Luoyang Wohong Petrochemical Equipment: Introduction to the Performance Diagnosis and Evaluation Project of Solvent Recovery Unit

After three to five years of operation, most solvent recovery devices will encounter the same problem: while the data continues to be recorded, the recovery rate is quietly declining. The decline is gradual, and those who review the records daily may not notice it until the quarterly reconciliation reveals the discrepancy. The performance diagnosis and evaluation project is to conduct a comprehensive "physical examination" for the device: use data to clarify the current situation, identify the reasons for the decline, and provide targeted suggestions for modification and adjustment, so that subsequent investments are focused on the right areas.

What content is being diagnosed

The diagnosis is conducted along three lines: the recovery effect line, which calculates the recovery rate and the correspondence between the amount of recovered liquid and the amount of solvent input, to assess the true level of the recovery section; the energy consumption line, which calculates the electricity and cooling consumption per unit of gas volume and compares it with the operational baseline, identifying the deviation to the specific unit equipment; and the status line, which verifies the pressure difference of the heat exchange surface, sealing status, and instrument accuracy item by item, to identify equipment factors affecting the effect and energy consumption. By combining and cross-verifying the data from these three lines, the true level of performance and shortcomings become apparent. Focusing solely on one line can easily lead to misjudgments.

The diagnostic criteria should first be aligned with the using unit: the statistical period should be a full year, the measurement points should be selected from a few fixed locations, and the benchmark for comparison should be the data from the commissioning acceptance or the data after the most recent overhaul. If the criteria are not aligned, the calculated differences cannot be verified, and the conclusions cannot be applied to the decision-making for transformation.

How to conduct diagnosis

Diagnosis begins with data and information: operation records, maintenance records, and historical recovery and energy consumption data are collected first, and trend curves are drawn to identify inflection points. On-site verification focuses on actual measurements - inlet gas concentration, temperature and pressure differences at each level, and condensate volume are measured point by point and compared with instrument readings. Instrument inaccuracy is a common cause of "normal data but declining performance". Sampling inspection of heat exchange surfaces is conducted to check pressure differences and scaling status, and seals and valves are inspected one by one. Actual measurements and data must be mutually corroborated for the conclusion to be valid.

What is the evaluation report for

The value of diagnosis lies in the executable conclusions. The evaluation report includes three parts: performance status evaluation, which lists the gaps between the actual level of each unit and the operational baseline item by item; a problem positioning list, which specifies the judgment basis and impact quantification for each problem, without using terms like "possibly" or "probably"; and suggestions for modification and adjustment, which are sorted by input-output - projects with low input and high return, such as instrument calibration, are listed first, while major projects, such as heat exchange modification, are accompanied by accounting basis, using numbers to speak for themselves, so that the enterprise can do the accounting itself.

Diagnostic content reference

Steps of the project

1. Data collection: archiving and trending of operation, maintenance, and energy consumption data;
2. On-site actual measurement: verify the concentration, temperature, pressure difference, and condensate volume point by point;
3. Status verification: Check the heat exchange sealing instruments one by one;
4. Analysis and positioning: Quantify and rank the impact of the problem list;
5. Report review: It is recommended to arrange the deliverables in order of input-output;
6. Follow-up review: Retest key data after rectification to verify the effectiveness.

Frequently Asked Questions

The device's operational data is all normal. Do we still need to diagnose it?

It depends on who provides the data. Both instrument inaccuracy and measurement drift can make the data "appear normal". Normal data and normal performance are two different things. One of the values of regular diagnosis is to confirm the credibility of this set of data.

Should the machine be stopped for diagnosis?

The inspection primarily focuses on actual operational status, without any downtime; a few items, such as internal inspection of the heat exchange surface, are arranged during production gaps or combined with routine maintenance. The on-site workload for the entire project usually takes two to three working days, without affecting production.

How often is an appropriate diagnosis?

For devices that have been in operation for less than three years, data tracking is the primary approach, with a comprehensive diagnosis conducted every three to five years. For older devices and those with frequently changing operating conditions, the frequency can be increased to once every two years. After each diagnosis, recommended corrections are implemented, and the effectiveness is verified in the next round of diagnosis.

This article is compiled by Luoyang Wohong Petrochemical Equipment Co., Ltd., which provides design, manufacturing, and operation and maintenance services for condensation recovery, membrane separation recovery, and complete solvent recovery equipment to chemical and pharmaceutical enterprises. If you need process evaluation or scheme configuration, please feel free to contact us for discussion.