烟气中 S07.的脱出和回收方法及装置 技术领域 Method and device for extracting and recovering S0 7 in flue gas
本发明涉及一种烟气中 so2的脱出,并加以回收的方法及装置,特别涉及一种以 氨为原料 (包括液氨、 氨水和碳铵)的烟气脱硫方法。 The invention relates to a method and a device for desorbing and recovering SO 2 in flue gas, in particular to a flue gas desulfurization method using ammonia as a raw material (including liquid ammonia, ammonia water and ammonium carbonate).
背景技术 Background technique
含硫矿物及燃料燃烧时, 排放的烟气中含有 so2。烟气中 so2含量通常较低, 在When sulfur-containing minerals and fuels are burned, the exhaust gas contains so 2 . The content of so 2 in the flue gas is usually low.
300— 5000ppmv(1000—15000毫克 /标准立方米)之间, 但是, 烟气量十分巨大。 以燃 煤锅炉而论, 蒸汽规模从 IT/h到 2500T/h, 发电机组容量 6MW到 900MW, 烟气量 由 1万 Nm3/h到 250万 Nm3/h, 已产生了严重的酸雨和 S02污染。 因此, '烟气的脱 硫和 S02的回收已经得到了人们广泛的重视。 300-5000ppmv (1000-15000mg / standard cubic meter), but the amount of smoke is huge. In the case of coal-fired boilers, the steam scale ranges from IT / h to 2500T / h, the generating unit capacity is 6MW to 900MW, and the flue gas volume is from 10,000 Nm 3 / h to 2.5 million Nm 3 / h. Serious acid rain and S0 2 pollution. Therefore, 'desulfurization of flue gas and recovery of SO 2 have received widespread attention.
烟气脱硫的原理是碱性脱硫剂与酸性 S02气体的化学反应。 典型脱硫剂是石灰 石 (CaC03)和氨 (N¾), 形成了典型的两个技术类别, 分别称为钙法和氨法。 The principle of flue gas desulfurization is the chemical reaction between an alkaline desulfurizer and an acidic SO 2 gas. Typical desulfurizing agents are limestone (CaC0 3 ) and ammonia (N¾), forming two typical technology categories, which are called calcium method and ammonia method, respectively.
钙法在脱硫的同时生成石膏副产品, CaS04.2H20, 可用作建材原料, 但一般用 处不大, 只能弃置堆放。 因此, 钙法常被称为抛弃法。 The calcium method generates a gypsum by-product, CaS0 4 .2H 2 0, at the same time as desulfurization, which can be used as a raw material for building materials, but it is generally not very useful and can only be discarded and stacked. Therefore, the calcium method is often called the abandonment method.
氨法在脱硫的同时可副产多种产品, 如硫酸和硫铵化肥等。 氨法的脱硫副产品 比钙法具有更大的应用价值。 而且, 氨法的脱硫剂氨来自化肥, 其脱硫产品也作为 化肥, 对大自然不产生额外的生态环境问题, 因此, 氨法称为回收法。 The ammonia method can co-produce a variety of products while desulfurizing, such as sulfuric acid and ammonium sulfate fertilizers. The desulfurization by-product of the ammonia method has greater application value than the calcium method. In addition, the ammonia desulfurizing agent ammonia comes from chemical fertilizers, and its desulfurization products also serve as chemical fertilizers, which do not cause additional ecological and environmental problems to nature. Therefore, the ammonia method is called the recycling method.
在氨法脱硫过程中, 通常包括两个步骤: The ammonia desulfurization process usually includes two steps:
(1) 吸收 so2生成亚硫酸铵和亚硫酸氢铵混合溶液, 反应原理为: (1) So 2 is absorbed to form a mixed solution of ammonium sulfite and ammonium bisulfite. The reaction principle is:
NH3溶解: H3 +NH4HS03― (NH4)2S03 NH 3 is dissolved: H 3 + NH 4 HS0 3 ― (NH 4 ) 2 S0 3
(以碳铵为原料时, H4HC03 +NH4HS03 = (NH4)2S03 + C02+H20) (When using ammonium carbonate as raw material, H 4 HC0 3 + NH 4 HS0 3 = (NH 4 ) 2 S0 3 + C0 2 + H 2 0)
总反应为: The total response is:
S02 +xNH3 +H20= (NH4)xH2-xS03 S0 2 + xNH 3 + H 2 0 = (NH 4 ) x H 2-x S0 3
在吸收液中含有 NH4HS03和 (NH4)2S03, 两个盐的比例是由脱硫工艺过程的 H3/S02比控制的, 在中国专利 99110643.6 中, N¾/S02 = 1.2— 1.4, 溶液中的 (NH4)2S03和 N¾HS03比例为 1/4—2/3。 The absorption solution contains NH 4 HS0 3 and (NH 4 ) 2 S0 3. The ratio of the two salts is controlled by the H 3 / S0 2 ratio in the desulfurization process. In Chinese patent 99110643.6, N¾ / S0 2 = 1.2 — 1.4, the ratio of (NH 4 ) 2 S0 3 and N¾HS03 in the solution is 1 / 4-2 / 3.
亚硫铵混合溶液是脱硫过程副产的半成品, 也可以直接予以利用, 比如经过加
氨中和后, 得到亚硫酸铵溶液, 作为液体氮肥予以销售。 一般而言, 在火电厂烟气 脱硫领域, 需要将亚硫铵加工为固体硫铵, 便于储存、 运输和季节性销售。 The mixed solution of ammonium sulfite is a semi-finished product produced as a by-product of the desulfurization process, and it can also be directly used, for example, by adding After the ammonia was neutralized, an ammonium sulfite solution was obtained and sold as a liquid nitrogen fertilizer. Generally speaking, in the field of flue gas desulfurization of thermal power plants, ammonium sulfite needs to be processed into solid ammonium sulfide, which is convenient for storage, transportation and seasonal sales.
(2)亚硫铵混合溶液的加工转化 (2) Processing transformation of ammonium sulfite mixed solution
在中国专利 99110643.6中, 公布了一种方法, 以硫酸分解亚硫铵溶液, 得到硫 酸铵和 S02气体。 通过鼓入空气, 可以得到较高 S02浓度的空气混合物, 比如 S02 含量为 7—15%,适合于采用催化 (催化剂为 V205/Si02)氧化方法氧化为 S03,经过浓 硫酸吸收得到 98.2%浓度的商品级浓硫酸。一部分硫酸作为亚硫铵分解用,一部分作 为商品硫酸外卖。 由于亚硫铵中的氨 /硫比在 1.2—1.4, 回收 S02中有 30— 40%生产 商品硫酸。 其反应如下: In Chinese patent 99110643.6, a method is disclosed that decomposes ammonium sulfite solution with sulfuric acid to obtain ammonium sulfate and SO 2 gas. By blowing in air, an air mixture with a higher S0 2 concentration can be obtained, for example, the content of S0 2 is 7-15%, which is suitable for oxidation to S0 3 by a catalytic (V 2 0 5 / Si0 2 ) oxidation method. Sulfuric acid absorption gave 98.2% concentration of commercial grade concentrated sulfuric acid. Part of the sulfuric acid is used for the decomposition of ammonium sulfite, and part of it is sold as commercial sulfuric acid. Since the ammonia / sulfur ratio in ammonium sulfite is between 1.2 and 1.4, 30-40% of the recovered SO 2 is produced in commercial sulfuric acid. The response is as follows:
(NH4)xH2-xS03+H2S04 = x(NH4)2S04+S02+H20 (1) S02+ 1/202=S03 (2) S03+H20=H2S04 (3) 中国电力, 2001]中, 介绍了另外一种亚硫铵加工方案, 采用磷酸分解压 硫铵溶液, 得到磷酸二氢铵和 so2。 在这个方案中, 全部 so2转化为硫酸。 硫酸用 于磷酸生产。 该方案特别适用于火电厂旁边有磷铵化肥厂的情况。 (NH 4 ) x H 2- xS0 3 + H 2 S0 4 = x (NH 4 ) 2 S0 4 + S0 2 + H 2 0 (1) S0 2 + 1/20 2 = S0 3 (2) S0 3 + H 2 0 = H 2 S0 4 (3) China Electric Power, 2001] introduced another ammonium sulfite processing scheme, using phosphoric acid to decompose the ammonium sulfide solution to obtain ammonium dihydrogen phosphate and so 2 . In this scheme, all of the so 2 is converted to sulfuric acid. Sulfuric acid is used in phosphoric acid production. This solution is especially applicable to the case where there is an ammonium phosphate fertilizer plant next to the thermal power plant.
上述公开的技术特别适合含硫量髙的锅炉烟气, 比如燃用高硫煤的烟气或有色 金属冶炼厂的烧结机烟气。 但是, 对于含硫量较低的锅炉烟气, 如烟气中 so2含量 小于 lOOOppmv, 相当于锅炉燃煤含硫量小于 1%, 尤其是锅炉容量较小, 每年脱出 的 S02总量较小。 如果采用生产硫酸的方案, 由于硫酸装置规模太小, 相对投资和 能耗较高, 经济性较差。 因此, 开发研究含硫量很低的烟气中硫的脱出和回收利用, 将具有十分重要的意义。 The above-disclosed technology is particularly suitable for boiler flue gas containing sulfur, such as flue gas burning high sulfur coal or sintering machine flue gas of non-ferrous metal smelting plant. However, lower sulfur content for boiler flue gas, such as flue gas SO 2 content is less than lOOOppmv, the sulfur content of coal-fired boilers corresponding to less than 1%, especially smaller boiler capacity, the total annual prolapse than S0 2 small. If a solution for producing sulfuric acid is used, the scale of the sulfuric acid plant is too small, the relative investment and energy consumption are high, and the economy is poor. Therefore, it is of great significance to develop and research the sulfur extraction and recycling in the flue gas with very low sulfur content.
发明内容 Summary of the Invention
本发明需要解决的技术问题是公开一种特别适用于含硫量低的烟气中的 S02的 脱出和回收方法及装置, 以克服现有技术存在的缺陷。 ' 本发明的技术构思是这样的: 从吸收过程来的亚硫铵混合溶液, 经过加氨中和 后得到亚硫酸铵溶液: The technical problem to be solved by the present invention is to disclose a method and device for extracting and recovering SO 2 in flue gas with low sulfur content, so as to overcome the defects existing in the prior art. '' The technical idea of the present invention is as follows: from the mixed solution of ammonium sulfite from the absorption process, after neutralization with ammonia, an ammonium sulfite solution is obtained:
(NH4)xH2-xS03 + (2-x) H3 = (NH4)2S03 (NH 4 ) x H 2-x S0 3 + (2-x) H 3 = (NH 4 ) 2 S0 3
对亚硫酸铵溶液鼓空气直接氧化, 便可得到硫酸铵: The ammonium sulfite solution is oxidized directly, and ammonium sulfate can be obtained:
(NH4)2S03 + 1/202 = (NH4)2S04
就亚硫酸氧化反应而言, 看视很简单, 但是, 由于该反应与溶液的盐 (包括亚硫 酸铵和硫酸铵盐)浓度成一种很独特的关系, 实际实施过程较为困难。 在文献(NH 4 ) 2 S0 3 + 1/20 2 = (NH 4 ) 2 S0 4 As far as the oxidation reaction of sulfite is concerned, it is easy to see. However, since the reaction has a unique relationship with the concentration of the salt of the solution (including ammonium sulfite and ammonium sulfate), the actual implementation process is difficult. In the literature
[Chemical Engineering Science, 2000 ]中, 阐述了这一独特性质, 当盐浓度小于 0.5mol/L (约 5 %(wt))时,亚硫酸铵氧化速率随其浓度增加而增加,而当超过这个极限 值时, 氧化速率随浓度增加而降低。 在较高盐浓度时, 亚硫酸铵氧化速度很低。 因 此, 在实际实施过程中, 传统技术, 如文献 [S« p/i«r, 1995]中介绍的技术, 烟气脱硫 得到了 10— 20%(wt)的亚硫酸铵溶液, 氧化过程为压縮空气加压氧化, 压缩空气压 力为 0.5_0.8Mpa。 氧化后得到的硫酸铵溶液, 再经过三效蒸发、 浓缩、 结晶、 干燥 步骤, 得到固体硫酸铵。 这个过程的投资大、 电耗和蒸汽消耗高, 设备防腐蚀要求 也高。 中国发明专利 ZL99113403.6也正是为了克服这个缺点而提出来的一种方法, 在这个方法中, 亚硫酸铵混合盐浓度的上限不受限制, 常规操作浓度在 30— 50 % (wt), 这样, 能耗很低, 设备投资较小。 但是该方法更适合于高硫煤和 (或)大型发电 厂。 据此, 发明人提出了如下的设想: [Chemical Engineering Science, 2000] described this unique property. When the salt concentration is less than 0.5mol / L (about 5% (wt)), the oxidation rate of ammonium sulfite increases with its concentration, and when it exceeds this concentration, At the limit, the oxidation rate decreases with increasing concentration. At higher salt concentrations, the oxidation rate of ammonium sulfite is very low. Therefore, in the actual implementation process, traditional technology, such as the technology introduced in the document [S «p / i« r, 1995], the flue gas desulfurization obtained a 10-20% (wt) ammonium sulfite solution, the oxidation process is The compressed air is pressurized and oxidized, and the compressed air pressure is 0.5_0.8Mpa. The ammonium sulfate solution obtained after the oxidation is further subjected to three-effect evaporation, concentration, crystallization, and drying steps to obtain solid ammonium sulfate. The investment in this process is high, the power consumption and steam consumption are high, and the equipment requires high corrosion protection. Chinese invention patent ZL99113403.6 is also a method proposed to overcome this shortcoming. In this method, the upper limit of the concentration of ammonium sulfite mixed salt is not limited, and the normal operating concentration is 30-50% (wt), In this way, energy consumption is low and equipment investment is small. However, this method is more suitable for high-sulfur coal and / or large power plants. Accordingly, the inventor has proposed the following:
1.控制亚硫酸铵的浓度, 尤其亚硫酸铵浓度在最低值, 一般在 0.1— 5 %(wt)之 间, 最好在 0.5— 2.0%之间, 创造最有利于氧化的条件, 降低氧化的能耗和投资; 1. Control the concentration of ammonium sulfite, especially the lowest concentration of ammonium sulfite, generally between 0.1-5% (wt), preferably between 0.5-2.0%, to create the most favorable conditions for oxidation and reduce oxidation Energy consumption and investment;
2.合理利用烟气的热量, 将其用于稀硫酸铵溶液的浓缩, 使硫酸铵溶液的浓度 在不消耗额外能量 (蒸汽)条件下达到 30— 50%(wt); 2. Use the heat of the flue gas reasonably and use it for the concentration of dilute ammonium sulfate solution, so that the concentration of the ammonium sulfate solution reaches 30-50% (wt) without consuming additional energy (steam) ;
3. 构造一个多功能的脱硫装置, 相当于分为多段, 它具有亚硫酸铵氧化功能、 硫酸铵溶液浓缩功能、 S02吸收功能、 水洗和除雾(沬)功能, 称为五效装置 (塔) (Five-Way Column, FWC)。 3. Construct a multi-functional desulfurization device, which is equivalent to being divided into multiple sections. It has ammonium sulfite oxidation function, ammonium sulfate solution concentration function, SO 2 absorption function, water washing and defogging (沬) function. It is called a five-effect device ( Tower) (Five-Way Column, FWC).
具体的方法包括如下步骤: The specific method includes the following steps:
( 1 ) .低含硫烟气首先与亚硫酸铵溶液进行反应,生成亚硫酸铵与亚硫酸氢铵的 混合溶液, 控制亚硫酸铵的浓度在 0.1— 5 %(wt)之间, 最好在 0.5— 2.0%之间, 以创 造最有利于氧化的条件, 降低氧化的能耗和投资, 确保高的脱硫效率, 因此, 氨 /硫 比 =1.3— 1.8(摩尔比), 气 /液比为 2000-5000 (体积比) , 然后加氨反应, 生成亚硫 酸铵溶液, 所说的氨包括液氨、 氨水或 /和碳铵; (1). The low sulfur-containing flue gas is first reacted with an ammonium sulfite solution to form a mixed solution of ammonium sulfite and ammonium bisulfite, and the concentration of ammonium sulfite is controlled to be between 0.1 and 5% (wt), preferably In the range of 0.5-2.0%, in order to create the most favorable conditions for oxidation, reduce the energy consumption and investment of oxidation, and ensure high desulfurization efficiency, therefore, the ammonia / sulfur ratio = 1.3-1.8 (molar ratio), gas / liquid ratio It is 2000-5000 (volume ratio), and then ammonia is added to react to form ammonium sulfite solution. The ammonia includes liquid ammonia, ammonia water or / and ammonium carbonate;
(2) .生成的亚硫酸铵溶液与空气进行氧化反应得到硫酸铵溶液。压缩空气的压 力一般在 0.05— 0.2Mpa (表压), 压縮空气的流量是亚硫酸铵氧化理论需要量的 1~5 倍,常见的是 2—4倍,氧化反应停留时间一般在 1~3小时之间,最好在 2小时左右。
在此条件下, 氧化率大可于 95%。 硫酸铵溶液的浓度一般为 5—20%(wt)。 (2) The ammonium sulfite solution is oxidized with air to obtain an ammonium sulfate solution. The pressure of the compressed air is generally 0.05-0.2Mpa (gauge pressure). The flow rate of the compressed air is 1 to 5 times the theoretical amount of ammonium sulfite oxidation. Commonly, it is 2 to 4 times. The residence time of the oxidation reaction is generally 1 to Between 3 hours, preferably around 2 hours. Under these conditions, the oxidation rate can be greater than 95%. The concentration of ammonium sulfate solution is generally 5-20% (wt).
(3) .步骤(2)生成的硫酸铵溶液与温度为 100—160°C的热烟气接触,通过热、 质同传过程, 热烟气温度降低到 50— 55°C, 湿度增加到接近饱和湿度。 而硫酸铵溶 液中水分蒸发, 硫酸铵浓度可增加到 40_50%(wt), 送往硫铵结晶器, 加工成商品 硫铵化肥。 (3). The ammonium sulfate solution generated in step (2) is in contact with hot flue gas with a temperature of 100-160 ° C. Through the process of heat and mass transfer, the temperature of the hot flue gas is reduced to 50-55 ° C and the humidity is increased to Near saturation humidity. While the water in the ammonium sulfate solution evaporates, the ammonium sulfate concentration can be increased to 40-50% (wt), sent to the ammonium sulfate crystallizer, and processed into commercial ammonium sulfate fertilizer.
(4)对被氨的水溶液吸收了 S02后的烟气进行水洗,洗脱烟气中夹带的吸收液, 尤其是硫铵等, 以便减少产品的损失, 同时防止带入再热器。 水洗的水流量是为维 持吸收系统水平衡所需的流量, 与烟气条件有关, 一般是吸收液流量的 5~20%。 (4) an aqueous solution of ammonia to be absorbed S0 2 the flue gas is washed with water, eluting the absorption liquid entrained in the flue gas, in particular ammonium sulfate, etc., in order to reduce product loss, while preventing into the reheater. The water flow of the washing is the flow required to maintain the water balance of the absorption system, which is related to the flue gas conditions, and is generally 5 to 20% of the absorption liquid flow.
(5 )对水洗后的烟气进行除沫, 其功能是除去烟气中夹带的水雾滴。 除沬后的 烟气可直接排空。 (5) Defoaming the water-washed flue gas, the function of which is to remove the water droplets entrained in the flue gas. The removed flue gas can be evacuated directly.
按照本发明, 除沬后烟气的最好进行加热, 因为烟气基本上为水汽饱和的烟气, 如果不经过再热, 提高温度, 必然在烟道和烟囱内壁形成水露, 对烟道产生腐蚀。 另外,饱和的烟气离开烟囱,会经常形成一条"白龙", 由于抬升髙度不足,形成雨滴, 对锅炉厂区构成酸雨污染。 通常情况下, 脱硫后的烟气温度为 48— 50°C, 饱和露点 约为 48°C, 为解决上述问题, 烟气温度应高于露点 20°C以上。 因此, 再热后的烟气 温度大于 70°C即可。 再热的热源可来自于原烟气, 其温度在 130—160°C之间, 经再 热后的脱硫烟气, 经过增压后送入烟囱排空。 According to the present invention, it is best to heat the flue gas after removing it, because the flue gas is basically a vapor saturated with water vapor. If it is not reheated and the temperature is increased, water dew will necessarily form on the flue and the inner wall of the chimney. Causes corrosion. In addition, the saturated smoke leaving the chimney will often form a "white dragon". Due to insufficient lifting degree, raindrops will be formed, which will cause acid rain pollution to the boiler plant area. Generally, the flue gas temperature after desulfurization is 48-50 ° C, and the saturated dew point is about 48 ° C. In order to solve the above problems, the flue gas temperature should be above 20 ° C above the dew point. Therefore, the reheated flue gas temperature should be greater than 70 ° C. The reheating heat source can come from the original flue gas, whose temperature is between 130-160 ° C. After the reheating, the desulfurized flue gas is sent to the chimney and exhausted after being pressurized.
用于实现上述方法的装置至少包括- 一个包括 S02吸收段、 亚硫酸铵氧化段、 硫酸铵溶液浓缩段、 水洗段和除雾沬 段的脱硫塔; The device for implementing the above method includes at least one desulfurization tower including a SO 2 absorption section, an ammonium sulfite oxidation section, an ammonium sulfate solution concentration section, a water washing section and a defogging section;
一个通过管线与浓缩段下部的浓硫酸铵溶液出口相连接的硫酸铵结晶槽; · 一个通过管线与硫酸铵结晶槽相连接的硫酸铵液固分离器; An ammonium sulfate crystallization tank connected to the outlet of the concentrated ammonium sulfate solution at the lower part of the concentration section through a pipeline; an ammonium sulfate liquid-solid separator connected to the ammonium sulfate crystallization tank through a pipeline;
一个分别通过管线与氧化段的稀硫酸铵出口和分离器的母液出口相连接的硫酸 铵溶液循环槽; An ammonium sulfate solution circulation tank connected to the dilute ammonium sulfate outlet of the oxidation section and the mother liquid outlet of the separator through a pipeline;
一个通过管线与循环槽相连接的循环泵, 该循环泵的出口与设置在硫酸铵溶液 浓缩段上部的稀硫酸铵溶液入口相连接; A circulation pump connected to the circulation tank through a pipeline, and the outlet of the circulation pump is connected to the dilute ammonium sulfate solution inlet provided on the upper part of the ammonium sulfate solution concentration section;
一个通过管线分别与设置在氧化段底部的吸收液出口与设置在吸收段上部的吸 收液入口相连接的吸收液循环泵; An absorption liquid circulation pump connected through a pipeline to an absorption liquid outlet provided at the bottom of the oxidation section and an absorption liquid inlet provided at the upper portion of the absorption section;
一个通过管线与液固分离器相连接的硫酸铵干燥器。
本发明的装置是这样运行的: An ammonium sulfate dryer connected to the liquid-solid separator via a line. The device of the invention works like this:
含有 so2的烟气在脱硫塔中与进入脱硫塔的吸收液 (亚硫铵混合溶液)进行反 应, 使烟气中的 S02生成浓度为 0.1— 5 %(wt)的亚硫酸铵溶液, 该亚硫酸铵溶液再与 进入脱硫塔的空气接触, 被氧化为硫酸铵溶液, 硫酸铵溶液与进入脱硫塔的高温烟 气接触, 利用高温烟气的热量将硫酸铵溶液浓缩, 浓缩后的硫酸铵溶液被送入硫酸 铵液固分离器, 分离的固体硫酸铵在硫酸铵干燥器被干燥, 即获得成品硫酸铵, 可 用作一般的化肥; The flue gas containing so 2 is reacted in the desulfurization tower with the absorption solution (mixed solution of ammonium sulfite) entering the desulfurization tower, so that the S0 2 in the flue gas generates an ammonium sulfite solution with a concentration of 0.1 to 5% (wt), The ammonium sulfite solution is then contacted with the air entering the desulfurization tower and is oxidized into an ammonium sulfate solution. The ammonium sulfate solution is contacted with the high temperature flue gas entering the desulfurization tower. The ammonium sulfate solution is concentrated by using the heat of the high temperature flue gas, and the concentrated sulfuric acid The ammonium solution is sent to an ammonium sulfate liquid-solid separator, and the separated solid ammonium sulfate is dried in an ammonium sulfate dryer to obtain a finished ammonium sulfate, which can be used as a general chemical fertilizer;
脱出了 S02的烟气在脱硫塔的上部与进入的水接触, 进行水洗, 然后通过设置 在脱硫塔顶部的除雾 (沫)装置除雾 (沬), 最后, 净化后的烟气由脱硫塔顶部排出。 Prolapse S0 2 in the flue gas desulfurization tower in contact with the upper portion of the water entering, washed with water, and then by the demister provided at the top of the desulfurization column (Mo) demisting means (respiratory droplets), and finally, the purified flue gas desulfurization Discharge from the top of the tower.
本发明的方法和装置, 集烟气中 S02吸收、 亚硫酸铵氧化、 硫酸铵溶液浓缩、 水洗和除雾 (沬)功能于一体, 操作方便, 投资费用与现有技术相比, 在相同的处理量 的条件下, 可降低 10~30%, 而且能耗较低, 高温烟气的余热获得了充分的利用, 蒸 汽消耗可降低 90%。而且,脱硫效率很高,其中烟气中 S02的浓度可降至 10~100ppm 以下, 而获得的硫酸铵的质量符合国家的化肥级标准, 氮含量为 20.5~21%, 可作为 农业用化肥。 The method and device of the present invention integrate the functions of SO 2 absorption in flue gas, oxidation of ammonium sulfite, concentration of ammonium sulfate solution, water washing and defogging (沬), convenient operation, and the investment cost is the same as that of the prior art. Under the conditions of processing capacity, it can be reduced by 10 ~ 30%, and the energy consumption is low. The waste heat of high temperature flue gas is fully utilized, and the steam consumption can be reduced by 90%. In addition, the desulfurization efficiency is very high, in which the concentration of SO 2 in the flue gas can be reduced to less than 10 to 100 ppm, and the quality of the obtained ammonium sulfate conforms to the national fertilizer grade standard, and the nitrogen content is 20.5 to 21%, which can be used as agricultural fertilizer .
附图说明 BRIEF DESCRIPTION OF THE DRAWINGS
图 1为本发明的流程图。 FIG. 1 is a flowchart of the present invention.
图 2为脱硫塔结构示意图。 Figure 2 shows the structure of the desulfurization tower.
图 3为纵分隔板和横分隔板示意图。 FIG. 3 is a schematic diagram of a vertical partition plate and a horizontal partition plate.
具体实施方式 detailed description
参见图 1和图 2, 本发明的装置包括: Referring to Figures 1 and 2, the device of the present invention includes:
一个包括 S02吸收段 63、 亚硫酸铵氧化段 61、 硫酸铵溶液浓缩段 62、 水洗段 64和除雾沫段 65的脱硫塔 6; A desulfurization tower 6 including an S0 2 absorption section 63, an ammonium sulfite oxidation section 61, an ammonium sulfate solution concentration section 62, a water washing section 64 and a demister section 65;
一个通过管线与设置在液浓缩段 62下部的浓硫酸铵溶液出口 6201相连接的硫 酸铵结晶槽 9; An ammonium sulfate crystallization tank 9 connected to the concentrated ammonium sulfate solution outlet 6201 provided at the lower portion of the liquid concentration section 62 through a pipeline 9;
一个通过管线与硫酸铵结晶槽 9 相连接的硫酸铵液固分离器 13 , 可优选离心 机; An ammonium sulfate liquid-solid separator 13 connected to the ammonium sulfate crystallization tank 9 through a pipeline, and a centrifuge may be preferred;
一个硫酸铵溶液循环槽 12, 该循环槽 12分别通过管线与氧化段 61的稀硫酸铵 出口 6101和分离器 13的母液出口 1301相连接;
一个通过管线与循环槽 12相连接的循环泵 10, 该循环泵 10的出口与设置在硫 酸铵溶液浓缩段 62上部的稀硫酸铵溶液入口 6202相连接; An ammonium sulfate solution circulation tank 12 is connected to the dilute ammonium sulfate outlet 6101 of the oxidation section 61 and the mother liquid outlet 1301 of the separator 13 through pipelines, respectively; A circulation pump 10 connected to the circulation tank 12 through a pipeline, and the outlet of the circulation pump 10 is connected to the dilute ammonium sulfate solution inlet 6202 provided on the upper part of the ammonium sulfate solution concentration section 62;
• 一个将设置在吸收段 63下部的吸收液出口 6301与氧化段 61的亚硫酸铵溶液入 口 6102相连接的亚硫酸铵输送管线 5; • An absorption solution outlet 6301 provided at the lower portion of the absorption section 63 and an ammonium sulfite solution inlet 6102 of the oxidation section 61 are connected to the ammonium sulfite delivery line 5;
一个通过管线分别与设置在氧化段 61底部的吸收液出口 6103与设置在吸收段 63上部的吸收液入口 6302相连接的吸收液循环泵 7; An absorption liquid circulation pump 7 connected to the absorption liquid outlet 6103 provided at the bottom of the oxidation section 61 and the absorption liquid inlet 6302 provided at the upper portion of the absorption section 63 through a pipeline, respectively; 7
一个通过管线与液固分离器 13相连接的硫酸铵干燥器 14, 可优选流化床干燥 益; An ammonium sulfate dryer 14 connected to the liquid-solid separator 13 through a pipeline may be preferably a fluidized bed dryer;
由图 1同时可见, 本发明还包括: It can be seen from FIG. 1 that the present invention further includes:
一个通过管线与脱硫塔 6相连接的再热器 2, 用于提升净化烟气的温度; 一个通过管线与脱硫塔 6底部相连接的过滤器 4, 用于对硫酸铵进行过滤; 一个设置在干燥器 14后端的干燥风机 15, 干燥风机 15的出口与结晶槽 9相连 接, 可使干燥器 14负压操作, 干燥后的热风进入结晶槽 9, 除去夹带在热风中的细 硫酸铵颗粒后再进入脱硫塔 6。 这样, 本发明将不产生额外的废气。 A reheater 2 connected to the desulfurization tower 6 through a pipeline for raising the temperature of the purified flue gas; a filter 4 connected to the bottom of the desulfurization tower 6 through a pipeline for filtering ammonium sulfate; The drying fan 15 at the rear end of the dryer 14 and the outlet of the drying fan 15 are connected to the crystallization tank 9 so that the dryer 14 can be operated under negative pressure. The dried hot air enters the crystallization tank 9 and the fine ammonium sulfate particles entrained in the hot air are removed. Then enter the desulfurization tower 6. In this way, the present invention will not generate additional exhaust gas.
由图 2可见, 所述及的脱硫塔 6为一个立式的塔器, 由下至上依次包括亚硫铵 氧化段 61、 硫酸铵浓缩段 62、 S02吸收段 63、 水洗段 64和除雾沫段 65, 烟气进口 66设置在脱硫塔 6的下部,净化气出口 67设置在脱硫塔 6的顶部,用于氧化的空气 入口 68设置在氧化段 61的侧部, 工艺用水入口 69设置在水洗段 64的上部; . 所述及的氧化段 61设有纵分隔板 6104和横分隔板 6105, 如图 3所示。 横向分 隔板 6105为筛孔板, 筛孔均匀分布, 筛孔直径 d。=5— 15mm, 开孔率为 0.1~0.5%, 纵向分隔板 6104的一端设有通道孔 6106, 从而使液体流道¾蛇形, 亚硫酸铵入口 6102设置在氧化段 61的一侧, 稀硫酸铵出口 6101设置在另一侧, 亚硫酸铵从一端 进入氧化段 61, 从其对面一端离幵氧化段 61, 使未氧化的亚硫酸铵溶液与氧化的硫 铵溶液尽量分开, 不发生返混。 烟气进口 66设置在纵分隔板 6104和横分隔板 6105 的上方, 氧化空气入口 68设置在氧化段 61横分隔板 6105的下方。 It can be seen from FIG. 2 that the desulfurization tower 6 mentioned above is a vertical tower, which includes an ammonium sulfite oxidation section 61, an ammonium sulfate concentration section 62, a S0 2 absorption section 63, a water washing section 64, and a demister from the bottom to the top. In the foam section 65, a flue gas inlet 66 is provided at the lower part of the desulfurization tower 6, a purge gas outlet 67 is provided at the top of the desulfurization tower 6, an air inlet 68 for oxidation is provided at the side of the oxidation section 61, and a process water inlet 69 is provided at The upper part of the water washing section 64; the mentioned oxidation section 61 is provided with a vertical partition plate 6104 and a horizontal partition plate 6105, as shown in FIG. The transverse partition plate 6105 is a sieve hole plate, the sieve holes are evenly distributed, and the sieve hole diameter d. = 5—15mm, opening ratio is 0.1 ~ 0.5%, one end of the vertical partition plate 6104 is provided with a channel hole 6106, so that the liquid flow path is ¾ serpentine, and the ammonium sulfite inlet 6102 is set on one side of the oxidation section 61, The dilute ammonium sulfate outlet 6101 is set on the other side. The ammonium sulfite enters the oxidation section 61 from one end, and leaves the tritium oxidation section 61 from the opposite end, so that the unoxidized ammonium sulfite solution and the oxidized ammonium sulfate solution are separated as much as possible. Back to mix. The flue gas inlet 66 is provided above the vertical partition plate 6104 and the horizontal partition plate 6105, and the oxidation air inlet 68 is provided below the horizontal partition plate 6105 of the oxidation section 61.
所述及的硫酸铵浓缩段 62与氧化段 61之间设有具有气体分布装置和液体收集 器的第一分隔板 6203, 稀硫酸铵溶液入口 6202设置在浓缩段 62的上部, 硫酸铵溶 液的出口 6201设置在浓缩段 62的下部, 氨气入口 6204设置在浓缩段 62的上方; 所述及的 S02吸收段 63与硫酸铵浓缩段 62之间设有具有气体分布装置和液体
收集器的第二分隔板 6303, 吸收段 63中装填有汽液接触元件 6304, 该汽液接触元 件 6304可优选釆用筛板式和填料式。 比如, 在中国专利 99113403.6中, 公布了一种 大孔筛板, 孔径为 10— 25mm, 开孔率 15— 25%, 特别适合本发明的情况。 或优选 采用 50— 150m2/m3规格的规整填料,填料装填高度一般在 2— 5m,适宜高度 3— 4m。 另外, 采用大孔筛板, 一般采用 2— 5块, 适宜为 3— 4块, 吸收液入口 6302设置在 吸收段 63上部, 含有亚硫酸铵的吸收液出口 6301设置在吸收段 63下部, 并通过连 接管线 5与氧化段 61的亚硫酸铵入口 6102相连接。 A first partition plate 6203 with a gas distribution device and a liquid collector is provided between the ammonium sulfate concentration section 62 and the oxidation section 61, and a dilute ammonium sulfate solution inlet 6202 is provided in the upper part of the concentration section 62. The ammonium sulfate solution An outlet 6201 is provided in the lower part of the concentration section 62, and an ammonia gas inlet 6204 is provided above the concentration section 62. A gas distribution device and a liquid are provided between the above-mentioned S0 2 absorption section 63 and the ammonium sulfate concentration section 62. The second partition plate 6303 of the collector and the absorption section 63 are filled with a vapor-liquid contact element 6304. The vapor-liquid contact element 6304 can be preferably a sieve plate type or a packing type. For example, in Chinese patent 99113403.6, a large-pore sieve plate is disclosed with a hole diameter of 10-25 mm and an opening ratio of 15-25%, which is particularly suitable for the situation of the present invention. Or it is preferred to use structured packing with a specification of 50-150m 2 / m 3. The filling height of the packing is generally 2-5m, and a suitable height is 3-4m. In addition, a large-pore screen is used, generally 2-5 pieces, suitably 3-4 pieces. An absorption liquid inlet 6302 is provided in the upper part of the absorption section 63, and an absorption liquid outlet 6301 containing ammonium sulfite is provided in the lower part of the absorption section 63. It is connected to the ammonium sulfite inlet 6102 of the oxidation section 61 through a connection line 5.
水洗段 64 中装填有聚丙烯材质的板波纹规整填料, 型号可采用 125 或 250m2/m3, 装填高度为 0.3—0.6m。 The washing section 64 is filled with polypropylene plate corrugated structured packing. The model can be 125 or 250m 2 / m 3 , and the filling height is 0.3-0.6m.
除雾沫段 65中装填有 250— 500m2/m3的规整波紋填料, 髙度为 0.3— 0.6m。 采用上述的装置对低含硫量的烟气进行处理时, 操作步骤如下: .The defogging section 65 is filled with 250-500m 2 / m 3 structured corrugated packing with a degree of 0.3-0.6m. When the above-mentioned device is used to process low sulfur content flue gas, the operation steps are as follows:.
( 1 )低含硫烟气从烟气入口 66进入脱硫塔 6, 穿过第一分隔板 6203进入浓缩 段 62, 与来自硫酸铵溶液循环槽 12的稀硫酸铵溶液进行热、质交换, 烟气被降温增 湿, 稀硫酸铵溶液被浓缩; 然后烟气穿过第二分隔板 6303进入吸收段 63, 与吸收段 63顶部喷淋而下的吸收液逆流接触, 烟气中的 S02被吸收, 生成亚硫酸铵, 净化后 的烟气穿过水洗段 64和除雾沫段 65后,排出脱硫塔 6,并在再热器 2中与高温烟气 进行换热, 提升温度后由烟囱排空; (1) The low sulfur-containing flue gas enters the desulfurization tower 6 from the flue gas inlet 66, passes through the first partition plate 6203, and enters the concentration section 62, and performs heat and mass exchange with the dilute ammonium sulfate solution from the ammonium sulfate solution circulation tank 12, The flue gas is cooled and humidified, and the dilute ammonium sulfate solution is concentrated. Then the flue gas passes through the second partition plate 6303 and enters the absorption section 63, and comes into countercurrent contact with the absorption liquid sprayed down from the top of the absorption section 63. S0 in the flue gas 2 is absorbed, and ammonium sulfite is generated. The purified flue gas passes through the water washing section 64 and the defogging section 65, and then exits the desulfurization tower 6 and exchanges heat with the high temperature flue gas in the reheater 2. Empty by chimney;
(2)被浓缩的硫酸铵溶液进入结晶槽 9结晶, 然后被送往液固分离器 13, 分离 后的母液返回循环槽 12, 固态硫酸铵则在干燥器 14中被干燥成为商品化肥。 (2) The concentrated ammonium sulfate solution enters the crystallization tank 9 for crystallization, and then is sent to the liquid-solid separator 13, the separated mother liquor is returned to the circulation tank 12, and the solid ammonium sulfate is dried in the dryer 14 to become a commercial fertilizer.
(3 )所述及的亚硫酸铵溶液通过连接管线 5进入氧化段 61, 与进入氧化段 61 的空气进行氧化反应, 生成硫酸铵, 流入循环槽 12后由泵 10送入浓縮段 62。 (3) The ammonium sulfite solution mentioned above enters the oxidation section 61 through the connection line 5 and undergoes an oxidation reaction with the air entering the oxidation section 61 to generate ammonium sulfate, which flows into the circulation tank 12 and is sent by the pump 10 to the concentration section 62.
实施例 1 Example 1
一个 220T/h 的燃煤热电锅炉, 烟气流量为 25 万 Nm3/hr, S02含量为 1500mg/Nm3, 烟气含尘量为 80mg/Nm3, 烟气温度为 140 °C。脱硫塔 6的直径为 6m, 高为 28m。 再热器 2为热管式。烟气经过再热器 2后,温度降为 110Ό,进入脱 硫塔 6。 离幵脱硫塔时, 脱硫尾气中 S02含量为 20mg/Nm3, H3含量为 lmg/Nm3, 水沬含量为 96mg/Nm3。 A 220T / h coal-fired thermoelectric boiler has a flue gas flow of 250,000 Nm 3 / hr, a S0 2 content of 1500mg / Nm 3 , a flue gas dust content of 80mg / Nm 3 , and a flue gas temperature of 140 ° C. The desulfurization tower 6 has a diameter of 6 m and a height of 28 m. The reheater 2 is of a heat pipe type. After the flue gas passes through the reheater 2, the temperature drops to 110 ° F. and enters the desulfurization tower 6. When Depart from the desulfurization tower, desulfurizing tail gas S0 2 content of 20mg / Nm 3, H 3 content lmg / Nm 3, the water content through droplets of 96mg / Nm 3.
吸收段采用 100m2/m3的聚丙烯规整孔板波纹填料, 吸收液流量为 100m3/hr, 硫 铵含量为 7.5 %(wt), 离开吸收段时, 亚硫铵浓度为 0.6%(wt)。
在吸收段, 进氨量按 N/S为 1.45, BP 145kg/hr。 水的加入量为 11.75m3/ r。 硫铵产量为 780kg/hr, 其中硫酸铵含量为 97.8%, 相当于含氮量为 20.8%。 The absorption section uses 100m 2 / m 3 polypropylene structured porous plate corrugated packing, the absorption liquid flow rate is 100m 3 / hr, and the ammonium sulfate content is 7.5% (wt). When leaving the absorption section, the ammonium sulfite concentration is 0.6% (wt ). In the absorption section, the ammonia feed rate is 1.45 according to N / S, and the BP is 145 kg / hr. The amount of water added was 11.75 m 3 / r. The ammonium sulfate production was 780 kg / hr, of which the ammonium sulfate content was 97.8%, which was equivalent to a nitrogen content of 20.8%.
实施例 2 Example 2
一个 670T/h的火力发电机组, 即 200MW, 燃用含硫量在 1.5—2.0%之间的煤., 烟气流量为 80万 Nm3/hr, S02含量为 4200mg/Nm3, 电除尘器为 3电场, 烟气含尘 量为 200mg/Nm3, 烟气温度为 145Ό。 脱硫塔 6的直径为 10m, 髙为 30m。 A 670T / h thermal power unit, namely 200MW, burns coal with a sulfur content between 1.5-2.0%. The flue gas flow is 800,000 Nm 3 / hr, and the S0 2 content is 4200mg / Nm 3 . The device has 3 electric fields, the dust content of the flue gas is 200mg / Nm 3 , and the flue gas temperature is 145 ° F. The desulfurization tower 6 has a diameter of 10 m and 髙 is 30 m.
再热器 2为旋转蓄热式。烟气经过再热器后, 温度降为 116°C , 进入脱硫塔。离 开脱硫塔时, 脱硫尾气中 S02含量为 34mg/Nm3, NH3含量为 lmg/Nm3, 水沫含量为 125mg/Nm The reheater 2 is a rotary heat storage type. After the flue gas passes through the reheater, the temperature drops to 116 ° C and enters the desulfurization tower. Leaving the desulfurization tower, desulfurizing tail gas S0 2 content of 34mg / Nm 3, NH 3 content of lmg / Nm 3, Shuimo content of 125mg / Nm
吸收段釆用 125m2/m3的聚丙烯规整孔板波纹填料, 吸收液流量为 400m3/hr, 硫 铵含量为 17.3 %(wt), 离开吸收段时, 亚硫铵浓度为 1.6%(wt)。 The absorption section was filled with 125m 2 / m 3 polypropylene structured porous plate corrugated packing, the absorption liquid flow was 400m 3 / hr, and the ammonium sulfate content was 17.3% (wt). When leaving the absorption section, the ammonium sulfite concentration was 1.6% ( wt).
在吸收段, 进氨量按 N/S = 1.45, 即 1295kg/hr。 水的加入量控制在 39.5m3/hr。 硫铵产量为 7070kg/hr, 其中硫酸铵含量为 98.0%, 相当于含氮量为 21.0%。
In the absorption section, the ammonia feed rate is N / S = 1.45, which is 1295 kg / hr. The amount of water added was controlled at 39.5 m 3 / hr. The output of ammonium sulfate is 7070 kg / hr, and the ammonium sulfate content is 98.0%, which is equivalent to the nitrogen content of 21.0%.