Agenda

The paper will present a case study of continuous migration of silica and phosphate from a unique source into high pressure steam generated from raw gas Boilers. The incident happened in newly commissioned 900 MTPD ammonia production unit in India.

Owing to regular migration of silica and phosphate in steam, the rotor and diaphragms of the PAC (Process Air Compressor) steam turbine were choked, resulting in the forced shut down of the plant. The reason for carryover of silica and phosphate in the high pressure steam were rightly identified and the ammonia plant resumed normal operation after replacing rotor of high pressure PAC steam turbine. The ammonia plant continued with high load operation at 110% afterwards without noticing any process related abnormality for one further year. It was then noticed that pressure drop across the HT Shift Converter had started rising very slowly. There had not been any observations related to any process upset related to HT shift converter operation. In subsequent operative period; pressure drop across HT Shift converter started increasing at higher rate with looming fear for another forced shutdown.

The paper will present problem analysis, counteracting measures, operational philosophy adopted by National Fertilizers Limited, a leading nitrogenous fertilizer manufacturer in India, to continue operation till next planned annual turnaround. The paper will also provide glimpse to operational limitations faced due to slow deterioration in efficiency of process air compressor steam turbine from one of least expected source.

This paper will describe the challenges of the current, widely used methods for accurate water measuring during ammonia catalyst reduction and startup and unveil ActiSafE™, a new non-dispersive infrared technology based on NDIR that was developed by Clariant. To illustrate the advantages of ActiSafE™ two cases studies of water measuring during startup and reduction of Clariant’s ammonia synthesis catalyst AmoMax 10 in Yara’s ammonia plants in Tertre and Hull will be demonstrated.

Water is a substance that negatively influences the activity of ammonia synthesis catalysts and must be limited to certain concentration levels during the reduction. Therefore, accurate measurements of the water concentration during catalyst reduction and startup are crucial. However, the significance of the water measurements is limited by certain challenges like the possible condensation of water in poorly insulated sample lines, which can lead to misleading measurement values and hence to a suboptimal catalyst performance after reduction

Existing analytical methods to determine the water concentration are the Ascarite, the Carbide method and the Karl-Fisher Method. These methods can bring good results but have some operational challenges like high labor, the need for chemicals and delayed results. Due to the discontinuous nature of the measurement, plant operators may be unable to counteract a sudden increase in water concentration (e.g. by reducing the temperature) before permanent damage is caused to the catalyst.

In contrast, the new ActiSafE™ method developed by Clariant (patent application is pending) provides several advantages like continuous real-time measurements of the water concentration in a range of 100 – 6000 ppm while also measuring the ammonia concentration at the same time. There is no requirement of manual operation as the instrument has an analog output and can be connected to the DCS system of the plant for monitoring real-time values in the control room. The real-time data allows plant operators to react quickly to changes in water content and to optimize the reduction procedure, thus saving time and/or avoiding catalyst poisoning. Irregularities in the sample line like water condensation can be immediately detected and rectified.

During the reduction of the wustite-based ammonia synthesis catalyst AmoMax 10 at Yara Tertre and Hull, the new ActiSafE™ method was successfully applied to monitor the water concentration with high accuracy. Condensation in the sample lines was detected in time and the lines were properly insulated before the start of catalyst reduction. Due to the reliable water measurements, the reduction was carried out safely and as fast as possible despite certain challenges during the procedure. Consequently, the ActiSafE™ method helped Yara to optimize staff (no personal in laboratory needed anymore) and costs of the catalyst reduction.

Casale is continuously expanding its urea technology portfolio by introducing novel technical solutions in order to optimize the efficiency and reliability of urea process. This paper describes the key features and outstanding performance of the latest technologies developed by Casale and currently available on the market: Casale Improved High Efficiency Trays and Casale Vibrating Skin Bucket.

One of the major developments aimed at enhancing the urea process efficiency is the design of new reactor trays that are an improvement of the widely applied Casale-Dente High Efficiency Trays.

Thanks to the innovative shape, the new trays maximize the mixing effect between the gas and the liquid phase along the whole reactor length, allowing to operate the urea reactor near to theoretical equilibrium conversion. As an overall result, it is possible to achieve a remarkable increase of reactor conversion as well as a reduction of plant energy consumption with reduced reactor volume.

Casale Improved High Efficiency Trays can be effectively applied in new reactors to achieve high urea yield with low reactor volume or to promote the conversion of existing reactor in revamping project with targets of capacity increase and energy saving.

Another area of improvement of the urea process regards the quality of the final product. Casale has recently developed an advanced design for vibrating prilling bucket, the so-called Vibrating Skin Bucket. This technology has been developed in collaboration with  Tuttle Prilling Systems and successfully tested on industrial scale.

The Casale Vibrating Skin Bucket is such that an excellent control of liquid droplet formation can be reached over a wide range of plant load. Casale Vibrating Skin Bucket can produce on-spec prills with various average prill diameter and can be successfully applied in urea plant with capacity ranging from small to large.

By replacing a traditional rotating bucket with a Casale Vibrating Skin, it is possible to increase plant production and improve the uniformity (size and shape) of the urea prills. Furthermore, a reduction of fine particle content in the product as well as a decrease of dust emission from the top of the prilling tower are achieved.

Many of the most important characteristics of catalyst pellets when used in a catalytic reactor are shape and size, strength, voidage, pressure drop and heat transfer.  Historically, many of these parameters have been developed and evaluated experimentally and difficult to capture the full range of applications of customers across the industry. 

Johnson Matthey has a long history of utilising state of the art modelling techniques to allow development of catalyst shapes for applications including pre-reforming, reforming and water-gas shift, we use powerful of computational modelling and rapid prototyping in catalyst development.

This paper will describe work carried out by Johnson Matthey and in collaboration with academic partners in developing and evaluating catalyst shapes and features such as complex geometries or surface textures.  It will also touch on how utilising modern additive layer manufacturing techniques can allow for rapid prototyping, which can in turn accelerate experimental validation of computational models. 

We will present comprehensive data showing the development of Johnson Matthey’s QUADRALOBE^TM family of shapes that continue to be market leading 20 years after the launch – over which time it they have been proven to improve efficiencies and run length on hundreds of  SMR’s.   We will additionally present on the development of the latest shape to be introduced into the HTS area, the Johnson Matthey F-Shape. 

Important bulk chemicals such as hydrogen, ammonia, and methanol are produced in a multiple step process. The first step is typically conversion of natural gas, or a similar feedstock, to produce hydrogen or synthesis gas (a mixture consisting of mainly hydrogen and carbon monoxide). This is followed by the actual synthesis and purification. The synthesis gas production step is often carried out by reforming of the feedstock with mixtures of steam and carbon dioxide (henceforth referred to as CO₂ reforming).

CO₂ reforming is an environmentally interesting process, as it offers a way of utilizing CO₂, which is a polluting greenhouse gas, and in many industries often considered as a waste product. CO₂ reforming is a process which can be designed with overall negative CO₂ emissions, or in other words can be designed to utilize more CO₂ than what is emitted. It is therefore expected to play an important role in combination with CO₂ capture technologies.

An increase in the amount of CO₂ added to the process will result in an increased fraction of CO in the produced synthesis gas. Synthesis gas with H₂/CO ratios in the range of 0,5–3 can be produced. These CO-rich gasses are typically utilized in the production of functional chemicals and synthetic fuels.

This paper describes a new high temperature CO₂ reforming process where preheated CO₂ is added directly downstream of a main reformer and then equilibrated in an adiabatic reactor. The technology makes use of the high temperature of the reformer effluent to circumvent carbon formation while at the same time maintaining an overall minimum steam-to-hydrocarbon carbon ratio, depending on process specific conditions. This new technology is a promising solution within the area of CO₂ utilization, converting CO₂ to valuable synthesis gas with a high content of CO, but without the traditional limitations requiring large amounts of steam addition. It can be used to retrofit an existing unit towards more CO production or included in new projects and is an excellent match in cases where excess CO₂ is available. In the presentation, the new technology will be described, and the benefits will be illustrated with specific examples.

Sandvik and Stamicarbon have introduced Safurex® as a ultimate corrosion resistance material for the urea synthesis in 1996 and is the basis of a long lasting partnership. This so-called super duplex stainless steel is specially designed for the urea synthesis in a long tradition of revolutionary innovations. Today more than 80 plants worldwide have included around 200 pieces of high pressure equipment in Safurex® with a strong focus on safety, reliability and performance.  

The paper demonstrates the fruits of a long lasting relationship and the commitment to improve the design of urea plants every day with innovative developments and a pioneering attitude to accomplish challenges necessary to take the next step. 

A remarkable milestone for Safurex® is clarified in relation to the failure frequency of tubes applied in HP tube and shell heat exchangers while it is demonstrated how core technical material knowledge and knowledge on ammonium-carbamate corrosion is validated and the relevance of high quality production standards work hand in hand.

In 2017, AmmoniaKnowHow.com and UreaKnowHow.com introduced global open source risk registers for ammonia and urea plants.

On July 1, 2020, the Risk Register Safety Risks in Urea Plants contained already 135 safety risks.

Detailed analyses concludes that most safety risks are associated to the high pressure synthesis section.

This paper describes what are the most critical safety risks and provides recommendations for prevention and mitigation measures.

This paper details the first commercial references of the novel steam reforming catalyst ReforMax 330 LDP Plus, demonstrating a significantly lower pressure drop in the reformer tubes and a strong poison resistance. Furthermore, Clariant’s reformer service ReforSafE™ was applied to evaluate the performance of the catalyst and to ensure a safe and efficient overall operation of the syngas plants.

Building on the successful operations of our well-proven Primary Reforming Catalysts, Clariant recently launched the next catalyst generation with the innovative LDP Plus shape – ReforMax^® 210 LDP Plus and ReforMax^® 330 LDP Plus.  This shape enhancement leads to approximately 20% less pressure drop compared to the traditional LDP shape and offers plants a solution for efficiency improvement or debottlenecking with no changes to the reformer tubes. The pressure drop decrease results in energy savings or alternately, if the plant rate is limited due to front end pressure drop, the LDP Plus shape allows higher throughputs, provided that all other systems and unit operations can accommodate the higher front-end rates.

To demonstrate the superior performance of the ReforMax LDP Plus series, key performance indicators of the first commercial references at Yara Tertre, and El Dorado are presented, proving significantly lower pressure drop and higher resistance against coking.

To evaluate overall condition and performance of the steam reforming furnace in the three reference plants Clariant’s reformer service ReforSafE™ was applied.

ReforSafE is available in different service levels (standard, premium, and premium plus) that start with a quick tube wall temperature check and catalyst performance evaluation and culminates in comprehensive reformer evaluations using thermal imaging and gold cup equipment to provide a 3D temperature profile across the furnace, allowing recommendations of burner adjustments, correction models for tube emissivity, and deriving of the thermal efficiency of the furnace.

The combination of Clariant’s new reforming technologies allowed all two customers to increase the efficiency and the safety of their operations.

In the period from 1973 to 1988, 45 TEC and GIAP Ammonia plants were constructed in Soviet Union. All these plants used Kellogg (KBR as it is now) or similar GIAP ammonia process and had nameplate capacity 1360 or 1420 MTPD of ammonia. For the years almost all plants were modernized to capacity of 1500-1800 MTPD. The analysis of equipment & piping margins shows, however, that the already achieved capacity of about 1800 MTPD is not the limit for these plants. New technologies can boost the capacity to next level of 2100 MTPD of ammonia and above, which is close to state-of-art grass-root plants.

The Acron Group was the first ammonia producer on post-USSR territory who not just choose offered by KBR a new revamp approach but a very fast and efficient implemented it at successful revamp project of TEC ammonia plant in Dorogobuzh. This unit had nameplate capacity of 1360 MTPD, achieved before current revamp capacity of 1725 MTPD and achieved guaranteed capacity of 2100 MTPD with simultaneous energy savings by 9% in December 2019. Moreover, because of implemented measures the plant reliability was enhanced that is proved by uninterrupted operation of the plant since start-up.

The project team included KBR as Licensor and Basic designer, Novgorod GIAP (Acron Group) as General Designer, Dorogobuzh (Acron Group) as general manager and supervisor for construction.

The project was implemented within 2.5 years. It included state-of-art KBR design solutions as KRES^TM and Cold Wall Add-on Ammonia converter as main design features for modernization of reforming and synthesis sections, respectively. In total about 60 positions of equipment were installed and modernized; approximately 10 km of new pipelines was installed, and more than 650 MT of steel structures were erected. Main part of works was performed during normal plant operation and only tie-in of new equipment was done during normal plant turnaround within 42 days. Upon stabilization of performance after start-up the plant achieved all guaranteed figures.

This Dorogobuzh ammonia revamp project is the first successful revamp project in Russia and FSU for capacity increase above 2100 MTPD with enhancement of plant reliability and reasonable investments and can be considered as a benchmark for future revamp projects of vintage TEC and GIAP plants.

This paper will cover various project milestones and design aspects of the project including troubleshooting and lessons learned during commissioning of the project.

Two bimetallic urea strippers which had been in service for more than 20 years were reaching the end of their operational life due to corrosion at the bottom tubesheet that affected the tubesheet overlay, the tube protrusion and the tube-to-tubesheet weld joints.

This paper details a unique refurbishment operation that extended the units’ life and reliability by several years and consisted in removing and restoring the tube protrusions and tube-to-tubesheet joints at the bottom tubesheet by shortening the stripper length of 40mm.

As a further added value, the bottom tubesheet was not just restored to the original condition, but the tube protrusion was increased from the original 5mm that used to be the standard at the time the units’ were manufactured to the modern standard of 18mm, and the tube-to-tubesheet joints were welded by state-of-the-art automatic orbital GTAW procedure.

The whole job was performed in-situ without removing the strippers from their position, at a cost of roughly 10% that of a new unit.

Compressors are an important machinery asset in the production of fertilizers and are integral in their ammonia and nitric acid production lines. Reliable compressor performance is dependent upon having a high quality, well maintained lubricant. These compressor lubricants are placed under a lot of thermal stress and may be exposed to process gases, which can cause rapid fluid deterioration. These chemical changes in the lubricant manifest themselves into mechanical challenges in the compressor set, such as vibration, bearing temperature increases and valve sticking in hydraulically manipulated controls.

This paper examines the nexus between these chemical changes in the fluid and mechanical impacts to the machinery. Furthermore, best-practice condition monitoring strategies and maintenance actions are suggested for integration into a fertilizer plant’s reliability program.

This abstract will encompass incidents within OCI-Geleen and Iowa Fertilizer-Wever, IA, both involving the Low Temperature Shift catalyst vessels and the safe operations of these units under harsh conditions.

Iowa Fertilizer (IFCO)-Wever, IA commissioned their plant in early 2017.  Upon startup, it was determined that the isolation valves for the Low Temperature Shift vessel did not work properly. During multiple plant trips, the catalyst was steamed.  Also, the ammonia recovery unit had several issues and could not be put into service, resulting in the inability to provide hydrogen to the hydrodesulfurization unit for several months, resulting in leaking of organic sulfur and successive poisoning the LTS catalyst. Another issue was that the waste heat boilers, 103-C’s, downstream of the High Temperature Shift vessel were contaminated and corroded during construction or commissioning. The 103-C’s were unable to reduce the inlet temperature to the LTS properly. Due to these incidents, the LTS was operated at relatively high inlet temperatures being quite close to End-of-Run conditions. IFCO contacted their catalyst supplier Clariant and others to determine best practices and the best path forward.  After the consultation, IFCO was able to operate their plant safely and effectively for the next 2.5 years, despite the damage to the catalyst.  During the 2.5 years until catalyst replacement, in kind, the LTS showed stable carbon monoxide leakage and very stable pressure drop, despite a significantly higher production rate (+160 mtpd). 

OCI Nitrogen in Geleen, The Netherlands was operating ShiftMax 217 since 2012 and in November 2015 they faced a severe condensation issue in their LTS converter. OCI and Clariant worked closely and diligently to understand the cause of the wetting of the complete catalyst bed. A special dry-out and start-up procedure were implemented to minimize damage to the catalyst. Despite the severe incident, only a minor change in the temperature profile and no rise in pressure drop over the catalyst bed could be observed. The catalyst will be replaced in 2020 after 8 years of runtime.

Fertial Spa have successfully revamped their Kellogg ammonia plant in Arzew during the 2019. The main objective for this project was to improve energy efficiency of the unit by way of reducing synthesis loop pressure from 145 bar to 110 bar as well as increasing ammonia production by 20%.

Among variety of modifications, ammonia converter 105-D was retrofitted by KBR from original four axial beds quench converter (so called bottle-shaped) to a three-bed three interchanger axial-radial flow design with a total change of the reactor internals to a new design. The new KBR vertical 3 bed axial-radial arrangement utilises the same 3rd bed series arrangement (Beds 3A/3B) which is a feature of the KBR horizontal converters.

Over the implementation period of the project, Fertial faced several challenges particularly on ammonia converter that included very limited confined space inside the reactor required to carry out interchanger and basket installations, welding procedure, catalyst loading, etc. Over this period Fertial followed strictly safety standards on permit issuing procedure including risk analysis on confined space entry to eliminate or minimize potential risks.

Another important challenge faced by Fertial was the mindset of operation staff who had been running the original 4-axial bed quench converter for the last 35 years and new converter configuration was totally different. That mindset together with uncertainty on catalyst bed temperature indicators’ location and readings was mainly the challenge during initial commissioning of the unit including catalyst reduction. .

Eventually ammonia converter was successfully commissioned and soon hit 100% load at 110 bar.

When basic chemicals such as nitric acid are produced for fertilizers, the process releases nitrous oxide into the atmosphere as a byproduct. This greenhouse gas has roughly 300 times the global warming potential of carbon dioxide and is thereby a major factor in global warming. More than 60 million tons of nitric acid are produced around the world annually, with an estimated 500,000 tons of nitrous oxide generated as a byproduct – equivalent to the carbon dioxide emissions from over 60 million mid-sized cars.

An innovative catalyst system thus offers a suitable, well-established system solution for reducing nitrous oxide emissions to lowest emission limits. Highly efficient catalysts from Heraeus and Lukasiewicz Research Network – New Chemical Syntheses Institute can significantly reduce nitrous oxide emissions up to 95%. Heraeus and Lukasiewicz Research Network – New Chemical Syntheses Institute are installing as partners this reduction technology in existing nitric acid plants around the world.  

Heraeus offers the possibility to reduce N₂O emissions by primary abatement. Due to our well-known FTC-technology, the primary N₂O abatement with the catalytic gauze system is fully customizable, making it suitable for full, as well as for partial loads. Therefore, the system helps our customers to meet the latest abatement requirements in the demanding N₂O emission markets in combination with secondary or tertiary solutions. Besides catalytic gauzes, Heraeus offers together with its partner Lukasiewicz Research Network – New Chemical Syntheses Institute Secondary Catalyst Systems for further N₂O emission reduction.

This presentation will show examples of success of reduced N₂O emissions at high process efficiency values in Europe. These successful results could be achieved with the combination of Heraeus reliable Gauze Catalyst System and high-quality Secondary Catalyst from Lukasiewicz Research Network – New Chemical Syntheses Institute.

These innovative catalyst systems highly support to reach the global climate goals and help for the fight against global warming. 

Control of pH is of extreme importance in the neutralization reaction process of Nitric Acid and Ammonia to produce Ammonia Nitrate. Many accidents, including explosions with fatalities, have been reported related to problems in the pH control of Ammonia Nitrate reactors. The state of the art for this control is a standard pH probe measuring pH of a sample, usually at 10% of concentration and at a temperature lower than 100oC. The sample needs to be diluted and refrigerated to avoid crystallization and damage in the pH electrode. Based on the sampling system, the pH measure is delayed, it is quite unreliable and attention-demanding; typical failures of the system are crystallization of the sample, uncontrolled dilution water, uncontrolled cooling and delays of the response.
In Fertiberia-Sagunto the pH control of the reaction is of greater importance due to the designed working conditions at high temperature (180oC) and at low pH (close to 1). The original pH control (standard system plus tritrometer) was not safe enough and caused many problems in the pH control system of the reactor. Fertiberia has installed a new control system concept based on sensors that measure free nitric acid or ammonia content. They are installed directly in the exit pipe of ammonium nitrate solution from reaction, at high temperature. This system gives an instant response of the excess content of the reactants, without delays and directly translatable to pH. One year of operation have proved the reliability of this control system and the consistency of the results.

Recent regulations have required Syngas producers and other refinery/petrochemical end-users to tighten Nitrogen Oxides (NOx) emissions from fired heaters, which has prompted end users to explore best available options for their application to achieve NOx emission reductions for their existing furnaces with minimal modifications. There are several methods of NOx reduction in furnaces that can be considered, such as mechanical or process changes that reduce the creation of NOx, installation of Low NOx burners, Selective Catalytic Reduction (SCR), and Selective Non-catalytic Reduction system. Selection of the correct technology(s) to achieve the required emission limits must consider numerous variables such as cost of installation, shutdown time, operation and potential production limitations or bottlenecks, etc. Often, a combination of technologies results in the most favorable solution. Both SCR and SNCR systems use ammonia (in aqueous or anhydrous form) to reduce NOx emissions. For each system there are considerations that determine the capability of achieving the targeted NOx and ammonia (NH3) slip such as the temperature range for effective reaction, the pressure drop available, the ability to mix the reactants, and the residence time at appropriate temperature. Historically, the application of an SNCR system for NOx reduction in Steam Methane Reformers (SMRs) – the type of fired heater discussed in this paper – has been limited for the above reasons. However, advances in Computational Fluid Dynamics (CFD) Modeling have allowed for study and experimentation of the variables involved in determining suitability for a particular installation that BD Energy Systems has successfully executed. This presentation and paper discusses the history of a particular SMR and a CFD study to determine the suitability of an SNCR system for required NOx emission reduction and NH3 slip, and optimization of the design that resulted in a successful installation and performance.

Ammonia is one of the best-known chemicals regarding safety measures for handling and storage in order to prevent hazardous releases. Yet no reliable measures have been developed for early warning and situation assessment in case of such incidents. The inherent risk was taken into account upon construction of todays facilities. Many of which are at least 40 to 60 years old. But growing productivity demands and ever-growing neighbouring cities constantly increased this risk. Warning for ammonia releases becomes an ever more urgent problem considering increasing worldwide demands for ammonia. And the prospect of ammonia playing a major role in the transportation and storage of hydrogen fuel as green fuel  will eventually catapult the demand for ammonia storage and ammonia production to new heights .

Automated early detection of gas leaks and tracking of moving gas clouds in case of an incident – this combination of risk prevention and incident mitigation was the design task for the early warning solution that was installed at CHEMELOT chemical park in Geleen, The Netherlands. In the first phase the scanfeld early warning solution safeguards the OCI melamine and urea complex. The site in close vicinity to a densely populated campus requires the warning of a release incident at any point within minutes. Once ammonia is in the air, the propagation of the moving cloud must be tracked and mapped live until it reaches the fence. The remote monitoring solution covers large areas and can locate a gas anywhere within sight. The early warning solution is based on spectroscopic analysis (FTIR spectroscopy) that allows safe identification and mapping of hundreds of different chemicals – both flammable and toxic – from large distances of up to 4 km.

While the detection and visualization of an ammonia cloud was the primary target of the first phase installation, the design goal of the solution is to eventually cover the entire CHEMELOT north site. By the time of the Ammonia Safety Symposium we will be able to show the first results.

Casale is the licensor and the EPC contractor of a 1500 MTD Nitric Acid plant in Navoiy, Uzbekistan.

The last phase of the site installation and the subsequent commissioning and start-up were successfully completed during the unexpected COVID 19 pandemic. The consequent strict restrictions on traveling imposed forced Casale and the End-user to think creatively and rapidly devise and implement creative approaches to accomplish the last phases of the project.

A reduced Casale staff at site granted the minimum necessary operability, while the Casale head office the manufacturers of key equipment  provided  assistance and support remotely.

This paper reviews such history of a successful plant start up despite the difficulties caused by Covid-19.

A successful solution of current process challenges including the increase of efficiency degree is not possible without new materials. VDM® Alloy 699 XA is a newly developed alloy for application in the chemical process industry (CPI) exhibiting an excellent resistance under metal dusting conditions. Remarkable increase of metal dusting corrosion resistance in combination with its excellent workability, especially regarding the production of seamless tubes, makes this alloy a high potential candidate for CPI applications. However, not only end application properties such as corrosion resistance are a key indicator for a materials performance; an equally fundamental requirement is the user-friendly weldability of the material, which allows complex constructions under high restraint conditions, or maintenance by easy weld repair, which finally guarantees a long material life.

This paper is focused on the welding aspects, investigation of the properties of welds, and their performance under metal dusting conditions. Additionally, the impact of a post weld heat treatment (PWHT) on mechanical properties as well as a surface treatment of the weld-joint before exposed to metal dusting conditions are shown. These results should help dimensioning of weld constructions and maintenance work routine. In this connection, two welding procedure qualifications similar to ASME Sec. IX or ISO 15614-1, with and without a PWHT at 980°C/ 3 hours are discussed. Depending on the construction considerations and the application temperature, the PWHT helps to prevent a possible risk of stress relaxation cracking.  Moreover, besides investigations of microstructure and mechanical properties of welds, the influence of the surface treatment such as grinding or brushing of the weld and its effect on the mass loss under metal dusting conditions are studied and quantified. It was found that weld ground with grid 60 reduces the mass loss significantly in comparison to a brushed surface.

In April 2019, a syngas plant suffered a major failure of the steam superheater outlet header. The header suffered a rupture of a longitudinal seam  weld. The extremely rapid loss of containment resulted in significant damage to surrounding equipment and infrastructure. By good fortune, there were no personnel in the vicinity of the equipment at the time and no injuries occurred. There is no doubt however, that anyone close to the equipment would have been in severe danger and fatalities could have been expected. The incident resulted in a major plant outage lasting many weeks before the plant could be restarted.

The HP steam superheater in question is located in the convection section of the primary reformer. It is the first coil to be exposed to the flue gas exiting the reformer radiant section. The inlet and outlet headers were identical in design. It was the higher temperature outlet header that failed.  The header was orientated vertically and was located in a box on the side of the convection section duct. The box was separated from the main duct by a non-gas tight tube sheet. It is anticipated that flue gas flow through the header box would have been minimal. The operating temperature would therefore have been strongly controlled by the steam temperature. A review of DCS data indicated that no abnormal conditions had been experienced prior to the failure.

Similarly, the design of the header was found to comply with the requirements of the ASME code. This paper describes the investigation into the failure mechanism and the cause of the failure. The operating conditions meant that the possibly more obvious damage mechanisms such as creep and fatigue could be readily discounted. Similarly, corrosion mechanisms such as stress corrosion cracking were not credible due to the absence of a corrosive media. The most credible damage mechanism was stress relaxation cracking. There were however a number of factors that did not fit with the commonly accepted understanding of this mechanism.

The investigation focussed on the material of construction, 316H stainless steel, the fabrication method and the morphology of the fracture. The findings have resulted in significant design modifications to the replacement header that were made with the intention of eliminating this damage mechanism.

Engro fertilizers limited is one of the leading urea manufacturers  in Pakistan. This paper comprehends structural rehabilitation of a 1960’s vintage wooden cooling tower at Engro’s Ammonia urea complex, relocated from Pascagoula, USA to Daharki, Pakistan in 1992. Subject cooling tower is of cross flow type, has capacity of 50,000 GPM with 06 cells and a common cold-water basin.

This paper describes the details of structural health assessment of the load bearing components of wooden cooling tower by destructive testing of selected samples and finite element analysis. Effect of cooling water chemistry and fungal attack on red wood is also discussed. Results are interpreted and translated into viable solution of strengthening the cooling tower structure by custom designed Fiber glass reinforced plastic (FRP) elements. Paper highlights the on-stream execution methodology adopted to ensure plant operation with no compromise on safety in a real challenging situation where 12 feet of cold-water basin filled with water at all times. this paper also entails the other Engineering and safety challenges faced during execution for benefit of other industries planning to execute similar jobs.

Structural strengthening of wooden cooling tower by FRP components has resulted in enhanced reliability of the structure which is evident by significant decrease in vibration of cooling tower fans and by elimination of sway in cooling tower. Beside the increase in reliability, the modification has also helped in increasing thermal efficiency of cooling tower by 8% resulting in more efficient plant operation.

PT Petrokimia Gresik, a fertilizer company in Indonesia, recently established a new 2000 MTPD capacity of ammonia plant with KBR Purifier^TM Technology, and It was commissioned in 2018. During 2 years operation period, the overall plant was running fairly well however 2 main issues occurred: higher consumption energy and a limitation on plant utilization due to the performance decline of the purifier package.

The main problem of energy efficiency was caused by higher steam consumption than designed condition related to air compressor turbine where the vacuum pressure of surface condenser tended to be high since the commissioning period and it was successfully resolved in early 2020, while the decline in purifier performance began in mid-2019 (after the first turnaround) and it was successfully recovered by rapid decompression blow in June 2020.

This paper will describe how to reduce the steam consumption of the air compressor turbine by about 10 tph or equal to 0.38 MMBTU/Ton and how to restore the ammonia production rate which fell by about 8% and loss ammonia reaction inside the Ammonia Converter in extremely case due to the performance decline of purifier package. Several alternatives to find the best solution has been tried to overcome these issues. Since the purifier package is the heart of the ammonia KBR Purifier^TM plant, these valuable experiences will be shared among the users or potential users who use or who have attracted a similar technology.

Engro Fertilizes Limited is one of the leading urea manufacturers of Pakistan, producing 2 Million tons per annum, which fulfills one third of country’s urea demand. The company carries more than five decades rich experience of operating ammonia-urea fertilizer complexes. It has two plants, and its newly commissioned plant started prilling in 2010.

Since commissioning, the plant has undergone through various challenges which included  high pressure super-heater steam coil damage, secondary reformer effluent waste heat boiler leakage, frequent fouling of process air machine and other steam turbines, condensate polisher issues, cooling water mal-distribution, change in feed-stock composition leading to installation of feed gas enrichment unit. These pleading problems have not only resulted in production loss but also demanded capital-intensive solutions.

Extensive efforts have been carried out for their resolution. Engro’s engineering team devised in-house solutions through rigorous modeling and simulations covering steady state and transient conditions. Moreover, liaison with seasoned consultants was made and OEM inputs were solicited for root cause analysis.

This paper explicates the solutions adopted to overcome these chronic issues and shares our lessons learnt.

A natural gas pipeline leak occurred on an Ammonia Plant. The direct cause of the failure was corrosion on the pipe surface which results in holes in the pipe around 2 millimeters of diameter. Plant management took a series of comprehensive actions to resolve the incident and maintain plant operations. The incident was manageable and the plant still running on safe conditions.

The paper focusing on discussing the act during the incident, how to prevent escalation of the hazard, operational stabilization, mitigation scenario, resolution, and recovery action. Safety mitigation conducted to manage and control the hazardous gas by installing a gas ejector to direct the gas to a safe place (vent stack). Several safety equipment installed on the site such as portable fire monitor, fire extinguisher, and fire curtain. Operational mitigation includes reviewing a number of possible scenarios, starting from if the leakage increases until when a fire is formed. Each scenario has its own set of work procedures that must be carried out during the emergency. Mechanical mitigation carried out to maintain the mechanical integrity of the pipe and prevent further failure by installing a box clamp. Then the next recovery plan is to replace the damaged pipe and conduct a more stringent corrosion monitoring program around the area.

Comprehensive actions taken have been able to maintain plant operating conditions at a safe level without unscheduled shutdown. Incident management is necessary to prevent further problems. Even a small problem that couldn’t be managed well, could lead to catastrophe.

Many industries may be required to reduce the amount of particulates they release into the environment.  These requirements typically depend on application field, location of plants, type and quantity of dust.

The technologies for the dedusting of industrial plants are as follows:

• Scrubbers
• Filters
• ESP

• Wet ESP
• Dry ESP

The Standard technology used for Fertilizer industry are Scrubbers and Filters.

Scrubbers are mainly involved in plant where required removal efficiency is quite low, due to the high consumption of energy. Filters are mainly involved in plant with low flow rate to be treated and not sticky dust.

Dry ESP technology is massively used in power plant technologies and metallurgical industry, as a final dedusting system for off gases.

Up to now, Wet ESP technology is well adopted in off gas mist SO₂ and SO₃ treatment plants.

Generally ESP technology is a Low Operation Cost, high efficiency, low pressure drop and temperature resistance technology.

Low maintenance effort is the main advantage,  especially if compared to Scrubbers and Filters, that require a huge maintenance protocol based on replacement of filtering media and cleaning activities.

Disadvantages would be related only to the  high investment cost and relatively huge dimension of plants.

The New project for a new CAN/ASN fertilizers production plant was conditionally approved by Czech state authorities in 2013. The outlet dust limit was strictly set by environment Authority to the level below 8 mg/Nm³, and no water discharges were admitted, even if disposed to water treatment plants.

The Company Lovochemie a.s. chose to adopt the WET ESP technology, even if there was no references worldwide, on fertilizer plants. No application of WET-ESP in fertilizer industry was known.

In 2013 the project for a new production line started. In 2016 order for Wet ESP was placed to AWS Corporation S.r.L.

The Wet ESP technology was "ad hoc" designed in order to match a good combination between operation costs, reliability of operations, efficiency, safety and zero emission philosophy.

In 2017 the gas treatment plant was started-up successfully.

Engro fertilizer, a pioneer in fertilizer sector of Pakistan, has been operating Ammonia Urea Complex for over 50 years. This paper encompasses Advance process controller (APC) installation at Ammonia unit of one of the largest single train Ammonia-Urea complex having capacity 3835 MTPD of urea in collaboration with IPCOS, the market leader in APC installation across the globe.

This paper details the various steps involved in APC implementation starting from pre-testing, challenges faced during DCS modifications done on stream without hindering plant operation and commissioning experience of APC without single process upset on one of the largest ammonia plants. It also highlights the aspects that need to be taken into account to ensure successful installation and operation of APC after commissioning.

After commissioning of the system, the data analysis indicated great stabilization in plant operation giving consistent ammonia production with breaking the highest ever single day ammonia production number in history of Engro’s plant operation. Moreover, because of limitation on waste heat boiler duty, APC greatly managed to keep all operating parameters within limits defined by boiler vendor to ensure safe plant operation while reaping maximum benefits available.

In the last three decades the advent of the fast computers combined with the development of accurate numerical algorithms for solving physical and chemical problems allows us the performing of computational fluid dynamics (CFD) simulations on complex industrial catalytic gauzes and large flow distribution simulation for industrial reactors with included detailed surface kinetics. Motivated by large industrial importance heterogeneous catalytic oxidation of ammonia with oxygen on Pt/Rh gauzes (first step of nitric acid production in the Ostwald process) is a perfect example for the application of aforementioned technique. The production of nitric acid via Ostwald process is one of the largest and most important industrial processes in the field of basic chemicals with an annual world production of over 80 million tons ^[1]. Despite numerous publications, there seems to be no published work that applies the existing reaction mechanisms in a flow simulation of the platinum gauze reactor. Since the reaction is known to be strongly heat- and mass transfer controlled, simulations which combine the surface chemistry, flow, diffusion and heat conduction are the key to the better understanding of the process and developing of new catalyst and optimization of the whole process of nitric acid production.

A mechanistic model of ammonia oxidation on platinum previously published by Kraehnert and Baerns was implemented in a CFD simulation using the rate mapping approach. Simulations were performed for industrially used gauzes produced by Umicore. The main results obtained by the simulations can be summarized as follows

• Realistic temperature and concentration distribution in gauze package.
• The N₂O Selectivity varies along the perimeter of each wire. The front side of the wire has a higher selectivity as a rear side.
• In a complex industrial gauze, the selectivity on the individual wires depends on the relative position of the wires in the gauze pack and is determined by local mass transfer effects.

Finally, the simulations have shown, that the complex industrial gauzes designs have lower N₂O selectivity compared to conventional woven gauzes (Figure 2).

Furthermore, it was possible to perform simulations of the industrial scale reactor including the chemical reactions in the catalytic zone obtaining suitable results. To tackle the challenge of different scales of gauze (µm scale) and ammonia oxidation reactor (m scale), the kinetics of a simplified gauze geometry have been investigated and the results have been stored in look-up tables. Then, the results of fluid calculations of the process gas inside the reactor have been coupled to the look-up tables to examine the consequences of the gas flow distribution in the reactor. 

The current study provides for the first time CFD simulation coupled with detailed surface kinetic mechanism of ammonia oxidation on complex industrial gauzes and in the industrial ammonia burner. It can explain the observed influence of the geometry on the performance of the catalytic gauze. 

As a result of implementation of this modelling approach a novel enhanced catalyst has been developed with increased efficiency and lower N₂O emission.

Chemical plant processes are complex and filled with potential sources of inefficiency. In today’s competitive landscape, minimizing these sources has become more and more important to be a successful player on the market. One way to minimize inefficiency is continuous optimization, which is something that can be built in the daily routines with procedures for monitoring of the firing of the reformer and temperature optimizations in the ammonia converter as examples. Other activities require in-depth knowledge and specific experience, a knowledge that is possible to get by partnering with a company that can offer both process and catalyst know-how, a company like Haldor Topsoe A/S.

An Asian ammonia producer struggled with some bottlenecks limiting their production. After performing a plant optimization together with a team of Topsoe engineers, it was possible to increase the production by 3%. This boost in production, which meant higher profits with no additional investments, was the result of a successful collaboration between the customer and Topsoe.

Operation at a loop pressure higher than design costs energy resources, and this was something an Indian ammonia producer had identified. Unable to pinpoint the root cause, they reached out to Topsoe for help. A team of Topsoe specialists helped identifying the reason and after the problem had been rectified, the loop pressure decreased by 4 bar and back to the expected level.

New times require new ways of thinking. In the light of the current challenging Covid-19 situation, Topsoe has developed remote services in order to assist customers, also when it is not possible to travel. This includes assistance with loadings, activations, and start-ups. We would now like to take the opportunity to share how advanced technical services, performed remotely or at site, can help decreasing downtime and increasing profit.

Digital products and services provided by thyssenkrupp Industrial Solutions combine the vast engineering and process know-how gathered as EPC contractor during decades of engineering and commissioning of process plants worldwide with state-of-the-art data-driven methods and artificial intelligence. Objective is to provide solutions for the operational challenges our customers face and to achieve a continuous and measurable improvement of their plant, e. g. by increasing reliability and uptime, optimizing efficiency and production as well as improving the overall operation and maintenance planning.

Connectivity to the plant using thyssenkrupp’s data logger and optional data storage in our cloud are the basis for our digital products and services, e. g. remote condition monitoring. Our process experts and data scientists analyze the data and provide regular reports including recommendations for operation and maintenance. Optimization potential is determined using a digital twin of the plant.

Additionally, thyssenkrupp Industrial Solutions offers a set of operator training sessions with different key aspects. Using the ammonia plant simulator, the operator can learn how to react in critical situations, such as trips or failures, and also test the reaction of the plant to different scenarios without any risk.

With the best digital services, thyssenkrupp Industrial Solutions can help to analyze, stabilize and optimize the customers plant during its lifetime.

Thermal separation processes like distillation require high energy inputs. Industrial heat pumps utilizing Mechanical Vapors Recompression (MVR) Blower technology unlock process energy savings. This case study shows how incorporating MVR Blowers reduces CO2 emissions and energy costs in a methanol stripping process.

There are different types of heat pumps using absorption, chemical systems and compression cycles. The compression cycles are differentiated into closed loops – the classic heat pump cycle – and the semi-open loops: thermal vapor recompression (TVR) and mechanical vapor recompression (MVR).

Waste heat recovery in industrial processes covers methods to re-use lost heat from industrial processes. The selection of heat recovery methods and techniques largely depends on key factors such as the quality, quantity and the nature of heat sources in terms of suitability and effectiveness. The identification of the waste heat sources is an important aspect when looking into heat recovery methods for industrial processes in order to achieve optimum results and efficiency. Heat pumps are devices for heat recovery shifting waste heat up to a useful temperature level and thus creating new potentials for energy savings.

The goal of implementing an industrial heat pump is to recover waste heat from the chemical plant to significantly improve overall efficiencies and to recycle it for process heating. Therefore, PILLER offers two solutions: the direct compression of process vapor by MVR blower technology and the compression of low-pressure steam generated by the waste heat source.

An MVR system compresses vapors evaporated from the process itself. The pressure rise of the compressed vapor increases the condensation temperature. This allows to reuse the heat of vaporization for process heating. For distillation columns the compressed overhead vapor is usually directed to the reboiler, supplying the column with heat.

In MVR processes, turbo blowers are often favored over turbo compressors due to higher reliability, easier integration, shorter lead times, lower investment and maintenance cost. PILLER is specialized in MVR Blower Technology with more than 3,500 installations worldwide. The presentation will outline the latest achievements.

Case Study: High energy efficiency methanol stripping with MVR technology

With an annual production of over 100 million tons, methanol is currently one of the most important basic chemicals worldwide. About 85% of it is used as starting material for synthetic products or as a solvent. The rest is used in the energy sector as fuel or a fuel additive. Besides the raw material input, the purification process is energy consuming and cost intensive.

This case study focuses on a methanol stripping process. By implementing an industrial heat pump, based on the PILLER MVR Blower technology, energy cost savings and a reduction of CO2 emissions can be achieved. In figures, this means a COP of 6.3 and reducing the final energy consumption by 84 % compared to single stage column with live steam heated reboiler.

The current penalties imposed to CO₂ emissions force industries to reduce the exhaust temperature to 90-100°C, which results in the raise of the furnace’s efficiency by at least 3-5%. APEX Group presents a solution for this new challenge, by using our new polymer composite plate-type Heat Exchanger.

In industrial processes, heat exchangers are often applied as air preheaters for furnaces, which constitutes as the process heart of an industrial plant. For example, in syngas, ammonia, methanol and hydrogen plants, Steam-methane Reformers (SMR) are widely used. And due to the pre-heated air, the efficiency of the combustion process is greatly increased. Overall, the installation of a heat exchanger as part of a  furnaces system (e.g. SMR) considerably reduces the operational expenses (OpEx) and CO₂ emissions due to a lower fuel consumption. The Heat Exchangers are usually designed to have a minimum metal temperature close to, but above the acid dew point (in the range of 120 - 140°C) to avoid condensation of H2SO4 and as a result corrosion of the heat transfer surface. Presently, due to the strict restriction on CO₂ emission, the exhaust temperature is forced to be reduced to 90-100 ?. At these temperatures being well below the acid dew point, the condensation of H₂SO₄ on the heat transfer surface of the air preheater is unavoidable. 

The concept of further reduction of the flue gas temperature was, up to now, limited due to material issues. We applied our in-house expertise from over 500 plate-type heat exchangers in the past 20 years to develop a highly efficient plate-type heat exchanger from a polymer composite resistant against acid corrosion. The new developed Cold-End Heat Exchanger will be able to lower exhaust temperature to a new level.

The presentation will describe the new polymer composite plate-type heat exchanger in detail and will discuss the necessary requirements for the implementation of such. 

APEX Group designs, sells and constructs heavy-duty plate-type Heat Exchangers for handling large volumes of gases for heat recovery and gas treatment applications. The operation principle consists of cold gases (e.g. air) and hot gases (e.g. flue gas) flowing through alternating parallel channels in a cross or (most efficiently) countercurrent arrangement.

In steam methane reformers, failure of refractory linings can lead to energy wastage, poor performance and loss of structural integrity, often resulting in an emergency shut down. IGS offer several options in online heater refractory maintenance that can be performed while the furnace is at operating temperature and still producing. All types of hot refractory repair services offer exceptionally fast payback, compared to the costs associated with conventional repairs which require the heater be shut down.

Hot Refractory Repair Services may be made by making access through the heater steel shell directly behind the damaged area. Minimal openings are used to insert specially designed components to support the repair material. This technique offers a semi-permanent repair method since high-quality refractory materials are employed with full structural reinforcement.

In addition to the online refractory repairs, IGS offer other online maintenance services, including vacuum cleaning of catalyst banks in SCR units and cleaning convection section tube surfaces.

During a routine inspection, an internal refractory failure was discovered on the transition duct from the radiant to the convection section in a refinery heater. Steam lines were added to the shell but could not get a meaningful decrease and consequentially production rates had to be lowered. The client had a tough choice to make: continue to operate at lower rates, losing ~$400,000 per day or take an unplanned shutdown and give up tens of millions of dollars in lost production. Fortunately, IGS was able to complete the repair, online, without further impacting production. After the repair, rates returned to typical production and the estimated ROI was over $40M.

IGS completed this repair, along with over 50 other refractory repair projects, online, safely and successfully over the last 12 years. With offices and agents located globally, IGS can react and mobilize to repairs timely, and saving clients from unplanned shutdowns and lost production.

This paper describes the groundbreaking ammonia-methanol co-production process developed and licenced by KBR and JM, that combines their market-leading ammonia and methanol technologies.

 

The co-production process is based on well-proven technologies utilizing KBR’s proprietary PURIFIER™ ammonia process and JM’s methanol process. Both KBR’s ammonia technology and JM’s methanol technology showcase a long history, deep experience, continuous improvements and leading-edge performance. KBR has licensed, engineered or constructed 244 ammonia plants worldwide.  JM has supplied the methanol industry with leading technology and catalysts for over 45 years and has licensed over 100 grassroots methanol plants during this period.

Ammonia is primarily used in the production of urea for fertilizer, with methanol and its derivative products primarily used to produce formaldehyde, acrylic and other polymers, synthetic fabrics, adhesives, paints, fuels and other products in pharmaceuticals and agrichemicals. The co-production of methanol and ammonia in a single plant offers many advantages including reduced capital expenditures (CAPEX) and lower operating expenses (OPEX).

The KBR and JM co-production process makes the most of the possible synergies between the two processes, maximizing the savings in CAPEX and OPEX while offering the highest levels of safety, flexibility and reliability.

In addition to the new Ammonia-Methanol Co-Production process development for new builds at world scale the two companies have considered process modification schemes that allow existing ammonia plants to produce methanol which can be desirable for on-site UFC manufacture at remote sites as UFC import is otherwise  constantly a need in the urea granulation process.

The removal of acid gases is an important step in the ammonia and syngas processes.  Improved modeling and performance of absorbers and regenerators can be achieved with rate based mass transfer algorithms and the latest random packing technology.  Rate based models overcome the deficiencies of equilibrium based calculations such as the need to estimate deviation from true equilibrium and packing or tray efficiency.  RATEFRAC^® software models the actual mass transfer column internals, not just a theoretical representation. 

The lasted advancements in random packing have resulted in improved effective surface area for mass transfer, higher capacity and lower pressure drop compared to previous generations.  These benefits can be used to reduce tower size and cost or increase throughput.  The differences between equilibrium and rate based models will be presented as well as a brief overview of the RATEFRAC^® software.  The software will be used to highlight the performance improvements that can be achieved using the latest generation INTALOX^® ULTRA random packing.