CN114920476A - Method for producing cement zero-carbon-emission from limestone - Google Patents

Abstract

The patent discloses a method for producing cement zero-emission carbon by limestone, limestone powder is decomposed in a suspension decomposition system, lime is discharged from the bottom of the system, and mixed gas of water vapor and carbon dioxide is discharged from the top of the system; electrolyzing the mixed gas to obtain fuel; and (3) carrying out ball milling and mixing on the lime, the correcting material, the siliceous material and the mineral stabilizer to obtain a cement raw material, and calcining the cement raw material to obtain the low-carbon portland cement. Compared with the prior art, the method has the advantages of simple operation and low cost, and realizes the carbon-free emission in the production of cement from limestone.

Description

Method for producing cement zero-carbon-emission from limestone

Technical Field

The invention relates to the field of carbon neutralization in building material industry, in particular to carbon resource utilization in limestone raw materials and cement fuel and power supply replacement for cement industry.

Background

The largest carbon dioxide emission in the building material industry is the cement industry, the cement industry is the third largest world energy consumption industry and occupies 7% of industrial energy consumption, and the cement industry is the second largest world carbon dioxide emission industry and occupies 7% of global carbon dioxide emission. In 2020, carbon emission of cement industry in China is about 13.2 hundred million tons (including power consumption), which accounts for 80% of the building material industry and 13.5% of the whole country. The main sources of carbon emissions from the cement industry are electricity consumption for production, fuel combustion and raw material carbonate decomposition. Calculated according to the relevant current national standard value, the carbon dioxide emission of each ton of cement is about 675 kilograms; wherein, the indirect emission of production power consumption accounts for about 11%, the direct emission of fuel combustion accounts for about 31%, the direct emission of raw material carbonate decomposition accounts for about 58% [ Qidong, Zhang Dai, Luoning ] building materials industry carbon neutralization [ J ]. Chinese building materials, 2021, (7): 92-97].

As a commodity gas with rich value and a chemical raw material, hydrogen can become an energy storage carrier for converting renewable energy sources. The water electrolysis technology is combined with the renewable energy power generation, redundant electric energy can be stored in hydrogen in a chemical energy mode, fluctuation of renewable energy is suppressed, the consumption level is improved, and energy sources are pushed to replace cleanly [ Zhao and Ying, Li Gen base, Sun and Tong Xiao, etc. ] key technology of hydrogen production by electrolysis under the goal of double carbon and application progress [ J ]. global energy Internet, 2021, 4 (5): 436-446]. The green hydrogen prepared by utilizing renewable energy can be directly applied to the building material industry to replace carbonaceous fuel, and an effective way is provided for realizing deep carbon emission reduction. In addition, water and carbon dioxide are jointly electrolyzed and reacted to be converted into methane and carbon monoxide, renewable energy sources are stored, the existing natural gas pipeline system can be used for conveying, and investment is reduced.

A preparation method of green petrochemical natural gas is characterized by comprising the following steps: the method comprises the following steps: a. preparing carbon dioxide: reacting limestone at high temperature to obtain carbon dioxide; b. preparing carbon monoxide: reducing the carbon dioxide to carbon monoxide; c. synthesizing natural gas: and (3) reacting the carbon monoxide with hydrogen under the action of a catalyst to obtain the catalyst. The temperature of the high temperature in the step a is 1100-1600 ℃. The temperature of reduction in the step b is 1000-1600 ℃, and the pressure during reduction is 4-9 MPa [ Yangxiangquan ], a preparation method of green petrochemical natural gas [ P ]. 201510017706.3, 2015.01.14 ]. Therefore, the patent obtains the natural gas in three steps, the reaction temperature is high, pressure equipment is adopted, and the process is complex.

A method for co-producing synthesis gas by carbonate hydrorefining for carbon dioxide emission reduction is characterized by comprising the following steps: the method comprises the following steps: utilizing renewable energy sources to drive the preparation of hydrogen; and (ii) carrying out co-heat treatment on the hydrogen obtained in the step (i) as a reduction reaction gas and metal carbonate to obtain metal oxide, and completing the hydrogenation of carbon dioxide in situ to prepare the synthesis gas. The metal carbonate is any one or more of calcium carbonate, magnesium carbonate, iron carbonate, barium carbonate, cadmium carbonate, zinc carbonate, lead carbonate or copper carbonate. The molar ratio of the amount of the carbonate to the amount of the hydrogen used in the step (ii) is 1/100-1/1. And (ii) the gas flow velocity of the reaction gas in the pyrolysis treatment process of the step (ii) is 1mL/min-1000mL/min, and the gas pressure is normal pressure to 10 MPa. The pyrolysis temperature of the pyrolysis treatment in the step (ii) is 100-1500 ℃, the heating rate is 1-100 ℃/min, and the reaction time is 1-1000 min [ Shao Ming Fei, Xun, Shehenfu ], a method for producing synthesis gas by hydrogenation refining carbonate for reducing carbon dioxide emission [ P ]. 202111018899.6, 2021.09.01 ]. In the patent embodiment, 10g of calcium carbonate is flatly laid in a tubular furnace, the pyrolysis temperature is set to be 800 ℃, the heating rate is 10 ℃/min, the reaction time is 60min, a calcium oxide product is obtained after roasting, and the ratio of H2 to CO in synthesis gas is 2: 1. By regulating the flow rate of the hydrogen gas, the ratio of H2 to CO in the obtained synthesis gas can be controlled to be in the range of (1:4) - (4: 1). This patent adopts calcium carbonate as the raw materials, and the reaction in flat tubular furnace, the product can not continuous production, and production efficiency is lower, and the heat of reaction product can not effectively be retrieved. The patent needs to produce hydrogen separately, and the process is complex. When the synthesis gas is separated from the solid metal oxide, a small amount of synthesis gas is adsorbed on the surface of the solid metal oxide, so that the removal process is increased, the cost is increased, and the environmental safety is easily influenced.

The method utilizes carbon in the limestone as a raw material to produce fuel and calcium as a raw material to co-produce cement, and can realize resource utilization of all components of the limestone. The used electricity of this patent is green electricity, has realized the zero carbon emission of production process.

Disclosure of Invention

Compared with the prior art, the method for producing the cement zero-rank carbon by the limestone has the characteristics of simple operation, low cost, easy application and obvious economic and social benefits.

A method for producing cement zero-rank carbon from limestone comprises the following steps:

decomposing limestone powder in a suspension decomposition system, discharging lime from the bottom of the system, and discharging a mixed gas of water vapor and carbon dioxide from the top of the system; electrolyzing the mixed gas to obtain fuel; carrying out ball milling and mixing on lime, a correcting material, a siliceous material and a mineral stabilizer to obtain a cement raw material, and calcining the cement raw material to obtain low-carbon portland cement; the suspension decomposition system is composed of a cyclone preheater, a decomposition furnace and a cooling cyclone cylinder which are vertically connected in series, and a cooling medium in the cooling cyclone cylinder is water; the heat source of the decomposing furnace is a hollow ceramic plate internally provided with a green electric heating element, the hollow ceramic plate is one of bauxite ceramic, kaolinite ceramic and anorthite ceramic, and the green electric heating element is one of iron-chromium-aluminum alloy wire, nickel-chromium wire, tungsten wire and molybdenum wire; the mixed gas electrolysis equipment is a solid oxide gas electrolysis cell.

The decomposition temperature in the decomposition furnace is 700-1000 ℃.

The electrolyte of the solid oxide gas electrolytic cell is one of zirconia-based electrolyte and ceria-based electrolyte.

The correcting material is one of steel slag, manganese slag and nickel-iron slag, and the adding amount of the correcting material is 5-25% of the mass of the limestone.

The siliceous material is one of mud powder, red mud and sludge, and the addition amount is 20-40% of the mass of limestone.

The mineral stabilizer is one of apatite, barite and boromagnesite, and the addition amount of the mineral stabilizer is 0.1-0.9% of the mass of the limestone.

The equipment used for calcining the cement raw material is a suspension preheater kiln, a heating device of the suspension preheater is a hollow ceramic plate internally provided with a green electric heating element, fuel used for calcining in the kiln is green hydrogen, and the calcining temperature is 1200-1350 ℃.

The green hydrogen is renewable energy source water electrolysis hydrogen production, and the hydrogen production device is a solid oxide water electrolysis cell.

The green electricity is electricity produced by solar energy, wind energy and water energy.

The low-carbon portland cement is formed by adding water and is cured by carbon dioxide.

Active micro powder and alkali activator are added into the lime to prepare clinker-free cement.

The water used for cooling medium in the cooling cyclone is obtained by condensing the flue gas discharged by a cement suspension preheater kiln system.

Compared with the prior art, the invention has the following advantages:

limestone is a common raw material for producing cement, the main chemical component of the limestone is calcium carbonate, limestone powder is suspended and decomposed to facilitate heat exchange and accelerate the diffusion of carbon dioxide gas, the decomposition efficiency of the limestone can be improved, the decomposition temperature is reduced by 100-200 ℃, and the production efficiency is improved.

The suspension decomposition system is composed of a cyclone preheater, a decomposing furnace and a cooling cyclone cylinder which are vertically connected in series, wherein the cyclone preheater, the decomposing furnace and the cooling cyclone cylinder are respectively arranged from top to bottom. The cyclone preheater is designed according to the principle of a preheater of an external decomposing kiln of a cement plant; the principle of the decomposing furnace is a columnar spouting turbulent bed which is formed by connecting 3-8 column units with necking in series, wherein the ratio of the inner diameter of each column unit to the inner diameter of each necking is 1.1:1-1.8:1, and the ratio of the inner height of each column unit to the inner diameter of each column unit is 1:1-4: 1; the cooling cyclone cylinder is designed according to the principle of the cyclone preheater; wherein, the number of stages of the cyclone preheater is 3-6 stages, and the number of stages of the cooling cyclone cylinder is 1-3 stages. Materials are added from the upper part of the cyclone preheater and discharged from the cooling cyclone cylinder at the lowest stage, so that the preheating, the reaction and the cooling of the materials are realized; water is atomized and sprayed from the lowest stage of cooling cyclone, and the mixed gas of the water vapor and the carbon dioxide is discharged from the highest stage of cyclone preheater; namely, the material and the gas reversely run to realize heat exchange and recover heat. In the suspension decomposition system, the material is in a suspension state and is fully contacted with gas, so that heat exchange is facilitated; the retention time of the materials in the suspension decomposition system is less than 20 seconds, and the reaction speed is high; the equipment realizes continuous production of products, improves production efficiency and reduces energy consumption.

Water is used as a cooling medium in the cooling cyclone cylinder, so that heat in lime which is a decomposition product of limestone can be recovered, water vapor can be provided for mixed gas, and the limestone decomposition and the mixed gas electrolytic coupling are realized. If air cooling is adopted, the processes of capturing and separating carbon dioxide from the flue gas are increased, and the production cost is increased. The water is atomized and sprayed on the hot lime powder, the water temperature and the spraying amount are controlled, the water resource waste caused by the hydration of the lime into calcium hydroxide is avoided, and the subsequent cement production efficiency can be prevented from being influenced. The atomized water absorbs heat and then is converted into water vapor, so that a gas phase is provided for the suspension decomposition system, and the material is suspended in the system. The water used for cooling the cooling medium in the cooling cyclone is obtained by condensing the flue gas discharged by a cement suspension preheater kiln system, so that the water is recycled, and the natural water resource is saved.

The solid oxide electrolytic cell has higher energy conversion efficiency, and the efficiency of hydrogen production by electrolysis in a laboratory is close to 100 percent. From the thermodynamic perspective, as the temperature rises, the theoretical decomposition voltage of water drops, the consumption of electric energy in the hydrogen production process is reduced, the consumption of heat energy is increased, and the energy conversion efficiency is increased. From the kinetic angle, the operation at high temperature effectively reduces the overpotential and the energy loss, and improves the energy utilization rate. The water vapor required by the solid oxide electrolytic cell is coupled with the suspension calcining system to recover lime heat, so that the energy utilization efficiency reaches the level of a laboratory.

The electrolyte of the solid oxide gas electrolytic cell is one of zirconia-based electrolyte and cerium oxide-based electrolyte, and the zirconia-based electrolyte is yttrium-stabilized zirconia-based electrolyte. One or two of bismuth oxide and copper oxide are doped in the electrolytes to be used as sintering aids, and the addition amount of the sintering aids is 0.5-10% of the mass of the electrolytes, so that the sintering temperature of the electrolytes is reduced by 100-200 ℃. One or two of neodymium oxide, gadolinium oxide, manganese oxide and titanium oxide are doped in the electrolytes to serve as impurity elements to improve the ion transport capability of the electrolytes, the doping amount of the impurity elements is 1 to 20 percent of the molar amount of zirconium or cerium of the electrolytes, and the ion transport capability of the electrolytes is improved by 50 to 100 percent after doping. Electrolyzing the mixed gas of the water vapor and the carbon dioxide to obtain fuel consisting of carbon monoxide, methane and residual water vapor, and after the fuel is cooled, carrying out gas-water separation to obtain high-quality fuel gas; the separated water can be used for lime cooling to realize recycling. The cathode catalyst of the solid oxide gas electrolytic cell is one or two of nickel, cobalt and iron, and the doping amount is 1-20% of the molar amount of the electrolyte zirconium or cerium. The cathode catalyst is beneficial to the generation of methane, the reaction efficiency is improved by 100-200%, and the generation of carbon deposition is avoided.

The electrolyte of the solid oxide water electrolytic cell is proton conduction type solid oxide and is a cubic perovskite BaCeO3-BaZrO3 system. One or two of yttria, gadolinia and ytterbia are doped in the electrolyte to be used as impurity elements to improve the proton transmission capability of the electrolyte, the doping amount of the impurity elements is 1-20% of the molar amount of zirconium in the electrolyte, and the ion transmission capability of the doped electrolyte is improved by 40-100%. The sintering aid is one of nickel oxide, copper oxide and zinc oxide, and the addition amount of the sintering aid is 0.5-10% of the mass of the electrolyte, so that the sintering temperature of the electrolyte is reduced by 50-150 ℃.

The correction material is one of steel slag, manganese slag and ferronickel slag, the steel slag is waste slag generated by a steel mill, the manganese slag is waste slag generated by an electrolytic manganese mill, and the ferronickel slag is waste slag generated by pyrometallurgy of laterite-nickel ore, the waste slag contains iron resources, the comprehensive utilization difficulty is high, and the patent can realize resource utilization. Iron can increase the liquid phase of cement mineral during sintering, reduce the viscosity of the liquid phase, facilitate the growth of clinker mineral and improve the performance of clinker.

The siliceous material is one of mud powder, red mud and silt, and the siliceous material is waste, so that the method is favorable for resource utilization. The mud powder is produced in the process of producing recycled aggregate and recycled micro powder by using construction waste, the red mud is waste residue produced in the process of producing alumina, and the sludge is waste residue produced in dredging of river channels or lakes.

The mineral stabilizer is one of apatite, barite and boromagnesite, can stabilize the high-temperature structure of dicalcium silicate, and is beneficial to improving the early strength of dicalcium silicate; the mineral stabilizer also generates a trace liquid phase at low temperature, so that tricalcium silicate is favorably formed, and the calcination temperature of clinker is reduced.

The suspension preheater kiln consists of preheater and rotary kiln, and has no decomposing furnace compared with available kiln. The limestone is decomposed in the suspension decomposition system, and compared with the method of directly decomposing the cement raw meal in the suspension decomposition system, only the limestone is decomposed in the suspension decomposition system, so that the heat load of the suspension decomposition system can be reduced, impurities caused by non-calcium components of the raw meal are avoided, and the purity of carbon dioxide is improved; the liquid phase of non-calcium components in the raw materials can be avoided, so that the decomposing furnace is skinned, and the continuous production is facilitated; and is also beneficial to the utilization of the waste heat in the kiln tail flue gas.

In the patent, different hollow ceramic plates and green electric heating elements are used to achieve the purpose of the invention. The bauxite ceramic, the kaolinite ceramic and the anorthite ceramic are respectively sintered ceramics taking bauxite, kaolinite and anorthite as raw materials, and have the characteristics of rich raw material sources and low production cost.

The calcination temperature of the cement raw material is 1200-1350 ℃, which is lower than 1450 ℃ of the traditional portland cement production, thus being beneficial to reducing the consumption of fuel and improving the production efficiency.

Carbon dioxide curing, namely carbonization curing, adopts gas of carbon dioxide, the concentration of which is 1 to 30 percent, the curing time is 1 to 7 days, and the curing temperature is 10 to 40 ℃. The carbon dioxide can promote the hydration reaction of clinker minerals, and is beneficial to improving the early strength of the artificial stone; part of clinker minerals react with carbon dioxide to obtain calcium carbonate, and carbon dioxide gas can be solidified, which is beneficial to reducing greenhouse gas emission.

The lime produced by the method is quenched by water, has high hydration activity, and is added with active micro powder and an alkali activator to prepare clinker-free cement; wherein the active micro powder is one of metakaolin, calcined clay, water granulated slag mineral powder and calcined coal gangue powder, and the addition amount is 10-50% of the mass of the limestone; the alkali activator is one of the mirabilite residue, the sodium sulfide residue and the flue gas dry desulphurization residue, and the addition amount is 1-10% of the mass of the limestone. The 28-day compressive strength of the clinker-free cement after molding and curing according to the national standard exceeds 35 MPa.

Detailed Description

The present invention will be described in further detail with reference to specific examples.

Decomposing limestone powder in a suspension decomposition system, discharging lime from the bottom of the system, and discharging mixed gas of water vapor and carbon dioxide from the top of the system; electrolyzing the mixed gas to obtain fuel; and (3) carrying out ball milling and mixing on the lime, the correcting material, the siliceous material and the mineral stabilizer to obtain a cement raw material, and calcining the cement raw material to obtain the low-carbon portland cement. Limestone decomposition temperature, electrolyte and electrolysis temperature of mixed gas electrolyzer, fuel composition, see table 1. The cement calcination method comprises the following steps of (1) preparing a correction material, a siliceous material and a mineral stabilizer, and controlling the calcination temperature of cement; the cement sample is added with water according to the national standard, molded, maintained for 1 day, and then demoulded, and the compressive strength is shown in table 2 at normal pressure and carbon dioxide concentration of 20 percent after carbonization and maintenance for 2 days.

TABLE 1

TABLE 2

The embodiments of the present invention can be carried out and achieved for the purpose of the invention, and the present invention is not limited to these embodiments.

Claims (12)

1. The method for producing cement zero-emission carbon by using limestone is characterized by sequentially comprising the following steps of: decomposing limestone powder in a suspension decomposition system, discharging lime from the bottom of the system, and discharging mixed gas of water vapor and carbon dioxide from the top of the system; electrolyzing the mixed gas to obtain fuel; carrying out ball milling and mixing on lime, a correcting material, a siliceous material and a mineral stabilizer to obtain a cement raw material, and calcining the cement raw material to obtain low-carbon portland cement; the suspension decomposition system is composed of a cyclone preheater, a decomposition furnace and a cooling cyclone cylinder which are vertically connected in series, and a cooling medium in the cooling cyclone cylinder is water; the heat source of the decomposing furnace is a hollow ceramic plate internally provided with a green electric heating element, the hollow ceramic plate is one of bauxite ceramic, kaolinite ceramic and anorthite ceramic, and the green electric heating element is one of iron-chromium-aluminum alloy wire, nickel-chromium wire, tungsten wire and molybdenum wire; the mixed gas electrolysis equipment is a solid oxide gas electrolysis cell.

2. The method for producing cement zero-rank carbon by limestone as claimed in claim 1, wherein the decomposition temperature in the decomposition furnace is 700-.

3. The method for producing cement zero-emission carbon from limestone as claimed in claim 1, wherein the electrolyte of the solid oxide gas electrolytic cell is one of zirconia-based electrolyte and ceria-based electrolyte.

4. The method for producing cement zero-carbon emission from limestone as claimed in claim 1, wherein the correcting material is one of steel slag, manganese slag and ferronickel slag, and the addition amount is 5-25% of the mass of the limestone.

5. The method for producing cement zero-carbon emission from limestone as claimed in claim 1, wherein the siliceous material is one of mud powder, red mud and sludge, and the addition amount is 20-40% of the limestone mass.

6. The method for producing cement zero-emission carbon from limestone as claimed in claim 1, wherein the mineral stabilizer is one of apatite, barite and boromagnesite, and is added in an amount of 0.1-0.9% of the mass of the limestone.

7. The method for producing cement zero-rank carbon from limestone as claimed in claim 1, wherein the equipment for calcining cement raw material is suspension preheater kiln, the heating device of the suspension preheater is hollow ceramic plate with green electric heating element inside, the fuel for calcining in kiln is green hydrogen, and the calcining temperature is 1200-1350 ℃.

8. The method for producing cement zero-carbon emission from limestone as claimed in claim 1, wherein the green hydrogen is renewable energy source water electrolysis hydrogen production, and the hydrogen production device is a solid oxide water electrolytic cell.

9. The method for producing cement zero-emission carbon from limestone as claimed in claim 1, wherein the green electricity is electricity produced by solar energy, wind energy or water energy.

10. The method for producing cement zero-emission carbon from limestone as claimed in claim 1, wherein the low-carbon portland cement is formed by adding water and is cured by carbon dioxide.

11. The method for producing cement zero-emission carbon from limestone as claimed in claim 1, wherein clinker-free cement is prepared by adding active micropowder and alkali activator into lime.

12. The method for producing cement zero-emission carbon from limestone as claimed in claim 1, wherein the water used for the cooling medium in the cooling cyclone is obtained by condensing the flue gas exhausted from the kiln system of the cement suspension preheater.