Risk Assessment Associated with the Failure of the Safety Instrumented Function of the Reactor of Methanation (I-6 / I-351) on the Ammonia Plant (station II) from Nitrogenous Fertilizer, Fertinitro CEC, Located in Venezuela, Using the Simulaton Packagde P

SEDE CORPORATIVA

GERENCIA CORPORATIVA DE SEGURIDAD, HIGIENE Y AMBIENTE

INGENIERIA DE RIESGOS

ABSTRACT FOR THE 6TH CCPS LATIN AMERICAN CONFERENCE ON PROCESS SAFETY

Risk assessment associated with the failure of the safety instrumented function of the reactor of methanation (I-6 / I-351) on the Ammonia plant (station II) from Nitrogenous Fertilizer, Fertinitro CEC, located in Venezuela, using the simulaton packagde PHAST RISK 6.7

Based on the premise of "Only that which is known can be controlled," we must apply methodologies to identify dangerous situations, analyze and assess the associated risk. This is the approach of this study: analysis of the risks associated with an installation of the petrochemical industry in the handling of hazardous materials; ie evaluating the frequency of occurrence of an event and its effects or consequences (the probability and possibility is immersed in the evaluation) .

Technological development in industrialized countries as Venezuela has been accompanied by a marked improvement in their standard of living. However, the proliferation of industrial facilities has also led to the appearance of new risks such as the petrochemical industry. That is reason in this paper a risk assessment will be performed Fertilizer Company, Fertinitro CEC

FertiNitro C.E.C is in Venezuela. It is a petrochemical company dedicated to the production and sale of anhydrous ammonia and granulated urea high quality, located within the Oil and Petrochemical Complex General Jose Antonio Anzoátegui. Throughout the value chain Fertinitro, ammonia and urea are produced due to the transformation of raw materials such as natural gas (which comes from the gas extraction plant of PDVSA) and the atmospheric air. Fertinitro is formed by two identical trains, which in turn are cut by two facilities of anhydrous ammonia; the maximum production capacity is 1,800 tons per day each, and two facilities of granulated urea, with maximum production capacity of 2,200 tons per day each.

The Ammonia plant is divided into several stages (Desulfuration, Reformation, Conversion of Carbon Monoxide, Carbon Dioxide Removal, Methanation, Synthesis Gas Compression, and Synthesis of Ammonia Refrigeration). In the Methanation´s stage, the reactor of methanation also known as methanator (12/22-R-301 ), wherein the process gas comes from the stages of conversion of carbon monoxide and carbon dioxide removal, is introduced Carbon respectively (rich in hydrogen and Nitrogen with small traces of carbon monoxide and carbon dioxide ).

Considering that the presence of Carbon Monoxide (CO) and Carbon Dioxide (CO2) into the reactor 12/22-R-501 (located downstream of methanation section) cause adverse effects to the design intent of the inside thereof, the catalyst content in the methanator promotes a exotherm reaction, converting the traces of CO and CO2 to methane (CH4) . The resulting of process gas within the methanation section, contains mainly Hydrogen (H2), nitrogen (N2) with trace amounts of methane (CH4) and argon (Ar), the latter two inert in the ammonia synthesis section .

The inlet temperature to the methanation reactor is controlled by the Temperature Indicator Controller 12/22-TIC-3353 , which in divided range, first checks the " bypass " exchanger associated gas / gas 12/22-E-311 A/B generating the opening of the temperature control valve and if necessary 12/22-TV-3353A further heating, the temperature controller 12/22-TIC-3353 sends an opening signal to the valve 12/22 -TV- 3353B, and thereby increases the amount of gas converted passing through heater 12/22-E-211 of the methanation reactor .

Moreover, the temperatures in the catalyst bed are measured at four different levels in order to monitor the temperature profile. If there is the entry of CO and / or CO2 in the methanator, due to poor operation of the conversion section of CO and / or section Removal of CO2, the temperature rise through the methanator be so high that may exceed the design temperature of the methanator. To prevent such an incident has been installed in the catalyst bed high temperature switch to trigger the security group of methanator interlocks (I-351 / I-6)

In this sense, motivated operating conditions and hazardous materials handled in the section of methanation, the equipment is considered high risk, so the Risk Assessment related to the failure of the instrumented function safety methanator be held (I-6 / I -351  on the Ammonia plant (station II ) of Fertinitro C.E.C, using the simulation package PHAST RISK 6.7 .