EP-4741344-A1 - PROCESS FOR PRODUCING A GASEOUS AMMONIA FUEL FOR A FIRED EQUIPMENT

EP4741344A1EP 4741344 A1EP4741344 A1EP 4741344A1EP-4741344-A1

Abstract

The invention relates to a process for producing, from a liquid feed stream (2) comprising ammonia, a gaseous ammonia fuel (3) for a fired equipment (4), said process comprising the following steps: - providing said liquid feed stream (2) to a fuel vaporizer (5) to produce said gaseous ammonia fuel (3), said gaseous ammonia fuel (3) being at a nominal pressure p0 in the fuel vaporizer (5); - directing the gaseous ammonia fuel (3) to the fired equipment (4) for performing a combustion of the gaseous ammonia fuel (3); and - when a variation in a demand in said gaseous ammonia fuel (3) occurs, maintaining the pressure of the gaseous ammonia fuel (3) in the fuel vaporizer (5) at the nominal pressure p0.

Inventors

LUTZ, MICHAEL
SIKORSKI, ROBERT
Borgosz, Malgorzata
VICARI, Lorenzo
Olszynska, Sara
ULBER, DIETER

Assignees

L'AIR LIQUIDE, SOCIETE ANONYME POUR L'ETUDE ET L'EXPLOITATION DES PROCEDES GEORGES CLAUDE

Dates

Publication Date: 20260513
Application Date: 20241112

Claims (14)

A process for producing, from a liquid feed stream (2) comprising ammonia, a gaseous ammonia fuel (3) for a fired equipment (4), said process comprising the following steps: - providing said liquid feed stream (2) to a fuel vaporizer (5) to produce said gaseous ammonia fuel (3), said gaseous ammonia fuel (3) being at a nominal pressure p0 in the fuel vaporizer (5); - directing the gaseous ammonia fuel (3) to the fired equipment (4) for performing a combustion of the gaseous ammonia fuel (3); and - when a variation in a demand in said gaseous ammonia fuel (3) occurs, maintaining the pressure of the gaseous ammonia fuel (3) in the fuel vaporizer (5) at the nominal pressure p0.
The process according to the preceding claim, wherein maintaining the pressure of the gaseous ammonia fuel (3) in the fuel vaporizer (5) at the nominal pressure p0 comprises the step of adjusting the heat provided to the liquid ammonia (19) in the fuel vaporizer (5).
The process according to any one of the preceding claims, wherein adjusting the heat provided to the fuel vaporizer (5) is made by controlling the flow rate of a heating medium (8) to a heat exchanger (7) in the fuel vaporizer (5).
The process according to any one of the preceding claims, wherein adjusting a heat provided to the fuel vaporizer (5) is made by controlling a temperature of a heating medium (8) to a heat exchanger (7) in the fuel vaporizer (5).
The process according to any one of the preceding claims, wherein the process comprises the step of controlling the level of liquid ammonia (19) in the fuel vaporizer (5).
The process according to the preceding claim, wherein the fuel vaporizer (5) comprises a heat exchanger (7), and maintaining the pressure of the gaseous ammonia fuel (3) in the fuel vaporizer (5) at the nominal pressure p0 is made by controlling the level of liquid ammonia in the fuel vaporizer (5) so as to adjust a portion of the heat exchanger (7) immersed in the liquid ammonia in the fuel vaporizer (5), so as to maintain a first portion of the heat exchanger (7) immersed in the liquid ammonia level and a second portion of the heat exchanger (7) above the liquid ammonia level.
The process according to any one of the claims 5 and 6, wherein controlling the level of liquid ammonia in the fuel vaporizer (5) comprises the steps of: - measuring the level of liquid ammonia in the fuel vaporizer (5), - adjusting the liquid feed stream (2) flow rate to the fuel vaporizer (5) so that the level of liquid ammonia in the fuel vaporizer (5) reaches a requested level.
The process according to any one of the preceding claims, wherein the process comprises the steps of: - comparing the level of liquid ammonia in the fuel vaporizer (5) with a predetermined minimum level, - in case the level is lower than the predetermined minimum level, adjusting the liquid feed stream (2) to the fuel vaporizer (5) so as to maintain the level above the predetermined minimum level.
The process according to any one of the preceding claims, wherein the process comprises the steps of: - vaporizing, in a main vaporizer, an ammonia feedstock stream for an ammonia cracking reaction, - directing, via a main vaporizer blowdown, liquid ammonia from said main vaporizer to the fuel vaporizer (5) so that said liquid ammonia from the main vaporizer is the liquid feed stream (2) for the fuel vaporizer (5).
The process according to the preceding claim, wherein the process comprises the step of: - providing an additional liquid ammonia stream (24), in addition to the liquid feed stream (2) from the main vaporizer to the fuel vaporizer (5).
The process according to any one of the preceding claims, wherein the process comprises performing said combustion with the fired equipment (4) to provide heat to a gas conversion, for producing a hydrogen product.
The process according to the preceding claim, wherein the gas conversion comprises a reforming reaction of a hydrocarbon and produces a synthesis gas stream as said hydrogen product.
The process according to any one of the preceding claims, wherein the process comprises the steps of: - detecting said variation in the demand for the gaseous ammonia fuel (3) that occurs, by measuring a variation of a flow rate of the gaseous ammonia fuel (3) to the fired equipment (4), or detecting a variation of a flow rate of a feed to said gas conversion, - maintaining the pressure of the gaseous ammonia fuel (3) in the fuel vaporizer (5) at the nominal pressure p0 by performing a compensation action.
The process according to any one of the preceding claims, wherein the process comprises recovering hydrogen from said hydrogen product, thereby producing a purified hydrogen product and an off gas, said off gas being used as fuel for the fired equipment (4).

Description

The present invention relates to a process for producing, from a liquid feed stream comprising ammonia, a gaseous ammonia fuel for a fired equipment. In an endothermic process for producing hydrogen (for example ammonia cracking) where ammonia is used as a fuel, for example such as a trim fuel, liquid ammonia feed needs to be vaporized. In a process of ammonia cracking reaction, a main ammonia vaporizer is provided in the process line of an ammonia cracker. The main vaporizer vaporizes ammonia at a process pressure ranging from 20 to 60 bar. However, the ammonia fuel is required at a lower pressure (1 to 5 bar). Therefore, a fuel vaporizer that operates at a lower pressure is beneficial. Controlling this fuel vaporizer is challenging because the vaporized ammonia fuel must be able to respond quickly to changes in load. Unlike trim fuels that are already in a gaseous state, such as natural gas, ammonia must first be vaporized, which can introduce a lag time and delay the availability of gaseous ammonia fuel. Furthermore, a rapid increase in the fuel demand, and the subsequent opening of the flow control for vaporized ammonia fuel, would cause a quick depressurization of the fuel vaporizer. The present invention aims to overcome these drawbacks. For this purpose, the invention proposes a process for producing, from a liquid feed stream comprising ammonia, a gaseous ammonia fuel for a fired equipment, said process comprising the following steps: providing said liquid feed stream to a fuel vaporizer to produce said gaseous ammonia fuel, said gaseous ammonia fuel being at a nominal pressure p0 in the fuel vaporizer;directing the gaseous ammonia fuel to the fired equipment for performing a combustion of the gaseous ammonia fuel; andwhen a variation in a demand in said gaseous ammonia fuel occurs, maintaining the pressure of the gaseous ammonia fuel in the fuel vaporizer at the nominal pressure p0. The variation in the demand for said gaseous ammonia fuel may appear in the following situations: an increase in the heating load of the fired equipment, particularly correlated with a desired increase in hydrogen production of a related hydrogen production process using the fired equipment and therefore an increase in a gas conversion feed stream flow rate (that is a process gas as different from the liquid feed stream to the fuel vaporizer) to a gas conversion unit,a decrease in the heating load of the fired equipment, particularly correlated with a desired decrease in hydrogen production of a related hydrogen production process using the fired equipment and therefore a decrease in a gas conversion feed stream flow rate (that is a process gas as different from the liquid feed stream to the fuel vaporizer) to a gas conversion unit,a decrease (or even loss) in the availability of another fuel (such as the PSA (Pressure Swing Adsorption) off gas associated with a hydrogen recovery) for the total firing duty, thus requiring compensation with more gaseous ammonia fuel, particularly more gaseous ammonia trim fuel. The gaseous ammonia fuel may be a trim fuel for the fired equipment. When an increase in a demand in said gaseous ammonia fuel occurs leading to a pressure decrease in the fuel vaporizer, the process may comprise the step of recovering the nominal pressure p0 of the gaseous ammonia fuel in the fuel vaporizer at the nominal pressure p0 by re-increasing the pressure in the vaporizer. Said step of recovering the nominal pressure p0 is an example of the step of maintaining the pressure p0 of the gaseous ammonia fuel in the fuel vaporizer at the nominal pressure p0. In one embodiment, the liquid feed stream provides liquid ammonia to the fuel vaporizer. In one embodiment, maintaining the pressure of the gaseous ammonia fuel in the fuel vaporizer at the nominal pressure p0 comprises the step of adjusting the heat provided to the fuel vaporizer, in particular to the liquid ammonia in the fuel vaporizer. In one embodiment, adjusting the heat provided to the fuel vaporizer is made by controlling the flow rate of a heating medium to a heat exchanger in the fuel vaporizer. For instance, by increasing the flow rate of the heating medium to the heat exchanger in the fuel vaporizer, the heat provided to the fuel vaporizer, in particular to the liquid ammonia in the fuel vaporizer, is increased and the pressure of the gaseous ammonia fuel in the fuel vaporizer is increased, for instance: to recover the nominal pressure p0, orthe pressure of the gaseous ammonia fuel in the fuel vaporizer is increased temporarily before going back to the nominal pressure p0. In an embodiment, controlling the heating medium flow rate is made by adjusting said flow rate downstream of the heat exchanger. In an embodiment, controlling the heating medium flow rate is made by adjusting said flow rate upstream of the heat exchanger. In one embodiment, adjusting a heat provided to the fuel vaporizer is made by controlling a temperature of a heating medium