32% - 99% process flow (3 + 2 process)
1. Adopt double effect countercurrent falling film production process to evaporate 32% of raw alkali and concentrate it to 61% of high concentration liquid alkali;
2.61% alkali liquor is pressurized and transported to the upper part of the final falling film concentrator through the concentrated alkali pump. After distribution and orifice flow restriction, it enters each falling film pipe. During the falling process, the liquid film exchanges heat with high-temperature dissolved salt, and dehydrates into molten alkali. Then, the superheated steam is separated from the finished product separator, and then enters the two parallel flake alkali machines after adjusting the flow through the alkali liquor distributor to make flake alkali, and then enters the semi-automatic packaging machine for weighing and packaging respectively;
3. 10% white sugar solution prepared from industrial white sugar is added to the I-Effect falling film evaporator to remove sodium chlorate, so as to reduce the corrosion of concentrated alkali to nickel equipment;
4. The molten salt furnace uses natural gas, hydrogen, gas and coal as fuel, which can be burned alone or mixed in any proportion, which is convenient for control and makes the operation more stable. The high-temperature flue gas passes through the air preheater to fully recover its waste heat;
5. In order to ensure that the flake alkali is cooled and in good condition, the cooling water temperature shall be 32 ° C and the closed-circuit circulation shall be realized;
6. The temperature of vacuum water shall be ≤ 32 ° C, and complete closed-circuit circulation shall be realized;
7. Apply DCS to the unit to make the molten salt furnace system and alkali system operate safely and stably;
8. The dust removal fan is used to suck and wash the alkali dust, so as to reduce the pollution of alkali dust to the environment;
9. The unit can produce both 50% liquid alkali and 99% flake alkali.
Brief description of process flow
32% of the raw alkali is transported to the II effect falling film evaporator through the raw alkali pump, and the concentration is increased to 47%. Then it is transported to the I effect falling film evaporator through the 47% alkali record and the I effect condensate preheater, and the concentration is increased to 61%. Finally, it is transported to the final concentrator through the concentrated alkali pump, and evenly enters each falling film pipe. During the descent process, the alkali liquor is pulled into a uniform liquid film by high-speed steam and heat exchanged with high-temperature molten salt, Dehydration is molten alkali. Then, it is fully separated from the superheated steam in the finished product separator, and the molten alkali enters the alkali liquor distributor according to the level difference. After the flow is adjusted by the alkali liquor distributor, it is distributed to two flake alkali machines to make flake alkali, weighed, packaged and stacked for storage, that is, 99% flake alkali.
The steam from the steam system enters the I-Effect falling film evaporator. The secondary steam generated by the I-Effect falling film evaporator and the secondary steam generated by the final falling film concentrator enter the ii-effect falling film evaporator at the same time. The secondary steam generated by the ii-effect falling film evaporator enters the surface condenser and condenses after indirect heat exchange with the circulating water to form a vacuum, and the non condensable gas is pumped out by the vacuum pump.
(1) Circulating water: the low-temperature water from the circulating water system is sent back to the circulating water system for cooling through the pump after heat exchange between the flake alkali machine and the surface condenser;
(2) Condensate: the high-temperature condensate produced by effect I falling film evaporator is used for 47% alkali liquor to recover its heat. The condensate produced by Effect II falling film evaporator is sent to the condensate tank, pressurized by the condensate pump, to the humidifier for humidification. Finally, the secondary steam and sugarcane water of the concentrator are used, and the excess condensate is sent out of the battery limit for use.
(3) Pure water: the pure water sent by the pure water system is used for pump seal cooling and cleaning pipeline equipment during system startup and shutdown.
Molten salt system: the molten salt of about 395 ° C sent from the molten salt storage tank is heated to about 425 ° C in the molten salt heating furnace and sent to the final concentrator to provide the heat required for concentration. After heat exchange, it flows back to the molten salt storage tank; The fuel required for heating molten salt is natural gas, hydrogen, gas, coal and other fuels. After the pressure is stabilized by the pressure reducing and stabilizing valve group of the burner, the gas enters the burner for combustion after the flow is adjusted by the load regulating device. The cold air is sent to the air preheater through the blower to exchange heat with the flue gas from the molten salt furnace, and then enters the furnace of the molten salt furnace for mixed combustion with natural gas. After the heat is transferred to the molten salt through the coil of the molten salt furnace, it becomes high-temperature flue gas. After the heat is recovered by the air preheater, it is sent to the chimney for discharge.
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