Self-heat Recuperation Research Articles

Experimental and simulation investigations on self-heat recuperative fluidized bed dryer for biomass drying with superheated steam

An exergy recuperative module was developed and applied to biomass drying. The proposed drying process has an energy consumption 1/20 that of a conventional heat recovery drying system. Experimental work was conducted to confirm the details of the self-heat recuperation technology concept. A high drying rate and a stable heat exchange were found through the experimental drying results. Furthermore, the heat pairing was confirmed in the drying system for the first time.

Energy saving in a biodiesel production process based on self-heat recuperation technology

Acid-catalyzed biodiesel production processes offer a competitive alternative for biodiesel production using waste cooking oil as raw materials and are less complex than alkali-catalyzed approaches. However, acid-catalyzed biodiesel processes are not yet commercialized because of high energy requirements, especially for the recovery of excess methanol and purification of the biodiesel and glycerol. We have developed an advanced biodiesel production process with energy savings through application of self-heat recuperation technology for methanol recovery and biodiesel and glycerol purification. Both the sensible and latent waste heat were recirculated within the proposed process, significantly reducing energy requirements. Simulation showed that the total energy requirement of the proposed process was 378.7kWh per ton biodiesel, some 71% lower than that of the conventional biodiesel production process.

Reply to “Comment on ‘Application of Entransy Analysis in Self-Heat Recuperation Technology’”

Reply to “Comment on ‘Application of Entransy Analysis in Self-Heat Recuperation Technology’”

Comment on “Application of Entransy Analysis in Self-Heat Recuperation Technology”

Comment on “Application of Entransy Analysis in Self-Heat Recuperation Technology”

Energy saving analysis for a solution evaporation system with high boiling point elevation based on self-heat recuperation theory

This paper focuses on the application of self-heat recuperation theory (SHRT) in mechanical vapor recompression (MVR) evaporation systems when used to concentrate solutions with boiling point elevation (BPE). A nonlinear model is presented and used to analyze the advantages of heat recovery and multi-stage MVR over single-stage MVR. The model is then used to optimize the number of stages, evaporation temperatures, heat transfer temperature differences and stage concentration changes in relation to the compressor energy requirements. In comparison with single-stage MVR and conventional three-effect evaporation, multi-stage MVR with SHRT is shown to offer advantages when the number of stages is large, the evaporation temperatures are high and a large mass concentration difference between the outlet and inlet is required. However, the SHRT-based MVR system does not always yield energy savings when dealing with an inorganic salt solution with high BPE. A case study on concentrating a calcium chloride solution indicates that the SHRT-based MVR system uses more energy when the inlet mass fraction is over 38% compared to the conventional three-effect evaporation technology.

Analysis of energy saving for ammonium sulfate solution processing with self-heat recuperation principle

As an important production process, the evaporative concentration of the inorganic salt solution is extensively applied in the industry, and it is significant to investigate the energy saving potential of such evaporation systems. In the paper, taking the ammonium sulfate solution for example, the self-heat recuperation technology (SHRT) is utilized to design two mechanical vapor recompression (MVR) systems, and the relevant energy saving performance is analyzed. It is found that the designed systems, which are satisfied with SHTR, enable the recovery of the sensible and latent heat of the emission solution without any additional heat, and compared to the conventional three-effect evaporation system, the energy saving performance are more prominent. However, in view of the existence of the boiling point elevation (BPE) for the inorganic salt solution, a maximum reduction amplitude of 40% of the energy saving performance for the double-stage MVR system is obtained compared with the single-stage MVR system. As a result, it is concluded that the only satisfaction to the SHRT is not enough, and the pattern of the MVR system should also be considered to ensure a prominent energy saving performance.

An Innovative Dimethyl Ether (dme) Production Using Self-heat Recuperation

Dimethyl ether (DME) has been categorized as a green energy source, and the demand of the DME continue increasing. In this research, we investigated the feasibility of applying self-heat recuperation technology to DME production process using indirect method and developed an innovative process for DME production process from the energy saving point of view. By installing the self-heat recuperation technology to the DME production process, the energy consumption of the thermal and separation processes can be greatly reduced.

An innovative methanol synthesis process based on self-heat recuperation

The demand for methanol will continue to increase since methanol is an attractive fuel for fuel cells in addition to being an intermediate raw material for hydrogen and dimethyl ether (DME), which are categorized as green energy sources. To produce methanol with a minimum amount of energy, it is necessary to investigate and reconsider a whole methanol synthesis process from energy saving point of view. Recently, we developed an innovative process design technology referred to as self-heat recuperation technology for saving energy. To apply this technology, whole-process heat is recirculated within the process without heat addition leading to large energy savings. In this paper, the feasibility of applying self-heat recuperation technology to the methanol synthesis process is investigated and an innovative process for methanol synthesis is developed from an energy saving point of view. The use of this self-heat recuperation technology in the methanol synthesis process greatly reduces the energy consumption.

Simplification and Energy Saving of Drying Process Based on Self-Heat Recuperation Technology

A simplified drying process based on self-heat recuperation (SHR), which can further reduce energy consumption compared to previous SHR drying processes, is proposed. The specific energy consumption (SEC) of the SHR drying process was evaluated at various air flow rates and compared with a mechanical vapor recompression (MVR) drying process with superheated steam. The results show that the SEC of SHR can be reduced from 474 to 147 kJ (kg-H2O evaporated)−1 by removing heat exchangers for preheating. The SEC of the simplified SHR process was only 1/16 of a conventional drying process with heat recovery and 3/5 of an MVR process. Exergy transfer of the process was also analyzed and summarized as exergy flow diagrams.

Experimental investigation of an active magnetic regenerative heat circulator applied to self-heat recuperation technology

An experimental investigation into an active magnetic regenerative (AMR) heat circulator based on self-heat recuperation technology, was conducted to evaluate its energy saving potential in heat circulation. In an AMR heat circulator, magnetocaloric effect is applied to recuperate the heat exergy of the process fluid. The recuperated heat can be reused to heat the feed process fluid and realize self-heat recuperation. In this paper, AMR heat circulator has newly been constructed to determine the amount of heat circulated when applied to self-heat recuperation and the energy consumption of the heat circulator. Gadolinium and water was used as the magnetocaloric working material and the process fluid, respectively. The heat circulated amount was determined by measuring the temperature of the process fluid and gadolinium. The net work input for heat circulation was obtained from the magnetizing and demagnetizing forces and the distance travelled by the magnetocaloric bed. The results were compared with the minimum work input needed for heat circulation derived from exergy loss during heat exchange. It was seen that the experimentally obtained value was close to the minimum work input needed for heat circulation.

An Advanced Cryogenic Air Separation Process Based on Self-heat Recuperation for CO2 Separation

An advanced cryogenic air separation process for oxy-combustion is proposed based on self-heat recuperation technology. Compared with the conventional double-column cryogenic air separation process, only one distillation column is used in the proposed process. The heat of N2 product gas from the top of the distillation column is recirculated by exchanging latent heat with the liquid O2 in the bottom and feed streams, largely reducing the energy consumption. The simulation results showed that the energy consumption of the proposed cryogenic air separation process was decreased by 30% comparing with the conventional process, when producing O2 with low purity (95 mol%) and low pressure (120kPa).

Self-heat Recuperative Heat Circulator with Thermoelectric Device

Self-heat recuperation (SHR) technology has been proven to reduce exergy loss in different process systems, which lead to large energy savings due to its non-combustion process. The purpose of this research is to develop a novel self-heat recuperative heat circulation system using thermoelectric (TE) device as a heat circulator for non-gaseous systems. Most research involving TE coolers is related to maximizing the temperature difference (ΔT) of a device, whereas in self-heat recuperative heat circulator, a large ΔT is not required, but only a minimum temperature difference between the surfaces of the TE device and process fluid (ΔTmin) for self-heat exchange is required in order to use it as a heat circulator. The lower ΔT can improve COP of TE devices significantly.

Design of a Low-cost CO2 Capture Process Based on Heat Integration Technology

CO2 capture and storage (CCS) technology has attracted attention to mitigate CO2 emission. Among the dominant CO2 capture technologies, pressure swing adsorption (PSA) is a promising alternative but requires still intensive energy consumption. In this study, a novel self-heat recuperation technology has been applied to the PSA process to reduce the CO2 capture cost. The detailed energy input of the proposed process is simulated using a commercial process simulator (PRO/II, Invensys). The simulation results indicate that the heat of adsorption stage (exothermic reaction) can be significantly recovered by reaction heat transformer (RHT), and reused for adsorbent regeneration (endothermic reaction). Meanwhile, an expander is added to recover wasted pressure associated with residual gas. As a result, the energy consumption of the proposed process is reduced to 40% of that of the conventional process.

Advanced Energy Saving in the Evaporation System of Ammonium Sulfate Solution with Self-heat Recuperation Technology

A concept of a novel double-stage mechanical vapor recompression (MVR) evaporation system based on the principles of self-heat recuperation technology for ammonium sulfate solution processing is proposed. In the paper, the single-stage and double-stage MVR evaporation systems for ammonium sulfate solution are designed and analyzed. A parametric study is performed to investigate the effects from the emission concentration of the first stage, the evaporation temperature and the temperature difference (TD) between the condensing steam and the boiling solution on the power consumption and heat transfer. During the investigation, the initial ammonium sulfate solution with a concentration of 3% is concentrated to the saturation solution, which has a concentration of 53%. The results show that despite the satisfaction to the principle of self-heat recuperation technology for the two systems, the boiling point elevation will result in a high energy consumption for the compressor in the single-stage MVR system, while the double-stage MVR evaporation system has an obvious energy saving effect with an improved amplitude of 40%.

Application of Entransy Analysis in Self-Heat Recuperation Technology

Aside from the introductory and concluding remarks, this article is divided into four sections. Following a brief description of the concepts of entransy and entransy dissipation, which measures th...

Development of Innovative Methanol Synthesis Process Based on Self-Heat Recuperation

In recent years, the demand for methanol will continue increasing. As well as other chemical processes, many methanol synthesis processes have reactant recycle system with product separation due to the low conversion ratio of the reactor. For this product separation from reactant recycle stream, a gas-liquid separator or distillation process has often been used. However, this gas-liquid separator and distillation processes are well known as an energy intensive process. Thus, many chemical engineers and investigators have been managing to produce a catalyst which achieves high conversion from reactant to production in the reactor for whole process optimization. In contrast, authors have developed self-heat recuperation technology based on exergy recuperation, in which whole process heat is utilized without any additional heat, leading to the reduction of energy requirement in several chemical processes. In this research, we developed an innovative integrated process design method based on self-heat recuperation for methanol synthesis process from energy saving point of view.

6-1-3 自己熱再生によるメタノール合成プロセスの省エネルギー化(6-1 省エネ技術,Session 6 省エネルギー)

6-1-3 自己熱再生によるメタノール合成プロセスの省エネルギー化(6-1 省エネ技術,Session 6 省エネルギー)

A novel NGL (natural gas liquid) recovery process based on self-heat recuperation

This study examined an innovative self-heat-recuperation technology that circulates latent and sensible heat in the thermal process and applied it to the NGL (natural gas liquid) recovery process. A CGCC (column grand composite curve) was used to assess the thermodynamic feasibility of implementing the heat pump system and self-heat-recuperation technology into a conventional distillation column. The proposed distillation based on self-heat recuperation reduced the energy consumption dramatically by compressing the effluent stream, whose temperature was increased to provide the minimum temperature difference for the heat exchanger, and circulating the stream heat in the process. According to a simulation of the proposed sequence, up to 73.43 and 83.48% of the condenser and reboiler energy, respectively, were saved compared to a conventional column. This study also proposes heat integration to improve the performance of self-heat recuperation. The results showed that the modified sequence saves up 64.35, 100.00 and 31.60% of the condenser energy requirements, reboiler energy requirements and OP (operating cost), respectively, compared to a classical heat pump system, and 90.24, 100.00, and 67.19%, respectively, compared to a conventional column. The use of these sequences to retrofit a distillation column to save energy was also considered.

Magnetocaloric heat circulator based on self-heat recuperation technology

A concept of a novel magnetocaloric heat circulator based on self-heat recuperation technology for application in thermal processing is proposed. In the heat circulator, process heat is recirculated by using the magnetocaloric effect of ferromagnetic materials subjected to cyclic magnetization and demagnetization. The ferromagnetic material is magnetized or demagnetized adiabatically at the highest or lowest process temperature to create the temperature difference required for heat exchange so that all heat is recirculated inside the thermal process without heat addition. The magnetocaloric heat circulation cycle has been analyzed in terms of the temperature–entropy diagram to evaluate its energy consumption. Simulation has been conducted to clarify the theoretical potentials of applying magnetocaloric effect to self-heat recuperation. The simulation results show that the total energy consumption of the magnetocaloric heat circulator is reduced below 1/5 compared to conventional processes with heat recovery, thus showing its potential for energy saving in thermal processes.

Conceptual design of an active magnetic regenerative heat circulator based on self-heat recuperation technology

A conceptual design of an active magnetic regenerative (AMR) heat circulator for self-heat recuperation to realize energy savings in thermal processes is proposed. The process fluid heat is recuperated by the magnetocaloric effect of ferromagnetic material through the AMR heat circulation cycle. In an AMR heat circulator, all the process fluid heat is circulated and no make-up heat is added to raise the process fluid to its set temperature. A one-dimensional mathematical model of the AMR heat circulator was constructed to understand its behavior and verify its energy-saving potential. From the constructed one-dimensional mathematical model, it is seen that AMR heat circulator has potential to drastically reduce the total energy consumption in a thermal process. The temperature–entropy diagram shows that in order to gain the maximum energy saving, optimization of the parameters such as the flow rate and geometry of the ferromagnetic working material beds is needed.