Main Characteristics of the APMP pulping process include high whiteness, high yield, low chemical use, less pollution, etc. It is a new high-yield pulping process. Fewer chemicals are used in the bleaching process, and APMP pulp is different from chemical pulp (which produces a large amount of black liquor). so the APMP process is environmentally friendly.
A.Screw Conveyor: various specifications and diameters of serial products. Main materials of the equipment include carbon steel and stainless steel according to different processing requirements.
B. Tearing Machine.
C. Heat Recovery Equipment: normal pressure scrubber and pressure scrubber
D. Thickening Equipment.
E. Container: wood chip bin, latency chest.high concentration bleaching tower, filter,etc.
The production line consists of eleven main processes, including chip washing, first stage impregnation, second stage impregnation, first stage pulping, high concentration bleaching, second stage pulping, screening, concentration, chemical preparation, heat recovery, and slurry regrinding.
The wood chips from the preparation first enter the wood chip balance bin to buffer the amount of wood chips entering the pulping system, and the wood chips stay for 20 minutes.
The wood chips in the chip warehouse enter the chip washing machine through a metering screw. In the chip washing machine, impurities such as dust and sand brought by the chips are removed, and the washed chips are pumped into the dehydration screw through a chip pump.
The conveying concentration of the wood chip pump is 5%. The dehydration screw is lined with a sieve plate, and a large amount of water is removed from the sieve plate and returned to the washing water tank. The wood chips are transported by the screw to the atmospheric pressure silo, where they are steamed to about 80 ℃ to remove air from the wood chips. Enter the MSD spiral extrusion and loosening machine through the second metering screw.
Wood chips are compressed to 60% dryness in the MSD spiral extrusion and loosening machine, and then enter the first stage of the impregnator to come into contact with the medicinal liquid. The medicinal liquid is composed of four chemicals: alkali, hydrogen peroxide, chelate total (DTPA), and sodium silicate.
After the first pre impregnation spiral impregnation, the wood chips enter the first reaction chamber; The retention time is 20 minutes, followed by entering the second stage impregnator, where chemicals of the same composition are added. Alkali is added to ensure the strength of the pulp, while hydrogen peroxide is added to improve the brightness of the pulp. DTPA and sodium silicate are stabilizers for peroxides. The wood chips from the second stage impregnator enter the second stage reaction chamber, and the wood chips stay in the reaction chamber for 45 minutes to complete the bleaching and carbonylation reactions of the wood chips.
The wood components contained in the wastewater extruded by the second MSD spiral extrusion and loosening machine inhibit the bleaching reaction. The BOD and COD of this wastewater account for 25-30% of the entire system.
The wood chips after the second stage reaction chamber are compressed into wood chips with a dryness of about 45% through the PLUG SCREW FEEDER, and then enter the first stage pressure pulping machine for pulping. The ground slurry is fed into the slurry steam separator through a spray tube, and the secondary steam generated by the slurry enters the heat recovery system. The slurry enters the bleaching tower through the PLUG SCREW DISCHARGER and cooling screw.
The pulp completes the bleaching reaction in the bleaching tower, with a retention time of 1 hour, a bleaching temperature of 70 ℃, and a bleaching concentration of 30%. A scraper discharge device is installed at the bottom of the bleaching tower, and the pulp at the bottom of the tower is diluted with water to a 10% concentration. It is pumped into screw press through a medium concentration pump to wash the pulp and concentrate it.
The pulp from the screw press enters the second stage pressure grinding machine through a horizontal conveyor screw and a plug screw feeder. The ground slurry is sprayed into the second stage pulp steam separator through a discharge pipe, and then enters the recreational pulp pool through a plug screw unloader.
The pulp pump after submergence is sent to a low concentration pressure screen for screening, and the screened good slurry enters a multi disc thickener for concentration and washing of the pulp. The pulp concentration from the multi disc is 10%. The washed pulp is sent to the medium concentration slurry storage tower for storage by the medium concentration pulp pump and used for paper operation by the paper machine.
The pulp from the pressure screen and the good pulp from the first and second stages of the desander are pumped into the inclined screen for dehydration before entering the ungrinsed slurry tank. The slurry is then pumped to the T double disc refiner for re grinding before entering the ground pulp tank
After being screened by the pulp pressure screen, the good pulp enters the multi disc thickener, and the pulp from the pulp pressure screen enters the first stage of the desander for circulation.
