Discussion on quality control during installation of mechanical grate incinerator in waste power station

With the acceleration of social and economic development, the quality of people's production has also improved, which has increased the amount of waste emissions to a certain extent. For the person in charge of the waste power station, it should be guided by the strategy of resource conservation and environmental protection to improve the efficiency of waste incineration in a timely manner, that is, through the use of mechanical stoker incinerators to successfully complete the waste disposal task. In fact, the installation quality of the mechanical grate incinerator affects its use effect, so it is necessary to control the safety quality of the whole process, meet the needs of mechanized waste incineration, and realize the large-scale promotion and effective application of the mechanical grate incinerator.

Key words: waste power station; Mechanical grate; An incinerator; Installation quality; Control measure

In recent years, the demand of power grate in waste power station is increasing, which requires the development enterprises of hydraulic grate system to innovate their ideas, enrich the function of hydraulic system, meet the requirements of mechanized operation of incinerator, and realize the reduction of waste. At present, Jiangsu Jiangyin City Yuecheng Huanshan Everbright Environmental Protection Energy Co., Ltd. has developed the first domestic waste incineration power grate, although it has made up the gap in the industry, but it has encountered some resistance in the technical practice stage. Based on this, combined with the problems encountered in practical work and solutions, the paper focuses on the quality control of the installation process of the mechanical grate incinerator in the waste power station, aiming at improving the installation level of the mechanical grate incinerator.

1. The role of mechanical grate incinerator in waste power station

The reason why mechanical grate incinerators are popular is that new incinerators have advantages that traditional waste disposal devices do not have, and can better meet the sustainable development needs of waste power stations in the new era [1]. From the point of view of the incinerator's own characteristics, it supports direct waste treatment, saves pretreatment and other tedious procedures to a certain extent, and achieves the goal of short-term waste incineration reduction. The incinerator has a wide range of application, and supports long-term use. During the operation of the mechanical grate, the basic needs such as stable operation and reliable operation are met. In addition, the operation procedure is simple, which correspondingly reduces the audit requirements for the mechanical grate operators. From the perspective of energy conservation and emission reduction, during the use of mechanical grate incinerators, less smoke is emitted, which can also meet the burning demand of low-heating value garbage and avoid the wide spread of pollutants, so it will not cause resistance to environmental protection practices. It should be noted that the clean smoke system plays a key role in it, so the air pollution prevention and control work can be effectively carried out.

Not only that, the functions of waste dry incineration, mixing and stirring combustion are unique to the incinerator, which once again lays the tone of its application in the waste power station, and provides reliable equipment support for the efficient disposal of waste. With the continuous improvement of the structure of mechanized incinerators and the combination of advanced technologies, the economic and social benefits of waste incinerators have been improved again, laying a solid foundation for the steady development of waste power plants [2].

2. Analysis of installation process of mechanical grate incinerator of waste power station

2.1 Installation Difficulties

First, the continuous operation of the hydraulic system of the mechanical grate is not less than 8,000 hours, and the length of the grate is > 10m. Second, both ends of the hydraulic control grate cylinders are required to be synchronized. Third, the feed speed of the feed grate requires precise control, and for multiple feed furnaces, the principle of synchronous use should be adhered to. Fourth, leakage and emergency devices are not allowed on site [3].

2.2 Installing Major Components

2.2.1 Installing the furnace barrel

Before the lifting and installation of the furnace barrel, do a good job of transportation and combination, ensure the integration of lifting operations, and complete the lifting task of the furnace barrel in the roof smoothly and accurately. During the actual installation, consider the need to eliminate risk factors and stabilize lifting, adjust the bearing of the boom appropriately, and coordinate with the crane until the furnace barrel is in place according to the established requirements. During the installation, the cable wind rope and steel frame provide support for it. At the same time, the manual micro-adjustment is made, and the whole reinforcement is carried out after the boom passes through the top of the board.

2.2.2 Installing a snake Pipe

Based on the ball-passing test, the shape adjustment and friction were carried out according to evidence, and the material quality of the snake tube was carefully checked. In the specific installation, it is necessary to ensure the rationality of the installation sequence, and properly control the spacing distance between the components, as well as the direction and position of the snake tube, so as to achieve the width deviation between -4.7mm and 4.5mm, the vertical deviation of the side tube between -4.6mm and 4.6mm, and the diagonal deviation between -9.5mm and 9.8mm [4]. The assembly link, based on the fixed position, completes the smooth docking task of the container pipe, and then installs the next pipe head one by one. In order to avoid errors in the installation process, the installation personnel are required to refer to the corresponding drawings and requirements for accurate installation, each time the completion of the phased installation task, the quality check, once the inspection process found improper, then timely correction, until it meets the standardized installation requirements, which is an effective measure to control the overall installation quality of the incinerator. When installing the anti-wear device, reserve a certain expansion gap according to the design drawing, and ensure the stability and flatness of the welding position to prevent smoke leakage.

2.2.3 Installing the Water Cooling System

The water cooling system consists of several components, such as water wall, separator, superheater, etc. The system is located in the top plate, which can shorten the heating time of the boiler and reduce the expansion phenomenon. The parts to be installed mainly include membrane wall and water-cooled wall. Before the actual installation, the staff needs to carefully check, record the firmness, welding process and integrity of the installed parts, eliminate risk factors as soon as possible, and fully ensure the stability and safety of the installation. During the installation of the water wall, the installation personnel find the position of the lifting point and install it in a team according to the relevant specifications and requirements, so as to improve the installation efficiency and save the overall installation time of the incinerator. Then the installation sequence of front top and side back is adjusted to lay a foundation for reasonable control of parameters of water-cooled bed and fluidized bed.

After the installation of the components, it is also necessary to calibrate the water wall and butt the gap. During the calibration process, the horizontal and longitudinal positions of the top plate beam are ensured around the reference line. Generally speaking, the reference point is the 100cm elevation line of the steel frame column, and the height value of the heating surface components is measured in turn, and the boom is stabilized to maintain the balance of the load state. When the gap is connected, the position of the lower header is adjusted, and the reinforcement is processed. At the same time, the tube screen splicing and the four corners splicing are implemented to ensure the stress adequacy. In the process of joint, the stress of the parts is carefully observed, and the coordination between the staff is coordinated to ensure the quality of the joint of the gap as a whole.

2.2.4 Installing rigid beams

Pay off and install cables according to the center line of the upper expansion box. The allowable ranges of pay off deviation and installation deviation are -1.8mm to 1.8mm and -4.5mm to +4.8mm respectively. In actual installation, the principle of layer-by-layer installation is followed to avoid deviation of reference point. At the same time, the installation quality of the corner is strictly controlled to make the gap size within the allowable range [5]. In addition, the installation process should also dynamically monitor the furnace pressure changes to do a good job in crack prevention and control.

3. Quality control measures in the installation process of mechanical grate incinerator of waste power station

In order to ensure the normal application of mechanical grate hydraulic equipment, it is necessary to do a good job in the early stage of hydraulic system and pipeline technology design, and strengthen communication with the owner, considering the reasonable suggestions put forward by the owner. At the same time, actively participate in the manufacturing and installation of hydraulic systems and pipelines and quality inspection activities, strict quality control. When the hydraulic equipment technology development work is completed, it is also necessary to systematically train equipment operators and maintenance personnel, so that the hydraulic equipment can be effectively applied in the operation of the mechanical grate and achieve good results in garbage disposal.

3.1 Troubleshooting Solution

In view of the mechanical grate hydraulic equipment design, there is some resistance in the safety link, so in the problem solution development link, starting from the specific working conditions of the site, and a wide understanding of similar foreign working conditions, on the basis of objective analysis of the shortcomings, improve the hydraulic system technology development program, and optimize the configuration of hydraulic components, formulate emergency configuration, so as to use one standby. The most critical is to objectively analyze the mechanical grate structure of the waste power station and optimize the structure through remote control to improve the utilization rate of the incinerator. Taking into account the objective needs of environmental protection, for the entire hydraulic system circulation cleaning, cleanliness to reach the NAS7 level requirements, the function of the test, according to the test results to adjust the hydraulic system cleaning plan, to ensure that the cleaning operation to meet the standard requirements. In addition, based on the phenomenon of one-sided artificial monitoring and inefficient monitoring, with the help of electronic sensors to feedback various alarm data to solve oil leakage, pressure relief, overpressure, high temperature and other failures, at the same time, equipped with energy storage device, in case of power outage emergencies, so that the hydraulic system quickly restore the initial working state.

3.2 Key points of construction technology

During the installation of the hydraulic system of the incinerator, errors should be reduced as much as possible, and the installation task should be completed well and quickly. Especially in the era of information technology, a platform should be built in the development of BIM technology and hydraulic system technology, that is, a model should be built using this technology to make the traditional design drawing appear in the three-dimensional model and ensure that the installation personnel can intuitively understand the distribution of hydraulic pipes in the internal structure of the incinerator [6]. In the testing process, BIM technology is also used for crash testing, incomplete testing, missing testing, and misplacement testing to provide data reference for the deepening design of hydraulic pipelines, and finally generate the best test scheme and high-precision design scheme to ensure the standardized installation practice. One of the key links, the implementation of three-dimensional technology disclosure, in order to dynamically grasp the installation quality control situation, efficient and high quality to complete the mechanical grate incinerator difficult installation tasks.

3.3 Quality control measures

3.3.1 Hydraulic system design

The design quality of the hydraulic system of the mechanical grate directly affects the installation and application effect of the subsequent incinerator. Based on this, innovation points should be added in the design process, and the design quality should be guaranteed to pave the way for the proper installation and effective application of the incinerator. First, the grate valve station power supply is set separately so that it is not affected when the line is damaged. Secondly, distributed control of the electric control cabinet, so that it can meet the requirements of convenient operation, timely maintenance and maintenance. Thirdly, the power source of the incinerator operation is adequately supplied to make the waste incineration reduction work continue. Finally, the accumulator system is improved to ensure the pressure stabilization of the hydraulic oil circuit.

3.3.2 Component Installation Design

Grate and ash hopper installation design. Before installation, number the components to avoid incorrect installation or missing installation. And the fixed shaft is installed first, and the grate is installed later. The hydraulic equipment at the grate connection position is designed and installed according to the requirements, and the inspection report presented is compliant, which means that the installation design activity is officially opened. In order to ensure that the installation personnel perform the grate combination task in an orderly manner, we should base on the installation status, scientifically develop a quality management system, as well as a dynamic supervision mechanism, avoid random installation, and greatly improve the quality installation level of the grate. Not only the installation design link should carry out strict quality control, but also the inspection, acceptance and other links need to be standardized management, so that the waste machinery incineration practice is unified control. Because there are certain risks in the grate installation design process, and quality defects occur frequently, it is necessary to implement the post responsibility system, implement the quality control work to the individual, and reduce the grate installation errors by improving the attention of the responsible subject. During this period, the emergency filing team was set up, and the members made records in the installation design, quality inspection and other links. Once an emergency was found, the corresponding emergency treatment plan was launched in time to minimize the risk of grate installation design. When the hopper is installed and designed, the section size is accurately measured to ensure that the inlet size is > the section size of the hopper, and the actual size value is consistent with the specified standard. In addition to the size of the factor affecting the quality, the ash bucket and grate gap docking work is also an important quality control point, only intact docking, eliminate cracks, in order to avoid the phenomenon of air pollution in the waste incineration link, and this operation lays the foundation for the subsequent high-quality installation of air pipes.

Furnace bar and shell installation design. Because the installation design of mechanical grate incinerator is step-by-step, the same is true in the installation design of grate bar and shell. When designing the installation plan of the bar, it is often necessary to refine the design points after the installation of the transmission device, guide the installation practice first and then, and finally improve the corresponding installation process by referring to the drawings. In order to understand the practicability of the installation design drawing, it is regularly inspected and the information is recorded. After the information is verified and correct, the furnace bar is reinforced. When designing the shell installation drawings, in order to ensure the quality of the sections, the overall design drawing is often subdivided into several pieces to guide the installation personnel to install the shell with high precision and high quality. Due to the actual installation requirements may change, so the design personnel, quality control personnel, installation personnel should communicate with each other to ensure the reference value of the design drawing. In this process, dynamic supervision strategies are implemented, supervision and management efforts are strengthened, and the supervision system is adjusted according to the situation, so that the furnace shell installation design task can be completed well and quickly [7].

Garbage feeding system installation design. In order to speed up the automatic process of waste incineration reduction, the feeding system is carefully designed. Specifically, starting from the installation and design of the incinerator feeding device, when the devices cooperate and coordinate, the feeding speed will be greatly accelerated, and the waste treatment efficiency will be significantly improved. Generally speaking, the waste incinerator is equipped with three devices, such as waste hopper, chute and pusher, and only when the devices are closely coordinated can the waste treatment be carried out in an orderly manner to maximize the application value of the incinerator. Among them, the garbage hopper is the garbage inlet, and then slides from the chute to the pusher, and pushes evenly to the grate under the action of power. During the installation design stage, ensure the constant supply of garbage to avoid the phenomenon of blocking at too fast a speed, but if the feeding speed is too slow, it will increase the cost of garbage disposal and affect the efficiency of power generation. The hopper gate is arranged at the connection between the hopper and the chute, which mainly plays a sealing role. In order to comprehensively and real-time grasp the operation of the waste feeding system, industrial TV and ultrasonic level meter are placed on the hopper, and feeding and suspending actions are made through signal transmission to achieve human-computer interaction. In addition, the water cooling jacket is set under the hopper slip pipe to avoid the radial heat of the pusher and the dry grate port affecting the equipment, and the control equipment passes the corresponding early warning information according to the actual temperature change to ensure the high quality completion of the waste mechanical incineration task.

Summary: In summary, in the critical period of effective utilization of resources and comprehensive protection of the environment, waste disposal is urgent. When the mechanical grate incinerator is used in the waste power station, it can achieve the effect of effective waste treatment and protection of the ecological environment, but also provide opportunities for the deep-level development of hydraulic system technology. The application of grate hydraulic equipment in waste power plant can not only improve the effectiveness of waste incineration treatment, but also lay a solid foundation for the quality control of incinerator installation. With the gradual improvement of the waste incineration reduction requirements and the corresponding improvement of the installation level of grate hydraulic equipment, the incinerator has been put into use with high efficiency in the waste treatment, so that the waste treatment task has been successfully completed.

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