Method for improving desulfurization efficiency of high-sulfur coal type unit by utilizing desulfurization synergist

Abstract

The invention relates to the field of desulfurization with a desulfurization synergist, and discloses a method for improving the desulfurization efficiency of a high-sulfur coal type unit by using the desulfurization synergist, in a wet limestone-gypsum desulfurization process, a desulfurization system consists of an absorption tower system, a slurrying system and a dehydration system, the end equipment of the slurrying system is a limestone slurry tank, and the end equipment of the dehydration system is a dehydration system. The main function is to provide absorbent limestone slurry for an absorption tower system; an absorption tower system and a pulping system are both provided with pits, and a synergist is generally applied and is generally injected into an absorption tower through the pits of the absorption tower system; according to the invention, the adding point and mode of the synergist are changed, and the synergist is injected into the limestone slurry tank through the pit of the slurrying system, so that the dissolving speed of limestone is increased, the activity of calcium carbonate is enhanced, the chemical absorption of sulfur dioxide is accelerated, and the desulfurization efficiency is improved.

Description

Technical Field

[0001] The invention relates to the field of desulfurization with desulfurization synergist, and in particular to a method for improving the desulfurization efficiency of a high-sulfur coal unit by utilizing the desulfurization synergist. Background Art

[0002] As enterprises' awareness of clean production continues to increase, the control of sulfur dioxide concentration in flue gas is becoming more and more stringent. In the wet limestone and gypsum desulfurization process, limestone slurry and sulfur dioxide are usually reacted in the absorption tower to achieve the purpose of desulfurization. In enterprises in areas burning high-sulfur coal, the coal burning conditions are difficult to meet the needs of desulfurization equipment, which has exceeded the design treatment value of the absorption tower. They often reduce the operating load to meet the standard emission of net flue gas sulfur dioxide. The absorption tower has a high power consumption rate, the equipment is overloaded, and it cannot be effectively maintained and ages prematurely, increasing the cost of desulfurization production.

[0003] Traditional absorption towers enhance the desulfurization effect by adding synergists. Specifically, the synergist is injected into the pit at the bottom of the absorption tower at one time, and a circulating pump is used to spray the slurry directly after the injection. However, blindly increasing the amount of synergist used does not increase the desulfurization effect, but instead causes a waste of the synergist. Summary of the invention

[0004] The present invention aims to provide a method for improving the desulfurization efficiency of a high-sulfur coal unit by utilizing a desulfurization synergist, and the desulfurization effect is enhanced by changing the adding method of the synergist.

[0005] To achieve the above object, the present invention adopts the following technical scheme: a method for improving the desulfurization efficiency of a high-sulfur coal unit by using a desulfurization synergist, which is used in a desulfurization system, wherein the desulfurization system includes an absorption tower system and a pulping system, wherein the absorption tower system includes a pit, and the terminal equipment of the pulping system is a limestone slurry tank.

[0006] The pulping system includes a pulping area drainage pit, and a limestone slurry tank is used to provide absorbent and limestone slurry to the absorber system;

[0007] Set up synergist adding points, which include the first adding point and the daily adding point. The first adding point is located in the pit, and the daily adding point is located in the drainage pit in the pulping area.

[0008] The beneficial effects of this program are:

[0009] 1. The synergistic principle of the synergist is: the reaction rate of limestone and sulfur dioxide is controlled by the dissolution rate of limestone. Since the solubility of limestone in water is low, a large amount of limestone exists in the absorption tower in the form of tiny particles. There is a large double membrane resistance of air film and liquid film on the surface of these microspheres, which affects the transfer of sulfur dioxide. The synergist can weaken and eliminate the ability of the double membrane effect to promote the dissolution of limestone, effectively improve the activity of limestone, and accelerate the chemical absorption of sulfur dioxide.

[0010] The inventors have found through experiments that in the prior art, the synergist is directly added to the pit of the absorption tower system. Although it is convenient and quick, the synergist cannot immediately enter the spray layer of the absorption tower together with the limestone slurry to carry out absorption reaction in the absorption zone; instead, the synergist enters the spray layer for absorption reaction after mixing and circulating through the slurry pool of the absorption tower. Therefore, this method has a poor synergistic effect on desulfurization for the following reasons:

[0011] a. After the synergist enters the absorption tower, the CaCO 3 The content is relatively small, and it needs to be mixed with the gypsum slurry in the slurry pool before entering the slurry circulation pump to mix with the limestone slurry. Moreover, the mixing time is relatively short, and the synergist does not have enough time to weaken and eliminate the double-film effect, and the activity of the limestone is not increased in time, so the synergist cannot achieve the expected effect;

[0012] b. A large amount of synergist is added to the absorption tower at one time through the pit. In the early stage, the concentration of the synergist is high and the consumption is fast. However, since the limestone slurry is not added in large quantities at one time, the desulfurization effect is slightly improved. In the later stage, as the number of synergist recycling increases, part of the synergist is discharged from the absorption tower along with the gypsum generated by the reaction, the loss of the synergist increases, and the effect of the synergist is weakened, so that the synergist cannot achieve the best synergistic effect.

[0013] Experiments have shown that if the mixing time of the synergist and limestone slurry is prolonged and all of it is used to mix with CaCO 3 By directly reacting and changing the number of times and amount of synergist added, the desulfurization effect brought by the same synergist will be greatly improved. Even if the amount of limestone is reduced, the same effect as the existing technology can be achieved.

[0014] 2. However, if you want to increase the mixing time of the synergist and limestone slurry, you either need to increase the length of the pipeline for circulating the limestone slurry, or set up a separate mixing tank to fully mix the synergist and limestone slurry. These solutions require the existing structure to be dismantled and rebuilt, which is very expensive and requires shutdown for reconstruction, reducing industrial production capacity and causing great losses.

[0015] However, based on the idea of ​​reducing the transformation cost, the inventor changed his thinking and looked for a new location for adding the synergist. He looked for a suitable location along the upstream process, hoping to increase the mixing time of the synergist and the limestone slurry by using the longer distance (usually hundreds of meters) of the pipeline between the upstream process and the absorption tower. Following the upstream process of the limestone slurry, two synergist addition points can be quickly found: the limestone slurry tank in the pulping area and the drainage pit in the pulping area. After adding the synergist at these two locations, the synergist and the limestone slurry have sufficient mixing time.

[0016] 3. If you choose to add the synergist directly into the limestone slurry tank of the pulping system, since the synergist is in powder form, it is usually added manually once a day. After one day of use, the concentration of the synergist will decrease by 50-60%, so it is necessary to add it regularly every day to ensure that the synergist is maintained at a reasonable concentration; since the limestone slurry tank is relatively high (15 meters) and the transportation distance is long, it is impossible to add it multiple times a day, otherwise the labor cost will be too high; then the synergist, limestone slurry and water are stirred together, and there is no need to install a separate mixer and stirring tank. The synergist can be stirred using the mixer that comes with the limestone slurry tank, so it can quickly make CaCO 3 Dissolved; then, the enhancer will flow into the absorption tower together with a part of the limestone slurry. However, the limestone slurry added to the limestone slurry tank can only be mixed with the remaining enhancer in the early stage after entering the absorption tower. The mixing time of the limestone and enhancer added later is not extended.

[0017] If the operator chooses to add the synergist in the drainage pit of the pulping area, the operator can first simply stir the synergist and water to make the synergist and water preliminarily mixed, and then send part of the synergist and water into the limestone slurry tank for stirring according to the need of stirring the limestone slurry, and the synergist will not be consumed immediately. Next, after being stirred by the mixer, the synergist is further mixed with water and enters the absorption tower together with the limestone slurry; thereby ensuring that the mixing time of the synergist and the limestone slurry is always long enough; at the same time, since the concentration of the synergist is controllable, the concentration of the synergist can be controlled within the concentration range with the best synergistic effect according to the ratio of the synergist, water and limestone; after the synergist and water are mixed, they can be pumped into the limestone slurry tank together by a water pump, and the synergist is controlled by the water pump to enter the limestone slurry tank, which is convenient and quick, and does not require multiple manual transportation and addition.

[0018] 4. When the production line is just started, gypsum has not yet been produced. The first addition can still be made in the pit, which is convenient for stirring and can ensure that the synergist quickly reaches the required concentration. In the later stage, the synergist can be added to the pulping area pool every day; the synergist to be added daily is piled next to the drainage pit in the pulping area, and the emergency spare synergist is placed next to the pit of the absorption tower system, separated from each other for management, so that in case of emergencies such as increased sulfur content, a large amount of synergist can be added to the pit for emergency.

[0019] Furthermore, the synergist is put into the pit for stirring at one time, and the synergist and limestone slurry enter the absorption tower together for circulation.

[0020] Furthermore, the ratio of the amount of the synergist added for the first time to the amount of the absorber slurry is 2000:1.

[0021] Furthermore, the synergist is periodically put into the drainage pit of the pulping area for stirring, and the synergist and water are put into the limestone slurry tank for stirring.

[0022] Furthermore, the daily addition amount is calculated as: Q 常 =Q 石 ×0.25%.

[0023] Furthermore, when the sulfur content in the absorption tower suddenly increases, a synergist is added to the pit in a sudden manner, and the single sudden addition amount of the synergist is less than 500 kg. At the same time, the limestone slurry tank suddenly supplies limestone slurry to the absorption tower until the pH value in the absorption tower returns to the level before the sudden increase in sulfur content.

[0024] This solution also has the following effects:

[0025] 1. The daily addition method in this scheme is: the amount of synergist added is calculated every day according to the actual sulfur content. Since the sulfur content is difficult to calculate, the role of the synergist is to help dissolve the limestone. The synergist will not be consumed by the reaction. Its loss mainly comes from wastewater discharge, gypsum carryover, and flue gas water carryover. Therefore, the consumption is relatively small and can be effectively supplemented while supplying slurry. The amount of slurry supply can be counted by the limestone consumption.

[0026] Therefore, the amount of synergist added is calculated based on the amount of limestone added, and then the amount of synergist and water added is controlled by a water pump in the drainage pit in the pulping area to ensure that the concentration of the synergist is maintained in the optimal range.

[0027] 2. Since the concentration of the synergist is maintained in the optimal range, the limestone dissolution efficiency is higher, and the proportion of limestone discharged with gypsum without reaction is less. Therefore, for the desulfurization of the same amount of sulfur, less limestone solution is required, thereby using less electricity, thereby achieving the purpose of saving electricity.

[0028] 3. Compared with the drainage pit in the pulping area, the ground pit is closer to the absorption tower. Therefore, when an emergency occurs, such as a slurry circulation pump failure or a slurry supply pipeline failure, or a sudden increase in sulfur content causing the outlet to exceed the standard or limit the load, an emergency synergist can be added to the ground pit based on the outlet net smoke sulfur content, and the slurry supply and pH value can be kept unchanged in time. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1This is an overall schematic diagram of the desulfurization system of Example 1;

[0030] Figure 2 This is a schematic diagram of the pulping area of ​​Example 1;

[0031] Figure 3 This is a schematic diagram of the pit in Example 1. DETAILED DESCRIPTION

[0032] The following is further described in detail through specific implementation methods:

[0033] The figure marks in the drawings of the specification include: absorption tower system 1, absorption tower 11, pit 12, pit agitator 13, slurry pump 14, circulation pump 15, pulping system 2, pulping area drainage pit 21, puddle agitator 22, pulping water 23, water pump 24, limestone slurry tank 25, limestone slurry tank agitator 26, first addition point 31, daily addition point 32.

[0034] Example 1

[0035] Example 1 is basically as Figure 1-3 As shown: A method for improving the desulfurization efficiency of a high-sulfur coal unit by using a desulfurization synergist.

[0036] Prepare a desulfurization system, which includes a pulping system 2 and several absorption tower systems 1. The absorption tower system 1 includes an absorption tower 11. A pit 12 is provided at the bottom of the absorption tower 11. To facilitate the display of the pit 12, Figure 1 In the figure, the lead-out pit 12 is shown separately.

[0037] like Figure 2 As shown, the pulping system 2 includes a pulping area drainage pit 21 and a limestone slurry tank 25. The pulping area drainage pit 21 contains pulping water 23. A puddle agitator 22 and two water pumps 24 are installed in the pulping area drainage pit 21. The puddle agitator 22 can be a low-power agitator that can achieve the effect of manual mixing. The two water pumps 24 are respectively connected to the two limestone slurry tanks 25. Figure 2 Only an enlarged schematic diagram of one of the limestone slurry boxes 25 is shown. A limestone slurry box agitator 26 is provided in each of the limestone slurry boxes 25. The limestone slurry enters the limestone slurry box 25 and is mixed and stirred with water to further dissolve the limestone in the water.

[0038] The absorption tower system 1 includes an absorption tower 11 and a plurality of slurry pumps 14. A limestone slurry tank 25 is connected to the absorption towers 11 of the plurality of absorption tower systems 1 at the same time, and the limestone slurry is pumped to the absorption tower 11 for desulfurization through the plurality of slurry pumps 14. Figure 1 Only an enlarged schematic diagram of one absorption tower 11 is shown.

[0039] A pit 12 is provided at the bottom of the absorption tower 11. The slurry after the reaction in the absorption tower 11 enters the pit 12. A pit agitator 13 and a circulation pump 15 are provided in the pit 12. The circulation pump 15 pumps the slurry in the pit 12 back into the absorption tower 11.

[0040] Set up the synergist adding points, which include the first adding point 31, the surprise adding point and the daily adding point 32, such as Figure 2 As shown, the first addition point 31 is located at the pit 12. The first addition method of the first addition point 31 is: put the synergist into the pit 12 at one time and stir it. The synergist and the limestone slurry enter the absorption tower 11 together for circulation. The ratio of the synergist to the slurry in the absorption tower 11 is 2000:1.

[0041] like Figure 3 As shown, the daily addition point 32 is located in the pulping area drainage pit 21; the daily addition method of the daily addition point 32 is: regularly put the synergist into the pulping area drainage pit 21 for stirring every day, and the synergist and water are put into the limestone slurry tank 25 for stirring. The calculation formula of the daily addition amount is:

[0042] Qchang=Qshi×0.25%.

[0043] The first addition point 31 and the sudden addition point are at the same position. When the sulfur content in the absorption tower 11 suddenly increases, the synergist is suddenly added to the pit 12. The single sudden addition amount of the synergist is less than 500 kg. At the same time, the limestone slurry tank 25 suddenly supplies limestone slurry to the absorption tower 11 until the pH value in the absorption tower 11 returns to the level before the sulfur content suddenly increases.

[0044] Comparative experiment 1:

[0045] Experimental conditions: According to this embodiment, three groups of comparative experiments were conducted under the same working conditions, the difference being that the daily addition amount was different. Each experimental group was conducted for 5 days, with experimental group 1 conducted first and experimental group 2 conducted later. The sulfur content of the exhaust gas, the amount of synergist added and the amount of limestone consumed were recorded every day.

[0046] Experimental group 1: Calculate the daily addition amount based on the stone consumption of the previous day; Q 常 =Q 石 ×0.2%; for the convenience of addition, it is calculated based on a bag of synergist of 25kg and rounded up to the whole bag number.

[0047] Experimental Group 2: After the end of Experimental Group 1, the daily consumption and product output of the materials were maintained the same as the first day of Experimental Group 1 for three consecutive days, and then Experimental Group 2 was started. The daily consumption and product output of the materials in Experimental Group 2 were maintained the same as those in Experimental Group 1. The daily addition amount was calculated based on the total consumption of the synergist in Experimental Group 1 for 5 days, and the daily addition amount Q was set to be equal:

[0048] Q 定 =∑Q 常i / 5;

[0049] Q 常i - Daily supplementation amount on day i of experimental group 1, where i = 1, 2, 3, 4, 5;

[0050] In experimental group 2, the packaging bags of the enhancer were directly opened and accurately dosed according to the calculated daily addition amount Q, without converting it into the number of whole packages.

[0051] Experimental results:

[0052]

[0053] The average sulfur content of the exhaust gas of experimental group 1 is 301.6 mg / Nm 3 The average sulfur content of the exhaust gas in experimental group 2 is 308.6 mg / Nm 3 Compared with experimental group 2, experimental group 1 can reduce the sulfur content of exhaust gas by 2.26% only by changing the daily addition amount, which is a significant effect. When the daily addition amount is calculated according to the limestone consumption, the desulfurization effect is better.

[0054] Example 2

[0055] Example 2 is a method for determining the daily addition position of a synergist, which is applicable to Example 1 and comprises the following steps:

[0056] Step 1: determine the adding position of the upstream production line of the absorption tower 11 where the synergist can be added, and form a position library;

[0057] Step 2: determine the pipe length between the adding position and the nearest agitator, and delete the adding position with a pipe length greater than fifty from the position library;

[0058] Step 3: Use the control variable method to set up a comparative experiment, where the quantitative value is the amount of synergist added, the variable is the adding position in the position library, and the existing adding position is used as the variable of the comparative group. In this embodiment, the existing adding position is the pit 12; the output values ​​of the experimental results are: whether the power consumption, limestone consumption and exhaust gas meet the standards;

[0059] Step 4: Determine the best adding position according to the experimental results, analyze the reasons according to the experimental results, and design an improvement plan based on the best adding position.

[0060] Comparative Experiment 2: Experimental conditions: Two adding locations were determined: the drainage pit 21 in the pulping area of ​​the pulping system 2 and the limestone slurry tank 25, and three groups of comparative experiments were set up; the experiment was conducted for a total of three days, a certain amount of synergist was added every day, and the data was recorded once a day. The power consumption was characterized by the power consumption rate, that is, the percentage of the power consumption of the desulfurization system to the total power generation of the production line.

[0061] Experimental group 1: the drainage pit 21 in the pulping area was the daily addition location; Experimental group 2: the limestone slurry box 25 was the daily addition location; Control group: the pit 12 was the daily addition location.

[0062] Test results:

[0063]

[0064] Therefore, when the pulping area drainage pit 21 is used as the daily addition location, the power consumption and limestone consumption are minimized.

[0065] The above is only an embodiment of the present invention, and the common knowledge such as the known specific technical solutions and / or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for improving the desulfurization efficiency of a high-sulfur coal unit by using a desulfurization synergist, which is used in a desulfurization system, wherein the desulfurization system includes an absorption tower system and a pulping system, wherein the absorption tower system includes a pit, and the terminal equipment of the pulping system is a limestone slurry tank, and is characterized in that: The pulping system includes a pulping area drainage pit, and a limestone slurry tank is used to provide absorbent and limestone slurry to the absorber system; Set up synergist adding points, which include the first adding point and the daily adding point. The first adding point is located in the pit, and the daily adding point is located in the drainage pit in the pulping area.

2. The method of improving the desulfurization efficiency of a high-sulfur coal unit by using a desulfurization synergist according to claim 1, characterized in that: The first addition method of the first addition point is: put the synergist into the pit and stir it at one time. After stirring, the synergist enters the absorption tower for circulation.

3. The method of improving the desulfurization efficiency of a high-sulfur coal unit by using a desulfurization synergist according to claim 2, characterized in that: The ratio of the first added synergist to the absorber slurry is 2000:

1.

4. The method of improving the desulfurization efficiency of a high-sulfur coal unit by using a desulfurization synergist according to claim 3, characterized in that: The daily addition method of the daily addition point is: regularly put the synergist into the drainage pit in the pulping area for stirring, and the synergist and water are put into the limestone slurry tank for stirring.

5. A method for improving the desulfurization efficiency of a high-sulfur coal unit by using a desulfurization synergist according to claim 4, characterized in that: The calculation formula for daily addition is: Q 常 =Q 石 ×0.25%。 6. The method of improving the desulfurization efficiency of a high-sulfur coal unit by using a desulfurization synergist according to claim 5, characterized in that: When the sulfur content in the absorption tower suddenly increases, a synergist is added to the pit in a sudden manner. The single sudden addition amount of the synergist is less than 500 kg. At the same time, the limestone slurry tank supplies limestone slurry to the absorption tower in a sudden manner until the pH value in the absorption tower returns to the level before the sudden increase in sulfur content.

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