Electricity and Control March 2016

HAZARDOUS AREAS + SAFETY

AHF

– Anhydrous Hydrogen Fluoride (AHF)

HAZOP – Hazard and Operability Study HF – Hydrogen Fluoride IBC – Intermediate Bulk Container PFD – Process Flow Diagram P ID – Piping & Instrumentation Diagram SIS – Safety Instrumented System

Abbreviations/Acronyms

‘non-issue’ items raised during the review, but not include these items in the information incorporated into operator training and plant operational manuals.

Case Study - Metal fluoride salts plant A pilot scale facility was designed for the production of a transition metal fluoride salt within the boundaries of a larger production complex. When designed, the plant consisted of a raw material stor- age area, a solution make-up area, the salt production area, product handling area and final product storage. However the requiredmarket for the metal fluoride salt product that the plant was designed for was never secured, and the facility was subsequently mothballed. Subsequent to the mothballing, some of the equipment installed on this plant has been removed for utilisation in other processes in the larger production complex. This mothballed facility has been earmarked to be utilised for metal fluoride salts production by BFluor (a different metal fluo- ride salt than it was originally designed for). In order to utilise this pilot plant for this product, the plant must be de-mothballed and refurbished, as well as a redesign with relation to some portions of the facility. Due to the deviation from the original design intent of the process, several constraints are imposed by the current design with relation to the new process. Significant retrofitting and process modifications are therefore required to ensure that the facility is able to meet the BFluor process’ intent. Brief process description Raw materials for the production of the metal fluoride salt include: metal oxide, Anhydrous Hydrogen Fluoride (AHF), water and a base solution. The metal oxide powder is stored in a storage hopper in the raw materials storage area. The AHF is stored in a 100 m 3 tank with 20% freeboard. The demineralised (‘demin’) water is supplied from the water supply pipeline. The base is a powder (used to make up the base solution) stored in a storage hopper. The first stage of the process is the make-up of the solutions required in the process, a 70% HF solution and a 20% base solution. The HF dilution occurs in the HF dilution tank (a polypropylene tank) while the base solution make-up is done in two separate make-up tanks (polypropylene tanks). The metal fluoride salt reaction occurs in two vessels. In the first, the metal oxide powder is dissolved into the 70% HF to produce a metal fluoride acid. This in turn is reacted with the base solution in the next reaction vessel to form the metal fluoride salt. Subsequent

Figure 1: Typical HAZOP Methodology as adapted from IEC-61882.

Figure 2: High level block flow diagram.

March ‘16 Electricity+Control

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