A calculation method and application of calcium-sulfur ratio in semi-dry desulfurization system

Abstract

The present disclosure relates to a calculation method and application of the calcium-sulfur ratio in a semi-dry desulfurization system. The method includes: calculating the calcium-sulfur ratio of the semi-dry desulfurization system using the calcium-sulfur ratio formula; the calcium-sulfur ratio formula is as shown in Equation 1: #imgabs0# where χ CaO渣 is the mass content of CaO in the desulfurized slag sample, in %; χ CaO灰 is the mass content of CaO in the fly ash sample, in %; χ CaSO3渣 is the mass content of CaSO3 in the desulfurized slag sample, in %; χ CaSO3灰 is the mass content of CaSO3 in the fly ash sample, in %; χ CaSO4渣 is the mass content of CaSO4 in the desulfurized slag sample, in %; χ CaSO4灰 is the mass content of CaSO4 in the fly ash sample, in %; α 灰 is the proportion of the fly ash amount to the desulfurized slag amount; the fly ash sample is the fly ash sample at the inlet of the desulfurization system. Through the calculation method of the present disclosure, the difficulty and cost of accurately analyzing Ca(OH)2 in the desulfurized slag sample are reduced, the accuracy of the calcium-sulfur ratio test in the semi-dry desulfurization system is improved, and the performance level of the desulfurization equipment is more truly reflected.

Description

Technical Field

[0001] The present disclosure relates to the technical field of performance detection of a semi-dry desulfurization system, and in particular to a calculation method and application of a calcium-sulfur ratio of a semi-dry desulfurization system. Background Art

[0002] As the country's requirements for environmental emissions continue to increase, new desulfurization devices are constantly being introduced. For newly built desulfurization equipment, desulfurization performance acceptance tests must be carried out to assess equipment performance; for operating desulfurization systems, performance tests must also be carried out regularly to detect equipment operating conditions. The calcium-sulfur ratio is an important parameter for the performance of the reactive desulfurization system and is a must-test item for desulfurization performance tests. Semi-dry desulfurization is a widely used desulfurization process. In thermal power plants, it is mostly arranged outside the furnace and combined with calcium spraying in the circulating fluidized bed boiler furnace for desulfurization.

[0003] The SO2 emission concentration is controlled by directly adding limestone powder in the circulating fluidized bed boiler furnace. The limestone put into the furnace is calcined at high temperature and decomposed into CaO, and then CaO, SO2 and oxygen react chemically to form CaSO4. When the boiler flue gas enters the semi-dry desulfurization device outside the furnace, the efficiency of the pre-pre-dust collector is mostly around 70% (even without a pre-electrostatic precipitator), resulting in a large amount of boiler fly ash in the circulating material of the semi-dry desulfurization device. The presence of fly ash increases the difficulty and cost of Ca(OH)2 detection in the desulfurization slag, and the presence of CaSO4 causes result deviation, which in turn leads to inaccurate calcium-sulfur ratio testing.

[0004] Therefore, it is necessary to study the calculation method that can accurately reflect the calcium-sulfur ratio. Summary of the invention

[0005] The purpose of the present invention is to provide a calculation method and application of the calcium-sulfur ratio of a semi-dry desulfurization system, so as to solve the problem that the calcium-sulfur ratio test method specified in the national standard is inaccurate due to the presence of a large amount of boiler fly ash in the circulating material of the semi-dry desulfurization device, which carries the calcium injection desulfurization product CaSO4 and the incompletely reacted desulfurizer CaO in the furnace.

[0006] In order to achieve the above object, the first aspect of the present disclosure provides a method for calculating the calcium-sulfur ratio of a semi-dry desulfurization system, the calculation method comprising: calculating the calcium-sulfur ratio of the semi-dry desulfurization system using a calcium-sulfur ratio formula;

[0007] The calcium-sulfur ratio formula is as follows:

[0008]

[0009] Among them, χ CaO渣 is the mass content of CaO in the desulfurization slag sample, in %; CaO灰 is the mass content of CaO in the fly ash sample, in %; CaSO3渣is the mass content of CaSO3 in the desulfurization slag sample, in %; CaSO3灰 is the mass content of CaSO3 in the fly ash sample, in %; CaSO4渣 is the mass content of CaSO4 in the desulfurization slag sample, in %; CaSO4灰 is the mass content of CaSO4 in the fly ash sample, in %; α 灰 M is the proportion of fly ash to desulfurization slag; CaSO4 is the molar mass of CaSO4, in g / mol; M CaO is the molar mass of CaO, in g / mol; M CaSO3 is the molar mass of CaSO3 in g / mol;

[0010] The fly ash sample is the fly ash sample at the inlet of the desulfurization system.

[0011] Optionally, the method further comprises calculating the proportion of the fly ash amount to the desulfurization slag amount using the formula shown in Formula 2: 灰 ,

[0012]

[0013] Where Q 灰 is the fly ash amount, in kg / h, Q 渣 It is the amount of desulfurization slag, in kg / h.

[0014] Optionally, the method further comprises calculating the fly ash amount Q using the formula shown in Formula 3 灰 ,

[0015] Q 灰 =Q 烟气 · χ 灰 10 -6

[0016] Formula 3,

[0017] Among them, Q 烟气 is the flue gas volume at the desulfurization system inlet, in m 3 / h; x 灰 is the dust concentration of the fly ash sample, in mg / m 3 ;

[0018] And, the desulfurization slag amount Q is calculated using the formula shown in Formula 4 渣 ,

[0019]

[0020] Said SO2 concentration in the flue gas at the desulfurization system inlet, in mg / m 3 .

[0021] Optionally, the calculation of the flue gas volume Q 烟气 Including measuring the flue gas volume Q at the inlet of the desulfurization system according to the national standard GB / T 21508-2008 烟气 .

[0022] Optionally, the method further comprises: calculating the smoke concentration χ of the fly ash sample 灰 Before the ash sample is dried and weighed, the smoke concentration χ of the ash sample is calculated according to the national standard GB / T 16157-1996. 灰 ; and measure the SO2 concentration in the flue gas at the inlet of the desulfurization system in accordance with the national standard GB / T 16157-1996

[0023] Optionally, the method further comprises collecting fly ash samples at the inlet of the desulfurization system in accordance with the national standard GB / T 16157-1996; the collection comprises collecting fly ash samples at a constant speed using a grid method at the inlet section of the desulfurization system, and analyzing the x CaO灰 , χ CaSO4灰 and χ CaSO3灰 quality content.

[0024] Optionally, the assay includes assaying the fly ash sample according to the national standard GB / T 5484-2012. CaO灰 , χ CaSO4灰 and χ CaSO3灰 quality content.

[0025] Optionally, the method further comprises collecting a desulfurization slag sample at the bottom of the bag filter or at the desulfurization ash recycling chute, and testing the desulfurization slag sample for x CaO渣 , χ CaSO4渣 and χ CaSO3渣 quality content.

[0026] Optionally, collecting the desulfurization slag sample at the outlet of the desulfurization system includes obtaining it by direct measurement method.

[0027] The second aspect of the present disclosure provides an application of evaluating the performance of a semi-dry desulfurization device using the calculation method described in the first aspect of the present disclosure.

[0028] Through the above technical scheme, the calculation method disclosed in the present invention calculates the calcium-sulfur ratio of the semi-dry desulfurization system by calculating the fly ash amount at the inlet of the desulfurization system, deducting the mass content of the corresponding substances in the fly ash sample from the mass content of CaO, CaSO4, and CaSO3 in the desulfurization slag sample according to the proportion of the fly ash amount to the desulfurization slag. The method disclosed in the present invention reduces the difficulty and cost of accurately testing Ca(OH)2 in the desulfurization slag, improves the accuracy of the calcium-sulfur ratio test of the semi-dry desulfurization system, and more realistically reflects the performance level of the desulfurization equipment.

[0029] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0031] Figure 1 It is a schematic flow chart of the desulfurization process in Example 1. DETAILED DESCRIPTION

[0032] The specific embodiments of the present disclosure are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure, and are not used to limit the present disclosure.

[0033] A first aspect of the present disclosure provides a method for calculating a calcium-sulfur ratio of a semi-dry desulfurization system, the method comprising: calculating the calcium-sulfur ratio of the semi-dry desulfurization system using a calcium-sulfur ratio formula;

[0034] The calcium-sulfur ratio formula is as follows:

[0035]

[0036] Among them, χ CaO渣 is the mass content of CaO in the desulfurization slag sample, in %; CaO灰 is the mass content of CaO in the fly ash sample, in %; CaSO3渣 is the mass content of CaSO3 in the desulfurization slag sample, in %; CaSO3灰 is the mass content of CaSO3 in the fly ash sample, in %; CaSO4渣 is the mass content of CaSO4 in the desulfurization slag sample, in %; CaSO4灰 is the mass content of CaSO4 in the fly ash sample, in %; α 灰 M is the proportion of fly ash to desulfurization slag; CaSO4 is the molar mass of CaSO4, 136, in g / mol; M CaO is the molar mass of CaO 56, in g / mol; M CaSO3 is the molar mass of CaSO3, 120, in g / mol;

[0037] The fly ash sample is the fly ash sample at the inlet of the desulfurization system.

[0038] The method disclosed in the present invention samples the fly ash at the inlet of the semi-dry desulfurization system, tests the mass contents of CaO, CaSO4 and CaSO3 therein, deducts the contents of the corresponding substances in the fly ash sample from the mass contents of CaO, CaSO4 and CaSO3 in the desulfurization slag sample according to the proportion of the fly ash amount to the desulfurization slag, and calculates the calcium-sulfur ratio of the semi-dry desulfurization system, thereby reducing the difficulty and cost of accurately testing Ca(OH)2 in the desulfurization slag, improving the accuracy of the calcium-sulfur ratio test of the semi-dry desulfurization system, and more realistically reflecting the performance level of the desulfurization equipment.

[0039] According to an embodiment of the present disclosure, the method further comprises calculating the proportion of the fly ash amount to the desulfurization slag amount using the formula shown in Formula 2: 灰 ,

[0040]

[0041] Where Q 灰 is the fly ash amount, in kg / h, Q 渣 The above implementation can improve the accuracy of the calcium-sulfur ratio test of the semi-dry desulfurization system.

[0042] According to an embodiment of the present disclosure, the method further comprises calculating the fly ash amount Q using the formula shown in Formula 3: 灰 ,

[0043] Q 灰 =Q 烟气 · χ 灰 10 -6

[0044] Formula 3,

[0045] Among them, Q 烟气 is the flue gas volume at the desulfurization system inlet, in m 3 / h; x 灰 is the dust concentration of the fly ash sample, in mg / m 3 ;

[0046] In a further embodiment, the desulfurization slag amount Q is calculated using the formula shown in Formula 4 渣 ,

[0047]

[0048] Said SO2 concentration in the flue gas at the desulfurization system inlet, in mg / m 3 The above implementation method measures the inlet fly ash concentration, flue gas volume, and calculates the fly ash volume, which can correct the calculation of the calcium-sulfur ratio in the existing national standard and improve the accuracy of the calcium-sulfur ratio test of the semi-dry desulfurization system.

[0049] According to an embodiment of the present disclosure, the calculation of the flue gas volume Q 烟气 Including measuring the flue gas volume Q at the inlet of the desulfurization system according to the national standard GB / T21508-2008 烟气 .

[0050] In a further embodiment, the method further comprises: in calculating the smoke concentration χ of the fly ash sample 灰 Before the ash sample is dried and weighed, the smoke concentration χ of the ash sample is calculated according to the national standard GB / T 16157-1996. 灰 ; and measure the SO2 concentration in the flue gas at the inlet of the desulfurization system according to the national standard GB / T 16157-1996 SO2 .

[0051] According to an embodiment of the present disclosure, the method further comprises collecting fly ash samples at the inlet of the desulfurization system in accordance with the national standard GB / T16157-1996; the collection comprises collecting fly ash samples at a constant speed using a grid method at the inlet section of the desulfurization system, and analyzing the fly ash samples for x CaO灰 , χ CaSO4灰 and χ CaSO3灰 quality content.

[0052] In a further embodiment, the assay comprises assaying the fly ash sample for x CaO灰 , χ CaSO4灰 and χ CaSO3灰 quality content.

[0053] According to an embodiment of the present disclosure, the method further comprises collecting a desulfurization slag sample at the bottom of the bag filter or at the desulfurization ash recycling chute, and testing the desulfurization slag sample for x CaO渣 , χ CaSO4渣 and χ CaSO3渣 In a further embodiment, the collecting of the desulfurization slag sample at the outlet of the desulfurization system comprises obtaining the sample by a direct measurement method, wherein the direct measurement method comprises measuring the sample using a weighing instrument.

[0054] The implementation method described above reduces the difficulty and cost of accurately testing Ca(OH)2 in desulfurization slag, improves the accuracy of calcium-sulfur ratio testing in a semi-dry desulfurization system, and more realistically reflects the performance level of the desulfurization equipment.

[0055] The second aspect of the present disclosure provides the application of the calculation method described in the first aspect of the present disclosure in evaluating the performance of a semi-dry desulfurization device.

[0056] The present disclosure is further described in detail below through examples. Unless otherwise specified, the raw materials used in the examples can be obtained through commercial channels.

[0057] Example 1

[0058] At the inlet section of the desulfurization system absorption tower, the fly ash sample was collected according to the national standard GB / T 16157-1996, and the fly ash sample was tested according to the national standard GB / T 5484-2012. CaO灰 , χ CaSO4灰 and χ CaSO3灰 The mass content of 6.07%, 4.39% and 0.14% respectively, and the inlet flue gas volume Q of the desulfurization system is measured in accordance with the national standard GB / T21508-2008 烟气 , which is 468048m 3 / h, the collected fly ash samples were dried and weighed, and the smoke concentration χ of the fly ash samples was calculated according to the national standard GB / T 16157-1996 灰 , is 5480mg / m 3 ; and measure the SO2 concentration in the flue gas at the inlet of the desulfurization system according to the national standard GB / T 16157-1996 SO2 , is 624mg / m 3 ; Collect desulfurization slag samples at the desulfurization ash recycling chute, and test the desulfurization slag samples according to the national standard GB / T 5484-2012 for x CaO渣 , χ CaSO4渣 and χ CaSO3渣 The mass contents are 16.2%, 22.27% and 3.71% respectively.

[0059] According to the fly ash amount Q 灰 , is 2565kg / h,

[0060] Q 灰 =Q 烟气 · χ 灰 10 -6

[0061] Formula 3;

[0062] The desulfurization slag amount Q is calculated using the formula shown in Formula 4 渣 , is 2784kg / h

[0063]

[0064] The ratio of the fly ash to the desulfurization slag is calculated using the formula shown in Formula 2. 灰 , is 0.92,

[0065]

[0066] The calcium-sulfur ratio S is calculated using formula 1 t The results are shown in Table 1.

[0067]

[0068] Among them, χ CaO渣 is the mass content of CaO in the desulfurization slag sample, in %; CaO灰 is the mass content of CaO in the fly ash sample, in %; CaSO3渣 is the mass content of CaSO3 in the desulfurization slag sample, in %; CaSO3灰 is the mass content of CaSO3 in the fly ash sample, in %; CaSO4渣 is the mass content of CaSO4 in the desulfurization slag sample, in %; CaSO4灰 is the mass content of CaSO4 in the fly ash sample, in %; α 灰 M is the proportion of fly ash to desulfurization slag; CaSO4 is the molar mass of CaSO4, 136, in g / mol; M CaO is the molar mass of CaO 56, in g / mol; M CaSO3 The molar mass of CaSO3 is 120, and the unit is g / mol.

[0069] Comparative Example 1

[0070] The calcium-sulfur ratio of the semi-dry desulfurization system was calculated with reference to the national standard GB / T 21508-2008. The desulfurization slag sample was collected at the bottom of the bag filter. The mass contents of CaSO4·2H2O, CaSO3·0.5H2O and Ca(OH)2 in the desulfurization slag sample were tested. The results were 28.17%, 3.99% and 7.00%, respectively. The calculation formula of the calcium-sulfur ratio is as follows: t See Table 1,

[0071]

[0072] Among them, χ Ca(OH)2 is the mass content of Ca(OH)2 in the desulfurization slag, in %; CaSO3·0.5H2O is the mass content of CaSO3·0.5H2O in the desulfurization slag, in %; CaSO4·2H2O is the mass content of CaSO4·2H2O in the desulfurization slag, in %; M CaSO4·2H2O The molar mass of CaSO4·2H2O is 172.18, in g / mol; M Ca(OH)2 The molar mass of Ca(OH)2 is 74.08, in g / mol; M CaSO3·0.5H2O The molar mass of CaSO3·0.5H2O is 129.15, and the unit is g / mol.

[0073] Table 1

[0074] Example 1 Comparative Example 1 <![CDATA[Calcium-sulfur ratio S t > 1.16 1.48

[0075] According to the results in Table 1, by comparing the embodiments and comparative examples, it can be known that the national standard GB / T21508-2008 does not take into account the calcium-sulfur ratio in the fly ash sample at the inlet of the desulfurization system when calculating the calcium-sulfur ratio. Therefore, the calcium-sulfur ratio calculated by the method of the present invention is smaller than the calcium-sulfur ratio calculated by the national standard GB / T 21508-2008. The method of the present invention deducts the mass content of the corresponding substances in the fly ash sample of the desulfurization system from the mass content of CaO, CaSO4 and CaSO3 in the desulfurization slag sample, thereby improving the accuracy of the calcium-sulfur ratio test of the semi-dry desulfurization system and more realistically reflecting the performance level of the desulfurization equipment.

[0076] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0077] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0078] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A method for calculating the calcium-sulfur ratio of a semi-dry desulfurization system, characterized in that: The calculation method includes: using a calcium-sulfur ratio formula to calculate the calcium-sulfur ratio of a semi-dry desulfurization system; The calcium-sulfur ratio formula is as follows: Among them, χ CaO渣 is the mass content of CaO in the desulfurization slag sample, in %; CaO灰 is the mass content of CaO in the fly ash sample, in %; CaSO3渣 is the mass content of CaSO3 in the desulfurization slag sample, in %; CaSO3灰 is the mass content of CaSO3 in the fly ash sample, in %; CaSO4渣 is the mass content of CaSO4 in the desulfurization slag sample, in %; CaSO4灰 is the mass content of CaSO4 in the fly ash sample, in %; α 灰 M is the proportion of fly ash to desulfurization slag; CaSO4 is the molar mass of CaSO4, in g / mol; M CaO is the molar mass of CaO, in g / mol; M CaSO3 is the molar mass of CaSO3, in g / mol; the fly ash sample is the fly ash sample at the inlet of the desulfurization system; The ratio of the fly ash to the desulfurization slag is calculated using the formula shown in Formula 2. 灰 , Where Q 灰 is the fly ash amount, in kg / h, Q 渣 is the amount of desulfurization slag, in kg / h; The fly ash amount Q is calculated using the formula shown in Formula 3 灰 , Q 灰 =Q 烟气 ·χ 灰 ·10 -6 Formula 3, Among them, Q 烟气 is the flue gas volume at the inlet of the desulfurization system, in m 3 / h; x 灰 is the dust concentration of the fly ash sample, in mg / m 3 ; And, the desulfurization slag amount Q is calculated using the formula shown in Formula 4 渣 , Said SO2 concentration in the flue gas at the desulfurization system inlet, in mg / m 3 .

2. The calculation method according to claim 1, wherein: The calculation of the flue gas volume Q 烟气 Including measuring the flue gas volume Q at the inlet of the desulfurization system according to the national standard GB / T 21508-2008 烟气 .

3. The calculation method according to claim 1, wherein: The method further comprises: calculating the smoke concentration χ of the fly ash sample 灰 Before the ash sample is dried and weighed, the smoke concentration χ of the ash sample is calculated according to the national standard GB / T 16157-1996. 灰 ; and measure the SO2 concentration in the flue gas at the inlet of the desulfurization system in accordance with the national standard GB / T 16157-1996 4. The calculation method according to claim 1, wherein: The method further comprises collecting fly ash samples at the inlet of the desulfurization system in accordance with the national standard GB / T 16157-1996; the collection comprises collecting fly ash samples at a constant speed by using a grid method at the inlet section of the desulfurization system, and testing the fly ash samples for x CaO灰 , χ CaSO4灰 and χ CaSO3灰 quality content.

5. The calculation method according to claim 4, wherein: The test includes testing the fly ash sample in accordance with the national standard GB / T 5484-2012. CaO灰 , χ CaSO4灰 and χ CaSO3灰 quality content.

6. The calculation method according to claim 1, wherein: The method also includes collecting a desulfurization slag sample at the bottom of the bag filter or at the desulfurization ash recycling chute, and testing the desulfurization slag sample for x CaO渣 , χ CaSO4渣 and χ CaSO3渣 quality content.

7. The calculation method according to claim 6, wherein: The collecting of desulfurization slag samples includes obtaining the samples by direct measurement method.

8. The performance of a semi-dry desulfurization device is evaluated by using the calculation method described in any one of claims 1 to 7.

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