Ammonium bisulfate ash-like premix preparation and its strength detection and evaluation method and application

Abstract

The application provides a method for preparing ammonium bisulfate ash-like premix and detecting and evaluating the strength of the ammonium bisulfate ash-like premix, and application, and comprises the following steps: ammonium bisulfate powder and fly ash are punched into tablets by using the auxiliary action of boric acid; the strength of the ammonium bisulfate ash is detected through tablet compression, and the change rule of the strength enhancement of the ammonium bisulfate ash is obtained accordingly; the method is simple to operate and facilitates the cleaning of the air preheater blockage, solves the problem that the fly ash cannot be formed into a tablet under low ammonium bisulfate content, can analyze and evaluate the strength increase influence rule of the ammonium bisulfate on the ash tablet, and provides a theoretical guidance for the cleaning of the ammonium bisulfate deposition ash of the air preheater.

Description

TECHNICAL FIELD

[0001] The application relates to an air preheater blockage cleaning technology field of a thermal power plant, in particular to an ammonium bisulfate ash sample premixing preparation method and strength detection and evaluation method and application. BACKGROUND

[0002] SCR flue gas denitrification technology is generally used in coal-fired units to reduce nitrogen oxide emissions, but the denitrification ammonia escape reacts with SO3 in the flue gas to generate ammonium bisulfate, which is deposited between the heat exchange elements in the low-temperature section of the air preheater, and the ash scale reduces the cleaning effect of the steam soot blower, causing serious blockage of the air preheater and increasing the power consumption of the fan.

[0003] Ammonium bisulfate enhances the strength of ash scale, but the degree of increase lacks quantitative analysis. Since the ammonium bisulfate blockage of the air preheater cannot be directly measured for its strength, laboratory manual configuration becomes a research direction. In the research of Yan Lu, “Interaction mechanism of denitrification associated ammonium bisulfate and fly ash and influence on air preheater blockage”, ammonium bisulfate powder is premixed with fly ash, heated and treated on an iron plate plane, and then the deposition ash sample is simulated. A blower is used for blowing, and the amount of ash sample remaining on the iron plate plane is used to judge the effect of ammonium bisulfate on ash scale. This method cannot directly show the influence law of ammonium bisulfate on the strengthening of ash scale, and can only show that ammonium bisulfate will make the ash sample into ash scale. Therefore, it cannot provide theoretical guidance for the cleaning of the ammonium bisulfate deposition ash scale of the air preheater. SUMMARY

[0004] In order to solve the above technical problems, the application provides an ammonium bisulfate ash sample premixing preparation method and strength detection and evaluation method and application, which is simple to operate and convenient for cleaning the blockage of the air preheater. Not only does it solve the problem that fly ash cannot be formed into ash scale under low ammonium bisulfate content, but it also analyzes and evaluates the influence law of ammonium bisulfate on the strengthening of ash scale, thereby providing theoretical guidance for the cleaning of the ammonium bisulfate deposition ash scale of the air preheater.

[0005] In order to achieve the above purpose, the technical scheme of the application is as follows:

[0006] An ammonium bisulfate ash sample premixing preparation method and strength detection and evaluation method, comprising the following steps:

[0007] The ammonium bisulfate powder and fly ash are punched into tablets with the aid of boric acid;

[0008] The strength of the ammonium bisulfate ash scale is detected by tablet compression, and the change law of the strength enhancement of the ash scale caused by ammonium bisulfate is obtained.

[0009] The application provides a method for preparing ammonium bisulfate ash-like premix and detecting and evaluating the strength of the ammonium bisulfate ash-like premix, and application, which is simple in operation, facilitates cleaning of air preheater blockage, solves the problem that low ammonium bisulfate content cannot be combined with fly ash to form a plate, and can analyze and evaluate the influence law of ammonium bisulfate on the strength increase of ash and dirt combination, thereby providing a theoretical guidance for cleaning of ammonium bisulfate deposition ash and dirt of the air preheater.

[0010] As a preferred technical solution, the following steps are included:

[0011] S1. Different masses of boric acid, fly ash and ammonium bisulfate powder are weighed and fully stirred and mixed to obtain uniformly stirred and mixed ammonium bisulfate ash-like premix;

[0012] S2. The uniformly stirred and mixed ammonium bisulfate ash-like premix is pressed into a tablet sample by punching;

[0013] S3. The tablet sample is heated to enable the ammonium bisulfate in the tablet sample to change from solid to liquid state and adhere;

[0014] S4. The heated tablet sample is cooled to room temperature, and the cooled tablet sample is placed under a compression equipment for pressure testing. After the sample is broken, the testing is completed, and the performance parameters of the compression equipment are read to obtain the compression strength of the tablet sample under different ammonium bisulfate contents;

[0015] S5. An orthogonal test scheme is designed for the boric acid content, ammonium bisulfate content and heating temperature of the tablet sample. Based on the blank sample, the tablet strength data of multiple samples are processed to obtain the influence law of ammonium bisulfate on the strength increase of ash and dirt combination.

[0016] As a preferred technical solution, the ammonium bisulfate powder in step S1 is sieved to 180-220 mesh.

[0017] As a preferred technical solution, the punching pressure in step S2 is 9-11 tons.

[0018] As a preferred technical solution, the tablet sample is heated to a temperature of 147-220 DEG C in step S3, and the tablet sample is heated for 2-3 hours.

[0019] As a preferred technical solution, the ammonium bisulfate powder is treated to be in a liquid state at a temperature of 147-220 DEG C in step S3.

[0020] As a preferred technical solution, the mass fraction of the boric acid is 30%.

[0021] As a preferred technical solution, the mass fraction of the ammonium bisulfate powder is 2%-7%.

[0022] The application provides a preparation method of an ammonium bisulfate ash sample and application of a strength detection and evaluation method thereof.

[0023] The application provides a preparation method of an ammonium bisulfate ash sample and a strength detection and evaluation method thereof, application thereof, simple operation, convenient for cleaning of air preheater blockage, solves the problem that low ammonium bisulfate content cannot be formed with fly ash, can analyze and evaluate the strength increase influence law of ammonium bisulfate on ash setting, and provides theoretical guidance for cleaning of air preheater ammonium bisulfate deposition ash. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 A tablet sample strength limit change graph is provided for the application.

[0025] Figure 2 A flowchart of the preparation method of the ammonium bisulfate ash sample and the strength detection and evaluation method thereof is provided for the application. DETAILED DESCRIPTION

[0026] The preferred embodiments of the application are described in detail below with reference to the accompanying drawings.

[0027] It can be understood that the application achieves the purpose of the application through some embodiments.

[0028] As shown in the drawings, Figure 2 The preparation method of the ammonium bisulfate ash sample and the strength detection and evaluation method thereof provided by the application include the following steps:

[0029] S1: Different masses of boric acid, fly ash and ammonium bisulfate powder (ammonium bisulfate powder screen mesh size is 180-220 mesh) are weighed and placed in dry and clean vessels, and are fully stirred and mixed to obtain uniformly stirred ammonium bisulfate ash;

[0030] S2: The uniformly stirred ammonium bisulfate ash is punched under the setting pressure of the tablet press (punching pressure is 9-11 tons) to press into a round cake-shaped tablet sample;

[0031] S3: The tablet sample is heated in an electric oven with a heating temperature setting of 147-220 DEG C for 4h to perform solid-liquid adhesion treatment of ammonium bisulfate (the treatment temperature of ammonium bisulfate in liquid state is between 147-220 DEG C);

[0032] S4: The heated tablet sample is naturally cooled to room temperature outside the oven, and the cooled sample is placed under a compression equipment for pressure testing. After the sample is broken, the testing is completed, and the performance parameters of the compression equipment are read to obtain the compression strength of the sample under different ammonium bisulfate contents;

[0033] S5 An orthogonal test scheme is designed for the factors of boric acid content, ammonium bisulfate content and heating temperature, the tabletting strength data of various samples are processed based on a blank sample, and the influence law of the strength increase of ammonium bisulfate ash fouling is obtained through evaluation and analysis.

[0034] By adding boric acid (H3BO3), the mechanical strength of the ammonium bisulfate ash sample is increased, and the tablet is pressed under the setting pressure of the tablet press (the setting pressure of the tablet press is preferably 10 tons); by reducing the content of boric acid, the minimum content data of boric acid when the tablet sample is formed (without large shedding, crack and other phenomena) is shown in Table 1.

[0035] Table 1: Content of boric acid and fly ash of different mass

[0036]

[0037] From Table 1, we can observe that the boric acid content of experimental tablet samples 1-4 is high, the highest is reduced from 44.44% to 33.33%, and there is no obvious change, and the tablet sample is relatively complete;

[0038] Experimental tablet samples 5-8 begin to appear edge shedding phenomenon, with the decrease of boric acid content, different degrees of tablet sample shedding appear, but the overall situation of the tablet sample is good;

[0039] Experimental samples 9-12 appear tablet sample splitting and large area shedding phenomenon, and tablet sample 12 has a serious shedding phenomenon;

[0040] Therefore, the boric acid content in the tablet sample between 25% and 30% should meet the subsequent experimental requirements.

[0041] The ammonium bisulfate ash sample provided by the application is prepared, an 8g ammonium bisulfate ash sample is prepared, different mass of boric acid, fly ash and ammonium bisulfate powder are weighed, the mass fraction of boric acid is 30% (2.4g), the content of ammonium bisulfate is divided into four groups, which are 0%, 2%, 3.3% and 6.7%, and the rest is fly ash; different mass of ammonium bisulfate content corresponding to the content of boric acid and fly ash is shown in Table 2.

[0042] Table 2: Content of boric acid and fly ash corresponding to different mass of ammonium bisulfate content

[0043] predetermined design group number data 1 2 3 4 total mass (g) 8 8 8 8 ash (g) 5.6 5.44 5.33 5.07 ABS (g) 0 0.16 0.27 0.53 boric acid (g) 2.4 2.4 2.4 2.4 ABS mass fraction 0 2％ 3.3％ 6.7％

[0044] The ammonium bisulfate ash sample premix preparation and strength detection evaluation method provided by the application comprises the following steps:

[0045] S1 the ammonium bisulfate ash sample prepared above is placed in a dry and clean container and mixed thoroughly to obtain a stirred and mixed ammonium bisulfate ash sample;

[0046] S2 the stirred and mixed ammonium bisulfate ash sample is pressed using a tablet press to obtain a round cake-shaped tablet sample;

[0047] S3 the electric oven is turned on and the heating temperature is set to 180 DEG C, and after the temperature reaches the set temperature, the tablet sample is placed in the electric oven for heating, and the heating time is 2h;

[0048] S4 after heating, the tablet sample is taken out of the electric oven and naturally cooled to room temperature, and the cooled tablet sample is placed under a compression testing device for compression and tension testing, and after the sample is broken, the testing is completed, and the performance parameters of the compression testing device (see Table 3 below) are read to obtain the compression strength of the tablet sample under different ammonium bisulfate contents.

[0049] Table 3 Performance parameters of the compression testing device

[0050] actual group number data 1 (reference sample) 2 3 4 total mass (g) before heating 8.112 8.058 7.989 7.934 ash (g) 5.598 5.430 5.331 5.073 ammonium bisulfate (g) 0 0.162 0.273 0.534 boric acid (g) 2.389 2.391 2.401 2.403 breaking limit N 30.25 31.50 49.50 59.15

[0051] From Table 3 and Figure 1 we observe that the compression and tension performance strength of the tablet sample increases with the increase of the ammonium bisulfate content, which proves that the ammonium bisulfate ash-induced scale hardening strength increases with the increase of the ammonium bisulfate content, but is not a linear correlation, and the ammonium bisulfate ash-induced scale strength enhancement change rule is obtained, which provides a theoretical guidance for the cleaning of the ammonium bisulfate deposition scale in the air preheater.

[0052] The application of the ammonium bisulfate ash sample premix preparation and strength detection and evaluation method provided by the application is used as a theoretical guidance in the cleaning of the ammonium bisulfate deposition scale in the air preheater according to any one of the ammonium bisulfate ash sample premix preparation and strength detection and evaluation method, and the ammonium bisulfate ash-induced scale strength enhancement change rule is obtained, which provides a theoretical guidance for the steam blowing of the ammonium bisulfate deposition scale in the air preheater.

[0053] The ammonium bisulfate ash sample premix preparation and strength detection and evaluation method and application provided by the application are simple to operate and convenient for cleaning the air preheater blockage, not only solve the problem that low ammonium bisulfate content cannot be formed with fly ash, but also can analyze and evaluate the ammonium bisulfate ash-induced scale strength increase influence rule, and provide a theoretical guidance for the cleaning of the ammonium bisulfate deposition scale in the air preheater.

[0054] It is to be understood that the present application is described by way of example only, and that modifications or alterations can be made to the features and embodiments described without departing from the spirit and scope of the application. In addition, modifications can be made to the features and embodiments described to adapt them to particular situations and materials without departing from the spirit and scope of the application. Accordingly, the present application is not limited to the specific embodiments described herein, but rather only by the claims which follow, all variations and equivalents which fall within the ranges of the claims being intended to be embraced herein.

Claims

1. A method for preparing ammonium bisulfate ash premix and evaluating its strength, characterized in that, Includes the following steps: S1 Weigh different masses of boric acid, fly ash and ammonium bisulfate powder and mix them thoroughly to obtain a uniformly mixed ammonium bisulfate ash sample. S2 The ammonium bisulfate ash sample, which is stirred and mixed evenly, is pressed into a tablet sample by stamping. S3 heats the tablet sample to achieve a solid-to-liquid adhesion process for ammonium bisulfate in the tablet sample; S4. Cool the heated tablet sample to room temperature, place the cooled tablet sample under the compression tester for pressure testing, and after the sample breaks, the test is completed. Read the performance parameters of the compression tester to obtain the compressive strength of the tablet sample with different ammonium bisulfate contents. S5 designed an orthogonal experimental scheme for the factors of boric acid content, ammonium bisulfate content and heating temperature of the tablet samples. Based on blank samples, the tablet strength data of various samples were processed and evaluated to obtain the influence law of ammonium bisulfate on the increase of the strength of the scale caking.

2. The method for preparing ammonium bisulfate ash premix and evaluating its strength according to claim 1, characterized in that, In step S1, the ammonium bisulfate powder is sieved to a mesh size of 180–220.

3. The method for preparing ammonium bisulfate ash premix and evaluating its strength according to claim 1, characterized in that, The stamping pressure in step S2 is 9 to 11 tons.

4. The method for preparing ammonium bisulfate ash premix and evaluating its strength according to claim 1, characterized in that, In step S3, the temperature of the tablet sample is heated to 147-220℃, and the heating time is 2-3 hours.

5. The method for preparing ammonium bisulfate ash premix and evaluating its strength according to claim 1, characterized in that, In step S3, the temperature at which the ammonium bisulfate powder is processed into a liquid state is 147–220°C.

6. The method for preparing ammonium bisulfate ash premix and evaluating its strength according to claim 1, characterized in that, The boric acid has a mass fraction of 30%.

7. The method for preparing ammonium bisulfate ash premix and evaluating its strength according to claim 1, characterized in that, The mass fraction of the ammonium bisulfate powder is 2% to 7%.

8. The application of a method for preparing ammonium bisulfate ash premix and evaluating its strength, wherein the method for preparing ammonium bisulfate ash premix and evaluating its strength according to any one of claims 1-7 is used as theoretical guidance in the cleaning of ammonium bisulfate deposits in air preheaters.

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