WO2015101361A1 - Method of producing nanoscale white carbon black by using furnace flue gas directly to carbonize water glass - Google Patents

Abstract

Provided in the present invention is a method of producing nanoscale white carbon black by using furnace flue gas directly to carbonize water glass. The method comprises the following steps: 1.) preparing a water glass solution; 2.) purifying flue gas; 3.) carbonizing: feeding the purified flue gas recovered in step 2.) into the sodium silicate solution obtained in step 1.) to allow an acidification-neutralization reaction to occur between the sodium silicate solution and the carbon dioxide in the flue gas; 4.) separating out silicon dioxide: filtering solid and liquid mixtures produced in step 3.) to separate therefrom silicon dioxide precipitates and the sodium carbonate solution; 5.) drying the white carbon black product; 6.) filtrate treating to yield superfine calcium carbonate: adding limewater to the sodium carbonate solution separated out in step 5.), and then separating, drying, and pulverizing to obtain a superfine calcium carbonate product. The white carbon black produced by said method has a large specific surface area, is low in energy consumption, and can greatly reduce the greenhouse gas emissions in the flue gas from biomass-fired power plants.

Description

Method for producing nano-scale white carbon black by using boiler flue gas direct carbonized water glass

The invention relates to a technology for utilizing boiler flue gas, in particular to a method for producing nano-scale white carbon black by directly carbonizing water glass using boiler flue gas.

At present, the production process of white carbon black is divided into two types: precipitation method and gas phase method. The fumed silica product is of high quality and its products are micro-nano grade and are used in many high-end products. However, the environment in which fumed silica is produced is very harsh and the pollution is serious. Due to the high price of fumed silica, precipitated silica is generally used. The precipitation method is obtained by reacting sulfuric acid or hydrochloric acid with water glass. Since the specific surface area of the white carbon black produced by the sulfuric acid method or the hydrochloric acid method is small, it is generally from 90 to 120 m ² /g. The production and use limitations are large, the market is in a low grade, the price is below 6,000 yuan / ton. Many domestic white carbon black manufacturers use this method, the output is relatively large, and some manufacturers may be eliminated in the next few years.

The technical problem to be solved by the present invention is to provide a method for producing nano-scale white carbon black by directly carbonizing water glass using boiler flue gas, and the white carbon black produced by the method has large specific surface area and low energy consumption, and can also make Greenhouse gas emissions from flue gases from biomass power plants are significantly reduced.

The technical solution adopted by the present invention to solve the above technical problems is:

A method for producing nano-scale white carbon black by using boiler flue gas direct carbonized water glass, which comprises the following steps:

1) preparing a water glass solution: dissolving the water glass in soft water;

2) Flue gas purification: using flue gas generated by boiler combustion as raw material, cooling flue gas, fine purification, blasting pressure, as raw material gas for preparing white carbon black;

The flue gas may be a coal-fired boiler, a combustion biomass boiler, or a natural gas-fired steam boiler;

3) carbonization: the purified flue gas recovered in step 2) is passed into the sodium silicate solution obtained in step 1) to acidify and neutralize the carbon dioxide in the sodium silicate solution and the flue gas. The gas pressure is 5886Pa, the reaction temperature is 85~95°C, the reaction time is 2.5~4.5h, and a solid-liquid mixture of silica precipitate and sodium carbonate solution is formed;

4) separating the silica: filtering the solid solution and the liquid mixture formed in the step 3) to separate the silica precipitate and the sodium carbonate solution;

5) drying of the white carbon black product: washing and drying the silica precipitate separated in step 4) to obtain a white carbon black product;

6) Preparation of ultrafine calcium carbonate by filtration treatment: Lime water is added to the sodium carbonate solution separated in step 5), and then separated, dried and pulverized to obtain a finished ultrafine calcium carbonate.

In the above solution, the mass percentage concentration of the water glass solution in the step 1) is 1 to 15%.

In the above solution, in the step 2), the flue gas is cooled to below 40 ° C, and then pressurized to a gauge pressure of 5886 Pa, and after precision filtration, the flue gas contains less than 5 mg/Nm ^{3 of} dust.

In the above scheme, the reaction temperature in the step 3) is preferably 90 ° C, and the reaction time is 2.5 h, so that the sodium silicate solution and the carbon dioxide in the flue gas are sufficiently acidified and neutralized to generate as much as possible. Silica precipitation and sodium carbonate solution lay the foundation for the preparation of white carbon black. The chemical reaction equation is as follows:

Na ₂ SiO ₃ +CO ₂ +nH ₂ O=Na ₂ CO ₃ +SiO ₂ ·nH ₂ O

The above-mentioned white carbon black prepared by the method of directly producing carbonized water glass using boiler flue gas to produce nano-scale white carbon black.

In the above embodiment, the silica has a particle diameter of 10 to 100 nm.

In the above embodiment, the silica has a specific surface area of 160 to 250 m ² /g.

The invention adopts carbonization (acidification) neutralization treatment of the flue gas, and the obtained white carbon black and ultrafine calcium carbonate have the advantages of:

First, the carbon dioxide in the flue gas is used as the acidification neutralization medium, and the carbon dioxide is taken to the flue gas of the power plant. The raw material cost is extremely low, the source is sufficient, and carbon dioxide is used instead of sulfuric acid or hydrochloric acid, and the strong acid is excluded from the process operation. A large number of interventions avoid many of the dangers and safety hazards of sulfuric acid or hydrochloric acid in transportation, storage and production, as well as environmental pollution. For example, a plant with an annual output of 30,000 tons of white carbon can save about 16,000 tons of sulfuric acid or hydrochloric acid per year.

Second, the rational use of a large amount of flue gas has greatly reduced the greenhouse gas carbon dioxide gas of the power plant, effectively reducing the emission of industrial waste gas, and turning the power plant into an environmentally friendly cleaning plant. For example, a plant with an annual output of 30,000 tons of white carbon black can reduce the emission of carbon dioxide gas by about 15,000 tons per year.

Third, this patent uses burning biomass boiler flue gas instead of sulfuric acid and hydrochloric acid carbonized water glass, the specific surface area of its product white carbon black is increased to 130-250m ² /g, primary particles reach nanometer level, can be used as rubber The reinforcing reinforcing agent can replace the use of some fumed silica, and the price of the product is increased to 1,200-16,000 yuan/ton. The production environment is friendly and no toxic substances are discharged. The production energy consumption is lower than that of the sulfuric acid or hydrochloric acid method, and the production cost is also low. Therefore, the use of flue gas carbonized water glass to produce precipitated silica has a relatively good development prospect.

4. This patent is further improved on the basis of the applicant's 2007-10-31 patent application "200710053717.2": the patent "200710053717.2" is to remove the carbon dioxide from the flue gas by the MEA method for the flue gas, and then use The MEA solution is heated by steam, and the carbon dioxide is analyzed and sent to the reaction kettle through pressurization; the patent uses the flue gas to be cooled and dedusted and directly sent to the reaction kettle for use. After this change, there are the following benefits:

1) 2 tons of steam per ton of white carbon black;

2) In the flue gas treatment, without investment in stainless steel, the investment will save 70%;

3) Due to the direct use of flue gas, the reaction of carbon dioxide in the flue gas with the sodium silicate solution can be made milder, the obtained white carbon black has better dispersibility, and the white carbon black has a finer particle size, so that the white carbon is made. The quality of black finished products is improved. The original white carbon black has a particle size of micron. Now, the direct carbonization of flue gas to form white carbon black can reach nanometer level, and the price of white carbon black finished products can be increased from less than 6,000 yuan/ton to 1,200-15,000 yuan. /Ton.

In summary, the waste of a biomass power plant can be processed into two industrial products: nano-silica can be used in various industries such as rubber, plastics, paint, toothpaste, catalyst, heat preservation and water quality. Ultra-fine calcium carbonate is also an indispensable basic chemical raw material for the national economy. Therefore, part of the carbon dioxide gas in the flue gas of the power plant can also be used reasonably, which not only makes the power plant take a big step to the zero-row target, but also greatly reduces the production cost and energy consumption of the product, and greatly increases the The profit of power plants has significant social and economic benefits.

FIG. 1 is a schematic diagram of a process flow for co-production of white carbon black and ultra-fine calcium carbonate by biomass gas power plant flue gas.

Figure 2 is a scanning electron micrograph of the finished silica.

detailed description

The present invention is further described in the following with reference to the accompanying drawings and embodiments.

Figure 1 shows the process of co-production of white carbon black and ultra-fine calcium carbonate using biomass power plant flue gas, which includes the following steps:

1) preparing a water glass solution: dissolving the water glass in soft water, the concentration of the water glass is 5-15% (mass percentage);

2) Flue gas purification: using flue gas from biomass power plant as raw material, firstly cool the flue gas to below 40 °C, then pressurize it to about 5886 Pa (gauge pressure), and after precision filtration, make the flue gas contain dust. Less than 5mg/Nm ³ ;

3) Sodium silicate: The flue gas recovered in the step 2) is passed to the sodium silicate solution obtained in the step 1), and can be carried out in a carbonization tower provided with a circulation heater externally, and the reaction temperature is set. The temperature is 85 ° C -95 ° C, the flue gas pressure is 5886 Pa (gauge pressure), the reaction time is 2.5-4.5 h, so that the sodium silicate solution or the sol and the carbon dioxide in the flue gas are fully acidified and neutralized to form two A solid-liquid mixture of silica precipitate and sodium carbonate solution.

4) Separation of silica: The solid-liquid mixture produced in the step 3) is filtered to separate the silica precipitate and the sodium carbonate solution.

5) Drying of white carbon black: The silica precipitate separated in step 4) is washed and dried to obtain a finished white carbon black. After testing, the quality requirements are in accordance with HG/T3061-1999 standard, and the specific surface area is 160~250m ² /g.

6) Filtration treatment by-product ultrafine calcium carbonate: The lime water is added to the sodium carbonate solution separated in the step 4), and then separated, dried and pulverized to obtain a superfine calcium carbonate product.

As can be seen from Fig. 2, the silica has a particle diameter of 10 to 100 nm.

Take a rice husk fuel biomass power plant as an example to illustrate its economic benefits:

The silica content of the rice hull ash determines the yield of the two finished products. For example, a biomass power plant with an annual power generation capacity of 1.2 MW can produce about 17.89 million tons of rice hull ash per year. If it contains 90% of silica, about 15,000 tons of white carbon black, the filter can be treated with ultrafine Calcium carbonate is about 6,000 tons; if it contains 60% of silica, about 1.0 million tons of white carbon black, and the filtrate treatment can obtain about 4,000 tons of ultrafine calcium carbonate. Of course, as a power plant, it is desirable that the rice husks are burned more fully, and the carbon content in the rice husk ash is as small as possible.

Due to the large specific surface area of white carbon black, its price is 1.2-1.5 million yuan / ton; the price of ultra-fine calcium carbonate is 3,000 yuan / ton. In this way, in addition to power generation revenue, this power plant can obtain an output value of 1.5-1.8 billion yuan per year, with a profit of about 30-60 million yuan.

It should be understood that those skilled in the art should understand that the invention may be modified or equivalently substituted without departing from the spirit and scope of the present invention, which should be included in the scope of the claims of the present invention. .

Claims (7)

1. A method for producing nano-scale white carbon black by using boiler flue gas direct carbonized water glass, characterized in that it comprises the following steps:

   1) preparing a water glass solution: dissolving the water glass in soft water;

   2) Flue gas purification: using flue gas generated by boiler combustion as raw material, cooling flue gas, fine purification, blasting pressure, as raw material gas for preparing white carbon black;

   3) carbonization: the purified flue gas recovered in step 2) is passed into the sodium silicate solution obtained in step 1) to acidify and neutralize the carbon dioxide in the sodium silicate solution and the flue gas. The gas pressure is 5886Pa, the reaction temperature is 85~95°C, the reaction time is 2.5~4.5h, and a solid-liquid mixture of silica precipitate and sodium carbonate solution is formed;

   4) separating the silica: filtering the solid solution and the liquid mixture formed in the step 3) to separate the silica precipitate and the sodium carbonate solution;

   5) drying of the white carbon black product: washing and drying the silica precipitate separated in step 4) to obtain a white carbon black product;

   6) Preparation of ultrafine calcium carbonate by filtration treatment: Lime water is added to the sodium carbonate solution separated in step 5), and then separated, dried and pulverized to obtain a finished ultrafine calcium carbonate.
2. The method according to claim 1, wherein the water glass solution in the step 1) has a mass percentage concentration of from 1 to 15%.
3. The method according to claim 1, wherein in the step 2), the flue gas is cooled to below 40 ° C, and then pressurized to a gauge pressure of 5886 Pa, which is subjected to precision filtration to make the flue gas contain dust. Less than 5mg/Nm ³ spare.
4. The method according to claim 1, wherein the reaction temperature in the step 3) is 90 ° C and the reaction time is 2.5 h.
5. The white carbon black prepared by the method for producing nano-scale silica using boiler flue gas carbonized water glass according to any one of claims 1 to 4.
6. The white carbon black according to claim 5, wherein the white carbon has a particle diameter of 10 to 100 nm.
7. The white carbon black according to claim 5, wherein the white carbon has a specific surface area of from 160 to 250 m ² /g.