Workflow Design and Operational Analysis of a Coal‐Based Multi‐Energy Combined Supply System for Electricity, Heating, Cooling, and Gas

Abstract

ABSTRACT

The combined cooling, heating, and power (CCHP) system, as a typical representative of novel distributed energy systems, demonstrates significant advantages in the cascade utilization of energy and the control of transmission and distribution losses. However, the inherent reliance of traditional CCHP systems on natural gas as fuel structurally conflicts with China's energy endowment, characterized by abundant coal and scarce natural gas, severely limiting their large‐scale application. To adapt to this energy consumption profile and fully leverage the strengths of CCHP systems, this study establishes a coal‐fueled electricity‐gas‐heating‐cooling polygeneration system based on physical and mathematical models within the Aspen Plus 9.0 commercial simulation platform. The reliability of the proposed model is validated through comparisons with data from relevant literature. To identify the optimal operating parameters, the effects of coal‐water slurry concentration and oxygen‐to‐coal ratio on key gasification indicators (e.g., gasifier temperature, syngas composition, syngas calorific value, and cold gas efficiency) and system output loads (e.g., electricity, heating, cooling, and municipal gas) are systematically investigated. Finally, a comprehensive simulation of the entire system is conducted, with energy and exergy analyses performed on major functional units. The results indicate that coal‐water slurry concentration and oxygen‐to‐coal ratio significantly influence gasifier temperature, syngas composition, calorific value, and cold gas efficiency. The system achieves optimal performance at an oxygen‐to‐coal ratio of 1.05 and a coal‐water slurry concentration of 65%. Under design conditions, the system attains a comprehensive energy efficiency of 66.18% and an exergy efficiency of 34.43%. This study provides an innovative solution to address technological bottlenecks in China's energy transition, not only enhancing the efficiency of clean coal utilization but also offering a new technical pathway for coal‐fired power transformation under the “dual carbon” goals (carbon peaking and carbon neutrality).

Introduction

Energy serves as both a driver of social development and an essential requirement for sustaining and enhancing human life and social stability [1]. Coal, notable for its abundant reserves and affordability, plays a significant role in the energy sector [2]. The main method of coal utilization is combustion, which provides thermal energy, but also poses risks to human health and the environment [3, 4]. Combustion of coal emits substantial pollutants, including sulfur dioxide (SO₂), nitrogen oxides (NO_x), particulate matter (PM), and volatile organic compounds (VOCs). These pollutants contribute to environmental degradation and provoke issues such as smog and acid rain [5]. Moreover, carbon dioxide (CO₂) emissions from coal combustion are a primary greenhouse gas, intensifying the greenhouse effect and hastening global warming [6]. Hence, the active development of clean coal technologies is among the vital challenges currently confronting the global community [7].

Coal gasification is an important means of clean utilization of coal [8]. In the gasification process, solid coal reacts with a certain amount of oxygen, air, steam, carbon dioxide, or a mixture of these gases at temperatures of 700°C or higher, producing combustible synthesis gas (mainly H₂ and CO). The synthesis gas is purified of H₂S, NH₃, and particulate matter, and can be used as fuel for combustion [9]. Compared to the traditional direct combustion of coal, gasification processes can significantly reduce pollutant emissions from coal-fired plants. Moreover, under a certain thermal load, the volume of gas emitted by the gasification process is smaller than that from direct coal combustion, allowing the use of smaller equipment to meet demand, thereby reducing the overall cost [10]. To fully exploit the advantages of coal gasification, the conventional method involves using an integrated gasification combined cycle (IGCC) system for power generation [11].

Combined Cooling, Heating, and Power (CCHP) systems represent a new type of distributed energy system that can simultaneously provide different forms of energy, such as cooling, heating, and electricity, considered as an alternative to traditional electricity and thermal production models. In the production process, these systems achieve cascading energy utilization, reducing energy transmission losses and investment costs. Compared to independent power generation at large power plants, such systems have higher overall efficiency, thus possessing promising development prospects [12, 13]. Traditional CCHP systems use natural gas as fuel, which has the advantages of being clean, high calorific value, and easy transportation [14]. However, for countries rich in coal resources but lacking natural gas resources (like China) [15], constructing large-scale CCHP systems powered by natural gas is not feasible. Thus, seeking alternative fuels to natural gas is an urgent need.

The primary combustible component of natural gas is CH₄, whereas H₂ and CO are the main combustible components of coal gasification synthetic gas. Despite their different compositions, both gases have similar combustion and emission characteristics [16]. Replacing natural gas turbines with coal gasification synthetic gas turbines in Combined Cooling, Heating, and Power (CCHP) systems allows for the use of coal gasification synthetic gas as a primary energy source, offering a viable option for countries like China.

Coal gasification is an effective method for converting coal into clean synthetic gas, and it is gaining increasing attention. The CCHP system, integrating cooling, heating, and power supply, is a prominent topic in the comprehensive energy utilization field. It is expected that a coal-based CCHP system that uses multiple energy flows from coal gasification could effectively promote energy conservation and emission reduction, enhancing the clean and efficient use of coal with considerable development potential. Furthermore, clean coal gasification synthetic gas could also be directly supplied to residents as domestic gas [17], a topic not commonly addressed in traditional CCHP research.

The objective of this study is to integrate coal gasification technology with polygeneration technology, proposing a novel coal-based multi-energy flow polygeneration system (gas-heating-electricity-cooling) on the Aspen Plus 9.0 commercial simulation platform. This system is designed to directly supply gas to end-users while incorporating modeling, sensitivity analysis, and thermodynamic analysis to technically evaluate its operational feasibility. The research provides an innovative solution to address technological bottlenecks in China's energy structure transition, not only enhancing the efficiency of clean coal utilization but also offering a new technical pathway for coal-fired power transformation under the “dual carbon” goals (carbon peaking and carbon neutrality). Furthermore, it presents a novel and viable approach for comprehensive coal utilization in countries, including China, that are rich in coal resources but lack natural gas reserves.

Modeling of Coal-Based Multi-Energy Supply Technology

Figure 1 illustrates a schematic of a coal-based multi-energy cogeneration system that integrates gas, heat, electricity, and cooling. The system's complexity and high level of integration necessitate initial construction of various functional units, each tasked with specific functions. These units are organically combined to form a comprehensive coal gasification-based multi-energy cogeneration system, as depicted in Figure 2. The primary units include the coal-water slurry preparation unit, coal gasification unit, syngas purification unit, and the integrated gas-heat-electricity-cooling supply unit.

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The operational process is as follows: Raw coal is pulverized into coal powder and mixed with water in a mill to form a specific concentration of coal-water slurry in the preparation unit [18]. This slurry reacts with oxygen from an air separation device in a gasifier, generating crude syngas [19]. After purification to remove harmful components in the syngas purification unit, the resulting clean syngas is partly supplied directly to consumers as commercial gas for municipal or industrial use. The remainder enters the combustion chamber of a gas turbine, burning to produce high-temperature, high-pressure exhaust gases that drive a generator for electricity production. The remaining heat in the exhaust gases is further utilized; some is used to power a dual-effect LiBr absorption chiller to generate cooling energy, while the rest is transferred through a heat exchanger to produce thermal energy [20], thereby facilitating a multi-energy supply of gas, electricity, heat, and cooling.

The system is segmented into four distinct units for modeling: the coal-water slurry preparation unit, the coal gasification unit, the syngas purification unit, and a multifunctional unit for the combined generation of coal gas, heat, electricity, and cooling. The description of these units’ modeling is as follows: Coal gasification is essential for developing a new multi-energy flow system utilizing coal. Selecting a gasification technology involves various factors, with coal type flexibility often being the least variable [21]. Therefore, the selection typically depends on the specific characteristics of the coal under consideration. This study uses coal from Fushun, Liaoning Province, China. The industrial and elemental analyses of this coal are detailed in Table 1. Given the properties listed in Table 1, this study has chosen the Texaco coal-water slurry gasification technology, noted for its robust adaptability to various raw materials, high efficiency in gasification, and superior syngas quality, applying it within a fluidized bed gasification approach.

Table 1 Properties of coal used in the system.

Proximate analysis (wt.%)	Ultimate analysis (wt.%, LHV(MJ/kg))
Moisture	VM	FC	Ash	C	H	O	N	S	LHV
2.1	35.7	50.5	11.7	69.71	4.8	8.59	1.4	3.64	27.93

Coal Water Slurry Preparation Unit

The Aspen Plus diagram for preparing a coal-water slurry is depicted in Figure 3. This process involves conventional, unconventional, and solid components, thus the choice of MIXNCPSD for the stream type [22]. Property calculations for solids utilize the SOLIDS method, and for conventional components, the PR-BM method is applied. This method uses the Peng-Robinson cubic state equation along with the Boston-Mathias alpha function for all thermodynamic properties calculations [23]. For unconventional components like coal and ash, the models HCOALGEN (coal enthalpy) and DCOALIGT (coal density) are employed. The simulation relies on databases such as COMBUST, AQUEOUS, SOLIDS, inorganic, NIST-TRC, and PURE37. The Barin equation calculates the physical properties of solids. Initially, coal is processed in a crusher to reduce its size below 30 mm. The crushed coal is then mixed with water and sent to a mill for wet grinding to produce coal-water slurry [24], with the mill represented by the Crusher module. Post-grinding, coal particle size is limited to 0.2 mm. The suitably sized coal-water slurry is filtered and directed to a gasifier for gasification, while oversized particles are returned to the mill for regrinding. The filtering system uses a Screen module, with screen holes sized at 0.3 mm.

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Coal Gasification Unit

Coal gasification involves the partial oxidation of coal into combustible gases, primarily CO and H₂, under high temperatures and pressures through reactions with gasifying agents such as oxygen, air, steam, and CO₂, or their combinations [25]. This process encompasses two primary stages: pyrolysis and gasification combustion. Initially, coal breaks down into volatile components such as CO, CO₂, CH₄, H₂O, H₂, H₂S, NH₃, and tar, along with solid residues like semi-coke, a process termed pyrolysis. Gasification combustion refers to the complex series of chemical reactions between the volatile matter and char produced from pyrolysis and the gasifying agents, leading to the generation of combustible gases [26]. This study models the key physical and chemical processes in a gasifier, namely coal pyrolysis, gasification combustion, and slagging. The modeling assumptions include: (1) Instant and complete mixing of gas and solid phases. (2) Ignoring pressure drops within the gasifier. (3) Disregarding solid residence time. (4) Omitting the duration needed for the gasification reactions. The principal chemical reactions occurring in the gasifier are detailed below [27].

• 1.

  Pyrolysis or devolatilization I$\mathrm{Coal}\stackrel{\mathrm{Heating}}{⟶}\mathrm{Volatile} \mathrm{matter}\left(\mathrm{CO},{\mathrm{CO}}_2,{\mathrm{H}}_2,{\mathrm{H}}_2\mathrm{O},{\mathrm{CH}}_4, \mathrm{et} \mathrm{al}.\right)+\mathrm{Semicoke}.$

• 2.

  Combustion reaction II$\mathrm{C}+{\mathrm{O}}_2\leftrightarrow {\mathrm{CO}}_2 \Delta H=-\text{393.5\hspace{0.05em}kJ}/\text{mol.}$ III$2{\mathrm{H}}_2+{\mathrm{O}}_2\leftrightarrow {\mathrm{H}}_2\mathrm{O} \Delta H=-\text{285.9\hspace{0.05em}kJ}/\text{mol.}$

• 3.

  Water gas shift reaction IV$\mathrm{C}+{\mathrm{H}}_2\mathrm{O}\leftrightarrow {\mathrm{H}}_2+\mathrm{CO} \Delta H=\text{118.5\hspace{0.05em}kJ}/\text{mol.}$

• 4.

  Boudouard reaction V${\mathrm{CO}}_2+\mathrm{C}\leftrightarrow 2\mathrm{CO} \Delta H=\text{159.0\hspace{0.05em}kJ}/\text{mol.}$

• 5.

  Methanation VI$\mathrm{CO}+2{\mathrm{H}}_2\leftrightarrow {\mathrm{CH}}_4 \Delta H=-\text{74.5\hspace{0.05em}kJ}/\text{mol.}$

• 6.

  Shift conversion VII$\mathrm{CO}+{\mathrm{H}}_2\mathrm{O}\leftrightarrow {\mathrm{CO}}_2+{\mathrm{H}}_2 \Delta H=-\text{42.3\hspace{0.05em}kJ}/\text{mol.}$

• 7.

  Steam Methane Reforming VIII${\mathrm{CH}}_4+{\mathrm{H}}_2\mathrm{O}\leftrightarrow \mathrm{CO}+3{\mathrm{H}}_2 \Delta H=\text{206.1\hspace{0.05em}kJ}/\text{mol.}$

The final composition of the syngas is primarily influenced by reactions 6 and 7, where S in the coal is converted into H₂S and a minor amount of carbonyl sulfide. The coal gasification unit's Aspen Plus process flow is illustrated in Figure 4. The flow section type MIXCINC is selected, and the property method used is PR-BM. The RStoic reactor model simulates the coal's pyrolysis process. Assuming simplification for computation, coal in the RStoic reactor decomposes into steam, C, S, N₂, H₂, O₂, and ash. Based on onsite measurements, the coal conversion rate is set at 0.99, with unconverted coal and ash treated as inert, non-reacting components. Reaction stoichiometries are computed using the Calculator module in Aspen Plus. Owing to the complex, kinetically unknown reactions involved in the gasification combustion of coal pyrolysis products, these products are processed in a Gibbs reactor (RGibbs) to simulate the gasification combustion process. Calculations in the Gibbs reactor are based on minimizing Gibbs free energy to identify potential products and their compositions under equilibrium conditions [28]. The oxidants needed for gasification, composed of 95.0% oxygen and 5.0% nitrogen, are supplied by an air separation unit (ASU) and pressurized in a compressor before being introduced into the gasifier. The high-temperature syngas from the gasifier is cooled in a quench chamber (QC), yielding crude syngas. Slag settles into the water pool at the gasifier's bottom, separating slag (ash and unreacted coal) from the products. The bottom water pool is simulated using the Sep module, with slag ultimately removed via a slag removal system.

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Synthesis Gas Purification Unit

As illustrated in Figure 5, the main role of the synthesis gas purification unit is to remove acidic gases such as CO₂, Cl₂, HCl, NH₃, H₂S, COS, and HCN from raw synthesis gas [29]. This is crucial for fulfilling the quality standards required for municipal and industrial use. Acidic gases are eliminated using a low-temperature methanol washing technique [30]. The unit's flow scheme type is designated as CONVEN, employing the PR-BM property method and utilizing the Rad Frac module to simulate both the acidic gas and CO₂ absorption columns. The purification process involves crude synthesis gas initially entering a water wash unit (WASH), where a dilute ammonia solution extracts HCl, Cl₂, and some sulfides. The resulting wastewater is expelled from the bottom of the unit. Following this, the gas, now somewhat purified, is directed through a heat exchanger (SG-HTX), where it undergoes heat exchange with the cleaned synthesis gas before being routed to the bottom of the acidic gas absorption column (H₂SAB). It merges with circulating gases from the CO₂ absorption column (CO₂AB) and encounters the absorbing agent (a low-temperature methanol solution enriched with CO₂) from above, enabling the absorption of acidic gases (CO₂ and H₂S). The enriched H₂S solution is drained from the bottom of the column, with recovered sulfur subsequently utilized as a chemical feedstock. The gas, now devoid of H₂S, exits the top of the H2SAB column and enters the CO₂ absorption column (CO₂AB) to remove CO₂. The now-clean synthesis gas is then reheated in the heat exchanger (SG-HTX) with the crude synthesis gas before progressing to the next stage. The concentrated CO₂ solution extracted from the bottom of the column is processed in the CO₂ separation device (CO₂SPLT), separating CO₂ and methanol; the CO₂ is reclaimed, and methanol is recycled for further use [31].

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Multi-Energy Combined Supply Unit

The gas-heat-electricity-cooling cogeneration unit is shown in Figure 6. In this unit, the stream type is selected as CONVEN. The property method for the double-effect LiBr absorption chiller model employs the ELECNRTL method, while other models utilize the PR-BM method. Within the setup depicted in Figure 6, the combustion chamber is represented through the RStoic reactor model. The turbine generator is modeled using the Compr turbine model, the air compressor is depicted using the Compr compressor model, and the Heatx model portrays the flue gas-water heat exchanger in the heating system.

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After purification by the synthesis gas cleaning unit, the purified synthetic gas enters a distributor. A portion serves as municipal gas, while another flows into the combustion chamber where it combines with compressed high-pressure air from an air compressor. This mixture ignites combustion reactions, producing high-temperature and high-pressure flue gases. These gases power a gas turbine, which drives an electricity generator. Post-power generation, the gases pass through a flue gas distributor and are divided into two streams. One stream feeds into a double-effect LiBr absorption chiller, creating chilled water. The second stream moves into a flue gas-to-hot water heat exchanger, generating hot water for users and achieving a multi-energy co-generation system encompassing gas, heat, electricity, and cooling [32].

Besides the flue gas-hot water heat exchanger and the gas turbine generator unit, the system also includes a double-effect LiBr absorption refrigeration unit. The high-temperature flue gas generated by the gas turbine after power generation is used for cooling in the double-effect LiBr absorption chiller. Absorption chiller sets are classified by heat supply method into hot water, steam, direct-fired, and flue gas types [33]. In this study, the heat source is the high-temperature flue gas produced after gas turbine power generation; thus, the flue gas type refrigeration unit is selected. The flue gas type refrigeration unit fully utilizes the waste heat of the generated high-temperature flue gas and does not require additional auxiliary equipment for energy [34].

The double-effect LiBr absorption refrigeration unit is shown in Figure 7. The Flash2 module is used to simulate the high-pressure generator and low-pressure generator, the Heater module is used to simulate the evaporator and condenser, the HeatX and Heater modules are used to simulate the other heat exchanging equipment in the system, the Mixer module is used to simulate the absorber, the Valve module is used to simulate the pressure reducing valve, and the Pump module is used to simulate the solution pump. The refrigeration capacity is controlled by adjusting the flow rates of the absorber and condensate.

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Heat Exchangers

The proposed coal gasification gas-heat-electricity-cooling multi-energy flow cogeneration system includes several heat exchangers, all of which are counter-flow shell and tube types. The heat recovered from these exchangers is calculated by Equation (1): 1$Q_{Exh}=m_{Exh}\times (h_{Exh-in}-h_{Exh-out}).$where $Q_{Exh}$ represents the heat recovered by the heat exchanger, in kW; $m_{Exh}$ is the mass flow rate of the heating medium, in kg/s; $h_{Exh-in}$ is the enthalpy of the heating medium at the inlet, in kJ/kg; $h_{Exh-out}$ is the enthalpy of the heating medium at the outlet, in kJ/kg.

The total heat transfer coefficient of the heat exchanger is calculated by Equation (2): 2$\mathit{k}\mathit{=}1\mathit{/}\left(\frac{1}{{\mathit{h}}_{\mathit{0}}}\mathit{+}\frac{1}{{\mathit{h}}_{\mathit{i}}}\mathit{+}\frac{\mathit{\delta }}{\mathit{\lambda }}\right),$where $k$ is the total heat transfer coefficient of the heat exchanger, in $\mathrm{kW}/({\mathrm{m}}^2·\mathrm{K})$; $h_0$ is the convective heat transfer coefficient of the external fluid, in $\mathrm{kW}/({\mathrm{m}}^2·\mathrm{K})$; $h_i$ is the convective heat transfer coefficient of the internal fluid, in $\mathrm{kW}/({\mathrm{m}}^2·\mathrm{K})$; $\delta$ is the thickness of the heat exchanger pipes, m; $\lambda$ is the thermal conductivity of the heat exchanger pipes, in $\mathrm{kW}/(\mathrm{m}·\mathrm{K})$.

Thus, the heat transfer area of the heat exchanger can be calculated by Equation (3): 3$\mathit{A}\mathit{=}\frac{{\mathit{Q}}_{\mathit{E}\mathit{x}\mathit{h}}}{\mathit{k}\times \Delta \mathit{T}},$where $\mathit{A}$ represents the heat transfer area of the heat exchanger, in m²; $\Delta \mathit{T}$ is the temperature difference between the internal and external fluids, in K.

Model Validation

The accuracy of gasifier simulation results plays a critical role in the overall system performance. Based on experimental data from references [35, 36], the reliability of the proposed model is validated as follows: (1) under specified operating pressure and temperature conditions [35], the main components of the raw syngas produced by the gasifier are verified, as summarized in Tables 2, and (2) the performance parameters of the gasifier are validated against experimental conditions provided in reference [36], with detailed results listed in Table 3.

Table 2 Comparison of simulation results and literature [35] for main components of crude syngas (mol%).

Components	Simulation results	Values from literature	Relative error	Components	Simulation results	Values from literature	Relative error
CO	41.2	38.4	7.29%	CO2	11.4	12.6	11.90%
H2	26.9	28.6	5.94%	H2O	18.7	17.4	7.47%

Table 3 Model prediction and measured data [36] for performance parameters.

Items	α	β	Gasifier temperature (K)	Cold gas efficiency	Carbon conversion
Measured	62.5%	1.13	1623	80.6%	95.0%
Prediction	1652	74.5%	91.3%
Relative error	—	—	1.78%	7.57%	3.89%

As discussed in reference [35], under specified operational parameters (operating pressure P = 4.1 MPa and temperature T = 1644.0 K), the molar concentrations of the primary components of the crude synthesis gas from the simulation (CO, H₂, CO₂, and H₂O) were compared to the results measured in the gasifier reported in the same reference [35], as detailed in Table 2. The table indicates that CO and H₂O were overestimated, whereas H₂ and CO₂ were underestimated, with CO and H₂O exceeding the experimental values by 7.29% and 7.47%, respectively, and H₂ and CO₂ falling below by 5.94% and 11.90%. This might be attributed to neglecting the wall heat losses of the gasifier in the simulation. Nonetheless, the simulation results are fundamentally consistent with the documented values. Although discrepancies exist, they are within an acceptable range, affirming the reliability of the model established in this study.

Based on the discussion in reference [36], the experimentally measured oxygen-to-carbon (β) ratio and concentration of coal-water slurry (α) are 1.13% and 62.5%, respectively, which are adopted identically in the simulation. As shown in Table 3, the gasifier temperature is overpredicted, while the cold gas efficiency and carbon conversion rate are underpredicted. Specifically, the simulated gasifier temperature exceeds the experimental value by 1.78%, whereas the cold gas efficiency and carbon conversion rate are 7.57% and 3.89% lower than their experimental counterparts, respectively. These discrepancies may arise from two factors: (1) the neglect of gasifier wall heat loss in the simulation, and (2) the omission of the catalytic effect of coal ash on carbon conversion during modeling. It is noteworthy that low-quality coal was utilized in reference [36], whereas high-quality coal is employed in the present study, resulting in significant deviations between the values in Tables 2 and 3 and those in Figure 8. In summary, the reliability of the proposed model is confirmed through the aforementioned analysis.

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The Impact of Operational Parameters on System Performance

In system operations, several operational parameters play crucial roles, with the concentration of the coal-water slurry (α) and the oxygen-to-coal ratio (β) in the gasifier being particularly critical [36, 37]. These parameters significantly affect system performance. To deepen our understanding of how the concentration of α and β impact system operations, a sensitivity analysis based on the previously established production process was performed. This analysis focused on: (1) The influence of α and β on syngas temperature, composition, calorific value, and cold gas efficiency, conducted under constant gasification pressure. (2) The effects of α and β on the system's energy load distribution, maintaining a fixed energy distribution ratio. During this analysis, all other system parameters were held constant, with the main operational parameters outlined in Table 4, referencing both literature and actual equipment operation data.

Table 4 Main operating parameters of the system.

Index	Parameters	Value	Index	Parameters	Value
1	Coal powder flow rate, kg/s	10.0	13	Distribution rate of waste gas heating flow	0.40
2	Gasification pressure, MPa	4.4	14	Inlet temperature of refrigeration unit refrigerant water, °C	25.0
3	Exit temperature of air separation unit (ASU), °C	110.0	15	Outlet temperature of refrigeration unit refrigerant water, °C	12.0
4	Exit pressure of air separation unit (ASU), MPa	4.0	16	Inlet temperature of refrigeration unit cooling water, °C	5.0
5	Exit temperature of quench cooler (QC), °C	380.0	17	Outlet temperature of refrigeration unit cooling water, °C	25.0
6	Inlet temperature of gas turbine, °C	15.0	18	Temperature of dual refrigeration unit high-pressure generator, °C	36.0
7	Inlet pressure of gas turbine, MPa	4.5	19	Pressure of refrigeration unit high-pressure generator, kPa	140.0
8	Outlet pressure of air compressor, MPa	1.6	20	Temperature of refrigeration unit low-pressure generator, °C	90.0
9	Isentropic efficiency of air compressor, %	88.0	21	Pressure of refrigeration unit low-pressure generator, kPa	90.0
10	Mechanical efficiency of air compressor, %	99.0	22	Water temperature at inlet of Flue Gas-Water Heat Exchanger (HEATX), °C	8.0
11	Efficiency of solution transport pump, %	99.0	23	Water temperature at outlet of Flue Gas-Water Heat Exchanger (HEATX), °C	15.0
12	Distribution rate of municipal gas flow	0.20	24	Exhaust gas temperature, °C	120.0

The Primary Parameters Involved In the Sensitivity Analysis

• 1.

  Concentration of coal-water slurry 4$\alpha =\frac{M_{\text{coal}}}{M_{\text{water}}+M_{\text{coal}}}\times 100\%,$where $\alpha$ is concentration of coal-water slurry (%), $M_{\text{coal}}$ is quality of coal in coal-water slurry (kg/m³), $M_{\text{water}}$ is quality of water in coal-water slurry (kg/m³).

• 2.

  Oxygen-to-coal ratio 5$\beta =\frac{M_{\mathrm{O}}}{M_C},$where β is oxygen coal ratio, $M_{\mathrm{O}}$ is quantity of oxygen atoms contained within the air supplied to the gasifier per unit time (mol/s), $M_{\mathrm{c}}$ is quantity of carbon atoms contained within the air supplied to the gasifier per unit time (mol/s).

• 3.

  Low heating value of syngas 6$LH{V}_{\text{sygas}}\mathit{=}\sum _{i=1}^n{x}_i{Q}_i,$where $LH{V}_{\text{sygas}}$ is low heating value of syngas (MJ/m³), $x_i$ is molar fraction of component i in synthesis gas, $Q_i$ is low heating value of component i in synthesis gas (MJ/m³).

• 4.

  Cold gas efficiency 7${\eta }_{\text{GET}}=\frac{E_{\text{syngas}}}{E_{\text{coal}}}\times 100\%,$where ${\eta }_{\text{GET}}$ is cold gas efficiency (%), $E_{\text{syngas}}$ is chemical energy of crude synthesis gas produced by the gasifier per unit time (MW), $E_{\text{coal}}$ is chemical energy of coal entering the gasifier per unit time (MW).

• 5.

  Molar fraction of components 8$x_i=\frac{G_i}{G_{\text{all}}},$where $x_i$ is molar fraction of components, $G_i$ is productivity of component i in syngas (mol/s), $G_{\text{all}}$ is productivity of syngas (mol/s).

• 6.

  Outputs of various energy loads in the systems

The energy outputs of the system include electrical, municipal gas, heating thermal, and cooling loads. In calculating the thermal and cooling loads among the various energy outputs, the ambient temperature is set at 25°C, with the enthalpy of the medium at this temperature defined as zero. When the medium's temperature exceeds this value, the system discharges thermal energy through the medium. When it is below, the system releases cooling energy.

The Influence of α and β on the Operating Parameters of Gasifiers

The concentration of coal-water slurry (α) and the oxygen-to-coal ratio (β) are highly flexible and adjustable parameters that significantly influence the operation of systems, particularly gasifiers. In this study, the gasifier operates at a set pressure of 4.4 MPa, making the operating temperature a critical parameter that depends on α and β [36, 37]. Figure 8a demonstrates the effect of α and β on the gasifier's operating temperature. The diagram shows that as α and β values increase, the gasifier's temperature gradually rises. For instance, at α = 50% and β = 0.95, the temperature reaches only 905.85°C, but at α = 70% and β = 1.15, it escalates to 1922.95°C. Operationally, determining the gasifier's temperature requires considering multiple factors. For energy conservation, operating at lower temperatures is preferable. However, primary gasification reactions necessitating significant heat absorption. If the temperature is too low, reactions slow down markedly or may not proceed. Additionally, the system employs a Texaco coal-water slurry gasifier, a type of fluidized bed gasifier, which necessitates consideration of liquid slag removal. Thus, a sufficiently high temperature is essential for the gasifier. However, for safety, the operating temperature must not exceed the furnace's refractory material's maximum temperature limit. Considering these factors, the gasifier's operating temperature should ideally range from 1200°C to 1600°C.

Figure 8b–d illustrate the impacts of α and β on the molar concentrations of H₂, CO, and CO₂ in synthesis gas. It is evident from the figures that with increasing α and β values, the molar concentration of H₂ in the synthesis gas linearly decreases (Figure 8b), while CO and CO₂ exhibit different trends (Figure 8c,d). At lower α values, as the β values increase, the molar concentrations of both CO and CO₂ gradually rise, but the variation in CO's concentration curve is considerably smoother than that of CO₂. At higher α values, increasing β values lead to a gradual decrease in the molar concentrations of CO and CO₂, with CO's concentration curve being smoother than that of CO₂. In summary, numerous reactions take place in the gasifier, predominantly reversible ones. The rates of these reactions are influenced by several factors, including furnace temperature, pressure, and composition. Consequently, the final composition of the synthesis gas is the result of the combined effects of these reactions. In terms of overall system operation, our primary concern should be the output quantities of electricity, municipal gas, heat, and cooling energy that the system can provide. Therefore, more attention should be directed towards the yield and calorific value of the synthesis gas rather than any individual component.

Figure 8e illustrates the effects of α and β on cold gas efficiency. As shown, when α is low, the efficiency of cold gas exhibits different trends as β increases, compared to when α is high. At lower α levels, the efficiency initially rises with an increasing β before dropping, peaking at a certain value. As α increases, the trend line depicting the changes in cold gas efficiency with respect to the β flattens into a gradually declining slope. This reveals that at lower α values (α < 60%), an unsuitable β will decrease cold gas efficiency, whereas at higher α values (α > 60%), lowering β values can yield better efficiency. In summary, maintaining a constant β value while increasing α enhances cold gas efficiency.

Figure 8f illustrates the effects of α and β on the lower heating value of syngas. The curve in Figure 8f exhibits a similar pattern to that shown in Figure 8e. With a low α value, the lower heating value of syngas first increases and then decreases with increasing β values, reaching a peak. As α value increases, the curve depicting cold gas efficiency versus β values evolves into a steadily declining line. However, this trend is significantly weaker compared to that in Figure 8d.

It should be noted that, in addition to the significant influence of α and β on gasifier operation, other factors such as pressure fluctuations, catalysts, and impurities in coal, particularly catalysts, also substantially affect gasifier performance [14, 15]. However, due to limitations of the simulation platform, these aspects were not investigated in this study.

The Impact of α and β on the Output Energy Load of the System

Figure 9a–d illustrate α and β on the energy load outputs of the system. Figure 9a details the effects on electrical load, while Figure 9b,c focus on cooling and heating loads, respectively. The trend lines in these figures are similar, closely matching those seen in Figure 8e. At lower α values, the output loads for electricity, heat, and cooling initially rise with increasing β values and then decline, reaching a peak. At higher α values, these loads decrease as the β values increases, showing a negative correlation. Figure 9d describes the impact on municipal gas loads, which is distinctly different from that in Figure 9a–c. At lower α values, the municipal gas load curve rises with increasing β values, positively correlated. At higher α values, it falls, showing a negative correlation. An integrated analysis of these graphs in Figure 9 indicates that with constant input parameters (notably the primary energy supply of coal powder), tweaking α and β values can effectively modulate outputs of electricity, heating, cooling, and municipal gas loads, thus enhancing the system's flexibility in response.

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Thermodynamic Performance Analysis of the System

As outlined earlier, the Texaco water-coal slurry gasification furnace requires not only high cold gas efficiency and substantial calorific value from the gas produced but also necessitates maintaining a suitable operating temperature for effective liquid slag removal. Operating experience dictates that the gasifier's temperature must exceed the ash fusion point of the utilized coal by at least 50°C. With the ash fusion point recorded at 1290.5°C for the coal employed in this study, the operational temperature was established at 1350°C. This setting aligns with a water-coal slurry concentration of α = 65% and an oxygen to carbon ratio β = 1.05, as depicted in Figure 8a. These parameters were identified as critical for system operation. Additionally, the energy consumption for oxygen production via air separation was noted at 810.0 kJ/kg, and for the coal powder preparation at 13.0 kJ/kg, with the gasifier's thermal losses accounting for 1% of the input coal's lower heat value. Other operational parameters are detailed in Table 4. Following these specifications, the system was subjected to a simulation. Postoperation, a thermodynamic performance analysis emphasized the comprehensive efficiency of primary energy utilization and the exergy destruction in critical system components.

Evaluation Indicators

• 1.

  Comprehensive utilization efficiency of primary energy

  The comprehensive utilization efficiency of primary energy is established based on the first law of thermodynamics and is defined as the ratio of the system's total output energy to its primary energy input [38, 39]. This total output energy includes the net electricity generation load, heating load, cooling load, and municipal gas load. The input of primary energy refers to the energy inherent in raw coal. The comprehensive utilization efficiency of primary energy is derived from Formula: 9$\eta =\frac{E+N+Q+G-H}{Q_{\mathrm{G}}}\times 100\%,$where $\eta$ is the comprehensive utilization efficiency of primary energy; $E$ is net power generation load, kW; $N$ is cooling load, kW; $Q$ is heating load, kW; $G$ is municipal gas load, kW; $H$ represents the total power consumption load of the system, which encompasses the energy required for the operation of various components, including compressed air, air separation devices, solution pumps, coal powder preparation and transportation, kW, and $Q_{\mathrm{G}}$ represents the total input of primary energy (coke oven gas or natural gas) into the system, kW. Meanwhile, $Q_{\mathrm{G}}$ can be represented as: 10$Q_{\mathrm{G}}=m_{\mathrm{G}}\times LHV,$where $m_{\mathrm{G}}$ is the mass flow rate of coal input by the system, kg/s; $h_{\text{out}}$ is the low heating value of coal, MJ/kg.

• 2.

  Exergy efficiency and exergy destruction of the system

  The exergy analysis is based on the second law of thermodynamics. The exergy of a material flow is comprised of four components: physical exergy, chemical exergy, kinetic exergy and potential exergy [40, 41]. These can be expressed as follows: 11$Ex=E{x}_{\text{ch}}+E{x}_{\mathrm{ph}}+E{x}_{\text{ki}}+E{x}_{\text{po}},$where $E{x}_{\text{ch}}$, $E{x}_{\text{ph}}$, $E{x}_{\text{ki}}$ and $E{x}_{\text{po}}$ are the chemical exergy, physical exergy, kinetic exergy and potential exergy of the material flow, kW. The steady state material flows, kinetic energy, and potential exergy are numerically very low compared to chemical exergy and physical exergy, so they are neglected in this study. Therefore, the value of energy (physical energy) of the material flow in the system, except coal, can be expressed as: 12$E{x}_{\mathrm{ph}}=m\times [h_{\text{in}}-h_{\text{out}}-T_0(s_{\text{in}}-s_{\text{out}}\left)\right],$where $E{x}_{\text{ph}}$ is the exergy of material flow, kW; $m$ is the mass flow rate, kg/s; $m$, $h_{\text{out}}$ are the specific enthalpy of import and export, respectively, kJ/kg, and $s_{\text{in}}$, $s_{\text{out}}$ are the specific entropy of import and export, respectively, kJ/(kg K).

  The physical exergy of the fuel coal is very numerically very low compared to the chemical exergy, so it is neglected in this study, and its chemical exergy can be expressed as: 13$E{x}_{\text{ch}}=m_{\mathrm{G}}\times LHV=Q_G,$where $E{x}_{\text{ch}}$ is the chemical exergy of the fuel coal, kW

  The system's exergy efficiency is calculated by: 14$\lambda =\frac{E{x}_{\mathrm{P},\text{tot}}}{E{x}_{\mathrm{G}}}\times 100\%,$where $E{x}_{\mathrm{P},\text{tot}}$ is the total output exergy of the system (includes cooling, heating, electricity, and municipal gas.), kW; $E{x}_{\mathrm{G}}$ is the exergy of the coal input to the system, kW.

  Under the condition of ignoring the physical exergy of coal, there is: 15$E{x}_{\mathrm{G}}\approx E{x}_{\text{ch}}.$

  The exergy destruction of a system or equipment can be expressed as: 16$E{x}_{\mathrm{d}}=E{x}_{\text{in}}-E{x}_{\text{out}},$where $E{x}_{\mathrm{d}}$ is the exergy loss of a system or equipment in an irreversible process, kW; $E{x}_{\text{in}}$ is input exergy to a system or device, kW, and $E{x}_{\text{out}}$ is output exergy to a system or device, kW.

• 3.

  Exergy destruction and exergy efficiency of the main functional units

  In addition to the overall system exergy analysis, this paper conducts exergy analyses on five main functional units within the system. These units include the coal-water slurry preparation and gasification unit, the syngas purification unit, the gas turbine power generation unit, the double-effect LiBr absorption chiller unit, and the flue gas-water heat exchanger unit. The analysis focuses on the exergy destruction and efficiencies of each functional unit.

  • 1.

    The coal-water slurry preparation and gasification unit 17$\Delta E{x}_{\text{gasi}}=E{x}_{{\mathrm{H}}_2\mathrm{O}}+E{x}_{coal}+E{x}_{\text{W1}}+E{x}_{{\mathrm{O}}_2}-E{x}_{\mathrm{A}},$ 18${\eta }_{\text{gasi}}=\frac{1-\Delta E{x}_{\text{gasi}}}{E{x}_{{\mathrm{H}}_2\mathrm{O}}+E{x}_{coal}+E{x}_{\text{W1}}+E{x}_{{\mathrm{O}}_2}}\times 100\%,$where $\Delta E{x}_{\text{gasi}}$ is exergy destruction of the coal-water slurry preparation and coal gasification unit, $\mathrm{kW;} E{x}_{{\mathrm{H}}_2\mathrm{O}},$$E{x}_{coal}$, $E{x}_{\text{W1}}$, $E{x}_{{\mathrm{O}}_2}$, and $E{x}_{\mathrm{A}}$ are exergy of each material flow involved in the calculation, kW; ${\eta }_{\text{gasi}}$ represents the exergy efficiency of the coal-water slurry preparation and coal gasification unit.

  • 2.

    The syngas cleaning unit 19$\Delta E{x}_{\text{clean}}=E{x}_{\mathrm{B}}-E{x}_{\mathrm{C}},$ 20${\eta }_{\text{clean}}=\frac{1-E{x}_{\text{clean}}}{E{x}_{\mathrm{B}}}\times 100\%,$where $\Delta E{x}_{\text{clean}}$ represents the exergy destruction of the syngas purification unit, in kW; $E{x}_{\mathrm{B}}$ and $E{x}_{\mathrm{C}}$ represent the exergy of the streams (B) and (C), respectively, in kW. ${\eta }_{\text{clean}}$ represents exergy efficiency of the syngas cleaning unit.

  • 3.

    The gas turbine power generation unit 21$\Delta E{x}_{\text{GT}}=\left(E{x}_{\text{AIR}}+E{x}_{\mathrm{D}}\right)-\left(E{x}_{\mathrm{W}}+E{x}_{\text{EX}}\right),$ 22${\eta }_{\text{GT}}=\frac{1-E{x}_{\text{GT}}}{E{x}_{\text{AIR}}+E{x}_{\mathrm{D}}}\times 100\%,$where $\Delta E{x}_{\text{GT}}$ represents the exergy destruction of the gas turbine power generation unit, in kW; $E{x}_{\text{AIR}}$, $E{x}_{\mathrm{D}}$, $E{x}_{\mathrm{W}}$, and $E{x}_{\text{EX}}$ represent the exergy of each material flow involved in the calculation respectively, in kW. ${\eta }_{\text{GT}}$ is the exergy efficiency of the gas turbine power generation unit.

  • 4.

    The double effect LiBr absorption refrigeration unit 23$E{x}_{\text{LiBr}}=\left(E{x}_{\text{EX4}}-E{x}_{\text{EX5}}\right)-\left(E{x}_{17}-E{x}_{16}\right),$where $E{x}_{\text{LiBr}}$ represents the exergy destruction of the double-effect LiBr absorption chiller unit, in kW; $E{x}_{\text{EX4}}$, $E{x}_{\text{EX5}}$, $E{x}_{17}$, and $E{x}_{16}$ represent the exergy of each material flow involved in the calculation, respectively, in kW. ${\eta }_{\text{LiBr}}$ is exergy efficiency of the double effect LiBr absorption refrigeration system.

  • 5.

    The flue gas-water heat exchanger unit

    24${\eta }_{\text{HEATX}}=\left(E{x}_{\text{EX2}}-E{x}_{\text{EX3}}\right)-\left(E{x}_{\text{HW}}-E{x}_{\text{CW}}\right),$ 25${\eta }_{\text{HEATX}}=\frac{1-E{x}_{\text{HEATX}}}{E{x}_{\text{EX2}}-E{x}_{\text{EX3}}}\times 100\%,$where $E{x}_{\text{HEATX}}$ is exergy loss of flue gas-water heat exchanger unit, kW; $E{x}_{\text{EX2}}$, $E{x}_{\text{EX3}}$, $E{x}_{\text{EX3}}$, and $E{x}_{\text{CW}}$ are the exergy of each material flow involved in the calculation, kW; ${\eta }_{\text{HEATX}}$ is exergy efficiency of the flue gas-water heat exchanger unit.

Assessment Results

The analysis of the system's operational results indicates that the electrical, cooling, heating, and municipal gas load capacities are 50.94, 55.78, 40.84, and 37.28 MW, respectively. The cooling coefficient of the double-effect LiBr absorption chiller unit is 1.37. The overall electricity generation efficiency, net electricity generation efficiency, cooling efficiency, heating efficiency, and gas supply efficiency are 21.91%, 19.50%, 19.97%, 14.62%, and 13.35%, respectively. The comprehensive utilization efficiency of primary energy has reached 66.18%, and the system's exergy efficiency is 34.43%.

Figures 10 and 11 depict the exergy destruction and efficiency for the five primary subsystems under designated operational conditions. The syngas purification unit achieves the highest exergy efficiency at 95.72% and the lowest exergy destruction at 0.09 MW. This efficiency is primarily due to the non-involvement of combustible gases in chemical reactions and minimal temperature changes during the purification process. The coal-water slurry preparation and gasification units exhibit an exergy efficiency of 69.72% and suffer the system's highest exergy destruction at 86.70 MW, mainly attributed to thermodynamic irreversibility during coal conversion. The gas turbine operates with an exergy efficiency of 67.44% and an exergy destruction of 46.03 MW, while the smoke exchanger records the lowest efficiency at 9.53 and an exergy destruction of 22.03 MW.

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Conclusion

This study proposes a coal-fueled electricity-gas-heating-cooling polygeneration system based on China's energy consumption profile characterized by abundant coal resources but relatively scarce oil and natural gas reserves. The system is designed, simulated, and analyzed in detail using the Aspen Plus 9.0 platform. First, the modeling process and methodology for key units—including coal-water slurry preparation, coal gasification, syngas purification, and multi-energy output—are comprehensively described. The reliability of the model is validated through comparisons with data from relevant literature. Subsequently, sensitivity and thermodynamic analyses are conducted. The results demonstrate that the system exhibits outstanding performance in terms of primary energy utilization efficiency and exergy efficiency, with high energy conversion efficiency and practical applicability. The system not only enables efficient coal utilization and reduced pollutant emissions but also achieves energy cascade utilization through multi-energy co-supply, minimizing energy transmission losses. It provides a novel pathway for comprehensive coal utilization in coal-rich nations, offering significant practical implications for advancing clean and efficient coal use and achieving energy conservation and emission reduction goals.

The sensitivity analysis reveals that coal-water slurry concentration and oxygen-to-coal ratio are critical parameters influencing system performance, significantly affecting gasifier operating temperature, syngas composition, calorific value, cold gas efficiency, and system output loads (electricity, heating, cooling, and municipal gas). Key findings include:

• 1.

  Gasifier temperature: Increasing coal-water slurry concentration and oxygen-to-coal ratio elevates gasifier operating temperature. At a slurry concentration of 65% and oxygen-to-coal ratio of 1.05, the temperature reaches 1350°C, meeting slag-tapping requirements while balancing energy efficiency and operational safety.

• 2.

  Syngas composition: Lower slurry concentrations and optimized oxygen-to-coal ratios enhance syngas calorific value and cold gas efficiency by increasing H₂ and CO molar fractions while reducing CO₂.

• 3.

  System flexibility: Adjusting slurry concentration and oxygen-to-coal ratio allows modulation of electricity, heating, cooling, and municipal gas outputs, enhancing system adaptability.

• 4.

  Optimal performance: At 65% slurry concentration and an oxygen-to-coal ratio of 1.05, the system achieves superior output levels across all energy vectors.

Thermodynamic analysis indicates high energy conversion efficiency under selected conditions, with a primary energy utilization efficiency of 66.18% and an exergy efficiency of 34.43%. Detailed results are as follows:

• 1.

  Output loads: Electricity (50.94 MW), cooling (55.78 MW), heating (40.84 MW), and municipal gas (37.28 MW). Corresponding efficiencies include power generation (21.91% gross, 19.50% net), cooling (19.97%), heating (14.62%), and gas supply (13.35%).

• 2.

  Exergy destruction: Exergy destructions are concentrated in the coal-water slurry preparation and gasification units (86.70 MW) and the gas turbine power generation unit (46.03 MW). The syngas purification unit exhibits the highest exergy efficiency (95.72%), while the flue gas heat exchanger has the lowest (9.53%) due to irreversibility in heat transfer. The double-effect LiBr absorption chiller incurs relatively low exergy destruction, benefiting from its high coefficient of performance.

Acknowledgements

This study is supported by the National Key Research and Development Program of China (No. 2017YFA0700300).

References

Z. Kong, X. Dong, Q. Jiang, et al., “Prospect of China's Synthetic Natural Gas From Coal Gasification Technology Under Consideration of Economic, Environmental, and Security Factors,” Clean Technologies and Environmental Policy 23 (2021): 1821–1835, https://doi.org/10.1007/s10098-021-02069-0.

F. Xu, S. Wang, X. Yuan, and R. Kong, “Effects of Nonionic Collectors With Oxygen‐Containing Functional Groups on Flotation Performance of Low‐Rank Coal,” Fuel 330 (2022): 125585, https://doi.org/10.1016/j.fuel.2022.125585.

S. V. Syrodoy, G. V. Kuznetsov, N. Y. Gutareva, and V. V. Salomatov, “The Efficiency of Heat Transfer Through the Ash Deposits on the Heat Exchange Surfaces by Burning Coal and Coal‐Water Fuels,” Journal of the Energy Institute 91, no. 6 (2018): 1091–1101, https://doi.org/10.1016/j.joei.2017.06.014.

M. E. Munawer, “Human Health and Environmental Impacts of Coal Combustion and Post‐Combustion Wastes,” Journal of Sustainable Mining 17, no. 2 (2018): 87–96, https://doi.org/10.1016/j.jsm.2017.12.007.

S. Wang and R. Kong, “Analyzing the Flotation Kinetics of Long‐Flame Coal Slurry Using Water‐Soluble Emulsified Collector Mixtures,” Fuel 360 (2024): 130572, https://doi.org/10.1016/j.fuel.2023.130572.

K. O. Yoro and M. O. Daramola, “CO2 Emission Sources, Greenhouse Gases, and the Global Warming Effect,” Advances in Carbon Capture, ed. M. R. Rahimpour, M. Farsi, and M. A. Makarem (Woodhead Publishing, 2020), 3–28, https://doi.org/10.1016/B978-0-12-819657-1.00001-3.

W. Chen and R. Xu, “Clean Coal Technology Development in China,” Energy Policy 38, no. 5 (2010): 2123–2130, https://doi.org/10.1016/j.enpol.2009.06.003.

K. Liu, Z. Cui, and T. H. Fletcher, “Coal Gasification,” in Hydrogen and Syngas Production and Purification Technologies, ed. K. Liu, C. Song, and V. Subramani (Wiley, 2009), 156–218, https://doi.org/10.1002/9780470561256.ch4.

T. Hasegawa, M. Sato, and T. Nakata, “A Study of Combustion Characteristics of Gasified Coal Fuel,” Journal of Engineering for Gas Turbines and Power 123, no. 1 (2000): 22–32, https://doi.org/10.1115/1.1287586.

G. J. Stiegel and R. C. Maxwell, “Gasification Technologies: The Path to Clean, Affordable Energy in the 21st Century,” Fuel Processing Technology 71, no. 1–3 (2001): 79–97, https://doi.org/10.1016/S0378-3820(01)00138-2.

F. Emun, M. Gadalla, T. Majozi, and D. Boer, “Integrated Gasification Combined Cycle (IGCC) Process Simulation and Optimization,” Computers & Chemical Engineering 34, no. 3 (2010): 331–338, https://doi.org/10.1016/j.compchemeng.2009.04.007.

P. J. Mago and A. D. Smith, “Combined Cooling, Heating, and Power (CCHP) Systems,” in Handbook of Clean Energy Systems, ed. J. Yan (Wiley, 2015), 1–15, https://doi.org/10.1002/9781118991978.hces109.

R. Salem, A. Bahadori‐Jahromi, A. Mylona, P. Godfrey, and D. Cook, “Comparison and Evaluation of the Potential Energy, Carbon Emissions, and Financial Impacts From the Incorporation of CHP and CCHP Systems in Existing UK Hotel Buildings,” Energies 11, no. 5 (2018): 1219, https://doi.org/10.3390/en11051219.

R. Kong, S. Wang, and D. Gui, “Effects of Microemulsion Collector Mixtures on the Flotation Performance of Low‐Rank Coal: A Combined Simulation and Experimental Study,” Advanced Powder Technology 35, no. 2 (2024): 104334, https://doi.org/10.1016/j.apt.2024.104334.

S. Wang, Y. Wang, and R. Kong, “New Insights Into the Interaction Between Low‐Rank Coal Particles and Clay Minerals and Its Role in Flotation Responses,” Particuology 94 (2024): 48–58, https://doi.org/10.1016/j.partic.2024.07.018.

S. Karellas, K. D. Panopoulos, G. Panousis, A. Rigas, J. Karl, and E. Kakaras, “An Evaluation of Substitute Natural Gas Production From Different Coal Gasification Processes Based on Modeling,” Energy 45, no. 1 (2012): 183–194, https://doi.org/10.1016/j.energy.2012.03.075.

B. Yan, S. Xue, Y. Li, J. Duan, and M. Zeng, “Gas‐Fired Combined Cooling, Heating and Power (CCHP) in Beijing: A Techno‐Economic Analysis,” Renewable and Sustainable Energy Reviews 63 (2016): 118–131, https://doi.org/10.1016/j.rser.2016.05.036.

G. Atesok, F. Boylu, A. A. Sirkeci, and H. Dincer, “The Effect of Coal Properties on the Viscosity of Coal–Water Slurries,” Fuel 81, no. 14 (2002): 1855–1858, https://doi.org/10.1016/S0016-2361(02)00107-2.

N. J. Wagner, M. Coertzen, R. H. Matjie, and J. C. van Dyk, “Coal Gasification,” in Applied Coal Petrology, ed. I. Suárez‐Ruiz and J. C. Crelling (Elsevier, 2008), 119–144, https://doi.org/10.1016/B978-0-08-045051-3.00005-1.

P. Roque Díaz, Y. R. Benito, and J. A. R. Parise, “Thermoeconomic Assessment of a Multi‐Engine, Multi‐Heat‐Pump CCHP (Combined Cooling, Heating and Power Generation) System: A Case Study,” Energy 35, no. 9 (2010): 3540–3550, https://doi.org/10.1016/j.energy.2010.04.002.

Y. Dong, X. Jiang, Z. Liang, and J. Yuan, “Coal Power Flexibility, Energy Efficiency, and Pollutant Emissions Implications in China: A Plant‐Level Analysis Based on Case Units,” Resources, Conservation and Recycling 134 (2018): 184–195, https://doi.org/10.1016/j.resconrec.2018.03.012.

A. S. Makarov, S. D. Boruk, A. I. Egurnov, T. N. Dimitryuk, and R. E. Klishchenko, “Utilization of Industrial Wastewater in Production of Coal‐Water Fuel,” Journal of Water Chemistry and Technology 36 (2014): 180–183, https://doi.org/10.3103/S1063455X14040055.

S. M. Nyambura, C. Li, J. Xu, et al., “Techno‐Economic Assessment of Co‐Pyrolyzed Kitchen Waste and Rice Straw for Co‐Generation of Heat and Power,” Sustainable Production and Consumption 42 (2023): 434–445, https://doi.org/10.1016/j.spc.2023.06.015.

J. Liu, J. Zhao, S. Gu, and X. Fu, “The Effect of Wet‐Grinding on Coal Mechanochemical Pre‐Desulfurization,” Energy Sources, Part A: Recovery, Utilization, and Environmental Effects 45, no. 2 (2023): 4432–4445, https://doi.org/10.1080/15567036.2023.2198985.

V. İncili, G. Karaca Dolgun, A. Keçebaş, and T. Ural, “Energy and Exergy Analyses of a Coal‐Fired Micro‐CHP System Coupled Engine as a Domestic Solution,” Energy 274 (2023): 127400, https://doi.org/10.1016/j.energy.2023.127400.

T. Xu, J. Chen, Y. Wu, X. Gao, and S. Bhattacharya, “Syngas Production From Two‐Step CO2 Gasification of Low‐Rank Coal in an Entrained Flow Reactor,” Journal of the Energy Institute 103 (2022): 169–176, https://doi.org/10.1016/j.joei.2022.06.004.

Y. Zhang, L. Wan, J. Guan, Q. A. Xiong, S. Zhang, and X. Jin, “A Review on Biomass Gasification: Effect of Main Parameters on Char Generation and Reaction,” Energy & Fuels 34, no. 11 (2020): 13438–13455, https://doi.org/10.1021/acs.energyfuels.0c02900.

S. Begum, M. Rasul, D. Akbar, and D. Cork, “An Experimental and Numerical Investigation of Fluidized Bed Gasification of Solid Waste,” Energies 7, no. 1 (2014): 43–61, https://doi.org/10.3390/en7010043.

C. Halliday and T. A. Hatton, “Sorbents for the Capture of CO2 and Other Acid Gases: A Review,” Industrial & Engineering Chemistry Research 60, no. 26 (2021): 9313–9346, https://doi.org/10.1021/acs.iecr.1c00597.

H. Li, R. Zhang, T. Wang, et al., “Simulation of H2S and CO2 Removal From IGCC Syngas by Cryogenic Distillation,” Carbon Capture Science & Technology 3 (2022): 100012, https://doi.org/10.1016/j.ccst.2021.100012.

S. Yang, L. Zhang, and D. Song, “Conceptual Design, Optimization, and Thermodynamic Analysis of a CO2 Capture Process Based on Rectisol,” Energy 244 (2022): 122566, https://doi.org/10.1016/j.energy.2021.122566.

Z. Wang, W. Han, N. Zhang, M. Liu, and H. Jin, “Proposal and Assessment of a New CCHP System Integrating Gas Turbine and Heat‐Driven Cooling/Power Cogeneration,” Energy Conversion and Management 144 (2017): 1–9, https://doi.org/10.1016/j.enconman.2017.04.043.

J. Deng, R. Z. Wang, and G. Y. Han, “A Review of Thermally Activated Cooling Technologies for Combined Cooling, Heating, and Power Systems,” Progress in Energy and Combustion Science 37, no. 2 (2011): 172–203, https://doi.org/10.1016/j.pecs.2010.05.003.

K. Talukdar and T. K. Gogoi, “Exergy Analysis of a Combined Vapor Power Cycle and Boiler Flue Gas Driven Double‐Effect Water–LiBr Absorption Refrigeration System,” Energy Conversion and Management 108 (2016): 468–477, https://doi.org/10.1016/j.enconman.2015.11.020.

L. Zheng and E. Furinsky, “Comparison of Shell, Texaco, BGL, and KRW Gasifiers as Part of IGCC Plant Computer Simulations,” Energy Conversion and Management 46, no. 11–12 (2005): 1767–1779, https://doi.org/10.1016/j.enconman.2004.09.004.

Y. Wu, J. Zhang, P. J. Smith, et al., “Three‐Dimensional Simulation for an Entrained Flow Coal Slurry Gasifier,” Energy & Fuels 24, no. 4 (2010): 1156–1163, https://doi.org/10.1021/ef901085b.

D. Li, J. Liu, S. Wang, and J. Cheng, “Study on Coal Water Slurries Prepared From Coal Chemical Wastewater and Their Industrial Application,” Applied Energy 268 (2020): 114976, https://doi.org/10.1016/j.apenergy.2020.114976.

X. Wang, C. Yang, M. Huang, and X. Ma, “Multi‐Objective Optimization of a Gas Turbine‐Based CCHP Combined With Solar and Compressed Air Energy Storage System,” Energy Conversion and Management 164 (2018): 93–101, https://doi.org/10.1016/j.enconman.2018.02.081.

W. Ma, S. Fang, and G. Liu, “Hybrid Optimization Method and Seasonal Operation Strategy for Distributed Energy System Integrating CCHP, Photovoltaic and Ground Source Heat Pump,” Energy 141 (2017): 1439–1455, https://doi.org/10.1016/j.energy.2017.11.081.

S. Kang, H. Li, L. Liu, J. Lei, and G. Zhang, “Exergy Analysis of a Novel CHP–GSHP Coupling System,” Applied Thermal Engineering 93 (2016): 308–314, https://doi.org/10.1016/j.applthermaleng.2015.09.039.

X. D. Xue, T. Zhang, X. L. Zhang, et al., “Performance Evaluation and Exergy Analysis of a Novel Combined Cooling, Heating, and Power (CCHP) System Based on Liquid Air Energy Storage,” Energy 222 (2021): 119975, https://doi.org/10.1016/j.energy.2021.119975.