Distillation

Binary distillation — Skogestad's "Column A".

Action space	Box((2,)), all actions in [-1, 1]
Observation space	Box((6,))
Tracked variable(s)	yD (mole fraction)
Episode length	200 steps (12000 s at 60 s per step)
Import	from target_gym import DistillationColumn, DistillationParams
Cite as	distillation-v1

Action space

Actions are normalised to [-1, 1] and mapped onto the plant's real actuator range inside the environment.

#	meaning	min	max
0	L_raw	-1	1
1	V_raw	-1	1

Observation space

6 values. Indices (0,) carry the tracked variable(s) that the reward scores.

Rewards

Both product purities tracked, minus reboiler duty.

Every environment in this suite scores on one contract: the reward is (tracking terms, multiplied) x (1 - weighted costs), bounded in [0, 1], and reaches 1 only while the target is held exactly. See Reward shaping.

Starting state

reset samples the initial condition and the target; state has 7 fields.

Episode end

Termination. See check_is_terminal.

Truncation. After 200 steps.

Baselines

A tuned PID ships with this environment.

Arguments

parameter	default
delta_t	1
max_steps_in_episode	200
alpha	1.5
M_tray	0.5
M_drum	0.5
F	1
zF_nominal	0.5
qF	1
zF_noise_std	0.03
zF_min	0.4
zF_max	0.6
L_min	2.3
L_max	3.1
V_min	2.8
…	9 more, see the params dataclass