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 The construction of enterprise-owned power stations will bring opportunities to the power design market. This gives electric engineering designers more opportunities and conditions to have full contact with the non-power system industry. In recent years, our institute has successively undertaken a number of projects involving the construction of new or modified or extended projects for self-owned power plants outside the system of coal mining, petrochemical, papermaking and other industries. Because each industry has its own characteristics, the requirements for the operation of the power plant are not the same. How to make the design work is a problem that every designer will face. This paper combines some specific design conditions of Dongguan Hailong Paper Co., Ltd. #5 machine engineering. , talk about a few experiences.
I. Project Introduction Dongguan Hailong Paper Co., Ltd. #5 unit is part of the owner-owned power station unit of wholly-owned foreign enterprise Dongguan Hailong Paper Co., Ltd. The planned capacity is a 3×50 MW coal-fired desulfurization extraction steam heating unit with a master control operation. In the current period, one station was built, and the public system was designed according to the planned capacity. The boiler is a WGZ280/9.8.1 type high-temperature, high-pressure, natural-cycle, coal-fired solid slagging furnace produced by the Wuhan Boiler Works, with a steel structure and open-air layout. Light oil ignition and combustion, the oil gun uses mechanical atomization. The steam turbine is a C50-8.83/0.648 50MW single-suction condensing steam turbine produced by the Nanjing Turbine Generator Plant and an electro-hydraulic control system. The generator is a QF-60-2.10.5 air-cooled 60 MW turbine generator produced by Nanjing Turbine Generator Factory. Brushless excitation system. Steel ball mill middle storage type hot air powder feeding system. Each furnace is equipped with 2 cylinder steel ball mills, 2 belt coal feeders, 2 powder dischargers and 12 impeller feeds. Feeders and feeders are frequency controlled. Balanced ventilation system, each furnace is equipped with 2 sets of fans, 2 sets of induced draft fans, all of them are centrifugal fans, and air preparators are tube type. The heat recovery system is equipped with 3 low pressure heaters, 2 high pressure heaters, 1 deaerator and 1 steam seal heater. A bubble deaerator. The public system is equipped with 2 desuperheaters and pressure reducers. The project will provide 0.648MPa, 227°C, and 150t/n low-pressure steam to the newly-built papermaking workshop during the same period; electricity will be used for its own use and will not be connected to the local grid.
Second, the specific design 1. The determination of the control mode  As the project planning capacity of 3 × 50 MW units, the main steam and water supply system for the mother control. According to the actual project, at the design stage of the project, it is necessary to determine the furnace, machine, and electricity centralized control in cooperation with the related professional such as heat engine, and the control room adopts a three-machine-one-control scheme. The control room is arranged between the #5 furnace of the current unit and the #6 furnace of the next unit, and the rational layout is reasonable and feasible. According to this, several control room layout plans are recommended to the owner. However, after the owners read it, they proposed that the three-machine-one-control method is reasonable, but the construction of the current project is only one, and the construction dates of the other two units are still inconclusive. From the perspective of private enterprise management, they do not want to sacrifice a great deal for the next period. With space, neither profit nor capital idleness. Therefore, it is preferable to re-establish the control room when the next phase of the project is launched, and insist on adopting a one-machine-one-control approach. For the conditions in which we proposed that there are different unit-to-machine and furnace cross-operations in the parental control operation mode, one machine-one control is not conducive to the coordinated control of the three units. The owner thinks this can be solved by the operating personnel frequently exchanging information among the three control rooms and increasing the labor intensity to solve this problem. On the other hand, the engineering furnace and machine matching in this period can be operated temporarily based on the unit system control mode. Ensure the safe operation of the unit. Under the repeated insistence of the owners, we met their requirements and finally determined that the control method was furnace, machine, and electric centralized control, and the control room was controlled by one machine. Eliminating the electric control building, boilers, steam turbines, generators, oxygen-free water supply, temperature reducing and decompression, fire-fighting pumps, circulating water pumps and other systems are centralized to a control room for unified monitoring, which facilitates dispatch management of the whole plant. The central control room is located between columns #4 to #6 of the operating floor BC frame. There are two electronic devices, #1 and #2. #1 The electronic equipment room is located between #3 and 4 columns, and all the DCS and related cabinets are located here. The engineer station is located in #1 electronic equipment room. #2 The electronic equipment room is located between the two furnaces in the operating floor. The power distribution cabinet, the thermal distribution box and the electric secondary equipment are located here.
2. Determine the level of control. What kind of control level is adopted will play a crucial role in the operation and management of the power plant and determine the efficiency and effectiveness of the power plant. In engineering design, first of all, we should fully listen to and respect the opinions of the owners, but we should not follow blindly. We must give comprehensive consideration and judgment from the perspective of design so that we can design finished products that are satisfactory to the owners. The final determination of the level of control over this journey has undergone a rather tortuous process.
 At the stage of program identification, the owner explicitly pointed out in the minutes of the meeting that this project adopted the control method of a conventional instrument panel. We feel embarrassed about this. Nowadays, with the rapid development of computer technology, the maturity of control theory and the renewal of control methods, DCS has greatly improved both in terms of safety, reliability and practicality. With the successful application of DCS in various power plants across the country, the power plant The level of automation control has been substantially improved, DCS decentralized control system has become the first choice for power plant design. With the development of the times and the advancement of science and technology, the control mode of the conventional instrument panel, which is mainly based on type III instruments, has been difficult to trace in modernized new power plants and is being replaced by DCS. Many of the domestic early-built power plants with conventional disk control have been or are undergoing DCS retrofits. Hailong Paper Co., Ltd. is large in scale and well-funded. The paper production lines are all imported advanced equipment from abroad and adopt advanced control methods. However, the level of control of self-powered power plants is so low that it is puzzling. In line with the attitude of providing services for owners and owners, we conducted special discussions with owners on this issue, comparing DCS control from operability, reliability, stability and economics to dashboard controls, and clarifying its advantages. And rationality, I hope the owners can listen to their opinions and change their thinking.
 However, as a proposal for the program, the owner must have its reasons. The analysis is as follows:
 (1) Since the power station is only a paper factory auxiliary workshop that provides industrial extraction, the investment relative to the entire paper mill is only a small part. The upper decision makers of the paper mill did not pay enough attention to it. In the discussion we It is learned that the control of the #1~#4 units of the company is a conventional instrument panel. For this type of control method, the operating personnel are very familiar with the operation and no problems have occurred. Therefore, the unit is naturally used. Control level.
 (2) Due to the nature of the business, all employees are determined to be working for the employer. If there is any mistake in their work, they may face punishment or even be dismissed. The company clearly stipulates that whenever the supply of steam cannot be interrupted, the profit of the mill is calculated in minutes. No worker can afford it because of a loss of production due to a power station failure. The operating personnel would rather choose the most familiar operation method to ensure that they did not make mistakes in their work, and that they did not have time to understand whether such operation was reasonable and advanced. Therefore, the grass-roots specific staff members also strongly recommend conventional dashboards for their own benefit.
(3) The non-power system industry may not have a deep understanding of DCS in the control of self-provided power stations. To investigate the operation of DCS in different power plants, it is not concerned with how the DCS control system is economical, reasonable, and controllable, but wants to understand How many accidents occurred, stopped several times, etc., exaggerated its failure situation, resulting in doubts about the reliability of the DCS and distrust it.
 In addition, training operators need to master DCS operations for a long time, and the off-study learning is inconsistent with the principle of employing the company; companies will certainly recruit skilled DCS operators to replace conventional instrument operators who have no use, causing them to DCS. Inconsistent; inconsistent with the way DCS controls the theory of profit control, easy to rely on conventional instruments, it is difficult to identify with advanced production methods, the fear of operational errors in the work and the reality of punishment and dismissal, etc. All have caused specific staff to conflict with the DCS.
 For various reasons why the above owners prefer to abandon DCS and consider conventional instrument control methods. We conducted in-depth and meticulous communication with the owners, from the DCS software and hardware configuration, the safety, reliability, and ease of operation of the power plant to DCS investment and control room layout, compared with the conventional dashboard. After several special arguments, the owner finally got convinced by us, and made it clear that the #5 machine project had an improvement in the control level compared with the first four units. It was decided to adopt the DCS decentralized control system for the unit control. However, at the same time, another requirement was put forward. In order to ensure reliable operation, when DCS crashes, it is necessary to add enough hands-on exercises to maintain its normal operation. We also strongly oppose this decision. Now that the entire system has been decided to adopt DCS control, there is absolutely no need to increase enough backup operations. This is first of all a distrust of the DCS decentralized control system. It is afraid that the DCS system will cause problems and affect production, and still expects the traditional conventional disk control. Theory and approach. Facts have proved that the monitoring coverage of DCS on the unit is becoming more and more perfect, and the design of the HMI of the unit control room has also undergone profound changes. The monitoring mode of the conventional instrument plus hard hand operation has been canceled and replaced by a large screen, CRT operator. Station plus soft hand exercises.
 The owner proposed to “reserve part of the backup hand operation to prepare for the normal operation of the unit when the DCS system failsâ€. After our demonstration, we believe that the following problems exist:
 (1) Inconsistent with the provisions of 12.9.4 of the “Technical Specification for Thermal Power Plant Design†(DL5000-2000) regarding the backup manual operation, we can only design the necessary backup operation for the emergency shutdown of the unit in accordance with this clause.
 (2) The control room area increases. No backup manual operation DCS design, 50MW unit unit control room area needs 16 × 8 = 128m2: reserve part of the backup operation DCS control mode design, the control room area needs a minimum of 24 × 8 = 192m2, the control room is located in the BC framework, This makes the control room appear cramped and inconvenient to operate. In addition, it also inconveniences the overall arrangement of the main subject.
 (3) The construction cost is greatly increased.
 (4) Security is not guaranteed. Due to the addition of conventional meters, accidents were increased. The unit needs overall coordinated control, and retaining only part of the operation does not guarantee complete safe operation of the unit when the DCS runs out of control. Only safety shutdowns can be done at this time.
 (5) The operation method is confusing. When operators are accustomed to the operation centered on the CRT and the keyboard, if there is a DCS failure, in the event of an emergency, the normal operation can be performed. Can it be adapted to it?
 Our school believes that, according to the rules of “fire regulations†and “twenty countermeasures,†when DCS fails, emergency shutdowns and furnace shutdowns can only be achieved through necessary backup operations. On this basis, part of the It is almost impossible to achieve complete normal operation of the unit.
Both sides have their own views, and after several consultations, they make concessions to each other. We eventually respected and agreed with the owner's proposal and retained the necessary backup exercises to ensure that the loss of paper production was minimized. Based on this principle, the control plan was finalized as follows: The unit adopts the DCS decentralized control system, the turbine control adopts the DEH digital electro-hydraulic control system, and the unit runs with the CRT and the keyboard as the center, in cooperation with the local personnel, in the control room It can realize the start and stop of the unit, the monitoring and operation of the normal operation, and the emergency treatment under the accident condition.
In order to ensure that the DCS can maintain the operation of the unit in the event of full operation or operator station crash, according to the owner's requirements, in addition to the provisions of the “Fire Regulationsâ€, the steam drum accident water release door, boiler safety door, and AC-DC lubricating oil pump shall be set on the backup disk. In addition to other back-up operating methods, back-up discs also reserve the backup operation means for sending air, powder, main steam, and water supply auxiliary equipment, valves, and baffles. Specifically:
 ◠A, B blower inlet baffle to adjust the door M / A operator;
 ◠A, B induced fan inlet baffle to adjust the door M / A operator;
 å·¦å³ â— left and right side of a water temperature control door, two water control valve M/A reducer;
â—Main water supply sluice gate, large feed water bypass gate, small water supply bypass bypass M/A manipulator;
◠Condenser feed water conditioning door M/A operator;
â—#1,#2 high water level adjustment M/A operator;
 ◠Deaerator pressure, water level adjustment M/A operator;
 â—#1, #2 temperature and pressure reducer outlet pressure, temperature adjustment M/A operator;
 These operators should be able to bypass the control system processor and use the same power supply as the control drive unit. Both directions are free from interference when switching. In addition, the control panel is also equipped with thermal signal light plate, furnace flame TV, water level television and related secondary instruments.
The ash removal system adopts the PLC+CRT control method, and the chemical water treatment, the fuel pump room and the slag removal control adopt conventional instruments. The auxiliary system has a workshop control room.
 Experience the owner's requirement for the unit's control level Several changes from the conventional instrument panel to the DCS plus the conventional instrument panel, and whether to use the human screen The big screen is one unit, one machine, one furnace; electrical professional backup manual operation reserved With several changes in the number, we have designed as many as 11 kinds of control room layout plans, and finally reached the owner's satisfaction.
3. Functions implemented by DCS  Data Acquisition System (DAS)
â—Analog Control System (MCS)
 Furnace Safety Monitoring System (FSSS)
â—Sequential Control System (SCS)
â—Electrical Control System (ECS)
 In addition, it has the function of implementing DEH operator station communication with DEH and implementing monitoring functions of other control systems (with data communication interface).
Third, the existing problems 1. Soot blowing system, fixed row system into the DCS
 When determining the three major mainframes and signing technical agreements with them, the owner determines that the system will be soot blown. The fixed row system is controlled by PLC program control. In the reality that the DCS is powerful and the operation mode is advanced, it is very reasonable and economical to incorporate soot blowing and drainage into the DCS system for overall control. Because of their single control system, operating on a program control panel not only lags behind, but also increases equipment investment.
2. There are too many types of equipment to choose from, and the design is complex. When the equipment is selected, the owner uses multiple products of the same type of equipment. For example, electric actuators are used for Rotork, German PS series and domestically-adopted products such as French Bernard technology; There are a large number of different types of conventional instruments. These models have too many models, adding complexity to design, installation, and commissioning operations.
3. The level of successful bidders is not good enough. Individual manufacturers have not even involved in power systems, and have no experience in the operation of power plant equipment. It is very difficult to cooperate with them when designing.
Fourth, a few experiences  through the design of the entire process of the Dragon Paper Industry, felt the following experience, which I would like to learn from the design of similar projects in the future.
 1. More communication with the owner. To complete a project design, we must first communicate with the owners to learn more about some of their ideas, especially the power system outside the industry, for its unique process requirements, operating conditions we do not know, only with full communication with them In order to understand the characteristics of its industry, we designed a finished product that meets the requirements.
 2. Be prepared for any changes that may occur at any time. Because the industries represented by the owners may have different characteristics in operation, management, and operation, they may change at any time, causing the designers to change the original design again, and some may even make repeated changes. This phenomenon occurred in the early work of the project. In this regard, designers should fully understand and give support.
 负责 负责 负责 负责 负责 负责 负责 负责                      As a design institute, it is our responsibility to design quality projects and be responsible to the owners. We are responsible for recommending better design ideas and control theories for them to understand and convince them. Only in this way can we achieve a win-win situation.
In recent years, with the deepening of reform and opening up, the level of national economic development has continued to increase. Economic development, electricity first. In order to meet the development requirements of enterprises, many industries have newly built or rebuilt or expanded self-contained power plants. With the increase in the size of enterprises, the capacity of power plant units is also expanding day by day.