Economic scheduling method for cement production process considering process coupling

Abstract

The application discloses a cement production process economic scheduling method considering process coupling, and belongs to the technical field of high-energy-consumption industrial load optimization scheduling. The method comprises the following steps: acquiring production equipment, material storage, product orders, time-of-use electricity price and demand response parameters, and determining the material flow, process connection and energy consumption relationship among various production links; raw materials, intermediate products, final products, storage capacity, equipment production capacity and power consumption are characterized as resources, and production links are characterized as tasks, so that a cement production process resource-task network model is constructed; device operation, material processing, resource balance, storage quantity, process connection, continuous production, order and power consumption constraints are established based on the model; an economic scheduling model with the minimum difference between the purchase cost and the demand response income as the target is established and solved in combination with the time-of-use electricity price and the incentive demand response mechanism, so that the optimal operation plan of the cement production process is obtained. The application can take into account the production continuity, order fulfillment and power grid response, and improve the economy and executability of the scheduling scheme.

Description

Technical Field

[0001] This invention belongs to the field of high-energy-consuming industrial load optimization scheduling and industrial process modeling technology, specifically involving an economic scheduling method for cement production process that considers process coupling. Background Technology

[0002] With the continuous advancement of the construction of new power systems, and the large-scale integration of fluctuating new energy sources such as wind power and photovoltaics into the power grid, the demand for rapid, flexible, and sustainable regulation resources in the power system is constantly increasing. Demand-side industrial loads, characterized by large capacity, rapid response, and wide distribution, are crucial regulation resources supporting coordinated operation of power sources and loads.

[0003] The cement industry is a typical high-energy-consuming industry. The raw material crushing, raw meal grinding, fuel grinding and cement grinding processes have certain start-up and shutdown and peak shifting capabilities, and can participate in time-of-use electricity pricing optimization and demand response by adjusting the production sequence. However, key processes such as clinker calcination have continuous operation requirements.

[0004] Cement production is not simply a combination of several independent pieces of equipment. The crushed raw materials, raw meal, kiln feed, pulverized coal, and clinker produced in the upstream process are the inputs to the downstream process. Various intermediate materials are also subject to upper and lower limits on storage capacity, and there is a ratio coupling between kiln feed and pulverized coal in the clinker calcination process. If the scheduling model only considers electricity prices or the load of a single piece of equipment, it is easy to encounter unexecutable situations such as material shortages, exceeding inventory limits, shutdown of key equipment, or inability to fulfill product orders.

[0005] Existing cement load optimization methods have conducted extensive research on equipment-level load transfer, but they still lack a unified characterization of material flow, storage buffers, process connections, continuous production, and demand response assessment rules, making it difficult to simultaneously ensure production safety, scheduling feasibility, and electricity economy.

[0006] Therefore, an economic dispatch method is needed that can model the coupling relationship between cement production processes and the electricity market mechanism in a unified manner, so as to form an executable equipment operation and power consumption plan under the premise of meeting production constraints and order requirements. Summary of the Invention

[0007] The purpose of this invention is to provide an economic scheduling method for cement production processes that considers process coupling, in order to solve the problems of insufficient consideration of the coupling relationship of production processes, difficulty in implementing optimization results, and low economic efficiency in participating in demand response in existing methods.

[0008] To achieve the above objectives, the present invention provides an economic scheduling method for a cement production process that considers process coupling, the method comprising:

[0009] S1: Obtain the rated processing capacity and rated power of each production equipment in the cement production process, the initial inventory and upper and lower limits of storage of various materials, product order demand, time-of-use electricity price parameters and demand response parameters, and determine the material flow, process connection and energy consumption relationship between each production link;

[0010] S2: Based on the resource-task network method, raw materials, intermediate products, final products, storage capacity, equipment production capacity and power consumption in the cement production process are represented as resources, and each production link is represented as a task. A resource-task network model of cement production process considering process coupling is established.

[0011] S3: Based on the resource-task network model, establish a cement production process constraint model that includes task operation status, material processing volume, resource balance and availability, storage quantity, process connection, key continuous production, production orders and power consumption.

[0012] S4: Based on the time-of-use pricing mechanism and the incentive-based demand response mechanism, an economic dispatch model is established with the goal of minimizing the difference between electricity purchase cost and demand response revenue. The economic dispatch model is solved to obtain the optimal operation plan for the cement production process.

[0013] Furthermore, the resources include raw materials, coal, crushed raw materials, raw meal, kiln feed, pulverized coal, clinker, finished cement, production equipment, and electricity; the tasks include raw material crushing, raw meal grinding, raw meal homogenization, fuel grinding, clinker calcination, and cement grinding.

[0014] The raw materials are successively crushed, ground and homogenized to produce kiln feed; coal is ground to produce coal powder; the kiln feed and coal powder are burned together to produce clinker; the clinker is ground to produce cement products.

[0015] Furthermore, the specific expression of the cement production process constraint model is as follows.

[0016] Binary variables are used to describe the operating status of the device corresponding to the task in each scheduling period:

[0017]

[0018] In the formula, Indicates task The corresponding number The equipment during the time period It is in operation. This indicates that the equipment is in a stopped state; For the task The corresponding set of devices; For a set of tasks; This is the set of scheduling time periods.

[0019] Furthermore, the task During the period The number of operating devices and their device number boundaries are represented as follows:

[0020]

[0021]

[0022] In the formula, For the task During the period The number of operating devices; For the set of devices The number of devices in the system.

[0023] Furthermore, the task During the period The material processing capacity is expressed as:

[0024]

[0025] In the formula, For the task During the period Material handling capacity; For the first The rated processing capacity of each piece of equipment per unit time; This represents the length of the scheduling period. This expression allows different devices to have different processing capabilities for the same task.

[0026] Furthermore, the resource balance constraint is expressed as:

[0027]

[0028] In the formula, For resources During the period Available quantity; For the task Resources The generation or consumption coefficient when the task generates resources. When the task consumes resources ; and Resources During the period External input and external output quantities; by modeling input and output quantities separately, the same symbol can be used to avoid having both positive and negative meanings.

[0029] To ensure sufficient available resources before task execution, resource availability constraints are set:

[0030]

[0031] In the formula, and Resources The quantity limits are the lower limit and the quantity limit; for intermediate materials, the upper and lower limits correspond to safety stock and storage capacity, respectively.

[0032] Furthermore, to characterize the ratio coupling of kiln feed and pulverized coal in the clinker firing process, a collaborative supply constraint is set:

[0033]

[0034] In the formula, and Time periods The amount of kiln feed and pulverized coal consumed in the clinker firing process; and These are the kiln feed coefficient and pulverized coal coefficient required for producing clinker per unit of production, respectively. For clinker calcination tasks during the time period The processing capacity.

[0035] Furthermore, clinker calcination becomes a critical continuous production task, and its continuous operation constraints are expressed as follows:

[0036]

[0037]

[0038] In the formula, For clinker firing task, This refers to the set of clinker calcination equipment. The first equation indicates that the operating status of the same rotary kiln remains unchanged in adjacent time periods, meaning there is no arbitrary start-up, shutdown, or equipment rotation within the scheduling cycle. The second equation indicates that at least one rotary kiln is operating in each time period. If the production line is equipped with only one rotary kiln, the above constraints are equivalent to that rotary kiln operating in all time periods. If the scheduling cycle includes planned maintenance, the scheduling cycle can be divided into several continuous operating intervals according to the maintenance time, and the above constraints can be applied to each interval.

[0039] Furthermore, to ensure that the quantity of finished cement products available for delivery within the scheduling cycle meets order requirements, production order constraints are set:

[0040]

[0041] In the formula, It is a finished cement product; The inventory of finished cement products available for order delivery at the start of the scheduling cycle; For cement grinding tasks; The output coefficient of the cement grinding task; This represents the order demand within the scheduling cycle. The ending safety stock of finished cement products is still guaranteed by the lower limit of resource quantity.

[0042] Furthermore, cement companies during the period The power consumption is expressed as:

[0043]

[0044] In the formula, For cement companies during the period The power consumption; For auxiliary systems such as fans, conveyors, and lighting, as well as non-adjustable base load power; For the task The corresponding number The rated operating power of the equipment. If auxiliary loads are not considered separately, it can be set as follows: .

[0045] Furthermore, the electricity purchase cost under the time-of-use pricing mechanism is expressed as follows:

[0046]

[0047] In the formula, For electricity purchase costs; For time period The electricity purchase price.

[0048] Furthermore, the demand response benefit under an incentive-based demand response mechanism is expressed as:

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055] In the formula, For demand response revenue; In response to the subsidy; For assessment fees; For the set of demand response periods; For time period Demand response clearing price; , and These are the actual response capacity, the effective response capacity, and the winning bid response capacity, respectively. and These are the baseline load and the actual load, respectively. To assess the price coefficient.

[0056] Furthermore, the economic dispatch model aims to minimize the overall electricity cost.

[0057]

[0058] In the formula, The overall electricity cost is considered. The economic dispatch model is a mixed-integer linear programming model; the minimum and maximum terms in the demand response revenue expression are linearized using a piecewise linearization method, and auxiliary continuous variables, 0-1 variables, and Big M constraints are introduced for equivalent transformation, and then a mixed-integer linear programming solver is used to solve it.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] First, by using a resource-task network to uniformly characterize the main material flow, fuel supply flow, storage buffer, equipment capacity, and energy consumption, the coupling relationship of cement production processes can be transformed into a solvable scheduling constraint.

[0061] Secondly, by considering resource availability, storage quantity, coordinated supply of kiln feed and pulverized coal, continuous clinker operation, and order constraints, it is possible to reduce intermediate material shortages, inventory overruns, and unplanned shutdowns in key processes, thereby improving the production feasibility of scheduling plans.

[0062] Third, by incorporating time-of-use electricity costs, demand response subsidies, and performance evaluation fees into a unified objective, the overall electricity costs for cement enterprises can be reduced while meeting production safety and output requirements.

[0063] Fourth, the model can output time-series plans for equipment operation, material inventory, and electricity load, providing a quantitative basis for the cement industry's load participation in grid demand response. Attached Figure Description

[0064] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments or the prior art are briefly described below. Obviously, the drawings described below are only some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0065] Figure 1 A flowchart of an economic scheduling method for a cement production process considering process coupling is provided in an embodiment of the present invention;

[0066] Figure 2A schematic diagram of the cement production process provided in an embodiment of the present invention;

[0067] Figure 3 This is a schematic diagram of a resource-task network model for the cement production process provided in an embodiment of the present invention.

[0068] Figure 4 This is a schematic diagram illustrating the solution of the economic scheduling model for the cement production process provided in this embodiment of the invention. Detailed Implementation

[0069] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be understood that the described embodiments are only for illustrating the present invention and are not intended to limit the scope of protection of the present invention. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0070] This embodiment provides an economic scheduling method for a cement production process that considers process coupling. See also... Figure 1 The method includes steps S1 to S4.

[0071] Specifically, in step S1, basic data of the production line is collected. The basic data includes the number of equipment corresponding to each task, rated processing capacity, rated power and start-stop characteristics, initial inventory, safety stock and storage capacity of various materials, cement finished product orders, scheduling cycle and step size, as well as time-of-use electricity price and demand response parameters.

[0072] See Figure 2 The cement production process includes a main material flow and a fuel supply flow. The main material flows sequentially through raw material crushing, raw meal grinding, raw meal homogenization, clinker calcination, and cement grinding; coal is ground into pulverized coal and participates in clinker calcination. The main material flow and the fuel supply flow are coupled at the clinker calcination stage.

[0073] Intermediate materials are temporarily stored in silos or homogenization warehouses. Storage facilities enable some adjustable tasks to be produced earlier during periods of low electricity prices and to reduce operating load during periods of high electricity prices or demand response, but inventory must be maintained between safety stock and storage capacity.

[0074] Specifically, in step S2, see Figure 3 Raw materials, coal, crushed raw materials, raw meal, kiln feed, pulverized coal, clinker, and finished cement are set as material resources, equipment capacity and electricity are set as production resources, and raw material crushing, raw meal grinding, raw meal homogenization, fuel grinding, clinker calcination, and cement grinding are set as tasks.

[0075] Solid lines connecting resource nodes and task nodes represent the relationship between material consumption and generation, while dashed lines connecting power resources and various power-consuming tasks represent the relationship between energy consumption. This forms a resource-task network that can describe the process coupling of cement production.

[0076] Specifically, in step S3, a constraint model is constructed based on the aforementioned task operation status, material processing volume, resource balance, resource availability, storage quantity, process connection, key continuous production, production orders, and power consumption expressions.

[0077] For peak-shifting tasks such as raw material crushing, raw meal grinding, fuel grinding, and cement grinding, the number of operating equipment can be adjusted while meeting inventory and order constraints. For clinker calcination tasks, the same equipment is kept running continuously by ensuring equal status in adjacent time periods, and clinker production is ensured to be uninterrupted by ensuring that at least one piece of equipment is running. Raw meal homogenization tasks can be set to continuous operation or peak-shifting operation according to the actual equipment configuration.

[0078] Specifically, in step S4, according to Figure 4 The process shown involves inputting equipment parameters, upper and lower limits of warehousing, initial inventory, order demand, time-of-use electricity price, and demand response parameters into the model, constructing a resource-task network and constraint model, calculating electricity purchase cost and demand response revenue, and calling the solver to obtain the optimal operating plan.

[0079] In one embodiment, the scheduling cycle is set to 24 hours, and the scheduling period length is set to 1 hour. Cement production tasks and core equipment parameters can be set according to Table 1.

[0080] Table 1 Examples of Cement Production Tasks and Core Equipment Parameters

[0081] The time-of-use pricing parameters can be set according to Table 2. The prices in the table are for illustrative purposes only and should be updated according to local electricity pricing policies in actual application.

[0082] Table 2 Example of Time-of-Use Electricity Pricing Parameters for Industrial Users

[0083] When solving the model, the resource-task network is first initialized based on the initial inventory and equipment status; then the processing volume of each task and the power consumption of each time period are calculated using binary running state variables; the material inventory is then updated through the resource balance equation, and storage, allocation, continuous production and order constraints are checked; finally, the electricity purchase cost, demand response subsidy and assessment fee are calculated.

[0084] In one embodiment, for the min and max operations in the demand response expression, auxiliary continuous variables such as effective response capacity, excess response capacity, and insufficient response capacity are set respectively, and 0-1 variables representing the segmented intervals are set. Equivalent linearization is performed by combining upper and lower bound constraints and big M constraints, so that the entire model can be solved by a mixed integer linear programming solver.

[0085] When peak or high electricity prices are high, or when the grid issues a demand response order, the model reduces the number of operating equipment for adjustable tasks such as raw material crushing, raw material grinding, fuel grinding, and cement grinding within the limits of available inventory. When it is a low-price period and storage capacity allows, the model increases the number of operating equipment for adjustable tasks to produce intermediate materials or finished cement products in advance.

[0086] In clinker calcination, the same rotary kiln maintains the same operating status in adjacent time periods, and at least one rotary kiln is operating in any given time period. The inventory and coordinated supply constraints of kiln feed and pulverized coal ensure that the clinker calcination task still has sufficient and appropriately proportioned input materials during load adjustments, thereby avoiding interruptions in critical production processes due to upstream peak shifting.

[0087] The final output includes the hourly operating status of each task, hourly material inventory, hourly power consumption, actual response capacity and effective response capacity during the demand response period, as well as electricity purchase cost, demand response revenue, and overall electricity cost. These outputs can serve as the basis for cement companies to formulate production plans and execute electricity consumption plans.

[0088] It should be noted that, in this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, system, apparatus, or medium that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, system, apparatus, or medium.

[0089] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An economic scheduling method for a cement production process considering process coupling, characterized in that, Includes the following steps: S1: Obtain the rated processing capacity and rated power of each production equipment in the cement production process, the initial inventory and upper and lower limits of storage of various materials, product order demand, time-of-use electricity price parameters and demand response parameters, and determine the material flow, process connection and energy consumption relationship between each production link; S2: Based on the resource-task network method, raw materials, intermediate products, final products, storage capacity, equipment production capacity and power consumption in the cement production process are represented as resources, and each production link is represented as a task. A resource-task network model of cement production process considering process coupling is established. S3: Based on the resource-task network model, establish a cement production process constraint model that includes task operation status, material processing volume, resource balance and availability, storage quantity, process connection, key continuous production, production orders and power consumption. S4: Based on the time-of-use pricing mechanism and the incentive-based demand response mechanism, an economic dispatch model is established with the goal of minimizing the difference between electricity purchase cost and demand response revenue. The economic dispatch model is solved to obtain the optimal operation plan for the cement production process.

2. The economic scheduling method for a cement production process considering process coupling according to claim 1, characterized in that, The resources include raw materials, coal, crushed raw materials, raw meal, kiln feed, pulverized coal, clinker, finished cement, production equipment, and electricity; the tasks include raw material crushing, raw meal grinding, raw meal homogenization, fuel grinding, clinker firing, and cement grinding; wherein, the raw materials are sequentially crushed, ground, and homogenized to produce kiln feed, the coal is ground to produce pulverized coal, the kiln feed and pulverized coal are fired together to produce clinker, and the clinker is ground to produce finished cement.

3. The economic scheduling method for cement production process according to claim 1, characterized in that, The task operation status and material handling volume meet the following requirements: ； ； ； In the formula, For the task The corresponding number The time period of the equipment It is in operation; For the task The corresponding set of devices; The number of devices in the device set; For the task During the period The number of operating devices; For the task During the period Material handling capacity; For the first The rated processing capacity of each device per unit time; This represents the length of the scheduling period.

4. The economic scheduling method for a cement production process considering process coupling according to claim 1, characterized in that, Resource balance, resource availability, and storage quantity are satisfied: ； ； ； In the formula, For resources During the period Available quantity; For the task Resources The generation or consumption coefficient; and Resources During the period External input and external output; To consume resources The task set; and Resources The lower limit and upper limit of the quantity.

5. The economic scheduling method for a cement production process considering process coupling according to claim 1, characterized in that, The process integration constraints, critical continuous production constraints, and production order requirements respectively satisfy: ； ； ； ； In the formula, and The clinker calcination task is divided into time periods. The amount of kiln feed and pulverized coal consumed; and These are the kiln feed coefficient and pulverized coal coefficient required per unit of clinker, respectively. The processing capacity for clinker calcination tasks; For clinker calcination task; The first continuous production formula means that the operating status of the same clinker calcining equipment remains unchanged in adjacent time periods, and the second continuous production formula means that at least one of the equipment is operating in any time period. It is a finished cement product. For cement grinding tasks, This represents the cement product output coefficient. This represents the order demand within the scheduling period.

6. The economic scheduling method for a cement production process considering process coupling according to claim 1, characterized in that, cement companies during the period The power consumption meets the following requirements: ； In the formula, For cement companies during the period The power consumption; For auxiliary systems and non-adjustable base load power; For the task The corresponding number The rated operating power of the equipment.

7. The economic scheduling method for a cement production process considering process coupling according to claim 1, characterized in that, The electricity purchase cost under the time-of-use pricing mechanism satisfies: ； In the formula, For electricity purchase costs; For time period The electricity purchase price.

8. The economic scheduling method for a cement production process considering process coupling according to claim 7, characterized in that, The demand response benefits under the incentive-based demand response mechanism satisfy: ； ； ； ； ； ； In the formula, For demand response revenue; In response to the subsidy; For assessment fees; For the set of demand response periods; Clearing prices for demand response; , and These are the actual response capacity, the effective response capacity, and the winning bid response capacity, respectively. and These are the baseline load and the actual load, respectively. To assess the price coefficient.

9. An economic scheduling method for a cement production process considering process coupling, as described in claim 8, is characterized in that, The objective function and output of the economic scheduling model satisfy the following: ； The optimal operation plan includes at least the operating status of each production task in each time period, the inventory quantity of various resources in each time period, the power consumption of the cement enterprise in each time period, the demand response capacity, the electricity purchase cost, the demand response revenue, and the comprehensive electricity cost.

10. An economic scheduling method for a cement production process considering process coupling according to claim 9, characterized in that, The economic scheduling model is a mixed-integer linear programming model. The minimum and maximum terms in the demand response revenue expression are linearized using a piecewise linearization method. Auxiliary continuous variables and 0-1 variables are introduced for equivalent transformation, and a mixed-integer linear programming solver is used to solve the problem.

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