Prehydrolysis sulfate dissolving slurry cooking equipment
The project introduces metso's dissolving pulp production technology, and the daily production of coniferous wood pulp is 350t. The prehydrolysis sulfate method is used for cooking operation, and the cooking capacity is 375adt/d.
This project adopts 3 sets of vertical batch cooking pots with a volume of 400m3. It is the largest vertical cooking pot made in China. There are 2 black liquor tanks, 1 replacement tank, 1 hot white tank, and 1 cold tank. 1 set of white liquor tank, 1 set of heat exchanger and 1 set of exhaust gas suction treatment equipment.
The cooking pot has a volume of 400 m3, a container inner diameter of 5.8 m, a container height of about 20 m, and an overall height of about 22 m. The height to diameter ratio of the cooking pot is 3.8, which ensures an even distribution of the circulating liquid in the cross section of the container. In addition to the conventional alkaline liquid in the production process of the sulphate method, an acidic liquid is produced in the prehydrolysis sulphate production process, so acid-resistant duplex stainless steel is used as the main material, and the rest is made of carbon steel.
The upper part of the pot body is provided with an annular sieve plate for circulating and returning liquid medicine, about 20m2, and a hole diameter of 6mm; the middle liquid extraction port sieve plate is about 30m2, and the aperture is 6mm; the sieve plate is made by punching holes, and the back of the plate body is provided with reinforcing ribs. board. The steamer pot neck is provided with a steam potter to increase the amount of pot and even the distribution of the wood chips, and at the same time, the wood chips can be heated to eliminate the air contained in the wood chips.
There are 9 dilution water nozzles in the lower cone of the pot body, and a dilution water port is also arranged at the discharge elbow to dilute the slurry. A set of weighing elements are installed at the legs of the cooking pot to measure the weight of the material in the pot.
An external level switch is arranged on the outside of the pot to measure the high level of material in the pot online. The middle part of the cooking pot is equipped with a direct steam heating device on the circulating liquid circulation pipe of the circulating pump. The mixing flow type is provided with two steam nozzles, which can uniformly spray the medium pressure steam into the circulating chemical liquid to avoid excessive vibration and noise.
In addition to the steam inlet port on the liquid circulation pipe and the steam port on the steam potter, there is a steam inlet port in the lower taper of the cooking pot, which can be added with medium or low pressure steam according to the process requirements. Different from traditional kraft cooking pots.
There are two pressure black liquor tanks and one replacement liquid tank in the tank area. The pressure black liquor tank has a volume of 550m3, a diameter of 5.5m, a container cylinder height of more than 20m, an upper and a lower head structure, and a skirt support form. Due to the acidic fluid that may be generated by the reflux of the cooking pot, the portion of the cylinder in contact with it is made of duplex stainless steel, and the support portion of the skirt is made of carbon steel.
As with the cooking pot, due to the external dimensions, the construction and installation of the black liquor tank is also carried out by means of segmentation and branch manufacturing in the manufacturing plant, and the installation method is carried out by means of sectional lifting, combination and flip-chip installation at the installation site. The black liquor tank is provided with a steam defoaming device at the exhaust gas discharge, and the droplets after the foam collapse fall back into the black liquor tank, thereby reducing the heat exchange load and the pipeline deposition problem caused by the droplets in the exhaust gas entrainment.
The replacement tank has a volume of 1200m3, a diameter of 10m, a container cylinder height of 15.3m, a flat bottom form, stainless steel material, a defoaming structure inside the equipment, and an automatic mechanical defoamer at the top exhaust port for defoaming and odor Discharge to the collection device.
The black and white liquid heat exchange system is equipped with 5 heat exchangers, one for the black liquor cooling of the washing section to the cooking section, one for the white liquor heating, and three for the hot black liquor. Cooling, heat storage and heat exchange of white liquor and clean water. The five heat exchangers are all shell-and-tube type structures, which are vertical and horizontal according to the needs of the workshop equipment layout. Due to the high pressure and high temperature of the cooking process and the water hammer phenomenon caused by the production operation, the frequent and frequent changes of cold and heat, the harsh working conditions, the pressure difference problem, etc., as the key equipment for heat conversion, the heat exchanger is selected, Design and manufacturing need to consider all influencing factors in order to ensure normal and safe use.
The complete set is made of stainless steel. In this project, due to the characteristics of the factory site, the condensing system, collection system, sewage collection and storage system can only be placed in separate areas and in sections. This system has solved this problem well. Due to the characteristics of this system, it is not only suitable for the pre-hydrolysis kraft pulping process, but also the conventional kraft pulping process.