DE10151054A1 - Process for the treatment of biomass - Google Patents

Abstract

The aim of the invention is to provide a simple method for the treatment of biomass, during which a synthesis gas is produced. According to the inventive method, a) the biomass is subjected to fast pyrolysis, forming bio-oil and pyrolysis coke, b) the pyrolysis coke in the bio-oil is reduced to an oil mud, c) the oil mud is compressed in an entrained bed gasifier which is maintained at an overpressure, and d) said oil mud is transformed into a raw synthesis gas in the entrained bed gasifier.

Description

The invention relates to a method for the treatment of Biomass according to the first claim.

The generation of energy by burning biomass or Products made from biomass have the advantage that the Overall carbon dioxide balance is balanced. For this reason are currently many processes for energy recovery of biomass and its products.

Under the term "biomass", all agricultural and forestry residual and waste products, especially understood straw, leaves, hay, residual wood and wood waste be with household waste, especially with paper, cardboard and plastics can be contaminated or blended.

One method for treating biomass is Rapid pyrolysis, sometimes referred to as "flash pyrolysis". This process uses shredded, dry biomass quickly heated to approx. 500 ° C in the absence of air, the emerging smoldering vapors quickly, that is, after a Dwell time of about one second. The The process is carried out under normal or slight negative pressure performed and is therefore technically straightforward. It supplies carbonization gas, bio oil and pyrolysis coke in changing, however, by the process parameters influenceable parts. The main product is generally bio oil, its use as a fuel for substitution corresponding mineral oil products is discussed. The smoldering gas will often used internally for heating purposes, while the The usability of the pyrolysis coke is limited.

Unlike organic oils, bio oil contains typically 10 to 35% by weight water. It is in petroleum products and non-polar organic solvents are not soluble, on the other hand, miscible with water so-called pyrolysis lignin fails. When distilling almost half of the original mass remains in the Distillation residue.

Rapid pyrolysis is in a number of publications described in detail, for example in the article by A. V. Bridgwater. "An Introduction to Fast Pyrolysis of Biomass for Fuels and Chemicals "in Fast Pyrolysis of Biomass: A Handbook by A. Bridgwater et al. cpl-press, Aston University May 1999. In this article are also the devices for implementation rapid pyrolysis.

In addition, entrained flow gasifiers have already been proposed for the treatment of biomass
(http: / / www.itas.fzk.de/deu/Jahresberichte/jahr97PSA.htm, section "Use of renewable raw materials and treatment of residues from plants").

A detailed description of entrained-flow gasifiers can be found themselves in "NOELL conversion process for recycling and Waste Disposal "by Jürgen Carl and Peter Fritz, EF publishing house for Energie- und Umwelttechnik GmbH (1994), especially in the section "Presentation of the NOELL conversion process" by Manfred Schingnitz.

This section explains the structure and how it works of an entrained-flow gasifier in detail based on an illustration described. The entrained flow gasifier consists of an outer one cylindrical pressure jacket and an internally cooled, also cylindrical reaction chamber, which is in the upper part of the pressure jacket is used in such a way that between an annular gap remains in the two components. in the A pilot flame is maintained with gas and technical oxygen is generated. In the flame zone the fuel is fed separately.

The two input stages of the Noell conversion process include pyrolysis and entrained flow gasification. subsequent Stages concern the cleaning of the resulting products and of wastewater.

The pyrolysis is carried out in an externally heated rotary tube carried out. Through pyrolysis, solid pyrolysis coke and a Pyrolysis raw gas generated. The raw pyrolysis gas is cooled, with small amounts of condensed contained Hydrocarbons as well as any water and coke dust be separated. Solid ingredients are in a decanter separated the liquid hydrocarbons. Another Cooling level and decanting result in an additional cleaning of the Pyrolysis gas, which in the subsequent entrained flow gasification is used.

The pilot flame of the entrained-flow gasifier can be switched off if necessary the pyrolysis gas are fed. The fuel is Pyrolysis coke used from the upstream pyrolysis. This Coke must be ground very finely beforehand. For feeding into the entrained flow carburetor is a specially developed one pneumatic dosing system used. A major advantage of the Entrained flow gasifier is that the hot inside of the Reaction chamber, which are provided with a silicon carbide lining is, in the course of operation of a so-called mineral "Slag fur" which covers the material in front of the protects corrosive conditions.

The invention has for its object a multi-stage Process for the treatment of biomass to specify the one Pyrolysis stage and a subsequent entrained-flow pressure gasification includes, in which pyrolysis coke is used as fuel, at which makes feeding the pyrolysis coke easier can be.

The object of the invention is achieved by the first Process described claim solved. preferred Embodiments of the method are the subject of claims 2 to 6.

According to the entrained-flow gasifier, the fuel Pyrolysis coke fed in the form of a pumpable slurry. This avoids the problems that arise with a Feeding the fuel in a fine, solid form into one result in entrained-flow gasifier kept at a high overpressure. As Organic oil is used as a slurry.

Bio-oil is the main product in rapid pyrolysis in addition to the products pyrolysis gas and pyrolysis coke. Because of these The entire pyrolysis coke produced can be in quantitative proportions slurried in bio oil. Preferably the Fast pyrolysis carried out at such operating parameters that 40 to 80% by weight of bio oil and 10 to 30% by weight of pyrolysis coke form. In this case, a slurry of the produced pyrolysis coke in the resulting bio-oil particularly suitable for the pumping and feeding properties Oil sludge. To carry out the fast pyrolysis, pressures are in the Range from atmospheric pressure to rough vacuum and Temperatures in the range of 400 ° C to 600 ° C are well suited. The The residence time of the steam until condensation should Range from 0.5 to 5 seconds.

The entrained flow gasification is of the entrained flow type carried out in the publication mentioned is described. The one maintained in the entrained flow carburetor Operating pressure should be at least 50 bar; the maximum pressure arises from the condition that supercritical states in the Entrained-flow carburettors can be avoided. Pressures of 50 bar and more are for example for the catalyzed Low pressure methanol synthesis required when on additional Syngas compressors should be dispensed with. Pressures are up to 200 bar however possible. A high operating pressure in the entrained flow gasifier offers the advantage that the synthesis gas with a corresponding pressure at higher pollutant concentrations and in smaller devices can be cleaned more easily. On high operating pressure ensures high Reaction speed and a high material turnover. The temperature in the Entrained-flow gasifier should be in the range of 1200 ° C to 1800 ° C; this causes the slag fur as intended to the Internal walls of the reaction space expires.

If necessary - especially if you have "dirty" biomass a high proportion of non-volatile ash is used - it is recommended to use the pyrolysis coke before slurrying wash the bio oil with water. In particular, the Items potassium and chlorine removed in the following Entrained-flow gasification and synthesis gas processing problems could prepare. For propagation and qualitative Improvement of the slag fur in the entrained-flow gasifier can do that Oil sludge in the form of an inorganic slag generator Ash rich coke from another source and / or one powdered mineral are added. It is irrelevant whether you can use these materials with the pyrolysis coke or mixed with the oil sludge.

The inventive method enables the use of total usable energy content of the biomass for the Synthesis gas generation in the subsequent entrained-flow gasification, without that on the entrained flow gasifier more than one metering device for Fuel must be provided. The pyrolysis gas from the Rapid pyrolysis is suitable for maintaining the Pilot flame or for atomizing oil sludge. Of particular The advantage is that on cleaning steps or on chemical Treatment process for the bio oil can be dispensed with because it is mixed with the pyrolysis coke anyway. The pyrolysis oil can also all condensates, especially the "Slurry products", for example, from decanters for the Synthesis gas cleaning can be added, so that the cleaning of the Product flows from fast pyrolysis are considerably simplified.

Bio oil or oil sludge is also easier transport and storage as well as more flexible use than dusty ones Pyrolysis. The invention opens up the possibility of bio oils or Oil sludge from several decentralized Bring fast pyrolysis facilities together and in a large, central Further processing entrained-flow gasifier. In these cases it is sensible, the pyrolysis gas directly in the fast pyrolysis use. In the pyrolysis gas of a fast pyrolysis is usually only around 10% or even less of the total calorific value of the initial Biomass contain so that still 90% or more of the Energy content of the original biomass in the Entrained-flow gasifier arrives.

The invention is illustrated below with the aid of a figure explained.

The figure shows a basic technical concept for generating Fuel and electricity from biomass.

The biomass is delivered and, if necessary, temporarily stored subjected to a pretreatment which involves crushing and includes drying. Then it becomes fast pyrolysis fed, which - as already mentioned above - easiest at Atmospheric pressure can be carried out. The Operating temperature is around 500 ° C and is usually above one Maintain heat transfer circuit.

The products of rapid pyrolysis are carbonization gas, bio oil and Pyrolysis coke. These products can, for example, in one Ratio of 15: 60: 25 wt .-% accrued. using options for the carbonization gas are used as fuel gas z. B. at the Fast pyrolysis itself, electricity generation in gas engines or Turbines and use as atomizing gas or fuel gas for the pilot burner of the downstream entrained flow gasification. The Bio oil is used to make the coke slurry. The pyrolysis coke is finely ground beforehand. Contains the Biomass used high potassium and chlorine proportions such as for example straw or other rapidly growing biomass, it can be useful to the pyrolysis coke before the slurry for example in a washing device with water from Potassium chloride and other soluble potassium / chlorine compounds too to free.

The typical calorific value of pyrolysis coke is almost twice as high high as the calorific value of bio oil, while the calorific value of Pyrolysis gas only roughly half the calorific value of bio-oil is.

The oil sludge resulting from the slurry of the Pyrolysis coke in bio oil is then obtained with the help of a High pressure pump pumped into the entrained flow carburetor. The Entrained-flow carburettors can be at just over 50 bar and one Temperature of 1500 ° C operated. The pilot flame will z. B. with pyrolysis gas from rapid pyrolysis or with Synthesis gas from the entrained-flow gasifier and technical oxygen operated. The oxygen content is said to be about one third to one Quarters based on total oxygen demand Oxidation of the ingredients amount. One must be sufficient high reaction temperature can be guaranteed so that chemical reaction takes place as completely as possible and the proper drainage of the slag fur is guaranteed. As a result of sub-stoichiometric oxygen content prevail in the Entrained flow carburettor reducing conditions.

The raw synthesis gas leaving the entrained flow gasifier can be used as High temperature fuel gas or used as a reducing gas become. But it can also be processed and valuable Chemical products, such as fuels, are implemented. The the pure synthesis gas leaving the gas treatment unit is suitable for methanol synthesis, as a fuel substitute or for others Synthesis in chemistry, for example to carry out Oxosynthesis or, after a shift reaction, hydrogenation. That at synthesis gas that has not been converted can be used in Gas turbines, gas engines or GUD systems can be turned into electricity.

Claims (6)

1. Process for the treatment of biomass, in which a) the biomass is subjected to rapid pyrolysis, bio-oil and pyrolysis coke being formed, b) the pyrolysis coke is slurried into an oil sludge in the bio-oil, c) the oil sludge is pressed into an entrained flow gasifier maintained at an overpressure and d) is converted into a raw synthesis gas in the entrained-flow gasifier. 2. The method according to claim 1, wherein the biomass is an agricultural waste product represents. 3. The method according to claim 1 or 2, wherein rapid pyrolysis is carried out under such conditions is that from the biomass 40 to 80 wt .-% bio oil and Form 10 to 30 wt .-% pyrolysis coke. 4. The method according to claim 1, 2 or 3, in which the oil sludge in the entrained flow gasifier at 25 bar to 200 bar and 1200 ° C to 1800 ° C with oxygen deficiency is implemented. 5. The method according to any one of claims 1 to 4, in which soluble before pyrolysis coke slurries Ingredients are washed out by washing with water. 6. The method according to any one of claims 1 to 5, in which the sludge an inorganic slag former in the form a high-ash coke and / or a powdery one Minerals are added.