CN1583219A

CN1583219A - Process for eliminating SOx in flue by activated carbon based adsorbent

Info

Publication number: CN1583219A
Application number: CN 200410024151
Authority: CN
Inventors: 李春虎
Original assignee: Ocean University of China
Current assignee: Ocean University of China
Priority date: 2004-05-26
Filing date: 2004-05-26
Publication date: 2005-02-23
Anticipated expiration: 2024-05-26
Also published as: CN100348298C

Abstract

A process for removing SO2 from fume by use of the activated carbon-based adsorbent features that the fume containing SO2 flows through the desulfurizing tower (or tank) filled by activated carbon-based adsorbent, and said adsorbent can be regenerated by hot water washing or high-temp inertial gas scavenging. Its by-product is H2SO4 or S.

Description

Method for removing SO in flue gas by using activated carbon-based adsorbent2Process for preparing (A) a

Technical Field

The invention relates to a method for removing SO in flue gas₂More specifically, the method utilizes the activated carbon-based adsorbent to remove SO from flue gas of coal-fired power plants, coal-fired boilers, coal-fired kilns and the like₂The process of (1).

Background

Coal accounts for 69 percent in the energy consumption structure of China, and the large-scale combustion of coal causes the national atmosphere to be polluted in a coal smoke type, particularly since the 80 s, along with the rapid development of the economy of China, the coal consumption is increasingly increased, and SO₂The discharge amount is continuously increased, and the atmospheric environment is seriously polluted. According to statistics, SO in China in 1985₂Emission was 1530 ten thousand tons in 1990 1752 thousand tons and increased to 2370 thousand tons in 1995, and the rate was estimated as SO in 2000₂The discharge amount will be 2590 ten thousand tons. Due to SO₂Is discharged in large quantities, resulting inThe ecological environment is destroyed and the acid rain phenomenon is serious. At present, the acid rain area of China already accounts for 40% of the area of the national soil, the acidity of national rainfall is averagely increased by 2-8 times, and the rare condition that the pH value of the rainfall in the world is lower than 4 occurs. Economic losses due to acid rain settlement to agriculture, forestry and material destruction are as high as 1000 billion yuan per year. SO that SO is reduced₂Discharge amount and reduce SO₂Concentration of discharged gas and prevention of SO₂Atmospheric pollution, based on the national conditions, has become the main task in the present and future for a considerable period of time to develop and adapt to flue gas desulfurization techniques of different scales.

According to the sustainable development strategy of China and the agenda of 21 st century China, the early century of this century, national SO₂Must not exceed 2370 million tons in 1995. However, the current flue gas desulfurization technology has high investment and running cost and is difficult to popularize, SO that the environmental protection department can increase SO year by year₂The fines discharged are of great intensity, but cannot be solved by the related art fundamentally. There are hundreds of flue gas desulfurization technologies currently being industrialized and researched at home and abroad, and these methods can be divided into dry methods and wet methods in terms of process, and can be divided into reject methods and recovery methods in terms of recovery and utilization of the added desulfurizing agent. Among the main methods that have been industrialized or tried in the middle are: 1) ammonium sulfite method; 2) citrate method; 3) wet desulfurization with activated carbon; 4) producing a phosphorus-ammonia compound fertilizer by wet desulphurization; 5) desulfurizing by an electron beam method; 6) desulfurizing by lime-gypsum method. The method has the disadvantages of large investment and high operating cost, or the waste desulfurizer after desulfurization cannot be utilized, secondary pollution is caused, and the waste residue is stacked or is subjected to transportation cost for large-capacity boilers of power plantsThe restriction of (2) or the limitation of site stacking are all key factors influencing the commercialization of the desulfurization technology. Therefore, the technologies are difficult to popularize and use in a large scale in China at present. Among them, the flue gas desulfurization technology (FGD lime powder spraying method) which has been applied in large-scale commercialization internationally has high technical maturity, and is introduced by power plants in China, but because of high cost, large investment and no comprehensive utilization of byproduct gypsum, none of the technologies succeeds. At present, most researchers think that the modified active semi-coke and other active carbon-based adsorbents remove SO from flue gas₂Most advanced before developmentIts application is disclosed.

Disclosure of Invention

The invention aims to provide a method for removing SO in flue gas by using an active carbon-based adsorbent₂The process of (1).

Method for removing SO in flue gas by using activated carbon-based adsorbent₂The process of (A) is to contain SO₂The flue gas is desulfurized by a desulfurizing tower or a desulfurizing tank which is provided with an active carbon-based adsorbent, and is treated as SO in the desulfurizing tower or the desulfurizing tank₂When the outlet concentration exceeds the index, the activated carbon-based adsorbent is washed by hot water or purged by inert gas at high temperature for regeneration, and the regenerated product is dilute H₂SO₄Or elemental S.

The specific technological operation conditions of the invention are that the temperature is 60-160 ℃ and the space velocity is 500-2000h^-1The lower desulfurization is carried out, and the desulfurization is carried out by washing and regenerating with hot water at 60-90 ℃ or at 340-680 ℃ and at a space velocity of 500-4000h^-1And then the inert gas is used for purging and regenerating. SO usually contained in flue gas₂The concentration is 0-5000 ppm. The activated carbon-based adsorbent can be prepared from activated carbon-based materials such as activated semicoke, activated coke or activated carbon by an ozone activation method or a pressurized water thermochemical activation method, and the two preparation methods are patented by the inventor.

The process of the present invention employs three (more) columns or three (more) tanks which can be operated either in series or in parallel, typically two desulfurisation, one regeneration.

The invention has the advantages that the sulfur capacity and the use efficiency of the adsorbent can be obviously improved, and the byproduct of dilute H is generated in the regeneration process₂SO₄Or simple substance S, thereby achieving the effect of comprehensive utilization of resources. The process can be used in the industries of desulfurization, purification and environmental protection of flue gas in coal-fired power plants, coal-fired boilers, coal-fired kilns and the like.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings by way of specific embodiments.

FIG. 1 is a process flow diagram of the present invention.

FIG. 2 is a flow diagram of a desulfurization process employing hot water scrubbing regeneration.

FIG. 3 is a flow diagram of a desulfurization process employing inert gas purging regeneration.

Example 1:

as shown in fig. 2, three reaction columns are used to operate individually or in series (parallel). The diameter of the reaction tower is 70mm, the filling amount of each tower is 1 liter, the weight of the active semi-coke adsorbent is 581 grams, the desulfurization temperature is 90 ℃, and the space velocity is 900h^-1The flue gas consists of SO₂800-2600ppm、O₂9.5-14.8 percent of carbon monoxide (CO) 75-435ppm and the balance of N₂And CO₂Under the conditions, the process operation is as follows: firstly, opening the No. 1 and No. 2 valves, and allowing the flue gas to enter the No. 1 valve^#The flue gas after desulfurization and purification enters a purified pipeline through a No. 2 valve and is discharged into a chimney; when 1 is^#Gas SO at the outlet of the column₂If the detection exceeds the standard (e.g. 200ppm), the valve No. 2 is closed, and the valves No. 3 and 5 are opened, in this case, 1^#Desulfurization reaction tower and 2^#The desulfurization reaction towers are connected in series for operation; when 2 is in^#SO in the gas at the outlet of the column₂When the detection exceeds the standard, the valves 1, 2, 3 and 5 are closed, and the valves 4, 6 and 8 are opened simultaneously, at the moment, the valve 2^#Towers and 3^#The towers are connected in series for flue gas desulfurization; simultaneously using hot water 1^#Regenerating the desulfurizing tower by opening valve A and injecting hot water of 90 deg.C and 1.0L into the desulfurizing tower^#The reaction tower stays for 1 hour, the valve A' is opened, and the elution regeneration liquid is pumped into the concentrated H₂SO₄In the recovery tank; then repeating the above operation pair 1 with hot water^#The adsorbent in the tower is regenerated, only the regenerated liquid is driven into dilute H₂SO₄In the groove; to be driven from 1^#When the pH value of the regeneration liquid flowing out of the tower is equal to 6, the regeneration is stopped. In the same way, when 3^#Tower outlet gas SO₂When the time exceeds the standard, the valves 4, 6 and 8 are closed; valves 7, 9 and 2 are opened simultaneously, at which time 3^#Column and regenerated 1^#Operation of the towers in series for flue gas desulfurization, 2^#The tower is subjected to adsorbent regeneration, whichThe process is as follows: first, open valve B and pump dilute H₂SO₄Dilute H in the tank₂SO₄Is driven into 2^#1 liter in the reaction tower, staying for 1 hour, opening a valve B', and injecting eluent into concentrated H₂SO₄In the groove; then 1 liter of regenerated hot water is injected into the system 2^#After a residence time of 1 hour in the column, the eluent was introduced into dilute H₂SO₄And repeating the steps until the pH value of the outlet eluent is increased to 6, and completely regenerating the outlet eluent. The cumulative sulfur capacity of the thus obtained activated carbon-based adsorbent was 168%. Therefore, the process can obviously improve the sulfur capacity and the use efficiency of the adsorbent.

Example 2:

as shown in fig. 3, three reaction columns are used to operate individually or in series (parallel). The diameter of the reaction tower is 70mm, the filling amount of each tower is 1 liter, the weight of the active semi-coke adsorbent is 581 grams, the desulfurization temperature is 90 ℃, and the space velocity is 900h^-1The flue gas consists of SO₂800-2600ppm、O₂9.5-14.8％、CO75-435ppm and N in balance₂And CO₂Under the conditions, the process operation is as follows: firstly, opening the No. 1 and No. 2 valves, and allowing the flue gas to enter the No. 1 valve^#The flue gas after desulfurization and purification enters a purified pipeline through a No. 2 valve and is discharged into a chimney; when 1 is^#Gas SO at the outlet of the column₂If the detection exceeds the standard (e.g. 200ppm), the valve No. 2 is closed, and the valves No. 3 and 5 are opened, in this case, 1^#Desulfurization reaction tower and 2^#The desulfurization reaction towers are connected in series for operation; when 2 is in^#SO in the gas at the outlet of the column₂When the detection exceeds the standard, the valves 1, 2, 3 and 5 are closed, and the valves 4, 6 and 8 are opened simultaneously. At this time 2^#Towers and 3^#The towers are connected in series for flue gas desulfurization; simultaneously using inert gas pairs 1 in a hot blast furnace^#Regenerating the reaction tower, opening the valves A' and A, and keeping the temperature at 340-^-1Lower pair 1^#Continuously blowing the adsorbent in the reaction tower from bottom to top, wherein the adsorbent and the adsorbed SO₂And SO₃The reaction generates sulfur steam, and the reaction formula is as follows:

the temperature of the outlet gas is reduced to below 60 ℃ after passing through a cooler, sulfur steam in the gas is changed into solid sulfur and recovered, tail gas after sulfur recovery can be continuously used after passing through a hot blast stove, and the sulfur content of the gas in the cooler is reduced to 10mg/Nm³When the regeneration is stopped, turn on 1^#Discharge valve pair 1 of storage bin^#And (4) supplementing the adsorbent in the reaction tower until the adsorbent in the reaction tower reaches the scale of 1 liter. At this time 1^#The reaction tower can perform the next round of desulfurization reaction. In the same way, when 3^#Tower outlet gas SO₂When the time exceeds the standard, the valves 4, 6 and 8 are closed; valves 7, 9 and 2 are opened simultaneously, at which time 3^#Column and regenerated 1^#Operation of the towers in series for flue gas desulfurization, 2^#The tower is used for regenerating the adsorbent in the same process as 1^#And (4) regenerating the tower. Openingvalves B' and B to recover tail gas (mainly CO)₂And N₂Gas) is pumped into the hot blast furnace 2^#The tower is continuously purged from bottom to top to regenerate the tower. After regeneration is complete, turn on 2^#Discharge valve pair 2 of storage bin^#The reaction tower is used for supplementing the adsorbent. Thus, the desulfurization and regeneration reactions are repeated. The cumulative sulfur capacity of the obtained activated carbon-based material adsorbent is 240%. Therefore, the process can obviously improve the sulfur capacity and the use efficiency of the adsorbent.

Claims

1. Method for removing SO in flue gas by using activated carbon-based adsorbent₂Is characterized in that the composition contains SO₂The flue gas is desulfurized by a desulfurizing tower or a desulfurizing tank filled with active carbon-based adsorbent, and when the flue gas is treated by SO in the desulfurizing tower or the desulfurizing tank₂And when the outlet concentration exceeds the index, the activated carbon-based adsorbent is regenerated by adopting hot water washing or inert gas high-temperature purging.

2. The method for removing SO in flue gas according to claim 1₂The process of (1), characterized in thatThe desulfurization is carried out at the temperature of 60-160 ℃ and the space velocity of 500-^-1Under the condition of the reaction.

3. The method for removing SO in flue gas according to claim 1₂The process is characterized in that the regeneration of the adsorbent is realized by washing and regenerating with hot water at 60-90 ℃ or at 340-680 ℃ and at a space velocity of 500-4000h^-1And then the inert gas is used for purging and regenerating.