurizing tower 5 corresponding to the latter stage and the former stage, respectively, in descending flows in order as viewed from the flow direction of the flue gas, and the desulfurization treatment of the flue gas is performed. The velocity of the flue gas in the desulfurizing towers 5 and 6 is set to 0.1 to 1.0 m/sec, for example. The total residence time of the desulfurizing agents in the desulfurizing towers 5 and 6 is set to 25 to 35 days, for example. The velocity of the flue gas is not limited to the above-described value because it can be determined according to the length of the desulfurization tower in the gas flow direction. The total residence time of the desulfurizing agent is determined by the height of the desulfurizing tower, and is not limited to the above-mentioned values.
Thus, when the desulfurization treatment is performed, calcium hydroxide in the desulfurizing agent becomes calcium sulfate (gypsum), and the gypsum source that has used the desulfurizing agent as a new desulfurizing agent is reused. Further, at the time of starting up the desulfurization system, as a gypsum source of the desulfurizing agent, for example, a used desulfurizing agent used in other desulfurization systems may be obtained, or, for example, hemihydrate gypsum may be used.
In the present embodiment, the desulfurization efficiency of the flue gas, the hardness of the desulfurizing agent, and the sulfur content of the used desulfurizing agent were measured and monitored.
The desulfurization efficiency is measured by measuring the concentration C of sulfur oxides in the flue gas before flowing into the first desulfurization tower 51And the concentration C of sulfur oxides in the flue gas flowing out of the second desulfurization tower 62The desulfurization efficiency { (C) was determined1－C2)/C1Is carried out by 100. Examples of the measurement method include absorptiometry using infrared absorption, ion chromatography, and precipitation measurement.
The measurement of the predetermined value described in the flow described below is performed by the following measuring instrument and method. For the determination of the desulfurization efficiency and the sulfur content of the used desulfurizing agent, an infrared type automatic concentration meter distributed in the market is also used. The hardness of the desulfurizing agent was measured by using the relative strength of the material measured by a log cabin hardness tester.
The method of operating the desulfurization system according to the embodiment of the present invention will be described with reference to the flowcharts of fig. 3A and 3B. At present, the operation of the desulfurization system is started, and gypsum, which is a raw material of the desulfurizing agent, is operated using the used desulfurizing agent used in the other desulfurization system, and a new desulfurizing agent is produced using the used desulfurizing agent generated by the system after the residence time of each of the desulfurizing agents in the second desulfurization tower 6 and the first desulfurization tower 5. In this example, the normal operation conditions include 35 mass% of slaked lime, 30 mass% of coal ash, 35 mass% of used desulfurizing agent, 10kg or more of hardness of the desulfurizing agent, 10.5 hours of hydrothermal treatment time, and 13 mass% or more of sulfur content of the used desulfurizing agent. The ratio of the raw materials is a ratio of the whole solid content.
First, as described above, the desulfurization efficiency of the flue gas, the hardness of the desulfurizing agent, and the sulfur content of the used desulfurizing agent were determined at predetermined time points. In this example, regarding the desulfurization efficiency of the flue gas, the flue gas before flowing into the first desulfurization tower 5 was continuously measured by an infrared spectrometerConcentration C of sulfur oxides in the body1And the concentration C of sulfur oxides in the flue gas flowing out of the second desulfurization tower 62The desulfurization efficiency was continuously determined. The time point at which the desulfurization efficiency of the flue gas is determined is not limited to being continuously determined, and may be intermittently determined, for example, every 5 hours.
Further, the hardness of the desulfurizing agent and the sulfur content of the used desulfurizing agent may be measured, for example, on monday, wednesday, and friday (3 days/week) in one week, and may be measured only on tuesday and thursday for 2 days in one week, or may be measured at a time point such as once a day.
Then, it is examined whether or not the desulfurization efficiency (abbreviated as "a" for convenience of explanation in fig. 3A) is equal to or less than a predetermined value, for example, equal to or less than 95% for one week (step S1). If yes in step S1, that is, if the desulfurization efficiency is 95% or less for one week, it is examined whether or not the measured value of the hardness of the desulfurizing agent is 10kg or less, for example, or less, for one week (step S2). The time point of measurement of the hardness is, for example, a time point before the steel sheet is manufactured by the manufacturing facility 1 and carried into the storage section 21 of the desulfurizer 2, but is not limited to this time point.
If "yes" in step S2, that is, if the measured value of the hardness of the desulfurizing agent continues for one week and is 10kg or less, then, for example, in this example, the discharging valve 31a of the manufacturing apparatus 1 is rapidly prepared to increase the amount of the raw material of the desulfurizing agent, that is, the used desulfurizing agent, and the preparing discharging valve 32a reduces the slaked lime (step S3). The amount of increase in the amount of the used desulfurizing agent is changed by the predetermined raw material ratio, i.e., the mass ratio of gypsum, slaked lime, and coal ash. For example, the amount of the used desulfurizing agent is increased by 5% by mass and the amount of the hydrated lime is decreased by 5% by mass. The amount of decrease in the slaked lime is an amount corresponding to the amount (amount) of increase in the desulfurizing agent that has been used, and is not limited to making the two values coincide as long as the two values do not differ extremely. For example, even in the case of increasing the used desulfurizing agent by 5 mass% and decreasing the slaked lime by 5.1%, the effect of the present invention can be obtained. Thus, by increasing the mixing ratio of the used desulfurizing agent, the mass ratio of gypsum increases, and as a result, the hardness of the desulfurizing agent increases.
After increasing the amount of the used desulfurizing agent in step S3, it is judged whether or not the desulfurization efficiency is 95% or less and the hardness of the desulfurizing agent is 10kg or less after four weeks, for example (step S4). In fig. 3A, the description events of step S4 and step S7 described later are not included in a frame and are described separately. The period of "four weeks" in step S4 corresponds to a time longer than the time from the time when the raw material ratio was changed in step S3 to the time when the changed desulfurizing agent is discharged from the first desulfurizing tower 5 via the second desulfurizing tower 6 in this example. That is, step S4 is a step of examining the influence of the change in the raw material ratio on the performance of the desulfurizing agent after the desulfurizing treatment is completed.
If yes in step S4, for example, if the desulfurization efficiency is 95% or less, the hardness of the desulfurizing agent is 10kg or less, or both the desulfurization efficiency and the hardness of the desulfurizing agent are predetermined values or less, it is determined that no effect is observed in the increase in the amount of the desulfurizing agent used, and the steam curing time (hydrothermal treatment time) of the steam curing device 4 of the manufacturing facility 1 is increased by, for example, 15% from the set time (step S5). The extension time is determined by the raw material ratio and the set time, and is not limited to 15%.
On the other hand, in the case of no at step S4, that is, in the case where the desulfurization efficiency exceeds 95% and the hardness of the desulfurizing agent exceeds 10kg, the raw material ratio changed at step S3 is returned to the raw material ratio before the change (step S6).
When the procedure returns to the next step of step S5, the hydrothermal treatment time is extended in step S5, and the same determination as in step S4 is made (step S7). That is, after the hydrothermal treatment time is extended in step S7, it is determined after four weeks whether the desulfurization efficiency is 95% or less and the hardness of the desulfurizing agent is 10kg or less. Step S7 is a step for examining the performance of the desulfurizing agent after the desulfurization treatment of the desulfurizing agent has been completed after the hydrothermal treatment time has been prolonged. If the judgment at step S7 is "no", the routine proceeds to step S6 already described, and if the judgment at step S7 is "yes", it is considered that an unexpected event is caused, and therefore, a detailed check of the desulfurization system is performed (step S8). Further, when the determination of step S7 is yes, the process may return to step S7, and when step S7 is yes again, the detailed check may be performed again (step S8).
Subsequently, returning to step S1, if the determination of step S1 is "no", that is, if the desulfurization efficiency exceeds 95% at any time during the measurement of one week, it is examined whether the measured value of the hardness of the desulfurizing agent is equal to or less than a predetermined value, for example, equal to or less than 10kg, for one week (step S9). It is difficult to imagine the case where the desulfurization efficiency exceeds 95% only once in one measurement of one week, and it is actually considered that the desulfurization efficiency is 95% or less for one week or that the desulfurization efficiency exceeds 95% for one week (or approximately one week).
In the case where "yes" is the step S9, the flow proceeds to the already described step S3, where the used desulfurizing agent is increased as described above. As is clear from steps S1, S2, S9, and S3, in the present embodiment, the used desulfurizing agent is added to the raw material of the desulfurizing agent as long as the hardness of the desulfurizing agent is 10kg or less for one week, regardless of whether the desulfurization efficiency is 95% or less for one week.
On the other hand, in the case of no in step S9, it is examined whether or not the sulfur content of the used desulfurizing agent (abbreviated as "B" in the frame) is equal to or less than the predetermined value in all measurements for one week, that is, whether or not the sulfur content is equal to or less than the predetermined value for one week (step S10). The predetermined value of the sulfur content is determined by the raw material ratio of the desulfurizing agent, etc., but here, 13 mass% is exemplified as the predetermined value. Further, if "no" in step S10, that is, in the case where the sulfur content of the used desulfurizing agent is within one week but once at all exceeds the prescribed value, the process returns to step S1. In this case, if "no", it is actually considered that the sulfur content exceeds the predetermined value for one week or substantially for one week.
If the determination in step S10 is yes, the supply amount of the desulfurizing agent per unit time to the first desulfurizing tower 5 and the second desulfurizing tower 6 may be larger than a predetermined value. That is, the residence time of the desulfurizing agent in the first desulfurizing tower 5 and the second desulfurizing tower 6 may be shorter than a predetermined value. Therefore, the supply amount and the discharge amount of the desulfurizing agent per unit time in the first desulfurizing tower 5 and the discharge amount of the desulfurizing agent per unit time in the second desulfurizing tower 6 are examined, and whether or not the supply amount and the discharge amount are maintained at the respective predetermined values is determined (step S11).
If yes at step S11, the process proceeds to step S11a in fig. 3B. When the supply amount of the desulfurizing agent per unit time is a predetermined value, the performance of the desulfurizing agent is highly likely to be lowered, and therefore, only the used desulfurizing agent of the predetermined value is increased in the raw material ratio of the desulfurizing agent, and only the slaked lime of the predetermined value is decreased. On the other hand, in the case of no at step S11, the opening degree of the discharge valves 21a, 61, 51 shown in fig. 1 is adjusted so that the supply amount of the desulfurizing agent per unit time becomes a predetermined value (step S12).
Then, when the process proceeds to step S11a, it is examined whether or not the sulfur content of the used desulfurizing agent is a predetermined value, for example, 13 mass% or less after four weeks (step S11b), and if "no", that is, if the sulfur content of the desulfurizing agent exceeds the predetermined value, the ratio of all raw materials is returned to the predetermined value (step S11 c). The meaning of "four weeks" is as described above. If YES in step S11b, the flow proceeds to step S8, where a detailed check is made.
When the explanation returns to step S2, if no in step S2, the slaked lime that is the raw material of the desulfurizing agent is decreased by a predetermined amount, for example, 5 mass%, and the coal ash is increased by 5 mass% in accordance with the amount of decrease in the slaked lime (step S13). This operation is based on the knowledge obtained by the present inventors that when the desulfurization performance is lowered, the desulfurization performance is improved by lowering the mass ratio (content) of slaked lime which is a raw material of the desulfurizing agent.
The increase amount of the coal ash is an amount corresponding to the amount (amount) of the slaked lime to be reduced, but is not limited to the two values being identical as long as the values of the two do not differ greatly. For example, even when the amount of hydrated lime is reduced by 5% by mass and the amount of coal ash is increased by 5.1%, the effect of the present invention can be obtained.
After the hydrothermal treatment time is prolonged, it is judged whether or not the desulfurization efficiency is, for example, 95% or less after four weeks (step S14). For the meaning of "four weeks", as explained in step S4. If no in step S14, the ratio of the raw materials changed in step S13 is returned to the value before the change (step S15). If "yes" in step S14, the hydrothermal treatment time of the steam curing device 4 of the manufacturing facility 1 for desulfurizing agent is extended by, for example, 15% from the set time (step S16) in the same manner as described in step S5.
After the hydrothermal treatment time is extended in step S16, the same determination as in step S14 is made (step S17). That is, after the hydrothermal treatment time is extended in step S17, it is determined whether the desulfurization efficiency is, for example, 95% or less after four weeks. Step S17 is a step for examining the influence of the extension of the hydrothermal treatment time on the performance of the desulfurizing agent after the desulfurization treatment of the desulfurizing agent after the hydrothermal treatment time has been extended. If the determination at step S17 is "no", the ratio of the raw materials changed at step S13 is returned to the ratio before the change, and the hydrothermal treatment time changed at step S16 is returned to the hydrothermal treatment time before the change (step S18).
If the determination of step S17 is yes, it is considered that an unexpected event has occurred, and therefore a detailed check of the desulfurization system is performed. If the determination at step S17 is yes, the process may return to step S17, and if the determination at step S17 is yes again, the detailed check may be performed again (step S18).
When "end" in the flowchart, the measurement time of one week is reset, and the determination of step S1 is started.
The above flowchart shows the following points. In steps S1, S2, S9, and S10, the desulfurization efficiency of the flue gas, the hardness of the desulfurizing agent, and the sulfur content of the used desulfurizing agent are obtained at predetermined time points as described above, and it is determined whether or not the measured value continues for one week and is equal to or less than the predetermined value, and this determination is performed as an example for evaluating whether or not the desulfurization efficiency, hardness, and sulfur content exceed the predetermined values. Therefore, as an evaluation method, the time interval of measurement can be arbitrarily set, and a duration in which the measured value deviates from a predetermined value can also be arbitrarily set, and for example, the duration can be changed to 3 days.
In the above embodiment, the used desulfurizing agent, which is obtained by using a desulfurizing agent containing hydrated lime, coal ash for supplying silica and alumina, and gypsum in the desulfurization treatment, is used as a gypsum source of a new desulfurizing agent. Then, the hardness of the desulfurizing agent was measured, and when it was evaluated that the hardness was not more than a predetermined value, the amount of the used desulfurizing agent was increased by a predetermined amount, and the amount of the slaked lime was decreased by the amount corresponding to the increase. Therefore, the hardness of the desulfurizing agent can be maintained at a predetermined value or more, and thus the operation with stable desulfurization efficiency can be performed.
Further, it is monitored whether or not the sulfur content of the used desulfurizing agent exceeds a prescribed value (step S10). Therefore, it is possible to detect that the amount of the desulfurizing agent supplied per unit time to the desulfurizing tower 6 is deviated from a predetermined value or that the performance of the desulfurizing agent is lowered. In addition, as for the performance degradation of the desulfurizing agent, the performance of the desulfurizing agent can be recovered by changing the mixing ratio of the raw materials of the desulfurizing agent as described above.
In the present invention, when the hardness of the desulfurizing agent is measured and evaluated to be equal to or less than a predetermined value, a step of reducing the slaked lime by a predetermined amount and increasing the used desulfurizing agent by a predetermined amount (corresponding to step S3 in the first raw material ratio changing step) is required, but the combination of the other steps is not limited to the description of fig. 3A and 3B. For example, the operation method may be such that the process returns to step S3, which is followed by step S1, and the raw material ratio is restored when step S9 is no.
In the above embodiment, the two-stage desulfurizing tower is provided, but a configuration may be provided in which one stage is provided, or three or more stages may be provided.
Verification test
A desulfurizing agent (1) produced by using slaked lime, coal ash and a used desulfurizing agent as raw materials and fixing the coal ash at 35 mass%, the slaked lime amount being set at 35 mass% and the used desulfurizing agent addition amount being set at 30 mass%, and a desulfurizing agent (2) produced by setting the slaked lime amount at 30 mass% and the used desulfurizing agent addition amount at 35 mass% were prepared. The desulfurizing agent having a Ca utilization of 65% has been used.
The hardness of each of the desulfurizing agents (1) and (2) was measured, and the hardness of the desulfurizing agent (1) was 4.6kg and the hardness of the desulfurizing agent (2) was 5.8 kg. Hardness was measured by using a log cabin type hardness tester, and hardness was measured 20 times for one sample, and the average value of the measured values was defined as the hardness of the sample. From the results, it is understood that the hardness of the desulfurizing agent increases by decreasing the content of the slaked lime and increasing the amount of the desulfurizing agent used.
Description of the symbols
1 desulfurizing agent production apparatus
2 desulfurization device
31 to 33 storage parts
31 b-33 b meter
34. 36 mixing mill
35 storage part
37 extrusion moulding machine
4 steam curing means
41 drier
5 first desulfurizing tower
6 second desulfurizing tower
7 flow path member
Claims (6)
1. A method for operating a dry desulfurization apparatus for desulfurizing a flue gas containing sulfur oxides, comprising the steps of:
a step of mixing a used desulfurizing agent, slaked lime, and an active source supplying material for supplying silica and alumina, with a desulfurizing agent containing slaked lime, an active source supplying material for supplying silica and alumina, and gypsum, the desulfurizing agent being used after a desulfurization treatment, to produce a desulfurizing agent;
a step of supplying the desulfurizing agent produced in the step from the upper part of the desulfurizing tower and forming a moving layer composed of the desulfurizing agent moving downward;
bringing the flue gas into contact with the moving bed in a cross-flow manner;
a step of taking out the used desulfurizing agent from the lower part of the desulfurizing tower;
a first raw material ratio changing step of measuring the hardness of the desulfurizing agent and, when the hardness is evaluated to be equal to or less than a predetermined value, reducing the slaked lime by a predetermined amount and increasing the amount of the desulfurizing agent used by a predetermined amount; and
measuring each concentration of sulfur oxides in the flue gas before and after flowing into the desulfurization tower, obtaining desulfurization efficiency of the flue gas based on the measurement result of the concentration, evaluating that the desulfurization efficiency of the flue gas is not more than a predetermined value, and performing a second raw material ratio changing step of reducing slaked lime by a predetermined amount and increasing the active source supplying material by a predetermined amount when evaluating that the hardness of the desulfurizing agent exceeds a predetermined value,
the step of producing the desulfurizing agent includes a step of curing a mixture containing at least slaked lime and the active source supplying material in a heated state in a steam atmosphere.
2. The method of operating a desulfurization system according to claim 1,
a step of performing the curing longer than a set time period when at least one of the following is included after the first raw material ratio changing step is performed:
a) measuring each concentration of sulfur oxides in the flue gas before and after flowing into the desulfurization tower, obtaining desulfurization efficiency of the flue gas based on the measurement result of the concentration, and evaluating that the desulfurization efficiency of the flue gas is equal to or lower than a preset value; and
b) the hardness of the desulfurizing agent was evaluated to be not more than a predetermined value.
3. The method of operating a desulfurization system according to claim 1,
and a step of performing the curing for a longer time than a predetermined time when the desulfurization efficiency of the flue gas is evaluated to be equal to or less than a predetermined value after the second raw material ratio changing step.
4. The method of operating a desulfurization system according to claim 1,
measuring each concentration of sulfur oxides in the flue gas before and after flowing into the desulfurization tower, and obtaining desulfurization efficiency of the flue gas based on the measurement result of the concentration,
when the desulfurization efficiency of the flue gas is evaluated to be higher than a predetermined value and the hardness of the desulfurizing agent is evaluated to be higher than a predetermined value, the sulfur content of the used desulfurizing agent is measured, and when the sulfur content is evaluated to be lower than or equal to the predetermined value, a step of confirming whether the supply amount of the desulfurizing agent per unit time to the desulfurizing tower is maintained at a predetermined value is performed,
when the supply amount is determined not to maintain a predetermined value, the supply amount is corrected to a predetermined value.
5. The method of operating a desulfurization system according to claim 4,
as a result of the step of checking whether or not the supply amount is maintained at the predetermined value, when it is determined that the supply amount is maintained at the predetermined value, a third raw material ratio changing step of reducing the slaked lime by a predetermined amount and increasing the used desulfurizing agent by a predetermined amount is performed.
6. The method of operating a desulfurization system according to any one of claims 1 to 5,
the curing step is performed by placing the mixture on a placing part which is configured so as not to transmit water vapor.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/JP2017/003790 WO2018142538A1 (en) | 2017-02-02 | 2017-02-02 | Method for operating desulfurization system |
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| CN108697978A CN108697978A (en) | 2018-10-23 |
| CN108697978B true CN108697978B (en) | 2021-10-26 |
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| WO (1) | WO2018142538A1 (en) |
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| WO2021124564A1 (en) * | 2019-12-20 | 2021-06-24 | 北海道電力株式会社 | Steam curing device and desulfurizing agent production device |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5037796A (en) * | 1988-10-24 | 1991-08-06 | The Hokkaido Electric Power Company, Inc. | Process for producing hydrated and cured product of lime-gypsum-coal ash mixture |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5748326A (en) * | 1980-09-06 | 1982-03-19 | Babcock Hitachi Kk | Moving layer type gas adsorbing apparatus |
| JPS59196719A (en) * | 1983-04-22 | 1984-11-08 | Sumitomo Heavy Ind Ltd | Treatment of exhaust gas |
| JPH02115039A (en) * | 1988-10-24 | 1990-04-27 | Hokkaido Electric Power Co Inc:The | Manufacture of desulfurization agent |
| JPH02194833A (en) * | 1989-01-24 | 1990-08-01 | Hokkaido Electric Power Co Inc:The | Production of dry desulfurizing agent for waste gas |
| JP2716574B2 (en) * | 1990-06-21 | 1998-02-18 | 北海道電力株式会社 | Manufacturing method of dry desulfurization agent for exhaust gas treatment |
| JPH04354538A (en) * | 1991-05-31 | 1992-12-08 | Babcock Hitachi Kk | Catalyst for denitrifying exhaust gas and exhaust gas treating device |
| JPH05261279A (en) * | 1992-03-19 | 1993-10-12 | Babcock Hitachi Kk | Production of desulfurizing agent |
| JP3214088B2 (en) * | 1992-09-07 | 2001-10-02 | 三菱マテリアル株式会社 | Manufacturing method of desulfurization material |
| JPH0833826A (en) * | 1994-07-25 | 1996-02-06 | Babcock Hitachi Kk | Treatment of boiler waste combustion gas for coal fired thermal power plant and device therefor |
| JP2952227B2 (en) * | 1998-02-26 | 1999-09-20 | 北海道電力株式会社 | Method for producing exhaust gas treatment agent |
| CN1911491A (en) * | 2006-08-03 | 2007-02-14 | 长春惠工净化工业有限公司 | Moving bed smoke desulfur denitrate and dust removal technology |
| CN103585868B (en) * | 2013-11-27 | 2016-06-08 | 张博 | The flue gas processing device of the de-mercury dedusting of a kind of synchronized desulfuring and denitrifying and method |
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2017
- 2017-02-02 WO PCT/JP2017/003790 patent/WO2018142538A1/en active Application Filing
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5037796A (en) * | 1988-10-24 | 1991-08-06 | The Hokkaido Electric Power Company, Inc. | Process for producing hydrated and cured product of lime-gypsum-coal ash mixture |
Non-Patent Citations (1)
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| 粉煤灰在燃煤锅炉烟气脱硫中的应用;李婷 等;《洁净煤技术》;20131024;第19卷(第5期);第82-84页 * |
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