U.S. patent application number 12/598065 was filed with the patent office on 2010-05-27 for use of a mixture of carbon dioxide and nitrogen as an inerting and flow medium in powder injection systems for pulverized coal gasification under pressure.
Invention is credited to Manfred Schingnitz, Gunter Tietze.
Application Number | 20100126068 12/598065 |
Document ID | / |
Family ID | 39760500 |
Filed Date | 2010-05-27 |
United States Patent
Application |
20100126068 |
Kind Code |
A1 |
Schingnitz; Manfred ; et
al. |
May 27, 2010 |
USE OF A MIXTURE OF CARBON DIOXIDE AND NITROGEN AS AN INERTING AND
FLOW MEDIUM IN POWDER INJECTION SYSTEMS FOR PULVERIZED COAL
GASIFICATION UNDER PRESSURE
Abstract
A powder injection system for use in pulverized coal
gasification under pressure is provided. The powder injection
system includes a reservoir for stocking the pulverized coal, a
plurality of power injection tubes and a metering unit. A mixture
of nitrogen and carbon dioxide is fed to the components that are at
operating pressure, namely the powder injection tube and the
metering unit, as the inerting and flow medium or fluidizing
medium. The nitrogen and carbon dioxide mixture-carrying components
are heated in such a manner that the temperature is above the
threshold of the diphase range. A method is also provided. The
method allows reduction of the nitrogen content in the product gas,
which nitrogen is caused by the powder injection system, especially
when used in pulverized coal gasification under pressure to produce
a synthesis gas for the production of different hydrocarbons.
Inventors: |
Schingnitz; Manfred;
(Freiberg, DE) ; Tietze; Gunter; (Freiberg,
DE) |
Correspondence
Address: |
SIEMENS CORPORATION;INTELLECTUAL PROPERTY DEPARTMENT
170 WOOD AVENUE SOUTH
ISELIN
NJ
08830
US
|
Family ID: |
39760500 |
Appl. No.: |
12/598065 |
Filed: |
April 18, 2008 |
PCT Filed: |
April 18, 2008 |
PCT NO: |
PCT/EP08/54713 |
371 Date: |
October 29, 2009 |
Current U.S.
Class: |
48/101 ;
48/210 |
Current CPC
Class: |
C10J 2200/15 20130101;
C10J 2300/0969 20130101; C10J 3/78 20130101; Y02P 20/141 20151101;
C10J 2200/156 20130101; Y02P 20/142 20151101; C10J 3/00 20130101;
C10J 2300/093 20130101; C10J 3/50 20130101 |
Class at
Publication: |
48/101 ;
48/210 |
International
Class: |
C10J 3/00 20060101
C10J003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 30, 2007 |
DE |
10 2007 020 332.4 |
Claims
1.-4. (canceled)
5. A method for operating a powder injection system for a
pulverized coal gasification under pressure, comprising: applying
an ambient pressure to a reservoir which supplies the pulverized
coal; applying a high operating pressure to a plurality of powder
injection tubes and to a metering vessel which heats up the
reservoir; feeding heated nitrogen to the reservoir as an inerting
and dispersal medium; feeding a nitrogen and carbon dioxide mixture
to a powder injection transfer tube as an inerting and flow medium;
and feeding the nitrogen and carbon dioxide mixture to the metering
vessel as a fluidization medium.
6. The method as claimed in claim 5, wherein the supplied nitrogen
and carbon dioxide mixture is heated up to a temperature above a
threshold to a two-phase region at a high process pressure in a
high-pressure region of the powder injection system.
7. A method as claimed in claim 5, wherein a nitrogen and carbon
dioxide mixture ratio is dimensioned according to a highest
permitted proportion of nitrogen at a flow control unit to a
reactor in accordance with a highest permissible injection of
nitrogen in a product gas of a gasification system.
8. The method as claimed in claim 5, wherein the high operating
pressure is 40 bar.
9. The method as claimed in claim 5, wherein the nitrogen and
carbon dioxide mixture is used as an injection gas and introduced
into a plurality of powder flow lines.
10. The method as claimed in claim 5, wherein the nitrogen and
carbon dioxide mixture ratio is 75/25.
11. The method as claimed in claim 5, wherein the nitrogen and
carbon dioxide mixture ratio is 60/40.
12. The method as claimed in claim 5, wherein the nitrogen and
carbon dioxide mixture ratio is 50/50.
13. The method as claimed in claim 5, wherein the nitrogen and
carbon dioxide mixture ratio is 40/60.
14. The method as claimed in claim 5, wherein the nitrogen and
carbon dioxide mixture ratio is 25/75.
15. An arrangement for a powder injection for pulverized coal
gasification under pressure, comprising: a reservoir to which an
ambient pressure is applied, the reservoir supplies the pulverized
coal; an injection tube to which a high operating pressure may be
applied; a metering vessel to which a high operating pressure may
be applied, wherein when the high operating pressure is applied to
the metering vessel, the reservoir is heated up, wherein heated
nitrogen is fed to the reservoir as an inerting and loosening
medium, wherein a nitrogen and carbon dioxide mixture is fed to the
powder injection transfer tube as an inerting and flow medium, and
wherein the nitrogen and carbon dioxide mixture is fed to the
metering vessel as a fluidization medium.
16. The arrangement as claimed in claim 15, wherein the supplied
nitrogen and carbon dioxide mixture is heated up to a temperature
above a threshold to a two-phase region at a high process pressure
in a high-pressure region of the powder injection system.
17. The arrangement as claimed in claim 15, wherein a nitrogen and
carbon dioxide mixture ratio is dimensioned according to a highest
permitted proportion of nitrogen at a flow control unit to a
reactor in accordance with a highest permissible injection of
nitrogen in a product gas of a gasification system.
18. The arrangement as claimed in claim 15, wherein the high
operating pressure is 40 bar.
19. The arrangement as claimed in claim 15, wherein the nitrogen
and carbon dioxide mixture is used as an injection gas and
introduced into a plurality of powder flow lines.
20. The arrangement as claimed in claim 15, wherein the nitrogen
and carbon dioxide mixture ratio is 75/25.
21. The arrangement as claimed in claim 15, wherein the nitrogen
and carbon dioxide mixture ratio is 60/40.
22. The arrangement as claimed in claim 15, wherein the nitrogen
and carbon dioxide mixture ratio is 50/50.
23. The arrangement as claimed in claim 15, wherein the nitrogen
and carbon dioxide mixture ratio is 40/60.
24. The arrangement as claimed in claim 15, wherein the nitrogen
and carbon dioxide mixture ratio is 25/75.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is the US National Stage of International
Application No. PCT/EP2008/054713, filed Apr. 18, 2008 and claims
the benefit thereof. The International Application claims the
benefits of German application No. 10 2007 020 332.4 DE filed Apr.
30, 2007, both of the applications are incorporated by reference
herein in their entirety.
FIELD OF INVENTION
[0002] The subject matter of the application relates to a method
for operating a powder injection system for pulverized coal
gasification under pressure and to an arrangement for powder
injection for pulverized coal gasification under pressure with the
features of the claims.
BACKGROUND OF INVENTION
[0003] Nitrogen from the air separation unit is usually used as an
inerting and flow medium in pneumatically-operated powder injection
systems of installations for pulverized coal gasification under
pressure. This method variant has proven itself both in injection
systems for powder injection in high-level ovens and also for
pulverized coal gasification under pressure and is largely
technically mature. Advantageously in such systems the dust is
already removed in special filter vessels from the expansion gas of
the powder injection transfer tubes and also from the surplus gas
arising under specific operating conditions in the metering vessel
under increased operating pressures. Although the powder injection
systems based on pneumatic compression flow conveyance operate with
very high loading conditions, the nitrogen injected into the
gasification systems exceeds the permitted limits in many cases.
The reason for this is also the increasing process pressure in most
applications. For pulverized coal gasification under pressure, in
particular with the objective of synthesis gas generation for the
production of different hydrocarbons, the flow is produced after a
restriction of the nitrogen component in the product gas.
SUMMARY OF INVENTION
[0004] The problem underlying the subject matter of the application
is that of developing a method or an arrangement of a powder
injection system for pulverized coal gasification under pressure
such that the nitrogen injection into the subsequent gasification
system and the disadvantages associated therewith will be
restricted.
[0005] The problem is solved by the features of the claims.
[0006] Inventively the flow after limitation of the nitrogen
component in the product gas from the pulverized coal gasification
under pressure will be taken into account by using mixtures of
carbon dioxide and nitrogen as an inerting and flow medium in the
powder injection system. The sections of the plant operated with
the nitrogen/carbon dioxide mixture are heated up to the point at
which a temperature above the boundary to the two-phase region is
produced. Advantageously the invention makes use of the fact that
not all components have to be operated with the nitrogen/carbon
dioxide mixture, but instead heated-up nitrogen is fed to the
reservoir as inerting and dispersal medium--with reduced outlay
compared to carbon dioxide.
[0007] In a particular embodiment of the invention the nitrogen
N.sub.2/carbon dioxide CO.sub.2 mixture ratio is dimensioned
according to the highest allowable proportion of nitrogen at the
flow control unit to the reactor as a measure of the highest
allowable injection of nitrogen into the product gas of the
gasification system. In this case the required heating effort for
fault-free operation of the powder injection system is lowered as
the proportion of nitrogen in the mixture increases and thus the
partial pressure of the carbon reduces.
[0008] Advantageous developments of the subject matter of the
application are specified in the subclaims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The subject matter of the application is explained in
greater detail below as an exemplary embodiment in a scope required
for understanding the process which refers to a Figure. The figure
shows:
[0010] FIG. 1 a basic diagram of an inventive pulverized
coal-injection system
DETAILED DESCRIPTION OF INVENTION
[0011] A reservoir BK under ambient pressure and able to be heated
up for supply of solid material FS, such as pulverized coal for
example, is able to be supplied with heated nitrogen N.sub.2 as an
inerting and dispersal medium. The solid material is able to be fed
via a flow device to one or more powder injection transfer tubes
SES which are at a high operating pressure of for example 40 bar.
The powder injection transfer tube is able to be fed a nitrogen
N.sub.2/carbon dioxide CO.sub.2 mixture as an inerting and flow
medium with a temperature above the boundary to the two-phase
region at high operating pressure. In the upper area of the powder
injection transfer tube the expansion gas is drained away, expanded
via a multi-stage pressure relief facility mEV to ambient pressure
and dedusted in a following filter F at ambient pressure. The solid
material is transferred from the powder injection transfer tubes
into the metering vessel DG by gravity flow via a suitably
dimensioned downpipe. Between two and four powder injection
transfer tubes are used in each powder injection system.
[0012] The nitrogen N.sub.2/carbon dioxide CO.sub.2 mixture is used
as fluidization gas. A partial eddy layer is created by the
fluidization gas in the bottom part of the metering vessel. In this
process the pulverized coal is transferred from a bulk pulverized
coal state into the eddy layer and thereby simultaneously put into
the flow state. Since it has been ensured in the previous method
steps that the gap volume of the bulk pulverized coal in metering
vessel is filled with the nitrogen N.sub.2/carbon dioxide CO.sub.2
mixture and the nitrogen N.sub.2/carbon dioxide CO.sub.2 mixture is
likewise used for the fluidization, the associated gas at the flow
control unit to the reactor consists of this nitrogen
N.sub.2/carbon dioxide CO.sub.2 mixture.
[0013] The nitrogen N.sub.2/carbon dioxide CO.sub.2 mixture is also
used as injection gas. The injection gas is introduced into the
powder flow lines. Injection gas feeds can be necessary to
recognize faults of the powder feed to the reactor quickly
enough.
[0014] Inventively it is proposed to employ a carbon
dioxide-nitrogen mixture of the same composition in all method
sections of the injection system to be operated at high-pressure,
namely the powder injection transfer tube and the metering
vessel.
[0015] To lessen the risks resulting from the incidence of liquid
carbon dioxide when it is used as an inerting and flow medium in
powder injection systems or to reduce the required heating effort
for use of pure carbon dioxide, the method works with mixtures of
the two inert gas components carbon dioxide and nitrogen.
[0016] Because of the thermodynamic properties of carbon dioxide
however, a few special characteristics are to be noted in such
cases. It is to be taken into account in particular that pure
carbon dioxide at the desired process pressures of above 40 bar
already reaches the boundary to the two-phase region at ambient
temperature. To avoid this, in all process sections which will be
operated at or above the required process pressures with carbon
dioxide, sufficiently high operating temperatures are always to be
guaranteed.
[0017] The mixing of the two inerting and flow media is created in
a suitable manner and provided for use in the powder injection
system. The problems resulting from the use of carbon dioxide as an
inerting and flow gas or the heating effort required for the
fault-free operation of the powder injection system will be reduced
as the proportion of nitrogen in the mixture increases and thereby
the partial pressure of the carbon dioxide decreases.
[0018] The permitted proportion of nitrogen in the mixture is
produced from the already acceptable nitrogen injection into the
product gas of the gasification system.
[0019] Typical mixture ratios of carbon dioxide/nitrogen are 75/25,
60/40, 50/50, 40/60 or 25/75.
[0020] The carbon dioxide/nitrogen mixture is already received at
the plant boundary with a sufficiently high temperature. The
cooling-down of the gas during its application, forwarding and also
the method-specific use itself is to be counteracted by a suitable
heating system.
[0021] It is of particular importance to keep the temperature of
the pulverized coal created in the upstream dryer mill system at a
sufficient high level right through to the flow control unit FLE in
the reactor. For this reason the pulverized coal reservoir
operating at ambient pressure and with nitrogen also applied to it
as an inerting and dispersal medium is also heated Likewise the
supplied nitrogen is heated up in order to avoid powder cooling
e.g. during long plant shutdowns. Inventively an end-to-end heating
in the gas storage, forwarding and metering process sections
themselves is provided.
[0022] To exclude problems from reduced life time of filter
elements through incidence of liquid carbon dioxide as a result of
polytropic cooling-down of the medium during transfer tube
expansion, the dedusting of the expansion gas under increased
operating pressure is dispensed with.
[0023] The pressure of the slightly powder-laden expansion gas is
relieved via multi-stage expansion facilities mEV. The dedusting of
the expansion gas is subsequently undertaken in a filter F
operating at ambient pressure.
[0024] The pipe section between powder injection transfer tube and
pressure relief facility is heated, to compensate for the
polytropic expansion cold and maintain the permitted operating
conditions of the expansion filter.
[0025] The pressure relief facility is embodied so that the
expansion noises are reduced at the same time. So-called silencer
plates known in specialist circles are used as a pressure relief
facility for example. These bring about a reduction of the
expansion noises on the one hand by multi-stage expansion and on
the other hand by dividing the hole cross section required into a
plurality of smaller holes. A wear-protected control valve with
downstream silencer is also able to be used If these measures are
not sufficient additional soundproofing measures can be used, such
as by means of a sound-deadening sheathing for example.
* * * * *