Mitsubishi Heavy Industries Technical Review Vol. 59 No. 4 (December 2022)
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Initiatives to Apply Small Scale CO2 Capture System toIndustrial Emission Sources

NORIAKI SENBA*1

HIROMITSU NAGAYASU*1

MASAYUKI INUI*2

TAKAHITO YONEKAWA*3

Mitsubishi Heavy Industries, Ltd. (MHI) Group has delivered its proprietary CO2 capture
process, KM CDR ProcessTM, to coal-fired power plants and chemical plants so far. Based on thistechnology, MHI is advancing the development of small-scale CO2 capture systems to respond tothe needs for the reduction of CO2 emissions at smaller-scale CO2 emission sources such as gas
engines, biomass boilers and refuse incinerators.

|1. Introduction
In the recent trends toward decarbonization and CO2 emissions reduction, goals have been
set for a reduction in anthropogenic CO2 to one third in 2040 (compared to 2014) and for theachievement of so-called carbon neutrality in 2060. Figure 1 shows the CO2 emissions reduction
required for the realization of the 1.5℃ scenario under the Paris Agreement(1). To achieve thesegoals, it is necessary to reduce emissions concurrently in various fields as well as reducingemissions at large-scale emission sources such as thermal power plants. In addition, needs for thereduction of CO2 emissions at smaller-scale CO2 emission sources such as gas engines, biomass
boilers and refuse incinerators have arisen.

Figure 1 CO2 emissions reduction required for the realization ofthe 1.5℃ scenario(Comparison between BAU*1 and 1.5℃ scenario by IEA)
*1

Chief Staff Researcher, Chemical Research Department, Research & Innovation Center, Mitsubishi Heavy Industries, Ltd.

*2

Chief Staff Manager, Business Development Department, Growth Strategy Office, Mitsubishi Heavy Industries, Ltd.

*3

Deputy Director, Decarbonization Business Department, Mitsubishi Heavy Industries Engineering, Ltd.

Mitsubishi Heavy Industries Technical Review Vol. 59 No. 4 (December 2022)2

Mitsubishi Heavy Industries Engineering, Ltd. in the MHI Group has delivered a proprietary
CO2 capture process, KM CDR ProcessTM, to coal fired power plants and chemical plants. The
scale of plants delivered so far is approximately 500t-CO2/day or larger.
Based on this technology, MHI is advancing the development of small-scale CO2 capturesystems to realize the concurrent CO2 reductions and also respond to the reduction needs atsmall-scale CO2 emission sources.

|2. Features of small-scale CO2 capture systems
The basic process of a small-scale CO2 capture system under development is the same as thatof a large-scale plant, but the following features are required for a small-scale system:(1) Applicable to many emission sources(2) Installable at a limited area
(3) Operable without full-time operators
In order to respond to various inquiries, we adopted a standard design of small-scale systems,
not a design according to each customer's specification adopted in conventional large-scale plants.
In addition, we realized a system with a compact design by modularization so that it can beinstalled at a smaller area. The modularization can produce the effects of reducing field works andadvancing the commencement of system operation. Furthermore, it eliminates the need for storagesites for construction materials, etc.
The small-scale system is equipped with an automatic operating and remote monitoring
system, thereby allowing operation without any full-time operator.
We built a lineup of standardized systems with the scales of 0.3, 3, 30, 100 and 200t-CO2/day
as shown in Table 1 (Figures 2 and 3). Selection of a system from this lineup will allow quick
delivery and installation of the system because only pretreatment equipment such as dust removal
device is newly designed.
Table 1

Lineup of products

TypeStandard CO2 capture amount (*1)
A
0.3 tonnes/dayB
3 tonnes/day
C30 tonnes/day
D
100 tonnes/day
E
200 tonnes/day*1: CO2 capture amount may be changed by inlet gas
conditions.

Figure 2 Small-scale CO2 capture system(0.3t-CO2/day)Figure 3 Small-scale CO2 captureplant (30t-CO2/day)|3. Automatic operating/remote monitoring system
Conventional large-scale CO2 capture plants have been delivered to chemical plants orcoal-fired power plants. At these plants, there are many workers involved in the operation and it isrelatively easy to secure operators for a newly installed CO2 capture plant. On the other hand, for acombustor to which a small-scale CO2 capture system is installed, only a few workers are involvedin the operation and if they have to operate a newly installed CO2 capture system, their workload
will be increased. Also, it is difficult to add new operators in many cases. Besides, there areMitsubishi Heavy Industries Technical Review Vol. 59 No. 4 (December 2022)
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problems that most of customers using small-scale combustors are unfamiliar with CO2 capturesystems and do not have know-how about its operation and system management.
In addition, the start and stop operation is different between a combustor to which asmall-scale CO2 capture system is installed and a chemical plant or coal-fired power plant. A
small-scale combustor is frequently started and stopped and often operated in DSS (Daily Start &Stop) mode, while a chemical plant or coal-fired power plant is less frequently started and stopped
and operated with little load change for a long time in most cases. At a large-scale plant, a CO2
capture plant is required to deliver stable performance in a long-time operation, while at asmall-scale combustor, it is required to start and stop easily and operate at a necessary load whenneeded.
To address such needs, our small-scale CO2 capture system is equipped with an automatic
operating and remote monitoring system (Figure 4) as standard, reducing field operations to aminimum. The system can be started and stopped only by pressing the start/stop button and it can
automatically operate when the temperature or pressure in the system changes.

Figure 4 Overview of the remote monitoring system

Concerning the remote monitoring system, we are developing a reliable system without
much new design by using the systems developed for conventional large combustors. Specifically,TOMONI®, which is used for thermal power plants, is used to monitor the operation of CO2
capture plants. We also set up a remote monitoring team and have commenced a test operation toprepare for full-scale operation in the near-future. Thus, it becomes possible to monitor and checkthe operation status of the system with a small number of workers. With the acquisition ofoperation data over time as well as the alarm monitoring for various abnormal values, we plan toimplement management of the absorbing solution, which will be needed in the medium and longterms.

|4. Dealing with properties of gases
The properties of gases generated from the CO2 emissions sources such as gas engines,marine engines, biomass boilers and refuse incinerators, to which the small-scale CO2 capturesystems are installed, are different from those of gases from chemical plants or coal-fired thermalplants. To deal with such properties of gasses, we have been conducting application tests insequence. For the tests, the smallest-scale system of 0.3t-CO2/day in the standard lineup is used.
We conducted tests for marine engines and biomass boilers and extracted issues (on removalof dust, etc.) to be addressed for application of the systems(2). We have also conducted tests forapplication to gas engines at our Sagamihara Machinery Works Sagamihara Plant since July 2022
(Figure 5). In the tests for gas engines, validation of the previously described automatic
operating/remote monitoring system has also been conducted. So far, the operation status has been

Mitsubishi Heavy Industries Technical Review Vol. 59 No. 4 (December 2022)
4favorable and it has been demonstrated that the system can achieve a satisfactory CO2 capture. We
will continue further tests and evaluate the applicability to exhaust gas from gas engines. Inaddition, we are conducting application tests for cement kiln in cooperation with Tokuyama
Corporation.
A demonstration test for refuse incinerator in Yokohama City is also being planned.

Figure 5

Small-scale CO2 capture system (for gas engine)|5. Conclusion
The MHI Group has been advancing the development of small-scale CO2 capture systems
based on its proprietary CO2 capture process, KM CDR ProcessTM. In the development, we havebeen studying aiming at development of products suited to the needs of small-scale systems by (1)offering a lineup of products with standard specifications, (2) making products compact andreducing field works by modularization and (3) installing an automatic operating/remotemonitoring system.
To validate the applicability to actual small-scale combustors, we are implementing andplanning demonstration tests with gas engines, marine engines, biomass boilers, refuse incinerators,etc.
Many of these small-scale combustors are manufactured within the MHI Group and MHIGroup companies have cooperated in developing optimal systems including CO2 capture plants.
KM CDR ProcessTM is a registered trademark of Mitsubishi Heavy Industries, Ltd. in Japan and othercountries and a registered trademark of Kansai Electric Power Co., Inc. in Japan, the European Community(CTM), Norway, Russia and Australia.
TOMONI® is a registered trademark of Mitsubishi Heavy Industries, Ltd. in Japan and other countries.

References(1)(2)

Energy technology Perspective 2017，IEA
Senba et. Al, CO2 Capture Technology Applied for Varied Fields such as Manufacturing Industries andEnergy-related Facilities, Mitsubishi Heavy Industries Technical Review Vol. 59 No. 1 (2022)