阅读说明：本技术 一种利用煤中天然钾钠元素进行催化气化的方法 (Method for catalytic gasification by using natural potassium and sodium elements in coal ) 是由 叶莲祥 宋星星 李晓黎 王贵顺 胡元旭 孙逢玖 于 2020-05-22 设计创作，主要内容包括：本发明公开了一种利用煤中天然钾钠元素进行催化气化的方法,该方法是将富含钾钠的原煤与普通原料煤混配成混配煤,将混配煤输送至气化炉中在钾钠催化作用下进行气化反应,得到粗合成气,钾钠富集在渣中随渣排出。该方法利用天然富含钾钠的原煤的催化特性,在无需外加钾钠催化剂的条件下,达到在相对较低的气化温度下,提升混配煤碳转化率、降低原煤消耗、保护气化炉的目的。(The invention discloses a method for catalytic gasification by utilizing natural potassium and sodium elements in coal, which comprises the steps of mixing raw coal rich in potassium and sodium with common raw coal to form mixed coal, conveying the mixed coal to a gasification furnace to carry out gasification reaction under the catalysis of potassium and sodium to obtain crude synthesis gas, and discharging potassium and sodium enriched in slag along with slag. The method utilizes the catalytic characteristic of natural raw coal rich in potassium and sodium, and achieves the purposes of improving the carbon conversion rate of blended coal, reducing the consumption of raw coal and protecting a gasification furnace at a relatively low gasification temperature under the condition of not adding a potassium-sodium catalyst.)

1. A method for carrying out catalytic gasification by utilizing natural potassium and sodium elements in coal is characterized by comprising the following steps: mixing raw coal rich in potassium and sodium elements with common raw coal to form mixed coal, conveying the mixed coal to a gasification furnace to carry out gasification reaction under the catalysis of potassium and sodium to obtain crude synthesis gas, wherein potassium and sodium are enriched in slag and discharged along with the slag.

2. The method for catalytic gasification by using natural potassium and sodium elements in coal as claimed in claim 1, wherein: the total content of potassium and sodium in the raw coal rich in potassium and sodium is measured by the total mass content of potassium oxide and sodium oxide in ash content of the raw coal rich in potassium and sodium being 2.5-10.0%.

3.The method for catalytic gasification by using natural potassium and sodium elements in coal as claimed in claim 2, wherein: the ash content of the raw coal rich in potassium and sodium is 1.8-3.8 in terms of silicon-aluminum ratio, and the silicon-aluminum ratio is SiO₂And Al₂O₃The mass ratio of (a) to (b).

4. The method for catalytic gasification by using natural potassium and sodium elements in coal as claimed in any one of claims 1 to 3, wherein: the total content of potassium and sodium in the blended coal is measured by the total mass content of potassium oxide and sodium oxide in ash of the blended coal, namely 2.5-8.0%.

5. The method for catalytic gasification by using natural potassium and sodium elements in coal as claimed in any one of claims 1 to 3, wherein: the silicon-aluminum ratio in the ash component of the blending coal is 1.8-2.8, and the silicon-aluminum ratio is SiO₂And Al₂O₃The melting point of ash is 1200-1440 ℃.

6. The method for catalytic gasification by using natural potassium and sodium elements in coal as claimed in claim 1, wherein: the temperature of the gasification reaction is 1400-1700 ℃, the pressure is 2.5-5.0 MPa, and the conversion rate of carbon in the mixed coal is not lower than 98.0%.

7. The method for catalytic gasification by using natural potassium and sodium elements in coal as claimed in claim 1, wherein: CO and H of the raw synthesis gas₂The percentage of the total volume is more than 80%.

Technical Field

The invention relates to a catalytic coal gasification method, in particular to a catalytic coal gasification method by utilizing natural potassium and sodium elements in coal, belonging to the technical field of coal gasification.

Background

At present, the entrained flow bed pressure gasification process is a mainstream process for preparing crude synthesis gas from large-scale industrialized coal. The entrained flow bed pressurized gasification process adopts the reaction of raw coal and pure oxygen, the raw coal and the pure oxygen are simultaneously pressurized and enter an entrained flow bed gasification furnace to generate a non-catalytic gasification reaction, and the reaction temperature is between 1300 ℃ and 1700 ℃, so that crude synthesis gas taking carbon monoxide and hydrogen as main products is generated.

The coal gasification reaction is a non-catalytic reaction, and according to an Arrhenius equation and a gas chemical reaction kinetics theory, the coal gasification reaction speed is related to the reaction temperature, the reaction activation energy, the reaction pressure and the reactant concentration. The reaction activation energy is related to the reactivity (volatile matter) of the coal as fired, and when the volatile matter of the coal as fired is kept stable for a period of time, the influence of the volatile matter on the coal gasification reaction speed can be ignored. The reaction pressure is kept relatively stable in the gasification furnace, and the influence on the coal gasification reaction speed can be ignored. The concentration of the reactant is related to the gasification reaction load, and when the gasification furnace keeps a certain load to stably operate, the influence of the concentration of the reactant on the gasification reaction speed can be ignored. Therefore, the gasification reaction temperature has a large influence on the coal gasification reaction rate.

Practice proves that the reaction speed is generally increased to 2-4 times of the original speed every time the reaction temperature is increased by 10 ℃. In the temperature range of 1300-1700 ℃ of coal gasification reaction, the reduction or increase of the reaction temperature by 10 ℃ has obvious influence on the carbon conversion rate, and can particularly reflect the change of the carbon content in the slag. Generally, the carbon content in the slag decreases as the gasification reaction temperature increases.

The gasification reaction temperature of the prior entrained flow coal gasification process is very high, about 1300-1700 ℃, and the ash residue is not completely converted into CO and CO₂The mass content of the residual carbon is generally between 5 and 25 percent, and the total carbon conversion rate is lower than 98 percent. The coal catalytic gasification process can reduce the gasification reaction temperature, improve the carbon conversion rate and reduce the energy consumption.

However, higher gasification reaction temperatures have a detrimental effect on the life of refractory bricks, silicon carbide refractories, and waterwalls. Therefore, the entrained flow coal gasification industry is continuously researching how to reduce the activation energy of the coal gasification reaction by using a proper catalyst, so as to reduce the gasification reaction temperature, but ensure that the carbon conversion rate is not reduced. At present, the process for producing the crude synthesis gas by catalytic gasification of coal is still researched, and no report of industrial application exists.

A large amount of literature and research show that alkali metal elements such as potassium, sodium and the like have catalytic gasification effect on coal gasification reaction.

Currently, coal catalytic gasification technology is generally developed by using an additional catalyst, and the additional catalyst is loaded in raw coal according to a certain proportion, or a fluidized bed technology is used for simultaneously adding the catalyst and the raw coal for catalytic reaction. The method for adding the catalyst has high use cost and complex process, and the catalyst recovery or treatment technology has great difficulty or high cost.

Chinese patent CN110628465A introduces: the coal particles, the steam and the catalyst-loaded thermal active semicoke are subjected to catalytic gasification reaction in a fluidized bed gasification reactor to generate product gas rich in methane and solid particles, wherein the solid particles comprise active semicoke particles, fly ash, carbon residue particles and ash.

Chinese patent CN108927189A relates to coal gasification technology field, especially relates to a coal catalytic gasification catalyst recovery method, recovery system and coal catalytic gasification system, and this patent introduces and adopts sharp cold water to quench coal catalytic gasification lime-ash, utilizes waste heat in the coal catalytic gasification lime-ash, passes through sharp cold water is right coal catalytic gasification lime-ash carries out washing processing to add digestion agent in the slag-water mixture after quenching processing, it is right coal catalytic gasification lime-ash digests the processing, and the product after will digesting the processing carries out solid-liquid separation, obtains catalyst recycle liquid and residue.

Chinese patent CN109652152A introduces a device and method for preparing methane by catalytic gasification of coal, which solves the problems of low carbon conversion rate, low methane yield, high energy consumption and complex structure existing in the prior art, and the invention adopts a bubbling turbulent bed gasification furnace with diameter-variable upper and lower spaces, comprising the following steps: the raw coal and the catalyst are subjected to catalytic gasification reaction with a gasification agent in the lower layer spaceThe synthesis gas generated by gasification reaction is mixed with partial circulating synthesis gas and catalyst in upper space to further strengthen methanation reaction, so that the technical scheme of the synthesis gas rich in methane is generated, and ash slag, CO and H generated by the reaction of the whole system₂、CH₄The carbon and methane are all circularly returned to different positions of the gasification furnace, the overall carbon conversion rate and the methane yield of the system are enhanced, and the method can be applied to the field of coal-to-natural gas.

For the coal catalytic gasification process, the above technologies, whether catalyst loading or catalyst recovery, have the disadvantages of high catalyst addition cost, large difficulty in recovery, high energy consumption, new hazardous waste generation and the like.

Disclosure of Invention

In order to solve the defects of high catalyst adding cost and large catalyst recycling difficulty in the production of crude synthesis gas by a coal catalytic gasification process in the prior art, the invention aims to provide a method for catalytic gasification by using potassium and sodium elements in biological specific raw coal which is rich in natural potassium and sodium elements as catalytic active ingredients; the method is characterized in that specific raw coal containing more potassium and sodium elements and other raw coal are mixed or are independently fed into a gasification furnace for gasification, the potassium and sodium elements in the specific raw coal play a catalytic role, no catalyst is required to be additionally added, organic components in the coal are subjected to catalytic gasification reaction at a relatively low gasification temperature to generate crude synthesis gas, the potassium and sodium elements with the catalytic role and coal ash in the coal are subjected to slagging reaction and discharged from a slag system in the form of slag to be used as a building material, and no catalyst is required to be recycled or treated, so that the purposes of improving the carbon conversion rate of mixed coal, reducing the consumption of the raw coal and protecting the gasification furnace at the relatively low gasification temperature are achieved.

In order to achieve the technical purpose, the invention provides a method for carrying out catalytic gasification by utilizing natural potassium and sodium elements in coal.

The common raw material coal related by the invention is a conventional coal raw material in a gasification process in the prior art, the total content of potassium and sodium is generally lower than 2.5%, and is mainly in the range of 0.5-2%, and the catalytic gasification effect of potassium and sodium on coal is not obvious in the range.

As a preferable scheme, the total content of potassium and sodium in the raw coal rich in potassium and sodium is measured by the total mass content of potassium oxide and sodium oxide in ash content of the raw coal rich in potassium and sodium is 2.5-10.0%. The ash content of the raw coal rich in potassium and sodium is higher than 2.5% in total mass, and the raw coal shows better catalytic gasification activity, for example, when the ash content is lower than 2.5%, the catalytic activity is lower, and the carbon gasification conversion rate is lower.

Preferably, the ratio of silicon to aluminum in the ash content of the raw coal rich in potassium and sodium is 1.8-3.8, and the ratio of silicon to aluminum is SiO₂And Al₂O₃The mass ratio of (a) to (b).

As a preferable scheme, the total content of potassium and sodium in the blended coal is measured by the total mass content of potassium oxide and sodium oxide in ash of the blended coal is 2.5-8.0%. If the total mass content of potassium oxide and sodium oxide in the ash content of the blended coal is lower than 2.5%, the carbon conversion rate is low, the problem of dust deposition and scaling of a subsequent heat exchanger occurs, and the total mass content of potassium oxide and sodium oxide in the ash content is more than 8.0%, the problem of dust deposition and blocking of the subsequent heat exchanger can be caused. Therefore, in the preferable proportion range, better catalytic coal gasification effect can be obtained. Generally, in the gasification process, only raw coal rich in potassium and sodium can be adopted, or raw coal rich in potassium and sodium can be used together with other common raw coal, and the mass ratio of the other common raw coal is preferably not higher than 75%. The high carbon conversion efficiency of the gasification reaction can be ensured by controlling the total content of potassium and sodium in the mixed coal, and the ratio of the effective components synthesized in the mixed coal is high.

As a preferable scheme, the ratio of silicon to aluminum in the ash component of the blending coal is 1.8-2.8, and the ratio of silicon to aluminum is SiO₂And Al₂O₃The melting point of ash is 1200-1440 ℃. The proper silicon-aluminum ratio is controlled to be beneficial to slag formation of potassium-sodium catalytic activity in the blended coal.

As a preferable scheme, the temperature of the gasification reaction is 1400-1700 ℃, the pressure is 2.5-5.0 MPa, and the conversion rate of carbon in the mixed coal is not lower than 98.0%.

As a preferred embodiment, the CO and H of the raw synthesis gas₂The percentage of the total volume is more than 80%.

The gasification furnace adopted by the technical scheme of the invention is a pressurized entrained flow bed gasification furnace.

In a preferable mode, the limestone is added into the blended coal to reduce the ash fusion point and the reaction temperature of the gasification furnace, and the addition amount of the limestone is 0.5-3.5% of the blended coal generally.

According to the technical scheme, the raw coal rich in potassium and sodium and other common raw coal are mixed and then are fed into the entrained flow gasifier for catalytic gasification, potassium and sodium elements in the catalytic coal have a catalytic gasification effect and react to generate crude synthesis gas, the potassium and sodium elements are discharged out of the gasifier along with ash slag to serve as building materials, no extra catalyst is added, and no catalyst recovery and treatment process is needed.

Compared with the prior art, the technical scheme of the invention has the following beneficial technical effects:

1. the technical scheme of the invention utilizes the potassium-sodium element naturally loaded in the raw coal as the catalyst, directly uses the raw coal rich in potassium and sodium as the catalyst and raw materials without adding extra catalyst, directly forms slag after the catalytic gasification reaction is finished, and discharges the potassium and sodium enriched in a slag phase to be utilized as a building material without setting catalyst recovery and treatment processes, thereby simplifying the process steps.

2. The raw coal rich in potassium and sodium adopted by the technical scheme of the invention utilizes the raw coal as a potassium and sodium carrier, the potassium and sodium dispersibility is good, the catalysis of potassium and sodium elements can be better exerted, the crude synthesis gas generated by catalytic gasification of coal is high in content, and the carbon conversion rate is obviously improved;

3. according to the technical scheme, the mixed coal ash composition is changed by adjusting the mixing proportion of the raw coal rich in potassium and sodium and other common raw coals, so that the mixed raw coal meets the requirements of a coal gasification device, and the coal for coal gasification has a wider selection range.

Detailed Description

The invention is further illustrated by the following examples, but is not limited thereto.

Example 1

The ash compositions of the following coal species, such as 187#, 158#, 153#, 152#, 087#, 170#, 125#, 178# were analyzed using XRF fluorescence spectroscopy, see table 1;

TABLE 1 Potassium sodium content in fly ash

In the above table, 158# and 178# raw coal ash has high potassium and sodium contents, which meet the definition of "catalytic coal". Combining 2 catalytic coals in table 1 with 1 other raw coal to form a 187# +158# +178# (1:1:1) ternary blended coal formula, inputting viscosity-temperature characteristic model software to calculate that the proportion of limestone to be added is 1.5% according to coal quality analysis data of the 187# +158# +178# (1:1:1) ternary blended coal, mixing the limestone and the limestone, adding the limestone into an AP pulverized coal gasification furnace to perform gasification reaction, performing continuous 72-hour performance test, determining that the carbon conversion rate is 98.5%, the gasification reaction temperature is 1575 ℃, and the gasification reaction pressure is 4.0MPa g; the potassium and sodium content of the ternary coal and the gasification production data are shown in Table 2.

TABLE 2

(3) The potassium and sodium elements in the catalytic coal and other ash components are discharged from a slag system after slagging reaction and are used for producing cement.

(4) Under the action of "catalytic coal", the conversion rate of coal carbon is greater than 98%, and the gasification reaction temperature is 1575 ℃.

Example 2

(1) 2 kinds of other raw coal in the table 1 are combined to form a 170# +125# (1:2) binary mixed coal formula.

(2) Inputting viscosity-temperature characteristic model software to calculate that the proportion of limestone to be added is 1.5% according to coal quality analysis data of 170# +125# (1:2) binary blended coal, mixing the limestone and the limestone, adding the limestone into an AP pulverized coal gasification furnace to perform gasification reaction, performing continuous 72-hour performance test, and determining that the carbon conversion rate is 95.4%, the gasification reaction temperature is 1636 ℃ and the gasification reaction pressure is 4.0MPa g; the potassium and sodium content of the binary coal and the gasification production data are shown in table 2.

(3) Due to the lack of high potassium and sodium "catalytic coal" in this formulation, the coal to carbon conversion in actual operation was only 95.4%, lower than in example 1 and the gasification reaction temperature was 1636 ℃ higher than about 60 ℃ in example 1.

Example 3

(1) 2 kinds of other raw coal in the table 1 are combined to form a 170# +125# (1:1) binary blending coal formula.

(2) Inputting viscosity-temperature characteristic model software to calculate that the proportion of limestone to be added is 2.3% according to coal quality analysis data of the binary blended coal of No. 170 +125 (1:1), mixing the limestone and the limestone together, adding the mixture into an AP pulverized coal gasification furnace to perform gasification reaction, performing continuous 72-hour performance test, and determining that the carbon conversion rate is 95.0%, the gasification reaction temperature is 1676 ℃, and the gasification reaction pressure is 4.0MPa (g); the content of potassium and sodium in the binary coal is 1.58%, the content of a catalytic substance, namely potassium and sodium elements in the mixed coal is low, and the conversion rate is low.