Title: Ash Handling Plant (AHP)

Industry: Power, Cement, Steel

Business Challenge:
Ash handling system mainly design for the collection, handling and disposal of bottom ash and fly ash from ESP System to Silo area and operation of its associated systems i.e. ash water, instrument air, conveying air and fluidizing air system. To increasing availability, increasing efficiency, and controlling emissions is a major requirement of the power industry today, and its importance will grow in the future. This causes industrial organizations to purchase control and instrumentation systems first on price, so that organization is able to control, monitor the complete plant remotely with ease access.

Solution:
We are committed to provide solutions to its customers as “start with, live with, and grow with”. In order to help operations in industry and realize a greater value, lower cost-of-ownership from their automation technology investments. This approach is applicable to end users in particular & developing regions, which are increasingly concerned about the long-term costs of maintaining their control systems assets. Compact Programmable Logic Controllers (PLCs) to meet the needs of customers with a wide range of industrial infrastructure projects.
The Master Logic solution provides the versatility and low cost commonly associated with PLCs and augments it with a global support network and the ability to integrate with the industry’s newest control systems-Experion-HS. A versatile line-up of I/O modules and networking options enables flexibility in how the controller fits into an entire automation scheme. The Master Logic (ML PLC) & EPKS Control system integration enables to read/write PLC data and monitor PLC alarms and events from Experion Station. Master Logic is designed to bring power and robustness to very high-speed logic, interlock and sequencing applications. Using the Experion-HS SCADA system we can generate the graphical (Standard/Customized) representation as per the application requirement.

Activities comes under the Engineering solution of each control system –

• Engineering Documentation (HDM,I/O Assignment, System Architecture)
• Software development (Control logic, Graphics, Database, Alarm management)
• FAT (Factory Acceptance Test)-Visual inspection & testing of hardware
• Site Commissioning
• SAT (Site Acceptance Test)-operation & maintenance Training, Handover etc.

Here is the detail of all above-mentioned packages that are controlled & operated from ML PLC & Experion-HS SCADA

Application: Ash Handling System
The major systems in Ash handling system are as below:

1. Bottom Ash handling
2. Fly Ash handling
3. Fly Ash Silo
4. Ash Water System
5. Air System

Bottom Ash Handling System-
The free falling ash from boiler furnace is collected and stored in a ‘VVV’ shaped water impounded bottom ash hopper provided below the boiler furnace for its periodic removal once in a shift of eight (8) hours per Unit. The hot ash from the furnace gets quenched as it enters into the water minimizing the clinker formation. The mixture of ash and water stored in the hopper is discharged through feed gate to clinker grinder to crush the oversize clinkers. The crushed clinker along with water (BAHP), which forms bottom ash slurry, is conveyed to Ash Slurry Sump through Hydro ejector (Jet pumps) for further transportation to Ash Disposal Pond through Ash Slurry disposal pumps. Water required for a Jet pump is supplied from bottom Ash high pressure (BAHP) water pumps located in Water pump house. Water seal trough arrangement is provided at the top of the bottom ash hopper for effective furnace seal and to prevent ingress of air into the furnace. A cooling trough arrangement is also provided at the top of the hopper. BALP Water supplied to the cooling trough will overflow continuously to provide continuous refractory cooling to enhance the life of refractory. Flushing header with nozzles provided at the end of bottom ash hopper sloping walls agitates and removes settled ash from the hopper.

Fly Ash Handling System-
Fly ash carried along with the flue gas from the furnace is collected continuously in APH, APH Duct and ESP Hoppers. There are total 108 ESP Hoppers, one Chimney Hopper, 8 APH Hoppers and 8 APH duct hoppers.

a) ESP Hoppers are placed in 3 Pass (AB, CD, and EF), 9 fields per pass, and each field having 4 nos. Hoppers, each hopper are connected to Ash conveyor vessels. Each field’s First vessel is provided with conveying air inlet valve and called master vessel (Except field 6 & 8) while rest of vessel called slave vessel. First four fields vessel are provided with one no electro - pneumatic operated Dome Valve, vent valve (for venting), pressure equalizing valve and wet system isolation valve, which segregates the hopper from dry and wet extraction of ash respectively. 5th, 7th and 9th field’s first vessel is provided with conveying air inlet valve. However in field 6th and 8th all vessel are slave vessel guided by master vessel of field 7th and 9threspectively. 5th to 9th Field’s vessel is provided with one no. electro - pneumatic operated Dome Valve.8 Diverter Valves/pass are provided for isolation of conveying lines between 2nd to 8th fields of each pass, finally 3 conveying lines/pass are provided for fed conveying fly ash from ESP Hoppers to 2 Nos. Intermediate Surge Hoppers.

b) APH & APH Duct Hoppers are placed in 2 Sets (A & B) each, having 4 nos. Hoppers per set, each hopper are connected to Ash conveyor vessels. Each Set’s First vessel is provided with conveying air inlet valve and called master vessel while rest of vessel called slave vessel. Each vessel is provided with one no electro - pneumatic operated Dome Valve, vent valve (for venting), pressure equalizing valve and wet system isolation valve which segregates the hopper from dry and wet extraction of ash respectively. 6 Diverter Valves are provided for isolation of conveying lines of each set and finally one common conveying line provided for fed conveying fly ash from APH & APH Duct Hoppers to 2 Nos. Intermediate Surge Hoppers (ISH). Air required for conveying of Ash from Hopper vessels is taken from Conveying Air Compressors (CAC). Fluidizing Air Blowers along with air heaters are provided to supply hot air for fluidizing the ash in ESP Hopper for effective conveying of fly ash.

Fly Ash Silo –
Mixture of transported Air and Ash conveyed from ISH Hoppers is discharged to any of six nos. Fly Ash Silo (FAS). On discharged into FAS, air gets separated from Ash and clean air is vented out in to atmosphere through vent filter provided on top of Silos. Each FAS is provided with four outlets. Two outlets are provided with pneumatic operated knife gate valve, rotary feeder and hydro mix dust conditioner (HMDC) to unload the dry ash in conditioned form into open truck for further transportation/disposal. Two outlets are provided with pneumatic operated knife gate valve, rotary feeder and Telescopic Chute to unload the dry ash into close truck for further transportation/disposal. Silo Aeration Blowers along with heaters are provided to assist in maintaining the fly ash in fluidized condition during unloading operation. Dust Conditioner water pumps are provided in the silo utility building to supply water to hydro mix dust conditioners.

Ash Water System –
HP & LP seal water pumps are provided to supply the water to Ash Slurry Pumps. BALP water pumps are provided to supply the water to Bottom Ash Area and Ash Slurry sump. BAHP water pumps are provided to supply the water to Bottom Ash Area, ISH area and Ash Slurry Sump. Recovery water Pumps, Recycle water pump and AHP Clarifier through Sludge Pumps are used to makeup water level of Ash water Sump.

Air System -
Conveying Air Compressors are provided to fulfill the requirement of conveying Fly ash from ESP/ APH Hoppers to Intermediate Surge Hoppers. Transport Air Compressors are provided to fulfill the requirement of transport Fly ash from Intermediate Surge Hoppers to Fly Ash Silos. Instrument Air Compressors (Main Plant Area & Silo Area) are provided to fulfill the requirement of Instrument air for pneumatic valves operation.

Benefits of Automation /Control system for various applications -

• Monitor & Control the entire system from control room.
• Live status from the field.
• Interface option to communicate with third-party devices using user-defined protocol.
• Enhanced redundancy features including fast switchover time, high-speed synchronization and dual ring topology option.
• Flexibility of network options (Fast Ethernet, Modbus ASCII/RTU/TCP)
• Variety of I/O modules including channel-to-channel isolation
• Robust diagnostics (system/error logs, system monitoring, network monitoring, ping test, frame monitor)
• Tight integration with Experian HS via dedicated protocol
• Integrated programming and engineering environment with Soft Master.