Application case 2: Anode baking flue gas cleaning control system.

Project Name: Nanshan Carbon Plant anode baking Alcoa two flue gas purification device monitoring system

Implementation Date: May 2003

Outline

Baking plant flue gas purification device is located at the end, including flue gas cooling subsystem, the subsystem dust bag, aluminium vacuum material handling subsystem and control subsystem. In the realization of the anode baking gas cooling, purification and discharge at the same time, but also for anode baking system provides a stable negative pressure, to ensure the normal operation of the anode baking.

Flue gas cleaning system, automatic control system is to purify the production monitoring and control of the integrated control system for flue gas emissions in the process of flue gas temperature , pressure, flow and other data to monitor, control, Carbon Factory anode baking system plays a crucial important role,

Process Description

Come from the baking plant flue gas first enters the spray tower, atomized water spray tower through the flue gas is cooled, if the flue gas temperature is low, spray cooling tower without treatment, only the spray tower outlet flue gas temperature is high the set value, the atomized spray tower was cooled, when the flue gas temperature is below the set value, stop the spray.

The cooled flue gas into the venturi reactor, the reaction with alumina, in the flue gas tar, asphalt particles adhered on the alumina powder. Alumina powder by a feed motor from the disk added to the hopper feed pipe, transported by the flow of the fan into the venturi reactor.

 After the reactor is fed into the gas bag filter, bag filter consists of two, each precipitator dust from the 12 chambers. Alumina powder is collected by bag filter and after into the return duct returned into the back bunker by the lift fan. Cleaning Blowback control has three operating modes: manual, timing, and differential pressure.

Baking plant required for normal production of negative pressure, purification system was cited by the wind turbines, the negative pressure is adjusted by adjusting the fan inlet valve opening businesses to achieve.

Control requirements

In order to ensure the normal operation of baking and emissions standards, requiring automatic control system for purifying device performs the following monitoring functions:

Acquisition, monitoring flue gas inlet and spray tower outlet temperature changes according to the temperature conditions implemented spray, bypass, through fire and flood control;

Detection alumina material flow pipeline and promptly stop sending alarm information;

Detection alumina silo material level, upper and lower alarm;

The action of the electric valve control and detect the switching status, fault alarm information;

Detection alumina flow and the formation of closed-loop control feeder, feeder speed controlled by an inverter;

Bag-type dust collector differential pressure detection state, in accordance with the three modes (manual, timing, and differential) control dust cleaning process;

Detecting changes in the negative pressure in the flue gas inlet, the inlet fan businesses form a closed control valve, the negative pressure to keep the set value of the error range;

Flue gas flow meter detects solid particle content, higher than the set value alarm.

Equipment selection and control scheme

  According to the actual requirements of security for the system to function properly, all full selection of an instrument imported or joint venture products:

All pressures were detected by ABB's pressure and differential pressure transmitter;

Temperature detection using ABB's platinum thermal resistance;

K-TEK material level using radar level gauge;

Flue gas flow using Verabar meter;

Gas -solids using English general products.

This system uses lower machine control system Siemens S7-300 series programmable controller (PLC), the central processor (CPU) using CPU315-2DP, using the interface module IM365 connected expansion I / O system can be extended communication speed.

PC system using industrial control machine as a man-machine interface, through the CP5611 communication card access Profibus-DP bus to communicate with the CPU, monitor software uses Siemens WinCC configuration monitoring software, multi-screen display system of the electric valve status, and monitor throughout the temperature and pressure changes.

Block diagram of the hardware configuration：

   Use Siemens STEP7 V5.0 to program software programs. STEP7 is one pair of S7-300 and S7-400PLC programming application configuration package can program S7-300, 400PLC program that can handle more complex PID calculation, but also on-line monitoring of the program, the query failure.

Application case 3: The optimal control of the new product RMPOS combustion boiler

RMPOS is the latest high-tech product developed by Beijing CIMAC Technology Co., Ltd., It is based on advanced neural network technology, modern control theory and nonlinear algorithms, through establishing a dynamic multi-objective optimization controller, intelligent optimization and adjustment DCS set parameters and control deviation, to achieve optimal control of boiler combustion, thereby improving thermal efficiency, reduce pollution emissions, with significant economic and social environmental benefits.

一. System features and optimization results

A.System features：

● System configuration is simple: just need a PC and system data communication tools

● As a software product, no loss, less maintenance

B. Typical optimization results：

• Improve combustion efficiency of 0.5% to 2.5%, fuel savings,
• NOx emissions by 10% to 50%, while reducing emissions of SOx and COx, is conducive to environmental protection
• Reduce the carbon content of fly ash
• Improve the quality of reheat steam temperature control, reducing both sides of the deviation
• improve operational automation level
• Reduce the labor intensity of operating personnel
• Extend equipment life
• reduce accidents and improve safety productivity

二. Economic Analysis

As a 300000 kilowatts coal-fired units, through optimized control system, if the boiler thermal efficiency rises by 1% a year, as the direct economic benefits for the 1.38 million Yuan, not including incidental indirect benefits. At the same time there is this project good social benefits, saving valuable coal resources, reducing air pollution and are environmentally friendly.

三. Power Plant Example: Before and after optimization system into the boiler thermal efficiency of about 2%

四. Project Background of RMPOS

Plant is a complex system, may occur at any unit load changes and other confounding factors, it is difficult to rely on artificial continuous operation will be in the best state of the control unit, which is the most typical boiler combustion control. Fuel cost is the main cost of power generation , power plant flue gas emissions is the main source of pollution , and how skillfully continuously adjust the amount of wind , bellows and furnace pressure and other variables , and always will be the best run state boiler control , which for the operating personnel technical level and workload requirements are very high . In fact , DCS system, there are thousands of data points , in part to participate in the control , in part for operating personnel to monitor the operational status of the unit , their role does not really play out. Boiler efficiency is a complex curved surface, the impact of many factors, and these factors are subject to change, by operating personnel continuously looking for the highest point of the surface is impossible, even if the operating personnel know the highest point, asking him to simultaneously adjust many parameters, which is unrealistic, with the help of RMPOS optimization control system, you can easily do it.

五. RMPOS principle

Artificial neural network is a simulation of biological neurons in the brain cell structure and function constitutes an information processing system with self-learning, self-identification, adaptive characteristics, can be arbitrary precision approximate any nonlinear continuous function, with a strong for complex environments and the ability to multi-objective control requirements for optimal control of complex systems.               

                

六. Structure and working process

RMPOS as a secondary control system, in addition to the necessary data communication, no need to add new hardware. RMPOS from DCS control system parameters in real time, through the analysis and optimization, obtained set-point or control deviation of control parameters affecting thermal efficiency of the boiler, and recommended valuesfor these parameters in an open loop or closed loop back to the DCS. Parameter returns once every 15 seconds, fully meet the control requirements of real-time dynamic scene. In addition, in order to ensure safety in production, the system also has the data validation feature, if there is deviation from the normal input parameters, the system will automatically exit, and gives alarm.