Proposed Revision of the Safety Management Process Safety with Emphasis on the Functional Safety of the Ammonia Plant in Monomeros Colombo Venezolanos SA

 INTRODUCTION

Monomers Colombo Venezuelan SA, is a company dedicated to the manufacture and distribution of fertilizer, animal nutrition and basic chemicals industry, has within its scheme operations Plant receiving, storage and consumption of NH3 Anhydrous Ammonia (also known as Plant 14).

The plant operates with a normal inventory of 5000 Ton, contained in two tanks of 20 m3 each and a compression system to keep liquid ammonia at -34 ° C and 300 mm of H2O. Additionally, there is a transport system where consumers sends ammonia at 15 ° C and 20 kg/cm2 through pumps and heat exchangers special.

The Plant control is exercised by a Distributed Control System for Basic Process Control System in maintaining process variables and Programmable Electronic systems for the plant protection, even internally recognized as Interlocks.  

In the field of Process Safety, the plant has been part of Quantitative Risk studies and has a Hazop developed in 2007, operations manual and procedures, P & ID and Logic Diagrams updated for the year 2013.

 1. PROPOSED WORK

1.1. Review and update of Hazop Ammonia Plant.

Evaluate the application of Hazop methodology to the Plant, in order to check if they are covered, all possible risk scenarios. The result should lead to a HAZOP report with hazard scenarios described in full, with causes initiators and loss events well defined, protections or "Safeguards" identified and installed independent and those recommended as a result of the review, in a such way that serve as input for the development of a Layer of Protection Analysis (LOPA) for high and medium risk hazard scenarios.

1.2. Developing the LOPA.

Execute the LOPA to the scenarios of high and medium risk selected from the Hazop. The result of the LOPA will guide the identification of the relevance of the current Independent Protection Layers (IPL) installed on the plant versus acceptable risk criteria established by monomers and the current context of operation thereof. The IPL's, including the safety instrumented functions (SIF), which are recommended in the HAZOP as a result of the review, will receive the same treatment if the risk assessment of the hazard scenario to which they were defined meets the high or medium risk criteria.

1.3. Safety integrity Level (SIL) specification and documentation of the safety requirement specifications (SRS) of the SIF from the Safety Instrumented System of Plant 14.

Given the HAZOP, the LOPA, and safety information available to the plant processes 14, will proceed to make the allocation of the intregruty levels of all the SIF installed and recommended. Also, it will be documented as indicated by the standard, the specifications of security requirements of each. Those that were recommended, should be designed from the standpoint of hardware. In software design will be treated according to the guidelines of the engineers of instrumentation and control of Monomeros.

1.4. Validation of the safety instrumented system currently installed at Plant 14.

This stage is to carry out this phase of the life cycle for functional safety at Plant 14. Basically allows to see if what is installed, complies with the security requirements defined for each SIF defined for each SIF that is based on the hazard scenario to protect and his level of risk.

2. RESULTS

The overall result of the work is a report detailing the strengths and weaknesses of the  Functional Safety of the Ammonia Plant. It clarifies that are only applied some life cycle phases for functional safety in light of the IEC-61511.