COMPANY
ADDRESS 1
ADDRESS 2
COUNTRY
For the attention of TITLE NAME SURNAME, POSITION
 
Dear Sir,
Budget Quotation for the Supply of a Cathode Block Preheating System
Our Ref: EA…..
 
Further to our recent communications, we are now pleased to submit our budget proposal for the supply of a new lift-off cover type Cathode Block Preheating System.
 
The system would be designed to heat up collector bars in a period of 100 minutes, whilst achieving a close temperature uniformity over the entire length of the steel bar at the end of the heat-up cycle, prior to casting. 
 
The operation of our system is based on the use of mesh type radiant plaque burners, which represent the state-of-the-art in surface combustion technology and are proven to release heat uniformly over a given surface, making them ideal for this type of application. These burners would be incorporated in a ceramic fibre lined fixed cover hood. This would maintain a relatively low cold face temperature of the cover hood backplate, and contain the heat under the cover to protect the combustion equipment mounted above. The cover hood would have a total of four individual cathode block preheating positions.
 
A set of four long, narrow, rectangular burners, laid out end-to-end to match the top surface of each bar, would transfer heat in infrared mode over the length of the bar. Due to the shape of the burners and the nature of the combustion, flame impingement onto the neighbouring carbon block would be avoided, thus keeping oxidation of the carbon to a minimum.
 
 
Hotwork Combustion Technology Ltd
Bretton Street, Savile Town, Dewsbury, West Yorkshire WF12 9DB, UK
Tel: +44 (0) 1924 506506, Fax: +44 (0) 1924 506311
E-mail: [email protected], Web: www.hotworkct.com
Co. Reg. No. 4386957, VAT Reg. No. GB 789581849

The system would be designed for reliability in operation, low maintenance, durability, ease of operation, energy efficiency and would incorporate all necessary items to comply with EN746-2 such as pressure proving, purge proving, automatic burner start-up and continuous flame supervision. After start-up, the burners will be set on a fixed rate and a timer with audible alarm and beacon will indicate the end of the heat-up cycle, at each preheating position.

A single atmosphere thermocouple, mounted in the flue at each preheating position, would be set to monitor 'over-temperature' of the particular preheat position. Should an over-temperature condition occur, the system would automatically 'shut down' that particular preheating position. 
 
As part of our scope of supply, we would also provide three bases to ensure that the cathode block assemblies are accurately located and horizontal during the preheating and casting operations. As explained, this arrangement would enable you to use one base for loading a set of four bar/block assemblies, one base for preheating another set and one base for casting and leaving another set to ‘rest’. This would allow you to cast twelve blocks during an 8-9 hour shift.
 
Hotwork CT have a wealth of experience in the design of combustion systems for the aluminium industry (reduction cell preheating systems, crucible preheating systems, melting furnace combustion systems) and we do hope that we will have the opportunity to work with you on this project.
 
We trust our proposal meets with your requirements. Please do not hesitate to contact us should you have any queries and we look forward to hearing from you in the near future.
 
Yours faithfully,
 
Denis Hunzinger
Sales and Marketing Manager
 
Photographs showing a Lift-off Cover Cathode Block Preheating System
to preheat 4-off cathode block assemblies illustrating the principal of operation.
 
TECHNICAL
 
1. General
 
Type of System:               Cathode Block Preheating System
 
Preheater Cover Hood                      
Dimensions:                                        Approx. 4500 mm long x 2700 mm wide x 3000 mm high. The hood will be of modular construction to facilitate site assembly, and mounted on four supporting legs.
     
Duty:                                                   To preheat steel collector bars from ambient to 550 ^oC in 100 minutes (max.), prior to casting the bars into the cathode blocks. NB: heat up times will vary depending on the ambient temperature at the time of preheating.
 
Temperature Uniformity:                    +/- 10 ^oC on the top surface of each bar (contained within the carbon block recess) at the end of the cycle.
Collector Bar and                             
Cathode Block Dimensions:              As per your Drawings No. ………………..
                                                                                                            
Bar and Block Configuration:             Four cathode block preheating positions. Collector bar in each cathode block recess to be positioned by overhead shop crane.
Cathode Block preheated side by side at 500mm centres. Height to top of Cathode Block to be agreed.
 
Production requirements:                  12-off cathode block assemblies per day
 
Proposed Burners:                              16-off mesh type radiant plaque burners, four per collector bar, each approx. 1000 mm long x 180 mm wide.
 
Rating per Collector Bar:                    150 kW (approx.)
 
Total Rating:                                        600 kW
 
Fuel type:                                            Natural gas available at 250 mb
 
Combustion Air Fan (also
includes air to drive flue
eductor & air curtain systems):          1,200 m³/h approx. at 65 mbar. Noise level: 85 dbA (max.) at 1 metre, with inlet filter
 
System exhaust:                                 Discharge directly into workshop.
 
Electrical Supply:                                380V +/- 20%, 3 Ph, 50 H_z (control: 110V.)
                                                                                   
All services to be available within 6 m of the preheater.

2. Scope of Supply
 
Our proposal includes for the supply of a Lift-off Cathode Block Preheating System as follows:
 
                a. A combustion system based on the use of 16-off mesh type radiant plaque burners to operate on natural gas.
 
                b. A control panel for the safe operation of the combustion system including flame programmers and heat-up cycle timers.
 
                c. A fabricated, fibre lined cover hood onto which part of the combustion equipment would be mounted.
 
                d. Design of the combustion system, the control panel and the hood including combustion schematic, electrical diagrams, general arrangement drawings, operating and maintenance manuals.
 
                e. Supply of three preheating bases
 
                f. Pre-testing and pre-commissioning of the system in our works
 
                g. Supply DDU PLANT LOCATION Incoterms 2000
 
                h. Supervision of site installation and site commissioning
 
                i. Supply of two sets of Operating and Maintenance Instructions on CD-ROM in English.
 
 
3. System Description
 
The system would consist of a fabricated lift-off cover hood of modular construction mounted on four legs. It would incorporate four sets of four mesh type radiant plaque burners. A set of burners will be located directly over each collector bar and radiate heat uniformly over the heating zone, effectively forming a long and narrow combustion channel with sides made of stack bonded ceramic fibre modules. The fibre would cover the top of the carbon blocks (with a small clearance gap), to protect the carbon from oxidation.
 
The burners have been sized to enable the collector bars to reach a temperature of 550 ^oC +/- 10 ^oC., in approx. 100 minutes of heating. They would operate in infrared mode for optimum heat transfer. Products of combustion would exit the hood through small flues (eductor air driven) at both ends of each ‘combustion channel’.
 
The combustion air fan would be mounted on top of the hood to feed air to the Preheating hood. The gas safety station would be located in an agreed position, to feed gas to the hood. The floor mounted control panel would contain the flame programmers, timers, with sirens and beacons to indicate the end of each heat-up cycle.
 

4. Combustion System
 
In order to achieve a uniform heat release over the entire length of the collector bars, as recommended by carbon block suppliers, we have chosen to use mesh type radiant plaque burners which would be fed with premix gas and operate in infrared mode for optimum heat transfer to the bars.
 
In order to heat up the length of each bar, four burners laid out end-to-end would be used. Each burner will be approx 1000 mm long x 180 mm wide and each group of four burners will have a total rating of approx. 150 kW. The cathode block preheater would have 16 burners with a total rating of 600 kW. The system would be fitted with automatic burner ignition and flame supervision by ionisation rod. The construction of the burners makes them very sturdy and resistant to both thermal and mechanical shock. As the mesh used for the burner has a low thermal mass, the burner starts radiating almost immediately after ignition.
 
The combustion system would be designed to comply with EN746-2 and will also include the following equipment:
Ÿ  A hood-mounted fan to supply approx. 1200 m³/h of combustion air at 65 mbar, an inlet silencer for 85 dBA (max.) at 1 metre and an inlet filter.
Ÿ  A three way air pressure switch test valve to check the presence of air.
Ÿ  An orifice plate with a pressure switch across it for purge proving.
Ÿ  A motorised air control valve with low fire pressure switch across it to start the combustion system at low fire.
Ÿ  Air limiting orifice valves
Ÿ  A main gas isolation valve
Ÿ  A gas filter
Ÿ  A gas pressure governor
Ÿ  A gas meter for totalised gas flow
Ÿ  High gas pressure and low gas pressure switches
Ÿ  A main gas safety shut-off solenoid valve
Ÿ  A 6m long steel braided gas flexible with a flex proving device to check the integrity of the flexible prior to ignition.
Ÿ  For each group of two burners (i.e. two groups per bar), a gas isolation valve, a safety shut-off valve, a ratio regulator and a mixer.
Ÿ  For each burner, a pre-mix limiting orifice valve to adjust burner rating.
 
 
5. Control System
 
The control system will consist of a free standing enclosure containing the combustion air fan contactor and motor protection unit, flame programmers, a panel transformer 380V to 110V and timers with associated beacons and alarm to indicate the end each preheat cycle.
Flexible cables would connect the preheating hood to the control panel.
 
6. Hood construction
 
The hood would be made of mild steel plate, strengthened and profiled to suit the particular burner heat flow pattern i.e. four long and narrow ‘combustion channels’ separated by fibre modules. Insulated flues at the end of each channel would allow the exhaust gases to flow out of the hood (these would be eductor air driven).
 
The combustion air equipment and fan would be mounted on top of the hood as would the burner gas components. The gas regulation/metering equipment from the main isolation valve to the gas flexible will be installed on the floor, between supply and hood.
 
The hood will be mounted on four supporting legs and, in order to help the crane operator to position the hood, two guiding tubes will be fitted in two opposing corners to be used in conjunction with two guiding posts on each base.
 
In terms of thermal insulation, we propose to use stack bonded anchored modules made of ceramic fibre material to protect the hood from the heat, form combustion channels as described in section 3, and protect the cathode blocks from oxidation.
 
 
6. Installation and commissioning
 
Our system would be designed in modular form for ease of assembly on site. It would be manufactured, pre-assembled, pre-tested and pre-commissioned in our works in order to minimise site time. We have estimated that mechanical and electrical site installation would be completed in 7 consecutive 12h days and commissioning would be completed in 4 consecutive 12h days including 1 day for trials. We propose that the system be installed by COMPANY fitters under the supervision of an HCT foreman. Please confirm that this arrangement is acceptable. Commissioning would be carried out by two HCT engineers.
 
Our budget price includes site time, travel time, travel costs, accommodation and expenses. Any extra time required for reasons beyond HCT’s control would be charged at £….../day for the site installation supervisor and £…...//day per commissioning engineer.
 
7. Exclusions
 
Ÿ  Building or foundation work.
Ÿ  Customs clearance, import duties and VAT
Ÿ  Offloading of equipment at site
Ÿ  Storage of equipment
Ÿ  Any extended heating trials
Ÿ  Automatic temperature control
Ÿ  Temperature recorder
Ÿ  Preheater hood lifting equipment
Ÿ  Any services more than 6 m away
Ÿ  Site cranage
Ÿ  Scaffolding on site
Ÿ  Any mechanical/electrical installation other than supervision
Ÿ  Electrical site wiring
Ÿ  Interpreter during site installation and commissioning
Ÿ  Any document or formalities that may be required to import the goods into COUNTRY or use the goods in COUNTRY (although we would provide reasonable assistance to COMPANY to obtain the necessary permits, if required).
Ÿ  Any major items or services not specified.

COMMERCIAL
 
 
1. Price
 
Our budget price for the design, manufacture, shop testing, supply, supervision of installation and commissioning of a Lift-off Cathode Block Preheating System, generally as described herein, is:
 
£………….. DDU PLANT LOCATION Incoterms 2000
(………………………… Pounds Sterling)
 
2. Delivery
 
·         4-6 weeks from receipt of downpayment to submission of drawings for COMPANY’s approval (schematic diagram and arrangement drawings).
·         12-14 weeks from acceptance of drawings by COMPANY to the supply of the system on DDU PLANT LOCATION basis
 
3. Terms of Payment
 
To be agreed but we suggest:

• Thirty percent (30%) downpayment with order against a bank guarantee.
• Seventy percent (70%) against a Confirmed Irrevocable Letter of Credit drawn at sight on a first class European bank.

 
4. Taxes and duties
 
The above prices are exclusive of all taxes and duties.
 
5. Validity
 
This is a budget proposal and as such is not open for acceptance.
 
6. Confidentiality
 
The contents of this quotation are Strictly Confidential and should not be discussed with or communicated to a Third party.
 
7. Customer care / Quality assurance
 
In order to improve continuously the service that we offer our customers,        Hotwork CT 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.

8. Acceptance
 
On turnkey multi-disciplined projects, we recognise the need for a defined end point to contract. With this in mind, Hotwork 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 temperature uniformity, fuel usage, production levels and delivery programme benchmarks. The Acceptance/Hand-over procedure will benefit Hotwork and its 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.
 
9. Warranty
 
Our proposal includes for a 12-month defects liability period from date of commissioning or 15 months from delivery whichever is the shortest period. However, our liability will be limited to defects due only to fair wear and tear of items of our supply and to HCT workmanship and design. The equipment should also be correctly maintained during the warranty period. Our liability shall not extend to the failure of the following items which, by their nature, should be considered as consumables:
Ÿ  Ignitors
Ÿ  Ionisation probes
Ÿ  Instrument fuses
Ÿ  Solenoids
Ÿ  Regulator springs and diaphragms.
 
10. Conditions of Sale
 
HCT Standard Conditions of Sale apply.
 
For HOTWORK COMBUSTION TECHNOLOGY LIMITED
 
D. P. Robinson
Managing Director

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