The main chemical products produced at the Octel site are listed below.
Bromine for customers is stored in five on site stock tanks. The material in No4 stock tank is normally used to supply the HBr plant. One other stock tank, usually No5, is used to store bromine which has been returned from the HBr plant or other customers , prior to it being reprocessed via the steaming out tower.
All bromine for customers must meet our product specification of less than 30 ppm moisture. In addition some customers require special analysis. This is normally indicated on the weekly sales sheet. It is normal for this Bromine to be packed the night before and a sample taken so that it is available for lab analysis first thing in the morning.
Bromine loading during normal hours is a Day Services responsibility. Each shift have a number of trained bromine loaders who load bromine at weekends and during the evening. Current union / management agreements allow for one bromine to be loaded per shift. (One DBE can also be loaded on the same shift. Alternately two DBEs can be loaded.)
A Bromine loading sheet must be filled by the SPM before the loader starts work. This gives information on the amount of bromine to be loaded and gives a check on the expected and actual empty tanker tare weights. This is important to avoid overfill of a tanker which may have returned with a significant heel of bromine in it. The SPM should also check the capacity of the tanker from the plant attached to the side of the tank.
It is important that the data on actual and expected tare weights are obtained from the gate man. Any discrepancy greater than 340kg must be carefully considered. If necessary the contents of the tanker should be blown back to a “waste” stock tank and the tanker reweighed.
Before any tanker is loaded it is essential that it’s capacity is checked from the plate on the tanker. The actual capacity should be checked against the advised required fill weight before the operator is authorised to fill the tank. The minimum and maximum weights should also be entered on to the sheet. These are shown below:
- Target weight 17.7 te. Min 17.3 te. Max 18.0 te. Required capacity 6250 litres
- Target weight 18 te. Min 17.6 te. Max 18.5 te. Required capacity 6400 litres
- Target weight 14 te. Min 13.8 te. Max 14.5 te. Required capacity 5000 litres
- Target weight 7.5 te. Min 13.8 te. Max 14.5 te. Required capacity 2600 litres
The minimum weight is 88% of the tank capacity and is to prevent instability due to excessive movement of the dense liquor inside the tanker. The maximum capacity is 92% which is based on an allowance for expansion of the material in hot climates.
Once the tanker has been filled by the operator the securing of the blanks and valves must be checked by the SPM before the dome is closed. For bromine tankers going to Tiejen the dome closure must be secured with a lead seal.
From time to time trailers are left at the loading bay for overnight loading without the tractor being coupled. In this case an approved independent third wheel jack must be put in position to support the tanker until the tractor is re-coupled .Before the tanker leaves site it must be weighed to ensure that the correct amount of bromine has been filled into the tanker. The net weight of the tanker must be between the maximum and minimum limits indicated on the sheet. Too full a tanker could result in lack of ullage space in hot weather. Too little in the tanker can lead to poor stability of the tanker due to the movement of the dense liquid during transport. In addition the maximum gross weight for the tanker must not be exceeded. This is normally 38 Tonnes. However road tanker which are going straight to a port for transport into Europe can have a maximum gross weight of up to 40 tonnes. The gate man is responsible for ensuring that the correct paper work is sent off site with the tanker.
Bromine can also be loaded into small lead or PVDF lined “Pots”. The pots contain between 300 and 500 kg of bromine and are loaded in a dedicated PLC controlled loading station. The pots are moved by fork lift truck.
The cost of production of crude bromine at the BOTs is very dependent on sea water flow. The extraction efficiency in the winter months is lower. The biggest variable cost for Bromine production is the power usage’s of the pump and fans in the BOT. The concept of “last drop cost” of bromine has been developed. This is automatically calculated and displayed on the BOT DCS screens. The last drop cost is the calculated cost of producing one extra tonne of bromine at the prevailing extraction efficiency. This must be kept below the current average selling cost of bromine for us to remain economically viable. During the Winter months this is achieved by restricting the Sea water flow to the BOT and therefore reducing pumping costs.
DBE is stored in three large stock tanks. Each stock tank must be sampled before discharging to road tankers. It is normal for a tank to be filled to around 220Te , sampled and then used exclusively for that day’s loading schedule. Product made during this time is filled into other tanks. Each stock tank contains a top layer of soda ash and a minimum level of 30 tonnes should be observed during tanker loading.
DBE loading during the week is normally a Day Services responsibility. Each shift have a number of trained DBE loaders these load DBE at weekend and during the evening. Current union / management agreements allow for two DBEs to be loaded per shift. (Or one DBE and one bromine tanker)
Any issue with the gaseous nitrogen supply or with the stock tank padding system will require DBE loading to stop. Some of the DBE tanker are composite barrel vehicles. Caustic solutions can be carried to Amlwch in the centre compartment and DBE to customers in the outer compartments.
Most DBE is loaded into Road tankers for delivery to Octel at Ellesmere Port or to the storage system at GATX on the Wirral. These tankers are loaded with 21 tonnes. One customer, Agrevo, will only accept DBE tankers with a maximum of 18 tonnes net weight. To ensure that this maximum load limit is not exceeded DBE tankers are weighed at the gate house. The Gateman must then inform the Day Services Supervisor or SPM of the tanker destination and net weight before the tanker is authorised to leave. Previously most DBE was loaded to rail tankers.
HBr acid is made as both 48 and 62% strength. The 48% HBr is loaded into plastic drums. The drums are palletised and plastic wrapped. The 48% acid can also be loaded into plastic lined Intermediate Bulk Containers (IBC). These contain around 1.5 tonnes of acid. The Final stock tank must be circulated and sampled prior to container filling.The 62% HBr is loaded into plastic lined steel drums. All of these containers are loaded on a dedicated facility. Both 48% and 62% acid can also be loaded into bulk road tanker containers. Most of the HBr product loading is carried out by Day Services section.
Anhydrous HBr liquid is filled into various gas cylinders containing around 70kg of HBr. The filled cylinders are stored in a special transportable rack which contains 11 cylinders. For movement by road the cylinders are always transported in the rack. A larger drum containing between 700 and 1000 kg of material is also available. All Liquid HBr containers are filled on a PLC controlled dedicated filling system.
Both DBM and BCM are filled into high density polythene lined steel drums on a dedicated facility. The drums are palletised and plastic wrapped. Material can also be transferred from the bulk stock tanks to a road container.
MPBF products can be dispatched in either drums of road tankers. Drums containing various amounts of product are loaded in a dedicated drum loading facility. The drums are palletised and plastic wrapped. Special instructions will depend on the product being made. The MPBF operators regularly drum product from their process.It is also possible for MPBF products to be loaded into bulk road tankers using the dedicated bulk loading system.