Low-carbon fuel prepared from papermaking solid waste and preparation method of low-carbon fuel

Abstract

The invention provides low-carbon fuel prepared from papermaking solid waste and a preparation method of the low-carbon fuel, and belongs to the technical field of low-carbon fuel. According to the invention, the papermaking waste residue and the sludge with different components are mixed, and the mixing ratio is optimized, so that the low-carbon material with high combustion efficiency is prepared, the combustion efficiency is improved, the low-carbon material has the characteristics of slagging resistance and corrosion resistance, the treatment efficiency of the papermaking solid waste material is improved, and the treatment cost is reduced. The content of calcium oxide in SB in the mixed fuel is relatively high, and the mixed fuel has a relatively strong sulfur fixation effect; iron oxide in SC has high catalytic activity. PW and SA have high calorific values, and the content of S and Cl in PW is low. The fuel has higher combustion potential. According to the method, other industrial waste or fossil fuel does not need to be added, the same solid waste is incinerated cooperatively, the combustion efficiency can be improved, and the resource utilization rate of the solid waste is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of low-carbon fuels, and in particular to a low-carbon fuel prepared from papermaking solid waste and a preparation method thereof. Background Art

[0002] With the rapid development of my country's papermaking industry, papermaking sludge refers to biomass solid waste generated during the treatment of papermaking wastewater. It contains a variety of toxic and harmful chemicals such as viruses, bacteria and parasites. At present, the disposal processes for sludge include: landfill dumping, biodegradation (land use), making building materials, incineration, etc. Compared with other methods, incineration has the advantages of reduction, harmlessness and resource utilization. However, the high water content, high ash content, low calorific value and low energy density of papermaking sludge are important factors restricting its efficient utilization. Therefore, papermaking sludge is usually mixed with other high calorific value fuels (wood chips, coal and industrial solid waste, etc.), but these solid wastes are complex in composition, and random mixing will lead to unstable boiler operation. At the same time, the purchase of other high calorific value fuels will increase transportation and storage costs. Papermaking waste residue is the residual material generated during the screening process of papermaking raw materials. Papermaking waste residue and papermaking sludge are both general industrial solid wastes. According to incomplete statistics, the amount of papermaking waste residue generated by recycled paper production nationwide is 18 to 22 million t / a, its main components are waste plastics, textiles, ropes, pulp, metals, stones and other waste residues; the output of papermaking sludge is about 20 million t / a, its main components are insoluble cellulose, fillers, flocculants and other pollutants.

[0003] The annual output of papermaking waste residue and papermaking sludge is large. Scientifically treating papermaking waste residue and papermaking sludge to avoid environmental pollution and bring economic benefits is a difficult problem faced by papermaking enterprises. Papermaking waste residue and papermaking sludge have a certain calorific value. Using circulating fluidized bed boilers to burn production capacity is one of the feasible ways to achieve harmless, reduced and resource utilization.

[0004] There are many problems with the existing incineration of papermaking solid waste, such as the large differences in the properties and calorific values ​​of papermaking waste residue and papermaking sludge. Therefore, boilers still have problems such as low combustion efficiency, slagging and scaling, which makes the coordinated treatment of papermaking solid waste difficult, equipment loss large, and operation and maintenance costs high. In general, most paper mills will mix various types of papermaking sludge together for treatment, and send them to incineration plants for combustion after concentration and drying. In addition, the current research on the combustion of papermaking sludge is also mainly based on mixed papermaking sludge, but the characteristics of papermaking sludge produced by different raw materials are different, and the impact on combustion and subsequent pollution control emissions are different.

[0005] The current technical problem to be solved is to prepare a fuel with high combustion efficiency and reduced slagging problem according to the combustion characteristics of different papermaking solid wastes. Summary of the invention

[0006] In view of this, the present invention provides a low-carbon fuel prepared from papermaking solid waste, which improves combustion efficiency and has anti-slagging and anti-corrosion properties, thereby improving the treatment efficiency of papermaking solid waste materials and reducing treatment costs.

[0007] The low-carbon fuel prepared from papermaking solid waste of the present invention comprises the following raw materials in parts by weight:

[0008] 65-75 parts of papermaking waste (PW), 3-5 parts of biochemical sludge A (SA), 20-25 parts of biochemical sludge B (SB), and 1-1.5 parts of Fenton sludge (SC).

[0009] Preferably, the papermaking waste residue comprises polyolefin and corrugated paper residue in a mass ratio of 1:1.

[0010] Preferably, the sludge ash of the biochemical sludge A includes the following compounds in weight percentage: K2O 1-2%, CaO 9-11%, Na2O 2-3%, MgO 1-2%, Al2O3 5-6%, Fe2O 9-10%, SiO2 38-40%, and the remainder is inevitable impurities.

[0011] Preferably, the sludge ash of the biochemical sludge B includes the following compounds in weight percentage: K2O 0-0.5%, CaO 45-50%, Na2O 1-2%, MgO 0-0.5%, Al2O3 4-5%, Fe2O 4-5%, SiO2 10-15%, and the remainder is inevitable impurities.

[0012] Preferably, the sludge ash of the Fenton sludge includes the following compounds in weight percentage: K2O 0-0.5%, CaO 4-7%, Na2O 1-3%, MgO 0-1%, Al2O3 25-30%, Fe2O 60-65%, SiO2 15-20%, and the remainder is inevitable impurities.

[0013] Preferably, the lower calorific value of the papermaking waste is 18-22 MJ / KJ; the lower calorific value of the biochemical sludge A is 10-13 MJ / KJ; the lower calorific value of the biochemical sludge B is 3-5 MJ / KJ; and the lower calorific value of the Fenton sludge is 5-7 MJ / KJ.

[0014] Preferably, in the low-carbon fuel prepared from papermaking solid waste, the S content is 0.26-0.49wt.%; the Cl content is 0.211-0.233wt.%; and the content of K2O+Na2O in the ash is ≤3wt.%.

[0015] Another object of the present invention is to provide a method for preparing the low-carbon fuel prepared from papermaking solid waste, the steps of which are as follows:

[0016] (1) First, the papermaking waste residue is crushed to a particle size of less than 2 cm; then the biochemical sludge A, biochemical sludge B, and Fenton sludge are filtered to a moisture content of 40-60%, and then placed outdoors for air drying to a moisture content of 25-35%;

[0017] (2) The raw materials are put into a high-speed mixer according to the proportion, and mixed at 1500-2000 rpm for 6-8 minutes to obtain the low-carbon fuel prepared from papermaking solid waste.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention provides a low-carbon fuel prepared from papermaking solid waste. Papermaking waste residues and sludge of different components are mixed, and the mixing ratio is optimized to prepare a low-carbon material with high combustion efficiency. The calcium oxide content in SB in the mixed fuel is relatively high, and has a strong sulfur fixation effect; the iron oxide in SC has a strong catalytic activity. PW and SA have high calorific values, and the S and Cl contents in PW are relatively low. The fuel has a high combustion potential. The present invention does not require the addition of other industrial wastes or fossil fuels. The same type of solid waste can be incinerated in a coordinated manner to improve the combustion efficiency and the resource utilization rate of the solid waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The weight loss rate (DTG) curves of different raw materials in air at a heating rate of 20℃ / min;

[0021] Figure 2 It is the absorbance of sulfur dioxide when different fuels are burned. DETAILED DESCRIPTION

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

[0023] Example 1

[0024] A low-carbon fuel prepared from papermaking solid waste, comprising the following raw materials in parts by weight:

[0025] 72 parts of papermaking waste (PW), 4 parts of biochemical sludge A (SA), 23 parts of biochemical sludge B (SB), and 1 part of Fenton sludge (SC).

[0026] The method for preparing low-carbon fuel using papermaking solid waste comprises the following steps:

[0027] (1) First, the papermaking waste residue is crushed to a particle size of less than 2 cm; then, the biochemical sludge A, biochemical sludge B, and Fenton sludge are filtered to a moisture content of 50%, and then placed outdoors for air drying to a moisture content of 30%;

[0028] (2) Add the raw materials into a high-speed mixer in proportion, add twice in total, and then mix them at 1500-2000 rpm for 8 minutes respectively to obtain the low-carbon fuel prepared from papermaking solid waste.

[0029] Among them, the main element composition and low calorific value of different raw materials are shown in Table 1:

[0030] Table 1

[0031]

[0032] The sludge ash composition is shown in Table 2:

[0033] Table 2

[0034]

[0035]

[0036] After mixing, the calorific value, acidic element S and halogen Cl, and ash composition of the fuel are shown in Table 3:

[0037] Table 3

[0038]

[0039] The following experiment was carried out on the low-carbon fuel (denoted as GA) prepared in Example 1.

[0040] Experiment 1

[0041] Using unmixed PW, SA, SB and SC as control examples, a laboratory-scale combustion experiment was conducted on the low-carbon fuel. A crucible containing 15±0.1 mg of the sample Al2O3 was heated from room temperature to 1000°C at a heating rate of 20°C / min in an air flow rate of 50 mL / min (N2 / O2=79% / 21%). A blank experiment was performed before the experiment to obtain a baseline. All experiments were performed 3 times to reduce experimental errors and achieve good reproducibility. The gas emission products produced by the combustion of the sample were determined by Fourier transform infrared spectroscopy (Nicoletis50, USA). The FTIR spectral resolution was better than 0.09 cm-1, and the scanning wavelength range was 4000-400 cm -1 .

[0042] The weight loss rate (DTG) curves of different raw materials in air at a heating rate of 20℃ / min are as follows: Figure 1 .from Figure 1It can be seen that the volatile release peak (about 300℃) of the main combustion stage of several papermaking solid wastes is the maximum weight loss peak, and the peak value is PW>SA>SB>SC; the weight loss rate in the main reaction stage is PW>SA>SC>SB, which is because PW and SA are rich in organic matter and lose weight faster. For GA, its maximum weight loss rate is greater than that of each single papermaking waste, which shows that the weight loss characteristics of the mixed fuel combustion after mixing are greater than those of each single papermaking waste, which improves the combustion efficiency.

[0043] Experiment 2

[0044] Record the combustion characteristics of different fuels, including: Ti ignition temperature, Tb burnout temperature, Tmax temperature corresponding to the maximum weight loss rate. DTGmax maximum weight loss rate, DTGmean, average weight loss rate, Di ignition index, Ci flammability index, S comprehensive combustion index, and obtain different combustion characteristic parameters as shown in Table 4:

[0045] Table 4

[0046] S PW SB SC GA <![CDATA[T i ]]> 257.5 268.7 238.4 231.4 239.1 <![CDATA[T b ]]> 645 673 804.3 818 667 <![CDATA[T max ]]> 291.6 324 295 303.6 305.2 <![CDATA[-DTG max ]]> 5.24 12.42 2.94 2.89 12.21 <![CDATA[-DTGmean·10 -3 ]]> 2.24 2.25 1.66 1.54 2.21 <![CDATA[D i ·10 -3 ]]> 1.39 2.85 0.83 0.82 3.45 <![CDATA[C i ·10 -5 ]]> 1.25 2.74 0.45 0.43 2.94 <![CDATA[S·10 -10 ]]> 2.75 5.77 1.07 1.02 8.38

[0047] The results in Table 4 show that T i The order of ignition temperature is PW>SA>GA>SB>SC. It can be seen that SB and SC have lower ignition temperatures, while PW and SA have higher ignition temperatures. The ignition temperature of GA after compatibility is lower than that of PW and SA, because the active metals in SB and SC have catalytic effects. The results of the combustion index S also show that the comprehensive combustion performance of GA is greater than that of each single papermaking waste.

[0048] Experiment 3

[0049] According to the method of Experiment 1, the absorbance of sulfur dioxide when different fuels are burned is tested. The results are as follows Figure 2 .

[0050] from Figure 2 It can be seen that the SO2 absorbance of PW and SA with lower sulfur content is greater than that of SB and SC with higher sulfur content. This is because SB and SC have higher ash content and are rich in various sulfur-fixing metals. The SO2 absorbance of GA is lower than that of PW and SA, which shows that the sulfur-fixing alkali metals in GA play a role in reducing the SO2 emission concentration. The SO2 absorbance of GA is not lower than that of SB and SC because the addition of SB and SC in GA cannot be too high to ensure the combustion performance of GA.

[0051] The low-carbon fuel prepared by the present invention can be directly used for incineration in a CFB fluidized bed boiler (800°C-950°C). Except for potassium and sodium (melting point 800-900°C), the melting points of other metal oxides are all greater than 1000°C. Based on the content of K2O and Na2O components, GA has good anti-slagging and corrosion properties.

[0052] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A low-carbon fuel prepared from papermaking solid waste, characterized in that: The invention comprises the following raw materials in parts by weight: 65-75 parts of papermaking waste, 3-5 parts of biochemical sludge A, 20-25 parts of biochemical sludge B, and 1-1.5 parts of Fenton sludge.

2. The low-carbon fuel prepared from papermaking solid waste according to claim 1, characterized in that: The papermaking waste residue comprises polyolefin and corrugated paper residue in a mass ratio of 1:

1.

3. The low-carbon fuel prepared from papermaking solid waste according to claim 1, characterized in that: The sludge ash of the biochemical sludge A includes the following compounds in weight percentage: K2O 1-2%, CaO 9-11%, Na2O 2-3%, MgO 1-2%, Al2O 35-6%, Fe2O 9-10%, SiO2 38-40%, and the remainder is inevitable impurities.

4. The low-carbon fuel prepared from papermaking solid waste according to claim 1, characterized in that: The sludge ash of the biochemical sludge B includes the following compounds in weight percentage: K2O 0-0.5%, CaO 45-50%, Na2O 1-2%, MgO 0-0.5%, Al2O 3 4-5%, Fe2O 4-5%, SiO2 10-15%, and the remainder is inevitable impurities.

5. The low-carbon fuel prepared from papermaking solid waste according to claim 1, characterized in that: The sludge ash of the Fenton sludge includes the following compounds in weight percentage: K2O 0-0.5%, CaO 4-7%, Na2O 1-3%, MgO 0-1%, Al2O3 25-30%, Fe2O 60-65%, SiO2 15-20%, and the remainder is inevitable impurities.

6. The low-carbon fuel prepared from papermaking solid waste according to claim 1, characterized in that: The low calorific value of the papermaking waste residue is 18-22 MJ / KJ; the low calorific value of the biochemical sludge A is 10-13 MJ / KJ; the low calorific value of the biochemical sludge B is 3-5 MJ / KJ; and the low calorific value of the Fenton sludge is 5-7 MJ / KJ.

7. The low-carbon fuel prepared from papermaking solid waste according to any one of claims 1 to 6, characterized in that: In the low-carbon fuel prepared from papermaking solid waste, the S content is 0.26-0.49wt.%, the Cl content is 0.211-0.233wt.%, and the K2O+Na2O content in the ash is ≤3wt.%.

8. The method for preparing low-carbon fuel using papermaking solid waste according to claim 1, characterized in that: Here are the steps: (1) First, the papermaking waste residue is crushed to a particle size of less than 2 cm; Then, the biochemical sludge A, biochemical sludge B and Fenton sludge are filtered to a moisture content of 40-60%, and then placed outdoors for air drying to a moisture content of 25-35%; (2) The raw materials are put into a high-speed mixer according to the proportion, and mixed at 1500-2000 rpm for 6-8 minutes to obtain the low-carbon fuel prepared from papermaking solid waste.

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