阅读说明：本技术 一种提高硫酸盐法制浆黑液蒸发冷凝水品质的方法 (Method for improving quality of evaporation condensate water of sulfate process pulping black liquor ) 是由 顾根生 赵云松 张裕 于 2019-09-11 设计创作，主要内容包括：本发明提供一种提高硫酸盐法制浆黑液蒸发冷凝水品质的方法；通过黑液闪蒸罐产生的含有有机物的闪蒸汽进入板式降膜蒸发器的板式加热器的内腔中上部,闪蒸气冷凝产生的含有有机物的污冷凝液,通过重力作用污冷凝液延板腔向下流动；干净蒸汽进入板式加热器的下部,依靠压差向上流动,与污冷凝液形成错流,且蒸汽-冷凝水之间产生动态的汽-液平衡过程中,污冷凝液中的有机物优先挥发,然后汇聚至加热板片的后冷凝区冷凝,同时蒸汽中的水蒸汽在主冷凝区优先冷凝,并在重力作用下到达加热器底部；主冷凝区冷凝液中的有机物被挥发,在后冷凝区形成的含有COD成分的冷凝水,排出系统另作处理。本发明提高蒸汽冷凝水的品质,降低蒸汽冷凝水COD值。(The invention provides a method for improving the quality of evaporation condensate water of black liquor prepared by a sulfate method; the flash steam containing organic matters generated by the black liquor flash tank enters the middle upper part of the inner cavity of the plate heater of the plate-type falling film evaporator, and the sewage condensate containing organic matters generated by the condensation of the flash steam flows downwards along the plate cavity under the action of gravity; clean steam enters the lower part of the plate heater, flows upwards by means of pressure difference, forms cross flow with the sewage condensate, and organic matters in the sewage condensate preferentially volatilize and then converge to a post-condensation area of the heating plate for condensation in the process of generating dynamic steam-liquid balance between steam and condensate, and meanwhile, water steam in the steam preferentially condenses in a main condensation area and reaches the bottom of the heater under the action of gravity; organic matters in the condensate in the main condensation area are volatilized, and the condensate water containing COD components formed in the post condensation area is discharged out of the system for additional treatment. The invention improves the quality of the steam condensate water and reduces the COD value of the steam condensate water.)

1. A method for improving the quality of evaporation condensate water of black liquor prepared by a sulfate method is characterized by comprising the following steps: the system comprises an independent thin black liquor flash evaporation tank, a plate type falling film evaporator with an independent flash evaporation steam inlet, a plate type surface condenser with an independent non-condensed steam inlet and a plate type falling film evaporator with an independent flash evaporation steam inlet;

the flash steam containing organic matters generated by the black liquor flash tank enters the middle upper part of the inner cavity of the plate heater of the plate-type falling film evaporator, and the sewage condensate containing organic matters generated by the condensation of the flash steam flows downwards along the plate cavity under the action of gravity; clean steam enters the lower part of the plate heater, flows upwards by means of pressure difference, forms cross flow with the sewage condensate, and organic matters in the sewage condensate preferentially volatilize and then converge to a post-condensation area of the heating plate for condensation in the process of generating dynamic steam-liquid balance between steam and condensate, and meanwhile, water steam in the steam preferentially condenses in a main condensation area and reaches the bottom of the heater under the action of gravity; organic matters in the condensate in the main condensation area are volatilized, and the condensate water containing COD components formed in the post condensation area is discharged out of the system and enters the next working procedure.

2. The method for improving the quality of the evaporation condensate water of the black liquor of the pulping by the sulfate method according to claim 1, which is characterized in that: and the independent thin black liquor flash tank separately leads out dirty flash steam evaporated by the thin black liquor flash tank; the dirtier flash gas evaporated by the weak black liquor flash drum is not incorporated into the clean heating steam.

3. The method for improving the quality of the evaporation condensate water of the black liquor of the pulping by the sulfate method according to claim 1, which is characterized in that: the method comprises the following steps that non-condensed steam containing high-concentration organic matters in an evaporation station enters the middle upper part of an inner cavity of a plate heater of a plate type surface condenser, the non-condensed steam is condensed to generate a sewage condensate containing the high-concentration organic matters, the condensate flows downwards along a plate cavity under the action of gravity and is directly contacted with rising clean steam, and in the steam-liquid balance process generated between steam and condensate, the organic matters in the condensate volatilize firstly and are converged to a post-condensation area of a heating plate sheet for condensation; and the water vapor in the steam is firstly condensed in the main condensation area until the condensate reaches the bottom of the heater, so that the organic matters in the condensate in the main condensation area are volatilized, and the condensate water containing COD component formed in the post condensation area is discharged out of the system and enters the next procedure.

4. The method for improving the quality of the evaporation condensate water of the black liquor of the pulping by the sulfate method according to claim 3, which is characterized in that: the organic-rich steam-containing non-condensable gas is not incorporated into the clean heating steam.

Technical Field

The invention belongs to the field of pulping wastewater treatment in the papermaking industry, and particularly relates to a method for improving the quality of steam condensate water by a sulfate pulping black liquor evaporation system.

Background

In the evaporation process of the black liquor of the chemical sulfate pulping wastewater, the black liquor contains organic volatile substances with higher concentration, so that organic substances in flash steam of the high-temperature dilute black liquor are preferentially volatilized, and the flash steam contains the organic substances with higher concentration. Meanwhile, the non-condensed steam discharged by the evaporation system also contains organic matters with higher concentration. In the design of the traditional evaporation system, the flash steam and the non-condensed steam are directly merged into the heating steam of the plate-type falling film evaporator or the plate-type surface condenser with the latter effect and enter the lower parts of the heat exchange plates of the plate-type falling film evaporator or the plate-type surface condenser along with the heating steam. Because the heating steam is polluted, the steam stripping effect is reduced, the steam condensate also contains high-concentration organic matters, the COD value of the steam condensate is higher, and the cyclic utilization of the steam condensate in a factory is influenced;

in view of the above disadvantages, a method for improving the quality of the steam condensate is needed, which can improve the quality of the steam condensate and reduce the COD value of the steam condensate.

Disclosure of Invention

The invention aims to provide a method for improving the quality of steam condensate water, and the COD value of the steam condensate water is reduced.

The invention provides the following technical scheme:

a method for improving the quality of evaporation condensate water of black liquor prepared by a sulfate method comprises the following steps: the design of an independent thin black liquor flash tank, a plate-type falling film evaporator with an independent flash steam inlet and a plate-type surface condenser with an independent non-condensed steam inlet;

wherein, the independent thin black liquor flash tank is used for independently leading out dirty flash steam evaporated by the thin black liquor flash tank;

dirty flash steam evaporated by the thin black liquor flash tank is not merged into clean heating steam, so that the heating steam is not polluted, and the self-stripping effect of the plate-type falling-film evaporator is improved;

dirty flash steam generated by the thin black liquor flash tank independently enters the upper part of a heat exchange plate of a plate-type falling film evaporator of the plate-type falling film evaporator for condensation, and dirty condensate can flow downwards along a plate cavity; the flow distance inside the heat exchange plate is increased to the height of the whole heating plate, the time of the steam stripping action is prolonged, and the steam stripping effect is improved.

And the non-condensable gas (rich in COD component) containing steam discharged by each effect evaporator of the evaporation station is independently introduced into the upper part of the heat exchange plate of the plate-type surface condenser for condensation, and the dirty condensate can flow downwards along the plate cavity; the flow distance inside the heat exchange plate is increased to the height of the whole heating plate, the time of the steam stripping action is prolonged, and the steam stripping effect is improved.

Clean steam can enter the lower part of the plate-type falling-film evaporator or the plate-type surface condenser and flows upwards through pressure difference and forms cross flow with the sewage condensate, and a dynamic steam-liquid balance process is generated between the steam and the sewage condensate in the flowing process. In the process, organic matters in the sewage condensate are continuously volatilized again and finally converged to a post-condensation area of the heating plate for condensation; meanwhile, water vapor in the steam is preferentially condensed in the main condensation area and reaches the bottom of the heater under the action of gravity. At the moment, most of organic matters in the condensate of the main condensation area are volatilized, and finally, condensate water with a very low COD value is obtained. While the dirty condensate water formed in the post-condensation zone is rich in most COD components and is discharged out of the system for additional treatment.

The invention has the beneficial effects that:

through the improvement of the invention, the COD content in the steam condensate can be reduced to below 50 percent of the original design, necessary guarantee is provided for the reuse of the condensate in a factory, and the invention has very obvious economic benefit and practical significance.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 is a block diagram of the present invention;

labeled as: 1. a plate falling film evaporator; 2. a plate surface condenser; 3. a housing; 4. a heat exchange plate; 5. a steam distribution box; 6. an independent flash steam inlet; 7. an independent non-condensable gas inlet; 8. a noncondensable gas collection box; 9. a feed liquid circulating pump; 10. an independent thin black liquor flash tank; 411. heating the steam; 12. flash evaporation gas; 13. non-condensable gas; 14. steam condensate water; 15. dirty condensed water; 16. feeding dilute black liquor; 17. concentrating black liquor; 18. a vacuum pump interface; 19. a circulating cooling water inlet; 20 circulating cooling water outlet.

Detailed Description

As shown in fig. 1, the high-temperature feeding thin black liquor enters an independent thin black liquor flash tank 10, dirty flash steam 12 which is flashed out can be independently collected and is independently sent to an independent flash steam inlet 6 of the plate-type falling-film evaporator 1 with the latter effect, so that the condition that the dirty flash steam and the heating steam 11 are mixed to pollute the heating steam in the traditional device is avoided, clean heating steam 11 is obtained, and the self-stripping effect of the plate-type falling-film evaporator 1 is greatly improved. The dirty flash steam 12 enters the middle upper part (inner cavity) of the heat exchange plate 4 of the plate-type falling-film evaporator 1, the dirty flash steam 12 begins to condense, and the produced dirty condensate also contains higher-concentration organic matters. The dirty condensate flows downwards along the plate cavity under the action of gravity; clean heating steam 11 enters the lower part of the heat exchange plate 4 of the plate-type falling-film evaporator 1 and flows upwards by virtue of pressure difference to form convection with the sewage condensate to continuously reheat the sewage condensate, so that a dynamic steam-liquid balance process is generated. In the process, organic matters in the sewage condensate are preferentially volatilized and are continuously gathered to a post-condensation area of the heat exchange plate 4 for condensation; meanwhile, water vapor in the steam is preferentially condensed in the main condensation area and reaches the bottom of the heater under the action of gravity, at the moment, most of organic matters in the condensate 14 in the main condensation area are volatilized, the COD value of the condensate 14 in the main condensation area is greatly reduced, and relatively clean steam condensate 14 is obtained.

The highly polluted non-condensable gas 13 containing steam is conveyed to the middle and upper part (inner cavity) of the heat exchange plate 4 of the plate-type surface condenser 2 through a pipeline, the condition that the non-condensable gas containing steam and the heating steam 11 in the traditional device are mixed to pollute the heating steam is avoided, the clean heating steam 11 is obtained, and the self-stripping effect of the plate-type surface condenser 2 is greatly improved. The highly contaminated steam-containing non-condensable gas 13 starts to condense and the resulting contaminated condensate likewise contains a higher concentration of organic matter. The condensate flows downwards along the plate cavity under the action of gravity, a vapor-liquid balance process can be generated in the process, and in the process, organic matters in the condensate are preferentially volatilized and are continuously gathered to a post-condensation area of the heat exchange plate 4 for condensation; meanwhile, the water vapor in the steam is preferentially condensed in the main condensation area until the condensate reaches the bottom of the heater, at the moment, most of organic matters in the condensate in the main condensation area are volatilized, the COD value of the condensate is greatly reduced, and cleaner steam condensate water 14 is obtained.

Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art will understand that various changes, modifications and substitutions can be made without departing from the spirit and scope of the invention as defined by the appended claims. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.