Practical Case of Heating Project in a Hebei Auto Parts Factory

Winter in northern China is long and extremely cold, with the minimum temperature ranging from -20℃ to -35℃. For large factories without conventional central heating (such as machinery manufacturing, auto parts, and electronic factories), workshop heating and equipment insulation are core requirements for winter production. Traditional boiler heating solutions generally have problems such as “constant temperature operation, inaccurate temperature control, and excessive energy consumption” — regardless of whether the workshop temperature meets the standard, the boiler operates at full load continuously, resulting in serious waste of electrical energy. Meanwhile, low temperatures in northern winters are prone to causing boiler pipeline freezing and cracking, as well as control system failure, which affects production continuity.

To address this pain point, we have created an energy-saving boiler solution with Siemens PLC as the core control unit. Through the “temperature contact linkage start-stop” logic, it achieves precise temperature control of “stop when reaching the standard, start when the temperature is low”. At the same time, it strengthens the cold resistance adaptation design of the boiler system, which not only ensures stable workshop temperature but also reduces heating power consumption costs by more than 30%. It perfectly meets the winter heating needs of large factories in northern China. Below, combined with the practical case of a Hebei auto parts factory, we will detail the in-depth adaptation logic and implementation effect of the solution.

Core Pain Points of Winter Heating in Northern Chinese Factories and Product Adaptation Logic

1. Pain Point: Severe Winter Cold (-25℃~-10℃) + No Conventional Heating → Adaptation Design: Cold-Resistant Boiler Body + Anti-Freezing Protection

Extremely low temperatures in northern winters are prone to causing boiler pipeline freezing and cracking, as well as combustion system icing. The ordinary materials and sealing structures of traditional boilers cannot resist severe cold, and failures are likely to occur during startup.

Product Adaptation Plan:

Boiler Body: Adopt Q345R low-temperature resistant boiler steel, with a wall thickness increased by 2mm compared to conventional products. The pipelines are made of 304 stainless steel, which has excellent low-temperature impact resistance (can withstand -40℃ without brittle fracture).

Anti-Freezing Protection: The outer layer of the pipeline is wrapped with a 50mm thick polyurethane insulation layer + aluminum foil protective cover. Key nodes (valves, pumps) are equipped with electric heat tracing belts (power 20W/m, automatically start when the temperature is below 5℃). A drain valve is designed at the bottom of the boiler to drain the water in the pipeline during long-term shutdown to avoid freezing and cracking.

Startup Optimization: Equipped with a low-temperature startup preheating module. Before startup, the combustion system and pipelines are preheated (heated to 10℃) to avoid component damage caused by direct startup at low temperatures.

Product Adaptation Plan:

Core Control Unit: Select Siemens S7-1200 series PLC (supports MODBUS TCP communication protocol), combined with Siemens TP700 touch screen, providing a visual operation interface for easy parameter setting and status monitoring.

Multi-Point Temperature Collection: Install 4-8 PT100 platinum resistance temperature sensors (temperature measurement accuracy ±0.5℃) in different areas of the workshop (work area, equipment area, corners) to collect ambient temperature in real time and avoid single-point temperature measurement blind spots.

Start-Stop Linkage Logic: Preset “start temperature contact” (e.g., 16℃) and “stop temperature contact” (e.g., 22℃) — when all sensors detect that the temperature is below 16℃, the PLC sends a start command, and the boiler automatically ignites and operates; when the temperature rises to 22℃, the PLC triggers a stop signal, and the boiler shuts down for heat preservation; if the temperature in a local area is below 18℃, the PLC only starts the heat dissipation terminal (such as a heater) in the corresponding area to avoid energy waste caused by overall restart.

Energy-Saving Optimization: The PLC has a built-in “peak-valley electricity price adaptation module”, which can set the valley electricity period (e.g., 23:00-7:00) to prioritize high-load operation and store heat; during the peak electricity period (e.g., 8:00-22:00), it only starts and stops on demand to further reduce electricity costs.

3. Pain Point: Large Space in Large Factories → Uneven Temperature → Adaptation Design: Zoned Heating + Intelligent Heat Dissipation Regulation

Large factory workshops have a large span (20-50 meters) and high floor height (8-15 meters). The single heating mode of traditional boilers is prone to causing “overheating at the near end and overcooling at the far end”, which affects the comfort of the production environment.

Product Adaptation Plan:

Zoned Heating Design: Divide the workshop into 3-5 independent heating zones. Each zone is equipped with an independent circulating pump and heat dissipation terminal (radiator/heater), which are independently controlled by Siemens PLC for start-stop and power regulation.

Intelligent Heat Dissipation Regulation: According to the production needs of different zones (e.g., 20℃ required for the equipment area, 18℃ required for the storage area), preset differentiated temperature thresholds in the PLC to achieve precise regulation of “one temperature per zone”.

Hot Air Circulation Optimization: Install circulating fans on the top of the workshop (controlled by PLC linkage). When the temperature difference between the upper and lower parts of the zone exceeds 3℃, the fans automatically start to promote hot air circulation and balance the indoor temperature.

Product Adaptation Plan:

Remote Monitoring Function: The Siemens PLC is connected to the factory local area network, supporting remote viewing of boiler operation status (temperature, pressure, energy consumption), start-stop records, and fault information on computers and mobile phone APPs without on-site duty.

Intelligent Fault Early Warning: The PLC real-time monitors key parameters such as boiler water level, pressure, and combustion status. When problems such as “low water level”, “abnormal pressure”, and “sensor failure” occur, it immediately triggers an acousto-optic alarm and pushes information to the manager’s mobile phone, while automatically executing safety protection actions (such as shutdown, pressure relief).

Maintenance Reminder Function: Preset maintenance cycles such as filter cleaning and pipeline inspection. After the expiration, the PLC automatically reminds to avoid efficiency reduction and faults caused by untimely maintenance.

5. Pain Point: High Requirements for Environmental Compliance → Adaptation Design: Low-Nitrogen Combustion + Exhaust Gas Treatment

Northern China has strict environmental requirements for industrial boilers. Nitrogen oxide emissions must comply with the GB 13271-2014 standard (≤30mg/m³). Traditional boilers are prone to exceeding the standard and facing penalties.

Product Adaptation Plan:

Low-Nitrogen Combustion System: Adopt a fully premixed low-nitrogen burner (nitrogen oxide emission ≤25mg/m³), combined with Siemens PLC to precisely control the air-fuel ratio (optimal ratio of 1:15), improve combustion efficiency (≥95%), and reduce pollutant emissions.

Exhaust Gas Treatment Optimization: Equipped with a ceramic honeycomb denitrification device and a high-efficiency dust collector to further reduce the content of nitrogen oxides and particulate matter in the exhaust gas and ensure environmental compliance.

Environmental Data Monitoring: The PLC real-time collects combustion efficiency and exhaust gas emission data, and automatically generates environmental reports for inspection by environmental protection departments.

Practical Case: Heating Project of a Hebei Auto Parts Factory (In-Depth Zoned Adaptation)

Project Background

A large Hebei auto parts factory covers an area of 30,000㎡, with a workshop area of 18,000㎡ (divided into 4 zones: stamping workshop, welding workshop, assembly workshop, and storage area). It has no central heating in winter and needs to meet the heating needs of 800 employees’ work areas and the insulation needs of production equipment (precision machine tools, welding robots). The core pain points of the project are:

The minimum winter temperature in the local area is -22℃, and traditional boilers have experienced pipeline freezing and cracking problems.

The original heating plan used ordinary electric boilers, which operated at constant temperature 24 hours a day, with monthly electricity bills exceeding 200,000 yuan and excessive energy consumption.

The workshop has a span of 35 meters and a floor height of 12 meters. The original plan had uneven temperature (25℃ at the near end and 15℃ at the far end), affecting production efficiency.

It needs to comply with Hebei Province’s environmental protection requirements, with nitrogen oxide emissions ≤30mg/m³.

Zoned Adaptation Plan and Implementation Details

Scenario 1: Stamping Workshop (4,500㎡, High Heat Dissipation Scenario)

Scenario Pain Points: The equipment generates a lot of heat during operation, but the temperature drops rapidly after shutdown at night in winter (3℃ per hour). It is necessary to ensure that the ambient temperature is ≥15℃ when the equipment starts to avoid freezing and blocking of the hydraulic system.

Customized Product Adaptation:

Boiler Configuration: 2 units of 1.2MW electric boilers (one for use and one for standby), combined with Siemens S7-1200 PLC main controller.

Temperature Control Logic: Preset “start temperature 15℃, stop temperature 18℃”. After shutdown at night, the PLC monitors the temperature every hour. If it is below 15℃, the boiler automatically starts and stops immediately after heating to 18℃ to avoid continuous operation.

Anti-Freezing Enhancement: The power of the electric heat tracing belt for pipelines around the equipment is upgraded to 30W/m. The PLC linkage monitors the pipeline temperature to ensure it is ≥5℃.

Energy-Saving Optimization: Utilize the waste heat generated during equipment operation, and the PLC automatically reduces the boiler operating power to only supplement the heat dissipation gap.

Scenario 2: Welding Workshop (5,000㎡, High Temperature Demand Scenario)

Scenario Pain Points: Welding operations require employees to stay for a long time, and the ambient temperature needs to be stably maintained at 20-22℃. In addition, the smoke and dust generated by welding need to be discharged, resulting in rapid heat loss.

Customized Product Adaptation:

Boiler Configuration: 1 unit of 1.5MW electric boiler, with 6 temperature sensors installed in zones to cover all corners of the workshop.

Temperature Control Logic: The PLC sets “start temperature 19℃, stop temperature 22℃”. When any sensor detects that the temperature is below 19℃, it starts the heater in the corresponding area. When the overall temperature is below 18℃, the boiler starts.

Hot Air Circulation: Install 8 top circulating fans, which are linked with temperature sensors by PLC. They automatically start when the temperature difference between the upper and lower parts exceeds 2℃ to balance the temperature.

Linked Ventilation: The PLC is linked with the workshop ventilation system. When ventilating, it automatically increases the boiler operating power to supplement heat loss.

Scenario 3: Assembly Workshop (5,500㎡, Precision Temperature Control Scenario)

Scenario Pain Points: Assembling precision components requires the ambient temperature to be stably maintained at 20±1℃. Excessive temperature fluctuations will affect the fitting accuracy of the components.

Customized Product Adaptation:

Boiler Configuration: 1 unit of 1.2MW electric boiler, equipped with 8 high-precision PT100 sensors (temperature measurement accuracy ±0.3℃).

Temperature Control Logic: The Siemens PLC adopts the “PID constant temperature regulation algorithm”. When the temperature is close to 20℃, it automatically reduces the boiler power (from 100% to 30%) to avoid overheating; when the temperature is below 19.5℃, it gradually increases the power to ensure the temperature fluctuation is ≤±0.5℃.

Insulation Enhancement: Install sealing strips on the workshop doors and windows, and perform insulation treatment on the walls and roof to reduce heat loss and lower the boiler start-stop frequency.

Scenario 4: Storage Area (3,000㎡, Low Energy Consumption Scenario)

Scenario Pain Points: It only needs to ensure that the goods do not freeze, and the ambient temperature ≥10℃ is sufficient. No high temperature is required, and extreme energy saving is pursued.

Customized Product Adaptation:

Boiler Configuration: Share the standby boiler (1.2MW) of the stamping workshop, with independent circulating pipelines and control modules.

Temperature Control Logic: The PLC sets “start temperature 10℃, stop temperature 12℃”. It only starts 2-3 times a day during the low-temperature period at night, with a single operation of 1-2 hours.

Energy-Saving Optimization: Prioritize starting the boiler during the valley electricity period (23:00-7:00) to store heat. During the day, the temperature is only maintained by the insulation layer, which greatly reduces energy consumption during the peak electricity period.

Implementation Effect and Customer Feedback

Since the project was put into operation for one heating season (150 days), the temperature in each zone has been stably up to standard, and the energy-saving effect is remarkable. The specific performance is as follows:

Temperature Control Precision: The temperature fluctuation in each workshop is ≤±1℃, and the temperature in the assembly workshop is stably maintained at 20±0.5℃, meeting the production process requirements.

Power Saving Effect: The monthly electricity bill has been reduced from the original 200,000 yuan to 130,000 yuan, saving 1.05 million yuan in electricity per season, with a power saving rate of 35%.

Cold Resistance Performance: When the extreme low temperature in winter is -22℃, there is no freezing and cracking of boiler pipelines, and the startup success rate is 100%.

Environmental Compliance: The measured nitrogen oxide emission is ≤22mg/m³, which meets Hebei Province’s environmental protection standards and has no penalty risk.

Convenient Maintenance: Remote monitoring covers the entire system, and fault early warning is timely. Only 2 routine maintenances were performed during the entire heating season, and no heating interruption occurred.

Feedback from the customer’s production and operation department: “The boiler solution controlled by Siemens PLC has accurately solved our heating pain points. The temperature is stable, energy consumption has been greatly reduced, and remote monitoring makes maintenance more worry-free. We saved more than 1 million yuan in electricity bills in one heating season, and the investment return period is only 14 months, which completely exceeds expectations.”

Summary: Adaptation Principles of Energy-Saving Boilers for Northern Factories

To achieve “precision temperature control + power saving and consumption reduction” for factories in severe cold northern regions, the core is “Siemens PLC linkage control + scenario-based customized design”:

High Heat Dissipation/Equipment Insulation Scenarios (Stamping Workshop, Machinery Workshop): Prioritize the “one for use and one for standby” boiler configuration. The PLC sets a low start temperature threshold, implements intermittent start-stop at night, and strengthens pipeline anti-freezing.

Personnel-Intensive/High Temperature Demand Scenarios (Welding Workshop, Assembly Workshop): Adopt zoned heating + hot air circulation. The PLC precisely controls temperature fluctuations and links auxiliary equipment (ventilation, heaters) to reduce energy consumption.

Low Demand Scenarios (Storage Area, Office Area): Share the standby boiler, store energy during the valley electricity period, and the PLC sets a wide temperature range to maximize energy saving.

General Principles: With Siemens PLC as the core, combined with multi-point high-precision temperature measurement, remote monitoring, and fault early warning functions, while strengthening the cold resistance performance and environmental protection adaptation of the boiler body, balancing stability, energy saving, and compliance.

If you are a factory in northern China without conventional central heating (machinery manufacturing, electronics, auto parts and other industries) and need a customized winter heating solution, please feel free to contact us — we will provide a full-process service of “Siemens PLC control scheme + boiler selection + installation and commissioning + operation and maintenance training” according to the factory area, workshop zoning, temperature requirements, and energy consumption budget to help you achieve the core goals of “temperature up to standard, energy saving and consumption reduction, and stable operation”.