1.                 PROCESS PARAMETERS 

 
 
Plant:                                       One Vertical Pig Iron Ladle Dryer / Preheating Station


 
Ladle Capacity:        4.5 tonnes
                               
 
Ladle Dimensions:          Diameter – 1375mm
                                Height – 1830mm

              Operation:                  Drying
Ambient – 1100^oC in 30 hours
                               
Preheating
                                Ambient – 1100^oC in 4 hours
                                600^oC – 1100^oC in 0.5 hours



Proposed Burners:          One Hotwork HV400 High Velocity Gas Burner                                 rated at 586 kW stoichiometric basis
                                              
 
Main Fuel:                                    Natural Gas available at 2 bar at takeover point.
GCV 8760 kcal/Nm³
 
 
Electrical:                               Supply          380V - 3ph - 60H_z, 
Controls      110V - 1ph - 50H_z
(to be confirmed)

 

2.                 SCOPE OF SUPPLY

Supply & Packing of the following:


o   A combustion system based on a single Hotwork HV400 Natural Gas Burner complete with combustion air fan, gas and air control system.
o   Totalising turbine type gas flow meter with pulsed output.
o   Refractory fibre lined heat shield
o   Steel jib arm & central support column with base plate.
o   Supply of a pre-tested temperature control and burner management panel.
o   Electrically actuated screwjack to raise and lower the lid.
 
Design services including:
 
o   Detailed combustion schematic and equipment list
o   General arrangement drawing
o   Floor loadings
o   Control panel layout and wiring diagrams
o   Operating and maintenance manuals on CD ROM in English
 
Supervision of installation and commissioning of the supplied equipment during one visit to your plant.
 
On-site training of personnel during the commissioning phase.

 

3.                 HEAT SHIELD

The cover will be designed to completely cover the specified ladle and will be approximately the same size as the ladle rim in diameter. It will be fabricated in suitably sized mild steel plate and sections, suitably stiffened with radial webs and flanges. 
 
The burner will be mounted on the heat shield in a fabricated metal housing, to fire vertically downwards along the central axis of the ladle.
 
The heat shield will be lined with stack-bonded Non-RCF ceramic fibre blocks retained by stainless steel anchors, suitable for operation up to temperatures of 1100°C. This type of fibre is particularly well suited to this application due to its lightweight construction, thermal performance and reliability.
 
The exhaust gases will escape to atmosphere via an annular gap between the heat shield cover and the vessel rim. It is important to size and maintain this gap correctly as inefficiency can result from incorrect flueing area.

 

4.                 SUPPORT STRUCTURE & MOVEMENT MECHANISM

The ladle heat shield/cover will be suspended from a mild steel jib arm, designed for movement in the vertical plane. The jib arm will be supported from the central support column through bearings and will have the capacity to be manually slewed about the central support column.


The raise and lower function of the heat shield lid will be undertaken by an inverter controlled electrically actuated screw jack. This will enable the heat shield/cover to be raised and lowered by approximately 700mm.
        
The station will be supplied with a drilled floor mounting plate which would allow the unit to be bolted as one complete module to your prepared foundations.
 
We have excluded the supply of the ladle locating base and guides (design included), floor fixing bolts and any civil work.
 
The support frame base and locating guides would accurately locate the ladles under the station which is important for the overall efficiency of the system. 
 
 

5.                 COMBUSTION EQUIPMENT

The system would be designed to comply with European Standard EN746 Industrial Thermoprocessing equipment, Part 2 and will include the following main items:
 
·         A combustion air fan, on the outlet of which will be a three-way air pressure test valve to prove the air pressure switch in the 'no pressure' state, this being required to permit start-up of the system.
 
·         A motorised air control valve with low fire proving differential pressure switch.
 
·         A combustion air orifice plate with purge proving differential pressure switch.
 
·         One Hotwork HV400 High Velocity Ceramic Burner complete with quarl, sight glass and igniter.  Flexible nipples would be provided to offset vibration.
 
·         Burner gas components mounted on the station consisting of an isolation valve, one safety shut-off valve and an air/gas ratio regulator.
 
·         A main gas train consisting of manual isolation valve, filter, gas pressure governor with overpressure protection, pressure switches, main safety shut-off valve and weep/vent solenoids supplied on a support bracket mounted off the system.
 
·         A pilot train comprising gas pressure regulator, two gas safety shut off valves and two gas isolation valves.
 
·         An auxiliary air supply taken from the main combustion air supply to provide cooling air to the flame scanner.
 
·         To allow the station to lift and slew, a 4mtr long gas flexible hose.
 
·         To allow monitoring of energy use on the station, a totalising turbine type gas flow meter with pulsed output to communicate with the plant data logging system.
 
·         Impulse lines from the controlled combustion air supply to the air/gas ratio regulator to ensure correct air/gas ratio throughout the burner range, together with a motorised impulse bleed valve to provide the option of fuel  only control (excess air facility) at lower operating temperatures. 
 
During the drying process in order to control low temperatures and to remove moisture and volatiles from new refractories, the system will operate with full combustion air flow with the thermal rate being varied by increasing or decreasing the flow of gas to the burners.

During preheating the system will fire on ratio with both the air and gas flow varying as required to increase or decrease the thermal output.


 
BURNER SPECIFICATION
 

Description	Data
Maximum Thermal Rating (kW)	586
Air Pressure at burner, mb cold at 20 oC	30
Gas Pressure at burner, mb	22
Maximum Turndown Stoichiometric	10 : 1

NB - This information is for guidance only
 
 
 
PROVISIONAL FAN SPECIFICATION 
 
The combustion air fan will have a noise levels of less than 85 dB(A) @ 1m.

Description	Volume m3a/h	Pressure mb	Temp oC
Combustion Air Fan	730	70 pressure	20

 
 
 
 
 
Note: Noise levels of fans will be assessed at 1m from the fan(s) if they are free standing or otherwise measured at 1m outside of any acoustic housing installed for the purpose of reducing environmental noise. Combustion generated noise measured as ‘breakout’ noise from poor door seals or uncontrolled furnace openings is excluded.
 

6.                 ELECTRICAL

A control system will be provided for the purpose of initiating and monitoring the safe start-up and operation of the ladle station and secondly to control the operating parameters to ensure optimum performance.
 
To achieve this, we propose a single control panel for the system which would be mounted adjacent to the station and would house the necessary equipment for system light up, operation and shutdown. This equipment will generally comprise:


·         Enclosure
·         Door interlocked 3 phase mains isolator
·         Combustion air starter and motor protection unit
·         Screwjack inverter
·         Step down control transformer
·         Eurotherm Temperature programmer - 10 programmes each with 16 segments.
·         Eurotherm Over temperature policeman
·         Alarm sirens, and beacons
·         Interface and control relays
·         Emergency stop relay, indicator lamps and buttons
·         Honeywell flame programmer and UV scanners
The panel would be designed, built and functionally tested in our works prior to despatch.
 
       Functional Description
 
The system temperature control will be undertaken by the temperature programmer running a temperature program profile to cover the process temperature ramps and holds. It would sense the vessel atmosphere and generate the appropriate signals to be sent to the control valves.
 
The system will be designed to provide the following functions.
 
§    System Start-Up
·     Air fan running
·     System air pressure healthy
·     System gas pressure healthy
·     purge completed
·     pipework (flexible) proving healthy
      
 
The Kromschroder burner safe start system will:
 
§    Drive the combustion air control valve to the purge position and purge the ladle with an air flow for five continuous volumes ensuring that there are no combustible gases present on light-up.
 
§    Drive the combustion air control valve to low fire and prove this condition prior to energising the pilot safety shut off valves and igniting the pilot flame.
§    Light the burner main flame and establish automatic temperature control.
 
§    Control the flow of air and gas in response to demands from the temperature in the ladle.
 
§    To ensure that on failure of the prescribed start permissives, the control system would go to lockout. An audible alarm would sound and a flashing beacon would light to draw attention to the fault.
 
§    Cause the automatic controlled shutdown of the system in the event of excessive fluctuations in gas or air pressures, excessive temperatures or loss of flame.
 
To protect the ladle refractories, lid and combustion system from excessive heat, an over temperature controller is included to shut the system down if a predetermined temperature setpoint is exceeded.
 
A gas safety system will be provided which will ensure that gas is only allowed to the burner after the ladle has been purged and the flexible have been checked for leakage. This is achieved by a series of bypasses and vents, which allow the system to be pressurised and checked for leaks. 
 
 

7.                 PREFABRICATION

In order to optimise the site installation time, the following would be pre-assembled to our detailed design at our Dewsbury workshops before being part dismantled into suitable sub-assemblies prior to their packing ready for collection:


·         main gas control train mounted on a support frame
·         air control train
·         heat shield
·         burner
·         jib arm
·         central support column
·         electrical control panel

 

8.                 SUPERVISION OF INSTALLATION & COMMISSIONING

The equipment in the scope of the supply will be installed by local labour who will assemble the station on prepared foundations under the supervision of an HCT engineer.


On completion of the installation phase, we will commission the combustion and control systems to the point of heating ladles. During this period, we will instruct your operators/maintenance personnel in the correct operation and maintenance procedures.
 
The installation and commissioning phase is scheduled to take 5 consecutive days to complete based on 10 hour shifts. Any additional time that may be required for reasons beyond HCT’s control would be charged extra.
 
Our price at this stage excludes travel time, travel costs, hotel and subsistence expenses.
 
 

9.                 DESIGN

An engineering package will be provided for the design of the station and will include the following drawings:


·         Detailed combustion schematic
·         Detailed bill of materials
·         General arrangement drawing
·         Floor loadings
·         Ladle base and locating guides
·         Control panel layout and wiring diagrams
·         Operating and Maintenance Manuals on CD ROM in English
 
HCT currently operates Auto-Cad Release 2011 on which the necessary drawings will be produced.  Drawings can also be converted to IGES or DXF format for translation to other CAD systems. 
 
The drawings and manuals would be provided in the English language and would be supplied in duplicate on CD ROM.

 

10.            HOTWORK DRYING AND PRE-HEATING SYSTEMS

The Hotwork CT Vessel Drying and Preheating System is now used in over two hundred separate installations at major steelmaking and aluminium plants throughout the world. The process offers significant benefits in terms of combustion efficiency, temperature uniformity and control of temperature.
 
The most efficient transfer of heat to the vessel lining is achieved during drying and preheating by utilising the products of combustion at high velocity and under pressure. Consequently, our proposal incorporates a high velocity burner firing into the vessel enclosure. The use of forced convection maximises heat transfer by breaking down the boundary layer of still air adjacent to the surface to be heated.
               
In drying applications, moisture and volatiles are rapidly removed from the refractory lining. The system will be designed to use high levels of excess air during the drying process, to ensure the efficient removal of water vapour and volatiles from the refractories and also to enable better control of temperature, particularly early in the process at low temperature.
 
Temperature uniformity over the complete lining surface is also improved, reducing hot spots and so virtually eliminating cracking or spalling of the linings, resulting in increased refractory life.
 

11.            EXCLUSIONS

· Any civil works including supply of ladle guides/locating base/mounting bolts
· Any spares
· Any engineering site visits
· Dual fuel operation
· Any venting of valves to atmosphere
· Any site installation labour and materials except for supervision
· Travel time, travel costs and local expenses
· Refractory dryout and heating/performance trials
· Delivery
· Taxes or duties
· Bank holiday or shift working
· Process thermocouples
· Any third party certification
· Any equipment or services not mentioned above


 

12.            SERVICES BY THE CLIENT

· Main incoming supply to the panel
· Fuel for commissioning and testing
· Site installation of equipment (material and labour)
· Scaffolding/Craneage
· Electrical power
· Staff for commissioning assistance
· Use of telephone and fax/email facilities
· Use of site cabin and mess facilities
· Secure storage area

13.            WARRANTIES

The equipment would be warranted for operation for 12 months from Acceptance or 18 months from Delivery, whichever is the earlier, with the exception of the following items which are considered as consumable and therefore are not eligible for warranty:
 
o   Flame detectors
o   Thermocouples
o   Filters
o   Fuses, lamps and pushbuttons  
o   Solenoids, regulator springs and diaphragms

 
COMMERCIAL
 

1.    BUDGET PRICE

For the design, supply packed Ex Works, supervision of installation and commissioning of a HV400 pig iron drying and preheating system, generally as described herein, our budget price is:
 
Site Rates:
·           Supervision & Commissioning: €850.00 per 10 hour man day or part thereof.
 

2.    DELIVERY

We would expect the equipment to be ready for delivered Ex Works in 14-16 weeks from receipt of down payment.   
 

3.    VALIDITY

  This is a budget proposal and as such is not open for acceptance.
 

4.    TAXES AND DUTIES

       To be charged extra as appropriate.
 

5.    TERMS OF PAYMENT

To be agreed but we propose the following:
 
·         50% of the contract price to be invoiced with acknowledgement of order, to be settled immediately on receipt of invoice.
·         45% of the contract price to be invoiced on readiness to deliver, to be settled immediately on receipt of invoice.
·         5% of the contract price to be invoiced on completion of commissioning, 30 days.
             

6.    TERMS AND CONDITIONS OF SALE

       HCT terms and conditions of business apply, a copy available on request.
 

7.    CONFIDENTIALITY

Any information, know-how or date contained in this specification is strictly confidential and is not to be divulged to a third party.
 

 

8.    CUSTOMER CARE

In order to improve continuously the service that we offer our customers, HCT operate a customer care policy.  Through a centralised point within the company, your concerns and queries regarding the service you receive will be dealt with objectively and independently.  Please contact the office of David Robinson, Managing Director if a situation arises that you feel requires this sort of attention.
 
 

9.    ACCEPTANCE

On turnkey multi-disciplined projects, we recognise the need for a defined end point to contract.  With this in mind, HCT operate an Acceptance process where measurable parameters are set out, by mutual agreement, to be confirmed during the closing stages of the project.
 
Typical examples of these parameters are fuel usage, production levels and delivery programme benchmarks.  The Acceptance/Hand-over procedure will benefit HCT and it’s customers in the elimination of 'grey areas' and uncertainty.  This will usually take the form of nominated representatives from both parties "signing off" completed work and agreeing any changes or modifications to the original scope.
 
The specific detail of the Acceptance criteria would be covered during the quotation or post order discussion stages.

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