Production of Hydrogen and Syngas via Steam Gasification of Glycerol in a Fixed-Bed Reactor

Glycerol is one of the by-products of transesterification of fatty acids to produce bio-diesel. Increased production of bio-diesel would lead to increased production of glycerol in Canadian market. Therefore, the production of hydrogen, syn gas and medium heating value gas is highly desirable to improve the economics of bio-diesel production process. In this study, steam gasification of pure and crude glycerol was carried out in a fixed-bed reactor at the liquid hourly space velocity (LHSV) and temperature of 0.77 h^?1 and 800 °C, respectively. In this process, the effects of different packing materials such as quartz particle and silicon carbide were studied. Catalytic steam gasification was performed in the presence of commercial Ni/Al₂O₃ catalyst in the range of steam to glycerol weight ratio of 0:100–50:50 to produce hydrogen or syngas when LHSV was maintained constant at 5.4 h^?1. Pure glycerol was completely converted to gas containing 92 mol% syngas (molar ratio of H₂/CO ≈ 1.94) and the calorific value of 13 MJ/m³ at 50:50 weight ratio of steam to glycerol. Hydrogen yield was increased by 15 mol% via the steam gasification process when compared to pyrolysis process. The presence of catalyst increased further the production of hydrogen and total gas in case of both pure and crude glycerol indicating their strong potential of making hydrogen or syngas. Maximum hydrogen, total gas and syn gas production of 68.4 mol%, 2.6 L/g of glycerol and 89.5 mol% were obtained from glycerol using Ni/Al₂O₃ catalyst at temperature and steam to glycerol ratio of 800 °C and 25:75, respectively.     

Enhancement of Methanol Production in a Membrane Dual‐Type Reactor

In this study, a dynamic model for a membrane dual‐type methanol reactor was developed in the presence of long term catalyst deactivation. The proposed model is used to compare the performance of a membrane dual‐type methanol reactor with a conventional dual‐type methanol reactor. A conventional dual‐type methanol reactor is a shell and tube heat exchanger reactor in which the first reactor is cooled with cooling water and the second one is cooled with synthesis gas. In a membrane dual‐type reactor, the wall of the tubes in the gas‐cooled conventional reactor is covered with a palladium‐silver membrane, which is only permeable to hydrogen. Hydrogen can penetrate from the feed synthesis gas side into the reaction side due to the hydrogen partial pressure driving force. Hydrogen permeation through the membrane shifts the reaction towards the product side according to the thermodynamic equilibrium. The proposed dynamic model was validated against measured daily process data of a methanol plant recorded for a period of four years and a good agreement was achieved. The simulation results show that there is a favorable profile of temperature and activity of the membrane dual‐type reactor relative to single and conventional dual‐type reactor systems. Therefore, the performance of methanol reactor systems improves when a membrane is used in a conventional dual‐type methanol reactor.     

Synthesis Gas Production Configurations for Gas‐to‐Liquid Applications

Different syngas configurations in a gas‐to‐liquid plant are studied including autothermal reformer (ATR), combined reformer, and series arrangement of gas‐heated reformer and ATR. The Fischer‐Tropsch (FT) reactor is based on a cobalt catalyst and the degrees of freedom are steam‐to‐carbon ratio, purge ratio of light ends, amount of tail gas recycled to synthesis gas (syngas) and FT synthesis units, and reactor volume. The production rate of liquid hydrocarbons is maximized for each syngas configuration. Installing a steam methane reformer in front of an ATR will reduce the total oxygen consumption per barrel of product by 40 % compared to the process with only an ATR. The production rate of liquid hydrocarbons is increased by 25.3 % since the flow rate of the purge stream for the ATR is the highest one compared to other configurations and contains mainly CO₂.     

Dynamic Simulation and Optimization of a Dual‐Type Methanol Reactor Using Genetic Algorithms

In this investigation, a dynamic simulation and optimization for an auto‐thermal dual‐type methanol synthesis reactor was developed in the presence of catalyst deactivation. Theoretical investigation was performed in order to evaluate the performance, optimal operating conditions, and enhancement of methanol production in an auto‐thermal dual‐type methanol reactor. The proposed reactor model was used to simulate, optimize, and compare the performance of a dual‐type methanol reactor with a conventional methanol reactor. An auto‐thermal dual‐type methanol reactor is a shell‐and‐tube heat exchanger reactor in which the first reactor is cooled with cooling water and the second one is cooled with synthesis gas. The proposed model was validated against daily process data measured of a methanol plant recorded for a period of 4 years. Good agreement was achieved. The optimization was achieve by use of genetic algorithms in two steps and the results show there is a favorable profile of methanol production rate along the dual‐type reactor relative to the conventional‐type reactor. Initially, the optimal ratio of reactor lengths and temperature profiles along the reactor were obtained. Then, the approach was followed to get an optimal temperature profile at three periods of operation to maximize production rate. These optimization approaches increased by 4.7 % and 5.8 % additional yield, respectively, throughout 4 years, as catalyst lifetime. Therefore, the performance of the methanol reactor system improves using optimized dual‐type methanol reactor.     

200kt/a焦炉气制甲醇装置合成催化剂升温还原过程简介

介绍200kt/a焦炉气制甲醇装置合成塔结构及催化剂装填情况,催化剂升温还原过程,导气及低负荷运行状况。     

Hydrogen Production by Sorption‐Enhanced Steam Glycerol Reforming: Sorption Kinetics and Reactor Simulation

Sorption‐enhanced glycerol reforming, an integrated process involving glycerol catalytic steam reforming and in situ CO₂ removal, offers a promising alternative for single‐stage hydrogen production with high purity, reducing the abundant glycerol by‐product streams. This work investigates this process in a fixed‐bed reactor, via a two‐scale, nonisothermal, unsteady‐state model, highlighting the effect of key operating parameters on the process performance. CO₂ adsorption kinetics was investigated experimentally and described by a mathematical reaction‐rate model. The integrated process presents an opportunity to improve the economics of green hydrogen production via an enhanced thermal efficiency process, the exothermic CO₂ adsorption providing the heat to endothermic steam glycerol reforming, while reducing the capital cost by removing the processing steps required for subsequently CO₂ separation. The operational time of producing high‐purity hydrogen can be enhanced by increasing the adsorbent/catalyst volume ratio, by adding steam to the reaction system and by increasing the inlet reactor temperature. © 2012 American Institute of Chemical Engineers AIChE J, 59: 2105–2118, 2013     

A Novel Fluidized‐Bed Membrane Dual‐Type Reactor Concept for Methanol Synthesis

A novel fluidized‐bed membrane dual‐type methanol reactor (FBMDMR) concept is proposed in this paper. In this proposed reactor, the cold feed synthesis gas is fed to the tubes of the gas‐cooled reactor and flows in counter‐current mode with a reacting gas mixture in the shell side of the reactor, which is a novel membrane‐assisted fluidized bed. In this way, the synthesis gas is heated by heat of reaction which is produced in the reaction side. Hydrogen can penetrate from the feed synthesis gas side into the reaction side as a result of a hydrogen partial pressure difference between both sides. The outlet synthesis gas from this reactor is fed to tubes of the water‐cooled packed bed reactor and the chemical reaction is initiated by the catalyst. The partially converted gas leaving this reactor is directed into the shell of the gas‐cooled reactor and the reactions are completed in this fluidized‐bed side. This reactor configuration solves some drawbacks observed from the new conventional dual‐type methanol reactor, such as pressure drop, internal mass transfer limitations, radial gradient of concentration, and temperature in the gas‐cooled reactor. The two‐phase theory of fluidization is used to model and simulate the proposed reactor. An industrial dual‐type methanol reactor (IDMR) and a fluidized‐bed dual‐type methanol reactor (FBDMR) are used as a basis for comparison. This comparison shows enhancement in the yield of methanol production in the fluidized‐bed membrane dual‐type methanol reactor (FBMDMR).     

Possibilities and state of development of nuclear coal gasification processes

By the development work of the last years and the successful operation of a experimental reactor it is clear today that the high temperature reactor is capable to produce heat at a temperature level of 950° C. This heat can be used in different industrial processes, especially for coal gasification. The processes of hydrogasification and steam gasification have been tested in large pilot plants in the past and are thought to be feasible today in connection with use of nuclear energy. In this paper the main aspects of these processes, of the nuclear reactor and of the heat exchanger system are presented and discussed. Questions like the choice and qualification of high temperature materials, the tritium contamination of the product gas and the aspects of licensing are key points of the technical realisation of nuclear process heat applications. This paper tries to summarize some of these results of the development programm of the PNP-Project (Prototyp Nukleare Prozeβwärme) in Germany, which is a common Projekt of German Companies financed by the government.     

Investigations on heat transfer and hydrodynamics under pyrolysis conditions of a pilot-plant draft tube conical spouted bed reactor

This paper describes the hydrodynamic and heat transfer performance of a pilot-plant scale conical spouted bed reactor designed for the pyrolysis of biomass wastes. The spouted bed reactor is the core of a fast pyrolysis pilot plant with continuous biomass feed of up to 25 kg/h, located at the Ikerlan-IK4 facilities.The aim of this paper is to obtain a deeper understanding of the spouted bed reactor performance at pyrolysis temperatures, in order to operate under stable conditions, improve the heat transfer rate in the reactor and minimize energy requirements. The influence of temperature on conical spouted bed hydrodynamics has been studied and wall-to-bed and bed-to-surface heat transfer coefficients have been determined.     

Study of the Characteristics of Methanol Synthesis in a Recirculation Slurry Reactor – A Novel Three‐Phase Synthesis Reactor

A process feasibility analysis on the liquid phase methanol synthesis (LPMeOH^TM) process was performed in a recirculation slurry reactor (RSR). In the three‐phase RSR system, a fine catalyst is slurried in the paraffin and this catalyst slurry is continuously recirculated through the nozzle from the slurry sector to the entrained sector by a pump. The syngas is fed concurrently with the downward flow of slurry to form the methanol product. A laboratory scale mini‐pilot plant version of a recirculation slurry reactor system was successfully designed and built to carry out process engineering research, and in addition, an identical cold model was built to measure the mass transfer coefficient in the recirculation slurry reactor. The effects of operating conditions, including temperature, pressure, gas flow rate and catalyst slurry recirculation flow rate on the productivity of methanol were studied. This experimental data helps the scale‐up and commercialization of the methanol synthesis process in recirculation slurry reactors.     

甲醇合成及精馏单元的能效优化

甲醇生产工艺普遍存在能耗、水耗过高的问题,对该工艺进行过程集成节能研究,具有重要的意义。以60万t/a煤制甲醇装置为背景,将处于上下游关系的甲醇合成及精馏单元作为一个系统考虑。利用夹点技术对该系统的用能现状和换热网络进行了分析,找出了违背夹点设计原则的不合理换热匹配。在此基础上,通过充分回收系统高温热源尤其是甲醇合成塔出塔合成气的能量,提出了2种现行换热网络的优化方案。方案1:节约低压蒸汽34.8%,节约脱盐水和循环冷却水21.1%,其中节约1.2 MPa低压蒸汽2 277.7 kW,节约0.3 MPa低压蒸汽20 544.4 kW;方案2:节约低压蒸汽30.8%,节约脱盐水和循环冷却水18.7%,其中节约1.2 MPa低压蒸汽6 027.0 kW,节约0.3 MPa低压蒸汽14 157.5 kW。当1.2 MPa与0.3 MPa低压蒸汽价格差距较大时,选择方案2较合理。     

煤制甲醇工艺甲醇合成塔的工艺设计探讨

以30万吨/年焦炉气制甲醇项目各工序的压力、温度、介质成分、流量等工艺条件,确定合成塔设备排热量及结构形式。甲醇合成塔又称甲醇合成反应器,是甲醇装置中的核心设备之一,也是合成工段中最关键的设备,合成塔为立式绝热管壳型反应器,管内装有C306型低压合成甲醇催化剂,本设计的目的是按照工艺要求设计甲醇合成工段甲醇合成塔,为压力容器设计提供理论依据。     

High Yttria–Zirconia and Yttria Ceramics for Petrochemical Reverse‐Flow Reactor Applications

Reverse‐flow reactors achieve the desired hydropyrolysis reaction of natural gas and other hydrocarbon feeds at very high temperatures of up to 2000°C, which enables the production of many high‐value chemicals. To identify refractory ceramic materials suitable for constructing key components of the reactor, the full range of solid solutions between zirconia and yttria having 18 to 100 mol% yttria have been tested in a laboratory reactor. Conventional yttria‐stabilized zirconia (YSZ) materials having 8 mol% Y₂O₃ appear to accommodate reactor thermal severity, but are prone to a new form of corrosion termed ceramic dusting that is observed when pyrolysis and oxidation cycles are alternated under reverse‐flow conditions. Yttria and high yttria–zirconia ceramics having ~80 mol% or more yttria suppress ceramic dusting corrosion in steam‐free pyrolysis environments. The addition of low levels of steam of ~5% to the pyrolysis gas stream increases the stability of YSZ materials substantially, so that the stability threshold is closer to 40 mol% Y₂O₃ in the yttria–zirconia system. The two approaches can be combined to optimize reactor performance. Key experimental results are presented and discussed taking into account the thermodynamic phase stability of the different phases.     

Performance analysis of integrated biomass gasification fuel cell (BGFC) and biomass gasification combined cycle (BGCC) systems

Biomass gasification processes are more commonly integrated to gas turbine based combined heat and power (CHP) generation systems. However, efficiency can be greatly enhanced by the use of more advanced power generation technology such as solid oxide fuel cells (SOFC). The key objective of this work is to develop systematic site-wide process integration strategies, based on detailed process simulation in Aspen Plus, in view to improve heat recovery including waste heat, energy efficiency and cleaner operation, of biomass gasification fuel cell (BGFC) systems. The BGFC system considers integration of the exhaust gas as a source of steam and unreacted fuel from the SOFC to the steam gasifier, utilising biomass volatilised gases and tars, which is separately carried out from the combustion of the remaining char of the biomass in the presence of depleted air from the SOFC. The high grade process heat is utilised into direct heating of the process streams, e.g. heating of the syngas feed to the SOFC after cooling, condensation and ultra-cleaning with the Rectisol^® process, using the hot product gas from the steam gasifier and heating of air to the SOFC using exhaust gas from the char combustor. The medium to low grade process heat is extracted into excess steam and hot water generation from the BGFC site. This study presents a comprehensive comparison of energetic and emission performances between BGFC and biomass gasification combined cycle (BGCC) systems, based on a 4th generation biomass waste resource, straws. The former integrated system provides as much as twice the power, than the latter. Furthermore, the performance of the integrated BGFC system is thoroughly analysed for a range of power generations, ～100–997 kW. Increasing power generation from a BGFC system decreases its power generation efficiency (69–63%), while increasing CHP generation efficiency (80–85%).     

Optimization of Methanol Yield from a Lurgi Reactor

Methanol is an important chemical with the potential to become an alternative fuel. An optimization study was performed for a Lurgi methanol synthesis reactor using the commercial process simulator Aspen Plus. The optimization routine is coupled with a steady‐state model of the methanol synthesis reactor. Syngas inlet temperature, steam drum pressure, and cooling water volumetric flow rate were optimized so that methanol production in the reactor outlet was maximized. The methanol yield increased by 7.04 %.     

Synthesis gas production using steam hydrogasification and steam reforming

Experimental work has been carried out on the mixed reforming reaction, i.e., simultaneous steam and CO₂ reforming of methane under a wide range of feed compositions and four different reaction temperatures from 700 °C to 850 °C using a commercial steam reforming catalyst. The experiments were conducted for a CO₂/CH₄ ratio from 0 to 2 and a steam to methane ratio from 3 to 5. The effect of CO₂/CH₄ ratio on the exit H₂/CO ratio and the conversions of the reactants indicate that the dry reforming reaction is dominant under increased carbon dioxide in the feed. Steam reforming of typical steam hydrogasification product gas consisting of CO, H₂ and CO₂ in addition to steam and methane has also been investigated. The H₂/CO ratio of the product synthesis gas varies from 4.3 to 3.7 and from 4.8 to 4.1 depending on the feed composition and reaction temperature. The CO/CO₂ ratios of the synthesis gas varied from 1.9 to 2.9 and 2.0 to 3.3. The results are compared with simulation results obtained through the Aspen Plus process simulation tool. The results demonstrate that a coupled steam hydrogasification and reforming process can generate a synthesis gas with a flexible H₂/CO ratio from carbon-containing feedstocks.     

Characteristics of fast pyrolysis of biomass in a free fall reactor

Fast pyrolysis of four kinds of biomass (legume straw, tobacco stalk, pine sawdust and apricot stone) was conducted in a free fall reactor. Interest is focused on hydrogen-rich gas production. The experimental results verify the occurrence of the in-situ steam reforming of tar, the steam gasification of char and the water–gas shift reaction with the primary pyrolysis of the biomass at higher heating rate in the free fall reactor. These reactions influence greatly the products' distribution and dry gas compositions in fast pyrolysis, especially at higher temperature. The pyrolysis is mass and heat transfer controlled for biomass particle size of above 0.20 mm but kinetically controlled in the case of particle size smaller than 0.20 mm. Biomass composed of higher cellulose and hemicellulose favors hydrogen-rich gas production in fast pyrolysis than that composed of higher lignin. The pyrolysis characteristics of each type of biomass can be explained according to its chemical compositions.     

Comparison of two-phase and three-phase methanol synthesis processes

A comparison is made between the ICI (two-phase) methanol synthesis process and a three-phase slurry process based on a multi-stage agitated reactor. The process calculations are based on a complete reactor system consisting of the reactor itself, a recycling system and a gas-liquid separator. The basic kinetic and thermodynamic data were taken from previous studies carried out in our laboratory. The results show that both reactor systems produce comparable methanol yields under the same process conditions except for the reactor temperature. Carbon conversion to methanol values close to 100% can be achieved. The three-phase process is more efficient in terms of heat recovery and power consumption. This is primarily caused by the fact that the three-phase process generates high-pressure steam and the ICI two-phase process yields boiler feed water of 90°C. Furthermore, the pressure drop in the three-phase reactor is smaller than in the two-phase reactor, resulting in a smaller duty of the recycle compressor. However, for the present low energy prices, the annual financial savings, coupled with these energetic aspects, are not sufficient to compensate for the higher capital investment of the three-phase reactor system relative to the ICI two-phase reactor system. A relatively high natural gas price of US $4.1 per gigajoule is needed to reach the economical break-even point between the two processes. More active catalysts may be developed in the near future. Our results show that a relative increase in the catalyst activity by a factor of 1.5 or more (for both processes) will make the three-phase process of economic interest at a natural gas price of US $2.5 per gigajoule.     

Simulation Study of a Novel Process Co‐Producing Synthesis Gas and Light Olefins

There are abundant resources of heavy hydrocarbons worldwide, and their utilization is becoming more widespread as time progresses. The present paper proposes a process that combines coke gasification and heavy hydrocarbon pyrolysis, producing synthesis gas and light olefins. Simulation studies on the process are carried out by using Aspen Plus. The results show that the temperature of the gasification‐pyrolysis can be controlled by changing the feed rate of O₂ and steam. In addition, the coke jam problem can be solved by increasing the gasification‐pyrolysis temperature or residence time. The maximum amount of light olefins can be acquired by controlling the gasification‐pyrolysis residence time. More than 37 wt % heavy hydrocarbons are changed to synthesis gas with more than 15 wt % changed to light olefins in the case studied.     

川西北甲醇装置高能耗原因与对策

设计工况下开工锅炉不能停运,开工过程中燃料消耗和放空损失大是造成川西北甲醇装置天然气和锅炉水消耗上升的主要原因。通过调整蒸气系统操作参数,更换换热设备和甲醇合成触媒,改造转化炉燃料气流程,缩短合成触媒倒入合成新鲜气时间的整改措施,解决了运行和开工过程中天然气和锅炉水消耗高的问题。