"Blocking tower" - common diseases and solutions of desulfurization tower

Desulfurization tower is a tower type equipment for desulfurization of industrial waste gas. Initially, granite masonry is the most widely used in desulfurization towers, which use the principle of water film desulfurization and dust removal, also known as granite water film desulfurization dust collector, or hemp stone water film desulfurization dust collector. The advantage is that it is easy to maintain and can achieve the effect of both dust removal and desulfurization (denitrification) by formulating different dust removal agents. With the development of FRP technology, desulfurization towers are gradually changed to be made of FRP. Compared with granite desulfurization tower, FRP desulfurization tower has low cost, easy processing, no rust, no rotten, light weight, so it becomes the future development trend of desulfurization tower. In addition, 316L stainless steel has three major advantages of corrosion resistance, high temperature resistance and wear resistance, is also one of the important trends in the development of desulfurization tower. After years of improvement, has developed into venturi type, cyclone plate type, cyclone column type, float type, sieve plate type, pneumatic emulsification type and other types of desulfurization tower, equipment technology is becoming increasingly mature, each has its own advantages and shortcomings, enterprises can choose different types according to their own needs.

The problem of "tower blockage" is a frequent problem in the use of desulfurization towers; the rising resistance of desulfurization towers and the occurrence of gas with liquid in serious cases is an inevitable problem of desulfurization systems and a common concern in the desulfurization industry. Although with the development of catalyst technology, many new catalysts have been equipped with the function of removing sulfur blockage, making the problem of tower blockage alleviated, but due to the process conditions of each enterprise, operation and management, etc., the problem of tower blockage is still the focus of attention in the desulfurization industry. I make up today and you all to talk about this topic

Speaking of tower plugging, mainly divided into sulfur plugging and salt plugging, the reasons for this, mainly in the following areas:

1. into the desulfurization tower gas composition is not good, the impurity content is high? (such as fly ash, coal tar and other solid particles)? into the packing layer blockage.

2, desulfurization tower in the desulfurization reaction, also accompanied by the occurrence of oxidation regeneration precipitation sulfur reaction, if the precipitation of sulfur (especially when the entrance H2S content is high) can not be brought out of the desulfurization tower with the desulfurization liquid in a timely manner, it is easy to filler surface, resulting in local blockage, partial flow, the formation of blocking tower in serious cases.

3, desulfurization tower spraying density is not enough. General requirements in 50 ~ 60m3/m2?/span>h, lower spray density will not only make the tower filler easy to form a dry area, resulting in sulfur plugging, and will greatly reduce the degree of purification of desulfurization tower. Especially for the larger diameter of the tower, must ensure sufficient amount of poor liquid.

4, the amount of regeneration air is not enough, blowing air strength is low (generally required in 50 ~ 80?m3/m2?/span>h) or regeneration equipment mismatch, this phenomenon is bound to cause regeneration tank sulfur foam flotation difficulties, so that the poor liquid in the suspended sulfur is higher, if the long operation is easy to form a plug tower.

5, desulfurization tower of the desulfurization equipment structure itself has problems. Such as improper selection of packing or tower liquid distributor, redistributor structure or installation is not reasonable, this phenomenon is easy to make the solution bias flow or distribution tank itself to accumulate sulfur and cause blocking tower.

6, the secondary reactants generated by the high concentration of various substances salts, low temperature precipitation to block the tower, under normal working conditions, especially for the better management of the manufacturers (the site does not have any run, bubble, drip, leak), desulfurization solution in the secondary salt increase is understandable, because the desulfurization solution in the absorption of H2S reaction process, accompanied by the occurrence of secondary reactions, which is inevitable, when the secondary salt increase, to take timely measures (discharge or induce partial cooling crystallization precipitation) to prevent salt blockage. Heating information network to understand as to how much content for exceeded, each enterprise due to different working conditions, the specific indicators are different. We believe that the salt should not exceed 250g / L, especially the content of Na2SO4 in the solution generally does not exceed 40 g / L, this exceeds the standard is not only the problem of salt plugging and the important thing is to cause serious corrosion of equipment.

7, molten sulfur production management awareness, by the heat supply steam tension, stop soluble sulfur equipment operation, or improper operation or molten sulfur device itself has problems, resulting in residual liquid entrained sulfur particles and foam increase, without precipitation, filtration, separation processing and return to the system, and finally brought to the tower plugging filler.

8, desulfurization liquid components control improperly, such as quebracho, vanadium ratio is out of balance, the formation of S-O-V precipitation, or quebracho pretreatment improperly, fill into the system, etc.. Resulting in increased particle size of desulfurization liquid, making it easier for sulfur to hang on the filler.

9, the impact of water quality. Some companies make up hard water, or other hard water into the sedimentation tank, into the system, the formation of calcium, magnesium, salt blockage.

10, improper choice of catalyst, we know that different types of catalysts in the catalytic oxidation process plays a different role, especially after the oxidation of the formation of monomeric sulfur crystal structure is not the same, its viscosity and particle size is not the same, if its own precipitation of monomeric sulfur viscosity is relatively large, in the tower precipitation of sulfur adhesion in the filler or distributor, must be carefully considered, do not lose sight of the other.

11, desulfurization tower defoamer accumulation of sulfur blockage. This blockage is often overlooked by enterprises, but also the least likely to be measured. General manufacturers in the determination of the resistance of the desulfurization tower, only to determine the differential pressure in and out of the tower. Of course, some manufacturers can also measure the differential pressure of each section of the packing. Generally found a section of the packing differential pressure, will determine a section of the packing or distributor blocked. I do not know when the cause of the defoamer blockage, on the one hand, is not cleaned for a long time, on the other hand, gas foam entrapment serious, thus causing the accumulation of sulfur blockage.

The factors that cause tower blockage are many and complex, but the various types of blocked towers are carefully analyzed. There are always traces and traces to be found. I summarize the reasons and some of the following:

(1) the catalyst is not applicable or improper dosage, poor efficiency of oxidation regeneration, can not meet the process requirements, suspended sulfur and high by-salt content, desulfurization liquid long-term vicious cycle.

(2) Long-term overload operation of the system, process conditions do not adapt, desulfurization, regeneration, sulfur recovery of the three major production links out of tune, imbalance, out of control, resulting in high suspended sulfur and by-salt content, desulfurization liquid long-term vicious cycle.

(3) desulfurization tower function is not enough or desulfurization pump function is not enough, resulting in low liquid to gas ratio, tower spraying density is not enough, packing section to form a semi-dry area or dry area.

(4) packing tower structure is not reasonable or installation is not standardized, resulting in uneven distribution of liquid and gas, the formation of partial flow, ditch flow, wall flow, etc., packing section to form a semi-dry area or dry area.

(5) filler selection is not applicable or filling unreasonable, the total amount of too much, single section is too thick, small void rate, especially the structure of serious liquid stagnation type filler, after the operation of the tower resistance will be significantly high.

(6) filler broken or deformed, especially the regular grille filler dumping or deformation, tower resistance will soon increase, and even production is difficult to maintain.

(7) tower before the configuration of electrostatic dust removal equipment or its function is not enough, the process gas quality is poor, high tar content, dust and other impurities.

(8) tower before the configuration of gas washing cooling equipment or its function is not enough, high temperature liquid temperature, can not meet the process requirements, low desulfurization efficiency, poor efficiency of oxidation regeneration, precipitation of small particles of singlet sulfur, suspended sulfur and high by-salt content.

(9) tower top distributor or inter-segment distributor, insufficient opening rate or small aperture, small diameter or height of the gas pipe and installation is not standardized, the instantaneous load change when the load is high pressure, often forming a tower system to stop the liquid, the liquid level suddenly rise into the gas pipe increase resistance phenomenon.

(10) flat tower plate open hole rate is insufficient or small aperture; full open hole or partial open hole hump type tower plate valley bottom, it is more likely to cause the accumulation of sulfur accumulation of salt accumulation of impurities blockage.

(11) tower top configuration of gas-liquid separation device, especially screen-type defoaming device is easier to clog, while measuring tower resistance or parking clear tower, often be ignored.

(12) regeneration tank volume is small or regeneration pump function is not enough, the efficiency of oxidation regeneration is poor, can not meet the process requirements, poor quality of poor liquid, desulfurization liquid long-term vicious cycle.

(13) The structure of regeneration tank is unreasonable, the opening rate of distribution orifice plate is not enough or the aperture diameter is small, easy to block, resulting in large internal resistance at the bottom of the tank, affecting the air intake, if the aperture diameter is large, the liquid surface tumbles seriously, and the monomeric sulfur is not easy to polymerize flotation. Poor liquid outlet to the sulfur foam overflow weir level difference is not enough, will bring the sulfur foam into the poor liquid tank, resulting in poor quality of poor liquid, high suspended flow content.

(14) Insufficient function of the injector or unreasonable assembly layout, the amount of inhaled air is insufficient or unevenly distributed, the efficiency of oxidation and regeneration is poor, or the local liquid surface tumbling is serious, and the monomeric sulfur is difficult to polymerize flotation from the liquid phase, resulting in poor quality of the poor liquid and high content of suspended sulfur.

(15) pressure tube nozzle blockage, uneven spray density, resulting in semi-dry area or dry area of the packing section.

(16) sulfur recovery filtered filtrate or molten sulfur residue, recovery of pre-treatment is not up to standard, high liquid temperature, impurities, affecting absorption and regeneration, resulting in poor quality residual liquid, high content of suspended sulfur.

(17) Poor quality of absorbent, many impurities, many catalyst residues, especially quebracho method desulfurization, unsuitable gum vanadium ratio, incomplete pretreatment, cooked quebracho inclusions, resulting in poor efficiency of oxidation regeneration, large viscosity of desulfurization liquid, poor quality of poor liquid, high suspended sulfur content.

(18) The system adds or reduces the load frequently, and the desulfurization liquid is also added or reduced, or a longer period of low-load and low-liquid production, which also easily causes the semi-dry area or dry area of the packing section.

(19) Process conditions are not suitable, process management is not in place. Process operation is not standardized, the operation is arbitrary. Small problems can accumulate into big problems.

(20) multi-solute solubility in the desulfurization liquid, compared to its single solubility in water, are reduced to varying degrees, therefore, the concentration of high or low solubility of the sub-salt, in the case of low liquid temperature, often form a mixed supersaturated precipitation crystals and blocking the tower, a manufacturer of variable off system winter parking, overnight and then drive, the occurrence of vicious "tower obstruction ", forced to pass steam heating and delayed driving.

Summarized so many reasons, then how to solve the problem?

Yi Xiaobian knocking time again ~ bang ~ bang ~ bang

Desulfurization tower blocking tower solutions:

(1) do a good job of gas into the tower before the purification, gas into the tower before washing and dust removal and electrostatic decoking, and strengthen the separation of gas and water to prevent coal tar, fly ash and other debris brought into the desulfurization system.

(2) seriously find the root cause of blocking tower, is the equipment design and installation problems, find opportunities for technical transformation, such as desulfurization tower in the filling and selection of filler, it is appropriate to fill according to three layers, each layer height 5-6 meters, the total height of the filler 15-18 meters, filler to bulk polypropylene ￠ 50-70㎜ as the main, the lower section of the filler should choose large specifications to prevent blocking; gas-liquid distributor, redistributor, defoamer and other components design should be Reasonable, gas-liquid distribution surface should be appropriate; filler bracket more hump plate, the enterprises more or less have happened hump blockage, serious hump slot is blocked full, had to stop to clean the filler, it is recommended that the hump plate into a lattice plate; oxidation regeneration tank should be set up 1-2 layers of distribution plate, the role of the pore plate is to make the gas-liquid mixture through the pore plate and then stirred by mixing, in order to facilitate regeneration efficiency, aperture is too large, mixing stirring effect Weakening; to ensure the quality of maintenance, in the tower after the packing raking out, should be a comprehensive inspection of the tower, found that the problem is dealt with in a timely manner.

(3) strict control of process indicators, good regeneration tank sulfur foam flotation and overflow, regeneration pressure (generally in 0.40-0.45MPa), and liquid level to be stable, to prevent large fluctuations and the precipitation flooding into the tower; control the regeneration temperature, regeneration temperature is too high, the secondary reaction is accelerated, resulting in more salt, salt crystallization, resulting in blocking the tower.

(4) to ensure sufficient circulation and spray density, so that the accumulation of sulfur attached to the surface of the packing to get flushed, reduce production, it is not appropriate to adjust the amount of circulation, should be used to reduce the total alkalinity of the solution as a means. Pay attention to molten sulfur recovery and processing, molten sulfur residue to be precipitated, filtered, cooled, oxidized and impurities will be removed before returning to the system.

(5) Use high quality catalysts. Due to the special chemical structure of the catalyst and has a very strong oxygen absorption capacity, in the process of desulfurization, constantly release a very strong activity of the atomic state of oxygen, can quickly convert H2S and part of the organic sulfur into monomersulfur, thus greatly improving the efficiency of desulfurization, removal of organic sulfur up to 50% or more, oxidation and regeneration of sulfur particles precipitated large, easy to separate recovery, so that the viscosity of the desulfurization solution to reduce the suspended sulfur, the solution Clear. In addition, the quality of the catalyst can not only adsorb oxygen, oxygen activation, but also the formation of polysulfide, polysulfide compounds are regenerated will precipitate sulfur, so that the solution of suspended sulfur gradually reduced, the filler adhered to the sulfur also gradually slacken down, so it has a certain role in cleaning the tower.

(6) after the tower blockage, resistance rose, out of the tower gas with liquid phenomenon processing. According to the author's many years of experience in operation and management, on the one hand, can increase the amount of circulation to flush the tower, on the other hand, can add a certain amount of vegetable oil to eliminate the tower deposited on the filler sulfur bubble and accumulation of sulfur, general vegetable oil once added in the amount of 200-300mL is appropriate, add too much, then in the tower resistance down, desulfurization efficiency will be reduced, mainly because the vegetable oil is a polymer organic compounds, is a kind of defoaming substance. Special attention should be paid to the addition of vegetable oil to clean the tower during the period, sulfur bubbles will increase in large quantities, it is advisable to strengthen the regeneration tank sulfur bubble flotation, to ensure normal overflow, and at the same time to strengthen the recovery of molten sulfur work.

To sum up, there are many reasons for the blockage of the desulfurization tower, to carefully find the causes, the right remedy, to take effective measures to solve the problem at its root, I hope that the content of today's I can help you to solve the fundamental problem of the old man. If you say something wrong, welcome to correct! If you have a different opinion, welcome to give Yi Xiaobian message comments, we discuss together! If you like the content of Yi Xiaobian, welcome to comment praise plus attention Oh!