CN101327928A - A kind of calcium carbide production method - Google Patents

Abstract

A method for producing calcium carbide belongs to the field of calcium carbide production. The traditional calcium carbide production process adopts block raw materials and electric arc heating. The invention adopts powdery carbon-containing raw materials and powdery calcium-containing raw materials, supplies heat by burning part of the carbon-containing raw materials with oxygen-containing gas, and prepares calcium carbide under the condition of 1700-2300 DEG C. The carbon-containing raw material is coal or coke, and the calcium-containing raw material is calcium carbonate, calcium oxide, calcium hydroxide or carbide slag. The particle size of the carbon-containing raw material and the calcium-containing raw material is below 1mm, and the mass ratio is 0.5-3:1. The oxygen-containing gas used for combustion is oxygen, oxygen-enriched air or air. The method solves the problems of high energy consumption and high pollution in the production of calcium carbide, and has the characteristics of wide selection range of raw materials, high energy utilization rate, continuous operation, and large production capacity. The process is also coupled with the coking of carbon-containing raw materials and the calcination of calcium-containing raw materials. The by-product CO produced by calcium carbide and the combustion of auxiliary fuels are used to preheat the raw materials to 500-1500 ° C, further reducing the oxygen consumption of calcium carbide production and process energy consumption.

Description

A kind of calcium carbide production method

Technical field:

The present invention relates to a production method of calcium carbide, in particular to the combustion pre-combustion of powdery carbon-containing raw materials and powdery calcium-containing raw materials through partial combustion in an oxygen-containing atmosphere to directly produce calcium carbide, and use the calcium carbide to produce by-product CO and auxiliary fuel. Hot powdered ingredients.

Background technique:

Calcium carbide, commonly known as calcium carbide (CaC ₂ ), was known as the mother of organic synthesis before the middle of the last century. At present, it is mainly used to produce series products such as vinyl chloride, vinyl acetate and acrylic acid. For example, about 70% of PVC (polyvinyl chloride) production in my country comes from calcium carbide acetylene. In recent years, the high price of oil has stimulated the development of calcium carbide industry. The output of calcium carbide in my country has increased from 4.25 million tons in 2002 to 11.77 million tons in 2006.

The traditional calcium carbide production adopts the fixed bed-arc method, using the high temperature generated by the arc to heat the lump calcium oxide and lump coke in the fixed bed (also known as moving bed or electric furnace) to above 2000°C, and stay for a certain period of time to form a molten state. Calcium carbide. During the production process, the mixture of calcium oxide and coke is added from the upper end of the electric furnace, and the CO produced by the reaction of the two is discharged from the upper part of the furnace body through the gap of the block material, and the molten calcium carbide is discharged from the bottom of the furnace, and the finished product is obtained after cooling and crushing.

The arc method uses high-grade electric heating, which consumes a lot of energy. It is reported that the average power consumption of 1 ton of calcium carbide in my country is 3250kW h [Tang Weicheng, Energy Saving Technology, 1999, 17(1): 38], of which about 60% is used for raw material heating and reaction, and about 40% is produced by high-temperature calcium carbide furnace Gas (including CO) is vented and taken away [Zheng Guohan, progress in calcium carbide production technology, Modern Chemical Industry, 1985: 22-25]. In addition, the structure of the electric furnace is complex, it is difficult to scale up, and the electrode consumption is large, resulting in high input and operating costs.

According to reports, calcium carbide can also be prepared by the oxythermal method, that is, the combustion of coal, heavy oil or natural gas provides heat to replace electrodes for heating [Zheng Guohan, Progress in Calcium Calcium Production Technology, Modern Chemicals, 1985: 22-25]. Japan (Zhao 61-178412) and Germany have disclosed the shaft furnace full coke oxythermal method, but because the consumption of coke is doubled, the production cost is still higher than that of the arc method. In 2005, my country (CN1843907A) disclosed an oxy-fuel injection technology that uses relatively cheap fuels such as coal, natural gas, and heavy oil to assist heating. By adding fluorite and crushed iron, calcium carbide and ferrosilicon are simultaneously produced, and the The gas CO is used to produce coal gas. But up to now, oxygen thermal method has not been popularized and applied [Chemical Technology Economics, 1990, 1:20].

Obviously, the traditional electric arc method and oxythermal method both use fixed-bed reactors to produce calcium carbide, and only block raw materials (3-20cm) can be used to ensure the discharge of product CO gas and avoid "bed collapse" caused by poor airflow. However, the reaction surface of bulk raw materials is small, the reaction rate is slow, the residence time in the furnace is long, the production capacity is small, and the energy consumption per unit product is high. In addition, the loss of massive raw materials in the preparation of raw materials is very large, and generally more than 20% of the raw materials cannot be used due to too small crushed particles [Wei Zemin, Research on energy-saving technology in the calcium carbide industry, China Chlor-Alkali, 1998, 7: 31]. Therefore, the key reason for the "high investment, high energy consumption, and high pollution" of calcium carbide production is the use of block raw materials and arc heating, and the by-product gas CO is not properly utilized.

Invention content:

The present invention aims to solve the problem of "high input, high energy consumption, and high pollution" in the production of calcium carbide. Through a lot of research and creative work, the inventor has developed a calcium carbide with simple process, low energy consumption, wide source of raw materials and low cost. production method.

The method mixes powdery carbon-containing raw materials and powdery calcium-containing raw materials, and directly heats the mixture through partial combustion of the carbon-containing raw materials to produce calcium carbide.

The powdery raw materials are carbon-containing raw materials with a particle size of less than 1 mm and calcium-containing raw materials with a particle size of less than 1 mm, preferably with a particle size of less than 0.3 mm.

The mass ratio of the carbon-containing raw material to the calcium-containing raw material is 0.5-3:1; the preferred mass ratio is 0.7-2:1.

After mixing, heat is directly supplied by partial combustion of the carbon-containing raw material, the oxidant used in the partial combustion of the carbon-containing raw material is an oxygen-containing gas, and the molar ratio of _O in the oxygen-containing gas to C in the carbon-containing raw material is 0.1-0.6, Make the temperature of the mixture reach 1700-2300°C, preferably in the range of 1750-1950°C; react for 0.1-10 minutes to generate calcium carbide.

The carbon-containing raw material is coal, coke or a mixture of the two, and the calcium-containing raw material is one or a mixture of calcium carbonate, calcium oxide, calcium hydroxide or calcium carbide slag.

The oxygen-containing gas is oxygen, oxygen-enriched air or air, and the reaction temperature can be adjusted by adjusting the ratio of the oxygen-containing gas to the carbon-containing raw material.

After the powdery carbon-containing raw material and powdery calcium-containing raw material are mixed, they are preheated to 500-1500° C., and then the reaction temperature of the mixture reaches 1700-2300° C. through partial combustion of the carbon-containing raw material to generate calcium carbide.

The preheating fuel used in preheating is CO or auxiliary fuel produced by calcium carbide, and the oxidant used in preheating is oxygen or air. When the preheating fuel is CO produced from calcium carbide, the volume ratio of CO to air is 1:2.5-4.

Preheating can not only reduce the consumption of carbon-containing raw materials in the subsequent reaction, improve the purity of calcium carbide in the product, but also reduce the oxygen consumption of the reaction.

The fuel used for preheating includes calcium carbide production by-product CO and auxiliary fuel. The auxiliary fuel includes gaseous fuel and liquid fuel. CO is a by-product of calcium carbide production, and its evacuation will cause air pollution. Its chemical utilization involves deep desulfurization and transportation problems, and the cost is high. The invention uses CO as one of the preheating fuels, which not only prevents air pollution, but also effectively utilizes energy, killing two birds with one stone.

The present invention has the following advantages:

Compared with the traditional calcium carbide production method, the present invention adopts powdery raw materials, has wide source of raw materials, high utilization rate, fast reaction rate, low reaction temperature and large production capacity.

Partial combustion of carbon-containing raw materials is used for direct heating instead of electric arc heating. The reactor is simple, the cost is low, and the reaction energy consumption is low.

The by-product gas CO is used to preheat raw materials, so that coking, lime burning and raw material preheating are integrated, and the system saves energy.

Detailed ways:

Example 1

120 grams of CaO with a particle size of 0.63mm, 150 grams of coke with a particle size of 0.63mm and 66 liters of oxygen were sprayed into the reactor to make the raw material temperature reach 1750°C, react for 10 minutes and cool to normal temperature, and the solid product was taken out to obtain The amount of solid product is 192g, the calcium carbide content is 68%, and the gas generation is 237L/kg.

Example 2

Using 48 liters of calcium carbide to produce by-product gas CO and 120 liters of air combustion, preheat 120g of calcium oxide with a particle size of 0.13mm and 110g of coke with a particle size of 0.13mm to 1500°C, and then spray the preheated material with 60 liters of oxygen Put into the reactor, make the raw material temperature reach 1750 ℃, cool to normal temperature after reacting for 5 minutes, take out the solid product, the obtained solid product is 149g, the calcium carbide content is 78%, and the gas generation is 274L/kg.

Example 3

Spray 120g of normal-temperature calcium oxide with a particle size of 0.13mm, 125g of normal-temperature coke with a particle size of 0.13mm and 128 liters of oxygen into the reactor to make the temperature of the raw materials reach 1950°C, react for 2 minutes and cool to normal temperature, take out the solid product, and obtain a solid The product amount is 144g, the calcium carbide content is 88%, and the gas generation volume is 309L/kg.

Example 4

Spray 120g of calcium oxide with a particle size of 0.16mm, 190g of coke with a particle size of 0.16mm and 114 liters of oxygen into the reactor to make the temperature of the raw materials reach 1750°C, react for 7 minutes and then cool to normal temperature, take out the solid product, the amount of solid product obtained It is 189g, the calcium carbide content is 73%, and the gas generation is 254L/kg.

Example 5

Using 48 liters of calcium carbide to produce by-product gas CO and 120 liters of air to burn, preheat 215 grams of calcium carbonate with a particle size of 0.40 mm and 150 grams of coke with a particle size of 0.40 mm to 900 ° C, and then preheat the material with 36 Rising oxygen was sprayed into the reactor to make the temperature of the raw material reach 1750° C. After reacting for 10 minutes, it was cooled to normal temperature, and the solid product was taken out. The amount of the obtained solid product was 193 g, the calcium carbide content was 66%, and the gas generation volume was 232 L/kg.

Example 6

Using 48 liters of calcium carbide to produce by-product gas CO and 120 liters of air combustion, preheat 120g of calcium oxide with a particle size of 0.13mm and 145g of coal powder with a particle size of 0.13mm to 1300°C, and then preheat the material with 73 liters of oxygen Spray into the reactor to make the raw material temperature reach 1800°C, react for 5 minutes and cool to normal temperature, take out the solid product, the amount of the solid product obtained is 164g, the calcium carbide content is 71%, and the gas generation is 249L/kg.

Example 7

Using 5 liters of CH ₄ and 50 liters of air combustion, preheat 159g of calcium hydroxide with a particle size of 0.13mm and 140g of coke with a particle size of 0.13mm to 500°C, and then inject the preheated material and 116 liters of oxygen into the reactor , make the raw material temperature reach 1750 ℃, cool to normal temperature after reacting for 5 minutes, take out the solid product, the obtained solid product amount is 152g, the calcium carbide content is 77%, and the gas generation is 272L/kg.

Example 8

Combustion with 8 grams of diesel oil and 140 liters of air, preheat 188g of calcium carbide slag with a particle size of 0.13mm and 126g of coke with a particle size of 0.13mm to 900°C, and then inject the preheated material and 68 liters of oxygen into the reactor to make the raw materials The temperature reached 1750°C. After reacting for 5 minutes, it was cooled to normal temperature, and the solid product was taken out. The obtained solid product was 174g, the calcium carbide content was 68%, and the gas generation volume was 238L/kg.

Example 9

Spray 120g of calcium oxide with a particle size of 0.16mm, 340g of coal powder with a particle size of 0.16mm and 570 liters of air into the reactor to make the raw material temperature reach 1750°C, react for 7 minutes and cool to normal temperature, take out the solid product, and obtain the solid product The weight is 189g, the calcium carbide content is 73%, and the gas generation is 254L/kg.

Examples 1-9 use carbon-containing raw materials to prepare calcium carbide directly, and the preparation temperature is similar to the temperature of modern pulverized coal power boilers. Therefore, compared with the current technology for preparing calcium carbide by electrode heating, the process of coal → heat → electricity → heat is avoided. Energy loss in energy saving, saving more than 50% of energy consumption; Embodiment 1-11 uses powdery raw materials, compared with the current block raw materials, electrode heating preparation calcium carbide technology, improves the processing capacity of the reaction furnace, and can save energy by 10% .

Examples 2 and 5-8 preheat coal, calcium carbonate, calcium hydroxide, carbide slag and other raw materials through the production of calcium carbide as a by-product CO or air combustion of auxiliary fuels, avoiding the high energy consumption of raw materials prepared by coking and burning lime in the current technology process, and retain the sensible heat of coke and calcium oxide, and save energy by 10%.

Claims (10)

1. a calcium carbide production method is characterized in that: powdery is contained carbon feedstock and the mixing of powdery calcic raw material, by containing carbon feedstock partial combustion direct heating mixture, produce calcium carbide.

2. calcium carbide production method according to claim 1 is characterized in that: granularity is contained carbon feedstock and granularity less than the powdery of 1mm mix less than the powdery calcic raw material of 1mm, the mass ratio that contains carbon feedstock and calcic raw material is 0.5-3: 1; After the mixing, by containing carbon feedstock partial combustion direct heating, described to contain the oxygenant that the carbon feedstock partial combustion adopted be oxygen-containing gas, O in the oxygen-containing gas ₂With the mol ratio that contains C in the carbon feedstock be 0.1-0.6, make the temperature of mixture reach 1700-2300 ℃, reacted 0.1-10 minute, generate calcium carbide.

3. calcium carbide production method according to claim 1 is characterized in that: described powdery contains the temperature of reaction that the carbon feedstock partial combustion makes mixture system and reaches 1750-1950 ℃.

4. calcium carbide production method according to claim 1 is characterized in that: described powdery contains the granularity of carbon feedstock and powdery calcic raw material less than 0.3mm.

5. calcium carbide production method according to claim 1 is characterized in that: the described carbon feedstock that contains is coal, coke or the mixing of the two, and the calcic raw material is one or several mixing of lime carbonate, calcium oxide, calcium hydroxide or carbide slag.

6. calcium carbide production method according to claim 1 is characterized in that: the described mass ratio that contains carbon feedstock and calcic raw material is 0.7-2: 1.

7. calcium carbide production method according to claim 1 is characterized in that: described oxygen-containing gas is oxygen, oxygen-rich air or air.

8. calcium carbide production method according to claim 1 is characterized in that: described powdery is preheated to 500-1500 ℃ after containing carbon feedstock and the mixing of powdery calcic raw material.

9. calcium carbide production method according to claim 8 is characterized in that: pining for used pre-heating fuel in advance is calcium carbide process gas product C O or auxiliary fuel, and pining for used oxygenant in advance is oxygen or air.

10. calcium carbide production method according to claim 8 is characterized in that: when described pre-heating fuel was calcium carbide process gas product C O, the volume ratio of CO and air was 1: 2.5-4.