[0020] In order to describe in detail the technical content, structural features, achieved objectives and effects of the present invention, the following is a detailed description in conjunction with the embodiments and accompanying drawings.
[0021] See figure 1 As shown, the white carbon black secondary drying method of this embodiment includes the following steps:
[0022] Step 1. Use spray drying method to dry the silica slurry for the first time, the hot air temperature required for drying is 450-480°C, the drying time is 20-30s, and the exhaust temperature obtained after drying is 80-90°C;
[0023] Among them, the spray drying can be carried out in the spray drying tower. The hot air furnace provides the hot air at 450-480℃ for drying into the spray drying tower. The moisture content of the white carbon black powder obtained after drying is measured to be 4-8wt %, the tail gas obtained after drying contains a lot of water vapor with a temperature between 80 and 90°C.
[0024] Step 2. The white carbon black powder obtained after the first drying is collected by bag filtration and directly sent to the airflow drying tower for the second drying. The hot air temperature required for drying is 150~180℃, and the drying time is 30~50s, the exhaust temperature after drying is 110~120℃;
[0025] Among them, bag filter collection can be carried out in the bag filter silo 1, which is connected to the outlet of the spray drying tower, and is used to capture the moisture content of 4-8wt% after drying by the spray drying tower. And separate the tail gas containing a large amount of water vapor with a temperature between 80 and 90°C (the first drying tail gas). The captured white carbon black powder directly enters the airflow drying tower for the second drying without other transitional processes (such as transfer, temporary storage, etc.), so the heat loss of the white carbon black powder is effectively avoided. The production energy consumption required for the second drying is reduced. Since the object of the second drying is silica powder with a water content of 4-8wt%, the silica powder can be dried at a lower temperature (150-180℃) and within a short time. The water content is reduced to less than 2wt%, and the tail gas obtained after the second drying contains only a small amount of water vapor. The temperature of the tail gas is controlled between 110 and 120 ℃, so it can effectively prevent the white carbon black powder from absorbing water and make the first The water content of the white carbon black powder obtained after secondary drying is stably controlled below 2wt%, which reduces the difficulty of production control and improves the stability of product quality. The tail gas containing a large amount of water vapor with a temperature between 80 and 90 ℃ separated by the bag filter (the first drying tail gas) is directly emptied or subjected to other treatments.
[0026] In this step, in order to improve the drying efficiency and drying effect, the hot air required for drying blows the white carbon black powder from the bottom to the top at a flow rate of 1 to 3 m/s, and a certain number of air-flow drying towers are arranged at intervals or continuously The spirally distributed baffle makes the white carbon black powder conveyed to the outlet of the airflow drying tower in a vortex.
[0027] In this step, the hot air required for the second drying can be provided by a hot air furnace alone, or by the same hot air furnace that provides hot air for the first drying. In order to optimize the production configuration and reduce energy consumption, this The invention preferably adopts a hot air furnace to provide hot air for the first drying and the second drying at the same time. This can reduce equipment costs, improve equipment utilization, reduce equipment energy consumption, optimize the layout of the production site, and the production personnel only need to be responsible To operate a hot blast stove, operation and maintenance costs are also greatly reduced. Since the hot air temperature required for the second drying only needs to reach 150-180℃, it can be obtained by setting up an induced air device to blow a certain amount of cold air into the hot air at 450-480℃ provided by the hot blast stove. The hot air at 150~180℃ also reduces the amount of hot air used, and reduces the amount of hot air that would otherwise require two hot air stoves to be satisfied by one hot air stove, realizing the optimization of production configuration.
[0028] In this step, in order to make full use of the water vapor in the tail gas obtained after the first drying, improve energy utilization and reduce tail gas emissions, the tail gas can be further sprayed by a spray tower to recover the water vapor therein, and the recovery is The hot water can be used in the process of washing the filter cake of silica or for other purposes, thereby improving energy utilization and reducing exhaust emissions; after spraying, the exhaust gas still contains more heat energy and entrained due to the spray zone In order to further improve the energy efficiency and achieve the requirement of zero emission of exhaust gas, the exhaust gas obtained after spraying can be separated by gas-liquid separator to make 99% Liquid moisture is removed to obtain dry hot air (measured at a temperature of about 80°C). After the dry hot air is purified by a purifying air box, purified gas that meets the requirements of the hot blast stove can be obtained. These purified gases are used in the hot blast stove. Under the action of the induced draft fan, it is further heated into the hot air furnace to form 450-480℃ high-temperature hot air, which can be used as the hot air for spray drying tower or airflow drying tower drying. This realizes the first drying exhaust gas recycling, greatly reducing In view of the energy consumed by the hot blast stove to heat the gas, it has been measured that the temperature of the clean air supplied to the existing hot blast stove is generally 25-30 ℃, and the present invention uses the first drying exhaust gas to make the purified gas supplied to the hot blast stove more than The existing clean air supplied to the hot blast stove can reduce the temperature by 50-55°C, and the hot blast stove can save energy and reduce consumption by more than 10%.
[0029] Step 3. The white carbon black powder obtained after the second drying is vacuum-packaged after being collected by bag filtration.
[0030] Among them, bag filter trapping can be carried out in the second bag filter silo. The second bag filter silo is connected with the outlet of the air-flow drying tower, and is used to capture the white water with a water content of less than 2wt% after being dried by the air-flow drying tower. Carbon black powder, and separate tail gas containing a small amount of water vapor with a temperature between 110 and 120 ℃ (second drying tail gas). The captured white carbon black powder is directly vacuum packaged, so as to completely eliminate the water absorption that may occur during the packaging process of the white carbon black powder and other problems that affect product quality, and ensure the stable quality of the product before use. The tail gas containing a small amount of water vapor with a temperature between 110 and 120 ℃ separated by the second bag filter (the second drying tail gas) is directly evacuated or processed.
[0031] In this step, since the second drying tail gas contains only a small amount of water vapor, the second drying tail gas only needs to be purified by the purifying wind box to obtain purified gas that meets the requirements of the hot blast stove, so as to make full use of the first The heat contained in the secondary drying exhaust gas is for the purpose of improving energy efficiency. Under the action of the induced draft fan of the hot blast stove, the purified gas enters the hot blast stove and is further heated to form high temperature hot air of 450-480℃, which can then be used as the hot air required for drying in the spray drying tower or airflow drying tower, thus achieving the second drying of the tail gas. The recycling utilization of the gas achieves the goal of zero exhaust emissions, and greatly reduces the energy consumed by the heating gas of the hot blast stove, so that the purified gas supplied to the hot blast stove can be heated by 80-95 ℃ less than the clean air supplied to the existing hot blast stove. The hot blast stove can save energy and reduce consumption by more than 12%. At the same time, since the second drying tail gas itself is the clean air formed after filtering through the secondary bag, it will not collect dust on the surface of the filter or cloth bag in the purification air box when it is processed by the air box, thereby reducing the filter or cloth bag. The degree of dust collection on the surface reduces the resistance of the air passing through the filter or cloth bag, so that the induced draft fan of the hot blast stove can blow in a sufficient amount of clean air under a relatively low load, thereby extending the service life of the hot blast stove and reducing energy consumption. The purpose of consumption. In this step, the purification air box can be set separately, or the same purification air box used in step 2 can be used to achieve the purpose of optimizing production configuration, that is, reducing equipment costs, improving equipment utilization, reducing equipment energy consumption, and optimizing the layout of the production site. At the same time reduce operation and maintenance costs.
