Project Overview

Coking Technology Co., Ltd. (hereinafter referred to as Coking) has three phases of clean heat recovery coke ovens, each equipped with a lime gypsum desulfurization device at the tail end. There are three desulfurization towers in total, but there is no tar and dust removal device before desulfurization, resulting in low activity of the desulfurization slurry and unstable operation. The slurry needs to be replaced regularly for ten days and a half months, which has caused difficulties for normal production. Therefore, a tar adsorption device needs to be added before desulfurization.

Two original data:

1. Design a flue gas volume of 20+300000 Nm ³/h, with a sulfur content of 4000mg (standard condition, wet basis);

2. Temperature range of 150-180 ℃;

3. The concentration of organic impurities such as tar and carbon black is 80-150mg/Nm3

Processing effect: Tar concentration below 10mg/Nm3

Three common tar flue gas treatment technologies

3.1 The composition of dust removal flue gas in the coking industry is complex and highly hazardous. The gas contains coal dust and various chemical substances, mainly composed of solid suspended solids, benzene soluble substances, benzo [a] pyrene, SO2, NOX, CO, and H2S. Fine dust has the ability to adsorb benzene soluble substances, thereby increasing the harm of such waste gas. Due to the high tar content in smoke and dust, the tar in the flue gas desulfurization project in the coking industry is a headache. The tar in the gas is everywhere, and if necessary treatment measures are not taken, the tar in the flue gas will cause the flue resistance to soar, resulting in low desulfurization slurry activity, decreased system air volume, and ultimately causing the system to malfunction.

3.2 Throughout the country, most enterprises have adopted two methods to deal with tar problems in the coking industry: coke adsorption bin adsorption method and electrostatic capture method. These two methods have been proven through years of practice to be unsatisfactory for the pretreatment of tar. Among them, the adsorption principle of the coke adsorption bin is to pack coke blocks in the bin, and filter and adsorb tar rich smoke and dust through the gaps between coke blocks, thereby achieving the goal of removing tar. This method has a better effect than pre spraying, but the actual resistance is extremely high, and the air volume of the dust removal system is weakened, which seriously affects the overall dust removal effect. In addition, coke attached with tar can be easily ignited by high-temperature sparks inhaled during long-term storage, which poses certain safety hazards and requires high maintenance costs for regular replacement of coke.

3.3 Another method is electrostatic trapping; This method is simple to run and easy to use; However, as the operating time increases, the tar and impurities adhering to the electrode plate affect the purification efficiency and normal operation of the point tar catcher. Although many manufacturers use electrode plate heating and spraying technology to solve the problem of electrode plate sticking, the electric tar catcher still cannot meet the existing environmental requirements. Mainly manifested in excessive tar emissions and benzo [a] pyrene emissions.

3.4 Yancheng Haiyun Environmental Engineering Technology Co., Ltd. was inspired by the adsorption of asphalt flue gas coke powder from other carbon enterprises and the coke powder adsorption system in the coking industry. By spraying hydrated lime powder into the flue gas, tar and VOC components in the flue gas were adsorbed. Adsorption method is a process in which exhaust gas comes into contact with porous solids, causing pollutants to adsorb on the solid surface and separate from the gas flow. Adsorption can occur at different interfaces, and the process of gas or pollutants being adsorbed on the solid (adsorbent) surface is a spontaneous process. For adsorbents and their adsorbates, the amount of adsorbate increases with the surface area. Lime powder itself is a very good adsorbent. Adsorbents generally meet the following requirements: (1) large specific surface area and porosity; (2) Strong adsorption capacity; (3) Good selectivity; (4) The particles are uniform, with good mechanical strength, chemical stability, and thermal stability; (5) Simple production and affordable price;

When the oil content in the flue gas is greater than 4% to 10% (weight percentage), lime powder with a mesh of about 200 can be used as an adsorbent in the silo to adsorb the oil sludge in the flue gas. After the calcium oxide powder is discharged from the silo and fed through the feeding device, the amount of calcium oxide transported is adjusted by the feeding control device, and then uniformly transported to the flue gas tar adsorption device through the pneumatic chute under the action of compressed air; Calcium oxide powder becomes floating in the tar adsorption device and fully mixes, reacts, and adsorbs on the surface with the high flow velocity flue gas entering in reverse, removing harmful substances such as waste oil from the flue gas. After the flue gas containing harmful substances is adsorbed by calcium hydroxide in the tar adsorption device, the calcium hydroxide containing adsorbates, smoke particles, and flue gas enter the first stage transport bed absorption and adsorption reactor,

The discharge port at the rear end of the first stage transport bed absorption adsorption reactor is connected to the feed port of the second stage high turbulence absorption adsorption reactor. At the rear end of the first stage transport bed absorption adsorption reactor and the front end of the second stage high turbulence absorption adsorption reactor, a second calcium based absorption adsorbent addition device is installed, and the specific surface area of the second calcium based absorption adsorbent is ≥ 15m2/g.

The newly added second calcium based absorption adsorbent and the material carried by the flue gas in the secondary high turbulence absorption adsorption reactor form a highly turbulent high specific surface material bed, further adsorbing the coke oil fume to achieve secondary adsorption of coke oil fume. The material adsorbed by coke oil fume aggregates and forms coarser particles in the high turbulence environment, which is conducive to the subsequent removal of smoke by the dust collector. And there will be no significant accumulation of tar in the device, so there is no risk of fire.

The newly added calcium based absorbent, circulating return material, and materials carried by the flue gas in the secondary high turbulence absorption and adsorption reactor are accelerated through the Venturi, and a large number of calcium based absorbent particles are vigorously mixed with the flue gas, fully contacting to form a high specific surface material bed with intense turbulence, greatly enhancing the mass and heat transfer between gas and solid, achieving the secondary adsorption of coke oil fume. The adsorption efficiency of tar smoke accounts for more than 90% of the total adsorption efficiency, and the material that adsorbs coke oil fume aggregates and condenses into coarse particles in the high turbulence environment. Tar is effectively wrapped, which is conducive to the removal of smoke by subsequent dust collectors.

The tar adsorption device equipment includes a tar adsorption tower, calcium oxide powder spray pipe, material fluidized bed, circulating pumping system, primary conveying bed system, and intelligent operating system. The tar adsorption device is located in front of the dust collector or desulfurization device, and is used for the separation of large particles and fine dust in tar flue gas.

Equipment investment estimation: Main equipment investment;XXXTen thousand yuan/Single set