Step adjusting system for pH of spraying slurry of wet desulphurization absorption tower

Abstract

The utility model discloses a wet desulphurization absorption tower spraying slurry pH gradient adjusting system which comprises an absorption tower, and an absorption tower slurry pool, a tray and a spraying layer with spraying slurry pH gradient increasing are sequentially arranged in the absorption tower from bottom to top. The spraying layers at least comprise a first spraying layer, a second spraying layer and a third spraying layer which are sequentially arranged from bottom to top and are used for spraying slurry, and the pH of the slurry is gradually increased in a stepped manner. The device disclosed by the utility model has the beneficial effects that the pH value of the spraying slurry of the spraying layer is controlled to be 5.4-6.4, and the high-pH slurry is beneficial to SO2 absorption, so that the desulfurization efficiency is improved, and ultralow emission of SO2 in flue gas is realized; the pH value of the slurry in the slurry pool of the absorption tower is controlled to be 4.5-5.5, and the low-pH slurry enables limestone to be easy to dissolve and facilitates oxidation of a desulfurization byproduct calcium sulfite and crystallization of gypsum, so that the quality of the gypsum is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of environmental protection, and in particular relates to a pH step adjustment system for spray slurry in a wet desulfurization absorption tower. Background Art

[0002] In the limestone-gypsum wet flue gas desulfurization process, the slurry pH is one of the important parameters that affect the desulfurization efficiency. Too low or too high pH values ​​are not conducive to the safe and economical operation of the system. High pH values ​​are conducive to the absorption of SO2, but the dissolution of limestone is inhibited. At the same time, a large amount of limestone and calcium sulfite will appear in the desulfurization by-products, and the gypsum crystallization is poor and the gypsum dehydration is difficult. Low pH values ​​are conducive to the dissolution of limestone and the oxidation of calcium sulfite, but low pH values ​​will inhibit the absorption of SO2, resulting in low absorption efficiency of SO2 in flue gas and reduced desulfurization efficiency. In view of the problem that pH affects wet desulfurization, one of the solutions is to add alkali solution to the circulation pipe of the absorption tower to adjust the pH value of the spray slurry.

[0003] Patent document CN113413753A discloses a method for adjusting the pH of the slurry in the slurry pool of a high-sulfur coal absorber to 4.8-5.3 and adding alkali solution to the inlet and outlet pipes of some circulating pumps to control the pH of the spray slurry in the spray layer in layers. The patent adds alkali solution to the absorber slurry pool and the inlet and outlet pipes of the circulating pump respectively, and the alkali adding method is complicated. Patent document CN104645817B discloses a system for adding alkali solution to the inlet pipe of the absorber circulating pump to control the pH of the slurry at the bottom of the absorber to 4.8-5.3. These patents disclose methods for adjusting the pH of the slurry in the slurry pool of the absorber, but the system is complex and costly, and none of them discloses how to regulate the pH of the spray slurry in the spray layer of the absorber, especially how to regulate the pH of the spray layer slurry in a step-by-step manner. Utility Model Content

[0004] The purpose of the utility model is to provide a pH step adjustment system for the spray slurry of a wet desulfurization absorption tower, which not only solves the problem that high pH slurry is not conducive to the dissolution of limestone and the oxidation and crystallization of desulfurization by-product gypsum, but also solves the problem that low pH slurry is not conducive to SO2 absorption and affects the desulfurization efficiency.

[0005] The purpose of the utility model is achieved through the following technical solutions:

[0006] A wet flue gas desulfurization absorption tower spray slurry pH step adjustment system comprises an absorption tower, in which an absorption tower slurry pool, a tray and a spray layer for spraying slurry with increasing pH step are arranged in sequence from bottom to top, and the spray layer comprises at least a first spray layer, a second spray layer and a third spray layer which are arranged in sequence from bottom to top and spray slurry with increasing pH step.

[0007] Furthermore, the absorption tower is provided with a flue gas inlet located between the absorption tower slurry pool and the tray, and the absorption tower is also provided with a demister located above the spray layer.

[0008] Furthermore, the first spray layer is a spray pipe for spraying slurry at pH 5.4±0.05, the second spray layer is a spray pipe for spraying slurry at pH 5.6±0.05, and the third spray layer is a spray pipe for spraying slurry at pH 5.8±0.05.

[0009] Furthermore, the spraying layer also includes a fourth spraying layer and a fifth spraying layer which are arranged sequentially from bottom to top starting from the third spraying layer and spray the slurry with increasing pH levels.

[0010] Furthermore, the fourth spray layer is a spray pipe for spraying slurry at pH 6.0±0.05, and the fifth spray layer is a spray pipe for spraying slurry at pH 6.2±0.05.

[0011] Furthermore, the spraying layer also includes a sixth spraying layer which is arranged sequentially from bottom to top starting from the fifth spraying layer and sprays the slurry with a pH value in a stepwise increasing manner.

[0012] Furthermore, the sixth spray layer is a spray pipe for spraying slurry at pH 6.4±0.05.

[0013] Furthermore, each spray layer is independently equipped with a slurry supply subsystem.

[0014] Furthermore, the slurry supply subsystem includes an inlet pipe, an outlet pipe and a slurry circulation pump, the absorption tower slurry pool is connected to the inlet pipe, the inlet pipe is connected to the slurry circulation pump, the slurry circulation pump is connected to the outlet pipe, the outlet pipe, the limestone slurry pipe is connected to the inlet pipe.

[0015] Furthermore, the limestone slurry pipeline is provided with a limestone slurry valve, and the outlet pipeline is provided with a pH meter.

[0016] Beneficial effects of the utility model:

[0017] (1) The pH of the spray slurry in the spray layer is controlled at 5.4-6.4. High pH slurry is conducive to SO2 absorption, improves desulfurization efficiency, and achieves ultra-low SO2 emissions in flue gas.

[0018] (2) The pH of the slurry in the absorption tower slurry pool is controlled at 4.5-5.5. The low pH slurry makes the limestone easy to dissolve and is conducive to the oxidation of the desulfurization by-product calcium sulfite and the crystallization of gypsum, thereby improving the quality of gypsum.

[0019] The aforementioned main scheme of the utility model and its further options can be freely combined to form multiple schemes, all of which are schemes that can be adopted and protected by the utility model; and in the utility model, (non-conflicting options) options and other options can also be freely combined. After understanding this scheme, those skilled in the art can understand that there are many combinations based on the existing technology and common knowledge, all of which are technical schemes to be protected by the utility model, and they are not exhaustively listed here. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of the utility model.

[0021] In the figure: 1. absorption tower, 11. absorption tower slurry pool, 12. spray layer, 12-1. first spray layer, 12-2. second spray layer, 12-3. third spray layer, 12-4. fourth spray layer, 12-5. fifth spray layer, 12-6. sixth spray layer, 13. demister, 14. tray, 2. slurry circulation pump, 21. inlet pipe, 22. outlet pipe, 3. limestone slurry pipe, 4. pH meter, 5. limestone slurry valve. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with specific embodiments and drawings.

[0023] Example 1

[0024] refer to Figure 1 As shown, a wet flue gas desulfurization absorber spray slurry pH cascade adjustment system includes an absorber 1, an absorber slurry pool 11, a spray layer 12, a demister 13, a tray 14 and a slurry supply subsystem, the spray layer 12 includes at least a first spray layer 12-1, a second spray layer 12-2 and a third spray layer 12-3, and a fourth spray layer 12-4, a fifth spray layer 12-5 and a sixth spray layer 12-6 are arranged as needed, and the slurry supply subsystem includes a slurry circulation pump 2, an inlet pipe 21, an outlet pipe 22, a limestone slurry pipe 3, a pH meter 4 and a limestone slurry valve 5.

[0025] The absorber 1 includes an absorber slurry pool 11, a tray 14, a spray layer 12 with a stepwise increase in pH value of the spray slurry, and a demister 13. The absorber 1 is provided with a flue gas inlet between the absorber slurry pool 11 and the tray 14, and the demister 13 is located above the spray layer 12.

[0026] The spray layer 12 at least includes a first spray layer 12-1, a second spray layer 12-2 and a third spray layer 12-3 which are arranged in sequence from bottom to top and spray the slurry with increasing pH levels. If necessary, the spray layer 12 also includes a fourth spray layer 12-4, a fifth spray layer 12-5 and a sixth spray layer 12-6 which are arranged in sequence from bottom to top starting from the third spray layer 12-3 and spray the slurry with increasing pH levels.

[0027] The first spray layer 12-1 is a spray pipe for spraying slurry at pH 5.4±0.05, the second spray layer 12-2 is a spray pipe for spraying slurry at pH 5.6±0.05, the third spray layer is a spray pipe for spraying slurry at pH 5.8±0.05, the fourth spray layer 12-4 is a spray pipe for spraying slurry at pH 6.0±0.05, the fifth spray layer 12-5 is a spray pipe for spraying slurry at pH 6.2±0.05, and the sixth spray layer 12-6 is a spray pipe for spraying slurry at pH 6.4±0.05.

[0028] Each spray layer is independently equipped with a slurry supply subsystem. The slurry supply subsystem includes an inlet pipe 21, an outlet pipe 22 and a slurry circulation pump 2. The absorber slurry pool 11 is connected to the inlet pipe 21, the inlet pipe 21 is connected to the slurry circulation pump 2, the slurry circulation pump 2 is connected to the outlet pipe 22, and the outlet pipe 22 and the limestone slurry pipe 3 are connected to the inlet pipe 21. The limestone slurry pipe 3 is provided with a limestone slurry valve 5, and the outlet pipe 22 is provided with a pH meter 4.

[0029] The working process of the utility model is as follows: the amount of limestone slurry added to the inlet pipe 21 is adjusted by the limestone slurry valve 5, and the display value of the pH meter 4 on the outlet pipe 22 is changed, so that the pH of the slurry in the outlet pipe is 5.4-6.4, and the pH of the spray slurry of the corresponding spray layer increases step by step from bottom to top.

[0030] When there are three spray layers, the pH values ​​of the spray slurry in the spray layers are 5.4, 5.6, and 5.8 from bottom to top respectively; when there are four spray layers, the pH values ​​of the spray slurry in the spray layers are 5.4, 5.6, 5.8, and 6.0 from bottom to top respectively; when there are five spray layers, the pH values ​​of the spray slurry in the spray layers are 5.4, 5.6, 5.8, 6.0, and 6.2 from bottom to top respectively; when there are six spray layers, the pH values ​​of the spray slurry in the spray layers are 5.4, 5.6, 5.8, 6.0, 6.2, and 6.4 from bottom to top respectively.

[0031] The slurry sprayed by the spray layer 12 contacts with the flue gas, absorbs SO2 and reacts chemically with SO2, and the pH of the slurry decreases step by step. The high pH slurry sprayed by the upper spray layer is superimposed with the low pH slurry sprayed by the lower spray layer, and the pH of the slurry is 5.2-5.7. It falls above the tray 14 to form a liquid holding layer of a certain height (the tray 14 is a tray with a pH of 5.2-2.7). After the liquid holding layer absorbs the flue gas SO2, the slurry falls into the absorption tower slurry pool, and the slurry pH decreases to 4.5-5.5 (the absorption tower slurry pool is a slurry pool with a pH of 4.5-5.5).

[0032] The pH of the spray slurry in the spray layer 12 is 5.4-6.4, which is conducive to absorbing flue gas SO2 and improving desulfurization efficiency. The pH of the slurry in the absorption tower slurry pool is 4.5-5.5, which is conducive to the dissolution of limestone, the oxidation of desulfurization by-products and the crystallization of gypsum.

[0033] Example 2

[0034] refer to Figure 1 As shown, a wet flue gas desulfurization absorption tower spray slurry pH cascade adjustment system, the spray layer 12 of this embodiment is composed of 5 spray layers, namely the first spray layer 12-1, the second spray layer 12-2, the third spray layer 12-3, the fourth spray layer 12-4 and the fifth spray layer 12-5. Others are the same as in Example 1.

[0035] The inlet pipe 21 is connected to the absorption tower slurry pool 11, the limestone slurry pipe 3 is connected to the inlet pipe 21, and the limestone slurry pipe 3 is provided with a limestone slurry valve 5. The outlet pipe 22 is connected to the corresponding spray layer 12, and the pH meter 4 is provided on the circulation pump outlet pipe 22.

[0036] The limestone slurry valve 5 is adjusted to change the amount of limestone slurry added to the inlet pipe 21 so that the pH meter 4 on the outlet pipe 22 displays a value of 5.4-6.2, and the pH increases step by step, that is, the pH of the spray slurry in the first spray layer 12-1 is 5.4, the pH of the spray slurry in the second spray layer 12-2 is 5.6, the pH of the spray slurry in the third spray layer 12-3 is 5.8, the pH of the spray slurry in the fourth spray layer 12-4 is 6.0, and the pH of the spray slurry in the fifth spray layer 12-5 is 6.2.

[0037] The fifth spray layer sprays slurry droplets with a pH of 6.2. After spraying downward through the fifth, fourth, third, second, and first spray layers to absorb flue gas SO2, the pH of the slurry droplets decreases step by step to 6.1, 6.0, 5.9, 5.8, and 5.7; the fourth spray layer sprays slurry droplets with a pH of 6.0. After spraying downward through the fourth, third, second, and first spray layers to absorb flue gas SO2, the pH of the slurry droplets decreases step by step to 5.9, 5.8, 5.7, and 5.6; the third spray layer sprays slurry droplets with a pH of 5.8. After spraying downward through the third, second, and first spray layers to absorb flue gas SO2, the pH of the slurry droplets decreases step by step to After the first spray layer absorbs flue gas SO2, the pH value of the slurry droplets decreases step by step to 5.6, 5.4, and 5.2; the second spray layer sprays slurry droplets with a pH value of 5.6, and after spraying downward through the second and first spray layers to absorb flue gas SO2, the pH value of the slurry droplets decreases step by step to 5.4 and 5.2; the first spray layer sprays slurry droplets with a pH value of 5.4, and after spraying downward through the first spray layer to absorb flue gas SO2, the pH value of the slurry droplets decreases to 5.2; these slurry droplets with different pH values ​​converge on the tray 14 to form a liquid holding layer with a pH value of 5.2-5.7.

[0038] The holding layer slurry with a pH of 5.2-5.7 contacts the flue gas passing through the tray perforated plate. After absorbing SO2, the slurry pH drops to 4.5-5.5 and falls into the absorption tower slurry pool 11 to facilitate the dissolution of limestone and the oxidation and crystallization of desulfurization by-products.

[0039] The above basic examples and further optional examples of the utility model can be freely combined to form multiple embodiments, which are all embodiments that can be adopted and claimed for protection by the utility model. In the scheme of the utility model, each optional example can be arbitrarily combined with any other basic examples and optional examples.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A pH step adjustment system for spray slurry in a wet desulfurization absorption tower, comprising an absorption tower (1), characterized in that: The absorption tower (1) is provided with an absorption tower slurry pool (11), a tray (14) and a spray layer (12) for spraying slurry with a pH value increasing in steps from bottom to top. The spray layer (12) comprises at least a first spray layer (12-1), a second spray layer (12-2) and a third spray layer (12-3) which are arranged in sequence from bottom to top and spray slurry with a pH value increasing in steps.

2. The pH step adjustment system for spray slurry of wet desulfurization absorption tower according to claim 1 is characterized in that: The absorption tower (1) is provided with a flue gas inlet located between the absorption tower slurry pool (11) and the tray (14), and the absorption tower (1) is also provided with a demister (13) located above the spray layer (12).

3. The pH step adjustment system for spray slurry of wet desulfurization absorption tower according to claim 1 is characterized in that: The first spray layer (12-1) is a spray pipe for spraying slurry at pH 5.4±0.05, the second spray layer (12-2) is a spray pipe for spraying slurry at pH 5.6±0.05, and the third spray layer is a spray pipe for spraying slurry at pH 5.8±0.

05.

4. The pH step adjustment system for spray slurry of wet desulfurization absorption tower according to claim 1 or 3, characterized in that: The spraying layer (12) further comprises a fourth spraying layer (12-4) and a fifth spraying layer (12-5) which are arranged in sequence from bottom to top starting from the third spraying layer (12-3) and spray slurry with pH values ​​increasing in a stepwise manner.

5. The pH step adjustment system for spray slurry of wet desulfurization absorption tower according to claim 4 is characterized in that: The fourth spray layer (12-4) is a spray pipe for spraying slurry at a pH of 6.0±0.05, and the fifth spray layer (12-5) is a spray pipe for spraying slurry at a pH of 6.2±0.

05.

6. The pH step adjustment system for spray slurry of wet desulfurization absorption tower according to claim 4 is characterized in that: The spray layer (12) further comprises a sixth spray layer (12-6) which is arranged sequentially from bottom to top starting from the fifth spray layer (12-5) and sprays the slurry with a pH value in a step-by-step manner.

7. The pH step adjustment system for spray slurry of wet desulfurization absorption tower according to claim 6 is characterized in that: The sixth spray layer (12-6) is a spray pipe for spraying slurry at pH 6.4±0.

05.

8. The pH step adjustment system for spray slurry of wet desulfurization absorption tower according to claim 1 is characterized in that: Each spray layer is independently equipped with a slurry supply subsystem.

9. The pH step adjustment system for spray slurry of wet desulfurization absorption tower according to claim 8 is characterized in that: The slurry supply subsystem comprises an inlet pipe (21), an outlet pipe (22) and a slurry circulation pump (2); the absorption tower slurry pool (11) is connected to the inlet pipe (21); the inlet pipe (21) is connected to the slurry circulation pump (2); the slurry circulation pump (2) is connected to the outlet pipe (22); the outlet pipe (22) and the limestone slurry pipe (3) are connected to the inlet pipe (21).

10. The pH step adjustment system for spray slurry of wet desulfurization absorption tower according to claim 9, characterized in that: The limestone slurry pipeline (3) is provided with a limestone slurry valve (5), and the outlet pipeline (22) is provided with a pH meter (4).

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