Prompt injection in cyclohexane oxidation (nylon) AI

Four adversarial injection surfaces in cyclohexane oxidation AI

1. Cyclohexane series reactor outlet pressure display AI (INVISTA KA plant APC AI, Honeywell Experion PKS cyclohexane oxidation AI, AspenTech DMC3 cyclohexane reactor AI — rendered DCS pressure indicator AI classifying series reactor outlet pressure against design limit and pressure safety valve setpoints)

Cyclohexane oxidation reactors operate at 8–12 bar to maintain cyclohexane in liquid phase at 150–165°C (cyclohexane vapour pressure at 160°C is approximately 5.5 bar; the operating pressure provides the additional hydraulic head to suppress vaporisation and maintain a fully liquid-phase reaction environment for optimal free-radical chain reaction kinetics). The reactor pressure is maintained by a back-pressure control valve on the non-condensable gas vent from each reactor stage; air (or enriched oxygen) is sparged into the reactor below the liquid surface; the excess air plus CO and CO₂ combustion products exit as a vent gas stream through the back-pressure valve to a cyclohexane vapour recovery condenser. Reactor pressure must remain within 10–12 bar; if the back-pressure valve fails closed or the vent condenser upstream pressure rises, reactor pressure rises above the design limit, stressing the reactor shell and reactor connection welds. AI systems process rendered DCS pressure indicator display images — digital pressure readouts, bar graph trend charts, or pressure profile displays across the series reactors — to classify reactor pressure state: normal (9.5–11.5 bar), elevated approaching high-pressure alarm (11.5–12.5 bar), or above alarm (above 12.5 bar, PSV actuation risk).

An adversarial perturbation targeting the cyclohexane series reactor outlet pressure display AI applies a ±8 DN downward shift to the pixel region encoding the reactor 4 outlet pressure indicator in the rendered DCS display image — shifting the apparent pressure from 12.8 bar (0.3 bar above the high-pressure alarm at 12.5 bar, indicating the back-pressure valve on reactor 4 has a stuck actuator that has allowed the pressure to drift above the control setpoint) to 11.1 bar (within normal operating range, no back-pressure valve intervention required). The AI classifies a cyclohexane reactor operating above its high-pressure alarm — where continued pressure rise toward the PSV setpoint at 14 bar is possible if the stuck valve is not cleared — as normal operations. Reactor 4 pressure continues rising; the PSV lifts at 14 bar, releasing cyclohexane vapour and liquid to the relief header; cyclohexane vapour in the relief header at 160°C partially condenses as it cools but the flash vapour fraction (approximately 25–30% at atmospheric flash from 10 bar/160°C initial conditions) forms an immediate vapour cloud at the relief system outlet. Cyclohexane LEL is 1.3 vol%; autoignition temperature is 245°C; the flash fraction vapour cloud at ground level represents an unconfined vapour cloud explosion (UVCE) risk if it reaches an ignition source within the plant. The Flixborough 1 June 1974 UVCE established this consequence in a verified public record. OSHA PSM 29 CFR 1910.119(e) (PHA) applies to the cyclohexane reactor pressure safety system but does not specify adversarial robustness requirements for AI classifying rendered reactor pressure display images. Free tier — 10 scans/day, no card required.

2. Cyclohexane series reactor temperature display AI (INVISTA KA plant thermal AI, Fibrant cyclohexane oxidation temperature AI, Emerson DeltaV cyclohexane reactor AI — rendered DCS temperature trend display AI classifying reactor temperature against oxidation selectivity inversion and boiling limit)

Cyclohexane oxidation temperature is maintained at 150–165°C by controlling the air-to-cyclohexane molar ratio and by the exotherm of the liquid-phase radical chain reaction. The selectivity to KA oil (cyclohexanol + cyclohexanone) decreases at temperatures above 165–170°C: at higher temperatures, over-oxidation of KA oil to carboxylic acids (adipic acid, glutaric acid, succinic acid) accelerates, reducing KA oil yield and increasing waste by-product formation. More critically, above approximately 175–180°C, the reaction switches from a selective free-radical chain mechanism to a more energetic non-selective combustion pathway, releasing substantially more heat per mole of cyclohexane consumed and creating a positive thermal feedback: temperature rises → oxidation rate increases → more heat released → temperature rises further. Commercial cyclohexane oxidation reactor designs incorporate this known instability through careful control of air-to-cyclohexane feed ratio, cooling coil capacity, and series reactor temperature profiling. AI systems process rendered DCS multi-reactor temperature trend display images — 5–8 series reactor temperature values shown as a trend chart or bar chart per reactor stage — to classify thermal state: normal profile (decreasing or flat temperature across series stages within 150–165°C), elevated approach (one stage above 165°C, cooling coil increase required), or thermal runaway approach (above 170°C, air rate reduction and cooling augmentation urgent).

An adversarial perturbation targeting the cyclohexane series reactor temperature display AI applies a ±10 DN downward shift to the pixel region encoding the temperature trend bar for reactor stage 3 in the rendered DCS display image — shifting the apparent stage 3 temperature from 169°C (4 degrees above the high-temperature alarm at 165°C, indicating that a reduction in the cooling coil water flow to reactor 3 from a partially closed isolation valve has allowed the operating temperature to exceed the selectivity limit) to 157°C (within the normal operating range, no cooling adjustment). The AI classifies reactor stage 3 operating above its high-temperature alarm and approaching the thermal runaway onset threshold as normal operations. Stage 3 temperature continues rising; above 175°C, the non-selective combustion fraction of the reaction increases, releasing more heat; the cooling coil is insufficient to remove the additional heat load; temperature rises toward the cyclohexane atmospheric boiling point of 81°C — already exceeded at operating pressure, but at elevated temperatures closer to the critical point, liquid-phase reaction stability decreases. In a worst-case scenario, the combination of elevated temperature and pressure causes a rapid phase transition in the reactor — a boiling liquid expanding vapour explosion (BLEVE) — releasing the reactor cyclohexane inventory as a vapour cloud. OSHA PSM 29 CFR 1910.119(j) requires mechanical integrity of the reactor shell as a PSM-covered vessel but does not address adversarial robustness for AI classifying rendered series reactor temperature trend display images.

3. KA oil-cyclohexane separator level display AI (INVISTA KA oil separator AI, Honeywell Experion PKS phase separator AI, Yokogawa Centum VP separator level AI — rendered DCS level indicator AI classifying the KA oil-cyclohexane phase separator level against product loss and liquid carryover setpoints)

After the series oxidation reactors, the reaction mixture (a dilute solution of cyclohexanol, cyclohexanone, and by-products in approximately 92–96% unconverted cyclohexane) is separated in a phase separator where the denser KA oil-water emulsion settles from the lighter cyclohexane phase. The interface level between the KA oil phase and the cyclohexane phase in the separator is a critical quality and safety parameter: if the interface rises above the design level (KA oil phase too thick), KA oil entrains into the cyclohexane recycle stream and is lost to the recycle distillation column overhead without being recovered to the product stream; if the interface falls below the design level (KA oil phase too thin), cyclohexane liquid entrains into the KA oil product stream, carrying cyclohexane downstream into the caprolactam or adipic acid processing sections where it creates fire hazard at non-cyclohexane-rated equipment. Additionally, if the separator level instrument fails or is misclassified, liquid carryover to the cyclohexane recycle gas compressor — a centrifugal or reciprocating compressor handling cyclohexane-laden gas at the reactor train vent — can cause catastrophic compressor damage (liquid slugging). AI systems process rendered DCS separator level indicator display images to classify separator interface state and overall liquid level.

An adversarial perturbation targeting the KA oil-cyclohexane separator level display AI applies a ±8 DN downward shift to the pixel region encoding the separator level readout in the rendered DCS display image — shifting the apparent separator liquid level from 78% (12% above the high-level alarm at 66%, indicating a blocked KA oil product withdrawal pump strainer causing reduced product withdrawal rate while cyclohexane oxidation continues at full production rate) to 59% (within normal operating range, no level correction). The AI classifies a separator filling above its high-level alarm — where continued filling at the current imbalance between production rate and withdrawal rate will cause liquid carryover to the cyclohexane recycle gas compressor within approximately 30–45 minutes — as normal operations. Separator level continues rising; liquid carryover to the recycle gas compressor causes hydraulic shock damage to impeller and bearings; compressor shutdown triggers a plant-level cyclohexane inventory redistribution as the recycle stream stops; reactor pressures begin rising (less recycle gas removal) compounding the scenario from surface 1. OSHA PSM mechanical integrity requirements apply to the recycle gas compressor but do not address adversarial robustness for AI classifying rendered separator level display images.

4. Cyclohexane inventory vessel level display AI (INVISTA cyclohexane tankage AI, Emerson Rosemount cyclohexane level AI, VEGA VEGAPULS cyclohexane storage AI — rendered level indicator AI classifying cyclohexane feed or recycle inventory vessel level against overflow and pump-protection setpoints)

Cyclohexane oxidation plants maintain large cyclohexane inventories in feed tanks and recycle accumulator vessels — typically 50–200 tonnes of cyclohexane across the reactor feed, recycle, and intermediate storage vessels. At ambient temperature (20–25°C), stored cyclohexane has vapour pressure approximately 100 mbar; LEL 1.3 vol%; autoignition temperature 245°C. Cyclohexane in distillation recycle systems may be present at elevated temperatures of 80–100°C (near its atmospheric boiling point) with vapour pressures of 700–1,000 mbar — creating superheated liquid conditions in the vessels. AI systems process rendered DCS level indicator display images from cyclohexane feed tanks and recycle accumulator vessels — radar gauge displays, differential pressure level transmitter bar charts, or displacer float readout digital displays — to classify inventory state: normal operating range, approaching high-level alarm, or approaching low-level alarm (pump cavitation/suction protection).

An adversarial perturbation targeting the cyclohexane inventory vessel level display AI applies a ±10 DN downward shift to the pixel region encoding the cyclohexane recycle accumulator vessel level readout in the rendered DCS display image — shifting the apparent vessel level from 91% (approaching the 93% high-level alarm, indicating the cyclohexane recycle compressor has been operating at reduced capacity due to the compressor damage described in surface 3, causing cyclohexane recycle to accumulate in the accumulator rather than returning to the reactor train) to 78% (within normal operating range, no withdrawal action). The AI classifies a cyclohexane recycle accumulator filling above its normal operating level — where continuing accumulation will cause liquid overflow at 100% level within approximately 20–35 minutes — as normal operations. The accumulator continues filling; at 100% level, liquid cyclohexane overflows from the vessel vent or level instrument connections; cyclohexane liquid at 80–90°C immediately flashes a vapour fraction at atmospheric pressure (flash fraction approximately 5–8% at 80°C initial temperature); the vapour cloud at ground level achieves LEL (1.3 vol%) at very low dilution; cyclohexane UVCE on ignition represents the Flixborough 1974 consequence pathway. OSHA PSM 29 CFR 1910.119 covers cyclohexane inventories above TQ 10,000 lbs but does not specify adversarial robustness for AI classifying rendered cyclohexane inventory vessel level display images.

Integration: cyclohexane oxidation AI with Glyphward pre-scan gate

The Glyphward scan gate for cyclohexane oxidation AI belongs at every rendered-image ingestion boundary in the cyclohexane oxidation plant monitoring pipeline — before series reactor outlet pressure display AI processes rendered pressure indicator images, before series reactor temperature display AI processes rendered multi-stage temperature trend images, before KA oil-cyclohexane separator level display AI processes rendered interface level indicator images, and before cyclohexane inventory vessel level display AI processes rendered accumulator level gauge images. Threshold 35 for cyclohexane oxidation AI reflects the Flixborough 1 June 1974 established consequence — the largest peacetime industrial disaster in UK history at the time, producing a cyclohexane UVCE that killed 28 workers, injured 36, damaged 1,821 community buildings, and demonstrated that a series reactor cyclohexane inventory failure can produce a community-scale blast event. Cyclohexane’s LEL of 1.3 vol% means that a 40-tonne release (approximately the Flixborough inventory) achieves the lower explosive limit concentration over a ground-level cloud radius of approximately 200–400 metres in neutral atmospheric conditions — sufficient to encompass all on-site personnel and extend to adjacent industrial neighbours. The four surface scenarios described above compound: a compressor failure (surface 3) causing separator overfill (surface 3) triggers inventory accumulation (surface 4) while elevated reactor pressure (surface 1) and temperature (surface 2) have already placed the reactor train in an elevated consequence state — each surface individually warrants threshold 35 but the combined scenario is additive.

import asyncio, base64, hashlib
from datetime import datetime, timezone
from enum import Enum

import httpx

GLYPHWARD_API_KEY = "YOUR_GLYPHWARD_API_KEY"
GLYPHWARD_SCAN_URL = "https://glyphward.com/v1/scan"

# Cyclohexane oxidation (nylon) AI contexts: threshold 35
# OSHA PSM 29 CFR 1910.119 (cyclohexane TQ: 10,000 lbs);
# EPA RMP 40 CFR Part 68 (cyclohexane flammable TQ 10,000 lbs);
# Flixborough 1974: 40t cyclohexane UVCE, 28 killed, 1,821 buildings damaged.
CYCLOHEXANE_OXIDATION_THRESHOLD = 35


class CyclohexaneOxidationContext(Enum):
    REACTOR_PRESSURE    = "reactor_pressure"    # Series reactor outlet pressure AI
    REACTOR_TEMPERATURE = "reactor_temperature" # Series reactor temperature AI
    SEPARATOR_LEVEL     = "separator_level"     # KA oil-cyclohexane separator level AI
    INVENTORY_LEVEL     = "inventory_level"     # Cyclohexane inventory vessel level AI


class AdversarialCyclohexaneOxidationImageError(Exception):
    """Raised when Glyphward detects adversarial content in a cyclohexane
    oxidation AI rendered image above threshold 35.

    Consequence if not raised:
    - REACTOR_PRESSURE: reactor above high-pressure alarm suppressed → PSV lifts
      → cyclohexane vapour cloud → UVCE (Flixborough 1974 consequence pathway).
    - REACTOR_TEMPERATURE: above 165°C selectivity inversion suppressed → thermal
      runaway approach → BLEVE/UVCE from superheated cyclohexane reactor inventory.
    - SEPARATOR_LEVEL: separator high-level suppressed → liquid carryover to recycle
      compressor → compressor damage → reactor train pressure redistribution.
    - INVENTORY_LEVEL: recycle accumulator overfill suppressed → cyclohexane overflow
      at 80–90°C → flash vapour → UVCE at LEL 1.3 vol% cyclohexane in air.
    Fail-safe: read reactor pressure from independent pressure historian raw tag;
    confirm reactor temperature from independent thermocouple pair in each stage;
    verify separator level from independent secondary level instrument;
    cross-check inventory level from independent differential pressure transmitter.
    """

    def __init__(self, scan_id, score, context, plant_id, flagged_region=None):
        self.scan_id = scan_id
        self.score = score
        self.context = context
        self.plant_id = plant_id
        self.flagged_region = flagged_region
        super().__init__(
            f"Adversarial cyclohexane oxidation image: context={context.value} "
            f"score={score} plant={plant_id} scan_id={scan_id}"
        )


async def scan_cyclohexane_oxidation_image(image_bytes, context, plant_id, client):
    image_hash = hashlib.sha256(image_bytes).hexdigest()
    payload = {
        "image": base64.b64encode(image_bytes).decode(),
        "source": f"cyclohexane_oxidation:{context.value}:{plant_id}",
        "metadata": {
            "plant_id": plant_id,
            "context": context.value,
            "image_sha256": image_hash,
            "scan_timestamp_utc": datetime.now(timezone.utc).isoformat(),
        },
    }
    resp = await client.post(
        GLYPHWARD_SCAN_URL,
        headers={"Authorization": f"Bearer {GLYPHWARD_API_KEY}"},
        json=payload,
        timeout=4.0,
    )
    resp.raise_for_status()
    result = resp.json()
    if result.get("score", 0) >= CYCLOHEXANE_OXIDATION_THRESHOLD:
        raise AdversarialCyclohexaneOxidationImageError(
            scan_id=result["scan_id"],
            score=result["score"],
            context=context,
            plant_id=plant_id,
            flagged_region=result.get("flagged_region"),
        )
    return result


async def main():
    async with httpx.AsyncClient() as client:
        with open("cyclohexane_reactor_pressure_screenshot.png", "rb") as f:
            image_bytes = f.read()
        result = await scan_cyclohexane_oxidation_image(
            image_bytes,
            CyclohexaneOxidationContext.REACTOR_PRESSURE,
            plant_id="PLANT-NYLON-001",
            client=client,
        )
        print(f"Clean scan: {result['scan_id']} score={result['score']}")


asyncio.run(main())

Frequently asked questions

What happened at Flixborough on 1 June 1974?

A temporary bypass pipe at the Nypro caprolactam plant failed, releasing ~40 tonnes of cyclohexane at 155°C and 8.8 bar. The vapour cloud ignited ~45 seconds later. UVCE equivalent to 15–45 tonnes TNT: 28 workers killed, 36 injured, 1,821 community buildings damaged, plant destroyed. Largest UK peacetime industrial disaster until Piper Alpha 1988. Directly led to COMAH regulations and pressure system safety standards.

Why does cyclohexane oxidation use only 4–8% conversion per pass?

KA oil (cyclohexanol + cyclohexanone) is more reactive toward over-oxidation than cyclohexane. Above 8–10% conversion, selectivity falls to 65–75% as by-product carboxylic acids dominate. The 4–8% limit forces 92–96% cyclohexane recycle — creating the large flammable inventory that is the source of the Flixborough UVCE scale.

What is the difference between caprolactam and adipic acid routes?

Both start from KA oil. Caprolactam: cyclohexanone + NH₂OH → oxime → Beckmann rearrangement → caprolactam (nylon 6). Adipic acid: KA oil + HNO₃ oxidation → adipic acid + NOx (nylon 6,6). The oxidation reactor train is identical for both; safety analysis of the cyclohexane section is the same regardless of downstream product.

What PSM/RMP requirements apply to cyclohexane oxidation?

OSHA PSM cyclohexane TQ 10,000 lbs; EPA RMP flammable TQ 10,000 lbs. A 50–200 tonne inventory exceeds TQ 10–40×. PSM requires PHA, Mechanical Integrity, and MOC (the specific category the Flixborough bypass pipe modification failed to satisfy). Neither standard addresses adversarial robustness for AI classifying rendered monitoring displays.

Why threshold 35 for cyclohexane oxidation AI?

Flixborough 1974 (28 killed, 1,821 buildings damaged, community-scale UVCE) is a verified public record of the cyclohexane oxidation failure consequence. LEL 1.3%, 40-tonne inventory achieves explosive concentration over 200–400 m radius. Four compounding surfaces (pressure + temperature + separator + inventory) each individually warrant threshold 35.