CN110813043B - Carbide slag/slurry flue gas desulfurization system and method - Google Patents
Carbide slag/slurry flue gas desulfurization system and method Download PDFInfo
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- CN110813043B CN110813043B CN201911147330.2A CN201911147330A CN110813043B CN 110813043 B CN110813043 B CN 110813043B CN 201911147330 A CN201911147330 A CN 201911147330A CN 110813043 B CN110813043 B CN 110813043B
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- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
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- B01D53/501—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound
- B01D53/502—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound characterised by a specific solution or suspension
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- B01D53/46—Removing components of defined structure
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- B01D53/50—Sulfur oxides
- B01D53/501—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound
- B01D53/504—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound characterised by a specific device
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Abstract
The invention discloses a carbide slag/slurry flue gas desulfurization system, which comprises a desulfurization tower, a flue gas pipeline, an exhaust pipe, a first conveying pipe, a second conveying pipe, a desulfurization slurry tank, a carbide slurry replenishing pipe, a third conveying pipe, a first spraying device, a second spraying device, a third spraying device, a fourth spraying device, a partition plate and a demisting device, wherein the first conveying pipe is used for conveying waste sulfuric acid into slurry at the bottom of the desulfurization tower, the second conveying pipe is used for conveying oxidizing air into slurry at the bottom of the desulfurization tower, the desulfurization slurry tank is used for adding carbide slurry into the desulfurization slurry tank, the third conveying pipe is used for conveying the slurry in the desulfurization tower into the desulfurization slurry tank, the first spraying device and the second spraying device are connected with the desulfurization slurry tank and used for conveying the desulfurization slurry into the desulfurization tower to spray and absorb sulfur dioxide, the third spraying device is connected with a liquid conveying pipe of the second spraying device, the fourth spraying device is arranged at the lower part in the desulfurization tower and is used for promoting the oxidation of calcium sulfite, the desulfurization efficiency is high, and the purity of the generated calcium sulfate is high.
Description
Technical Field
The invention relates to the technical field of flue gas desulfurization, in particular to a carbide slag/slurry flue gas desulfurization system and a carbide slag/slurry flue gas desulfurization method.
Background
The existing flue gas desulfurization methods include limestone-gypsum wet method, rotary spray drying method, metal oxide method, flue gas circulating fluidized bed method and activated carbon method, wherein the wet desulfurization method is widely applied in industry. The wet desulfurization is to use lime, carbide slag/slurry, limestone and the like as desulfurizing agents, the desulfurizing agents are prepared into slurry, the flue gas is in countercurrent contact with the slurry in a spray tower, and sulfur dioxide in the flue gas is oxidized and absorbed by the desulfurizing agents to form CaSO4Thereby achieving the purpose of flue gas desulfurization.
In the existing wet desulphurization, in order to improve the absorption efficiency of sulfur dioxide, the absorption slurry is strongly alkaline and is favorable for generating C by mainly improving the pH value of the desulphurization slurryaSO4However, the product calcium sulfate contains a large amount of calcium sulfite, so that the purity of the calcium sulfate is low and the additional value is low; on the other hand, the high content of the calcium sulfite can cause poor dehydration effect of the calcium sulfate, and a large amount of energy consumption can be caused in the subsequent drying of the calcium sulfate; in addition, the solubility of calcium sulfite is lower than that of calcium sulfate, so that the problems of scaling, blockage and the like of a pipeline are easily caused in the slurry circulation process, and the normal operation of a desulfurization system is further influenced.
In the existing flue gas desulfurization, the outlet of the desulfurizing tower monitors sulfur dioxide in flue gas on line, and when the emission concentration is high, the control system inevitably increases the addition of a desulfurizing agent and increases the circulation volume. After the pH value of the desulfurization slurry is increased, carbon dioxide and calcium hydroxide in the flue gas can form calcium carbonate, the pH value of the slurry in the tower kettle can be increased due to the surplus calcium hydroxide, calcium sulfite can not be effectively oxidized into calcium sulfate under the high pH condition, the calcium sulfite can not be effectively dehydrated, and a calcium sulfite cement plant with high water content after dehydration can not consume; if the carbide slag desulfurizer is added less, the pH of the desulfurization slurry is low, sulfur dioxide cannot produce calcium sulfite together with calcium hydroxide, and the emission of sulfur dioxide does not reach the standard.
In view of the above, there is a need to provide a new flue gas desulfurization process to solve the above problems.
Disclosure of Invention
The invention aims to solve the technical problem of providing a carbide slag/slurry flue gas desulfurization system which has high desulfurization efficiency, high conversion rate of converting calcium sulfite into calcium sulfate, high purity of the obtained calcium sulfate and increased additional value of desulfurization by-product calcium sulfate.
In order to solve the problems, the technical scheme of the invention is as follows:
1. a carbide slag/slurry flue gas desulfurization system comprises a desulfurization tower, a flue gas pipeline entering the bottom of the desulfurization tower from a boiler electric bag dust remover, a first delivery pipe entering slurry at the bottom of the desulfurization tower for delivering waste sulfuric acid, a second delivery pipe entering slurry at the bottom of the desulfurization tower for delivering oxidizing air, a third delivery pipe delivering slurry in the desulfurization tower to a desulfurization slurry tank, a carbide slurry replenishing pipe adding carbide slurry into the desulfurization slurry tank, a first spray device and a second spray device which are connected with the desulfurization slurry tank and used for delivering the desulfurization slurry to the top of the desulfurization tower to spray and absorb sulfur dioxide, a third spray device connected with a delivery pipe of the second spray device, a fourth spray device arranged at the lower part in the desulfurization tower and using the slurry at the bottom of the tower as spray liquid to promote calcium sulfite oxidation, a partition plate arranged in the desulfurization tower and provided with a gas lift pipe, a demisting device arranged at the top of the desulfurization tower, The exhaust pipe is arranged at the top of the desulfurizing tower;
the flue gas pipeline is inserted above the liquid level of the tower kettle of the desulfurizing tower at an angle of 15 degrees downwards in the horizontal direction so as to prevent the desulfurizing slurry from flowing backwards into the flue gas pipeline;
the partition plate is positioned above the liquid level of the tower kettle and divides the space at the middle lower part in the desulfurizing tower into an upper sulfur dioxide absorption area and a lower calcium sulfite oxidation area, the flue gas enters the desulfurizing tower kettle and is in countercurrent contact with the spray liquid of the fourth spray device and then enters the upper sulfur dioxide absorption area of the desulfurizing tower through the riser, and the partition plate also has the function of preventing the desulfurizing slurry obtained after the first spray device and the second spray device absorb the sulfur dioxide in the flue gas from directly entering the tower kettle to cause the pH value of slurry in the tower kettle to be increased so as to be not beneficial to the oxidation of calcium sulfite in the tower kettle;
the sulfur dioxide absorption area absorbs sulfur dioxide in flue gas by the desulfurization slurry sprayed by the first spraying device and the second spraying device, and the formed desulfurization slurry is conveyed to a desulfurization slurry tank to prepare desulfurization slurry;
the spray pipe of the fourth spray device is higher than the inlet position of the flue gas pipeline;
the calcium sulfite oxidation zone is used for introducing waste sulfuric acid through a first conveying pipe to reduce the pH value and conveying oxidation air through a second conveying pipe to oxidize calcium sulfite;
the third spraying device is positioned in the calcium sulfite oxidation zone, spraying liquid of the third spraying device is conveyed through a liquid conveying pipe of the second spraying device, the third spraying device is connected with a calcium carbide slurry replenishing pipe, and calcium sulfate is generated by replenishing calcium carbide slurry to the third spraying device so as to neutralize waste acid in the calcium sulfite oxidation zone;
the fourth spraying device, the third spraying device, the second spraying device and the first spraying device are sequentially arranged from the bottom to the top of the tower, the fourth spraying device and the first spraying device are respectively conveyed with spraying liquid by independent circulating pumps, the third spraying device and the second spraying device are conveyed with spraying liquid by the same circulating pump, corresponding circulating pumps are respectively provided with a frequency converter capable of being linked, so that the mass ratio of spraying desulfurization slurry of the fourth spraying device, the first spraying device and the second spraying device is controlled to be 2:1:1, the spraying amount of the third spraying device is adjusted by the liquid level of a desulfurization slurry tank, and the sum of the calcium carbide slurry adding amount of the desulfurization slurry tank, the calcium carbide slurry adding pipe and the third spraying device is supplemented to a demister at the top of the tower, so that the materials in the sulfur dioxide absorption zone are balanced;
the fourth, third, second and first spray devices comprise spray pipes and a plurality of nozzles arranged on the spray pipes, and the desulfurization slurry is uniformly distributed to each nozzle through the spray pipes and is sprayed out, and fully contacts with the flue gas flowing upwards in a counter-current manner so as to absorb sulfur dioxide in the flue gas.
2. The desulfurization method of the carbide slag/slurry flue gas desulfurization system based on the 1 comprises the following steps:
preparing desulfurization slurry: taking slurry in a sulfur dioxide absorption area above a partition plate of a desulfurizing tower as circulating slurry, adding calcium carbide slurry prepared from dry calcium carbide slag or calcium carbide slurry directly conveyed by other production devices through a pipeline into the circulating slurry to prepare the desulfurizing slurry, controlling the mass percentage concentration of the calcium carbide slurry in the desulfurizing slurry to be 20-30%, controlling the pH value of the desulfurizing slurry to be 7-8, and adding methyl silane oil or polysiloxane organic silicon defoamer with the mass percentage concentration of 1-5 per thousand;
and (3) circulation of the desulfurization slurry: conveying the desulfurization slurry from the desulfurization slurry tank to a first spraying device and a second spraying device at the middle part and the upper part of a desulfurization tower respectively by corresponding circulating pumps, enabling the desulfurization slurry to be in countercurrent contact with sulfur dioxide in flue gas, absorbing the sulfur dioxide in the flue gas to generate calcium sulfite, enabling the desulfurization slurry to enter the desulfurization tower slurry tank through a tower outlet pipe arranged at the upper side of a partition plate of the desulfurization tower, and adjusting the pH value of the desulfurization slurry to be 7-8 by adding carbide slurry;
calcium sulfite oxidation: respectively introducing waste sulfuric acid and oxidizing air into the slurry in the tower kettle through a first conveying pipe and a second conveying pipe, and reducing the pH value of the slurry in the tower kettle to 5.0-6.5 through the waste sulfuric acid so that calcium sulfite is oxidized into calcium sulfate by the oxidizing air under the weak acid condition; if the pH value of the slurry in the tower kettle is more than 6.5, the oxidation of calcium sulfite to generate calcium sulfate is not facilitated; if the pH value of the slurry in the tower kettle is lower than 5, the oxidation of calcium sulfite into calcium sulfate is facilitated, but the unreacted sulfuric acid enters a subsequent dehydration system;
the fourth spraying device is used for conveying the desulfurization slurry in the tower kettle to a calcium sulfite oxidation area through a circulating pump arranged outside the desulfurization tower and is used for increasing the contact rate of oxidation air and calcium sulfite and the contact rate of unabsorbed calcium hydroxide and sulfuric acid;
the third spraying device is used for sending the desulfurization slurry containing calcium sulfite and calcium hydroxide in the desulfurization slurry tank into the lower part of a partition plate of a desulfurization tower to absorb sulfur dioxide in the flue gas, the redundant calcium hydroxide in the desulfurization slurry enters a calcium sulfite oxidation area to continuously react with waste sulfuric acid to generate calcium sulfate, and the third spraying device is connected with a calcium carbide slurry replenishing pipe and is used for automatically adjusting the pH value of the calcium sulfite oxidation area to 5.0-6.5 by replenishing the calcium carbide slurry;
conveying calcium sulfate: calcium sulfate discharged from the bottom of the tower kettle is conveyed to a dewatering system through a pump, and is conveyed to a cement plant as a raw material for producing cement after being dewatered;
flue gas purification and automatic control: the flue gas enters from the bottom of the desulfurizing tower kettle and is in countercurrent continuous contact with the spraying desulfurization slurry of the fourth, third, second and first spraying devices, and the desulfurization slurry absorbs SO in the flue gas2Generating calcium sulfite, and discharging the desulfurized flue gas after demisting.
The carbide slag/slurry flue gas desulfurization system and the method have the beneficial effects that:
1. according to the carbide slag/slurry flue gas desulfurization system, the partition plate with the air lifting pipe is arranged in the desulfurization tower, so that the space in the desulfurization tower is divided into an upper sulfur dioxide absorption area and a lower calcium sulfite oxidation area; the slurry in the sulfur dioxide absorption area is used for preparing the desulfurization slurry, the pH value of the desulfurization slurry is adjusted to 7-8 by controlling the adding amount of the calcium carbide slurry, and the SO is increased2While suppressing CO2So that the absorption liquid does not contain CaCO3Ingredients to improve the purity of the desulfurization product calcium sulfate; by introducing waste sulfuric acid and oxidizing air into calcium sulfite oxidation zone and controllingThe addition of the sulfuric acid reduces the pH value of the slurry in the tower kettle to 5.0-6.5, which is favorable for spraying and absorbing SO2Oxidizing and crystallizing the formed calcium sulfite to oxidize most of the calcium sulfite in the desulfurization slurry into calcium sulfate; simultaneously, the desulfurized slurry portion enters a calcium sulfite oxidation zone for neutralizing sulfuric acid and reacting to produce calcium sulfate. The arrangement of the partition plate in the invention divides the inside of the desulfurizing tower into two parts, and can also avoid the problem that the pH value of slurry in the tower kettle is increased to be unfavorable for the oxidation of calcium sulfite in the tower kettle because high-pH desulfurizing slurry at the upper part enters the tower kettle.
2. The carbide slag/slurry flue gas desulfurization method of the invention introduces sulfuric acid to neutralize the desulfurization slurry and spray and absorb SO2Rear excess Ca (OH)2Therefore, the carbide slag/slurry in the sulfur dioxide absorption area can be excessive, the absorption of the sulfur dioxide in the flue gas is fully ensured, and the environmental protection risk is avoided; meanwhile, redundant calcium hydroxide in the carbide slag/slurry is converted into calcium sulfate.
3. The method for desulfurizing the carbide slag/slurry flue gas adopts the carbide slag/slurry desulfurization, introduces the waste sulfuric acid and oxidizes air to oxidize calcium sulfite, realizes the comprehensive treatment and utilization of waste gas, waste liquid and waste residue, and particularly comprehensively treats three wastes with higher treatment difficulty in one set of device by using the carbide as a raw material to generate the carbide slag/slurry by using dry acetylene, cleaning the concentrated sulfuric acid by using the concentrated sulfuric acid acetylene and generate the flue gas by using a coal-fired boiler.
4. According to the carbide slag/slurry flue gas desulfurization method, a large amount of calcium sulfate is generated in slurry, the calcium sulfate dehydration effect is good, the water content of the calcium sulfate after dehydration through a vacuum dehydrator is 10-15% by mass, the calcium sulfate content of dry slag is 98% by mass, and the calcium sulfite content of dry slag is only 0.5% by mass, so that the purity of the obtained calcium sulfate is high, the desulfurization efficiency and the product calcium sulfate purity are improved, the additional value of the desulfurization byproduct calcium sulfate is increased, and the flue gas desulfurization efficiency reaches 97.6% by mass.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below.
FIG. 1 is a schematic diagram of a carbide slag/slurry flue gas desulfurization system provided by the present invention.
Detailed Description
In order to make the technical solutions in the embodiments of the present invention better understood and make the above objects, features and advantages of the present invention more comprehensible, a specific embodiment of the present invention is further described below with reference to fig. 1. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The invention provides a carbide slag/slurry flue gas desulfurization system, which comprises a desulfurization tower, a flue gas pipeline entering the bottom of the desulfurization tower from a boiler electric bag dust remover, a first conveying pipe entering slurry at the bottom of the desulfurization tower for conveying waste sulfuric acid, a second conveying pipe entering slurry at the bottom of the desulfurization tower for conveying oxidized air, a third conveying pipe for conveying slurry in the desulfurization tower to a desulfurization slurry tank, a carbide slurry replenishing pipe for adding carbide slurry into the desulfurization slurry tank, a first spraying device and a second spraying device which are connected with the desulfurization slurry tank and used for conveying the desulfurization slurry to the top of the desulfurization tower for spraying and absorbing sulfur dioxide, a third spraying device connected with a liquid conveying pipe of the second spraying device, a fourth spraying device arranged at the inner lower part of the desulfurization tower and taking the slurry at the bottom of the tower as spraying liquid to promote calcium sulfite to be oxidized, and a partition plate arranged in the desulfurization tower and provided with a gas lifting pipe, The demisting device is arranged at the top of the desulfurizing tower, and the exhaust pipe is arranged at the top of the desulfurizing tower;
the flue gas pipeline is inserted above the liquid level of the tower kettle of the desulfurizing tower at an angle of 15 degrees downwards in the horizontal direction so as to prevent the desulfurizing slurry from flowing backwards into the flue gas pipeline;
the partition plate is positioned above the liquid level of the tower kettle and divides the space at the middle lower part in the desulfurizing tower into an upper sulfur dioxide absorption area and a lower calcium sulfite oxidation area, the flue gas enters the desulfurizing tower kettle and is in countercurrent contact with the spray liquid of the fourth spray device and then enters the upper sulfur dioxide absorption area of the desulfurizing tower through the riser, and the partition plate also has the function of preventing the desulfurizing slurry obtained after the first spray device and the second spray device absorb the sulfur dioxide in the flue gas from directly entering the tower kettle to cause the pH value of slurry in the tower kettle to be increased so as to be not beneficial to the oxidation of calcium sulfite in the tower kettle;
the sulfur dioxide absorption area absorbs sulfur dioxide in flue gas by the desulfurization slurry sprayed by the first spraying device and the second spraying device, and the formed desulfurization slurry is conveyed to a desulfurization slurry tank to prepare desulfurization slurry;
the spray pipe of the fourth spray device is higher than the inlet position of the flue gas pipeline;
the calcium sulfite oxidation zone is used for introducing waste sulfuric acid through a first conveying pipe to reduce the pH value and conveying oxidation air through a second conveying pipe to oxidize calcium sulfite;
the third spraying device is positioned in the calcium sulfite oxidation zone, spraying liquid of the third spraying device is conveyed through a liquid conveying pipe of the second spraying device, the third spraying device is connected with the calcium carbide slurry replenishing pipe, and calcium sulfate is generated by replenishing calcium carbide slurry to the third spraying device so as to neutralize waste acid in the calcium sulfite oxidation zone;
the fourth spraying device, the third spraying device, the second spraying device and the first spraying device are sequentially arranged from the bottom to the top of the tower, the fourth spraying device and the first spraying device are respectively conveyed with spraying liquid by independent circulating pumps, the third spraying device and the second spraying device are conveyed with spraying liquid by the same circulating pump, corresponding circulating pumps are respectively provided with a frequency converter capable of being linked, so that the mass ratio of spraying desulfurization slurry of the fourth spraying device, the first spraying device and the second spraying device is controlled to be 2:1:1, the spraying amount of the third spraying device is adjusted by the liquid level of a desulfurization slurry tank, and the sum of the calcium carbide slurry adding amount of the desulfurization slurry tank, the calcium carbide slurry adding pipe and the third spraying device is supplemented to a demister at the top of the tower, so that the materials in the sulfur dioxide absorption zone are balanced;
the fourth, third, second and first spray devices comprise spray pipes and a plurality of nozzles arranged on the spray pipes, and the desulfurization slurry is uniformly distributed to each nozzle through the spray pipes and is sprayed out, and fully contacts with the flue gas flowing upwards in a counter-current manner so as to absorb sulfur dioxide in the flue gas.
The carbide slag/slurry flue gas desulfurization system of the present invention is described in detail below by way of specific examples.
Example one
FIG. 1 is a schematic diagram of a carbide slag/slurry flue gas desulfurization system provided by the invention. The carbide slag/slurry flue gas desulfurization system provided by the invention comprises a desulfurization tower 1, a sulfuric acid conveying device 2, an oxidation air conveying device 3, a desulfurization slurry liquid tank 4, a carbide slurry replenishing pipe 5, a first spraying device 6, a second spraying device 7, a third spraying device 8, a fourth spraying device 9 and a partition plate 10. The partition 10 divides the reaction space in the desulfurization tower into two parts, a sulfur dioxide absorption zone 10a located at the upper part of the partition 10 and a calcium sulfite oxidation zone 10b located at the lower part of the partition 10.
The desulfurizing tower 1 is of a cylindrical structure, a flue gas pipeline 12 is arranged at the bottom of the desulfurizing tower, an exhaust pipe 13 is arranged at the top of the desulfurizing tower, the flue gas pipeline 12 is used for conveying flue gas treated by the electric bag dust collector of the boiler into the desulfurizing tower, and the flue gas is discharged from the exhaust pipe 13 after being purified. Specifically, the flue gas pipeline 12 is inserted above the liquid level of the tower bottom of the desulfurizing tower at an angle of 15 degrees downward in the horizontal direction so as to prevent the desulfurizing slurry from flowing backward into the flue gas pipeline 12.
The flue gas enters a calcium sulfite oxidation zone 10b from a flue gas inlet pipe 12, and is in countercurrent contact with the spray liquid of a fourth spray device 9 and the desulfurization slurry of a third spray device 8 in sequence to primarily absorb SO2Then, the flue gas enters a sulfur dioxide absorption area 10a through a riser 101 of the clapboard 10, and is in countercurrent contact with the desulfurization slurry of the second spray device 7 and the first spray device 6 in sequence to completely absorb SO2Then, after being demisted by the demisting device 14, the exhaust gas is discharged through the exhaust pipe 13. The structures of the second spraying device 7 and the first spraying device 6 of the sulfur dioxide spraying absorption device will be explained in combination with the structures of the desulfurization slurry tank 4 and the like in the following, the demisting device 14 is used for removing mist foam carried in flue gas and washing slag attached to the demister through spraying water, and the structure can refer to the prior art and is not described herein any more.
The sulfuric acid conveying device 2 comprises a sulfuric acid tank 21 and a first conveying pipe 22 for conveying sulfuric acid from the sulfuric acid tank 21 to the bottom of the desulfurizing tower 1, wherein the first conveying pipe 22 extends into the desulfurizing tower 1, and in the running state, the first conveying pipe 22 is inserted into the slurry, so that the sulfuric acid can be prevented from generating acid mist when entering the desulfurizing tower. Preferably, the pipe section of the first delivery pipe 22 inserted into the slurry is provided with a plurality of liquid outlet holes, so that the sulfuric acid is uniformly output in the tower, and the efficiency and the reaction degree of the chemical reaction in the slurry can be improved. Wherein, the sulfuric acid tank 21 stores waste sulfuric acid generated in industrial production. The waste sulfuric acid is introduced through the first conveying pipe 22 to reduce the pH value of the slurry in the calcium sulfite oxidation zone to 5-6.5, so that the oxidation of calcium sulfite is facilitated, and the condition that the oxidation of calcium sulfite is not facilitated due to the fact that the pH value of the desulfurization slurry in the whole desulfurization tower is 7-8 for improving the capability of absorbing sulfur dioxide in a common desulfurization tower is avoided;
the oxidizing air delivery device 3 comprises a second delivery pipe 31 arranged at the bottom of the desulfurization tower 1, wherein the second delivery pipe 31 extends into the desulfurization tower 1, and in the operating state, the second delivery pipe 31 is inserted into the slurry, so that oxidizing air directly enters the slurry and participates in the oxidation reaction of calcium sulfite. Preferably, the second delivery pipe 31 is provided with a plurality of air holes (not shown), and the plurality of air holes are distributed in different directions of the second delivery pipe 31, so that the input of the oxidizing air generates driving forces in different directions in the slurry, and the reaction substances can be fully contacted. In this embodiment, the oxidizing air may be obtained by an air compressor.
The desulfurization slurry tank 4 is connected with the sulfur dioxide absorption zone 10a on the upper part of the partition plate 10 through a third conveying pipe 41, and the slurry in the sulfur dioxide absorption zone 10a is used as circulating liquid and conveyed into the desulfurization slurry tank 4 for preparing desulfurization slurry. Since the slurry contains suspended particles, in order to prevent clogging of the piping during transportation, it is preferable to provide a stirring device in the desulfurization slurry tank 4. While in order to prevent clogging by calcium sulfite precipitation generated in the sulfur dioxide absorption zone 10a, it is preferable to provide an agitation device above the partition 9.
The carbide slurry supplementing pipe 5 can be used for preparing carbide slurry through dry carbide slag or directly providing the carbide slurry through other devices such as a dry acetylene generating device, the qualified carbide slurry is prepared and sent into a desulfurizing tower system through a pipeline, most of the carbide slurry is used for adding the carbide slurry into a desulfurizing slurry tank 4, SO that the conditions such as the concentration, the pH value and the like of the desulfurizing slurry are favorable for SO2A small part of the desulfurized slurry is used for supplementing the limestone slurry into the third spraying device 8, so that the conditions of the concentration, the pH value and the like of the desulfurized slurry are favorable for the oxidation of the calcium sulfite. At the same time, the carbide slurry is used for compensationMethyl hydrosilane oil or polysiloxane organosilicon antifoaming agent with the mass percentage concentration of 1-5 per mill is added into the feeding pipe 5 at the same time for inhibiting the organic matters in the waste sulfuric acid from entering into the foam generated by the desulfurizing tower.
The spray liquid of the second spray device 7 and the first spray device 6 is derived from the desulfurization slurry tank 4, and therefore, the second spray device 7 and the first spray device 6 are connected to the desulfurization slurry tank 4. In this embodiment, the SO may be increased by a two-stage spray absorption process2The absorption rate of (c). The first spraying device 6 and the second spraying device 7 are respectively connected with corresponding circulating pumps (not marked), desulfurization slurry is respectively conveyed by the corresponding circulating pumps, the circulating pumps are independently controlled, and the starting and stopping or rotating speed of the circulating pumps are adjusted according to different working conditions. Circulating pumps corresponding to the first spraying device 6 and the second spraying device 7 are respectively provided with a linked frequency converter for adjusting the spraying amount of the first spraying device 6 and the second spraying device 7 according to the operation condition, and the circulating pump is also used for reducing the circulating amount of the desulfurization slurry or directly stopping the first spraying device when the flue gas load is low. Preferably, the desulfurization slurry tank 4 is provided with a liquid level control device, and the liquid level controls the conveying amount of the third spraying device.
The first spraying device 6 and the second spraying device 7 both comprise spraying pipes and nozzles, and the desulfurization slurry is uniformly distributed to each nozzle through the spraying pipes and is sprayed out, and the desulfurization slurry is fully contacted with the flue gas flowing upwards in a counter-current manner so as to absorb sulfur dioxide in the flue gas. In this embodiment, the shower of the first shower device 6 is located above the shower of the second shower device 7.
The third spray device 8 is connected with the liquid pipe of the second spray device 7, the spray liquid is conveyed by the circulating pump corresponding to the second spray device 7, the spray pipe is positioned in the calcium sulfite oxidation zone 10b, the surplus part of the desulfurization slurry in the desulfurization slurry tank 4 enters the calcium sulfite oxidation zone at the bottom of the desulfurization tower kettle, on one hand, the desulfurization slurry contains surplus Ca (OH)2The calcium sulfate and the waste sulfuric acid are subjected to neutralization reaction to generate calcium sulfate; on the other hand, the slurry containing the calcium sulfite in the sulfur dioxide absorption zone is conveyed to a calcium sulfite oxidation zone to be oxidized into calcium sulfate. The third spraying device 8 is connected with a calcium carbide slurry supplementing pipe 5, and calcium carbide slurry is supplemented through the calcium carbide slurry supplementing pipe 5 and used for adjusting calcium sulfite oxygenThe pH of the chemical region 10 b.
The fourth spraying device 9 is arranged below the third spraying device 8 and is positioned in the calcium sulfite oxidation zone 10 b. On one hand, the spray liquid introduced by the fourth spray device 9 can be used for improving the contact rate of the oxidizing air and the calcium sulfite in the calcium sulfite oxidation zone 10b and the contact rate of the sulfuric acid and the calcium hydroxide, and improving the yield of the product calcium sulfate. The fourth spraying device 9 is used for conveying spraying slurry by a single circulating pump, and circularly conveying the tower bottom slurry to the calcium sulfite oxidation zone 10b, and the structure of the fourth spraying device is similar to that of the first spraying device 6 and the second spraying device 7, and the detailed description is omitted here.
Calcium sulfate generated at the bottom of the desulfurization tower is pumped to a dehydration system through a slurry delivery pump 15 for vacuum dehydration, and the slurry level at the bottom of the desulfurization tower automatically controls the delivery amount of the delivery pump 15.
In this embodiment, in order to prevent the slurry at the bottom of the tower from settling and blocking the pipeline, it is preferable to provide a stirring device at the bottom of the desulfurization tower 1 as well.
In this embodiment, the function of the partition board 10 is also to prevent calcium carbide slurry from entering the tower kettle to cause the pH value of slurry in the tower kettle to increase, which is not beneficial to the oxidation of calcium sulfite in the tower kettle. The arrangement of the air ascending pipe 101 on the partition plate 10 is key, and the pipe diameter of the air ascending pipe affects the treatment efficiency of the flue gas, the balance of the neutralization reaction and the calcium sulfite oxidation reaction, and is a key factor of the balance or unbalance of the desulfurization system. Tests show that the system effect is best when the pipe diameter of the gas lift pipe 101 accounts for 1/2 of the tower diameter of the desulfurizing tower 1.
Corresponding to the carbide slag/slurry flue gas desulfurization system, the carbide slag/slurry flue gas desulfurization method provided by the invention comprises the following steps:
(1) preparing desulfurization slurry: taking the slurry at the bottom of the sulfur dioxide absorption area 10a as circulating slurry, adding the carbide slurry into the circulating slurry to prepare desulfurized slurry, and maintaining the pH value of the desulfurized slurry at 7-8 in the running state;
the slurry at the bottom of the sulfur dioxide absorption area 10a enters a desulfurization slurry tank 4 through a third conveying pipe 41, and the pH value is adjusted to 7-8 by adding carbide slurry to form desulfurization slurry;favoring SO under this pH condition2Absorb and can inhibit CO2The absorption of (2) makes the product in the absorption slurry single. Wherein the mass percent of the carbide slurry in the desulfurization slurry is 20-30%;
it should be noted that, considering the flue gas desulfurization process of the present invention comprehensively, the components are complicated due to the introduction of the waste sulfuric acid and the carbide slag/slurry, and a certain amount of foam is generated in the slurry under the introduction condition of the oxidizing air, which will seriously affect the operation of the device. Therefore, the technical problem can be solved by adding a silicone antifoaming agent to the desulfurization slurry. The defoaming agent can be added when the calcium carbide slurry is prepared, and the adding amount is 1-5 per mill of the mass of the calcium carbide slurry; the defoaming agent can be an organic silicon defoaming agent or other special desulfurization defoaming agents.
(2) And (3) circulation of the desulfurization slurry: the desulfurization slurry from the desulfurization slurry tank 4 is respectively conveyed to a first spraying device 6 and a second spraying device 7 on the upper part and the middle part of the desulfurization tower by corresponding circulating pumps, and is in countercurrent contact with the flue gas, after absorbing sulfur dioxide in the flue gas to generate calcium sulfite, the desulfurization slurry enters the desulfurization tower slurry tank 4 through a tower outlet arranged on the upper side of a partition plate 10 of the desulfurization tower, the pH value of the desulfurization slurry is adjusted to be maintained at 7-8 by adding carbide slurry, and the circulation quantity of the desulfurization slurry can be reduced or the second spraying device is directly stopped when the flue gas load is low;
the spray pipe of the third spray device 8 is arranged in the calcium sulfite oxidation zone 10b, the delivery amount is adjusted through the liquid level of the desulfurization slurry tank, and the desulfurization slurry containing calcium sulfite and calcium hydroxide is delivered to the lower part of the partition plate 10 of the desulfurization tower to absorb sulfur dioxide in the flue gas; the redundant calcium hydroxide in the desulfurization slurry enters a calcium sulfite oxidation zone to continuously react with the waste sulfuric acid to generate calcium sulfate; the third spraying device 8 also supplements the calcium sulfite slurry through a calcium sulfite slurry supplementing pipe, and is used for adjusting the pH value of the calcium sulfite oxidation area 10 b.
(3) Calcium sulfite oxidation: introducing waste sulfuric acid and oxygen-containing air into the slurry in the kettle of the desulfurization tower, and reducing the pH value of the slurry in the kettle of the desulfurization tower to 5.0-6.5 by the waste sulfuric acid to oxidize air into calcium sulfate under the weak acid condition, wherein if the pH value of the slurry in the kettle of the desulfurization tower is more than 6.5, the oxidation of the calcium sulfite into the calcium sulfate is not facilitated; if the pH value of the slurry in the tower kettle is lower than 5, the oxidation of calcium sulfite into calcium sulfate is facilitated, but the unreacted sulfuric acid enters a subsequent dehydration system;
the fourth spraying device 9 is used for conveying the tower bottom slurry by a circulating pump arranged at the bottom of the desulfurization tower, and circulating the tower bottom slurry to the calcium sulfite oxidation zone to increase the contact rate of the oxidation air and the calcium sulfite and the contact rate of the unabsorbed calcium hydroxide and the sulfuric acid; the spray pipe of the fourth spray device 9 is slightly higher than the inlet position of the flue gas pipeline 12;
(4) conveying calcium sulfate: controlling the delivery amount of the calcium sulfate slurry at the bottom of the tower kettle through the liquid level of the tower kettle, pumping the slurry into a dewatering system, dewatering, and then delivering to a cement plant as a raw material for producing cement;
(5) flue gas purification: the flue gas enters from the bottom of the desulfurization tower kettle, is primarily absorbed by the tower kettle slurry of the fourth spray device 9, and then is in countercurrent contact with the spray desulfurization slurry of the third spray device 8, the second spray device 7 and the first spray device 6 in sequence, and the desulfurization slurry absorbs SO in the flue gas2Generating calcium sulfite, and discharging the desulfurized flue gas after demisting. The desulfurizing tower system controls the carbide slurry supplement amount of a desulfurizing slurry tank through a sulfur dioxide absorption area pH meter, controls the carbide slurry supplement amount of a third spraying system through a calcium sulfite oxidation area pH meter, and controls the carbide slurry supplement amount through a flue gas discharge port SO2The monitoring system controls the fourth, second and first spraying device circulating pump frequency converters to enable the desulfurization system to be in an environment-friendly, stable, low-consumption and high-efficiency running state.
In the embodiment, waste sulfuric acid is preferably adopted, so that the waste liquid is fully and effectively utilized, and the waste liquid treatment cost is reduced; the mass percentage of the used waste sulfuric acid is 80-85%. The introduction of the waste sulfuric acid can complete the excessive Ca (OH) in the slurry2The neutralization reaction generates calcium sulfate; the pH value of the reaction system is maintained at 5.0-6.5, under the condition, the oxidation and crystallization of calcium sulfite can be facilitated, and the dehydration effect of calcium sulfate crystals is improved;
by the process design of the invention, the calcium sulfite in the slurry is basically completely converted into calcium sulfate, and the content of the calcium sulfite is extremely small.
In the invention, the spraying amount ratio of the fourth spraying device, the second spraying device and the first spraying device is 2:1: 1; the reaction of the reaction system is optimized, and the reaction space in the desulfurizing tower is divided into two parts by increasing the design of the partition plate, so that the efficiency of each reaction system is improved. The spraying amount of the third spraying device 8 is adjusted through the liquid level of the desulfurization slurry tank, and is the sum of the calcium carbide slurry adding amount in the desulfurization slurry tank, the calcium carbide slurry adding amount supplemented to the third spraying device by the calcium carbide slurry supplementing pipe and the spraying water amount of the tower top demister, so that the materials in the sulfur dioxide absorption zone are balanced.
Example two
The application embodiment adopts a corresponding system and method of the embodiment, and the process conditions are as follows:
the flue gas enters a desulfurizing tower 260508m3/h，SO2Concentration 7590-7680mg/m3；
Controlling the calcium-sulfur mass ratio Ca/S of the desulfurization system to be 1.1;
controlling the mass percent of the carbide slag in the desulfurization slurry to be 20-30%;
controlling the gas-liquid ratio, controlling the mass ratio of the spraying quantity of the fourth spraying device to the mass ratio of the spraying quantity of the second spraying device to the spraying quantity of the first spraying device to be 2:1:1, and specifically controlling the circulation quantity of the fourth spraying device to be 2400m3H, the circulation volume of the first spraying device is 1200m3H, the circulation volume of the second spraying device is 1200m3The larger the circulation amount (the larger the gas-liquid ratio), the higher the desulfurization efficiency. The spraying amount of the third spraying device which is controlled to be sent into the calcium sulfite oxidation area through the liquid level of the desulfurization slurry tank is 10-15m3/h。
Spent sulfuric acid and carbide slag/pulp consumption: the concentration of the waste sulfuric acid is 85%, the device is calculated according to 3500t/a treatment capacity, 0.48t of waste sulfuric acid needs to be treated per hour, 0.45t/h of a desulfurizing agent (calculated by dry carbide slag) needs to be added, 1.5 tons of carbide slag is consumed per hour after flue gas desulfurization, 1.95 tons of dry carbide slag needs to be added into a desulfurizing tower per hour, 10 tons of carbide slurry needs to be added according to the mass percentage of 20% of the carbide slag, most of the part of the carbide slurry enters a desulfurizing slurry tank through the pH meter of a sulfur dioxide absorption zone, and the small part of the carbide slurry enters a third spraying device through the pH meter of a calcium sulfite oxidation zone;
the technical effects are as follows: flue gas goes out of desulfurizing tower 24550m3/h,SO2Concentration 185-3The desulfurization effect reaches 97.6 percent;
after the calcium sulfate is dehydrated by the vacuum dehydrator, the mass percent of the water content is 8-12%, the mass percent of the calcium sulfate content in the dry slag is 98.8%, and the mass percent of the calcium sulfite content is 0.5%, and as the waste sulfuric acid is neutralized to generate a large amount of calcium sulfate, the calcium sulfate dehydration effect is good;
and (5) sending the dehydrated clear liquid to a sewage plant for treatment, and discharging after reaching the standard.
In conclusion, the carbide slag/slurry flue gas desulfurization method and system provided by the invention improve the desulfurization efficiency and the purity of calcium sulfate product, and increase the added value of the desulfurization byproduct calcium sulfate.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments.
The embodiments of the present invention are described in detail above with reference to fig. 1, but the present invention is not limited to the described embodiments. Various changes, modifications, substitutions and alterations to these embodiments will occur to those skilled in the art without departing from the spirit and scope of the present invention.
Claims (1)
1. A desulfurization method of a carbide slag/slurry flue gas desulfurization system is characterized in that:
(1) the carbide slag/slurry flue gas desulfurization system comprises a desulfurization tower, a flue gas pipeline entering the bottom of the desulfurization tower from a boiler electric bag dust remover, a first conveying pipe for conveying waste sulfuric acid into slurry at the bottom of the desulfurization tower, a second conveying pipe for conveying oxidized air into the slurry at the bottom of the desulfurization tower, a third conveying pipe for conveying slurry in the desulfurization tower to a desulfurization slurry tank, a carbide slurry replenishing pipe for adding carbide slurry into the desulfurization slurry tank, a first spraying device and a second spraying device which are connected with the desulfurization slurry tank and used for conveying the desulfurization slurry into the desulfurization tower and spraying and absorbing sulfur dioxide at the top, a third spraying device connected with a liquid conveying pipe of the second spraying device, a fourth spraying device arranged at the lower part in the desulfurization tower and using the slurry at the bottom of the tower as spraying liquid to promote calcium sulfite to be oxidized, a partition plate arranged in the desulfurization tower and provided with a gas lifting pipe, The demisting device is arranged at the top of the desulfurizing tower, and the exhaust pipe is arranged at the top of the desulfurizing tower;
the flue gas pipeline is inserted above the liquid level of the tower kettle of the desulfurizing tower at an angle of 15 degrees downwards in the horizontal direction so as to prevent the desulfurizing slurry from flowing backwards into the flue gas pipeline;
the partition plate is positioned above the liquid level of the tower kettle and divides the space at the middle lower part in the desulfurizing tower into an upper sulfur dioxide absorption area and a lower calcium sulfite oxidation area, the flue gas enters the desulfurizing tower kettle and is in countercurrent contact with the spray liquid of the fourth spray device and then enters the upper sulfur dioxide absorption area of the desulfurizing tower through the riser, and the partition plate also has the function of preventing the desulfurizing slurry obtained after the first spray device and the second spray device absorb the sulfur dioxide in the flue gas from directly entering the tower kettle to cause the pH value of slurry in the tower kettle to be increased so as to be not beneficial to the oxidation of calcium sulfite in the tower kettle;
the sulfur dioxide absorption area absorbs sulfur dioxide in flue gas by the desulfurization slurry sprayed by the first spraying device and the second spraying device, and the formed desulfurization slurry is conveyed to a desulfurization slurry tank to prepare desulfurization slurry;
the spray pipe of the fourth spray device is higher than the inlet position of the flue gas pipeline;
the calcium sulfite oxidation zone is used for introducing waste sulfuric acid through a first conveying pipe to reduce the pH value and conveying oxidation air through a second conveying pipe to oxidize calcium sulfite;
the third spraying device is positioned in the calcium sulfite oxidation zone, spraying liquid of the third spraying device is conveyed through a liquid conveying pipe of the second spraying device, the third spraying device is connected with the calcium carbide slurry replenishing pipe, and calcium sulfate is generated by replenishing calcium carbide slurry to the third spraying device so as to neutralize waste acid in the calcium sulfite oxidation zone;
the fourth spraying device, the third spraying device, the second spraying device and the first spraying device are sequentially arranged from the bottom to the top of the tower, the fourth spraying device and the first spraying device are respectively conveyed with spraying liquid by independent circulating pumps, the third spraying device and the second spraying device are conveyed with spraying liquid by the same circulating pump, corresponding circulating pumps are respectively provided with a frequency converter capable of being linked, so that the mass ratio of spraying desulfurization slurry of the fourth spraying device, the first spraying device and the second spraying device is controlled to be 2:1:1, the spraying amount of the third spraying device is adjusted by the liquid level of a desulfurization slurry tank, and the sum of the calcium carbide slurry adding amount of the desulfurization slurry tank, the calcium carbide slurry adding pipe and the third spraying device is supplemented to a demister at the top of the tower, so that the materials in the sulfur dioxide absorption zone are balanced;
the fourth spraying device, the third spraying device, the second spraying device and the first spraying device respectively comprise a spraying pipe and a plurality of nozzles arranged on the spraying pipe, and the desulfurization slurry is uniformly distributed to each nozzle through the spraying pipe to be sprayed out and fully contacted with the flue gas flowing upwards in a counter-current manner so as to absorb sulfur dioxide in the flue gas;
(2) the desulfurization method of the carbide slag/slurry flue gas desulfurization system comprises the following steps:
preparing desulfurization slurry: taking the slurry in a sulfur dioxide absorption area above a clapboard of a desulfurizing tower as circulating slurry, adding carbide slurry into the circulating slurry to prepare the desulfurizing slurry, controlling the mass percent concentration of the carbide slurry in the desulfurizing slurry to be 20-30%, controlling the pH value of the desulfurizing slurry to be 7-8, and adding methyl hydrosilane oil or polysiloxane organosilicon antifoaming agent with the mass percent concentration of 1-5 per thousand into the carbide slurry;
and (3) circulation of the desulfurization slurry: conveying the desulfurization slurry from the desulfurization slurry tank to a second spraying device and a spraying device at the middle and upper parts of the desulfurization tower respectively by corresponding circulating pumps, enabling the desulfurization slurry to be in countercurrent contact with sulfur dioxide in the flue gas, absorbing the sulfur dioxide in the flue gas to generate calcium sulfite, enabling the desulfurization slurry to enter the desulfurization tower slurry tank through a tower outlet pipe arranged at the upper side of a partition plate of the desulfurization tower, and adjusting the pH value of the desulfurization slurry to be 7-8 by adding carbide slurry;
calcium sulfite oxidation: respectively introducing waste sulfuric acid and oxidizing air into the slurry in the tower kettle through a first conveying pipe and a second conveying pipe, and reducing the pH value of the slurry in the tower kettle to 5.0-6.5 through the waste sulfuric acid so that calcium sulfite is oxidized into calcium sulfate by the oxidizing air under the weak acid condition; if the pH value of the slurry in the tower kettle is more than 6.5, the oxidation of calcium sulfite to generate calcium sulfate is not facilitated; if the pH value of the slurry in the tower kettle is lower than 5, although the oxidation of calcium sulfite into calcium sulfate is facilitated, the unreacted sulfuric acid enters a subsequent dehydration system;
the fourth spraying device is used for conveying the desulfurization slurry in the tower kettle to a calcium sulfite oxidation area through a circulating pump arranged outside the desulfurization tower and is used for increasing the contact rate of oxidation air and calcium sulfite and the contact rate of unabsorbed calcium hydroxide and sulfuric acid;
the third spraying device sends the desulfurization slurry containing calcium sulfite and calcium hydroxide in the desulfurization slurry tank to the lower part of a partition plate of a desulfurization tower to absorb sulfur dioxide in the flue gas, and the redundant calcium hydroxide in the desulfurization slurry enters a calcium sulfite oxidation area to continuously react with the waste sulfuric acid to generate calcium sulfate; the third spraying device is connected with a calcium carbide slurry supplementing pipe and is used for automatically adjusting the pH value of the calcium sulfite oxidation area to 5.0-6.5 by supplementing the calcium carbide slurry;
conveying calcium sulfate: calcium sulfate discharged from the bottom of the tower kettle is conveyed to a dewatering system through a pump, and is conveyed to a cement plant as a raw material for producing cement after being dewatered;
flue gas purification and automatic control: the flue gas enters from the bottom of the desulfurizing tower kettle and is in countercurrent continuous contact with the spraying desulfurization slurry of the fourth, third, second and first spraying devices, and the desulfurization slurry absorbs SO in the flue gas2Generating calcium sulfite, and discharging the desulfurized flue gas after demisting.
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| CN112742196A (en) * | 2020-12-21 | 2021-05-04 | 安徽金禾实业股份有限公司 | Device and method for treating organic tail gas in high-salinity wastewater treatment |
| CN113898581B (en) * | 2021-09-30 | 2023-10-03 | 江苏昆仑互联科技有限公司 | Energy-saving control system and method for wet desulfurization Roots blower |
| CN114159945B (en) * | 2021-11-29 | 2024-03-12 | 内蒙古黄陶勒盖煤炭有限责任公司 | Wet flue gas desulfurization system and method |
| CN115259445B (en) * | 2022-07-12 | 2024-07-09 | 龙佰集团股份有限公司 | Treatment method of wet desulfurization spray liquid for inhibiting sulfur dioxide generation |
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