Method for relieving ring formation of rotary kiln in sintering process of deoiled rock debris-based ceramsite

Abstract

The invention provides a method for relieving ring formation of a rotary kiln in a sintering process of deoiled rock debris-based ceramsite. The method specifically comprises the following steps: (1) uniformly mixing deoiled rock debris, ceramsite sintering rotary kiln fly ash (hereinafter referred to as fly ash) and Portland cement to obtain a mixed raw material; (2) feeding the mixed raw material into a double-roller granulator, and pressurizing and granulating to obtain a ceramsite raw material; (3) adjusting the particle morphology by a shaping screening machine, and aging; and (4) sieving the ceramsite raw material, and sintering in a rotary kiln to obtain the ceramsite. In order to solve the problem of ring formation of a rotary kiln in the ceramsite sintering process after shale gas drilling rock debris is deoiled, a'deoiled rock debris (main ceramic forming component)-fly ash (with volcanic ash activity)-Portland cement 'ceramsite ternary component system is constructed to replace a'deoiled rock debris-clay' binary component system to produce a ceramsite raw material with certain initial strength; the high dependence on clay resources in ceramsite production can be avoided, and the conditions of powder accumulation (caused by bursting of ceramsite raw materials in a low-temperature section in the rotary kiln) and rapid ring formation in the rotary kiln are effectively relieved.

Description

Technical Field

[0001] The invention relates to the field of solid waste resource utilization in natural gas resource exploitation, and in particular to a method for alleviating rotary kiln ringing in the process of preparing ceramsite from drilling cuttings. Background Art

[0002] The development and utilization of shale gas has led to the generation of a large amount of drilling cuttings, posing a great threat to the ecological environment. Oil-based cuttings contain harmful substances such as petroleum hydrocarbons, organic matter and heavy metals, and their content exceeds the standard limits of the "Hazardous Waste Identification Standard Toxic Substance Content Identification" (GB5085.6-2007) and the "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial)" (GB15618-2018), which poses a great threat to the environment and needs to be disposed of.

[0003] The main methods for drilling cuttings disposal at home and abroad include incineration, thermal desorption, extraction technology, centrifugal separation, microbial treatment and chemical cleaning. At present, thermal desorption has been widely promoted in Sichuan and Chongqing, but the deoiled cuttings still need further resource utilization. Many companies are trying to prepare sintered ceramsite based on the "deoiled cuttings-clay" binary component system. In the actual production process, in order to reduce the cost of raw materials and increase the amount of cuttings, the company controls the proportion of clay in the ceramsite raw material below 20%. As a result, during the sintering process of ceramsite, the ceramsite raw material is easy to break and produce powder, which softens and adheres to the wall of the rotary kiln under high temperature, causing the rotary kiln to form rings quickly.

[0004] At present, relevant research has been conducted in China on alleviating the problem of rotary kiln ringing. From the research on principle and ratio, it can be seen that patent CN118480699A can effectively alleviate the problem of rotary kiln ringing by controlling the silicon-magnesium ratio, forcibly increasing the temperature gradient in the temperature zone and adding special crystal seeds, but the patent has high energy consumption and operating costs for temperature regulation; patent CN118308153A uses oxidants, loosening agents, catalysts and activated carbon to prepare decoking agents, which effectively alleviates ringing, but the decoking agent targets the fume (FeO) and iron silicate in the ringed material, which is different from the ringed material in the "deoiled rock cuttings-clay" binary component system ceramsite sintering process. From the study of the sintering process of the rotary kiln, it can be known that the patent CN117968371A invented an expansion belt combined with a hydraulic hammer ring cleaning device to achieve non-manual removal of the ring layer, but it requires furnace shutdown for treatment, and the furnace restart process after shutdown consumes a lot of manpower and financial resources; the patent CN220737934U combines an automation system to realize automatic identification of rings and broken ring layers, and can achieve automatic removal of rings without stopping the furnace; the patents CN118272646A and CN212930936U use the waste heat of the ceramsite preparation device to preheat the ceramsite precursor or the combustion-supporting cold air to alleviate the ring, but the configuration and maintenance costs of such systems are high. The patent CN118326153A alleviates the ring by extending the agglomeration process through secondary ball formation, and the sintering process is complicated and the ring formation time is prolonged. The patent CN117606227A prevents the ring formation of the rotary kiln by controlling the particle size ratio and specific surface area of ​​the raw material and the moisture content of the raw ball, which is highly feasible and has a good effect of slowing down the ring formation.

[0005] In view of the problem of rotary kiln ringing during the sintering of expanded clay after deoiling of shale gas drilling cuttings, the present invention constructs a ternary component system of expanded clay of "deoiled cuttings-fly ash-Portland cement" to replace the binary component system of "deoiled cuttings-clay" to produce expanded clay raw material with a certain initial strength. The high dependence on clay resources in expanded clay production can be eliminated, and the difficulties of powder accumulation in the rotary kiln (caused by the explosion of the expanded clay raw material in the low temperature section of the rotary kiln) and rapid ringing can be effectively alleviated. In addition, the technical process is simple, low-cost, highly operational, and easy to apply in engineering. Summary of the invention

[0006] The present invention provides a method for alleviating the ringing of a rotary kiln during the sintering process of deoiled rock debris-based ceramsite. The specific content of the invention is as follows:

[0007] (1) taking deoiled rock cuttings, fly ash and ordinary Portland cement and mixing them evenly to obtain a mixed raw material;

[0008] (2) the mixed raw materials are fed into a double-roll granulator for pressure granulation to obtain ceramsite raw material;

[0009] (3) The ceramsite raw material is aged after adjusting the particle shape through a shaping and screening machine;

[0010] (4) Screening the ceramsite raw material and putting it into a rotary kiln for sintering to obtain ceramsite.

[0011] Beneficial effects of the present invention:

[0012] (1) Resource utilization and environmental protection: The present invention forms a mixed raw material by compounding deoiled rock cuttings, fly ash from a rotary kiln, and ordinary Portland cement. This replaces the non-renewable resource clay in the "deoiled rock cuttings-clay" binary component system, more efficiently utilizes industrial waste, reduces the environmental risk of rock cuttings storage, and is more in line with the trend of sustainable development and environmental friendliness.

[0013] (2) Process optimization: The steps involved in the invention, including the preparation of mixed raw materials, the use of a double-roll granulator to form ceramsite raw materials, the use of a shaping and screening machine to adjust the particle shape, and the aging and sintering process of the raw materials, present a simplified and effective process.

[0014] (3) Strong operability and low cost: Compared with the traditional rotary kiln sintering method, the present invention provides a solution with simple process, low cost and strong operability. This means that enterprises can effectively alleviate the problem of rotary kiln ring formation with lower technical threshold and cost investment, and improve production stability and economic benefits.

[0015] (4) Targetedness and practicality: The present invention specifically targets the problem of ring formation in the rotary kiln during the sintering of ceramsite after deoiling shale gas drilling cuttings. By studying the ceramic components of deoiled cuttings, the volcanic ash activity of fly ash, and the hydration reaction of ordinary Portland cement, it ensures that the ceramsite precursor has a certain strength after aging, thereby effectively coping with the challenge of ring formation. This targeted solution demonstrates the high practicality and innovativeness of the present invention in solving problems.

[0016] (5) Technological innovation and application potential: This invention not only solves specific technical problems, but also demonstrates technological innovation and application potential in the field of rotary kiln sintering. By improving the raw material ratio, granulation process and sintering process, it provides feasible solutions and reference experience for similar industries. DETAILED DESCRIPTION

[0017] Implementation Case 1:

[0018] The raw material ratio of expanded clay is: deoiled rock chips: fly ash: ordinary Portland cement in a mass ratio of 5:4:1.

[0019] The implementation case includes the following steps:

[0020] 1) De-oiled rock chips, fly ash and ordinary Portland cement are mixed uniformly according to the raw material ratio to obtain a mixed raw material;

[0021] 2) feeding the mixed raw materials in step 1) into a double-roll granulator for pressure granulation to obtain ceramsite raw material;

[0022] 3) taking the ceramsite raw material from step 2) and adjusting the particle shape by a shaping and screening machine and aging it for 2 days;

[0023] 4) The ceramsite raw material after aging in step 3) is sieved and put into a rotary kiln for sintering to obtain ceramsite.

[0024] According to the implementation case, ceramsite sintering is carried out in a rotary kiln, and the ring-forming time of the rotary kiln is reduced from 12 hours in the original formula of the enterprise to 189 hours. The present invention has low cost and high feasibility, and effectively alleviates the problem of rotary kiln ring-forming in the process of sintering ceramsite after deoiling shale gas drilling cuttings.

[0025] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. The present invention discloses a method for alleviating the ringing of a rotary kiln during the sintering process of deoiled rock debris-based ceramsite, which mainly includes the following steps: (1) taking deoiled rock cuttings, fly ash and silicate cement and mixing them evenly to obtain a mixed raw material; (2) the mixed raw materials are fed into a double-roll granulator for pressure granulation to obtain ceramsite raw material; (3) The ceramsite raw material is aged after adjusting the particle shape through a shaping and screening machine; (4) Screening the ceramsite raw material and putting it into a rotary kiln for sintering to obtain ceramsite.

2. The mixed raw material according to claim 1, its main characteristics are as follows: the mixed raw material is obtained by uniformly mixing 5-7 parts of deoiled rock chips, 2-4 parts of fly ash and 1 part of ordinary Portland cement.

3. The deoiled cuttings according to claim 1, wherein the deoiled cuttings are derived from a thermal desorption and oil removal process of shale gas drilling cuttings, and the oil content is ≤ 1%.

4. The fly ash according to claim 1 has the following main characteristics: the fly ash comes from the desulfurization and dust removal section of the ceramsite sintering rotary kiln, and the volcanic ash activity index is ≥0.

85.

5. The silicate cement according to claim 1, wherein the silicate cement is ordinary silicate cement, slag silicate cement or fly ash silicate cement.

6. The ceramsite raw material according to claim 1, wherein the ceramsite raw material is aged for 2-7 days under normal temperature and pressure.