This paper introduces the technical development status of mechanized lime shaft kiln with mixing fuel and proposes improving measures for the main problems,and finally proposes the prospect in the next few years.
This paper introduces the structure,properties,chemical composition,mineral composition of the magnesite,as well as the physical and chemical changes in the calcination process,and studies the technical characteristics of grinding process,two-step calcination process and secondary briquetting process for production of high purity magnesia.
Application of turbine direct drive technology on draught fan for double beam kiln
Exhaust system and cooling system for the heat conduction oil of the combustion beam in the double beam lime kiln were re\|designed.The waste heat and heat energy of the heat conduction oil are recycled.By installing the turbine and electromotor on the same side,draught fan is directly driven by the recycled heat through turbine.This paper analyses the economic effects of such design and indicates that every kiln can save 1.4 million Yuan annually by power saving and the recoveryrate of waste heat is higher due to the omitting of intermediate energy conversion process.
Using zircon billet as aggregate，zircon powder as powder and aluminum dihydrogen phosphate liquid as binding component，this paper studied how different amount of micro zircon powder as admixture affects the performance of zircon ramming mass.With the help of scanning electron microscope，this paper also found the performance of the material under high temperature was improved as zircon powder amount was increased.The best case scenario occured with addition of 5% zircon powder to the mass.Micro level zircon powder will form a kind of heterogeneous plate-shape ceramic bond,improving mechanics performance of the material to a great extent.
Converter tapping hole is the channel of molten steel flowing from BOF furnace (converter furnace) to the ladle,which is one of the key refractory components for the converter.The tapping hole is composed of seating bricks and sleeve bricks with different structures and production modes.Utilization and installation should be taken into consideration to choose the production mode or structure of tapping hole.
At present,numerous CDQ chambers with coke quenching capacity of 190t·h-1 have been put into operation in China.The integral structure of the chamber is dumpy,the ratio of height to diameter of the cooling chamber is less than 0.6,and double chutes process is applied in the chamber.This article introduces the problems likely to occur in the chute in actual production and corresponding measures.
This paper introduces development situation, technology innovation situation and several problems of lime rotary kiln in 2016,and predicates the industry development and technology trends.
This paper gives a general market analysis on double-shaft lime kiln in 2016 and proposes improving measures towards the technical characteristics and the problems,finally predicates the development in the year of 2017.
This paper introduces a new technology of low-calorie gas in oxygen-enriched combustion for lime rotary kiln,and demonstrates the existing problems and solutions of low calorie gas in lime combustion for lime rotary kiln by theoretical analysis and thermal calculation.It concludes that oxygen-enriched combustion can increase the temperature of lime calcination and meet the requirements of product output and quality demand which is suitable and feasible for national conditions and factory conditions.
The service life of refractory is seriously restrict normal production of rotary kiln,which is the bottleneck of lime production process.The reasonable optimal use of refractory can not only reduce the production cost,but also prevent accidents.This article tackles technical problems from four aspects such as brick structure,raw material,chute cross section and anchor hook structure,which brings remarkable effects.
This paper introduces a kind of floating workbench for shaped product molding, which solves the problem of the density differences in different positions of sliding nozzle,and achieves the aims of improving products quality and production efficiency and reducing the production cost.
Flow simulation module of Solidworks software was used to numerical simulate on the cold air supply device for kiln crown of double shaft kiln.Through the contrastive analysis on different types of cold air supply devices，the critical factors were obtained which affect the cooling effect and the device structure was optimized and improved to design the optimal structure of cold air supply device.
In recent years, low calorific value gas and pulverized coal were combusted as blended fuel in double-shaft kiln. Based on the difficulties of fuel blending and fuel undersupply as well as the demands of lowing fuel expenses for some enterprises, ACRE develops the double-shaft lime kiln burning with low calorific value gas and pulverized coal which can be used alone or together.
Aim to the problem of effective utilization of small sized lime stone, this paper proposes a new calcination process scheme of lime rotary kiln with waste heat power generation system, as well as develops and introduces new type long rotary kiln and new type vertical cooler on the basis of the new process scheme.On analysis the economic benefit and social benefit,we find that the new process scheme has great practical value and popularization value.
Large quantities of CO2 is contained in tail gas of Maers kiln.Recovery and utilization of the CO2 has remarkable environmental value and economic benefits. This paper briefly introduces a number of CO2 recovery processes commonly used in industry and selects an appropriate recovery process for Maers kiln after comparison from economic and technical standpoints.In addition, the paper illustrates the technical principle and process flow of MEA method and predicts the environmental and economic benefits of the project.
All the power of the air burned by TD type double-shaft kiln is sourced from root blower. Different working conditions of blower’s inlets lead to quite different choices of blowers. According to tracing running data of blowers and analyzing the changes of kiln pressure of 500t·d-1 double-shaft kiln, calculating methods of blower type selection are systematically put forwards.
The automatic control system’s design scheme based on the redundant PLCs is described at length according to the designed control system of double-shaft lime kiln. The process flow and main equipment of double-shaft lime kiln are simply introduced. The shaft temperature’s double closed-loop control system and the proportional control system among the cooling air, the cooling air from the fuel gas gun and the theoretical combustion air are analyzed. The control principle of loading engine and the parameter set method of frequency converter are described in detail. Gas compression station control system and storage & transportation control system are also given. The control system general scheme and network configuration based on the redundant CPUs, redundant networks and redundant servers is designed. The software composition, hardware composition and the main functions of the double-shaft lime kiln control system are given.
This article introduces the procedures of lance replacement and the resume production by preheating gas to the ignition temperature in Maerz kiln, and proposes optimum methods combining with practical situation.
In this paper, flame photometry was used to evaluate the uncertainty of sodium oxide content, measurement model was established and influence factors were analyzed.
The production process of KR desulfurizer is introduced.By analyzing the defects of the whole process,the improved scheme of device is put forward.The results show that the improved production process can meet the demands of the particle size for desulfurizer,the vibrating screen is not appropriate for in production process of desulfurizer,and the circular hopper is more suitable for lime powder transportation than quadrate hopper.
This paper mainly introduces the projects of Qinghai lime production line and Mongolia’s lime production line with annual outputs of 100 000 tons both，and analyzes the optimization of the raw materials，process flow，equipment selection and installation.After production commissioning of the firing system，the paper analyzes the shaft kiln firing system.Finally，it summarizes the commissioning experience and proposes recommendations on further possible optimization.
By comparing the data of silica fireclay with different standards, this paper analyzes the effects of chemical compositions on high-temperature performances,and the analysis results of experiment data will be applied in the revision of the lasted editions of the silica fireclay standard.
Taking for example the active lime production line of rotary kiln,this paper introduces the key points of the random emission of dust in the production process of active lime,and proposes the controlling measures.
Taking a production line of calcium-based products with the capacity of 1.1 million tons as study object,this paper establishes and analyzes the resource comprehensive utilization scheme on energy conservation and emission reduction,which plays a guiding role in development of calcium industry.
In this paper,the current situation in using RH furnace refractories is summarized and its regular problems are analyzed.Solutions and measures are also given for an appropriate using this material in the long run.Furthermore,rational selecting materials at different positions in the RH furnace and the design are studied.
This paper briefly introduces the features and processing problems of solid wastes,and discusses the feasibility of solid wastes co-processing technology in cement kiln by comparing the national and international technologies.The result shows that the industrialization practice of the solid wastes co-processing technology in cement kiln can ensure harmless disposal and achieve the aim of emission reduction of solid wastes.
With the characteristics of low heat consumption,high quality,small occupation of land and high automation,double-shaft kilns occupy increasing market share in China.Control system is the main technological part of the double-shaft kiln.And control optimization is an important way to improve technology of the double-shaft kiln and guarantee the product quality.
This paper briefly introduces common technical specifications of lime slakers matching with dry method or semi-dry method desulfurizer,and systematically introduces the main performances of the matching devices and requests of the matching electrical devices and I&C system as well as supervising manufacture,performance test and technical service of project management.
This paper introduces the impacts of lime stone,coke oven gas,power consumption,process parameters control,labor costs,and other factors on the metallurgical lime production cost with Maerz kiln.In view of the actual production status,targets are put forward for the important factors such as fuels,raw materials,power consumption,process parameters control,etc.and control measures are made resulting in an dramatically-lowered operation cost so that the production cost of metallurgical lime can be lowered and management level of the same type of kiln can be upgraded in lime industry.
Large-scale double-shaft lime kiln is an inevitable development trend for lime industry. The research and development of the control system is an important part of the burning technology of large-scale lime kiln, and a stable reliable and standard control system is the requirement for large-scale lime kiln construction and application.
The lime process of rotary kiln is relatively complex，and the output and quantity of the products are influenced by material condition，material conveying speed，burning temperature，fuel supply，combustion air and main suction and other process parameters as well as working condition inside the kiln.Combined with lime process of the rotary kiln，this paper puts forwards technology of imitating biological neurons for model auto tuning by collecting online data with the basis of prediction technology of BP neuron network，and establishes high precision control model.The predictive control algorithm is an effective control algorithm with good applicability which can solve on\|site multi\|variable coupling effect and big time delay system.In practice，the burning process is controlled by burning unit and control system，the whole production system can run automatically according to the default parameters，and the limestone decomposes completely following the default temperature curve to produce high quality lime.
Bearings seat were located inside the chamber and on both sides of Φ1 220 reversing valve of Maerz lime kiln.Bearing seals could be easily burned out by hot gas and high concentration dust during the producing process,which could cause bearing failure and take too much time to replace the bearing and lead a great impact on production.After analyzing the reversing valve and improving its construction,bearing blocks are setted outside of chamber,which effectively avoids the accident of bearing failure etc.and ensures stable production.
The temperature of the tail gas in air heater of rotary kiln is above 250℃,and the exhaust temperature of the tail gas into the atmosphere is about 170℃,the waste heat should be utilized to avoid wasting energy.Based on the principle of saving energy and waste gas recycling, the factory can make full use of the gas energy to heat the water to the heating temperature by using low-temperature waste heat power recycling technology and setting one gas heat exchanger.
Aiming at the deformation problems of tundish dry material moulding bed during use, this paper analyzed the reasons of deformation and explained how to reduce the deformation and increase service life from two aspects, including of improvement on the inner temperature field and the integrity of the moulding bed.
This paper introduced the pressure stabilizing device used for heat treatment carburizing furnace and working device used for vertical hoisting and quenching.The combination of both the above devices improved the performances of die sleeve lower hardness and diameter size distortion out of tolerance caused by unstable and volatile pressure for carburizing furnace.As a result, the furnace pressure were stable,the quality of products after heat treatment and production efficiency were improved,and the production cost were reduced.
Wet injection lining technology has successfully applied in repair of many lime shaft kilns.The successfully extensive applications should be attributed to the innovation of material,improvement of technology and conclusion of feedback from users.
Coal consumption is an important indicator of calcination cost for rotary kiln,which accounts for about twenty percents of the total cost.This plant tackles technical problems in four aspects,such as calcining process optimization,coal preparing process optimization,reasonable repairing and raw coal quality control,and gets some results and improves the comprehensive management capacities as well.
This paper analyzes the production performance of Maerz kiln burning with low calorific value converter gas，and puts forward some improvement measures which can effectively solve the adverse effects of low calorific value converter gas and maintains steady production for the kiln.
This article introduces the combustion process,furnace condition characteristics and lining state of the thermal oxidation furnace.The development and design on lining materials and structures can resolve the premature damage problems of the key parts and improve the erosion resistance and thermal shock spalling resistance of furnace lining,consequently effectively increase the lining service life.
This paper studies a kind of new type castable used for end cover in centrifugal cast roll production.The castable is prepared with high\|quality flint clay as main raw material, mullite ore as matrix, and added alumina micro powder to produce mullite through the reaction of the introduced Al2O3 with SiO2 during use.The new type castable improves the thermal shock resistance, reduces the production cost and increases the service life.
Aiming at the problems of lining materials such as short service life, high temperature of kiln shell and large heat loss which are caused by alkali erosion and thermal shock spalling in large-scale rotary kiln during use,a study is carried out to improve the performances of alkali resistance,thermal shock resistance and abrasion resistance. Furthermore,mullite alkali resistance composite brick combined by heavy and semi-lightweight materials has long service life,which effectively lowers the kiln shell temperature and achieve energy efficiency as well.
ISSN 1673-7792 CN 21-1544/TQ Sponsor:ACRE Coking & Refractory Engineering Consulting Corporation,MCC Postal Code:8-29
