50% - 99% process flow (pre concentration + final concentration)
- Categories:Process flow and design
- Time of issue:2020-12-15 09:38:30
1. Falling film evaporator (pre concentrator) concentrates 50% of raw alkali 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 (final concentrator) through the concentrated alkali pump, and evenly distributed into each falling film pipe. During the falling process, the liquid film exchanges heat with high-temperature molten salt, and dehydrates into molten alkali. Then, the superheated steam is separated from the separator, and then distributed into two flake machines to make flake alkali, which is weighed and packaged by the semi-automatic packaging machine;
3. 10% white sugar solution prepared from industrial white sugar is added to the pre concentrator 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, coal and other fuels, which burns stably and is easy to control. The generated 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 complete 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.
1. The process adopts double effect evaporation and flash evaporation process, that is, the alkali liquor is concentrated from 50% to 61% by the pre concentrator, 97.5% to 97.5% by the final falling film concentrator, and 97.5% of the molten alkali is flash concentrated to 99% by the flash tank. The process has the characteristics of high efficiency and energy saving.
2. The single tube falling film tube has high heat transfer efficiency, stable product quality and high cost performance.
3. Molten salt furnace: it produces solid alkali with natural gas, hydrogen, gas, coal and other fuels, which is suitable for user requirements. It has the advantages of stable operation, easy control, high thermal efficiency, sufficient waste heat recovery, wide fuel selectivity and so on.
4. Control system: a set of DCS automatic control system can be built separately or centralized in the central control room to realize remote control. The valve with high operating frequency is controlled by computer. The key parameters such as temperature, flow, pressure, current and motor frequency are displayed on the computer screen. At the same time, it can be used as a signal source to control the regulating valve. The start and stop of key pumps and motor variable frequency speed regulation can be controlled on DCS.
5. The ignition of molten salt furnace and the regulation of molten salt temperature are automatically controlled by a separate control system, which can also be imported into DCS automatic control system according to the requirements of users.
After stabilizing the flow through the regulating valve and flowmeter, 50% of the raw alkali is transported to the pre concentrator, and the concentration is increased to 61%. After pressurizing by the concentrated alkali pump and stabilizing the flow through the regulating valve and flowmeter, it enters the final concentrator, and the concentration is increased to 97.5%. The molten alkali with a concentration of 97.5% from the final concentrator enters the flash tank by differential pressure, and the concentration after flash reaches 99%, Then enter the alkali liquor distributor to distribute the flow of alkali liquor, enter two flake alkali machines, make flake alkali, weigh, pack, stack and put into storage, that is, 99% flake alkali.
The secondary steam generated by the final concentrator enters the pre concentrator after being humidified and cooled by condensate, and the excess secondary steam is discharged to the atmosphere through the regulating valve to maintain the stability of the pressure in the heating chamber of the pre concentrator. The secondary steam generated by the pre concentrator enters the surface condenser for condensation to form a high negative pressure, 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 through the condenser on the bubble] surface of the flake caustic soda machine.
2. Condensate: the condensate generated by the pre concentrator is sent to the condensate tank, pressurized by the condensate pump, to the humidifier for humidification, and finally used for the secondary steam and sugarcane water of the humidifier. The excess condensate is sent out of the battery limit.
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 at about 395 ° C 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 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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