CN112076620A

CN112076620A - Dry desulfurization and denitrification system adopting hollow fiber membrane dust collector

Info

Publication number: CN112076620A
Application number: CN202010988635.2A
Authority: CN
Inventors: 郭绍华; 程旭滨; 吴绍海
Original assignee: Guangdong Fenghe Clean Engineering Co ltd
Current assignee: Guangdong Fenghe Clean Engineering Co ltd
Priority date: 2020-09-18
Filing date: 2020-09-18
Publication date: 2020-12-15

Abstract

A dry desulfurization and denitrification system adopting a hollow fiber membrane dust remover. In particular to an improved form of an SDS dry desulfurization and SCR low-temperature denitration system. The essence of the method is that a hollow fiber membrane dust collector replaces a commonly-used bag-type dust collector in the existing SDS dry desulfurization and SCR low-temperature denitration system, and the filtering precision is improved by 2-3 orders of magnitude, so that the efficiency of dry desulfurization and denitration is greatly improved, and a large amount of catalysts are saved.

Description

Dry desulfurization and denitrification system adopting hollow fiber membrane dust collector

Technical Field

A dry desulfurization and denitrification system adopting a hollow fiber membrane dust remover. In particular to an improved form of an SDS dry desulfurization and SCR low-temperature denitration system.

Background

An SDS dry desulfurization and SCR low-temperature denitration system is a novel comprehensive system technology for removing sulfur oxides, nitrogen oxides and dust in flue gas, and main components of the system are a desulfurizer supply device, a bag-type dust remover and an SCR low-temperature denitration device. CN 208066118U is a typical such system. The working principle is that sodium-based fine powder such as sodium bicarbonate or calcium-based fine powder such as calcium carbonate or both of the sodium-based fine powder and the calcium carbonate are sprayed into a flue gas channel or a reactor, so that a desulfurizing agent is mixed with flue gas and reacts with sulfide, hydrogen chloride and the like in the flue gas, then the flue gas enters a bag-type dust remover, dust in the flue gas and the desulfurizing agent are gradually deposited on the surface of a bag due to the obstruction of the bag to form a powder cake layer, the powder cake layer is a fixed bed, the flue gas continuously reacts on the fixed bed, the sulfide and the hydrogen chloride in the flue gas are acted by the desulfurizing agent to generate sulfate and calcium sulfate, and the sulfate and the calcium sulfate are discharged from an ash discharge port of the bag-type dust remover. The flue gas without most of oxysulfide and chloride enters the next stage of denitration link. The main working media in the SCR low-temperature denitration link are a low-temperature catalyst and a denitration reducing agent, and are mature technologies and are not described any more.

In the traditional SDS dry desulfurization and SCR low-temperature denitration system, the bag-type dust remover plays the roles of reaction, dust removal and fixed bed.

Due to the various advantages of this technique, a great number of applications are obtained, but there are two prominent drawbacks:

firstly, a bag-type dust remover is used in the existing SDS dry desulfurization and SCR low-temperature denitration system. The bag-type dust collector relies on the filter cake to form filter precision, that is to say, dust is filtered by dust, and for fine dust, a bag is only a carrier for loading the filter cake. When the powder cake is too thick and the wind resistance is too large, the powder cake is blown down by using the reverse blowing airflow, and a new powder cake is regenerated. The time before the new powder cake is generated is an interval with the lowest efficiency of the bag-type dust collector, and in the time, the dust filtering efficiency is lowest, and a large amount of desulfurizer dust which is loaded with oxysulfide and has not yet reacted penetrates through the pores of the bag; on the other hand, as the 'fixed bed' is not formed, and the reaction condition to the gas is not formed, a window period that the sulfur oxide directly penetrates through the bag-type dust remover is formed; thirdly, generally, the average filtering precision of the bag-type dust collector is from 5 to 30mg/m and the highest from 2 to 10mg/m, the formed fixed bed has low pore density, the contact surface of sulfur-containing gas is insufficient, and the efficiency of gas interception is not high. Fourthly, for the same reason, the bag-type dust collector has very low capability of intercepting dust particles with the particle size of less than 0.1-1 um, and the desulfurizing agents with the particle size of just small size have the largest specific surface area and the strongest capability of absorbing and reacting sulfur oxide gas. The four reasons for this are that the desulfurization efficiency of the system is usually only 70-85%, and it is difficult to obtain higher desulfurization efficiency.

And secondly, in the SCR low-temperature denitration link adopted by the existing SDS dry desulfurization and SCR low-temperature denitration system, a catalyst is used. The catalyst has three natural enemies: dust coverage, abrasion, alkaline metal poisoning. Because the filtration precision of the bag-type dust collector used at the front stage is only 2-30 mg/m for carrying out heavy year, the dust coming into the lower stage is 20mg/m for carrying out heavy year, the dust leaked by 100 ten thousand m/h for carrying out heavy year is 20kg/h, and 160 tons in one year is close to the weight of the catalyst. Dust coverage, abrasion are unavoidable and even quite severe. In addition, the alkaline metals in the flue gas exist in a dust state, and the alkaline metals reaching the catalyst all pass through the bag-type dust remover. Catalyst poisoning causes insufficient denitration efficiency and excessive catalyst loss.

In a word, the two defects can be summarized into the same problem, namely that the treatment precision of the bag-type dust remover in the system is not enough. If the filtering precision of the dust remover can be improved by 10-1000 times compared with the existing bag-type dust remover, the filtering precision reaches 0.001-0.1 mg, and the dust remover is not influenced by a back flushing period and always keeps stable, the two defects can not exist, and the efficiency of the SDS dry desulfurization and SCR low-temperature denitration system can be greatly improved. The solution is to find a better dust remover to replace a bag-type dust remover in the existing system.

The hollow fiber membrane is a new technology for treating high-dust and high-pollution flue gas. Compared with an electrostatic dust collector, a filter cartridge type dust collector and a cloth bag type dust collector, the filter has the outstanding advantages that the initial filter aperture is 0.1 micron; the thickness of the film is about 0.5mm, which is 50-100 times of the thickness of a film used on the film-coated cloth bag, so that the wear resistance and the service life are greatly improved; the change of the filtration efficiency before and after back flushing is very small, namely, the intrinsic filtration efficiency of the hollow fiber membrane is far higher than that of a cloth bag and is basically unrelated to the powder cake; the specific surface area is far larger than that of the cloth bag, so that the length of the membrane component with the same diameter and the same filtering area is only 5-6 times of that of the cloth bag, and the steel consumption of the cabinet is greatly reduced; the weight of the filter material is only 3-5 times of that of the filter material, so that the using amount of the tetrafluoro is greatly reduced, and the cost is greatly reduced. Therefore, the hollow fiber membrane dust collector is the best choice for replacing a bag-type dust collector in an SDS dry desulfurization and SCR low-temperature denitration system.

Since 2014, the group of gushao hua has been studied and practiced in this field, completing an on-site 40 m-th online inspection in 2019; carrying out one-year experiment in a 4000 m-year/h lead cigarette processing system in a doubling manner; and the industrial application project of the lead fume treatment of the 50000 m/h lead melting pot is completed in 8 months in 2020. The dust treatment effect reaches less than 1ug/m, and dust particles with the particle size of 0.3um are stable in the level of less than 1800 grains/L on average for a long time.

The inspiring experiment is an online replacement engineering project of 5000m high-speed/h high-speed bag-type dust remover in a medical waste treatment plant in a certain city in 9 months in 2020.

After the bag-type dust collector is switched to the hollow fiber membrane dust collector on line, the dust emission is gradually reduced from 6mg/m, the dust accumulated in the pipeline is gradually washed, and 30-50 ug/m cultivation is gradually approached. And reduced to 5 ug/m by day 2. Surprisingly, sulfur dioxide and hydrogen chloride emission values drop steeply within the first few minutes of online switching from the bag-type dust collector to the hollow fiber membrane dust collector, and the average 30-50 mg/m thin film cultivation is reduced to 3-5 mg/m thin film cultivation within a few minutes, and then the long-term stability is realized.

Through further observation, test and data analysis of the new system, the inventor realizes that the dust removal rate can be improved by 1000 times by only replacing the bag-type dust remover with the hollow fiber membrane dust remover on the premise of not changing the basic technological process and parameters of SDS dry desulphurization, the desulphurization efficiency can be greatly improved, and most heavy metals can be intercepted. After the activated carbon powder spraying device is additionally arranged, most dioxin can be intercepted. The system is expected to become a comprehensive system which can greatly improve the processing performance of dust, sulfide, nitride, heavy metal and dioxin.

Disclosure of Invention

Based on the findings and theoretical derivation of the experimental tests, the invention aims to provide an improved scheme aiming at various problems of the existing SDS dry desulfurization and SCR low-temperature denitration system. The core of the content of the invention is as follows: a hollow fiber membrane dust remover is used for replacing a bag-type dust remover in the existing SDS dry desulfurization and SCR low-temperature denitration system to form a novel comprehensive system for removing dioxin by the SDS dry desulfurization, the SCR low-temperature denitration system and the active carbon, wherein the hollow fiber membrane dust remover is used as a microgram-level dust removal, desulfurization reaction and fixed bed link.

The utility model provides an adopt dry process SOx/NOx control system of hollow fiber membrane dust remover which characterized in that: a dry desulphurization link is formed by a flue gas inlet pipe (2), a reactor (1), a sodium-based desulphurization powder supply device (3), a calcium-based desulphurization powder supply device (4), an activated carbon powder supply device (5) and a hollow fiber membrane dust remover (6); the SCR denitration process comprises a hollow fiber film dust remover (6), a denitration reducing agent supply device (8), a denitration reactor (9) and a catalyst (10) to form an SCR denitration link; a hollow fiber film dust remover (6) and an active carbon powder supply device form a dioxin removal link; the dry desulfurization link and the SCR denitration link jointly form a dry desulfurization and denitration system adopting a hollow fiber membrane dust remover;

the hollow fiber membrane dust collector (6) adopts hollow fiber membrane filaments with the diameter of 3-10 mm, the length of 0.3-1.5 m, the thickness of the membrane filament wall of 0.1-1 mm, the interval distance between the membrane filaments of 2-20 mm and the wind speed of 1-20 mm/S on the surface of each square centimeter of the membrane filaments.

Drawings

FIG. 1 is a block diagram of an example of a dry desulfurization and denitrification system using a hollow fiber membrane dust collector according to the present invention.

FIG. 2 shows SO measured by a chimney sensor when a bag-type dust remover is switched to a hollow fiber membrane dust remover in the implementation process of the dry desulfurization and denitrification system adopting the hollow fiber membrane dust remover²Graph of the change in value.

Detailed description of the invention

In 9/7/2020, the first half of the SDS dry desulfurization and SCR low-temperature denitration system is implemented in a certain medical waste treatment center in GuangdongOnly the dust removal and desulfurization parts are used. The specific mode is as follows: a hollow fiber membrane dust collector is used for switching and replacing an online operation bag-type dust collector with the same air volume and pressure. The operation air volume of the bag-type dust collector is 4500-5000 m/h, and the average pressure is 480 pa; the adopted cloth bag is a high-precision dust removal cloth bag with a PDFE base material and a PDFE coating, the diameter is 160mm, and the number of the cloth bags is 98; the dust filtration effect is 3-6 mg/m for high yield and high yield, SO²And carrying out thin film fruit pulp and thin film fruit pulp according to the following steps of carrying out thin film fruit pulp and thin film fruit pulp.

The switch is completed from 13 point 40 to 13 point 47. After 10 minutes, the stack sensor measures SO²The average discharge value is reduced to 3-5 mg/m for carrying out the plantation; the decline in HCL from 30mg/m to 2-3 mg/m was taken under the condition of constant weight.

After 1 hour, the emission concentration of Pm2.5 dust gradually decreases to 50ug/m, and the emission concentration gradually decreases to 5 ug/m for carrying out high harvest by 8:00 at 9 month and 8 th.

The invention achieves ideal effects beyond expectation by implementing the dust removal and desulfurization links. Since SCR denitration is a mature technology, the observation of catalyst change is also a long-term task, and opportunities are found to complete the whole system implementation test in the future.

Claims

1. The utility model provides an adopt dry process SOx/NOx control system of hollow fiber membrane dust remover which characterized in that: a dry desulphurization link is formed by a flue gas inlet pipe (2), a reactor (1), a sodium-based desulphurization powder supply device (3), a calcium-based desulphurization powder supply device (4), an activated carbon powder supply device (5) and a hollow fiber membrane dust remover (6); the SCR denitration process comprises a hollow fiber film dust remover (6), a denitration reducing agent supply device (8), a denitration reactor (9) and a catalyst (10) to form an SCR denitration link; a hollow fiber film dust remover (6) and an active carbon powder supply device (5) form a dioxin removal link; the dry desulfurization link and the SCR denitration link jointly form a dry desulfurization and denitration system adopting a hollow fiber membrane dust remover;