Fix run time of adding multible connection

[AntoniaBerger]

While simulating a stage model with about 300 cstrs we observed that connecting the cstr in the configuration step took around 50x longer then the simulation. We have not done any profiling jet.
The inital guess is that solving equations in every connecting iteration is very expensive.

Here is the configuration code:

from CADETProcess.processModel import ComponentSystem, Inlet, Outlet, Cstr, FlowSheet
from CADETProcess.processModel import  LRMDiscretizationFV, Process,LRMDiscretizationDG
from CADETProcess.simulator import Cadet, SolverTimeIntegratorParameters
from CADETProcess.processModel import  LumpedRateModelWithoutPores
from CADETProcess.processModel import Langmuir
    
import math

volume = 18.2 #ml 
col_length = (volume)/((math.pi/4)*(0.08)**2)
ncol = 357

component_system = ComponentSystem(['cm']) 

LangmuirIsotherm = Langmuir(component_system, 'LangmuirIsotherm')
LangmuirIsotherm.is_kinetic = False 
LangmuirIsotherm.adsorption_rate = [0.021]
LangmuirIsotherm.desorption_rate = [1] 
LangmuirIsotherm.capacity = [2.81/0.021]

epsilonCSTR = 1-Sf


inletCSTR = Inlet(component_system,'inletCSTR')
inletCSTR.flow_rate =  0.97/60

start_time = time.time()
cstrs = dict()
for i in range(ncol):
    name = f'cstr{i}'
    cstr = Cstr(component_system, name)
    cstr.c = [0]
    cstr.V = (volume/ncol)*(epsilonCSTR)
    cstr.binding_model = LangmuirIsotherm
    cstr.porosity = 1-0.456
    cstrs[name] = cstr
end_time = time.time()
duration_create_cstr = end_time - start_time

outlet_CSTR = Outlet(component_system,'outletCSTR')

flow_sheet_CSTR = FlowSheet(component_system)

start_time = time.time()
for i in cstrs.keys():
    flow_sheet_CSTR.add_unit(cstrs[i])
end_time = time.time()
duration_addUnit = end_time - start_time

flow_sheet_CSTR.add_unit(inletCSTR)
flow_sheet_CSTR.add_unit(outlet_CSTR)

start_time = time.time()
flow_sheet_CSTR.add_connection(inletCSTR,cstrs[f'cstr{0}'])
for i in range(0,ncol-1):
    flow_sheet_CSTR.add_connection(cstrs[f'cstr{i}'],cstrs[f'cstr{i+1}'])
flow_sheet_CSTR.add_connection(cstrs[f'cstr{ncol-1}'],outlet_CSTR)
end_time = time.time()
duration_addConnection = end_time - start_time

process_CSTR = Process(flow_sheet_CSTR, 'process_CSTR')
process_CSTR.cycle_time = 50*60

_ = process_CSTR.add_event('start load LR', 'flow_sheet.inletCSTR.c', [40.0], 0)
_ = process_CSTR.add_event('stop load LR', 'flow_sheet.inletCSTR.c', [0],1/0.97*60)


process_simulator = Cadet()
process_simulator.save_to_h5(process_CSTR, 'Stage_Model.h5')

#SolverTimeIntegratorParameters.abstol = 1e-15
#SolverTimeIntegratorParameters.reltol = 1e-10
start_time = time.time()
simulation_results_CSTR = process_simulator.simulate(process_CSTR)
end_time = time.time()
duration_simulation = end_time - start_time