Question 1: What should be done if the dew point of the biogas dryer fails to meet specifications (indicating poor dehydration performance)?

1. Core Cause

• Poor heat dissipation (accounting for 60%): Air-cooled units installed in high-temperature, enclosed spaces (>40°C), with fins clogged by dust and oil, or with damaged fans, result in elevated condensing pressures and insufficient cooling capacity.
• Drainage system malfunctions (25% of cases): clogging or failure of the automatic drain, freezing of the discharge pipe, and backflow of condensate, resulting in water that cannot be discharged and is instead carried away by biogas.
• Refrigerant and refrigeration system issues: refrigerant leakage, compressor aging, malfunction of the hot‑gas bypass valve, and inability to achieve adequate evaporator temperature.
• Mismatch between operating conditions and installation: intake airflow exceeds the equipment’s rated value, intake air temperature is greater than 45°C, and the available clearance for heat dissipation is less than 30 cm.

2. Step-by-Step Troubleshooting and Resolution

• Check cooling: Clean the condenser fins (blow them clean with compressed air); verify that the fan is operating, and replace it if damaged.
• Move to a well-ventilated area, leaving at least 50 cm of clearance on both sides and above, and avoid direct sunlight.
• Drainage check: Manually test the drain valve: Press the forced‑drain button; if no water flows, disassemble and clean the filter screen or replace the drain valve.
• In winter, ensure proper heat tracing and insulation of sewage discharge pipes to prevent freezing and blockages.
• Inspect the refrigeration system: Measure the refrigerant pressure. Refer to the equipment manual; if the pressure is abnormal, locate and repair any leaks, then recharge the refrigerant.
• Listen for compressor noise: If there is no starting sound, check the contactor and overload protector; if the compressor does not stop running, inspect the thermostat and bypass valve.
• When operating conditions exceed the rated flow, upgrade the equipment or add parallel units; install an air pre-cooler at the high-temperature inlet.

1. Main contributing factors

• Poor heat dissipation triggers high-pressure protection: fin blockage, fan failure, or high ambient temperature can cause excessive condensing pressure, activating the high-pressure protection.
• Voltage instability / Overload: Voltage < 380 V ± 5%, significant line voltage drop, compressor aging leading to cylinder seizure.
• Refrigerant abnormality: Excessive refrigerant (high high-pressure) or leakage (low low-pressure) triggers high- and low-pressure protection.
• Evaporator icing: Poor drainage and a malfunctioning bypass valve can cause ice formation, leading to a sudden increase in compressor load.

2. Quick Resolution Steps

1. Emergency shutdown reset: Power off for 15 minutes to allow cooling, then reset the circuit breaker and thermal relay; avoid frequent forced restarts.
2. Cooling system emergency response: thoroughly clean the fins, replace the faulty fan, and improve airflow for better cooling.
3. Electrical and Power Supply Inspection: Measure three-phase voltage balance, tighten wiring terminals, and promptly replace aged wiring.
4. Refrigeration system inspection: measure refrigerant pressure, detect leaks and recharge refrigerant; inspect the bypass valve, and if icing occurs, shut down the unit to defrost.
5. Load management: Avoid operating beyond capacity; during the summer, appropriately reduce the load and increase operational intervals.

1. The fundamental cause of icing

• Incomplete drainage: the automatic drain is clogged, the condensate drain pipe has an insufficient slope, and residual condensate freezes.
• Hot gas bypass failure: At low temperatures and under light load, the bypass valve fails to open, causing the evaporator temperature to drop excessively and resulting in ice formation.
• Insulation deficiency: The unit body, drain pipe, and valves are uninsulated, leading to rapid freezing and blockage in low-temperature environments.

2. Antifreeze and Thawing Plan

(1) Daily Frost Protection (Prevention First)

• Drainage Optimization: Inspect the drains daily to ensure they are free of blockages; maintain a slope of ≥5° for the discharge pipes to prevent water accumulation.
• Enable freeze‑protection mode: Open the equipment’s hot‑gas bypass valve and automatically modulate cooling capacity at low temperatures to prevent the evaporator from icing up.
• Thermal insulation retrofit: The equipment body is wrapped with thermal insulation cotton, the drain pipe is fitted with a heating cable and an additional insulation layer, and the valves are also insulated.
• Low-Temperature Operation Guidelines: When the ambient temperature is below 5°C, keep the equipment running continuously for 24 hours to prevent water from accumulating and freezing during shutdowns.

(2) Thawing after freezing (safe operating procedures)

1. Stop the machine immediately, disconnect the power supply, and do not attempt to restart it by force.
2. Natural thawing (preferred): Allow the ambient temperature to rise above 10°C, then drain any accumulated water once the ice has melted.
3. Auxiliary defrosting: Rinse the frozen area with warm water (below 40°C); do not use open flames for heating to prevent pipe deformation or leakage.
4. Post-thaw inspection: Verify there is no cracking; perform a manual drainage test, and restart the equipment once normal operation is confirmed.

1. Four Core Factors in Model Selection

• Atmospheric parameters: If the biogas contains H₂S (which is corrosive), a 304/316L stainless steel evaporator must be selected to ensure corrosion resistance; ordinary copper tubing is prone to pitting and perforation when exposed to corrosive acidic solutions.
• Handling capacity: Select equipment based on the project’s maximum gas production multiplied by a factor of 1.2 (allowing for a 20% margin) to prevent failures during full‑load operation.
• Inlet conditions: inlet temperature ≤ 45°C, pressure 0.2–0.6 MPa; for high-temperature applications, select a pre-cooling model; for low-pressure applications, choose a dedicated micro‑negative‑pressure model.
• Environment and Safety: Choose a rain- and dust-proof model for outdoor use; biogas is flammable and explosive, so the entire unit must be explosion-proof (with explosion-proof certification for electrical components).

2. Lino Biogas Refrigerated Dryer Adaptation Solution

• Small and medium-sized projects (50–500 m³/h): standard explosion-proof air-cooled model, customizable in 304 stainless steel, dew point of 2–10°C, skid-mounted design for easy installation.
• Large‑scale projects (1,000–5,000 m³/h): Customized water‑cooled design with heat recovery, reducing energy consumption by 20% and suitable for high‑flow, high‑sulfur‑content operating conditions.

1. Daily maintenance

• Check whether the equipment’s pressure, temperature, and dew point are within normal limits.
• Manually test the drain to ensure unobstructed drainage.
• Check for unusual noises, vibrations, or leaks.

2. Weekly Maintenance

• Clean the condenser fins (blow them with compressed air) to ensure efficient heat dissipation.
• Inspect the fan and motor operating conditions, and tighten any loose bolts.
• Inspect pipelines and valves for corrosion and leaks.

3. Monthly maintenance

• Verify the thermostat and pressure switch to ensure accurate parameter settings.
• Check the refrigerant pressure; if it’s low, locate and repair any leaks, then recharge the system.
• Clean the evaporator to remove scale buildup (to prevent a decline in heat exchange efficiency).

4. Annual Maintenance (Professional Personnel)

• Comprehensive disassembly and maintenance: clean the heat exchanger, replace aged seals, and lubricate moving parts.
• Electrical system inspection: replace aged wiring and verify explosion-proof components.
• Performance Calibration: Adjust dew point and pressure parameters to restore optimal operating conditions.